Ordinary mode instability associated with thermal ring distribution

Energy Technology Data Exchange (ETDEWEB)

Hadi, F.; Qamar, A. [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); Yoon, P. H. [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of)

2015-02-15

The purely growing ordinary (O) mode instability driven by excessive parallel temperature anisotropy has recently received renewed attention owing to its potential applicability to the solar wind plasma. Previous studies of O mode instability have assumed either bi-Maxwellian or counter-streaming velocity distributions. For solar wind plasma trapped in magnetic mirror-like geometry such as magnetic clouds or in the vicinity of the Earth's collisionless bow shock environment, however, the velocity distribution function may possess a loss-cone feature. The O-mode instability in such a case may be excited for cyclotron harmonics as well as the purely growing branch. The present paper investigates the O-mode instability for plasmas characterized by the parallel Maxwellian distribution and perpendicular thermal ring velocity distribution in order to understand the general stability characteristics.

High-power single-mode cw dye ring laser

Energy Technology Data Exchange (ETDEWEB)

Schroeder, H W; Stein, L; Froelich, D; Fugger, B; Welling, H [Technische Univ. Hannover (Germany, F.R.). Inst. fuer Angewandte Physik

1977-12-01

Due to spatial hole burning, standing-wave dye lasers require a large amount of selectivity inside the cavity for single-mode operation. The output power of these lasers is limited by losses caused by the frequency selecting elements. In a travelling-wave laser, on the other hand, spatial hole burning does not exist, thereby eliminating the need for high selectivity. A travelling-wave cw dye laser was realized by unidirectional operation of a ring laser, yielding single mode output powers of 1.2 W at 595 nm and of 55 mW in the UV-region with intracavity frequency doubling.

High resolution spectroscopy of jet cooled phenyl radical: The ν{sub 1} and ν{sub 2} a{sub 1} symmetry C–H stretching modes

Energy Technology Data Exchange (ETDEWEB)

Chang, Chih-Hsuan; Nesbitt, David J. [JILA, National Institute of Standards and Technology, University of Colorado, Boulder, Colorado 80309, USA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309 (United States)

2016-07-28

A series of CH stretch modes in phenyl radical (C{sub 6}H{sub 5}) has been investigated via high resolution infrared spectroscopy at sub-Doppler resolution (∼60 MHz) in a supersonic discharge slit jet expansion. Two fundamental vibrations of a{sub 1} symmetry, ν{sub 1} and ν{sub 2}, are observed and rotationally analyzed for the first time, corresponding to in-phase and out-of-phase symmetric CH stretch excitation at the ortho/meta/para and ortho/para C atoms with respect to the radical center. The ν{sub 1} and ν{sub 2} band origins are determined to be 3073.968 50(8) cm{sup −1} and 3062.264 80(7) cm{sup −1}, respectively, which both agree within 5 cm{sup −1} with theoretical anharmonic scaling predictions based on density functional B3LYP/6-311g++(3df,3dp) calculations. Integrated band strengths for each of the CH stretch bands are analyzed, with the relative intensities agreeing remarkably well with theoretical predictions. Frequency comparison with previous low resolution Ar-matrix spectroscopy [A. V. Friderichsen et al., J. Am. Chem. Soc. 123, 1977 (2001)] reveals a nearly uniform Δν ≈ + 10-12 cm{sup −1} blue shift between gas phase and Ar matrix values for ν{sub 1} and ν{sub 2}. This differs substantially from the much smaller red shift (Δν ≈ − 1 cm{sup −1}) reported for the ν{sub 19} mode, and suggests a simple physical model in terms of vibrational mode symmetry and crowding due to the matrix environment. Finally, the infrared phenyl spectra are well described by a simple asymmetric rigid rotor Hamiltonian and show no evidence for spectral congestion due to intramolecular vibrational coupling, which bodes well for high resolution studies of other ring radicals and polycyclic aromatic hydrocarbons. In summary, the combination of slit jet discharge methods with high resolution infrared lasers enables spectroscopic investigation of even highly reactive combustion and interstellar radical intermediates under gas phase, jet

Dynamics of the OH stretching mode in crystalline Ba(ClO4)2.3H2O

Science.gov (United States)

Hutzler, Daniel; Brunner, Christian; Petkov, Petko St.; Heine, Thomas; Fischer, Sighart F.; Riedle, Eberhard; Kienberger, Reinhard; Iglev, Hristo

2018-02-01

The vibrational dynamics of the OH stretching mode in Ba(ClO4)2 trihydrate are investigated by means of femtosecond infrared spectroscopy. The sample offers plane cyclic water trimers in the solid phase that feature virtually no hydrogen bond interaction between the water molecules. Selective excitation of the symmetric and asymmetric stretching leads to fast population redistribution, while simultaneous excitation yields quantum beats, which are monitored via a combination tone that dominates the overtone spectrum. The combination of steady-state and time-resolved spectroscopy with quantum chemical simulations and general theoretical considerations gives indication of various aspects of symmetry breakage. The system shows a joint population lifetime of 8 ps and a long-lived coherence between symmetric and asymmetric stretching, which decays with a time constant of 0.6 ps.

Piezoelectric Lead Zirconate Titanate (PZT) Ring Shaped Contour-Mode MEMS Resonators

Science.gov (United States)

Kasambe, P. V.; Asgaonkar, V. V.; Bangera, A. D.; Lokre, A. S.; Rathod, S. S.; Bhoir, D. V.

2018-02-01

Flexibility in setting fundamental frequency of resonator independent of its motional resistance is one of the desired criteria in micro-electromechanical (MEMS) resonator design. It is observed that ring-shaped piezoelectric contour-mode MEMS resonators satisfy this design criterion than in case of rectangular plate MEMS resonators. Also ring-shaped contour-mode piezoelectric MEMS resonator has an advantage that its fundamental frequency is defined by in-plane dimensions, but they show variation of fundamental frequency with different Platinum (Pt) thickness referred as change in ratio of fNEW /fO . This paper presents the effects of variation in geometrical parameters and change in piezoelectric material on the resonant frequencies of Platinum piezoelectric-Aluminium ring-shaped contour-mode MEMS resonators and its electrical parameters. The proposed structure with Lead Zirconate Titanate (PZT) as the piezoelectric material was observed to be a piezoelectric material with minimal change in fundamental resonant frequency due to Platinum thickness variation. This structure was also found to exhibit extremely low motional resistance of 0.03 Ω as compared to the 31-35 Ω range obtained when using AlN as the piezoelectric material. CoventorWare 10 is used for the design, simulation and corresponding analysis of resonators which is Finite Element Method (FEM) analysis and design tool for MEMS devices.

Infrared, diode laser spectroscopy of the Ar--N2O complex: Observation of the intermolecular bending mode in combination with the highest frequency intramolecular stretching mode

International Nuclear Information System (INIS)

Hu, T.A.; Chappell, E.L.; Sharpe, S.W.

1993-01-01

Rotationally resolved vibrational spectra consisting of a-type transitions have been observed for the low-frequency, intermolecular bending mode in combination with the highest frequency, intramolecular stretching mode of Ar--N 2 O. Analysis of the spectral data places the origin of the combination band at 2256.1 cm -1 while the origin of the intramolecular stretching fundamental is at 2223.9 cm -1 . The difference between these two origins is approximately 32.2 cm -1 and agrees well with our calculated frequency of 31.5 cm -1 for the intermolecular bending mode, which was obtained by analysis of the centrifugal distortion constants. In addition, argon--nitrous oxide exhibits an anomalously large inertial defect of 10.96 amu A 2 in the combination state. This indicates a breakdown in the assumption of separation between vibration and rotation. While much of the inertial defect in the ground state can be accounted for by including Coriolis interactions, that occurring in the combination state is only partially accounted for by a similar analysis. Small, but significant changes, are observed in both the radial and angular parameters for Ar--N 2 O when going from the ground to the combination state, indicating large amplitude motion. The combination band is approximately 200 times less intense than the high-frequency, stretching fundamental of Ar--N 2 O. In addition, over 400 new rovibrational transitions are assigned to the previously observed 1 0 1 intramolecular stretching fundamental of the complex, and the subsequent rotational analysis is found to be in close agreement with earlier studies. Data were taken on a newly built, rapid-scan, diode laser spectrometer that incorporates a 12 cmx200 μm pulsed slit-expansion nozzle

Guided mode resonance in planar metamaterials consisting of two ring resonators with different sizes

International Nuclear Information System (INIS)

Yu Zhen; Che Hang; Liu Jianjun; Jing Xufeng; Li Xiangjun; Hong Zhi

2017-01-01

We proposed and experimentally investigated a two-ring-resonator composed planar hybrid metamaterial (MM), in which the spectra of guided mode resonance (GMR) and Fano resonance or EIT-like response induced by coherent interaction between MM resonance and GMR can be easily controlled by the size of the two rings in the terahertz regime. Furthermore, a four-ring-resonator composed MM for polarization-insensitive GMRs was demonstrated, where GMRs of both TE and TM modes are physically attributed to the diffraction coupling by two ±45° tilting gratings. Such kind of device has great potential in ultra-sensitive label-free sensors, filters, or slow light based devices. (paper)

Mode-Locked 1.5 um Semiconductor Optical Fiber Ring

DEFF Research Database (Denmark)

Pedersen, Niels Vagn; Jakobsen, Kaj Bjarne; Vaa, Michael

1996-01-01

The dynamics of a mode-locked SOA fiber ring are investigated experimentally and numerically. Generation of near transform-limited (time-bandwidth product = 0.7) 1.5 um 54 ps FWHM pulses with a peak power of 2.8 mW at a repetition rate of 960 MHz is demonstrated experimentally. The experimental r...

Generation of picosecond pulses and frequency combs in actively mode locked external ring cavity quantum cascade lasers

International Nuclear Information System (INIS)

Wójcik, Aleksander K.; Belyanin, Alexey; Malara, Pietro; Blanchard, Romain; Mansuripur, Tobias S.; Capasso, Federico

2013-01-01

We propose a robust and reliable method of active mode locking of mid-infrared quantum cascade lasers and develop its theoretical description. Its key element is the use of an external ring cavity, which circumvents fundamental issues undermining the stability of mode locking in quantum cascade lasers. We show that active mode locking can give rise to the generation of picosecond pulses and phase-locked frequency combs containing thousands of the ring cavity modes

Mode-locking peculiarities in an all-fiber erbium-doped ring ultrashort pulse laser with a highly-nonlinear resonator

Science.gov (United States)

Dvoretskiy, Dmitriy A.; Sazonkin, Stanislav G.; Kudelin, Igor S.; Orekhov, Ilya O.; Pnev, Alexey B.; Karasik, Valeriy E.; Denisov, Lev K.

2017-12-01

Today ultrashort pulse (USP) fiber lasers are in great demand in a frequency metrology field, THz pulse spectroscopy, optical communication, quantum optics application, etc. Therefore mode-locked (ML) fiber lasers have been extensively investigated over the last decade due the number of scientific, medical and industrial applications. It should be noted, that USP fiber lasers can be treated as an ideal platform to expand future applications due to the complex ML nonlinear dynamics in a laser resonator. Up to now a series of novel ML regimes have been investigated e.g. self-similar pulses, noise-like pulses, multi-bound solitons and soliton rain generation. Recently, we have used a highly nonlinear germanosilicate fiber (with germanium oxides concentration in the core 50 mol. %) inside the resonator for more reliable and robust launching of passive mode-locking based on the nonlinear polarization evolution effect in fibers. In this work we have measured promising and stable ML regimes such as stretched pulses, soliton rain and multi-bound solitons formed in a highly-nonlinear ring laser and obtained by intracavity group velocity dispersion (GVD) variation in slightly negative region. As a result, we have obtained the low noise ultrashort pulse generation with duration 59 dB) and relative intensity noise <-101 dBc / Hz.

Coordination of {Mo142} Ring to La3+ Provides Elliptical {Mo134La10} Ring with a Variety of Coordination Modes

Directory of Open Access Journals (Sweden)

Eri Ishikawa

2009-12-01

Full Text Available A28-electron reduced C2h-Mo-blue 34Ǻ outer ring diameter circular ring, [Mo142O429H10(H2O49(CH3CO25(C2H5CO2]30- (≡{Mo142(CH3CO25(C2H5CO2} comprising eight carboxylate-coordinated (with disorder {Mo2} linkers and six defect pockets in two inner rings (four and three for each, respectively, reacts with La3+ in aqueous solutions at pH 3.5 to yield a 28-electron reduced elliptical Ci-Mo-blue ring of formula [Mo134O416H20(H2O46{La(H2O5}4{La(H2O7}4{LaCl2(H2O5}2]10- (≡{Mo134La10}, isolated as the Na10[Mo134O416H20(H2O46{La(H2O5}4{La(H2O7}4{LaCl2(H2O5}2]·144 H2O Na+ salt. The elliptical structure of {Mo134La10} showing 36 and 31 Å long and short axes for the outer ring diameters is attributed to four (A-D modes of LaO9/LaO7Cl2 tricapped-trigonal-prismatic coordination (TTP geometries. Two different LaO2(H2O7 and one LaO2(H2O2Cl2 TTP geometries (as A-C modes for each of two inner rings result from the coordination of all three defect pockets of the inner ring for {Mo142(CH3CO25(C2H5CO2}, and two LaO4(H2O5 TTP geometries (as D mode result from the displacement of two (acetate/propionate-coordinated binuclear {Mo2} linkers with La3+ in each inner ring. The isothermal titration calorimetry (ITC of the ring modification from circle to ellipsoid, showing the endothermic reaction of [La3+]/[{Mo142(CH3CO25(C2H5CO2}] = 6/1 with DH = 22 kJ×mol-1, DS = 172 J×K-1×mol-1, DG = −28 kJ×mol-1, and K = 9.9 ´ 104 M-1 at 293 K, leads to the conclusion that the coordination of the defect pockets to La3+ precedes the replacement of the {Mo2} linkers with La3+. 139La- NMR spectrometry of the coordination of {Mo142(CH3CO25(C2H5CO2} ring to La3+ is also discussed.

PF-KO system for single bunch mode operation of a storage ring

International Nuclear Information System (INIS)

Ohgaki, H.; Sugiyama, S.; Mikado, T.; Chiwaki, M.; Yamada, K.; Suzuki, R.; Sei, N.; Noguchi, T.; Yamazaki, T.

1994-01-01

A new RF-KO (RF knockout) system for the single bunch mode operation of a storage ring has been developed. The knockout signal is modulated by the sum signal of the RF acceleration frequency of the storage ring and a bunch selection signal. We do not need any special device or a timing unit with this method. We obtain a high purity of bunch structure in a short knock out time. The single bunch impurity of 0.2% has been achieved. (author)

Ultrashort Generation Regimes in the All-Fiber Kerr Mode-Locked Erbium-Doped Fiber Ring Laser for Terahertz Pulsed Spectroscopy

Directory of Open Access Journals (Sweden)

V. S. Voropaev

2015-01-01

Full Text Available Many femtosecond engineering applications require for a stable generation of ultrashort pulses. Thus, in the terahertz pulsed spectroscopy a measurement error in the refractive index is strongly dependent on the pulse duration stability with allowable variation of few femtoseconds. The aim of this work is to study the ultrashort pulses (USP regimes stability in the all – fiber erbium doped ring laser with Kerr mode-locking. The study was conducted at several different values of the total resonator intra-cavity dispersion. Three laser schemes with the intra-cavity dispersion values from -1.232 ps2 to +0.008 ps2 have been studied. In the experiment there were two regimes of generation observed: the stretched pulse generation and ordinary soliton generation. Main attention is focused on the stability of regimes under study. The most stable regime was that of the stretched pulse generation with a spectrum form of sech2 , possible pulse duration of 490 fs at least, repetition rate of 2.9 MHz, and average output power of 17 mW. It is worth noting, that obtained regimes had characteristics suitable for the successful use in the terahertz pulsed spectroscopy. The results may be useful in the following areas of science and technology: a high-precision spectroscopy, optical frequency standards, super-continuum generation, and terahertz pulsed spectroscopy. The future system development is expected to stabilize duration and repetition rate of the obtained regime of ultra-short pulse generation.

Low-emittance tuning of storage rings using normal mode beam position monitor calibration

Science.gov (United States)

Wolski, A.; Rubin, D.; Sagan, D.; Shanks, J.

2011-07-01

We describe a new technique for low-emittance tuning of electron and positron storage rings. This technique is based on calibration of the beam position monitors (BPMs) using excitation of the normal modes of the beam motion, and has benefits over conventional methods. It is relatively fast and straightforward to apply, it can be as easily applied to a large ring as to a small ring, and the tuning for low emittance becomes completely insensitive to BPM gain and alignment errors that can be difficult to determine accurately. We discuss the theory behind the technique, present some simulation results illustrating that it is highly effective and robust for low-emittance tuning, and describe the results of some initial experimental tests on the CesrTA storage ring.

5-GHz passively mode-locked quantum dot ring laser diode at 1.5 μm

NARCIS (Netherlands)

Heck, M.J.R.; Renault, A.; Bente, E.A.J.M.; Oei, Y.S.; Smit, M.K.; Eikema, K.S.E.; Ubachs, W.; Anantathanasarn, S.; Nötzel, R.

2008-01-01

In this paper we present the first observation of passive mode-locking in a quantum dot (QD) ring laser operating at wavelengths around 1.5 µm. The device consists of an 18-mm long (electrically pumped) ring cavity, corresponding to a 5-GHz roundtrip frequency. The waveguide width is 2 µm. A

Low-emittance tuning of storage rings using normal mode beam position monitor calibration

Directory of Open Access Journals (Sweden)

A. Wolski

2011-07-01

Full Text Available We describe a new technique for low-emittance tuning of electron and positron storage rings. This technique is based on calibration of the beam position monitors (BPMs using excitation of the normal modes of the beam motion, and has benefits over conventional methods. It is relatively fast and straightforward to apply, it can be as easily applied to a large ring as to a small ring, and the tuning for low emittance becomes completely insensitive to BPM gain and alignment errors that can be difficult to determine accurately. We discuss the theory behind the technique, present some simulation results illustrating that it is highly effective and robust for low-emittance tuning, and describe the results of some initial experimental tests on the CesrTA storage ring.

Pseudo-single-bunch mode for a 100 MHz storage ring serving soft X-ray timing experiments

Science.gov (United States)

Olsson, T.; Leemann, S. C.; Georgiev, G.; Paraskaki, G.

2018-06-01

At many storage rings for synchrotron light production there is demand for serving both high-flux and timing users simultaneously. Today this is most commonly achieved by operating inhomogeneous fill patterns, but this is not preferable for rings that employ passive harmonic cavities to damp instabilities and increase Touschek lifetime. For these rings, inhomogeneous fill patterns could severely reduce the effect of the harmonic cavities. It is therefore of interest to develop methods to serve high-flux and timing users simultaneously without requiring gaps in the fill pattern. One such method is pseudo-single-bunch (PSB), where one bunch in the bunch train is kicked onto another orbit by a fast stripline kicker. The light emitted from the kicked bunch can then be separated by an aperture in the beamline. Due to recent developments in fast kicker design, PSB operation in multibunch mode is within reach for rings that operate with a 100 MHz RF system, such as the MAX IV and Solaris storage rings. This paper describes machine requirements and resulting performance for such a mode at the MAX IV 1.5 GeV storage ring. A solution for serving all beamlines is discussed as well as the consequences of beamline design and operation in the soft X-ray energy range.

Measurement of resonance modes causative of beam position monitor signal noise in vacuum chamber of storage ring

Energy Technology Data Exchange (ETDEWEB)

Joo, Youngdo; Hwang, Ilmoon; Park, Sungju [Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Kim, Changbum, E-mail: chbkim@postech.ac.k [Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

2011-05-11

It is known that the position reading obtained from the beam position monitor (BPM) mounted at the storage ring can be corrupted by the resonance mode. We carried out a three dimensional finite-difference time-domain (FDTD) simulation of vacuum chambers of the storage ring of the Pohang Light Source (PLS) without simplified modeling to measure the frequencies of resonance modes excited in the vacuum chamber. The frequencies of resonance modes obtained by the eigenmode simulation are well matched with the peak frequencies of RF transmission scattering matrix (S{sub 21}) graph of sector vacuum chamber measured using a network analyzer. It is found that a transverse electric (TE) resonance mode exists in the operation frequency band of BPM and the vertically oriented electric field of TE resonance mode is linked to the BPM position reading noise. Based on this study, we can easily design a vacuum chamber free from the BPM position reading noise caused by the TE resonance mode.

Measurement of resonance modes causative of beam position monitor signal noise in vacuum chamber of storage ring

International Nuclear Information System (INIS)

Joo, Youngdo; Hwang, Ilmoon; Park, Sungju; Kim, Changbum

2011-01-01

It is known that the position reading obtained from the beam position monitor (BPM) mounted at the storage ring can be corrupted by the resonance mode. We carried out a three dimensional finite-difference time-domain (FDTD) simulation of vacuum chambers of the storage ring of the Pohang Light Source (PLS) without simplified modeling to measure the frequencies of resonance modes excited in the vacuum chamber. The frequencies of resonance modes obtained by the eigenmode simulation are well matched with the peak frequencies of RF transmission scattering matrix (S 21 ) graph of sector vacuum chamber measured using a network analyzer. It is found that a transverse electric (TE) resonance mode exists in the operation frequency band of BPM and the vertically oriented electric field of TE resonance mode is linked to the BPM position reading noise. Based on this study, we can easily design a vacuum chamber free from the BPM position reading noise caused by the TE resonance mode.

Mode-locked 1.5 micrometers semiconductor optical amplifier fiber ring

DEFF Research Database (Denmark)

Pedersen, Niels V.; Jakobsen, Kaj Bjarne; Vaa, Michael

1996-01-01

The dynamics of a mode-locked SOA fiber ring are investigated experimentally and numerically. Generation of near transform-limited (time-bandwidth product=0.7) 1.5 μm 54 ps FWHM pulses with a peak power of 2.8 mW at a repetition rate of 960 MHz is demonstrated experimentally. The experimental...... results agree well with the simulation results obtained using a transmission line laser model (TLLM) model, Both experiments and numerical simulations show how the RF power and the detuning affect the pulsewidth...

The carbon monoxide stretching modes in camphor-bound cytochrome P-450cam. The effect of solvent conditions, temperature, and pressure.

Science.gov (United States)

Schulze, H; Ristau, O; Jung, C

1994-09-15

The effect of pH, monovalent cations, glycerol, temperature, and pressure on the carbonmonoxy (CO) stretching mode of camphor-bound cytochrome P-450cam (CYP 101) was studied. Two effects, band overlap and frequency shift, have been observed. The CO stretch infrared band located at about 1940 cm-1 is asymmetric because of the overlap of three bands at about 1931 cm-1, 1939 cm-1, and 1942 cm-1 with strongly different populations. Reducing the temperature or increasing the pressure leads to splitting the band or switching the asymmetry from the lower energy side to the higher energy side of the infrared band. The overlap of several CO stretch bands indicates conformational substates within the heme pocket. A frequency shift of the predominantly populated band is observed by changing all the parameters mentioned. The pH-induced frequency shift follows an S-shape with the pK at 6.2, which matches the pK observed for the pH-induced high-spin/low-spin transition. Conformational changes on the proximal heme side are suggested to be the origin. Monovalent cations at saturating concentration induce a small frequency shift depending on the ion radius. The potassium ion is the one that induces a CO stretch frequency with the highest wave-number while sodium and lithium (smaller radii) and rubidium and caesium ion (larger radii) have diminished values, which is supporting evidence for the special function of the potassium ion within the structure. Glycerol and hydrostatic pressure induce a red shift of the CO stretching frequency. Forced contact of the polar hydroxyl group of Thr252 of the I helix induced by pressure and indirectly by glycerol is suggested to change the CO dipole moment, reflecting in the decreased CO stretching frequency.

Transient filament stretching rheometer II

DEFF Research Database (Denmark)

Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

1997-01-01

The Lagrangian sspecification is used to simulate the transient stretching filament rheometer. Simulations are performed for dilute PIB-solutions modeled as a four mode Oldroyd-B fluid and a semidilute PIB-solution modeled as a non-linear single integral equation. The simulations are compared...

A low vertical β mode for the LNLS UVX electron storage ring

International Nuclear Information System (INIS)

Lin, Liu; Tavares, P.

1991-01-01

An operation mode with low vertical betatron function in one of the long dispersion free straight sections of the LNLS UVX Electron Storage Ring is studied for applications with small gap insertions. The flexibility of this lattice is analyzed regarding two aspects: the range of variation of the vertical betatron tune and the ability to set the betatron functions to high/low values in the insertion straights

Switchable dual-wavelength single-longitudinal-mode erbium fiber laser utilizing a dual-ring scheme with a saturable absorber

Science.gov (United States)

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

2018-06-01

In this work, we propose and demonstrate a switchable dual-wavelength erbium-doped fiber (EDF) ring laser with stable single-longitudinal-mode (SLM) output. Here, a dual-ring (DR) structure with an unpumped EDF of 2 m is designed to achieve SLM oscillation. Five fiber Bragg gratings (FBGs) are applied in the laser cavity serving as the reflective element to generate different dual-wavelength outputs. In the measurement, six sets of generated dual-wavelengths with various mode-spacing (Δλ) can be achieved via the five FBGs. Additionally, the stability performance of the proposed EDF DR laser is also demonstrated.

A tuneable, power efficient and narrow single longitudinal mode fibre ring laser using an inline dual-taper fibre Mach–Zehnder filter

International Nuclear Information System (INIS)

Ahmad, H; Dernaika, M; Alimadad, M; Ibrahim, M F; Lim, K S; Harun, S W; Kharraz, O M

2014-01-01

A tuneable single longitudinal mode fibre ring laser with dual-taper fibre filter is proposed and experimentally demonstrated in this paper. The single longitudinal mode operation, and power limitations for a Mach–Zehnder interferometer filter generated from a single mode fibre, are verified for the first time. Incorporating an in-line taper fibre Mach–Zehnder interferometer filter inside the laser ring cavity causes a spatial mode beating interference, resulting in a passive narrow band filter with the ability to generate stable single longitudinal modes. The single longitudinal mode achieves a side mode suppression ratio of more than 60 dB using low pump power. The tuneability of the fibre laser ranges from 1525 to 1562 nm using a passive band pass filter. A study of the stability and limitation of the single longitudinal mode in the Mach–Zehnder tapered fibre is also presented. (paper)

A voltage-controlled ring oscillator using InP full enhancement-mode HEMT logic

Energy Technology Data Exchange (ETDEWEB)

Du Rui; Dai Yang; Chen Yanling; Yang Fuhua, E-mail: ddrr@semi.ac.c [Research Center of Semiconductor Integration, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

2009-03-15

A voltage-controlled ring oscillator (VCO) based on a full enhancement-mode InAlAs/InGaAs/InP high electron mobility transistor (HEMT) logic is proposed. An enhancement-mode HEMT (E-HEMT) is fabricated, whose threshold is demonstrated to be 10 mV. The model of the E-HEMT is established and used in the SPICE simulation of the VCO. The result proves that the full E-HEMT logic technology can be applied to the VCO. And compared with the HEMT DCFL technology, the complexity of our fabrication process is reduced and the reliability is improved.

Ring-shaped active mode-locked tunable laser using quantum-dot semiconductor optical amplifier

Science.gov (United States)

Zhang, Mingxiao; Wang, Yongjun; Liu, Xinyu

2018-03-01

In this paper, a lot of simulations has been done for ring-shaped active mode-locked lasers with quantum-dot semiconductor optical amplifier (QD-SOA). Based on the simulation model of QD-SOA, we discussed about the influence towards mode-locked waveform frequency and pulse caused by QD-SOA maximum mode peak gain, active layer loss coefficient, bias current, incident light pulse, fiber nonlinear coefficient. In the meantime, we also take the tunable performance of the laser into consideration. Results showed QD-SOA a better performance than original semiconductor optical amplifier (SOA) in recovery time, line width, and nonlinear coefficients, which makes it possible to output a locked-mode impulse that has a higher impulse power, narrower impulse width as well as the phase is more easily controlled. After a lot of simulations, this laser can realize a 20GHz better locked-mode output pulse after 200 loops, where the power is above 17.5mW, impulse width is less than 2.7ps, moreover, the tunable wavelength range is between 1540nm-1580nm.

Stretch-dependent slow force response in isolated rabbit myocardium is Na+ dependent.

Science.gov (United States)

von Lewinski, Dirk; Stumme, Burkhard; Maier, Lars S; Luers, Claus; Bers, Donald M; Pieske, Burkert

2003-03-15

Stretch induces functional and trophic effects in mammalian myocardium via various signal transduction pathways. We tested stretch signal transduction on immediate and slow force response (SFR) in rabbit myocardium. Experiments were performed in isolated right ventricular muscles from adult rabbit hearts (37 degrees C, 1 Hz stimulation rate, bicarbonate-buffer). Muscles were rapidly stretched from 88% of optimal length (L88) to near optimal length (L98) for functional analysis. The resulting immediate and slow increases in twitch force (first phase and SFR, respectively) were assessed at reduced [Na+]o or without and with blockade of stretch activated ion channels (SACs), angiotensin-II (AT1) receptors, endothelin-A (ET(A)) receptors, Na+/H+-exchange (NHE1), reverse mode Na+/Ca2+-exchange (NCX), or Na+/K+-ATPase. The effects of stretch on sarcoplasmic reticulum Ca2+-load were characterized using rapid cooling contractures (RCCs). Intracellular pH was measured in BCECF-AM loaded muscles, and action potential duration (APD) was assessed using floating electrodes. On average, force increased to 216+/-8% of the pre-stretch value during the immediate phase, followed by a further increase to 273+/-10% during the SFR (n=81). RCCs significantly increased during SFR, whereas pH and APD did not change. Neither inhibition of SACs, AT1, or ET(A) receptors affected the stretch-dependent immediate phase nor SFR. In contrast, SFR was reduced by NHE inhibition and almost completely abolished by reduced [Na+]o or inhibition of reverse-mode NCX, whereas increased SFR was seen after raising [Na+]i by Na+/K+-ATPase inhibition. The data demonstrate the existence of a delayed, Na+- and Ca2+-dependent but pH and APD independent SFR to stretch in rabbit myocardium. This inotropic response appears to be independent of autocrine/paracrine AT1 or ET(A) receptor activation, but mediated through stretch-induced activation of NHE and reverse mode NCX.

An asymmetric integrated extended cavity 20GHz mode-locked quantum well ring laser fabricated in the JePPIX technology platform

NARCIS (Netherlands)

Tahvili, M.S.; Barbarin, Y.; Ambrosius, H.P.M.M.; Smit, M.K.; Bente, E.A.J.M.; Leijtens, X.J.M.; Vries, de T.; Smalbrugge, E.; Bolk, J.

2011-01-01

In this paper, we present mode-locked operation of a monolithic 20GHz integrated extended cavity ring laser. The 4mm-long laser ring cavity incorporates a 750µm-long optical amplifier section (SOA), a separate 40µm long saturable absorber (SA) section, passive waveguide sections (shallow and deep

High-power actively Q-switched single-mode 1342 nm Nd:YVO4 ring laser, injection-locked by a cw single-frequency microchip laser.

Science.gov (United States)

Koch, Peter; Bartschke, Juergen; L'huillier, Johannes A

2015-11-30

In this paper we report on the realization of a single-mode Q-switched Nd:YVO4 ring laser at 1342 nm. Unidirectional and single-mode operation of the ring laser is achieved by injection-locking with a continuous wave Nd:YVO4 microchip laser, emitting a single-frequency power of up to 40 mW. The ring laser provides a single-mode power of 13.9 W at 10 kHz pulse repetition frequency with a pulse duration of 18.2 ns and an excellent beam quality (M2 laser, a power of 8.7 W at 671 nm with a pulse duration of 14.8 ns and a beam propagation factor of M2 < 1.1 is obtained. The 671 nm radiation features a long-term spectral width of 75 MHz.

Time evolution of coupled-bunch modes from beta function variation in storage rings

Directory of Open Access Journals (Sweden)

Kai Meng Hock

2007-08-01

Full Text Available We present an analytical and numerical study of the equations of motion for bunches coupled by transverse wakefields. We base our study on a recent lattice design for the damping rings in the baseline configuration of the International Linear Collider. Using the macroparticle model, and assuming resistive wall wakefield coupling, we present numerical results on the time evolution of the multibunch modes. Decay modes display growth after initial decay, and mode amplitudes exhibit high-frequency oscillations. These phenomena are not expected if the beta function is assumed to have a constant, averaged value. We show analytically that they can come from coupling between modes caused by variation of the beta function in a real lattice. The effect is shown to be comparable to the effect of a nonuniform fill pattern and significantly larger than that of the higher-order mode wakefield localized in the rf cavities. Turning to the case of constant beta function, we develop a more complete treatment of the equations of motion. We derive general formulas for the bunch trajectories, and show that such formulas can only be valid in the limit of small wakefield coupling.

Local vibrational modes of the water dimer - Comparison of theory and experiment

Science.gov (United States)

Kalescky, R.; Zou, W.; Kraka, E.; Cremer, D.

2012-12-01

Local and normal vibrational modes of the water dimer are calculated at the CCSD(T)/CBS level of theory. The local H-bond stretching frequency is 528 cm-1 compared to a normal mode stretching frequency of just 143 cm-1. The adiabatic connection scheme between local and normal vibrational modes reveals that the lowering is due to mass coupling, a change in the anharmonicity, and coupling with the local HOH bending modes. The local mode stretching force constant is related to the strength of the H-bond whereas the normal mode stretching force constant and frequency lead to an erroneous underestimation of the H-bond strength.

Body-insensitive Multi-Mode MIMO Terminal Antenna of Double-Ring Structure

DEFF Research Database (Denmark)

Zhao, Kun; Zhang, Shuai; Ishimiya, Katsunori

2015-01-01

of mobile terminals. With the multimode excitation, the MIMO cellular antenna can operate at 830-900 MHz, 1700-2200 MHz, and 2400-2700 MHz, for 2G, 3G, and LTE bands, respectively. The MIMO Wi-Fi antenna can cover two Wi-Fi bands from 2.4 to 2.5 GHz and from 5.2 to 5.8 GHz. The effect of a user's body......In this paper, we propose a novel multimode multi-input multi-output (MIMO) antenna system composed of a dual-element MIMO cellular antenna and dual-element MIMO Wi-Fi antenna for mobile terminal applications. The antenna system has a double-ring structure and can be integrated with the metal frame...... on the MIMO cellular antenna is investigated on CTIA standard phantoms and a real user. Since our antenna mainly operates in the loop mode, it has a much lower efficiency loss than conventional mobile antennas in both talking and data modes. Our theoretical analysis and experiments have shown that our design...

Low-timing-jitter, stretched-pulse passively mode-locked fiber laser with tunable repetition rate and high operation stability

International Nuclear Information System (INIS)

Liu, Yuanshan; Zhang, Jian-Guo; Chen, Guofu; Zhao, Wei; Bai, Jing

2010-01-01

We design a low-timing-jitter, repetition-rate-tunable, stretched-pulse passively mode-locked fiber laser by using a nonlinear amplifying loop mirror (NALM), a semiconductor saturable absorber mirror (SESAM), and a tunable optical delay line in the laser configuration. Low-timing-jitter optical pulses are stably produced when a SESAM and a 0.16 m dispersion compensation fiber are employed in the laser cavity. By inserting a tunable optical delay line between NALM and SESAM, the variable repetition-rate operation of a self-starting, passively mode-locked fiber laser is successfully demonstrated over a range from 49.65 to 50.47 MHz. The experimental results show that the newly designed fiber laser can maintain the mode locking at the pumping power of 160 mW to stably generate periodic optical pulses with width less than 170 fs and timing jitter lower than 75 fs in the 1.55 µm wavelength region, when the fundamental repetition rate of the laser is continuously tuned between 49.65 and 50.47 MHz. Moreover, this fiber laser has a feature of turn-key operation with high repeatability of its fundamental repetition rate in practice

Guidelines for Stretch Flanging Advanced High Strength Steels

International Nuclear Information System (INIS)

Sriram, S.; Chintamani, J.

2005-01-01

Advanced High Strength Steels (AHSS) are currently being considered for use in closure and structural panels in the automotive industry because of their high potential for affordable weight reduction and improved performance. AHSS such as dual phase steels are currently being used in some vehicle platforms. From a manufacturing perspective, stretch flanging during stamping is an important deformation mode requiring careful consideration of geometry and the die process. This paper presents some geometric and process guidelines for stretch flanging AHSS. Hole expansion experiments were conducted to determine the failure limit for a sheared edge condition. Effects of punching clearance, prestrain and prior strain path on hole expansion were explored in these experiments. In addition, dynamic explicit FE calculations using LS-DYNA were also conducted for a typical stretch flange by varying some key geometric parameters. The experimental and FEA results were then analyzed to yield process and geometric guidelines to enable successful stretch flanging of AHSS

Ring interferometry

CERN Document Server

Malykin, Grigorii B; Zhurov, Alexei

2013-01-01

This monograph is devoted to the creation of a comprehensive formalism for quantitative description of polarized modes' linear interaction in modern single-mode optic fibers. The theory of random connections between polarized modes, developed in the monograph, allows calculations of the zero shift deviations for a fiber ring interferometer. The monograph addresses also the

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

Stability of large orbit, high-current particle rings

International Nuclear Information System (INIS)

Lovelace, R.V.E.

1994-01-01

A review is made of theory of the low-frequency stability of large orbit, high-current particle rings which continue to be of interest for compact fusion systems. The precession mode was the first mode predicted by Furth and observed by Christofilos to be unstable under certain conditions. Subsequently, many detailed studies have been made of the stability of particle rings- different modes, different ring geometries, systems with/without a toroidal B field, and sytems with/without a current carrying plasma component. The possibly dangerous modes are still thought to include the precession mode, the tilting mode, and the low order kink modes. copyright American Institute of Physics

Excitation and deexcitation of the Si-H stretching mode in a Si:H with picosecond free electron laser pulses

International Nuclear Information System (INIS)

Xu, Z.; Fauchet, M.; Rella, C.W.

1995-01-01

Hydrogen in amorphous and crystalline silicon has been the topic of intense theoretical and experimental investigations for more than one decade. To better understand how the Si-H bonds interact with the Si matrix and how they can be broken, it would be useful to excite selectively these bonds and monitor the energy flow from the Si-H bonds into the bulk Si modes. One attractive way of exciting the Si-H modes selectively is with an infrared laser tuned to a Si-H vibrational mode. Unfortunately, up to now, this type of experiment had not been possible because of the lack of a laser producing intense, ultrashort pulses that are tunable in the mid infrared. In this presentation, we report the first measurement where a 1 picosecond long laser pulse was used to excite the Si-H stretching modes near 2000 cm -1 and another identical laser pulse was used to measure the deexcitation from that specific vibrational mode. The laser was the Stanford free electron laser generating ∼1 ps-long pulses, tunable in the 5 μm region and focussed to an intensity of ∼1 GW/cm 2 . The pump-probe measurements were performed in transmission at room temperature on several 2 μm thick a-Si:H films deposited on c-Si. Samples with predominant Si-H 1 modes, predominant Si-H n>1 modes and with a mixture of modes were prepared. The laser was tuned on resonance with either of these modes. Immediately after excitation, we observe a bleaching of the infrared absorption, which can be attributed to excitation of the Si-H mode. Beaching is expected since, as a result of anharmonicity, the detuning between the (E 3 - E 2 ) resonance and the (E 2 - E 1 ) resonance is larger than the laser bandwidth. Note that despite the anharmonicity, it should be possible to climb the vibrational ladder due to power broadening

Eliminating electromechanical instability in dielectric elastomers by employing pre-stretch

International Nuclear Information System (INIS)

Jiang, Liang; Jerrams, Stephen; Betts, Anthony; Kennedy, David

2016-01-01

Electromechanical instability (EMI) is one of most common failure modes for dielectric elastomers (DEs). It has been reported that pre-stretching a DE sample can suppress EMI due to strain stiffening taking place for larger strains and a higher elastic modulus are achieved at high stretch ratios when a voltage is applied to the material. In this work, the influence of equi-biaxial stretch on DE secant modulus was studied using VHB 4910 and silicone rubber (SR) composites containing barium titanate (BaTiO 3 , BT) particles and also dopamine coated BT (DP-BT) particles. The investigation of equi-biaxial deformation and EMI failure for VHB 4910 was undertaken by introducing a voltage-stretch function. The results showed that EMI was suppressed by equi-biaxial pre-stretch for all the DEs fabricated and tested. The stiffening properties of the DE materials were also studied with respect to the secant modulus. Furthermore, a voltage-induced strain of above 200% was achieved for the polyacrylate film by applying a pre-stretch ratio of 2.0 without EMI occurring. However, a maximum voltage-induced strain in the polyacrylate film of 78% was obtained by the SR/20 wt% DP-BT composite for a lower applied pre-stretch ratio of 1.6 and again EMI was eliminated. (paper)

Stretched exponentials and power laws in granular avalanching

Science.gov (United States)

Head, D. A.; Rodgers, G. J.

1999-02-01

We introduce a model for granular surface flow which exhibits both stretched exponential and power law avalanching over its parameter range. Two modes of transport are incorporated, a rolling layer consisting of individual particles and the overdamped, sliding motion of particle clusters. The crossover in behaviour observed in experiments on piles of rice is attributed to a change in the dominant mode of transport. We predict that power law avalanching will be observed whenever surface flow is dominated by clustered motion.

Stretch Sensor Device

DEFF Research Database (Denmark)

2013-01-01

The invention relates to a method for determining stretch values and movement of body parts, e.g. a foot, by analysing stretch data from a stretch sensor. By analysing data from the stretch sensor it is possible to determine stretch samples which are associated with particular motion phases...

Performance Comparison of Mode-Locked Erbium-Doped Fiber Laser with Nonlinear Polarization Rotation and Saturable Absorber Approaches

International Nuclear Information System (INIS)

Ismail, M. A.; Tan, S. J.; Shahabuddin, N. S.; Harun, S. W.; Arof, H.; Ahmad, H.

2012-01-01

A mode-locked erbium-doped fiber laser (EDFL) is demonstrated using a highly concentrated erbium-doped fiber (EDF) as the gain medium in a ring configuration with and without a saturable absorber (SA). Without the SA, the proposed laser generates soliton pulses with a repetition rate of 12 MHz, pulse width of 1.11 ps and energy pulse of 1.6 pJ. By incorporating SA in the ring cavity, the optical output of the laser changes from soliton to stretched pulses due to the slight change in the group velocity dispersion. With the SA, a cleaner pulse is obtained with a repetition rate of 11.3 MHz, a pulse width of 0.58 ps and a pulse energy of 2.3 pJ. (fundamental areas of phenomenology(including applications))

Tunable and switchable dual-wavelength passively mode-locked Bi-doped all-fiber ring laser based on nonlinear polarization rotation

International Nuclear Information System (INIS)

Luo, A-P; Luo, Z-C; Xu, W-C; Dvoyrin, V V; Mashinsky, V M; Dianov, E M

2011-01-01

We demonstrate a tunable and switchable dual-wavelength passively mode-locked Bi-doped all-fiber ring laser by using nonlinear polarization rotation (NPR) technique. Exploiting the spectral filtering effect caused by the combination of the polarizer and intracavity birefringence, the wavelength separation of dual-wavelength mode-locked pulses can be flexibly tuned between 2.38 and 20.45 nm. Taking the advantage of NPR-induced intensity-dependent loss to suppress the mode competition, the stable dual-wavelength pulses output is obtained at room temperature. Moreover, the dual-wavelength switchable operation is achieved by simply rotating the polarization controllers (PCs)

Measurement of calcium influx in tethered rings of rabbit aorta under tension

International Nuclear Information System (INIS)

Gleason, M.M.; Ratz, P.H.; Flaim, S.F.

1985-01-01

Calcium (Ca) influx in vascular smooth muscle is routinely measured in untethered preparations not under passive stretch, and Ca influx data are correlated with data for steady-state isometric tension obtained under parallel conditions from tethered preparations under passive stretch. The validity of this method was tested by simultaneous measurement of Ca influx and tension in tethered rings of rabbit thoracic aorta. Ca influx ( 45 Ca 3-min pulse) and tension were measured at 3 and 30 min after norepinephrine (NE) or KCl and under control (no agonist) conditions. Active tension was significantly altered by variations in passive tension. Ca influx was unaffected by passive tension under control, NE, or KCl conditions, and results were similar at 3 and 30 min. The results confirm the validity of correlating Ca influx data from untethered rings with steady-state contractile response data obtained from tethered rings under similar experimental conditions

Stretching

Science.gov (United States)

... after a workout. Stretching still can be a beneficial activity after you have sufficiently warmed up. The ... light aerobic activity and stretching. If you're running at a quick pace, you can slow down ...

Electrical Characteristics of the Contour-Vibration-Mode Piezoelectric Transformer with Ring/Dot Electrode Area Ratio

Science.gov (United States)

Yoo, Juhyun; Yoon, Kwanghee; Lee, Yongwoo; Suh, Sungjae; Kim, Jongsun; Yoo, Chungsik

2000-05-01

Contour-vibration-mode Pb(Sb1/2Nb1/2)O3-Pb(Zr, Ti)O3 [PSN-PZT] piezoelectric transformers with different ring/dot electrode area ratios were fabricated to the size of 27.5× 27.5× 2.5 mm3 by cold isostatic pressing. The electrical properties and characteristic temperature rises caused by the vibration were measured at various load resistances. Efficiencies above 90% with load resistance were obtained from all the transformers. The voltage step-up ratio appeared to be proportional to the dot electrode area. A 14 W fluorescent lamp, T5, was successfully driven by all of the fabricated transformers. The transformer with ring/dot electrode area ratio of 4.85 exhibited the best properties in terms of output power, efficiency and characteristic temperature rise, 14.88 W, 98% and 5°C, respectively.

Non-destructive splitter of twisted light based on modes splitting in a ring cavity.

Science.gov (United States)

Li, Yan; Zhou, Zhi-Yuan; Ding, Dong-Sheng; Zhang, Wei; Shi, Shuai; Shi, Bao-Sen; Guo, Guang-Can

2016-02-08

Efficiently discriminating beams carrying different orbital angular momentum (OAM) is of fundamental importance for various applications including high capacity optical communication and quantum information processing. We design and experimentally verify a distinguished method for effectively splitting different OAM-carried beams by introducing Dove prisms in a ring cavity. Because of rotational symmetry broken of two OAM-carried beams with opposite topological charges, their transmission spectra will split. When mode and impedance matches between the cavity and one OAM-carried beam are achieved, this beam will transmit through the cavity and other beam will be reflected, both beams keep their spatial shapes. In this case, the cavity acts like a polarized beam splitter. Besides, the transmitting beam can be selected at your will, the splitting efficiency can reach unity if the cavity is lossless and it completely matches the beam. Furthermore, beams carry multi-OAMs can also be split by cascading ring cavities.

Highly optimized tunable Er3+-doped single longitudinal mode fiber ring laser, experiment and model

DEFF Research Database (Denmark)

Poulsen, Christian; Sejka, Milan

1993-01-01

A continuous wave (CW) tunable diode-pumped Er3+-doped fiber ring laser, pumped by diode laser at wavelengths around 1480 nm, is discussed. Wavelength tuning range of 42 nm, maximum slope efficiency of 48% and output power of 14.4 mW have been achieved. Single longitudinal mode lasing...... with a linewidth of 6 kHz has been measured. A fast model of erbium-doped fiber laser was developed and used to optimize output parameters of the laser...

1.5 W high efficiency and tunable single-longitudinal-mode Ho:YLF ring laser based on Faraday effect.

Science.gov (United States)

Wu, Jing; Ju, Youlun; Dai, Tongyu; Yao, Baoquan; Wang, Yuezhu

2017-10-30

We demonstrated an efficient and tunable single-longitudinal-mode Ho:YLF ring laser based on Faraday effect for application to measure atmospheric carbon dioxide (CO 2 ). Single-longitudinal-mode power at 2051.65 nm achieved 528 mW with the slope efficiency of 39.5% and the M 2 factor of 1.07, and the tunable range of about 178 GHz was obtained by inserting a Fabry-Perot (F-P) etalon with the thickness of 0.5 mm. In addition, the maximum single-longitudinal-mode power reached 1.5 W with the injected power of 528 mW at 2051.65 nm by master oscillator power amplifier (MOPA) technique. High efficiency and tunable single-longitudinal-mode based on Faraday effect around 2 μm has not been reported yet to the best of our knowledge.

50-fs pulse generation directly from a colliding-pulse mode-locked Ti:sapphire laser using an antiresonant ring mirror

Science.gov (United States)

Naganuma, Kazunori; Mogi, Kazuo

1991-05-01

50-fs pulses were directly generated from a colliding-pulse mode-locked Ti:sapphire laser. To achieve the colliding-pulse mode locking, a miniature antiresonant ring containing an organic saturable dye jet was employed as the end mirror for the linear cavity laser. Based on measured dispersion of intracavity elements, a prism pair was implemented to control the cavity dispersion. The generated pulses have no linear chirp but do exhibit parabolic instantaneous frequency owing to third-order dispersion introduced by the prism pair.

Stretching & Flexibility: An Interactive Encyclopedia of Stretching. [CD-ROM].

Science.gov (United States)

2002

This CD-ROM offers 140 different stretches in full-motion video sequences. It focuses on the proper techniques for overall physical fitness, injury prevention and rehabilitation, and 23 different sports (e.g., golf, running, soccer, skiing, climbing, football, and baseball). Topics include stretching for sports; stretching awareness and education…

Modification of MEA modulator-klystron units enabling short pulse injection into a pulse-stretcher ring

International Nuclear Information System (INIS)

Kroes, F.B.; Heine, E.

1989-01-01

In order to modify the present 500 MeV, 1% duty factor electron accelerator MEA into a 900 MeV, 0.1% d.f. injector for a newly to be build pulse- stretching ring, the present modulator-klystron units have to be adapted from 4 MW, 2% d.f. mode of operation into the 10 MW, 0.2% d.f. mode. Suitable klystrons are commercially available, the matching modulators, however, will be obtained by modifying the present ones, which policy is dictated by economical considerations. The design principles of these modulators -a proto-type is presently under construction- will be discussed. Special attention is given to the video-pulse shape requirements, dictated by the future performance of the pulse-stretcher. This device has to deliver low emittance, high duty factor (n90%) beams for nuclear physics experiments. Some proto-type tests of the video-pulse forming modifications will be presented. (author). 5 refs.; 11 figs.; 2 tabs

The Considere condition and rapid stretching of linear and branched polymer melts

DEFF Research Database (Denmark)

McKinley, Gareth H; Hassager, Ole

1999-01-01

to larger Hencky strains as the number of branches is increased. Numerical computations at finite Deborah numbers also show that there is an optimal range of deformation rates over which homogeneous extensions can be maintained to large strain. We also consider other rapid homogeneous stretching...... deformations, such as biaxial and planar stretching, and show that the degree of stabilization afforded by inclusion of material with long-chain branching is a sensitive function of the imposed mode of deformation....

Multiple-bunch-length operating mode design for a storage ring using hybrid low alpha and harmonic cavity method

Energy Technology Data Exchange (ETDEWEB)

Gao, Weiwei, E-mail: gaomqr@mail.ustc.edu.cn [College of Mathematics and Physics, Fujian University of Technology, Fuzhou 350118 (China); Wang, Lin; Li, Heting [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China)

2017-03-11

In this paper we design a simultaneous three bunch length operating mode at the HLS-II (Hefei Light Source II) storage ring by installing two harmonic cavities and minimizing the momentum compaction factor. The short bunches (2.6 mm) presented in this work will meet the requirement of coherent millimeter-wave and sub-THz radiation experiments, while the long bunches (20 mm) will efficiently increase the total beam current. Therefore, this multiple-bunch-length operating mode allows present synchrotron users and coherent millimeter-wave users (or sub THz users) to carry out their experiments simultaneously. Since the relatively low energy characteristic of HLS-II we achieve the multiple-bunch-length operating mode without multicell superconducting RF cavities, which is technically feasible.

Investigation of the isochronous mode of the experimental storage ring (ESR) and the collector ring (CR). Decay spectroscopy of highly charged stored 140Pr ions at the FRS-ESR facility

International Nuclear Information System (INIS)

Litvinov, Sergey A.

2008-11-01

The combination of the present fragment separator FRS and the cooler-storage ring ESR at GSI provides conditions for accurate mass and unique half-life measurements of exotic nuclei. A major part of this doctoral work has been devoted to investigations of the isochronous ion-optical operating mode of the present ESR facility and the planned Collector Ring (CR) facility at FAIR. A detailed ion-optical study of the isochronous storage ring with the emphasis on the main parameters has been done. For example, a simple scaling law providing a quantitative estimate for the mass resolving power as a function of the transverse acceptance has been derived. The ion-optical matching of the FRS-ESR has been calculated and experimentally verified for both the standard and the isochronous operating modes of the ESR. In addition, the dispersion function of a stored ion beam has been measured for both ion-optical modes at the straight section. The improved setting for higher transmission in the standard mode has been used in an experiment on the half-life measurements of highly-charged ions. Orbital electron capture (EC) and/or β + -decay rates of 140 Pr ions with zero-, one- and two- bound electrons have been measured. A complementary future study of EC-decay in highly-charged 64 Cu ions is discussed. Based on the present experience, the ion-optical matching between the future in-flight fragment separator Super-FRS and the CR has been calculated. The isochronous mode of the CR has been calculated. A dedicated Monte-Carlo code (ISOCHRON) has been developed in order to investigate the influence of the transverse acceptance, the closed orbit distortions, the fringe fields of the quadrupoles, the magnetic field imperfections of the magnets on the mass resolving power. The influence of chromaticity on the isochronicity has been investigated. The correction of the chromaticity and of second-order isochronicity has been performed employing sextupole magnets in the arcs of the CR. The

Modes of storage ring coherent instabilities

Energy Technology Data Exchange (ETDEWEB)

Wang, J.M.

1986-12-01

Longitudinal impedance in a beam and various modes of longitudinal coherent instabilities are discussed. The coasting beam coherent instability, microwave instability, and single-bunch longitudinal coherent instabilities are considered. The Vlasov equation is formulated, and a method of solving it is developed. The synchrotron modes are treated, which take the possible bunch shape distortion fully into consideration. A method of treating the synchrotron mode coupling in the case of a small bunch is discussed which takes advantage of the fact that only a few of the synchrotron modes can contribute in such a case. The effect of many bunches on the coherent motion of the beam and the longitudinal symmetric coupled bunch modes are discussed. The transverse impedance is then introduced, and the transverse coasting beam instability is discussed. Various bunched beam instabilities are discussed, including both single bunch instabilities and coupled bunch instabilities. The Vlasov equation for transverse as well as longitudinal motion of particles is introduced as well as a method of solving it within a linear approximation. Head-tail modes and short bunch instabilities and strong coupling instabilities in the long bunch case are covered. (LEW)

Modes of storage ring coherent instabilities

International Nuclear Information System (INIS)

Wang, J.M.

1986-12-01

Longitudinal impedance in a beam and various modes of longitudinal coherent instabilities are discussed. The coasting beam coherent instability, microwave instability, and single-bunch longitudinal coherent instabilities are considered. The Vlasov equation is formulated, and a method of solving it is developed. The synchrotron modes are treated, which take the possible bunch shape distortion fully into consideration. A method of treating the synchrotron mode coupling in the case of a small bunch is discussed which takes advantage of the fact that only a few of the synchrotron modes can contribute in such a case. The effect of many bunches on the coherent motion of the beam and the longitudinal symmetric coupled bunch modes are discussed. The transverse impedance is then introduced, and the transverse coasting beam instability is discussed. Various bunched beam instabilities are discussed, including both single bunch instabilities and coupled bunch instabilities. The Vlasov equation for transverse as well as longitudinal motion of particles is introduced as well as a method of solving it within a linear approximation. Head-tail modes and short bunch instabilities and strong coupling instabilities in the long bunch case are covered

[Current trends in the effects of stretching: application to physical exercise in the workplace].

Science.gov (United States)

Eguchi, Yasumasa; Ohta, Masanori; Yamato, Hiroshi

2011-09-01

A review of the Survey on the State of Employees' Health by the Ministry of Health, Labour and Welfare (2008) shows that the most commonly implemented aspect as an activity of worksite health promotion is "Health counseling", and the second is "Workplace physical exercise." Physical exercise, "Taiso", is acceptable and sustainable for workers, as it is easy to do in a group or alone. Various modes of stretching are implemented for workplace physical exercise. However, articles suggesting negative or contradictory effects of stretching have increased in recent years. Several review articles have revealed that static stretching may induce impairments of muscle power performance and no stretching will prevent or reduce muscle soreness after exercise. There are various aims of workplace physical exercise, so we have to consider the situational method when we apply stretching to occupational health.

Investigation of the isochronous mode of the experimental storage ring (ESR) and the collector ring (CR). Decay spectroscopy of highly charged stored {sup 140}Pr ions at the FRS-ESR facility

Energy Technology Data Exchange (ETDEWEB)

Litvinov, Sergey A.

2008-11-15

The combination of the present fragment separator FRS and the cooler-storage ring ESR at GSI provides conditions for accurate mass and unique half-life measurements of exotic nuclei. A major part of this doctoral work has been devoted to investigations of the isochronous ion-optical operating mode of the present ESR facility and the planned Collector Ring (CR) facility at FAIR. A detailed ion-optical study of the isochronous storage ring with the emphasis on the main parameters has been done. For example, a simple scaling law providing a quantitative estimate for the mass resolving power as a function of the transverse acceptance has been derived. The ion-optical matching of the FRS-ESR has been calculated and experimentally verified for both the standard and the isochronous operating modes of the ESR. In addition, the dispersion function of a stored ion beam has been measured for both ion-optical modes at the straight section. The improved setting for higher transmission in the standard mode has been used in an experiment on the half-life measurements of highly-charged ions. Orbital electron capture (EC) and/or {beta}{sup +}-decay rates of {sup 140}Pr ions with zero-, one- and two- bound electrons have been measured. A complementary future study of EC-decay in highly-charged {sup 64}Cu ions is discussed. Based on the present experience, the ion-optical matching between the future in-flight fragment separator Super-FRS and the CR has been calculated. The isochronous mode of the CR has been calculated. A dedicated Monte-Carlo code (ISOCHRON) has been developed in order to investigate the influence of the transverse acceptance, the closed orbit distortions, the fringe fields of the quadrupoles, the magnetic field imperfections of the magnets on the mass resolving power. The influence of chromaticity on the isochronicity has been investigated. The correction of the chromaticity and of second-order isochronicity has been performed employing sextupole magnets in the

Coherent oscillations of a ring of relativistic particles

International Nuclear Information System (INIS)

Hofmann, I.

1976-07-01

The effect of ring curvature on the coherent perturbations of a ring of relativistic particles is studied within the framework of the linearized Vlasov equation. Finite curvature is shown to have a minor effect on the dynamics of the 'negative mass' mode; the 'transverse' mode in radial direction, however, is found to be coupled with a simultaneous longitudinal density modulation which modifies the dispersion relation. In the limit of small mode frequency (ω/Ω [de

Probing adenine rings and backbone linkages using base specific isotope-edited Raman spectroscopy: application to group II intron ribozyme domain V.

Science.gov (United States)

Chen, Yuanyuan; Eldho, Nadukkudy V; Dayie, T Kwaku; Carey, Paul R

2010-04-27

Raman difference spectroscopy is used to probe the properties of a 36-nt RNA molecule, "D5", which lies at the heart of the catalytic apparatus in group II introns. For D5 that has all of its adenine residues labeled with (13)C and (15)N and utilizing Raman difference spectroscopy, we identify the conformationally sensitive -C-O-P-O-C- stretching modes of the unlabeled bonds adjacent to adenine bases, as well as the adenine ring modes themselves. The phosphodiester modes can be assigned to individual adenine residues based on earlier NMR data. The effect of Mg(2+) binding was explored by analyzing the Raman difference spectra for [D5 + Mg(2+)] minus [D5 no Mg(2+)], for D5 unlabeled, or D5 labeled with (13)C/(15)N-enriched adenine. In both sets of data we assign differential features to G ring modes perturbed by Mg(2+) binding at the N7 position. In the A-labeled spectra we attribute a Raman differential near 1450 cm(-1) and changes of intensity at 1296 cm(-1) to Mg binding at the N7 position of adenine bases. The A and G bases involved in Mg(2+) binding again can be identified using earlier NMR results. For the unlabeled D5, a change in the C-O-P-O-C stretch profile at 811 cm(-1) upon magnesium binding is due to a "tightening up" (in the sense of a more rigid molecule with less dynamic interchange among competing ribose conformers) of the D5 structure. For adenine-labeled D5, small changes in the adenine backbone bond signatures in the 810-830 cm(-1) region suggest that small conformational changes occur in the tetraloop and bulge regions upon binding of Mg(2+). The PO(2)(-) stretching vibration, near 1100 cm(-1), from the nonbridging phosphate groups, probes the effect of Mg(2+)-hydrate inner-sphere interactions that cause an upshift. In turn, the upshift is modulated by the presence of monovalent cations since in the presence of Na(+) and Li(+) the upshift is 23 +/- 2 cm(-1) while in the presence of K(+) and Cs(+) it is 13 +/- 3 cm(-1), a finding that correlates

Ring current instabilities excited by the energetic oxygen ions

International Nuclear Information System (INIS)

Kakad, A. P.; Singh, S. V.; Lakhina, G. S.

2007-01-01

The ring current instabilities driven by the energetic oxygen ions are investigated during the magnetic storm. The electrons and protons are considered to have Maxwellian distributions, while energetic oxygen ions are having loss-cone distribution. Dispersion relation for the quasielectrostatic modes with frequencies ω>ω cp (proton cyclotron frequency) and propagating obliquely to the magnetic field is obtained. Dispersion relation is studied numerically for the storm time ring current parameters and it is found that these instabilities are most prominent during intense storms when the oxygen ions become the dominant constituents of the ring current plasma. For some typical storm-time ring current parameters, these modes can produce quasielectrostatic noise in the range of 17-220 Hz, thus providing a possible explanation of the electrostatic noise observed at the inner boundary of the ring current during magnetic storms. Further, these modes can attain saturation electric fields of the order of 100-500 μV/m, and therefore, are expected to scatter O + ions into the loss-cone giving rise to their precipitation into the atmosphere, thus contributing to the ring current decay

Strings, vortex rings, and modes of instability

Directory of Open Access Journals (Sweden)

Steven S. Gubser

2015-03-01

Full Text Available We treat string propagation and interaction in the presence of a background Neveu–Schwarz three-form field strength, suitable for describing vortex rings in a superfluid or low-viscosity normal fluid. A circular vortex ring exhibits instabilities which have been recognized for many years, but whose precise boundaries we determine for the first time analytically in the small core limit. Two circular vortices colliding head-on exhibit stronger instabilities which cause splitting into many small vortices at late times. We provide an approximate analytic treatment of these instabilities and show that the most unstable wavelength is parametrically larger than a dynamically generated length scale which in many hydrodynamic systems is close to the cutoff. We also summarize how the string construction we discuss can be derived from the Gross–Pitaevskii Lagrangian, and also how it compares to the action for giant gravitons.

Parametric study of the damage ring pattern in fused silica induced by multiple longitudinal modes laser pulses

Energy Technology Data Exchange (ETDEWEB)

Chambonneau, M., E-mail: maxime.chambonneau@hotmail.fr; Grua, P.; Rullier, J.-L.; Lamaignère, L. [CEA CESTA, 15 Avenue des Sablières, CS 60001, 33116 Le Barp Cedex (France); Natoli, J.-Y. [Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille (France)

2015-03-14

With the use of multiple longitudinal modes nanosecond laser pulses at 1064 nm, laser damage sites at the exit surface of fused silica clearly and systematically exhibit ring patterns. It has been shown in our previous works that the apparent chronology of rings was closely related to the temporal shape of the laser pulses. This particular correspondence had suggested an explanation of the ring morphology formation based on the displacement of an ionization front in the surrounding air. To provide a former basis for this hypothesis and deeper understanding of ring pattern formation, additional experiments have been performed. First, the impact of fluence has been investigated, revealing that a wide variety of damage sites are produced within a very narrow fluence range; this fact involves the chronology of appearance of a surface plasma during the laser pulse. The sizes of the damage sites are proportional to the fluence of their expansion occurring between the beginning of the plasma and the end of the laser pulse. Second, specific experiments have been carried out at different angles of incidence, resulting in egg-shaped patterns rather than circular ones. This behavior can be explained by our previous hypothesis of creation of a plasma in air, its expansion being tightly conditioned by the illumination angle. This series of experiments, in which the angle of incidence is varied up to 80°, permits us to link quantitatively the working hypothesis of ionization front propagation with theoretical hydrodynamics modeling.

Stretch-minimising stream surfaces

KAUST Repository

Barton, Michael; Kosinka, Jin; Calo, Victor M.

2015-01-01

We study the problem of finding stretch-minimising stream surfaces in a divergence-free vector field. These surfaces are generated by motions of seed curves that propagate through the field in a stretch minimising manner, i.e., they move without stretching or shrinking, preserving the length of their arbitrary arc. In general fields, such curves may not exist. How-ever, the divergence-free constraint gives rise to these 'stretch-free' curves that are locally arc-length preserving when infinitesimally propagated. Several families of stretch-free curves are identified and used as initial guesses for stream surface generation. These surfaces are subsequently globally optimised to obtain the best stretch-minimising stream surfaces in a given divergence-free vector field. Our algorithm was tested on benchmark datasets, proving its applicability to incompressible fluid flow simulations, where our stretch-minimising stream surfaces realistically reflect the flow of a flexible univariate object. © 2015 Elsevier Inc. All rights reserved.

Stretch-minimising stream surfaces

KAUST Repository

Barton, Michael

2015-05-01

We study the problem of finding stretch-minimising stream surfaces in a divergence-free vector field. These surfaces are generated by motions of seed curves that propagate through the field in a stretch minimising manner, i.e., they move without stretching or shrinking, preserving the length of their arbitrary arc. In general fields, such curves may not exist. How-ever, the divergence-free constraint gives rise to these \\'stretch-free\\' curves that are locally arc-length preserving when infinitesimally propagated. Several families of stretch-free curves are identified and used as initial guesses for stream surface generation. These surfaces are subsequently globally optimised to obtain the best stretch-minimising stream surfaces in a given divergence-free vector field. Our algorithm was tested on benchmark datasets, proving its applicability to incompressible fluid flow simulations, where our stretch-minimising stream surfaces realistically reflect the flow of a flexible univariate object. © 2015 Elsevier Inc. All rights reserved.

Origin of the blue shift of the CH stretching band for 2-butoxyethanol in water.

Science.gov (United States)

Katsumoto, Yukiteru; Komatsu, Hiroyuki; Ohno, Keiichi

2006-07-26

The blue shift of the isolated CD stretching band of 2-butoxyethanol (C4E1), which is observed for the aqueous solution during the dilution process, has been investigated by infrared (IR) spectroscopy and quantum chemical calculations. Mono-deuterium-labeled C4E1's were employed to remove the severe overlapping among the CH stretching bands. The isolated CD stretching mode of the alpha-methylene in the butoxy group shows a large blue shift, while those of the beta-methylene and methyl groups are not largely shifted. The spectral simulation results for the C4E1/H2O complexes indicate that the large blue shift of the CD stretching band of the butoxy group arises mainly from the hydration of the ether oxygen atom.

Stretching Safely and Effectively

Science.gov (United States)

... shown that stretching immediately before an event weakens hamstring strength. Instead of static stretching, try performing a " ... If you play soccer, for instance, stretch your hamstrings as you're more vulnerable to hamstring strains. ...

Acute Effects of Static vs. Ballistic Stretching on Strength and Muscular Fatigue Between Ballet Dancers and Resistance-Trained Women.

Science.gov (United States)

Lima, Camila D; Brown, Lee E; Wong, Megan A; Leyva, Whitney D; Pinto, Ronei S; Cadore, Eduardo L; Ruas, Cassio V

2016-11-01

Lima, CD, Brown, LE, Wong, MA, Leyva, WD, Pinto, RS, Cadore, EL, and Ruas, CV. Acute effects of static vs. ballistic stretching on strength and muscular fatigue between ballet dancers and resistance-trained women. J Strength Cond Res 30(11): 3220-3227, 2016-Stretching is used to increase joint range of motion, but the acute effects can decrease muscle strength. However, this may depend on the population or mode of stretching. The purpose of this study was to compare the acute effects of static vs. ballistic stretching on strength and muscular fatigue between ballet dancers and resistance-trained women. Fifteen resistance-trained women (age 23.8 ± 1.80 years, mass 67.47 ± 7.77 kg, height 168.30 ± 5.53 cm) and 12 ballet dancers (age 22.8 ± 3.04 years, mass 58.67 ± 5.65 kg, height 168.00 ± 7.69 cm) performed 5 days of testing. The first day was control (no stretching), whereas the other 4 days were static or ballistic stretching in a counterbalanced order. Range of motion, strength, and fatigue tests were also performed. Both groups demonstrated a significant decrease in hamstrings strength after static (102.71 ± 2.67 N·m) and ballistic stretching (99.49 ± 2.61 N·m) compared with control (113.059 ± 3.25 N·m), with no changes in quadriceps strength. For fatigue, only ballet dancers demonstrated a decrease from control (71.79 ± 4.88%) to ballistic (65.65 ± 8.19%), but no difference with static (65.01 ± 12.29%). These findings suggest that stretching decreases hamstrings strength similarly in ballet dancers and resistance-trained women, with no differences between modes of stretching. However, ballistic stretching only decreased muscular fatigue in ballet dancers, but not in resistance-trained women. Therefore, no stretching should be performed before strength performance. However, ballistic stretching may decrease acute muscular fatigue in ballet dancers.

The Relation Between Stretching Typology and Stretching Duration: The Effects on Range of Motion.

Science.gov (United States)

Thomas, Ewan; Bianco, Antonino; Paoli, Antonio; Palma, Antonio

2018-04-01

Different stretching strategies and protocols are widely used to improve flexibility or maintain health, acting on the muscle tendon-unit, in order to improve the range of motion (ROM) of the joints. This review aims to evaluate the current body of literature in order to understand the relation between stretching typology and ROM, and secondly to evaluate if a relation exists between stretching volume (either as a single training session, weekly training and weekly frequency) and ROM, after long-term stretching. Twenty-three articles were considered eligible and included in the quantitative synthesis. All stretching typologies showed ROM improvements over a long-term period, however the static protocols showed significant gains (p<0.05) when compared to the ballistic or PNF protocols. Time spent stretching per week seems fundamental to elicit range of movement improvements when stretches are applied for at least or more than 5 min, whereas the time spent stretching within a single session does not seem to have significant effects for ROM gains. Weekly frequency is positively associated to ROM. Evaluated data indicates that performing stretching at least 5 days a week for at least 5 min per week using static stretching may be beneficial to promote ROM improvements. © Georg Thieme Verlag KG Stuttgart · New York.

Transverse multibunch modes for non-rigid bunches, including mode coupling

Energy Technology Data Exchange (ETDEWEB)

Berg, J S; Ruth, R D [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

1996-08-01

A method for computing transverse multibunch growth rates and frequency shifts in rings, which has been described previously, is applied to the PEP-II B factory. The method allows multibunch modes with different internal-bunch oscillation modes to couple to one another, similar to single-bunch mode coupling. Including coupling between the multibunch modes gives effects similar to those seen in single-bunch mode coupling. These effects occur at currents that are lower than the single-bunch mode coupling threshold. (author)

The partially filled viscous ring damper.

Science.gov (United States)

Alfriend, K. T.

1973-01-01

The problem of a spinning satellite with a partially filled viscous ring damper is investigated. It is shown that there are two distinct modes of motion, the nutation-synchronous mode and spin-synchronous mode. From an approximate solution of the equations of motion a time constant is obtained for each mode. From a consideration of the fluid dynamics several methods are developed for determining the damping constant.

Analysis of ultra-relativistic charged particle beam and stretched wire measurement interactions with cylindrically symmetric structures

International Nuclear Information System (INIS)

Deibele, C.E.

1996-01-01

The beam impedance and wakefield are quantities which describe the stability of charged particles in their trajectory within an accelerator. The stretched wire measurement technique is a method which estimates the beam impedance and wakefield. Definitions for the beam impedance, the wakefield, and the stretched wire measurement are presented. A pillbox resonator with circular beampipes is studied for its relatively simple profile and mode structure. Theoretical predictions and measurement data are presented for the interaction of various charged particle beams and center conductor geometries between the cavity and beampipe. Time domain predictions for the stretched wire measurement and wakefield are presented and are shown to be a linear interaction

The injection system of the stretcher ring ELSA

International Nuclear Information System (INIS)

Dreist, A.

1989-07-01

For the stretcher ring ELSA in the framwork of this thesis an injection system has been concipated and constructed which should allow all projected operational modes of this stretcher ring, the stretcher, the post-acceleration, and the accumulation mode. The proof could be performed that the realized concept allows all these operational modes. Furthermore it could be shown that the injection shifted from the equilibrium orbit has no disadvantageous effects on a uniform extraction and by this on a high touching ratio. In fact it is even possible to apply the decay of the coherent betatron oscillations around the equilibrium orbit, caused by injection of the incident beam shifted from the equilibrium orbit, to diagnosis purposes: By reproduction of this damping process in a simulation model statements on nonlinearities present in the ring and by this statements on the actual phase-space structure are possible. It has so been shown that the concept presented in this thesis and realized for this thesis represents a suited injection system for the stretcher ring ELSA. (orig.) [de

Plasmon-induced transparency in ring-bar meta-atom

Directory of Open Access Journals (Sweden)

Wan-Xia Huang

2018-03-01

Full Text Available We introduce an approach for constructing a scalable metamaterial structure, which is composed of a ring and a bar in a unit cell, and supports singular plasmon-induced transparency. The composite multilayered structure consists of coupled meta-atom with bright modes and dark modes interacting through the introduction of structural asymmetry, which involves the displacement of the bar from the center of the ring. The splitting and merging of the absorption peaks is observed with the change in asymmetric degree. In addition, coupled-mode theory with a two-mode and two-port model is introduced to explain the observed novel spectral feature. The results provide a reference for further application to optoelectronic devices.

LASL high-current proton storage rings

International Nuclear Information System (INIS)

Lawrence, G.P.; Cooper, R.K.; Hudgings, D.W.; Spalek, G.; Jason, A.J.; Higgins, E.F.; Gillis, R.E.

1980-01-01

The Proton Storage Ring at LAMPF is a high-current accumulator designed to convert long 800-MeV linac pulses into very short high-intensity proton bunches ideally suited to driving a pulsed polyenergetic neutron source. The Ring, authorized for construction at $19 million, will operate in a short-bunch high-frequency mode for fast neutron physics and a long-bunch low-frequency mode for thermal neutron-scattering programs. Unique features of the project include charge-changing injection with initial conversion from H - to H 0 , a high repetition rate fast-risetime extraction kicker, and high-frequency and first-harmonic bunching system

Surface enhanced Raman spectroscopy and structural characterization of Ag/Cu chiral nano-flower sculptured thin films

International Nuclear Information System (INIS)

Savaloni, Hadi; Babaei, Reza

2013-01-01

Silver chiral nano-flower sculptured thin films with 3-, 4- and 5-fold symmetry were produced on copper substrates using oblique angle deposition method in conjunction with rotation of sample holder with different speeds at different sectors of each revolution corresponding to symmetry order of the acquired nano-flower. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) were employed to obtain morphologies and nano-structure of the films. Raman spectroscopy was performed on all samples that were subject to impregnation by 4,4′-bipyridine (C 10 H 8 N 2 ) solution. A high degree of enhancement of the main bands at 1610, 1297, and 1009 cm −1 that can be assigned to the C=C stretching mode, aromatic ring stretching ring and in-plane ring mode of 4,4′-bipyridine, is achieved.

Surface enhanced Raman spectroscopy and structural characterization of Ag/Cu chiral nano-flower sculptured thin films

Energy Technology Data Exchange (ETDEWEB)

Savaloni, Hadi, E-mail: savaloni@khayam.ut.ac.ir [Department of Physics, University of Tehran, North-Kargar Street, Tehran (Iran, Islamic Republic of); Babaei, Reza, E-mail: reza_babaee_62@yahoo.com [Department of Physics, Islamic Azad University, Science and Research Branch, Tehran (Iran, Islamic Republic of)

2013-09-01

Silver chiral nano-flower sculptured thin films with 3-, 4- and 5-fold symmetry were produced on copper substrates using oblique angle deposition method in conjunction with rotation of sample holder with different speeds at different sectors of each revolution corresponding to symmetry order of the acquired nano-flower. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) were employed to obtain morphologies and nano-structure of the films. Raman spectroscopy was performed on all samples that were subject to impregnation by 4,4′-bipyridine (C{sub 10}H{sub 8}N{sub 2}) solution. A high degree of enhancement of the main bands at 1610, 1297, and 1009 cm{sup −1} that can be assigned to the C=C stretching mode, aromatic ring stretching ring and in-plane ring mode of 4,4′-bipyridine, is achieved.

Mode group specific amplification length in an asymmetric LPG assisted few-mode EDFA

Science.gov (United States)

Rastogi, Vipul; Gaur, Ankita; Aschieri, Pierre; Dussardier, Bernard

2017-01-01

This article presents a scheme for few-mode EDFA, which allows to choose independent amplification lengths for different mode groups. The EDF is a dual concentric core fiber, where the central core is connected to the line FMF and the ring core is doped with erbium to provide amplification. The modes of FMF are launched into the central core of the EDF, are converted into ring modes using LPG for amplification and then converted back into central core modes using another LPG. The distance between the LPGs determines the amplification length. The amplification length, can thus, be chosen for a given mode group. We demonstrate the working of this concept by choosing LP11 and LP21 mode groups of the FMF and show that a suitable choice of amplification lengths for the two mode groups can tailor the differential modal gain (DMG) to any desired value. We demonstrate achieving zero DMG among all the mode of LP11 and LP21 mode groups using this concept while having gain in excess of 20 dB. The study should be useful for optical fiber communication system employing space-division multiplexing (SDM).

Passive mode locking at harmonics of the free spectral range of the intracavity filter in a fiber ring laser.

Science.gov (United States)

Zhang, Shumin; Lu, Fuyun; Dong, Xinyong; Shum, Ping; Yang, Xiufeng; Zhou, Xiaoqun; Gong, Yandong; Lu, Chao

2005-11-01

We report the passive mode-locking at harmonics of the free spectral range (FSR) of the intracavity multi-channel filter in a fiber ring laser. The laser uses a sampled fiber Bragg grating (SFBG) with a free spectral range (FSR) of 0.8 nm, or 99 GHz at 1555 nm, and a length of highly nonlinear photonic crystal fiber with low and flat dispersion. Stable picosecond soliton pulse trains with twofold to sevenfold enhancement in the repetition rate, relative to the FSR of the SFBG, have been achieved. The passive mode-locking mechanism that is at play in this laser relies on a dissipative four-wave mixing process and switching of repetition rate is realized simply by adjustment of the intracavity polarization controllers.

Development of a single-ring OpenPET prototype

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Eiji, E-mail: rush@nirs.go.jp; Tashima, Hideaki; Wakizaka, Hidekatsu; Nishikido, Fumihiko; Hirano, Yoshiyuki; Inadama, Naoko; Murayama, Hideo; Ito, Hiroshi; Yamaya, Taiga

2013-11-21

One of the challenging applications of PET is implementing it for in-beam PET, which is an in situ monitoring method for charged particle therapy. For this purpose, we have previously proposed an open-type PET scanner, OpenPET. The original OpenPET had a physically opened field-of-view (FOV) between two detector rings through which irradiation beams pass. This dual-ring OpenPET (DROP) had a wide axial FOV including the gap. This geometry was not necessarily the most efficient for application to in-beam PET in which only a limited FOV around the irradiation field is required. Therefore, we have proposed a new single-ring OpenPET (SROP) geometry which can provide an accessible and observable open space with higher sensitivity and a reduced number of detectors than the DROP. The proposed geometry was a cylinder shape with its ends cut at a slant, in which the shape of each cut end became an ellipse. In this work, we developed and evaluated a small prototype of the SROP geometry for proof-of-concept. The SROP prototype was designed with 2 ellipse-shaped detector rings of 16 depth-of-interaction (DOI) detectors each. The DOI detectors consisted of 1024 GSOZ scintillator crystals which were arranged in 4 layers of 16×16 arrays, coupled to a 64-channel FP-PMT. Each ellipse-shaped detector ring had a major axis of 281.6 mm and a minor axis of 207.5 mm. For the slant mode, the rings were placed at a 45-deg slant from the axial direction and for the non-slant mode (used as a reference) they were at 90 deg from the axial direction with no gap. The system sensitivity measured from a {sup 22}Na point source was 5.0% for the slant mode. The average spatial resolutions of major and minor axis directions were calculated as 3.8 mm FWHM and 4.9 mm FWHM, respectively for the slant mode. This difference resulted from the ellipsoidal ring geometry and the spatial resolution of the minor axis direction degraded by the parallax error. Comparison between the slant mode and the non

Influence of the stretch wrapping process on the mechanical behavior of a stretch film

Science.gov (United States)

Klein, Daniel; Stommel, Markus; Zimmer, Johannes

2018-05-01

Lightweight construction is an ongoing task in packaging development. Consequently, the stability of packages during transport is gaining importance. This study contributes to the optimization of lightweight packaging concepts regarding their stability. A very widespread packaging concept is the distribution of goods on a pallet whereas a Polyethylene (PE) stretch film stabilizes the lightweight structure during the shipment. Usually, a stretch wrapping machine applies this stretch film to the pallet. The objective of this study is to support packaging development with a method that predicts the result of the wrapping process, based on the mechanical characterization of the stretch film. This result is not only defined by the amount of stretch film, its spatial distribution on the pallet and its internal stresses that result in a containment force. More accurate, this contribution also considers the influence of the deformation history of the stretch film during the wrapping process. By focusing on similarities of stretch wrappers rather than on differences, the influence of generalized process parameters on stretch film mechanics and thereby on pallet stability can be determined experimentally. For a practical use, the predictive method is accumulated in an analytic model of the wrapping process that can be verified experimentally. This paves the way for experimental and numerical approaches regarding the optimization of pallet stability.

Local-mode vibrations of water

International Nuclear Information System (INIS)

Lawton, R.T.; Child, M.S.

1981-01-01

Quantum-mechanical eigenvalues for the stretching vibrations of H 2 O on the Sorbie-Murrell potential surface are shown to contain a series of local-mode doublets, with splittings which vary as the energy increases from 100 cm - 1 at v=1 to 0.001 cm - 1 at v=8. Preliminary calculations indicate that this pattern is largely unaffected by inclusion of the bending vibrational mode. (author)

Efficient {pi} electrons delocalization in prospective push-pull non-linear optical chromophore 4-[N,N-dimethylamino]-4'-nitro stilbene (DANS): A vibrational spectroscopic study

Energy Technology Data Exchange (ETDEWEB)

Vijayakumar, T.; Hubert Joe, I. [Centre for Molecular and Biophysics Research, Department of Physics, Mar Ivanios College, Thiruvananthapuram 695 015, Kerala (India); Reghunadhan Nair, C.P. [Polymers and Special Chemicals Division, Vikram Sarabhai Space Centre, Thiruvananthapuram 695 022, Kerala (India); Jayakumar, V.S. [Centre for Molecular and Biophysics Research, Department of Physics, Mar Ivanios College, Thiruvananthapuram 695 015, Kerala (India)], E-mail: vsjk@vsnl.net

2008-01-22

A comprehensive investigation on the intramolecular charge transfer (ICT) of an efficient {pi}-conjugated potential push-pull NLO chromophore, 4-[N,N-dimethylamino]-4'-nitro stilbene (DANS), from a strong electron-donor group (dimethylamino-N(CH{sub 3}){sub 2}) to a strong electron-acceptor group (nitro-NO{sub 2}) through the {pi}-conjugated bridge (trans-stilbene) has been carried out from their vibrational spectra. The NIR FT-Raman and FT-IR spectra supported by the density functional theory (DFT) quantum chemical computations have been employed to analyze the effects of intramolecular charge transfer on the geometries and the vibrational modes contributing to the linear electro-optic effect of the organic NLO material. It has been observed that the changes in the endocyclic and exocyclic angles result from the charge-transfer interaction of the phenyl ring and the amino group in the electron-donor side of the NLO chromophore. The strongest vibrational modes contributing to the electro-optic effect have been identified and examined from the concurrent IR and Raman activation of {nu}(C=C/C-C) mode, ring C=C stretching modes, in-plane deformation modes, nitro modes and the umbrella mode of methyl groups. Furthermore, the splitting of the vinyl stretching modes and the electronic effects such as hyperconjugation and backdonation on the methyl hydrogen atoms causing the decrease of stretching frequencies and infrared intensities have also been analyzed in detail. The effect of frontier orbitals transition of electron density transfer and the influence of planarity between the phenyl rings of the stilbene moiety on the first hyperpolarizability have also been discussed.

Free-standing nano-scale graphite saturable absorber for passively mode-locked erbium doped fiber ring laser

International Nuclear Information System (INIS)

Lin, Y-H; Lin, G-R

2012-01-01

The free-standing graphite nano-particle located between two FC/APC fiber connectors is employed as the saturable absorber to passively mode-lock the ring-type Erbium-doped fiber laser (EDFL). The host-solvent-free graphite nano-particles with sizes of 300 – 500 nm induce a comparable modulation depth of 54%. The interlayer-spacing and lattice fluctuations of polished graphite nano-particles are observed from the weak 2D band of Raman spectrum and the azimuth angle shift of –0.32 ° of {002}-orientation dependent X-ray diffraction peak. The graphite nano-particles mode-locked EDFL generates a 1.67-ps pulsewidth at linearly dispersion-compensated regime with a repetition rate of 9.1 MHz. The time-bandwidth product of 0.325 obtained under a total intra-cavity group-delay-dispersion of –0.017 ps 2 is nearly transform-limited. The extremely high stability of the nano-scale graphite saturable absorber during mode-locking is observed at an intra-cavity optical energy density of 7.54 mJ/cm 2 . This can be attributed to its relatively high damage threshold (one order of magnitude higher than the graphene) on handling the optical energy density inside the EDFL cavity. The graphite nano-particle with reduced size and sufficient coverage ratio can compete with other fast saturable absorbers such as carbon nanotube or graphene to passively mode-lock fiber lasers with decreased insertion loss and lasing threshold

Transverse Periodic Beam Loading Effects in a Storage Ring

International Nuclear Information System (INIS)

Thompson, J.R.; Byrd, J.M.

2009-01-01

Uneven beam fill patterns in storage rings, such as gaps in the fill patterns, leads to periodic, or transient loading of the modes of the RF cavities. We show that an analogous effect can occur in the loading of a dipole cavity mode when the beam passes off the electrical center of the cavity mode. Although this effect is small, it results in a variation of the transverse offset of the beam along the bunch train. For ultralow emittance beams, such as optimized third generation light sources and damping rings, this effect results in a larger projected emittance of the beam compared with the single bunch emittance. The effect is particularly strong for the case when a strong dipole mode has been purposely added to the ring, such as a deflecting, or 'crab' cavity. We derive an approximate analytic solution for the variation of the beam-induced deflecting voltage along the bunch train.

Short Durations of Static Stretching when Combined with Dynamic Stretching do not Impair Repeated Sprints and Agility.

Science.gov (United States)

Wong, Del P; Chaouachi, Anis; Lau, Patrick W C; Behm, David G

2011-01-01

This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performed (90 s total). Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. Key pointsThe duration of combined static and dynamic stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit and reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001).No significant differences in RSA and COD between the 3 stretching conditions.The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects.The short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments.

Short Durations of Static Stretching when Combined with Dynamic Stretching do not Impair Repeated Sprints and Agility

Science.gov (United States)

Wong, Del P.; Chaouachi, Anis; Lau, Patrick W.C.; Behm, David G.

2011-01-01

This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performed (90 s total). Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. Key points The duration of combined static and dynamic stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit and reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). No significant differences in RSA and COD between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. The short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. PMID:24149890

New graft sizing rings for aortic valve reimplantation procedures.

Science.gov (United States)

Jelenc, Matija; Jelenc, Blaž; Kneževic, Ivan; Klokocovnik, Tomislav

2018-01-01

The objective was to design sizing rings that would enable proper sizing of the graft in reimplantation procedures and to perform leaflet repair before graft implantation. The rings were designed in Autodesk Fusion 360 (San Rafael, CA, USA) and 3D printed using a commercial online 3D printing service. We designed incomplete rings with a low profile and complete rings with a high profile. The complete rings are best suited for reimplantation procedures, whereas low profile C rings are intended for isolated aortic valve repair, where the ascending aorta is not transected. The rings come in sizes corresponding to Vascutek Gelweave graft sizes (Vascutek Terumo, Renfrewshire, Scotland). The ring internal diameters are 5% larger than the designated ring sizes and account for the 5% stretch of the grafts when pressurized. Blades of the rings are placed at 20° intervals. The slits between the blades are designed in such a way that the commissural U-sutures, when put in place and under tension, will lock the ring in position. The rings were successfully used in 10 of our latest reimplantation procedures. After dissection of the aortic root, the commissures were suspended with U-stitches and then the ring was seated onto them. Complete leaflet repair with plication to achieve adequate effective height was then performed, followed by graft implantation. No additional leaflet repair was needed. The newly designed sizing rings enable proper sizing of the graft in reimplantation procedures and enable complete leaflet repair before graft implantation. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Spectral decomposition of the stretching dynamics of the Arnold cat map

International Nuclear Information System (INIS)

Hasegawa, Hiroshi H.; Driebe, Dean J.; Li, C.-B.

2003-01-01

Using the Markov partition of the Arnold cat map on the covering space allows for the introduction of a stable basis in which the Frobenius-Perron operator may be decomposed. We consider in detail the stretching dynamics on the partition of the transformation that yields the cat map under two iterations. The discrete decay modes of the system are constructed

Acute effects of static stretching on peak and end-range hamstring-to-quadriceps functional ratios

Science.gov (United States)

Sekir, Ufuk; Arabaci, Ramiz; Akova, Bedrettin

2015-01-01

AIM: To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps (H/Q) strength ratios in elite women athletes. METHODS: Eleven healthy female athletes in an elite competitive level participated to the study. All the participants fulfilled the static stretching or non-stretching (control) intervention protocol in a randomized design on different days. Two static unassisted stretching exercises, one in standing and one in sitting position, were used to stretch both the hamstring and quadriceps muscles during these protocols. The total time for the static stretching was 6 ± 1 min. The isokinetic peak torque measurements for the hamstring and quadriceps muscles in eccentric and concentric modes and the calculations for the functional H/Q strength ratios at angular velocities of 60°/s and 180°/s were made before (pre) and after (post) the control or stretching intervention. The strength measurements and functional strength ratio calculations were based during the entire- and end-range of knee extension. RESULTS: The pre-test scores for quadriceps and hamstring peak torque and end range values were not significantly different between the groups (P > 0.05). Subsequently, although the control group did not exhibit significant changes in quadriceps and hamstring muscle strength (P > 0.05), static stretching decreased eccentric and concentric quadriceps muscle strength at both the 60°/s and 180°/s test speeds (P hamstring muscle strength at both the 60°/s and 180°/s test speeds (P 0.05). Furthermore, the functional H/Q strength ratios exhibited no significant alterations during the entire and end ranges of knee extension both in the static stretching or the control intervention (P > 0.05). CONCLUSION: According to our results, static stretching routine does not influence functional H/Q ratio. Athletes can confidently perform static stretching during their warm-up routines. PMID:26495249

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.

Dissociation pathways of a single dimethyl disulfide on Cu(111): Reaction induced by simultaneous excitation of two vibrational modes

Energy Technology Data Exchange (ETDEWEB)

Motobayashi, Kenta, E-mail: kmotobayashi@cat.hokudai.ac.jp [Catalysis Research Center, Hokkaido University, Sapporo 001-0021 (Japan); Department of Advanced Materials Science, The University of Tokyo, Kashiwa 277-8561 (Japan); Surface and Interface Science Laboratory, RIKEN, Wako 351-0198 (Japan); Kim, Yousoo [Surface and Interface Science Laboratory, RIKEN, Wako 351-0198 (Japan); Arafune, Ryuichi [International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044 (Japan); Ohara, Michiaki; Ueba, Hiromu; Kawai, Maki, E-mail: maki@k.u-tokyo.ac.jp [Department of Advanced Materials Science, The University of Tokyo, Kashiwa 277-8561 (Japan)

2014-05-21

We present a novel reaction mechanism for a single adsorbed molecule that proceeds via simultaneous excitation of two different vibrational modes excited by inelastic tunneling electrons from a scanning tunneling microscope. Specifically, we analyze the dissociation of a single dimethyl disulfide (DMDS, (CH{sub 3}S){sub 2}) molecule on Cu(111) by using a versatile theoretical method, which permits us to simulate reaction rates as a function of sample bias voltage. The reaction is induced by the excitation of C-H stretch and S-S stretch modes by a two-electron process at low positive bias voltages. However, at increased voltages, the dissociation becomes a single-electron process that excites a combination mode of these stretches, where excitation of the C-H stretch is the energy source and excitation of the S-S stretch mode enhances the anharmonic coupling rate. A much smaller dissociation yield (few orders of magnitude) at negative bias voltages is understood in terms of the projected density of states of a single DMDS on Cu(111), which reflects resonant excitation through the molecular orbitals.

Local-mode vibrations of water

Energy Technology Data Exchange (ETDEWEB)

Lawton, R.T.; Child, M.S. (Oxford Univ. (UK). Dept. of Theoretical Chemistry)

1981-05-11

Quantum-mechanical eigenvalues for the stretching vibrations of H/sub 2/O on the Sorbie-Murrell potential surface are shown to contain a series of local-mode doublets, with splittings which vary as the energy increases from 100 cm/sup -1/ at v=1 to 0.001 cm/sup -1/ at v=8. Preliminary calculations indicate that this pattern is largely unaffected by inclusion of the bending vibrational mode.

Local-mode vibrations of water

Energy Technology Data Exchange (ETDEWEB)

Lawton, R.T.; Child, M.S. (Oxford Univ. (UK). Dept. of Theoretical Chemistry)

1981-05-11

Quantum-mechanical eigenvalues for the stretching vibrations of H/sub 2/O on the Sorbie-Murrell potential surface are shown to contain a series of local-mode doublets, with splittings which vary as the energy increases from 100 cm/sup -1/ at theta=1 to 0.001 cm/sup -1/ at theta=8. Preliminary calculations indicate that this pattern is largely unaffected by inclusion of the bending vibrational mode.

Passive Stretch Versus Active Stretch on Intervertebral Movement in Non - Specific Neck Pain

International Nuclear Information System (INIS)

Abd El - Aziz, A.H.; Amin, D.I.; Moustafa, I.

2016-01-01

Neck pain is one of the most common and painful musculoskeletal conditions. Point prevalence ranges from 6% to 22% and up to 38% of the elderly population, while lifetime prevalence ranges from 14,2% to 71%. Up till now no randomized study showed the effect between controversy of active and passive stretch on intervertebral movement. The purpose: the current study was to investigate the effect of the passive and active stretch on intervertebral movement in non - specific neck pain. Material and methods: Forty five subjects from both sexes with age range between 18 and 30 years and assigned in three groups, group I (15) received active stretch, ultrasound and TENS. Group II (15) received passive stretch, ultrasound and TENS. Group III (15) received ultrasound and TENS. The radiological assessment was used to measure rotational and translational movement of intervertebral movement before and after treatment. Results: MANOVA test was used for radiological assessment before and after treatment there was significant increase in intervertebral movement in group I as p value =0.0001. Conclusion: active stretch had a effect in increasing the intervertebral movement compared to the passive stretch

Optical self-injection mode-locking of semiconductor optical amplifier fiber ring with electro-absorption modulation—fundamentals and applications

International Nuclear Information System (INIS)

Chi, Yu-Chieh; Lin, Gong-Ru

2013-01-01

The optical self-injection mode-locking of a semiconductor optical amplifier incorporated fiber ring laser (SOAFL) with spectrally sliced multi-channel carriers is demonstrated for applications. The synthesizer-free SOAFL pulse-train is delivered by optical injection mode-locking with a 10 GHz self-pulsed electro-absorption modulator (EAM). Such a coupled optical and electronic resonator architecture facilitates a self-feedback oscillation with a higher Q-factor and lower phase/intensity noises when compared with conventional approaches. The theoretical model of such an injection-mode-locking SOAFL is derived to improve the self-pulsating performance of the optical return-to-zero (RZ) carrier, thus providing optimized pulsewidth, pulse extinction ratio, effective Q-factor, frequency variation and timing jitter of 11.4 ps, 9.1 dB, 4 × 10 5 , −1 bi-directional WDM transmission network with down-stream RZ binary phase-shift keying (RZ-BPSK) and up-stream re-modulated RZ on–off-keying (RZ-OOK) formats. Under BPSK/OOK bi-directional data transmission, the self-pulsed harmonic mode-locking SOAFL simultaneously provides four to six WDM channels for down-stream RZ-BPSK and up-stream RZ-OOK formats with receiving sensitivities of −17 and −15.2 dBm at a bit error rate of 10 −9 , respectively. (paper)

SHORT DURATIONS OF STATIC STRETCHING WHEN COMBINED WITH DYNAMIC STRETCHING DO NOT IMPAIR REPEATED SPRINTS AND AGILITY

Directory of Open Access Journals (Sweden)

Del P. Wong

2011-06-01

Full Text Available This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA and change of direction (COD. Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s. Three dynamic stretching exercises of 30 s duration were then performed (90 s total. Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p < 0.001. However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (< 90 s static stretching may not have provided sufficient stimulus to elicit performance impairments

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

Dynamic motion modes of high temperature superconducting maglev on a 45-m long ring test line

Science.gov (United States)

Lei, W. Y.; Qian, N.; Zheng, J.; Jin, L. W.; Zhang, Y.; Deng, Z. G.

2017-10-01

With the development of high temperature superconducting (HTS) maglev, studies on the running stability have become more and more significant to ensure the operation safety. An experimental HTS maglev vehicle was tested on a 45-m long ring test line under the speed from 4 km/h to 20 km/h. The lateral and vertical acceleration signals of each cryostat were collected by tri-axis accelerometers in real time. By analyzing the phase relationship of acceleration signals on the four cryostats, several typical motion modes of the HTS maglev vehicle, including lateral, yaw, pitch and heave motions were observed. This experimental finding is important for the next improvement of the HTS maglev system.

Measurements of electron beam emittance in the Accelerator Test Facility damping ring operated in multibunch modes

Directory of Open Access Journals (Sweden)

Yosuke Honda

2003-09-01

Full Text Available We present the measurement results of electron beam emittance in the Accelerator Test Facility damping ring operated in multibunch modes. The measurements were carried out with an upgraded laser wire beam profile monitor. The monitor has now a vertical wire as well as a horizontal one and is able to make much faster measurements thanks to an increased effective laser power inside the cavity. The measured emittance shows no large bunch-to-bunch dependence in either the horizontal or vertical directions. The values of the vertical emittance are similar to those obtained in the single-bunch operation. The present results are an important step toward the realization of a high-energy linear collider.

Operational Status of PF-Ring and PF-AR after the Earthquake

International Nuclear Information System (INIS)

Honda, T; Asaoka, S; Haga, K; Harada, K; Honda, Y; Izawa, M; Kamiya, Y; Kobayashi, Y; Miyajima, T; Miyauchi, H; Nagahashi, S; Nakamura, N; Nogami, T; Obina, T; Ozaki, T; Sagehashi, H; Sakai, H; Sakanaka, S; Sasaki, H; Sato, Y

2013-01-01

In 2011, two SR sources of KEK, PF-ring and PF-AR, needed to change the operation schedule because of the unprecedented earthquake on March 11. Though the injector linac and the storage rings suffered a serious damage, temporary recovery was accomplished quickly and the trial operation started in May. The regular user operation could be resumed in October 2011. In the restoration work after the earthquake, some old vacuum components were removed from PF-ring. This work fortunately brought an effect of settling the quadrupole-mode longitudinal instability. For the top-up injection of PF-ring, the pulsed sextupole magnet has been used instead of the conventional kicker magnets since 2011. The hybrid-fill mode in place of the single-bunch mode has become available. Recently, the 10-Hz orbit switching for the tandem circularly polarized undulators has been developed for the user operation.

Curved Piezoelectric Actuators for Stretching Optical Fibers

Science.gov (United States)

Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

2008-01-01

Assemblies containing curved piezoceramic fiber composite actuators have been invented as means of stretching optical fibers by amounts that depend on applied drive voltages. Piezoceramic fiber composite actuators are conventionally manufactured as sheets or ribbons that are flat and flexible, but can be made curved to obtain load-carrying ability and displacement greater than those obtainable from the flat versions. In the primary embodiment of this invention, piezoceramic fibers are oriented parallel to the direction of longitudinal displacement of the actuators so that application of drive voltage causes the actuator to flatten, producing maximum motion. Actuator motion can be transmitted to the optical fiber by use of hinges and clamp blocks. In the original application of this invention, the optical fiber contains a Bragg grating and the purpose of the controlled stretching of the fiber is to tune the grating as part of a small, lightweight, mode-hop-free, rapidly tunable laser for demodulating strain in Bragg-grating strain-measurement optical fibers attached to structures. The invention could also be used to apply controllable tensile force or displacement to an object other than an optical fiber.

Optimization design of high power ultrasonic circular ring radiator in coupled vibration.

Science.gov (United States)

Xu, Long; Lin, Shuyu; Hu, Wenxu

2011-10-01

This paper presents a new high power ultrasonic (HPU) radiator, which consists of a transducer, an ultrasonic horn, and a metal circular ring. Both the transducer and horn in longitudinal vibrations are used to drive a metal circular ring in a radial-axial coupled vibration. This coupled vibration cannot only generate ultrasound in both the radial and axial directions, but also focus the ultrasound inside the circular ring. Except for the radial-axial coupled vibration mode, the third longitudinal harmonic vibration mode with relative large vibration amplitude is also detected, which can be used as another operation mode. Overall, the HPU with these two vibration modes should have good potential to be applied in liquid processing, such as sonochemistry, ultrasonic cleaning, and Chinese herbal medicine extraction. Copyright © 2011 Elsevier B.V. All rights reserved.

Stretch strength of Al-Li alloy sheet

Energy Technology Data Exchange (ETDEWEB)

Sato, K.; Sawa, Y.; Yokoyama, T.; Fujimoto, S. [Science Univ. of Tokyo (Japan). Dept. of Mech. Eng.; Sakamoto, T. [Kobe Steel Works, Tokyo (Japan)

1998-07-01

Stretch test on Al-Li alloy sheet was carried out in stretch rate of 0.01 to 0.2 mm/sec. The limiting stretch depth was measured in various conditions and the following results were obtained. (1) Stretch rate does not affect the limiting stretch depth of Al-Li alloy. (2) The limiting stretch depth is increased with increase of the profile radius. (3) Strain hardening exponent(n-value) and r-value of Lankford do not affect the limiting stretch depth. (4) Rapture pattern in stretch test of Al is {alpha} type rapture and that of Al-Li alloy is straight line type rapture. (orig.) 4 refs.

Injection into the LNLS UVX electron storage ring

International Nuclear Information System (INIS)

Lin, Liu

1991-01-01

To inject the 1.15 GeV electron storage ring - UVX - a beam from a linear accelerator - MAIRA - is used. The electrons are injected and accumulated at low energy (100MeV) until the nominal current of 100 mA is reached and than are ramped to the nominal energy. A study on a conventional injection scheme has been carried out. Two injection modes are investigated: injection with the phase ellipse parameters matched and mismatched to the ring's acceptance. The mismatched mode is optimized to fit the maximum of the injected beam into the acceptance

Width dependent transition of quantized spin-wave modes in Ni80Fe20 square nanorings

Science.gov (United States)

Banerjee, Chandrima; Saha, Susmita; Barman, Saswati; Rousseau, Olivier; Otani, YoshiChika; Barman, Anjan

2014-10-01

We investigated optically induced ultrafast magnetization dynamics in square shaped Ni80Fe20 nanorings with varying ring width. Rich spin-wave spectra are observed whose frequencies showed a strong dependence on the ring width. Micromagnetic simulations showed different types of spin-wave modes, which are quantized upto very high quantization number. In the case of widest ring, the spin-wave mode spectrum shows quantized modes along the applied field direction, which is similar to the mode spectrum of an antidot array. As the ring width decreases, additional quantization in the azimuthal direction appears causing mixed modes. In the narrowest ring, the spin-waves exhibit quantization solely in azimuthal direction. The different quantization is attributed to the variation in the internal field distribution for different ring width as obtained from micromagnetic analysis and supported by magnetic force microscopy.

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.

Azimuthal decomposition of optical modes

CSIR Research Space (South Africa)

Dudley, Angela L

2012-07-01

Full Text Available This presentation analyses the azimuthal decomposition of optical modes. Decomposition of azimuthal modes need two steps, namely generation and decomposition. An azimuthally-varying phase (bounded by a ring-slit) placed in the spatial frequency...

Fulltext PDF

Indian Academy of Sciences (India)

Administrator

... respectively, in poly-2-cynoaniline. The peak at 1455 cm–1 is attributed to C–N stretching of nitrile group attached to the benzene ring. The bands at. 1120 and 762 cm–1 can be attributed to the in-plane and out-of-plane C–H bending vibration modes, respectively. The 1331 cm–1 band may be assigned to C–C stretching.

Atomic Stretch: Optimally bounded real-time stretching and beyond

DEFF Research Database (Denmark)

Jensen, Rasmus Ramsbøl; Nielsen, Jannik Boll

2016-01-01

Atomic Stretch is a plugin for your preferred Adobe video editing tool, allowing real-time smooth and optimally bounded retarget-ting from and to any aspect ratio. The plugin allows preserving of high interest pixels through a protected region, attention redirection through color-modification, co......Atomic Stretch is a plugin for your preferred Adobe video editing tool, allowing real-time smooth and optimally bounded retarget-ting from and to any aspect ratio. The plugin allows preserving of high interest pixels through a protected region, attention redirection through color...

Generation of linearly polarized orbital angular momentum modes in a side-hole ring fiber with tunable topology numbers.

Science.gov (United States)

Han, Ya; Liu, Yan-Ge; Huang, Wei; Wang, Zhi; Guo, Jun-Qi; Luo, Ming-Ming

2016-07-25

A refractive index (RI) tunable functional materials infiltrated side-hole ring fiber (SHRF) is proposed to generate 10 LP OAM states with 6 topology numbers. On the basis of perturbation theory, the basis of the SHRF is demonstrated to be the LP modes. After a fixed propagation distance of 0.03 m, 0.009 m and 0.012 m, the phase difference between the odd and even LP11x, LP21x,y, LP31x,y modes in the SHRF accumulate to ± π/2 respectively with na ranging from 1.412 to 1.44. Correspondingly, the output states are OAM ± 1x, OAM ± 2x,y, OAM ± 3x,y with a bandwidth of 380 nm, 100 nm and 80 nm respectively. The proposed fiber is easy to be fabricated with the mature fiber drawing technology and could facilitate the realization of all fiber based OAM system.

A vortex ring interacting with a vortex filament and its deformation near the two-dimensional stagnation point

International Nuclear Information System (INIS)

Kiya, M.; Sato, T.

1986-01-01

In this paper the interaction between vortex filaments and vortex rings and the deformation of vortex rings near the two-dimensional stagnation point are simulated by a three-dimensional vortex method. The two problems are respectively concerned with the effect of free-stream turbulence on turbulent plane mixing layers and the production of turbulence by the vortex stretching near saddles associated with large-scale coherent structures. The authors assume that the first step to understand the free-stream turbulence effect is to study the interaction between a vortex ring and a vortex filament and that the process of deformation of a vortex ring gives us a clue to understand physical processes occurring near the saddles

Integrated Microwave Photonic Isolators: Theory, Experimental Realization and Application in a Unidirectional Ring Mode-Locked Laser Diode

Directory of Open Access Journals (Sweden)

Martijn J.R. Heck

2015-09-01

Full Text Available A novel integrated microwave photonic isolator is presented. It is based on the timed drive of a pair of optical modulators, which transmit a pulsed or oscillating optical signal with low loss, when driven in phase. A signal in the reverse propagation direction will find the modulators out of phase and, hence, will experience high loss. Optical and microwave isolation ratios were simulated to be in the range up to 10 dB and 20 dB, respectively, using parameters representative for the indium phosphide platform. The experimental realization of this device in the hybrid silicon platform showed microwave isolation in the 9 dB–22 dB range. Furthermore, we present a design study on the use of these isolators inside a ring mode-locked laser cavity. Simulations show that unidirectional operation can be achieved, with a 30–50-dB suppression of the counter propagating mode, at limited driving voltages. The potentially low noise and feedback-insensitive operation of such a laser makes it a very promising candidate for use as on-chip microwave or comb generators.

How to determine local stretching and tension in a flow-stretched DNA molecule

DEFF Research Database (Denmark)

Pedersen, Jonas Nyvold; Marie, Rodolphe; Kristensen, Anders

2016-01-01

We determine the nonuniform stretching of and tension in amega base pairs-long fragment of deoxyribonucleic acid (DNA) that is flow stretched in a nanofluidic chip. We use no markers, do not know the contour length of the DNA, and do not have the full DNA molecule inside our field of view. Instead......, we analyze the transverse thermal motion of the DNA. Tension at the center of the DNA adds up to 16 pN, giving almost fully stretched DNA. This method was devised for optical mapping of DNA, specifically, DNA denaturation patterns. It may be useful also for other studies, e.g., DNA......-protein interactions, specifically, their tension dependence. Generally, wherever long strands of DNA—e.g., native DNA extracted from human cells or bacteria—must be stretched with ease for inspection, this method applies....

Analysis of a filament stretching rheometer

DEFF Research Database (Denmark)

Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

1996-01-01

A finite element analysis of the stretching filament rheometer of Tirtaadmadja and Sridhar (1993) is presenetd. Simulations of the stretching of a filament of the polymet test solution, fluid A, between two plates are shown.......A finite element analysis of the stretching filament rheometer of Tirtaadmadja and Sridhar (1993) is presenetd. Simulations of the stretching of a filament of the polymet test solution, fluid A, between two plates are shown....

Investigation of an He-Ne laser generating a beam with a ring-shaped intensity distribution

Energy Technology Data Exchange (ETDEWEB)

Sukhanov, I I; Troitskii, IU V; Iakushkin, S V

1987-02-01

The paper examines an He-Ne laser regime with the simultaneous generation of TEM(01) and TEM(10) modes, forming a beam with a ring-shaped intensity distribution with total suppression of the TEM(00) mode. The ratio of the intensity at the ring crest to the intensity at the axis reached a value of 200 and was limited by scattering in the optical components of the resonator. A regime of mutual frequency locking of the TEM(01) and TEM(10) modes was achieved with total spatial coherence of the ring-shaped beam. 14 references.

EFFICACY OF MODIFIED PROPRIOCEPTIVE NEUROMUSCULAR FACILITATION STRETCHING WITH CRYOTHERAPY OVER MANUAL PASSIVE STRETCHING WITH CRYOTHERAPY ON HAMSTRING FLEXIBILITY

Directory of Open Access Journals (Sweden)

Shamik Bhattacharjee

2016-04-01

Full Text Available Background: Healthy individuals, to ease and accomplish their activities of daily living they need flexible body without any tightness in the muscles, particularly those used for a definite function. Cooling soft tissues in a lengthened position after stretching has been shown to promote more lasting increases in soft tissue length and minimize post stretch muscle soreness. There are less documented studies which compared modified proprioceptive neuromuscular facilitation (PNF stretch over passive manual stretch with cold application commonly after the interventions. Methods: Thirty high school going healthy students were divided into two groups- Group I received Passive Manual stretching (n=15 and Group II received modified PNF stretching (n=15 and both groups received cold application after the interventions for 10 minutes commonly for 5 days. ROM was taken on day 1, day 5 and day 7. Results: After day 7, Group II with Modified PNF stretching along with cold application showed a significant increase in range of motion tested with active knee extension test (AKET. Conclusion: Modified PNF stretching is considered to be the effective intervention in increasing and maintaining ROM in AKET over passive manual stretching with cold applications commonly after the interventions.

On the structure and normal modes of hydrogenated Ti-fullerene compounds

Energy Technology Data Exchange (ETDEWEB)

Tlahuice-Flores, Alfredo, E-mail: tlahuicef@yahoo.com [Universidad Nacional Autonoma de Mexico, Instituto de Fisica (Mexico); Mejia-Rosales, Sergio, E-mail: sergio.mejiars@uanl.edu.mx [Universidad Autonoma de Nuevo Leon, CICFIM-Facultad de Ciencias Fisico Matematicas, and Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia (Mexico); Galvan, Donald H., E-mail: donald@cnyn.unam.mx [Centro de Nanociencias y Nanotecnologia-Universidad Nacional Autonoma de Mexico (Mexico)

2012-08-15

When titanium covers a C{sub 60} core, the metal atoms may suppress the fullerene's capacity of storing hydrogen, depending on the number of Ti atoms covering the C{sub 60} framework, the Ti-C binding energy, and diffusion barriers. In this article, we study the structural and vibrational properties of the C{sub 60}TiH{sub n} (n = 2, 4, 6, and 8) and C{sub 60}Ti{sub 6}H{sub 48} compounds. The IR spectra of C{sub 60}TiH{sub n} compounds have a maximum attributable to the Ti-H stretching mode, which shifts to lower values in the structures with n = 4, 8, while their Raman spectra show two peaks corresponding to the stretching modes of H{sub 2} molecules at apical and azimuthal positions. On the other hand, the IR spectrum of C{sub 60}Ti{sub 6}H{sub 48} shows an intense peak due to the Ti-H in-phase stretching mode, while its Raman spectrum has a maximum attributed to the pentagonal pinch of the C{sub 60} core. Finally, we have found that the presence of one apical H{sub 2} molecule enhances the pentagonal pinch mode, becoming the maximum in the Raman spectrum.Graphical Abstract.

Radial mode structure of curvature-driven instabilities in EBT

International Nuclear Information System (INIS)

Spong, D.A.

1983-01-01

Viewgraphs describe the theoretical treatment of the radial mode structure of plasma instabilities in the Elmo Bumpy Torus. The calculation retains nonlocal structure of the modes, connects inner and outer ring regions together, uses a self-consistent finite β, includes the relativistic effects for the hot electron ring, and examines a wide range of parameters

Measuring a Fiber-Optic Delay Line Using a Mode-Locked Laser

Science.gov (United States)

Tu, Meirong; McKee, Michael R.; Pak, Kyung S.; Yu, Nan

2010-01-01

The figure schematically depicts a laboratory setup for determining the optical length of a fiber-optic delay line at a precision greater than that obtainable by use of optical time-domain reflectometry or of mechanical measurement of length during the delay-line-winding process. In this setup, the delay line becomes part of the resonant optical cavity that governs the frequency of oscillation of a mode-locked laser. The length can then be determined from frequency-domain measurements, as described below. The laboratory setup is basically an all-fiber ring laser in which the delay line constitutes part of the ring. Another part of the ring - the laser gain medium - is an erbium-doped fiber amplifier pumped by a diode laser at a wavelength of 980 nm. The loop also includes an optical isolator, two polarization controllers, and a polarizing beam splitter. The optical isolator enforces unidirectional lasing. The polarization beam splitter allows light in only one polarization mode to pass through the ring; light in the orthogonal polarization mode is rejected from the ring and utilized as a diagnostic output, which is fed to an optical spectrum analyzer and a photodetector. The photodetector output is fed to a radio-frequency spectrum analyzer and an oscilloscope. The fiber ring laser can generate continuous-wave radiation in non-mode-locked operation or ultrashort optical pulses in mode-locked operation. The mode-locked operation exhibited by this ring is said to be passive in the sense that no electro-optical modulator or other active optical component is used to achieve it. Passive mode locking is achieved by exploiting optical nonlinearity of passive components in such a manner as to obtain ultra-short optical pulses. In this setup, the particular nonlinear optical property exploited to achieve passive mode locking is nonlinear polarization rotation. This or any ring laser can support oscillation in multiple modes as long as sufficient gain is present to overcome

Examining flow-flame interaction and the characteristic stretch rate in vortex-driven combustion dynamics using PIV and numerical simulation

KAUST Repository

Hong, Seunghyuck; Speth, Raymond L.; Shanbhogue, Santosh J.; Ghoniem, Ahmed F.

2013-01-01

In this paper, we experimentally investigate the combustion dynamics in lean premixed flames in a laboratory scale backward-facing step combustor in which flame-vortex driven dynamics are observed. A series of tests was conducted using propane/hydrogen/air mixtures for various mixture compositions at the inlet temperature ranging from 300K to 500K and at atmospheric pressure. Pressure measurements and high speed particle image velocimetry (PIV) are used to generate pressure response curves and phase-averaged vorticity and streamlines as well as the instantaneous flame front, respectively, which describe unsteady flame and flow dynamics in each operating regime. This work was motivated in part by our earlier study where we showed that the strained flame consumption speed Sc can be used to collapse the pressure response curves over a wide range of operating conditions. In previous studies, the stretch rate at which Sc was computed was determined by trial and error. In this study, flame stretch is estimated using the instantaneous flame front and velocity field from the PIV measurement. Independently, we also use computed strained flame speed and the experimental data to determine the characteristic values of stretch rate near the mode transition points at which the flame configuration changes. We show that a common value of the characteristic stretch rate exists across all the flame configurations. The consumption speed computed at the characteristic stretch rate captures the impact of different operating parameters on the combustor dynamics. These results suggest that the unsteady interactions between the turbulent flow and the flame dynamics can be encapsulated in the characteristic stretch rate, which governs the critical flame speed at the mode transitions and thereby plays an important role in determining the stability characteristics of the combustor. © 2013 The Combustion Institute.

Effect of CH stretching excitation on the reaction dynamics of F + CHD{sub 3} → DF + CHD{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Yang, Jiayue; Zhang, Dong; Chen, Zhen; Jiang, Bo [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, 457 Zhongshan Road, Dalian, Liaoning 116023 (China); Blauert, Florian [Dynamics at Surfaces, Faculty of Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen (Germany); Dai, Dongxu; Wu, Guorong, E-mail: wugr@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn; Zhang, Donghui; Yang, Xueming, E-mail: wugr@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, 457 Zhongshan Road, Dalian, Liaoning 116023 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2015-07-28

The vibrationally excited reaction of F + CHD{sub 3}(ν{sub 1} = 1) → DF + CHD{sub 2} at a collision energy of 9.0 kcal/mol is investigated using the crossed-beams and time-sliced velocity map imaging techniques. Detailed and quantitative information of the CH stretching excitation effects on the reactivity and dynamics of the title reaction is extracted with the help of an accurate determination of the fraction of the excited CHD{sub 3} reagent in the crossed-beam region. It is found that all vibrational states of the CHD{sub 2} products observed in the ground-state reaction, which mainly involve the excitation of the umbrella mode of the CHD{sub 2} products, are severely suppressed by the CH stretching excitation. However, there are four additional vibrational states of the CHD{sub 2} products appearing in the excited-state reaction which are not presented in the ground-state reaction. These vibrational states either have the CH stretching excitation retained or involve one quantum excitation in the CH stretching and the excitation of the umbrella mode. Including all observed vibrational states, the overall cross section of the excited-state reaction is estimated to be 66.6% of that of the ground-state one. Experimental results also show that when the energy of CH stretching excitation is released during the reaction, it is deposited almost exclusively as the rovibrational energy of the DF products, with little portion in the translational degree of freedom. For vibrational states of the CHD{sub 2} products observed in both ground- and excited-state reactions, the CH stretching excitation greatly suppresses the forward scattered products, causing a noticeable change in the product angular distributions.

Examining flow-flame interaction and the characteristic stretch rate in vortex-driven combustion dynamics using PIV and numerical simulation

KAUST Repository

Hong, Seunghyuck

2013-08-01

In this paper, we experimentally investigate the combustion dynamics in lean premixed flames in a laboratory scale backward-facing step combustor in which flame-vortex driven dynamics are observed. A series of tests was conducted using propane/hydrogen/air mixtures for various mixture compositions at the inlet temperature ranging from 300K to 500K and at atmospheric pressure. Pressure measurements and high speed particle image velocimetry (PIV) are used to generate pressure response curves and phase-averaged vorticity and streamlines as well as the instantaneous flame front, respectively, which describe unsteady flame and flow dynamics in each operating regime. This work was motivated in part by our earlier study where we showed that the strained flame consumption speed Sc can be used to collapse the pressure response curves over a wide range of operating conditions. In previous studies, the stretch rate at which Sc was computed was determined by trial and error. In this study, flame stretch is estimated using the instantaneous flame front and velocity field from the PIV measurement. Independently, we also use computed strained flame speed and the experimental data to determine the characteristic values of stretch rate near the mode transition points at which the flame configuration changes. We show that a common value of the characteristic stretch rate exists across all the flame configurations. The consumption speed computed at the characteristic stretch rate captures the impact of different operating parameters on the combustor dynamics. These results suggest that the unsteady interactions between the turbulent flow and the flame dynamics can be encapsulated in the characteristic stretch rate, which governs the critical flame speed at the mode transitions and thereby plays an important role in determining the stability characteristics of the combustor. © 2013 The Combustion Institute.

Flexibility and stretching physiology : responses and adaptations to different stretching intensities.

OpenAIRE

Freitas, Sandro Remo Martins Neves Ramos

2014-01-01

Doutoramento em Motricidade Humana, especialidade de Biomecânica Research and reported literature regarding the conceptual, methodological, and training effects of stretching with different intensities are scarce. The purposes of this thesis were to: i) explore and develop methodological conditions to achieve the second purpose (studies: 1 to 3); ii) characterize the acute and chronic effects induced by different stretching intensities on skeletal muscle and joint mechanical properti...

Yb-doped rod-type photonic crystal fibers for single-mode amplification

DEFF Research Database (Denmark)

Poli, Frederica; Passaro, Davide; Cucinotta, Annamaria

2009-01-01

The competition among the guided modes in rod-type photonic crystal fibers with a low refractive index ring in the Yb-doped core is investigated with an amplifier model to demonstrate the effective higher-order mode suppression.......The competition among the guided modes in rod-type photonic crystal fibers with a low refractive index ring in the Yb-doped core is investigated with an amplifier model to demonstrate the effective higher-order mode suppression....

Lattice design for the CEPC double ring scheme

Science.gov (United States)

Wang, Yiwei; Su, Feng; Bai, Sha; Zhang, Yuan; Bian, Tianjian; Wang, Dou; Yu, Chenghui; Gao, Jie

2018-01-01

A future Circular Electron Positron Collider (CEPC) has been proposed by China with the main goal of studying the Higgs boson. Its baseline design, chosen on the basis of its performance, is a double ring scheme; an alternative design is a partial double ring scheme which reduces the budget while maintaining an adequate performance. This paper will present the collider ring lattice design for the double ring scheme. The CEPC will also work as a W and a Z factory. For the W and Z modes, except in the RF region, compatible lattices were obtained by scaling down the magnet strength with energy.

EFFECTIVENESS OF PNF STRETCHING AND CYCLIC STRETCHING OF CALF TIGHTNESS ON COLLEGE GOING GIRLS

Directory of Open Access Journals (Sweden)

Ashlesha Sirari

2015-06-01

Full Text Available Background: Flexibility helps with injury prevention, the reduction of soreness following a workout, and a general sense of well-being. There are different stretching techniques and protocols for improvements in calf extensibility and flexibility. The purpose of the study was to investigate the effectiveness of two techniques i.e. CYCLIC and PNF stretching which improves calf flexibility. This study was done to find the effectiveness of calf Cyclic and PNF stretching technique to improve calf flexibility. Methods: 30 subjects with age group 21-22 years were randomly allocated to 2 groups equally. Group 1(n=15 were given CYCLIC and group 2(n=15 were given PNF stretching technique. Plantar flexion was used to measure the calf tightness which was done before and after the treatment. Treatment was given for 7 days and on the 7th day the calf tightness was again measured. Results: The mean difference of the CYCLIC is 4.6 and mean difference of PNF is 4.7 which indicate that CYCLIC and PNF both are effective to improve calf flexibility but PNF is more effective than CYCLIC to improve calf flexibility. Conclusion: The neurophysiological basis of PNF, stating that the excitatory efficient of the neuromuscular spindle or the inhibitory afferent of the Golgi tendon organ (GTO or both are responsible for the effects. During PNF stretch and isometric contraction of stretched agonists for extended period may cause activation of its neuromuscular spindle. The increase in tension created during the isometric contraction of the pre – lengthened agonist contracts concentrically. Both the fascia & the spindle of the agonist adjust to the nearly lengthened position. These impulses travel via causing post synaptic inhibition of the motor neuron to agonist increasing the tension from the GTO. These impulses can override the impulses coming from the neuromuscular spindles arousing the muscle to reflexly resist to the change in length, thus helping in lengthening

Vibrational Characteristics of ring-type ultrasonic motor stator using ESPI

International Nuclear Information System (INIS)

Jung, Hyun Kyu; Paik, Sung Hoon; Kim, Seung Ho; Park, Ki Jun; Wang, Young Sung

2001-01-01

A stator of ring-type ultrasonic motor composed of the piezoelectric ceramic and the elastic metal was made to generate the travelling wave. Vibrational behavior of the stator was simulated by a finite element analysis using ATILA program and was measured by the electronic speckle pattern interferometry (ESPI) method. The resonance frequencies and vibration modes were analysed depending upon the comparison between the finite element analysis and ESPI measurement. The optimal vibration mode and frequency was estimated to be 7th resonant mode which was corresponded to the measured frequency of 39 KHz. It could be concluded that this fabricated stator can be applied for ring-type ultrasonic motor.

Effect of antisymmetric C–H stretching excitation on the dynamics of O({sup 1}D) + CH{sub 4} → OH + CH{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Pan, Huilin; Yang, Jiayue; Zhang, Dong; Shuai, Quan; Jiang, Bo [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023 (China); Dai, Dongxu; Wu, Guorong, E-mail: wugr@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn; Yang, Xueming, E-mail: wugr@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2014-04-21

The effect of antisymmetric C–H stretching excitation of CH{sub 4} on the dynamics and reactivity of the O({sup 1}D) + CH{sub 4} → OH + CD{sub 3} reaction at the collision energy of 6.10 kcal/mol has been investigated using the crossed-beam and time-sliced velocity map imaging techniques. The antisymmetric C–H stretching mode excited CH{sub 4} molecule was prepared by direct infrared excitation. From the measured images of the CH{sub 3} products with the infrared laser on and off, the product translational energy and angular distributions were derived for both the ground and vibrationally excited reactions. Experimental results show that the vibrational energy of the antisymmetric stretching excited CH{sub 4} reagent is channeled exclusively into the vibrational energy of the OH co-products and, hence, the OH products from the excited-state reaction are about one vibrational quantum hotter than those from the ground-state reaction, and the product angular distributions are barely affected by the vibrational excitation of the CH{sub 4} reagent. The reactivity was found to be suppressed by the antisymmetric stretching excitation of CH{sub 4} for all observed CH{sub 3} vibrational states. The degree of suppression is different for different CH{sub 3} vibrational states: the suppression is about 40%–60% for the ground state and the umbrella mode excited CH{sub 3} products, while for the CH{sub 3} products with one quantum symmetric stretching mode excitation, the suppression is much less pronounced. In consequence, the vibrational state distribution of the CH{sub 3} product from the excited-state reaction is considerably different from that of the ground-state reaction.

Width dependent transition of quantized spin-wave modes in Ni{sub 80}Fe{sub 20} square nanorings

Energy Technology Data Exchange (ETDEWEB)

Banerjee, Chandrima; Saha, Susmita; Barman, Saswati; Barman, Anjan, E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Rousseau, Olivier [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Otani, YoshiChika [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

2014-10-28

We investigated optically induced ultrafast magnetization dynamics in square shaped Ni{sub 80}Fe{sub 20} nanorings with varying ring width. Rich spin-wave spectra are observed whose frequencies showed a strong dependence on the ring width. Micromagnetic simulations showed different types of spin-wave modes, which are quantized upto very high quantization number. In the case of widest ring, the spin-wave mode spectrum shows quantized modes along the applied field direction, which is similar to the mode spectrum of an antidot array. As the ring width decreases, additional quantization in the azimuthal direction appears causing mixed modes. In the narrowest ring, the spin-waves exhibit quantization solely in azimuthal direction. The different quantization is attributed to the variation in the internal field distribution for different ring width as obtained from micromagnetic analysis and supported by magnetic force microscopy.

The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects.

LENUS (Irish Health Repository)

O'Sullivan, Kieran

2009-01-01

BACKGROUND: Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls. METHODS: A randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM). 18 previously injured individuals and 18 uninjured controls participated. On both days, four measurements of PKE ROM were recorded: (1) at baseline; (2) after warm-up; (3) after stretch (static or dynamic) and (4) after a 15-minute rest. Participants carried out both static and dynamic stretches, but on different days. Data were analysed using Anova. RESULTS: Across both groups, there was a significant main effect for time (p < 0.001). PKE ROM significantly increased with warm-up (p < 0.001). From warm-up, PKE ROM further increased with static stretching (p = 0.04) but significantly decreased after dynamic stretching (p = 0.013). The increased flexibility after warm-up and static stretching reduced significantly (p < 0.001) after 15 minutes of rest, but remained significantly greater than at baseline (p < 0.001). Between groups, there was no main effect for group (p = 0.462), with no difference in mean PKE ROM values at any individual stage of the protocol (p > 0.05). Using ANCOVA to adjust for the non-significant (p = 0.141) baseline difference between groups, the previously injured group demonstrated a greater response to warm-up and static stretching, however this was not statistically significant (p = 0.05). CONCLUSION: Warm-up significantly increased hamstring flexibility. Static stretching also increased hamstring flexibility, whereas dynamic did not, in agreement with previous findings on uninjured controls. The effect of warm-up and static stretching on flexibility was greater in those with reduced

Amplitude-modulated fiber-ring laser

DEFF Research Database (Denmark)

Caputo, J. G.; Clausen, Carl A. Balslev; Sørensen, Mads Peter

2000-01-01

Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self......-starting of stable solitonic pulses from small random noise, provided the modulation depth is small. The perturbative analysis leads to a nonlinear coupled return map for the amplitude, phase, and position of the soliton pulses circulating in the fiber-ring laser. We established the validity of this approach...

GHz-bandwidth upconversion detector using a unidirectional ring cavity to reduce multilongitudinal mode pump effects

DEFF Research Database (Denmark)

Meng, Lichun; Høgstedt, Lasse; Tidemand-Lichtenberg, Peter

2017-01-01

We demonstrate efficient upconversion of modulated infrared (IR) signals over a wide bandwidth (up to frequencies in excess of 1 GHz) via cavity-enhanced sum-frequency generation (SFG) in a periodically poled LiNbO3. Intensity modulated IR signal is produced by combining beams from two 1547 nm...... narrow-linewidth lasers in a fiber coupler while tuning their wavelength difference down to 10 pm or less. The SFG crystal is placed inside an Nd:YVO4 ring cavity that provides 1064 nm circulating pump powers of up to 150 W in unidirectional operation. Measured Fabry-Perot spectrum at 1064 nm confirms...... the enhanced spectral stability from multiple to single longitudinal mode pumping condition. We describe analytically and demonstrate experimentally the deleterious effects of using a multimode pump to the high-bandwidth RF spectrum of the 630 nm SFG output. Offering enhanced sensitivity without the need...

Continuous-wave singly resonant optical parametric oscillator placed inside a ring laser

DEFF Research Database (Denmark)

Abitan, Haim; Buchhave, Preben

2003-01-01

A cw singly resonant optical parametric oscillator (SRO) was built and placed inside the cavity of a ring laser. The system consists of a diode-end-pumped Nd:YVO4 ring laser with intracavity periodically poled lithium niobate as the nonlinear gain medium of the SRO. When the laser was operated...... in a unidirectional mode, we obtained more than 520 mW of signal power in one beam. When the laser was operated in a bidirectional mode, we obtained 600 mW of signal power (300 mW in two separate beams). The power and the spectral features of the laser in the unidirectional and bidirectional modes were measured while...... the laser was coupled with the SRO. The results show that it is preferable to couple a SRO with a unidirectional ring laser....

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.

Ring power balance observing plasma stability constraints

International Nuclear Information System (INIS)

Campbell, R.B.; Logan, B.G.

1982-01-01

Ring power balance is performed for an E-ring stabilized tandem mirror reactor, taking into account constraints imposed by plasma stability. The two most important criteria are the stability of the core interchange and hot electron interchange modes. The former determines the ring thickness, the latter determines the minimum hot electron temperature; both quantities are important for power balance. The combination of the hot electron interchange constraint and the fact that the barrier density is low places the operating point on the synchrotron dominated branch of power balance. The reference case considered here requires a reasonable 34 MW of heating power deposited in the rings. We also have examined the sensitivity of the required ring power on uncertainties in the numerical coefficients of the stability constraints. We have found that the heating power is strongly affected

EFFECTIVENESS OF PNF STRETCHING VERSUS STATIC STRETCHING ON PAIN AND HAMSTRING FLEXIBILITY FOLLOWING MOIST HEAT IN INDIVIDUALS WITH KNEE OSTEOARTHRITIS

Directory of Open Access Journals (Sweden)

Meena .V

2016-10-01

Full Text Available Background: Osteoarthritis (OA is a degenerative joint disease and one of the major public health problem that causesfunctional impairment and reduced quality of life. To compare the effectiveness of PNF Hold relax stretching versus Static stretching on pain and flexibility of hamstring following moist heat in individuals with knee osteoarthritis. Hamstring tightness is the major problem in knee osteoarthritis individuals. Therefore the need of study is comparing the effectiveness of PNF Hold relax stretching versus static stretching on pain and flexibility of hamstrings following moist heat in knee osteoarthritis participants. Determining the effects of PNF Hold relax stretching versus Static stretching along with moist heat on pain and hamstring flexibility by VAS and Active knee extension range of motion in knee osteoarthritis individuals. Methods: 30 subjects with symptoms of knee osteoarthritis were randomly distributed into 2 groups 15 in each group. PNF Hold relax stretching along with moist heat is compared to Static stretching along with moist heat. Pain was measured by Visual Analogue Scale (VAS and hamstring flexibility by Active knee Extension Range of Motion (AKEROM by universal goniometer. Measurements are taken pre and post intervention. Results: The results indicated PNF Hold relax stretching along with moist heat showed a statistically significant improvement in pain (p<0.05 and improvement in hamstring flexibility (p<0.05 when compared to Static stretching along with moist heat. Conclusion: Subjects with PNF Hold relax stretching along with moist heat showed significant improvement in pain reduction and improving hamstring flexibility than Static stretching along with moist heat.

Endovascular rescue method for undesirably stretched coil.

Science.gov (United States)

Cho, Jae Hoon

2014-10-01

Undesirable detachment or stretching of coils within the parent artery during aneurysm embolization can be related with thrombus formation, which can be caused occlusion of parent artery or embolic event(s). To escape from this situation, several rescue methods have been reported. A case with undesirably stretched coil in which another rescue method was used, is presented. When the stretched coil is still located in the coil delivery microcatheter, the stretched coil can be removed safely using a snare and a handmade monorail microcatheter. After a snare is lodged in the handmade monorail microcatheter, the snare is introduced over the coil delivery micorcatheter and located in the distal part of the stretched coil. After then, the handmade monorail microcatheter captures the stretched coil and the snare as one unit. This technique using a handmade monorail microcatheter and a snare can be a good rescue modality for the undesirably stretched coil, still remained within the coil delivery microcatheter.

Effects of cryogenic temperature and pre-stretching on mechanical properties and deformation characteristics of a peak-aged AA6082 extrusion

Energy Technology Data Exchange (ETDEWEB)

Xu, Zebing [Department of Materials Science and Engineering, NTNU, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Roven, Hans J., E-mail: hans.j.roven@material.ntnu.no [Department of Materials Science and Engineering, NTNU, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Jia, Zhihong [College of Materials Science and Engineering, Chongqing University, 400044 (China)

2017-01-02

Plastic deformation studies of a peak-aged AA6082 alloy by means of tensile tests at 77 K and 295 K, and related microstructure characteristics obtained by Scanning Electron Microscopy (SEM), Electron Backscatter Diffraction (EBSD), Transmission Electron Microscopy (TEM) and Atom Force Microscopy (AFM), revealed new results. A simultaneous improvement in ductility and strength occurred at 77 K, but not at 295 K. A higher work hardening accompanied by a more homogeneous slip mode explained the improved properties at 77 K. Pre-stretching at these two temperatures and subsequent tensile testing at room temperature revealed a marked yield point. However, pre-stretching at 77 K exhibited a slightly higher room temperature yield strength and ductility than the condition pre-stretched at 295 K. Annealing after pre-stretching improved ductility and reduced the magnitude of the yield point. Pre-stretching at 77 K and subsequent annealing introduced somewhat higher strength and ductility as compared to the counterpart pre-stretched at 295 K. The observed mechanical behaviour and associated phenomena were directly linked to microstructure characteristics such as deformation substructure history, slip localization, dislocation density and the precipitate β{sup '} /β{sup ''} ratio.

Mode Selection in Flame-Vortex driven Combustion Instabilities

KAUST Repository

Speth, Ray; Hong, Seung Hyuck; Shanbogue, Santosh; Ghoniem, Ahmed

2011-01-01

is governed by a combustion-related time delay inversely proportional to the flame speed. Our model predicts the transition between distinct operating modes. We introduce non-dimensional parameters characterizing the flame speed and stretch rate, and develop a

The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects

Directory of Open Access Journals (Sweden)

Murray Elaine

2009-04-01

Full Text Available Abstract Background Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls. Methods A randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM. 18 previously injured individuals and 18 uninjured controls participated. On both days, four measurements of PKE ROM were recorded: (1 at baseline; (2 after warm-up; (3 after stretch (static or dynamic and (4 after a 15-minute rest. Participants carried out both static and dynamic stretches, but on different days. Data were analysed using Anova. Results Across both groups, there was a significant main effect for time (p 0.05. Using ANCOVA to adjust for the non-significant (p = 0.141 baseline difference between groups, the previously injured group demonstrated a greater response to warm-up and static stretching, however this was not statistically significant (p = 0.05. Conclusion Warm-up significantly increased hamstring flexibility. Static stretching also increased hamstring flexibility, whereas dynamic did not, in agreement with previous findings on uninjured controls. The effect of warm-up and static stretching on flexibility was greater in those with reduced flexibility post-injury, but this did not reach statistical significance. Further prospective research is required to validate the hypothesis that increased flexibility improves outcomes. Trial Registration ACTRN12608000638336

Coupled-bunch instabilities in the APS ring

International Nuclear Information System (INIS)

Emery, L.

1991-01-01

A study of coupled bunch instabilities for the APS storage ring is presented. The instabilities are driven by the higher-order modes of the fifteen 352-MHz single-cell RF cavities. These modes are modeled using the 2-D cavity program URMEL. The program ZAP is then used to estimate the growth time of the instabilities for an equally-spaced bunch pattern. The cavity modes most responsible for the instabilities will be singles out for damping. 7 refs., 5 tabs

Nanoscale charcoal powder induced saturable absorption and mode-locking of a low-gain erbium-doped fiber-ring laser

International Nuclear Information System (INIS)

Lin, Yung-Hsiang; Chi, Yu-Chieh; Lin, Gong-Ru

2013-01-01

Triturated charcoal nano-powder directly brushed on a fiber connector end-face is used for the first time as a fast saturable absorber for a passively mode-locked erbium-doped fiber-ring laser (EDFL). These dispersant-free charcoal nano-powders with a small amount of crystalline graphene phase and highly disordered carbon structure exhibit a broadened x-ray diffraction peak and their Raman spectrum shows the existence of a carbon related D-band at 1350 cm −1 and the disappearance of the 2D-band peak at 2700 cm −1 . The charcoal nano-powder exhibits a featureless linear absorbance in the infrared region with its linear transmittance of 0.66 nonlinearly saturated at 0.73 to give a ΔT/T of 10%. Picosecond mode-locking at a transform-limited condition of a low-gain EDFL is obtained by using the charcoal nano-powder. By using a commercial EDFA with a linear gain of only 17 dB at the saturated output power of 17.5 dB m required to initiate the saturable absorption of the charcoal nano-powder, the EDFL provides a pulsewidth narrowing from 3.3 to 1.36 ps associated with its spectral linewidth broadening from 0.8 to 1.83 nm on increasing the feedback ratio from 30 to 90%. This investigation indicates that all the carbon-based materials containing a crystalline graphene phase can be employed to passively mode-lock the EDFL, however, the disordered carbon structure inevitably induces a small modulation depth and a large mode-locking threshold, thus limiting the pulsewidth shortening. Nevertheless, the nanoscale charcoal passively mode-locked EDFL still shows the potential to generate picosecond pulses under a relatively low cavity gain. An appropriate cavity design can be used to compensate this defect-induced pulsewidth limitation and obtain a short pulsewidth. (letter)

High resolution spectroscopy of 1,2-difluoroethane in a molecular beam: A case study of vibrational mode-coupling

Science.gov (United States)

Mork, Steven W.; Miller, C. Cameron; Philips, Laura A.

1992-09-01

The high resolution infrared spectrum of 1,2-difluoroethane (DFE) in a molecular beam has been obtained over the 2978-2996 cm-1 spectral region. This region corresponds to the symmetric combination of asymmetric C-H stretches in DFE. Observed rotational fine structure indicates that this C-H stretch is undergoing vibrational mode coupling to a single dark mode. The dark mode is split by approximately 19 cm-1 due to tunneling between the two identical gauche conformers. The mechanism of the coupling is largely anharmonic with a minor component of B/C plane Coriolis coupling. Effects of centrifugal distortion along the molecular A-axis are also observed. Analysis of the fine structure identifies the dark state as being composed of C-C torsion, CCF bend, and CH2 rock. Coupling between the C-H stretches and the C-C torsion is of particular interest because DFE has been observed to undergo vibrationally induced isomerization from the gauche to trans conformer upon excitation of the C-H stretch.

Transverse intrinsic localized modes in monatomic chain and in graphene

Energy Technology Data Exchange (ETDEWEB)

Hizhnyakov, V. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Klopov, M. [Department of Physics, Faculty of Science, Tallinn University of Technology, Ehitajate 5, 19086 Tallinn (Estonia); Shelkan, A., E-mail: shell@ut.ee [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia)

2016-03-06

In this paper an analytical and numerical study of anharmonic vibrations of monatomic chain and graphene in transverse (perpendicular) with respect to the chain/plane direction is presented. Due to the lack of odd anharmonicities and presence of hard quartic anharmonicity for displacements in this direction, there may exist localized anharmonic transverse modes with the frequencies above the spectrum of the corresponding phonons. Although these frequencies are in resonance with longitudinal (chain) or in-plane (graphene) phonons, the modes can decay only due to a weak anharmonic process. Therefore the lifetime of these vibrations may be very long. E.g. in the chain, according to our theoretical and numerical calculations it may exceed 10{sup 10} periods. We call these vibrations as transverse intrinsic localized modes. - Highlights: • In a stretched monatomic chain, long-living nonlinear transverse localized modes may exist. • Transverse vibrations of a chain slowly decay due to creation of longitudinal phonons. • Lifetime of transverse vibrations of a chain may exceed billion periods of vibrations. • In stretched graphene, long-living out-of-plain localized vibrations may exist.

Dynamic Contractility and Efficiency Impairments in Stretch-Shortening Cycle Are Stretch-Load-Dependent After Training-Induced Muscle Damage

NARCIS (Netherlands)

Vaczi, Mark; Racz, Levente; Hortobagyi, Tibor; Tihanyi, Jozsef

Vaczi, M, Racz, L, Hortobagyi, T, and Tihanyi, J. Dynamic contractility and efficiency impairments in stretch-shortening cycle are stretch-load-dependent after training-induced muscle damage. J Strength Cond Res 27(8): 2171-2179, 2013To determine the acute task and stretch-load dependency of

Entanglement of distant superconducting quantum interference device rings

International Nuclear Information System (INIS)

Zukarnain, Z Ahmad; Konstadopoulou, A; Vourdas, A; Migliore, R; Messina, A

2005-01-01

We consider two distant mesoscopic SQUID rings, approximated with two-level systems, interacting with two-mode microwaves. The Hamiltonian of the system is used to calculate its time evolution. The cases with microwaves which at t = 0 are in separable states (classically correlated) or entangled states (quantum mechanically correlated) are studied. It is shown that the Josephson currents in the two SQUID rings are also correlated

Biaxial stretching of film principles and applications

CERN Document Server

Demeuse, M T

2011-01-01

Biaxial (having two axes) stretching of film is used for a range of applications and is the primary manufacturing process by which products are produced for the food packaging industry. Biaxial stretching of film: principles and applications provides an overview of the manufacturing processes and range of applications for biaxially stretched films. Part one reviews the fundamental principles of biaxial stretching. After an introductory chapter which defines terms, chapters discuss equipment design and requirements, laboratory evaluations, biaxial film structures and typical industrial processes for the biaxial orientation of films. Additional topics include post production processing of biaxially stretched films, the stress-strain behaviour of poly(ethylene terephthalate) and academic investigations of biaxially stretched films. Part two investigates the applications of biaxial films including fresh cut produce, snack packaging and product labelling. A final chapter investigates potential future trends for bi...

Universal Linear Motor Driven Leg Press Dynamometer and Concept of Serial Stretch Loading.

Science.gov (United States)

Hamar, Dušan

2015-08-24

Paper deals with backgrounds and principles of universal linear motor driven leg press dynamometer and concept of serial stretch loading. The device is based on two computer controlled linear motors mounted to the horizontal rails. As the motors can keep either constant resistance force in selected position or velocity in both directions, the system allows simulation of any mode of muscle contraction. In addition, it also can generate defined serial stretch stimuli in a form of repeated force peaks. This is achieved by short segments of reversed velocity (in concentric phase) or acceleration (in eccentric phase). Such stimuli, generated at the rate of 10 Hz, have proven to be a more efficient means for the improvement of rate of the force development. This capability not only affects performance in many sports, but also plays a substantial role in prevention of falls and their consequences. Universal linear motor driven and computer controlled dynamometer with its unique feature to generate serial stretch stimuli seems to be an efficient and useful tool for enhancing strength training effects on neuromuscular function not only in athletes, but as well as in senior population and rehabilitation patients.

Plasma confinement in a magnetic field of the internal ring current

International Nuclear Information System (INIS)

Shafranov, Vitaly; Popovich, Paul; Samitov, Marat

2000-01-01

Plasma confinement in compact region surrounding an internal ring current is considered. As the limiting case of large aspect ratio system the cylindrical plasma is considered initially. Analysis of the cylindrical tubular plasma equilibrium and stability against the most dangerous flute (m=0) and kink (m=1) modes revealed the possibility of the MHD stable plasma confined by magnetic field of the internal rod current, with rather peaked plasma pressure and maximal local beta β(γ)=0.4. In case of the toroidal internal ring system an additional external magnetic field creates the boundary separatrix witch limits the plasma volume. The dependence of the plasma pressure profiles, marginally stable with respect to the flute modes, from the shape of the external plasma boundary (separatrix) in such kind closed toroidal systems is investigated. The internal ring system with circular poloidal magnetic mirror, where the ring supports could be placed, is proposed. (author)

A multipole-expanded effective field theory for vortex ring-sound interactions

Science.gov (United States)

Garcia-Saenz, Sebastian; Mitsou, Ermis; Nicolis, Alberto

2018-02-01

The low-energy dynamics of a zero temperature superfluid or of the compressional modes of an ordinary fluid can be described by a simple effective theory for a scalar field — the superfluid `phase'. However, when vortex lines are present, to describe all interactions in a local fashion one has to switch to a magnetic-type dual two-form description, which comes with six degrees of freedom (in place of one) and an associated gauge redundancy, and is thus considerably more complicated. Here we show that, in the case of vortex rings and for bulk modes that are much longer than the typical ring size, one can perform a systematic multipole expansion of the effective action and recast it into the simpler scalar field language. In a sense, in the presence of vortex rings the non-single valuedness of the scalar can be hidden inside the rings, and thus out of the reach of the multipole expansion. As an application of our techniques, we compute by standard effective field theory methods the sound emitted by an oscillating vortex ring.

Correlation between structure and conductivity in stretched Nafion

Science.gov (United States)

Allahyarov, Elshad; Taylor, Philip

2008-03-01

We have used coarse-grained simulation methods to investigate the effect of stretching-induced structure orientation on the proton conductivity of Nafion-like polyelectrolyte membranes. Recent experimental data on the morphology of ionomers describe Nafion as an aggregation of polymeric backbone chains forming elongated objects embedded in a continuous ionic medium. Uniaxial stretching of a recast Nafion film causes a preferential orientation of these objects in the direction of stretching. Our simulations of humid Nafion show that this has a strong effect on the proton conductivity, which is enhanced along the stretching direction, while the conductivity perpendicular to the stretched polymer backbone is strongly reduced. Stretching also causes the perfluorinated side chains to orient perpendicular to the stretching axis. The sulphonate multiplets shrink in diameter as the stretching is increased and show a spatially periodic ordering in their distribution. This in turn affects the distribution of contained water at low water contents. The water forms a continuous network with narrow bridges between small water clusters absorbed in head-group multiplets. We find the morphological changes in the stretched Nafion to be retained upon removal of the uniaxial stress.

Characterization of mechanical behavior of a porcine pulmonary artery strip using a randomized uniaxial stretch and stretch-rate protocol

Directory of Open Access Journals (Sweden)

Criscione John C

2008-01-01

Full Text Available Abstract Background Much of the experimental work in soft tissue mechanics has been focused on fitting approximate relations for specific tissue types from aggregate data on multiple samples of the tissue. Such relations are needed for modeling applications and have reasonable predictability – especially given the natural variance in specimens. There is, however, much theoretical and experimental work to be done in determining constitutive behaviors for particular specimens and tissues. In so doing, it may be possible to exploit the natural variation in tissue ultrastructure – so to relate ultrastructure composition to tissue behavior. Thus, this study focuses on an experimental method for determining constitutive behaviors and illustrates the method with analysis of a porcine pulmonary artery strip. The method characterizes the elastic part of the response (implicitly in terms of stretch and the inelastic part in terms of short term stretch history (i.e., stretch-rate Ht2, longer term stretch history Ht1, and time since the start of testing T. Methods A uniaxial testing protocol with a random stretch and random stretch-rate was developed. The average stress at a particular stretch was chosen as the hyperelastic stress response, and deviation from the mean at this particular stretch is chosen as the inelastic deviation. Multivariable Linear Regression Analysis (MLRA was utilized to verify if Ht2, Ht1, and T are important factors for characterizing the inelastic deviation. For acquiring Ht2 and Ht1, an integral function type of stretch history was employed with time constants chosen from the relaxation spectrum of an identical size strip from the same tissue with the same orientation. Finally, statistical models that characterize the inelasticity were developed at various, nominal values of stretch, and their predictive capability was examined. Results Inelastic deviation from hyperelasticity was high (31% for low stretch and declined

Numerical Analysis of AHSS Fracture in a Stretch-bending Test

Science.gov (United States)

Luo, Meng; Chen, Xiaoming; Shi, Ming F.; Shih, Hua-Chu

2010-06-01

Advanced High Strength Steels (AHSS) are increasingly used in the automotive industry due to their superior strength and substantial weight reduction advantage. However, their limited ductility gives rise to numerous manufacturing issues. One of them is the so-called `shear fracture' often observed on tight radii during stamping processes. Since traditional approaches, such as the Forming Limit Diagram (FLD), are unable to predict this type of fracture, efforts have been made to develop failure criteria that can predict shear fractures. In this paper, a recently developed Modified Mohr-Coulomb (MMC) ductile fracture criterion[1] is adopted to analyze the failure behavior of a Dual Phase (DP) steel sheet during stretch bending operations. The plasticity and ductile fracture of the present sheet are fully characterized by the Hill'48 orthotropic model and the MMC fracture model respectively. Finite Element models with three different element types (3D, shell and plane strain) were built for a Stretch Forming Simulator (SFS) test and numerical simulations with four different R/t ratios (die radius normalized by sheet thickness) were performed. It has been shown that the 3D and shell element models can accurately predict the failure location/mode, the upper die load-displacement responses as well as the wall stress and wrap angle at the onset of fracture for all R/t ratios. Furthermore, a series of parametric studies were conducted on the 3D element model, and the effects of tension level (clamping distance) and tooling friction on the failure modes/locations were investigated.

Dispersion of guided modes in two-dimensional split ring lattices

DEFF Research Database (Denmark)

Hansen, Per Lunnemann; Koenderink, A. Femius

2014-01-01

. This method takes into account all retarded electrodynamic interactions as well as radiation damping self-consistently. As illustration, we analyze the dispersion of plasmon nanorod lattices, and of 2D split ring resonator lattices. Plasmon nanorod lattices support transverse and longitudinal in...

Stretched polygons in a lattice tube

Energy Technology Data Exchange (ETDEWEB)

Atapour, M [Department of Mathematics and Statistics, York University, Toronto, ON M3J 1P3 (Canada); Soteros, C E [Department of Mathematics and Statistics, University of Saskatchewan, Saskatoon, SK S7N 5E6 (Canada); Whittington, S G [Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6 (Canada)], E-mail: atapour@mathstat.yorku.ca, E-mail: soteros@math.usask.ca, E-mail: swhittin@chem.utoronto.ca

2009-08-14

We examine the topological entanglements of polygons confined to a lattice tube and under the influence of an external tensile force f. The existence of the limiting free energy for these so-called stretched polygons is proved and then, using transfer matrix arguments, a pattern theorem for stretched polygons is proved. Note that the tube constraint allows us to prove a pattern theorem for any arbitrary value of f, while without the tube constraint it has so far only been proved for large values of f. The stretched polygon pattern theorem is used first to show that the average span per edge of a randomly chosen n-edge stretched polygon approaches a positive value, non-decreasing in f, as n {yields} {infinity}. We then show that the knotting probability of an n-edge stretched polygon confined to a tube goes to one exponentially as n {yields} {infinity}. Thus as n {yields} {infinity} when polygons are influenced by a force f, no matter its strength or direction, topological entanglements, as defined by knotting, occur with high probability. (fast track communication)

Stretched polygons in a lattice tube

International Nuclear Information System (INIS)

Atapour, M; Soteros, C E; Whittington, S G

2009-01-01

We examine the topological entanglements of polygons confined to a lattice tube and under the influence of an external tensile force f. The existence of the limiting free energy for these so-called stretched polygons is proved and then, using transfer matrix arguments, a pattern theorem for stretched polygons is proved. Note that the tube constraint allows us to prove a pattern theorem for any arbitrary value of f, while without the tube constraint it has so far only been proved for large values of f. The stretched polygon pattern theorem is used first to show that the average span per edge of a randomly chosen n-edge stretched polygon approaches a positive value, non-decreasing in f, as n → ∞. We then show that the knotting probability of an n-edge stretched polygon confined to a tube goes to one exponentially as n → ∞. Thus as n → ∞ when polygons are influenced by a force f, no matter its strength or direction, topological entanglements, as defined by knotting, occur with high probability. (fast track communication)

Ultrafast optical responses of {beta}-carotene and lycopene probed by sub-20-fs time-resolved coherent spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Fujiwara, M.; Sugisaki, M. [CREST-JST and Department of Physics, Osaka City University, Osaka 558-8585 (Japan); Gall, A.; Robert, B. [CEA, Institut de Biologie et Technologies de Saclay, and CNRS, Gif-sur-Yvette F-91191 (France); Cogdell, R.J. [IBLS, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow G12 8QQ, Scotland (United Kingdom); Hashimoto, H., E-mail: hassy@sci.osaka-cu.ac.j [CREST-JST and Department of Physics, Osaka City University, Osaka 558-8585 (Japan)

2009-12-15

We investigate how structural distortions in carotenoid cause decoherences of its high-frequency vibrational modes by applying the sub-20-fs time-resolved transient grating spectroscopy to {beta}-carotene and lycopene. The results indicate that the C=C central stretching mode shows significant loss of coherence under the effects of the steric hindrance between {beta}-ionone ring and polyene backbone, whereas the other high-frequency modes do not show such dependency on the structural distortions.

Ultrafast optical responses of β-carotene and lycopene probed by sub-20-fs time-resolved coherent spectroscopy

International Nuclear Information System (INIS)

Fujiwara, M.; Sugisaki, M.; Gall, A.; Robert, B.; Cogdell, R.J.; Hashimoto, H.

2009-01-01

We investigate how structural distortions in carotenoid cause decoherences of its high-frequency vibrational modes by applying the sub-20-fs time-resolved transient grating spectroscopy to β-carotene and lycopene. The results indicate that the C=C central stretching mode shows significant loss of coherence under the effects of the steric hindrance between β-ionone ring and polyene backbone, whereas the other high-frequency modes do not show such dependency on the structural distortions.

Stable CSR in storage rings: A model

International Nuclear Information System (INIS)

Sannibale, Fernando; Byrd, John M.; Loftsdottir, Agusta; Venturini, Marco; Abo-Bakr, Michael; Feikes, Jorge; Holldack, Karsten; Kuske, Peter; Wustefeld, Godehart; Hubers, Heinz-Willerm; Warnock, Robert

2005-01-01

A comprehensive historical view of the work done on coherent synchrotron radiation (CSR) in storage rings is given in reference [1]. Here we want just to point out that even if the issue of CSR in storage rings was already discussed over 50 years ago, it is only recently that a considerable number of observations have been reported. In fact, intense bursts of coherent synchrotron radiation with a stochastic character were measured in the terahertz frequency range, at several synchrotron light source storage rings [2-8]. It has been shown [8-11], that this bursting emission of CSR is associated with a single bunch instability, usually referred as microbunching instability (MBI), driven by the fields of the synchrotron radiation emitted by the bunch itself. Of remarkably different characteristics was the CSR emission observed at BESSY II in Berlin, when the storage ring was tuned into a special low momentum compaction mode [12, 13]. In fact, the emitted radiation was not the quasi-random bursting observed in the other machines, but a powerful and stable flux of broadband CSR in the terahertz range. This was an important result, because it experimentally demonstrated the concrete possibility of constructing a stable broadband source with extremely high power in the terahertz region. Since the publication of the first successful experiment using the ring as a CSR source [14], BESSY II has regular scheduled user s shifts dedicated to CSR experiments. At the present time, several other laboratories are investigating the possibility of a CSR mode of operation [15-17] and a design for a new ring optimized for CSR is at an advanced stage [18]. In what follows, we describe a model that first accounts for the BESSY II observations and then indicates that the special case of BESSY II is actually quite general and typical when relativistic electron storage rings are tuned for short bunches. The model provides a scheme for predicting and optimizing the performance of ring

Stable CSR in Storage Rings: A Model

International Nuclear Information System (INIS)

Sannibale, F.

2005-01-01

A comprehensive historical view of the work done on coherent synchrotron radiation (CSR) in storage rings is given in reference [1]. Here we want just to point out that even if the issue of CSR in storage rings was already discussed over 50 years ago, it is only recently that a considerable number of observations have been reported. In fact, intense bursts of coherent synchrotron radiation with a stochastic character were measured in the terahertz frequency range, at several synchrotron light source storage rings [2-8]. It has been shown [8-11], that this bursting emission of CSR is associated with a single bunch instability, usually referred as microbunching instability (MBI), driven by the fields of the synchrotron radiation emitted by the bunch itself. Of remarkably different characteristics was the CSR emission observed at BESSY II in Berlin, when the storage ring was tuned into a special low momentum compaction mode [12, 13]. In fact, the emitted radiation was not the quasi-random bursting observed in the other machines, but a powerful and stable flux of broadband CSR in the terahertz range. This was an important result, because it experimentally demonstrated the concrete possibility of constructing a stable broadband source with extremely high power in the terahertz region. Since the publication of the first successful experiment using the ring as a CSR source [14], BESSY II has regular scheduled user's shifts dedicated to CSR experiments. At the present time, several other laboratories are investigating the possibility of a CSR mode of operation [15-17] and a design for a new ring optimized for CSR is at an advanced stage [18]. In what follows, we describe a model that first accounts for the BESSY II observations and then indicates that the special case of BESSY II is actually quite general and typical when relativistic electron storage rings are tuned for short bunches. The model provides a scheme for predicting and optimizing the performance of ring

Stretch Marks

Science.gov (United States)

... completely without the help of a dermatologist or plastic surgeon. These doctors may use one of many types of treatments — from actual surgery to techniques like microdermabrasion and laser treatment — to reduce the appearance of stretch marks. These techniques are ...

Universal growth modes of high-elevation conifers

Czech Academy of Sciences Publication Activity Database

Datsenko, N. M.; Sonechkin, D. M.; Büntgen, Ulf; Yang, B.

2016-01-01

Roč. 38, JUN (2016), s. 38-50 ISSN 1125-7865 Institutional support: RVO:67179843 Keywords : tree-ring chronologies * summer temperature-variations * northeastern tibetan plateau * climate signal * fennoscandian summers * annual precipitation * density * variability * qinghai * Growth modes * Ring width and maximum latewood density * Eigenvector analysis Subject RIV: EF - Botanics Impact factor: 2.259, year: 2016

Communication: A coil-stretch transition in planar elongational flow of an entangled polymeric melt

Science.gov (United States)

Nafar Sefiddashti, Mohammad H.; Edwards, Brian J.; Khomami, Bamin

2018-04-01

Virtual experimentation of atomistic entangled polyethylene melts undergoing planar elongational flow revealed an amazingly detailed depiction of individual macromolecular dynamics and the resulting effect on bistable configurational states. A clear coil-stretch transition was evident, in much the same form as first envisioned by de Gennes for dilute solutions of high polymers, resulting in an associated hysteresis in the configurational flow profile over the range of strain rates predicted by theory. Simulations conducted at steady state revealed bimodal distribution functions, in which equilibrium configurational states were simultaneously populated by relatively coiled and stretched molecules which could transition from one conformational mode to the other over a relatively long time scale at critical values of strain rates. The implication of such behavior points to a double-well conformational free energy potential with an activation barrier between the two configurational minima.

Effect of nonlinear electrostatic forces on the dynamic behaviour of a capacitive ring-based Coriolis Vibrating Gyroscope under severe shock

Science.gov (United States)

Chouvion, B.; McWilliam, S.; Popov, A. A.

2018-06-01

This paper investigates the dynamic behaviour of capacitive ring-based Coriolis Vibrating Gyroscopes (CVGs) under severe shock conditions. A general analytical model is developed for a multi-supported ring resonator by describing the in-plane ring response as a finite sum of modes of a perfect ring and the electrostatic force as a Taylor series expansion. It is shown that the supports can induce mode coupling and that mode coupling occurs when the shock is severe and the electrostatic forces are nonlinear. The influence of electrostatic nonlinearity is investigated by numerically simulating the governing equations of motion. For the severe shock cases investigated, when the electrode gap reduces by ∼ 60 % , it is found that three ring modes of vibration (1 θ, 2 θ and 3 θ) and a 9th order force expansion are needed to obtain converged results for the global shock behaviour. Numerical results when the 2 θ mode is driven at resonance indicate that electrostatic nonlinearity introduces mode coupling which has potential to reduce sensor performance under operating conditions. Under some circumstances it is also found that severe shocks can cause the vibrating response to jump to another stable state with much lower vibration amplitude. This behaviour is mainly a function of shock amplitude and rigid-body motion damping.

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...

Omnidirectional piezo-optical ring sensor for enhanced guided wave structural health monitoring

International Nuclear Information System (INIS)

Giurgiutiu, Victor; Roman, Catalin; Lin, Bin; Frankforter, Erik

2015-01-01

This paper presents a novel method for the detection of ultrasonic waves from acoustic emission events using piezoelectric wafer ac3tive sensors (PWAS) and optical fiber Bragg grating (FBG) sensing combined with mechanical resonance amplification principles. The method is best suited for detecting the out-of-plane motion of the AE wave with preference for a certain frequency that can be adjusted by design. Several issues are discussed: (a) study the mode shapes of the sensors under different resonance frequencies in order to understand the behavior of the ring in a frequency band of interest; (b) comparison of analytical results and mode shapes with FEM predictions; (c) choice of the final piezo-optical ring sensor shape; (d) testing of the piezo-optical ring sensor prototype; (e) discussion of the ring-sensor test results in comparison with conventional results from PWAS and FBG sensors mounted directly on the test structure. The paper ends with summary, conclusions, and suggestions for further work. (paper)

Effects of contract-relax vs static stretching on stretch-induced strength loss and length-tension relationship

DEFF Research Database (Denmark)

Balle, S S; Magnusson, S P; McHugh, M P

2015-01-01

The purpose of this study was to determine the acute effects of contract-relax stretching (CRS) vs static stretching (SS) on strength loss and the length-tension relationship. We hypothesized that there would be a greater muscle length-specific effect of CRS vs SS. Isometric hamstring strength wa...

a First-Principles Model of Fermi Resonance in the Alkyl CH Stretch Region: Application to Hydronaphthalenes, Indanes, and Cyclohexane

Science.gov (United States)

Sibert, Edwin; Kidwell, Nathanael; Zwier, Timothy S.

2014-06-01

The infrared (IR) spectroscopy of the alkyl CH stretch region (2750-3000 cm-1) of a series of bicyclic hydrocarbons and free radicals has been studied under supersonic expansion cooling in the gas phase, and compared with a theoretical model that describes the local mode stretch-bend Fermi resonance interactions. The double resonance method of fluorescence-dip infrared (FDIR) spectroscopy was used on the stable molecules 1,2-dihydronaphthalene, 1,4-dihydronaphthalene, tetralin, indene, and indane using the S_0-S_1 origin transition as a monitor of transitions. Resonant ion-dip infrared (RIDIR) spectra were recorded for the trihydronaphthyl (THN) and inden-2-yl methyl (I2M) radicals. The previously developed model Hamiltonian [J. Chem. Phys. 138 064308 (2013)] incorporates cubic stretch-bend coupling with parameters obtained from density functional theory methods. Full dimensional calculations are compared to reduced dimensional Hamiltonian results in which anharmonic CH streches and CH_2 scissor modes are Fermi coupled. Excellent agreement between theoretical results is found. Scale factors of select terms in the reduced dimensional Hamiltonian, obtained by fitting the theoretical Hamiltonian predictions to the experimental spectra, are found to be similar to previous work. The resulting Hamiltonian predicts successfully all the major spectral features considered in this study. A simplified model is introduced in which the CH_2 groups are decoupled. This model enables the assignment of many of the spectral features. The model results are extended to describe the CH stretch spectrum of the chair and twist-boat conformers of cyclohexane. The chair conformer is used to illustrate the shortcomings of the CH_2 coupling model.

Analysis of the partially filled viscous ring damper. [application as nutation damper for spinning satellite

Science.gov (United States)

Alfriend, K. T.

1973-01-01

A ring partially filled with a viscous fluid has been analyzed as a nutation damper for a spinning satellite. The fluid has been modelled as a rigid slug of finite length moving in a tube and resisted by a linear viscous force. It is shown that there are two distinct modes of motion, called the spin synchronous mode and the nutation synchronous mode. Time constants for each mode are obtained for both the symmetric and asymmetric satellite. The effects of a stop in the tube and an offset of the ring from the spin axis are also investigated. An analysis of test results is also given including a determination of the effect of gravity on the time constants in the two modes.

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.

A discrete electromechanical model for human cardiac tissue: effects of stretch-activated currents and stretch conditions on restitution properties and spiral wave dynamics.

Science.gov (United States)

Weise, Louis D; Panfilov, Alexander V

2013-01-01

We introduce an electromechanical model for human cardiac tissue which couples a biophysical model of cardiac excitation (Tusscher, Noble, Noble, Panfilov, 2006) and tension development (adjusted Niederer, Hunter, Smith, 2006 model) with a discrete elastic mass-lattice model. The equations for the excitation processes are solved with a finite difference approach, and the equations of the mass-lattice model are solved using Verlet integration. This allows the coupled problem to be solved with high numerical resolution. Passive mechanical properties of the mass-lattice model are described by a generalized Hooke's law for finite deformations (Seth material). Active mechanical contraction is initiated by changes of the intracellular calcium concentration, which is a variable of the electrical model. Mechanical deformation feeds back on the electrophysiology via stretch-activated ion channels whose conductivity is controlled by the local stretch of the medium. We apply the model to study how stretch-activated currents affect the action potential shape, restitution properties, and dynamics of spiral waves, under constant stretch, and dynamic stretch caused by active mechanical contraction. We find that stretch conditions substantially affect these properties via stretch-activated currents. In constantly stretched medium, we observe a substantial decrease in conduction velocity, and an increase of action potential duration; whereas, with dynamic stretch, action potential duration is increased only slightly, and the conduction velocity restitution curve becomes biphasic. Moreover, in constantly stretched medium, we find an increase of the core size and period of a spiral wave, but no change in rotation dynamics; in contrast, in the dynamically stretching medium, we observe spiral drift. Our results may be important to understand how altered stretch conditions affect the heart's functioning.

A discrete electromechanical model for human cardiac tissue: effects of stretch-activated currents and stretch conditions on restitution properties and spiral wave dynamics.

Directory of Open Access Journals (Sweden)

Louis D Weise

Full Text Available We introduce an electromechanical model for human cardiac tissue which couples a biophysical model of cardiac excitation (Tusscher, Noble, Noble, Panfilov, 2006 and tension development (adjusted Niederer, Hunter, Smith, 2006 model with a discrete elastic mass-lattice model. The equations for the excitation processes are solved with a finite difference approach, and the equations of the mass-lattice model are solved using Verlet integration. This allows the coupled problem to be solved with high numerical resolution. Passive mechanical properties of the mass-lattice model are described by a generalized Hooke's law for finite deformations (Seth material. Active mechanical contraction is initiated by changes of the intracellular calcium concentration, which is a variable of the electrical model. Mechanical deformation feeds back on the electrophysiology via stretch-activated ion channels whose conductivity is controlled by the local stretch of the medium. We apply the model to study how stretch-activated currents affect the action potential shape, restitution properties, and dynamics of spiral waves, under constant stretch, and dynamic stretch caused by active mechanical contraction. We find that stretch conditions substantially affect these properties via stretch-activated currents. In constantly stretched medium, we observe a substantial decrease in conduction velocity, and an increase of action potential duration; whereas, with dynamic stretch, action potential duration is increased only slightly, and the conduction velocity restitution curve becomes biphasic. Moreover, in constantly stretched medium, we find an increase of the core size and period of a spiral wave, but no change in rotation dynamics; in contrast, in the dynamically stretching medium, we observe spiral drift. Our results may be important to understand how altered stretch conditions affect the heart's functioning.

Solid-state ring laser gyroscope

Science.gov (United States)

Schwartz, S.

The ring laser gyroscope is a rotation sensor used in most kinds of inertial navigation units. It usually consists in a ring cavity filled with a mixture of helium and neon, together with high-voltage pumping electrodes. The use of a gaseous gain medium, while resulting naturally in a stable bidirectional regime enabling rotation sensing, is however the main industrially limiting factor for the ring laser gyroscopes in terms of cost, reliability and lifetime. We study in this book the possibility of substituting for the gaseous gain medium a solid-state medium (diode-pumped Nd-YAG). For this, a theoretical and experimental overview of the lasing regimes of the solid-state ring laser is reported. We show that the bidirectional emission can be obtained thanks to a feedback loop acting on the states of polarization and inducing differential losses proportional to the difference of intensity between the counterpropagating modes. This leads to the achievement of a solid-state ring laser gyroscope, whose frequency response is modified by mode coupling effects. Several configurations, either mechanically or optically based, are then successively studied, with a view to improving the quality of this frequency response. In particular, vibration of the gain crystal along the longitudinal axis appears to be a very promising technique for reaching high inertial performances with a solid-state ring laser gyroscope. Gyrolaser à état solide. Le gyrolaser est un capteur de rotation utilisé dans la plupart des centrales de navigation inertielle. Dans sa forme usuelle, il est constitué d'une cavité laser en anneau remplie d'un mélange d'hélium et de néon pompé par des électrodes à haute tension. L'utilisation d'un milieu amplificateur gazeux, si elle permet de garantir naturellement le fonctionnement bidirectionnel stable nécessaire à la mesure des rotations, constitue en revanche la principale limitation industrielle des gyrolasers actuels en termes de coût, fiabilit

a Study of Vibrational Mode Coupling in 2-FLUOROETHANOL and 1,2-DIFLUOROETHANE Using High-Resolution Infrared Spectroscopy.

Science.gov (United States)

Mork, Steven Wayne

High resolution infrared spectroscopy was used to examine intramolecular vibrational interactions in 2 -fluoroethanol (2FE) and 1,2-difluoroethane (DFE). A high resolution infrared spectrophotometer capable of better than 10 MHz spectral resolution was designed and constructed. The excitation source consists of three lasers: an argon-ion pumped dye laser which pumps a color -center laser. The infrared beam from the color-center laser is used to excite sample molecules which are rotationally and vibrationally cooled in a supersonic molecular beam. Rovibrational excitation of the sample molecules is detected by monitoring the kinetic energy of the molecular beam with a bolometer. The high resolution infrared spectrum of 2FE was collected and analyzed over the 2977-2990 cm^ {-1}^ectral region. This region contains the asymmetric CH stretch on the fluorinated carbon. The spectrum revealed extensive perturbations in the rotational fine structure. Analysis of these perturbations has provided a quantitative measure of selective vibrational mode coupling between the C-H stretch and its many neighboring dark vibrational modes. Interestingly, excitation of the C-H stretch is known to induce a photoisomerization reaction between 2FE's Gg^' and Tt conformers. Implications of the role of mode coupling in the reaction mechanism are also addressed. Similarly, the high resolution infrared spectrum of DFE was collected and analyzed over the 2978-2996 cm ^{-1}^ectral region. This region contains the symmetric combination of asymmetric C-H stretches in DFE. Perturbations in the rotational fine structure indicate vibrational mode coupling to a single dark vibrational state. The dark state is split by approximately 19 cm^{-1} due to tunneling between two identical gauche conformers. The coupling mechanism is largely anharmonic with a minor component of B/C-plane Coriolis coupling. Effects of centrifugal distortion along the molecular A-axis are also observed. The coupled vibrational

Stretching and jamming of finite automata

NARCIS (Netherlands)

Beijer, de N.; Kourie, D.G.; Watson, B.W.; Cleophas, L.G.W.A.; Watson, B.W.

2004-01-01

In this paper we present two transformations on automata, called stretching and jamming. These transformations will, under certain conditions, reduce the size of the transition table, and under other conditions reduce the string processing time. Given a finite automaton, we can stretch it by

The effect of transverse multi-mode oscillation in passively modelocked solid-state lasers

Science.gov (United States)

Agnesi, A.; Reali, G. C.; Gabetta, G.

1992-03-01

We demonstrate that the pulses from a passively mode-locked flashlamp pumped solid-state laser can be considerably shorter using an antiresonant-ring mirror than using a linear cavity with a standard contacted dye-cell mirror, and we suggest that transverse-mode-filtering effects in the antiresonant ring play an important role in explaining this difference.

Results and analysis of free-electron-laser oscillation in a high-energy storage ring

International Nuclear Information System (INIS)

Couprie, M.E.; Velghe, M.; Prazeres, R.; Jaroszynski, D.; Billardon, M.

1991-01-01

A storage-ring free-electron laser at Orsay has been operating since 1989 in the visible wavelength range. In contrast with previous experiments, it operates with positrons and at higher energies (600--800 MeV), with the storage ring Super-ACO (ACO denotes Anneau de Collisions d'Orsay). The optical gain, the laser power, the transverse profile, and the macrotemporal structure of the laser are analyzed. In particular, we show that the gain matrix possesses many off-diagonal elements, which results in lasing on a combination of noncylindrical Gaussian modes. The eigenmode of the laser oscillation is a combination of one or two main Gaussian modes and several higher-order modes, which results in most of the power being extracted in these modes

Magnitude and duration of stretch modulate fibroblast remodeling.

Science.gov (United States)

Balestrini, Jenna L; Billiar, Kristen L

2009-05-01

Mechanical cues modulate fibroblast tractional forces and remodeling of extracellular matrix in healthy tissue, healing wounds, and engineered matrices. The goal of the present study is to establish dose-response relationships between stretch parameters (magnitude and duration per day) and matrix remodeling metrics (compaction, strength, extensibility, collagen content, contraction, and cellularity). Cyclic equibiaxial stretch of 2-16% was applied to fibroblast-populated fibrin gels for either 6 h or 24 h/day for 8 days. Trends in matrix remodeling metrics as a function of stretch magnitude and duration were analyzed using regression analysis. The compaction and ultimate tensile strength of the tissues increased in a dose-dependent manner with increasing stretch magnitude, yet remained unaffected by the duration in which they were cycled (6 h/day versus 24 h/day). Collagen density increased exponentially as a function of both the magnitude and duration of stretch, with samples stretched for the reduced duration per day having the highest levels of collagen accumulation. Cell number and failure tension were also dependent on both the magnitude and duration of stretch, although stretch-induced increases in these metrics were only present in the samples loaded for 6 h/day. Our results indicate that both the magnitude and the duration per day of stretch are critical parameters in modulating fibroblast remodeling of the extracellular matrix, and that these two factors regulate different aspects of this remodeling. These findings move us one step closer to fully characterizing culture conditions for tissue equivalents, developing improved wound healing treatments and understanding tissue responses to changes in mechanical environments during growth, repair, and disease states.

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.

Matching modes between HIRFL and CSR

International Nuclear Information System (INIS)

Tang, J.Y.; Li, H.H.; Yuan, Y.J.

2001-01-01

National key scientific project 'HIRFL-CSR Cooler Storage Ring' makes use of existing HIRFL as its pre-accelerator. In order to take the full capability of HIRFL, we have studied in detailed the matching modes between HIRFL and CSR. It is proposed to use two matching modes: direct matching between SFC (HIRFL injector cyclotron) and CSRm (CSR main ring), three-cascade matching of SFC, SSC (HIRFL main cyclotron) and CSRm. With these combinations, better beam transmission efficiency, better beam utilization efficiency of HIRFL-CSR accelerator complex and better operation efficiency of HIRFL can be obtained. In the first case, SSC can be used simultaneously in other purposes, either to accelerate medium energy heavy ions or to accelerate protons combined with another small cyclotron

Foam topology. Bending versus stretching dominated architectures

International Nuclear Information System (INIS)

Deshpande, V.; Ashby, M.; Fleck, N.

2000-01-01

Cellular solids can deform by either the bending or stretching of the cell walls. While most cellular solids are bending-dominated, those that are stretching-dominated are much more weight-efficient for structural applications. In this study we have investigated the topological criteria that dictate the deformation mechanism of a cellular solid by analysing the rigidity (or otherwise) of pin-jointed frameworks comprising inextensional struts. We show that the minimum node connectivity for a special class of lattice structured materials to be stretching-dominated is 6 for 2D foams and 12 for 3D foams. Similarly, sandwich plates comprising of truss cores faced with planar trusses require a minimum node connectivity of 9 to undergo stretching-dominated deformation for all loading states. (author)

Numerical modeling of the plasma ring acceleration experiment

International Nuclear Information System (INIS)

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

1987-01-01

Modeling of the LLNL RACE experiment and its many applications has necessitated the development and use of a wide array of computational tools. The two-dimensional MHD code, HAM, has been used to model the formation of a compact torus plasma ring in a magnetized coaxial gun and its subsequent acceleration by an additional applied toroidal field. Features included in the 2-D calculations are self-consistent models for (1) the time-dependent poloidal field produced by a capacitor bank discharge through a solenoid field coil (located either inside the gun inner electrode or outside the outer gun electrode) and the associated diffusion of magnetic flux through neighboring conductors, (2) gas flow into the gun annular region from a simulated puffed gas valve plenum, (3) formation and motion of a current sheet produced by J x B forces resulting from discharge of the gun capacitor bank through the plasma load between the coaxial gun electrodes, (4) the subsequent stretching and reconnection of the poloidal field lines to form a compact torus plasma ring, and (5) finally the discharge of the accelerator capacitor bank producing an additional toroidal field for acceleration of the plasma ring. The code has been extended to include various models for gas breakdown, plasma anomalous resistivity, and mass entrainment from ablation of electrode material

THE INFRARED SPECTROSCOPY OF POLYCYCLIC AROMATIC HYDROCARBONS WITH FIVE- AND SEVEN-MEMBERED FUSED RING DEFECTS

International Nuclear Information System (INIS)

Ricca, Alessandra; Bauschlicher, Charles W. Jr; Allamandola, Louis J.

2011-01-01

Polycyclic aromatic hydrocarbon (PAH) growth and destruction are thought to proceed via the occasional incorporation of five- and seven-membered fused ring defects in the hexagonal carbon skeleton. Using density functional theory, this paper investigates the effect such five- and seven-membered fused ring defects have on the infrared spectra of ovalene, circumovalene, and circumcircumovalene. The defects make only small changes to the overall infrared (IR) spectra, both in the mid-IR and in the far-IR, of these species. In addition to small shifts in the positions of the bands between the PAHs with and without defects, the most common effect of the defects is to increase the number of bands. Except for an anion with the Stone-Wales defect, all of the species studied have the C-C stretching band at 6.3 μm or at longer wavelengths, the position in Classes B and C astronomical PAH spectra. In the case of the Stone-Wales anion, the band falls at 6.20 μm, suggesting that further study of defects is probably worthwhile, as some PAHs with defects might be important in those sources (Class A) that show a C-C stretching band that falls near 6.2 μm.

Sub-Doppler slit jet infrared spectroscopy of astrochemically relevant cations: Symmetric (ν1) and antisymmetric (ν6) NH stretching modes in ND2H2+

Science.gov (United States)

Chang, Chih-Hsuan; Nesbitt, David J.

2018-01-01

Sub-Doppler infrared rovibrational transitions in the symmetric (v1) and antisymmetric (v6) NH stretch modes of the isotopomerically substituted ND2H2+ ammonium cation are reported for the first time in a slit jet discharge supersonic expansion spectrometer. The partially H/D substituted cation is generated by selective isotopic exchange of ND3 with H2O to form NHD2, followed by protonation with H3+ formed in the NHD2/H2/Ne slit-jet discharge expansion environment. Rotational assignment for ND2H2+ is confirmed rigorously by four line ground state combination differences, which agree to be within the sub-Doppler precision in the slit jet (˜9 MHz). Observation of both b-type (ν1) and c-type (ν6) bands enables high precision determination of the ground and vibrationally excited state rotational constants. From an asymmetric top Watson Hamiltonian analysis, the ground state constants are found to be A″ = 4.856 75(4) cm-1, B″ = 3.968 29(4) cm-1, and C″ = 3.446 67(6) cm-1, with band origins at 3297.5440(1) and 3337.9050(1) cm-1 for the v1 and v6 modes, respectively. This work permits prediction of precision microwave/mm-wave transitions, which should be invaluable in facilitating ongoing spectroscopic searches for partially deuterated ammonium cations in interstellar clouds and star-forming regions of the interstellar medium.

Optofluidic time-stretch microscopy: recent advances

Science.gov (United States)

Lei, Cheng; Nitta, Nao; Ozeki, Yasuyuki; Goda, Keisuke

2018-04-01

Flow cytometry is an indispensable method for valuable applications in numerous fields such as immunology, pathology, pharmacology, molecular biology, and marine biology. Optofluidic time-stretch microscopy is superior to conventional flow cytometry methods for its capability to acquire high-quality images of single cells at a high-throughput exceeding 10,000 cells per second. This makes it possible to extract copious information from cellular images for accurate cell detection and analysis with the assistance of machine learning. Optofluidic time-stretch microscopy has proven its effectivity in various applications, including microalga-based biofuel production, evaluation of thrombotic disorders, as well as drug screening and discovery. In this review, we discuss the principles and recent advances of optofluidic time-stretch microscopy.

Stretch due to Penile Prosthesis Reservoir Migration

Directory of Open Access Journals (Sweden)

E. Baten

2016-03-01

Full Text Available A 43-year old patient presented to the emergency department with stretch, due to impossible deflation of the penile prosthesis, 4 years after successful implant. A CT-scan showed migration of the reservoir to the left rectus abdominis muscle. Refilling of the reservoir was inhibited by muscular compression, causing stretch. Removal and replacement of the reservoir was performed, after which the prosthesis was well-functioning again. Migration of the penile prosthesis reservoir is extremely rare but can cause several complications, such as stretch.

Wave-Kinetic Simulations of the Nonlinear Generation of Electromagnetic VLF Waves through Velocity Ring Instabilities

Science.gov (United States)

Ganguli, G.; Crabtree, C. E.; Rudakov, L.; Mithaiwala, M.

2014-12-01

Velocity ring instabilities are a common naturally occuring magnetospheric phenomenon that can also be generated by man made ionospheric experiments. These instabilities are known to generate lower-hybrid waves, which generally cannot propagte out of the source region. However, nonlinear wave physics can convert these linearly driven electrostatic lower-hybrid waves into electromagnetic waves that can escape the source region. These nonlinearly generated waves can be an important source of VLF turbulence that controls the trapped electron lifetime in the radiation belts. We develop numerical solutions to the wave-kinetic equation in a periodic box including the effects of nonlinear (NL) scattering (nonlinear Landau damping) of Lower-hybrid waves giving the evolution of the wave-spectra in wavenumber space. Simultaneously we solve the particle diffusion equation of both the background plasma particles and the ring ions, due to both linear and nonlinear Landau resonances. At initial times for cold ring ions, an electrostatic beam mode is excited, while the kinetic mode is stable. As the instability progresses the ring ions heat, the beam mode is stabilized, and the kinetic mode destabilizes. When the amplitude of the waves becomes sufficient the lower-hybrid waves are scattered (by either nearly unmagnetized ions or magnetized electrons) into electromagnetic magnetosonic waves [Ganguli et al 2010]. The effect of NL scattering is to limit the amplitude of the waves, slowing down the quasilinear relaxation time and ultimately allowing more energy from the ring to be liberated into waves [Mithaiwala et al. 2011]. The effects of convection out of the instability region are modeled, additionally limiting the amplitude of the waves, allowing further energy to be liberated from the ring [Scales et al., 2012]. Results are compared to recent 3D PIC simulations [Winske and Duaghton 2012].

Mode specific dynamics of the H2 + CH3 → H + CH4 reaction studied using quasi-classical trajectory and eight-dimensional quantum dynamics methods

International Nuclear Information System (INIS)

Wang, Yan; Li, Jun; Guo, Hua; Chen, Liuyang; Yang, Minghui; Lu, Yunpeng

2015-01-01

An eight-dimensional quantum dynamical model is proposed and applied to the title reaction. The reaction probabilities and integral cross sections have been determined for both the ground and excited vibrational states of the two reactants. The results indicate that the H 2 stretching and CH 3 umbrella modes, along with the translational energy, strongly promote the reactivity, while the CH 3 symmetric stretching mode has a negligible effect. The observed mode specificity is confirmed by full-dimensional quasi-classical trajectory calculations. The mode specificity can be interpreted by the recently proposed sudden vector projection model, which attributes the enhancement effects of the reactant modes to their strong couplings with the reaction coordinate at the transition state

Simultaneous spectral and temporal analyses of kinetic energies in nonequilibrium systems: theory and application to vibrational relaxation of O-D stretch mode of HOD in water.

Science.gov (United States)

Jeon, Jonggu; Lim, Joon Hyung; Kim, Seongheun; Kim, Heejae; Cho, Minhaeng

2015-05-28

A time series of kinetic energies (KE) from classical molecular dynamics (MD) simulation contains fundamental information on system dynamics. It can also be analyzed in the frequency domain through Fourier transformation (FT) of velocity correlation functions, providing energy content of different spectral regions. By limiting the FT time span, we have previously shown that spectral resolution of KE evolution is possible in the nonequilibrium situations [Jeon and Cho, J. Chem. Phys. 2011, 135, 214504]. In this paper, we refine the method by employing the concept of instantaneous power spectra, extending it to reflect an instantaneous time-correlation of velocities with those in the future as well as with those in the past, and present a new method to obtain the instantaneous spectral density of KE (iKESD). This approach enables the simultaneous spectral and temporal resolution of KE with unlimited time precision. We discuss the formal and novel properties of the new iKESD approaches and how to optimize computational methods and determine parameters for practical applications. The method is specifically applied to the nonequilibrium MD simulation of vibrational relaxation of the OD stretch mode in a hydrated HOD molecule by employing a hybrid quantum mechanical/molecular mechanical (QM/MM) potential. We directly compare the computational results with the OD band population relaxation time profiles extracted from the IR pump-probe measurements for 5% HOD in water. The calculated iKESD yields the OD bond relaxation time scale ∼30% larger than the experimental value, and this decay is largely frequency-independent if the classical anharmonicity is accounted for. From the integrated iKESD over intra- and intermolecular bands, the major energy transfer pathways were found to involve the HOD bending mode in the subps range, then the internal modes of the solvent until 5 ps after excitation, and eventually the solvent intermolecular modes. Also, strong hydrogen

A Fundamental Study of Stretch-Drawing Process of Sheet Metals : Single and Double Operations

Science.gov (United States)

Gotoh, Manabu; Kim, Young-soo; Yamashita, Minoru

1998-05-01

Fundamental and informative data of axisymmetric stretch-drawing of several sheet metals with thichness of 0.7 1.0 mm are presented especially for single and double operations. Very small radius is applied to the die-profile (or -shoulder) in all operations to induce wall-thinning by the effect of bending-under-tension, from which the name `stretch-drawing' comes. It is clearly demonstrated that deeper cups could be formed by the single and double stretch-drawings from smaller cirlcular blanks due to such wall-thinning action than in the usual deep-drawing of larger blanks. From this fact, it is emphasized that the deep-drawability of a sheet metal is not evaluated simply by the conventional LDR (=limiting drawing ratio), but the depth of the drawn cup should also be taken into account. Many experimental data about various metals and thicknesses given in this paper offer a valueable information on this process for more general use which recommends to replace the conventional deep-drawing process by the stretch-drawing process both for single and double operations. In the single stretch-drawing, it is also confirmed that a deeper cup can be produced by raising the blank-holding force at later stage of operation. Fracturing is found to occur at the middle section of the wall part or at the die-profile other than at the punch profile common in the usual deep-drawing process. Numerical simulation of the single stretch-drawing process is also performed by use of DYNA-3D code to confirm that a satisfactory prediction especially in the depth of the drawn-cup can be done at least in a practical sense, although this kind of numerical analysis is very difficult because of the severity or localization of deformation around the die profile. The drawn cup of SUS304 among others fractures in a couple of weeks after the operation due to the residual circumferential tensile stress, whereas that of SUS304L does not. In the double stretch-drawing, it is confirmed that very deeper

POLYCYCLIC AROMATIC HYDROCARBONS WITH ARMCHAIR EDGES AND THE 12.7 μm BAND

International Nuclear Information System (INIS)

Candian, A.; Tielens, A. G. G. M.; Sarre, P. J.

2014-01-01

In this Letter, we report the results of density functional theory calculations on medium-sized neutral polycyclic aromatic hydrocarbon (PAH) molecules with armchair edges. These PAH molecules possess strong C-H stretching and bending modes around 3 μm and in the fingerprint region (10-15 μm), and also strong ring deformation modes around 12.7 μm. Perusal of the entries in the NASA Ames PAHs Database shows that ring deformation modes of PAHs are common, although generally weak. Therefore, we propose that armchair PAHs with N C > 65 are responsible for the 12.7 μm aromatic infrared band in H II regions and discuss the astrophysical implications in the context of the PAH life cycle

Raman spectra of iodine-derivatives of tyrosine and thyronine

International Nuclear Information System (INIS)

Loh, E.

1974-01-01

The Raman spectra of the iodine derivatives of tyrosine and thyronine in the form of compressed crystalline powders have been excited by 4880 A Argon laser on rotating samples at room temperature. The strong peaks in the low-frequency, -1 , region may be described by analogous vibrations of benzene as: I. the C-I out-of-plane bendings of E 1 sub(g) mode from 100 cm -1 to 180 cm -1 ; II. the C-I in-plane bendings of E 2 sub(g) and A 2 sub(g) mode from 190 cm -1 to 330 cm -1 and III. the C-I stretchings of E 2 sub(g) mode from 330 cm -1 to 400 cm -1 . In 3,3',5-triiodo-derivatives, the number of both the C-I in-plane bendings and C-I stretchings on the inner phenyl ring approximately doubles from thet of diiodo-derivatives. This doubling in number of peaks is presumably due to the modulation caused by the libration, which is associated with the C-I out-of-plane bending at position 3', of the outer phenyl ring

Vortices trapped in discrete Josephson rings

International Nuclear Information System (INIS)

Van der Zanta, H.S.J.; Orlando, T.P.; Watanabe, Shinya; Strogatz, S.H.

1994-01-01

We report the first measurements of current- (I-V) characteristics of discrete rings of Josephson junctions. As I is increased, resonant steps appear in the I-V curve, due to phase-locking between a propagating, trapped vortex and the linear waves excited in its wake. Unexpectedly, the phase velocity of the linear waves, not the group velocity, is the physically important quantity and mode numbers outside the Brillouin zone are relevant. Our measurements show that away from the resonant steps, a single vortex can move in an environment with very little damping, making the discrete one-dimensional ring a well-defined model system for the study of ballistic and quantum vortex experiments. ((orig.))

Vortices trapped in discrete Josephson rings

Energy Technology Data Exchange (ETDEWEB)

Van der Zanta, H.S.J. [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Orlando, T.P. [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Watanabe, Shinya [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Strogatz, S.H. [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

1994-12-01

We report the first measurements of current- (I-V) characteristics of discrete rings of Josephson junctions. As I is increased, resonant steps appear in the I-V curve, due to phase-locking between a propagating, trapped vortex and the linear waves excited in its wake. Unexpectedly, the phase velocity of the linear waves, not the group velocity, is the physically important quantity and mode numbers outside the Brillouin zone are relevant. Our measurements show that away from the resonant steps, a single vortex can move in an environment with very little damping, making the discrete one-dimensional ring a well-defined model system for the study of ballistic and quantum vortex experiments. ((orig.)).

Ring cavity surface emitting semiconductor lasers

International Nuclear Information System (INIS)

Mujagic, E.

2010-01-01

Quantum cascade lasers (QCLs) are electrically driven semiconductor lasers, which have undergone a steady improvement since the first demonstration in 1994. These are now well established as reliable sources of coherent light in the mid-infrared (MIR) and terahertz (THz)range of the electromagnetic spectrum (3-300 μm). The rapid progress of this type of lasers is based on a high degree of freedom in tailoring the emission wavelength within a large variety of semiconductor heterostructure designs and materials. These properties have attracted the attention of various applications such as gas analysis, chemical sensing, spectral imaging and free-space telecommunication. In order to improve the selectivity, sensitivity and efficiency of today's sensor systems, high optical power, continuous wave and room temperature performance, single-mode operation and low divergence optical beams, are highly desirable qualities of a compact laser source in this field of research. Since all of these features cannot be provided by a conventional edge-emitting device at the same time, research has put focus on the development of surface emitting devices. Nowadays, the vertical cavity surface emitting lasers (VCSELs) are the most prominent representative for this type of light emitters. With its capability of producing narrow circular beams, the feasibility of two-dimensional arrays and on-wafer testing, such a coherent light source results in a reduction of the fabrication effort and production costs. Since the radiation in QCLs is strictly polarized normal to the epitaxial layer plane, fabrication of VCSELs based on QC structures is not viable. The subject of this work is the design and realization of 'ring cavity surface emitting lasers' (ring-CSELs). This type of lasers employs a circular ring cavity and a resonant distributed feedback (DFB) surface grating. Ring-CSELs were fabricated on the basis of MIR and THz QC structures, which cover a wavelength range from 4 μm to 93 �

Mechanical stretching for tissue engineering: two-dimensional and three-dimensional constructs.

Science.gov (United States)

Riehl, Brandon D; Park, Jae-Hong; Kwon, Il Keun; Lim, Jung Yul

2012-08-01

Mechanical cell stretching may be an attractive strategy for the tissue engineering of mechanically functional tissues. It has been demonstrated that cell growth and differentiation can be guided by cell stretch with minimal help from soluble factors and engineered tissues that are mechanically stretched in bioreactors may have superior organization, functionality, and strength compared with unstretched counterparts. This review explores recent studies on cell stretching in both two-dimensional (2D) and three-dimensional (3D) setups focusing on the applications of stretch stimulation as a tool for controlling cell orientation, growth, gene expression, lineage commitment, and differentiation and for achieving successful tissue engineering of mechanically functional tissues, including cardiac, muscle, vasculature, ligament, tendon, bone, and so on. Custom stretching devices and lab-specific mechanical bioreactors are described with a discussion on capabilities and limitations. While stretch mechanotransduction pathways have been examined using 2D stretch, studying such pathways in physiologically relevant 3D environments may be required to understand how cells direct tissue development under stretch. Cell stretch study using 3D milieus may also help to develop tissue-specific stretch regimens optimized with biochemical feedback, which once developed will provide optimal tissue engineering protocols.

Immediate effects of different types of stretching exercises on badminton jump smash.

Science.gov (United States)

Jang, Hwi S; Kim, Daeho; Park, Jihong

2018-01-01

Since different types of stretching exercises may alter athletic performance, we compared the effects of three types of stretching exercises on badminton jump smash. Sixteen male collegiate badminton players performed one of three different stretching exercises in a counterbalanced order on different days. Static stretching had seven typical stretches, while dynamic stretching involved nine dynamic movements, and resistance dynamic stretching was performed with weighted vests and dumbbells. Before and after each stretching exercise, subjects performed 20 trials of jump smashes. Dependent measurements were the jump heights during jump smashes, velocities of jump-smashed shuttlecocks, and drop point of jump-smashed shuttlecocks. To test the effects of each stretching exercise, we performed mixed model ANOVAs and calculated between-time effect sizes (ES). Each stretching exercise improved the jump heights during jump smashes (type main effect: F(2,75)=1.19, P=0.31; static stretching: 22.1%, Pjump-smashed shuttlecocks (type main effect: F(2,75)=2.18, P=0.12; static stretching: 5.7%, P=0.61, ES=0.39; dynamic stretching: 3.4%, P=0.94, ES=0.28; resistance dynamic stretching: 6%, P=0.50, ES=0.66). However, there were no differences among the stretching exercises for any measurement. The drop point of jump-smashed shuttlecocks did not change (interaction: F(2,75)=0.88, P=0.42). All stretching exercises improved badminton jump smash performance, but we could not determine the best protocol. Since badminton requires high-speed movement and explosive force, we suggest performing dynamic stretching or resistance dynamic stretching.

Lattice stretching bistability and dynamic heterogeneity

DEFF Research Database (Denmark)

Christiansen, Peter Leth; Savin, A. V.; Zolotaryuk, A. V.

2012-01-01

A simple one-dimensional lattice model is suggested to describe the experimentally observed plateau in force-stretching diagrams for some macromolecules. This chain model involves the nearest-neighbor interaction of a Morse-like potential (required to have a saturation branch) and a harmonic second......-neighbor coupling. Under an external stretching applied to the chain ends, the intersite Morse-like potential results in the appearance of a double-well potential within each chain monomer, whereas the interaction between the second neighbors provides a homogeneous bistable (degenerate) ground state, at least...... stretched bonds with a double-well potential. This case allows us to explain the existence of a plateau in the force-extension diagram for DNA and α-helix protein. Finally, the soliton dynamics are studied in detail....

Comparing the effects of 3 weeks of upper-body vibration training, vibration and stretching, and stretching alone on shoulder flexibility in college-aged men.

Science.gov (United States)

Ferguson, Steven L; Kim, Eonho; Seo, Dong-Il; Bemben, Michael G

2013-12-01

This study compared the effects of 3 weeks of upper-body vibration training, vibration and stretching, and stretching alone on shoulder flexibility in college-aged men. Twenty-one men were randomly assigned to vibration-stretching (VS; n = 8), vibration only (VO; n = 6), or stretching only (SO; n = 7) groups that trained 3 times per week for 3 weeks. All 3 groups performed 9 total sets of 30-second stretches. The VS group performed four 30-second upper-body vibration exercises and five 30-second upper-body stretching exercises. The VO group performed nine 30-second upper-body vibration exercises. The SO group performed nine 30-second upper-body stretching exercises. Shoulder flexion (SF), shoulder extension (SE), and shoulder transverse extension (STE) were assessed by a Leighton Flexometer and back scratch tests bilaterally (BSR, BSL) were measured via tape measure. A 1-way analysis of variance (ANOVA) evaluated groups at baseline and a 2-way repeated-measures ANOVA evaluated the interventions over time. At baseline, there were no group differences in age, height, or weight. There was a significant (p alone or combined with stretching, is a viable alternative to a standard stretching routine when attempting to increase shoulder flexibility. Adding vibration training to a flexibility regimen may improve the likelihood of regularly performing flexibility sessions because of increased variety.

Studies of molecular dynamics with neutron scattering techniques. Part of a coordinated programme on neutron scattering techniques

International Nuclear Information System (INIS)

Vinhas, L.A.

1980-05-01

Molecular dynamics was studied in samples of tert-butanol, cyclohexanol and methanol, using neutron inelastic and quasi-elastic techniques. The frequency spectra of cyclohexanol in crystalline phase were interpreted by assigning individual energy peaks to hindered rotation of molecules, lattice vibration, hydrogen bond stretching and ring bending modes. Neutron quasi-elastic scattering measurements permitted the testing of models for molecular diffusion as a function of temperature. The interpretation of neutron incoherent inelastic scattering on methanol indicated the different modes of molecular dynamics in this material; individual inelastic peaks in the spectra could be assigned to vibrations of crystalline lattice, stretching of hydrogen bond and vibrational and torsional modes of CH 3 OH molecule. The results of the experimental work on tertbutanol indicate two distinct modes of motion in this material: individual molecular librations are superposed to a cooperative rotation diffusion which occurs both in solid and in liquid state

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/

Bruxism: Is There an Indication for Muscle-Stretching Exercises?

Science.gov (United States)

Gouw, Simone; de Wijer, Anton; Creugers, Nico Hj; Kalaykova, Stanimira I

Bruxism is a common phenomenon involving repetitive activation of the masticatory muscles. Muscle-stretching exercises are a recommended part of several international guidelines for musculoskeletal disorders and may be effective in management of the jaw muscle activity that gives rise to bruxism. However, most studies of muscle-stretching exercises have mainly focused on their influence on performance (eg, range of motion, coordination, and muscle strength) of the limb or trunk muscles of healthy individuals or individuals with sports-related injuries. Very few have investigated stretching of the human masticatory muscles and none muscle-stretching exercises in the management of (sleep) bruxism. This article reviews the literature on muscle-stretching exercises and their potential role in the management of sleep bruxism or its consequences in the musculoskeletal system.

Various vibration modes in a silicon ring resonator driven by p–n diode actuators formed in the lateral direction

Science.gov (United States)

Tsushima, Takafumi; Asahi, Yoichi; Tanigawa, Hiroshi; Furutsuka, Takashi; Suzuki, Kenichiro

2018-06-01

In this paper, we describe p–n diode actuators that are formed in the lateral direction on resonators. Because previously reported p–n diode actuators, which were driven by a force parallel to the electrostatic force induced in a p–n diode, were fabricated in the perpendicular direction to the surface, the fabrication process to satisfy the requirement of realizing a p–n junction set in the middle of the plate thickness has been difficult. The resonators in this work are driven by p–n diodes formed in the lateral direction, making the process easy. We have fabricated a silicon ring resonator that has in-plane vibration using p–n–p and n–p–n diode actuators formed in the lateral direction. First, we consider a space charge model that can sufficiently accurately describe the force induced in p–n diode actuators and compare it with the capacitance model used in most computer simulations. Then, we show that multiplying the vibration amplitude calculated by computer simulation by the modification coefficient of 4/3 provides the vibration amplitude in the p–n diode actuators. Good agreement of the theory with experimental results of the in-plane vibration measured for silicon ring resonators is obtained. The computer simulation is very useful for evaluating various vibration modes in resonators driven by the p–n diode actuators. The small amplitude of the p–n diode actuator measured in this work is expected to increase greatly with increased doping of the actuator.

Modeling and analysis on ring-type piezoelectric transformers.

Science.gov (United States)

Ho, Shine-Tzong

2007-11-01

This paper presents an electromechanical model for a ring-type piezoelectric transformer (PT). To establish this model, vibration characteristics of the piezoelectric ring with free boundary conditions are analyzed in advance. Based on the vibration analysis of the piezoelectric ring, the operating frequency and vibration mode of the PT are chosen. Then, electromechanical equations of motion for the PT are derived based on Hamilton's principle, which can be used to simulate the coupled electromechanical system for the transformer. Such as voltage stepup ratio, input impedance, output impedance, input power, output power, and efficiency are calculated by the equations. The optimal load resistance and the maximum efficiency for the PT will be presented in this paper. Experiments also were conducted to verify the theoretical analysis, and a good agreement was obtained.

Ring aggregation pattern of metro passenger trips: A study using smart card data

Science.gov (United States)

Wang, Ziyang; Hu, Yuxin; Zhu, Peng; Qin, Yong; Jia, Limin

2018-02-01

With the widespread implementation of smart cards and with more travel details being recorded, travel patterns can be studied more precisely and deeply. Although considerable attention has been paid to travel patterns, the relationship between travel patterns and the functional structure of a city is yet to be well understood. In this research, we study this relationship by analysing metro passenger trip data (in Beijing and Shenzhen in China and London in the United Kingdom), and we present two unprecedented findings. First, through averaging, a linear relationship is found to exist between individual travel distance and the distance between the origin and the city centre. The underlying mechanism is a travel pattern we call "ring aggregation", i.e., the daily movement of city passengers is aggregated into a ring (with approximately equal distances to the city centre). Then, for commuting trips, the daily travel pattern can be regarded as switching between the outer residential ring and the inner work ring. Second, this linear relationship and the ring aggregation pattern seem to be exclusive characteristics of metro systems (and may also fit other moderate- and long-distance transportation modes) but do not apply to short-distance transportation modes, such as bicycles and taxis. This finding implies that the ring aggregation pattern is a product of the relationship between travel patterns and the city functional structure at a large scope.

Effect of B-ring substitution pattern on binding mode of propionamide selective androgen receptor modulators.

Science.gov (United States)

Bohl, Casey E; Wu, Zengru; Chen, Jiyun; Mohler, Michael L; Yang, Jun; Hwang, Dong Jin; Mustafa, Suni; Miller, Duane D; Bell, Charles E; Dalton, James T

2008-10-15

Selective androgen receptor modulators (SARMs) are essentially prostate sparing androgens, which provide therapeutic potential in osteoporosis, male hormone replacement, and muscle wasting. Herein we report crystal structures of the androgen receptor (AR) ligand-binding domain (LBD) complexed to a series of potent synthetic nonsteroidal SARMs with a substituted pendant arene referred to as the B-ring. We found that hydrophilic B-ring para-substituted analogs exhibit an additional region of hydrogen bonding not seen with steroidal compounds and that multiple halogen substitutions affect the B-ring conformation and aromatic interactions with Trp741. This information elucidates interactions important for high AR binding affinity and provides new insight for structure-based drug design.

Compact Dual-Band Bandpass Filter Using Stubs Loaded Ring Resonator

Science.gov (United States)

Xu, Jin

2016-01-01

This paper presents a novel second-order dual-band bandpass filter (BPF) by using proposed stubs loaded ring resonator. The resonant behavior of proposed stubs loaded ring resonator is analyzed by even-/odd-mode method, which shows its multiple-mode resonant characteristic. Parameters sweep is done so as to give the design guidelines. As an example, a second-order dual-band BPF operating at 1.8/5.2 GHz for GSM and WLAN applications is designed, fabricated and measured. The fabricated filter has a very compact size of 0.05λg×0.15λg. Measured results also show that the proposed dual-band BPF has a better than 20 dB rejection upper stopband from 5.47 GHz to 12.56 GHz. Good agreement is shown between the simulated and measured results.

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)

End Point of Black Ring Instabilities and the Weak Cosmic Censorship Conjecture.

Science.gov (United States)

Figueras, Pau; Kunesch, Markus; Tunyasuvunakool, Saran

2016-02-19

We produce the first concrete evidence that violation of the weak cosmic censorship conjecture can occur in asymptotically flat spaces of five dimensions by numerically evolving perturbed black rings. For certain thin rings, we identify a new, elastic-type instability dominating the evolution, causing the system to settle to a spherical black hole. However, for sufficiently thin rings the Gregory-Laflamme mode is dominant, and the instability unfolds similarly to that of black strings, where the horizon develops a structure of bulges connected by necks which become ever thinner over time.

Delay differential equations for mode-locked semiconductor lasers.

Science.gov (United States)

Vladimirov, Andrei G; Turaev, Dmitry; Kozyreff, Gregory

2004-06-01

We propose a new model for passive mode locking that is a set of ordinary delay differential equations. We assume a ring-cavity geometry and Lorentzian spectral filtering of the pulses but do not use small gain and loss and weak saturation approximations. By means of a continuation method, we study mode-locking solutions and their stability. We find that stable mode locking can exist even when the nonlasing state between pulses becomes unstable.

Stretch induced endothelin-1 secretion by adult rat astrocytes involves calcium influx via stretch-activated ion channels (SACs)

International Nuclear Information System (INIS)

Ostrow, Lyle W.; Suchyna, Thomas M.; Sachs, Frederick

2011-01-01

Highlights: → Endothelin-1 expression by adult rat astrocytes correlates with cell proliferation. → Stretch-induced ET-1 is inhibited by GsMtx-4, a specific inhibitor of Ca 2+ permeant SACs. → The less specific SAC inhibitor streptomycin also inhibits ET-1 secretion. → Stretch-induced ET-1 production depends on a calcium influx. → SAC pharmacology may provide a new class of therapeutic agents for CNS pathology. -- Abstract: The expression of endothelins (ETs) and ET-receptors is often upregulated in brain pathology. ET-1, a potent vasoconstrictor, also inhibits the expression of astrocyte glutamate transporters and is mitogenic for astrocytes, glioma cells, neurons, and brain capillary endothelia. We have previously shown that mechanical stress stimulates ET-1 production by adult rat astrocytes. We now show in adult astrocytes that ET-1 production is driven by calcium influx through stretch-activated ion channels (SACs) and the ET-1 production correlates with cell proliferation. Mechanical stimulation using biaxial stretch ( 2+ threshold. This coupling of mechanical stress to the astrocyte endothelin system through SACs has treatment implications, since all pathology deforms the surrounding parenchyma.

Driven-Dissipative Supersolid in a Ring Cavity

Science.gov (United States)

Mivehvar, Farokh; Ostermann, Stefan; Piazza, Francesco; Ritsch, Helmut

2018-03-01

Supersolids are characterized by the counterintuitive coexistence of superfluid and crystalline order. Here we study a supersolid phase emerging in the steady state of a driven-dissipative system. We consider a transversely pumped Bose-Einstein condensate trapped along the axis of a ring cavity and coherently coupled to a pair of degenerate counterpropagating cavity modes. Above a threshold pump strength the interference of photons scattered into the two cavity modes results in an emergent superradiant lattice, which spontaneously breaks the continuous translational symmetry towards a periodic atomic pattern. The crystalline steady state inherits the superfluidity of the Bose-Einstein condensate, thus exhibiting genuine properties of a supersolid. A gapless collective Goldstone mode correspondingly appears in the superradiant phase, which can be nondestructively monitored via the relative phase of the two cavity modes on the cavity output. Despite cavity-photon losses the Goldstone mode remains undamped, indicating the robustness of the supersolid phase.

BSDB: the Biomolecule Stretching Database

Science.gov (United States)

Cieplak, Marek; Sikora, Mateusz; Sulkowska, Joanna I.; Witkowski, Bartlomiej

2011-03-01

Despite more than a decade of experiments on single biomolecule manipulation, mechanical properties of only several scores of proteins have been measured. A characteristic scale of the force of resistance to stretching, Fmax , has been found to range between ~ 10 and 480 pN. The Biomolecule Stretching Data Base (BSDB) described here provides information about expected values of Fmax for, currently, 17 134 proteins. The values and other characteristics of the unfolding proces, including the nature of identified mechanical clamps, are available at www://info.ifpan.edu.pl/BSDB/. They have been obtained through simulations within a structure-based model which correlates satisfactorily with the available experimental data on stretching. BSDB also lists experimental data and results of the existing all-atom simulations. The database offers a Protein-Data-Bank-wide guide to mechano-stability of proteins. Its description is provided by a forthcoming Nucleic Acids Research paper. Supported by EC FUNMOL project FP7-NMP-2007-SMALL-1, and European Regional Development Fund: Innovative Economy (POIG.01.01.02-00-008/08).

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...

Analysis of oil consumption in cylinder of diesel engine for optimization of piston rings

Science.gov (United States)

Zhang, Junhong; Zhang, Guichang; He, Zhenpeng; Lin, Jiewei; Liu, Hai

2013-01-01

The performance and particulate emission of a diesel engine are affected by the consumption of lubricating oil. Most studies on oil consumption mechanism of the cylinder have been done by using the experimental method, however they are very costly. Therefore, it is very necessary to study oil consumption mechanism of the cylinder and obtain the accurate results by the calculation method. Firstly, four main modes of lubricating oil consumption in cylinder are analyzed and then the oil consumption rate under common working conditions are calculated for the four modes based on an engine. Then, the factors that affect the lubricating oil consumption such as working conditions, the second ring closed gap, the elastic force of the piston rings are also investigated for the four modes. The calculation results show that most of the lubricating oil is consumed by evaporation on the liner surface. Besides, there are three other findings: (1) The oil evaporation from the liner is determined by the working condition of an engine; (2) The increase of the ring closed gap reduces the oil blow through the top ring end gap but increases blow-by; (3) With the increase of the elastic force of the ring, both the left oil film thickness and the oil throw-off at the top ring decrease. The oil scraping of the piston top edge is consequently reduced while the friction loss between the rings and the liner increases. A neural network prediction model of the lubricating oil consumption in cylinder is established based on the BP neural network theory, and then the model is trained and validated. The main piston rings parameters which affect the oil consumption are optimized by using the BP neural network prediction model and the prediction accuracy of this BP neural network is within 8%, which is acceptable for normal engineering applications. The oil consumption is also measured experimentally. The relative errors of the calculated and experimental values are less than 10%, verifying the

The stretch reflex and the contributions of C David Marsden

Directory of Open Access Journals (Sweden)

Kalyan B Bhattacharyya

2017-01-01

Full Text Available The stretch reflex or myotatic reflex refers to the contraction of a muscle in response to its passive stretching by increasing its contractility as long as the stretch is within physiological limits. For ages, it was thought that the stretch reflex was of short latency and it was synonymous with the tendon reflex, subserving the same spinal reflex arc. However, disparities in the status of the two reflexes in certain clinical situations led Marsden and his collaborators to carry out a series of experiments that helped to establish that the two reflexes had different pathways. That the two reflexes are dissociated has been proved by the fact that the stretch reflex and the tendon reflex, elicited by stimulation of the same muscle, have different latencies, that of the stretch reflex being considerably longer. They hypothesized that the stretch reflex had a transcortical course before it reached the spinal motor neurons for final firing. Additionally, the phenomenon of stimulus-sensitive cortical myoclonus lent further evidence to the presence of the transcortical loop where the EEG correlate preceded the EMG discharge. This concept has been worked out by later neurologists in great detail , and the general consensus is that indeed, the stretch reflex is endowed with a conspicuous transcortical component.

Whirling modes and parametric instabilities in the discrete Sine-Gordon equation: Experimental tests in Josephson rings

International Nuclear Information System (INIS)

Watanabe, S.; Strogatz, S.H.; van der Zant, H.S.J.; Orlando, T.P.

1995-01-01

We analyze the damped driven discrete sine-Gordon equation. For underdamped, highly discrete systems, we show that whirling periodic solutions undergo parametric instabilities at certain drive strengths. The theory predicts novel resonant steps in the current-voltage characteristics of discrete Josephson rings, occurring in the return path of the subgap region. We have observed these steps experimentally in a ring of 8 underdamped junctions. An unusual prediction, verified experimentally, is that such steps occur even if there are no vortices in the ring. Numerical simulations indicate that complex spatiotemporal behavior occurs past the onset of instability

Gap solitons in a chain of split-ring resonator dimers

Energy Technology Data Exchange (ETDEWEB)

Cui, Wei-na, E-mail: cuiweinaa@163.com [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Li, Hong-xia, E-mail: hxli@njust.edu.cn [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Sun, Min [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Bu, Ling-bing [Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

2017-06-21

Dynamics of a chain of split-ring resonator dimers with Kerr nonlinear interaction are investigated. A dimer is built as a pair of coupled split-ring resonators with different size. It is shown that the gap solitons with frequency lying in the gap exist due to the interaction of the discreteness and nonlinearity. Such localized structures are studied in the phase plane and analytical and numerical expressions are also obtained. - Highlights: • The coupling of the two modes is studied in the chain of split-ring resonator dimers with Kerr nonlinear interaction. • The evolution of the localized structures is studied in the phase plane. • This system supports gap solitons with the frequencies lying in the gap.

Static stretching does not alter pre and post-landing muscle activation

Directory of Open Access Journals (Sweden)

Moss Wesley R

2011-05-01

Full Text Available Abstract Background Static stretching may result in various strength and power deficiencies. Prior research has not determined, however, if static stretching causes a change in muscle activation during a functional task requiring dynamic stability. The purpose of this study was to determine if static stretching has an effect on mean pre and postlanding muscle (vastus medialis VM, vastus lateralis VL, medial hamstring MH, and biceps femoris BF activity. Methods 26 healthy, physically active subjects were recruited, from which 13 completed a 14-day static stretching regimen for the quadriceps and hamstrings. Using the data from the force plate and EMG readings, a mean of EMG amplitude was calculated for 150 msec before and after landing. Each trial was normalized to an isometric reference position. Means were calculated for the VM, VL, MH, and BF from 5 trials in each session. Measures were collected pre, immediately following the 1st stretching session, and following 2 weeks of stretching. Results A 14-day static stretching regimen resulted in no significant differences in pre or postlanding mean EMG amplitude during a drop landing either acutely or over a 14-day period. Conclusions Static stretching, done acutely or over a 14-day period does not result in measurable differences of mean EMG amplitude during a drop landing. Static stretching may not impede dynamic stability of joints about which stretched muscles cross.

Active mode locking of quantum cascade lasers in an external ring cavity.

Science.gov (United States)

Revin, D G; Hemingway, M; Wang, Y; Cockburn, J W; Belyanin, A

2016-05-05

Stable ultrashort light pulses and frequency combs generated by mode-locked lasers have many important applications including high-resolution spectroscopy, fast chemical detection and identification, studies of ultrafast processes, and laser metrology. While compact mode-locked lasers emitting in the visible and near infrared range have revolutionized photonic technologies, the systems operating in the mid-infrared range where most gases have their strong absorption lines, are bulky and expensive and rely on nonlinear frequency down-conversion. Quantum cascade lasers are the most powerful and versatile compact light sources in the mid-infrared range, yet achieving their mode-locked operation remains a challenge, despite dedicated effort. Here we report the demonstration of active mode locking of an external-cavity quantum cascade laser. The laser operates in the mode-locked regime at room temperature and over the full dynamic range of injection currents.

Charged black rings at large D

Energy Technology Data Exchange (ETDEWEB)

Chen, Bin [Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,5 Yiheyuan Rd, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter,5 Yiheyuan Rd, Beijing 100871 (China); Center for High Energy Physics, Peking University,5 Yiheyuan Rd, Beijing 100871 (China); Li, Peng-Cheng; Wang, Zi-zhi [Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,5 Yiheyuan Rd, Beijing 100871 (China)

2017-04-28

We study the charged slowly rotating black holes in the Einstein-Maxwell theory in the large dimensions (D). By using the 1/D expansion in the near regions of the black holes we obtain the effective equations for the charged slowly rotating black holes. The effective equations capture the dynamics of various stationary solutions, including the charged black ring, the charged slowly rotating Myers-Perry black hole and the charged slowly boosted black string. Via different embeddings we construct these stationary solutions explicitly. For the charged black ring at large D, we find that the charge lowers the angular momentum due to the regularity condition on the solution. By performing the perturbation analysis of the effective equations, we obtain the quasinormal modes of the charge perturbation and the gravitational perturbation analytically. Like the neutral case the charged thin black ring suffers from the Gregory-Laflamme-like instability under the non-axisymmetric perturbations, but the charge weakens the instability. Besides, we find that the large D analysis always respects the cosmic censorship.

Fermilab Recycler Ring: Technical design report. Revision 1.1

International Nuclear Information System (INIS)

Jackson, G.

1996-07-01

This report describes the technical design of the Fermilab Recycler Ring. The purpose of the Recycler is to augment the luminosity increase anticipated from the implementation of the Fermi III upgrade project, which has as its main component the Fermilab Main Injector construction project. The Recycler is a fixed 8 GeV kinetic energy storage ring. It is located in the Main Injector tunnel directly above the Main Injector beamline, near the ceiling. The construction schedule calls for the installation of the Recycler ring before the installation shutdown of the Main Injector. This aggressive construction schedule is made possible by the exclusive use of permanent magnets in the ring lattice, removing the need for expensive conventional iron/copper magnet construction along with the related power supplies, cooling water system, and electrical safety systems. The location, operating energy, and mode of construction are chosen to minimize operational impacts on both Fermilab's ongoing High Energy Physics program and the Main Injector construction project

A novel in-plane mode rotary ultrasonic motor

Directory of Open Access Journals (Sweden)

Lu Xiaolong

2014-04-01

Full Text Available Ultrasonic motors have the merits of high ratio of torque to volume, high positioning precision, intrinsic holding torque, etc., compared to the conventional electromagnetic motors. There have been several potential applications for this type of motor in aerospace exploration, but bearings and bonding mechanism of the piezoelectric ring in the motors limit the performance of them in the space operation conditions. It is known that the Langevin type transducer has excellent energy efficiency and reliability. Hence using the Langevin type transducer in ultrasonic motors may improve the reliability of piezoelectric motors for space applications. In this study, a novel in-plane mode rotary ultrasonic motor is designed, fabricated, and characterized. The proposed motor operates in in-plane vibration mode which is excited by four Langevin-type bending vibrators separately placed around a ring-shaped stator. Two tapered rotors are assembled to the inner ring of the stator and clamped together by a screw nut. In order to make the motor more stable and convenient to fix, a thin cylindrical support is placed under the stator ring. Due to its no-bearing structure and Langevin transducer excitation, the prototype ultrasonic motor may operate well in aeronautic and astronautic environments.

Summary of the stretching tectonics research

International Nuclear Information System (INIS)

Yu Dagan

1994-01-01

The rise of stretching tectonics is established on the basis of recent structural geology theory, the establishment of metamorphic nucleus complex structural model on one hand plays an important promoting art to the development of stretching structure, on the other hand, it needs constant supplement and perfection in practice. Metamorphic nucleus complex is the carrier of comparatively deep geological information in vertical section of the crust and has wide distribution in the era of south China. Evidently, it can be taken as the 'key' to understanding the deep and studying the basement, Strengthening the study will play the important promoting role to the deep prospecting. The study of stretching tectonics is not only limited within the range of structure and metamorphism, but combine with the studies of sedimentation, magmatism, metamorphism and mineralization, thus form a new field of tectonic geology of self-developing system

EFFECT OF DIFFERENT STRETCHING PROTOCOLS ON VERTICAL JUMP PERFORMANCE

Directory of Open Access Journals (Sweden)

Emre Serin

2018-04-01

Full Text Available This study aimed to examine the effect of different stretching exercises on vertical jump performance. A total of 14 national male athletes sporting in the elite level took part in the study. The age average of the participants was 20.25±1.03 year, the average height was 1.80±.08 m, the average body weight was 77.14±18.91 kg, average of sporting age was 9.87±3.31 year and the average number of participation in international games was 10.0±3.31. As stretching protocol: Method 1 (5 minutes of jogging and 2 minutes of active rest followed by Method 2 (static stretching for 4 different muscle groups 3 repetitions for 15 seconds of static stretching, rest for 10 seconds between groups and then consecutively, Method 3 (Dynamic stretching exercises with 3 repetitions for 15 seconds and 10 seconds rest between different muscle groups were applied in the study. The vertical jump performance before and after different stretching exercises of the participants was determined by means of the vertical jump test using the smart speed lite system. Before and after the training of all athletes, HR was recorded with a heart rate monitor (RS 800, Polar Vantage NV, Polar Electro Oy, Finland with 5 seconds intervals. Before the study, the chest band of the heartbeat monitor was placed on the chest of the athlete and the HR was recorded from the monitor. SPSS 15.0 statistical package program was used for evaluation and calculation of the data. In this study in addition to descriptive statistics (mean and standard deviation paired samples t-test was used to determine the difference between the vertical jump performance of the participants before and after different stretching exercises. As a result, this study showed that; applying the dynamic and static stretching exercises consecutively affected the vertical jump performance 4.5 cm positively (p<.05. It is suggested that different dynamic and static stretching exercises should be included in the vertical jump.

Single-mode amplification in Yb-doped rod-type photonic crystal fibers for high brilliance lasers

DEFF Research Database (Denmark)

Poli, F.; Lægsgaard, Jesper; Passaro, D.

2009-01-01

This paper presents the effect of a low refractive index ring in the Yb-doped rod-type photonic crystal fibre core on the guided mode propagation and analyzed through a spatial and spectral amplifier model. The ring provides a higher differential overlap between the fundamental mode (FM...... to identify a proper ring characteristic that is width, position and refractive index. Then rod-type PCF designs have been optimized with a full-vector modal solver based on the finite-element method. Then, the amplification properties of the Yb-doped rod-type PCFs have been investigated by assuming a forward...

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.

Phase transitions in single macromolecules: Loop-stretch transition versus loop adsorption transition in end-grafted polymer chains

Science.gov (United States)

Zhang, Shuangshuang; Qi, Shuanhu; Klushin, Leonid I.; Skvortsov, Alexander M.; Yan, Dadong; Schmid, Friederike

2018-01-01

We use Brownian dynamics simulations and analytical theory to compare two prominent types of single molecule transitions. One is the adsorption transition of a loop (a chain with two ends bound to an attractive substrate) driven by an attraction parameter ɛ and the other is the loop-stretch transition in a chain with one end attached to a repulsive substrate, driven by an external end-force F applied to the free end. Specifically, we compare the behavior of the respective order parameters of the transitions, i.e., the mean number of surface contacts in the case of the adsorption transition and the mean position of the chain end in the case of the loop-stretch transition. Close to the transition points, both the static behavior and the dynamic behavior of chains with different length N are very well described by a scaling ansatz with the scaling parameters (ɛ - ɛ*)Nϕ (adsorption transition) and (F - F*)Nν (loop-stretch transition), respectively, where ϕ is the crossover exponent of the adsorption transition and ν is the Flory exponent. We show that both the loop-stretch and the loop adsorption transitions provide an exceptional opportunity to construct explicit analytical expressions for the crossover functions which perfectly describe all simulation results on static properties in the finite-size scaling regime. Explicit crossover functions are based on the ansatz for the analytical form of the order parameter distributions at the respective transition points. In contrast to the close similarity in equilibrium static behavior, the dynamic relaxation at the two transitions shows qualitative differences, especially in the strongly ordered regimes. This is attributed to the fact that the surface contact dynamics in a strongly adsorbed chain is governed by local processes, whereas the end height relaxation of a strongly stretched chain involves the full spectrum of Rouse modes.

Resting state networks' corticotopy: the dual intertwined rings architecture.

Directory of Open Access Journals (Sweden)

Salma Mesmoudi

Full Text Available How does the brain integrate multiple sources of information to support normal sensorimotor and cognitive functions? To investigate this question we present an overall brain architecture (called "the dual intertwined rings architecture" that relates the functional specialization of cortical networks to their spatial distribution over the cerebral cortex (or "corticotopy". Recent results suggest that the resting state networks (RSNs are organized into two large families: 1 a sensorimotor family that includes visual, somatic, and auditory areas and 2 a large association family that comprises parietal, temporal, and frontal regions and also includes the default mode network. We used two large databases of resting state fMRI data, from which we extracted 32 robust RSNs. We estimated: (1 the RSN functional roles by using a projection of the results on task based networks (TBNs as referenced in large databases of fMRI activation studies; and (2 relationship of the RSNs with the Brodmann Areas. In both classifications, the 32 RSNs are organized into a remarkable architecture of two intertwined rings per hemisphere and so four rings linked by homotopic connections. The first ring forms a continuous ensemble and includes visual, somatic, and auditory cortices, with interspersed bimodal cortices (auditory-visual, visual-somatic and auditory-somatic, abbreviated as VSA ring. The second ring integrates distant parietal, temporal and frontal regions (PTF ring through a network of association fiber tracts which closes the ring anatomically and ensures a functional continuity within the ring. The PTF ring relates association cortices specialized in attention, language and working memory, to the networks involved in motivation and biological regulation and rhythms. This "dual intertwined architecture" suggests a dual integrative process: the VSA ring performs fast real-time multimodal integration of sensorimotor information whereas the PTF ring performs multi

Resting State Networks' Corticotopy: The Dual Intertwined Rings Architecture

Science.gov (United States)

Mesmoudi, Salma; Perlbarg, Vincent; Rudrauf, David; Messe, Arnaud; Pinsard, Basile; Hasboun, Dominique; Cioli, Claudia; Marrelec, Guillaume; Toro, Roberto; Benali, Habib; Burnod, Yves

2013-01-01

How does the brain integrate multiple sources of information to support normal sensorimotor and cognitive functions? To investigate this question we present an overall brain architecture (called “the dual intertwined rings architecture”) that relates the functional specialization of cortical networks to their spatial distribution over the cerebral cortex (or “corticotopy”). Recent results suggest that the resting state networks (RSNs) are organized into two large families: 1) a sensorimotor family that includes visual, somatic, and auditory areas and 2) a large association family that comprises parietal, temporal, and frontal regions and also includes the default mode network. We used two large databases of resting state fMRI data, from which we extracted 32 robust RSNs. We estimated: (1) the RSN functional roles by using a projection of the results on task based networks (TBNs) as referenced in large databases of fMRI activation studies; and (2) relationship of the RSNs with the Brodmann Areas. In both classifications, the 32 RSNs are organized into a remarkable architecture of two intertwined rings per hemisphere and so four rings linked by homotopic connections. The first ring forms a continuous ensemble and includes visual, somatic, and auditory cortices, with interspersed bimodal cortices (auditory-visual, visual-somatic and auditory-somatic, abbreviated as VSA ring). The second ring integrates distant parietal, temporal and frontal regions (PTF ring) through a network of association fiber tracts which closes the ring anatomically and ensures a functional continuity within the ring. The PTF ring relates association cortices specialized in attention, language and working memory, to the networks involved in motivation and biological regulation and rhythms. This “dual intertwined architecture” suggests a dual integrative process: the VSA ring performs fast real-time multimodal integration of sensorimotor information whereas the PTF ring performs multi

Cascade conical refraction for annular pumping of a vortex Nd:YAG laser and selective excitation of low- and high-order Laguerre–Gaussian modes

Science.gov (United States)

Wu, Yongxiao; Wang, Zhongyang; Chen, Sanbin; Shirakwa, Akira; Ueda, Ken-ichi; Li, Jianlang

2018-05-01

We proposed an efficient and vortex Nd:YAG laser for selective lasing of low- and high-order vortex modes, in which multiple-ring pump light was originated from cascaded conical refraction of multiple biaxial crystals. In our proof of concept demonstration, we used two-crystal cascade conical refraction to generate two-ring pump light; the mutual intensity ratio and relative separation of the inner ring and outer ring were controlled by rotating the second biaxial crystal and by moving the imaging lens, respectively. As a result, we obtained selective excitation of Laguerre–Gaussian (LG01 and LG03) vortex modes in the end-pump Nd:YAG laser. For LG01-mode output, the laser power reached 439 mW with 52.5% slope efficiency; for LG03-mode output, the laser power reached 160 mW with 41.3% slope efficiency. Our results revealed that the multiple-ring pumping technique based on cascaded conical refraction would pave the way for realization of the efficient and switchable excitation of low- and high-order LG modes in an end-pumped solid-state laser.

Storage-ring FEL for the vuv

International Nuclear Information System (INIS)

Peterson, J.M.; Bisognano, J.J.; Garren, A.A.; Halbach, K.; Kim, K.J.; Sah, R.C.

1984-09-01

A free-electron laser for the vuv operating in a storage ring requires an electron beam of high density and low energy spread and a short wavelength, narrow-gap undulator. These conditions tend to produce longitudinal and transverse beam instabilities, excessive beam growth through multiple intrabeam scattering, and a short gas-scattering lifetime. Passing the beam only occasionally through the undulator in a by-pass straight section, as proposed by Murphy and Pellegrini, allows operation in a high-gain, single-pass mode and a long gas-scattering lifetime. Several storage ring designs have been considered to see how best to satisfy the several requirements. Each features a by-pass, a low-emittance lattice, and built-in wigglers for enhanced damping to counteract the intra-beam scattering. 15 references, 3 figures, 2 tables

A Japanese Stretching Intervention Can Modify Lumbar Lordosis Curvature.

Science.gov (United States)

Kadono, Norio; Tsuchiya, Kazushi; Uematsu, Azusa; Kamoshita, Hiroshi; Kiryu, Kazunori; Hortobágyi, Tibor; Suzuki, Shuji

2017-08-01

Eighteen healthy male adults were assigned to either an intervention or control group. Isogai dynamic therapy (IDT) is one of Japanese stretching interventions and has been practiced for over 70 years. However, its scientific quantitative evidence remains unestablished. The objective of this study was to determine whether IDT could modify lumbar curvature in healthy young adults compared with stretching exercises used currently in clinical practice. None of previous studies have provided data that conventional stretching interventions could modify spinal curvatures. However, this study provides the first evidence that a specific form of a Japanese stretching intervention can acutely modify the spinal curvatures. We compared the effects of IDT, a Japanese stretching intervention (n=9 males), with a conventional stretching routine (n=9 males) used widely in clinics to modify pelvic tilt and lumbar lordosis (LL) angle. We measured thoracic kyphosis (TK) and LL angles 3 times during erect standing using the Spinal Mouse before and after each intervention. IDT consisted of: (1) hip joint correction, (2) pelvic tilt correction, (3) lumbar alignment correction, and (4) squat exercise stretch. The control group performed hamstring stretches while (1) standing and (2) sitting. IDT increased LL angle to 25.1 degrees (±5.9) from 21.2 degrees (±6.9) (P=0.047) without changing TK angle (pretest: 36.8 degrees [±6.9]; posttest: 36.1 degrees [±6.5]) (P=0.572). The control group showed no changes in TK (P=0.819) and LL angles (P=0.744). IDT can thus be effective for increasing LL angle, hence anterior pelvic tilt. Such modifications could ameliorate low back pain and improve mobility in old adults with an unfavorable pelvic position.

Prenatal Diagnosis of a Fetus with Congenital Heart Defect and Ring Chromosome 14

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Javier Sánchez

2012-01-01

Full Text Available Monosomy of chromosome 14 has been reported in only a few prenatal cases. Generally, this monosomy is associated with a mosaicism of ring chromosome 14. Ring chromosome 14 is a rare cytogenetic entity with clinical characteristics that include growth retardation, facial dysmorphia, hypotonia, seizures, and retinitis pigmentosa. Given that the majority of symptoms appear postnatally, few cases have been reported of prenatal diagnosis of mosaicism monosomy/ring chromosome 14. We describe the prenatal diagnosis of a case of chromosomal mosaicism, a cell line with ring chromosome 14, r(14, and a second cell line with monosomy 14, in a fetus with aortic coarctation and chamber asymmetry. This is the first case of a prenatal diagnosis associating mosaicism with ring chromosome 14, monosomy 14, and fetal cardiopathy. We identified the exact breakpoint in ring chromosome 14 in IGH locus, which may provide further insight into the mode of ring formation as well as prenatal findings.

Mode specificity in the OH + CHD3 reaction: Reduced-dimensional quantum and quasi-classical studies on an ab initio based full-dimensional potential energy surface

International Nuclear Information System (INIS)

Song, Hongwei; Yang, Minghui; Lu, Yunpeng; Li, Jun; Guo, Hua

2016-01-01

An initial state selected time-dependent wave packet method is applied to study the dynamics of the OH + CHD 3 reaction with a six-dimensional model on a newly developed full-dimensional ab initio potential energy surface (PES). This quantum dynamical (QD) study is complemented by full-dimensional quasi-classical trajectory (QCT) calculations on the same PES. The QD results indicate that both translational energy and the excitation of the CH stretching mode significantly promote the reaction while the excitation of the umbrella mode has a negligible effect on the reactivity. For this early barrier reaction, interestingly, the CH stretching mode is more effective than translational energy in promoting the reaction except at very low collision energies. These QD observations are supported by QCT results. The higher efficacy of the CH stretching model in promoting this early barrier reaction is inconsistent with the prediction of the naively extended Polanyi’s rules, but can be rationalized by the recently proposed sudden vector projection model.

The influence of stretching on tensile strength and solubility of poly(vinyl alcohol) fibres

NARCIS (Netherlands)

Heikens, D.; Bleijenberg, A.C.A.M.; Hoppenbrouwers, J.J.M.; Barentsen, W.M.

1971-01-01

The strength of wet-spun poly(vinyl alcohol) (pva) fibres is given as function of bath-stretching, wet-stretching and hot-stretching. In the two equations derived for strength of wet-stretching and hot-stretching the complex influence of the bath-stretching and hot-stretching is demonstrated. The

Longitudinal bunch deformation of a multi-bunched beam in the TRISTAN Accumulation Ring

International Nuclear Information System (INIS)

Obina, T.; Satoh, K.; Kasuga, T.; Funakoshi, Y.; Tobiyama, M.

1997-01-01

A remarkable bunch deformation has been observed in the TRISTAN Accumulation Ring (AR) during multi-bunch operations. When two bunches that have different populations are stored in the ring, the bunch length of the weaker bunch is longer than that of the stronger one. The phenomenon can be explained as an effect of wake fields due to higher-order modes (HOMs) of accelerating cavities. We tried to find out the frequency of the mode and the strength of the wake field, and introduced a new technique called a test bunch measurement. The estimated field strength from the experiment shows a reasonable agreement with the calculation of HOM impedance. copyright 1997 American Institute of Physics

Mechanical stretching effect on the actuator performance of cellulose electroactive paper

International Nuclear Information System (INIS)

Kim, Jung-Hwan; Yun, Ki-Ju; Kim, Joo-Hyung; Kim, Jaehwan

2009-01-01

The mechanical stretching effect on the actuating performance of electroactive cellulose paper (EAPap) was studied. A lattice elongation of cellulose fibrils due to in-plane tensile stress along the stretching direction was observed by the x-ray diffraction method. The shrinkage of the fibril diameter as a function of stretching ratio was confirmed by surface and cross-sectional images. While the actuator performance in terms of bending displacement decreased as the stretching ratio increased, the resonance frequency linearly increased as the stretching ratio increased, which was compared with the theoretical frequency data found from a cantilever beam model. The actuator efficiency was evaluated from the electrical input power consumption and the mechanical output power of an EAPap actuator. It was revealed that the stretching process increased the electro-mechanical efficiency of the EAPap actuator. The mechanism of the influence of the stretching effect on the performance of an EAPap actuator is discussed

Spontaneous bending of pre-stretched bilayers.

Science.gov (United States)

DeSimone, Antonio

2018-01-01

We discuss spontaneously bent configurations of pre-stretched bilayer sheets that can be obtained by tuning the pre-stretches in the two layers. The two-dimensional nonlinear plate model we use for this purpose is an adaptation of the one recently obtained for thin sheets of nematic elastomers, by means of a rigorous dimensional reduction argument based on the theory of Gamma-convergence (Agostiniani and DeSimone in Meccanica. doi:10.1007/s11012-017-0630-4, 2017, Math Mech Solids. doi:10.1177/1081286517699991, arXiv:1509.07003, 2017). We argue that pre-stretched bilayer sheets provide us with an interesting model system to study shape programming and morphing of surfaces in other, more complex systems, where spontaneous deformations are induced by swelling due to the absorption of a liquid, phase transformations, thermal or electro-magnetic stimuli. These include bio-mimetic structures inspired by biological systems from both the plant and the animal kingdoms.

Optofluidic time-stretch quantitative phase microscopy.

Science.gov (United States)

Guo, Baoshan; Lei, Cheng; Wu, Yi; Kobayashi, Hirofumi; Ito, Takuro; Yalikun, Yaxiaer; Lee, Sangwook; Isozaki, Akihiro; Li, Ming; Jiang, Yiyue; Yasumoto, Atsushi; Di Carlo, Dino; Tanaka, Yo; Yatomi, Yutaka; Ozeki, Yasuyuki; Goda, Keisuke

2018-03-01

Innovations in optical microscopy have opened new windows onto scientific research, industrial quality control, and medical practice over the last few decades. One of such innovations is optofluidic time-stretch quantitative phase microscopy - an emerging method for high-throughput quantitative phase imaging that builds on the interference between temporally stretched signal and reference pulses by using dispersive properties of light in both spatial and temporal domains in an interferometric configuration on a microfluidic platform. It achieves the continuous acquisition of both intensity and phase images with a high throughput of more than 10,000 particles or cells per second by overcoming speed limitations that exist in conventional quantitative phase imaging methods. Applications enabled by such capabilities are versatile and include characterization of cancer cells and microalgal cultures. In this paper, we review the principles and applications of optofluidic time-stretch quantitative phase microscopy and discuss its future perspective. Copyright © 2017 Elsevier Inc. All rights reserved.

Amplitude and polarization asymmetries in a ring laser

Science.gov (United States)

Campbell, L. L.; Buholz, N. E.

1971-01-01

Asymmetric amplitude effects between the oppositely directed traveling waves in a He-Ne ring laser are analyzed both theoretically and experimentally. These effects make it possible to detect angular orientations of an inner-cavity bar with respect to the plane of the ring cavity. The amplitude asymmetries occur when a birefringent bar is placed in the three-mirror ring cavity, and an axial magnetic field is applied to the active medium. A simplified theoretical analysis is performed by using a first order perturbation theory to derive an expression for the polarization of the active medium, and a set of self-consistent equations are derived to predict threshold conditions. Polarization asymmetries between the oppositely directed waves are also predicted. Amplitude asymmetries similar in nature to those predicted at threshold occur when the laser is operating in 12-15 free-running modes, and polarization asymmetry occurs simultaneously.

ACUTE EFFECTS OF THREE DIFFERENT STRETCHING PROTOCOLS ON THE WINGATE TEST PERFORMANCE

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Bruno L. Franco

2012-03-01

Full Text Available The purpose of this study was to examine the acute effects of different stretching exercises on the performance of the traditional Wingate test (WT. Fifteen male participants performed five WT; one for familiarization (FT, and the remaining four after no stretching (NS, static stretching (SS, dynamic stretching (DS, and proprioceptive neuromuscular facilitation (PNF. Stretches were targeted for the hamstrings, quadriceps, and calf muscles. Peak power (PP, mean power (MP, and the time to reach PP (TP were calculated. The MP was significantly lower when comparing the DS (7.7 ± 0.9 W/kg to the PNF (7.3 ± 0.9 W/kg condition (p < 0.05. For PP, significant differences were observed between more comparisons, with PNF stretching providing the lowest result. A consistent increase of TP was observed after all stretching exercises when compared to NS. The results suggest the type of stretching, or no stretching, should be considered by those who seek higher performance and practice sports that use maximal anaerobic power.

Effects of Static Stretching and Playing Soccer on Knee Laxity.

Science.gov (United States)

Baumgart, Christian; Gokeler, Alli; Donath, Lars; Hoppe, Matthias W; Freiwald, Jürgen

2015-11-01

This study investigated exercise-induced effects of static stretching and playing soccer on anterior tibial translation (ATT) of the knee joint. Randomized controlled trial. University biomechanics laboratory. Thirty-one athletes were randomly assigned into a stretching (26.9 ± 6.2 years, 1.77 ± 0.09 m, 67.9 ± 10.7 kg) and a control group (27.9 ± 7.4 years, 1.75 ± 0.08 m, 72.0 ± 14.9 kg). Thirty-one amateur soccer players in an additional soccer group (25.1 ± 5.6 years, 1.74 ± 0.10 m, 71.8 ± 14.8 kg). All participants had no history of knee injury requiring surgery and any previous knee ligament or cartilage injury. The stretching group performed 4 different static stretching exercises with a duration of 2 × 20 seconds interspersed with breaks of 10 seconds. The soccer group completed a 90-minute soccer-specific training program. The control group did not perform any physical activity for approximately 30 minutes. Anterior tibial translation was measured with the KT-1000 knee arthrometer at forces of 67 N, 89 N, and maximal manual force (Max) before and after the intervention. There was a significant increase in ATT after static stretching and playing soccer at all applied forces. Maximal manual testing revealed a mean increase of ATT after static stretching of 2.1 ± 1.6 mm (P soccer of 1.0 ± 1.5 mm (P = 0.001). The ATT increase after static stretching at 67 and 89 N is significantly higher than in controls. At maximum manual testing, significant differences were evident between all groups. Static stretching and playing soccer increase ATT and may consequently influence mechanical factors of the anterior cruciate ligament. The ATT increase after static stretching was greater than after playing soccer. The observed increase in ATT after static stretching and playing soccer may be associated with changes in kinesthetic perception and sensorimotor control, activation of muscles, joint stability, overall performance, and higher injury risk.

Correlations and the Ring-Kinetic Equation in Dense Sheared Granular Flows

Science.gov (United States)

Kumaran, V.

A formal way of deriving fluctuation-correlation relations in densesheared granular media, starting with the Enskog approximation for the collision integral in the Chapman-Enskog theory, is discussed. The correlation correction to the viscosity is obtained using the ring-kinetic equation, in terms of the correlations in the hydrodynamic modes of the linearised Enskog equation. It is shown that the Green-Kubo formula for the shear viscosity emerges from the two-body correlation function obtained from the ring-kinetic equation.

Acute effect of different stretching methods on isometric muscle strength

Directory of Open Access Journals (Sweden)

Gabriel Vasconcellos de Lima Costa e Silva

2014-03-01

This study investigated the acute effect of static stretching methods (SS and proprioceptive neuromuscular facilitation (PNF on the static muscle strength (SMS. Eleven young male subjects with strength training experience, performed 3 tests with a 48h interval between them, randomly selected, where each one subject carried out all procedures: a hand grip without stretching; b hand grip preceded by static stretching of wrist flexors muscles; c hand grip preceded by PNF stretching of wrist flexors muscles. The Shapiro-Wilk test verified the normality of data, and a one-way ANOVA with repeated measures, followed by Tukey’s post hoc test, evaluated the differences between the groups. The significance was set at p 0.05. In conclusion, both stretching methods had caused negative effects on isometric strength, reducing its levels.

Observing microscopic structures of a relativistic object using a time-stretch strategy

Science.gov (United States)

Roussel, E.; Evain, C.; Le Parquier, M.; Szwaj, C.; Bielawski, S.; Manceron, L.; Brubach, J.-B.; Tordeux, M.-A.; Ricaud, J.-P.; Cassinari, L.; Labat, M.; Couprie, M.-E.; Roy, P.

2015-05-01

Emission of light by a single electron moving on a curved trajectory (synchrotron radiation) is one of the most well-known fundamental radiation phenomena. However experimental situations are more complex as they involve many electrons, each being exposed to the radiation of its neighbors. This interaction has dramatic consequences, one of the most spectacular being the spontaneous formation of spatial structures inside electrons bunches. This fundamental effect is actively studied as it represents one of the most fundamental limitations in electron accelerators, and at the same time a source of intense terahertz radiation (Coherent Synchrotron Radiation, or CSR). Here we demonstrate the possibility to directly observe the electron bunch microstructures with subpicosecond resolution, in a storage ring accelerator. The principle is to monitor the terahertz pulses emitted by the structures, using a strategy from photonics, time-stretch, consisting in slowing-down the phenomena before recording. This opens the way to unpreceeded possibilities for analyzing and mastering new generation high power coherent synchrotron sources.

Upper Limb Static-Stretching Protocol Decreases Maximal Concentric Jump Performance

Directory of Open Access Journals (Sweden)

Paulo H. Marchetti

2014-12-01

Full Text Available The purpose of the present study was to evaluate the acute effects of an upper limb static-stretching (SS protocol on the maximal concentric jump performance. We recruited 25 young healthy, male, resistance trained individuals (stretched group, n = 15 and control group, n = 10 in this study. The randomized between group experimental protocol consisted of a three trials of maximal concentric jump task, before and after a SS of the upper limb. Vertical ground reaction forces (vGRF and surface electromyography (sEMG of both gastrocnemius lateralis (GL and vastus lateralis (VL were acquired. An extensive SS was employed consisting of ten stretches of 30 seconds, with 15 seconds of rest, and 70-90% of the point of discomfort (POD. ANOVA (2x2 (group x condition was used for shoulder joint range of motion (ROM, vGRF and sEMG. A significant interaction for passive ROM of the shoulder joint revealed significant increases between pre- and post-SS protocol (p < 0.001. A significant interaction demonstrated decreased peak force and an increased peak propulsion duration between pre- and post-stretching only for stretch group (p = 0.021, and p = 0.024, respectively. There was a significant main effect between groups (stretch and control for peak force for control group (p = 0.045. Regarding sEMG variables, there were no significant differences between groups (control versus stretched or condition (pre-stretching versus post-stretching for the peak amplitude of RMS and IEMG for both muscles (VL and GL. In conclusion, an acute extensive SS can increase the shoulder ROM, and negatively affect both the propulsion duration and peak force of the maximal concentric jump, without providing significant changes in muscle activation.

Cyclic Stretch Alters Vascular Reactivity of Mouse Aortic Segments

Directory of Open Access Journals (Sweden)

Arthur Leloup

2017-10-01

Full Text Available Large, elastic arteries buffer the pressure wave originating in the left ventricle and are constantly exposed to higher amplitudes of cyclic stretch (10% than muscular arteries (2%. As a crucial factor for endothelial and smooth muscle cell function, cyclic stretch has, however, never been studied in ex vivo aortic segments of mice. To investigate the effects of cyclic stretch on vaso-reactivity of mouse aortic segments, we used the Rodent Oscillatory Tension Set-up to study Arterial Compliance (ROTSAC. The aortic segments were clamped at frequencies of 6–600 bpm between two variable preloads, thereby mimicking dilation as upon left ventricular systole and recoiling as during diastole. The preloads corresponding to different transmural pressures were chosen to correspond to a low, normal or high amplitude of cyclic stretch. At different time intervals, cyclic stretch was interrupted, the segments were afterloaded and isometric contractions by α1-adrenergic stimulation with 2 μM phenylephrine in the absence and presence of 300 μM L-NAME (eNOS inhibitor and/or 35 μM diltiazem (blocker of voltage-gated Ca2+ channels were measured. As compared with static or cyclic stretch at low amplitude (<10 mN or low frequency (0.1 Hz, cyclic stretch at physiological amplitude (>10 mN and frequency (1–10 Hz caused better ex vivo conservation of basal NO release with time after mounting. The relaxation of PE-precontracted segments by addition of ACh to stimulate NO release was unaffected by cyclic stretch. In the absence of basal NO release (hence, presence of L-NAME, physiological in comparison with aberrant cyclic stretch decreased the baseline tension, attenuated the phasic contraction by phenylephrine in the absence of extracellular Ca2+ and shifted the smaller tonic contraction more from a voltage-gated Ca2+ channel-mediated to a non-selective cation channel-mediated. Data highlight the need of sufficient mechanical activation of endothelial and

Mode specificity in the OH + CHD{sub 3} reaction: Reduced-dimensional quantum and quasi-classical studies on an ab initio based full-dimensional potential energy surface

Energy Technology Data Exchange (ETDEWEB)

Song, Hongwei, E-mail: hwsong@wipm.ac.cn; Yang, Minghui [Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Lu, Yunpeng [Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Li, Jun [School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China); Guo, Hua [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

2016-04-28

An initial state selected time-dependent wave packet method is applied to study the dynamics of the OH + CHD{sub 3} reaction with a six-dimensional model on a newly developed full-dimensional ab initio potential energy surface (PES). This quantum dynamical (QD) study is complemented by full-dimensional quasi-classical trajectory (QCT) calculations on the same PES. The QD results indicate that both translational energy and the excitation of the CH stretching mode significantly promote the reaction while the excitation of the umbrella mode has a negligible effect on the reactivity. For this early barrier reaction, interestingly, the CH stretching mode is more effective than translational energy in promoting the reaction except at very low collision energies. These QD observations are supported by QCT results. The higher efficacy of the CH stretching model in promoting this early barrier reaction is inconsistent with the prediction of the naively extended Polanyi’s rules, but can be rationalized by the recently proposed sudden vector projection model.

Modeling multipulsing transition in ring cavity lasers with proper orthogonal decomposition

International Nuclear Information System (INIS)

Ding, Edwin; Shlizerman, Eli; Kutz, J. Nathan

2010-01-01

A low-dimensional model is constructed via the proper orthogonal decomposition (POD) to characterize the multipulsing phenomenon in a ring cavity laser mode locked by a saturable absorber. The onset of the multipulsing transition is characterized by an oscillatory state (created by a Hopf bifurcation) that is then itself destabilized to a double-pulse configuration (by a fold bifurcation). A four-mode POD analysis, which uses the principal components, or singular value decomposition modes, of the mode-locked laser, provides a simple analytic framework for a complete characterization of the entire transition process and its associated bifurcations. These findings are in good agreement with the full governing equation.

Operation and Recent Developments of the Photon Factory Advanced Ring

CERN Document Server

Miyajima, Tsukasa; Ebihara, Kiyokazu; Haga, Kaiichi; Harada, Kentaro; Hori, Yoichiro; Ieiri, Takao; Isagawa, Shigeru; Kageyama, Tatsuya; Kasuga, Toshio; Katoh, Tadahiko; Kawata, Hiroshi; Kikuchi, Mitsuo; Kobayashi, Yukinori; Kudo, Kikuo; Mitsuhashi, Toshiyuki; Nagahashi, Shinya; Nakamura, Tatsuro; Nakanishi, Hiroshi; Nogami, Takashi; Obina, Takashi; Ohsawa, Yasunobu; Ono, Masaaki; Ozaki, Toshiyuki; Sakai, Hiroshi; Sakamoto, Yutaka; Sakanaka, Shogo; Sato, Masayuki; Satoh, Masato; Shioya, Tatsuro; Suetake, Masaaki; Sugahara, Ryuhei; Tadano, Mikito; Takahashi, Takeshi; Takasaki, Seiji; Tanimoto, Yasunori; Tejima, Masaki; Tsuchiya, Kimichika; Uchiyama, Takashi; Ueda, Akira; Umemori, Kensei; Xing Cheng, Wei; Yamamoto, Noboru; Yamamoto, Shigeru; Yoshimoto, S

2005-01-01

The Photon Factory Advanced Ring (PF-AR) is a synchrotron light source dedicated to X-ray research. The PF-AR is usually operated at a beam energy of 6.5 GeV, but a 5.0 GeV mode is also available for medical application. In 6.5 GeV mode the typical lifetime of 15 hrs and the beam current of 60 mA with a single-bunch have been archived. Almost full-time single-bunch operation for pulse X-ray characterize the PF-AR. However, single-bunch high-current caused several problems to be solved, including the temperature rise of the some of the vacuum component, a pressure increase in the ring, and a sudden drop in lifetime. In order to avoid these issues the developments of new methods have been continued. In this paper, the status and the recent developments of the PF-AR will be presented. It concerns: the successful operation with two-bunch high-current in 5.0 GeV mode; varying the vertical beam size for the medical application; modulating the RF acceleration phase in order to elongate the length of bunch; stabilizi...

Stretching skeletal muscle: chronic muscle lengthening through sarcomerogenesis.

Directory of Open Access Journals (Sweden)

Alexander M Zöllner

Full Text Available Skeletal muscle responds to passive overstretch through sarcomerogenesis, the creation and serial deposition of new sarcomere units. Sarcomerogenesis is critical to muscle function: It gradually re-positions the muscle back into its optimal operating regime. Animal models of immobilization, limb lengthening, and tendon transfer have provided significant insight into muscle adaptation in vivo. Yet, to date, there is no mathematical model that allows us to predict how skeletal muscle adapts to mechanical stretch in silico. Here we propose a novel mechanistic model for chronic longitudinal muscle growth in response to passive mechanical stretch. We characterize growth through a single scalar-valued internal variable, the serial sarcomere number. Sarcomerogenesis, the evolution of this variable, is driven by the elastic mechanical stretch. To analyze realistic three-dimensional muscle geometries, we embed our model into a nonlinear finite element framework. In a chronic limb lengthening study with a muscle stretch of 1.14, the model predicts an acute sarcomere lengthening from 3.09[Formula: see text]m to 3.51[Formula: see text]m, and a chronic gradual return to the initial sarcomere length within two weeks. Compared to the experiment, the acute model error was 0.00% by design of the model; the chronic model error was 2.13%, which lies within the rage of the experimental standard deviation. Our model explains, from a mechanistic point of view, why gradual multi-step muscle lengthening is less invasive than single-step lengthening. It also explains regional variations in sarcomere length, shorter close to and longer away from the muscle-tendon interface. Once calibrated with a richer data set, our model may help surgeons to prevent muscle overstretch and make informed decisions about optimal stretch increments, stretch timing, and stretch amplitudes. We anticipate our study to open new avenues in orthopedic and reconstructive surgery and enhance

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.

Enhanced spin wave propagation in magnonic rings by bias field modulation

Science.gov (United States)

Venkat, G.; Venkateswarlu, D.; Joshi, R. S.; Franchin, M.; Fangohr, H.; Anil Kumar, P. S.; Prabhakar, A.

2018-05-01

We simulate the spin wave (SW) dynamics in ring structures and obtain the ω - k dispersion relations corresponding to the output waveguide. Different bias field configurations affect the transfer of SW power from one arm of the structure to the other arm. To this end, we show that circular or radial bias fields are more suitable for energy transfer across the ring than the conventional horizontal bias field Hx. The SW dispersion shows that modes excited, when the bias field is along the ring radius, are almost 10 dB higher in power when compared to the modal power in the case of Hx. This is also corroborated by the SW energy density in the receiving stub.

Hydrogen-Bonding Network and OH Stretch Vibration of Cellulose: Comparison of Computational Modeling with Polarized IR and SFG Spectra.

Science.gov (United States)

Lee, Christopher M; Kubicki, James D; Fan, Bingxin; Zhong, Linghao; Jarvis, Michael C; Kim, Seong H

2015-12-10

Hydrogen bonds play critical roles in noncovalent directional interactions determining the crystal structure of cellulose. Although diffraction studies accurately determined the coordinates of carbon and oxygen atoms in crystalline cellulose, the structural information on hydrogen atoms involved in hydrogen-bonding is still elusive. This could be complemented by vibrational spectroscopy; but the assignment of the OH stretch peaks has been controversial. In this study, we performed calculations using density functional theory with dispersion corrections (DFT-D2) for the cellulose Iβ crystal lattices with the experimentally determined carbon and oxygen coordinates. DFT-D2 calculations revealed that the OH stretch vibrations of cellulose are highly coupled and delocalized through intra- and interchain hydrogen bonds involving all OH groups in the crystal. Additionally, molecular dynamics (MD) simulations of a single cellulose microfibril showed that the conformations of OH groups exposed at the microfibril surface are not well-defined. Comparison of the computation results with the experimentally determined IR dichroism of uniaxially aligned cellulose microfibrils and the peak positions of various cellulose crystals allowed unambiguous identification of OH stretch modes observed in the vibrational spectra of cellulose.

Static versus dynamic stretching: Chronic and acute effects on Agility performance in male athletes

Directory of Open Access Journals (Sweden)

Iman Taleb-Beydokhti

2015-04-01

Full Text Available The purpose of this study was to examine the acute and chronic effects of static & dynamic stretching protocols on agility performance in amateur handball players. Twelve male amateur handball players (age: 19.66 ± 4.02 years old, weight: 67.12 ± 8.73 kg, height: 178.29 ± 7.81 cm participated in this study. The athletes were randomly allocated into two groups: static stretching or dynamic stretching. All of them underwent an initial evaluation and were submitted to the first intervention. They were evaluated once again and at the end of 12 training sessions. The results analyzed using ANOVA showed that there was a significant decrease in agility time after dynamic stretching against no stretching in the acute phase; but, there were no significant differences between dynamic stretching and no stretching in the chronic phase. In addition, there was no a significant difference between no stretching and static stretching in the acute phase; while, There was a significant decrease in agility time after no stretching against static stretching in the chronic phase. It was concluded that acute dynamic stretching as part of a warm-up may decrease agility time performance, whereas static stretching seems to increase agility time performance. Consequently, the acute and chronic static stretching should not be performed prior to an explosive athletic performance. Keywords: Handball, Agility, Dynamic stretching, Static stretching

Run permit software for the proton storage ring

International Nuclear Information System (INIS)

Bair, S.S.

1985-01-01

The Run Permit system is intended to protect equipment from radiation effects caused by having beam enabled when required equipment is not operational. This system will not allow beam unless certain devices are ready and will drop beam if any of these devices become inoperative. A system to provide such protection might be implemented in hardware. However, because the several operating modes of the Proton Storage Ring/Weapons Neutron Research facility require certain devices to be in different states (depending on mode), a dynamic configuration capability is needed, that is, a software solution is more feasible

Filament stretching rheometer: inertia compensation revisited

DEFF Research Database (Denmark)

Szabo, Peter; McKinley, Gareth H.

2003-01-01

The necessary inertia compensation used in the force balance for the filament stretching rheometer is derived for an arbitrary frame of reference. This enables the force balance to be used to extract correctly the extensional viscosity from measurements of the tensile force at either end of the e......The necessary inertia compensation used in the force balance for the filament stretching rheometer is derived for an arbitrary frame of reference. This enables the force balance to be used to extract correctly the extensional viscosity from measurements of the tensile force at either end...

High-resolution sub-Doppler infrared spectroscopy of atmospherically relevant Criegee precursor CH2I radicals: CH2 stretch vibrations and "charge-sloshing" dynamics

Science.gov (United States)

Kortyna, A.; Lesko, D. M. B.; Nesbitt, D. J.

2018-05-01

The combination of a pulsed supersonic slit-discharge source and single-mode difference frequency direct absorption infrared spectroscopy permit first high resolution infrared study of the iodomethyl (CH2I) radical, with the CH2I radical species generated in a slit jet Ne/He discharge and cooled to 16 K in the supersonic expansion. Dual laser beam detection and collisional collimation in the slit expansion yield sub-Doppler linewidths (60 MHz), an absolute frequency calibration of 13 MHz, and absorbance sensitivities within a factor of two of the shot-noise limit. Fully rovibrationally resolved direct absorption spectra of the CH2 symmetric stretch mode (ν2) are obtained and fitted to a Watson asymmetric top Hamiltonian with electron spin-rotation coupling, providing precision rotational constants and spin-rotation tensor elements for the vibrationally excited state. Analysis of the asymmetric top rotational constants confirms a vibrationally averaged planar geometry in both the ground- and first-excited vibrational levels. Sub-Doppler resolution permits additional nuclear spin hyperfine structures to be observed, with splittings in excellent agreement with microwave measurements on the ground state. Spectroscopic data on CH2I facilitate systematic comparison with previous studies of halogen-substituted methyl radicals, with the periodic trends strongly correlated with the electronegativity of the halogen atom. Interestingly, we do not observe any asymmetric CH2 stretch transitions, despite S/N ≈ 25:1 on strongest lines in the corresponding symmetric CH2 stretch manifold. This dramatic reversal of the more typical 3:1 antisymmetric/symmetric CH2 stretch intensity ratio signals a vibrational transition moment poorly described by simple "bond-dipole" models. Instead, the data suggest that this anomalous intensity ratio arises from "charge sloshing" dynamics in the highly polar carbon-iodine bond, as supported by ab initio electron differential density plots and

Characterization and optimization of an ultrasonic piezo-optical ring sensor

International Nuclear Information System (INIS)

Frankforter, Erik; Lin, Bin; Giurgiutiu, Victor

2016-01-01

A resonant piezo-optical ring sensor with both piezoelectric and fiber Bragg grating (FBG) sensing elements was assessed for ultrasonic wave detection. The ring sensor is an existing device that has been shown experimentally to exhibit a number of sensing features: omnidirectionality, mode selectivity, and frequency tunability. The present study uses finite element modeling to understand these features as a means to characterize and optimize the sensor. A combined vibration-wave propagation modeling approach was used, where the vibrational modeling provided a basis for understanding sensing features, and the wave propagation modeling provided predictive power for sensor performance. The sensor features corresponded to the fundamental vibrational mode of the sensor, particularly to the base motion of this mode. The vibrational modeling was also used to guide sensor optimization, with an emphasis on the FBG and piezoelectric sensing elements. It was found that sensor symmetry and nodes of extraneous resonance modes could be exploited to provide a single-resonance response. A series of pitch-catch guided wave experiments were performed on a thin aluminum plate to assess the optimized sensor configuration. Tuning curves showed a single-frequency response to a Lamb wave and mechanical filtering away from the dominant frequency; the sensor capability for mechanical amplification of a Lamb wave and mechanical amplification of a pencil-lead-break acoustic emission event were also demonstrated. (paper)

Report of the eRHIC Ring-Ring Working Group

Energy Technology Data Exchange (ETDEWEB)

Aschenauer, E. C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Berg, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Brennan, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Fedotov, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Fischer, W. [Brookhaven National Lab. (BNL), Upton, NY (United States); Litvinenko, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Montag, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Palmer, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Parker, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Peggs, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ptitsyn, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ranjbar, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tepikian, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Trbojevic, D. [Brookhaven National Lab. (BNL), Upton, NY (United States); Willeke, F. [Brookhaven National Lab. (BNL), Upton, NY (United States)

2015-10-13

This report evaluates the ring-ring option for eRHIC as a lower risk alternative to the linac-ring option. The reduced risk goes along with a reduced initial luminosity performance. However, a luminosity upgrade path is kept open. This upgrade path consists of two branches, with the ultimate upgrade being either a ring-ring or a linac-ring scheme. The linac-ring upgrade could be almost identical to the proposed linac-ring scheme, which is based on an ERL in the RHIC tunnel. This linac-ring version has been studied in great detail over the past ten years, and its significant risks are known. On the other hand, no detailed work on an ultimate performance ring-ring scenario has been performed yet, other than the development of a consistent parameter set. Pursuing the ring-ring upgrade path introduces high risks and requires significant design work that is beyond the scope of this report.

Optical bio-chemical sensors on SNOW ring resonators

Science.gov (United States)

Khorasaninejad, Mohammadreza; Clarke, Nigel; Anantram, M. P.; Singh Saini, Simarjeet

2011-08-01

In this paper, we propose and analyze novel ring resonator based bio-chemical sensors on silicon nanowire optical waveguide (SNOW) and show that the sensitivity of the sensors can be increased by an order of magnitude as compared to silicon-on-insulator based ring resonators while maintaining high index contrast and compact devices. The core of the waveguide is hollow and allows for introduction of biomaterial in the center of the mode, thereby increasing the sensitivity of detection. A sensitivity of 243 nm/refractive index unit (RIU) is achieved for a change in bulk refractive index. For surface attachment, the sensor is able to detect monolayer attachments as small as 1 Å on the surface of the silicon nanowires.

Coaxial higher-order mode damper employing a high-pass filter

International Nuclear Information System (INIS)

Kang, Y.W.; Jiang, X.

1997-01-01

Two different types of coaxial higher-order mode (HOM) dampers have been investigated for the Advanced Photon Source (APS) storage ring cavities: e-probe dampers and h-loop dampers. Realization of the h-loop dampers has been difficult because the loop antenna couples not only to the HOMs but also to the accelerating mode and results in loss of Q at the fundamental frequency. Previously, a first-order fundamental rejection filter was tested with unsatisfactory rejection characteristics. This problem can be overcome by using a higher-order high-pass filter between the loop and the matched load. Prototype dampers have been fabricated and tested in a storage ring single-cell cavity and the damping characteristic was analyzed

Stretching single fibrin fibers hampers their lysis.

Science.gov (United States)

Li, Wei; Lucioni, Tomas; Li, Rongzhong; Bonin, Keith; Cho, Samuel S; Guthold, Martin

2017-09-15

Blood clots, whose main structural component is a mesh of microscopic fibrin fibers, experience mechanical strain from blood flow, clot retraction and interactions with platelets and other cells. We developed a transparent, striated and highly stretchable substrate made from fugitive glue (a styrenic block copolymer) to investigate how mechanical strain affects lysis of single, suspended fibrin fibers. In this suspended fiber assay, lysis manifested itself by fiber elongation, thickening (disassembly), fraying and collapse. Stretching single fibrin fibers significantly hampered their lysis. This effect was seen in uncrosslinked and crosslinked fibers. Crosslinking (without stretching) also hampered single fiber lysis. Our data suggest that strain is a novel mechanosensitive factor that regulates blood clot dissolution (fibrinolysis) at the single fiber level. At the molecular level of single fibrin molecules, strain may distort, or hinder access to, plasmin cleavage sites and thereby hamper lysis. Fibrin fibers are the major structural component of a blood clot. We developed a highly stretchable substrate made from fugitive glue and a suspended fibrin fiber lysis assay to investigate the effect of stretching on single fibrin fibers lysis. The key findings from our experiments are: 1) Fibers thicken and elongate upon lysis; 2) stretching strongly reduces lysis; 3) this effect is more pronounced for uncrosslinked fibers; and 4) stretching fibers has a similar effect on reducing lysis as crosslinking fibers. At the molecular level, strain may distort plasmin cleavage sites, or restrict access to those sites. Our results suggest that strain may be a novel mechanobiological factor that regulates fibrinolysis. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Numerical investigation of a tunable band-pass plasmonic filter with a hollow-core ring resonator

International Nuclear Information System (INIS)

Setayesh, Amir; Mirnaziry, S Reza; Abrishamian, Mohammad Sadegh

2011-01-01

In this study, a compact nanoscale plasmonic filter which consists of two metal–insulator–metal (MIM) waveguides coupled to each other by a rectangular ring resonator is presented and investigated numerically. The propagating modes of surface plasmon polaritons (SPPs) are studied in this structure. By replacing a portion of the ring core with air, while the outer dimensions of the structure are kept constant, we illustrate the possibility of the redshift of resonant wavelengths in order to tune the resonance modes. This feature is useful for integrated circuits in which we have limitations on the outer dimensions of the filter structure and it is not possible to enlarge the dimension of the ring resonator to reach longer resonant wavelengths. The corresponding results are illustrated by the 2D finite-difference time-domain (FDTD) method. The proposed structure has potential applications in plasmonic integrated circuits and can be simply fabricated

Numerical investigation of a tunable band-pass plasmonic filter with a hollow-core ring resonator

Science.gov (United States)

Setayesh, Amir; Mirnaziry, S. Reza; Sadegh Abrishamian, Mohammad

2011-03-01

In this study, a compact nanoscale plasmonic filter which consists of two metal-insulator-metal (MIM) waveguides coupled to each other by a rectangular ring resonator is presented and investigated numerically. The propagating modes of surface plasmon polaritons (SPPs) are studied in this structure. By replacing a portion of the ring core with air, while the outer dimensions of the structure are kept constant, we illustrate the possibility of the redshift of resonant wavelengths in order to tune the resonance modes. This feature is useful for integrated circuits in which we have limitations on the outer dimensions of the filter structure and it is not possible to enlarge the dimension of the ring resonator to reach longer resonant wavelengths. The corresponding results are illustrated by the 2D finite-difference time-domain (FDTD) method. The proposed structure has potential applications in plasmonic integrated circuits and can be simply fabricated.

Broadband impedance of the NESTOR storage ring

International Nuclear Information System (INIS)

Androsov, V.P.; Gladkikh, P.I.; Gvozd, A.M.; Karnaukhov, I.M.; Telegin, Yu.N.

2011-01-01

The contributions from lossy and inductive vacuum chamber components to the broadband impedance of the NESTOR storage ring are obtained by using both low-frequency analytical approaches and computer simulations. As was expected considering the small ring circumference (15.44m), the main contributions both to the longitudinal impedance Z || /n and the loss factor k loss come from the RF-cavity. Cavity impedance was also estimated with CST Microwave Studio (CST Studio Suite TM 2006) by simulating coaxial wire method commonly used for impedance measurements. Both estimates agree well. Finally, we performed the simulations of a number of inductive elements with CST Particle Studio 2010 by using wake field solver. We have also evaluated the bunch length in NESTOR taking the conservative estimate of 3 Ohm for the ring broadband impedance and have found that the bunch length s z = 0.5 cm could be obtained in steady state operation mode for the designed bunch current of 10 mA and RF-voltage of 250 kV.

Characterizing the stretch-flangeability of hot rolled multiphase steels

International Nuclear Information System (INIS)

Pathak, N.; Butcher, C.; Worswick, M.; Gao, J.

2013-01-01

Hole expansion tests are commonly used to characterize the edge stretching limit of a material. Traditionally, a conical punch is used to expand a punched hole until a through-thickness crack appears. However, many automotive stretch flanging operations involve in-plane edge stretching that is best captured with a flat punch. In this paper, hole expansion tests were carried out on two different hot-rolled multiphase steels using both flat and conical punches. The fracture mechanisms for both punch types were investigated using scanning electron microscopy (SEM)

High-Q contacted ring microcavities with scatterer-avoiding “wiggler” Bloch wave supermode fields

Energy Technology Data Exchange (ETDEWEB)

Liu, Yangyang, E-mail: yangyang.liu@colorado.edu; Popović, Miloš A., E-mail: milos.popovic@colorado.edu [Nanophotonic Systems Laboratory, Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309 (United States)

2014-05-19

High-Q ring resonators with contacts to the waveguide core provide a versatile platform for various applications in chip-scale optomechanics, thermo-, and electro-optics. We propose and demonstrate azimuthally periodic contacted ring resonators based on multi-mode Bloch matching that support contacts on both the inner and outer radius edges with small degradation to the optical quality factor (Q). Radiative coupling between degenerate modes of adjacent radial spatial order leads to imaginary frequency (Q) splitting and a scatterer avoiding high-Q “wiggler” supermode field. We experimentally measure Qs up to 258 000 in devices fabricated in a silicon device layer on buried oxide undercladding and up to 139 000 in devices fully suspended in air using an undercut step. Wiggler supermodes are true modes of the microphotonic system that offer additional degrees of freedom in electrical, thermal, and mechanical design.

Beam separation for p-anti p collisions in a single ring in the multibunch mode

International Nuclear Information System (INIS)

Berley, D.; Garren, A.A.; Month, M.

1978-01-01

A discussion is given of proton-antiproton colliding beam operation in storage rings. Some means of separating the beams at points where no experiment is being performed seems to be an important feature for a p-anti p colliding beam ring. By exciting a betatron oscillation in some appropriate, localized region, one could create a specific collision point while at the same time cause the p and anti p beams to oscillate in opposition so that their orbits meet at only a small number of points, roughly given by twice the tune, 2ν

Structural and vibrational study of a neurotransmitter molecule: Dopamine [4-(2-aminoethyl) benzene-1,2-diol].

Science.gov (United States)

Jha, Omkant; Yadav, T K; Yadav, R A

2018-01-15

Structural and vibrational studies for the most stable conformer of dopamine {4-(2-Aminoethyl) benzene-1, 2-diol} have been carried out at the DFT/B3LYP/6-311++G** level using the Gaussian 09 software. The IR and Raman spectra have been recorded and analyzed in light of the computed vibrational parameters using the DFT and the PEDs computed with the help of the GAR2PED software. Some of the fundamentals have considerably changed frequencies in going from benzene to dopamine. Except the rocking and wagging modes of the NH 2 group the other four modes are pure group modes. The rocking and wagging modes of the NH 2 group show mixing with the other modes. The two OH stretching vibrations are highly localized modes. The Kekule phenyl ring stretching mode is found to remain almost unchanged. The HOMO-LUMO study suggests the existence of charge transfer within the molecule and the energy gap supports the pharmacological active property of the dopamine molecule. The NBO analysis has been carried out to understand the proper and improper hydrogen bonding. Copyright © 2017. Published by Elsevier B.V.

Enhanced Age Strengthening of Mg-Nd-Zn-Zr Alloy via Pre-Stretching

Directory of Open Access Journals (Sweden)

Erjun Guo

2016-08-01

Full Text Available Pre-stretching was carried out to modify the microstructure of Mg-Nd-Zn-Zr alloy to enhance its age strengthening. The results indicated that more heterogeneous nucleation sites can be provided by the high density of dislocations caused by the plastic pre-stretching deformation, as well as speeding up the growth rate of precipitates. Comparison of microstructure in non-pre-stretched specimens after artificial aging showed that pre-stretched specimens exhibited a higher number density of precipitates. The fine and coarse plate-shaped precipitates were found in the matrix. Due to an increase in the number density of precipitates, the dislocation slipping during the deformation process is effectively hindered, and the matrix is strengthened. The yield strength stabilizes at 4% pre-stretching condition, and then the evolution is stable within the error bars. The 8% pre-stretched specimens can achieve an ultimate tensile strength of 297 MPa. However, further pre-stretching strains after 8% cannot supply any increase in strength. Tensile fracture surfaces of specimens subjected to pre-stretching strain mainly exhibit a trans-granular cleavage fracture. This work indicated that a small amount of pre-stretching strain can further increase strength of alloy and also effectively enhance the formation of precipitates, which can expand the application fields of this alloy.

Duration Dependent Effect of Static Stretching on Quadriceps and Hamstring Muscle Force

Directory of Open Access Journals (Sweden)

Leyla Alizadeh Ebadi

2018-03-01

Full Text Available The aim of this study was to determine the acute effect of static stretching on hamstring and quadriceps muscles’ isokinetic strength when applied for various durations to elite athletes, to investigate the effect of different static stretching durations on isokinetic strength, and finally to determine the optimal stretching duration. Fifteen elite male athletes from two different sport branches (10 football and five basketball participated in this study. Experimental protocol was designed as 17 repetitive static stretching exercises for hamstring and quadriceps muscle groups according to the indicated experimental protocols; ((A 5 min jogging; (B 5 min jogging followed by 15 s static stretching; (C 5 min jogging followed by 30 s static stretching; (D 5 min jogging, followed by static stretching for 45 s. Immediately after each protocol, an isokinetic strength test consisting of five repetitions at 60°/s speed and 20 repetitions at 180°/s speed was recorded for the right leg by the Isomed 2000 device. Friedman variance analysis test was employed for data analysis. According to the analyzes, it was observed that 5 min jogging and 15 s stretching exercises increased the isokinetic strength, whereas 30 and 45 s stretching exercises caused a decrease.

The influence of foot position on stretching of the plantar fascia.

Science.gov (United States)

Flanigan, Ryan M; Nawoczenski, Deborah A; Chen, Linlin; Wu, Hulin; DiGiovanni, Benedict F

2007-07-01

A recent study found nonweightbearing stretching exercises specific to the plantar fascia to be superior to the standard program of weightbearing Achilles tendon-stretching exercises in patients with chronic plantar fasciitis. The present study used a cadaver model to demonstrate the influence of foot and ankle position on stretching of the plantar fascia. Twelve fresh-frozen lower-leg specimens were tested in 15 different configurations representing various combinations of ankle and metatarsophalangeal (MTP) joint dorsiflexion, midtarsal transverse plane abduction and adduction, and forefoot varus and valgus. Measurements were recorded by a differential variable reluctance transducer (DVRT) implanted into the medial band of the plantar fascia, and primary measurement was a percent deformation of the plantar fascia (stretch) with respect to a reference position (90 degrees ankle dorsiflexion, 0 degrees midtarsal and forefoot orientation, and 0 degrees MTP dorsiflexion). Ankle and MTP joint dorsiflexion produced a significant increase (14.91%) in stretch compared to the position of either ankle dorsiflexion alone (9.31% increase, p plantar fascia tissue-specific stretching exercises and lends support to the use of ankle and MTP joint dorsiflexion when employing stretching protocols for nonoperative treatment in patients with chronic proximal plantar fasciitis.

High duty factor structures for e+e- storage rings

International Nuclear Information System (INIS)

Allen, M.A.; Karvonen, L.G.

1976-01-01

The next generation e + e - storage rings will need rf systems similar to those required for a continuous-duty linac of over 50 MeV. For the PEP Storage Ring at 18 GeV, it is presently planned to provide a peak accelerating voltage of 77 MV in 18 aluminum accelerating structures, each structure consisting of five slot-coupled cells operating in the π mode. Operating experience with the SPEAR five-cell structure is discussed. Power to each structure is provided by a 125-kW high-efficiency four-cavity klystron. No isolation has been used and the resulting interaction between the accelerating structures, klystrons and the stored beams is discussed

Interset stretching does not influence the kinematic profile of consecutive bench-press sets.

Science.gov (United States)

García-López, David; Izquierdo, Mikel; Rodríguez, Sergio; González-Calvo, Gustavo; Sainz, Nuria; Abadía, Olaia; Herrero, Azael J

2010-05-01

This study was undertaken to examine the role of interset stretching on the time course of acceleration portion AP and mean velocity profile during the concentric phase of 2 bench-press sets with a submaximal load (60% of the 1 repetition maximum). Twenty-five college students carried out, in 3 different days, 2 consecutive bench-press sets leading to failure, performing between sets static stretching, ballistic stretching, or no stretching. Acceleration portion and lifting velocity patterns of the concentric phase were not altered during the second set, regardless of the stretching treatment performed. However, when velocity was expressed in absolute terms, static stretching reduced significantly (p velocity during the second set compared to the first one. Therefore, if maintenance of a high absolute velocity over consecutive sets is important for training-related adaptations, static stretching should be avoided or replaced by ballistic stretching.

Numerical and experimental investigation of stretch-flange forming

International Nuclear Information System (INIS)

Cinotti, N.; Shakeri, H.R.; Worswick, M.J.; Truttmann, S.; Finn, M.J.; Jain, M.; Lloyd, D.J.

2000-01-01

Simulations of stretch flange forming operations are undertaken using explicit dynamic finite element calculations incorporating anisotropic yield criteria. Simple circular stretch flanges utilizing a single circular punch to expand the cut-out were considered. Experiments were performed using 101mm diameter tooling on AA 5754 and AA 5182 aluminum alloy sheets, with varying cut-out and gauge size. Metallurgical aspects of the formability of these aluminum alloys and damage mechanisms were studied. Both optical and Scanning Electron Microscopy (SEM) were used to study ductile fracture behaviour in these materials during the forming operation. The limit strains obtained from the circular stretch flange formability experiments are compared to forming limit diagram (FLD) data from hemispherical dome specimens. (author)

Spectroscopic study of the charge-transfer complexes TiCl4/styrene and TiCl4/polystyrene

Science.gov (United States)

Gonçalves, Norberto S.; Noda, Lúcia. K.

2017-10-01

In this work, solutions of TiCl4/styrene and TiCl4/polystyrene charge-transfer complexes in CHCl3 or CDCl3 were investigated by UV-vis, resonance Raman and 1H NMR spectroscopies in order to study their molecular and electronic structures. Both show a yellow colour due to absorption in the 400 nm region, related to a charge-transfer transition. In Raman spectra, as the excitation approaches the resonance region, the primary enhancement of aromatic ring modes was mainly observed, rather than intensification of the vinylic double-bond stretch. Under the experimental conditions it was observed that formation of polystyrene takes place, as showed by 1H NMR spectra, and the most significant interaction occurs at the aromatic ring, as supported by the results from interaction of TiCl4 with polystyrene, as indicated by the charge-transfer band and resonant intensification of the aromatic ring modes.

Design of a quasi-isochronous storage ring for THz light source

International Nuclear Information System (INIS)

Zhu Jiapeng; Xu Hongliang; Feng Guangyao; Lan Jieqin

2012-01-01

A quasi-isochronous storage ring is designed by manipulating lattice parameters to introduce a negative dispersion function to the dispersion section. This quasi-isochronous storage ring is designed for a THz synchrotron radiation source. The simulation of the optics function and beam emittance shows its feasibility, and the tracing result of particles indicates that the designed ring has a good particle dynamic aperture. In addition, a three-dimensional model of the vacuum chamber used for photon radiation in the quasi-isochronous mode is also designed. The eigenmodes of the chamber are simulated, and characteristic parameters such as quality factor, power loss and characteristic impedance are also calculated. The result shows that the vacuum chamber has little effect on the circulating beam. (authors)

Magnetic neutral point stretching and coalescence in tearing-generated magnetohydrodynamic structures

International Nuclear Information System (INIS)

Malara, F.; Veltri, P.; Carbone, V.

1991-01-01

The time evolution of the instability of a sheet pinch is numerically studied using a sufficiently high ratio of system length to width in order to allow the simultaneous growth of several unstable wavelengths. This numerical simulation provides new insights into the nonlinear development of the tearing instability. Before the instability saturates, the nonlinear interactions among the unstable modes produce local coalescence phenomena that destroy the weaker current pinches and reduce the number of magnetic islands. In contrast with the usual picture, this coalescence is not due to the attraction between the current maxima, but is due to the stretching of the X-neutral points associated with the most intense current pinches. The global perturbation growth rate remains essentially unchanged in time, being of the order of the resistive instability growth rate

Stretch activates myosin light chain kinase in arterial smooth muscle

International Nuclear Information System (INIS)

Barany, K.; Rokolya, A.; Barany, M.

1990-01-01

Stretching of porcine carotid arterial muscle increased the phosphorylation of the 20 kDa myosin light chain from 0.23 to 0.68 mol [32P]phosphate/mol light chain, whereas stretching of phorbol dibutyrate treated muscle increased the phosphorylation from 0.30 to 0.91 mol/mol. Two-dimensional gel electrophoresis followed by two-dimensional tryptic phosphopeptide mapping was used to identify the enzyme involved in the stretch-induced phosphorylation. Quantitation of the [32P]phosphate content of the peptides revealed considerable light chain phosphorylation by protein kinase C only in the phorbol dibutyrate treated arterial muscle, whereas most of the light chain phosphorylation was attributable to myosin light chain kinase. Upon stretch of either the untreated or treated muscle, the total increment in [32P]phosphate incorporation into the light chain could be accounted for by peptides characteristic for myosin light chain kinase catalyzed phosphorylation, demonstrating that the stretch-induced phosphorylation is caused by this enzyme exclusively

On Sagnac frequency splitting in a solid-state ring Raman laser.

Science.gov (United States)

Liang, Wei; Savchenkov, Anatoliy; Ilchenko, Vladimir; Griffith, Robert; De Cuir, Edwin; Kim, Steven; Matsko, Andrey; Maleki, Lute

2017-11-15

We report on an accurate measurement of the frequency splitting of an optical rotating ring microcavity made out of calcium fluoride. By measuring the frequencies of the clockwise and counter-clockwise coherent Raman emissions confined in the cavity modes, we show that the frequency splitting is inversely proportional to the refractive index of the cavity host material. The measurement has an accuracy of 1% and unambiguously confirms the classical theoretical prediction based on special theory of relativity. This Letter also demonstrates the usefulness of the ring Raman microlaser for rotation measurements.

Torsional mode ultrasonic helical waveguide sensor for re-configurable temperature measurement

Directory of Open Access Journals (Sweden)

Suresh Periyannan

2016-06-01

Full Text Available This paper introduces an ultrasonic torsional mode based technique, configured in the form of a helical “spring-like” waveguide, for multi-level temperature measurement. The multiple sensing levels can be repositioned by stretching or collapsing the spring to provide simultaneous measurements at different desired spacing in a given area/volume. The transduction is performed using piezo-electric crystals that generate and receive T(0,1 mode in a pulse echo mode. The gage lengths and positions of measurements are based on machining multiple reflector notches in the waveguide at required positions. The time of fight (TOF measurements between the reflected signals from the notches provide local temperatures that compare well with co-located thermocouples.

Convective Heat Transfer Scaling of Ignition Delay and Burning Rate with Heat Flux and Stretch Rate in the Equivalent Low Stretch Apparatus

Science.gov (United States)

Olson, Sandra

2011-01-01

To better evaluate the buoyant contributions to the convective cooling (or heating) inherent in normal-gravity material flammability test methods, we derive a convective heat transfer correlation that can be used to account for the forced convective stretch effects on the net radiant heat flux for both ignition delay time and burning rate. The Equivalent Low Stretch Apparatus (ELSA) uses an inverted cone heater to minimize buoyant effects while at the same time providing a forced stagnation flow on the sample, which ignites and burns as a ceiling fire. Ignition delay and burning rate data is correlated with incident heat flux and convective heat transfer and compared to results from other test methods and fuel geometries using similarity to determine the equivalent stretch rates and thus convective cooling (or heating) rates for those geometries. With this correlation methodology, buoyant effects inherent in normal gravity material flammability test methods can be estimated, to better apply the test results to low stretch environments relevant to spacecraft material selection.

Stretch-sensitive paresis and effort perception in hemiparesis.

Science.gov (United States)

Vinti, Maria; Bayle, Nicolas; Hutin, Emilie; Burke, David; Gracies, Jean-Michel

2015-08-01

In spastic paresis, stretch applied to the antagonist increases its inappropriate recruitment during agonist command (spastic co-contraction). It is unknown whether antagonist stretch: (1) also affects agonist recruitment; (2) alters effort perception. We quantified voluntary activation of ankle dorsiflexors, effort perception, and plantar flexor co-contraction during graded dorsiflexion efforts at two gastrocnemius lengths. Eighteen healthy (age 41 ± 13) and 18 hemiparetic (age 54 ± 12) subjects performed light, medium and maximal isometric dorsiflexion efforts with the knee flexed or extended. We determined dorsiflexor torque, Root Mean Square EMG and Agonist Recruitment/Co-contraction Indices (ARI/CCI) from the 500 ms peak voluntary agonist recruitment in a 5-s maximal isometric effort in tibialis anterior, soleus and medial gastrocnemius. Subjects retrospectively reported effort perception on a 10-point visual analog scale. During gastrocnemius stretch in hemiparetic subjects, we observed: (1) a 25 ± 7 % reduction of tibialis anterior voluntary activation (maximum reduction 98 %; knee extended vs knee flexed; p = 0.007, ANOVA); (2) an increase in dorsiflexion effort perception (p = 0.03, ANCOVA). Such changes did not occur in healthy subjects. Effort perception depended on tibialis anterior recruitment only (βARI(TA) = 0.61, p hemiparesis, voluntary ability to recruit agonist motoneurones is impaired--sometimes abolished--by antagonist stretch, a phenomenon defined here as stretch-sensitive paresis. In addition, spastic co-contraction increases effort perception, an additional incentive to evaluate and treat this phenomenon.

The multimodal magnetoelectric effect in the ring-shaped magnetostrictive-piezoelectric bulk composites

Science.gov (United States)

Radchenko, G. S.; Filippov, D. A.; Laletin, V. M.

2015-11-01

The theoretical and experimental investigation of the direct magnetoelectric effect in the ring-type structures made of the bulk magnetostrictive-piezoelectric composites has been presented. The analytical expression for the magnetoelectric voltage coefficient has been obtained using the effective parameters method. The frequency dependence of this parameter is also analyzed. The dependence of the resonant frequency and the amplitude of this effect of the geometrical parameters of the ring for the first and second oscillation modes are presented. The experimental investigation of the direct magnetoelectric effect for the ring-type composite specimens consisting of the nickel ferrite spinel-PZT bulk composite is done. The obtained experimental data are in good agreement with the theoretical predictions.

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.

Effect of spinal manipulative therapy with stretching compared with stretching alone on full-swing performance of golf players: a randomized pilot trial☆

Science.gov (United States)

Costa, Soraya M.V.; Chibana, Yumi E.T.; Giavarotti, Leandro; Compagnoni, Débora S.; Shiono, Adriana H.; Satie, Janice; Bracher, Eduardo S.B.

2009-01-01

Abstract Objective There has been a steady growth of chiropractic treatment using spinal manipulative therapy (SMT) that aims to increase the performance of athletes in various sports. This study evaluates the effect of SMT by chiropractors on the performance of golf players. Methods Golfers of 2 golf clubs in São Paulo, Brazil, participated in this study. They were randomized to 1 of 2 groups: Group I received a stretch program, and group II received a stretch program in addition to SMT. Participants in both groups performed the same standardized stretching program. Spinal manipulative therapy to dysfunctional spinal segments was performed on group II only. All golfers performed 3 full-swing maneuvers. Ball range was considered as the average distance for the 3 shots. Treatment was performed after the initial measurement, and the same maneuvers were performed afterward. Each participant repeated these procedures for a 4-week period. Student t test, Mann-Whitney nonparametric test, and 1-way analysis of variance for repeated measures with significance level of 5% were used to analyze the study. Results Forty-three golfers completed the protocol. Twenty participants were allocated to group I and 23 to group II. Average age, handicap, and initial swing were comparable. No improvement of full-swing performance was observed during the 4 sessions on group I (stretch only). An improvement was observed at the fourth session of group II (P = .005); when comparing the posttreatment, group II had statistical significance at all phases (P = .003). Conclusions Chiropractic SMT in association with muscle stretching may be associated with an improvement of full-swing performance when compared with muscle stretching alone. PMID:19948307

Ca2+ influx and ATP release mediated by mechanical stretch in human lung fibroblasts

International Nuclear Information System (INIS)

Murata, Naohiko; Ito, Satoru; Furuya, Kishio; Takahara, Norihiro; Naruse, Keiji; Aso, Hiromichi; Kondo, Masashi; Sokabe, Masahiro; Hasegawa, Yoshinori

2014-01-01

Highlights: • Uniaxial stretching activates Ca 2+ signaling in human lung fibroblasts. • Stretch-induced intracellular Ca 2+ elevation is mainly via Ca 2+ influx. • Mechanical strain enhances ATP release from fibroblasts. • Stretch-induced Ca 2+ influx is not mediated by released ATP or actin cytoskeleton. - Abstract: One cause of progressive pulmonary fibrosis is dysregulated wound healing after lung inflammation or damage in patients with idiopathic pulmonary fibrosis and severe acute respiratory distress syndrome. The mechanical forces are considered to regulate pulmonary fibrosis via activation of lung fibroblasts. In this study, the effects of mechanical stretch on the intracellular Ca 2+ concentration ([Ca 2+ ] i ) and ATP release were investigated in primary human lung fibroblasts. Uniaxial stretch (10–30% in strain) was applied to fibroblasts cultured in a silicone chamber coated with type I collagen using a stretching apparatus. Following stretching and subsequent unloading, [Ca 2+ ] i transiently increased in a strain-dependent manner. Hypotonic stress, which causes plasma membrane stretching, also transiently increased the [Ca 2+ ] i . The stretch-induced [Ca 2+ ] i elevation was attenuated in Ca 2+ -free solution. In contrast, the increase of [Ca 2+ ] i by a 20% stretch was not inhibited by the inhibitor of stretch-activated channels GsMTx-4, Gd 3+ , ruthenium red, or cytochalasin D. Cyclic stretching induced significant ATP releases from fibroblasts. However, the stretch-induced [Ca 2+ ] i elevation was not inhibited by ATP diphosphohydrolase apyrase or a purinergic receptor antagonist suramin. Taken together, mechanical stretch induces Ca 2+ influx independently of conventional stretch-sensitive ion channels, the actin cytoskeleton, and released ATP

Investigating the role of musical genre in human perception of music stretching resistance

OpenAIRE

Chen, Jun; Wang, Chaokun

2017-01-01

To stretch a music piece to a given length is a common demand in people's daily lives, e.g., in audio-video synchronization and animation production. However, it is not always guaranteed that the stretched music piece is acceptable for general audience since music stretching suffers from people's perceptual artefacts. Over-stretching a music piece will make it uncomfortable for human psychoacoustic hearing. The research on music stretching resistance attempts to estimate the maximum stretchab...

Equibiaxial cyclic stretch stimulates fibroblasts to rapidly remodel fibrin.

Science.gov (United States)

Balestrini, Jenna Leigh; Billiar, Kristen Lawrence

2006-01-01

Understanding the effects of the mechanical environment on wound healing is critical for developing more effective treatments to reduce scar formation and contracture. The aim of this study was to investigate the effects of dynamic mechanical stretch on cell-mediated early wound remodeling independent of matrix alignment which obscures more subtle remodeling mechanisms. Cyclic equibiaxial stretch (16% stretch at 0.2 Hz) was applied to fibroblast-populated fibrin gel in vitro wound models for eight days. Compaction, density, tensile strength, and collagen content were quantified as functional measures of remodeling. Stretched samples were approximately ten times stronger, eight-fold more dense, and eight times thinner than statically cultured samples. These changes were accompanied by a 15% increase in net collagen but no significant differences in cell number or viability. When collagen crosslinking was inhibited in stretched samples, the extensibility increased and the strength decreased. The apparent weakening was due to a reduction in compaction rather than a decrease in ability of the tissue to withstand tensile forces. Interestingly, inhibiting collagen crosslinking had no measurable effects on the statically cultured samples. These results indicate that amplified cell-mediated compaction and even a slight addition in collagen content play substantial roles in mechanically induced wound strengthening. These findings increase our understanding of how mechanical forces guide the healing response in skin, and the methods employed in this study may also prove valuable tools for investigating stretch-induced remodeling of other planar connective tissues and for creating mechanically robust engineered tissues.

Beam loading effects for two-beam ring

International Nuclear Information System (INIS)

Wang Lanfa; Lin Yuzheng; Tong Dechun

1999-01-01

An analytic treatment of multi-bunch potential well distortion for a two-beam storage ring is presented. The longitudinal wake effects are separated into: the mode loss, the synchrotron tune shift (both due to potential well distortion) and the coherent multi-bunch coupling. Here, only the first two effects are studied. Resulting simple analytic formulas describe the mode loss and the synchrotron tune shift experienced by a given bunch within the two-beam, as a function of the high order mode's parameters. One can get immediately a simple quantitative answer in term of the mode loss and the synchrotron tune shift experienced by each bunch from these formulas, so the authors can know how to modify the existing configuration of parasitic cavity resonance (via frequency tuning) so that the resulting potential well distortion effects are minimized. When the RF cavities are symmetrically distributed about the interaction points, the two beams will have same beam loading effects, so the authors can compensate the phase shift of the two beam using the same method as in one beam case

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

The Influence of Dosing Modes of Coagulate on Arsenic Removal

Directory of Open Access Journals (Sweden)

Zhibin Zhang

2014-01-01

Full Text Available Three different dosing modes, including one single dosing mode and two sequential dosing modes, were applied in high-arsenic contaminated water treatment. The results illustrated that the As (V soluble and the As (V nonspecifically sorbed were the insignificant species from Fe-As (V samples in the sequential dosing mode, while they were higher in the single dosing mode. However, it could be further concluded that the mobility of the Fe-As (V in sequential dosing mode was greater than that in single dosing mode. Besides, the main arsenic speciation governing the arsenic-borne coagulates was the As (V associated with poorly crystalline hydrous oxides of Fe in sequential or single dosing mode. Moreover, the particle size distribution analysis indicated that the sequential dosing mode was more prevalent in neutralizing and adsorbing the As (V compared with the single dosing mode. In the FT-IR spectra, the presence of arsenic was highlighted by a well resolved band at 825–829 cm−1. The positions of the As–O stretching vibration bands were shifted gradually as the dosing mode changed from the single to the sequential. This result could be related to the distribution of arsenic speciation in different dosing modes.

Double Ring Antenna Design for MIMO Application in Mobile Terminals

DEFF Research Database (Denmark)

Zhao, Kun; Zhang, Shuai; Ying, Zhinong

2015-01-01

In this paper, We present a MIMO bezel antenna design composed by a seamless double metal ring structure. The MIMO antenna mainly operates in the loop mode and can cover the majority of globe cellular bands. Good efficiencies (>-4dB) and a low envelope correlation coefficient (<0.5) are achieved,...

Lewis lung carcinoma regulation of mechanical stretch-induced protein synthesis in cultured myotubes.

Science.gov (United States)

Gao, Song; Carson, James A

2016-01-01

Mechanical stretch can activate muscle and myotube protein synthesis through mammalian target of rapamycin complex 1 (mTORC1) signaling. While it has been established that tumor-derived cachectic factors can induce myotube wasting, the effect of this catabolic environment on myotube mechanical signaling has not been determined. We investigated whether media containing cachectic factors derived from Lewis lung carcinoma (LLC) can regulate the stretch induction of myotube protein synthesis. C2C12 myotubes preincubated in control or LLC-derived media were chronically stretched. Protein synthesis regulation by anabolic and catabolic signaling was then examined. In the control condition, stretch increased mTORC1 activity and protein synthesis. The LLC treatment decreased basal mTORC1 activity and protein synthesis and attenuated the stretch induction of protein synthesis. LLC media increased STAT3 and AMP-activated protein kinase phosphorylation in myotubes, independent of stretch. Both stretch and LLC independently increased ERK1/2, p38, and NF-κB phosphorylation. In LLC-treated myotubes, the inhibition of ERK1/2 and p38 rescued the stretch induction of protein synthesis. Interestingly, either leukemia inhibitory factor or glycoprotein 130 antibody administration caused further inhibition of mTORC1 signaling and protein synthesis in stretched myotubes. AMP-activated protein kinase inhibition increased basal mTORC1 signaling activity and protein synthesis in LLC-treated myotubes, but did not restore the stretch induction of protein synthesis. These results demonstrate that LLC-derived cachectic factors can dissociate stretch-induced signaling from protein synthesis through ERK1/2 and p38 signaling, and that glycoprotein 130 signaling is associated with the basal stretch response in myotubes. Copyright © 2016 the American Physiological Society.

Quadrupole modes in linearized beam-beam interaction in e+e- colliding rings

International Nuclear Information System (INIS)

Matsumoto, Shuji; Hirata, Kohji.

1992-01-01

The dynamic-beta model is extended, incorporating the synchrotron radiation effects. The model yields dynamic-emittance effect. The steady-state envelope matrix is explicitly obtained. Both equal-beam and flip-flop solutions are found. The stability of the steady-state solutions are investigated by numerical calculations. The model illustrates some characteristic features of the beam-beam interaction at e + e - colliding rings in spite of containing some qualitatively unrealistic points. (author)

Effects of special composite stretching on the swing of amateur golf players.

Science.gov (United States)

Lee, Joong-Chul; Lee, Sung-Wan; Yeo, Yun-Ghi; Park, Gi Duck

2015-04-01

[Purpose] The study investigated stretching for safer a golf swing compared to present stretching methods for proper swings in order to examine the effects of stretching exercises on golf swings. [Subjects] The subjects were 20 amateur golf club members who were divided into two groups: an experimental group which performed stretching, and a control group which did not. The subjects had no bone deformity, muscle weakness, muscle soreness, or neurological problems. [Methods] A swing analyzer and a ROM measuring instrument were used as the measuring tools. The swing analyzer was a GS400-golf hit ball analyzer (Korea) and the ROM measuring instrument was a goniometer (Korea). [Results] The experimental group showed a statistically significant improvement in driving distance. After the special stretching training for golf, a statistically significant difference in hit-ball direction deviation after swings were found between the groups. The experimental group showed statistically significant decreases in hit ball direction deviation. After the special stretching training for golf, statistically significant differences in hit-ball speed were found between the groups. The experimental group showed significant increases in hit-ball speed. [Conclusion] To examine the effects of a special stretching program for golf on golf swing-related factors, 20 male amateur golf club members performed a 12-week stretching training program. After the golf stretching training, statistically significant differences were found between the groups in hit-ball driving distance, direction deviation, deflection distance, and speed.

Stretching and folding mechanism in foams

International Nuclear Information System (INIS)

Tufaile, Alberto; Pedrosa Biscaia Tufaile, Adriana

2008-01-01

We have described the stretching and folding of foams in a vertical Hele-Shaw cell containing air and a surfactant solution, from a sequence of upside-down flips. Besides the fractal dimension of the foam, we have observed the logistic growth for the soap film length. The stretching and folding mechanism is present during the foam formation, and this mechanism is observed even after the foam has reached its respective maximum fractal dimension. Observing the motion of bubbles inside the foam, large bubbles present power spectrum associated with random walk motion in both directions, while the small bubbles are scattered like balls in a Galton board

Stretching and folding mechanism in foams

Energy Technology Data Exchange (ETDEWEB)

Tufaile, Alberto [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)], E-mail: tufaile@usp.br; Pedrosa Biscaia Tufaile, Adriana [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)

2008-10-13

We have described the stretching and folding of foams in a vertical Hele-Shaw cell containing air and a surfactant solution, from a sequence of upside-down flips. Besides the fractal dimension of the foam, we have observed the logistic growth for the soap film length. The stretching and folding mechanism is present during the foam formation, and this mechanism is observed even after the foam has reached its respective maximum fractal dimension. Observing the motion of bubbles inside the foam, large bubbles present power spectrum associated with random walk motion in both directions, while the small bubbles are scattered like balls in a Galton board.

High resolution infrared and Raman spectra of 13C12CD2: The CD stretching fundamentals and associated combination and hot bands

International Nuclear Information System (INIS)

Di Lonardo, G.; Fusina, L.; Canè, E.; Tamassia, F.; Martínez, R. Z.; Bermejo, D.

2015-01-01

Infrared and Raman spectra of mono 13 C fully deuterated acetylene, 13 C 12 CD 2 , have been recorded and analysed to obtain detailed information on the C—D stretching fundamentals and associated combination, overtone, and hot bands. Infrared spectra were recorded at an instrumental resolution ranging between 0.006 and 0.01 cm −1 in the region 1800–7800 cm −1 . Sixty new bands involving the ν 1 and ν 3 C—D stretching modes also associated with the ν 4 and ν 5 bending vibrations have been observed and analysed. In total, 5881 transitions have been assigned in the investigated spectral region. In addition, the Q branch of the ν 1 fundamental was recorded using inverse Raman spectroscopy, with an instrumental resolution of about 0.003 cm −1 . The transitions relative to each stretching mode, i.e., the fundamental band, its first overtone, and associated hot and combination bands involving bending states with υ 4 + υ 5 up to 2 were fitted simultaneously. The usual Hamiltonian appropriate to a linear molecule, including vibration and rotation l-type and the Darling–Dennison interaction between υ 4 = 2 and υ 5 = 2 levels associated with the stretching states, was adopted for the analysis. The standard deviation for each global fit is ≤0.0004 cm −1 , of the same order of magnitude of the measurement precision. Slightly improved parameters for the bending and the ν 2 manifold have been also determined. Precise values of spectroscopic parameters deperturbed from the resonance interactions have been obtained. They provide quantitative information on the anharmonic character of the potential energy surface, which can be useful, in addition to those reported in the literature, for the determination of a general anharmonic force field for the molecule. Finally, the obtained values of the Darling–Dennison constants can be valuable for understanding energy flows between independent vibrations

Upgraded cavities for the positron accumulator ring of the APS

International Nuclear Information System (INIS)

Kang, Y.W.; Jiang, X.; Mangra, D.

1997-01-01

Upgraded versions of cavities for the APS positron accumulator ring (PAR) have been built and are being tested. Two cavities are in the PAR: a fundamental 9.8-MHz cavity and a twelfth harmonic 117.3-MHz cavity. Both cavities have been manufactured for higher voltage operation with improved Q-factors, reliability, and tuning capability. Both cavities employ current-controlled ferrite tuners for control of the resonant frequency. The harmonic cavity can be operated in either a pulsed mode or a CW mode. The rf properties of the cavities are presented

Fatigue Crack Growth Characteristics of Cold Stretched STS 304 Welded Joint

Energy Technology Data Exchange (ETDEWEB)

Lee, Jeong Won; Na, Seong Hyeon; Yoon, Dong Hyun; Kim, Jae Hoon [Chungnam Nat’l Univ., Daejeon (Korea, Republic of); Kim, Young Kyun; Kim, Ki Dong [Korea Gas Coporation R& D Division, Daejeon (Korea, Republic of)

2017-09-15

STS 304 steel is used as pressure vessel material, and although it exhibits excellent mechanical characteristics at a low temperature, it is heavier than other materials. To address this issue, a method using cold-stretching techniques for STS 304 can be applied. In this study, a cold-stretching part and welded joint specimen were directly obtained from a cold-stretching pressure vessel manufactured according to ASME code. Fatigue crack propagation tests were carried out at room temperature and -170℃ using the compliance method for stress ratios of 0.1 and 0.5. The results indicate that crack growth rate of the welded joint is higher than that of the cold-stretching part within the same stress intensity factor range. The outcome of this work is expected to serve as a basis for the development of a cold-stretched STS 304 pressure vessel.

Diagnostics of the Raman spectral structure of the stretching vibrations of water by means of polarization CARS

International Nuclear Information System (INIS)

Bunkin, A.F.; Maltsev, D.V.; Surskii, K.O.; Shapiro, Y.G.; Chernov, V.G.

1988-01-01

A method is proposed for decomposing into components by computer the partially resolved polarization CARS spectra of the ν OH Raman band of stretching vibrations of liquid water under various experimental conditions. The spectroscopic parameters of the ν OH band of the components at water temperatures of 5 degree C and 20 degree C are given. It is shown that single-mode-continuum models and mixed models of the structure of liquid water (in the 5--60 degree C range) contradict the results of experiments on polarization CARS

Linking structure and vibrational mode coupling using high-resolution infrared spectroscopy: A comparison of gauche and trans 1-chloro-2-fluoroethane

Science.gov (United States)

Miller, C. Cameron; Stone, Stephen C.; Philips, Laura A.

1995-01-01

The high-resolution infrared spectrum of 1-chloro-2-fluoroethane in a molecular beam was collected over the 2975-2994 cm-1 spectral region. The spectral region of 2975-2981 cm-1 contains a symmetric C-H stretching vibrational band of the gauche conformer containing the 35Cl isotope. The spectral region of 2985-2994 cm-1 contains three vibrational bands of the trans conformer. Two of the three bands are assigned as an antisymmetric C-H stretch of each of the two different chlorine isotopes. The third band is assigned as a symmetric C-H stretch of the 35Cl isotope. The gauche conformer of 1-chloro-2-fluoroethane showed doublet patterns similar to those previously observed in 1,2-difluoroethane. The model for 1,2-difluoroethane is further refined in the present work. These refinements suggest that the coupling dark state in 1,2-difluoroethane is composed of 1 quantum C-H bend, 1 quantum C-C stretch, and 12 quanta of torsion. For 1-chloro-2-fluoroethane the dark state could not be identified due to a small data set. The trans conformer of 1-chloro-2-fluoroethane showed no evidence of mode coupling in the three vibrational bands. Including 2-fluoroethanol in this series of molecules, the extent of vibrational mode coupling did not correlate with the density of states available for coupling. Therefore, density of states alone is insufficient to explain the observed trend. A correlation was observed between the degree of intramolecular interaction and vibrational mode coupling.

Beam-based alignment at the KEK-ATF damping ring

International Nuclear Information System (INIS)

Woodley, Mark D.; Nelson, Janice; Ross, Marc; Turner, James; Wolski, A.; Kubo, Kiyoshi

2004-01-01

The damping rings of a future linear collider will have demanding alignment and stability requirements in order to achieve the low vertical emittance necessary for high luminosity. The Accelerator Test Facility (ATF) at KEK has successfully demonstrated the vertical emittance below 5 pm that is specified for the GLC/NLC Main Damping Rings. One contribution to this accomplishment has been the use of Beam Based Alignment (BBA) techniques. The mode of operation of the ATF presents particular challenges for BBA, and we describe here how we have deduced the offsets of the BPMs with respect to the quadrupoles. We also discuss a technique that allows for direct measurements of the beam-to-quad offsets

Ultimate strength analysis of ring-stiffened cylinders subjected to hydrostatic pressure

International Nuclear Information System (INIS)

Park, Chi Mo

1990-01-01

In this study, ultimate strength analysis of ring-stiffened cylinders have been performed, considering the elasto-plastic large deflection. In the elasto-plastic analysis, von Mises yield criteria, the plastic flow theory and the layered approach have been adopted. In order to take into account the follower force effect of the hydrostatic pressure, the incremental load components have been updated at every loading step. As collapse modes, axisymmetric yielding, interframe shell buckling and general buckling are considered, while local buckling of ring-stiffener is not considered. Initial shape imperfection is assumed to be the elastic buckling mode to obtain the lower bound of the ultimate strength. Results of numerical analysis are compared with the experimental results to show the validity of the present approach. It has been drawn that the present numerical results are closely correlated with the experimental results. On the other hand, the effects of initial shape imperfection and condition on the ultimate strength have been investigated. (Author)

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.

Design of a lattice for JAERI storage ring (JSR)

International Nuclear Information System (INIS)

Harada, Shunji; Yokomizo, Hideaki; Yanagida, Kenichi

1990-08-01

The new 8GeV synchrotron radiation facility (SPring-8) is planned to be constructed in Japan, and our institute (JAERI) are involved in this project with RIKEN. A compact electron storage ring JSR has been constructed in JAERI in order to study various kind of accelerator technologies, to test some devices such as the insertion devices and the beam monitors, and to train young researchers. The ring size is limited by the available space of a linac building, so that the circumference of JSR becomes 20.546 m. However, even in this small ring, one straight section with the length of ∼1.5 m, where the dispersion is free, is provided for the insertion device study. JSR takes Chasman-Green lattice with a superperiodicity of three. JSR is possible not only to suppress the dispersion but also to leave it on the long straight section. An electron beam from a linac is accepted into JSR in any operating modes. (author)

The theoretical and numerical models of the novel and fast tunable semiconductor ring laser

Science.gov (United States)

Zhu, Jiangbo; Zhang, Junwen; Chi, Nan; Yu, Siyuan

2011-01-01

Fast wavelength-tunable semiconductor lasers will be the key components in future optical packet switching networks. Especially, they are of great importance in the optical network nodes: transmitters, optical wavelength-routers, etc. In this paper, a new scheme of a next-generation fast tunable ring laser was given. Tunable lasers in this design have better wavelength tunability compared with others, for they are switched faster in wavelength and simpler to control with the injecting light from an external distributed Bragg-reflector(DBR). Then some discussion of the waveguide material system and coupler design of the ring laser were given. And we also derived the multimode rate equations corresponding to this scheme by analyzing some characteristics of the semiconductor ring cavity, directionality, nonlinear mode competition, optical injection locking, etc. We did MatLab simulation based on the new rate equations to research the process of mode competition and wavelength switching in the laser, and achieved the basic functions of a tunable laser. Finally some discussion of the impact of several key parameters was given.

Pulsed rf systems for large storage rings

International Nuclear Information System (INIS)

Wilson, P.B.

1979-03-01

The possibility is considered that by using a pulsed rf system a substantial reduction can be made in the rf power requirement for the next generation of large storage rings. For a ring with a sufficiently large circumference, the time between bunch passages, T/sub b/, can exceed the cavity filling time, T/sub f/. As the ratio T/sub b//T/sub f/ increases, it is clear that at some point the average power requirement can be reduced by pulsing the rf to the cavities. In this mode of operation, the rf power is turned on a filling time or so before the arrival of a bunch and is switched off again at the time of bunch passage. There is no rf energy in the accelerating structure, and hence no power dissipation, for most of the period between bunches

Fast-extraction modulators for Los Alamos Scientific LaboratorY Proton Storage Ring

International Nuclear Information System (INIS)

Nunnally, W.C.; Hudgings, D.W.; Sarjeant, W.J.

1980-01-01

The development of a short-bunch mode fast-extraction modulator for the LASL proton storage ring has made necessary the design and development of a resonant transformer charging circuit and the design of a new FIB line circuit to provide bipolar pulse outputs with low prepulse, postpulse, and an optimum high-voltage switch environments. The systems are now being developed to operate reliably at the high-average powers required. The short-bunch mode fast-extraction modulator prototype is presently operating. The initial construction of the long-bunch mode fast-extraction modulator prototype is under way, with results expected within the year

Strain and temperature characteristics of the LP11 mode based on a few-mode fiber Bragg grating and core-offset splicing

Science.gov (United States)

Jin, Wenxing; Xu, Yao; Jiang, Youchao; Wu, Yue; Yao, Shuzhi; Xiao, Shiying; Qi, Yanhui; Ren, Wenhua; Jian, Shuisheng

2018-02-01

We propose and demonstrate a ring fiber laser based on a few-mode fiber Bragg grating for strain and temperature sensing using only the LP11 mode. The core-offset splicing method is used to ensure effective coupling from the fundamental mode to the LP11 mode. A stable erbium-doped fiber laser operating as a single LP11 mode with a 3 dB linewidth of about 0.02 nm and an optical signal-to-noise ratio over 42 dB is achieved by appropriately adjusting the polarization controller between the optical circulator and the few-mode fiber Bragg grating. A high axial strain sensitivity of 0.8778 pm μ\\varepsilon-1 and a temperature sensitivity of 9.9214 pm °C-1 are achieved with the advantages of all-fiber, simple construction and easy control.

The effectiveness of manual stretching in the treatment of plantar heel pain: a systematic review

Directory of Open Access Journals (Sweden)

Parish Ben

2011-06-01

Full Text Available Abstract Background Plantar heel pain is a commonly occurring foot complaint. Stretching is frequently utilised as a treatment, yet a systematic review focusing only on its effectiveness has not been published. This review aimed to assess the effectiveness of stretching on pain and function in people with plantar heel pain. Methods Medline, EMBASE, CINAHL, AMED, and The Cochrane Library were searched from inception to July 2010. Studies fulfilling the inclusion criteria were independently assessed, and their quality evaluated using the modified PEDro scale. Results Six studies including 365 symptomatic participants were included. Two compared stretching with a control, one study compared stretching to an alternative intervention, one study compared stretching to both alternative and control interventions, and two compared different stretching techniques and durations. Quality rating on the modified Pedro scale varied from two to eight out of a maximum of ten points. The methodologies and interventions varied significantly between studies, making meta-analysis inappropriate. Most participants improved over the course of the studies, but when stretching was compared to alternative or control interventions, the changes only reached statistical significance in one study that used a combination of calf muscle stretches and plantar fascia stretches in their stretching programme. Another study comparing different stretching techniques, showed a statistically significant reduction in some aspects of pain in favour of plantar fascia stretching over calf stretches in the short term. Conclusions There were too few studies to assess whether stretching is effective compared to control or other interventions, for either pain or function. However, there is some evidence that plantar fascia stretching may be more effective than Achilles tendon stretching alone in the short-term. Appropriately powered randomised controlled trials, utilizing validated outcome

Beam position monitor system for storage rings

International Nuclear Information System (INIS)

Nakamura, M.; Hinkson, J.A.

1985-05-01

Beam position monitors (BPM) for synchrotron light storage rings usually consist of beam pickup electrodes, coaxial relays and a narrowband receiver. While accurate, these systems are slow and of limited use in the commissioning of an accelerator. A beam position monitor is described which is intended to be a principal diagnostic during debug and routine running of a storage ring. It is capable of measuring the position of a single bunch on the first or nth orbit to an accuracy of a few percent. Stored beam position is more accurately measured with averaging techniques. Beam position changes can be studied in a bandwidth from DC to a few MHz. The beam monitor electronics consist of a separate amplification, detection, and sampling channel for each beam pickup electrode. Fast switches in each channel permit selection of the nth turn for measurement (single bunch mode). A calibration pulse is injected into each channel after beam measurement to permit gain offsets to be measured and removed from the final data. While initially more costly than the usual beam position monitor system, this sytem will pay for itself in reduced storage ring debug and trouble shooting time. 5 refs., 5 figs

Weak depth and along-strike variations in stretching from a multi-episodic finite stretching model: Evidence for uniform pure-shear extension in the opening of the South China Sea

Science.gov (United States)

Chen, Lin; Zhang, Zhongjie; Song, Haibin

2013-12-01

The South China Sea is widely believed to have been opened by seafloor spreading during the Cenozoic. The details of its lithospheric extension are still being debated, and it is unknown whether pure, simple, or conjunct shears are responsible for the opening of the South China Sea. The depth-dependent and along-strike extension derived from the single-stage finite stretching model or instantaneous stretching model is inconsistent with the observation that the South China Sea proto-margins have experienced multi-episodic extension since the Late Cretaceous. Based on the multi-episodic finite stretching model, we present the amount of lithosphere stretching at the northern continental margin of the South China Sea for different depth scales (upper crust, whole crust and lithosphere) and along several transects. The stretching factors are estimated by integrating seven deep-penetration seismic profiles, the Moho distribution derived from gravity modeling, and the tectonic subsidence data for 41 wells. The results demonstrate that the amount of stretching increases rapidly from 1.1 at the continent shelf to over 3.5 at the lower slope, but the stretching factors at the crust and lithosphere scales are consistent within error (from the uncertainty in paleobathymetry and sea-level change). Furthermore, the along-strike variation in stretching factor is within the range of 1.11-1.9 in west-east direction, accompanied by significant west-east differences in the thickness of high-velocity layers (HVLs) within the lowermost crust. This weak along-strike variation of the stretching factor is most likely produced by the preexisting contrasts in the composition and thermal structure of the lithosphere. The above observations suggest that the continental extension in the opening of the South China Sea mainly takes the form of a uniform pure shear rather than depth-dependent stretching.

All-passive pixel super-resolution of time-stretch imaging

Science.gov (United States)

Chan, Antony C. S.; Ng, Ho-Cheung; Bogaraju, Sharat C. V.; So, Hayden K. H.; Lam, Edmund Y.; Tsia, Kevin K.

2017-03-01

Based on image encoding in a serial-temporal format, optical time-stretch imaging entails a stringent requirement of state-of-the-art fast data acquisition unit in order to preserve high image resolution at an ultrahigh frame rate — hampering the widespread utilities of such technology. Here, we propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch imaging that preserves pixel resolution at a relaxed sampling rate. It harnesses the subpixel shifts between image frames inherently introduced by asynchronous digital sampling of the continuous time-stretch imaging process. Precise pixel registration is thus accomplished without any active opto-mechanical subpixel-shift control or other additional hardware. Here, we present the experimental pixel-SR image reconstruction pipeline that restores high-resolution time-stretch images of microparticles and biological cells (phytoplankton) at a relaxed sampling rate (≈2-5 GSa/s)—more than four times lower than the originally required readout rate (20 GSa/s) — is thus effective for high-throughput label-free, morphology-based cellular classification down to single-cell precision. Upon integration with the high-throughput image processing technology, this pixel-SR time-stretch imaging technique represents a cost-effective and practical solution for large scale cell-based phenotypic screening in biomedical diagnosis and machine vision for quality control in manufacturing.

The Electromechanical Behavior of a Micro-Ring Driven by Traveling Electrostatic Force

Science.gov (United States)

Ye, Xiuqian; Chen, Yibao; Chen, Da-Chih; Huang, Kuo-Yi; Hu, Yuh-Chung

2012-01-01

There is no literature mentioning the electromechanical behavior of micro structures driven by traveling electrostatic forces. This article is thus the first to present the dynamics and stabilities of a micro-ring subjected to a traveling electrostatic force. The traveling electrostatic force may be induced by sequentially actuated electrodes which are arranged around the flexible micro-ring. The analysis is based on a linearized distributed model considering the electromechanical coupling effects between electrostatic force and structure. The micro-ring will resonate when the traveling speeds of the electrostatic force approach some critical speeds. The critical speeds are equal to the ratio of the natural frequencies to the wave number of the correlative natural mode of the ring. Apart from resonance, the ring may be unstable at some unstable traveling speeds. The unstable regions appear not only near the critical speeds, but also near some fractions of some critical speeds differences. Furthermore the unstable regions expand with increasing driving voltage. This article may lead to a new research branch on electrostatic-driven micro devices. PMID:22438705

Stretching the Border

DEFF Research Database (Denmark)

Horstmann, Alexander

2014-01-01

In this paper, I hope to add a complementary perspective to James Scott’s recent work on avoidance strategies of subaltern mountain people by focusing on what I call the refugee public. The educated Karen elite uses the space of exile in the Thai borderland to reconstitute resources and to re-ent......-based organizations succeed to stretch the border by establishing a firm presence that is supported by the international humanitarian economy in the refugee camps in Northwestern Thailand....

Modeling and Simulation of Longitudinal Dynamics for Low Energy Ring-High Energy Ring at the Positron-Electron Project

International Nuclear Information System (INIS)

Rivetta, Claudio; Mastorides, T.; Fox, J.D.; Teytelman, D.; Van Winkle, D.

2007-01-01

A time domain dynamic modeling and simulation tool for beam-cavity interactions in the Low Energy Ring (LER) and High Energy Ring (HER) at the Positron-Electron Project (PEP-II) is presented. Dynamic simulation results for PEP-II are compared to measurements of the actual machine. The motivation for this tool is to explore the stability margins and performance limits of PEP-II radio-frequency (RF) systems at future higher currents and upgraded RF configurations. It also serves as a test bed for new control algorithms and can define the ultimate limits of the low-level RF (LLRF) architecture. The time domain program captures the dynamic behavior of the beam-cavity-LLRF interaction based on a reduced model. The ring current is represented by macrobunches. Multiple RF stations in the ring are represented via one or two macrocavities. Each macrocavity captures the overall behavior of all the 2 or 4 cavity RF stations. Station models include nonlinear elements in the klystron and signal processing. This enables modeling the principal longitudinal impedance control loops interacting via the longitudinal beam model. The dynamics of the simulation model are validated by comparing the measured growth rates for the LER with simulation results. The simulated behavior of the LER at increased operation currents is presented via low-mode instability growth rates. Different control strategies are compared and the effects of both the imperfections in the LLRF signal processing and the nonlinear drivers and klystrons are explored

A Novel Non-Planar Transverse Stretching Process for Micro-Porous PTFE Membranes and Resulting Characteristics

KAUST Repository

Chang, Y.-H.

2018-02-26

Polytetrafluoroethylene (PTFE) micro-porous membranes were prepared from PTFE fine powder through extruding, rolling, and uniaxial longitudinally stretching. In contrast to conventional planar transverse stretching, a novel 3D mold design of non-planar transverse stretching process was employed in this study to produce micro-porous structure. The morphology, membrane thickness, mean pore size, and porosity of the PTFE membrane were investigated. The results show that the non-planar transverse stretched membranes exhibit more uniform average pore diameter with thinner membrane thickness. Morphological changes induced by planar and non-planar transverse stretching for pore characteristics were investigated. The stretching conditions, stretching temperature and rate, affect the stretched membrane. Increasing temperature facilitated the uniformity of pore size and uniformity of membrane thickness. Moreover, increase in stretching rate resulted in finer pore size and thinner membrane.

Note on beam--beam tune shift in single ring multi bunch mode

International Nuclear Information System (INIS)

Month, M.

1978-01-01

If many identical counter-rotating bunches of protons and antiprotons are stored in a single ring, they will have identical orbits. The question is: Is this total tune shift relevant to the problem of beam stability. The answer is: not in general. The nonlinear force is described by its ''strength'', Δν/sub I/, for each bunch interaction individually. It is not at all clear that the sum of the individual Δν/sub I/ is the significant quantity

How to remove the spurious resonances from ring polymer molecular dynamics

Energy Technology Data Exchange (ETDEWEB)

Rossi, Mariana; Manolopoulos, David E. [Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ (United Kingdom); Ceriotti, Michele [Laboratory of Computational Science and Modeling, IMX, École Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland)

2014-06-21

Two of the most successful methods that are presently available for simulating the quantum dynamics of condensed phase systems are centroid molecular dynamics (CMD) and ring polymer molecular dynamics (RPMD). Despite their conceptual differences, practical implementations of these methods differ in just two respects: the choice of the Parrinello-Rahman mass matrix and whether or not a thermostat is applied to the internal modes of the ring polymer during the dynamics. Here, we explore a method which is halfway between the two approximations: we keep the path integral bead masses equal to the physical particle masses but attach a Langevin thermostat to the internal modes of the ring polymer during the dynamics. We justify this by showing analytically that the inclusion of an internal mode thermostat does not affect any of the established features of RPMD: thermostatted RPMD is equally valid with respect to everything that has actually been proven about the method as RPMD itself. In particular, because of the choice of bead masses, the resulting method is still optimum in the short-time limit, and the transition state approximation to its reaction rate theory remains closely related to the semiclassical instanton approximation in the deep quantum tunneling regime. In effect, there is a continuous family of methods with these properties, parameterised by the strength of the Langevin friction. Here, we explore numerically how the approximation to quantum dynamics depends on this friction, with a particular emphasis on vibrational spectroscopy. We find that a broad range of frictions approaching optimal damping give similar results, and that these results are immune to both the resonance problem of RPMD and the curvature problem of CMD.

How to remove the spurious resonances from ring polymer molecular dynamics

International Nuclear Information System (INIS)

Rossi, Mariana; Manolopoulos, David E.; Ceriotti, Michele

2014-01-01

Two of the most successful methods that are presently available for simulating the quantum dynamics of condensed phase systems are centroid molecular dynamics (CMD) and ring polymer molecular dynamics (RPMD). Despite their conceptual differences, practical implementations of these methods differ in just two respects: the choice of the Parrinello-Rahman mass matrix and whether or not a thermostat is applied to the internal modes of the ring polymer during the dynamics. Here, we explore a method which is halfway between the two approximations: we keep the path integral bead masses equal to the physical particle masses but attach a Langevin thermostat to the internal modes of the ring polymer during the dynamics. We justify this by showing analytically that the inclusion of an internal mode thermostat does not affect any of the established features of RPMD: thermostatted RPMD is equally valid with respect to everything that has actually been proven about the method as RPMD itself. In particular, because of the choice of bead masses, the resulting method is still optimum in the short-time limit, and the transition state approximation to its reaction rate theory remains closely related to the semiclassical instanton approximation in the deep quantum tunneling regime. In effect, there is a continuous family of methods with these properties, parameterised by the strength of the Langevin friction. Here, we explore numerically how the approximation to quantum dynamics depends on this friction, with a particular emphasis on vibrational spectroscopy. We find that a broad range of frictions approaching optimal damping give similar results, and that these results are immune to both the resonance problem of RPMD and the curvature problem of CMD

Effective representation of amide III, II, I, and A modes on local vibrational modes: Analysis of ab initio quantum calculation results.

Science.gov (United States)

Hahn, Seungsoo

2016-10-28

The Hamiltonian matrix for the first excited vibrational states of a protein can be effectively represented by local vibrational modes constituting amide III, II, I, and A modes to simulate various vibrational spectra. Methods for obtaining the Hamiltonian matrix from ab initio quantum calculation results are discussed, where the methods consist of three steps: selection of local vibrational mode coordinates, calculation of a reduced Hessian matrix, and extraction of the Hamiltonian matrix from the Hessian matrix. We introduce several methods for each step. The methods were assessed based on the density functional theory calculation results of 24 oligopeptides with four different peptide lengths and six different secondary structures. The completeness of a Hamiltonian matrix represented in the reduced local mode space is improved by adopting a specific atom group for each amide mode and reducing the effect of ignored local modes. The calculation results are also compared to previous models using C=O stretching vibration and transition dipole couplings. We found that local electric transition dipole moments of the amide modes are mainly bound on the local peptide planes. Their direction and magnitude are well conserved except amide A modes, which show large variation. Contrary to amide I modes, the vibrational coupling constants of amide III, II, and A modes obtained by analysis of a dipeptide are not transferable to oligopeptides with the same secondary conformation because coupling constants are affected by the surrounding atomic environment.

Theory of high-force DNA stretching and overstretching.

Science.gov (United States)

Storm, C; Nelson, P C

2003-05-01

Single-molecule experiments on single- and double-stranded DNA have sparked a renewed interest in the force versus extension of polymers. The extensible freely jointed chain (FJC) model is frequently invoked to explain the observed behavior of single-stranded DNA, but this model does not satisfactorily describe recent high-force stretching data. We instead propose a model (the discrete persistent chain) that borrows features from both the FJC and the wormlike chain, and show that it resembles the data more closely. We find that most of the high-force behavior previously attributed to stretch elasticity is really a feature of the corrected entropic elasticity; the true stretch compliance of single-stranded DNA is several times smaller than that found by previous authors. Next we elaborate our model to allow coexistence of two conformational states of DNA, each with its own stretch and bend elastic constants. Our model is computationally simple and gives an excellent fit through the entire overstretching transition of nicked, double-stranded DNA. The fit gives the first value for the bend stiffness of the overstretched state. In particular, we find the effective bend stiffness for DNA in this state to be about 12 nm k(B)T, a value quite different from either the B-form or single-stranded DNA.

The Acute Effects of Upper Extremity Stretching on Throwing Velocity in Baseball Throwers

Directory of Open Access Journals (Sweden)

Michael Williams

2013-01-01

Full Text Available Purpose. To examine the effects of static and proprioceptive neuromuscular facilitation (PNF stretching of the shoulder internal rotators on throwing velocity. Subjects. 27 male throwers (mean age = 25.1 years old, SD = 2.4 with adequate knowledge of demonstrable throwing mechanics. Study Design. Randomized crossover trial with repeated measures. Methods. Subjects warmed up, threw 10 pitches at their maximum velocity, were randomly assigned to 1 of 3 stretching protocols (static, PNF, or no stretch, and then repeated their 10 pitches. Velocities were recorded after each pitch and average and peak velocities were recorded after each session. Results. Data were analyzed using a repeated measures ANOVA. No significant interaction between stretching and throwing velocity was observed. Main effects for time were not statistically significant. Main effects for the stretching groups were statistically significant. Discussion. Results suggest that stretching of the shoulder internal rotators did not significantly affect throwing velocity immediately after stretching. This may be due to the complexity of the throwing task. Conclusions. Stretching may be included in a thrower's warm-up without any effects on throwing velocity. Further research should be performed using a population with more throwing experience and skill.

Efficacy of hamstring stretching programs in schoolchildren. A systematic review

Directory of Open Access Journals (Sweden)

Carlos-Alberto BECERRA FERNANDEZ

2017-03-01

Full Text Available The main purpose of the present review was to examine the scientific literature on the effects of physical education-based stretching programs on hamstring extensibility in schoolchildren aged 6-11 years. For this purpose relevant studies were searched from ten electronic databases dated up through May 2015. Of the 25 potentially relevant articles identified and retrieved for more detailed evaluation, only eight studies were included in the present review because they met the inclusion criteria. The overall results showed that incorporating hamstring stretching as a part of physical education classes produces a significant improvement in the scores of the tests: straight leg raise and classic sit-and-reach, for the experimental groups, but not for control groups. Stretching programs can be included in Physical Education classes, specifically during the warm-up and the cool down periods in order to improve hamstring extensibility. Although it seems that the stretching exercises in the warm-up period could be less effective in gaining flexibility in school children. Studies that use a stretching volume between 4 and 7 minutes per session and 2-4 training classes per week, obtain statistically significant improvements on the levels of hamstring flexibility in the experimental groups. However, after a five-week detraining period, children revert back to their initial flexibility levels. Therefore, it seems appropriate that physical education teachers should implement stretching programs to improve the students´ flexibility during the Physical Education classes.

Implementation of a controller for linear positioners applicable in optical fiber stretching

International Nuclear Information System (INIS)

Castrillo Piedra, Andres Rodolfo

2014-01-01

A low cost controller is implemented for linear positioners applicable in optic fiber stretching. The possibility of using a donated equipment is evaluated by the Escuela de Ingenieria Mecanica. The equipment is required by the non-linear photonic research laboratory (NLPR-LAB) for stretching of micro structured fiber. The process has required a slow and precise stretching, so the controllers must be precisely programmed to rotate the motors at different speeds. Donated equipment is evaluated to see if it is possible to use for fiber stretching [es

A narrow linewidth tunable single longitudinal mode Ga-EDF fiber laser

Science.gov (United States)

Mohamed Halip, N. H.; Abu Bakar, M. H.; Latif, A. A.; Muhd-Yasin, S. Z.; Zulkifli, M. I.; Mat-Sharif, K. A.; Omar, N. Y. M.; Mansoor, A.; Abdul-Rashid, H. A.; Mahdi, M. A.

2018-05-01

A tunable ring cavity single longitudinal mode (SLM) fiber laser incorporating Gallium-Erbium co-doped fiber (Ga-EDF) gain medium and several mode filtration techniques is demonstrated. With Ga-EDF, high emission power was accorded in short fiber length, allowing shorter overall cavity length and wider free spectral range. Tunable bandpass filter, sub-ring structure, and cascaded dissimilar fiber taper were utilized to filter multi-longitudinal modes. Each of the filter mechanism was tested individually within the laser cavity to assess its performance. Once the performance of each filter was obtained, all of them were deployed into the laser system. Ultimately, the 1561.47 nm SLM laser achieved a narrow linewidth laser, optical signal-to-noise ratio, and power fluctuation of 1.19 kHz, 61.52 dB and 0.16 dB, respectively. This work validates the feasibility of Ga-EDF to attain a stable SLM output in simple laser configuration.

Post-activation depression of soleus stretch reflexes in healthy and spastic humans

DEFF Research Database (Denmark)

Grey, Michael James; Klinge, Klaus; Crone, Clarissa

2007-01-01

Reduced depression of transmitter release from Ia afferents following previous activation (post-activation depression) has been suggested to be involved in the pathophysiology of spasticity. However, the effect of this mechanism on the myotatic reflex and its possible contribution to increased...... reflex excitability in spastic participants has not been tested. To investigate these effects, we examined post-activation depression in Soleus H-reflex responses and in mechanically evoked Soleus stretch reflex responses. Stretch reflex responses were evoked with consecutive dorsiflexion perturbations...... of the soleus stretch reflex and H-reflex decreased as the interval between the stimulus/perturbation was decreased. Similarly, the stretch-evoked torque decreased. In the spastic participants, the post-activation depression of both reflexes and the stretch-evoked torque was significantly smaller than...

Micro-Fluidic Dye Ring Laser - Experimental Tuning of the Wavelength and Numerical Simulation of the Cavity Modes

DEFF Research Database (Denmark)

Gersborg-Hansen, Morten; Balslev, Søren; Mortensen, Niels Asger

2006-01-01

We demonstrate wavelength tuning of a micro-fluidic dye ring laser. Wavelength tunability is obtained by controlling the liquid dye concentration. The device performance is modelled by FEM simulations supporting a ray-tracing view.......We demonstrate wavelength tuning of a micro-fluidic dye ring laser. Wavelength tunability is obtained by controlling the liquid dye concentration. The device performance is modelled by FEM simulations supporting a ray-tracing view....

Damage percolation during stretch flange forming of aluminum alloy sheet

Science.gov (United States)

Chen, Zengtao; Worswick, Michael J.; Keith Pilkey, A.; Lloyd, David J.

2005-12-01

A multi-scale finite element (FE)-damage percolation model was employed to simulate stretch flange forming of aluminum alloys AA5182 and AA5754. Material softening and strain gradients were captured using a Gurson-based FE model. FE results were then fed into the so-called damage percolation code, from which the damage development was modelled within measured microstructures. The formability of the stretch flange samples was predicted based upon the onset of catastrophic failure triggered by profuse void coalescence within the measured second-phase particle field. Damage development is quantified in terms of crack and void areal fractions, and compared to metallographic results obtained from interrupted stretch flange specimens. Parametric study is conducted on the effect of void nucleation strain in the prediction of formability of stretch flanges to "calibrate" proper nucleation strains for both alloys.

Diadophis Puntatus Puntatus (Southern Ring-neck Snake) Predation

Science.gov (United States)

Gotte, Steve W.

2016-01-01

DIADOPHIS PUNCTATUS PUNCTATUS (Southern Ring-necked Snake). PREDATION. Here I present the first record of Buteo lineatus (Red-shouldered Hawk) predator on a Diadophis p. punctatus. At ca. 1100h on l2 February2 013,I observed a B. lineatus eating a katydid in Corkscrew Swamp Sanctuary (26.2730'N, 81.6079"W;WGS 84), Collier Co., Florida, USA. The hawk was in a Pond Cypress tree on the edge of a small prairie bordered on one side by a cypress swamp and by pine woodland on the other. Immediately upon consuming the katydid, the hawk flew to the ground ca. 1.5 m from an elevated boardwalk to grab an adult D. punctatus. It then flew with the snake in its talons to a branch 3 m high ca. l0 m from the boardwalk. The hawk stretched and otherwise manipulated the struggling snake (Fig.1) before consuming the still moving snake. Although snakes are a well-known component of B. lineatus diet (Clark1 987A. Field Guide to the Hawks of North America. Houghton Mifflin Co. Boston, Massachusetts 198 pp.), I found only one literature reference to Red-shouldered Hawks eating Ring-neck Snakes (Fisher 1893.Hawks and Owls of the United States in their Relation to Agriculture. U.S. Dept. Agric., Div Ornith. Mamm. Bull. 3). That specimen was from Canton, New York (taken 26 Oct IBBB) and would be a D. p. edwardisii (Northern Ring-necked Snake), while the snake reported on here is a Diadophis p. punctatus (USNM Herp Image 2847a -c). Based on evidence presented by Fontanella et al. (2008. Mol. Phylogenet Evol.46:1049-1070), D. p. edwardisii and D. p. punctatus are likely different species.

Application of FEL technique for constructing high-intensity, monochromatic, polarized gamma-sources at storage rings

Energy Technology Data Exchange (ETDEWEB)

Saldin, E.L.; Schneidmiller, E.A.; Ulyanov, Yu.N. [Automatic Systems Corporation, Samara (Russian Federation)] [and others

1995-12-31

A possibility to construct high-intensity tunable monochromatic{gamma}-source at high energy storage rings is discussed. It is proposed to produce {gamma}-quanta by means of Compton backscattering of laser photons on electrons circulating in the storage. The laser light wavelength is chosen in such a way that after the scattering, the electron does not leave the separatrix. So as the probability of the scattering is rather small, energy oscillations are damped prior the next scattering. As a result, the proposed source can operate in {open_quotes}parasitic{close_quote} mode not interfering with the main mode of the storage ring operation. Analysis of parameters of existent storage rings (PETRA, ESRF, Spring-8, etc) shows that the laser light wavelength should be in infrared, {lambda}{approximately} 10 - 400 {mu}m, wavelength band. Installation at storage rings of tunable free-electron lasers with the peak and average output power {approximately} 10 MW and {approximately} 1 kW, respectively, will result in the intensity of the {gamma}-source up to {approximately} 10{sup 14}s{sup -1} with tunable {gamma}-quanta energy from several MeV up to several hundreds MeV. Such a {gamma}-source will reveal unique possibilities for precision investigations in nuclear physics.

Coherent time-stretch transformation for real-time capture of wideband signals.

Science.gov (United States)

Buckley, Brandon W; Madni, Asad M; Jalali, Bahram

2013-09-09

Time stretch transformation of wideband waveforms boosts the performance of analog-to-digital converters and digital signal processors by slowing down analog electrical signals before digitization. The transform is based on dispersive Fourier transformation implemented in the optical domain. A coherent receiver would be ideal for capturing the time-stretched optical signal. Coherent receivers offer improved sensitivity, allow for digital cancellation of dispersion-induced impairments and optical nonlinearities, and enable decoding of phase-modulated optical data formats. Because time-stretch uses a chirped broadband (>1 THz) optical carrier, a new coherent detection technique is required. In this paper, we introduce and demonstrate coherent time stretch transformation; a technique that combines dispersive Fourier transform with optically broadband coherent detection.

Facet development for a faceted stretched-membrane dish by Solar Kinetics, Inc

Energy Technology Data Exchange (ETDEWEB)

Schertz, P.T.; Brown, D.C.; Konnerth, A. III (Solar Kinetics, Inc., Dallas, TX (United States))

1991-07-01

A 3.6-meter diameter stretched-membrane optical facet for a parabolic dish has been successfully designed and demonstrated under contract with Sandia National Laboratories. Twelve facets identical to them will be used to make the lightweight reflector of the dish. The project goal of 2.5-mrad surface accuracy was met with each of the two full-sized prototypes, and accuracies of as low as 1.1 mrad were achieved. The facet weight is 11.7 kg/m{sup 2} (2.4lbs/ft{sup 2}). The facet is similar in construction to the successful stretched-membrane heliostat; it has two thin metal membranes attached to a ring. However, the front membrane for this facet is plastically formed at the factor in order to achieve a shorter facet f/D (approximately 3.0). A passive tether restrains the from membrane when not in operation, that is, when the stabilizing vacuum is off. The optical surface is achieved with a silvered-acrylic film laminated to the metal membrane. The facet is expected to cost $55.40/m{sup 2} at a production rate of 10,000 facets per year and $115, 000/m{sup 2}-at a production rate of 500 facets a year. Several key issues have been resolved. Stress concentrations due to seams in the reflective laminate did not cause membrane rupture during forming as they have for dishes with lower focal length-to-diameter ratios. The laminate survived the forming process and simulated operation without deterioration. The optical effect of the tether on the membrane was tested and found to be very small. Most important, highly accurate shapes were obtained using a simple forming procedure. Additional tests are needed to demonstrate process repeatablility and facet performance in typical operating conditions. 18 refs., 36 figs., 11 tabs.

Fast all-optical multistate flip-flop operation realized by a single self-sustained micro-ring laser memory cell

International Nuclear Information System (INIS)

Wang, Zhuoran; Yuan, Guohui

2013-01-01

We investigate all-optical multistate flip-flop operation realized by a single self-sustained micro-ring laser memory cell based on a time-domain multi-mode nonlinear model. Each state is written by the corresponding 100 ps-width input non-return-to-zero (NRZ) pulse carrying the directional and wavelength information, and the cell remains in the written state until another trigger arrives. The effects of key parameters including the detuning frequency and injection power ratio on the injection locking and flipping regions of different modes in both directions of the micro-ring device are studied. By optimizing the operation conditions, we simulate the minimal switching speed for each mode. The fast switching speed of less than 20 ps and up to ten mode flip-flop operation indicate that this single optical memory cell can support ten states at a data rate of at least 10 Gbps, which is particularly valuable for the realization of future all-optical networking and functional sub-system technology. (letter)

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.

Dynamics of a Dispersion-Managed Passively Mode-Locked Er-Doped Fiber Laser Using Single Wall Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Norihiko Nishizawa

2015-07-01

Full Text Available We investigated the dynamics of a dispersion-managed, passively mode-locked, ultrashort-pulse, Er-doped fiber laser using a single-wall carbon nanotube (SWNT device. A numerical model was constructed for analysis of the SWNT fiber laser. The initial process of passive mode-locking, the characteristics of the output pulse, and the dynamics inside the cavity were investigated numerically for soliton, dissipative-soliton, and stretched-pulse mode-locking conditions. The dependencies on the total dispersion and recovery time of the SWNTs were also examined. Numerical results showed similar behavior to experimental results.

Ca{sup 2+} influx and ATP release mediated by mechanical stretch in human lung fibroblasts

Energy Technology Data Exchange (ETDEWEB)

Murata, Naohiko [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Ito, Satoru, E-mail: itori@med.nagoya-u.ac.jp [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Furuya, Kishio [Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Takahara, Norihiro [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Naruse, Keiji [Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Okayama 700-8558 (Japan); Aso, Hiromichi; Kondo, Masashi [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Sokabe, Masahiro [Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Hasegawa, Yoshinori [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan)

2014-10-10

Highlights: • Uniaxial stretching activates Ca{sup 2+} signaling in human lung fibroblasts. • Stretch-induced intracellular Ca{sup 2+} elevation is mainly via Ca{sup 2+} influx. • Mechanical strain enhances ATP release from fibroblasts. • Stretch-induced Ca{sup 2+} influx is not mediated by released ATP or actin cytoskeleton. - Abstract: One cause of progressive pulmonary fibrosis is dysregulated wound healing after lung inflammation or damage in patients with idiopathic pulmonary fibrosis and severe acute respiratory distress syndrome. The mechanical forces are considered to regulate pulmonary fibrosis via activation of lung fibroblasts. In this study, the effects of mechanical stretch on the intracellular Ca{sup 2+} concentration ([Ca{sup 2+}]{sub i}) and ATP release were investigated in primary human lung fibroblasts. Uniaxial stretch (10–30% in strain) was applied to fibroblasts cultured in a silicone chamber coated with type I collagen using a stretching apparatus. Following stretching and subsequent unloading, [Ca{sup 2+}]{sub i} transiently increased in a strain-dependent manner. Hypotonic stress, which causes plasma membrane stretching, also transiently increased the [Ca{sup 2+}]{sub i}. The stretch-induced [Ca{sup 2+}]{sub i} elevation was attenuated in Ca{sup 2+}-free solution. In contrast, the increase of [Ca{sup 2+}]{sub i} by a 20% stretch was not inhibited by the inhibitor of stretch-activated channels GsMTx-4, Gd{sup 3+}, ruthenium red, or cytochalasin D. Cyclic stretching induced significant ATP releases from fibroblasts. However, the stretch-induced [Ca{sup 2+}]{sub i} elevation was not inhibited by ATP diphosphohydrolase apyrase or a purinergic receptor antagonist suramin. Taken together, mechanical stretch induces Ca{sup 2+} influx independently of conventional stretch-sensitive ion channels, the actin cytoskeleton, and released ATP.

Low-frequency electrostatic dust-modes in a nonuniform magnetized dusty plasma

International Nuclear Information System (INIS)

Paul, S.K.; Duha, S.S.; Mamun, A.A.

2004-07-01

A self-consistent and general description of obliquely propagating low frequency electrostatic dust-modes in a inhomogeneous, magnetized dusty plasma system has been presented. A number of different situations, which correspond to different low-frequency electrostatic dust-modes, namely, dust-acoustic mode, dust-drift mode, dust-cyclotron mode, dust-lower-hybrid mode, and other associated modes (such as, accelerated and retarded dust-acoustic modes, accelerated and retarded dust-lower-hybrid modes, etc.), have also been investigated. It has been shown that the effects of obliqueness and inhomogeneities in plasma particle number densities introduce new electrostatic dust modes as well as significantly modify the dispersion properties of the other low-frequency electrostatic dust-modes. The implications of these results to some space and astrophysical dusty plasma systems, especially to planetary ring-systems and cometary tails, are briefly mentioned. (author)

Eddy current inspection of stationary blade rings

International Nuclear Information System (INIS)

Krzywosz, K.J.; Hastings, S.N.

1994-01-01

Stationary turbine blade rings in a US power plant have experienced chloride-induced cracking. Failure analysis determined two types of cracking mechanisms: corrosion fatigue cracking confined to the leading edge of the outer shroud; and stress corrosion cracking present all over the blade surface. Fluorescent dye penetrant is typically used to detect and size cracks. However, it requires cleaning the blade rings by sandblasting to obtain reliable inspection results. Sand blasting in turn requires sealing the lower half of the turbine housing to prevent sand from contaminating the rest of the power plant components. Furthermore, both the penetrant examination and the removal of the sand are time consuming and costly. An alternative NDE technique is desirable which requires no pre-cleaning of the blade and a quick go/no-go inspection with the capability of estimating the crack length. This paper presents an innovative eddy current technique which meets the desired objectives by incorporating the use of specially designed contoured scanners equipped with an array of pancake coils. A set of eddy current pancake coils housed in three different scanners is used to manually scan and inspect the convex side of the stationary blade rings. The pancake coils are operated in a transmit/receive mode using two separate eddy current instruments. This paper presents the inspection concept, including scanner and probe designs, and test results from the various stages of multiple blade rings

Investing in a Large Stretch Press

Science.gov (United States)

Choate, M.; Nealson, W.; Jay, G.; Buss, W.

1986-01-01

Press for forming large aluminum parts from plates provides substantial economies. Study assessed advantages and disadvantages of investing in large stretch-forming press, and also developed procurement specification for press.

Optimal stretching in the reacting wake of a bluff body.

Science.gov (United States)

Wang, Jinge; Tithof, Jeffrey; Nevins, Thomas D; Colón, Rony O; Kelley, Douglas H

2017-12-01

We experimentally study spreading of the Belousov-Zhabotinsky reaction behind a bluff body in a laminar flow. Locations of reacted regions (i.e., regions with high product concentration) correlate with a moderate range of Lagrangian stretching and that range is close to the range of optimal stretching previously observed in topologically different flows [T. D. Nevins and D. H. Kelley, Phys. Rev. Lett. 117, 164502 (2016)]. The previous work found optimal stretching in a closed, vortex dominated flow, but this article uses an open flow and only a small area of appreciable vorticity. We hypothesize that optimal stretching is common in advection-reaction-diffusion systems with an excitation threshold, including excitable and bistable systems, and that the optimal range depends on reaction chemistry and not on flow shape or characteristic speed. Our results may also give insight into plankton blooms behind islands in ocean currents.

Stretching of material lines in pseudo-turbulence induced by small rising bubbles

International Nuclear Information System (INIS)

Tanaka, M; Tsujimura, Y; Kanatani, H

2011-01-01

Direct numerical simulations have been conducted for the stretching of material lines in pseudo-turbulence induced by small rising bubbles in order to understand the mixing characteristics of bubbly flows. Contaminated bubbles are considered and are treated as light solid particles. An immersed boundary method has been used for evaluating the coupling force between the bubbles and the surrounding fluid flows. Numerical results show that the total length of material lines increases exponentially in time as a result of stretching and folding due to the rising bubbles. The material lines tend to accumulate in the wake regions of the bubbles, and they are strongly stretched in the vertical direction there. It is also found that the stretching rate of material lines increases with the mean void fraction when it is normalized by the magnitude of the rate-of-strain tensor of liquid flow in pseudo-turbulence. In the case of high void fractions, material lines tend to align with the direction of maximum stretching, and are effectively stretched.

Stretching of material lines in pseudo-turbulence induced by small rising bubbles

Energy Technology Data Exchange (ETDEWEB)

Tanaka, M; Tsujimura, Y; Kanatani, H, E-mail: mtanaka@kit.ac.jp [Department of Mechanical and System Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan)

2011-12-22

Direct numerical simulations have been conducted for the stretching of material lines in pseudo-turbulence induced by small rising bubbles in order to understand the mixing characteristics of bubbly flows. Contaminated bubbles are considered and are treated as light solid particles. An immersed boundary method has been used for evaluating the coupling force between the bubbles and the surrounding fluid flows. Numerical results show that the total length of material lines increases exponentially in time as a result of stretching and folding due to the rising bubbles. The material lines tend to accumulate in the wake regions of the bubbles, and they are strongly stretched in the vertical direction there. It is also found that the stretching rate of material lines increases with the mean void fraction when it is normalized by the magnitude of the rate-of-strain tensor of liquid flow in pseudo-turbulence. In the case of high void fractions, material lines tend to align with the direction of maximum stretching, and are effectively stretched.

A coaxial ring-sidearm power extraction design

International Nuclear Information System (INIS)

Ben-Menahem, S.; Yu, D.

1996-01-01

We report a successful klystron power extraction design, in which a TEM coaxial mode is transmitted into TE10 mode of a WR90 rectangular waveguide at 11.42 GHz, with very little TEM reflection and almost vanishing asymmetric (TEM → TE11, or monopole to dipole) reflectance. Our coupler consists of a ring (disk) around the coaxial waveguide, and a coax-WR90 sidearm junction. The methods used in the design are numerical simulation, performed on the MAFIA3 T3 time- domain module and on the High Frequency Structure Simulator, and analytical treatment to guide the numerical runs. The demerit parameters (dipole reflectance and TEM reflection) can be reduced as much as desired (to zero in principle), the only limitation being computer run time and memory. Results are accurate to a few percent

A numerical study of the quantum oscillations in multiple dangling rings

International Nuclear Information System (INIS)

Gu, B.Y.; Basu, C.

1994-12-01

We present the quantum mechanical calculations on magnetoconductance of the quantum waveguide topology containing multiply connected dangling mesoscopic rings with the transfer matrix approach. The profiles of the conductance as functions of the Fermi wave number of electrons and of the magnetic flux depend on the number of rings as also on the geometric configuration of the system. The conductance spectrum of this system for disordered lengths in the ring circumferences, dangling links, ballistic leads connecting consecutive dangling rings and disordered magnetic flux is examined in details. We find that there exist two kinds of mini-bands, one originating from the eigenstates of the rings, i.e. the intrinsic mini-bands, and the extra mini-bands. Some of these extra minibands are associated with the dangling links connecting the rings to the main quantum wire, while others are from the standing wave modes associated with the ballistic leads connecting adjacent dangling rings. These different kinds of mini-bands have completely different properties and responds differently to the geometric parameter fluctuations. Unlike the system of potential scatterers, this system of geometric scatterers shows complete band formations at all energies even for finite number of scatterers present. There is a preferential decay of the energy states, depending upon the type of disorder introduced. By controlling the geometric parameters, the conductance band structure of such a model can be artificially tailored and thus may guide the design of better mesoscopic switching devices. (author). 19 refs, 7 figs

Effect of simultaneous stretching of the wrist and finger extensors for lateral epicondylitis: a gross anatomical study of the tendinous origins of the extensor carpi radialis brevis and extensor digitorum communis.

Science.gov (United States)

Shirato, Rikiya; Wada, Takuro; Aoki, Mitsuhiro; Iba, Kousuke; Kanaya, Kohei; Fujimiya, Mineko; Yamashita, Toshihiko

2015-11-01

Pulling the wrist into flexion with the elbow in extension and forearm in pronation has been used as the stretching technique of wrist extensors for lateral epicondylitis. Simultaneous stretching of the fingers in addition to the wrist flexion has also been applied. However, the mechanism of this simultaneous stretching has not been clarified. This study is designed to clarify the mechanism underlying this simultaneous stretching technique based on the anatomical features of the origins of the extensor carpi radialis brevis (ECRB) and extensor digitorum communis (EDC). Thirty-nine arms from formalin-embalmed Japanese human specimens were dissected. The features of the origins of the ECRB and EDC were macroscopically observed, and the locations of each origin on the lateral epicondyle were measured. The ECRB had a long and wide, purely tendinous origin which originated from the anterior slope of the lateral epicondyle. The tendinous origin of the index finger of the EDC (EDC-IF) arose from the posterior aspect of the ECRB tendinous origin, with a coexisting muscular portion observed at the level of the proximal forearm. The middle finger of the EDC (EDC-MF) had a short tendinous origin with an associated muscular portion and originated proximo-laterally to the origin of the ECRB on the lateral epicondyle. In addition, the muscular origin of the EDC-MF arose on the superficial and posterior aspect of the ECRB tendinous origin. In contrast, the ring and little fingers of the EDC originated from the tendinous septum of the extensor digiti minimi and extensor carpi ulnaris, and had no connection with the ECRB tendinous origin. On the basis of our anatomical findings, simultaneous stretching of the wrist extensors by wrist, index and middle fingers flexion could provide stretching force to both the tendinous origins of the ECRB and EDC through the EDC-IF and EDC-MF.

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)

Time stretch and its applications

Science.gov (United States)

Mahjoubfar, Ata; Churkin, Dmitry V.; Barland, Stéphane; Broderick, Neil; Turitsyn, Sergei K.; Jalali, Bahram

2017-06-01

Observing non-repetitive and statistically rare signals that occur on short timescales requires fast real-time measurements that exceed the speed, precision and record length of conventional digitizers. Photonic time stretch is a data acquisition method that overcomes the speed limitations of electronic digitizers and enables continuous ultrafast single-shot spectroscopy, imaging, reflectometry, terahertz and other measurements at refresh rates reaching billions of frames per second with non-stop recording spanning trillions of consecutive frames. The technology has opened a new frontier in measurement science unveiling transient phenomena in nonlinear dynamics such as optical rogue waves and soliton molecules, and in relativistic electron bunching. It has also created a new class of instruments that have been integrated with artificial intelligence for sensing and biomedical diagnostics. We review the fundamental principles and applications of this emerging field for continuous phase and amplitude characterization at extremely high repetition rates via time-stretch spectral interferometry.

Minimum stiffness criteria for ring frame stiffeners of space launch vehicles

Science.gov (United States)

Friedrich, Linus; Schröder, Kai-Uwe

2016-12-01

Frame stringer-stiffened shell structures show high load carrying capacity in conjunction with low structural mass and are for this reason frequently used as primary structures of aerospace applications. Due to the great number of design variables, deriving suitable stiffening configurations is a demanding task and needs to be realized using efficient analysis methods. The structural design of ring frame stringer-stiffened shells can be subdivided into two steps. One, the design of a shell section between two ring frames. Two, the structural design of the ring frames such that a general instability mode is avoided. For sizing stringer-stiffened shell sections, several methods were recently developed, but existing ring frame sizing methods are mainly based on empirical relations or on smeared models. These methods do not mandatorily lead to reliable designs and in some cases the lightweight design potential of stiffened shell structures can thus not be exploited. In this paper, the explicit physical behaviour of ring frame stiffeners of space launch vehicles at the onset of panel instability is described using mechanical substitute models. Ring frame stiffeners of a stiffened shell structure are sized applying existing methods and the method suggested in this paper. To verify the suggested method and to demonstrate its potential, geometrically non-linear finite element analyses are performed using detailed finite element models.

Use of a ring-shaped, passively stable, superconducting magnetic bearing in the ring spinning process; Einsatz eines ringfoermigen, passiv stabilen, supraleitenden Magnetlagers im Ringspinnprozess

Energy Technology Data Exchange (ETDEWEB)

Berger, Anne; Sparing, Maria; Berger, Dietmar; Fuchs, Guenter; Schultz, Ludwig [IFW Dresden (Germany). Inst. fuer Metallische Werkstoffe; Hossain, Mahmud; Abdkader, Anwar; Cherif, Chokri [TU Dresden (Germany). ITM

2015-07-01

For the integration of a superconducting magnetic bearing in a ring spinning machine a LN{sub 2} continuous flow cryostat was developed, which is needed to cool the superconductor below its transition temperature of ∝91 K and simultaneously ensures that the spinning process takes place at room temperature. The ring spinning process is the most widely used process for spinning yarn. In this case, a loose fiber connection is first stretched in a roller system, then twisted by the so-called spinning ring-ring traveler system, and finally wound on a spindle. The spinning ring is a circular guide, which is mounted around the spindle. On this the ring traveler rotates as yarn guide. The yarn is driven by the rotation of the spindle and there is a balloon-shaped movement of the yarn which results the twist. The productivity of the process is limited by the systematic frictional heat between the yarn, spinning ring and ring travelers. This leads at high speeds to yarn breakage and limits the maximum spindle speed depending on the type of fiber to a maximum of 25,000 U/min. To increase the speed and thus the productivity of the process, the conventional spinning ring-ring rotor system is replaced by a superconducting magnetic bearing. Here floats a NdFeB permanent magnet passively stable over the LN{sub 2} cooled ceramic high-temperature superconductor YBa{sub 2}Cu{sub 3}O{sub 7-x}. Driven by the yarn the permanent magnet rotates, thus ensuring the necessary balloon-shaped yarn movement to twist. Such a bearing has been successfully tested in a ring spinning machine. Preliminary results show a similar yarn quality. [German] Fuer die Integration eines supraleitenden Magnetlagers in eine Ringspinnmaschine wurde ein LN{sub 2}-Durchflusskryostat entwickelt, der noetig ist, um den Supraleiter unter seine Sprungtemperatur von ∝91 K zu kuehlen und gleichzeitig dafuer sorgt, dass der Spinnprozess bei Raumtemperatur ablaeuft. Der Ringspinnprozess ist der am weitesten verbreitete

Optimisation of spontaneous four-wave mixing in a ring microcavity

Science.gov (United States)

Chuprina, I. N.; An, P. P.; Zubkova, E. G.; Kovalyuk, V. V.; Kalachev, A. A.; Gol'tsman, G. N.

2017-11-01

A theory of spontaneous four-wave mixing in a ring microcavity is developed. The rate of emission of biphotons for pulsed and monochromatic pumping with allowance for the dispersion of group velocities is analytically calculated. In the first case, pulses in the form of an increasing exponential are considered, which are optimal for excitation of an individual resonator mode. The behaviour of the group velocity dispersion as a function of the width and height of the waveguide is studied for a specific case of a ring microcavity made of silicon nitride. The results of the numerical calculation are in good agreement with the experimental data. The ring microcavity is made of two types of waveguides: completely etched and half etched. It is found that the latter allow for better control over the parameters in the manufacturing process, making them more predictable. Presented at the Russian - British Symposium on Quantum Technologies (Moscow, 20 - 23 March 2017)

EFFECTS OF DYNAMIC AND STATIC STRETCHING WITHIN GENERAL AND ACTIVITY SPECIFIC WARM-UP PROTOCOLS

Directory of Open Access Journals (Sweden)

Michael Samson

2012-06-01

Full Text Available The purpose of the study was to determine the effects of static and dynamic stretching protocols within general and activity specific warm-ups. Nine male and ten female subjects were tested under four warm-up conditions including a 1 general aerobic warm-up with static stretching, 2 general aerobic warm-up with dynamic stretching, 3 general and specific warm-up with static stretching and 4 general and specific warm-up with dynamic stretching. Following all conditions, subjects were tested for movement time (kicking movement of leg over 0.5 m distance, countermovement jump height, sit and reach flexibility and 6 repetitions of 20 metre sprints. Results indicated that when a sport specific warm-up was included, there was an 0.94% improvement (p = 0.0013 in 20 meter sprint time with both the dynamic and static stretch groups. No such difference in sprint performance between dynamic and static stretch groups existed in the absence of the sport specific warm-up. The static stretch condition increased sit and reach range of motion (ROM by 2.8% more (p = 0.0083 than the dynamic condition. These results would support the use of static stretching within an activity specific warm-up to ensure maximal ROM along with an enhancement in sprint performance

Chromaticity correction in the TRISTAN phase I main ring with two types of insertion

International Nuclear Information System (INIS)

Wu, Yingzhi; Egawa, Kazumi.

1984-07-01

The TRISTAN main ring now under construction has four insertions. Besides the normal modes in which the four insertions have the same optics, the TRISTAN main ring will be operated in somewhat more complicated configurations with insertions having different optics. This report will consider chromaticity corrections using six families of sextupoles for the TRISTAN main ring with two different insertion types; opposite insertions have the same optics. The strength of correcting sextupoles is determined mainly using the W-correction method. The program PATRICIA is used to track the trajectories of test particles over 800 turns. The results show that the correction scheme adopted allows adequately large amplitudes of betatron and synchrotron oscillations. (author)

Contact of a spherical probe with a stretched rubber substrate

Science.gov (United States)

Frétigny, Christian; Chateauminois, Antoine

2017-07-01

We report on a theoretical and experimental investigation of the normal contact of stretched neo-Hookean substrates with rigid spherical probes. Starting from a published formulation of surface Green's function for incremental displacements on a prestretched, neo-Hookean, substrate [J. Mech. Phys. Solids 56, 2957 (2008), 10.1016/j.jmps.2008.07.002], a model is derived for both adhesive and nonadhesive contacts. The shape of the elliptical contact area together with the contact load and the contact stiffness are predicted as a function of the in-plane stretch ratios λx and λy of the substrate. The validity of this model is assessed by contact experiments carried out using an uniaxally stretched silicone rubber. For stretch ratio below about 1.25, a good agreement is observed between theory and experiments. Above this threshold, some deviations from the theoretical predictions are induced as a result of the departure of the mechanical response of the silicone rubber from the neo-Hokeean description embedded in the model.

Periostin inhibits mechanical stretch-induced apoptosis in osteoblast-like MG-63 cells.

Science.gov (United States)

Yu, Kai-Wen; Yao, Chung-Chen; Jeng, Jiiang-Huei; Shieh, Hao-Ying; Chen, Yi-Jane

2018-04-01

Appropriate mechanical stress plays an important role in regulating the proliferation and differentiation of osteoblasts, whereas high-level mechanical stress may be harmful and compromise cell survival. Periostin, a matricellular protein, is essential in maintaining functional integrity of bone and collagen-rich connective tissue in response to mechanical stress. This study investigated whether or not high-level mechanical stretch induces cell apoptosis and the regulatory role of periostin in mechanical stretch-induced apoptosis in osteoblastic cells. Osteoblast-like MG-63 cells were seeded onto Bio-Flex I culture plates and subjected to cyclic mechanical stretching (15% elongation, 0.1 Hz) in a Flexercell tension plus system-5000. The same process was applied to cells pre-treated with exogenous human recombinant periostin before mechanical stretching. We used a chromatin condensation and membrane permeability dead cell apoptosis kit to evaluate the stretch-induced cell responses. Expression of caspase-3 and cPARP was examined by immunofluorescent stain and flow cytometry. The expression of periostin in MG-63 cells is involved in the TGF-β signaling pathway. High-level cyclic mechanical stretch induced apoptotic responses in MG-63 osteoblastic cells. The percentages of apoptotic cells and cells expressing cPARP protein increased in the groups of cells subjected to mechanical stretch, but these responses were absent in the presence of exogenous periostin. Our study revealed that high-level mechanical stretch induces apoptotic cell death, and that periostin plays a protective role against mechanical stretch-induced apoptosis in osteoblastic cells. Copyright © 2017. Published by Elsevier B.V.

Multi-state lasing in self-assembled ring-shaped green fluorescent protein microcavities

Energy Technology Data Exchange (ETDEWEB)

Dietrich, Christof P., E-mail: cpd3@st-andrews.ac.uk; Höfling, Sven; Gather, Malte C., E-mail: mcg6@st-andrews.ac.uk [SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS (United Kingdom)

2014-12-08

We demonstrate highly efficient lasing from multiple photonic states in microcavities filled with self-assembled rings of recombinant enhanced green fluorescent protein (eGFP) in its solid state form. The lasing regime is achieved at very low excitation energies of 13 nJ and occurs from cavity modes dispersed in both energy and momentum. We attribute the momentum distribution to very efficient scattering of incident light at the surface of the eGFP rings. The distribution of lasing states in energy is induced by the large spectral width of the gain spectrum of recombinant eGFP (FWHM ≅ 25 nm)

Force encoding in muscle spindles during stretch of passive muscle.

Directory of Open Access Journals (Sweden)

Kyle P Blum

2017-09-01

Full Text Available Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle

Force encoding in muscle spindles during stretch of passive muscle.

Science.gov (United States)

Blum, Kyle P; Lamotte D'Incamps, Boris; Zytnicki, Daniel; Ting, Lena H

2017-09-01

Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs) of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt) predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening) of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle lengthening conditions

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.

Stretch activates human myometrium via ERK, caldesmon and focal adhesion signaling.

Directory of Open Access Journals (Sweden)

Yunping Li

2009-10-01

Full Text Available An incomplete understanding of the molecular mechanisms responsible for myometrial activation from the quiescent pregnant state to the active contractile state during labor has hindered the development of effective therapies for preterm labor. Myometrial stretch has been implicated clinically in the initiation of labor and the etiology of preterm labor, but the molecular mechanisms involved in the human have not been determined. We investigated the mechanisms by which gestation-dependent stretch contributes to myometrial activation, by using human uterine samples from gynecologic hysterectomies and Cesarean sections. Here we demonstrate that the Ca requirement for activation of the contractile filaments in human myometrium increases with caldesmon protein content during gestation and that an increase in caldesmon phosphorylation can reverse this inhibitory effect during labor. By using phosphotyrosine screening and mass spectrometry of stretched human myometrial samples, we identify 3 stretch-activated focal adhesion proteins, FAK, p130Cas, and alpha actinin. FAK-Y397, which signals integrin engagement, is constitutively phosphorylated in term human myometrium whereas FAK-Y925, which signals downstream ERK activation, is phosphorylated during stretch. We have recently identified smooth muscle Archvillin (SmAV as an ERK regulator. A newly produced SmAV-specific antibody demonstrates gestation-specific increases in SmAV protein levels and stretch-specific increases in SmAV association with focal adhesion proteins. Thus, whereas increases in caldesmon levels suppress human myometrium contractility during pregnancy, stretch-dependent focal adhesion signaling, facilitated by the ERK activator SmAV, can contribute to myometrial activation. These results suggest that focal adhesion proteins may present new targets for drug discovery programs aimed at regulation of uterine contractility.

Soleus stretch reflex during cycling

DEFF Research Database (Denmark)

Grey, Michael James; Pierce, C. W.; Milner, T. E.

2001-01-01

The modulation and strength of the human soleus short latency stretch reflex was investigated by mechanically perturbing the ankle during an unconstrained pedaling task. Eight subjects pedaled at 60 rpm against a preload of 10 Nm. A torque pulse was applied to the crank at various positions durin...

Optical tweezers stretching of chromatin

NARCIS (Netherlands)

Pope, L.H.; Bennink, Martin L.; Greve, Jan

2003-01-01

Recently significant success has emerged from exciting research involving chromatin stretching using optical tweezers. These experiments, in which a single chromatin fibre is attached by one end to a micron-sized bead held in an optical trap and to a solid surface or second bead via the other end,

Acute effects of 15min static or contract-relax stretching modalities on plantar flexors neuromuscular properties.

Science.gov (United States)

Babault, Nicolas; Kouassi, Blah Y L; Desbrosses, Kevin

2010-03-01

The present study aimed to investigate the immediate effects of 15 min static or sub-maximal contract-relax stretching modalities on the neuromuscular properties of plantar flexor muscles. Ten male volunteers were tested before and immediately after 15 min static or contract-relax stretching programs of plantar flexor muscles (20 stretches). Static stretching consisted in 30s stretches to the point of discomfort. For the contract-relax stretching modality, subjects performed 6s sub-maximal isometric plantar flexion before 24s static stretches. Measurements included maximal voluntary isometric torque (MVT) and the corresponding electromyographic activity of soleus (SOL) and medial gastrocnemius (MG) muscles (RMS values), as well as maximal peak torque (Pt) elicited at rest by single supramaximal electrical stimulation of the tibial nerve. After 15 min stretching, significant MVT and SOL RMS decreases were obtained (-6.9+/-11.6% and -6.5+/-15.4%, respectively). No difference was obtained between stretching modalities. Pt remained unchanged after stretching. MG RMS changes were significantly different between stretching modalities (-9.4+/-18.3% and +3.5+/-11.6% after static and contract-relax stretching modalities, respectively). These findings indicated that performing 15 min static or contract-relax stretching had detrimental effects on the torque production capacity of plantar flexor muscles and should be precluded before competition. Mechanisms explaining this alteration seemed to be stretch modality dependent. Copyright 2009 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Stretching Diagnostics and Mixing Properties In The Stratosphere

Science.gov (United States)

Legras, B.; Shuckburgh, E.

The "finite size Lyapunov exponent" and the "effective diffusivity" are two diagnos- tics of mixing which have been recently introduced to investigate atmospheric flows. Both have been used to successfully identify the barriers to transport, for instance at the edge of the stratospheric polar vortex. Here we compare the two diagnostics in detail. The equivalent length has the advantage of arising as a mixing quantification from a rigid theoretical framework, however it has the disadvantage of being an aver- age quantity (the average around a tracer contour). The finite size Lyapunov exponent may be defined at any point in the flow, and quantifies the stretching properties expe- rienced by a fluid parcel both in its past and future evolution. In particular, the lines of maximum stretching at any time delineate the building blocks of the chaotic stirring. However the interpretation of the finite size Lyapunov exponent as a mixing time is less direct and depends on the alignment of tracer contours with the stretching lines.

Stretch-stimulated glucose transport in skeletal muscle is regulated by Rac1.

Science.gov (United States)

Sylow, Lykke; Møller, Lisbeth L V; Kleinert, Maximilian; Richter, Erik A; Jensen, Thomas E

2015-02-01

Rac1 regulates stretch-stimulated (i.e. mechanical stress) glucose transport in muscle. Actin depolymerization decreases stretch-induced glucose transport in skeletal muscle. Rac1 is a required part of the mechanical stress-component of the contraction-stimulus to glucose transport in skeletal muscle. An alternative to the canonical insulin signalling pathway for glucose transport is muscle contraction/exercise. Mechanical stress is an integrated part of the muscle contraction/relaxation cycle, and passive stretch stimulates muscle glucose transport. However, the signalling mechanism regulating stretch-stimulated glucose transport is not well understood. We recently reported that the actin cytoskeleton regulating GTPase, Rac1, was activated in mouse muscle in response to stretching. Rac1 is a regulator of contraction- and insulin-stimulated glucose transport, however, its role in stretch-stimulated glucose transport and signalling is unknown. We therefore investigated whether stretch-induced glucose transport in skeletal muscle required Rac1 and the actin cytoskeleton. We used muscle-specific inducible Rac1 knockout mice as well as pharmacological inhibitors of Rac1 and the actin cytoskeleton in isolated soleus and extensor digitorum longus muscles. In addition, the role of Rac1 in contraction-stimulated glucose transport during conditions without mechanical load on the muscles was evaluated in loosely hanging muscles and muscles in which cross-bridge formation was blocked by the myosin ATPase inhibitors BTS and Blebbistatin. Knockout as well as pharmacological inhibition of Rac1 reduced stretch-stimulated glucose transport by 30-50% in soleus and extensor digitorum longus muscle. The actin depolymerizing agent latrunculin B similarly decreased glucose transport in response to stretching by 40-50%. Rac1 inhibition reduced contraction-stimulated glucose transport by 30-40% in tension developing muscle but did not affect contraction-stimulated glucose transport in

Possible stretched exponential parametrization for humidity absorption in polymers.

Science.gov (United States)

Hacinliyan, A; Skarlatos, Y; Sahin, G; Atak, K; Aybar, O O

2009-04-01

Polymer thin films have irregular transient current characteristics under constant voltage. In hydrophilic and hydrophobic polymers, the irregularity is also known to depend on the humidity absorbed by the polymer sample. Different stretched exponential models are studied and it is shown that the absorption of humidity as a function of time can be adequately modelled by a class of these stretched exponential absorption models.

The hydrogen-bond network of water supports propagating optical phonon-like modes.

Science.gov (United States)

Elton, Daniel C; Fernández-Serra, Marivi

2016-01-04

The local structure of liquid water as a function of temperature is a source of intense research. This structure is intimately linked to the dynamics of water molecules, which can be measured using Raman and infrared spectroscopies. The assignment of spectral peaks depends on whether they are collective modes or single-molecule motions. Vibrational modes in liquids are usually considered to be associated to the motions of single molecules or small clusters. Using molecular dynamics simulations, here we find dispersive optical phonon-like modes in the librational and OH-stretching bands. We argue that on subpicosecond time scales these modes propagate through water's hydrogen-bond network over distances of up to 2 nm. In the long wavelength limit these optical modes exhibit longitudinal-transverse splitting, indicating the presence of coherent long-range dipole-dipole interactions, as in ice. Our results indicate the dynamics of liquid water have more similarities to ice than previously thought.

Process Parameter Identification in Thin Film Flows Driven by a Stretching Surface

Directory of Open Access Journals (Sweden)

Satyananda Panda

2014-01-01

Full Text Available The flow of a thin liquid film over a heated stretching surface is considered in this study. Due to a potential nonuniform temperature distribution on the stretching sheet, a temperature gradient occurs in the fluid which produces surface tension gradient at the free surface of the thin film. As a result, the free surface deforms and these deformations are advected by the flow in the stretching direction. This work focuses on the inverse problem of reconstructing the sheet temperature distribution and the sheet stretch rate from observed free surface variations. This work builds on the analysis of Santra and Dandapat (2009 who, based on the long-wave expansion of the Navier-Stokes equations, formulate a partial differential equation which describes the evolution of the thickness of a film over a nonisothermal stretched surface. In this work, we show that after algebraic manipulation of a discrete form of the governing equations, it is possible to reconstruct either the unknown temperature field on the sheet and hence the resulting heat transfer or the stretching rate of the underlying surface. We illustrate the proposed methodology and test its applicability on a range of test problems.

The acute effect of static and dynamic stretching during warm-ups on anaerobic performance in trained women

Directory of Open Access Journals (Sweden)

rouhollah haghshenas

2014-09-01

Full Text Available The purpose of this study was to investigate effects of static stretching, dynamic stretching and no stretching methods on power and speed in volleyball players. Therefore, Twenty-four volleyball players (height: 173.29 ± 7.81 m; mass: 62.12 ± 8.73 kg; age: 22.66 ± 4.02 years; experience: 3.27 ± 6.37 were tested for speed performance using the 20 meter sprint test and also for power using vertical jump test after static stretching, dynamic stretching and no stretching. The results analyzed using ANOVA showed that There was a significant increase in height jump after dynamic stretching against static stretching. But, there were no significant differences between no stretching and static stretching groups. In addition, there was a significant decrease in time 20 meter sprint after dynamic stretching against static stretching and no stretching groups. The results of this study suggest that it may be desirable for volleyball players to perform dynamic exercises before the performance of activities that require a high power output.

4-Mercaptophenylboronic acid: conformation, FT-IR, Raman, OH stretching and theoretical studies.

Science.gov (United States)

Parlak, Cemal; Ramasami, Ponnadurai; Tursun, Mahir; Rhyman, Lydia; Kaya, Mehmet Fatih; Atar, Necip; Alver, Özgür; Şenyel, Mustafa

2015-06-05

4-Mercaptophenylboronic acid (4-mpba, C6H7BO2S) was investigated experimentally by vibrational spectroscopy. The molecular structure and spectroscopic parameters were studied by computational methods. The molecular dimer was investigated for intermolecular hydrogen bonding. Potential energy distribution analysis of normal modes was performed to identify characteristic frequencies. The present work provides a simple physical picture of the OH stretch vibrational spectra of 4-mpba and analogues of the compound studied. When the different computational methods are compared, there is a strong evidence of the better performance of the BLYP functional than the popular B3LYP functional to describe hydrogen bonding in the dimer. The findings of this research work should be useful to experimentalists in their quests for functionalised 4-mpba derivatives. Copyright © 2015 Elsevier B.V. All rights reserved.

A method for simultaneous linear optics and coupling correction for storage rings with turn-by-turn beam position monitor data

Energy Technology Data Exchange (ETDEWEB)

Yang, Xi [Brookhaven National Laboratory, Upton, Long Island, NY 11973 (United States); Huang, Xiaobiao, E-mail: xiahuang@slac.stanford.edu [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

2016-08-21

We propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. The fitting results are used for lattice correction. The method has been successfully demonstrated on the NSLS-II storage ring.

A method for simultaneous linear optics and coupling correction for storage rings with turn-by-turn beam position monitor data

Energy Technology Data Exchange (ETDEWEB)

Yang, Xi [Brookhaven National Lab. (BNL), Upton, NY (United States); Huang, Xiaobiao [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2016-08-01

We propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. Furthermore, the fitting results are used for lattice correction. Our method has been successfully demonstrated on the NSLS-II storage ring.

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

The effects of the pedestal/floor interface on the dynamic characteristics of the storage ring girder support assemblies

International Nuclear Information System (INIS)

Jendrzejczyk, J.A.; Chen, S.S.; Zhu, S.; Mangra, D.; Smith, R.K.

1993-05-01

To avoid unacceptable vibration of the storage ring quadrupoles, and to ensure that the established vibration criteria are satisfied, the philosophy from inception of the APS has been (1) to locate and design the machine to minimize motion of the storage ring basemat and, (2) following construction, to monitor machine operation and user experiments to ensure that vibration sources are not introduced. This report addresses the design of the storage ring girder support assemblies, and, specifically, the effect of the pedestal/floor interface on the dynamic characteristics (i.e., resonant frequencies, damping, and mode shape)

Towards the Fourier limit on the super-ACO Storage Ring FEL

International Nuclear Information System (INIS)

Couprie, M.E.; De Ninno, G.; Moneron, G.; Nutarelli, D.; Hirsch, M.; Garzella, D.; Renault, E.; Roux, R.; Thomas, C.

2001-01-01

Systematic studies on the Free Electron Laser (FEL) line and micropulse have been performed on the Super-ACO storage ring FEL with a monochromator and a double-sweep streak camera under various conditions of operation (detuning, 'CW' and Q-switched mode). From these data, it appears that the FEL is usually operated very close to the Fourier limit

Towards the Fourier limit on the super-ACO Storage Ring FEL

CERN Document Server

Couprie, Marie Emmanuelle; Garzella, D; Hirsch, M; Moneron, G; Nutarelli, D; Renault, E; Roux, R; Thomas, C

2001-01-01

Systematic studies on the Free Electron Laser (FEL) line and micropulse have been performed on the Super-ACO storage ring FEL with a monochromator and a double-sweep streak camera under various conditions of operation (detuning, 'CW' and Q-switched mode). From these data, it appears that the FEL is usually operated very close to the Fourier limit.

On the effect of nuclear bridge modes on donor-acceptor electronic coupling in donor-bridge-acceptor molecules

International Nuclear Information System (INIS)

Davis, Daly; Toroker, Maytal Caspary; Speiser, Shammai; Peskin, Uri

2009-01-01

We report a theoretical study of intra-molecular electronic coupling in a symmetric DBA (donor-bridge-acceptor) complex, in which a donor electronic site is coupled to an acceptor site by way of intervening orbitals of a molecular bridge unit. In the off-resonant (deep tunneling) regime of electronic transport, the lowest unoccupied molecular orbitals (MO's) of the DBA system are split into distinguishable donor/acceptor and bridge orbitals. The effect of geometrical changes at the bridge on the donor/acceptor electronic energy manifold is studied for local stretching and bending modes. It is demonstrated that the energy splitting in the manifold of donor/acceptor unoccupied MOs changes in response to such changes, as assumed in simple McConnell-type models. Limitations of the simple models are revealed where the electronic charging of the bridge orbitals correlates with increasing donor/acceptor orbital energy splitting only for stretching but not for bending bridge modes.

Dynamics and structure of stretched flames

Energy Technology Data Exchange (ETDEWEB)

Law, C.K. [Princeton Univ., NJ (United States)

1993-12-01

This program aims to gain fundamental understanding on the structure, geometry, and dynamics of laminar premixed flames, and relate these understanding to the practical issues of flame extinction and stabilization. The underlying fundamental interest here is the recent recognition that the response of premixed flames can be profoundly affected by flame stretch, as manifested by flow nonuniformity, flame curvature, and flame/flow unsteadiness. As such, many of the existing understanding on the behavior of premixed flames need to be qualitatively revised. The research program consists of three major thrusts: (1) detailed experimental and computational mapping of the structure of aerodynamically-strained planar flames, with emphasis on the effects of heat loss, nonequidiffusion, and finite residence time on the flame thickness, extent of incomplete reaction, and the state of extinction. (2) Analytical study of the geometry and dynamics of stretch-affected wrinkled flame sheets in simple configurations, as exemplified by the Bunsen flame and the spatially-periodic flame, with emphasis on the effects of nonlinear stretch, the phenomena of flame cusping, smoothing, and tip opening, and their implications on the structure and burning rate of turbulent flames. (3) Stabilization and blowoff of two-dimensional inverted premixed and stabilization and determining the criteria governing flame blowoff. The research is synergistically conducted through the use of laser-based diagnostics, computational simulation of the flame structure with detailed chemistry and transport, and mathematical analysis of the flame dynamics.

Excluded Volume Effects in Gene Stretching

OpenAIRE

Lam, Pui-Man

2002-01-01

We investigate the effects excluded volume on the stretching of a single DNA in solution. We find that for small force F, the extension h is not linear in F but proportion to F^{\\chi}, with \\chi=(1-\

Calculation of electrodynamical characteristics and choice of accelerating structure for storage ring

International Nuclear Information System (INIS)

Karnaukhov, I.M.; Popkov, Yu.P.; Telegin, Yu.N.; Trushkin, N.A.; Dajkovskij, A.G.; Zakamskaya, L.T.; Ryabov, A.D.

1989-01-01

Comparative analysis of several types of accelerating structures at standing E 010 wave is conducted on the basis of numerical calculations performed with the use of the PRUD-0 and PRUD programs. Dispersion dependences of electromagnetic field distribution, quality and coupling impedance are calculated both for axially symmetric and axially asymmetric modes of oscillations in structures with 699.3 MHz operating frequency. It is shown that structure with a cell the form of which is optimized with respect to shunt resistance on the main mode possesses the numerical spurious impedance in higher modes. This is the main factor when choosing accelerating structure for storage ring with multi-bunch operation conditions. 12 refs.; 3 figs.; 3 tabs

Stretched versus compressed exponential kinetics in α-helix folding

International Nuclear Information System (INIS)

Hamm, Peter; Helbing, Jan; Bredenbeck, Jens

2006-01-01

In a recent paper (J. Bredenbeck, J. Helbing, J.R. Kumita, G.A. Woolley, P. Hamm, α-helix formation in a photoswitchable peptide tracked from picoseconds to microseconds by time resolved IR spectroscopy, Proc. Natl. Acad. Sci USA 102 (2005) 2379), we have investigated the folding of a photo-switchable α-helix with a kinetics that could be fit by a stretched exponential function exp(-(t/τ) β ). The stretching factor β became smaller as the temperature was lowered, a result which has been interpreted in terms of activated diffusion on a rugged energy surface. In the present paper, we discuss under which conditions diffusion problems occur with stretched exponential kinetics (β 1). We show that diffusion problems do have a strong tendency to yield stretched exponential kinetics, yet, that there are conditions (strong perturbation from equilibrium, performing the experiment in the folding direction) under which compressed exponential kinetics would be expected instead. We discuss the kinetics on free energy surfaces predicted by simple initiation-propagation models (zipper models) of α-helix folding, as well as by folding funnel models. We show that our recent experiment has been performed under condition for which models with strong downhill driving force, such as the zipper model, would predict compressed, rather than stretched exponential kinetics, in disagreement with the experimental observation. We therefore propose that the free energy surface along a reaction coordinate that governs the folding kinetics must be relatively flat and has a shape similar to a 1D golf course. We discuss how this conclusion can be unified with the thermodynamically well established zipper model by introducing an additional kinetic reaction coordinate

Design analysis of a self-acting spiral-groove ring seal for counter-rotating shafts. [o ring seals

Science.gov (United States)

Dirusso, E.

1983-01-01

A self-acting spiral groove inter-shaft ring seal of nominal 16.33 cm (6.43 in.) diameter for sealing fan bleed air between counter rotating shafts in advanced turbofan engines was analyzed. The analysis focused on the lift force characteristics of the spiral grooves. A NASA Lewis developed computer program for predicting the performance of gas lubricated face seals was used to optimize the spiral groove geometry to produce maximum lift force. Load capacity curves (lift force as function of film thickness) were generated for four advanced turbofan engine operating conditions at relative seal speeds ranging from 17,850 to 29,800 rpm, sealed air pressures from 6 to 42 N/sq cm (9 to 60 psi) absolute and temperatures from 95 to 327 C (203 to 620 F). The relative seal sliding speed range was 152 to 255 m/sec (500 to 836 ft/sec). The analysis showed that the spiral grooves are capable of producing sufficient lift force such that the ring seal will operate in a noncontacting mode over the operating range of typical advanced turbofan engines.

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

Tunable and stable single-longitudinal-mode dual-wavelength erbium fiber laser with 1.3 nm mode spacing output

International Nuclear Information System (INIS)

Yeh, C H; Shih, F Y; Wang, C H; Chow, C W; Chi, S

2008-01-01

In this investigation, we propose and investigate a stable and tunable dual-wavelength erbium-doped fiber (EDF) ring laser with self-injected Fabry-Perot laser diode (FP-LD) scheme. By using an FP-LD incorporated with a tunable bandpass filter (TBF) within the gain cavity, the fiber laser can lase at two single-longitudinal-mode (SLM) wavelengths simultaneously due to the self-injected operation. The proposed dual-wavelength laser has a good performance of the output power and optical side-mode suppression ratio (SMSR). The laser also shows a wide tuning range from 1523.08 to 1562.26 nm. Besides, the output stabilities of the fiber laser are also discussed

Effect of Twisting and Stretching on Magneto Resistance and Spin Filtration in CNTs

Directory of Open Access Journals (Sweden)

Anil Kumar Singh

2017-08-01

Full Text Available Spin-dependent quantum transport properties in twisted carbon nanotube and stretched carbon nanotube are calculated using density functional theory (DFT and non-equilibrium green’s function (NEGF formulation. Twisting and stretching have no effect on spin transport in CNTs at low bias voltages. However, at high bias voltages the effects are significant. Stretching restricts any spin-up current in antiparallel configuration (APC, which results in higher magneto resistance (MR. Twisting allows spin-up current almost equivalent to the pristine CNT case, resulting in lower MR. High spin filtration is observed in PC and APC for pristine, stretched and twisted structures at all applied voltages. In APC, at low voltages spin filtration in stretched CNT is higher than in pristine and twisted ones, with pristine giving a higher spin filtration than twisted CNT.

Optimal control of stretching process of flexible solar arrays on spacecraft based on a hybrid optimization strategy

Directory of Open Access Journals (Sweden)

Qijia Yao

2017-07-01

Full Text Available The optimal control of multibody spacecraft during the stretching process of solar arrays is investigated, and a hybrid optimization strategy based on Gauss pseudospectral method (GPM and direct shooting method (DSM is presented. First, the elastic deformation of flexible solar arrays was described approximately by the assumed mode method, and a dynamic model was established by the second Lagrangian equation. Then, the nonholonomic motion planning problem is transformed into a nonlinear programming problem by using GPM. By giving fewer LG points, initial values of the state variables and control variables were obtained. A serial optimization framework was adopted to obtain the approximate optimal solution from a feasible solution. Finally, the control variables were discretized at LG points, and the precise optimal control inputs were obtained by DSM. The optimal trajectory of the system can be obtained through numerical integration. Through numerical simulation, the stretching process of solar arrays is stable with no detours, and the control inputs match the various constraints of actual conditions. The results indicate that the method is effective with good robustness. Keywords: Motion planning, Multibody spacecraft, Optimal control, Gauss pseudospectral method, Direct shooting method

Effect of Ankle Positioning During Hamstring Stretches for Improving Straight Leg Hip Flexion Motion.

Science.gov (United States)

Laudner, Kevin G; Benjamin, Peter J; Selkow, Noelle M

2016-03-01

To compare the effects of stretching the hamstrings with the ankle in either a plantar-flexed (PF) or dorsiflexed (DF) position for improving straight leg hip flexion range of motion (ROM) over a 4-week period. Randomized, single-blinded, pretest, posttest design. Athletic training facility. Each limb of 34 asymptomatic individuals (15 males, 19 females) was randomly assigned to one of the 3 groups. Twenty-four limbs received hamstring stretches with the ankle in DF, 24 limbs received hamstring stretches with the ankle in PF, and 20 limbs received no stretch (control). Ankle position (PF, DF) during hamstring stretching. We measured pretest and posttest passive straight leg hip flexion ROM with the test ankle in a neutral position. For the intervention groups, the test limb was passively stretched with the ankle held in end range DF or PF for their respective group. Each stretch was held for 30 seconds for a total of 3 applications. Two treatment sessions were completed per week for a total of 4 weeks. The control limbs received no stretching during the 4-week period. We conducted 1-way analyses of covariance to determine significant changes in ROM between groups (P hamstrings in either PF or DF improve straight leg hip ROM compared with a control group. The results of this study should be considered by clinicians when determining the optimal stretching techniques aimed at increasing hamstring length.

Acute Effect of Different Combined Stretching Methods on Acceleration and Speed in Soccer Players

Directory of Open Access Journals (Sweden)

Amiri-Khorasani Mohammadtaghi

2016-04-01

Full Text Available The purpose of this study was to investigate the acute effect of different stretching methods, during a warm-up, on the acceleration and speed of soccer players. The acceleration performance of 20 collegiate soccer players (body height: 177.25 ± 5.31 cm; body mass: 65.10 ± 5.62 kg; age: 16.85 ± 0.87 years; BMI: 20.70 ± 5.54; experience: 8.46 ± 1.49 years was evaluated after different warm-up procedures, using 10 and 20 m tests. Subjects performed five types of a warm-up: static, dynamic, combined static + dynamic, combined dynamic + static, and no-stretching. Subjects were divided into five groups. Each group performed five different warm-up protocols in five non-consecutive days. The warm-up protocol used for each group was randomly assigned. The protocols consisted of 4 min jogging, a 1 min stretching program (except for the no-stretching protocol, and 2 min rest periods, followed by the 10 and 20 m sprint test, on the same day. The current findings showed significant differences in the 10 and 20 m tests after dynamic stretching compared with static, combined, and no-stretching protocols. There were also significant differences between the combined stretching compared with static and no-stretching protocols. We concluded that soccer players performed better with respect to acceleration and speed, after dynamic and combined stretching, as they were able to produce more force for a faster execution.

Flow of viscous fluid along an exponentially stretching curved surface

Directory of Open Access Journals (Sweden)

N.F. Okechi

Full Text Available In this paper, we present the boundary layer analysis of flow induced by rapidly stretching curved surface with exponential velocity. The governing boundary value problem is reduced into self-similar form using a new similarity transformation. The resulting equations are solved numerically using shooting and Runge-Kutta methods. The numerical results depicts that the fluid velocity as well as the skin friction coefficient increases with the surface curvature, similar trend is also observed for the pressure. The dimensionless wall shear stress defined for this problem is greater than that of a linearly stretching curved surface, but becomes comparably less for a surface stretching with a power-law velocity. In addition, the result for the plane surface is a special case of this study when the radius of curvature of the surface is sufficiently large. The numerical investigations presented in terms of the graphs are interpreted with the help of underlying physics of the fluid flow and the consequences arising from the curved geometry. Keywords: Boundary layer flow, Curved surface, Exponential stretching, Curvature

Directional Cell Migration in Response to Repeated Substratum Stretching

Science.gov (United States)

Okimura, Chika; Iwadate, Yoshiaki

2017-10-01

Crawling migration plays an essential role in a variety of biological phenomena, including development, wound healing, and immune system function. Migration properties such as anterior-posterior polarity, directionality, and velocity are regulated not only by the reception of a chemoattractant but also by sensing mechanical inputs from the external environment. In this review, we describe the mechanical response of migrating cells, particularly under repeated stretching of the elastic substratum, highlighting the fact that there appear to be two independent mechanosensing systems that generate the polarity needed for migration. Cells that have no stress fibers, such as Dictyostelium cells and neutrophil-like differentiated HL-60 cells, migrate perpendicular to the stretching direction via myosin II localization. Cells that do possess stress fibers, however, such as fish keratocytes, migrate parallel to the stretching via a stress-fiber-dependent process.

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

Mixed-mode elastic-plastic fracture of 2024-T351 aluminium alloy

International Nuclear Information System (INIS)

Sakata, Masaru; Aoki, Shigeru; Kishimoto, Kikuo; Chikugo, Hiroshi; Takizawa, Masakazu.

1985-01-01

In order to evaluate accurately the strength and structural soundness of the structures made of high toughness materials, it is necessary to clarify the fracture behavior under the loading condition of mixed mode such as oblique cracks as well as the elasto-plastic fracture behavior of the materials in the case of single opening displacement type mode. About the fracture condition in the state of mixed mode, various theories based on the linear fracture mechanics have been proposed. In this study, the elasto-plastic fracture toughness test of mixed mode was carried out by using an aluminum alloy as the subject, and the behavior of dulling and development of cracks was observed with a scanning electron microscope. Moreover, the state of deformation of the test pieces was analyzed by elasto-plastic finite element method, thus the parameters controlling the elasto-plastic fracture of mixed mode were examined. In the range of this study, the limiting stretch zone width in the case of loading of mixed mode was 12 μm similarly to the case of single mode. Also in the case of mixed mode, there was distinct difference between the inclination of a dulling straight line and an R-curve, and the limit value of J intergral was determined by their intersection. (Kako, I.)

On prediction of OH stretching frequencies in intramolecularly hydrogen bonded systems

DEFF Research Database (Denmark)

Hansen, Poul Erik; Spanget-Larsen, Jens

2012-01-01

OH stretching frequencies are investigated for a series of non-tautomerizing systems with intramolecular hydrogen bonds. Effective OH stretching wavenumbers are predicted by the application of empirical correlation procedures based on the results of B3LYP/6-31G(d) theoretical calculations...

Optimization of path length stretching in Monte Carlo calculations for non-leakage problems

Energy Technology Data Exchange (ETDEWEB)

Hoogenboom, J.E. [Delft Univ. of Technology (Netherlands)

2005-07-01

Path length stretching (or exponential biasing) is a well known variance reduction technique in Monte Carlo calculations. It can especially be useful in shielding problems where particles have to penetrate a lot of material before being tallied. Several authors sought for optimization of the path length stretching parameter for detection of the leakage of neutrons from a slab. Here the adjoint function behaves as a single exponential function and can well be used to determine the stretching parameter. In this paper optimization is sought for a detector embedded in the system, which changes the adjoint function in the detector drastically. From literature it is known that the combination of path length stretching and angular biasing can result in appreciable variance reduction. However, angular biasing is not generally available in general purpose Monte Carlo codes and therefore we want to restrict ourselves to the application of pure path length stretching and finding optimum parameters for that. Nonetheless, the starting point for our research is the zero-variance scheme. In order to study the solution in detail the simplified monoenergetic two-direction model is adopted, which allows analytical solutions and can still be used in a Monte Carlo simulation. Knowing the zero-variance solution analytically, it is shown how optimum path length stretching parameters can be derived from it. It results in path length shrinking in the detector. Results for the variance in the detector response are shown in comparison with other patterns for the stretching parameter. The effect of anisotropic scattering on the path length stretching parameter is taken into account. (author)

Cyclic mechanical stretch enhances BMP9-induced osteogenic differentiation of mesenchymal stem cells.

Science.gov (United States)

Song, Yang; Tang, Yinhong; Song, Jinlin; Lei, Mingxing; Liang, Panpan; Fu, Tiwei; Su, Xudong; Zhou, Pengfei; Yang, Li; Huang, Enyi

2018-04-01

The purpose of this study was to investigate whether mechanical stretch can enhance the bone morphogenetic protein 9 (BMP9)-induced osteogenic differentiation in MSCs. Recombinant adenoviruses were used to overexpress the BMP9 in C3H10T1/2 MSCs. Cells were seeded onto six-well BioFlex collagen I-coated plates and subjected to cyclic mechanical stretch [6% elongation at 60 cycles/minute (1 Hz)] in a Flexercell FX-4000 strain unit for up to 12 hours. Immunostaining and confocal microscope were used to detect cytoskeleton organization. Cell cycle progression was checked by flow cytometry. Alkaline phosphatase activity was measured with a Chemiluminescence Assay Kit and was quantified with a histochemical staining assay. Matrix mineralization was examined by Alizarin Red S Staining. Mechanical stretch induces cytoskeleton reorganization and inhibits cell proliferation by preventing cells entry into S phase of the cell cycle. Although mechanical stretch alone does not induce the osteogenic differentiation of C3H10T1/2 MSCs, co-stimulation with mechanical stretch and BMP9 enhances alkaline phosphatase activity. The expression of key lineage-specific regulators (e.g., osteocalcin (OCN), SRY-related HMG-box 9, and runt-related transcription factor 2) is also increased after the co-stimulation, compared to the mechanical stretch stimulation along. Furthermore, mechanical stretch augments the BMP9-mediated bone matrix mineralization of C3H10T1/2 MSCs. Our results suggest that mechanical stretch enhances BMP9-induced osteoblastic lineage specification in C3H10T1/2 MSCs.

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.

Photon-induced tunability of the thermospin current in a Rashba ring

Science.gov (United States)

Abdullah, Nzar Rauf; Arnold, Thorsten; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar

2018-04-01

The goal of this work is to show how the thermospin polarization current in a quantum ring changes in the presence of Rashba spin-orbit coupling and a quantized single photon mode of a cavity the ring is placed in. Employing the reduced density operator and a general master equation formalism, we find that both the Rashba interaction and the photon field can significantly modulate the spin polarization and the thermospin polarization current. Tuning the Rashba coupling constant, degenerate energy levels are formed corresponding to the Aharonov-Casher destructive phase interference in the quantum ring system. Our analysis indicates that the maximum spin polarization can be observed at the points of degenerate energy levels due to spin accumulation in the system without the photon field. The thermospin current is thus suppressed. In the presence of the cavity, the photon field leads to an additional kinetic momentum of the electron. As a result the spin polarization can be enhanced by the photon field.

Optical properties of Au colloids self-organized into rings via copolymer templates

Energy Technology Data Exchange (ETDEWEB)

Lamarre, S. S. [Laval University, Department of Chemistry (Canada); Sarrazin, A.; Proust, J.; Yockell-Lelievre, H.; Plain, J. [University of Technology of Troyes, Laboratory of Nanotechnology, Instrumentation and Optics, Charles Delaunay Institute (France); Ritcey, A. M. [Laval University, Department of Chemistry (Canada); Maurer, T., E-mail: thomas.maurer@utt.fr [University of Technology of Troyes, Laboratory of Nanotechnology, Instrumentation and Optics, Charles Delaunay Institute (France)

2013-05-15

The investigation of the localized surface plasmon resonance for plasmonic nanoparticles has opened new perspectives for optical nanosensors. Nowadays, an issue in plasmonics is the development of large scale and low cost devices. We focus here on the Langmuir-Blodgett technique to self-organize gold nanoparticles ({approx}7 nm) into rings ({approx}60 nm) via polystyrene-b-polymethylmethacrylate templates. In particular, we investigated the optical properties of organized gold nanoparticle rings over large areas and report experimental evidence for plasmon resonances of both individual nanoparticles and collective modes. This paves the way for designing devices with multiple resonances in the visible-infra-red spectrum and developing optical sensors.

Crustal Stretching Style and Lower Crust Flow of the South China Sea Northern Margin

Science.gov (United States)

Bai, Y.; Dong, D.; Runlin, D.

2017-12-01

There is a controversy about crustal stretching style of the South China Sea (SCS) northern margin mainly due to considerable uncertainty of stretching factor estimation, for example, as much as 40% of upper crust extension (Walsh et al., 1991) would be lost by seismic profiles due to poor resolution. To discover and understand crustal stretching style and lower crustal flow on the whole, we map the Moho and Conrad geometries based on gravity inversion constrained by deep seismic profiles, then according to the assumption of upper and lower crust initial thickness, upper and lower crust stretching factors are estimated. According to the comparison between upper and lower crust stretching factors, the SCS northern margin could be segmented into three parts, (1) sediment basins where upper crust is stretched more than lower crust, (2) COT regions where lower crust is stretched more than upper crust, (3) other regions where the two layers have similar stretching factors. Stretching factor map shows that lower crust flow happened in both of COT and sediment basin regions where upper crust decouples with lower crust due to high temperature. Pressure contrast by sediment loading in basins and erosion in sediment-source regions will lead to lower crust flow away from sediment sink to source. Decoupled and fractured upper crust is stretched further by sediment loading and the following compensation would result in relatively thick lower crust than upper crust. In COT regions with thin sediment coverage, low-viscosity lower crust is easier to thin in extensional environment, also the lower crust tends to flow away induced by magma upwelling. Therefore, continental crust on the margin is not stretching in a constant way but varies with the tectonic setting changes. This work is supported by National Natural Science Foundation of China (Grant No. 41506055, 41476042) and Fundamental Research Funds for the Central Universities China (No.17CX02003A).

The Orbital Angular Momentum Modes Supporting Fibers Based on the Photonic Crystal Fiber Structure

Directory of Open Access Journals (Sweden)

Hu Zhang

2017-10-01

Full Text Available The orbital angular momentum (OAM of light can be another physical dimension that we exploit to make multiplexing in the spatial domain. The design of the OAM mode supporting fiber attracts many attentions in the field of the space division multiplexing (SDM system. This paper reviews the recent progresses in photonic crystal fiber (PCF supporting OAM modes, and summarizes why a PCF structure can be used to support stable OAM transmission modes. The emphasis is on the circular PCFs, which possess many excellent features of transmission performance, such as good-quality OAM modes, enough separation of the effective indices, low confinement loss, flat dispersion, a large effective area, and a low nonlinear coefficient. We also compare the transmission properties between the circular PCF and the ring core fiber, as well as the properties between the OAM EDFA based on circular PCF and the OAM EDFA based on the ring core fiber. At last, the challenges and prospects of OAM fibers based on the PCF structure are also discussed.

Dust-cyclotron and dust-lower-hybrid modes in self-gravitating ...

Indian Academy of Sciences (India)

cantly modifies the dispersion properties of these two electrostatic modes. The implications of these results to some space and astrophysical dusty plasma systems, especially to planetary ring-systems and cometary tails, are briefly mentioned. Keywords. Dusty plasmas; dust-cyclotron waves; dust-lower-hybrid waves.

Sequence-length variation of mtDNA HVS-I C-stretch in Chinese ethnic groups.

Science.gov (United States)

Chen, Feng; Dang, Yong-hui; Yan, Chun-xia; Liu, Yan-ling; Deng, Ya-jun; Fulton, David J R; Chen, Teng

2009-10-01

The purpose of this study was to investigate mitochondrial DNA (mtDNA) hypervariable segment-I (HVS-I) C-stretch variations and explore the significance of these variations in forensic and population genetics studies. The C-stretch sequence variation was studied in 919 unrelated individuals from 8 Chinese ethnic groups using both direct and clone sequencing approaches. Thirty eight C-stretch haplotypes were identified, and some novel and population specific haplotypes were also detected. The C-stretch genetic diversity (GD) values were relatively high, and probability (P) values were low. Additionally, C-stretch length heteroplasmy was observed in approximately 9% of individuals studied. There was a significant correlation (r=-0.961, Ppopulations. The results from the Fst and dA genetic distance matrix, neighbor-joining tree, and principal component map also suggest that C-stretch could be used as a reliable genetic marker in population genetics.

Natural Frequencies and Mode Shapes of Statically Deformed Inclined Risers

KAUST Repository

Alfosail, Feras

2016-10-15

We investigate numerically the linear vibrations of inclined risers using the Galerkin approach. The riser is modeled as an Euler-Bernoulli beam accounting for the nonlinear mid-plane stretching and self-weight. After solving for the initial deflection of the riser due to self-weight, we use a Galerkin expansion employing 15 axially loaded beam mode shapes to solve the eigenvalue problem of the riser around the static equilibrium configuration. This yields the riser natural frequencies and corresponding exact mode shapes for various values of inclination angles and tension. The obtained results are validated against a boundary-layer analytical solution and are found to be in good agreement. This constitutes a basis to study the nonlinear forced vibrations of inclined risers.

Theoretical examination of the slot channel waveguide configured in a cylindrically symmetric dielectric ring profile

Science.gov (United States)

Gauthier, Robert C.; Alzahrani, Mohammed A.; Jafari, Seyed Hamed

2014-10-01

It has recently been experimentally demonstrated that slot channel waveguides, configured in cylindrical space, can support high azimuthal order modes similar to whispering-gallery modes. This paper presents a mode solver based on Maxwell's vector wave equation for the electric field cast into an eigenvalue problem using a Fourier-Bessel basis function space. The modal frequencies and field profiles of the high azimuthal order slot-channel-whispering-gallery (SCWG) modes are computed for a set of nanometer spaced silicon rings supported by oxide. The computations show, that in addition to the traditionally observed, lowest order mode, the structure may support higher order SCWG modes. We complete the analysis by computing structures response as an ambient medium index of refraction sensor which achieves over 400 nm per RIU sensitivity.

Mechanical stretching stimulates collagen synthesis via down-regulating SO2/AAT1 pathway

Science.gov (United States)

Liu, Jia; Yu, Wen; Liu, Yan; Chen, Selena; Huang, Yaqian; Li, Xiaohui; Liu, Cuiping; Zhang, Yanqiu; Li, Zhenzhen; Du, Jie; Tang, Chaoshu; Du, Junbao; Jin, Hongfang

2016-01-01

The aim of the study was to investigate the role of endogenous sulfur dioxide (SO2)/ aspartate aminotransferase 1 (AAT1) pathway in stretch-induced excessive collagen expression and its mechanism. The mechanical stretch downregulated SO2/AAT1 pathway and increased collagen I and III protein expression. Importantly, AAT1 overexpression blocked the increase in collagen I and III expression, transforming growth factor-β1 (TGF- β1) expression and phosphorylation of Smad2/3 induced by stretch, but AAT1 knockdown mimicked the increase in collagen I and III expression, TGF- β1 expression and phosphorylation of Smad2/3 induced by stretch. Mechanistically, SB431542, a TGF-β1/Smad2/3 inhibitor, eliminated excessive collagen I and III accumulation induced by AAT1 knockdown, stretch or stretch plus AAT1 knockdown. In a rat model of high pulmonary blood flow-induced pulmonary vascular collagen accumulation, AAT1 expression and SO2 content in lung tissues of rat were reduced in shunt rats with high pulmonary blood flow. Supplement of SO2 derivatives inhibited activation of TGF- β1/Smad2/3 pathway and alleviated the excessive collagen accumulation in lung tissues of shunt rats. The results suggested that deficiency of endogenous SO2/AAT1 pathway mediated mechanical stretch-stimulated abnormal collagen accumulation via TGF-β1/Smad2/3 pathway. PMID:26880260

DNA analysis by single molecule stretching in nanofluidic biochips

DEFF Research Database (Denmark)

Abad, E.; Juarros, A.; Retolaza, A.

2011-01-01

Imprint Lithography (NIL) technology combined with a conventional anodic bonding of the silicon base and Pyrex cover. Using this chip, we have performed single molecule imaging on a bench-top fluorescent microscope system. Lambda phage DNA was used as a model sample to characterize the chip. Single molecules of λ-DNA......Stretching single DNA molecules by confinement in nanofluidic channels has attracted a great interest during the last few years as a DNA analysis tool. We have designed and fabricated a sealed micro/nanofluidic device for DNA stretching applications, based on the use of the high throughput Nano...... stained with the fluorescent dye YOYO-1 were stretched in the nanochannel array and the experimental results were analysed to determine the extension factor of the DNA in the chip and the geometrical average of the nanochannel inner diameter. The determination of the extension ratio of the chip provides...

Effect of acute stretch injury on action potential and network activity of rat neocortical neurons in culture.

Science.gov (United States)

Magou, George C; Pfister, Bryan J; Berlin, Joshua R

2015-10-22

The basis for acute seizures following traumatic brain injury (TBI) remains unclear. Animal models of TBI have revealed acute hyperexcitablility in cortical neurons that could underlie seizure activity, but studying initiating events causing hyperexcitability is difficult in these models. In vitro models of stretch injury with cultured cortical neurons, a surrogate for TBI, allow facile investigation of cellular changes after injury but they have only demonstrated post-injury hypoexcitability. The goal of this study was to determine if neuronal hyperexcitability could be triggered by in vitro stretch injury. Controlled uniaxial stretch injury was delivered to a spatially delimited region of a spontaneously active network of cultured rat cortical neurons, yielding a region of stretch-injured neurons and adjacent regions of non-stretched neurons that did not directly experience stretch injury. Spontaneous electrical activity was measured in non-stretched and stretch-injured neurons, and in control neuronal networks not subjected to stretch injury. Non-stretched neurons in stretch-injured cultures displayed a three-fold increase in action potential firing rate and bursting activity 30-60 min post-injury. Stretch-injured neurons, however, displayed dramatically lower rates of action potential firing and bursting. These results demonstrate that acute hyperexcitability can be observed in non-stretched neurons located in regions adjacent to the site of stretch injury, consistent with reports that seizure activity can arise from regions surrounding the site of localized brain injury. Thus, this in vitro procedure for localized neuronal stretch injury may provide a model to study the earliest cellular changes in neuronal function associated with acute post-traumatic seizures. Copyright © 2015. Published by Elsevier B.V.

Use of the Halbach perturbation theory for the multipole design of the ALS storage ring sextupole

Energy Technology Data Exchange (ETDEWEB)

Marks, S. [Lawrence Berkeley Lab., CA (United States)

1995-02-01

The Advanced Light Source (ALS) storage ring sextupole is a unique multi-purpose magnet. It is designed to operate in the primary or sextupole mode and in three auxiliary trim modes: horizontal steering, vertical steering, and skew quadrupole. Klaus Halbach developed a perturbation theory for iron-dominated magnets which provides the basis for this design. Many magnet designers, certainly those who have been exposed to Klaus, are familiar with this theory and have used it for such things as evaluating the effect of assembly alignment errors. The ALS sextupole design process was somewhat novel in its use of the perturbation theory to design essential features of the magnet. In particular, the steering and skew quadrupole functions are produced by violating sextupole symmetry and are thus perturbations of the normal sextupole excitation. The magnet was designed such that all four modes are decoupled and can be excited independently. This paper discusses the use of Halbach`s perturbation theory to design the trim functions and to evaluate the primary asymmetry in the sextupole mode, namely, a gap in the return yoke to accommodate the vacuum chamber. Prototype testing verified all operating modes of the magnet and confirmed the expected performance from calculations based upon the Halbach perturbation theory. A total of 48 sextupole magnets of this design are now installed and operating successfully in the ALS storage ring.

The static actuation of dielectric elastomer actuators: how does pre-stretch improve actuation?

International Nuclear Information System (INIS)

Kofod, Guggi

2008-01-01

It has previously been shown that providing dielectric elastomer actuators with a level of pre-stretch can improve properties such as breakdown strength, actuation strain and efficiency. The actuation in such actuators depends on an interplay between the highly nonlinear hyperelastic stress-strain behaviour with the electrostatic Maxwell's stress; however, the direct effects of pre-stretch on the electromechanical coupling have still not been investigated in detail. We compare several experimental results found in the literature on the hyperelastic parameters of the Ogden model for the commonly used material VHB 4910, and introduce a more detailed and thus more accurate fit to a previous uniaxial stress-strain experiment. Electrostatic actuation models for a pure shear cuboid dielectric elastomer actuator with pre-stretch are introduced, for both intensive and extensive variables. For both intensive and extensive variables the constant strain (blocked stress or force) as well as the actuation strain is presented. It is shown how in the particular case of isotropic amorphous elastomers the pre-stretch does not affect the electromechanical coupling directly, and that the enhancement in actuation strain due to pre-stretch occurs through the alteration of the geometrical dimensions of the actuator. Also, the presence of the optimum load is explained as being due to the plateau region in the force-stretch curve, and it is shown that pre-stretch is not able to affect its position. Finally, it is shown how the simplified Ogden fit leads to entirely different conclusions for actuation strain in terms of extensive variables as does the detailed fit, emphasizing the importance of employing accurate hyperelastic models for the stress-stretch behaviour of the elastomer.

Acute effect of different stretching methods on flexibility and jumping performance in competitive artistic gymnasts.

Science.gov (United States)

Dallas, G; Smirniotou, A; Tsiganos, G; Tsopani, D; Di Cagno, A; Tsolakis, Ch

2014-12-01

The purpose of this study was to investigate the acute effects of 3 different warm up methods of stretching (static, proprioceptive neuromuscular facilitation, and stretching exercises on a Vibration platform) on flexibility and legs power-jumping performance in competitive artistic gymnasts. Eighteen competitive artistic gymnasts were recruited to participate in this study. Subjects were exposed to each of 3 experimental stretching conditions: static stretching (SS), proprioceptive neuromuscular facilitation stretching (PNF), and stretching exercises on a Vibration platform (S+V). Flexibility assessed with sit and reach test (S & R) and jumping performance with squat jump (SJ) and counter movement jump (CMJ) and were measured before, immediately after and 15 min after the interventions. Significant differences were observed for flexibility after all stretching conditions for S+V (+1.1%), SS (+5.7%) and PNF (+6.8%) (P=0.000), which remained higher 15 min after interventions (S+V (1.1%), SS (5.3%) and PNF (5.5%), respectively (P=0.000). PNF stretching increased flexibility in competitive gymnasts, while S+V maintained jumping performance when both methods were used as part of a warm-up procedure.