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1

Explosives detection by nuclear quadrupole resonance (NQR)  

NASA Astrophysics Data System (ADS)

Pure nuclear quadrupole resonance (NQR) of 14N nuclei is quite promising as a method for detecting explosives such as RDX and contraband narcotics such as cocaine and heroin in quantities of interest. Pure NQR is conducted without an external applied magnetic field, so potential concerns about damage to magnetically encoded data or exposure of personnel to large magnetic fields are not relevant. Because NQR frequencies of different compounds are quite distinct, we do not encounter false alarms from the NQR signals of other benign materials. We have constructed a laboratory prototype NQR explosives detector which interrogates a volume of 300 liters (10 ft3). This paper presents abbreviated results from a demonstration of the laboratory prototype NQR explosives detector conducted at the Federal Aviation Administration Technical Center in May 1994 on RDX-based explosives.

Garroway, Allen N.; Buess, M. L.; Yesinowski, J. P.; Miller, J. B.; Krauss, Ronald A.

1994-10-01

2

Frequency selective detection of nuclear quadrupole resonance (NQR) spin echoes  

NASA Astrophysics Data System (ADS)

Nuclear Quadrupole Resonance (NQR) is a radio frequency (RF) technique that can be used to detect the presence of quadrupolar nuclei, such as the 14N nucleus prevalent in many explosives and narcotics. The technique has been hampered by low signal-to-noise ratios and is further aggravated by the presence of RF interference (RFI). To ensure accurate detection, proposed detectors should exploit the rich form of the NQR signal. Furthermore, the detectors should also be robust to any remaining residual interference, left after suitable RFI mitigation has been employed. In this paper, we propose a new NQR data model, particularly for the realistic case where multiple pulse sequences are used to generate trains of spin echoes. Furthermore, we refine two recently proposed approximative maximum likelihood (AML) detectors, enabling the algorithm to optimally exploit the data model of the entire echo train and also incorporate knowledge of the temperature dependent spin-echo decay time. The AML-based detectors ensure accurate detection and robustness against residual RFI, even when the temperature of the sample is not precisely known, by exploiting the dependencies of the NQR resonant lines on temperature. Further robustness against residual interference is gained as the proposed detector is frequency selective; exploiting only those regions of the spectrum where the NQR signal is expected. Extensive numerical evaluations based on both simulated and measured NQR data indicate that the proposed Frequency selective Echo Train AML (FETAML) detector offers a significant improvement as compared to other existing detectors.

Somasundaram, Samuel D.; Jakobsson, Andreas; Smith, John A. S.; Althoefer, Kaspar A.

2006-06-01

3

A general numerical analysis of time-domain NQR experiments.  

PubMed

We introduce a general numerical approach for solving the Liouville equation of an isolated quadrupolar nuclide that can be used to analyze the unitary dynamics of time-domain NQR experiments. A numerical treatment is necessitated by the dimensionality of the Liouville space, which precludes analytical, closed form solutions for I > 3/2. Accurate simulations of experimental nutation curves, forbidden transition intensities, powder and single crystal spectra, and off-resonance irradiation dynamics can be computed with this method. We also examine the validity of perturbative approximations where the signal intensity of a transition is proportional to the transition moment between the eigenstates of the system, thus providing a simple basis for determining selection rules. Our method allows us to calculate spectra for all values of the asymmetry parameter, eta, and sample orientations relative to the coil axis. We conclude by demonstrating the methodology for calculating the response of the quadrupole system to amplitude- and frequency-modulated pulses. PMID:16996760

Harel, Elad; Cho, Herman

2006-12-01

4

Multi-Frequency Resonances in Pure Multiple-Pulse NQR  

NASA Astrophysics Data System (ADS)

We have observed multi-frequency resonances in a system with a spin 3/2 irradiated simultaneously by a multiple-pulse radiofrequency sequence and a low frequency field swept in the range 0 ÷ 80 kHz. The theoretical description of the effect is presented using both the rotating frame approximation and the Floquet theory. Both approaches give indentical results at the calculation of the resonance frequencies, transition probabilities and shifts of resonance frequency. The calculated magnetization vs. the frequency of the low-frequency field agrees with the obtained experimental data.

Furman, G. B.; Kibrik, G. E.; Polyakov, A. Yu.

2004-12-01

5

Numerical simulation of NQR/NMR: Applications in quantum computing.  

PubMed

A numerical simulation program able to simulate nuclear quadrupole resonance (NQR) as well as nuclear magnetic resonance (NMR) experiments is presented, written using the Mathematica package, aiming especially applications in quantum computing. The program makes use of the interaction picture to compute the effect of the relevant nuclear spin interactions, without any assumption about the relative size of each interaction. This makes the program flexible and versatile, being useful in a wide range of experimental situations, going from NQR (at zero or under small applied magnetic field) to high-field NMR experiments. Some conditions specifically required for quantum computing applications are implemented in the program, such as the possibility of use of elliptically polarized radiofrequency and the inclusion of first- and second-order terms in the average Hamiltonian expansion. A number of examples dealing with simple NQR and quadrupole-perturbed NMR experiments are presented, along with the proposal of experiments to create quantum pseudopure states and logic gates using NQR. The program and the various application examples are freely available through the link http://www.profanderson.net/files/nmr_nqr.php. PMID:21324720

Possa, Denimar; Gaudio, Anderson C; Freitas, Jair C C

2011-04-01

6

Unconventional Pairing States in Heavy-Fermion Superconductors Studied by the NQR/NMR Experiments  

NASA Astrophysics Data System (ADS)

We review the studies on the unconventional superconducting pairing states and their relevance with magnetism in the f-electron derived heavy-fermion (HF) systems by means of nuclear-magnetic-resonance (NMR) and nuclear-quadrupole-resonance (NQR). These studies have unraveled a rich variety of the phenomena in the ground state of HF systems. In this article, we address an intimate relationship between the onset of strong-coupling superconductivity (SC) and critical magnetic fluctuations emerging in the vicinity of quantum critical point (QCP). Furthermore, we focus on the novel phase diagram of the HF antiferromagnet CeRhIn5 under pressure which is characterized by the tetracritical point separating the pure antiferromagnetism (AFM) phase, the AFM+SC uniformly coexisting phase, and the paramagnetic SC phase. A comparison is also presented on the AFM+SC uniformly coexisting phase in high-temperature superconductors as the function of carrier doping. As a consequence, we raise a question; Do we need a bosonic glue to pair electrons in these superconductors? Finally, we address a possible origin of the novel SC in the itinerant ferromagnet UGe2, which is mediated by ferromagnetic spin-density fluctuations relevant with the first-order transition inside the ferromagnetic states.

Kitaoka, Yoshio; Mukuda, Hidekazu; Yashima, Mitsuharu; Harada, Atsushi

2007-05-01

7

Two-dimensional NQR using ultra-broadband electronics.  

PubMed

We have recently developed an ultra-broadband instrument that can effectively excite and detect NMR and NQR signals over a wide frequency range. Our current system operates between 100 kHz and 3.2 MHz using an un-tuned sample coil. The major benefits of this instrument compared to conventional NQR/NMR systems include increased robustness, ease of use (in particular for multi-frequency experiments), and elimination of the need for tuning adjustments in the hardware. Here we describe its use for performing two-dimensional (2D) scans, which allow improved interpretation of complex NQR spectra by detecting the connected resonances. Our method relies on population transfers between the three energy levels of spin-1 nuclei (such as (14)N) by using multi-frequency excitation and a single RF coil. Experimental results on pure samples and mixtures are also presented. PMID:24495675

Mandal, S; Song, Y-Q

2014-03-01

8

NQR investigation and characterization of cocrystals and crystal polymorphs  

NASA Astrophysics Data System (ADS)

The application of 14N NQR to the study of cocrystals and crystal polymorphs is reviewed. In ferroelectric and antiferroelectric organic cocrystals 14N NQR is used to determine proton position in an N-H...O hydrogen bond and proton displacement below TC. In cocrystal isonicitinamide - oxalic acid (2:1) 14N NQR is used to distinguish between two polymorphs and to determine the type of the hydrogen bond (N-...H-O). The difference in the 14N NQR spectra of cocrystal formers and cocrystal is investigated in case of carbamazepine, saccharin and carbamazepine - saccharin (1:1). The experimental resolution allows an unambiguous distinction between the 14N NQR spectrum of the cocrystal and the 14N NQR spectra of the cocrystal formers. The possibility of application of NQR and double resonance for the determination of the inhomogeneity of the sample and for the study of the life time of an unstable polymorph is discussed.

Seliger, Janez; Žagar, Veselko; Asaji, Tetsuo

2013-05-01

9

Optimised NQR pulse technique for the effective detection of Heroin Base.  

PubMed

The nuclear quadrupole resonance (NQR) method has been applied to Heroin Base (HB) to find an optimised multi-pulse technique for effective detection of HB. Experimental results of applying the proposed spin-locking multi-pulse (SLMP) technique to nitrogen-14 NQR in this sample are presented and convincingly demonstrate as a path towards efficient detection. A detection using a sequence of this character could be achieved over real-world scan volumes for screening of goods. All experiments were carried out at room temperature. PMID:18342493

Rudakov, T N; Hayes, P A; Flexman, J H

2008-03-01

10

Nuclear magnetic resonance experiments with dc SQUID amplifiers  

SciTech Connect

The development and fabrication of dc SQUIDs (Superconducting QUantum Interference Devices) with Nb/Al{sub 2}O{sub 3}/Nb Josephson junctions is described. A theory of the dc SQUID as a radio-frequency amplifier is presented, with an optimization strategy that accounts for the loading and noise contributions of the postamplifier and maximizes the signal-to-noise ratio of the total system. The high sensitivity of the dc SQUID is extended to high field NMR. A dc SQUID is used as a tuned radio-frequency amplifier to detect pulsed nuclear magnetic resonance at 32 MHz from a metal film in a 3.5 Tesla static field. A total system noise temperature of 11 K has been achieved, at a bath temperature of 4.2 K. The minimum number of nuclear Bohr magnetons observable from a free precession signal after a single pulse is about 2 {times} 10{sup 17} in a bandwidth of 25 kHz. In a separate experiment, a dc SQUID is used as a rf amplifier in a NQR experiment to observe a new resonance response mechanism. The net electric polarization of a NaClO{sub 3} crystal due to the precessing electric quadrupole moments of the Cl nuclei is detected at 30 MHz. The sensitivity of NMR and NQR spectrometers using dc SQUID amplifiers is compared to the sensitivity of spectrometers using conventional rf amplifiers. A SQUID-based spectrometer has a voltage sensitivity which is comparable to the best achieved by a FET-based spectrometer, at these temperatures and operating frequencies.

Heaney, M.B. (California Univ., Berkeley, CA (USA). Dept. of Physics Lawrence Berkeley Lab., CA (USA))

1990-11-01

11

Application of the spherical tensor method for Two-Frequency pure NQR of spin I =1 nuclei  

Microsoft Academic Search

The results of a theoretical investigation of two-frequency excitation in pure nuclear quadrupole resonance (NQR) for a spinI=1 nucleus with a nonaxial elecric field gradient are presented. The multipole tensor operator technique is used for the treatment\\u000a of the one- and two-frequency pulse excitations. The results are applied to the characterization of the two-frequency signal\\u000a of nitrogen14N nuclei. The experiments

G. V. Mozjoukhine

2002-01-01

12

Stark effect of 14N NQR in single crystals of ferroelectric NaNO2  

Microsoft Academic Search

The effects of the external electric field on 14N nuclear quadrupole resonance (NQR) have been investigated in the ferroelectric phase of sodium nitrite (NaNO2) single crystals with either the single domain or the multidomain structure. NQR measurements of two resonance lines of n and n were made at 77 K under the external electric field up to 25 kV\\/cm. The

S. H. Choh; Y. J. Park; H. K. Kim; Y. M. Chang

1989-01-01

13

The two-frequency nuclear quadrupole resonance for explosives detection  

Microsoft Academic Search

The two-frequency nuclear quadrupole resonance (NQR) of14N nuclei is described for purposes of explosives detection. Two applications are known: two-frequency NQR for increasing the\\u000a signal intensity, two-frequency NQR for improved reliability of explosives detection. The two-frequency experiments were carried\\u000a out in hexahydro-1,3,5-trinitro-s-triazine C3H6N6O6 and sodium nitrite NaNO2 as a substitute for octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocycine C4H8N8O8. The two-frequency sequences for NQR are proposed

G. V. Mozjoukhine

2000-01-01

14

Microstrip resonators for electron paramagnetic resonance experiments  

NASA Astrophysics Data System (ADS)

In this article we evaluate the performance of an electron paramagnetic resonance (EPR) setup using a microstrip resonator (MR). The design and characterization of the resonator are described and parameters of importance to EPR and spin manipulation are examined, including cavity quality factor, filling factor, and microwave magnetic field in the sample region. Simulated microwave electric and magnetic field distributions in the resonator are also presented and compared with qualitative measurements of the field distribution obtained by a perturbation technique. Based on EPR experiments carried out with a standard marker at room temperature and a MR resonating at 8.17 GHz, the minimum detectable number of spins was found to be 5×1010 spins/GHz1/2 despite the low MR unloaded quality factor Q0=60. The functionality of the EPR setup was further evaluated at low temperature, where the spin resonance of Cr dopants present in a GaAs wafer was detected at 2.3 K. The design and characterization of a more versatile MR targeting an improved EPR sensitivity and featuring an integrated biasing circuit for the study of samples that require an electrical contact are also discussed.

Torrezan, A. C.; Mayer Alegre, T. P.; Medeiros-Ribeiro, G.

2009-07-01

15

NQR spin-echo methods at very low temperatures  

Microsoft Academic Search

Pulsed methods may be successfully used in very low temperature NMR or NQR experiments provided good thermal anchoring of the sample is achieved. In order to reduce heating effects, it is advantageous to use rf pulses that are shorter than the standard magnetization tipping pulses used at higher temperatures. The present work describes the use of short nonstandard rf pulses

I. P. Goudemond; J. M. Keartland; M. J. R. Hoch

1991-01-01

16

Investigation of Structural Information for Boron - Solids and Aluminates via NMR and Nqr Studies.  

NASA Astrophysics Data System (ADS)

Nuclear Magnetic Resonance (NMR) has been prevailed in investigating local structures for a variety of materials: various oxide glasses, zeolites, superconductors, etc. Since glasses have short range ordered structures instead of long range ordered ones in crystals, NMR is usually more useful in determining the local structures for many glasses than any other detection methods do. Along with NMR, Nuclear Quadrupole Resonance (NQR) has become important recently for obtaining structural information from such glasses. The NQR studies prove in this thesis that they provide more accurate structural information than the NMR studies have done. This study presents boron and aluminum NMR, and NQR studies for some borate glasses and compounds, icosahedral boron-rich solids, some crystalline aluminosilicates. Various borates were employed to acquire structural information as well as to determine the quadrupole parameters (the quadrupole coupling constant Q_{cc } and the asymmetry parameter eta ) using NQR under a guidance of NMR or vice versa. By NQR a previously unknown boron site was observed for vitreous Li_2OcdotB _2O_3. The boron site had an intermediate Q_{cc } value in-between the reported value ranges of Q_{cc} for BO _3 and BO_4 sites, and was concluded to be a previously unknown BO _4 site. The NMR and NQR studies were performed on some icosachedral boron-rich solids: alpha -rhombohedral boron (B_{12}), beta-boron (B_{105 }) and boron carbide (B_{12 }C_3). Strong NQR responses were obtained from boron atoms in the C-B-C chains along with several other NQR responses from boron atoms in the icosahedral. These NQR results were consistent with the NMR studies by Silver and Bray, and those by Hynes and Alexander. Also, for the icosahedral boron-rich solids, the ^{11}B NMR studies revealed the possibility of chemical shifts due to two distinct boron sites in the icosahedra. A very interesting phenomenon was found from an isotopic change of boron nuclei (substitution of ^{10}B for ^{11}B) in boron carbide: in ^{11}B high field (7.05 Tesla) NMR spectra, two distinct peaks separated by some chemical shifts for unenriched boron carbide (B _{12}C_3) became a single peak for ^{10} B enriched boron carbide (90.61 at.% of ^{10}B). Three different forms of crystalline aluminosilicate (Al_2SiO_5) were studied by NQR. The NQR study yielded more accurate values of the quadrupole parameters for ^ {27}Al than the previous NMR single crystal study did.

Lee, Donghoon

17

Measurement of in-situ stress in salt and rock using NQR techniques  

SciTech Connect

A discussion of how stress and strain affect the quantities which can be measured in an NQR experiment shows that, for stresses of the magnitude to be expected at depths up to about 10,000 feet, quadrupole coupling constants will fall in the range of 1 to 10 kHz for both the sodium and chloride ions in NaCl. The most promising system involves pulsed nuclear double resonance detection; and alterative is to observe the quadrupolar splitting of the NMR signal. Choices to be made in the measurement and mapping techniques are discussed. The well-known perturbation of the homogenous stress field in the neighborhood of a borehole is shown to be advantageous from the point of view of obtaining directional information on the stress. Construction and operation of a borehole stress sensor are considered. The NQR technique seems feasible for measuring the magnitude and direction of underground stress with a resolution of about 25 psi, or 2.5% at 1000 psi. Downhole instrumentation suitable for in-situ determinations of stress appears within the state of the art. Additional tasks required on the project are identified.

Schempp, E.; Hirschfeld, T.; Klainer, S.

1980-12-01

18

Nuclear quadrupole resonance detection of explosives: an overview  

NASA Astrophysics Data System (ADS)

Nuclear Quadrupole Resonance (NQR) is a spectroscopic technique closely related to Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI). These techniques, and NQR in particular, induce signals from the material being interrogated that are very specific to the chemical and physical structure of the material, but are relatively insensitive to the physical form of the material. NQR explosives detection exploits this specificity to detect explosive materials, in contrast to other well known techniques that are designed to detect explosive devices. The past two decades have seen a large research and development effort in NQR explosives detection in the United States aimed at transportation security and military applications. Here, I will briefly describe the physical basis for NQR before discussing NQR developments over the past decade, with particular emphasis on landmine detection and the use of NQR in combating IED's. Potential future directions for NQR research and development are discussed.

Miller, Joel B.

2011-05-01

19

Cooperative Phenomenon of Ferromagnetism and Unconventional Superconductivity in UGe2: A 73Ge-NQR Study under Pressure  

Microsoft Academic Search

We report on a cooperative phenomenon of ferromagnetism and unconventional superconductivity (SC) in UGe2 through the measurements of 73Ge nuclear-quadrupole-resonance (NQR) under pressure (P). The NQR spectra evidenced phase separation into ferromagnetic and paramagnetic phases in the vicinity of Pc˜ 1.5 GPa, pointing to a first-order transition. The measurements of nuclear-spin-lattice-relaxation-rate 1\\/T1 revealed that SC emerges under the background of

Atsushi Harada; Shinji Kawasaki; Hisashi Kotegawa; Yoshio Kitaoka; Yoshinori Haga; Etsuji Yamamoto; Yoshichika Onuki; K. M. Itoh; Eugene Haller; Hisatomo Harima

2005-01-01

20

Cooperative Phenomenon of Ferromagnetism and Unconventional Superconductivity in UGe2: A 73Ge-NQR Study under Pressure  

NASA Astrophysics Data System (ADS)

We report on a cooperative phenomenon of ferromagnetism and unconventional superconductivity (SC) in UGe2 through the measurements of 73Ge nuclear-quadrupole-resonance (NQR) under pressure (P). The NQR spectra evidenced phase separation into ferromagnetic and paramagnetic phases in the vicinity of Pc˜ 1.5 GPa, pointing to a first-order transition. The measurements of nuclear-spin-lattice-relaxation-rate 1/T1 revealed that SC emerges under the background of ferromagnetism, but not of the paramagnetic phase.

Harada, A.; Kawasaki, S.; Kotegawa, H.; Kitaoka, Y.; Haga, Y.; Yamamoto, E.; ?nuki, Y.; Itoh, K. M.; Haller, E. E.; Harima, H.

2005-10-01

21

New technologies: nuclear quadrupole resonance as an explosive and narcotic detection technique  

Microsoft Academic Search

Possibilities of detecting nuclear quadrupole resonance (NQR) signals in explosives and drugs are considered. Direct and indirect NQR techniques for searching substances are described and the potentialities of various experimental methods are compared.

Vadim S Grechishkin; Nikolai Ya Sinyavskii

1997-01-01

22

FPGA based pulsed NQR spectrometer  

NASA Astrophysics Data System (ADS)

An NQR spectrometer for the frequency range of 1 MHz to 5 MHZ has been designed constructed and tested using an FPGA module. Consisting of four modules viz. Transmitter, Probe, Receiver and computer controlled (FPGA & Software) module containing frequency synthesizer, pulse programmer, mixer, detection and display, the instrument is capable of exciting nuclei with a power of 200W and can detect signal of a few microvolts in strength. 14N signal from NaNO2 has been observed with the expected signal strength.

Hemnani, Preeti; Rajarajan, A. K.; Joshi, Gopal; Motiwala, Paresh D.; Ravindranath, S. V. G.

2014-04-01

23

35Cl NQR of an organic ferroelectric phenazine chloranilic acid co-crystal  

NASA Astrophysics Data System (ADS)

A ferroelectric transition of phenazine (Phz) chloranilic acid (H 2ca) co-crystal was studied by 35Cl nuclear quadrupole resonance (NQR). The single NQR line observed at 36.689 MHz at 295 K, split into a doublet below the ferroelectric transition temperature Tc=253 K in accord with the inversion-symmetry breaking at the H 2ca molecular center in the crystal. The continuous variation of the splitting-width through Tc suggests a second-order nature of this phase transition. The NQR frequency is consistent with the crystal structure in which the two acid hydrogen atoms of H 2ca remain as attached to the quinone molecules. The spin-lattice relaxation time T1 showed a decrease with decreasing temperature in the ferroelectric phase. This suggests the existence of a fast motion of nearby atomic group, which is a cause of electric field gradient fluctuation.

Asaji, Tetsuo; Gotoh, Kazuma; Watanabe, Jun

2006-06-01

24

INSTRUMENTS AND METHODS OF INVESTIGATION: New technologies: nuclear quadrupole resonance as an explosive and narcotic detection technique  

NASA Astrophysics Data System (ADS)

Possibilities of detecting nuclear quadrupole resonance (NQR) signals in explosives and drugs are considered. Direct and indirect NQR techniques for searching substances are described and the potentialities of various experimental methods are compared.

Grechishkin, Vadim S.; Sinyavskii, Nikolai Ya

1997-04-01

25

14N NQR in the tetrazole family  

NASA Astrophysics Data System (ADS)

14N NQR frequencies and spin-lattice relaxation times were measured in technologically important 5-aminotetrazole and 5-aminotetrazole monohydrate at different temperatures between 77 K and 300 K. Five NQR triplets ?+, ?- and ?0 were found for the five inequivalent nitrogen atoms in each compound between 0.7 MHz and 4 MHz. Carr-Purcell based multipulse sequences were used to accumulate quadrupole echo signals before the FFT analysis. Assignment of the frequencies to atomic positions was made and the results are analysed in relation to the molecular chemical bonds and possible H-bonds in the crystal structures. The new NQR frequencies are reasonably related to the previously published NQR spectrum of the third family member, 1H-tetrazole.

Pirnat, Janez; Lužnik, Janko; Jazbinšek, Vojko; Žagar, Veselko; Seliger, Janez; Klapötke, Thomas M.; Trontelj, Zvonko

2009-10-01

26

Pulsed Spin Locking in Spin-1 NQR: Broadening Mechanisms  

NASA Astrophysics Data System (ADS)

Nuclear Quadrupole Resonance (NQR) is a branch of magnetic resonance physics that allows for the detection of spin I > 1/2 nuclei in crystalline and semi-crystalline materials. Through the application of a resonant radio frequency (rf) pulse, the nuclei's response is to create an oscillating magnetic moment at a frequency unique to the target substance. This creates the NQR signal, which is typically weak and rapidly decaying. The decay is due to the various line broadening mechanisms, the relative strengths of which are functions of the specific material, in addition to thermal relaxation processes. Through the application of a series of rf pulses the broadening mechanisms can be refocused, narrowing the linewidth and extending the signal in time. Three line broadening mechanisms are investigated to explain the NQR signal's linewidth and behavior. The first, electric field gradient (EFG) inhomogeneity, is due to variations in the local electric environment among the target nuclei, for instance from crystal imperfections. While EFG inhomogeneity can vary between samples of the same chemical composition and structure, the other broadening mechanisms of homonuclear and heteronuclear dipolar coupling are specific to this composition and structure. Simple analytical models are developed that explain the NQR signal response to pulse sequences by accounting for the behavior of each broadening mechanism. After a general theoretical introduction, a model of pairs of spin-1 nuclei is investigated, and the refocusing behaviors of EFG and homonuclear dipolar coupling are analyzed. This reveals the conditions where EFG is refocused but homonuclear dipolar coupling is not. In this case the resulting signal shows a rapid decay, the rate of which becomes a measure of interatomic distances. This occurs even in the more complex case of a powder sample with its many randomly oriented crystallites, under particular pulsing conditions. Many target NQR compounds are rich in hydrogen, and therefore might have a significant heteronuclear dipolar coupling component. To incorporate this, a second model is developed composed of two different nuclear species, one spin 1 the other spin 1/2, although the work can be extended to additional spin species. This model reveals that heteronuclear dipolar coupling for this system behaves just like EFG broadening under spin locking, and that the strong homonuclear response is still observable. The experimental results closely match theoretical predictions, and the conclusions greatly expand the number of target substances that are suitable for this measurement technique of homonuclear dipolar coupling. The combined results explain why certain pulse sequences perform better than others for substance detection: it is because of the relative strengths of the line broadening mechanisms. Therefore the ability to measure homonuclear dipolar coupling's contribution to the linewidth is useful not only for material characterization, but also for substance detection. By explaining the conditions that reveal homonuclear coupling, we make it possible to measure the relative broadening strengths, increasing the efficiency of NQR in these roles.

Malone, Michael W.

27

Broken Atomic Beam Resonance Experiment  

Microsoft Academic Search

Cesium atoms from a heated oven were passed through a bouncing box, ; where they suffered at least two collisions, between two six-pole deflecting ; magnets. The characteristic Ramsey separated oscillatory field resonance pattern ; was found corresponding to atomic transitions between the F =4, M = 0 and F = 3, ; M = 0 state. (W.D.M.);

Daniel Kleppner; Norman F. Ramsey; Paul Fjelstadt

1958-01-01

28

Radiative widths of resonances (experiments)  

SciTech Connect

After a hiatus of several years, this conference brings us considerable new data on resonance production in photon photon interactions. I will first discuss the contributions concerning the tensor, pseudoscalar and scalar mesons, then review the current status of the (c/ovr string/c /eta//sub c/) and finally summarize the exciting new results concerning the spin 1 mesons. 40 refs., 21 figs., 7 tabs.

Gidal, G.

1988-07-01

29

Pressure and temperature dependence of the chlorine NQR in caesium and sodium chlorates.  

PubMed

The (35)Cl nuclear quadrupole resonance (NQR) frequencies (nu(Q)) in caesium and sodium chlorates were measured as a function of temperature, from 77 to 300 K at different pressures up to 5.1 kbar, and the data were analysed to estimate the volume dependence of the electric field gradient (EFG), torsional frequency and also the contributions to the NQR frequency from static and dynamic effects. The variation of spin-lattice relaxation time with pressure at different temperatures was studied in the case of sodium chlorate and at room temperature in case of caesium chlorate. The pressure dependence of the spin-lattice relaxation time (T(1)) suggests that the relaxation is mainly due to the torsional motions. PMID:18324738

Ramesh, K P; Suresh, K S; Raghavendra Rao, C; Ramakrishna, J

2008-06-01

30

Undergraduate Electron-Spin-Resonance Experiment.  

ERIC Educational Resources Information Center

Describes the basic procedures for use of an electron-spin resonance spectrometer and potassium azide (KN3) in an experiment which extends from the phase of sample preparation (crystal growth, sample mounting, and orientation) through data taking to the stages of calculation and theoretical explanation. (Author/DS)

Willis, James S.

1980-01-01

31

NQR Line Broadening Due to Crystal Lattice Imperfections and Its Relationship to Shock Sensitivity  

NASA Astrophysics Data System (ADS)

The hydrodynamic hot spot model is used to explain the difference between shock sensitive and shock insensitive explosives. Among the major factors that influence the shock sensitivity of energetic compounds are the quality and particle size of the energetic crystals used to formulate the cast plastic bonded explosive. As do all energetic compounds, RDX and HMX exhibit internal crystal defects the magnitude and type of which depend on the manufacturing process used to synthesize and re-crystallize the energetic compound. Nuclear Quadrupole Resonance (NQR) spectroscopy was used to determine the crystal quality of RDX, HMX and CL-20 obtained from various manufacturers. The NQR experimental results are discussed. Cast plastic bonded explosives were made using the RDX and HMX obtained from the various manufacturers and subsequently subjected to the NOL large-scale gap test (LSGT). The results of the LSGT are discussed and correlated with the NQR results. A relationship between the crystal defect density and shock initiation pressure of the plastic bonded explosive is developed and discussed.

Caulder, S. M.; Buess, M. L.; Garroway, A. N.; Miller, P. J.

2004-07-01

32

Crystallization and preliminary analysis of the NqrA and NqrC subunits of the Na(+)-translocating NADH:ubiquinone oxidoreductase from Vibrio cholerae.  

PubMed

The Na(+)-translocating NADH:ubiquinone oxidoreductase (Na(+)-NQR) from Vibrio cholerae is a membrane protein complex consisting of six different subunits NqrA-NqrF. The major domains of the NqrA and NqrC subunits were heterologously expressed in Escherichia coli and crystallized. The structure of NqrA1-377 was solved in space groups C2221 and P21 by SAD phasing and molecular replacement at 1.9 and 2.1?Å resolution, respectively. NqrC devoid of the transmembrane helix was co-expressed with ApbE to insert the flavin mononucleotide group covalently attached to Thr225. The structure was determined by molecular replacement using apo-NqrC of Parabacteroides distasonis as search model at 1.8?Å resolution. PMID:25005105

Vohl, Georg; Nedielkov, Ruslan; Claussen, Björn; Casutt, Marco S; Vorburger, Thomas; Diederichs, Kay; Möller, Heiko M; Steuber, Julia; Fritz, Günter

2014-07-01

33

35Cl-NQR and DFT study of electronic structure of amlodipine and felodipine vascular-selective drugs from the dihydropyridine Ca ++ antagonists group  

NASA Astrophysics Data System (ADS)

Amlodipine (AM) and felodipine (FL) have been studied in solid state by the nuclear quadrupole resonance (NQR) and density functional theory (DFT). The results have shown that NQR data do not permit a differentiation between R and S enantiomers, which is a consequence of the symmetry of the 4-aryl ring, whereas they permit a differentiation between free bases and salts. The HOMO-LUMO gap is smaller for AM than for FL, which suggests smaller energy of excitation for AM. The absolute hardness, chemical potential and electrophilicity of both AM enantiomers are lower than the corresponding values for FL enantiomers, suggesting that AM should be more reactive than FL in unimolecular reactions.

Latosi?ska, J. N.; Latosi?ska, M.; Kasprzak, J.

2008-09-01

34

Radio-frequency tunable atomic magnetometer for detection of solid-state NQR  

NASA Astrophysics Data System (ADS)

We constructed a potassium atomic magnetometer which resonantly detects rf magnetic fields with subfemtotesla sensitivity. The resonance frequency is set by the Zeeman resonance of the potassium atoms in a static magnetic field applied to the magnetometer cell. Strong optical pumping of the potassium atoms into a stretched state reduces spin-exchange broadening of the Zeeman resonance, resulting in relatively small linewidth of about 200 Hz (half-width at half-maximum). The magnetometer was used to detect ^14N NQR signal from powdered ammonium nitrate at 423 kHz, with sensitivity an order of magnitude higher than with a conventional room temperature pickup coil with comparable geometry. The demonstrated sensitivity of 0.24 fT/Hz^1/2 can be improved by several means, including use of higher power lasers for pumping and probing. Our technique can potentially be used to develop a mobile, open-access NQR spectrometer for detection of nitrogen-containing solids of interest in security applications.

Lee, S.-K.; Sauer, K. L.; Seltzer, S. J.; Alem, O.; Romalis, M. V.

2007-06-01

35

Multiple-pulse NQR dynamics of spin systems with strong heteronuclear coupling  

NASA Astrophysics Data System (ADS)

The results are presented of a theoretical consideration of the nuclear quadrupole resonance (NQR) and spin—spin relaxation for a paramagnetic body containing nuclei of two different sorts coupled by the strong homonuclear and heteronuclear dipole—dipole interactions and influenced by an external multiple-pulse radiofrequency magnetic field acting only on nuclei of one sort. Kinetic equations were obtained giving the possibility of finding the time dependence of the magnetization of the body and the kinetic coefficients calculated as a function of the multiple-pulse field parameters. The possibilities of using the results in question for molecular structure and molecular dynamics investigations are briefly surveyed.

Furman, G. B.; Shaposhnikov, I. G.

1994-05-01

36

Correlation of far-infrared and nuclear quadrupole resonance studies in 1,3,5-tribromobenzene  

NASA Astrophysics Data System (ADS)

The torsional modes that contribute to the change in nuclear quadrupole resonance (NQR) frequencies with temperatures in 1,3,5-tribromobenzene are indentified by correlating the observed variation of 79Br NQR frequencies with temperature with the theoretical expectations using the low frequency vibrational modes obtained from the far-infrared (FIR) spectrum.

Venkatacharyulu, P.; Krishnamurthy, V.

1991-02-01

37

Interpretive Experiments: An Interpretive Experiment in Ion Cyclotron Resonance Spectroscopy.  

ERIC Educational Resources Information Center

Provides a discussion which is intended for chemistry college students on the ion cyclotron resonance (ICR) spectroscopy, the physical basis for ion cyclotron resonance, and the experimental methodology employed by ICR spectroscopists. (HM)

Burnier, R. C.; Freiser, B. S.

1979-01-01

38

Flow Excited Helmholtz Resonator - Theory and Experiments  

Microsoft Academic Search

Flow over the orifice of a Helmoltz resonator can result in a self excited resonance. The present research has focused on understanding this vortical-acoustic coupling by considering a simple control volume momentum analysis. A forcing term can then be identified, and considered in terms of a combined hydrodynamic-acoustic scaling. Direct measurements of the forcing were obtained using PIV for a

Scott Morris; Paul Slaboch; Ruolong Ma

2007-01-01

39

Nuclear quadrupole resonance study of hydrogen bonded solid materials.  

PubMed

Nuclear quadrupole resonance is presented as a method for the study of solid hydrogen bonded materials. NQR study of hydrogen bonds in ferroelectric and paraelectric KH2PO4, antiferroelectric and paraelectric squaric acid, ferroelectric croconic acid and antiferroelectric and paraelectric cocrystal 5'-dimethyl-2, 2'-bipyridine - chloranilic acid (1:1) are discussed in more details. A 14N NQR study of the strong short O-HKN hydrogen bond in two polymorphic forms of cocrystal isonicotinamide-oxalic acid (2:1) is presented as well. Various correlations between the NQR parameters and between the NQR and structural parameters have been observed. These correlations may be used to determine the proton position in a hydrogen bond and some other structural parameters from the NQR data. PMID:24062106

Seliger, Janez

2011-09-01

40

Narcotics and explosives detection by 14N pure nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

Pure nuclear quadrupole resonance (NQR) of 14N nuclei is quite promising as a method for detecting explosives such as RDX and contraband narcotics such as cocaine and heroin in quantities of interest. Pure NQR is conducted without an external applied magnetic field, so potential concerns about damage to magnetically encoded data or exposure of personnel to large magnetic fields are not relevant. Because NQR frequencies of different compounds are quite distinct, we do not encounter false alarms from the NQR signals of other benign materials. We have constructed a proof-of-concept NQR explosives detector which interrogates a volume of 300 liters (10 ft3). With minimal modification to the existing explosives detector, we can detect operationally relevant quantities of (free base) cocaine within the 300-liter inspection volume in 6 seconds. We are presently extending this approach to the detection of heroin base and also examining 14N and 35,37Cl pure NQR for detection of the hydrochloride forms of both materials. An adaptation of this NQR approach may be suitable for scanning personnel for externally carried contraband and explosives. We first outline the basics of the NQR approach, highlighting strengths and weaknesses, and then present representative results for RDX and cocaine detection. We also present a partial compendium of relevant NQR parameters measured for some materials of interest.

Garroway, Allen N.; Buess, M. L.; Yesinowski, J. P.; Miller, J. B.

1994-03-01

41

Miniature Magnet for Electron Spin Resonance Experiments  

ERIC Educational Resources Information Center

Describes commercially available permanent magnets that have been incorporated in a compact and inexpensive structure providing both field sweep and modulation suitable for electron spin resonance at microwave frequencies. (MLH)

Rupp, L. W.; And Others

1976-01-01

42

Flow Excited Helmholtz Resonator - Theory and Experiments  

NASA Astrophysics Data System (ADS)

Flow over the orifice of a Helmoltz resonator can result in a self excited resonance. The present research has focused on understanding this vortical-acoustic coupling by considering a simple control volume momentum analysis. A forcing term can then be identified, and considered in terms of a combined hydrodynamic-acoustic scaling. Direct measurements of the forcing were obtained using PIV for a range of speeds and orifice geometries. These measurements have motivated a simplified model for the forcing which allows accurate predictions of both the frequency and amplitude of the cavity pressure fluctuations.

Morris, Scott; Slaboch, Paul; Ma, Ruolong

2007-11-01

43

Stability and molecular dynamics of chloroxylenol (API of antiseptics and drugs) in solid state studied by 35Cl-NQR spectroscopy and DFT calculations  

NASA Astrophysics Data System (ADS)

Thermal stability of 4-chloro-3,5-dimethyl-phenol (chloroxylenol) in solid state has been studied by 35Cl-NQR spectroscopy. Two NQR resonance lines at the frequencies 34.348 and 34.415 MHz at 77 K have been assigned to chlorine atoms from two crystallographically inequivalent molecules on the basis of the B3LYP/6-311++G ?? results. The temperature dependence of the resonance frequency and full width at half maximum suggest the occurrence of small-angle torsional oscillations of the mean activation energy of 3.83 kJ/mol and rotation of both methyl groups around their symmetry axis C3 with the activation energies 12.49 and 11.27 kJ/mol for CH 3 in molecule A and B, respectively. B3LYP/6-311++G ?? method reproduced very well the activation energies of both motions.

Latosi?ska, J. N.; Tomczak, M. A.; Kasprzak, J.

2009-02-01

44

Rabi resonance in spin systems: Theory and experiment  

NASA Astrophysics Data System (ADS)

The response of a magnetic resonance spin system is predicted and experimentally verified for the particular case of a continuous wave amplitude modulated radiofrequency excitation. The experimental results demonstrate phenomena not previously observed in magnetic resonance systems, including a secondary resonance condition when the amplitude of the excitation equals the modulation frequency. This secondary resonance produces a relatively large steady state magnetisation with Fourier components at harmonics of the modulation frequency. Experiments are in excellent agreement with the theoretical prediction derived from the Bloch equations, which provides a sound theoretical framework for future developments in NMR spectroscopy and imaging.

Layton, Kelvin J.; Tahayori, Bahman; Mareels, Iven M. Y.; Farrell, Peter M.; Johnston, Leigh A.

2014-05-01

45

Local resonance bandgaps in periodic media: theory and experiment.  

PubMed

Periodic composites such as acoustic metamaterials use local resonance phenomenon in designing low frequency sub-Bragg bandgaps. These bandgaps emerge from a resonant scattering interaction between a propagating wave and periodically arranged resonators. This paper develops a receptance coupling technique to combine the dynamics of the resonator with the unit cell dynamics of the background medium to analyze flexural wave transmission in a periodic structure, involving a single degree of freedom coupling between the medium and the resonator. Receptance techniques allow for a straightforward extension to higher dimensional systems with multiple degrees of freedom coupling and for easier experimental measurements. Closed-form expressions for the location and width of sub-Bragg bandgaps are obtained. Rigid body modes of the unit cell of the background medium are shown to set the bounding frequencies for local resonance bandgaps. Results from the receptance analysis compare well with Bloch wave analysis and experiments performed on a finite structural beam with periodic masses and resonators. Stronger coupling and inertia of the resonator increase the local resonance bandgap width. Two-fold periodicity widens the Bragg bandgap, narrowed by local resonators, thus expanding the design space and highlighting the advantages of hierarchical periodicity. PMID:23967928

Raghavan, L; Phani, A Srikantha

2013-09-01

46

Nuclear quadrupole resonance of boron in borate glasses  

NASA Astrophysics Data System (ADS)

A continuous wave nuclear quadrupole resonance spectrometer that has a high sensitivity even at low frequencies has been built. Boron and aluminum NQR has been detected in the region 200 kHz to 1.4 MHz. For the first time, boron NQR has been detected in a glass. The NQR spectrum of pure B 20 3 glass is consistent with 85 ± 2% of the boron atoms belonging to boroxol rings. In sodium borate glasses, the number of borons in boroxol rings decreases with increasing sodium content, until when sodium oxide comprises 20 mol% of the glass less than 2% of the borons are in boroxol rings.

Gravina, Samuel J.; Bray, Phillip J.

47

27Al-NQR\\/NMR Study of Kondo Semiconductor CeFe2Al10  

Microsoft Academic Search

27Al-NQR\\/NMR measurements have been performed on CeFe2Al10 in relevance to the novel phase below T0=27 K of isostructural CeRu2Al10. NQR peaks are assigned to five crystallographically inequivalent Al sites. No splitting of the NQR spectra down to 1.5 K confirms the lack of phase transition in this compound. The gaplike decrease in the spin-lattice relaxation rate 1\\/T1 above about 20

Yukihiro Kawamura; Shingo Edamoto; Tomoaki Takesaka; Takashi Nishioka; Harukazu Kato; Masahiro Matsumura; Yo Tokunaga; Shinsaku Kambe; Hiroshi Yasuoka

2010-01-01

48

Fundamentals of Pulsed Nitrogen-14 Quadrupole Resonance  

NASA Astrophysics Data System (ADS)

The essential features of nitrogen-14 Nuclear Quadrupole Resonance, a new tool based on density matrix calculations is proposed. After a brief review of the density matrix theory, it is demonstrated that, for each of the three NQR transitions, the (3,3) density matrix can be reduced to a (2,2) matrix, evidently easier to handle. (2,2) rotation matrices are defined for predicting, in a straightforward manner, the system evolution under a rf pulse. The first example treated by this methodology concerns nutation experiments (evolution of the signal amplitude as a function of the pulse length) and it is shown that the NMR (Nuclear Magnetic Resonance) flip angle, in the case of powder samples, should be substituted by a pseudo flip angle which is no longer proportional to the pulse length. Still for powder samples, it is demonstrated that, in NQR, data averaging continuously improves when shortening the repetition time. Finally it has been possible to define proper phase cycles in view of measuring relaxation times (T1 and T2) by a two-pulse sequence. In all cases, experimental verifications were performed in order to assess this methodology.

Canet, Daniel; Ferrari, Maude

49

The single NqrB and NqrC subunits in the Na(+)-translocating NADH: quinone oxidoreductase (Na(+)-NQR) from Vibrio cholerae each carry one covalently attached FMN.  

PubMed

The Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR) is the prototype of a novel class of flavoproteins carrying a riboflavin phosphate bound to serine or threonine by a phosphodiester bond to the ribityl side chain. This membrane-bound, respiratory complex also contains one non-covalently bound FAD, one non-covalently bound riboflavin, ubiquinone-8 and a [2Fe-2S] cluster. Here, we report the quantitative analysis of the full set of flavin cofactors in the Na(+)-NQR and characterize the mode of linkage of the riboflavin phosphate to the membrane-bound NqrB and NqrC subunits. Release of the flavin by ?-elimination and analysis of the cofactor demonstrates that the phosphate group is attached at the 5'-position of the ribityl as in authentic FMN and that the Na(+)-NQR contains approximately 1.7mol covalently bound FMN per mol non-covalently bound FAD. Therefore, each of the single NqrB and NqrC subunits in the Na(+)-NQR carries a single FMN. Elimination of the phosphodiester bond yields a dehydro-2-aminobutyrate residue, which is modified with ?-mercaptoethanol by Michael addition. Proteolytic digestion followed by mass determination of peptide fragments reveals exclusive modification of threonine residues, which carry FMN in the native enzyme. The described reactions allow quantification and localization of the covalently attached FMNs in the Na(+)-NQR and in related proteins belonging to the Rhodobacter nitrogen fixation (RNF) family of enzymes. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012). PMID:22366169

Casutt, Marco S; Schlosser, Andreas; Buckel, Wolfgang; Steuber, Julia

2012-10-01

50

Spatiotemporal Stochastic Resonance:Theory and Experiment  

NASA Astrophysics Data System (ADS)

The amplification of weak periodic signals in bistable or excitable systems via stochastic resonance has been studied intensively over the last years. We are going one step further and ask: Can noise enhance spatiotemporal patterns in excitable media and can this effect be observed in nature? To this end, we are looking at large, two dimensional arrays of coupled excitable elements. Due to the coupling, excitation can propagate through the array in form of nonlinear waves. We observe target waves, rotating spiral waves and other wave forms. If the coupling between the elements is below a critical threshold, any excitational pattern will die out in the absence of noise. Below this threshold, large scale rotating spiral waves - as they are observed above threshold - can be maintained by a proper level of the noise[1]. Furthermore, their geometric features, such as the curvature can be controlled by the homogeneous noise level[2]. If the noise level is too large, break up of spiral waves and collisions with spontaneously nucleated waves yields spiral turbulence. Driving our array with a spatiotemporal pattern, e.g. a rotating spiral wave, we show that for weak coupling the excitational response of the array shows stochastic resonance - an effect we have termed spatiotemporal stochastic resonance. In the last part of the talk I'll make contact with calcium waves, observed in astrocyte cultures and hippocampus slices[3]. A. Cornell-Bell and collaborators[3] have pointed out the role of calcium waves for long-range glial signaling. We demonstrate the similarity of calcium waves with nonlinear waves in noisy excitable media. The noise level in the tissue is characterized by spontaneous activity and can be controlled by applying neuro-transmitter substances[3]. Noise effects in our model are compared with the effect of neuro-transmitters on calcium waves. [1]P. Jung and G. Mayer-Kress, CHAOS 5, 458 (1995). [2]P. Jung and G. Mayer-Kress, Phys. Rev. Lett.62, 2682 (1995). [3] A. Cornell-Bell, Steven M. Finkbeiner, Mark.S. Cooper and Stephen J. Smith, SCIENCE, 247, 373 (1990).

Peter, Jung

1996-03-01

51

Cyclotron resonance maser experiment in a nondispersive waveguide  

Microsoft Academic Search

A cyclotron-resonance maser (CRM) oscillator experiment in which a spiraling electron beam interacts with a transverse electromagnetic wave in a nondispersive waveguide is presented. The experiment employs a low-energy (<5 keV) low-current (<1 A) electron beam in a two-wire (Lecher type) waveguide. The microwave output frequency is tuned in this experiment by the axial magnetic field in the range 3.5-6.0

E. Jerby; A. Shahadi; R. Drori; M. Korol; M. Einat; M. Sheinin; V. Dikhtiar; V. Grinberg; M. Bensal; T. Harhel; Y. Baron; A. Fruchtman; V. L. Granatstein; G. Bekefi

1996-01-01

52

Assignment of phycocyanobilin in HMPT using triple resonance experiments.  

PubMed

A complete assignment of all resonances of a small organic molecule is a prerequisite for a structure determination using NMR spectroscopy. This is conventionally obtained using a well-established strategy based on COSY, HMQC and HMBC spectra. In case of phycocyanobilin (PCB) in HMPT this strategy was unsuccessful due to the symmetry of the molecule and extreme signal overlap. Since (13) C and (15) N labeled material was available, an alternative strategy for resonance assignment was used. Triple resonance experiments derived from experiments conventionally performed for proteins are sensitive and easy to analyze. Their application led to a complete and unambiguous assignment using three types of experiments. Copyright © 2011 John Wiley & Sons, Ltd. PMID:21815209

Röben, Marco; Schmieder, Peter

2011-08-01

53

Experimental study of the structure of chalcogenide glassy semiconductors in three-component systems of Ge-As-Se and As-Sb-Se by means of NQR and EPR spectroscopy  

NASA Astrophysics Data System (ADS)

The structure of chalcogenide glassy semiconductors in three-component systems of Ge-As-Se and As-Sb-Se has been studied by means of both NQR (nuclear quadrupole resonance) and EPR (electron paramagnetic resonance) spectroscopy. It is investigated that in the glasses of both systems the value of the electric field gradient at the resonating nuclei grows with increasing concentration of the clusters As2Se3 and Sb2Se3, thereby increasing the NQR resonance frequencies. It appears that for the Ge-As-Se system the structural transition from a two-dimensional to three-dimensional structure occurs at average coordination number = 2.45. The EPR spectral parameters of glasses depend on the composition, the average coordination number and the temperature, and these are discussed. The effect of "ageing" for CGS (chalcogenide glassy semiconductors) of As-Sb-Se system due to partial crystallization of the sample is observed from the EPR spectra.

Bolebrukh, Olga N.; Sinyavsky, Nikolay Ya.; Korneva, Irina P.; Dobosz, Bernadeta; Ostafin, Michal; Nogaj, Boleslaw; Krzyminiewski, Ryszard

2013-12-01

54

Hafnium Resonance Parameter Analysis using Neutron Capture and Transmission Experiments  

NASA Astrophysics Data System (ADS)

The focus of this work is to determine resonance parameters for stable hafnium isotopes in the 0.005-200 eV region, with special emphasis on the overlapping 176Hf and 178Hf resonances near 8 eV. The large neutron cross section of hafnium, combined with its corrosion resistance and excellent mechanical properties, make it a useful material for controlling nuclear reactions. Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute (RPI) electron linear accelerator (LINAC) using the time of flight method. 6Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m. Capture experiments were done using a sixteen-section NaI(Tl) multiplicity detector at a flight path length of 25 m. These experiments utilized various thicknesses of metallic and isotopically enriched liquid samples. The liquid samples were designed to provide information on the 176Hf and 178Hf contributions to the 8-eV doublet without saturation. Data analysis was done using the R-matrix Bayesian code SAMMY version M6 beta. SAMMY is able to account for experimental resolution effects for each of the experimental setups at the RPI LINAC, and also can correct for multiple scattering effects in neutron capture yield data. The combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005-200 eV. Resonance integrals were calculated along with errors for each hafnium isotope using the NJOY and INTER codes. The isotopic resonance integrals calculated were significantly different than previously published values; however the calculated elemental hafnium resonance integral changed very little.

Trbovich, Michael J.; Barry, Devin P.; Slovacek, Rudy E.; Danon, Yaron; Block, Robert C.; Burke, John A.; Drindak, Noel J.; Leinweber, Greg; Ballad, Robert V.

2005-05-01

55

A beat wave experiment in an open resonator  

Microsoft Academic Search

The present beat-wave experiment matches an open resonator to microwave sources in order to achieve a high field intensity with reasonable electromagnetic power input. By taking into account the plasma oscillation dynamics, as well as the electromagnetic field dynamics within the cavity that is coupled with the microwave sources, a novel set of optimal parameters and scaling laws is obtained.

G. di Massa; R. Fedele; G. Miano; C. Nappi

1990-01-01

56

I: Low Frequency NMR and NQR Using a dc SQUID. II: Variable-temperature 13C CP/MAS of Organometallics  

SciTech Connect

NMR and NQR at low frequencies are difficult prospects due to small nuclear spin polarization. Furthermore, the sensitivity'of the inductive pickup circuitry of standard spectrometers is reduced as the frequency is lowered. I have used a cw-SQUID (Superconducting QUantum Interference Device) spectrometer, which has no such frequency dependence, to study the local atomic environment of {sup 14}N via the quadrupolar interaction. Because {sup 14}N has spin I = 1 and a 0-6 MHz frequency range, it is not possible to obtain well-resolved spectra in high magnetic fields. I have used a technique to observe {sup 14}N NQR resonances via their effect on neighboring protons mediated by the heteronuclear dipolar interaction to study peptides and narcotics. The sensitivity of the SQUID is not enough to measure low-frequency surface (or other low spin density) systems. The application of spin-polarized xenon has been previously used to enhance polarization in conventional NMR experiments. Because xenon only polarizes spins with which it is in contact, it is surface selective. While differences in chemical shifts between surface and bulk spins are not large, it is expected that the differences in quadrupole coupling constant should be very large due to the drastic change of the electric field gradient surrounding spins at the surface. With this in mind, I have taken preliminary steps to measure SQUID detected polarization transfer from Xe to another spin species at 4.2 K and in small magnetic fields (<50 G). In this regime, the spin-lattice relaxation of xenon is dependent on the applied magnetic field. The results of our efforts to characterize the relaxation of xenon are presented. The final section describes the solid-state variable-temperature (VT) one- and two-dimensional {sup 13}C cross polarization (CP)/magic angle spinning (MAS) NMR of Hf({eta}{sup 5}-C{sub 5}H{sub 5}){sub 2}({eta}{sup 1}-C{sub 5}H{sub 5}){sub 2}, Zr({eta}{sup 5}-C{sub 5}H{sub 5}){sub 3}({eta}{sup 1}-C{sub 5}H{sub 5}) and Sn({eta}{sup 1}-C{sub 5}H{sub 5}){sub 4}. This work was undertaken in the hope of gaining insight into the intramolecuhrr dynamics, specifically which fluxional processes exist in the solid state, by what mechanism rearrangements are occurring, and the activation energies by which these processes are governed.

Ziegeweid, M.A.

1995-11-29

57

Magnetic Field Gradient Calibration as an Experiment to Illustrate Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

A nuclear magnetic resonance (NMR) spectroscopy experiment for the undergraduate physical chemistry laboratory is described that encompasses both qualitative and quantitative pedagogical goals. Qualitatively, the experiment illustrates how images are obtained in magnetic resonance imaging (MRI). Quantitatively, students experience the…

Seedhouse, Steven J.; Hoffmann, Markus M.

2008-01-01

58

Possible stripe fluctuations in La2 - x - yNdySrxCuO4 at room temperature observed by 63Cu NQR spectroscopy  

NASA Astrophysics Data System (ADS)

63Cu nuclear quadrupole resonance (NQR) studies at room temperature were reported on six Nd-doped La2 - xSrxCuO4 samples. The NQR spectrum for La1.48Nd0.4Sr0.12CuO4 has a different line shape compared with those from the other samples, which is similar to the case of the insulating La2CuO4. This may suggest that the stripe fluctuations at such a special Nd and Sr doping fall into the frequency window of 63Cu NQR. The spectra of the other five samples were analysed by pairs of 63Cu and 65Cu Gaussians at A and B sites. The full width of half-maxim (FWHM) for 63Cu at B sites is anomalously large for La1.45Nd0.4Sr0.15CuO4, which was considered to be related to the stripe fluctuations.

Zhang, Q.-M.; Ying, X. N.; Gu, M.; Wang, Y. N.

2005-04-01

59

Novel 2D Triple-Resonance NMR Experiments for Sequential Resonance Assignments of Proteins  

NASA Astrophysics Data System (ADS)

We present 2D versions of the popular triple resonance HN(CO) CACB, HN(COCA)CACB, HN(CO)CAHA, and HN(COCA) CAHA experiments, commonly used for sequential resonance assignments of proteins. These experiments provide information about correlations between amino proton and nitrogen chemical shifts and the ?- and ?-carbon and ?-proton chemical shifts within and between amino acid residues. Using these 2D spectra, sequential resonance assignments of H N, N, C ?, C ?, and H ? nuclei are easily achieved. The resolution of these spectra is identical to the well-resolved 2D 15N- 1H HSQC and H(NCO)CA spectra, with slightly reduced sensitivity compared to their 3D and 4D versions. These types of spectra are ideally suited for exploitation in automated assignment procedures and thereby constitute a fast and efficient means for NMR structural determination of small and medium-sized proteins in solution in structural genomics programs.

Ding, Keyang; Gronenborn, Angela M.

2002-06-01

60

INDO Investigation of the halogen N.Q.R. frequencies and 14 N nuclear quadrupole coupling constants of halothiophenes and halopyridines  

Microsoft Academic Search

The 35Cl, 79Br, and 127I N.Q.R. frequencies of a number of halothiophenes and halopyridines and the 14N nuclear quadrupole coupling constants of halopyridines have been determined in terms of the Kaplansky-Whitehead theory with the INDO MO approximations using a consistent set of atomic parameters derived from SCF Hartree-Fock calculations. The theoretical spectral properties are in satisfactory overall agreement with experiment.

V. Galasso

1974-01-01

61

An ultra-broadband low-frequency magnetic resonance system  

NASA Astrophysics Data System (ADS)

MR probes commonly employ resonant circuits for efficient RF transmission and low-noise reception. These circuits are narrow-band analog devices that are inflexible for broadband and multi-frequency operation at low Larmor frequencies. We have addressed this issue by developing an ultra-broadband MR probe that operates in the 0.1-3 MHz frequency range without using conventional resonant circuits for either transmission or reception. This “non-resonant” approach significantly simplifies the probe circuit and allows robust operation without probe tuning while retaining efficient power transmission and low-noise reception. We also demonstrate the utility of the technique through a variety of NMR and NQR experiments in this frequency range.

Mandal, S.; Utsuzawa, S.; Cory, D. G.; Hürlimann, M.; Poitzsch, M.; Song, Y.-Q.

2014-05-01

62

NMR and NQR parameters of the SiC-doped on the (4,4) armchair single-walled BPNT: a computational study.  

PubMed

The structural properties, NMR and NQR parameters in the pristine and silicon carbide (SiC) doped boron phosphide nanotubes (BPNTs) were calculated using DFT methods (BLYP, B3LYP/6-31G) in order to evaluate the influence of SiC-doped on the (4,4) armchair BPNTs. Nuclear magnetic resonance (NMR) parameters including isotropic (CS(I)) and anisotropic (CS(A)) chemical shielding parameters for the sites of various (13)C, (29)Si, (11)B, and (31)P atoms and quadrupole coupling constant (C ( Q )), and asymmetry parameter (? ( Q )) at the sites of various (11)B nuclei were calculated in pristine and SiC- doped (4,4) armchair boron phosphide nanotubes models. The calculations indicated that doping of (11)B and (31)P atoms by C and Si atoms had a more significant influence on the calculated NMR and NQR parameters than did doping of the B and P atoms by Si and C atoms. In comparison with the pristine model, the SiC- doping in Si(P)C(B) model of the (4,4) armchair BPNTs reduces the energy gaps of the nanotubes and increases their electrical conductance. The NMR results showed that the B and P atoms which are directly bonded to the C atoms in the SiC-doped BPNTs have significant changes in the NMR parameters with respect to the B and P atoms which are directly bonded to the Si atoms in the SiC-doped BPNTs. The NQR results showed that in BPNTs, the B atoms at the edges of nanotubes play dominant roles in determining the electronic behaviors of BPNTs. Also, the NMR and NQR results detect that the Fig. 1b (Si(P)C(B)) model is a more reactive material than the pristine and the Fig. 1a (Si(B)C(p)) models of the (4,4) armchair BPNTs. PMID:21625895

Baei, Mohammad T; Sayyad-Alangi, S Zahra; Moradi, Ali Varasteh; Torabi, Parviz

2012-03-01

63

First-principles study of (75)As NQR in arsenic-chalcogenide compounds.  

PubMed

We present a theoretical study of the nuclear quadrupole interaction, ?(Q), of (75)As in crystalline and amorphous materials containing sulfur and selenium, and compare them with experiment. We studied a combination of hydrogen-terminated molecular clusters and periodic cells at various levels of quantum chemical theory. The results show clearly that the standard density functional theory (DFT) approximations, LDA and GGA, underestimate the nuclear quadrupole (NQR) interaction systematically, while Hartree-Fock theory overestimates it to an even greater degree. However, various levels of configuration interaction and the B3LYP hybrid exchange-correlation functional, which includes some exact exchange, give very good quantitative agreement for As bonded only to the chalcogen species. As-As bonds require highly converged basis sets. We have performed a systematic study of the effect of local distortions around an arsenic atom on ?(Q) and ?. Using a simple, semiclassical model, we have combined our total energy results with our NQR calculations to predict ?(Q) lineshapes for bond angle and bond length distortions. Our predictions for lineshape, including first and second moments, are in excellent agreement with the results of Su et al for a-As(2)S(3), a-As(2)Se(3) and a-AsSe. We offer new insight into the distortions that led to this inhomogeneous broadening. Our results show clearly that, for trivalent arsenic atoms with zero or one arsenic nearest neighbor, symmetric bond stretching is the predominant contributor to the ?(Q) linewidth. However, in the presence of two arsenic nearest neighbors, distortions of the As-As-As apex angle dominates and, in fact, leads to a much larger second moment, in agreement with experiment. PMID:21406910

Edwards, Arthur H; Taylor, P C; Campbell, Kristy A; Pineda, Andrew C

2011-02-01

64

First-principles study of 75As NQR in arsenic-chalcogenide compounds  

NASA Astrophysics Data System (ADS)

We present a theoretical study of the nuclear quadrupole interaction, ?Q, of 75As in crystalline and amorphous materials containing sulfur and selenium, and compare them with experiment. We studied a combination of hydrogen-terminated molecular clusters and periodic cells at various levels of quantum chemical theory. The results show clearly that the standard density functional theory (DFT) approximations, LDA and GGA, underestimate the nuclear quadrupole (NQR) interaction systematically, while Hartree-Fock theory overestimates it to an even greater degree. However, various levels of configuration interaction and the B3LYP hybrid exchange-correlation functional, which includes some exact exchange, give very good quantitative agreement for As bonded only to the chalcogen species. As-As bonds require highly converged basis sets. We have performed a systematic study of the effect of local distortions around an arsenic atom on ?Q and ?. Using a simple, semiclassical model, we have combined our total energy results with our NQR calculations to predict ?Q lineshapes for bond angle and bond length distortions. Our predictions for lineshape, including first and second moments, are in excellent agreement with the results of Su et al for a-As2S3, a-As2Se3 and a-AsSe. We offer new insight into the distortions that led to this inhomogeneous broadening. Our results show clearly that, for trivalent arsenic atoms with zero or one arsenic nearest neighbor, symmetric bond stretching is the predominant contributor to the ?Q linewidth. However, in the presence of two arsenic nearest neighbors, distortions of the As-As-As apex angle dominates and, in fact, leads to a much larger second moment, in agreement with experiment.

Edwards, Arthur H.; Taylor, P. C.; Campbell, Kristy A.; Pineda, Andrew C.

2011-02-01

65

Optimal filtering in multipulse sequences for nuclear quadrupole resonance detection  

NASA Astrophysics Data System (ADS)

The application of the multipulse sequences in nuclear quadrupole resonance (NQR) detection of explosive and narcotic substances has been studied. Various approaches to increase the signal to noise ratio (SNR) of signal detection are considered. We discussed two modifications of the phase-alternated multiple-pulse sequence (PAMS): the 180° pulse sequence with a preparatory pulse and the 90° pulse sequence. The advantages of optimal filtering to detect NQR in the case of the coherent steady-state precession have been analyzed. It has been shown that this technique is effective in filtering high-frequency and low-frequency noise and increasing the reliability of NQR detection. Our analysis also shows the PAMS with 180° pulses is more effective than PSL sequence from point of view of the application of optimal filtering procedure to the steady-state NQR signal.

Osokin, D. Ya.; Khusnutdinov, R. R.; Mozzhukhin, G. V.; Rameev, B. Z.

2014-05-01

66

^63Cu NQR relaxation in the p-type transparent conductor CuScO_2:Mg  

NASA Astrophysics Data System (ADS)

Transparent conducting oxides with p-type conductivity are of interest as electronic complements to the more familiar n-type transparent conductors. This paper reports the first results of a study of carrier spin dynamics in p-type CuScO_2:Mg using ^63Cu nuclear spin-lattice relaxation measurements. Relaxation rates 1/T1 have been measured by nuclear quadrupole resonance (NQR) over the range 280 K to 400 K. The ^63Cu NQR frequency is found to be 28,135 ± 5 kHz at 300 K and to decrease linearly with temperature over the experimental range. The value of 1/T1 at 300 K is 130 ± 10 s-1. The rate is weakly dependent on temperature and increases by only about 15 % up to 400 K. This behavior contrasts sharply with results obtained previously(1. A. Rajabzadeh, J. Tate and W. Warren, Bull. Am. Phys. Soc. 48, 1009 (2003).) for the related material CuYO_2:Ca. In that material, relaxation rates for ^63Cu and ^65Cu were strongly temperature dependent, being approximately thermally-activated with activation energy 152 ± 10 meV. The nuclear relaxation properties of CuScO_2:Mg are suggestive of more conventional metallic transport in CuScO_2:Mg compared with CuYO_2:Ca.

Rossi, Vincent; Tate, Janet; Warren, William; Li, Jun; Sleight, Arthur

2003-05-01

67

Experiments on statistical mechanics using resonance ionization spectroscopy  

SciTech Connect

Five different fluctuation phenomena at the atomic and molecular levels have been studied by resonance ionization spectroscopy techniques with one-atom detection sensitivity. The Poisson distribution described the observed frequency distributions suggesting random behavior. In addition, a gedanken experiment suggested by Einstein and Furth on the diffusion of atoms was performed in order to test the equality between time and ensemble averages. The obtained results confirmed the ergodicity of the studied system.

Iturbe, J.; Allman, S.L.; Hurst, G.S.; Payne, M.G.

1984-04-01

68

Nitrogen-detected CAN and CON experiments as alternative experiments for main chain NMR resonance assignments  

PubMed Central

Heteronuclear direct-detection experiments, which utilize the slower relaxation properties of low ? nuclei, such as 13C have recently been proposed for sequence-specific assignment and structural analyses of large, unstructured, and/or paramagnetic proteins. Here we present two novel 15N direct-detection experiments. The CAN experiment sequentially connects amide 15N resonances using 13C? chemical shift matching, and the CON experiment connects the preceding 13C? nuclei. When starting from the same carbon polarization, the intensities of nitrogen signals detected in the CAN or CON experiments would be expected four times lower than those of carbon resonances observed in the corresponding 13C-detecting experiment, NCA-DIPAP or NCO-IPAP (Bermel et al. 2006b; Takeuchi et al. 2008). However, the disadvantage due to the lower ? is counteracted by the slower 15N transverse relaxation during detection, the possibility for more efficient decoupling in both dimensions, and relaxation optimized properties of the pulse sequences. As a result, the median S/N in the 15N observe CAN experiment is 16% higher than in the 13C observe NCA-DIPAP experiment. In addition, significantly higher sensitivity was observed for those residues that are hard to detect in the NCA-DIPAP experiment, such as Gly, Ser and residues with high-field C? resonances. Both CAN and CON experiments are able to detect Pro resonances that would not be observed in conventional proton-detected experiments. In addition, those experiments are free from problems of incomplete deuterium-to-proton back exchange in amide positions of perdeuterated proteins expressed in D2O. Thus, these features and the superior resolution of 15N-detected experiments provide an attractive alternative for main chain assignments. The experiments are demonstrated with the small model protein GB1 at conditions simulating a 150 kDa protein, and the 52 kDa glutathione S-transferase dimer, GST.

Takeuchi, Koh; Heffron, Gregory; Sun, Zhen-Yu J.; Frueh, Dominique P.

2010-01-01

69

Nuclear quadrupole resonance lineshape analysis for different motional models: stochastic Liouville approach.  

PubMed

A general theory of lineshapes in nuclear quadrupole resonance (NQR), based on the stochastic Liouville equation, is presented. The description is valid for arbitrary motional conditions (particularly beyond the valid range of perturbation approaches) and interaction strengths. It can be applied to the computation of NQR spectra for any spin quantum number and for any applied magnetic field. The treatment presented here is an adaptation of the "Swedish slow motion theory," [T. Nilsson and J. Kowalewski, J. Magn. Reson. 146, 345 (2000)] originally formulated for paramagnetic systems, to NQR spectral analysis. The description is formulated for simple (Brownian) diffusion, free diffusion, and jump diffusion models. The two latter models account for molecular cooperativity effects in dense systems (such as liquids of high viscosity or molecular glasses). The sensitivity of NQR slow motion spectra to the mechanism of the motional processes modulating the nuclear quadrupole interaction is discussed. PMID:22168707

Kruk, D; Earle, K A; Mielczarek, A; Kubica, A; Milewska, A; Moscicki, J

2011-12-14

70

Magnetic correlations in La(2-x)Sr(x)CuO4 from NQR relaxation and specific heat  

NASA Technical Reports Server (NTRS)

La-139 and Cu-63 Nuclear Quadrupole Resonance (NQR) relaxation measurements in La(2-x)Sr(x)CuO4 for x ranging from 0 up to 0.3, with particular emphasis on the effect of doping on the Cu(2+) magnetic correlations and dynamics, are reviewed. In the low doping limit, x less than or equal to 0.05, the results can be interpreted consistently in terms of a simple phenomenological 'two-fluids' model whereby the effect of thermally-activated mobile O(2p) holes is the one of disrupting locally the Cu(2+) spin correlations. For x greater than or equal to 0.1, the results indicate the onset, as T approaches T(sub c)(+), of a strong coupling between Cu(2+) spins and the Fermi liquid of O(2p) holes leading to the apparent disappearance of localized Cu(2+) moment in connection with the opening of a superconducting gap.

Borsa, F.; Rigamonti, A.

1991-01-01

71

Copper Nqr and NMR Study of Metal-Substituted Yttrium BARIUM(2) COPPER(3) OXYGEN(7) and Yttrium BARIUM(2) COPPER(4) OXYGEN(8)  

NASA Astrophysics Data System (ADS)

Pulsed nuclear quadrupole resonance (NQR) and nuclear magnetic resonance (NMR) have been used to investigate the effect of metal-substitution for copper in YBa_2Cu_3O_7 (YBCO123) and YBa_2Cu_4O_8 (YBCO124). Among many metal substitutions, Zn has an especially dramatic effect in suppressing the superconducting temperature T_{c}, and hence superconductivity. More interesting is that Zn and Fe have the same T_{c} suppression effect in YBCO124. This study focuses on the Zn substitutions in YBCO123 and Zn, Fe, and Co substitutions in YBCO124. In Zn doped YBCO123, Cu(2), plane site, NQR spectra and the frequency dependence of the spin-lattice relaxation rates have been measured over a temperature range from 77 K to 300 K to study the correlation of the suppression of the relaxation rate with the distance between the probe Cu nuclei and the impurity. It is found that the relaxation rate is insensitive to the variation of the NQR resonance frequency. However, by comparing the results of the Zn doped YBCO124 with those of YBCO123, it can be concluded that the suppression of the relaxation rate for both YBCO compounds in the normal state is caused by destruction of short-range antiferromagnetic correlation with substitution of nonmagnetic ion Zn on the Cu(2) sites. NQR and NMR measurements were carried out on both Cu(2), plane, and Cu(1), chain sites, for various concentrations of Zn, Fe, and Co dopants in YBCO124 over a temperature range from 77 K to 300 K. A strong correlation of the enhancement of Cu(2) spin lattice relaxation rate and suppression of superconductivity by impurities was found. The temperature dependence of the Cu(2) NMR linewidth exhibits a strong RKKY type exchange interaction below 225 K for Zn and Fe doped samples, which indicates the formation of the local magnetic moment. The enhancement of the relaxation rate is caused by the local magnetic moment Fe^ {+3} ion and the moments on Cu(2) neighbors when Zn^{+2} is substituted on Cu(2). This study gives us a clear picture of the spin pseudogap behavior in the high temperature superconductor cuprates. It also suggests that the magnetic moment on the CuO_2 plane may relate to the suppression of T_{c} in metal-substituted YBCO124.

Cheng, Show-Jye

72

Crystal cavity resonance for hard x rays: A diffraction experiment  

SciTech Connect

We report the details of the recent x-ray back diffraction experiments, in which interference fringes due to x-ray cavity resonance are unambiguously observed. The Fabry-Perot type cavities, the tested crystal devices of reflectivity R{approx_equal}0.5 and finesse F{approx_equal}2.3, consist of monolithic two-plate and eight-plate silicon crystals. They were prepared by using x-ray lithographic techniques. The thicknesses of the crystal plates and the gaps between the two adjacent plates are a few tens to hundreds {mu}m. The (12 4 0) back reflection and synchrotron x-radiation of energy resolution {delta}E=0.36 meV at 14.4388 keV are employed. Interference fringes in angle- and photon-energy scans for two-plate and eight-plate cavities are shown. Considerations on the temporal and spatial coherence for observable resonance interference fringes using synchrotron x-rays are presented. The details about the accompanied simultaneous 24-beam diffraction in relation to x-ray photon energy are also described.

Chang, S.-L. [Department of Physics, National Tsing Hua University (NTHU), Hsinchu, Taiwan, 300 (China); National Synchrotron Radiation Research Center (NSRRC), Hsinchu, Taiwan, 300 (China); Stetsko, Yu. P.; Tang, M.-T.; Shew, B.-Y. [National Synchrotron Radiation Research Center (NSRRC), Hsinchu, Taiwan, 300 (China); Lee, Y.-R.; Sun, W.-H.; Wu, H.-H.; Kuo, T.-T.; Chen, S.-Y.; Chang, Y.-Y.; Shy, J.-T. [Department of Physics, National Tsing Hua University (NTHU), Hsinchu, Taiwan, 300 (China); Yabashi, M. [Spring-8/JASRI, Mikazuki, Hyogo 679-5198 (Japan); Ishikawa, T. [Spring-8/JASRI, Mikazuki, Hyogo 679-5198 (Japan); Spring-8/RIKEN, Mikazuki, Hyogo 679-5148 (Japan); Lin, Y.-H. [Scientific Instrumentation Research and Development Center, Hsinchu, Taiwan, 300 (China); Tamasaku, K.; Miwa, D. [Spring-8/RIKEN, Mikazuki, Hyogo 679-5148 (Japan)

2006-10-01

73

Optical Resonators in Current and Future Experiments of the ALPS Collaboration  

SciTech Connect

The ALPS collaboration runs a 'light shining through a wall' (LSW) experiment to search for weakly interacting sub-eV particles (WISPs). Its sensitivity is significantly enhanced by the incorporation of a large-scale production resonator and a small-scale high-power resonant second harmonic generator. Here we report on important experimental details and limitations of these resonators and derive recommendations for further experiments. A very promising improvement for a future ALPS experiment is the incorporation of an additional large-scale regeneration resonator. We present a rough sketch of how to combine a regeneration resonator with a single-photon counter (SPC) as detector for regenerated photons.

Meier, T. [Max-Planck-Institute for Gravitational Physics, Albert-Einstein-Institute (Germany) and Institut fuer Gravitationsphysik, Leibniz Universitaet Hannover, Callinstr. 38, D-30167 Hannover (Germany)

2010-08-30

74

Ferromagnetic Quantum Critical Fluctuations and Anomalous Coexistence of Ferromagnetism and Superconductivity in UCoGe Revealed by Co-NMR and NQR Studies  

NASA Astrophysics Data System (ADS)

Co nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) studies were carried out for the recently discovered UCoGe, in which the ferromagnetic and superconducting (SC) transitions are reported to occur at TCurie˜ 3 K and TS˜ 0.8 K [Huy et al.: Phys. Rev. Lett. 99 (2007) 067006], in order to investigate the coexistence of ferromagnetism and superconductivity as well as the normal-state and SC properties from a microscopic point of view. From the nuclear spin-lattice relaxation rate 1/T1 and Knight-shift measurements, we confirm that ferromagnetic fluctuations that possess a quantum critical character are present above TCurie and also the occurrence of a ferromagnetic transition at 2.5 K in our polycrystalline sample. The magnetic fluctuations in the normal state show that UCoGe is an itinerant ferromagnet similar to ZrZn2 and YCo2. The onset SC transition is identified at TS˜ 0.7 K, below which 1/T1 arising from 30% of the volume fraction starts to decrease due to the opening of the SC gap. This component of 1/T1, which follows a T3 dependence in the temperature range 0.3-0.1 K, coexists with the magnetic components of 1/T1 showing a \\sqrt{T} dependence below TS. From the NQR measurements in the SC state, we suggest that the self-induced vortex state is realized in UCoGe.

Ohta, Tetsuya; Nakai, Yusuke; Ihara, Yoshihiko; Ishida, Kenji; Deguchi, Kazuhiko; Sato, Noriaki K.; Satoh, Isamu

2008-02-01

75

Resonant solar neutrino oscillation versus laboratory neutrino oscillation experiments  

SciTech Connect

The interplay between resonant solar neutrino oscillations and neutrino oscillations in laboratory experiments is investigated in a 3 generation model. Due to the assumed hierarchy of neutrino masses, together with our choice of a convenient parameterization of the 3 generation mixing matrix, we can derive a simple analytic formula which reduces the solar neutrino problem to an effective 2 generation problem. The reduction makes it apparent that the allowed range of mixing and mass parameters crucially depend on whether the survival probability of solar neutrinos S satisfies S greater than or equal to 1/3 or not. The formulae for probabilities of laboratory neutrino oscillations are also greatly simplified. We argue that a combination of the observed solar neutrino depletion and data obtained from reactor experiments seems to rule out some range of neutrino masses. If a sizable nu/sub ..mu../ ..-->.. nu/sub e/ oscillation is observed at accelerators, as suggested at this Workshop, it severely restricts the range of 2 mixing angles.

Lim, Chong-Sa

1987-02-01

76

27Al-NQR Study on Novel Phase Transition in CeOs2Al10  

NASA Astrophysics Data System (ADS)

We have performed 27Al-NQR measurements in CeOs2Al10 which exhibits a novel phase transition at T0=29 K The NQR parameters determined for all the Al sites in ambient pressure were compared with those in CeRu2Al10 with T0=27 K and CeFe2Al10 with no phase transition. The distinct NQR splitting just below T0=32.5 K under pressure 0.66 GPa ensures an enhancement of T0 and a homogeneous transition. Despite the increase of T0, the nuclear spin-lattice relaxation rate 1/Tl is suppressed over whole range of temperature than in ambient pressure. The characteristic features of no critical slowing down at T0 and of the remarkable decrease of 1/T1T starting at T > T0 become prominent under pressure, suggesting an approach to Kondo semiconductor in a valence fluctuation regime.

Matsumura, M.; Inagaki, T.; Kato, H.; Nishioka, T.; Tanida, H.; Sera, M.

2012-12-01

77

NQR1 controls lifespan by regulating the promotion of respiratory metabolism in yeast  

PubMed Central

Summary The activity and expression of plasma membrane NADH coenzyme Q reductase is increased by calorie restriction (CR) in rodents. Although this effect is well established and is necessary for CR's ability to delay aging, the mechanism is unknown. Here we show that the Saccharomyces cerevisiae homolog, NQR1, resides at the plasma membrane and when overexpressed extends both replicative and chronological lifespan. We show that NQR1 extends replicative lifespan in a SIR2-dependent manner by shifting cells towards respiratory metabolism. Chronological lifespan extension, in contrast, occurs via a SIR2-independent decrease in ethanol production. We conclude that NQR1 is a key mediator of lifespan extension by CR through its effects on yeast metabolism and discuss how these findings could suggest a function for this protein in lifespan extension in mammals.

Jimenez-Hidalgo, Maria; Santos-Ocana, Carlos; Padilla, Sergio; Villalba, Jose M.; Lopez-Lluch, Guillermo; Martin-Montalvo, Alejandro; Minor, Robin K.; Sinclair, David A.; de Cabo, Rafael; Navas, Placido

2009-01-01

78

Structural Isomer Identification via NMR: A Nuclear Magnetic Resonance Experiment for Organic, Analytical, or Physical Chemistry.  

ERIC Educational Resources Information Center

Background information, procedures used, and typical results obtained are provided for an experiment that examines the ability of nuclear magnetic resonance (NMR) to distinguish between structural isomers via resonance multiplicities and chemical shifts. Reasons for incorporating the experiment into organic, analytical, or physical chemistry…

Szafran, Zvi

1985-01-01

79

Advanced Undergraduate-Laboratory Experiment on Electron Spin Resonance in Single-Crystal Ruby  

ERIC Educational Resources Information Center

An electron-spin-resonance experiment which has been successfully performed in an advanced undergraduate physics laboratory is described. A discussion of that part of the theory of magnetic resonance necessary for the understanding of the experiment is also provided in this article. (DT)

Collins, Lee A.; And Others

1974-01-01

80

Density functional calculations of 14N and 11B NQR parameters in the H-capped (6,0) and (4,4) single-walled BN nanotubes  

NASA Astrophysics Data System (ADS)

Density functional theory (DFT) calculations were performed to calculate nitrogen-14 and boron-11 nuclear quadrupole resonance (NQR) spectroscopy parameters in the representative considered models of zigzag and armchair boron nitride nanotubes (BNNTs) for the first time. The considered models consisting of 1 nm length of H-capped (6,0) and (4,4) single-walled BNNT were first allowed to fully relax and then the NQR calculations were performed on the geometrically optimized models. The evaluated nuclear quadrupole coupling constants and asymmetry parameters for the mentioned nuclei reveal that the considered models can be divided into four layers of nuclei with an equivalent electrostatic environment where those nuclei at the ends of tubes have a very strong electrostatic environment compared to the other nuclei along the length of tubes. Those nuclei at the center of the tube length also have an equivalent electrostatic environment. The calculations were performed based on the B3LYP DFT method and 6-311G** and 6-311++G** standard basis sets using the Gaussian 98 package of program.

Mirzaei, Mahmoud; Hadipour, Nasser L.

2008-02-01

81

Cu-NQR of CeCu2Si2 under high pressure  

NASA Astrophysics Data System (ADS)

We have measured 63Cu-NQR spectral lines and nuclear spin-lattice relaxation time T1 under pressure up to 5.4 GPa. Daphne oil 7474 is used as the pressure-transmitting medium to obtain good hydrostaticity. NQR frequency 63?q above 4 GPa suddenly decreases from the linear pressure dependence in the low pressure range (P <= 3.5 GPa). The observed sudden downward deviation of 63?q is associated with an increase of Ce valence. Above 4.5 GPa, the linear pressure dependence of 63?q is observed again, most likely related to the sharp crossover to the high valence state.

Fujiwara, K.; Iwata, M.; Okazaki, Y.; Ikeda, Y.; Araki, S.; Kobayashi, T. C.; Murata, K.; Geibel, C.; Steglich, F.

2012-12-01

82

Superconductivity and magnetic fluctuations in Cd(2))Re(2)O(7) via Cd nuclear magnetic resonance and re nuclear quadrupole resonance.  

PubMed

We report Cd nuclear magnetic resonance (NMR) and Re nuclear quadrupole resonance (NQR) studies on Cd(2)Re(2)O(7), the first superconductor among pyrochlore oxides (T(c) approximately 1 K). The Re NQR spectrum at zero magnetic field below 100 K rules out any magnetic or charge order. The spin-lattice relaxation rate below T(c) exhibits a pronounced coherence peak and follows the weak-coupling BCS theory with nearly isotropic energy gap. The results of Cd NMR point to a moderate ferromagnetic enhancement at high temperatures followed by a rapid decrease of the density of states below the structural transition temperature of 200 K. PMID:12097064

Vyaselev, O; Arai, K; Kobayashi, K; Yamazaki, J; Kodama, K; Takigawa, M; Hanawa, M; Hiroi, Z

2002-07-01

83

Experiments on Statistical Mechanics Using Resonance Ionization Spectroscopy.  

National Technical Information Service (NTIS)

Five different fluctuation phenomena at the atomic and molecular levels have been studied by resonance ionization spectroscopy techniques with one-atom detection sensitivity. The Poisson distribution described the observed frequency distributions suggesti...

J. Iturbe S. L. Allman G. S. Hurst M. G. Payne

1984-01-01

84

Electronic properties of Y-Ba-Cu-O superconductors as seen by Cu and O NMR/NQR  

NASA Technical Reports Server (NTRS)

Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) allow the investigation of electronic properties at the atomic level. We will report on such studies of typical members of the the Y-Ba-Cu-O family such as YBa2Cu30(6 + x) (1-2-3-(6 + x)), YBa2Cu4O8 (1-2-4) and Y2Ba4Cu7015 (2-4-7) with many examples of recent work performed in our laboratory. In particular, we will deal with Knight shift and relaxation studies of copper and oxygen. We will discuss important issues of current studies such as: (1) Existence of a common electronic spin-susceptibility in the planes (and perhaps in the chains) of 1-2-4; (2) Strong evidence for the existence of a pseudo spin-gap of the antiferromagnetic fluctuations in 1-2-4 and 2-4-7; (3) Evidence for d-wave pairing in 1-2-4; (4) Strong coupling of inequivalent Cu-O planes in 2-4-7 and possible origin for the high Tc value of this compound; and (5) The possibility to describe NMR data in the framework of a charge-excitation picture.

Brinkmann, D.

1995-01-01

85

A new strategy for backbone resonance assignment in large proteins using a MQ-HACACO experiment  

Microsoft Academic Search

A new strategy of backbone resonance assignment is proposed based on a combination of the most sensitive TROSY-type triple resonance experiments such as TROSY-HNCA and TROSY-HNCO with a new 3D multiple-quantum HACACO experiment. The favourable relaxation properties of the multiple-quantum coherences and signal detection using the 13C' antiphase coherences optimize the performance of the proposed experiment for application to larger

Konstantin Pervushin; Alexander Eletsky

2003-01-01

86

Investigation of Wavelet-Based Enhancements to Nuclear Quadrupole Resonance Explosives Detectors  

SciTech Connect

Nuclear Quadrupole Resonance (NQR) is effective for the detection and identification of certain types of explosives such as RDX, PETN and TNT. In explosive detection, the NQR response of certain 14N nuclei present in the crystalline material is probed. The 14N nuclei possess a nuclear quadrupole moment which in the presence of an electric field gradient produces an energy level splitting which may be excited by radio-frequency magnetic fields. Pulsing on the sample with a radio signal of the appropriate frequency produces a transient NQR response which may then be detected. Since the resonant frequency is dependent upon both the quadrupole moment of the 14N nucleus and the nature of the local electric field gradients, it is very compound specific. Under DARPA sponsorship, the authors are using multiresolution methods to investigate the enhancement of operation of NQR explosives detectors used for land mine detection. For this application, NQR processing time must be reduced to less than one second. False alarm responses due to acoustic and piezoelectric ringing must be suppressed. Also, as TNT is the most prevalent explosive found in land mines, NQR detection of TNT must be made practical despite unfavorable relaxation tunes. All three issues require improvement in signal-to-noise ratio, and all would benefit from improved feature extraction. This paper reports some of the insights provided by multiresolution methods that can be used to obtain these improvements. It includes results of multiresolution analysis of experimentally observed NQR signatures for RDX responses and various false alarm signatures in the absence of explosive compounds.

Kercel, Stephen W.; Dress, William B.; Hibbs, Andrew D.; Barrall, Geoffrey A.

1998-06-01

87

Wavelet-based enhancements to nuclear quadrupole resonance explosives detectors  

NASA Astrophysics Data System (ADS)

Nuclear Quadrupole Resonance (NQR) is effective for the detecting and identification of certain types of explosives such as RDX, PETN and TNT. In explosive detection, the NQR response of certain 14N nuclei present in the crystalline material is proved. The 14N nuclei possess a nuclear quadrupole moment which in the presence of an electric field gradient produces an energy level splitting which may be excited by radio-frequency magnetic fields. Pulsing on the sample with a radio signal of the appropriate frequency produces a transient NQR response which may then be detected. Since the resonant frequency is dependent upon both the quadrupole moment of the 14N nucleus and the nature of the local electric field gradients, it is very compound specific. Under DARPA sponsorship, the authors are using multiresolution methods to investigate the enhancement of operation of NQR explosives detectors used for mine detection. For this application, NQR processing time must be reduced to less than one second. False alarm response due to acoustic and piezoelectric ringing must be suppressed. Also, as TNT is the most prevalent explosive found in land mines NWR detection of TNT must be made practical despite unfavorable relaxation times. All three issues require improvement in signal-to-noise ratio, and all would benefit from improved feature extraction. This paper reports some of the insights provided by multiresolution methods that can be used to obtain these improvements. It includes results of multiresolution analysis of experimentally observed NQR signatures for RDX response and various false alarm signatures in the absence of explosive compounds.

Kercel, Stephen W.; Dress, William B.; Hibbs, Andrew D.; Barrall, Geoffrey A.

1998-03-01

88

Sensing of chemical substances using SQUID-based nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

Using a high- Tc radio frequency superconducting quantum interference device (rf SQUID) with a normal metal transformer, we successfully detected the nuclear quadrupole resonance (NQR) at about 888 kHz of 14N in p-nitrotoluene (PNT) at room temperature. Only one coil was used as the resonator coil for the transmission and the pickup coil of the transformer. To reduce the influence of the strong excitation field, cross diodes and switches were inserted in the transformer. The signal-to-noise ratio of the NQR spectrum using high- Tc rf SQUID system was comparable to that of using a low noise preamplifier.

Tachiki, M.; He, D. F.; Itozaki, H.

2007-10-01

89

Measurement of the spin-lattice relaxation time in the NQR of light nuclei  

SciTech Connect

This work proposed a method for increasing the signal/noise ratio in NQR by preliminary magnetization of the sample in a constant magnetic field B/sub 0/ and it subsequent adiabatic demagnetization. The proposed method for the measurement of spin-lattice relaxation times is verified experimentally with a number of compounds. The results agree well with published data.

Anferov, V.P.; Anferova, S.V.; Grechishkin, V.S.; Sinyavskii, N.Ya.

1988-01-01

90

Modeling Nonlinear Acoustic Standing Waves in Resonators: Theory and Experiments  

NASA Technical Reports Server (NTRS)

The overall goal of the cooperative research with NASA Glenn is to fundamentally understand, computationally model, and experimentally validate non-linear acoustic waves in enclosures with the ultimate goal of developing a non-contact acoustic seal. The longer term goal is to transition the Glenn acoustic seal innovation to a prototype sealing device. Lucas and coworkers are credited with pioneering work in Resonant Macrosonic Synthesis (RMS). Several Patents and publications have successfully illustrated the concept of Resonant Macrosonic Synthesis. To utilize this concept in practical application one needs to have an understanding of the details of the phenomenon and a predictive tool that can examine the waveforms produced within resonators of complex shapes. With appropriately shaped resonators one can produce un-shocked waveforms of high amplitude that would result in very high pressures in certain regions. Our goal is to control the waveforms and exploit the high pressures to produce an acoustic seal. Note that shock formation critically limits peak-to-peak pressure amplitudes and also causes excessive energy dissipation. Proper shaping of the resonator is thus critical to the use of this innovation.

Raman, Ganesh; Li, Xiaofan; Finkbeiner, Joshua

2004-01-01

91

Parametric resonance oscillations of flexible slender cylinders in harmonically perturbed axial flow. Part 2: experiments  

SciTech Connect

The dynamic behavior of a flexible slender cylinder in axial flow, perturbed harmonically in time was examined experimentally. Parametric resonance oscillations were found to exist over certain ranges of frequencies and amplitudes of flow-velocity perturbations. The most prominent of the resonances, in these experiments, was associated with the second-mode principal primary resonance and was studied extensively. Agreement with theory was found to be quite good.

Paidoussis, M.P.; Issid, N.T.; Tsui, M.

1980-12-01

92

Modern Michelson-Morley Experiment using Cryogenic Optical Resonators  

Microsoft Academic Search

We report on a new test of Lorentz invariance performed by comparing the resonance frequencies of two orthogonal cryogenic optical resonators subject to Earth's rotation over ˜1 yr. For a possible anisotropy of the speed of light c, we obtain Deltathetac\\/c0=(2.6±1.7)×10-15. Within the Robertson-Mansouri-Sexl (RMS) test theory, this implies an isotropy violation parameter beta-delta-1\\/2=(-2.2±1.5)×10-9, about 3 times lower than the

Holger Müller; Sven Herrmann; Claus Braxmaier; Stephan Schiller; Achim Peters

2003-01-01

93

Experiments on Magnetoacoustic Resonances in a Rotating Plasma.  

National Technical Information Service (NTIS)

An external ringing resonance circuit was coupled to a rotating fully ionized hydrogen plasma. The damping of the oscillations was a measure of the coupling between the external circuit and the plasma. The frequency of the oscillations was varied and abso...

E. Tennfors J. Bergstroem M. Bures

1974-01-01

94

Optical control of nuclear resonant absorption: Theory and experiment  

NASA Astrophysics Data System (ADS)

Modification of nuclear resonant absorption by means of laser radiation is analyzed both theoretically and experimentally. Theoretical analysis is done on the basis of four-level model of atom. This model includes both electronic and nuclear excitations. It is predicted that under coherent laser driving nuclear resonant Mossbauer absorption can be significantly modified, e.g. new Mossbauer resonances can appear, some of the existing resonances can vanish, both can be Rabi-split, broadened by laser action. In addition, it is predicted that Mossbauer absorption can be completely suppressed due to coherent population trapping. Experimental observation of laser-induced transformations of Mossbauer spectra of 57 Fe2+:MgO is accomplished. New Mossbauer lines appear with laser driving while the existing are broadened. Possible explanations of the observed changes in 57Fe 2+:MgO Mossbauer spectra are population of higher-lying electronic states of iron ion and significant modification of electronic relaxation processes due to modified Jahn-Teller interaction.

Kolesov, Roman L.

95

The microfiber loop resonator: theory, experiment, and application  

Microsoft Academic Search

This paper describes the theory of a microfiber loop resonator (MLR) and experimentally demonstrates a high quality factor MLR in free space. The MLR is fabricated from the ?1-?m diameter waist of a biconical fiber taper using the CO2 laser indirect heating technique. The high coupling efficiency of an MLR is achieved through an adiabatically slow variation of the microfiber

M. Sumetsky; Y. Dulashko; J. M. Fini; A. Hale; D. J. DiGiovanni

2006-01-01

96

Laboratory Experiments for Exploring the Surface Plasmon Resonance  

ERIC Educational Resources Information Center

The surface plasmon wave is a surface wave confined at the interface between a dielectric and a metal. The excitation of the surface plasmon resonance (SPR) on a gold thin film is discussed within the Kretschmann configuration, where the coupling with the excitation light is achieved by means of a prism in total reflection. The electromagnetic…

Pluchery, Olivier; Vayron, Romain; Van, Kha-Man

2011-01-01

97

Low-frequency nuclear quadrupole resonance with a dc SQUID  

SciTech Connect

Conventional pure nuclear quadrupole resonance (NQR) is a technique well suited for the study of very large quadrupolar interactions. Numerous nuclear magnetic resonance (NMR) techniques have been developed for the study of smaller quadrupolar interactions. However, there are many nuclei which have quadrupolar interactions of intermediate strength. Quadrupolar interactions in this region have traditionally been difficult or unfeasible to detect. This work describes the development and application of a SQUID NQR technique which is capable of measuring intermediate strength quadrupolar interactions, in the range of a few hundred kilohertz to several megahertz. In this technique, a dc SQUID (Superconducting QUantum Interference Device) is used to monitor the longitudinal sample magnetization, as opposed to the transverse magnetization, as a rf field is swept in frequency. This allows the detection of low-frequency nuclear quadrupole resonances over a very wide frequency range with high sensitivity. The theory of this NQR technique is discussed and a description of the dc SQUID system is given. In the following chapters, the spectrometer is discussed along with its application to the study of samples containing half-odd-integer spin quadrupolar nuclei, in particular boron-11 and aluminum-27. The feasibility of applying this NQR technique in the study of samples containing integer spin nuclei is discussed in the last chapter. 140 refs., 46 figs., 6 tabs.

Chang, J.W.

1991-07-01

98

Novel phase diagram of superconductivity and ferromagnetism in UGe2: a 73Ge-NQR study under high pressure  

Microsoft Academic Search

We report on the pressure-induced novel phases of ferromagnetism (FM) and superconductivity (SC) in the itinerant ferromagnet UGe2 through 73Ge-NQR measurements under pressure (P). The P dependence of the NQR spectrum points to a first-order transition from strongly to weakly polarized ferromagnetic phases (SP and WP) around a critical pressure of P_{\\\\mathrm {c}}^*\\\\sim 1.2 GPa. Furthermore, it shows the phase

Y. Kitaoka; H. Kotegawa; A. Harada; S. Kawasaki; Y. Kawasaki; Y. Haga; E. Yamamoto; Y. Onuki; K. M. Itoh; E. E. Haller; H. Harima

2005-01-01

99

Evidence for the microscopic coexistence of superconductivity and ferromagnetism in UGe2:Ge-NMR\\/NQR study  

Microsoft Academic Search

We report on the pressure-induced novel phases of ferromagnetism and superconductivity (SC) in the itinerant ferromagnet UGe2 via the 73Ge-NQR measurements under pressure (P). The NQR spectrum has revealed that the ferromagnetic phases are separated into weakly and strongly polarized phases around a critical value of Pc*˜1.2GPa, pointing to a first-order transition around Pc*. Here we present further evidence for

A. Harada; H. Kotegawa; Y. Kawasaki; G.-Q. Zheng; Y. Kitaoka; E. Yamamoto; Y. Haga; Y. Onuki; K. Itoh; E. E. Haller

2005-01-01

100

Evidence for Uniform Coexistence of Ferromagnetism and Unconventional Superconductivity in UGe2: A 73Ge-NQR Study under Pressure  

Microsoft Academic Search

We report on the itinerant ferromagnetic superconductor UGe2 through 73Ge-NQR measurements under pressure (P). The P dependence of the NQR spectrum signals a first-order transition from the low-temperature (T) and low-P ferromagnetic phase (FM2) to high-T and high-P one (FM1) around a critical pressure of Px ˜ 1.2 GPa. The superconductivity exhibiting a maximum value of Tsc=0.7 K at Px

H. Kotegawa; A. Harada; S. Kawasaki; Y. Kawasaki; Y. Kitaoka; Y. Haga; E. Yamamoto; Y. Onuki; K. M. Itoh; E. E. Haller; H. Harima

2005-01-01

101

Modern Michelson-Morley Experiment using Cryogenic Optical Resonators  

NASA Astrophysics Data System (ADS)

We report on a new test of Lorentz invariance performed by comparing the resonance frequencies of two orthogonal cryogenic optical resonators subject to Earth's rotation over ˜1 yr. For a possible anisotropy of the speed of light c, we obtain ??c/c0=(2.6±1.7)×10-15. Within the Robertson-Mansouri-Sexl (RMS) test theory, this implies an isotropy violation parameter ?-?-1/2=(-2.2±1.5)×10-9, about 3 times lower than the best previous result. Within the general extension of the standard model of particle physics, we extract limits on seven parameters at accuracies down to 10-15, improving the best previous result by about 2 orders of magnitude.

Müller, Holger; Herrmann, Sven; Braxmaier, Claus; Schiller, Stephan; Peters, Achim

2003-07-01

102

Peptide backbone orientation and dynamics in spider dragline silk and two-photon excitation in nuclear magnetic and quadrupole resonance  

NASA Astrophysics Data System (ADS)

In the first part of the dissertation, spider dragline silk is studied by solid state NMR techniques. The dependence of NMR frequency on molecular orientation is exploited using the DECODER experiment to determine the orientation of the protein backbone within the silk fibre. Practical experimental considerations require that the silk fibres be wound about a cylindrical axis perpendicular to the external magnetic field, complicating the reconstruction of the underlying orientation distribution and necess-itating the development of numerical techniques for this purpose. A two-component model of silk incorporating static b-sheets and polyglycine II helices adequately fits the NMR data and suggests that the b-sheets are well aligned along the silk axis (20 FWHM) while the helices are poorly aligned (68 FWHM). The effects of fibre strain, draw rate and hydration on orientation are measured. Measurements of the time-scale for peptide backbone motion indicate that when wet, a strain-dependent frac-tion of the poorly aligned component becomes mobile. This suggests a mechanism for the supercontraction of silk involving latent entropic springs that undergo a local strain-dependent phase transition, driving supercontraction. In the second part of this dissertation a novel method is developed for exciting NMR and nuclear quadrupole resonance (NQR) by rf irradiation at multiple frequencies that sum to (or differ by) the resonance frequency. This is fundamentally different than traditional NMR experiments where irradiation is applied on-resonance. With excitation outside the detection bandwidth, two-photon excitation allows for detection of free induction signals during excitation, completely eliminating receiver dead-time. A theoretical approach to describing two-photon excitation is developed based on average Hamiltonian theory. An intuition for two-photon excitation is gained by analogy to the coherent absorption of multiple photons requiring conservation of total energy and momentum. It is shown that two-photon excitation efficiency impro-ves when the two applied rf frequencies deviate from half-resonance. For two-photon NQR, it is shown that observable magnetization appears perpendicular to the excita-tion coil, requiring a second coil for detection, and that double quantum coherences are also generated. Several model systems and experimental geometries are used to demonstrate the peculiarities of two-photon excitation in NMR and NQR.

Eles, Philip Thomas

103

Experiences with functional magnetic resonance imaging at 1 tesla  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) has been performed on a standard 1 T system using a pulse sequence developed to utilize blood oxygen level dependent (BOLD) contrast and an oV-line analysis routine using correlation techniques. The sequence and the data analysis routine have been validated by reproducing the conventional hand movement paradigm studies reported by numerous other workers. Our work

A P JONES; D G HUGHES; D S BRETTLE; L ROBINSON; J R SYKES; Q AZIZ; S HAMDY; D G THOMPSON; S W G DERBYSHIRE; A C N CHEN

1998-01-01

104

Idea Bank: A Resonance Tube Experiment Using "Boomwhackers"  

NSDL National Science Digital Library

Bring the "sound of music" to your science classroom--this activity uses the lengths and fundamental frequencies of a set of resonance tubes to verify the expression for the relationship between these two quantities and the value of the speed of sound. Students blow into one end of the boomwhackers and capture the sound onto a computer. Analysis of the resulting waveform provides an excellent introduction to the mathematical relationships between the musical intervals in a scale.

Lopresto, Michael

2005-01-01

105

Stereoelectronic structure and 35Cl NQR parameters of 4-(trichlorgermyl)butan-2-one using ab initio calculations  

NASA Astrophysics Data System (ADS)

The results of ab initio calculations at the RHF/6-31G(d) and MP2/6-31G(d) levels of two stable structures of the 4-(trichlorgermyl)butan-2-one molecule with total optimization of their geometry have been represented. The structure with pentacoordinated Ge atom is energetically more advantageous as compared with that with tetracoordinated one. Using these results, the 35Cl nuclear quadrupole resonance (NQR) frequencies and asymmetry parameters of the electric field gradient (EFG) at the 35Cl nuclei in molecule with pentacoordinated Ge atom have been assessed, the frequencies satisfactorily agreeing with experimental data. Calculations at the RHF/6-31G(d) level have been performed also at various Ge⋯O distances. It has been demonstrated that convergence of the Ge and O coordination centers leads to the increase of positive charge at the Ge coordination center and of negative charge at the O coordination center, at that, electron density from the Ge atom shifts mainly to the axial Cl atom and from the C atom of carbonyl group - to its O atom. The electron density transfer from the O to Ge atom does not occur.

Feshin, V. P.; Feshina, E. V.

2012-03-01

106

Magnetic correlations in La(2-x)Sr(x)CuO4 from NQR relaxation and specific heat  

NASA Astrophysics Data System (ADS)

La-139 and Cu-63 Nuclear Quadrupole Resonance (NQR) relaxation measurements in La(2-x)Sr(x)CuO4 for O = to or less than 0.3 and in the temperature range 1.6 + 450 K are analyzed in terms of Cu(++) magnetic correlations and dynamics. It is described how the magnetic correlations that would result from Cu-Cu exchange are reduced by mobile charge defects related to x-doping. A comprehensive picture is given which explains satisfactorily the x and T dependence of the correlation time, of the correlation length and of the Neel temperature T(sub n)(x) as well as being consistent with known electrical resistivity and magnetic susceptibility measurements. It is discussed how, in the superconducting samples, the mobile defects also cause the decrease, for T yields T(sub c)(+) of the hyperfine Cu electron-nucleus effective interaction, leading to the coexistence of quasi-localized, reduced magnetic moments from 3d Cu electrons and mobile oxygen p-hole carriers. The temperature dependence of the effective hyperfine field around the superconducting transition yields an activation energy which could be related to the pairing energy. New specific heat measurements are also presented and discussed in terms of the above picture.

Borsa, F.; Rigamonti, A.

1990-04-01

107

Triple Resonance Solid State NMR Experiments with Reduced Dimensionality Evolution Periods  

NASA Astrophysics Data System (ADS)

Two solid state NMR triple resonance experiments which utilize the simultaneous incrementation of two chemical shift evolution periods to obtain a spectrum with reduced dimensionality are described. The CON CA experiment establishes the correlation of 13C i-1 to 13C? i and 15N i by simultaneously encoding the 13CO i-1 and 15N i chemical shifts. The CAN COCA experiment establishes the correlation 13Ca i and 15CO i to 13C? i-1 and 15N i-1 within a single experiment by simultaneous encoding of the 13C? i and 15N i chemical shifts. This experiment establishes sequential amino acid correlations in close analogy to the solution state HNCA experiment. Reduced dimensionality 2D experiments are a practical alternative to recording multiple 3D data sets for the purpose of obtaining sequence-specific resonance assignments of peptides and proteins in the solid state.

Astrof, Nathan S.; Lyon, Charles E.; Griffin, Robert G.

2001-10-01

108

Velocity of sound and resonance absorption determination from a low-cost Helmholtz experiment  

Microsoft Academic Search

A low-cost Helmholtz resonator system is described. The system is simple to construct and yet yields high quality absorption line shapes and a value for the velocity of sound accurate to within 1%. The experiment should be a welcome addition to an under-graduate laboratory where there is a general lack of acoustics experiments and in particular precision measurement of acoustic

S. H. Tant; H. S. Tan; K. L. Tan; T. S. Hsu

1985-01-01

109

Satellites Probing the Alfvénic Resonator Cavity Experiment : SPARC-E  

NASA Astrophysics Data System (ADS)

We discuss a space sensor network that has the objective of understanding and quantitatively understanding the role of low frequency plasma waves in driving ion outflow from the ionosphere to the magnetosphere in the coupled magnetosphere-ionosphere (MI) system. Recently, attention has fallen on the Ionospheric Alfvén Resonator (IAR). The IAR is a cavity-resonator with natural frequencies ~0.1 - 5 Hz in the upper atmosphere, formed with a lower boundary at the conducting E-region and an upper boundary at the Alfvén speed maxima at around 1 earth radius. This cavity resonator is believed to play an important part in the development of perpendicular density and field aligned current (FAC) scales, resonant coupling with electromagnetic ion cyclotron waves that provide loss mechanisms for energetic particles in the radiation belt, and ion and energy outflow feedback mechanisms into the ionosphere. However, the simultaneous multi-point in-situ observations inside the IAR cavity that are needed to categorize observationally how the waves and density structures evolve have never been made. Validation of IAR models at low altitude would benefit from satellite measurements in the topside ionosphere. At assumed F-region altitudes of 200-400 km, optimal data will be obtained if the (unambiguous) spatial and temporal resolution of measurements is better than the expected phenomenon scales; this would require simultaneous in-situ measurements separated by spatial scales from as small as 100 m up to on the order of a few km, at up to ~1 s cadence. Remote imaging techniques integrate over the ionosphere within volumes that have scale sizes of several tens of km, and are thus unsuitable for determining the smaller spatial scales that are proposed in this study. Sensors on a single satellite taking point measurements suffer from an inherent inability to distinguish spatial and temporal effects, which is a strong requirement for unambiguously studying waves. An absolute minimum of four satellites in an out-of-plane constellation is required to unambiguously resolve space and time effects in the ambient region. The proposed SPARC-E mission consists of plasma sensors measuring electron temperature and density placed on eight satellites in similar orbits between 300 and 800 km. Inter-satellite separations increase over the lifetime of the mission from a few cm to tens of km. The mission concept is to deploy ten wirelessly-linked, very small satellites to take distributed, in-situ measurements of ionospheric plasma density and temperature in the IAR cavity. A high-latitude circular orbit (>60 degree inclination, ~350-800 km altitude) allows sensor satellites to enter and exit the IAR cavity region of interest and thus acquire both baseline and disturbed measurements. The constellation will not be maintained, but rather be launched together and allowed to disperse naturally due to orbital perturbations. Orbit control is not required or desired, as the natural perturbations will serve to alter the separation and lower the altitude over time without adding the complexity and overhead of a propulsion subsystem. We will describe details of the overall mission concept to include the payload, spacecraft bus, and mission operations.

Dearborn, M. E.; Balthazor, R. L.; McHarg, M. G.; Huffman, J. J.

2009-12-01

110

Nuclear quadrupole resonance and nuclear magnetic resonance of copper in the high-T/sub c/ superconductor YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/  

SciTech Connect

The /sup 65/Cu and /sup 63/Cu zero-field nuclear quadrupole resonance (NQR), nuclear magnetic resonance (NMR) at 4.7 and 8.5 T and the spin-lattice relaxation time T/sub 1/ at 8.5 T are measured in the superconducting oxide YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ between 80 and 300 K. No sign of magnetic order or localized moments are found. The NQR linewidth is strongly dependent on the oxygen content. We assign the /sup 63/Cu NQR line at 22 MHz to the Cu site with oxygen coordination 5. T/sub 1/ is dominated by the quadrupolar relaxation due to spin-phonon coupling.

Furo, I.; Janossy, A.; Mihaly, L.; Banki, P.; Pocsik, I.; Bakonyi, I.; Heinmaa, I.; Joon, E.; Lippmaa, E.

1987-10-01

111

Neutral-Ionic Phase Transition in DMTTF-QCl4 Investigated by 35Cl NQR  

NASA Astrophysics Data System (ADS)

We report a 35Cl NQR investigation into the neutral-ionic (NI) phase transition in DMTTF-QCl4 (4,4'-dimethyltetrathiafulvalene- p-chloranil), the end material of the family containing an NI quantum transition system. Four distinct lines with comparable intensities were observed well below Tc=65 K; this observation is consistent with the antiferroelectric nature of the ionic phase. The temperature dependences of the spectral shift and splitting below Tc are moderate in contrast with the case of TTF-QCl4. Low-energy charge-lattice fluctuations are observed around Tc as a drastic increase of 1/T1, allowing the observation of the quantum fluctuations in a chemically substituted complex. An analysis of the NQR spectra yields detailed temperature variations in the charge transfer and the concomitant lattice distortion around the NI transition.

Iwase, Fumitatsu; Miyagawa, Kazuya; Fujiyama, Shigeki; Kanoda, Kazushi; Horiuchi, Sachio; Tokura, Yoshinori

2007-07-01

112

Conformations and intermolecular interactions pattern in solid chloroxylenol and triclosan (API of anti-infective agents and drugs). A (35) Cl NQR, (1) H-(14) ?N NQDR, X-ray and DFT/QTAIM study.  

PubMed

Two antibacterial and antifungal agents, chloroxylenol (4-chloro-3,5-dimethyl-phenol) and triclosan (5-chloro-2-(2',4'-dichlorophenoxy)-phenol), were studied experimentally in solid state with an X-ray, (35) Cl-nuclear quadrupole resonance (NQR) and (17) O-nuclear quadrupole double resonance (NQDR) spectroscopies and, theoretically, with the density functional theory/quantum theory of atoms in molecules (DFT/QTAIM). The crystallographic structure of triclosan, which crystallises in space group P3(1) with one molecule in the asymmetric unit [a?=?12.64100(10), b?=?12.64100(10), c = 6.71630(10) Å], was solved with an X-ray and refined to a final R-factor of 2.81% at room temperature. The NQR frequencies of (35) Cl and (17) O were detected with the help of the density functional theory (DFT) assigned to particular chlorine and oxygen sites in the molecules of both compounds. The NQR frequencies at (35) Cl sites in chloroxylenol and triclosan were found to be more differentiated than frequencies at the (17) O site. The former better describes the substituent withdrawing effects connected to ?-electron delocalization within the benzene rings and the influence of temperature; whereas, those at the (17) O site provide more information on O-H bond and intermolecular interactions pattern. The conformation adopted by diphenyl ether of triclosan in solid state was found to be typical of diphenyl ethers, but the opposite to those adopted when it was bound to different inhibitors. According to an X-ray study, temperature had no effect on the conformation of the diphenyl ring of triclosan, which was the same at 90?K and at room temperature (RT). The scattering of NQR frequencies reproduced by the DFT under assumption of the X-ray data at 90?K and RT is found to be a good indicator of the quality of resolution of the crystallographic structure. Copyright © 2012 John Wiley & Sons, Ltd. PMID:22354770

Latosi?ska, J N; Latosi?ska, M; Tomczak, M A; Seliger, J; Zagar, V; Maurin, J K

2012-02-21

113

Near-field optical experiments on low-symmetry split-ring-resonator arrays.  

PubMed

Effective symmetric and antisymmetric eigenmodes of coupled plasmonic resonances play a crucial role in many photonic metamaterials. Recently, we discussed a particular arrangement of metallic split-ring resonators that is planar, hence enabling direct experimental access to the different eigenmodes via near-field optical microscopy. In this Letter, corresponding optical experiments are presented and compared with simple theoretical modeling, providing a direct confirmation of our previous, more indirect conclusions. PMID:21042383

Diessel, Daniela; Decker, Manuel; Linden, Stefan; Wegener, Martin

2010-11-01

114

Ru NQR Probe of Superconducting Property in Impurity-Doped CeRu 2  

Microsoft Academic Search

Superconducting characteristics of CeRu2 have been investigated by systematic measurements of the nuclear-spin lattice relaxation rate, 1\\/T1 of 101Ru on pure and impurity-substituted CeRu2, employing an NQR technique in zero magnetic field. (1\\/T1) for CeRu2 shows a broad coherence plateau just below T c followed by an exponential decrease well below T c. By contrast, a distinct coherence peak of

Hidekazu Mukuda; Kenji Ishida; Yoshio Kitaoka; Kunisuke Asayama

1998-01-01

115

Addition compounds of antimony trichloride and tribromide. Crystal structure and charge transfer from NQR data  

NASA Astrophysics Data System (ADS)

The correlation analysis of the quadrupcle coupling constants(QCC) for the antimony nuclei in the intermolecular compounds of SbCl 3 and SbBr 3 with aromatic hydrocarbons is carried out. The results confirm a supposition about the general similarity of the crystal structures of these complexes. The correlative dependence between the antimony QCC values and also the results of the chlorine and bromine NQR spectra Investigation permit the evaluation of the relative acceptor strength of the antimony trihalide molecules.

Kjuntsel, I. A.; Gordeev, A. D.

116

Unconventional superconductivity in ferromagnetic UGe2: a 73Ge nuclear magnetic resonance\\/nuclear quadrupole resonance study  

Microsoft Academic Search

We report 73Ge nuclear magnetic resonance\\/nuclear quadrupole resonance (NMR\\/NQR) measurements on the itinerant ferromagnetic superconductor UGe2 at ambient pressure (P = 0) and P = 1.3 GPa. Measurements of the nuclear spin-lattice relaxation rate 1\\/T1 of the 73Ge NMR at P = 0 have revealed a T1T = constant behaviour well below TCurie = 52 K, evidencing the presence of

H. Kotegawa; S. Kawasaki; A. Harada; Y. Kawasaki; K. Okamoto; G.-q. Zheng; Y. Kitaoka; E. Yamamoto; Y. Haga; Y. Onuki; K. M. Itoh; E. E. Haller

2003-01-01

117

14N nuclear quadrupole resonance of p-nitrotoluene using a high-Tc rf SQUID  

NASA Astrophysics Data System (ADS)

Using a high-Tc radio-frequency superconducting quantum interference device (rf SQUID), we successfully detected nuclear quadrupole resonance (NQR) at about 887 kHz for 14N in p-nitrotoluene (PNT). A normal metal transformer made of copper wire was used to improve the sensitivity of the high-Tc rf SQUID and pulse-controlled rf switches and cross diodes were inserted in the transformer to reduce the influence of the strong excitation field. The preliminary results for NQR detection using the high-Tc SQUID had a similar signal-to-noise ratio to that of using a low noise preamplifier.

He, D. F.; Tachiki, M.; Itozaki, H.

2007-03-01

118

27Al-NQR/NMR Study of Kondo Semiconductor CeFe2Al10  

NASA Astrophysics Data System (ADS)

27Al-NQR/NMR measurements have been performed on CeFe2Al10 in relevance to the novel phase below T0=27 K of isostructural CeRu2Al10. NQR peaks are assigned to five crystallographically inequivalent Al sites. No splitting of the NQR spectra down to 1.5 K confirms the lack of phase transition in this compound. The gaplike decrease in the spin-lattice relaxation rate 1/T1 above about 20 K, following the Korringa law (T1T = const.) below 20 K, indicates a pseudogap opening near the Fermi level. The gap magnitude of 70 K with a mid-gap state of 42% is estimated based on a rectangular density of states. The gap magnitude is much larger than the gap of 15 K evaluated previously from the electrical resistivity, which suggests CeFe2Al10 to be a Kondo semiconductor with a Kondo temperature much higher than 300 K.

Kawamura, Yukihiro; Edamoto, Shingo; Takesaka, Tomoaki; Nishioka, Takashi; Kato, Harukazu; Matsumura, Masahiro; Tokunaga, Yo; Kambe, Shinsaku; Yasuoka, Hiroshi

2010-10-01

119

Vibrate... Resonate... Quicken the Educational Experience into Intensest Life  

ERIC Educational Resources Information Center

In the quest for more effective education, how can direct personal engagement with actual aesthetic experiences--attendance of performances, participation in artistic workshops and activities, and viewing of actual artworks--play an important role? Art educators have a tremendous opportunity to guide students to engage mind, body, and soul--until…

Chin, Christina

2011-01-01

120

Isotope effect on the temperature dependence of the 35Cl NQR frequency in (NH4)2RuCl6  

NASA Astrophysics Data System (ADS)

The 35Cl nuclear quadrupole resonance frequencies and spin-lattice relaxation times for (NH4)2RuCl6, (ND4)2RuCl6, (NH4)2SnCl6, and (ND4)2SnCl6 were measured in the temperature range 4.2-300 K. In these four compounds, it was confirmed that no phase transition occurs in the observed temperature range. At 4.2 K, discrepancies of the NQR frequency between non-deuterated and deuterated compounds, which are attributed to the difference in the spatial distributions of hydrogen (deuterium) atoms in the ground states of the rotational motion of ammonium ion, reached to 24 kHz and 23 kHz for the ruthenate compounds and the stannate compounds, respectively. The separation between the ground and the first excited states of the rotational motion of the ammonium ion was estimated to be 466 J mol-1 and 840 J mol-1 for (ND4)2RuCl6 and (NH4)2RuCl6, respectively, by least-square fitting calculations of temperature dependence of the NQR frequency. For (ND4)2SnCl6 and (NH4)2SnCl6, these quantities were estimated to be 501 J mol-1 and 1544 J mol-1, respectively. It was clarified that the T1 minimum, which has been observed for the stannate compounds at around 60 K as a feature of the temperature dependence, was dependent on a method of sample preparation. It is concluded that the minimum is not an essential character of the ammonium hexachlorostannate(IV) since the crystals prepared in strong acid condition to prevent a partial substitution of chlorine atoms by hydroxyl groups, did not show such T1 minimum.

Kume, Yoshio; Amino, Daiki; Asaji, Tetsuo

2013-07-01

121

Antitank and Antipersonnel Mine Detection Test Results for a Nuclear Quadrupole Resonance Detection System.  

National Technical Information Service (NTIS)

This report summarizes the results of an interim test of a system that uses the nuclear quadrupole resonance (NQR) signature of explosives for the detection of antipersonnel (AP) and antitank (AT) land mines. The system, designed and built by Quantum Magn...

F. S. Rotondo E. Ayers

2000-01-01

122

Effects of Resonant Absorption in Direct-Drive Experiments on OMEGA  

NASA Astrophysics Data System (ADS)

The resonant absorption mechanism enhances laser absorption and can result in the generation of fast electrons in direct-drive experiments on OMEGA. These effects influence the shock timing and can modify the adiabat in imploded targets. The effects of resonant absorption in planar OMEGA experiments using the 1-D code LILAC are numerically studied. The code includes a direct solution of Maxwell's equations for the incident laser light. The simulation results indicate an important contribution of the resonance absorption during the first 100 to 200 ps regardless of the dissipation mechanisms of the absorbed laser energy near the critical surface. The results of the model will be presented and compared against the experimental data. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-92SF19460.

Igumenshchev, I. V.; Goncharov, V. N.; Smalyuk, V. A.; Seka, W.; Edgell, D. H.; Boehly, T. R.; Delettrez, J. A.

2006-10-01

123

Observation of Pure Resonance and Threshold Effects in Electron Impact Experiments in High Intensity Laser Fields.  

National Technical Information Service (NTIS)

This report describes experiments which were aimed to: 1) observe induced one photon free-free transitions associated with electron scattering by rare gas atoms in a CO2 laser field; 2) observe resonances in the free-free channel under experimental condit...

R. McAdams H. S. Taylor S. Trajmar

1984-01-01

124

Initial Experience with the Resonance Metallic Stent for Antegrade Ureteric Stenting  

Microsoft Academic Search

Background and purpose. We describe our initial experience with a new metallic ureteric stent which has been designed to provide long-term urinary drainage in patients with malignant ureteric strictures. The aim is to achieve longer primary patency rates than conventional polyurethane ureteric stents, where encrustation and compression by malignant masses limit primary patency. The Resonance metallic double-pigtail ureteric stent (Cook,

Tze M. Wah; Henry C. Irving; Jon Cartledge

2007-01-01

125

Temperature Effects on DNA Chip Experiments from Surface Plasmon Resonance Imaging: Isotherms and Melting Curves  

Microsoft Academic Search

We present an analysis of hybridization experiments on a DNA chip studied by surface plasmon resonance imaging. The reaction constants at various temperatures and for different probe lengths are obtained from Langmuir isotherms and hybridization kinetics. The melting curves from temperature scans are also obtained without any labeling of the targets. The effects of the probe length on the hybridization

J. B. Fiche; A. Buhot; R. Calemczuk; T. Livache

2007-01-01

126

Surgical experience of syringomyelia with reference to the findings of magnetic resonance imaging  

Microsoft Academic Search

We present our surgical experience of 20 patients with syringomyelia, who were divided into two groups based on the findings of magnetic resonance (MR) imaging: a “non-visible cisterna magna” group, in which MR imaging did not reveal cerebrospinal fluid (CSF) in the cisterna magna, and a “visible cisterna magna” group. Patients with non-visible cisterna magna were associated with Chiari malformation

Kazuhiko Kyoshima; Takayuki Kuroyanagi; Toshihide Toriyama; Takeomi Takizawa; Yunoshin Hirooka; Hiroshi Miyama; Akihiko Tanabe; Susumu Oikawa

2004-01-01

127

Ion Cyclotron Resonant Heating slot antenna for the Tandem Mirror Experiment-Upgrade  

SciTech Connect

The Ion Cyclotron Resonant Heating (ICRH) slot antenna has been a part of the ion and electron plasma heating system in the central cell region of the Tandem Mirror Experiment-Upgrade (TMX-U). This paper presents the mechanical design and arrangement of the antenna, coax feed lines, feedthroughs, and matching network for the slot antenna.

Brooksby, C.A.; Calderson, M.O.; Cummins, W.F.; Ferguson, S.W.; Williamson, V.L.

1985-11-14

128

Structural study of selected polyhalogenated benzimidazoles (protein kinase CK2 inhibitors) by nuclear quadrupole double resonance, X-ray, and density functional theory.  

PubMed

Protein kinase CK2 inhibitors, polyhalogenated benzimidazoles, have been studied experimentally in solid state by NMR-NQR double resonance and X-ray and theoretically by the density functional theory (DFT). Six resonance frequencies on (14)N have been detected and assigned to particular nitrogen sites in each polyhalogenated benzimidazole molecule. The effects of prototropic annular tautomerism and polymorphism related to stable cluster formation due to intermolecular hydrogen bonding interactions on the (14)N NQR parameters have been analyzed within the DFT and AIM (atoms in molecules) formalism. The studies suggest that all polyhalogenobenzimidazoles are isostructural and can exhibit polymorphism and that (14)N NQR is very sensitive to hydrogen bondings but less sensitive to the specific arrangement of the hydrogen bonded molecules. NQDR and DFT results suggest the presence of the prototropic annular tautomerism 50:50, which is in a good agreement with the X-ray and (1)H NMR data. PMID:20055520

Latosi?ska, J N; Latosi?ska, M; Seliger, J; Zagar, V; Maurin, J K; Orzeszko, A; Kazimierczuk, Z

2010-01-14

129

Resonance  

NSDL National Science Digital Library

All About Circuits is a website that âÂÂprovides a series of online textbooks covering electricity and electronics.â Written by Tony R. Kuphaldt, the textbooks available here are wonderful resources for students, teachers, and anyone who is interested in learning more about electronics. This specific section, Resonance, is the sixth chapter in the Volume II textbook. Topics covered in this chapter include: electric pendulum, simple parallel resonance, simple series resonance, resonance in series-parallel circuits, and Q and bandwidth of a resonant circuit. Diagrams and detailed descriptions of concepts are included throughout the chapter to provide users with a comprehensive lesson. Visitors to the site are also encouraged to discuss concepts and topics using the All About Circuits discussion forums (registration with the site is required to post materials).

Kuphaldt, Tony R.

2008-07-07

130

Structure and phase transition in bis(pyrrolidinium) hexachlorometallates, (C 4H 8NH 2) 2MCl 6 (M=Sn, Te and Pt), studied by X-ray diffraction, 35Cl NQR and DSC  

NASA Astrophysics Data System (ADS)

Single crystal X-ray diffraction, 35Cl nuclear quadrupole resonance (NQR) and differential scanning calorimetry (DSC) measurements were taken for bis(pyrrolidinium) hexachlorometallates, (C 4H 8NH 2) 2MCl 6 (M=Sn, Te and Pt). A solid-solid phase transition was observed at 150(1), 159(1) and 134(1) K for stannate, tellurate and platinate, respectively. 35Cl NQR signals were observed in stannate and platinate, both of which showed a two-line spectrum in the high-temperature phase and a three-line spectrum in the low-temperature phase. The high-temperature phases of the three complexes were found to be isostructural with each other belonging to the space group C2/ m (#12). The C 4H 8NH 2+ and MCl 62- ions are connected by N-H⋯Cl hydrogen bonds forming parallel sheets in the crystals. Disorder of the cation ring appears in these high-temperature phases. Semi-empirical MO calculations were performed to estimate the stable structure of the pyrrolidinium ion.

Ishida, H.; Furukawa, Y.; Sato, S.; Kashino, S.

2000-06-01

131

Frequencies of nuclear resonances for copper and electronic wave function of antiferromagnetic La2CuO4  

Microsoft Academic Search

Calculated values of the frequencies of nuclear magnetic and quadrupole resonances (for65Cuv(NMR) = 107 MHz, v(NQR) = 32 MHz) are close to the experimental values (100 MHz and 29.5 MHz). This coincidence is a reliable test of the obtained electronic wave function.

V. V. Flambaum; O. P. Sushkov

1990-01-01

132

Doubly excited resonances in the photoionization spectrum of Li+: experiment and theory  

NASA Astrophysics Data System (ADS)

Absolute cross-section measurements for resonant double photoexcitation of Li+ ions followed by autoionization have been performed at high resolution in the photon energy range from 148 eV, just below the (2s2p, 2(0, 1)n+) resonance, to 198 eV (the region of the double ionization threshold). The measurements have been made using the photon-ion merged-beam endstation at the Advanced Light Source, Lawrence Berkeley National Laboratory, USA. The absolute cross-section measurements show excellent agreement with theoretical results from the R-matrix plus pseudo-state (RMPS) method. Comparisons between theory and experiment for the Auger resonance energies, autoionization linewidth (?) and the Fano line profile index q for several members of the principal (2snp, 2(0, 1)n+) and (3snp, 3(1, 1)n+) Rydberg series found in the photoionization spectra for the 1Po symmetry show satisfactory accord.

Scully, S. W. J.; Álvarez, I.; Cisneros, C.; Emmons, E. D.; Gharaibeh, M. F.; Leitner, D.; Lubell, M. S.; Müller, A.; Phaneuf, R. A.; Püttner, R.; Schlachter, A. S.; Schippers, S.; Shi, W.; Ballance, C. P.; McLaughlin, B. M.

2006-09-01

133

Roles of the sodium-translocating NADH:quinone oxidoreductase (Na+-NQR) on vibrio cholerae metabolism, motility and osmotic stress resistance.  

PubMed

The Na+ translocating NADH:quinone oxidoreductase (Na+-NQR) is a unique respiratory enzyme catalyzing the electron transfer from NADH to quinone coupled with the translocation of sodium ions across the membrane. Typically, Vibrio spp., including Vibrio cholerae, have this enzyme but lack the proton-pumping NADH:ubiquinone oxidoreductase (Complex I). Thus, Na+-NQR should significantly contribute to multiple aspects of V. cholerae physiology; however, no detailed characterization of this aspect has been reported so far. In this study, we broadly investigated the effects of loss of Na+-NQR on V. cholerae physiology by using Phenotype Microarray (Biolog), transcriptome and metabolomics analyses. We found that the V. cholerae ?nqrA-F mutant showed multiple defects in metabolism detected by Phenotype Microarray. Transcriptome analysis revealed that the V. cholerae ?nqrA-F mutant up-regulates 31 genes and down-regulates 55 genes in both early and mid-growth phases. The most up-regulated genes included the cadA and cadB genes, encoding a lysine decarboxylase and a lysine/cadaverine antiporter, respectively. Increased CadAB activity was further suggested by the metabolomics analysis. The down-regulated genes include sialic acid catabolism genes. Metabolomic analysis also suggested increased reductive pathway of TCA cycle and decreased purine metabolism in the V. cholerae ?nqrA-F mutant. Lack of Na+-NQR did not affect any of the Na+ pumping-related phenotypes of V. cholerae suggesting that other secondary Na+ pump(s) can compensate for Na+ pumping activity of Na+-NQR. Overall, our study provides important insights into the contribution of Na+-NQR to V. cholerae physiology. PMID:24811312

Minato, Yusuke; Fassio, Sara R; Kirkwood, Jay S; Halang, Petra; Quinn, Matthew J; Faulkner, Wyatt J; Aagesen, Alisha M; Steuber, Julia; Stevens, Jan F; Häse, Claudia C

2014-01-01

134

Roles of the Sodium-Translocating NADH:Quinone Oxidoreductase (Na+-NQR) on Vibrio cholerae Metabolism, Motility and Osmotic Stress Resistance  

PubMed Central

The Na+ translocating NADH:quinone oxidoreductase (Na+-NQR) is a unique respiratory enzyme catalyzing the electron transfer from NADH to quinone coupled with the translocation of sodium ions across the membrane. Typically, Vibrio spp., including Vibrio cholerae, have this enzyme but lack the proton-pumping NADH:ubiquinone oxidoreductase (Complex I). Thus, Na+-NQR should significantly contribute to multiple aspects of V. cholerae physiology; however, no detailed characterization of this aspect has been reported so far. In this study, we broadly investigated the effects of loss of Na+-NQR on V. cholerae physiology by using Phenotype Microarray (Biolog), transcriptome and metabolomics analyses. We found that the V. cholerae ?nqrA-F mutant showed multiple defects in metabolism detected by Phenotype Microarray. Transcriptome analysis revealed that the V. cholerae ?nqrA-F mutant up-regulates 31 genes and down-regulates 55 genes in both early and mid-growth phases. The most up-regulated genes included the cadA and cadB genes, encoding a lysine decarboxylase and a lysine/cadaverine antiporter, respectively. Increased CadAB activity was further suggested by the metabolomics analysis. The down-regulated genes include sialic acid catabolism genes. Metabolomic analysis also suggested increased reductive pathway of TCA cycle and decreased purine metabolism in the V. cholerae ?nqrA-F mutant. Lack of Na+-NQR did not affect any of the Na+ pumping-related phenotypes of V. cholerae suggesting that other secondary Na+ pump(s) can compensate for Na+ pumping activity of Na+-NQR. Overall, our study provides important insights into the contribution of Na+-NQR to V. cholerae physiology.

Minato, Yusuke; Halang, Petra; Quinn, Matthew J.; Faulkner, Wyatt J.; Aagesen, Alisha M.; Steuber, Julia; Stevens, Jan F.; Hase, Claudia C.

2014-01-01

135

Use of the Carbonyl Chemical Shift to Relieve Degeneracies in Triple-Resonance Assignment Experiments  

NASA Astrophysics Data System (ADS)

We illustrate an approach that uses the backbone carbonyl chemical shift to relieve resonance overlaps in triple-resonance assignment experiments conducted on protein samples. We apply this approach to two cases of simultaneous overlaps: those of ( 1H N, 15N) spin pairs and those of ( 1H ?, 13C ?) spin pairs in residues preceding prolines. For these cases we employed respectively CBCACO(N)H and H(CA)CON experiments, simple variants of the commonly used CBCA(CO)NH and HCA(CO)N experiments obtained by replacing one of the indirect dimensions with a carbonyl dimension. We present data collected on ribosomal protein S4 using these experiments, along with overlap statistics for four other polypeptides ranging in size from 76 to 263 residues. These data indicate that the CBCACO(N)H, in combination with the CBCA(CO)NH, can relieve >83% of the ( 1H N, 15N) and ( 1H N, 13C') overlaps for these proteins. The data also reveal how the H(CA)CON experiment successfully completed the assignment of triply and quadruply degenerate X-Pro spin systems in a mobile, proline-rich region of S4, even when X was a glycine. Finally, we discuss the relative sensitivities of these experiments compared to those of existing sequences, an analysis that reinforces the usefulness of these experiments in assigning extensively overlapped and/or proline-rich sequences in proteins.

Sayers, Eric W.; Torchia, Dennis A.

2001-12-01

136

Initial Experience with the Resonance Metallic Stent for Antegrade Ureteric Stenting  

Microsoft Academic Search

Background and purpose  We describe our initial experience with a new metallic ureteric stent which has been designed to provide long-term urinary\\u000a drainage in patients with malignant ureteric strictures. The aim is to achieve longer primary patency rates than conventional\\u000a polyurethane ureteric stents, where encrustation and compression by malignant masses limit primary patency. The Resonance\\u000a metallic double-pigtail ureteric stent (Cook, Ireland)

Tze M. Wah; Henry C. Irving; Jon Cartledge

2007-01-01

137

Analysis of pulsed gradient nuclear magnetic resonance experiments using feedforward neural networks  

Microsoft Academic Search

Analysis of the data yielded by the pulsed-field-gradient nuclear magnetic resonance (NMR) experiment, which is used to measure self-diffusion coefficients of molecules, is problematic when the diffusion of the probe molecule is restricted by structural barriers. The solution of the diffusion equation for the particular arrangement of barriers and\\/or boundaries, in terms of the magnetization phase that is measured in

A. J. Lennon; P. W. Kuchel

1995-01-01

138

Low threshold parametric decay backscattering instability in tokamak electron cyclotron resonance heating experiments.  

PubMed

The experimental conditions leading to substantial reduction of the backscattering decay instability threshold in electron cyclotron resonance heating experiments in toroidal devices are analyzed. It is shown that a drastic decrease of threshold is provided by the nonmonotonic behavior of plasma density in the vicinity of magnetic island and poloidal magnetic field inhomogeneity making possible localization of ion Bernstein decay waves. The corresponding ion Bernstein wave gain and the parametric decay instability pump power threshold is calculated. PMID:20867578

Gusakov, E Z; Popov, A Yu

2010-09-10

139

Low-temperature nuclear quadrupole resonance studies of antimony and application to thermometry  

Microsoft Academic Search

The spin-lattice retaxation time, Tsb1, of finely divided powdered metallic antinomy immersed in liquid sp3He was measured using pulsed Nuclear Quadrupole Resonance (NQR) techniques. In this technique, the nuclear quadrupole resonant antinomy nuclei were saturated using an RF pulse. The recovery back to equilibrium was monitored using short inspection pulses and the magnetization recovery follows a recovery curve characterized by

Edgar Baylon Genio

1997-01-01

140

Nuclear quadrupole resonance of explosives: Simultaneous detection of RDX and PETN in semtex  

Microsoft Academic Search

We have used nuclear quadrupole resonance (NQR) for the detection of14N in explosives and introduce a new method for the simultaneous detection of the explosives cyclotrimethylene trinitramine\\u000a (RDX) and pentaerythritol tetranitrate (PETN). We have developed an interleaved pulse sequence, which provides efficient excitation\\u000a of both RDX and PETN, to drive a solenoid coil that is doubly resonant at 3.41 and

R. I. Jenkinson; J. M. Bradley; G. N. Shilstone

2004-01-01

141

Photoluminescence Enhancement by Surface-Plasmon Resonance: Recombination-Rate Theory and Experiments  

NASA Astrophysics Data System (ADS)

Recombination rates were experimented with in colloidal mixtures of semiconductor/metal nanoparticles, and calculated as a function of semiconductor-metal distance. Radiative recombination rates were evaluated from the electrodynamical interactions between single-dipole emitter and a metal nanoparticle, according to Mertens' 2007 model. Nonradiative recombination rates were obtained from the energy-transfer rate from a single exciton to the surface-plasmon band (analogous to Govorov's theory). This research verified that quantum-efficiency calculation based on carrier dynamics matches well with photoluminescence experiments by surface-plasmon resonance.

Nahm, Changwoo; Jung, Dae-Ryong; Kim, Jongmin; Nam, Seunghoon; Choi, Hongsik; Hong, Saeromi; Hwang, Taehyun; Moon, Taeho; Park, Byungwoo

2013-05-01

142

An accessible two-dimensional solution nuclear magnetic resonance experiment on human ubiquitin*.  

PubMed

Solution-state nuclear magnetic resonance (NMR) is an invaluable tool in structural and molecular biology research, but may be underutilized in undergraduate laboratories because instrumentation for performing structural studies of macromolecules in aqueous solutions is not yet widely available for use in undergraduate laboratories. We have implemented an experiment that is ideal for more commonly available 4.8-7.0 Tesla, double-channel NMR instruments that would not usually be used for biomolecular NMR work. We analyzed a commercially available, (15) N-enriched human ubiquitin sample with a two-dimensional correlation experiment using indirect (1) H evolution and direct (15) N detection, which produced spectra with high resolution on a spectrometer operating at 7.0 Tesla (300 MHz (1) H resonance frequency). The simplicity of the experiment makes it possible to be configured by undergraduate students with minimal supervision from the instructor. Students gain experience in acquiring multidimensional biomolecular NMR experiments, confirm that ubiquitin is stably folded, and observe the correspondence between specific signals and individual amino acids in ubiquitin. PMID:21638557

Rovnyak, David; Thompson, Laura E

2005-03-01

143

Resonance Frequency Tuning of a Double Ring Resonator in GaInAsP/InP: Experiment and Simulation  

NASA Astrophysics Data System (ADS)

A racetrack shaped double ring resonator (DRR) filter is demonstrated with radii of 200 ?m. The double ring resonator contains two -3 dB multimode interference (MMI) couplers for I/O coupling and a -13 dB codirectional coupler in between the rings. A free spectral range of 50 GHz has been realized. A simulation model has been developed to describe the DRR. As fabrication tolerances do not allow the realization of two identical rings with required nm-circumference accuracy in the resonator, a frequency alignment of the resonator is indispensable. The resonance frequency tuning is performed thermally using platinum resistors which have been placed on top of the waveguides in both rings. An on-off ratio increase has been achieved of more than 3 dB, resulting in a total on-off ratio larger than 18 dB. The frequency alignment is inevitable in the case of multiple coupled micro ring resonators.

Rabus, Dominik Gerhard; Hamacher, Michael; Heidrich, Helmut

2002-02-01

144

Sodium and potassium salts of dichloroisocyanuric acid and their hydrates as antimicrobials agents studied by 35Cl-NQR spectroscopy and DFT calculations  

Microsoft Academic Search

The electronic structure of dichloroisocyanuric acid derivatives was analysed by 35Cl-NQR spectroscopy and DFT calculations. Here we concentrate our attention on three different factors: type of metallic substituent (sodium and potassium), temperature of the sample (liquid nitrogen and room) and degree of hydration (an amount of water molecules attached to analysed compounds). In particular, all the variations in 35Cl-NQR frequencies

A. Walczak; B. Brycki; M. Kaczmarek; O. Kh. Poleshchuk; M. Ostafin; B. Nogaj

2006-01-01

145

Protein carbon-13 spin systems by a single two-dimensional nuclear magnetic resonance experiment  

SciTech Connect

By applying a two-dimensional double-quantum carbon-13 nuclear magnetic resonance experiment to a protein uniformly enriched to 26% carbon-13, networks of directly bonded carbon atoms were identified by virtue of their one-bond spin-spin couplings and were classified by amino acid type according to their particular single- and double-quantum chemical shift patterns. Spin systems of 75 of the 98 amino acid residues in a protein, oxidized Anabaena 7120 ferredoxin (molecular weight 11,000), were identified by this approach, which represents a key step in an improved methodology for assigning protein nuclear magnetic resonance spectra. Missing spin systems corresponded primarily to residues located adjacent to the paramagnetic iron-sulfur cluster. 25 references, 2 figures.

Oh, B.H.; Westler, W.M.; Darba, P.; Markley, J.L.

1988-05-13

146

Numerical experiment and analysis of the differential acoustic resonance spectroscopy for elastic property measurements  

NASA Astrophysics Data System (ADS)

Differential acoustic resonance spectroscopy (DARS) was recently developed to estimate the elastic parameters of rock samples with a resonant frequency perturbation caused by a test sample at kilohertz frequency. In the derivation of the DARS theory, the wave inside the cavity is assumed to be a harmonic acoustic plane wave, which may be a source of measurement errors. A simulation program may help researchers to understand the mechanism of this device and to find out whether the assumption in the theory derivation is correct. In this paper, we develop a simulation program based on the elastic wave equation in cylindrical coordinates, and model the DARS system. The modeled power spectrum agrees well with that obtained by the laboratory measurement. An analysis of the wave field snapshots and the pressure distribution curves shows that the standing wave inside the cavity along its long axis is asymmetrical. This study also investigates the relationships between the resonant frequencies and the density, the compressibility and the P-wave and S-wave velocities of the samples. By numerical experiments, this paper finds that only the compressibility can be estimated with the resonant frequency, when the sample is located at the velocity node. But when the sample is located at other positions, the P-wave and S-wave velocities can alter the shape of the vibration curve, though they have no impact on the resonant power spectrum. This implies that it may be possible to estimate the P-wave and S-wave velocities by using the full waveform of the vibration curve.

Dong, Chunhui; Wang, Shangxu; Zhao, Jianguo; Tang, Genyang

2013-10-01

147

Pressure-induced unconventional superconductivity in the heavy-fermion antiferromagnet CeIn3 : An In115 -NQR study under pressure  

NASA Astrophysics Data System (ADS)

We report on pressure-induced unconventional superconductivity (SC) in the heavy-fermion (HF) antiferromagnet CeIn3 by means of nuclear-quadrupole-resonance (NQR) studies conducted under a high pressure. The temperature (T) and pressure (P) dependences of the In-NQR spectra have revealed a first-order quantum-phase transition (QPT) from antiferromagnetism (AFM) to paramagnetism (PM) at a critical pressure Pc=2.46GPa at which AFM disappears with a minimum value of TN(Pc)=1.2K . High-energy x-ray scattering measurements under P show a progressive decrease in the lattice density without any change in the crystal structure, whereas an increase in the NQR frequency (?Q) indicates an increase in the hybridization between 4f electrons and conduction electrons, which stabilizes the HF-PM state. This competition between the AFM phase where TN is reduced and the formation of the HF-PM phase triggers the first-order QPT at Pc=2.46GPa . Despite the lack of an AFM quantum critical point in the P-T phase diagram, we highlight the fact that unconventional SC occurs in both phases of AFM and PM. The measurements of the nuclear spin-lattice relaxation rate 1/T1 in the AFM phase have provided evidence for the uniformly coexisting AFM+SC phase. Remarkably, the significant increase in 1/T1 upon cooling in the AFM phase has revealed the development of low-lying magnetic excitations down to Tc in the AFM phase; it is indeed relevant to the onset of the uniformly coexisting AFM+SC phase. In the HF-PM phase where AFM fluctuations are not developed, 1/T1 decreases without the coherence peak just below Tc , followed by a power-law-like T dependence that indicates an unconventional SC with a line-node gap. Remarkably, Tc has a peak around Pc in the HF-PM phase as well as in the AFM phase. In other words, an SC dome exists with a maximum value of Tc=230mK around Pc , indicating that the origin of the pressure-induced HF SC in CeIn3 is not relevant to AFM spin fluctuations but to the emergence of the first-order QPT in CeIn3 . These phenomena observed in CeIn3 should be understood in terms of the first-order QPT because these new phases of matter are induced by applying P . When the AFM critical temperature is suppressed at the termination point of the first-order QPT, Pc=2.46GPa , the diverging AFM spin-density fluctuations emerge at the critical point from AFM to PM. The results with CeIn3 leading to a new type of quantum criticality deserve further theoretical investigations.

Kawasaki, S.; Yashima, M.; Kitaoka, Y.; Takeda, K.; Shimizu, K.; Oishi, Y.; Takata, M.; Kobayashi, T. C.; Harima, H.; Araki, S.; Shishido, H.; Settai, R.; ?nuki, Y.

2008-02-01

148

You'll never crawl alone: neurophysiological evidence for experience-dependent motor resonance in infancy.  

PubMed

Lately, neuroscience is showing a great interest in examining the functional and neural mechanisms which support action observation and understanding. Recent studies have suggested that our motor skills crucially affect the way in which we perceive the actions generated by others, by showing stronger motor resonance for observation of actions that are established in one's motor repertoire. In the present study we extend previous findings that were based on expert motor skills in adults to the natural development of actions in infants. To investigate the effect of natural motor experience on motor resonance during action observation, 14- to 16-month-old infants' EEG was recorded during observation of action videos. Stronger mu- and beta-desynchronizations were found for observation of crawling compared to walking videos and the size of the effect was strongly related to the infant's own crawling experience. This suggests that already early in life one's own action experience is closely related to how actions of others are perceived. PMID:18760368

van Elk, M; van Schie, H T; Hunnius, S; Vesper, C; Bekkering, H

2008-12-01

149

Resonant X-ray Scattering Experiments on the Ordering of Electronic Degrees of Freedom  

NASA Astrophysics Data System (ADS)

Resonant X-ray scattering (RXS) has been developed as a powerful technique for observing orderings of electronic degrees of freedom: charge, spin, orbital, and multipoles. After a brief introduction of the RXS technique, we review some RXS experiments on the orderings in d and f electron systems with a strong correlation between electrons. The basic concept of RXS and the recent developments of the technique are described in this review paper. We also present future prospects of the studies using RXS for users.

Matsumura, Takeshi; Nakao, Hironori; Murakami, Youichi

2013-02-01

150

Limiting effects on laser compression by resonant backward Raman scattering in modern experiments  

SciTech Connect

Through resonant backward Raman scattering, the plasma wave mediates the energy transfer between long pump and short seed laser pulses. These mediations can result in pulse compression at extraordinarily high powers. However, both the overall efficiency of the energy transfer and the duration of the amplified pulse depend upon the persistence of the plasma wave excitation. At least with respect to the recent state-of-the-art experiments, it is possible to deduce that at present the experimentally realized efficiency of the amplifier is likely constrained mainly by two effects, namely, the pump chirp and the plasma wave wavebreaking.

Yampolsky, Nikolai A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Fisch, Nathaniel J. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States)

2011-05-15

151

M dependence in the analysis of NH3-He microwave double resonance experiments  

NASA Technical Reports Server (NTRS)

New close-coupled calculations of laboratory-frame, m-dependent cross sections for rotational excitation in NH3-He collisions are used to examined the validity of using degeneracy averaged values in the analysis of four-level double resonance experiments. It is found that the proper use of m-dependent cross sections and absorption probabilities produces only minor changes in the calculated Delta I/I (the fractional change in the signal absorption intensity when pumping radiation is applied) and does not, therefore, resolve the discrepancies between theoretical and experimental values that were noted in previous studies.

Davis, S. L.; Green, S.

1983-01-01

152

Experiences using 3-tesla magnetic resonance imaging in the treatment of Moyamoya disease  

Microsoft Academic Search

\\u000a \\u000a Purpose  To introduce our initial experiences using 3-tesla (3T) magnetic resonance (MR) imaging in the treatment of moyamoya disease\\u000a (MMD).\\u000a \\u000a \\u000a \\u000a Methods  3T MR imaging was used to study 63 consecutive patients with MMD. Evaluation of regional cerebral blood flow (rCBF) was performed\\u000a with 123IMP-SPECT or 15O2 gas steady-state PET. T2*-weighted gradient-echo imaging was used to study the incidence of asymptomatic cerebral microbleeds

Ken-ichiro Kikuta

153

First results of an auxiliary electron cyclotron resonance heating experiment in the GDT magnetic mirror  

NASA Astrophysics Data System (ADS)

The axially symmetric magnetic mirror device gas-dynamic trap (GDT, Budker Institute, Novosibirsk) has recently demonstrated a tangible increase in plasma electron temperature. According to laser scattering, a value of 0.4 keV has been achieved (a twofold increase). In addition to standard machine operation, utilizing a 5 MW neutral beam injection, a newly installed electron cyclotron resonance heating (ECRH) system was employed (54.5 GHz, 0.4 MW). The reported progress in electron temperature, along with previous experiments, which demonstrated plasma confinement at beta as high as 60%, is a significant advancement towards an energy efficient fusion neutron source based on GDT physics.

Bagryansky, P. A.; Kovalenko, Yu. V.; Savkin, V. Ya.; Solomakhin, A. L.; Yakovlev, D. V.

2014-08-01

154

Sparsely-sampled High-resolution 4-D Experiments for Efficient Backbone Resonance Assignment of Disordered Proteins  

PubMed Central

Intrinsically disordered proteins (IDPs) play important roles in many critical cellular processes. Due to their limited chemical shift dispersion, IDPs often require four pairs of resonance connectivities (H?, C?, C? and CO) for establishing sequential backbone assignment. Because most conventional 4-D triple-resonance experiments share an overlapping C? evolution period, combining existing 4-D experiments does not offer an optimal solution for non-redundant collection of a complete set of backbone resonances. Using alternative chemical shift evolution schemes, we propose a new pair of 4-D triple resonance experiments—HA(CA)CO(CA)NH/HA(CA)CONH—that complement the 4-D HNCACB/HN(CO)CACB experiments to provide complete backbone resonance information. Collection of high-resolution 4-D spectra with sparse sampling and FFT-CLEAN processing enables efficient acquisition and assignment of complete backbone resonances of IDPs. Importantly, because the CLEAN procedure iteratively identifies resonance signals and removes their associating aliasing artifacts, it greatly reduces the dependence of the reconstruction quality on sampling schemes and produces high-quality spectra even with less-than-optimal sampling schemes.

Wen, Jie; Wu, Jihui; Zhou, Pei

2011-01-01

155

Rabi and Larmor nuclear quadrupole double resonance of spin-1 nuclei.  

PubMed

We demonstrate the creation of two novel double-resonance conditions between spin-1 and spin-1/2 nuclei in a crystalline solid. Using a magnetic field oscillating at the spin-1/2 Larmor frequency, the nuclear quadrupole resonance (NQR) frequency is matched to the Rabi or Rabi plus Larmor frequency, as opposed to the Larmor frequency as is conventionally done. We derive expressions for the cross-polarization rate for all three conditions in terms of the relevant secular dipolar Hamiltonian, and demonstrate with these expressions how to measure the strength of the heterogenous dipolar coupling using only low magnetic fields. In addition, the combination of different resonance conditions permits the measurement of the spin-1/2 angular momentum vector using spin-1 NQR, opening up an alternate modality for the monitoring of low-field nuclear magnetic resonance. We use ammonium nitrate to explore these resonance conditions, and furthermore use the oscillating field to increase the signal-to-noise ratio per time by a factor of 3.5 for NQR detection of this substance. PMID:23231223

Prescott, D W; Malone, M W; Douglass, S P; Sauer, K L

2012-12-01

156

Doubly Excited Resonances in the Photoionization Spectrum of Li^+: experiment and theory  

NASA Astrophysics Data System (ADS)

Absolute cross-section measurements for resonant double photoexcitation of Li^+ ions followed by subsequent autoionization have been performed in the photon energy range from 148 eV, just below the (2s2p, 2(0,1)2^+) resonance to 198 eV (the region of the double ionization threshold) at high resolution. The measurements have been made using the photon-ion merged-beam endstation at the Advanced Light Source, Lawrence Berkeley National Laboratory. The absolute cross section measurements when compared with theoretical results from the R-matrix plus pseudo-state (RMPS) method show excellent agreement. Comparisons made between theory and experiment for the Auger resonance energies, autoionization linewidth (?) and the Fano line profile index q for several members of the principal (2snp, 2(0,1)n^+) and (3snp, 3(1,1)n^+) Rydberg series found in the photoionization spectra for the ^1P^o symmetry show suitable accord. Further details will be presented at the meeting.

Scully, S. W. J.; Emmons, E. D.; Gharaibeh, M. F.; Phaneuf, R. A.; Leitner, D.; Schlachter, A. S.; Müller, A.; Schippers, S.; Püttner, R.; Lubell, M. S.; Álvarez, I.; Cisneros, C.; Ballance, C. P.; McLaughlin, B. M.

2006-05-01

157

Conformational isomerism of methyl dichloroacetate. An infrared, Raman and 35Cl NQR study  

NASA Astrophysics Data System (ADS)

The IR and Raman spectra of methyl dichloroacetate (M-DCA) have been recorded on the liquid, glassy and crystalline states. The vibrational assignment for M-DCA is proposed on the basis of the spectral comparisons between CCl nH 3? n COOCH 3 and CCl nH 5? n CONHCH 5 ( n = 0-3) in the solid state. The observed spectral data indicate that M-DCA exists as a conformational equilibrium in the liquid and in the glassy state and that the conformation in the crystalline state is entirely different from those in the liquid and glassy states. The 35Cl NQR spectrum suggests that the conformation of M-DCA in the crystalline state is the cis form in which one of the two chlorine atoms is located in the cis position with respect to the carbonyl group. Examination of vibrational spectra also leads to the same conclusion.

Mido, Yoshiyuki; Hashimoto, Masao

1985-10-01

158

Initial Experience with the Resonance Metallic Stent for Antegrade Ureteric Stenting  

SciTech Connect

Background and purpose. We describe our initial experience with a new metallic ureteric stent which has been designed to provide long-term urinary drainage in patients with malignant ureteric strictures. The aim is to achieve longer primary patency rates than conventional polyurethane ureteric stents, where encrustation and compression by malignant masses limit primary patency. The Resonance metallic double-pigtail ureteric stent (Cook, Ireland) is constructed from coiled wire spirals of a corrosion-resistant alloy designed to minimize tissue in-growth and resist encrustation, and the manufacturer recommends interval stent change at 12 months. Methods. Seventeen Resonance stents were inserted via an antegrade approach into 15 patients between December 2004 and March 2006. The causes of ureteric obstruction were malignancies of the bladder (n = 4), colon (n = 3), gynecologic (n = 5), and others (n = 3). Results. One patient had the stent changed after 12 months, and 3 patients had their stents changed at 6 months. These stents were draining adequately with minimal encrustation. Four patients are still alive with functioning stents in situ for 2-10 months. Seven patients died with functioning stents in place (follow-up periods of 1 week to 8 months). Three stents failed from the outset due to bulky pelvic malignancy resulting in high intravesical pressure, as occurs with conventional plastic stents. Conclusion. Our initial experience with the Resonance metallic ureteric stent indicates that it may provide adequate long-term urinary drainage (up to 12 months) in patients with malignant ureteric obstruction but without significantly bulky pelvic disease. This obviates the need for regular stent changes and would offer significant benefit for these patients with limited life expectancy.

Wah, Tze M., E-mail: Tze.Wah@leedsth.nhs.uk; Irving, Henry C. [St. James's University Hospital, Department of Radiology (United Kingdom); Cartledge, Jon [St. James's University Hospital, Department of Urology (United Kingdom)

2007-07-15

159

Evidence for the microscopic coexistence of superconductivity and ferromagnetism in UGe2:73Ge-NMR/NQR study  

NASA Astrophysics Data System (ADS)

We report on the pressure-induced novel phases of ferromagnetism and superconductivity (SC) in the itinerant ferromagnet UGe2 via the 73Ge-NQR measurements under pressure ( P). The NQR spectrum has revealed that the ferromagnetic phases are separated into weakly and strongly polarized phases around a critical value of Pc*?1.2 GPa, pointing to a first-order transition around Pc*. Here we present further evidence for the phase separation into ferromagnetic and paramagnetic phases around a critical pressure Pc?1.6 GPa. The measurements of nuclear spin-lattice relaxation rate 1/T1 have probed that SC sets only in the ferromagnetic phase at Tsc?0.2 K, but it does not in the paramagnetic phase.

Harada, A.; Kotegawa, H.; Kawasaki, Y.; Zheng, G.-q.; Kitaoka, Y.; Yamamoto, E.; Haga, Y.; ?nuki, Y.; Itoh, K.; Haller, E. E.

2005-04-01

160

Solid-state NMR/NQR and first-principles study of two niobium halide cluster compounds.  

PubMed

Two hexanuclear niobium halide cluster compounds with a [Nb6X12](2+) (X=Cl, Br) diamagnetic cluster core, have been studied by a combination of experimental solid-state NMR/NQR techniques and PAW/GIPAW calculations. For niobium sites the NMR parameters were determined by using variable Bo field static broadband NMR measurements and additional NQR measurements. It was found that they possess large positive chemical shifts, contrary to majority of niobium compounds studied so far by solid-state NMR, but in accordance with chemical shifts of (95)Mo nuclei in structurally related compounds containing [Mo6Br8](4+) cluster cores. Experimentally determined ?iso((93)Nb) values are in the range from 2400 to 3000ppm. A detailed analysis of geometrical relations between computed electric field gradient (EFG) and chemical shift (CS) tensors with respect to structural features of cluster units was carried out. These tensors on niobium sites are almost axially symmetric with parallel orientation of the largest EFG and the smallest CS principal axes (Vzz and ?33) coinciding with the molecular four-fold axis of the [Nb6X12](2+) unit. Bridging halogen sites are characterized by large asymmetry of EFG and CS tensors, the largest EFG principal axis (Vzz) is perpendicular to the X-Nb bonds, while intermediate EFG principal axis (Vyy) and the largest CS principal axis (?11) are oriented in the radial direction with respect to the center of the cluster unit. For more symmetrical bromide compound the PAW predictions for EFG parameters are in better correspondence with the NMR/NQR measurements than in the less symmetrical chlorine compound. Theoretically predicted NMR parameters of bridging halogen sites were checked by (79/81)Br NQR and (35)Cl solid-state NMR measurements. PMID:24581866

Peri?, Berislav; Gautier, Régis; Pickard, Chris J; Bosio?i?, Marko; Grbi?, Mihael S; Požek, Miroslav

2014-01-01

161

Detection of {sup 14}N and {sup 35}Cl in cocaine base and hydrochloride using NQR, NMR, and SQUID techniques  

SciTech Connect

Results from {sup 14}N pure NQR of cocaine in the free base form (cocaine base) yield a nuclear quadrupole coupling constant (NQCC) e{sup 2}Qq/h of 5.0229 ({+-}0.0001) MHz and an asymmetry parameter {eta} of 0.0395 ({+-}0.0001) at 295 K, with corresponding values of 5.0460 ({+-}0.0013) MHz and 0.0353 ({+-}0.0008) at 77 K. Both pure NQR (at 295-77 K) and a superconducting quantum interference device (SQUID) detector (at 4.2 K) were used to measure the very low (<1 MHz) {sup 14}N transition frequencies in cocaine hydrochloride; at 295 K the NQCC is 1.1780 ({+-}0.0014) MHz and the asymmetry parameter is 0.2632 ({+-}0.0034). Stepping the carrier frequency enables one to obtain a powder pattern without the severe intensity distortions that otherwise arise from finite pulse power. A powder pattern simulation using an NQCC value of 5.027 MHz and an asymmetry parameter {eta} of 0.2 agrees reasonably well with the experimental stepped-frequency spectrum. The use of pure NQR for providing nondestructive, quantitative, and highly specific detection of crystalline compounds is discussed, as are experimental strategies. 31 refs., 8 figs., 1 tab.

Yesinowski, J.P.; Buess, M.L.; Garroway, A.N. [Naval Research Lab., Washington, DC (United States); Ziegeweid, M.; Pines, A. [Univ. of California, Berkeley, CA (United States)]|[Lawrence Berkeley Lab., CA (United States)

1995-07-01

162

On-line kinetic model discrimination for optimized surface plasmon resonance experiments.  

PubMed

In order to improve the throughput of surface plasmon resonance-based biosensors, an on-line iterative optimization algorithm has been presented aiming at reducing experimental time and material consumption without any loss of confidence on kinetic parameters [De Crescenzo (2008) J. Mol Recognit., 21, 256-66.]. This algorithm was based on a simple Langmuirian model to compute the confidence and predict optimal injections. However, this kinetic model is not suitable for all interactions, as it does not include mass transfer limitation that may occur for fast interaction kinetics. If a simple model was to be used when this phenomenon influenced the interactions, kinetic parameters would be biased. On the other hand, we show in this paper that data analysis with a kinetic model including a mass transfer limitation step would lead to longer experiments and poorer confidence if the interactions were simple. So, in this manuscript, we present an on-line model discrimination and optimization approach to increase the throughput of surface plasmon resonance biosensors. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24700594

Mehand, Massinissa Si; Crescenzo, Gregory De; Srinivasan, Bala

2014-05-01

163

Focal magnetic resonance guided focused ultrasound for prostate cancer: Initial North American experience  

PubMed Central

The treatment of low-risk prostate cancer is a common clinical dilemma between standard curative whole gland therapy (and its associated quality of life diminishing side effects) and active surveillance (and its low, but real, risk of progression). The goal of focal therapy in low-risk prostate cancer is to achieve the best balance between cancer control and maintenance of quality of life. Magnetic resonance-guided focused ultrasound (MRgFUS) surgery is a non-invasive thermal ablation method that integrates magnetic resonance imaging for target identification, treatment planning and closed-loop control of thermal deposition and focused ultrasound for thermal ablation of the tumour target. This novel transrectal system allows for tumour localization, targeting and monitoring of tumour target ablation in real time, while simultaneously preserving adjacent normal tissue thereby minimizing the side effects of standard curative surgical or radiation therapy. We report the first North American clinical experience of treatment of localized prostate cancer with focal MR-guided transrectal focused ultrasound (clinicaltrial.gov identifier NCT01226576).

Lindner, Uri; Ghai, Sangeet; Spensieri, Paula; Hlasny, Eugen; Van der Kwast, Theodorus H.; McCluskey, Stuart A.; Haider, Masoom A.; Kucharczyk, Walter; Trachtenberg, John

2012-01-01

164

Anxious and non-anxious adolescents' experiences of non-clinical magnetic resonance imaging research.  

PubMed

Magnetic resonance imaging (MRI) has become a ubiquitous research tool for developmental neuroscientists interested in brain structure and function in children and adolescents. However, ethical concerns are sometimes raised about using MRI with children and adolescents, especially when participants have anxiety. We asked 17 clinically/sub-clinically anxious and 19 non-anxious adolescents about their experiences of taking part in MRI for research purposes. Although the anxious group reported experiencing more anxiety during the scan, these differences had attenuated by the time participants got home. We found no evidence that anxious adolescents would be less likely to choose to have another scan or would feel more nervous during another scan. There was some evidence that more trait anxious adolescents found the MRI study enjoyable. These findings should give ethics committees, clinicians, and parents confidence that so long as researchers exercise appropriate care, MRI research is acceptable to adolescents, including those with clinical anxiety. PMID:23232793

Haddad, Anneke D M; Platt, Belinda; James, Anthony C; Lau, Jennifer Y F

2013-08-01

165

Space Time Reversal Experiment by Use of Pulsed Neutron Ramsey Resonance  

SciTech Connect

We have developed a pulsed neutron Ramsey resonance for a T-violation experiment on polarized neutron transmission through a polarized nuclear target. Two separated oscillatory fields were placed in a pulsed neutron beam line, which were synchronized with a neutron pulse for precision neutron spin manipulation. We observed neutron Larmor precession between the two oscillatory fields as a function of a neutron time of flight (TOF). We modulated the phase of the second oscillatory field with respect to the first oscillatory field. The effect of the phase modulation was found in a neutron intensity modulation as a function of the TOF. From the neutron intensity modulation, the neutron spin direction as well as the neutron velocity between the two oscillatory fields was precisely obtained.

Masuda, Y.; Jeong, S. C.; Watanabe, Y. [Institute of Particle and Nuclear Studies, KEK, Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Skoy, V. [Joint Institute for Nuclear Research, 14980 Dubna Moscow Region (Russian Federation); Ino, T. [Institute of Material Structure Science, KEK, Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan)

2007-06-13

166

Magnetic resonance imaging (MRI): method and early clinical experiences in diseases of the central nervous system.  

PubMed

Magnetic resonance imaging (MRI) has undergone a rapid development which is still continuing. In this article a survey is given of the present status of this new diagnostic tool in the evaluation of diseases of the central nervous system. When atoms with uneven numbers of protons or neutrons in a homogeneous magnetic field are tilted against the main vector of this field by a radiofrequency pulse, nuclear magnetic resonance can be observed. During the relaxation of the little dipoles back to the direction of the underlying magnetic field, a resonance signal is generated. The superposition of variable field gradients enables the scanning of sectional images in the axial, frontal and sagittal plane. The variables of H+-magnetic resonance which can be utilized for imaging are: the proton density, the relaxation times T1 (spin-lattice) and T2 (spin-spin) and flow effects. While the proton density in organic tissue fluctuates only by some 10%, the relaxation times may vary by several hundred per cent. Tissue contrast, therefore, is mainly based on relaxation times differences. The image character can also be influenced by variations of imaging parameters (i.e. repetition rate, interpulse delay, read out or echo delay) in different imaging sequences, such as the spin-echo and the inversion recovery technique. Depending on these imaging parameters T1 and T2 will contribute to the signal to a varying degree. This fact is most important for the diagnostic information of MRI. In initial clinical experiences in the diagnosis of diseases of the central nervous system, MRI has demonstrated high sensitivity in the detection of lesions (such as oedema, neoplasms, demyelinating disease), but less significance in lesion discrimination. In spinal disease the direct sagittal imaging of MRI enables MRI-myelography without contrast medium, superior to conventional myelography in many cases. For detailed evaluation of disc disease, however, the spatial resolution still has to be improved. Promising results have been obtained from flow effects. Depending on the flow velocity of blood, vessels appear white with intensive signals (slow flow) or black due to low signal intensities (rapid flow). MRI-angiography including measurement of blood flow seems possible. MRI-contrast media are not yet available for routine clinical use. Promising results have been reported on the basis of rare-earth elements, such as gadolinium Gd3+. These substances decrease T1 and T2 with subsequent increase in signal intensity. Concerning harmful side-effects of MRI, three possible sources have to be considered: the static magnetic field, the changing magnetic field, and radiofrequency heating.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:6397697

Huk, W J; Gademann, G

1984-01-01

167

Detailed design of a resonantly enhanced axion-photon regeneration experiment  

SciTech Connect

A resonantly enhanced photon-regeneration experiment to search for the axion or axionlike particles is described. This experiment is a shining light through walls study, where photons traveling through a strong magnetic field are (in part) converted to axions; the axions can pass through an opaque wall and convert (in part) back to photons in a second region of strong magnetic field. The photon regeneration is enhanced by employing matched Fabry-Perot optical cavities, with one cavity within the axion generation magnet and the second within the photon-regeneration magnet. Compared to simple single-pass photon regeneration, this technique would result in a gain of (F/{pi}){sup 2}, where F is the finesse of each cavity. This gain could feasibly be as high as 10{sup 10}, corresponding to an improvement in the sensitivity to the axion-photon coupling, g{sub a{gamma}}{sub {gamma}}, of order (F/{pi}){sup 1/2}{approx}300. This improvement would enable, for the first time, a purely laboratory experiment to probe axion-photon couplings at a level competitive with, or superior to, limits from stellar evolution or solar axion searches. This report gives a detailed discussion of the scheme for actively controlling the two Fabry-Perot cavities and the laser frequencies, and describes the heterodyne signal detection system, with limits ultimately imposed by shot noise.

Mueller, Guido; Sikivie, Pierre; Tanner, D. B.; Bibber, Karl van [Department of Physics, University of Florida, Gainesville, Florida 32611 (United States); Naval Postgraduate School, Monterey, California 93943 (United States)

2009-10-01

168

Detection of plastic explosives in luggage with 14 N nuclear quadrupole resonance spectroscopy  

Microsoft Academic Search

Nuclear quadrupole resonance (NQR) of14N nuclei has many advantages as a method for detecting nitrogen-containing explosives, the most important are very high chemical\\u000a specificity, true noninvasive operation and detection of bulk explosive in situ only (no vapor or particular capture needed).\\u000a One of the most high explosives is hexogen (RDX) often used by terrorists in plasticized forms. The ring nitrogen

M. Ostafin; B. Nogaj

2000-01-01

169

Robust optimal design of diffusion-weighted magnetic resonance experiments for skin microcirculation  

NASA Astrophysics Data System (ADS)

Skin microcirculation plays an important role in several diseases including chronic venous insufficiency and diabetes. Magnetic resonance (MR) has the potential to provide quantitative information and a better penetration depth compared with other non-invasive methods such as laser Doppler flowmetry or optical coherence tomography. The continuous progress in hardware resulting in higher sensitivity must be coupled with advances in data acquisition schemes. In this article, we first introduce a physical model for quantifying skin microcirculation using diffusion-weighted MR (DWMR) based on an effective dispersion model for skin leading to a q-space model of the DWMR complex signal, and then design the corresponding robust optimal experiments. The resulting robust optimal DWMR protocols improve the worst-case quality of parameter estimates using nonlinear least squares optimization by exploiting available a priori knowledge of model parameters. Hence, our approach optimizes the gradient strengths and directions used in DWMR experiments to robustly minimize the size of the parameter estimation error with respect to model parameter uncertainty. Numerical evaluations are presented to demonstrate the effectiveness of our approach as compared to conventional DWMR protocols.

Choi, J.; Raguin, L. G.

2010-10-01

170

Observations of noise bands associated with the upper hybrid resonance by the Imp 6 radio astronomy experiment  

Microsoft Academic Search

The intense noise bands occurring near the upper hybrid resonanace ; frequency have been observed with the Imp 6 GSFC radio astronomy experiment in ; the plasmasphere. The identification of the upper hybrid resonance provides an ; accurate measure of the local electron density and allows the observed noise data ; to be fit to the scale of characteristic frequencies

Stephen R. Mosier; Michael L. Kaiser; L. W. Brown

1973-01-01

171

On the second harmonic electron cyclotron resonance heating and current drive experiments on T-10 and D3-D  

Microsoft Academic Search

Studies of electron cyclotron current drive at the second harmonic resonance have been performed both on the D3-D and T-10 tokamaks at injected power levels of approximately 0.5 MW. The D3-D experiment used high held launch of the extraordinary mode at an angle of 15 deg to the radial. In this experiment, with pulse lengths approximately equal to 500 msec,

J. Lohr; C. B. Forest; Y. R. Lin-Liu; T. C. Luce; R. W. Harvey; E. A. Downs; R. A. James; A. A. Bagdasarov; A. A. Borshegovskii; V. V. Chistyakov; M. M. Dremin; A. V. Gorshkov; Y. A. Gorelov; Y. V. Esipchuk; N. V. Ivanov; A. Y. Kislov; D. A. Kislov; S. E. Lysenko; A. A. Medvedev; V. Y. Mirenskii; G. E. Notkin; V. V. Parail; Y. D. Pavlov; K. A. Razumova; I. N. Roi; P. V. Savrukhin; V. V. Sannikov; A. V. Sushkov; V. M. Trukhin; N. L. Vasin; V. V. Volkov; G. G. Denisov; M. I. Petelin; V. A. Flyagin

1993-01-01

172

Sodium and potassium salts of dichloroisocyanuric acid and their hydrates as antimicrobials agents studied by 35Cl-NQR spectroscopy and DFT calculations  

NASA Astrophysics Data System (ADS)

The electronic structure of dichloroisocyanuric acid derivatives was analysed by 35Cl-NQR spectroscopy and DFT calculations. Here we concentrate our attention on three different factors: type of metallic substituent (sodium and potassium), temperature of the sample (liquid nitrogen and room) and degree of hydration (an amount of water molecules attached to analysed compounds). In particular, all the variations in 35Cl-NQR frequencies upon hydration of salts containing sodium and potassium ions are explained as a consequence of H-bonds formation and accompanied effects of charge redistribution. Our studies can be useful in searching for the derivatives of dichloroisocyanuric acid revealing higher antimicrobial activity.

Walczak, A.; Brycki, B.; Kaczmarek, M.; Poleshchuk, O. Kh.; Ostafin, M.; Nogaj, B.

2006-06-01

173

Experiments with biased side electrodes in electron cyclotron resonance ion sources.  

PubMed

The output of highly charged ions from an electron cyclotron resonance ion source (ECRIS) consists of ionic losses from a highly confined plasma. Therefore, an increase of the output of the ions of interest always is a compromise between an increase in the confinement and an increase of the losses. One route towards a solution consists of attacking the losses in directions - i.e., radial directions - that do not contribute to the required output. This was demonstrated in an experiment (using the Kei ECRIS at NIRS, Japan) where radial losses were electrostatically reduced by positively biasing one set of six "side" electrodes surrounding the plasma in side-ward directions attached (insulated) to the cylindrical wall of the plasma chamber. Recently new studies were performed in two laboratories using two essentially different ion sources. At the BioNano ECRIS (Toyo University, Japan) various sets of electrodes were used; each of the electrodes could be biased individually. At the Atomki ECRIS (Hungary), one movable, off-axis side electrode was applied in technically two versions. The measurements show indeed a decrease of ionic losses but different effectivities as compared to the biased disk. PMID:24593500

Drentje, A G; Kitagawa, A; Uchida, T; Rácz, R; Biri, S

2014-02-01

174

Optimizing ion-cyclotron resonance frequency heating for ITER: dedicated JET experiments  

NASA Astrophysics Data System (ADS)

In the past years, one of the focal points of the JET experimental programme was on ion-cyclotron resonance heating (ICRH) studies in view of the design and exploitation of the ICRH system being developed for ITER. In this brief review, some of the main achievements obtained in JET in this field during the last 5 years will be summarized. The results reported here include important aspects of a more engineering nature, such as (i) the appropriate design of the RF feeding circuits for optimal load resilient operation and (ii) the test of a compact high-power density antenna array, as well as RF physics oriented studies aiming at refining the numerical models used for predicting the performance of the ICRH system in ITER. The latter include (i) experiments designed for improving the modelling of the antenna coupling resistance under various plasma conditions and (ii) the assessment of the heating performance of ICRH scenarios to be used in the non-active operation phase of ITER.

Lerche, E.; Van Eester, D.; Ongena, J.; Mayoral, M.-L.; Laxaback, M.; Rimini, F.; Argouarch, A.; Beaumont, P.; Blackman, T.; Bobkov, V.; Brennan, D.; Brett, A.; Calabro, G.; Cecconello, M.; Coffey, I.; Colas, L.; Coyne, A.; Crombe, K.; Czarnecka, A.; Dumont, R.; Durodie, F.; Felton, R.; Frigione, D.; Gatu Johnson, M.; Giroud, C.; Gorini, G.; Graham, M.; Hellesen, C.; Hellsten, T.; Huygen, S.; Jacquet, P.; Johnson, T.; Kiptily, V.; Knipe, S.; Krasilnikov, A.; Lamalle, P.; Lennholm, M.; Loarte, A.; Maggiora, R.; Maslov, M.; Messiaen, A.; Milanesio, D.; Monakhov, I.; Nightingale, M.; Noble, C.; Nocente, M.; Pangioni, L.; Proverbio, I.; Sozzi, C.; Stamp, M.; Studholme, W.; Tardocchi, M.; Versloot, T. W.; Vdovin, V.; Vrancken, M.; Whitehurst, A.; Wooldridge, E.; Zoita, V.; EFDA Contributors, JET

2011-12-01

175

Optimization of nonlinear hyperelastic coefficients for foot tissues using a magnetic resonance imaging deformation experiment.  

PubMed

Accurate prediction of plantar shear stress and internal stress in the soft tissue layers of the foot using finite element models would provide valuable insight into the mechanical etiology of neuropathic foot ulcers. Accurate prediction of the internal stress distribution using finite element models requires that realistic descriptions of the material properties of the soft tissues are incorporated into the model. Our investigation focused on the creation of a novel three-dimensional (3D) finite element model of the forefoot with multiple soft tissue layers (skin, fat pad, and muscle) and the development of an inverse finite element procedure that would allow for the optimization of the nonlinear elastic coefficients used to define the material properties of the skin muscle and fat pad tissue layers of the forefoot based on a Ogden hyperelastic constitutive model. Optimization was achieved by comparing deformations predicted by finite element models to those measured during an experiment in which magnetic resonance imaging (MRI) images were acquired while the plantar surface forefoot was compressed. The optimization procedure was performed for both a model incorporating all three soft tissue layers and one in which all soft tissue layers were modeled as a single layer. The results indicated that the inclusion of multiple tissue layers affected the deformation and stresses predicted by the model. Sensitivity analysis performed on the optimized coefficients indicated that small changes in the coefficient values (±10%) can have rather large impacts on the predicted nominal strain (differences up to 14%) in a given tissue layer. PMID:23699713

Petre, Marc; Erdemir, Ahmet; Panoskaltsis, Vassilis P; Spirka, Thomas A; Cavanagh, Peter R

2013-06-01

176

Interstitial magnetic resonance lymphography with gadobutrol in rabbits and an initial experience in humans.  

PubMed

The purpose of this study was first to evaluate gadobutrol as a contrast agent for interstitial Magnetic Resonance Lymphography (MRL) in rabbits, and second, to extend the study to humans, if the initial results were satisfactory. In our experiment, gadobutrol was injected into twelve white New Zealand rabbits. In nine animals, 0.5 ml of gadobutrol was subcutaneously administered through each foot pad of the hindlegs while in the remaining three animals the agent was given in each foot of the forelegs. In four of the nine rabbits, slight local massage was applied at the site of administration. Subsequently, we proceeded to administer 5 ml (4.5 ml gadobutrol mixed with 0.5 ml hydrochloride lidocaine) into the limbs of two healthy humans. We achieved imaging of four lymph node groups (popliteal, inguinal, iliac and paraortic) in the hind-legs of the nine-rabbit group, whereas, in the forelegs of the remaining three rabbits, three lymph node groups (axillary, parasternal, mediastinal) were depicted. The flow of the contrast agent was significantly faster in the rabbits that received local massage (P<0.02). In humans, normal lymph vessels, as well as inguinal lymph nodes, were depicted in the legs. No side-effects were observed either in the rabbits or humans. PMID:17319627

Dimakakos, E; Koureas, A; Skiadas, V; Kostapanagiotou, G; Katsenis, K; Arkadopoulos, N; Giannopoulos, A; Gouliamos, A; Vlahos, L

2006-12-01

177

Measurements of radial profiles of ion cyclotron resonance heating on the tandem mirror experiment  

SciTech Connect

A small Radial Energy Analyzer (REA) was used on the Tandem Mirror Experiment-Upgrade (TMX-U), at Lawrence Livermore National Laboratory, to investigate the radial profiles of ion temperature, density, and plasma potential during Ion Cyclotron Resonance Heating (ICRH). This analyzer indicates an increase in ion temperature from {approx}20 eV before ICRH to {approx}150 eV during ICRH, with {approx}60 kW of broadcast power. The REA measurements were cross-checked against other diagnostics on TMX-U and found to be consistent. The ion density measurement was compared to the line-density measured by microwave interferometry and found to agree within 10 to 20%. A radial integral of n{sub i}T{sub i} as measured by the REA shows good agreement with the diamagnetic loop measurement of plasma energy. The radial density profile is observed to broaden during the RF heating pulses, without inducing additional radial losses in the core plasma. The radial profile of plasma potential is seen to vary from axially peaked, to nearly flat, as the plasma conditions varied over the series of experiments. To relate the increase in ion temperature to power absorbed by the plasma, a power balance as a function of radius was performed. The RF power absorbed is set equal to the sum of the losses during ICRH, minus those without ICRH. This method accounts for more than 70% of the broadcast power using a simple power balance model. The measured radial profile of the RF heating was compared to the calculations of two codes, ANTENA and GARFIELD, to test their effectiveness as predictors of power absorption profiles for TMX-U.

Falabella, S.

1988-01-01

178

Measurements of radial profiles of ion cyclotron resonance heating on the Tandem Mirror Experiment-Upgrade  

SciTech Connect

A small Radial Energy Analyzer (REA) was used on the Tandem Mirror Experiment-Upgrade (TMX-U), at Lawerence Livermore National Laboratory, to investigate the radial profiles of ion temperature, density, and plasma potential during Ion Cyclotron Resonance Heating (ICRH). The probe has been inserted into the central-cell plasma at temperatures of 200 eV and densities of 3 x 10/sup 12/cm/sup /minus 3// without damage to the probe, or major degradation of the plasma. This analyzer has indicated an increase in ion temperature from near 20 eV before ICRH to near 150 eV during ICRH, with about 60 kW of broadcast power. The REA measurements were cross-checked against other diagnostics on TMX-U and found to be consistent. The ion density measurement was compared to the line-density measured by microwave interferometry and found to agree within 10 to 20%. A radial intergral of n/sub i/T/sub i/ as measured by the REA shows good agreement with the diamagnetic loop measurement of plasma energy. The radial density profile is observed to broaden during the RF heating pulses, without inducing additional radial losses in the core plasma. The radial profile of plasma is seen to vary from axially peaked, to nearly flat as the plasma conditions carried over the series of experiments. To relate the increase in ion temperature to power absorbed by the plasma, a power balance as a function of radius was performed. The RF power absorbed is set equal to the sum of the losses during ICRH, minus those without ICRH. This method accounts for more than 70% of the broadcast power using a simple power balance model. The measured radial profile of the RF heating was compared to the calculations of two codes, ANTENA and GARFIELD, to test their effectiveness as predictors of power absorption profiles for TMX-U. 62 refs., 63 figs., 7 tabs.

Falabella, S.

1988-05-11

179

Generating positive contrast from off-resonant spins with steady-state free precession magnetic resonance imaging: theory and proof-of-principle experiments  

NASA Astrophysics Data System (ADS)

It is well known that magnetic susceptibility variations lead to signal voids in MRI. However, recent work has shown that positive-contrast imaging of susceptibility-induced field variations can provide signal enhancements rather than signal losses. In this paper, we propose a new method for generating positive contrast from off-resonant spins with steady-state free precession (SSFP) magnetic resonance imaging. Based on theory and experiments, we demonstrate that positive-contrast images can be acquired in the presence of susceptibility-shift media with low flip angle excitations that are determined by the spin relaxation time constants of the imaging medium. Compared to other techniques, this technique is substantially faster and has low specific absorption rates, permitting high-field imaging. In addition to acquiring positive-contrast images, we also show that it is possible to suppress the imaging medium to desired levels; thereby allowing for simultaneous registration of the background details surrounding the susceptibility-shift media. Among practical applications, we anticipate that the proposed technique can potentially facilitate high field magnetic-resonance-based molecular imaging.

Dharmakumar, Rohan; Koktzoglou, Ioannis; Li, Debiao

2006-09-01

180

Injection Seeding of Ti:Al2O3 in an unstable resonator theory and experiment  

NASA Technical Reports Server (NTRS)

Injection Seeding of a Ti:Al2O3 unstable resonator using both a pulsed single-mode Ti:Al2O3 laser and a continuous wave laser diode has been characterized. Results are compared with a theory which calculates injection seeding as function of seed and resonator alignment, beam profiles, and power.

Barnes, J. C.; Wang, L. G.; Barnes, N. P.; Edwards, W. C.; Cheng, W. A.; Hess, R. V.; Lockard, G. E.; Ponsardin, P. L.

1991-01-01

181

Using split-ring resonators to measure the electromagnetic properties of materials: An experiment for senior physics undergraduates  

NASA Astrophysics Data System (ADS)

A spilt-ring resonator experiment suitable for senior physics undergraduates is described and demonstrated in detail. The apparatus consists of a conducting hollow cylinder with a narrow slit along its length and can be accurately modelled as a series LRC circuit. The resonance frequency and quality factor of the split-ring resonator are measured when the apparatus is suspended in air, submerged in water, and submerged in an aqueous solution of various concentrations of NaCl. The experimental results are used to extract the dielectric constant of water and to investigate the dependence of the resonator quality factor on the conductivity of the NaCl solution. The apparatus provides opportunities to experimentally examine radiative losses, complex permittivity, the electromagnetic skin depth, and cutoff frequencies of rf propagation in cylindrical waveguides, which are all concepts introduced in an undergraduate course in electrodynamics. To connect with current research, the use of split-ring resonators as a tool to precisely measure the electromagnetic properties of materials is emphasized.

Bobowski, J. S.

2013-12-01

182

The performance of magnetic resonance imaging in early cervical carcinoma: a long-term experience.  

PubMed

We report our long-term experience of performance of magnetic resonance imaging (MRI) in localizing cervical tumor, assessing tumor size, staging, and lymph node infiltration in patients with early cervical cancer. MRI of 150 patients with early carcinoma between 1995-2005 was retrospectively reviewed. Tumor location, size, tumor distance from internal os, parametrial invasion, myometrial invasion, lymph node size, and location were documented. All patients underwent surgery, pelvic lymphadenectomy, and histological correlation of MRI findings. For staging, MRI and histopathology had kappa value of 0.89. For parametrial invasion, MRI had specificity, negative predictive value (NPV) of 97% and 100%, respectively. For tumor size, MRI and histology had mean difference of -0.9 mm with 95% limits of agreement between -12.6 to +13 mm. In tumors greater than 10 mm, mean difference was 0.3 mm and limits of agreement were -7.5 to +7.9 mm. For internal os involvement sensitivity, specificity, positive predictive value (PPV) and NPV were 90%, 98%, 86%, 98%. respectively. For myometrial invasion sensitivity, specificity, NPV, and PPV were 100%, 99%, 88%, 100%, respectively. Incidence of nodal metastases was 2.9%. On a per-patient basis, sensitivity, specificity for nodal involvement was 37% and 92% and on node-by-node basis, sensitivity and specificity of MRI was 27% and 99%, respectively. Our study confirms MRI is highly accurate in localizing cervical tumor, excluding parametrial invasion, confirming myometrial and internal os invasion. MRI is therefore useful in selecting patients for surgery and mandatory in patients for fertility-preserving surgery. Using accepted size criteria for nodal involvement, MRI is insensitive and currently will not avoid need for pelvic lymphadenectomy. PMID:17309561

Sahdev, A; Sohaib, S A; Wenaden, A E T; Shepherd, J H; Reznek, R H

2007-01-01

183

Evidence for Uniform Coexistence of Ferromagnetism and Unconventional Superconductivity in UGe2: A 73Ge-NQR Study under Pressure  

NASA Astrophysics Data System (ADS)

We report on the itinerant ferromagnetic superconductor UGe2 through 73Ge-NQR measurements under pressure (P). The P dependence of the NQR spectrum signals a first-order transition from the low-temperature (T) and low-P ferromagnetic phase (FM2) to high-T and high-P one (FM1) around a critical pressure of Px ˜ 1.2 GPa. The superconductivity exhibiting a maximum value of Tsc=0.7 K at Px ˜ 1.2 GPa, was found to take place in connection with the P-induced first-order transition. The nuclear spin-lattice relaxation rate 1/T1 has probed the ferromagnetic transition, exhibiting a peak at the Curie temperature as well as a decrease without the coherence peak below~Tsc. These results reveal the uniformly coexistent phase of ferromagnetism and unconventional superconductivity with a line--node gap. We remark on an intimate interplay between the onset of superconductivity and the underlying electronic state for the ferromagnetic phases.

Kotegawa, H.; Harada, A.; Kawasaki, S.; Kawasaki, Y.; Kitaoka, Y.; Haga, Y.; Yamamoto, E.; ?nuki, Y.; Itoh, K. M.; Haller, E. E.; Harima, H.

2005-02-01

184

N.Q.R measurements of low energy Chiral structures in powdered glassy As2Se3  

NASA Astrophysics Data System (ADS)

Experimental and theoretical work on the As-chalcogen glasses have shown that in the glassy state the local cylindrical symmetry associated with the elemental pyramidal unit is preserved. Here we introduce a local paracrystalline model of glassy As2Se3. This model is based on a tight binding calculation of the electric field gradient (EFG) at the core of an As atom located at the apex of the pyramidal structure. This EFG is shown to be hyper sensitive to the bond angles and bond lengths the As atom forms with the chalcogen nearest neighbors, as well as the hybrid angle formed with second neighbor As atoms. A continuous variation of the bonding parameters produces a unique set of these pyramidal units which are shown to fit the NQR data for powdered glassy samples. The best fit to the NQR data indicates that the pyramidal units organize themselves into Chiral structures in the glass. A plot of the electronic energy per molecular site shows that the chiral structures have on average a lower electronic energy than a random configuration.

Nelson, Chris

2012-02-01

185

The resonant X-ray diffraction in Co-Akermanite: Theory and experiment  

SciTech Connect

The structural factors for X-ray resonant diffraction near the K-absorption edge of cobalt in Co-akermanite have been calculated with allowance for the known data about its incommensurate 2D modulation. It is shown that the local symmetry of Co atoms in the basic structure does not allow any pure resonant reflections in the dipole-dipole approximation. However, pure resonant reflections of the h00 (h = 2n + 1) type are possible owing to the dipole-quadrupole contribution. The 5D formalism is used for the incommensurately modulated structure. It is shown that the displacement terms in the anisotropic tensor atomic factors could mainly contribute to the first-order satellites, providing pure resonant satellite reflections of the hhlm0 (m = 2n + 1) or h00mm-bar (h = 2n + 1) types.

Bindi, L. [Universitae di Firenze, Dipartimento di Scienze della Terra (Italy); Dmitrienko, V. E. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Ovchinnikova, E. N. [Moscow State University (Russian Federation); Soedzhima, Yu. [Kyushu University, Department of Physics (Japan)

2006-12-15

186

Nuclear quadrupole resonance studies of the SORC sequence and nuclear magnetic resonance studies of polymers  

SciTech Connect

The behavior of induction signals during steady-state pulse irradiation in {sup 14}N NQR was investigated experimentally. Because Strong Off-resonance Comb (SORC) signals recur as long as the pulsing continues, very efficient signal-averaging can result. The dependence of these steady-state SORC signals on pulse parameters and on frequency offset are presented, together with a discussion of the applicability of the method. Also as part of the NQR work, cocaine base has been detected using conventional NQR techniques. The experimental results show that SORC detection can be of sufficient sensitivity to form the basis of narcotics screening devices for both mail and airline baggage. A new NMR technique, to obtain the correlation time of the random thermal motion of a polymer at temperatures near the glass transition has been introduced. The temperature dependence is a result of thermal motion. For slow-motion of a polymer chain near the glass transition, the CSA parameter begins to decrease. This motional narrowing can be interpreted to yield the correlation time of the thermal motion. In this work nitrocellulose isotopically highly enriched with {sup 15}N was studied at four different temperatures between 27{degrees} and 120{degrees} Celsius and the correlation times for polymer backbone motions were obtained. Naflon films containing water (D{sub 2}O and H{sub 2} {sup 17}O) and methanol (CH{sub 3}OD, CH{sub 3} {sup 17}OH), have been studied using deuteron and oxygen-17 NMR spectroscopy. Glassy behavior of the water domains at low temperature is evidenced by the specific nature of the {sup 2}H NMR lineshapes. Activation energies extracted from {sup 2}H spin-lattice relaxation data on the high temperature side of the T{sub 1} minimum exhibit a steady increase with increasing water content. In spite of a high degree of molecular mobility, angular-dependent spectra of both unstretched and stretched samples reflect considerable anisotrophy of the host polymer.

Jayakody, J.R.P.

1993-12-31

187

The Bloch Equations in High-Gradient Magnetic Resonance Force Microscopy: Theory and Experiment  

NASA Astrophysics Data System (ADS)

We report theory and observations of paramagnetic resonance in a measured field gradient of 44,000 T per meter by the technique of magnetic resonance force microscopy (MRFM). Resonance was induced in a dilute solid solution of diphenylpicrylhydrazyl in polystyrene at 77 and 10 K by an amplitude-modulated microwave field. This modulated the force between resonant sample spins and a micrometer-scale SmCo magnetic tip on a force microscope cantilever. The force signals were typically of order 10 fN, and were detected above a thermal noise floor of 80 aN per root hertz at 10 K, equivalent to a magnetic moment noise of 200 ? B per root hertz of bandwidth. Resonance saturation was readily observed. Starting with the Bloch equations, we derived simple analytic expressions for the predicted cantilever signal amplitudes and T1-dependent phase lags, valid at low microwave power levels. For power levels below saturation, the data were in good agreement with the Bloch equation predictions, while above saturation the measured force increased more slowly with power than predicted. Several ESR mechanisms which might lead to non-Bloch dynamics in the MRFM environment are reviewed. Spin-relaxation mechanisms are also reviewed. A detailed description of the experimental apparatus is offered.

Dougherty, W. M.; Bruland, K. J.; Chao, S. H.; Garbini, J. L.; Jensen, S. E.; Sidles, J. A.

2000-03-01

188

A 4 K cryogenic probe for use in magnetic resonance force microscopy experiments  

SciTech Connect

The detailed design of a mechanically detected nuclear magnetic resonance probe using the SPAM (Springiness Preservation by Aligning Magnetization) geometry, operating at 4 K, in vacuum, and a several-Tesla magnetic field is described. The probe head is vibration-isolated well enough from the environment by a three-spring suspension system that the cantilever achieves thermal equilibrium with the environment without the aid of eddy current damping. The probe uses an ultra-soft Si cantilever with a Ni sphere attached to its tip, and magnetic resonance is registered as a change in the resonant frequency of the driven cantilever. The RF system uses frequency sweeps for adiabatic rapid passage using a 500 ?m diameter RF coil wound around a sapphire rod. The RF coil and optical fiber of the interferometer used to sense the cantilever's position are both located with respect to the cantilever using a Garbini micropositioner, and the sample stage is mounted on an Attocube nanopositioner.

Smith, Doran D.; Alexson, Dimitri A. [U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783 (United States)] [U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783 (United States); Garbini, Joseph L. [Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States)] [Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States)

2013-09-15

189

Toward Resonant, Imaginative Experiences in Ecological and Democratic Education. A Response to "Imagination and Experience: An Integrative Framework"  

ERIC Educational Resources Information Center

In this response to Fettes's "Imagination and Experience," the authors further consider the varieties of educational experience that inspire ecological flourishing and a living democracy. The essential interconnectedness of encounter-driven and language-driven ways of knowing are explored with particular reference to the…

Derby, Michael; Blenkinsop, Sean; Telford, John; Piersol, Laura; Caulkins, Michael

2013-01-01

190

Microscopic properties of the heavy-fermion superconductor PuCoIn5 explored by nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

We report 115In nuclear quadrupolar resonance (NQR) measurements on the heavy-fermion superconductor PuCoIn5, in the temperature range 0.29K ? T ? 75K. The NQR parameters for the two crystallographically inequivalent In sites are determined, and their temperature dependence is investigated. A linear shift of the quadrupolar frequency with lowering temperature below the critical value Tc is revealed, in agreement with the prediction for composite pairing. The nuclear spin-lattice relaxation rate T1-1(T) clearly signals a superconducting (SC) phase transition at Tc ? 2.3 K, with strong spin fluctuations, mostly in-plane, dominating the relaxation process in the normal state near to Tc. Analysis of the T1-1 data in the SC state suggests that PuCoIn5 is a strong-coupling d-wave superconductor.

Koutroulakis, G.; Yasuoka, H.; Chudo, H.; Tobash, P. H.; Mitchell, J. N.; Bauer, E. D.; Thompson, J. D.

2014-05-01

191

Low-power stimulated emission nuclear quadrupole resonance detection system utilizing Rabi transitions  

NASA Astrophysics Data System (ADS)

The application of CW radar techniques to Nuclear Quadrupole Resonance (NQR) detection of nitrogen based explosives and chlorine based narcotics enables the use of low power levels, in the range of 10's of watts, to yield high signal strengths. By utilizing Rabi transitions the nucleus oscillates between states one and two under the time dependent incident electromagnetic field and alternately absorbs energy from the incident field while emitting coherent energy via stimulated emission. Through the application of a cancellation algorithm the incident field is eliminated from the NQR response, allowing the receive signal to be measured while transmitting. The response signal is processed using matched filters of the NQR response which enables the direct detection of explosives. This technology has applicability to the direct detection of explosives and narcotics for security screening, all at safe low power levels, opposed to the current XRay and Millimeter wave screening systems that detect objects that may contain explosives and utilize high power. The quantum mechanics theoretical basis for the approach and an application for a system for security screening are described with empirical results presented to show the effects observed.

Apostolos, John; Mouyos, William; Feng, Judy; Chase, Walter

2013-06-01

192

SpinWave Resonance Fields, Linewidths, and Intensities of a Permalloy Film: Theory and Experiment  

Microsoft Academic Search

Using only the surface-anisotropy constants and the saturation magnetization as adjustable parameters, we have found good agreement between an observed and a calculated spin-wave resonance spectrum. A uniform magnetization, effects of exchange, conductivity, and Landau-Lifshitz damping are included in the theory.

G. C. Bailey; C. Vittoria

1972-01-01

193

Effect of granular media on the vibrational response of a resonant structure: theory and experiment.  

PubMed

The acoustic response of a structure that contains a cavity filled with a loose granular material is analyzed. The inputs to the theory are the effective masses of each subsystem: that of the empty-cavity resonating structure and that of the granular medium within the cavity. This theory accurately predicts the frequencies, widths, and relative amplitudes of the various flexural mode resonances observed with rectangular bars, each having a cavity filled with loose tungsten granules. Inasmuch as the dominant mechanism for damping is due to adsorbed water at the grain-grain contacts, the significant effects of humidity on both the effective mass of the granular medium as well as on the response of the grain-loaded bars are monitored. Here, depending upon the humidity and the preparation protocol, it is possible to observe one, two, or three distinct resonances in a wide frequency range (1-5 kHz) over which the empty bar has but one resonance. These effects are understood in terms of the theoretical framework, which may simplify in terms of perturbation theories. PMID:21110572

Valenza, John J; Hsu, Chaur-Jian; Johnson, David Linton

2010-11-01

194

You'll never crawl alone: Neurophysiological evidence for experience-dependent motor resonance in infancy  

Microsoft Academic Search

Lately, neuroscience is showing a great interest in examining the functional and neural mechanisms which support action observation and understanding. Recent studies have suggested that our motor skills crucially affect the way in which we perceive the actions generated by others, by showing stronger motor resonance for observation of actions that are established in one's motor repertoire. In the present

M. van Elk; H. T. van Schie; S. Hunnius; C. Vesper; H. Bekkering

2008-01-01

195

Folded Fabry-Perot quasi-optical ring resonator diplexer Theory and experiment  

NASA Technical Reports Server (NTRS)

Performance of folded Fabry-Perot quasi-optical ring resonator diplexers with different geometries of reflecting surfaces is investigated both theoretically and experimentally. Design of optimum surface geometry for minimum diffraction, together with the figure of merit indicating improvement in performance, are given.

Pickett, H. M.; Chiou, A. E. T.

1983-01-01

196

Gramicidin A backbone and side chain dynamics evaluated by molecular dynamics simulations and nuclear magnetic resonance experiments. II: nuclear magnetic resonance experiments.  

PubMed

Motional properties are important for understanding protein function and are accessible to NMR relaxation measurements. The goal of this study is to investigate the internal dynamics occurring in gramicidin A (gA) channels in order to provide benchmark experimental data for comparison with the results of molecular dynamics simulations. We therefore synthesized several (15)N isotope-enriched gA samples, covering all backbone residues as well as the Trp indole side chains for NMR relaxation experiments. On the basis of the (15)N NMR spectra for labeled gA samples incorporated in sodium dodecylsulfate (SDS) micelles, we determined T(1), T(2), and heteronuclear NOE values for backbone and indole (15)NH groups. The results indicate that the SDS-incorporated gA channel is a constrained structure without an especially "floppy" region. The NMR observables, particularly those for backbone groups, are predicted well by the molecular dynamics simulations in the accompanying article (DOI 10.1021/jp200904d ). PMID:21574558

Vostrikov, Vitaly V; Gu, Hong; Ingólfsson, Helgi I; Hinton, James F; Andersen, Olaf S; Roux, Benoît; Koeppe, Roger E

2011-06-01

197

Ultrasound imparted air-recoil resonance ((UIAR) method for acoustic power estimation: theory and experiment.  

PubMed

Ultrasound imparted air-recoil resonance (UIAR), a new method for acoustic power estimation, is introduced with emphasis on therapeutic high-intensity focused ultrasound (HIFU) monitoring applications. Advantages of this approach over existing practices include fast response; electrical and magnetic inertness, and hence MRI compatibility; portability; high damage threshold and immunity to vibration and interference; low cost; etc. The angle of incidence should be fixed for accurate measurement. However, the transducer-detector pair can be aligned in any direction with respect to the force of gravity. In this sense, the operation of the device is orientation independent. The acoustic response of a pneumatically coupled pair of Helmholtz resonators, with one of them acting as the sensor head, is used for the estimation of acoustic power. The principle is valid in the case of pulsed/ burst as well as continuous ultrasound exposure, the former being more sensitive and accurate. An electro-acoustic theory has been developed for describing the dynamics of pressure flow and resonance in the system considering various thermo- viscous loss mechanisms. Experimental observations are found to be in agreement with theoretical results. Assuming the window damage threshold (~10 J·mm(-2)) and accuracy of RF power estimation are the upper and lower scale-limiting factors, the performance of the device was examined for an RF power range of 5 mW to 100 W with a HIFU transducer operating at 1.70 MHz, and an average nonlinearity of ~1.5% was observed. The device is also sensitive to sub-milliwatt powers. The frequency response was analyzed at 0.85, 1.70, 2.55, and 3.40 MHz and the results are presented with respective theoretical estimates. Typical response time is in the millisecond regime. Output drift is about 3% for resonant and 5% for nonresonant modes. The principle has been optimized to demonstrate a general-purpose acoustic power meter. PMID:25004503

Kaiplavil, S; Rivens, I; Ter Haar, Gail

2013-07-01

198

Vibration characteristics of composite piezoceramic plates at resonant frequencies: experiments and numerical calculations  

Microsoft Academic Search

The experimental measurement of the resonant frequencies for the piezoceramic material is generally performed by impedance analysis. In this paper, we employ an optical interferometry method called the amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) to investigate the vibration characteristics of piezoceramic\\/aluminum laminated plates. The AF-ESPI is a powerful tool for the full-field, noncontact, and real-time measurement method of surface displacement

Chi-Hung Huang; Chien-Ching Ma

2001-01-01

199

Parabolic-confocal unstable-resonator semiconductor lasers-Modeling and experiments  

Microsoft Academic Search

Surface-emitting all-grating-based unstable-resonator lasers, suitable for integration with diffractive beam-forming elements, have been experimentally and theoretically studied. The lasers exhibit single spatial mode operation for a device width of 160 ?m. The device performance is modeled using a beam propagation method, which accounts for spatial hole burning as well as thermal and carrier diffusion effects. Near- and far-field calculations are

Niklas Eriksson; Anders Larsson; Masahiro Uemukai; Toshiaki Suhara

1998-01-01

200

Coaxial probe for nuclear magnetic resonance diffusion and relaxation correlation experiments  

NASA Astrophysics Data System (ADS)

A coaxial nuclear magnetic resonance (NMR) probe is built to measure diffusion and relaxation properties of liquid samples. In particular, we demonstrate the acquisition of two-dimensional (2D) distribution functions (T1-T2 and diffusion-T2), essential for fluids characterization. The compact design holds promise for miniaturization, thus enabling the measurement of molecular diffusion that is inaccessible to conventional micro-NMR setups. Potential applications range from crude oil characterization to biomolecular screening and detections.

Tang, Yiqiao; Hürlimann, Martin; Mandal, Soumyajit; Paulsen, Jeffrey; Song, Yi-Qiao

2014-02-01

201

Magnetic resonance study of arsenic bonding sites in ternary chalcogenide glasses  

NASA Astrophysics Data System (ADS)

75As NQR and high-field NMR experiments have been performed on Ge xAs ySe 1- x- y glasses. Evolution of As bonding structure from arsenic sites with axially symmetric distribution of the electric field gradient (EFG) to highly asymmetric As surroundings has been revealed. Arsenic atoms form pyramidal structural units in Ge 2As 2Se 7 with no evidence of significant concentration of homopolar bonds. In Ge 2As 2Se 5 most of arsenic atoms form structural units with two As-As bonds per atom and asymmetric EFG distribution. Arsenic bondings become more complicated in Ge 0.33As 0.12Se 0.55 where all arsenic sites are highly distorted. The combination of NQR and NMR data provide valuable information on arsenic bonding dynamics in these glasses.

Mammadov, E.; Bobela, D.; Reyes, A.; Mehdiyeva, S.; Taylor, P. C.

2011-10-01

202

Simulation and beamline experiments for the superconducting electron cyclotron resonance ion source VENUS  

SciTech Connect

The particle-in-cell code WARP has been enhanced to incorporate both two- and three-dimensional sheath extraction models giving WARP the capability of simulating entire ion beam transport systems including the extraction of beams from plasma sources. In this article, we describe a method of producing initial ion distributions for plasma extraction simulations in electron cyclotron resonance (ECR) ion sources based on experimentally measured sputtering on the source biased disk. Using this initialization method, we present preliminary results for extraction and transport simulations of an oxygen beam and compare them with experimental beam imaging on a quartz viewing plate for the superconducting ECR ion source VENUS.

Todd, Damon S.; Leitner, Daniela; Lyneis, Claude M.; Grote, David P. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2008-02-15

203

Using an NMR Spectrometer to Do Magnetic Resonance Imaging: An Undergraduate Physical Chemistry Laboratory Experiment  

ERIC Educational Resources Information Center

A conventional Fourier-transform NMR spectrometer with a triple-axis gradient probe can function as a MRI imager. In this experiment students gain hands-on experience with MRI while they learn about important principles underlying the practice of NMR, such as gradients, multi-dimensional spectroscopy, and relaxation. Students image a biological…

Steinmetz, Wayne E.; Maher, M. Cyrus

2007-01-01

204

Experiments with a double solenoid system: Measurements of the 6He + p Resonant Scattering  

NASA Astrophysics Data System (ADS)

A recent experiment has been performed in the double solenoid system Radioactive Ion Beams in Brasil (RIBRAS) by impinging a pure 6He secondary beam on a thick CH2 target to measure the 6He + p excitation function. Results of this experiment will be presented.

Pampa Condori, R.; Lichtenthäler, R.; Lépine-Szily, A.; Gasques, L. R.; de Faria, P. N.; Mendes, D. R.; Morais, M. C.; Pires, K. C. C.; Scarduelli, V. B.; Leistenschneider, E.; Alcántara-Núñez, J. A.; Shorto, J. M. B.; Assunção, M.

2014-03-01

205

Power instability of singly resonant optical parametric oscillators: theory and experiment.  

PubMed

We present a theoretical model on the effects of mechanical perturbations on the output power instability of singly-resonant optical parametric oscillators (SR-OPOs). Numerical simulations are performed based on real experimental parameters associated with a SR-OPO designed in our laboratory, which uses periodically-poled LiNbO3 (PPLN) as the nonlinear crystal, where the results of the theoretical model are compared with the measurements. The out-coupled power instability is simulated for a wide range of input pump powers the SR-OPO oscillation threshold. From the results, maximum instability is found to occur at an input pump power of ~1.5 times above the OPO threshold. It is also shown theoretically that the idler instability is susceptible to variations in the cavity length caused by vibrations, with longer cavities capable of generating more stable output power. The validity of the theoretical model is verified experimentally by using a mechanical vibrator in order to vary the SR-OPO resonator length over one cavity mode spacing. It is found that at 1.62 times threshold, the out-coupled idler suffers maximum instability. The results of experimental measurements confirm good agreement with the theoretical model. An intracavity etalon is finally used to improve the idler output power by a factor of ~2.2 at an input pump power of 1.79 times oscillation threshold. PMID:23262694

Sabouri, Saeed Ghavami; Khorsandi, Alireza; Ebrahim-Zadeh, Majid

2012-12-01

206

Evolution of an Unconventional Superconducting State inside the Antiferromagnetic Phase of CeNiGe3 under Pressure: A 73Ge-Nuclear-Quadrupole-Resonance Study  

NASA Astrophysics Data System (ADS)

We report a 73Ge nuclear-quadrupole-resonance (NQR) study on novel evolution of unconventional superconductivity in antiferromagnetic (AFM) CeNiGe3. The measurements of the 73Ge-NQR spectrum and the nuclear spin-lattice relaxation rate (1/T1) have revealed that the unconventional superconductivity evolves inside a commensurate AFM phase around the pressure (P) where Néel temperature TN exhibits its maximum at 8.5 K. The superconducting transition temperature TSC has been found to be enhanced with increasing TN, before reaching the quantum critical point at which the AFM order collapses. Above TSC, the AFM structure transits from an incommensurate spin-density-wave order to a commensurate AFM order at T˜ 2 K, accompanied by a longitudinal spin-density fluctuation. With regard to heavy-fermion compounds, these novel phenomena have hitherto never been reported in the P-T phase diagram.

Harada, Atsushi; Mukuda, Hidekazu; Kitaoka, Yoshio; Thamizhavel, Arumugam; Okuda, Yusuke; Settai, Rikio; ?nuki, Yoshichika; Itoh, Kouhei M.; Haller, Eugene E.; Harima, Hisatomo

2008-10-01

207

Evidence for Ca substituting Ba in YBa 2- xCa xCu 4O 8± y: a nuclear quadrupole resonance investigation  

NASA Astrophysics Data System (ADS)

For the understanding of the Tc enhancement in Ca doped YBa 2Cu 4O 8± y it is crucial to know which crystallographic site the Ca +2 ion is occupying. We investigated this problem by measuring the Cu nuclear quadrupole resonance (NQR) spectrum at 100 K in YBa 2Cu 4O 8± y doped with 10% Ca ( Tc = 91 K). The NQR lines of the plane and chain Cu sites appear at the same frequencies vq as in the pure compound, however, both lines are broadend by static defects. Within the linewidths no temperature dependence of vq was observed and no indication for magnetic ordering at the Cu sites was found. At 20 600 Mhz, near to the Cu(1) line, a resonance line has been detected which is absent in the pure YBa 2- xCa xCu 4O 8± y spectrum. Based on NQR arguments we assign this new line to Cu(1) nuclei whose electric field gradients are disturbed by Ca +2 ions occupying Ba +2 sites. We concluded that a major fraction of Ca ions occupy Ba sites, therefore the increase of Tc by Ca doping cannot be explained by an increase of the hole concentration.

Mangelschots, I.; Mali, M.; Roos, J.; Zimmermann, H.; Brinkmann, D.; Rusiecki, S.; Karpinski, J.; Kaldis, E.; Jilek, E.

1990-12-01

208

Time resolved experiments at the Frankfurt 14 GHz electron cyclotron resonance ion source  

NASA Astrophysics Data System (ADS)

Time resolved measurements of the extracted ion currents at the Frankfurt 14 GHz electron cyclotron resonance ion source (ECRIS) are reported. These measurements were performed to provide more detailed information on the ``biased disk effect'' in an ECRIS. From a first series of measurements with pulsed biased disk voltage it was concluded that the ``biased disk effect'' is mainly due to improvements of the extraction conditions and the enhanced transport of highly charged ions into the extraction area. In this article we present new measurements with an improved setup allowing for a faster pulsing of the biased disk voltage. We also present data for the injection of neutral particles from laser ablated plasmas and Bremsstrahlung spectra for different dc biased disk voltages. All results from these measurements support our previous conclusion.

Runkel, S.; Hohn, O.; Stiebing, K. E.; Schempp, A.; Schmidt-Böcking, H.; Mironov, V.; Shirkov, G.

2000-02-01

209

Description of depolarization effects in double-quantum solid state nuclear magnetic resonance experiments using multipole-multimode Floquet theory.  

PubMed

Using an analytical model based on multipole-multimode Floquet theory (MMFT), we describe the polarization loss (or depolarization) observed in double-quantum (DQ) dipolar recoupling magic angle spinning (MAS) experiments. Specifically, the factors responsible for depolarization are analyzed in terms of higher order corrections to the spin Hamiltonian in addition to the usual phenomenological decay rate constant. From the MMFT model and the effective Hamiltonians, we elucidate the rationale behind the inclusion of a phenomenological damping term in DQ recoupling experiments. As a test of this theoretical approach, the recoupling efficiency of one class of (13)C-(13)C and (13)C-(15)N resonance width dipolar recoupling experiments are investigated at different magnetic field strengths and compared with the more exact numerical simulations. In contrast to existing analytical treatments, the role of higher order corrections is clearly explained in the context of the MMFT approach leading to a better understanding of the underlying spin physics. Furthermore, the analytical model presented herein provides a general framework for describing coherent and incoherent effects in homonuclear and heteronuclear DQ MAS recoupling experiments. PMID:16942159

Ramachandran, Ramesh; Griffin, Robert G

2006-07-28

210

On the second harmonic electron cyclotron resonance heating and current drive experiments on T-10 and DIII-D  

SciTech Connect

Studies of electron cyclotron current drive at the second harmonic resonance have been performed both on the DIII-D and T-10 tokamaks at injected power levels of approximately 0.5 MW. The DIII-D experiment used high held launch of the extraordinary mode at an angle of 15[degree] to the radial. In this experiment, with pulse lengths [approx equal] 500 msec, a loop voltage difference, compared to the value expected from the measured profiles, of [approx equal] 50 mV was ascribed to approximately 50 kA of rf-driven current. When dc electric field and trapped particle effects were considered, this was consistent with theoretical predictions. T-10 experiments planned for the fall of 1992 will use low field launch of the extraordinary mode and an injection angle of 21[degree] off-radial. In preliminary experiments with relatively poor machine conditions and pulse lengths [approx equal] 400 msec, rf current drive was not observed despite the fact that driven currents as low as 10 kA, corresponding to a loop voltage difference for co- versus counter-injection of 20 mV, could have been detected. In this paper we examine the T-10 experiments using ray tracing and transport calculations in an attempt to understand the results. The dependence of the current drive efficiency on discharge parameters, flux penetration, and non-linear effects will be discussed. The results show that the launching geometry can have a significant effect on the observation of electron cyclotron current drive using the loop voltage as a diagnostic. In addition, predictions for the next series of experiments on T-10, for which greater than 2 MW of high frequency power should be available, will be presented.

Lohr, J.; Forest, C.B.; Lin-Liu, Y.R.; Luce, T.C.; Harvey, R.W. (General Atomics, San Diego, CA (United States)); Downs, E.A. (General Atomics, San Diego, CA (United States) Cornell Univ., Ithaca, NY (United States)); James, R.A. (General Atomics, San Diego, CA (United States) Lawrence Livermore National Lab., CA (United States)); Bagdasarov, A.A.; Borshegovskii, A.A.; Chistyakov, V.V.; Dremin, M.M.; Gors

1993-02-01

211

On the second harmonic electron cyclotron resonance heating and current drive experiments on T-10 and DIII-D  

SciTech Connect

Studies of electron cyclotron current drive at the second harmonic resonance have been performed both on the DIII-D and T-10 tokamaks at injected power levels of approximately 0.5 MW. The DIII-D experiment used high held launch of the extraordinary mode at an angle of 15{degree} to the radial. In this experiment, with pulse lengths {approx_equal} 500 msec, a loop voltage difference, compared to the value expected from the measured profiles, of {approx_equal} 50 mV was ascribed to approximately 50 kA of rf-driven current. When dc electric field and trapped particle effects were considered, this was consistent with theoretical predictions. T-10 experiments planned for the fall of 1992 will use low field launch of the extraordinary mode and an injection angle of 21{degree} off-radial. In preliminary experiments with relatively poor machine conditions and pulse lengths {approx_equal} 400 msec, rf current drive was not observed despite the fact that driven currents as low as 10 kA, corresponding to a loop voltage difference for co- versus counter-injection of 20 mV, could have been detected. In this paper we examine the T-10 experiments using ray tracing and transport calculations in an attempt to understand the results. The dependence of the current drive efficiency on discharge parameters, flux penetration, and non-linear effects will be discussed. The results show that the launching geometry can have a significant effect on the observation of electron cyclotron current drive using the loop voltage as a diagnostic. In addition, predictions for the next series of experiments on T-10, for which greater than 2 MW of high frequency power should be available, will be presented.

Lohr, J.; Forest, C.B.; Lin-Liu, Y.R.; Luce, T.C.; Harvey, R.W. [General Atomics, San Diego, CA (United States); Downs, E.A. [General Atomics, San Diego, CA (United States)]|[Cornell Univ., Ithaca, NY (United States); James, R.A. [General Atomics, San Diego, CA (United States)]|[Lawrence Livermore National Lab., CA (United States); Bagdasarov, A.A.; Borshegovskii, A.A.; Chistyakov, V.V.; Dremin, M.M.; Gorshkov, A.V.; Gorelov, Y.A.; Esipchuk, Y.V.; Ivanov, N.V.; Kislov, A.Y.; Kislov, D.A.; Lysenko, S.E.; Medvedev, A.A.; Mirenskii, V.Y.; Notkin, G.E.; Parail, V.V.; Pavlov, Y.D.; Razumova, K.A.; Roi, I.N.; Savrukhin, P.V.; Sannikov, V.V.; Sushkov, A.V.; Trukhin, V.M.; Vasin, N.L.; Volkov, V.V. [Kurchatov Inst., Moscow (Russian Federation). Russian Research Center; Denisov, G.G.; Petelin, M.I.; Flyagin, V.A. [Inst. of Applied Physics, Nizhny Novgorod, (Russian Federation)

1993-02-01

212

Secular resonances. [of asteroidal dynamics  

NASA Technical Reports Server (NTRS)

Theories and numerical experiments regarding secular resonances are reviewed. The basic dynamics and the positions of secular resonances are discussed, and secular perturbation theories for the nu16 resonance case, the nu6 resonance, and the nu5 resonance are addressed. What numerical experiments have revealed about asteroids located in secular resonances, the stability of secular resonances, variations of eccentricities and inclinations, and chaotic orbits is considered. Resonant transport of meteorites is discussed.

Scholl, H.; Froeschle, CH.; Kinoshita, H.; Yoshikawa, M.; Williams, J. G.

1989-01-01

213

Focusing twist reflector for electron-cyclotron resonance heating in the Tandem Mirror Experiment-Upgrade  

SciTech Connect

A twist reflector plate is described that linearly polarizes and focuses the TE/sub O/sub 1// circular waveguide mode for heating hot electrons in the thermal barrier of the Tandem Mirror Experiment-Upgrade (TMX-U). The plate polarizing efficiency is 95%, and it has operated satisfactorily at 150 kW power level.

Stallard, B.W.; Coffield, F.E.; Felker, B.; Taska, J.; Christensen, T.E.; Gallagher, N.C. Jr.; Sweeney, D.W.

1984-05-01

214

Sodium-neon resonant photoexcitation soft x-ray laser experiments on Saturn  

SciTech Connect

This paper summarizes progress made at Sandia Laboratories on x-ray lasers. Experiments have demonstrated two main requirements necessary for constructing a radiation pumped soft x-ray laser: (1) a source of sufficient intensity to produce high grain and (2) creation of a significant population of neon ions close to the pump. (FSD) 11 figs.

Porter, J.; Spielman, R.; Matzen, K.; McGuire, G.; Hussey, T.

1990-01-01

215

The fetal magnetic resonance imaging experience in a large community medical center.  

PubMed

Fetal magnetic resonance imaging (MRI) continues to prove a useful problem solving tool for diagnostic and management decision making issues encountered in the antenatal period. In this paper, we attempt to review basic fetal MRI protocol considerations and demonstrate key imaging findings through multiple modalities, with pathologic correlation in several cases. A study of five fetal MRI cases, from our institution, were selected in order to highlight both the indications for, and benefits obtained from this advanced imaging technique. Fetal MRI proved useful in each case in better defining fetal anomalies, especially where ultrasound (due to drawbacks such as shadowing by pelvic bones) was unable to be completely diagnostic. The more in-depth study made possible by MRI also helped with formulation of disease prognosis and estimation of survival chances of the fetus. Further, MRI as a diagnostic and prognostic tool has become more ubiquitous across the medical community. This imparts tangible benefit to patients, who are now able to find this service within arm's reach. Whereas previously these patients were obligatorily referred up to 90 miles away from our centre for further medical work-up, now a large percentage can obtain their prenatal imaging and perinatal care locally. In addition, medical education benefits as new types of cases, those with pathology of the antenatal period, are retained for work-up and management in these large community settings. Cases from our institution exemplify these types of pathologies, from fetal chest masses to a syndromic presentation of bilateral renal agenesis. PMID:21966626

Ghobrial, Peter M; Levy, Rebecca A; O'Connor, Stephen C

2011-01-01

216

Myocardial late gadolinium enhancement in specific cardiomyopathies by cardiovascular magnetic resonance: a preliminary experience.  

PubMed

Late gadolinium enhancement cardiovascular magnetic resonance (CMR) can visualize myocardial interstitial abnormalities. The aim of this study was to assess whether regions of abnormal myocardium can also be visualized by late enhancement gadolinium CMR in the specific cardiomyopathies. A retrospective review of all referrals for gadolinium CMR with specific cardiomyopathy over 20 months. Nine patients with different specific cardiomyopathies were identified. Late enhancement was demonstrated in all patients, with a mean signal intensity of 390 +/- 220% compared with normal regions. The distribution pattern of late enhancement was unlike the subendocardial late enhancement related to coronary territories found in myocardial infarction. The affected areas included papillary muscles (sarcoid), the mid-myocardium (Anderson-Fabry disease, glycogen storage disease, myocarditis, Becker muscular dystrophy) and the global sub-endocardium (systemic sclerosis, Loeffler's endocarditis, amyloid, Churg-Strauss). Focal myocardial late gadolinium enhancement is found in the specific cardiomyopathies, and the pattern is distinct from that seen in infarction. Further systematic studies are warranted to assess whether the pattern and extent of late enhancement may aid diagnosis and prognostic assessment. PMID:18163027

Silva, Caterina; Moon, James C; Elkington, Andrew G; John, Anna S; Mohiaddin, Raad H; Pennell, Dudley J

2007-12-01

217

Real sample temperature: a critical issue in the experiments of nuclear resonant vibrational spectroscopy on biological samples  

PubMed Central

There are several practical and intertangled issues which make the experiments of nuclear resonant vibrational spectroscopy (NRVS) on biological samples difficult to perform. The sample temperature is one of the most important issues. In NRVS the real sample temperatures can be very different from the readings on the temperature sensors. In this study the following have been performed: (i) citing and analyzing various existing NRVS data to assess the real sample temperatures during the NRVS measurements and to understand their trends with the samples’ loading conditions; (ii) designing several NRVS measurements with (Et4N)[FeCl4] to verify these trends; and (iii) proposing a new sample-loading procedure to achieve significantly lower real sample temperatures and to balance among the intertangled experimental issues in biological NRVS measurements.

Wang, Hongxin; Yoda, Yoshitaka; Kamali, Saeed; Zhou, Zhao-Hui; Cramer, Stephen P.

2012-01-01

218

A new sample environment for cryogenic nuclear resonance scattering experiments on single crystals and microsamples at P01, PETRA III  

NASA Astrophysics Data System (ADS)

In order to carry out orientation dependent nuclear resonance scattering (NRS) experiments on small single crystals of e.g. iron proteins and/or chemical complexes but also on surfaces and other micrometer-sized samples a 2-circle goniometer including sample positioning optics has been installed at beamline P01, PETRA III, DESY, Hamburg. This sample environment is now available for all users of this beamline. Sample cooling is performed with a cryogenic gas stream which allows NRS measurements in the temperature range from 80 up to 400 K. In a first test this new sample environment has been used in order to investigate the orientation dependence of the nuclear inelastic scattering (NIS) signature of (i) a dinuclear iron(II) spin crossover (SCO) system and (ii) a hydrogen peroxide treated metmyoglobin single crystal.

Rackwitz, Sergej; Faus, Isabelle; Schmitz, Markus; Kelm, Harald; Krüger, Hans-Jörg; Andersson, K. Kristoffer; Hersleth, Hans-Petter; Achterhold, Klaus; Schlage, Kai; Wille, Hans-Christian; Schünemann, Volker; Wolny, Juliusz A.

2014-04-01

219

Observation of Resonance in Beat-Wave Experiments witb Nd Lasers  

Microsoft Academic Search

We present experimental results obtained in a beat-wave experiment performed with both Nd-YAG (1.064 mm) and Nd-YLF (1.053 imm) laser wavelengths in a D2 plasma. The two infrared beams together with a green probe beam are focused colinearly in a gas chamber filled with D2 at different pressures. The green light scattered by the plasma is observed at O\\

F. Amiranoff; M. Laberge; J. R. Man; F. Moulin; E. Fabre; C. Stenz

220

Pituitary Magnetic Resonance Imaging for Sellar and Parasellar Masses: Ten-Year Experience in 2598 Patients  

PubMed Central

Context: Sellar and parasellar masses present with overlapping clinical and radiological features ranging from asymptomatic incidental presentations and hormonal effects to compressive local mass effects. Pituitary masses are diagnosed with increased frequency with magnetic resonance imaging (MRI) advancements and availability, but indications and diagnostic outcomes of MRI screening for sellar lesions are not defined. Although pituitary adenomas are the most frequently encountered sellar mass lesions, other etiologies should be considered in the differential diagnosis of a sellar mass. Setting: The study was conducted at a tertiary pituitary center. Patients: This study was a retrospective review of 2598 subjects undergoing at least one pituitary MRI scan from 1999 to 2009. Main Outcome Measure: Prevalence and diagnosis of specific sellar and parasellar masses as screened by pituitary MRI. Results: The most common indications for pituitary imaging, excluding known mass follow-up, were for evaluation of hyperprolactinemia or hypogonadism. A normal pituitary gland was reported in 47% of subjects undergoing pituitary MRI. The most common pituitary adenomas initially identified by MRI included prolactinoma (40%), nonfunctioning adenoma (37%), and GH adenoma (13%). Nonadenomatous sellar masses accounted for 18% of visible lesions, of which the most common were Rathke's cleft cyst (19%), craniopharyngioma (15%), and meningioma (15%). Metastases accounted for 5% of nonpituitary lesions and breast cancer was the most common primary source. Conclusions: Half of all pituitary MRI scans performed in a large patient population yielded no visible lesion. Nonadenomatous pituitary lesions should be considered in the diagnosis of sellar masses observed on MRI, and a high clinical suspicion is required to exclude the presence of a nonfunctioning pituitary adenoma.

Famini, Pouyan; Maya, Marcel M.

2011-01-01

221

Enchancement of the Ionosphere Alfvén Resonance caused by earthquake: experiment and model  

NASA Astrophysics Data System (ADS)

Analysis of geomagnetic and telluric data, measured at the station PRK (Parkfield, ULF flux-gate 3-axial magnetometer) 1 week before (including) the day of major EQ (EarthQuake, Ms=6.0, 28-SEP-2004, 17:15:24) near Parkfield, California, USA, are presented. Spectral analysis reveals enhancement the IAR (Ionosphere Alfvén Resonance) modes, localized in the frequency range 0.25-1 Hz, observed the day before the event, Sep 27, at 15:00-20:00 by UT, and at the day of the EQ, Sep 28, at 11:00-19:00 (9 hours before the event). Estimations of the amplitudes of the signals give following values: up to 20 pT for the magnetic channels and 1.5 mkV/km for the telluric ones. Observed phenomena occurs under quiet geomagnetic conditions (|Dst|< 20 nT). We have calculated the efficiency of the modulation of the Alfvén wave at frequencies f = 0.1 - 10 Hz, which passes from the magnetosphere (z > 600 km) to the ionosphere and the to the Earth's surface and the lithosphere. The set of equations for the both magnetic and electric field components has been solved numerically. It has been obtained that the 20% modulation of the concentration of the ion and electron concentrations (which is also observed experimentally) at the heights z = 200 km can lead to the same (or higher) modulation of the amplitude of the variable magnetic field at the Earth's surface (z = 0) at f = 0.1 - 10 Hz. Moreover, the effect depends weakly on the conductivity of the lithosphere. Therefore, an influence of the coupling mechanisms on the F-layer of the ionosphere could lead to observable effects at the Earth's surface.

Kotsarenko, A.; Grimalsky, V.; Pulinets, S.; Koshevaya, S.; Perez-Enriquez, R.; Cruz Abeyro, J. A. L.

2009-04-01

222

Detuned resonances of Tollmien-Schlichting waves in an airfoil boundary layer: Experiment, theory, and direct numerical simulation  

NASA Astrophysics Data System (ADS)

Transition prediction in two-dimensional laminar boundary layers developing on airfoil sections at subsonic speeds and very low turbulence levels is still a challenge. The commonly used semi-empirical prediction tools are mainly based on linear stability theory and do not account for nonlinear effects present unavoidably starting with certain stages of transition. One reason is the lack of systematic investigations of the weakly nonlinear stages of transition, especially of the strongest interactions of the instability modes predominant in non-self-similar boundary layers. The present paper is devoted to the detailed experimental, numerical, and theoretical study of weakly nonlinear subharmonic resonances of Tollmien-Schlichting waves in an airfoil boundary layer, representing main candidates for the strongest mechanism of these initial nonlinear stages. The experimental approach is based on phase-locked hot-wire measurements under controlled disturbance conditions using a new disturbance source being capable to produce well-defined, complex wave compositions in a wide range of streamwise and spanwise wave numbers. The tests were performed in a low-turbulence wind tunnel at a chord Reynolds number of Re = 0.7 × 106. Direct numerical simulations (DNS) were utilized to provide a detailed comparison for the test cases. The results of weakly nonlinear theory (WNT) enabled a profound understanding of the underlying physical mechanisms observed in the experiments and DNS. The data obtained in experiment, DNS and WNT agree basically and provide a high degree of reliability of the results. Interactions occurring between components of various initial frequency-wavenumber spectra of instability waves are investigated by systematic variation of parameters. It is shown that frequency-detuned and spanwise-wavenumber-detuned subharmonic-type resonant interactions have an extremely large spectral width. Similar to results obtained for self-similar base flows it is found that the amplification factors in the frequency-detuned resonances can be even higher than in tuned cases, in spite of the strong base-flow non-self-similarity. An explanation of this unusual phenomenon is found based on the theoretical analysis and comparison of experimental, theoretical, and DNS data.

Würz, W.; Sartorius, D.; Kloker, M.; Borodulin, V. I.; Kachanov, Y. S.; Smorodsky, B. V.

2012-09-01

223

Generating positive contrast from off-resonant spins with steady-state free precession magnetic resonance imaging: theory and proof-of-principle experiments  

Microsoft Academic Search

It is well known that magnetic susceptibility variations lead to signal voids in MRI. However, recent work has shown that positive-contrast imaging of susceptibility-induced field variations can provide signal enhancements rather than signal losses. In this paper, we propose a new method for generating positive contrast from off-resonant spins with steady-state free precession (SSFP) magnetic resonance imaging. Based on theory

Rohan Dharmakumar; Ioannis Koktzoglou; Debiao Li

2006-01-01

224

Vacuum ultraviolet measurements on hydrogen resonance lines in the Maryland Centrifugal Experiment  

SciTech Connect

Extended spectroscopic measurements of hydrogen emission into the vacuum ultraviolet region on the Maryland Centrifugal Experiment [R. F. Ellis, A. B. Hassam, S. Messer, and B. R. Osborn, Phys. Plasmas 8, 2057 (2001)] indicate, from opacity on the Lyman series, {approx}6% atomic hydrogen coexisting with protons, electrons, and carbon-impurity ions in a plasma region where the temperature is {approx}15 eV. An explanation is offered, based upon charge exchange of entering cold hydrogen atoms with plasma protons, followed by collisional excitation and radiative decay.

Ghosh, J.; Elton, R.; Griem, H.; Teodorescu, C.; Case, A.; Ellis, R. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States)

2005-03-01

225

Vacuum ultraviolet measurements on hydrogen resonance lines in the Maryland Centrifugal Experiment  

NASA Astrophysics Data System (ADS)

Extended spectroscopic measurements of hydrogen emission into the vacuum ultraviolet region on the Maryland Centrifugal Experiment [R. F. Ellis, A. B. Hassam, S. Messer, and B. R. Osborn, Phys. Plasmas 8, 2057 (2001)] indicate, from opacity on the Lyman series, ~6% atomic hydrogen coexisting with protons, electrons, and carbon-impurity ions in a plasma region where the temperature is ~15 eV. An explanation is offered, based upon charge exchange of entering cold hydrogen atoms with plasma protons, followed by collisional excitation and radiative decay.

Ghosh, J.; Elton, R.; Griem, H.; Teodorescu, C.; Case, A.; Ellis, R.

2005-03-01

226

Automated NMR resonance assignment strategy for RNA via the phosphodiester backbone based on high-dimensional through-bond APSY experiments.  

PubMed

A fast, robust and reliable strategy for automated sequential resonance assignment for uniformly [(13)C, (15)N]-labeled RNA via its phosphodiester backbone is presented. It is based on a series of high-dimensional through-bond APSY experiments: a 5D HCP-CCH COSY, a 4D H1'C1'CH TOCSY for ribose resonances, a 5D HCNCH for ribose-to-base connection, a 4D H6C6C5H5 TOCSY for pyrimidine resonances, and a 4D H8C8(C)C2H2 TOCSY for adenine resonances. The utilized pulse sequences are partially novel, and optimized to enable long evolution times in all dimensions. The highly precise APSY peak lists derived with these experiments could be used directly for reliable automated resonance assignment with the FLYA algorithm. This approach resulted in 98 % assignment completeness for all (13)C-(1)H, (15)N1/9 and (31)P resonances of a stem-loop with 14 nucleotides. PMID:24771326

Krähenbühl, Barbara; El Bakkali, Issam; Schmidt, Elena; Güntert, Peter; Wider, Gerhard

2014-06-01

227

A tunable general purpose Q-band resonator for CW and pulse EPR/ENDOR experiments with large sample access and optical excitation  

NASA Astrophysics Data System (ADS)

We describe a frequency tunable Q-band cavity (34 GHz) designed for CW and pulse Electron Paramagnetic Resonance (EPR) as well as Electron Nuclear Double Resonance (ENDOR) and Electron Electron Double Resonance (ELDOR) experiments. The TE 011 cylindrical resonator is machined either from brass or from graphite (which is subsequently gold plated), to improve the penetration of the 100 kHz field modulation signal. The (self-supporting) ENDOR coil consists of four 0.8 mm silver posts at 2.67 mm distance from the cavity center axis, penetrating through the plunger heads. It is very robust and immune to mechanical vibrations. The coil is electrically shielded to enable CW ENDOR experiments with high RF power (500 W). The top plunger of the cavity is movable and allows a frequency tuning of ±2 GHz. In our setup the standard operation frequency is 34.0 GHz. The microwaves are coupled into the resonator through an iris in the cylinder wall and matching is accomplished by a sliding short in the coupling waveguide. Optical excitation of the sample is enabled through slits in the cavity wall (transmission ˜60%). The resonator accepts 3 mm o.d. sample tubes. This leads to a favorable sensitivity especially for pulse EPR experiments of low concentration biological samples. The probehead dimensions are compatible with that of Bruker flexline Q-band resonators and it fits perfectly into an Oxford CF935 Helium flow cryostat (4-300 K). It is demonstrated that, due to the relatively large active sample volume (20-30 ?l), the described resonator has superior concentration sensitivity as compared to commercial pulse Q-band resonators. The quality factor ( Q L) of the resonator can be varied between 2600 (critical coupling) and 1300 (over-coupling). The shortest achieved ?/2-pulse durations are 20 ns using a 3 W microwave amplifier. ENDOR (RF) ?-pulses of 20 ?s ( 1H @ 51 MHz) were obtained for a 300 W amplifier and 7 ?s using a 2500 W amplifier. Selected applications of the resonator are presented.

Reijerse, Edward; Lendzian, Friedhelm; Isaacson, Roger; Lubitz, Wolfgang

2012-01-01

228

A tunable general purpose Q-band resonator for CW and pulse EPR/ENDOR experiments with large sample access and optical excitation.  

PubMed

We describe a frequency tunable Q-band cavity (34 GHz) designed for CW and pulse Electron Paramagnetic Resonance (EPR) as well as Electron Nuclear Double Resonance (ENDOR) and Electron Electron Double Resonance (ELDOR) experiments. The TE(011) cylindrical resonator is machined either from brass or from graphite (which is subsequently gold plated), to improve the penetration of the 100 kHz field modulation signal. The (self-supporting) ENDOR coil consists of four 0.8mm silver posts at 2.67 mm distance from the cavity center axis, penetrating through the plunger heads. It is very robust and immune to mechanical vibrations. The coil is electrically shielded to enable CW ENDOR experiments with high RF power (500 W). The top plunger of the cavity is movable and allows a frequency tuning of ±2 GHz. In our setup the standard operation frequency is 34.0 GHz. The microwaves are coupled into the resonator through an iris in the cylinder wall and matching is accomplished by a sliding short in the coupling waveguide. Optical excitation of the sample is enabled through slits in the cavity wall (transmission ?60%). The resonator accepts 3mm o.d. sample tubes. This leads to a favorable sensitivity especially for pulse EPR experiments of low concentration biological samples. The probehead dimensions are compatible with that of Bruker flexline Q-band resonators and it fits perfectly into an Oxford CF935 Helium flow cryostat (4-300 K). It is demonstrated that, due to the relatively large active sample volume (20-30 ?l), the described resonator has superior concentration sensitivity as compared to commercial pulse Q-band resonators. The quality factor (Q(L)) of the resonator can be varied between 2600 (critical coupling) and 1300 (over-coupling). The shortest achieved ?/2-pulse durations are 20 ns using a 3 W microwave amplifier. ENDOR (RF) ?-pulses of 20 ?s ((1)H @ 51 MHz) were obtained for a 300 W amplifier and 7 ?s using a 2500 W amplifier. Selected applications of the resonator are presented. PMID:22196894

Reijerse, Edward; Lendzian, Friedhelm; Isaacson, Roger; Lubitz, Wolfgang

2012-01-01

229

Reduced fluorescence lifetime heterogeneity of 5-fluorotryptophan in comparison to tryptophan in proteins: implication for resonance energy transfer experiments.  

PubMed

Tryptophan (Trp), an intrinsically fluorescent residue of proteins, has been used widely as an energy donor in fluorescence resonance energy transfer (FRET) experiments aimed at measuring intramolecular distances and distance distributions in protein folding-unfolding reactions. However, the high level of heterogeneity associated with the fluorescence lifetime of tryptophan, even in single-tryptophan proteins, imposes restrictions on its use as the energy donor. A search for a tryptophan analogue having reduced lifetime heterogeneity when compared to tryptophan led us to 5-fluorotryptophan (5F-Trp). A single tryptophan-containing mutant form of barstar, a small 89-residue bacterial protein, has multiple lifetime components in its various structural forms including the unfolded state, similar to observations made with several other proteins. Biosynthetic incorporation of 5F-Trp in place of Trp in the mutant barstar resulted in a significant decrease in the level of heterogeneity of fluorescence decay when compared to Trp-barstar, in the native state as well as in the denatured state. Importantly, observation of a major decay component of more than 80% in both the states makes 5F-Trp a significantly better candidate for being the energy donor in FRET experiments, as compared to Trp. This is expected to enable an unambiguous estimation of intramolecular distance distributions during protein folding and unfolding. The sequence insensitivity of the fluorescence decay kinetics of 5F-Trp in proteins was demonstrated by observing the decay kinetics of 5F-Trp incorporated in several synthetic peptides. PMID:21574591

Sarkar, Saswata Sankar; Udgaonkar, Jayant B; Krishnamoorthy, G

2011-06-01

230

Proton and deuterium NMR experiments in zero field. [Perdeuterated p-demethoxybenzene, perdeuterated malonic acid, diethyl terephthalate-d4, nonadecane-2,2'-D2, sodium propionate-D2  

SciTech Connect

High field solid-state NMR lineshapes suffer from inhomogeneous broadening since resonance frequencies are a function of molecular orientation. Time domain zero field NMR is a two-dimensional field-cycling technique which removes this broadening by probing the evolution of the spin system under zero applied field. The simplest version, the sudden transition experiment, induces zero field evolution by the sudden removal of the applied magnetic field. Theory and experimental results of this experiment and several variations using pulsed dc magnetic fuelds to initiate zero field evolution are presented. In particular, the pulsed indirect detection method allows detection of the zero field spectrum of one nuclear spin species via another (usually protons) by utilizing the level crossings which occur upon adiabatic demagnetization to zero field. Experimental examples of proton/deuteron systems are presented which demonstrate the method results in enhanced sensitivity relative to that obtained in sudden transition experiments performed directly on deuterium. High resolution /sup 2/H NQR spectra of a series of benzoic acid derivatives are obtained using the sudden transition and indirect detection methods. Librational oscillations in the water molecules of barium chlorate monohydrate are studied using proton and deuterium ZF experiments. 177 refs., 88 figs., 2 tabs.

Millar, J.M.

1986-02-01

231

Results from the TARC experiment: spallation neutron phenomenology in lead and neutron-driven nuclear transmutation by adiabatic resonance crossing  

NASA Astrophysics Data System (ADS)

We summarize here the results of the TARC experiment whose main purpose is to demonstrate the possibility of using Adiabatic Resonance Crossing (ARC) to destroy efficiently Long-Lived Fission Fragments (LLFFs) in accelerator-driven systems and to validate a new simulation developed in the framework of the Energy Amplifier programme. An experimental set-up was installed in a CERN PS proton beam line to study how neutrons produced by spallation at relatively high energy ( E n?1 MeV) slow down quasi-adiabatically with almost flat isolethargic energy distribution and reach the capture resonance energy of an element to be transmuted where they will have a high probability of being captured. Precision measurements of energy and space distributions of spallation neutrons (using 2.5 and 3.5 GeV/ c protons) slowing down in a 3.3 m×3.3 m×3 m lead volume and of neutron capture rates on LLFFs 99Tc, 129I, and several other elements were performed. An appropriate formalism and appropriate computational tools necessary for the analysis and understanding of the data were developed and validated in detail. Our direct experimental observation of ARC demonstrates the possibility to destroy, in a parasitic mode, outside the Energy Amplifier core, large amounts of 99Tc or 129I at a rate exceeding the production rate, thereby making it practical to reduce correspondingly the existing stockpile of LLFFs. In addition, TARC opens up new possibilities for radioactive isotope production as an alternative to nuclear reactors, in particular for medical applications, as well as new possibilities for neutron research and industrial applications.

Abánades, A.; Aleixandre, J.; Andriamonje, S.; Angelopoulos, A.; Apostolakis, A.; Arnould, H.; Belle, E.; Bompas, C. A.; Brozzi, D.; Bueno, J.; Buono, S.; Carminati, F.; Casagrande, F.; Cennini, P.; Collar, J. I.; Cerro, E.; Del Moral, R.; Díez, S.; Dumps, L.; Eleftheriadis, C.; Embid, M.; Fernández, R.; Gálvez, J.; García, J.; Gelès, C.; Giorni, A.; González, E.; González, O.; Goulas, I.; Heuer, D.; Hussonnois, M.; Kadi, Y.; Karaiskos, P.; Kitis, G.; Klapisch, R.; Kokkas, P.; Lacoste, V.; Le Naour, C.; López, C.; Loiseaux, J. M.; Martínez-Val, J. M.; Méplan, O.; Nifenecker, H.; Oropesa, J.; Papadopoulos, I.; Pavlopoulos, P.; Pérez-Enciso, E.; Pérez-Navarro, A.; Perlado, M.; Placci, A.; Poza, M.; Revol, J.-P.; Rubbia, C.; Rubio, J. A.; Sakelliou, L.; Saldaña, F.; Savvidis, E.; Schussler, F.; Sirvent, C.; Tamarit, J.; Trubert, D.; Tzima, A.; Viano, J. B.; Vieira, S.; Vlachoudis, V.; Zioutas, K.

2002-02-01

232

Field experiment provides ground truth for surface nuclear magnetic resonance measurement  

USGS Publications Warehouse

The need for sustainable management of fresh water resources is one of the great challenges of the 21st century. Since most of the planet's liquid fresh water exists as groundwater, it is essential to develop non-invasive geophysical techniques to characterize groundwater aquifers. A field experiment was conducted in the High Plains Aquifer, central United States, to explore the mechanisms governing the non-invasive Surface NMR (SNMR) technology. We acquired both SNMR data and logging NMR data at a field site, along with lithology information from drill cuttings. This allowed us to directly compare the NMR relaxation parameter measured during logging, T 2, to the relaxation parameter T 2 * measured using the SNMR method. The latter can be affected by inhomogeneity in the magnetic field, thus obscuring the link between the NMR relaxation parameter and the hydraulic conductivity of the geologic material. When the logging T 2 data were transformed to pseudo-T 2 * data, by accounting for inhomogeneity in the magnetic field and instrument dead time, we found good agreement with T 2 * obtained from the SNMR measurement. These results, combined with the additional information about lithology at the site, allowed us to delineate the physical mechanisms governing the SNMR measurement. Such understanding is a critical step in developing SNMR as a reliable geophysical method for the assessment of groundwater resources. Copyright 2012 by the American Geophysical Union.

Knight, R.; Grunewald, E.; Irons, T.; Dlubac, K.; Song, Y.; Bachman, H. N.; Grau, B.; Walsh, D.; Abraham, J. D.; Cannia, J.

2012-01-01

233

Study of plasma start-up initiated by second harmonic electron cyclotron resonance heating on WEGA experiment  

NASA Astrophysics Data System (ADS)

Although both 1st harmonic ordinary mode (O1) and 2nd harmonic extra-ordinary mode (X2) have been successfully used to initiate pre-ionization and breakdown in many devices, a complete theoretical model is still missing to explain the success of this method. Moreover, some experimental observations are not completely understood, such as what occurs during the delay time between the turn-on of ECRH power and first signals of density or light measurements. Since during this free period the ECRH power has to be absorbed by in-vessel components, it is of prime importance to know what governs this delay time. Recently, dedicated start-up experiments have been performed on WEGA, using a 28 GHz ECRH system in X2-mode. This machine has the interesting capability to be run also as a tokamak allowing comparative experiments between stellarator (?/2? > 0) and tokamak (?/2? = 0) configurations. Different scans in heating power, neutral gas pressure, and rotational transform (?) show clearly that the start-up is a two step process. A first step following the turn-on of the ECRH power during which no measurable electron density (or just above the noise level in some cases), ECE and radiated power is detected. Its duration depends strongly on the level of injected power. The second step corresponds to the gas ionization and plasma expansion phase, with a velocity of density build-up and filling-up of the vessel volume depending mainly on pressure, gas and rotational transform. Moreover, an interesting scenario of ECRH pre-ionization without loop voltage in tokamak configuration by applying a small optimal vertical field is relevant for start-up assistance on future experiments like ITER. The results from this experimental parametric study are useful for the modeling of the start-up assisted by the second harmonic electron cyclotron resonance heating. The aim of this work is to establish predictive scenarios for both ITER and W7-X operation.

Preynas, M.; Laqua, H. P.; Otte, M.; Stange, T.; Wauters, T.; Aßmus, D.

2014-02-01

234

s-wave superconductivity in superconducting BaTi2Sb2O revealed by 121/123Sb-NMR/nuclear quadrupole resonance measurements  

NASA Astrophysics Data System (ADS)

We report the 121/123Sb-NMR/nuclear quadrupole resonance (NQR) measurements on the superconductor BaTi2Sb2O with a two-dimensional Ti2O square-net layer formed with Ti3+ (3d1). NQR measurements revealed that the in-plane four-fold symmetry is broken at the Sb site below TA˜40 K, without an internal field appearing at the Sb site. These exclude a spin-density wave (SDW)/ charge density wave (CDW) ordering with incommensurate correlations, but can be understood with the commensurate CDW ordering at TA. The spin-lattice relaxation rate 1/T1, measured at the four-fold symmetry breaking site, decreases below superconducting (SC) transition temperature Tc, indicative of the microscopic coexistence of superconductivity and the CDW/SDW phase below TA. Furthermore, 1/T1 of 121Sb-NQR shows a coherence peak just below Tc and decreases exponentially at low temperatures. These results are in sharp contrast with those in cuprate and iron-based superconductors, and strongly suggest that its SC symmetry is classified to an ordinary s-wave state.

Kitagawa, S.; Ishida, K.; Nakano, K.; Yajima, T.; Kageyama, H.

2013-02-01

235

NMR and NQR study of the electronic and structural properties of Al-Cu-Fe and Al-Cu-Ru quasicrystals  

SciTech Connect

[sup 27]Al and [sup 63,65]Cu NMR is reported for powdered stable Al-Cu-Fe and Al-Cu-Ru icosahedral quasicrystals and crystalline approximants, and for an Al-Pd-Mn single-grain quasicrystal. [sup 27]Al NQR spectra at 4.2 K were observed in Al-Cu-Fe and Al-Cu-Ru samples. From quadrupole-perturbed NMR spectra at different magnetic fields, and from zero-field NQR spectra, a wide distribution of local electric-field gradient (EFG) tensor components and principal-axis-system orientations was found at the Al site. A model EFG calculation based on a 1/1 Al-Cu-Fe approximant successfully explained the observed NQR spectra. The average local gradient is largely determined by the [ital p]-electron wave function at the Al site, while the width of the distribution is due to EFG lattice contribution. Comparison of [sup 63]Cu and [sup 27]Al NMR shows the EFG distribution at the two sites is similar, but the electronic contribution to the EFG is considerably smaller at the Cu site, in agreement with a more [ital s]-type wave function of the conduction electrons. Overall spread of EFG values is well reproduced by calculation based on the approximant. However, the experimental spectra indicate a much larger number of nonequivalent sites when compared with the simulated NQR spectra based on the 1/1 approximant. The short-range, local chemical order is well represented by the approximant, but differences in coordination must be included at intermediate range in the quasicrystal. Measured [sup 27]Al Knight shift, magnetic susceptibility, and nuclear spin-lattice relaxation time as a function of temperature indicate reduced density of states at the Fermi level by a factor of 7 or 8 from the value in Al metal, consistent with the notion of a pseudogap for these quasicrystals. No differences in measured parameters were detected as a function of composition of the quasicrystalline alloys.

Shastri, A.; Borsa, F.; Torgeson, D.R.; Shield, J.E.; Goldman, A.I. (Ames Laboratory, U.S. Department of Energy and Department of Physics Astronomy, Iowa State University, Ames, Iowa 50011 (United States))

1994-12-01

236

Application of quantitative (19) F nuclear magnetic resonance spectroscopy in tape-stripping experiments with natural microemulsions.  

PubMed

The skin penetration of flufenamic acid (Fluf) and fluconazole (Fluc) from innovative natural microemulsions was investigated in tape-stripping experiments on pig ears. The formulations were based on the eudermic surfactants lecithin, sucrose laurate, alkylpolyglycoside or a mixture thereof. The quantification of the penetrated drug amounts was executed by (19) F nuclear magnetic resonance (NMR) in comparison with high-performance liquid chromatography (HPLC). The data obtained by the (19) F NMR method were confirmed by additional quantitative studies using HPLC. An excellent linear correlation was found for Fluf as well as for Fluc between (19) F NMR and HPLC data. This work presents a strategy outlining the use of (19) F NMR to selectively monitor the skin penetration routes of fluorinated compounds. Fluc penetrated generally well into the stratum corneum with the significantly highest amounts from the sucrose laurate microemulsion on the tape strips 1-5. Similarly, the highest amounts of penetrated Fluf could be observed from the formulation based on sucrose laurate. In addition, NMR self-diffusion studies were conducted and revealed a bicontinuous microstructure of the investigated microemulsions. The skin penetration results are in good agreement with the obtained (19) F NMR self-diffusion coefficients of the active compounds in the microemulsion systems. PMID:23794482

Schwarz, Julia C; Hoppel, Magdalena; Kählig, Hanspeter; Valenta, Claudia

2013-08-01

237

Probing the collective Josephson plasma resonance in Bi2Sr2CaCu2O8+y by W-band-mixing experiments  

NASA Astrophysics Data System (ADS)

We report on W-band-mixing experiments with mesa structures patterned on top of Bi2Sr2CaCu2O8+y single crystals. Due to the intrinsic Josephson effect the mixing process could be observed. There is a steep increase of the mixing intensity when the bias current approaches the critical current. We show that the mixing response is related to the excitation of the collective Josephson plasma resonance. In magnetic fields we observed a decrease of the Josephson plasma frequency. From this dependence we were able to estimate the frequency of the Josephson plasma resonance for zero bias and zero field ranging from 105 to 220 GHz.

Walkenhorst, W.; Hechtfischer, G.; Schlötzer, S.; Kleiner, R.; Müller, P.

1997-10-01

238

Multipulse sequences for explosives detection by NQR under conditions of magnetoacoustic and piezoelectric ringing  

Microsoft Academic Search

A number of methods for cancelling magnetoacoustic and piezoelectric ringing signals in the spectroscopy of the nuclear quadrupole\\u000a resonance are presented. The suggested methods include using the sequence (?0)?-(?-?x-2?-?\\u000a y\\u000a -2?-??x\\u000a -2?-??y\\u000a -?)\\u000a n\\u000a and a multipulse analog of the two-pulse Hahn sequence with the first pulse replaced by a short steady-state sequence. Another\\u000a method presented is the method of

V. T. Mikhaltsevitch; T. N. Rudakov; J. H. Flexman; P. A. Hayes; W. P. Chisholm

2004-01-01

239

Novel Phase Transition in CeRu2Al10 Probed by 27Al-NQR/NMR —No Evidence of Magnetic Ordering—  

NASA Astrophysics Data System (ADS)

The 27Al-NQR/NMR measurements of CeRu2Al10 were carried out to clarify the unusual phase transition at T0=27 K. Distinct NQR peaks associated with five nonequivalent Al sites have been observed at T > T0, and each peak is successfully assigned to their respective Al sites. Below the transition temperature T < T0, each peak simply splits into two peaks except for one site. This indicates that the phase transition is not accompanied by magnetic order, but is presumably associated with the onset of structural transition with lowering symmetry. The nuclear spin-lattice relaxation rate 1/T1 suggests a local moment picture above T*˜ 60 K, and the development of Kondo coherence toward T0. Below T0, 1/T1 shows a gaplike decrease with a gap magnitude of 106 K, being consistent with the macroscopic measurements. The Korringa term below 10 K after the gaplike decrease suggests a gap opening over a portion of the Fermi surface.

Matsumura, Masahiro; Kawamura, Yukihiro; Edamoto, Shingo; Takesaka, Tomoaki; Kato, Harukazu; Nishioka, Takashi; Tokunaga, Yo; Kambe, Shinsaku; Yasuoka, Hiroshi

2009-12-01

240

NQR investigation of pressure-induced charge transfer in oxygen-deficient YBa sub 2 Cu sub 3 O sub 7-. delta. (. delta. = 0. 38)  

SciTech Connect

Measurements of the pressure dependence of {sup 63}Cu nuclear quadrupole frequency in YBa{sub 2}Cu{sub 3}O{sub 6.62} from ambient pressure up to 1.5 GPa at 4k have been performed. {Tc} was found to increase with pressure: d{Tc}/dp {approximately} 5 K/GPa. All observed NQR lines are linear in pressure: dln{nu}{sub Q}/dp=z. We found positive z for the empty chain sites, consistent with ionic (Cu{sup 1+}) configuration in which the atom simply feels a squeezing lattice. Planar coppers close to the empty chains have positive z, while those that are close to full chains have z {approximately} 0. We present an analysis of the NQR result on the basis of the charge transfer model in which the mobile charges migrate from the chain to the plane sites. We deduced that a transfer of 0.021 holes to the O(2,3) sites would explain the result in YBa{sub 2}Cu{sub 3}O{sub 6.62}, whereas only 0.007 holes transfer in fully oxygenated YBa{sub 2}Cu{sub 3}O{sub 7}.

Reyes, A.P.; Ahrens, E.T.; Hammel, P.C.; Heffner, R.H. (Los Alamos National Lab., NM (United States)); Takigawa, M. (International Business Machines Corp., Yorktown Heights, NY (United States). Thomas J. Watson Research Center)

1992-01-01

241

NMR and NQR study of Si-doped (6,0) zigzag single-walled aluminum nitride nanotube as n or P-semiconductors.  

PubMed

Density functional theory (DFT) calculations were performed to investigate the electronic structure properties of pristine and Si-doped aluminum nitride nanotubes as n or P-semiconductors at the B3LYP/6-31G* level of theory in order to evaluate the influence of Si-doped in the (6,0) zigzag AlNNTs. We extended the DFT calculation to predict the electronic structure properties of Si-doped aluminum nitride nanotubes, which are very important for production of solid-state devices and other applications. To this aim, pristine and Si-doped AlNNT structures in two models (Si(N) and Si(Al)) were optimized, and then the electronic properties, the isotropic (CS(I)) and anisotropic (CS(A)) chemical shielding parameters for the sites of various (27)Al and (14)N atoms, NQR parameters for the sites of various of (27)Al and (14)N atoms, and quantum molecular descriptors were calculated in the optimized structures. The optimized structures, the electronic properties, NMR and NQR parameters, and quantum molecular descriptors for the Si(N) and Si(Al) models show that the Si(N) model is a more reactive material than the pristine or Si(Al) model. PMID:22588584

Baei, Mohammad T; Peyghan, Ali Ahmadi; Tavakoli, Khadijeh; Babaheydari, Ali Kazemi; Moghimi, Masoumeh

2012-09-01

242

An ultrahigh-vacuum apparatus for resonant diffraction experiments using soft x rays (h{nu}=300-2000 eV)  

SciTech Connect

We have developed an ultrahigh-vacuum instrument for resonant diffraction experiments using polarized soft x rays in the energy range of h{nu}=300-2000 eV at beamline BL17SU of SPring-8. The diffractometer consists of modified differentially pumped rotary feedthroughs for {theta}-2{theta} stages, a sample manipulator with motor-controlled x-y-z-, tilt ({chi})-, and azimuth ({phi})-axes, and a liquid helium flow-type cryostat for temperature dependent measurements between 30 and 300 K. Test results indicate that the diffractometer exhibits high reproducibility (better than 0.001 deg.) for a Bragg reflection of {alpha}-quartz 100 at a photon energy of h{nu}=1950 eV. Typical off- and on-resonance Bragg reflections in the energy range of 530-1950 eV could be measured using the apparatus. The results show that x-ray diffraction experiments with energy-, azimuth-, and incident photon polarization-dependence can be reliably measured using soft x rays in the energy range of {approx}300-2000 eV. The facility can be used for resonant diffraction experiments across the L-edge of transition metals, M-edge of lanthanides, and up to the Si K-edge of materials.

Takeuchi, T.; Chainani, A.; Takata, Y.; Tanaka, Y.; Oura, M. [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho Sayo-gun, Hyogo 679-5148 (Japan); Tsubota, M. [Synchrotron Radiation Research Center, Japan Atomic Energy Agency, 1-1-1 Kouto Sayo-cho Sayo-gun, Hyogo 679-5148 (Japan); Senba, Y.; Ohashi, H. [JASRI/SPring-8, 1-1-1 Kouto Sayo-cho Sayo-gun, Hyogo 679-5148 (Japan); Mochiku, T.; Hirata, K. [Superconducting Materials Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Shin, S. [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho Sayo-gun, Hyogo 679-5148 (Japan); ISSP, The University of Tokyo, 5-1-5 Kashiwanoha Kashiwa, Chiba 277-8581 (Japan)

2009-02-15

243

Nuclear quadrupole spin dynamics: How weak RF pulses and double resonance cross-relaxation contribute to explosives detection  

NASA Astrophysics Data System (ADS)

Nuclear quadrupole resonance (NQR) is a type of radio-frequency (rf) spectroscopy which can detect quadrupolar nuclei (I > 1/2), such as nitrogen, in crystalline solids. NQR spectroscopy is useful for the detection of the many types of explosives containing 14N, however it suffers from a low signal to noise ratio (SNR) particularly in samples with long spin-lattice relaxation times. To improve the SNR the nuclear quadrupole spin dynamics are exploited in two limiting cases: systems with long spin relaxation times and systems where the excitation power is limited. The former is addressed through double resonance effects and the latter through spin echoes created by weak rf pulses. The double resonance effect occurs in samples that also contain a second faster relaxing nuclear species, such as 1H in ammonium nitrate. In this sample an 1H-14N double resonance can be created between the species that improves the SNR. While the focus is on the common case of solids containing both nitrogen and hydrogen, the theory is generally applicable to solids containing spin-1 and spin-1/2 nuclei. A model of this system is developed that treats the motionally averaged secular dipolar Hamiltonian as a perturbation of the combined quadrupole and Zeeman Hamiltonians. This model reveals three types of double resonance conditions, involving static and rf fields, and predicts expressions for the cross-relaxation rate (Wd) between the two species. Using this cross-relaxation rate, in addition to the hydrogen and nitrogen autorelaxation rates, expressions governing the relaxation back to equilibrium in a spin-1/2 and spin-1 system are determined. The three different types of double resonance conditions are created experimentally; one of them for the first time in any system and another for the first time in a solid. Under these double resonance conditions, the increase in Wd and improvements in SNR are explored both theoretically and experimentally using ammonium nitrate. The second effect investigated is the NQR spin echo that forms after excitation of a powder sample by a single weak resonant radio-frequency pulse. This single-pulse echo is identified for the first time, and when applications are limited by a weak rf field, can be used effectively to increase the SNR over conventional detection techniques.

Prescott, David

244

Laser-induced fluorescence study of OH in flat flames of 1--10 bar compared with resonance CARS experiments  

SciTech Connect

Laser-induced fluorescence (LIF) measurements of OH were performed in flat stoichiometric CH{sub 4}/air flames burning at 1, 3, 5, 7, and 9.6 bar, which had previously been investigated using OH resonance CARS. In the LIF study, line shape information and temperatures were extracted from excitation spectra; in addition, OH profiles as a function of height above the burner surface and an estimate of the OH concentration for the different flames were obtained. The perspectives and feasibility of quantitative fluorescence measurements in high pressure flames are discussed, particularly in comparison with the application of resonance CARS. Key words: OH laser-induced fluorescence, high pressure flames, line shape parameters, temperature measurement, OH concentrations, comparison with resonance CARS.

Kohse-Hoinghaus, K.; Meier, U. (Institut fur Physikalische Chemie der Verbrennung, DFVLR, 7000 Stuttgart 80, Federal Republic of Germany (DE)); Attal-Tretout, B. (Office National d'Etudes et Recherches Aerospatiales, Chatillon, France (FR))

1990-04-01

245

Stochastic resonance of quantum discord  

SciTech Connect

We study the stochastic resonance of quantum discord (''discord resonance'') in coupled quantum systems and make a comparison with the stochastic resonance of entanglement (''entanglement resonance''). It is found that the discord resonance is much more robust against dephasing noise and thermal effects than the entanglement resonance. We also show that, unlike the entanglement resonance, the level of dissipation at which the discord resonance occurs is not sensitive to dephasing noise. These results suggest that it is easier to detect the discord resonance in actual experiments, where the dephasing noise and temperature are difficult to control.

Lee, Chee Kong [Centre for Quantum Technologies, National University of Singapore, 117543 Singapore (Singapore); Kwek, Leong Chuan [Centre for Quantum Technologies, National University of Singapore, 117543 Singapore (Singapore); National Institute of Education and Institute of Advanced Studies, Nanyang Technological University, 637616 Singapore (Singapore); Cao, Jianshu [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2011-12-15

246

MC generator TAUOLA: Implementation of resonance chiral theory for two and three meson modes. Comparison with experiment  

SciTech Connect

We present a partial upgrade of the Monte Carlo event generator TAUOLA with the two and three hadron decay modes using the theoretical models based on Resonance Chiral Theory. These modes account for 88% of total hadronic width of the tau meson. First results of the model parameters have been obtained using BaBar data for 3{pi} mode.

Shekhovtsova, O.; Nugent, I. M.; Przedzinski, T.; Roig, P.; Was, Z. [IFIC, Universitat de Valencia-CSIC, Apt. Correus 22085, E-46071, Valencia (Spain); RWTH Aachen University, III. Physikalisches Institut B, Aachen (Germany); The Faculty of Physics, Astronomy and Applied Computer Science, Jagellonian University, Reymonta 4, 30-059 Cracow, Poland and CERN PH-TH, CH-1211 Geneva 23 (Switzerland); Grup de Fisica Teorica, Institut de Fisica d'Altes Energies, Universitat Autonoma de Barcelona, E-08193 Bellaterra, Barcelona (Spain); Institute of Nuclear Physics, PAN, Krakow, ul. Radzikowskiego 152, Poland and CERN PH-TH, CH-1211 Geneva 23 (Switzerland)

2012-10-23

247

The 6Li(22Ne, 26Mg)d ?-transfer experiment for the study of low-energy resonances in 22Ne(?,?)26Mg  

NASA Astrophysics Data System (ADS)

While the reaction 22Ne(?,n)25Mg is considered an important neutron source for the s process in massive stars, the competing 22Ne(?,?)26Mg reaction may be of considerable strength and could significantly suppress the neutron production. For a better understanding of this neutron source, the branching ratio of n and ? partial widths (?n, ??) and spectroscopic information such as energies and spins of 26Mg resonance states within the Gamow window (E? = 400-1000 keV) should be experimentally determined with improved accuracy. In the present work, we propose to use the 6Li(22Ne, 26Mg)d ?-transfer reaction to investigate those resonance parameters and have tested the feasibility of the experiment.

Ota, Shuya; Makii, Hiroyuki; Ishii, Tetsuro; Angell, Christopher; Bardayan, Daniel W.; Chiba, Satoshi; Nishinaka, Ichiro; Nishio, Katsuhisa; Matos, Milan; Mitsuoka, Shinichi; Pain, Steven

2014-03-01

248

Long-lived frequency shifts observed in a magnetic resonance force microscope experiment following microwave irradiation of a nitroxide spin probe  

PubMed Central

We introduce a spin-modulation protocol for force-gradient detection of magnetic resonance that enables the real-time readout of longitudinal magnetization in an electron spin resonance experiment involving fast-relaxing spins. We applied this method to observe a prompt change in longitudinal magnetization following the microwave irradiation of a nitroxide-doped perdeuterated polystyrene film having an electron spin-lattice relaxation time of T1?1ms. The protocol allowed us to discover a large, long-lived cantilever frequency shift. Based on its magnitude, lifetime, and field dependence, we tentatively attribute this persistent signal to deuteron spin magnetization created via transfer of polarization from nitroxide spins.

Chen, Lei; Longenecker, Jonilyn G.; Moore, Eric W.; Marohn, John A.

2013-01-01

249

Long-lived frequency shifts observed in a magnetic resonance force microscope experiment following microwave irradiation of a nitroxide spin probe  

NASA Astrophysics Data System (ADS)

We introduce a spin-modulation protocol for force-gradient detection of magnetic resonance that enables the real-time readout of longitudinal magnetization in an electron spin resonance experiment involving fast-relaxing spins. We applied this method to observe a prompt change in longitudinal magnetization following the microwave irradiation of a nitroxide-doped perdeuterated polystyrene film having an electron spin-lattice relaxation time of T1~1ms. The protocol allowed us to discover a large, long-lived cantilever frequency shift. Based on its magnitude, lifetime, and field dependence, we tentatively attribute this persistent signal to deuteron spin magnetization created via transfer of polarization from nitroxide spins.

Chen, Lei; Longenecker, Jonilyn G.; Moore, Eric W.; Marohn, John A.

2013-04-01

250

Isotope ratio of Cl NQR spin-lattice relaxation times in 1D hydrogen-bonding system of tetramethylpyrazine-chloranilic acid at high temperatures  

NASA Astrophysics Data System (ADS)

The temperature dependences of spin-lattice relaxation time T 1 of 35Cl and 37Cl NQR were studied for the co-crystal of tetramethylpyrazine (TMP) with chloranilic acid (H2ca), TMP-H2ca, in which one-dimensional hydrogen bonding is formed by alternate arrangement of TMP and H2ca. The isotope ratio 37Cl T 1 / 35Cl T 1 was determined to be 1.0 ± 0.1 above ca. 290 K where a steep decrease of spin-lattice relaxation time T 1 with increasing temperature was observed. In this temperature range it is suggested that the relaxation is originated from the slow fluctuation of electric field gradient (EFG). Beside EFG fluctuation due to the external-charge-density fluctuation, the small angle reorientation of the quantization axis triggered by a proton transfer motion between N...H-O and N-H...O hydrogen bonding states is proposed.

Asaji, Tetsuo

2013-05-01

251

14N nuclear quadrupole resonance of picolinic, nicotinic, isonicotinic and dinicotinic acids  

NASA Astrophysics Data System (ADS)

The 14N nuclear quadrupole resonance (NQR) quadrupole coupling tensors of picolinic, nicotinic, isonicotinic and dinicotinic acids have been determined. Two different 14N quadrupole coupling constants 1007 kHz and 4159 kHz have been observed for picolinic acid demonstrating the presence of both protonated and non-protonated nitrogen atoms in this system in the solid. Only one set of non-protonated 14N NQR lines has been observed in other pyridinecarboxylic acids demonstrating the absence of the protonated zwitter ion forms observed in picolinic acid. The non-protonated 14N quadrupole coupling constant is the highest for the non-protonated nitrogen in picolinic acid and decreases to 3774 kHz in nicotinic acid and 3570 kHz in isonicotinic acid. It is the lowest in dinicotinic acid where the corresponding 14N quadrupole coupling constant is 2794 kHz. The observed anomalous decrease in the 14N quadrupole coupling constant of dinicotinic acid with decreasing temperature is tentatively explained as reflecting the increase in the residence time of the N-H⋯O bonded proton in the potential well close to the nitrogen.

Seliger, J.; Žagar, V.; Zidanšek, A.; Blinc, R.

2006-12-01

252

Extending the direct laser modulation bandwidth by exploiting the photon-photon resonance: modeling, simulations and experiments  

NASA Astrophysics Data System (ADS)

The direct laser modulation bandwidth can be extended substantially by introducing a supplementary photon-photon resonance (PPR) at a higher frequency than the carrier-photon resonance (CPR). The paper presents a modified rate equation model that takes into account the PPR by treating the longitudinal confinement factor as a dynamic variable. The conditions required for obtaining a strong PPR and an enhancement of the small-signal modulation bandwidth are analyzed and experimental results confirming the model are presented. Since the small-signal modulation bandwidth may not be indicative of the large-signal modulation capability, particularly in case of a small-signal modulation response with substantial variations across the bandwidth, we have also analyzed the influence of the PPR-enhanced small-signal modulation response shape on the large-signal modulation capability as well as the methods that can be employed to flatten the small-signal modulation transfer function between the CPR and PPR.

Dumitrescu, M.; Laakso, A.; Viheriala, J.; Kamp, M.; Bardella, P.; Eisenstein, G.

2013-03-01

253

Electric-energy generation using variable-capacitive resonator for power-free LSI: efficiency analysis and fundamental experiment  

Microsoft Academic Search

A power generator based on a vibration-to-electric energy converter using a variable-resonating capacitor is experimentally demonstrated. The generator consists of a complete system with a mechanical-variable capacitor, a charge-transporting LC tank circuit and an externally powered timing-capture controller. A practical design methodology to maximize the efficiency of the vibration-to-electric energy generation system is also described. The efficiency of the generator

Masayuki Miyazaki; Hidetoshi Tanaka; Goichi Ono; Tomohiro Nagano; Norio Ohkubo; Takayuki Kawahara; Kazuo Yano

2003-01-01

254

Electron paramagnetic resonance investigations of alpha-Al2O3 powders doped with Fe3+ ions: experiments and simulations  

Microsoft Academic Search

Electron paramagnetic resonance (EPR) of Fe3+ ions in Al2O3 is studied in powder samples prepared by different routes and\\/or modified by thermal or mechanical treatments, with different doping levels and grain sizes. The measurements are performed in various frequency bands (S, X, K, Q and W) and with bimodal detection in X-band. Simulations of the spectra are achieved with a

J. Y. Buzaré; G. Silly; J. Klein; G. Scholz; R. Stösser; M. Nofz

2002-01-01

255

Fast radio-frequency amplitude modulation in multiple-quantum magic-angle-spinning nuclear magnetic resonance: Theory and experiments  

Microsoft Academic Search

Multiple-quantum magic-angle-spinning (MQMAS NMR) spectroscopy has become a routine method to obtain high-resolution spectra of quadrupolar nuclei. One of the main problems in the performance of this experiment has been the poor efficiency of the radio-frequency pulses used in converting multiple-quantum coherences to the observable single-quantum signals. As the MQMAS experiment is basically an echo experiment this problem can be

P. K. Madhu; Amir Goldbourt; Lucio Frydman; Shimon Vega

2000-01-01

256

Terahertz transparency at Fabry-Perot resonances of periodic slit arrays in a metal plate: experiment and theory.  

PubMed

We report on a perfect transmission in one-dimensional metallic structure using time-domain terahertz spectroscopy. Fabry-Perot resonance appearing in spectral region below first Rayleigh minimum strongly enhances transmission up to over ninety-nine percent. Theoretical calculations reveal that under the perfect transmission condition, a symmetric eigenmode inside the slits is excited and a funneling of all incident energy onto the slits occurs, resulting in large energy concentration equivalent to the inverse sample coverage and high near-field enhancement of electric and magnetic field intensities. Our work opens way toward near-field terahertz amplification, applicable to high-field terahertz spectroscopy. PMID:19532155

Lee, J W; Seo, M A; Park, D J; Jeoung, S C; Park, Q H; Lienau, Ch; Kim, D S

2006-12-25

257

Sequential backbone assignment of uniformly 13C-labeled RNAs by a two-dimensional P(CC)H-TOCSY triple resonance NMR experiment.  

PubMed

A new 1H-13C-31P triple resonance experiment is described which allows unambiguous sequential backbone assignment in 13C-labeled oligonucleotides via through-bond coherence transfer from 31P via 13C to 1H. The approach employs INEPT to transfer coherence from 31P to 13C and homonuclear TOCSY to transfer the 13C coherence through the ribose ring, followed by 13C to 1H J-cross-polarisation. The efficiencies of the various possible transfer pathways are discussed. The most efficient route involves transfer of 31Pi coherence via C4'i and C4'i-1, because of the relatively large JPC4' couplings involved. Via the homonuclear and heteronuclear mixing periods, the C4'i and C4'i-1 coherences are subsequently transferred to, amongst others, H1'i and H1'i-1, respectively, leading to a 2D 1H-31P spectrum which allows a sequential assignment in the 31P-1H1' region of the spectrum, i.e. in the region where the proton resonances overlap least. The experiment is demonstrated on a 13C-labeled RNA hairpin with the sequence 5'(GGGC-CAAA-GCCU)3'. PMID:7533569

Wijmenga, S S; Heus, H A; Leeuw, H A; Hoppe, H; van der Graaf, M; Hilbers, C W

1995-01-01

258

Real-time magnetic resonance-guided high-intensity focused ultrasound focal therapy for localised prostate cancer: preliminary experience.  

PubMed

Five patients with unifocal, biopsy-proven prostate cancer (PCa) evident on multiparametric magnetic resonance imaging (MRI) were treated with magnetic resonance-guided focused ultrasound (MRgFUS) ablation before radical prostatectomy (RP). An endorectal probe featuring a phased-array focused ultrasound transducer was positioned for lesion ablation under MRI guidance. The tissue temperature and accumulation of thermal damage in the target zone was monitored during the procedure by MRI thermometry. Overlap between the ablation area and the devascularisation of the target lesion was evaluated by contrast-enhanced MRI performed immediately after treatment. The procedure was uneventful, and no adverse events were observed. RP was safely performed without significant surgical difficulties in relation to the previous MRgFUS treatment. The histopathology report showed extensive coagulative necrosis, with no residual tumour in the ablated area. Significant bilateral residual tumour, not evident on pretreatment MRI, was observed outside the treated area in two patients. MRgFUS ablation of focal localised PCa is feasible and, if confirmed in appropriate studies, could represent a valid option for the focal treatment of localised PCa. PMID:23159454

Napoli, Alessandro; Anzidei, Michele; De Nunzio, Cosimo; Cartocci, Gaia; Panebianco, Valeria; De Dominicis, Carlo; Catalano, Carlo; Petrucci, Federico; Leonardo, Costantino

2013-02-01

259

Reduced dimensionality tailored HN(C)N experiments for facile backbone resonance assignment of proteins through unambiguous identification of sequential HSQC peaks.  

PubMed

Two novel reduced dimensionality (RD) tailored HN(C)N [S.C. Panchal, N.S. Bhavesh, R.V. Hosur, Improved 3D triple resonance experiments, HNN and HN(C)N, for HN and 15N sequential correlations in (13C, 15N) labeled proteins: application to unfolded proteins, J. Biomol. NMR 20 (2001) 135-147] experiments are proposed to facilitate the backbone resonance assignment of proteins both in terms of its accuracy and speed. These experiments - referred here as (4,3)D-hNCOcaNH and (4,3)D-hNcoCANH - exploit the linear combination of backbone (15)N and (13)C'/(13)C(?) chemical shifts simultaneously to achieve higher peak dispersion and randomness along their respective F1 dimensions. Simply, this has been achieved by modulating the backbone (15)N(i) chemical shifts with that of (13)C' (i-1)/(13)C(?) (i-1) spins following the established reduced dimensionality NMR approach [T. Szyperski, D.C. Yeh, D.K. Sukumaran, H.N. Moseley, G.T. Montelione, Reduced-dimensionality NMR spectroscopy for high-throughput protein resonance assignment, Proc. Natl. Acad. Sci. USA 99 (2002) 8009-8014]. Though the modification is simple it has resulted an ingenious improvement of HN(C)N both in terms of peak dispersion and easiness of establishing the sequential connectivities. The increased dispersion along F1 dimension solves two purposes here: (i) resolves the ambiguities arising because of degenerate (15)N chemical shifts and (ii) reduces the signal overlap in F2((15)N)-F3((1)H) planes (an important requisite in HN(C)N based assignment protocol for facile and unambiguous identification of sequentially connected HSQC peaks). The performance of both these experiments and the assignment protocol has been demonstrated using bovine apo Calbindin-d9k (75 aa) and urea denatured UNC60B (a 152 amino acid ADF/cofilin family protein of Caenorhabditis elegans), as representatives of folded and unfolded protein systems, respectively. PMID:24161682

Kumar, Dinesh

2013-12-01

260

Cavity Resonators.  

National Technical Information Service (NTIS)

The microwave cavity resonator may be used in the field of electron spin resonance spectroscopy for studying samples of paramagnetic materials which are supported within the resonator. The resonator passes a maximum amount of light through the walls to th...

E. L. Cochran

1965-01-01

261

A multi-sample changer coupled to an electron cyclotron resonance source for accelerator mass spectrometry experiments.  

PubMed

A new multi-sample changer has been constructed allowing rapid changes between samples. The sample changer has 20 positions and is capable of moving between samples in 1 min. The sample changer is part of a project using Accelerator Mass Spectrometry (AMS) at the Argonne Tandem Linac Accelerator System (ATLAS) facility to measure neutron capture rates on a wide range of actinides in a reactor environment. This project will require the measurement of a large number of samples previously irradiated in the Advanced Test Reactor at Idaho National Laboratory. The AMS technique at ATLAS is based on production of highly charged positive ions in an electron cyclotron resonance ion source followed by acceleration in the ATLAS linac. The sample material is introduced into the plasma via laser ablation chosen to limit the dependency of material feed rates upon the source material composition as well as minimize cross-talk between samples. PMID:24593487

Vondrasek, R; Palchan, T; Pardo, R; Peters, C; Power, M; Scott, R

2014-02-01

262

Stochastic Resonance  

NASA Astrophysics Data System (ADS)

Preface; 1. Introduction and motivation; 2. Stochastic resonance: its definitions, history and debates; 3. Stochastic quantization; 4. Suprathreshold stochastic resonance: encoding; 5. Suprathreshold stochastic resonance: large N encoding; 6. Suprathreshold stochastic resonance: decoding; 7. Suprathreshold stochastic resonance: large N decoding; 8. Optimal stochastic quantization; 9. SSR, neural coding, and performance tradeoffs; 10. Stochastic resonance in the auditory system; 11. The future of stochastic resonance and suprathreshold stochastic resonance; Appendices; References; Index.

McDonnell, Mark D.; Stocks, Nigel G.; Pearce, Charles E. M.; Abbott, Derek

2012-10-01

263

Out-of-plane (e,2e) experiments on an autoionizing resonance using 488 eV incident energy electrons.  

NASA Astrophysics Data System (ADS)

Over the past several years there have been a variety of kinematically complete experiments with both coplanar and out-of- plane geometry involving charged particle impact ionization of a variety of atomic targets. Examples where data were obtained using COLTRIMS spectrometers include single ionization of helium by ions and electrons. An example where data were obtained using a more traditional spectrometer involved single ionization of magnesium by electron impact. Each of these studies has shown that while theoretical descriptions of coplanar experiments tend to be very good, there are large discrepancies in the description of out-of-plane experiments, providing ample motivation for further experimental studies. We have begun to perform kinematically complete out-of-plane experiments on helium using a traditional (e,2e) spectrometer modified for out-of-plane operation. These experiments cover all 2? radians of a plane that includes the momentum transfer direction and is perpendicular to the scattering plane. An overview of the apparatus will be presented as will preliminary results showing the angular distributions for direct ionization and autoionization via He 2s2p ^1P.

Deharak, B. A.; Martin, N. L. S.

2007-06-01

264

Impurity pump-out at the two-ion hybrid resonance during ICRF experiments in TFR tokamak plasmas  

Microsoft Academic Search

A heavy impurity (argon) is efficiently pumped out of a two-ion-component tokamak plasma during ICRF experiments in the mode conversion regime. This is achieved by choosing the plasma isotopic composition such that the two-ion hybrid layer location coincides with the position of the cyclotron frequency second harmonic of one of the argon ions.

1982-01-01

265

Out-of-plane (e,2e) experiments on an autoionizing resonance using 488 eV incident energy electrons  

Microsoft Academic Search

Over the past several years there have been a variety of kinematically complete experiments with both coplanar and out-of- plane geometry involving charged particle impact ionization of a variety of atomic targets. Examples where data were obtained using COLTRIMS spectrometers include single ionization of helium by ions and electrons. An example where data were obtained using a more traditional spectrometer

B. A. Deharak; N. L. S. Martin

2007-01-01

266

Simulation of non-resonant internal kink mode with toroidal rotation in the National Spherical Torus Experiment  

SciTech Connect

Plasmas in spherical and conventional tokamaks, with weakly reversed shear q profile and minimum q above but close to unity, are susceptible to an non-resonant (m,n) = (1,1) internal kink mode. This mode can saturate and persist and can induce a (2,1) seed island for Neoclassical Tearing Mode. [Breslau et al. Nucl. Fusion 51, 063027 (2011)]. The mode can also lead to large energetic particle transport and significant broadening of beam-driven current. Motivated by these important effects, we have carried out extensive nonlinear simulations of the mode with finite toroidal rotation using parameters and profiles of an NTSX plasma with a weakly reversed shear profile. The numerical results show that, at the experimental level, plasma rotation has little effect on either equilibrium or linear stability. However, rotation can significantly influence the nonlinear dynamics of the (1,1) mode and the induced (2,1) magnetic island. The simulation results show that a rotating helical equilibrium is formed and maintained in the nonlinear phase at finite plasma rotation. In contrast, for non-rotating cases, the nonlinear evolution exhibits dynamic oscillations between a quasi-2D state and a helical state. Furthermore, the effects of rotation are found to greatly suppress the (2,1) magnetic island even at a low level.

Wang, Feng; Liu, J. Y. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Fu, G. Y.; Breslau, J. A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Tritz, Kevin [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)] [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

2013-07-15

267

Proposed rocket experiments to measure the profile and intensity of the solar He1584A resonance line  

NASA Technical Reports Server (NTRS)

The intensity and profile of the helium resonance line at 584 A from the entire disc of the sun was investigated using a rocket-borne helium-filled spectrometer and a curve of growth technique. The line profile was found to be accurately represented by a Gaussian profile with full width at half maximum of 122 plus or minus 10m A while the integrated intensity was measured to be (2.6 plus or minus 1.3) x 10 to the 9th power/photons sec sq cm at solar levels of F sub 10.7 = 90.8 x 10 to the minus 22th power/sq m H sub z and R sub z = 27. The measured linewidth is in good agreement with previous spectrographic measurement but the integrated intensity is larger than most previous photoelectric measurements. However, the derived line center flux of (2.0 plus or minus 1.0) x 10 to the 10th power/photons sec sq cm A is in good agreement with values inferred from airglow measurements.

Judge, D. L.

1978-01-01

268

Sensing dissolved methane in aquatic environments: an experiment in the central baltic sea using surface plasmon resonance.  

PubMed

A new sensor for in situ, real time methane (CH4) measurements in aqueous environments is based on the refractive index (RI) modulation of a sensitive film composed of a polydimethylsiloxane (PDMS) layer incorporating molecules of cryptophane-A. The RI varies according to the amount of CH4 bound to the cryptophane-A in the film and is determined using surface plasmon resonance (SPR). Tests of the sensor in the summer of 2012 reveal the expansive range of conditions of the Central Baltic Sea with CH4 concentrations varying from 5 nM up to a few hundred nanomolar. The sensor showed detection limits down to 3 nM, sensitivity of 6 to 7 × 10(-6) RIU/nM, and response times of 1 to 2 min. Best responses were obtained for concentrations up to 200 nM. Side effects (temperature, cross-sensitivity) are reviewed for future improvements to the sensor design. CH4 values are highest in the Landsort Deep up to 1.2 ?M at 400 m depth and lowest in the Gotland Deep with 900 nM at 220 m depth. However, variable values in the upper layers indicate higher mixing rates due to currents and wind driven forces in the Gotland Basin compared with almost constant CH4 values in the Landsort Deep. PMID:23815404

Boulart, Cédric; Prien, Ralf; Chavagnac, Valérie; Dutasta, Jean-Pierre

2013-08-01

269

Adapting Data Processing To Compare Model and Experiment Accurately: A Discrete Element Model and Magnetic Resonance Measurements of a 3D Cylindrical Fluidized Bed  

PubMed Central

Discrete element modeling is being used increasingly to simulate flow in fluidized beds. These models require complex measurement techniques to provide validation for the approximations inherent in the model. This paper introduces the idea of modeling the experiment to ensure that the validation is accurate. Specifically, a 3D, cylindrical gas-fluidized bed was simulated using a discrete element model (DEM) for particle motion coupled with computational fluid dynamics (CFD) to describe the flow of gas. The results for time-averaged, axial velocity during bubbling fluidization were compared with those from magnetic resonance (MR) experiments made on the bed. The DEM-CFD data were postprocessed with various methods to produce time-averaged velocity maps for comparison with the MR results, including a method which closely matched the pulse sequence and data processing procedure used in the MR experiments. The DEM-CFD results processed with the MR-type time-averaging closely matched experimental MR results, validating the DEM-CFD model. Analysis of different averaging procedures confirmed that MR time-averages of dynamic systems correspond to particle-weighted averaging, rather than frame-weighted averaging, and also demonstrated that the use of Gaussian slices in MR imaging of dynamic systems is valid.

2013-01-01

270

Hyperemic stress myocardial perfusion cardiovascular magnetic resonance in mice at 3 Tesla: initial experience and validation against microspheres  

PubMed Central

Background Dynamic first pass contrast-enhanced myocardial perfusion is the standard CMR method for the estimation of myocardial blood flow (MBF) and MBF reserve in man, but it is challenging in rodents because of the high temporal and spatial resolution requirements. Hyperemic first pass myocardial perfusion CMR during vasodilator stress in mice has not been reported. Methods Five C57BL/6 J mice were scanned on a clinical 3.0 Tesla Achieva system (Philips Healthcare, Netherlands). Vasodilator stress was induced via a tail vein catheter with an injection of dipyridamole. Dynamic contrast-enhanced perfusion imaging (Gadobutrol 0.1 mmol/kg) was based on a saturation recovery spoiled gradient echo method with 10-fold k-space and time domain undersampling (k-t PCA). One week later the mice underwent repeat anaesthesia and LV injections of fluorescent microspheres at rest and at stress. Microspheres were analysed using confocal microscopy and fluorescence-activated cell sorting. Results Mean MBF at rest measured by Fermi-function constrained deconvolution was 4.1?±?0.5 ml/g/min and increased to 9.6?±?2.5 ml/g/min during dipyridamole stress (P?=?0.005). The myocardial perfusion reserve was 2.4 ±?0.54. The mean count ratio of stress to rest microspheres was 2.4 ±?0.51 using confocal microscopy and 2.6?±?0.46 using fluorescence. There was good agreement between cardiovascular magnetic resonance CMR and microspheres with no significant difference (P?=?0.84). Conclusion First-pass myocardial stress perfusion CMR in a mouse model is feasible at 3 Tesla. Rest and stress MBF values were consistent with existing literature and perfusion reserve correlated closely to microsphere analysis. Data were acquired on a 3 Tesla scanner using an approach similar to clinical acquisition protocols, potentially facilitating translation of imaging findings between rodent and human studies.

2013-01-01

271

The distribution and prognosis of anomalous coronary arteries identified by cardiovascular magnetic resonance: 15 year experience from two tertiary centres  

PubMed Central

Background Aberrant coronary arteries represent a diverse group of congenital disorders. Post-mortem studies reveal a high risk of exercise-related sudden cardiac death in those with an anomalous coronary artery originating from the opposite sinus of Valsalva (ACAOS) with an inter-arterial course. There is little documentation of lifetime history and long-term follow-up of patients with coronary artery anomalies. Methods Patients with anomalous coronary arteries undergoing cardiovascular magnetic resonance over a 15-year period were identified and classified by anatomy and course. Medical records were reviewed for major adverse cardiovascular events (MACE). Revascularisation or myocardial infarction counted only if occurring in the distribution of the anomalous artery. Results Consecutive patients with coronary artery anomalies were retrospectively identified (n?=?172). Median follow-up time was 4.3 years (IQR 2.5–7.8, maximum 15.6). 116 patients had ACAOS of which 64 (55%) had an inter-arterial course (IAC) and 52 (45%) did not. During follow up 110 ACAOS patients were alive, 5 died and 1 lost to follow-up. ACAOS patients experienced 58 MACE events (5 cardiovascular deaths, 5 PCI, 24 CABG and 24 had myocardial infarction). 47 MACE events occurred in ACAOS with IAC and 11 in those without (p?

2014-01-01

272

Operational experience with the Argonne National Laboratory Californium Rare Ion Breeder Upgrade facility and electron cyclotron resonance charge breeder.  

PubMed

The Californium Rare Ion Breeder Upgrade (CARIBU) of the Argonne National Laboratory Argonne Tandem Linac Accelerator System (ATLAS) facility provides low-energy and accelerated neutron-rich radioactive beams to address key nuclear physics and astrophysics questions. A 350 mCi (252)Cf source produces fission fragments which are thermalized and collected by a helium gas catcher into a low-energy particle beam with a charge of 1+ or 2+. An electron cyclotron resonance (ECR) ion source functions as a charge breeder in order to raise the ion charge sufficiently for acceleration in the ATLAS linac. The ECR charge breeder has achieved stable beam charge breeding efficiencies of 10.1% for (23)Na(7+), 17.9% for (39)K(10+), 15.6% for (84)Kr(17+), and 12.4% for (133)Cs(27+). For the radioactive beams, a charge breeding efficiency of 11.7% has been achieved for (143)Cs(27+) and 14.7% for (143)Ba(27+). The typical breeding times are 10 ms/charge state, but the source can be tuned such that this value increases to 100 ms/charge state with the best breeding efficiency corresponding to the longest breeding times-the variation of efficiencies with breeding time will be discussed. Efforts have been made to characterize and reduce the background contaminants present in the ion beam through judicious choice of q/m combinations. Methods of background reduction are being investigated based upon plasma chamber cleaning and vacuum practices. PMID:24593608

Vondrasek, R; Clark, J; Levand, A; Palchan, T; Pardo, R; Savard, G; Scott, R

2014-02-01

273

Lower-hybrid current drive experiments, synergism with the fast wave near ion cyclotron resonance and future plans on jet  

NASA Astrophysics Data System (ADS)

Acceleration of electrons up to energies in the MeV range has been observed in JET during combined application of Lower Hybrid and Fast Waves in fully non-inductively driven discharges. Without Fast Wave, the energy of the fast electrons remains below 200 keV. Up to 18% of the Fast Wave power has been estimated to be coupled to the fast electron population. This additional acceleration of electrons is defined as synergy between LH and Fast Wave. Specific experiments have indicated that the most likely responsible mechanism is the damping on fast electrons of an Ion Berstein Wave generated after mode conversion of the Fast Wave. The new JET RF systems, which are being prepared, (10 MW of Lower Hybrid and up to 20 MW of ICRF power at arbitrary phasing) will allow to assess if this synergism can be used to achieve the current drive efficiencies required in a reactor.

Gormezano, C.

1994-10-01

274

Comparison of particle-in-cell simulation with experiment for thetransport system of the superconducting electron cyclotron resonance ionsource VENUS  

SciTech Connect

The three-dimensional, particle-in-cell code WARP has been enhanced to allow end-to-end beam dynamics simulations of the VENUS beam transport system from the extraction region, through a mass-analyzing magnet, and up to a two-axis emittance scanner. This paper presents first results of comparisons between simulation and experimental data. A helium beam (He+, He2+) is chosen as an initial comparison beam due to its simple mass spectrum. Although a number of simplifications are made for the initial extracted beam, aberration characteristics appear in simulations that are also present in experimental phase space current density measurements. Further, measurements of phase space tilt indicate that simulations must have little or no space charge neutralization along the transport system to best agree with experiment. In addition, recent measurements of triangular beam structure immediately after the source are presented. This beam structure is related to the source magnetic confinement fields and will need to be taken into account as the initial beam approximations are lifted.

Todd, DamonS.; Leitner, Daniela; Leitner, Matthaeus; Lyneis,Claude M.; Qiang, Ji; Grote, Dave P.

2005-09-19

275

An instrument for fast acquisition of fluorescence decay curves at picosecond resolution designed for ``double kinetics'' experiments: Application to fluorescence resonance excitation energy transfer study of protein folding  

NASA Astrophysics Data System (ADS)

The information obtained by studying fluorescence decay of labeled biopolymers is a major resource for understanding the dynamics of their conformations and interactions. The lifetime of the excited states of probes attached to macromolecules is in the nanosecond time regime, and hence, a series of snapshot decay curves of such probes might - in principle - yield details of fast changes of ensembles of labeled molecules down to sub-microsecond time resolution. Hence, a major current challenge is the development of instruments for the low noise detection of fluorescence decay curves within the shortest possible time intervals. Here, we report the development of an instrument, picosecond double kinetics apparatus, that enables recording of multiple fluorescence decay curves with picosecond excitation pulses over wide spectral range during microsecond data collection for each curve. The design is based on recording and averaging multiphoton pulses of fluorescence decay using a fast 13 GHz oscilloscope during microsecond time intervals at selected time points over the course of a chemical reaction or conformational transition. We tested this instrument in a double kinetics experiment using reference probes (N-acetyl-tryptophanamide). Very low stochastic noise level was attained, and reliable multi-parameter analysis such as derivation of distance distributions from time resolved FRET (fluorescence resonance excitation energy transfer) measurements was achieved. The advantage of the pulse recording and averaging approach used here relative to double kinetics methods based on the established time correlated single photon counting method, is that in the pulse recording approach, averaging of substantially fewer kinetic experiments is sufficient for obtaining the data. This results in a major reduction in the consumption of labeled samples, which in many cases, enables the performance of important experiments that were not previously feasible.

Ishay, Eldad Ben; Hazan, Gershon; Rahamim, Gil; Amir, Dan; Haas, Elisha

2012-08-01

276

An instrument for fast acquisition of fluorescence decay curves at picosecond resolution designed for "double kinetics" experiments: application to fluorescence resonance excitation energy transfer study of protein folding.  

PubMed

The information obtained by studying fluorescence decay of labeled biopolymers is a major resource for understanding the dynamics of their conformations and interactions. The lifetime of the excited states of probes attached to macromolecules is in the nanosecond time regime, and hence, a series of snapshot decay curves of such probes might - in principle - yield details of fast changes of ensembles of labeled molecules down to sub-microsecond time resolution. Hence, a major current challenge is the development of instruments for the low noise detection of fluorescence decay curves within the shortest possible time intervals. Here, we report the development of an instrument, picosecond double kinetics apparatus, that enables recording of multiple fluorescence decay curves with picosecond excitation pulses over wide spectral range during microsecond data collection for each curve. The design is based on recording and averaging multiphoton pulses of fluorescence decay using a fast 13 GHz oscilloscope during microsecond time intervals at selected time points over the course of a chemical reaction or conformational transition. We tested this instrument in a double kinetics experiment using reference probes (N-acetyl-tryptophanamide). Very low stochastic noise level was attained, and reliable multi-parameter analysis such as derivation of distance distributions from time resolved FRET (fluorescence resonance excitation energy transfer) measurements was achieved. The advantage of the pulse recording and averaging approach used here relative to double kinetics methods based on the established time correlated single photon counting method, is that in the pulse recording approach, averaging of substantially fewer kinetic experiments is sufficient for obtaining the data. This results in a major reduction in the consumption of labeled samples, which in many cases, enables the performance of important experiments that were not previously feasible. PMID:22938314

Ishay, Eldad Ben; Hazan, Gershon; Rahamim, Gil; Amir, Dan; Haas, Elisha

2012-08-01

277

Bonding and molecular motions in the 1:1 molecular complexes of 1,4-diazabicyclo[2.2.2]octane with tetrahalomethane as studied by means of NQR  

NASA Astrophysics Data System (ADS)

NQR spectra were observed in the complexes of 1,4-diazabicyclo[2.2.2]octane (DABCO) with tetrachloromethane and tetrabromomethane at various temperatures. A phase transition was found at 319 K for DABCO·CBr 4. From spin-lattice relaxation times of nitrogen-14 in DABCO·CBr 4, the activation energy of the reorientation of DABCO about the N?N axis was calculated to be 18.3 kJ/mol which agrees with the value obtained from the second moment of proton NMR spectra. The bond nature is discussed using the Townes-Dailey treatment.

Okuda, T.; Suzuki, T.; Negita, H.

1983-12-01

278

Off-resonance rotating-frame relaxation dispersion experiment for (13)C in aromatic side chains using L-optimized TROSY-selection.  

PubMed

Protein dynamics on the microsecond-millisecond time scales often play a critical role in biological function. NMR relaxation dispersion experiments are powerful approaches for investigating biologically relevant dynamics with site-specific resolution, as shown by a growing number of publications on enzyme catalysis, protein folding, ligand binding, and allostery. To date, the majority of studies has probed the backbone amides or side-chain methyl groups, while experiments targeting other sites have been used more sparingly. Aromatic side chains are useful probes of protein dynamics, because they are over-represented in protein binding interfaces, have important catalytic roles in enzymes, and form a sizable part of the protein interior. Here we present an off-resonance R 1? experiment for measuring microsecond to millisecond conformational exchange of aromatic side chains in selectively (13)C labeled proteins by means of longitudinal- and transverse-relaxation optimization. Using selective excitation and inversion of the narrow component of the (13)C doublet, the experiment achieves significant sensitivity enhancement in terms of both signal intensity and the fractional contribution from exchange to transverse relaxation; additional signal enhancement is achieved by optimizing the longitudinal relaxation recovery of the covalently attached (1)H spins. We validated the L-TROSY-selected R 1? experiment by measuring exchange parameters for Y23 in bovine pancreatic trypsin inhibitor at a temperature of 328 K, where the ring flip is in the fast exchange regime with a mean waiting time between flips of 320 ?s. The determined chemical shift difference matches perfectly with that measured from the NMR spectrum at lower temperatures, where separate peaks are observed for the two sites. We further show that potentially complicating effects of strong scalar coupling between protons (Weininger et al. in J Phys Chem B 117: 9241-9247, 2013b) can be accounted for using a simple expression, and provide recommendations for data acquisition when the studied system exhibits this behavior. The present method extends the repertoire of relaxation methods tailored for aromatic side chains by enabling studies of faster processes and improved control over artifacts due to strong coupling. PMID:24706175

Weininger, Ulrich; Brath, Ulrika; Modig, Kristofer; Teilum, Kaare; Akke, Mikael

2014-05-01

279

Systematic study of the fragmentation of low-lying dipole strength in odd-{ital A} rare earth nuclei investigated in nuclear resonance fluorescence experiments  

SciTech Connect

Nuclear resonance fluorescence experiments were performed on the rare earth nuclei {sup 155}Gd and {sup 159}Tb to study the fragmentation of the {ital M}1 {ital scissors} {ital mode} in {ital odd} deformed nuclei and to establish a kind of systematics. Using the bremsstrahlung photon beam of the Stuttgart Dynamitron (end point energy 4.1 MeV) and high resolution Ge-{gamma} spectrometers detailed information was obtained on excitation energies, decay widths, transition probabilities, and branching ratios. The results are compared to those observed recently for the neighboring odd nuclei {sup 161,163}Dy and {sup 157}Gd. Whereas in the odd Dy isotopes the dipole strength is rather concentrated, both Gd isotopes show a strong fragmentation of the strength into about 25 ({sup 155}Gd) and 90 transitions ({sup 157}Gd) in the energy range 2{endash}4 MeV. The nucleus {sup 159}Tb linking the odd Dy and Gd isotopes exhibits an intermediate strength fragmentation. In general the observed total strength in the odd nuclei is reduced by a factor of 2{endash}3 as compared to their neighboring even-even isotopes. The different fragmentation behavior of the dipole strengths in the odd Dy and Gd isotopes is unexplained up to now. {copyright} {ital 1996 The American Physical Society.}

Nord, A.; Schiller, A.; Eckert, T.; Beck, O.; Besserer, J.; von Brentano, P.; Fischer, R.; Herzberg, R.; Jaeger, D.; Kneissl, U.; Margraf, J.; Maser, H.; Pietralla, N.; Pitz, H.H.; Rittner, M.; Zilges, A. [Institut fuer Strahlenphysik, Universitaet Stuttgart, Allmandring 3, D-70569 Stuttgart (Germany)] [Institut fuer Strahlenphysik, Universitaet Stuttgart, Allmandring 3, D-70569 Stuttgart (Germany); [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln (Germany)

1996-11-01

280

NQR investigation of pressure-induced charge transfer in oxygen-deficient YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} ({delta} = 0.38)  

SciTech Connect

Measurements of the pressure dependence of {sup 63}Cu nuclear quadrupole frequency in YBa{sub 2}Cu{sub 3}O{sub 6.62} from ambient pressure up to 1.5 GPa at 4k have been performed. {Tc} was found to increase with pressure: d{Tc}/dp {approximately} 5 K/GPa. All observed NQR lines are linear in pressure: dln{nu}{sub Q}/dp=z. We found positive z for the empty chain sites, consistent with ionic (Cu{sup 1+}) configuration in which the atom simply feels a squeezing lattice. Planar coppers close to the empty chains have positive z, while those that are close to full chains have z {approximately} 0. We present an analysis of the NQR result on the basis of the charge transfer model in which the mobile charges migrate from the chain to the plane sites. We deduced that a transfer of 0.021 holes to the O(2,3) sites would explain the result in YBa{sub 2}Cu{sub 3}O{sub 6.62}, whereas only 0.007 holes transfer in fully oxygenated YBa{sub 2}Cu{sub 3}O{sub 7}.

Reyes, A.P.; Ahrens, E.T.; Hammel, P.C.; Heffner, R.H. [Los Alamos National Lab., NM (United States); Takigawa, M. [International Business Machines Corp., Yorktown Heights, NY (United States). Thomas J. Watson Research Center

1992-03-01

281

Relaxation Anomalies of 69/71Ga NQR in the Paramagnetic State of the Itinerant Antiferromagnet UGa3: Possible Evidence for a Crossover to Localized Spin Fluctuations and Development of Orbital Fluctuations of 5f-electrons at High Temperatures  

NASA Astrophysics Data System (ADS)

The microscopic magnetic properties of the itinerant 5f-electron antiferromagnet UGa3 (TN=67 K) have been investigated in the paramagnetic state by means of Ga NQR studies of the two naturally abundant isotopes 69Ga and 71Ga. A striking and unusual increase of the nuclear longitudinal relaxation rate 1/T1 has been observed above 230 K, which includes a strong component of nuclear quadrupolar relaxation. Both the magnetic and quadrupolar relaxation rates have been found to increase simultaneously above 230 K. Correspondingly, the NQR frequencies also show a clear deviation from lower-T T3/2-dependence above 230 K. These results are discussed in terms of a crossover from lower-T itinerant to higher-T more localized spin fluctuations and associated orbital fluctuations on the part of the U 5f electrons. A mechanism of transferred quadrupole interaction is presented, through which the fluctuations among the U 5f orbitals involve those among the counter-anion Ga 4p orbitals and thereby cause quadrupolar relaxation of the Ga nuclear spins.

Takagi, Shigeru; Muraoka, Hideaki; Matsuda, Tatsuma D.; Haga, Yoshinori; Kambe, Shinsaku; Walstedt, Russell E.; Yamamoto, Etsuji; ?nuki, Yoshichika

2004-02-01

282

Supramolecular synthon pattern in solid clioquinol and cloxiquine (APIs of antibacterial, antifungal, antiaging and antituberculosis drugs) studied by ³?Cl NQR, ¹H-¹?O and ¹H-¹?N NQDR and DFT/QTAIM.  

PubMed

The quinolinol derivatives clioquinol (5-chloro-7-iodo-8-quinolinol, Quinoform) and cloxiquine (5-chloro-8-quinolinol) were studied experimentally in the solid state via ³?Cl NQR, ¹H-¹?O and ¹H-¹?N NQDR spectroscopies, and theoretically by density functional theory (DFT). The supramolecular synthon pattern of O-H···N hydrogen bonds linking dimers and ?-? stacking interactions were described within the QTAIM (quantum theory of atoms in molecules) /DFT (density functional theory) formalism. Both proton donor and acceptor sites in O-H···N bonds were characterized using ¹H-¹?O and ¹H-¹?N NQDR spectroscopies and QTAIM. The possibility of the existence of O-H···H-O dihydrogen bonds was excluded. The weak intermolecular interactions in the crystals of clioquinol and cloxiquine were detected and examined. The results obtained in this work suggest that considerable differences in the NQR parameters for the planar and twisted supramolecular synthons permit differentiation between specific polymorphic forms, and indicate that the more planar supramolecular synthons are accompanied by a greater number of weaker hydrogen bonds linking them and stronger ?···? stacking interactions. PMID:21080020

Latosi?ska, Jolanta Natalia; Latosi?ska, Magdalena; Tomczak, Marzena Agnieszka; Seliger, Janez; Zagar, Veselko

2011-07-01

283

High precision measurement of the 11Li and 9Li quadrupole moment ratio using zero-field ?-NQR  

NASA Astrophysics Data System (ADS)

The ratio of electric quadrupole moments of 11Li and 9Li was measured using the zero-field ?-detected nuclear quadrupole resonance technique at Triumf-Isac. The precision on the ratio Q11/Q9 = 1.0775(12) was improved by more than one order of magnitude and an absolute value for the quadrupole moment of 11Li was inferred. Systematic effects, as argued here, are not expected to contribute to the ratio on this scale. The zero-field spin-lattice relaxation time for 8Li implanted within SrTiO3 at 295?K in zero-field was found to be T1 = 1.73(2)?s. A comparison of the quadrupole moments of 9, 11Li and their ratio is made with the latest models, however, no conclusion may yet be drawn owing to the size of the theoretical uncertainties.

Voss, A.; Pearson, M. R.; Buchinger, F.; Crawford, J. E.; Kiefl, R. F.; Levy, C. D. P.; MacFarlane, W. A.; Mané, E.; Morris, G. D.; Shelbaya, O. T. J.; Song, Q.; Wang, D.

2014-01-01

284

Superconducting microwave resonator for millikelvin magnetic resonance force microscopy  

NASA Astrophysics Data System (ADS)

We have fabricated a superconducting resonator capable of generating a strong microwave magnetic field in a small (100 ?m) volume for low temperature magnetic resonance experiments. While the resonator was specifically developed for use at millikelvin temperatures in a dilution refrigerator, where the total cooling power is limited to a few hundred microwatts, it is also useful at temperatures up to 5 K. The resonator consists of a 220 ?m diameter, 2-1/2 turn niobium coil resonating with a short section of niobium microstripline. At a resonance frequency of 3 GHz, the loaded Q of the resonator was 780. The field strength was characterized by performing electron spin nutations. Operating at 100 mK with 320 ?W of dissipated power, the resonator generated a field of 4 G at a distance of 100 ?m from the coil.

Mamin, H. J.; Budakian, R.; Rugar, D.

2003-05-01

285

Ohmic effects in quasioptical resonators  

SciTech Connect

Several properties of the Fabry-Perot-type open resonator used in the quasioptical gyrotron (QOG) and the quasioptical induced resonance electron cyclotron (IREC) maser are derived. The electric fields of the normal modes are given for the general case of the resonator axis tilted with respect to the direction perpendicular to the electron beam axis. The ohmic quality factor and the power dissipated in the mirrors are derived, as is the energy stored in the resonator. The time dependence of the mirror heating, relevant for pulsed experiments, is also derived. The formulae are applied to an example of current relevance, the quasioptical IREC maser resonator.

Hargreaves, T.A.; Fischer, R.P.; McCowan, R.B.; Fliflet, A.W. (Naval Research Lab., Washington, DC (United States))

1991-01-01

286

Prostate Postbrachytherapy Seed Distribution: Comparison of High-Resolution, Contrast-Enhanced, T1- and T2Weighted Endorectal Magnetic Resonance Imaging Versus Computed Tomography: Initial Experience  

Microsoft Academic Search

Purpose: To compare contrast-enhanced, T1-weighted, three-dimensional magnetic resonance imaging (CEMR) and T2-weighted magnetic resonance imaging (T2MR) with computed tomography (CT) for prostate brachytherapy seed location for dosimetric calculations. Methods and Materials: Postbrachytherapy prostate MRI was performed on a 1.5 Tesla unit with combined surface and endorectal coils in 13 patients. Both CEMR and T2MR used a section thickness of 3

B. Nicolas Bloch; Robert E. Lenkinski; Thomas H. Helbich; Long Ngo; Renee Oismueller; Silvia Jaromi; Klaus Kubin; Robert Hawliczek; Irving D. Kaplan; Neil M. Rofsky

2007-01-01

287

Optical resonator  

NASA Technical Reports Server (NTRS)

The invention discloses a semi-ring Fabry-Perot (SRFP) optical resonator structure comprising a medium including an edge forming a reflective facet and a waveguide within the medium, the waveguide having opposing ends formed by the reflective facet. The performance of the SRFP resonator can be further enhanced by including a Mach-Zehnder interferometer in the waveguide on one side of the gain medium. The optical resonator can be employed in a variety of optical devices. Laser structures using at least one SRFP resonator are disclosed where the resonators are disposed on opposite sides of a gain medium. Other laser structures employing one or more resonators on one side of a gain region are also disclosed.

Taghavi-Larigani, Shervin (Inventor); Vanzyl, Jakob J. (Inventor); Yariv, Amnon (Inventor)

2006-01-01

288

Resonance acoustic field position sensor  

NASA Astrophysics Data System (ADS)

An acoustic position sensor, based on a piezoelectric-sound-resonance cavity (PSRC), is reported in which a resonance acoustic field is used as the sensing mechanism. It has been discovered that an inserted object or an object motion in the sound radiation field results in changes in the resonance state of the PSRC. Experiments have demonstrated a high position resolution in the axial direction, and also good sensitivity in the transverse.

Dong, Shuxiang; Bai, Feiming; Li, Jie-Fang; Viehland, Dwight

2003-06-01

289

Possible Multiple Gap Superconductivity with Line Nodes in Heavily Hole-Doped Superconductor KFe2As2 Studied by 75As Nuclear Quadrupole Resonance and Specific Heat  

NASA Astrophysics Data System (ADS)

We report the 75As nuclear quadrupole resonance (NQR) and specific heat measurements of the heavily hole-doped superconductor KFe2As2 (superconducting transition temperature Tc? 3.5 K). The spin-lattice relaxation rate 1/T1 in the superconducting state exhibits a gradual temperature dependence with no coherence peak below Tc. The quasiparticle specific heat CQP/T shows a small jump, which is about 30% of the electronic specific heat coefficient just below Tc. The CQP/T suggests the existence of low-energy quasiparticle excitation at the lowest measurement temperature T=0.4 K? Tc/10. The T dependences of 1/T1 and CQP/T can be explained by a multiple nodal superconducting gap scenario rather than by a multiple fully gapped s±-wave scenario determined using simple gap analysis.

Fukazawa, Hideto; Yamada, Yuji; Kondo, Kenji; Saito, Taku; Kohori, Yoh; Kuga, Kentarou; Matsumoto, Yosuke; Nakatsuji, Satoru; Kito, Hijiri; Shirage, Parasharam M.; Kihou, Kunihiro; Takeshita, Nao; Lee, Chul-Ho; Iyo, Akira; Eisaki, Hiroshi

2009-08-01

290

High-field 4.23 tesla magnetic resonance imaging: initial experience in turbo-inversion recovery imaging and fMRI physics  

Microsoft Academic Search

High-field magnetic resonance imaging (MRI) offers functional, biochemical and physiological information. High field is advantageous for both fMRI signal generated from deoxyhemoglobin and blood oxygen, and intracellular sodium by inversion recovery MRI imaging. High field MRI was used to image human and primates for sodium MRI imaging.

Rakesh Sharma

2004-01-01

291

Invited Article: Dynamics of diatomic molecules confined in a chemical trap II. Nuclear magnetic resonance experiments on CO in solid C60  

Microsoft Academic Search

A detailed nuclear magnetic resonance (NMR) study of CO isolated in a matrix of C60 is reported. CO in C60 shows both quantum and classical behaviour on the NMR timescale. Below 10 K orientational quantum tunnelling for part of the CO molecules is inferred from an analysis of the line shapes. Above 30 K, however, the system can be treated

M. Tomaselli

2003-01-01

292

Superconducting coplanar waveguide resonators for electron spin resonance applications  

NASA Astrophysics Data System (ADS)

Superconducting coplanar waveguide (CPW) resonators are a promising alternative to conventional volume resonators for electron spin resonance (ESR) experiments where the sample volume and thus the number of spins is small. However, the magnetic fields required for ESR could present a problem for Nb superconducting resonators, which can be driven normal. Very thin Nb films (50 nm) and careful alignment of the resonators parallel to the magnetic field avoid driving the Nb normal, but flux trapping can still be an issue. Trapped flux reduces the resonator Q-factor, can lead to resonant frequency instability, and can lead to magnetic field inhomogeneities. At temperatures of 1.9 K and in a magnetic field 0.32 T, we have tested X-band resonators fabricated directly on the surface of a silicon sample. Q-factors in excess of 15,000 have been obtained. A thin layer of GE varnish applied directly to the resonator has been used to glue a sapphire wafer to its surface, and we still find Q-factors of 16,000 or more in the 0.32 T field. ESR applications of these resonators will be discussed.

Sigillito, A. J.; Jock, R. M.; Tyryshkin, A. M.; Malissa, H.; Lyon, S. A.

2013-03-01

293

Parallel image-acquisition in continuous-wave electron paramagnetic resonance imaging with a surface coil array: Proof-of-concept experiments.  

PubMed

This article describes a feasibility study of parallel image-acquisition using a two-channel surface coil array in continuous-wave electron paramagnetic resonance (CW-EPR) imaging. Parallel EPR imaging was performed by multiplexing of EPR detection in the frequency domain. The parallel acquisition system consists of two surface coil resonators and radiofrequency (RF) bridges for EPR detection. To demonstrate the feasibility of this method of parallel image-acquisition with a surface coil array, three-dimensional EPR imaging was carried out using a tube phantom. Technical issues in the multiplexing method of EPR detection were also clarified. We found that degradation in the signal-to-noise ratio due to the interference of RF carriers is a key problem to be solved. PMID:24374749

Enomoto, Ayano; Hirata, Hiroshi

2014-02-01

294

Application of the double relaxation oscillation superconducting quantum interference device sensor to micro-tesla 1H nuclear magnetic resonance experiments  

Microsoft Academic Search

We developed an ultra-low field (ULF)-nuclear magnetic resonance (NMR) measurement system capable of working with a measurement field (Bm) of several micro-tesla and performed basic NMR studies with a double relaxation oscillation superconducting quantum interference device (DROS) instead of conventional dc-SQUIDs. DROS is a SQUID sensor utilizing a relaxation oscillation between a dc-SQUID and a relaxation circuit; the new unit

Chan Seok Kang; Kiwoong Kim; Seong-Joo Lee; Seong-Min Hwang; Jin-Mok Kim; Kwon Kyu Yu; Hyukchan Kwon; Sang Kil Lee; Yong-Ho Lee

2011-01-01

295

Piezoelectric d33 coefficients in foamed and layered polymer piezoelectrets from dynamic mechano-electrical experiments, electro-mechanical resonance spectroscopy and acoustic-transducer measurements  

NASA Astrophysics Data System (ADS)

Piezoelectrets are novel transducer materials which can be widely applied in sensors and actuators. Here, three techniques for determining piezoelectric d33 coefficients of piezoelectrets are reviewed and compared. Two types of piezoelectrets, polyethylene-naphthalate (PEN) polymer-foam piezoelectrets and fluorinated ethylene-propylene (FEP) copolymer-layer piezoelectrets, have been prepared and measured by means of dynamic, resonance, and acoustical methods. The dynamic measurements show that the d33 coefficient of PEN-foam samples clearly decreases with increasing stress, but 80% of the initial d33 can be retained after 1800 cycles of a continuous dynamic measurement in a mechanical fatigue test. The resonance measurements demonstrate that both PEN-foam and FEP-layer samples exhibit clear electro-mechanical resonances. PEN-foam samples show elastic moduli in the range from 1 to 12 MPa and d33 values up to 500 pC N-1, while FEP-layer samples show homogeneous elastic moduli of about 0.3 MPa and d33 values of about 280 pC N-1. The acoustical measurements reveal that both PEN-foam and FEP-layer samples exhibit stable frequency responses in the range from 5.7 to 20 kHz. In addition, d33 coefficients obtained with different experimental methods are in good agreement with each other, which confirms the reliability of all three techniques.

Fang, Peng; Holländer, Lars; Wirges, Werner; Gerhard, Reimund

2012-03-01

296

Fast response resonance fluorescence CO measurements aboard the C-130: Instrument characterization and measurements made during North Atlantic Regional Experiment 1993  

NASA Astrophysics Data System (ADS)

The resonance fluorescence instrument for the measurement of atmospheric CO described by Volz and Kley [1985] was characterized in the laboratory and adapted for use on aircraft. A major finding was that the background signal is largely due to continuum resonance Raman scattering by molecular oxygen and thus cannot be reduced by better design. The instrument was deployed on the United Kingdom Meteorological Office (UKMO) C-130 Hercules during August 1993 and in subsequent missions. The instrument achieved a detection limit (3?) of 5 ppb at a time resolution of 30 s. For a typical CO concentration of 100 ppb, the signal-to-noise ratio (1?) was 15 for an integration time of 2 s, which was the minimum time resolution that could be obtained during the flights because of limited pump capacity. Data collected over the North Atlantic show distinct layers of CO above the atmospheric boundary layer (ABL) that are well correlated with enhanced NOy mixing ratios and indicate transport of pollution from the American continent. Such layers, albeit much less pronounced, were encountered in westerly flow in the midtroposphere west of the coast of Portugal. Fairly high mixing ratios were observed in the lower troposphere associated with transport from southern Europe.

Gerbig, Christoph; Kley, Dieter; Volz-Thomas, Andreas; Kent, Joss; Dewey, Ken; McKenna, Danny S.

1996-12-01

297

Accurate computer-aided quantification of left ventricular parameters: experience in 1555 cardiac magnetic resonance studies from the Framingham Heart Study.  

PubMed

Quantitative analysis of short-axis functional cardiac magnetic resonance images can be performed using automatic contour detection methods. The resulting myocardial contours must be reviewed and possibly corrected, which can be time-consuming, particularly when performed across all cardiac phases. We quantified the impact of manual contour corrections on both analysis time and quantitative measurements obtained from left ventricular short-axis cine images acquired from 1555 participants of the Framingham Heart Study Offspring cohort using computer-aided contour detection methods. The total analysis time for a single case was 7.6 ± 1.7 min for an average of 221 ± 36 myocardial contours per participant. This included 4.8 ± 1.6 min for manual contour correction of 2% of all automatically detected endocardial contours and 8% of all automatically detected epicardial contours. However, the impact of these corrections on global left ventricular parameters was limited, introducing differences of 0.4 ± 4.1 mL for end-diastolic volume, -0.3 ± 2.9 mL for end-systolic volume, 0.7 ± 3.1 mL for stroke volume, and 0.3 ± 1.8% for ejection fraction. We conclude that left ventricular functional parameters can be obtained under 5 min from short-axis functional cardiac magnetic resonance images using automatic contour detection methods. Manual correction more than doubles analysis time, with minimal impact on left ventricular volumes and ejection fraction. PMID:22021128

Hautvast, Gilion L T F; Salton, Carol J; Chuang, Michael L; Breeuwer, Marcel; O'Donnell, Christopher J; Manning, Warren J

2012-05-01

298

Laser Resonator  

NASA Technical Reports Server (NTRS)

An optical resonator cavity configuration has a unitary mirror with oppositely directed convex and concave reflective surfaces disposed into one fold and concertedly reversing both ends of a beam propagating from a laser rod disposed between two total internal reflection prisms. The optical components are rigidly positioned with perpendicularly crossed virtual rooflines by a compact optical bed. The rooflines of the internal reflection prisms, are arranged perpendicularly to the axis of the laser beam and to the optical axes of the optical resonator components.

Harper, L. L. (inventor)

1983-01-01

299

Frequency stability of dielectric loaded HTS microwave resonators  

Microsoft Academic Search

High Q dielectric loaded superconducting resonators have many potential microwave applications. A key issue for many of these is the stability with which the resonant frequencies of such resonators may be realised, for use as frequency references etc. We report experiments on a number of different resonator geometries using YBCO thick films as planar shields for composite dielectric structures. The

J. Gallop; L. Hao; F. Abbas; C. D. Langham

1997-01-01

300

An Electromagnetic Resonance Circuit for Liquid Level Detection  

ERIC Educational Resources Information Center

Electromagnetic resonators are often used to detect foreign materials. Here we present a simple experiment for the measurement of liquid level. The resonator, consisting of a coil and a capacitor, is brought to resonance by an external magnetic field source, and the corresponding resonance frequency is determined using Fourier analysis combined…

Hauge, B. L.; Helseth, L. E.

2012-01-01

301

Gravitational Wave Generation and Detection Using Acoustic Resonators and Coupled Resonance Chambers  

Microsoft Academic Search

An experiment is described for the generation and detection of High-Frequency Gravitational Waves (HFGWs) in the laboratory utilizing acoustic piezoelectric resonators for generation, and coupled resonance chambers for detection. Film Bulk Acoustic Resonators or FBARs (similar to those utilized in commercial cellular telephones) energized by magnetrons (similar to those utilized in microwave ovens) are distributed in a ring-shaped array several

R. Clive Woods; Robert M. L. Baker

2005-01-01

302

Prostate Postbrachytherapy Seed Distribution: Comparison of High-Resolution, Contrast-Enhanced, T1- and T2-Weighted Endorectal Magnetic Resonance Imaging Versus Computed Tomography: Initial Experience  

SciTech Connect

Purpose: To compare contrast-enhanced, T1-weighted, three-dimensional magnetic resonance imaging (CEMR) and T2-weighted magnetic resonance imaging (T2MR) with computed tomography (CT) for prostate brachytherapy seed location for dosimetric calculations. Methods and Materials: Postbrachytherapy prostate MRI was performed on a 1.5 Tesla unit with combined surface and endorectal coils in 13 patients. Both CEMR and T2MR used a section thickness of 3 mm. Spiral CT used a section thickness of 5 mm with a pitch factor of 1.5. All images were obtained in the transverse plane. Two readers using CT and MR imaging assessed brachytherapy seed distribution independently. The dependency of data read by both readers for a specific subject was assessed with a linear mixed effects model. Results: The mean percentage ({+-} standard deviation) values of the readers for seed detection and location are presented. Of 1205 implanted seeds, CEMR, T2MR, and CT detected 91.5% {+-} 4.8%, 78.5% {+-} 8.5%, and 96.1% {+-} 2.3%, respectively, with 11.8% {+-} 4.5%, 8.5% {+-} 3.5%, 1.9% {+-} 1.0% extracapsular, respectively. Assignment to periprostatic structures was not possible with CT. Periprostatic seed assignments for CEMR and T2MR, respectively, were as follows: neurovascular bundle, 3.5% {+-} 1.6% and 2.1% {+-} 0.9%; seminal vesicles, 0.9% {+-} 1.8% and 0.3% {+-} 0.7%; periurethral, 7.1% {+-} 3.3% and 5.8% {+-} 2.9%; penile bulb, 0.6% {+-} 0.8% and 0.3% {+-} 0.6%; Denonvillier's Fascia/rectal wall, 0.5% {+-} 0.6% and 0%; and urinary bladder, 0.1% {+-} 0.3% and 0%. Data dependency analysis showed statistical significance for the type of imaging but not for reader identification. Conclusion: Both enumeration and localization of implanted seeds are readily accomplished with CEMR. Calculations with MRI dosimetry do not require CT data. Dose determinations to specific extracapsular sites can be obtained with MRI but not with CT.

Bloch, B. Nicolas [Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States); Department of Radiology, General Hospital Vienna, Medical University Vienna, Vienna (Austria)], E-mail: nbloch@bidmc.harvard.edu; Lenkinski, Robert E. [Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States); Helbich, Thomas H. [Department of Radiology, General Hospital Vienna, Medical University Vienna, Vienna (Austria); Ngo, Long [Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States); Oismueller, Renee [Institute for Radio-Oncology, Danube Hospital, Vienna (Austria); Jaromi, Silvia; Kubin, Klaus [Department of Radiology, General Hospital Vienna, Medical University Vienna, Vienna (Austria); Hawliczek, Robert [Institute for Radio-Oncology, Danube Hospital, Vienna (Austria); Kaplan, Irving D. [Department of Radiation Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States); Rofsky, Neil M. [Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States)

2007-09-01

303

Resonant ultrasonic attenuation in emulsions  

NASA Astrophysics Data System (ADS)

We report the achievement of scattering resonant emulsions devoted to the frequency-control of acoustic attenuation in the megahertz range. By means of robotics, we produced highly monodisperse, in both size and shape, fluorinated-oil droplet suspensions, providing experimental evidence of several Mie scattering resonances. Ultrasonic experiments performed in such complex media are compared, with an excellent quantitative agreement, to theoretical predictions derived within the framework of the independent scattering approximation.

Brunet, Thomas; Mascaro, Benoit; Poncelet, Olivier; Aristégui, Christophe; Raffy, Simon; Mondain-Monval, Olivier; Leng, Jacques

2013-08-01

304

Sound-resonance hydrogen sensor  

NASA Astrophysics Data System (ADS)

A hydrogen sensor is reported in which a small piezoelectric-sound-resonance-cavity (PSRC) is used as the sensing element. Detection utilizes sound resonance and acoustic property differences between H2 and air as a sensing mechanism. Changes in H2 concentration result in a shift of the sound-resonance state of the PSRC. Preliminary experiments have demonstrated a sensitivity limit of 8 ppm, a fast response time ~1.5 second, and detection capabilities over a broad concentration range 10-5

Dong, Shuxiang; Bai, Feiming; Li, Jiefang; Viehland, Dwight

2003-06-01

305

Spurious Resonances and Modelling of Composite Resonators.  

National Technical Information Service (NTIS)

Several three-dimensional models have been developed for explaining the characteristics of composite resonators. The agreement between the resonance spectra predicted by the models and the experimental data is excellent, including spurious resonance frequ...

K. B. Yoo H. Ueberall D. Ashrafi S. Ashrafi

1983-01-01

306

SENSITIVITY OF ENDOSCOPIC ULTRASOUND, MULTIDETECTOR COMPUTER TOMOGRAPHY AND MAGNETIC RESONANCE CHOLANGIOPANCREATOGRAPHY IN THE DIAGNOSIS OF PANCREAS DIVISUM: A TERTIARY CENTER EXPERIENCE  

PubMed Central

OBJECTIVES There are limited data comparing imaging modalities in the diagnosis of pancreas divisum. We aimed to: 1. Evaluate the sensitivity of endoscopic ultrasound (EUS), magnetic resonance cholangiopancreatography (MRCP) and multi-detector computed tomography (MDCT) for pancreas divisum. 2. Assess interobserver agreement (IOA) among expert radiologists for detecting pancreas divisum on MDCT and MRCP. METHODS For this retrospective cohort study, we identified 45 consecutive patients with pancreaticobiliary symptoms and pancreas divisum established by endoscopic retrograde pancreatography (ERP) who underwent EUS and cross-sectional imaging. The control group was composed of patients without pancreas divisum who underwent ERP and cross-sectional imaging. RESULTS The sensitivity of EUS for pancreas divisum was 86.7%, significantly higher than sensitivity reported in the medical records for MDCT (15.5%) or MRCP (60%) [p<0.001 for each]. On review by expert radiologists the sensitivity of MDCT increased to 83.3% in cases where the pancreatic duct was visualized, with fair IOA (?=0.34). Expert review of MRCPs did not identify any additional cases of pancreas divisum; IOA was moderate (?=0.43). CONCLUSIONS EUS is a sensitive test for diagnosing pancreas divisum and is superior to MDCT and MRCP. Review of MDCT studies by expert radiologists substantially raises its sensitivity for pancreas divisum.

Kushnir, Vladimir M.; Wani, Sachin B.; Fowler, Kathryn; Menias, Christine; Varma, Rakesh; Narra, Vamsi; Hovis, Christine; Murad, Faris; Mullady, Daniel; Jonnalagadda, Sreenivasa S.; Early, Dayna S.; Edmundowicz, Steven A.; Azar, Riad R.

2014-01-01

307

Fe-H/D stretching and bending modes in nuclear resonant vibrational, Raman and infrared spectroscopies: Comparisons of density functional theory and experiment  

PubMed Central

Infrared, Raman, and nuclear resonant vibrational (NRVS) spectroscopies have been used to address the Fe-H bonding in trans-Fe(H)(CO) iron hydride compound, Fe(H)(CO)(dppe)2, dppe = 1,2-bis(diphenylphosphino)ethane. H and D isotopomers of the compound, with the selective substitution at the metal-coordinated hydrogen, have been considered in order to address the Fe-H/D stretching and bending modes. Experimental results are compared to the normal mode analysis by the density functional theory (DFT). The results are that (i) the IR spectrum does not clearly show Fe–H stretching or bending modes; (ii) Fe–H stretching modes are clear but weak in the Raman spectrum, and Fe–H bending modes are weak; (iii) NRVS 57Fe spectroscopy resolves Fe-H bending clearly, but Fe–H or Fe–D stretching is above its experimentally resolved frequency range. DFT caclulations (with no scaling of frequencies) show intensities and peak locations that allow unambigous correlations between observed and calculated features, with frequency errors generally less than 15 cm?1. Prospects for using these techniques to unravel vibrational modes of protein active sites are discussed.

Pelmenschikov, Vladimir; Guo, Yisong; Wang, Hongxin; Cramer, Stephen P.; Case, David A.

2010-01-01

308

Fe-H/D stretching and bending modes in nuclear resonant vibrational, Raman and infrared spectroscopies: comparisons of density functional theory and experiment.  

PubMed

Infrared, Raman, and nuclear resonant vibrational (NRVS) spectroscopies have been used to address the Fe-H bonding in trans-HFe(CO) iron hydride compound, HFe(CO)(dppe)2, dppe = 1,2-bis(diphenylphosphino)ethane. H and D isotopomers of the compound, with selective substitution at the metal-coordinated hydrogen, have been considered in order to address the Fe-H/D stretching and bending modes. Experimental results are compared to the normal mode analysis by density functional theory (DFT). The results are that (i) the IR spectrum does not clearly show Fe-H stretching or bending modes; (ii) Fe-H stretching modes are clear but weak in the Raman spectrum, and Fe-H bending modes are weak; (iii) NRVS 57Fe spectroscopy resolves Fe-H bending clearly, but Fe-H or Fe-D stretching is above its experimentally resolved frequency range. DFT calculations (with no scaling of frequencies) show intensities and peak locations that allow unambiguous correlations between observed and calculated features, with frequency errors generally less than 15 cm(-1). Prospects for using these techniques to unravel vibrational modes of protein active sites are discussed. PMID:21322496

Pelmenschikov, Vladimir; Guo, Yisong; Wang, Hongxin; Cramer, Stephen P; Case, David A

2011-01-01

309

Resonant behavior of dielectric objects (electrostatic resonances).  

PubMed

Resonant behavior of dielectric objects occurs at certain frequencies for which the object permittivity is negative and the free-space wavelength is large in comparison with the object dimensions. Unique physical features of these resonances are studied and a novel technique for the calculation of resonance values of permittivity, and hence resonance frequencies, is proposed. Scale invariance of resonance frequencies, unusually strong orthogonality properties of resonance modes, and a two-dimensional phenomenon of "twin" spectra are reported. The paper concludes with brief discussions of optical controllability of these resonances in semiconductor nanoparticles and a plausible, electrostatic resonance based, mechanism for nucleation and formation of ball lightning. PMID:14754117

Fredkin, D R; Mayergoyz, I D

2003-12-19

310

Gramicidin A backbone and side chain dynamics evaluated by molecular dynamics simulations and nuclear magnetic resonance experiments. I: molecular dynamics simulations.  

PubMed

Gramicidin A (gA) channels provide an ideal system to test molecular dynamics (MD) simulations of membrane proteins. The peptide backbone lines a cation-selective pore, and due to the small channel size, the average structure and extent of fluctuations of all atoms in the peptide will influence ion permeation. This raises the question of how well molecular mechanical force fields used in MD simulations and potential of mean force (PMF) calculations can predict structure and dynamics as well as ion permeation. To address this question, we undertook a comparative study of nuclear magnetic resonance (NMR) observables predicted by fully atomistic MD simulations on a gA dimer embedded in a sodium dodecyl sulfate (SDS) micelle with measurements of the gA dimer backbone and tryptophan side chain dynamics using solution-state (15)N NMR on gA dimers in SDS micelles (Vostrikov, V. V.; Gu, H.; Ingo?lfsson, H. I.; Hinton, J. F.; Andersen, O. S.; Roux, B.; Koeppe, R. E., II. J. Phys. Chem. B2011, DOI 10.1021/jp200906y , accompanying article). This comparison enables us to examine the robustness of the MD simulations done using different force fields as well as their ability to predict important features of the gA channel. We find that MD is able to predict NMR observables, including the generalized order parameters (S(2)), the (15)N spin-lattice (T(1)) and spin-spin (T(2)) relaxation times, and the (1)H-(15)N nuclear Overhauser effect (NOE), with remarkable accuracy. To examine further how differences in the force fields can affect the channel conductance, we calculated the PMF for K(+) and Na(+) permeation through a gA channel in a dimyristoylphosphatidylcholine (DMPC) bilayer. In this case, we find that MD is less successful in quantitatively predicting the single-channel conductance. PMID:21574563

Ingólfsson, Helgi I; Li, Yuhui; Vostrikov, Vitaly V; Gu, Hong; Hinton, James F; Koeppe, Roger E; Roux, Benoît; Andersen, Olaf S

2011-06-01

311

First Clinical Experience with the Magnetic Resonance Imaging Contrast Agent and Superoxide Dismutase Mimetic Mangafodipir as an Adjunct in Cancer Chemotherapy--A Translational Study12  

PubMed Central

Preclinical research suggests that the clinically approved magnetic resonance imaging contrast agent mangafodipir may protect against adverse events (AEs) caused by chemotherapy, without interfering negatively with the anticancer efficacy. The present translational study tested if pretreatment with mangafodipir lowers AEs during curative (adjuvant) FOLFOX6 chemotherapy in stage III colon cancer (Dukes' C). The study was originally scheduled to include 20 patients, but because of the unforeseen withdrawal of mangafodipir from the market, the study had to be closed after 14 patients had been included. The withdrawal of mangafodipir was purely based on commercial considerations from the producer and not on any safety concerns. The patients were treated throughout the first 3 of 12 scheduled cycles. Patients were randomized to a 5-minute infusion of either mangafodipir or placebo (7 in each group). AEs were evaluated according to the National Cancer Institute's (NCI) Common Terminology Criteria for Adverse Events and the Sanofi-NCI criteria. The primary end points were neutropenia and neurosensory toxicity. There were four AEs of grade 3 (severe) and one AE of grade 4 (life threatening) in four patients in the placebo group, whereas there were none in the mangafodipir group (P < .05). Of the grade 3 and 4 events, two were neutropenia and one was neurosensory toxicity. Furthermore, white blood cell count was statistically, significantly higher in the mangafodipir group than in the placebo group (P < .01) after treatment with FOLFOX. This small feasibility study seems to confirm what has been demonstrated preclinically, namely, that pretreatment with mangafodipir lowers AEs during adjuvant 5-fluorouracil plus oxaliplatin-based chemotherapy in colon cancer patients.

Karlsson, Jan Olof G; Adolfsson, Karin; Thelin, Bo; Jynge, Per; Andersson, Rolf GG; Falkmer, Ursula G

2012-01-01

312

High-throughput backbone resonance assignment of small 13C,15N-labeled proteins by a triple-resonance experiment with four sequential connectivity pathways using chemical shift-dependent, apparent 1J(1H,13C): HNCACBcodedHAHB.  

PubMed

The proposed three-dimensional triple-resonance experiment HNCACBcodedHAHB correlates sequential 15N, 1H moieties via the chemical shifts of 13Calpha, 13Cbeta, 1Halpha, and 1Hbeta. The four sequential correlation pathways are achieved by the incorporation of the concept of chemical shift-coding [J. Biomol. NMR 25 (2003) 281] to the TROSY-HNCACB experiment. The monitored 1Halpha and 1Hbeta chemical shifts are then coded in the line shape of the cross-peaks of 13Calpha, 13Cbeta along the 13C dimension through an apparent residual scalar coupling, the size of which depends on the attached hydrogen chemical shift. The information of four sequential correlation pathways enables a rapid backbone assignment. The HNCACBcodedHAHB experiment was applied to approximately 85% labeled 13C,15N-labeled amino-terminal fragment of Vaccinia virus DNA topoisomerase I comprising residues 1-77. After one day of measurement on a Bruker Avance 700 MHz spectrometer and 8 h of manual analysis of the spectrum 93% of the backbone assignment was achieved. PMID:14643715

Pegan, Scott; Kwiatkowski, Witek; Choe, Senyon; Riek, Roland

2003-12-01

313

Silicon photonic resonator sensors and devices  

NASA Astrophysics Data System (ADS)

Silicon photonic resonators, implemented using silicon-on-insulator substrates, are promising for numerous applications. The most commonly studied resonators are ring/racetrack resonators. We have fabricated these and other resonators including disk resonators, waveguide-grating resonators, ring resonator reflectors, contra-directional grating-coupler ring resonators, and racetrack-based multiplexer/demultiplexers. While numerous resonators have been demonstrated for sensing purposes, it remains unclear as to which structures provide the highest sensitivity and best limit of detection; for example, disc resonators and slot-waveguide-based ring resonators have been conjectured to provide an improved limit of detection. Here, we compare various resonators in terms of sensor metrics for label-free bio-sensing in a micro-fluidic environment. We have integrated resonator arrays with PDMS micro-fluidics for real-time detection of biomolecules in experiments such as antigen-antibody binding reaction experiments using Human Factor IX proteins. Numerous resonators are fabricated on the same wafer and experimentally compared. We identify that, while evanescent-field sensors all operate on the principle that the analyte's refractive index shifts the resonant frequency, there are important differences between implementations that lie in the relationship between the optical field overlap with the analyte and the relative contributions of the various loss mechanisms. The chips were fabricated in the context of the CMC-UBC Silicon Nanophotonics Fabrication course and workshop. This yearlong, design-based, graduate training program is offered to students from across Canada and, over the last four years, has attracted participants from nearly every Canadian university involved in photonics research. The course takes students through a full design cycle of a photonic circuit, including theory, modelling, design, and experimentation.

Chrostowski, Lukas; Grist, Samantha; Flueckiger, Jonas; Shi, Wei; Wang, Xu; Ouellet, Eric; Yun, Han; Webb, Mitch; Nie, Ben; Liang, Zhen; Cheung, Karen C.; Schmidt, Shon A.; Ratner, Daniel M.; Jaeger, Nicolas A. F.

2012-02-01

314

Resonant Dark Matter  

SciTech Connect

It is usually assumed that dark matter direct detection is sensitive to a large fraction of the dark matter (DM) velocity distribution. We propose an alternative form of dark matter-nucleus scattering which only probes a narrow range of DM velocities due to the existence of a resonance, a DM-nucleus bound state, in the scattering - resonant dark matter (rDM). The scattering cross section becomes highly element dependent, has increased modulation and as a result can explain the DAMA/LIBRA results whilst not being in conflict with other direct detection experiments. We describe a simple model that realizes the dynamics of rDM, where the DM is the neutral component of a fermionic weak triplet whose charged partners differ in mass by approximately 10 MeV.

Bai, Yang; Fox, Patrick J.; /Fermilab

2009-09-01

315

Resonant dark matter  

NASA Astrophysics Data System (ADS)

It is usually assumed that dark matter direct detection is sensitive to a large fraction of the dark matter (DM) velocity distribution. We propose an alternative form of dark matter-nucleus scattering which only probes a narrow range of DM velocities due to the existence of a resonance, a DM-nucleus bound state, in the scattering - resonant dark matter (rDM). The scattering cross section becomes highly element dependent, has increased modulation and as a result can explain the DAMA/LIBRA results whilst not being in conflict with other direct detection experiments. We describe a simple model that realizes the dynamics of rDM, where the DM is the neutral component of a fermionic weak triplet whose charged partners differ in mass by approximately 10 MeV.

Bai, Yang; Fox, Patrick J.

2009-11-01

316

Photorefractivity in WGM resonators  

NASA Technical Reports Server (NTRS)

We report on observation of photorefractive effects in whispering gallery mode resonators made of as-grown and magnesium doped lithium niobate and lithium tantalate in the near as well as far infrared. The effects manifested themselves as dynamic modification of the spectra as well as quality factors of the resonators coupled to the laser radiation. We have observed a significant (exceeding 10-4) change of the ordinary index of refraction of all the materials exposed with 780 nm light. Photorefractive effects have also been detected at 1550 nm. Our experiments support the conclusion that the photorefractivity does not have a distinct red boundary. We show that the maximum saturated refractive index change in the infrared is of the same order of magnitude as in the visible light.

Matsko, Andrey; Savchenkov, Anatoliy; Strekalov, Dmitry; Ilchenko, Vladimir; Maleki, Lute

2006-01-01

317

Magnetic Resonance Fingerprinting  

PubMed Central

Summary Magnetic Resonance (MR) is an exceptionally powerful and versatile measurement technique. The basic structure of an MR experiment has remained nearly constant for almost 50 years. Here we introduce a novel paradigm, Magnetic Resonance Fingerprinting (MRF) that permits the non-invasive quantification of multiple important properties of a material or tissue simultaneously through a new approach to data acquisition, post-processing and visualization. MRF provides a new mechanism to quantitatively detect and analyze complex changes that can represent physical alterations of a substance or early indicators of disease. MRF can also be used to specifically identify the presence of a target material or tissue, which will increase the sensitivity, specificity, and speed of an MR study, and potentially lead to new diagnostic testing methodologies. When paired with an appropriate pattern recognition algorithm, MRF inherently suppresses measurement errors and thus can improve accuracy compared to previous approaches.

Ma, Dan; Gulani, Vikas; Seiberlich, Nicole; Liu, Kecheng; Sunshine, Jeffrey L.; Duerk, Jeffrey L.; Griswold, Mark A.

2013-01-01

318

All-resonant control of superconducting resonators.  

PubMed

An all-resonant method is proposed to control the quantum state of superconducting resonators. This approach uses a tunable artificial atom linearly coupled to resonators, and allows for efficient routes to Fock state synthesis, qudit logic operations, and synthesis of NOON states. This resonant approach is theoretically analyzed, and found to perform significantly better than existing proposals using the same technology. PMID:23215585

Strauch, Frederick W

2012-11-21

319

Resonance Rings  

NSDL National Science Digital Library

This is an activity about resonance and where it is found in related to astronomy. Learners will construct two differently sized rings out of file folder paper and tape them to a piece of cardboard. Next, they will shake the cardboard from side to side, which shakes the rings, and observe what happens when the frequency of the shaking is gradually increased. This activity is from the Stanford Solar Center's All About the Sun: Sun and Stars activity guide for Grades 5-8 and can also accompany the Stanford Solar Center's Build Your Own Spectroscope activity.

320

Comparison of particle-in-cell simulation with experiment for the transport system of the superconducting electron cyclotron resonance ion source VENUS  

SciTech Connect

The three-dimensional, particle-in-cell code WARP has been enhanced to allow end-to-end beam dynamics simulations of the VENUS beam transport system from the extraction region, through a mass-analyzing magnet, and up to a two-axis emittance scanner. This article presents the first results of comparisons between the simulation and experimental data. A helium beam (He{sup +} and He{sup 2+}) is chosen as an initial comparison beam due to its simple mass spectrum. Although a number of simplifications are made for the initial extracted beam, aberration characteristics appear in simulations that are also present in experimental phase-space current-density measurements. Further, measurements of phase-space tilt indicate that simulations must have little or no space-charge neutralization along the transport system to best agree with experiment. In addition, recent measurements of triangular beam structure immediately after the source are presented. This beam structure is related to the source magnetic confinement fields and will need to be taken into account as the initial beam approximations are lifted.

Todd, D.S.; Leitner, D.; Leitner, M.; Lyneis, C.M.; Qiang, J.; Grote, D.P. [LBNL, Berkeley, California 94720 (United States); LLNL, Livermore, California 94551 (United States)

2006-03-15

321

Charge-exchange neutral particle measurements on electron cyclotron resonance heating experiments in hot-ion-mode plasmas of the GAMMA 10 tandem mirror  

NASA Astrophysics Data System (ADS)

Charge-exchange (C-X) neutral particle measurements have been carried out in hot-ion-mode plasmas of the GAMMA 10 tandem mirror. In the present experiment, a microwave power of 40 kW in 28 GHz is injected toward a second harmonic ECR layer located in the vicinity of the ICR layer at the central region and the radial profiles of ion temperatures determined from the energy spectrum of the C-X neutrals by using a neutral particle energy analyzer (NPA) are investigated from the viewpoint of ion energy balance. At the onset of the ECRH pulse, a remarkable increase of C-X neutral flux with high energy (few keV to few tens keV) is observed with NPA and the resultant ion temperature on the plasma axis is found to increase from 2.5 to 5.0 keV at the electron line density of 3×1013 cm-2. Based on the measured plasma parameters, radial profiles of ion-energy losses due to classical processes are evaluated and ECRH in the central region is confirmed to reduce the energy loss due to electron drag significantly in the core-plasma region.

Nakashima, Y.; Hasegawa, Y.; Shoji, M.; Kobayashi, S.; Saito, T.; Kiwamoto, Y.; Cho, T.; Mase, A.; Ichimura, M.; Itakura, A.; Hirata, M.; Kohagura, J.; Islam, K. Md.; Oishi, M.; Yoshikawa, M.; Tamano, T.; Yatsu, K.

1999-01-01

322

Investigation of giant resonances via photon decay  

SciTech Connect

We describe some investigations into properties of giant resonances using elastic scattering of fast heavy-ion beams and the coincident detection of the gamma decay of the excited nucleus, using the TAPS array at GANIL. The particular experiments described are the identification of multiphoton giant resonance states and the measurement of projectile excitation, using the KVI forward wall detector.

Varner, R.L.; Beene, J.R.; Bertrand, F.E. [Oak Ridge National Lab., TN (United States)] [and others

1993-11-01

323

Nuclear Magnetic Resonance in Liquid Crystal Solvents  

Microsoft Academic Search

Since the discovery by Saupe and Englert that a nematic phase is a satisfactory solvent for high resolution nuclear magnetic resonance (NMR) studies, the variety of liquid crystal phases which have been found useful in NMR experiments has greatly increased. The resonance studies have increased our understanding of the structure of the solvent mesophases, and of their interactions with solute

Lawrence C. Snyder; Saul Meiboom

1969-01-01

324

Notes on Experiments.  

ERIC Educational Resources Information Center

Describes four physics experiments including "Investigation of Box Resonances Using a Micro"; "A Direct Reading Wattmeter, DC or AC"; "Exercises in the Application of Ohm's Law"; and "Hysteresis on Gas Discharges." Discusses procedures, instrumentation, and analysis in each example. (CW)

Physics Education, 1988

1988-01-01

325

Orbital electronegativities and the determination of s and d hybridization in various halides from nuclear quadrupole resonance frequencies  

Microsoft Academic Search

The use of Orbital Electronegativities in the interpretation of NQR results for various halides is discussed, and an attempt to determine the amount of d hybridization in s and p bonding is made. The ionic characters are assessed.

M. A. Whitehead; H. H. Jaffé

1963-01-01

326

Resonance and elastic nonlinear phenomena in rock  

NASA Astrophysics Data System (ADS)

In a great variety of laboratory experiments over large intervals in stress, strain, and frequency, rocks display pronounced nonlinear elastic behavior. Here we describe nonlinear response in rock from resonance experiments. Two important features of nonlinear resonant behavior are a shift in resonant frequency away from the linear resonant frequency as the amplitude of the disturbance is increased and the harmonics in the time signal that accompany this shift. We have conducted Young's mode resonance experiments using bars of a variety of rock types (limestone, sandstone, marble, chalk) and of varying diameters and lengths. Typically, samples with resonant frequencies of approximately 0.5-1.5 kHz display resonant frequency shifts of 10% or more, over strain intervals of 10-7 to 10-6 and under a variety of saturation conditions and ambient pressure conditions. Correspondingly rich harmonic spectra measured from the time signal progressively develop with increasing drive level. In our experiments to date, the resonant peak is observed to always shift downward (if indeed the peak shifts), indicating a net softening of the modulus with drive level. This observation is in agreement with our pulse mode and static test observations, and those of other researchers. Resonant peak shift is not always observed, even at large drive levels; however, harmonics are always observed even in the absence of peak shift when detected strain levels exceed 10-7 or so. This is an unexpected result. Important implications for the classical perturbation model approach to resonance results from this work. Observations imply that stress-strain hysteresis and discrete memory may play an important role in dynamic measurements and should be included in modeling. This work also illustrates that measurement of linear modulus and Q must be undertaken with great caution when using resonance.

Johnson, Paul A.; Zinszner, Bernard; Rasolofosaon, Patrick N. J.

1996-05-01

327

The Alfvén resonance in pair plasmas  

NASA Astrophysics Data System (ADS)

Waves propagating obliquely in a magnetized cold pair plasma experience an approximate resonance in the wavevector component perpendicular to the magnetic field, which is the analogue of the Alfvén resonance in normal electron-ion plasmas. Wave absorption at the resonance can take place via mode conversion to the analogue of the short wavelength inertial Alfvén wave. The Alfvén resonance could play a role in wave propagation in the pulsar magnetosphere leading to pulsar radio emission. Ducting of waves in strong plasma gradients may occur in the pulsar magnetosphere, which leads to the consideration of Alfvén surface waves, whose energy is concentrated in the region of strong gradients.

Cramer, N. F.

2014-05-01

328

Precision Electroweak Measurements on the Z Resonance  

Microsoft Academic Search

We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLD experiment using a polarised beam at SLC.

S. Schael; R Barate; R Brunelière; Damir Buskulic; I De Bonis; D Décamp; P Ghez; C Goy; S Jézéquel; J P Lees; A Lucotte; F Martin; E Merle; M N Minard; J Y Nief; P Odier; B Pietrzyk; B Trocmé; S Bravo; M P Casado; M Chmeissani; P Comas; J M Crespo; E Fernández; M Fernández-Bosman; L Garrido; E Graugès-Pous; A Juste; M Martínez; G Merino; R Miquel; L M Mir; S Orteu; A Pacheco; I C Park; J Perlas; I Riu; H Ruiz; F Sánchez; A Colaleo; D Creanza; N De Filippis; M De Palma; G Iaselli; G Maggi; M Maggi; S Nuzzo; A Ranieri; G Raso; F Ruggieri; G Selvaggi; L Silvestris; P Tempesta; A Tricomi; G Zito; X Huang; J Lin; Q Ouyang; T Wang; Y Xie; R Xu; S Xue; J Zhang; L Zhang; W Zhao; D Abbaneo; A Bazarko; U Becker; G Boix; F Bird; E Blucher; B Bonvicini; P Bright-Thomas; T Barklow; M Cattaneo; F Cerutti; B Clerbaux; H Drevermann; R W Forty; M Frank; T C Greening; R Hagelberg; A W Halley; F Gianotti; M Girone; J B Hansen; J Harvey; R Jacobsen; D E Hutchcroft; P Janot; B Jost; J Knobloch; M Kado; Ivan Lehraus; Pierre Lazeyras; P Maley; P Mato; J May; A Moutoussi; M Pepé-Altarelli; F Ranjard; Luigi Rolandi; W D Schlatter; B Schmitt; O Schneider; W Tejessy; F Teubert; I R Tomalin; E Tournefier; R Veenhof; A Valassi; W Wiedenmann; A E Wright; Ziad J Ajaltouni; F Badaud; G Chazelle; O Deschamps; S Dessagne; A Falvard; C Ferdi; D Fayolle; P Gay; C Guicheney; P Henrard; J Jousset; B Michel; S Monteil; J C Montret; D Pallin; J M Pascolo; P Perret; F Podlyski; H Bertelsen; T Fernley; J D Hansen; P H Hansen; A C Kraan; A Lindahl; R Møllerud; B S Nilsson; B Rensch; A Wäänänen; G Daskalakis; A Kyriakis; C Markou; E Simopoulou; I Siotis; A Vayaki; A Blondel; G Bonneaud; J C Brient; F Machefert; A Rougé; M Rumpf; M Swynghedauw; R Tanaka; M Verderi; H L Videau; V Ciulli; E Focardi; G Parrini; K Zachariadou; M Corden; C H Georgiopoulos; A Antonelli; M Antonelli; G Bencivenni; G Bologna; F Bossi; P Campana; G Capon; V Chiarella; G Felici; P Laurelli; G Mannocchi; G P Murtas; L Passalacqua; P Picchi; P Colrain; I ten Have; I S Hughes; J Kennedy; I G Knowles; J G Lynch; W T Morton; P Negus; V O'Shea; C Raine; P Reeves; J M Scarr; K Smith; A S Thompson; R M Turnbull; S R Wasserbaech; O L Buchmüller; R J Cavanaugh; S Dhamotharan; C Geweniger; P Hanke; G Hansper; V Hepp; E E Kluge; A Putzer; J Sommer; K Tittel; W Werner; M Wunsch; R Beuselinck; D M Binnie; W Cameron; G Davies; P J Dornan; S M Goodsir; N Marinelli; E Martin; J Nash; J Nowell; S A Rutherford; J K Sedgbeer; J C Thompson; R White; M D Williams; V M Ghete; P Girtler; E Kneringer; D Kuhn; G Rudolph; E Bouhova-Thacker; C K Bowdery; P G Buck; D P Clarke; G Ellis; A J Finch; F Foster; G Hughes; R W L Jones; N R Keemer; M R Pearson; N A Robertson; T Sloan; M Smizanska; S W Snow; M I Williams; O van der Aa; C Delaere; G Leibenguth; V Lemaître; L A T Bauerdick; U Blumenschein; P Van Gemmeren; I Giehl; F Hölldorfer; K Jakobs; M Kasemann; F Kayser; K Kleinknecht; A S Müller; G Quast; B Renk; E Rohne; H G Sander; S Schmeling; H W Wachsmuth; R Wanke; C Zeitnitz; T Ziegler; Jean-Jacques Aubert; C Benchouk; A Bonissent; J Carr; P Coyle; C Curtil; A Ealet; F Etienne; D Fouchez; F Motsch; P Payre; D Rousseau; M Talby; M Thulasidas; M Aleppo; F Ragusa; V Büscher; A David; H Dietl; G Ganis; K Hüttmann; G Lütjens; C Mannert; W Männer; H G Moser; R Settles; H Seywerd; H Stenzel; M Villegas; G Wolf; J Boucrot; O Callot; S Chen; A Cordier; M Davier; L Duflot; J F Grivaz; P Heusse; A Jacholkowska; F R Le Diberder; J Lefrançois; A M Mutz; M H Schune; L Serin; J J Veillet; I Videau; D Zerwas; P Azzurri; G Bagliesi; S Bettarini; T Boccali; C Bozzi; G Calderini; R Dell'Orso; R Fantechi; I Ferrante; F Fidecaro; L Foà; A Giammanco; A Giassi; A Gregorio; F Ligabue; A Lusiani; P S Marrocchesi; A Messineo; F Palla; G Rizzo; G Sanguinetti; A Sciabà; G Sguazzoni; P Spagnolo; J Steinberger; R Tenchini; C Vannini; A Venturi; P G Verdini; O Awunor; G A Blair; G Cowan; A García-Bellido; M G Green; T Medcalf; J A Strong; P Teixeira-Dias; David R Botterill; R W Clifft; T R Edgecock; M Edwards; S J Haywood; P R Norton; J J Ward; B Bloch-Devaux; D E Boumediene; P Colas; S Emery; B Fabbro; Witold Kozanecki; E Lançon; M C Lemaire; E Locci; P Pérez; J Rander; J F Renardy; A Roussarie; J P Schuller; J Schwindling; B Tuchming; B Vallage; S N Black; J H Dann; H Y Kim; N P Konstantinidis; A M Litke; M A McNeil; G Taylor; C N Booth; S Cartwright; F Combley; P N Hodgson; M H Lehto; L F Thompson; K Affholderbach; E Barberio; A Böhrer; S Brandt; H Burkhardt; E Feigl; C Grupen; J Hess; G Lutters; H Meinhard; J A Minguet-Rodríguez; L Mirabito; A Misiejuk; E Neugebauer; A Ngac; G Prange; F Rivera; P Saraiva; U Schäfer; U Sieler; L Smolik; F Stephan; H Trier; M Apollonio; C Borean; L Bosisio; R Della Marina; G Giannini; B Gobbo; G Musolino; L Pitis; H He; J Pütz; J E Rothberg; S R Armstrong; L Bellantoni; K Berkelman; D Cinabro; J S Conway; K Cranmer

2006-01-01

329

Resonant microwave cavity for 8.5-12 GHz optically detected electron spin resonance with simultaneous nuclear magnetic resonance  

NASA Astrophysics Data System (ADS)

We present a newly developed microwave resonant cavity for use in optically detected magnetic resonance (ODMR) experiments. The cylindrical quasi-TE011 mode cavity is designed to fit in a 1 in. magnet bore to allow the sample to be optically accessed and to have an adjustable resonant frequency between 8.5 and 12 GHz. The cavity uses cylinders of high dielectric material, so-called ``dielectric resonators,'' in a double-stacked configuration to determine the resonant frequency. Wires in a pseudo-Helmholtz configuration are incorporated into the cavity to provide frequencies for simultaneous nuclear magnetic resonance (NMR). The system was tested by measuring cavity absorption as microwave frequencies were swept, by performing ODMR on a zinc-doped InP sample, and by performing optically detected NMR on a GaAs sample. The results confirm the suitability of the cavity for ODMR with simultaneous NMR.

Colton, J. S.; Wienkes, L. R.

2009-03-01

330

Coherent Nuclear Resonance Fluorescence  

NASA Astrophysics Data System (ADS)

For a long time, the impact of ideas with respect to coherency and scattering on the art and science of Mössbauer spectroscopy was not very essential. The main line of development of Mössbauer experiments rested in the frame of absorption spectroscopy. Mössbauer physicists dealt mostly with absorption spectra taken either in traditional transmission experiments or in measurements of the conversion electron yield. For the interpretation and description of these spectra, it was appropriate to use the picture of interaction of ?-quantum with an individual nucleus where the nuclear resonant absorption cross-section was applied. The coherent properties of radiation and those of the interaction mechanism were not explicitly involved in these studies. In the meantime, coherent phenomena with Mössbauer ?-rays were thoroughly investigated, starting soon after Mössbauer's discovery. The present paper is aimed to illuminate this side of the Mössbauer story.

Smirnov, G. V.

331

Coexistence of Antiferromagnetism with Superconductivity in CePt2In7: Microscopic Phase Diagram Determined by In115 NMR and NQR  

NASA Astrophysics Data System (ADS)

Single crystals of the heavy-fermion antiferromagnet CePt2In7 with a Néel temperature (TN) of 5.2 K at ambient pressure have been investigated by zero-field In115-nuclear magnetic and quadrupole resonance measurements as a function of applied pressure. Within the antiferromagnetic state, the character of Ce's 4f electron appears to change from localized to itinerantlike at P*˜2.4 GPa, approximately the pressure where superconductivity first emerges. With increased pressure, the superconducting transition Tc reaches a maximum just at or slightly before antiferromagnetic order disappears, and not at the pressure Pc˜3.4 GPa, where the steeply decreasing Néel boundary extrapolates to zero temperature. For P >Pc, the spin relaxation rate drops sharply by more than 2 orders of magnitude at Tc, suggestive of a first-order transition.

Sakai, H.; Tokunaga, Y.; Kambe, S.; Ronning, F.; Bauer, E. D.; Thompson, J. D.

2014-05-01

332

Low-temperature nuclear quadrupole resonance studies of antimony and application to thermometry  

NASA Astrophysics Data System (ADS)

The spin-lattice retaxation time, Tsb1, of finely divided powdered metallic antinomy immersed in liquid sp3He was measured using pulsed Nuclear Quadrupole Resonance (NQR) techniques. In this technique, the nuclear quadrupole resonant antinomy nuclei were saturated using an RF pulse. The recovery back to equilibrium was monitored using short inspection pulses and the magnetization recovery follows a recovery curve characterized by the relaxation time Tsb1. Tsb1 measurements were performed at temperatures ranging from 150 mK to 1.25 mK. Temperatures down to 11 mK were achieved by using a dilution refrigerator. Lower temperatures were achieved using adiabatic nuclear demagnetization of a copper bundle starting at 8.5 Tesla (7.5 Tesla average field over the copper bundle). The sample was cooled by immersion in liquid sp3He which is in thermal contact with silver sinter packed in the bottom of a silver cell. This cell was bolted onto a cold plate attached to the copper bundle. It was found that a low temperatures starting near 75 mK, the measured total relaxation was significantly enhanced with respect to the Korringa relaxation, the dominant relaxation mechanism expected for a metal at these temperatures. This enhancement is attributed to a surface relaxation mechanism mediated by the surface sp3He atoms. In systems immersed in liquid sp3He, a surface relaxation mechanism is present due to a modulation of the interaction between the solid-like sp3He atoms on the surface and the surface spins. This modulation is due to the quantum zero-point motion of the sp3He atoms on the surface. This phenomenon has been well studied in insulating systems using Nuclear Magnetic Resonance. The measurements undertaken in this study demonstrate that this phenomenon is present in a metallic and quadrupolar system. This surface relaxation mechanism becomes the dominant relaxation mechanism at low temperatures. Considering the surface and bulk spins as belonging to different phases, a two phase relaxation analysis was used to extract the surface relaxation parameters. This work helps explain previous relaxation measurements by other groups, on powdered metals (with spin I? 0) immersed in liquid sp3He. In these studies, anomalies were reported whose features are consisted with the surface relaxation mechanism discussed in this work. Using magnetic field perturbed NQR, the intensity ratio of two transitions was studied from 1.4 mK to 0.25 mK. The intensity ratio was observed to change as a function of temperature. A comparison is made with the expected Boltzmann distribution. This intensity ratio can be used as a self-calibrating, absolute thermometer for the ultra-low temperature region.

Genio, Edgar Baylon

1997-11-01

333

?-meson photoproduction and N* resonances  

NASA Astrophysics Data System (ADS)

We investigate the ? photoproduction using the effective Lagrangian approach at the tree level. We include eight nucleon resonances, that is, D13(1520), S11(1535), S11(1650), D15(1675), F15(1680), D13(1700), P11(1710), P13(1720) as well as possible background contributions. In addition, we introduce the new nucleon resonance N*(1675) which was announced by the GRAAL, CB-ELSA and Tohoku LNS-GeV-? experiments. We investigate a possible role of the resonance with testing its spin and parity for four different cases of JP = 1/2± and 3/2±. We calculate various cross sections including beam asymmetries for neutron and proton targets. We find noticeable isospin asymmetry in transition amplitudes for proton and neutron targets.

Choi, K. S.; Nam, S. I.; Hosaka, A.; Kim, H. Ch

2009-01-01

334

Effective resonance levels  

Microsoft Academic Search

A method based on the use of effective resonance integrals or group cross sections with resonance self-shielding factors has come into extensive use in calculations of resonance absorption in homogeneous systems. An attempt is made to extend the subgroup treatment, which was initially formulated for the region of forbidden resonances, to the allowed region as applicable to heterogeneous media. A

B. P. Kochurov

1986-01-01

335

Potential of Delayed Gadolinium Enhancement Magnetic Resonance for Quantification of Reverse Remodeling of the Peri-Infarct Zone in Patients with Ischemic Cardiomyopathy Treated with Chronic Vasodilator Therapy: Initial Experience  

PubMed Central

Purpose The peri-infarct zone represents the morphological substrate for re-entry ventricular tachycardia after myocardial infarction (MI) and its extent is a strong predictor of major cardiac events. Although delayed gadolinium enhancement magnetic resonance (DGE-MRI) was shown to allow for detailed characterization of MI by quantifying infarct core zone and peri-infarct zone volume, potentials of DGE-MRI for measuring changes in peri-infarct zone volume are unknown. Therefore, we aimed to assess changes in volume of the peri-infarct zone among patients with ischemic cardiomyopathy treated with chronic vasodilator therapy. Materials and Methods Core and peri-infarct zone volumes as assessed with DGE-MRI were measured in 5 patients at baseline and following 6 months treatment with sustained-release dipyridamole. Results Core zone volume remained stable during follow-up [median(range): 19ml(9–42) vs. 16ml(11–46); p=0.785]. The ratio between the peri-infarct zone and the core zone volume decreased significantly at 6 month as compared to baseline [median(range): 0.22(0.19–0.42) vs. 0.18(0.09–0.32); p=0.043], and a trend towards reduction in peri-infarct zone volume was found [median(range): 5ml(2–8) vs. 3ml(2–6); p=0.059]. The peri-infarct zone volume decreased in all but 1 patient over the follow-up. Conclusions This initial experience suggests that reverse remodeling of the peri-infarct zone with reduction in peri-infarct zone volume may take place in patients with ischemic cardiomyopathy. Quantification of this process may be feasible with DGE-MRI, but further studies are needed to confirm this hypothesis and to further clarify the role of DGE-MRI for the assessment of changes in peri-infarct zone volume in patients with ischemic cardiomyopathy.

Muzzarelli, Stefano; Ordovas, Karen Gomes; Cannavale, Giuseppe; Naeger, David; Michaels, Andrew D.; Higgins, Charles B.

2011-01-01

336

Electroweak-scale resonant leptogenesis  

NASA Astrophysics Data System (ADS)

We study minimal scenarios of resonant leptogenesis near the electroweak phase transition. These models offer a number of testable phenomenological signatures for low-energy experiments and future high-energy colliders. Our study extends previous analyses of the relevant network of Boltzmann equations, consistently taking into account effects from out of equilibrium sphalerons and single lepton flavors. We show that the effects from single lepton flavors become very important in variants of resonant leptogenesis, where the observed baryon asymmetry in the Universe is created by lepton-to-baryon conversion of an individual lepton number, for example, that of the ?-lepton. The predictions of such resonant ?-leptogenesis models for the final baryon asymmetry are almost independent of the initial lepton-number and heavy neutrino abundances. These models accommodate the current neutrino data and have a number of testable phenomenological implications. They contain electroweak-scale heavy Majorana neutrinos with appreciable couplings to electrons and muons, which can be probed at future e+e- and ?+?- high-energy colliders. In particular, resonant ?-leptogenesis models predict sizable 0??? decay, as well as e- and ?-number-violating processes, such as ??e? and ??e conversion in nuclei, with rates that are within reach of the experiments proposed by the MEG and MECO collaborations.

Pilaftsis, Apostolos; Underwood, Thomas E. J.

2005-12-01

337

Indirect (J) coupling of inequivalent ^75As nuclei in crystalline and glassy As_2Se3 and As_2S_3  

NASA Astrophysics Data System (ADS)

Indirect nuclear spin-spin couplings, or J couplings, were first observed in liquids using nuclear magnetic resonance (NMR) techniques [1]. Because of the nature of the quadrupole Hamiltonian in pure nuclear quadrupole resonance (NQR) experiments J couplings should be observable between inequivalent nuclei [2]. We present results of ^75As NQR measurements in crystalline and glassy As_2S3 and As_2Se_3. These ^75As NQR measurements were performed at various frequencies between about 55 and 75 MHz. The NQR frequency is determined by the electric field gradient (EFG) at the nucleus, and in these materials there are two non-equivalent sites in each of the two crystals. The J coupling can occur through several chemical bonds, and in our case this coupling must go through two As-S covalent bonds since the nearest neighbor As sites are separated by chalcogen atoms. Instead of the monotonic decay expected from relaxation spin-spin theory, the decays of the NQR Hahn echoes following a 90^0-180^0pulse sequence exhibit damped oscillations superimposed on an exponential decay. These damped oscillations can be explained by an indirect coupling (J coupling). Experimental values of the J couplings were obtained from the periods of the oscillations and calculations of the most probable transitions using 2^nd order perturbation theory. The value estimated by this method for the ^2J(^75As-S-^75As) in crystalline As_2S3 compares well with empirical estimates, which are obtained using an existing value of ^2J(^31P-S-^31P) and known scalings with atomic number from the literature. 1. E. L. Hahn and D. E Maxwell, Phys. Rev. 84, 1246 (1951). 2. T. P. Das and E. L. Hahn, Solid State Physics, supp 1, Nuclear Quadrupole Resonance Spectroscopy, p. 28, Academic Press 1958.

Whitaker, J.; Ahn, E.; Hart, P.; Williams, G. A.; Taylor, P. C.; Facelli, J. C.

2004-03-01

338

Notes on Experiments.  

ERIC Educational Resources Information Center

Describes: (1) two experiments using a laser (resonant cavity for light and pinhole camera effect with a hologram); (2) optical differaction patterns displayed by microcomputer; and (3) automating the Hall effect (with comments on apparatus needed and computer program used); and (4) an elegant experiment in mechanical equilibrium. (JN)

Physics Education, 1985

1985-01-01

339

Resonant angular conversion in a Fabry-Perot resonator holding a dielectric cylinder.  

PubMed

Light transmission through a Fabry-Perot resonator (FPR) holding a dielectric cylinder rod is considered. For the cylinder parallel to mirrors of the FPR and the mirrors mimicked by the ? functions we present an exact analytical theory. It is shown that light transmits only for resonant incident angles, ?(m), similar to the empty FPR. However after transmission the light scatters into different resonant angles, ?(m'), performing resonant angular conversion. We compare the theory with experiment in the FPR, exploring multilayer films as the mirrors and glass cylinder with diameter coincided with the distance between the FPR mirrors. The measured values of angular light conversion agree qualitatively with the theoretical results. PMID:24562024

Bulgakov, E N; Sadreev, A F; Gerasimov, V P; Zyryanov, V Y

2014-02-01

340

Molecular structure and motion in zero field magnetic resonance  

SciTech Connect

Zero field magnetic resonance is well suited for the determination of molecular structure and the study of motion in disordered materials. Experiments performed in zero applied magnetic field avoid the anisotropic broadening in high field nuclear magnetic resonance (NMR) experiments. As a result, molecular structure and subtle effects of motion are more readily observed.

Jarvie, T.P.

1989-10-01

341

N Resonances in Neutrino Interactions  

NASA Astrophysics Data System (ADS)

The role of N* resonances in neutrino interactions with nucleons is discussed, stressing the relevance for neutrino cross-section and oscillation experiments. The cross section for single N* weak excitation is expressed in terms of vector and axial transition form factors, which can be partially constrained using the available experimental information from photon, electron and pion reactions on the nucleon. New measurements on hydrogen and deuterium are necessary to reduce further the uncertainties.

Alvarez-Ruso, L.

2014-01-01

342

Basics of magnetic resonance imaging  

SciTech Connect

Beginning with the behavior of a compass needle in a magnetic field, this text uses analogies from everyday experience to explain the phenomenon of nuclear magnetic resonance and how it is used for imaging. Using a minimum of scientific abbreviations and symbols, the basics of tissue visualization and characterization are presented. A description of the various types of magnets and scanners is followed by the practical advantages and limitations of MRI relative to x-ray CT scanning.

Oldendorf, W.; Oldendorf, W. Jr.

1988-01-01

343

Contact replacement for NMR resonance assignment  

Microsoft Academic Search

Motivation: Complementing its traditional role in structural studies of proteins, nuclear magnetic resonance (NMR) spectroscopy is playing an increasingly important role in functional studies. NMR dynamics experiments characterize motions involved in target recognition, ligand binding, etc., while NMR chemical shift perturbation experiments identify and localize protein-protein and protein-ligand interactions. The key bottleneck in these studies is to determine the backbone

Fei Xiong; Gopal Pandurangan; Chris Bailey-kellogg

2008-01-01

344

Contact Replacement for NMR Resonance Assignment  

Microsoft Academic Search

Motivation: Complementing its traditional role in structural studies of proteins, nuclear magnetic resonance (NMR) spectroscopy is playing an increasingly important role in functional studies. NMR dynamics experiments characterize motions involved in target reco- gnition, ligand binding, etc., while NMR chemical shift perturbation experiments identify and localize protein-protein and protein-ligand interactions. The key bottleneck in these studies is to determine the

Fei Xiong; Gopal Pandurangan; Chris Bailey-Kellogg

345

SGEMP for Resonant Structures.  

National Technical Information Service (NTIS)

Most satellites in existence to date are inherently resonant structures. By a resonant structure is meant that the currents and charges induced on it by an external transient electromagnetic source continue to oscillate without significant damping long af...

K. S. H. Lee L. Marin

1975-01-01

346

Neutron resonance averaging  

SciTech Connect

The principles of resonance averaging as applied to neutron capture reactions are described. Several illustrations of resonance averaging to problems of nuclear structure and the distribution of radiative strength in nuclei are provided. 30 refs., 12 figs.

Chrien, R.E.

1986-10-01

347

Resonance in Piezoelectric Vibrators.  

National Technical Information Service (NTIS)

The electrical behavior of a piezoelectric vibrator leads to criteria by which to describe onset and extent of the resonance region. The equi-immittance point is convenient for delimiting the resonance range and assesses the validity of circle representat...

A. Ballato

1969-01-01

348

Double stochastic resonance over an asymmetric barrier  

NASA Astrophysics Data System (ADS)

In a recent experiment [Müller , Phys. Rev. A 79, 031804(R) (2009)] reported a splitting of the stochastic resonance peak, which they attributed to the asymmetry of an effective double-well restoring potential in their optomechanical read-out device. We show here that such an effect, though smaller than reported, is indeed consistent with a characterization of stochastic resonance as a synchronization phenomenon, while it proves elusive in terms of spectral quantifiers.

Borromeo, M.; Marchesoni, F.

2010-01-01

349

Unstable optical resonators with tilted spherical mirrors  

Microsoft Academic Search

A means of achieving asymmetric magnification in collimated-output unstable resonators is proposed which obviates difficulties associated with nonspherical mirrors. By suitable choice of rather large tilt angles of spherical mirrors and mirror separation, simultaneous 'confocality' can be achieved in x-z and y-z planes to the lowest order. Simple resonator design equations are given. Experiments have confirmed the design equations by

C. Cason; R. W. Jones; J. F. Perkins

1978-01-01

350

Double-resonance magic angle coil spinning  

NASA Astrophysics Data System (ADS)

We present an extension of magic angle coil spinning (MACS) solid-state NMR spectroscopy to double-resonance experiments, enabling implementation of powerful double-resonance solid-state NMR methodologies including cross polarization, proton decoupling, and two-dimensional correlation spectroscopy etc., while still enjoying the merits that are intrinsic to MACS, such as high concentration sensitivity, eliminated magnetic susceptibility-induced field distortion, and an easy-to-use approach with the conventional and widespread hardware.

Inukai, Munehiro; Takeda, Kazuyuki

2010-02-01

351

Alpha resonant scattering for astrophysical reaction studies  

NASA Astrophysics Data System (ADS)

Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. One of the methods to study them is the ? resonant scattering using the thick-target method in inverse kinematics. Among the recent studies at CRIB, the measurement of 7Be+? resonant scattering is discussed. Based on the result of the experiment, we evaluated the contributions of high-lying resonances for the 7Be(?,?) reaction, and proposed a new cluster band in 11C.

Yamaguchi, H.; Kahl, D.; Nakao, T.; Wakabayashi, Y.; Kubano, S.; Hashimoto, T.; Hayakawa, S.; Kawabata, T.; Iwasa, N.; Teranishi, T.; Kwon, Y. K.; Binh, D. N.; Khiem, L. H.; Duy, N. G.

2014-05-01

352

Stability Limits in Resonant Planetary Systems  

NASA Astrophysics Data System (ADS)

The relationship between the boundaries for Hill and Lagrange stability in orbital element space is modified in the case of resonantly interacting planets. Hill stability requires the ordering of the planets to remain constant while Lagrange stability also requires all planets to remain bound to the central star. The Hill stability boundary is defined analytically, but no equations exist to define the Lagrange boundary, so numerical experiments are needed. To explore the effect of resonances, we consider orbital element space near the conditions in the HD 82943 and 55 Cnc systems. For each of those systems, we use simulations of the dynamical evolution of 1000 cases over 106 years, with initial conditions distributed over the range of observational uncertainty, to identify the Lagrange-stability boundary. The observational errors are large enough that non-resonant configurations are included in our sets of integrated cases. Previous studies have shown that, for non-resonant systems, the two stability boundaries are nearly coincident. Hill stability formulae are not applicable to resonant systems, so our investigation shows how the two boundaries diverge in the presence of a mean-motion resonance, while confirming that the Hill and Lagrange boundaries are similar otherwise. In resonance the region of stability is larger than the domain defined by the analytic formulae for Hill stability. Moreover, the expansion is greater in the 2:1 resonance (HD 82943) than for the 3:1 case (55 Cnc).

Barnes, Rory; Greenberg, R.

2007-07-01

353

Pediatric magnetic resonance imaging  

SciTech Connect

This book defines the current clinical potential of magnetic resonance imaging and focuses on direct clinical work with pediatric patients. A section dealing with the physics of magnetic resonance imaging provides an introduction to enable clinicians to utilize the machine and interpret the images. Magnetic resonance imaging is presented as an appropriate imaging modality for pediatric patients utilizing no radiation.

Cohen, M.D.

1986-01-01

354

General resonance spectroscopy  

Microsoft Academic Search

We introduce a generalized definition of resonance which is applicable to systems without well-defined energies and derive an approximate expression for the shape of the resonance curves. We also provide an algorithm for modelling the dynamics of an experimental system using this generalized resonance function.

K. Chang; A. Kodogeorgiou; A. Hübler; E. A. Jackson

1991-01-01

355

Observation of a Second-Order Spin-Depolarizing Resonance  

SciTech Connect

A recent experiment using a 160 MeV stored spin-polarized proton beam found clear evidence for a second-order intrinsic depolarizing resonance. With a 20% partial Siberian snake, we studied a first-order intrinsic depolarizing resonance; we then discovered and studied the second-order depolarizing resonance by changing both the horizontal and vertical betatron tunes. As expected, this second-order resonance is much weaker than the first-order resonance; it is probably due to sextupole fields plus coupling between the horizontal and vertical betatron oscillations caused by the 20% snake.

Ohmori, C.; Sato, H. [KEK, National Laboratory for High Energy Physics, Tsukuba, Ibaraki 305 (Japan)] [KEK, National Laboratory for High Energy Physics, Tsukuba, Ibaraki 305 (Japan); Alexeeva, L.V.; Anferov, V.A.; Caussyn, D.D.; Chu, C.M.; Crandell, D.A.; Gladycheva, S.E.; Hu, S.; Krisch, A.D.; Phelps, R.A.; Varzar, S.M.; Wong, V.K. [Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120 (United States)] [Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120 (United States); Lee, S.Y.; Rinckel, T.; Schwandt, P.; Sperisen, F.; Stephenson, E.J.; von Przewoski, B. [Indiana University Cyclotron Facility, Bloomington, Indiana 47408-0768 (United States)] [Indiana University Cyclotron Facility, Bloomington, Indiana 47408-0768 (United States); Baiod, R.; Russell, A.D. [Fermilab, Batavia, Illinois 60510 (United States)] [Fermilab, Batavia, Illinois 60510 (United States)

1995-09-04

356

Nuclear quadrupole resonance. Electronic structure and sterochemistry of halogenonaphthalenones  

SciTech Connect

The /sup 35/Cl NQR spectra of 2-chloro-, 2, 3-dihydro-2-bromo-2,3-dichloro-, and 2,2,3-trichloro-4-diphenyl-methylene-1(4H)-napthalenones (I-III) were studied. The experimental data are compared with the results from quantum-chemical calculations for the conformers of the molecules of (I-III) by the CNDO/2 method. The adequacy of the conformation description of systems (I-III) by the method using the /sup 35/Cl NQR frequencies was established by study of 1,2-dichloroacenaphthene and 2-chlorotetrahydropyran. It was established that compound (II) in the crystal exists in the form of the conformer with the bromine atom in the axial position. The possibilities of using an electrostatic model for the discussion of the conformations of the 2,3-dyhydro derivatives (II) and (III) with separate allowance for the geminal and vicinal environments of the chlorine probe atom are examined.

Romanenko, E.A.; Nesterenko, A.M.; Novikov, V.P.; Kolesnikov, V.T.

1987-11-01

357

Tailored Asymmetry for Enhanced Coupling to WGM Resonators  

NASA Technical Reports Server (NTRS)

Coupling of light into and out of whispering- gallery-mode (WGM) optical resonators can be enhanced by designing and fabricating the resonators to have certain non-axisymmetric shapes (see figure). Such WGM resonators also exhibit the same ultrahigh values of the resonance quality factor (Q) as do prior WGM resonators. These WGM resonators are potentially useful as tunable narrow-band optical filters having throughput levels near unity, high-speed optical switches, and low-threshold laser resonators. These WGM resonators could also be used in experiments to investigate coupling between high-Q and chaotic modes within the resonators. For a WGM resonator made of an optically nonlinear material (e.g., lithium niobate) or another material having a high index of refraction, a prism made of a material having a higher index of refraction (e.g., diamond) must be used as part of the coupling optics. For coupling of a beam of light into (or out of) the high-Q resonator modes, the beam must be made to approach (or recede from) the resonator at a critical angle determined by the indices of refraction of the resonator and prism materials. In the case of a lithium niobate/diamond interface, this angle is approximately 22 .

Mohageg, Makan; Maleki, Lute

2008-01-01

358

Gallium nitride nanowire electromechanical resonators  

NASA Astrophysics Data System (ADS)

Nanoscale mechanical resonators are of great interest for high-resolution sensing applications, where the small resonator mass and high quality factor (Q, defined as resonance frequency f0 over full width at half maximum power) lead to unprecedented sensitivity. Here, we investigate gallium nitride (GaN) nanowire (NW) resonators. The single-crystal, c-axis NWs are 5 mum -- 20 mum long, with diameters from 50 nm -- 500 nm, and grow essentially free of defects. Our initial experiments involve measuring the resonances of as-grown NWs in a scanning electron microscope, where we observe exceptionally high Q values of 10 4 -- 105, one to two orders of magnitude higher than most NWs of comparable size. Using a single NW as a mass sensor, we then demonstrate a sub-attogram mass sensitivity. To provide a more flexible measurement technique that avoids electron-microscope detection, we fabricate doubly clamped NWs with an entirely electronic drive and readout scheme using a combination of lithographic patterning and dielectrophoresis. An electrostatic gate induces vibration, while readout utilizes the piezoresistivity of GaN. Observed resonances range from 9--36 MHz with Q values typically around 103 at room temperature and 10 -4 Pa. We use the behavior of f0 and Q to sense the NW's local environment, such as the additional sources of energy dissipation not present in the as-grown NWs. By cooling the device to 8 K, Q increases by an order of magnitude to above 104, with a highest value to date of 26,000 under vacuum. We explore additional NW properties through the thermal noise in the NW's mechanical motion and the exponential decay of mechanical motion in the presence of burst drive. Finally, we investigate the low-frequency 1/f parameter noise displayed by f0. We show that the noise in f0 is consistent with noise in the NW's resistance leading to temperature noise from local Joule heating, which in turn generates resonance frequency noise. For sensor applications, there will be optimal drive conditions that balance the f 0 noise with the signal-to-noise ratio of the system. With these insights, along with the simple drive and readout technique, these GaN-NW doubly clamped resonators have significant potential for high-resolution sensing applications.

Gray, Jason Michael

359

Triply resonant sum frequency spectroscopy: combining advantages of resonance Raman and 2D-IR.  

PubMed

This article describes the new multidimensional spectroscopy technique triply resonant sum frequency spectroscopy, a four-wave mixing technique sharing advantages of both 2D-IR and resonance Raman experiments. In this technique, lasers with three independent frequencies interact coherently within a sample and generate an output frequency at their triple summation. The output intensity depends on coupled electronic and vibrational resonances in the sample. We use an organic dye as a model system to demonstrate fully resonant, fully coherent multidimensional spectroscopy using two independently tunable mid-infrared vibrational interactions and one visible electronic interaction. When the pulses are time ordered, the method has a single coherence pathway, eliminating interference between pathways. Fundamental vibrational transitions appear on one axis and overtones and combinations bands on the other, allowing anharmonicities of the modes to be determined easily and conveying molecular coupling information. The experiments demonstrate coupling between seven vibrational ring modes and an electronic state, the resolution of a Fermi resonance, detection of low concentrations, elimination of excitation pulse scattering and fluorescence, background suppression of solvent and co-solutes, and observation of coherence dephasing dynamics. The electronic resonance enhancements used in this methodology are similar to the enhancements responsible for resonance Raman spectroscopy and can be considered resonance 2D-IR spectroscopy. PMID:24160771

Boyle, Erin S; Neff-Mallon, Nathan A; Wright, John C

2013-11-27

360

Calcium cyclotron resonance and diatom mobility.  

PubMed

The hypothesis that movement of biological ions may be predicted by cyclotron resonance theory applied to cell membranes is tested in these experiments. Diatoms (Amphora coffeaeformis) were chosen as the biosystem since they move or don't move, depending on how much calcium is transported across the membrane. The experiments demonstrate that a particular ion (calcium) is apparently moved across the cell membrane in response to the DC and AC values of magnetic flux densities (B) and the frequency derived from the cyclotron resonance theory. A clear resonance is shown and a rather sharp frequency response curve is demonstrated. The experiments also show a dose response as the AC value of the flux density is varied, and that odd harmonics of the basic cyclotron frequency are also effective. PMID:3663247

Smith, S D; McLeod, B R; Liboff, A R; Cooksey, K

1987-01-01

361

Resonance condition of a microfiber knot resonator immersed in liquids.  

PubMed

Effects of immersing a microfiber knot resonator (MKR) in liquid solutions that have refractive indices close to that of silica are experimentally demonstrated and theoretically analyzed. Significant improvement in resonance extinction ratio within 2 to 10 dB was observed. To achieve a better understanding, a qualitative analysis of the coupling ratio and round-trip attenuation of the MKR is performed by using a curve-fitting method. It was observed that the coupling coefficient at the knot region increased when immersed in liquids. However, depending on the initial state of the coupling and the quantity of the increment in the coupling coefficient when immersed in a liquid, it is possible that the MKR may experience a deficit in the coupling parameter due to the sinusoidal relationship with the coupling coefficient. PMID:22015420

Lim, Kok Sing; Jasim, Ali A; Damanhuri, Siti S A; Harun, Sulaiman W; Rahman, B M Azizur; Ahmad, Harith

2011-10-20

362

The three principal secular resonances nu(5), nu(6), and nu(16) in the asteroidal belt  

NASA Astrophysics Data System (ADS)

Theoretical and numerical results obtained for secular resonant motion in the asteroidal belt are reviewed. William's (1969) theory yields the locations of the principal secular resonances nu(5), Nu(6), and nu(16) in the asteroidal belt. Theories by Nakai and Kinoshita (1985) and by Yoshikawa (1987) make it possible to model the basic features of orbital evolution at the secular resonances nu(16) and nu(6), respectively. No theory is available for the secular resonance nu(5). Numerical experiments by Froeschle and Scholl yield quantitative and new qualitative results for orbital evolutions at the three principal secular resonances nu(5), nu(6), and nu(16). These experiments indicate possible chaotic motion due to overlapping resonances. A secular resonance may overlap with another secular resonance or with a mean motion resonance. The role of the secular resonances as possible sources of meteorites is discussed.

Froeschle, Ch.; Scholl, H.

1989-09-01

363

Absolute extinction cross section of individual magnetic split-ring resonators  

Microsoft Academic Search

We measure the absolute extinction cross section spectra of individual split-ring resonators (fundamental magnetic resonance at 1.4-mum wavelength). The experiments are compared with a simple electric-circuit model and with microscopic calculations.

Martin Husnik; Matthias W. Klein; Martin Wegener; Michael König; Jens Niegemann; Kurt Busch; Nils Feth; STEFAN LINDEN

2008-01-01

364

Hafnium neutron cross sections and resonance analysis  

NASA Astrophysics Data System (ADS)

The focus of this thesis is to determine resonance parameters for the stable hafnium isotopes in the 0.005--200 eV region, with emphasis on the overlapping 176Hf and 178Hf resonances near 8 eV. The large neutron cross section of hafnium, combined with its corrosion resistance and excellent mechanical properties, make it an ideal material for controlling nuclear reactions. Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute (RPI) LINAC using the time of flight method. Transmission experiments utilized 6Li glass scintillation detectors at flight path lengths of 15 and 25 m. Capture experiments were done using a sixteen section NaI(Tl) multiplicity type detector at a flight path length of 25 m. These experiments utilized various thicknesses of metallic and isotope-enriched liquid samples. The liquid samples were designed to provide information on the 176Hf and 178Hf contributions to the 8 eV doublet without saturation. Data analysis was done using the R-matrix Bayesian fitting code SAMMY version M6 beta. SAMMY is able to account for experimental resolution effects for each of the experimental setups at the RPI LINAC, and also can correct for some of the multiple scattering effects in yield data. The resolution function for specific experimental setups was determined. A method was developed for estimating errors on the fitted resonance parameters due to uncertainties in the resolution function parameters. The combined capture and transmission data analysis yielded resonance parameters for all stable hafnium isotopes from 0.005--200 eV. Resonance integrals were calculated along with errors for each of the hafnium isotopes using the NJOY and INTER codes. The isotopic resonance integrals calculated were significantly different than some of the previous values; however the calculated elemental hafnium resonance integral changed very little.

Trbovich, Michael J.

365

Electrically connected resonant optical antennas.  

PubMed

Electrically connected resonant optical antennas hold promise for the realization of highly efficient nanoscale electro-plasmonic devices that rely on a combination of electric fields and local near-field intensity enhancement. Here we demonstrate the feasibility of such a concept by attaching leads to the arms of a two-wire antenna at positions of minimal near-field intensity with negligible influence on the antenna resonance. White-light scattering experiments in accordance with simulations show that the optical tunability of connected antennas is fully retained. Analysis of the electric properties demonstrates that in the antenna gaps direct current (DC) electric fields of 10(8) V/m can consistently be achieved and maintained over extended periods of time without noticeable damage. PMID:22800440

Prangsma, Jord C; Kern, Johannes; Knapp, Alexander G; Grossmann, Swen; Emmerling, Monika; Kamp, Martin; Hecht, Bert

2012-08-01

366

Searches for resonances decaying to top  

SciTech Connect

Searches for resonances decaying to top pairs in p{anti p} collisions at {radical}s = 1.96 TeV are presented. An upper limit on the production of a narrow width resonance is given using 2.1 fb{sup -1} data collected by the D0 experiment. Limits on the couplings of a massive gluon are given and a measurement of the differential cross section d{sigma}/dM{sub t{anti t}} is presented using 1.9 fb{sup -1} data collected by the CDF experiment.

Meyer, Jorg; /Gottingen U.

2008-04-01

367

Miniature Sapphire Acoustic Resonator - MSAR  

NASA Technical Reports Server (NTRS)

A room temperature sapphire acoustics resonator incorporated into an oscillator represents a possible opportunity to improve on quartz ultrastable oscillator (USO) performance, which has been a staple for NASA missions since the inception of spaceflight. Where quartz technology is very mature and shows a performance improvement of perhaps 1 dB/decade, these sapphire acoustic resonators when integrated with matured quartz electronics could achieve a frequency stability improvement of 10 dB or more. As quartz oscillators are an essential element of nearly all types of frequency standards and reference systems, the success of MSAR would advance the development of frequency standards and systems for both groundbased and flight-based projects. Current quartz oscillator technology is limited by quartz mechanical Q. With a possible improvement of more than x 10 Q with sapphire acoustic modes, the stability limit of current quartz oscillators may be improved tenfold, to 10(exp -14) at 1 second. The electromagnetic modes of sapphire that were previously developed at JPL require cryogenic temperatures to achieve the high Q levels needed to achieve this stability level. However sapphire fs acoustic modes, which have not been used before in a high-stability oscillator, indicate the required Q values (as high as Q = 10(exp 8)) may be achieved at room temperature in the kHz range. Even though sapphire is not piezoelectric, such a high Q should allow electrostatic excitation of the acoustic modes with a combination of DC and AC voltages across a small sapphire disk (approximately equal to l mm thick). The first evaluations under this task will test predictions of an estimated input impedance of 10 kilohms at Q = 10(exp 8), and explore the Q values that can be realized in a smaller resonator, which has not been previously tested for acoustic modes. This initial Q measurement and excitation demonstration can be viewed similar to a transducer converting electrical energy to mechanical energy and back. Such an electrostatic tweeter type excitation of a mechanical resonator will be tested at 5 MHz. Finite element calculation will be applied to resonator design for the desired resonator frequency and optimum configuration. The experiment consists of the sapphire resonator sandwiched between parallel electrodes. A DC+AC voltage can be applied to generate a force to act on a sapphire resonator. With the frequency of the AC voltage tuned to the sapphire resonator frequency, a resonant condition occurs and the sapphire Q can be measured with a high-frequency impedance analyzer. To achieve high Q values, many experimental factors such as vacuum seal, gas damping effects, charge buildup on the sapphire surface, heat dissipation, sapphire anchoring, and the sapphire mounting configuration will need attention. The effects of these parameters will be calculated and folded into the resonator design. It is envisioned that the initial test configuration would allow for movable electrodes to check gap spacing dependency and verify the input impedance prediction. Quartz oscillators are key components in nearly all ground- and space-based communication, tracking, and radio science applications. They play a key role as local oscillators for atomic frequency standards and serve as flywheel oscillators or to improve phase noise in high performance frequency and timing distribution systems. With ultra-stable performance from one to three seconds, an Earth-orbit or moon-based MSAR can enhance available performance options for spacecraft due to elimination of atmospheric path degradation.

Wang, Rabi T.; Tjoelker, Robert L.

2011-01-01

368

Conductive Coupling of Split Ring Resonators: A Path to THz Metamaterials with Ultrasharp Resonances  

NASA Astrophysics Data System (ADS)

We report on a novel metamaterial structure that sustains extremely sharp resonances in the terahertz domain. This system involves two conductively coupled split ring resonators that together exhibit a novel resonance, in broad analogy to the antiphase mode of the so-called Huygens coupled pendulum. Even though this resonance is in principle forbidden in each individual symmetric split ring, our experiments show that this new coupled mode can sustain quality factors that are more than one order of magnitude larger than those of conventional split ring arrangements. Because of the universality of the metamaterial response, the design principle we present here can be applied across the entire electromagnetic spectrum and to various metamaterial resonators.

Al-Naib, Ibraheem; Hebestreit, Erik; Rockstuhl, Carsten; Lederer, Falk; Christodoulides, Demetrios; Ozaki, Tsuneyuki; Morandotti, Roberto

2014-05-01

369

Conductive Coupling of Split Ring Resonators: A Path to THz Metamaterials with Ultrasharp Resonances.  

PubMed

We report on a novel metamaterial structure that sustains extremely sharp resonances in the terahertz domain. This system involves two conductively coupled split ring resonators that together exhibit a novel resonance, in broad analogy to the antiphase mode of the so-called Huygens coupled pendulum. Even though this resonance is in principle forbidden in each individual symmetric split ring, our experiments show that this new coupled mode can sustain quality factors that are more than one order of magnitude larger than those of conventional split ring arrangements. Because of the universality of the metamaterial response, the design principle we present here can be applied across the entire electromagnetic spectrum and to various metamaterial resonators. PMID:24856698

Al-Naib, Ibraheem; Hebestreit, Erik; Rockstuhl, Carsten; Lederer, Falk; Christodoulides, Demetrios; Ozaki, Tsuneyuki; Morandotti, Roberto

2014-05-01

370

Superconducting coplanar waveguide resonators for low temperature pulsed electron spin resonance spectroscopy  

NASA Astrophysics Data System (ADS)

We discuss the design and implementation of thin film superconducting coplanar waveguide micro-resonators for pulsed electron spin resonance experiments. The performance of the resonators with P doped Si epilayer samples is compared to waveguide resonators under equivalent conditions. The high achievable filling factor even for small sized samples and the relatively high Q-factor result in a sensitivity of 4.5 × 108 spins per shot, which is superior to that of conventional waveguide resonators, in particular to spins close to the sample surface. The peak microwave power is on the order of a few milliwatts, which is compatible with measurements at ultra-low temperatures. We also discuss the effect of the nonuniform microwave magnetic field on the Hahn echo power dependence.

Malissa, H.; Schuster, D. I.; Tyryshkin, A. M.; Houck, A. A.; Lyon, S. A.

2013-02-01

371

Observation of a second order intrinsic depolarizing resonance with a partial Siberian snake  

SciTech Connect

A recent experiment at the Indiana University Cyclotron Facility (IUCF) Cooler Ring found a second order intrinsic depolarizing resonance. The authors injected a spin-polarized beam at 160 MeV and studied both first and second order intrinsic resonances. With a 20% partial Siberian snake they observed clear evidence of a second order depolarizing resonance. This resonance, as expected, is much weaker than the first order intrinsic resonance also studied. Similar experiments with 0% and 10% partial Siberian snakes did not find this resonance.

Crandell, D.A.; Alexeeva, L.V.; Anferov, V.A. [Univ. of Michigan, Ann Arbor, MI (United States)] [and others

1995-04-01

372

Cyclotron Resonances in Electron Cloud Dynamics  

SciTech Connect

A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where lb<< 2pi c/omega c (with lb = bunch length, omega c = non-relativistic cyclotron frequency) resonances between the bunch frequency and harmonics of the electron cyclotron frequency cause an increase in the electron cloud density in narrow ranges of magnetic field near the resonances. For ILC parameters the increase in the density is up to a factor ~;;3, and the spatial distribution of the electrons is broader near resonances, lacking the well-defined vertical density"stripes" found for non-resonant cases. Simulations with the 2D computer code POSINST, as well as a single-particle tracking code, were used to elucidate the physics of the dynamics. The existence of the resonances has been confirmed in experiments at PEP-II. The resonances are expected to affect the electron cloud dynamics in the fringe fields of conventional lattice magnets and in wigglers, where the magnetic fields are low. Results of the simulations and experimental observations, the reason for the bunch-length dependence, and details of the dynamics are discussed here.

Celata, C. M.; Furman, Miguel A.; Vay, J.-L.; Ng, J. S.T.; Grote, D. P.; Pivi, M. T. F.; Wang, L. F.

2009-04-29

373

Fourth-integral resonance study on Alladin at SRC  

SciTech Connect

The fourth-integral betatron resonance driven by sextupoles was studied on the electron storage ring Aladdin at SRC. The resonance feature of capturing the phase space particles in the resonance islands was dearly demonstrated. In a computer simulation, the finite beam size is simulated by multi-particle tracking and the decoherence of the betatron oscillation was shown to agree well with experiment observation.

Liu, J.; Crosbie, E.; Teng, L.; Bridges, J.; Ciarlette, D. [Argonne National Lab., IL (United States); Symon, K. [Wisconsin Univ., Madison, WI (United States). Dept. of Physics; Trzeciak, W. [Wisconsin Univ., Stoughton, WI (United States). Synchrotron Radiation Center

1995-07-01

374

Off-resonant Raman transition impact in an atom interferometer  

Microsoft Academic Search

We study the influence of off-resonant two-photon transitions on high-precision measurements with atom interferometers based on stimulated Raman transitions. These resonances induce a two-photon light shift on the resonant Raman condition. The impact of this effect is investigated in two highly sensitive experiments using a gravimeter and a gyroscope-accelerometer. We show that it can lead to significant systematic phase shifts,

A. Gauguet; T. E. Mehlstäubler; Thomas Lévèque; J. Le Gouët; W. Chaibi; B. Canuel; Andre Clairon; F. Pereira Dos Santos; Arnaud Landragin

2008-01-01

375

Dynamically generated hadron resonances  

NASA Astrophysics Data System (ADS)

As an example of dynamically generated resonances we mention the interaction of vector mesons with baryons within the local hidden gauge formalism which gives rise to a large amount of such states, many of which can be associated to known resonances, while others represent predictions for new resonances. The width of these states coming from decay into pseudoscalar baryon is also addressed. We also mention recent states coming from ?? interaction obtained with Faddeev equations.

Oset, E.; Garzon, E. J.; Xie, Ju Jun; Gonzalez, P.; Ramos, A. Torres; Martinez, A.

2011-10-01

376

Secular resonances - New results  

Microsoft Academic Search

Results are presented from a numerical integration, in the frame of the four-body problem sun-Jupiter-Saturn-asteroid, of the orbit of the asteroid 1974 MA. This asteroid is an earth-crosser located in a region where three resonances overlap: the two secular resonances nu5 and nu6 and the mean motion resonance 5\\/1. The numerical integration yields a qualitative orbital evolution of this particular

Ch. Froeschle; H. Scholl

1988-01-01

377

Acoustic Levitator Maintains Resonance  

NASA Technical Reports Server (NTRS)

Transducer loading characteristics allow resonance tracked at high temperature. Acoustic-levitation chamber length automatically adjusted to maintain resonance at constant acoustic frequency as temperature changes. Developed for containerless processing of materials at high temperatures, system does not rely on microphones as resonance sensors, since microphones are difficult to fabricate for use at temperatures above 500 degrees C. Instead, system uses acoustic transducer itself as sensor.

Barmatz, M. B.; Gaspar, M. S.

1986-01-01

378

Resonant guided wave networks.  

PubMed

A resonant guided wave network is an optical materials design consisting of power-splitting elements arranged at the nodes of a waveguide network. The resulting wave dispersion depends on the network layout due to localized resonances at several length scales in the network. These structures exhibit both localized resonances with a Q approximately 80 at 1550 nm wavelength as well as photonic bands and band gaps in large periodic networks at infrared wavelengths. PMID:20481961

Feigenbaum, Eyal; Atwater, Harry A

2010-04-01

379

Resonant Optical Antennas  

Microsoft Academic Search

We have fabricated nanometer-scale gold dipole antennas designed to be resonant at optical frequencies. On resonance, strong field enhancement in the antenna feed gap leads to white-light supercontinuum generation. The antenna length at resonance is considerably shorter than one-half the wavelength of the incident light. This is in contradiction to classical antenna theory but in qualitative accordance with computer simulations

P. Mühlschlegel; H.-J. Eisler; O. J. F. Martin; B. Hecht; D. W. Pohl

2005-01-01

380

Resonant nonlinear ultrasound spectroscopy  

Microsoft Academic Search

Components with defects are identified from the response to strains applied at acoustic and ultrasound frequencies. The relative resonance frequency shift .vertline..DELTA..function.\\/.function..sub.0.vertline., is determined as a function of applied strain amplitude for an acceptable component, where .function..sub.0 is the frequency of the resonance peak at the lowest amplitude of applied strain and .DELTA..function. is the frequency shift of the resonance

Paul A. Johnson; James A. TenCate; Robert A. Guyer; Koen E. A. Van Den Abeele

2001-01-01

381

Resonances in accelerators  

SciTech Connect

Various resonances important in accelerators are analyzed, with the intention of demonstrating their essential similarity. Transverse instabilities of bunched electron beams are emphasized, including beam--beam effects.

Talman, R.

1987-02-25

382

Resonances in accelerators  

SciTech Connect

Various resonances important in accelerators are analyzed, with the intention of demonstrating their essential similarity. Transverse instabilities of bunched electron beams are emphasized, including beam-beam effects.

Talman, R.

1986-06-01

383

Giant resonance decay  

SciTech Connect

Decay studies of giant multipole resonances are discussed, emphasizing the role of Coulomb excitation with intermediate energy heavy ions, which can provide very large cross sections for both isoscalar and isovector resonances. We discuss measurement of the photon decay of one and two phonon giant resonances, reporting results where available. It is pointed out throughout the presentation that the use of E1 photons as a tag'' provides a means to observe weakly excited resonances that cannot be observed in the singles spectra. 30 refs., 16 figs., 1 tab.

Beene, J.R.; Bertrand, F.E.

1990-01-01

384

Superconducting Microwave Resonators  

NASA Astrophysics Data System (ADS)

High quality factor superconducting microwave resonators play a key role in applications to quantum computation and single photon detection schemes. We have optimized our aluminum quarter wavelength coplanar waveguide resonators in an effort to improve energy decay times. As the characteristic decay times in our samples begin to approach the requirements set out by fault tolerant error correction algorithms, reproducibility becomes a growing focus. Consistent reproduction of high quality factor resonators requires reliable determination of device parameters independent of experimental imperfections and environmental influences. These measurements permit an improved understanding of the variations between nominally identical resonators as well as variations in an individual sample over time. Recent experimental results will be discussed.

Neill, Charles; Megrant, Anthony; Lenander, Mike; Barends, Rami; Wenner, Jim; White, Ted; Sank, Daniel; Chen, Yu; Yin, Yi; Chiaro, Ben; Kelly, Julian; O'Malley, Peter; Roushan, Pedram; Lucero, Erik; Vainsencher, Amit; Bochmann, Joerg; Mariantoni, Matteo; Axline, Chris; Martinis, John; Cleland, Andrew

2012-02-01

385

Notes on Experiments.  

ERIC Educational Resources Information Center

An experiment on cooling by convection, holographic processes achieved using optical fibers and observation of magnetic domains are described. Also describes four demonstrations: mechanical resonance on air track, independence of horizontal/vertical motion, motion of sphere in fluid medium, and light scattering near the critical point. (JN)

Physics Education, 1983

1983-01-01

386

Experimenting with Woodwind Instruments  

ERIC Educational Resources Information Center

Simple experiments involving musical instruments of the woodwind family can be used to demonstrate the basic physics of vibrating air columns in resonance tubes using nothing more than straightforward measurements and data collection hardware and software. More involved experimentation with the same equipment can provide insight into the effects…

LoPresto, Michael C.

2007-01-01

387

Scattering by coupled resonating elements in air  

NASA Astrophysics Data System (ADS)

Scattering by (a) a single composite scatterer consisting of a concentric arrangement of an outer N-slit rigid cylinder and an inner cylinder which is either rigid or in the form of a thin elastic shell and (b) by a finite periodic array of these scatterers in air has been investigated analytically and through laboratory experiments. The composite scatterer forms a system of coupled resonators and gives rise to multiple low-frequency resonances. The corresponding analytical model employs polar angle dependent boundary conditions on the surface of the N-slit cylinder. The solution inside the slits assumes plane waves. It is shown also that in the low-frequency range the N-slit rigid cylinder can be replaced by an equivalent fluid layer. Further approximations suggest a simple square root dependence of the resonant frequencies on the number of slits and this is confirmed by data. The observed resonant phenomena are associated with Helmholtz-like behaviour of the resonator for which the radius and width of the openings are much smaller than the wavelength. The problem of scattering by a finite periodic array of such coupled resonators in air is solved using multiple scattering techniques. The resulting model predicts band-gap effects resulting from the resonances of the individual composite scatterers below the first Bragg frequency. Predictions and data confirm that use of coupled resonators results in substantial insertion loss peaks related to the resonances within the concentric configuration. In addition, for both scattering problems experimental data, predictions of the analytical approach and predictions of the equivalent fluid layer approximations are compared in the low-frequency interval.

Krynkin, Anton; Umnova, Olga; Chong, Alvin Y. B.; Taherzadeh, Shahram; Attenborough, Keith

2011-03-01

388

Airborne surface plasmon resonance biosensing  

NASA Astrophysics Data System (ADS)

On March 14, 2003 an experimental aircraft fitted with surface plasmon resonance (SPR) biosensors connected to an air sampling system performed a 90-minute flight over Renton, Washington, demonstrating the first-ever use of SPR sensors for airborne biodetection. In this paper, we describe the instrumentation constructed for this purpose, the experiment conducted, and the results obtained. Instrumentation was based on Texas Instruments" Spreeta SPR sensors combined with sample collection and fluidic apparatus designed for airborne sensing. Detection targets were two innocuous proteins ovalbumin and horseradish peroxidase. We describe future enhancements necessary to apply this technology on an unmanned airborne vehicle.

Chinowsky, Timothy M.; Naimushin, Alexei; Soelberg, Scott; Spinelli, Charles; Kauffman, Peter; Yee, Sinclair S.; Furlong, Clement E.

389

The Experimental Status of Baryon Resonances  

NASA Astrophysics Data System (ADS)

Nucleons are complex systems of confined quarks and exhibit characteristic spectra of excited states. Highly excited nucleon states are sensitive to details of quark confinement which is poorly understood within Quantum Chromodynamics (QCD), the fundamental theory of strong interactions. Thus, measurements of excited nucleon states and the corresponding determination of their properties are needed to come to a better understanding of how confinement works in nucleons. However, the excited states of the nucleon cannot simply be inferred from cleanly separated spectral lines. Quite the contrary, a spectral analysis in nucleon resonance physics is challenging because of the fact that these resonances are broadly overlapping states which decay into a multitude of final states involving mesons and baryons. To provide a consistent and complete picture of an individual nucleon resonance, the various possible production and decay channels must eventually be treated in a multi-channel framework that permits separating resonance from background contributions. A long-standing question in hadron physics is whether the large number of so-called missing baryon resonances really exists, i.e. experimentally not established baryon states which are predicted by quark models based on three constituent quark effective degrees of freedom. It is important to emphasize that nearly all existing data on non-strange production of baryon resonances result from ?N scattering experiments. However, quark models predict strong couplings of these missing states to ?p rendering the study of these resonances in photo-induced reactions a very promising approach. Several new states have in fact been proposed in recent experiments. Current and upcoming experiments at Jefferson Laboratory will determine polarization (or spin) observables for photoproduction processes involving baryon resonances. Differences between the predictions for these observables can be large, and so conversely they provide strong constraints on the analysis. An interesting question is whether it is possible to design a complete set of experiments which will uniquely determine the scattering amplitude for a given process. The current effort with the CLAS detector at Jefferson Lab is to utilize highly-polarized frozen-spin (butanol) and deuterium targets in combination with polarized photon beams. In particular, the very successful FROST experiment took the first double-polarization data from November '07 to February '08 paving the way for a complete experiment in K? and K? photoproduction. This contribution will review recent results and also discuss open questions and perspectives in N^* physics.

Crede, Volker

2010-11-01

390

Convertible pneumatic actuator for magnetic resonance elastography of the brain  

Microsoft Academic Search

Here we present a novel pneumatic actuator design for brain magnetic resonance elastography (MRE). Magnetic resonance elastography is a phase contrast technique capable of tracing strain wave propagation and utilizing this information for the calculation of mechanical properties of materials and living tissues. In MRE experiments, the acoustic waves are generated in a synchronized way with respect to image acquisition,

Peter Latta; Marco L. H. Gruwel; Patricia Debergue; Brendon Matwiy; Uta N. Sboto-Frankenstein; Boguslaw Tomanek

2011-01-01

391

Resonant four-wave mixing of laser radiation in plasmas  

Microsoft Academic Search

Experimental evidence of resonant four-wave mixing of COâ laser radiation in a plasma is presented for the first time to our knowledge. Comparison of the experiment with theory indicates that, while collisions lead to a narrow spectral width of the ion acoustic resonance, convection and detuning owing to laser heating limit the enhancement of the signal reflectivity to below the

A. Lal; Chan Joshi

1991-01-01

392

Single Molecule Electron Paramagnetic Resonance  

NASA Astrophysics Data System (ADS)

Electron paramagnetic resonance (EPR) is a powerful spectroscopic tool for studying the dynamics of biomolecular systems. EPR measurements on bulk samples using a commercial X-band spectrometer provide insight into atomic-scale structure and dynamics of ensembles of biomolecules. Separately, single molecule measurements of biomolecular systems allow researchers to capture heterogeneous behaviors that have revealed the molecular mechanisms behind many biological processes. We are merging these two powerful techniques to perform single molecule EPR. In this experiment, we selectively label double-stranded DNA molecules with nitrogen-vacancy (NV) center nanodiamonds and optically detect the magnetic resonance of the NV probe. Shifts and broadening of our EPR peaks indicate the changing position of the attached DNA relative to the applied magnetic field. Using this new technique, we have successfully measured the first EPR spectrum of a single biomolecule. By controlling the geometry of the diamond and the applied magnetic field, we will quantitatively determine the rotational and translational dynamics of single biomolecules. This research provides the foundation for an advanced single molecule magnetic resonance approach to studies of complex biomolecular systems.

Teeling-Smith, Richelle M.; Johnston-Halperin, Ezekiel; Poirier, Michael G.; Hammel, P. Chris

2013-03-01

393

Electrodynamics of a ring-shaped spiral resonator  

NASA Astrophysics Data System (ADS)

We present analytical, numerical, and experimental investigations of electromagnetic resonant modes of a compact monofilar Archimedean spiral resonator shaped in a ring, with no central part. Planar spiral resonators are interesting as components of metamaterials for their compact deep-subwavelength size. Such resonators couple primarily to the magnetic field component of the incident electromagnetic wave, offering properties suitable for magnetic meta-atoms. Surprisingly, the relative frequencies of the resonant modes follow the sequence of the odd numbers as f1:f2:f3:f4… = 1:3:5:7…, despite the nearly identical boundary conditions for electromagnetic fields at the extremities of the resonator. In order to explain the observed spectrum of resonant modes, we show that the current distribution inside the spiral satisfies a particular Carleman type singular integral equation. By solving this equation, we obtain a set of resonant frequencies. The analytically calculated resonance frequencies and the current distributions are in good agreement with experimental data and the results of numerical simulations. By using low-temperature laser scanning microscopy of a superconducting spiral resonator, we compare the experimentally visualized ac current distributions over the spiral with the calculated ones. Theory and experiment agree well with each other. Our analytical model allows for calculation of a detailed three-dimensional magnetic field structure of the resonators.

Maleeva, N.; Fistul, M. V.; Karpov, A.; Zhuravel, A. P.; Averkin, A.; Jung, P.; Ustinov, A. V.

2014-02-01

394

Resonance Conditions of Open Resonators at Microwave Frequencies.  

National Technical Information Service (NTIS)

The paper presents an extension of Vajnshtejn's approach for computing the resonance frequencies and loss factors of Fabry-Perot (FP) resonators at microwave frequencies. Numerical results are presented for FP resonators operated at microwave through mill...

T. Itch R. Mittra

1973-01-01

395

Precision Electroweak Measurements on the Z Resonance.  

National Technical Information Service (NTIS)

The authors report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. the data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3...

2005-01-01

396

TRITIUM PRODUCTION AND SELECTIVE RESONANT TUNNELING MODEL  

Microsoft Academic Search

Two principles of the selective resonant tunneling model are recapitulated, and applied to the case of tritium production. The model can explain the tritium production in condensed matter nuclear reaction with no neutron and gamma radiation semi-quantitatively. A similar model may excess heat with no commensurate neutron and gamma radiation. Some experiments are suggested to test our explanation. 1. TRITIUM

Si Chen; Xing Z. Li

397

Magnetic resonance, nuclear orientation and antiferromagnetism  

Microsoft Academic Search

A small range of compounds contain ions from two transition groups, 3d and 4f. Most of these enter an ordered antiferromagnetic state only at liquid helium temperatures, and the internal fields are 1 tesla or less. Experiments are suggested on various single crystals. Measurements by electron spin resonance on impurity ions in antiferromagnetic dysprosium phosphate show that similar compounds could

B. Bleaney

1998-01-01

398

Resonance Phenomena in Fluid Media. Abstract.  

National Technical Information Service (NTIS)

Studies were made to detect the presence of a memory in fluid media. The experiments revealed that the effect of electromagnetic radiation on fluid media can be explained by the phenomenon of resonant response of the system receiving the radiation. Studie...

A. T. Lukyanov V. M. Inyushin A. P. Gorokhov

1987-01-01

399

The resonator handbook  

NASA Technical Reports Server (NTRS)

The purpose of this work is to extend resonator theory into the region in which the planar mirror is quite small. Results of the theoretical description are then extended to resonator design and experimental arrangements as discussed in further sections of this work. Finally, a discussion of dielectric measurements for small samples is included as a specific application of this work.

Cook, Jerry D.; Zhou, Shiliang

1993-01-01

400

The Concept of Resonance  

ERIC Educational Resources Information Center

A general example of a delocalization system associated with a higher energy than the localized one, which suggests that it is wrong to consider delocalization as equivalent to resonance stabilization, is presented. The meaning of resonance energy as it appears in valence bond theory is described as the lowering of the calculated ground-state…

Truhlar, Donald G.

2007-01-01

401

Resonance characteristics of waveguide-coupled polyimide microring resonator  

Microsoft Academic Search

We report for the first time on the resonance characteristics of a polyimide-based micro-ring resonator model. The resonator consists of a microring coupled to a pair of waveguides. Using the finite-difference time-domain method, we were able to obtain resonance peaks, from which the resonance wavelength could be identified. For a resonator with a microring of 10 ?m diameter, known as

Hak-Phil Lee; Jong-Jin Park; Hyun-Ho Ryoo; Seung Gol Lee; O Beom Hoan; El-Hang Lee

2003-01-01

402

Resonant snubber inverter  

DOEpatents

A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter.

Lai, Jih-Sheng (Knoxville, TN); Young, Sr., Robert W. (Oak Ridge, TN); Chen, Daoshen (Knoxville, TN); Scudiere, Matthew B. (Oak Ridge, TN); Ott, Jr., George W. (Knoxville, TN); White, Clifford P. (Knoxville, TN); McKeever, John W. (Oak Ridge, TN)

1997-01-01

403

Resonant snubber inverter  

DOEpatents

A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter. 14 figs.

Lai, J.S.; Young, R.W. Sr.; Chen, D.; Scudiere, M.B.; Ott, G.W. Jr.; White, C.P.; McKeever, J.W.

1997-06-24

404

Alternating current circuit theory and pulsed NMR (Nuclear Magnetic Resonance)  

NASA Astrophysics Data System (ADS)

Pulsed NMR, by definition, deals with time varying excitations. These excitations, supplied by resonant circuits which provide a pulse of radiofrequency (frequencies in the megahertz region) power to a resonant circuit containing, among other things, a coil of wire, or inductor, in which a sample under investigation is placed for purposes of the nuclear magnetic resonance experiment. There are therefore two features of the pulse NMR experiment. First is the fact that we have available a source of continuous wave (CW) alternating current at some angular frequency, omega, measured in radians per second. This source is generally supplied by an ultrastable device called a frequency synthesizer. The second feature of the pulsed NMR experiment is that the sample is not continuously irradiated, but a pulse of radiofrequency oscillation is applied to the sample. This report discusses alternating current theory, resonant circuits and the equipment used in this experiment.

Gerstein, B. C.

1987-06-01

405

Air Column Resonance Spectra Using Basic Laboratory Equipment.  

ERIC Educational Resources Information Center

Several experiments are described using common laboratory apparatus and readily available materials to generate resonance spectra of air columns. The advantages of this apparatus and method of demonstration are visual impact and accuracy of results. (CS)

Jewett, J. W., Jr.

1980-01-01

406

Acoustic Resonance of Superfluid 3He in Parallel Plates  

NASA Astrophysics Data System (ADS)

We performed an acoustic resonance experiment of superfluid 3He confined in a stack of parallel plates, and found the fourth sound resonance. From its velocity, the superfluid density fraction was calculated. No size effect was found because the gap between parallel plates were much larger than the superfluid coherence length. The energy loss of the resonance was also measured. We found that the hydrodynamic theory qualitatively described its temperature dependence, but it could not describe the gap width dependence. Possible explanations is discussed in the text. More over, we found the unidentified resonance that cannot be explained by conventional sound modes.

Obara, K.; Kato, C.; Sasamoto, S.; Yano, H.; Ishikawa, O.; Hata, T.

2011-02-01

407

Neutron Resonance Spin Determination Using Multi-Segmented Detector DANCE  

NASA Astrophysics Data System (ADS)

A sensitive method to determine the spin of neutron resonances is introduced based on the statistical pattern recognition technique. The new method was used to assign the spins of s-wave resonances in 155Gd. The experimental neutron capture data for these nuclei were measured with the DANCE (Detector for Advanced Neutron Capture Experiment) calorimeter at the Los Alamos Neutron Science Center. The highly segmented calorimeter provided detailed multiplicity distributions of the capture ?-rays. Using this information, the spins of the neutron capture resonances were determined. With these new spin assignments, level spacings are determined separately for s-wave resonances with J? = 1- and 2-.

Baramsai, B.; Mitchell, G. E.; Agvaanluvsan, U.; Becvar, F.; Bredeweg, T. A.; Couture, A.; Chyzh, A.; Dashdorj, D.; Haight, R. C.; Jandel, M.; Keksis, A. L.; Krticka, M.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Walker, C.; Wouters, J. M.

2011-06-01

408

Coherence-Assisted Resonance with Sub-Transit-Limited Linewidth  

NASA Astrophysics Data System (ADS)

We demonstrate a novel approach to obtain a resonance linewidth below the transit limit. The cross correlation between the induced intensity modulation of two lasers coupling the target resonance exhibits a narrow spectrum. 1/30 of the transit-limited width is achieved in a proof-of-principle experiment where two ground states are the target resonance levels. Attainable linewidth is only limited by laser shot noise in principle. The experimental results qualitatively agree with an intuitive analytical model and numerical calculations. This technique can be easily implemented and should be applicable to many atomic, molecular, and solid state spin systems for spectroscopy, metrology, and resonance-based sensing and imaging.

Feng, Lei; Li, Pengxiong; Jiang, Liang; Wen, Jianming; Xiao, Yanhong

2012-12-01

409

Stability Limits in Resonant Planetary Systems  

NASA Astrophysics Data System (ADS)

The relationship between the boundaries for Hill and Lagrange stability in orbital element space is modified in the case of resonantly interacting planets. Hill stability requires the ordering of the planets to remain constant, while Lagrange stability also requires all planets to remain bound to the central star. The Hill stability boundary is defined analytically, but no equations exist to define the Lagrange boundary, so we perform numerical experiments to estimate the location of this boundary. To explore the effect of resonances, we consider orbital element space near the conditions in the HD 82943 and 55 Cnc systems. Previous studies have shown that, for nonresonant systems, the two stability boundaries are nearly coincident. However, the Hill stability formulae are not applicable to resonant systems, and our investigation shows how the two boundaries diverge in the presence of a mean-motion resonance, while confirming that the Hill and Lagrange boundaries are similar otherwise. In resonance the region of stability is larger than the domain defined by the analytic formula for Hill stability. We find that nearly all known resonant interactions currently lie in this unexpectedly stable region, i.e., where the orbits would be unstable according to the nonresonant Hill stability formula. This result bears on the dynamical packing of planetary systems, showing how quantifying planetary systems' dynamical interactions (such as proximity to the Hill stability boundary) provides new constraints on planet formation models.

Barnes, Rory; Greenberg, Richard

2007-08-01

410

Cavity QED with Microtoroidal Optical Resonators  

NASA Astrophysics Data System (ADS)

Quantum control of strong interactions between a single atom and a single photon has been achieved within the setting of cavity quantum electrodynamics (cQED). To move beyond proof-of-principle experiments involving one or two conventional optical cavities to more complex scalable systems that employ many microscopic resonators requires localization of atoms on distance scales ˜100 nm from a resonator's surface. A single atom trapped near the surface of a fiber-coupled microtoroidal resonator provides a promising system that allows access to a new regime of cQED. Here, due to its proximity to the surface of the resonator, an atom experiences both strong 1-photon and surface interactions [1]. To advance beyond transient observations [1], we are currently working to trap single atoms within the evanescent field of a microtoroidal resonator using a single tapered fiber to provide both optical coupling and a dipole trap for the atoms [2-4]. Our goal is to realize a flexible experimental platform for investigations of small quantum networks using strong interactions of single atoms and photons. [4pt] [1] D. J. Alton, et al., Nature Phys. 7, 159 (2011).[0pt] [2] V. I. Balykin et al. Phys. Rev. Lett., 60, 2137 (1988).[0pt] [3] E. Vetsch et al., Phys. Rev. Lett., 104, 203603 (2010).[0pt] [4] C. Lacroute et al., arXiv:1110.5372.

Alton, D. J.; Lacroute, C.; Forn-Diaz, P.; McClung, A.; Stern, N. P.; Aoki, Takao; Lee, H.; Ostby, E.; Vahala, K. J.; Kimble, H. J.

2012-06-01

411

Localized ferromagnetic resonance force microscopy of permalloy-cobalt films  

SciTech Connect

We report the Ferromagnetic Resonance Force Microscopy (FMRFM) experiments on a combined permalloy-cobalt continuous film. Our studies demonstrate the capability of FMRFM to perform local spectroscopy of different ferromagnetic materials. Theoretical analysis of the uniform resonance mode at the edge of the film provides good quantitative agreement with the experimental data. Our experiments demonstrate the micron scale lateral resolution and allow to extract local magnetic properties in continuous ferromagnetic samples.

Nazaretski, Evgueni [Los Alamos National Laboratory; Movshovich, Roman [Los Alamos National Laboratory; Martin, Ivar [Los Alamos National Laboratory; Cha, Kitty V [Los Alamos National Laboratory; Akhadov, Elshan A [Los Alamos National Laboratory; Obukhov, Yu [OH STATE U; Pelekhov, D C [OH STATE U; Hammel, P C [OH STATE U

2008-01-01

412

Degenerate and Resonant Four-Wave Mixing in Plasmas  

Microsoft Academic Search

The status of degenerate and resonant four-wave mixing in plasmas is reviewed. For the degenerate case in a collisional plasma, the theory predicts and experiments demonstrate that the thermal-force contribution to the signal reflectivity dominates over the ponderomotive-force contribution. In the resonant case, the reflectivity can be enhanced over the degenerate level. Experiments show that collisions can lead to a

C. Joshi; Y. Kitagawa; A. Lal

1992-01-01

413

Resonant quantum transitions in trapped antihydrogen atoms.  

PubMed

The hydrogen atom is one of the most important and influential model systems in modern physics. Attempts to understand its spectrum are inextricably linked to the early history and development of quantum mechanics. The hydrogen atom's stature lies in its simplicity and in the accuracy with which its spectrum can be measured and compared to theory. Today its spectrum remains a valuable tool for determining the values of fundamental constants and for challenging the limits of modern physics, including the validity of quantum electrodynamics and--by comparison with measurements on its antimatter counterpart, antihydrogen--the validity of CPT (charge conjugation, parity and time reversal) symmetry. Here we report spectroscopy of a pure antimatter atom, demonstrating resonant quantum transitions in antihydrogen. We have manipulated the internal spin state of antihydrogen atoms so as to induce magnetic resonance transitions between hyperfine levels of the positronic ground state. We used resonant microwave radiation to flip the spin of the positron in antihydrogen atoms that were magnetically trapped in the ALPHA apparatus. The spin flip causes trapped anti-atoms to be ejected from the trap. We look for evidence of resonant interaction by comparing the survival rate of trapped atoms irradiated with microwaves on-resonance to that of atoms subjected to microwaves that are off-resonance. In one variant of the experiment, we detect 23 atoms that survive in 110 trapping attempts with microwaves off-resonance (0.21 per attempt), and only two atoms that survive in 103 attempts with microwaves on-resonance (0.02 per attempt). We also describe the direct detection of the annihilation of antihydrogen atoms ejected by the microwaves. PMID:22398451

Amole, C; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Capra, A; Cesar, C L; Charlton, M; Deller, A; Donnan, P H; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Isaac, C A; Jonsell, S; Kurchaninov, L; Little, A; Madsen, N; McKenna, J T K; Menary, S; Napoli, S C; Nolan, P; Olchanski, K; Olin, A; Pusa, P; Rasmussen, C Ø; Robicheaux, F; Sarid, E; Shields, C R; Silveira, D M; Stracka, S; So, C; Thompson, R I; van der Werf, D P; Wurtele, J S

2012-03-22

414

LABCOM resonator Phase 3  

SciTech Connect

The purpose of this project was to develop quartz crystal resonator designs, production processes, and test capabilities for 5-MHz, 6.2-MHz, and 10-MHz resonators for Tactical Miniature Crystal Oscillator (TMXO) applications. GE Neutron Devices (GEND) established and demonstrated the capability to produce and test quartz crystal resonators for use in the TMXO developed by the US Army ERADCOM (now LABCOM). The goals in this project were based on the ERADCOM statement of work. The scope of work indicated that the resonator production facilities for this project would not be completely independent, but that they would be supported in part by equipment and processes in place at GEND used in US Department of Energy (DOE) work. In addition, provisions for production test equipment or or eventual technology transfer costs to a commercial supplier were clearly excluded from the scope of work. The demonstrated technical capability of the deep-etched blank design is feasible and practical. It can be manufactured in quantity with reasonable yield, and its performance is readily predictable. The ceramic flatpack is a very strong package with excellent hermeticity. The four-point mount supports the crystal to reasonable shock levels and does not perturb the resonator's natural frequency-temperature behavior. The package can be sealed with excellent yields. The high-temperature, high-vacuum processing developed for the TMXO resonator, including bonding the piezoid to its mount with conductive polyimide adhesive, is consistent with precision resonator fabrication. 1 fig., 6 tabs.

Keres, L.J.

1990-11-01

415

A phase qubit coupled to an RF-SQUID resonator  

NASA Astrophysics Data System (ADS)

We have coupled a tunable cavity (an RF-SQUID resonator) to a phase qubit. The resonator can be used both for state transfer experiments as well as a measurement/readout device for the qubit. Specifically, it can be used in three different ways to help interrogate the state of the qubit. First, changes in the resonator frequency can be monitored in order to read out the qubit state after a conventional fast measure pulse is applied to the qubit bias flux. Second, we can perform a linear dispersive measurement of the qubit state using the coupled interaction between the qubit and the resonator. Here, the resonator will have a qubit-state dependent frequency shift. Finally, we can exploit the nonlinearity of the resonator by driving it into the bifurcated regime and performing a single- shot measurement of the state of the qubit. I will discuss the design, fabrication, and operation of this system.

Whittaker, Jed; Allman, Shane; Cicak, Katarina; Nguyen, Francois; Sirois, Adam; Teufel, John; Zakka-Bajjani, Eva; Simmonds, Raymond

2011-03-01

416

Anomalous magnetic field effects in high Q superconducting resonators  

NASA Astrophysics Data System (ADS)

Superconducting coplanar wave guide resonators are an important tool in quantum computing for use as memory elements. Recent process improvements have allowed for quality factors in excess of 1.5 million at single photon excitations. While allowing for more sensitive experiments, the most recent group of resonators exhibit very high sensitivity to magnetic fields. Ordinarily Abrikosov vortex physics is expected to govern the magnetic response of the resonators. During field cooling, vortices begin to form at a threshold field, Bth, that depends quadratically on the width of the resonator. However these resonators show an observed Bth two orders of magnitude lower than predicted by theory and without any scaling with resonator width. We explore increased sensitivity to frequency fluctuations at nonzero field as a possible explanation for reduced quality factor long before vortices are expected to form.

Lenander, M.; Barends, R.; Chen, Yu; Kelly, J.; Lucero, Erik; Mariantoni, Matteo; Megrant, A.; O'Malley, P. J. J.; Neill, C.; Sank, D.; Vainsencher, A.; Wang, H.; Wenner, J.; White, T. C.; Yin, Y.; Zhao, J.; Palmstrom, C.; Cleland, A. N.; Martinis, John M.

2012-02-01

417

Giant resonances in single and double charge exchange  

SciTech Connect

A long-standing issue in nuclear physics is whether or not multiple excitations of the giant-dipole resonance do exist. Recent studies at LAMPF using pion-induced double-charge exchange reactions show the existence of previously unobserved giant resonances in the continuum at high-excitation energies. Based on their energies, characteristic angular distributions, and the cross sections at which the resonances are observed, they have been identified as two different types of double-collective-excitation modes of the nucleus: (1) The isovector giant-dipole resonance built on the isobaric analog state and (2) the isovector giant-dipole resonance built on the giant dipole. In this report we will discuss the general features of the new resonances as they have emerged from DCX experiments performed recently at LAMPF. 12 refs., 7 figs.

Mordechai, S. (Ben-Gurion Univ. of the Negev, Beersheba (Israel) Texas Univ., Austin, TX (United States)); Moore, C.F. (Texas Univ., Austin, TX (United States))

1991-01-01

418

Tunable multiwalled nanotube resonator  

DOEpatents

A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

Zettl, Alex K. (Kensington, CA); Jensen, Kenneth J. (Berkeley, CA); Girit, Caglar (Albany, CA); Mickelson, William E. (San Francisco, CA); Grossman, Jeffrey C. (Berkeley, CA)

2011-03-29

419

Microwave Oscillators Based on Nonlinear WGM Resonators  

NASA Technical Reports Server (NTRS)

Optical oscillators that exploit resonantly enhanced four-wave mixing in nonlinear whispering-gallery-mode (WGM) resonators are under investigation for potential utility as low-power, ultra-miniature sources of stable, spectrally pure microwave signals. There are numerous potential uses for such oscillators in radar systems, communication systems, and scientific instrumentation. The resonator in an oscillator of this type is made of a crystalline material that exhibits cubic Kerr nonlinearity, which supports the four-photon parametric process also known as four-wave mixing. The oscillator can be characterized as all-optical in the sense that the entire process of generation of the microwave signal takes place within the WGM resonator. The resonantly enhanced four-wave mixing yields coherent, phase-modulated optical signals at frequencies governed by the resonator structure. The frequency of the phase-modulation signal, which is in the microwave range, equals the difference between the frequencies of the optical signals; hence, this frequency is also governed by the resonator structure. Hence, further, the microwave signal is stable and can be used as a reference signal. The figure schematically depicts the apparatus used in a proof-of-principle experiment. Linearly polarized pump light was generated by an yttrium aluminum garnet laser at a wavelength of 1.32 microns. By use of a 90:10 fiber-optic splitter and optical fibers, some of the laser light was sent into a delay line and some was transmitted to one face of glass coupling prism, that, in turn, coupled the laser light into a crystalline CaF2 WGM disk resonator that had a resonance quality factor (Q) of 6x10(exp 9). The output light of the resonator was collected via another face of the coupling prism and a single-mode optical fiber, which transmitted the light to a 50:50 fiber-optic splitter. One output of this splitter was sent to a slow photodiode to obtain a DC signal for locking the laser to a particular resonator mode. The other output of this splitter was combined with the delayed laser signal in another 50:50 fiber-optic splitter used as a combiner. The output.of the combiner was fed to a fast photodiode that demodulated light and generated microwave signal. In this optical configuration, the resonator was incorporated into one arm of a Mach-Zehnder interferometer, which was necessary for the following reasons: It was found that when the output of the resonator was sent directly to a fast photodiode, the output of the photodiode did not include a measurable microwave signal. However, when the resonator was placed in an arm of the interferometer and the delay in the other arm was set at the correct value, the microwave signal appeared. Such behavior is distinctly characteristic of phase-modulated light. The phase-modulation signal had a frequency of about 8 GHz, corresponding to the free spectral range of the resonator. The spectral width of this microwave signal was less than 200 Hz. The threshold pump power for generating the microwave signal was about 1 mW. It would be possible to reduce the threshold power by several orders of magnitude if resonators could be made from crystalline materials in dimensions comparable to those of micro-resonators heretofore made from fused silica.

Maleki, Lute; Matsko, Andrey; Savchenkov, Anatoliy; Strekalov, Dmitry

2006-01-01

420

Comparison of multiple-scan direct and lock-in detection in magnetic resonance: Application to nuclear acoustic resonance  

NASA Astrophysics Data System (ADS)

Theoretical expressions are derived for the signal-to-noise ratios in magnetic resonance experiments for the lock-in and multiple-scan direct detection schemes. Effects of noise character, post-spectrometer filters, and modulation frequency are included in the analysis. The theoretical results are found to be in good agreement with experiment for the specific case of nuclear acoustic resonance in a metal single crystal.

Ashton, G. R.; Hsu, D. K.; Leisure, R. G.

1980-04-01

421

Magnetic resonance elastography detected with a SQUID in microtesla magnetic fields  

Microsoft Academic Search

We have used a SQUID-based microtesla magnetic resonance imaging (MRI) system to perform magnetic resonance elastography (MRE) experiments in a measurement field of 132 microtesla. Magnetic resonance elastography is based on MRI and measures three-dimensional displacement and strain fields in a sample. With appropriate data processing this allows for a quantitative map of the physical response of a material to

Nathan Kelso; Kristie Koski; Jeffrey Reimer

2005-01-01

422

Resonant neutrino activation and neutrino oscillations  

NASA Astrophysics Data System (ADS)

Low Q value weak nuclear decays are considered which have two body final states (electron captures and bound state beta decays, BSD). This permits an analogy with the Mössbauer effect, where the emitted (anti) neutrinos will resonantly activate daughter nuclei in a suitable absorber. Candidates for such a process are examined and the relevant solid state host problems are discussed. We point out that resonant line widths as large as the narrowest observed in Mössbauer spectroscopy suffice to greatly extend the sensitivity of ? [disappearance] oscillation experiments.

Kells, William P.

1983-06-01

423

Resonant neutrino activation and neutrino oscillations  

SciTech Connect

Low Q value weak nuclear decays are considered which have two body final states (electron captures and bound state ..beta.. decays, BSD). This permits an analogy with the Moessbauer effect, where the emitted (anti)neutrinos will resonantly activate daughter nuclei in a suitable absorber. Candidates for such a process are examined and the relevant solid state host problems are discussed. The authors point out that resonant line widths as large as the narrowest observed in Moessbauer spectroscopy suffice to greatly extend the sensitivity of nu (disappearance) oscillation experiments.

Kells, W.P.

1983-01-01

424

Double-pass hybrid resonator for COIL  

NASA Astrophysics Data System (ADS)

Based on the experiences made with a negative-branch hybrid resonator (NBHR) a double-pass configuration of the NBHR for a 10 kW class Chemical Oxygen Iodine Laser (COIL) is investigated. Measurements of the intensity distribution of the far field are performed, as well as measurements of the sensitivity against tilts of one of the resonator mirrors. The results are compared to calculations