Resonance Transport of Graphene Nanoribbon T-Shaped Junctions

International Nuclear Information System (INIS)

Xiao-Lan, Kong; Yong-Jian, Xiong

2010-01-01

We investigate the transport properties of T-shaped junctions composed of armchair graphene nanoribbons of different widths. Three types of junction geometries are considered. The junction conductance strongly depends on the atomic features of the junction geometry. When the shoulders of the junction have zigzag type edges, sharp conductance resonances usually appear in the low energy region around the Dirac point, and a conductance gap emerges. When the shoulders of the junction have armchair type edges, the conductance resonance behavior is weakened significantly, and the metal-metal-metal junction structures show semimetallic behaviors. The contact resistance also changes notably due to the various interface geometries of the junction

Design of a broadband hexagonal-shaped zeroth-order resonance antenna with metamaterials

Energy Technology Data Exchange (ETDEWEB)

Woo, Dong Sik; Kim, Kang Wook; Choi, Hyun Chul [Kyungpook National University, Daegu (Korea, Republic of)

2014-11-15

A broadband hexagonal-shaped metamaterials (MTMs)-based zeroth-order resonant (ZOR) antenna was designed and fabricated. The hexagonal shape of a top patch on a mushroom structure makes not only direct-current paths between the two ends of the patch but also round-current paths along the outside of the patch, thereby widening the resonance frequency of the mushroom MTM antenna. According to the shape of the hexagon patch, the presented antenna achieved impedance bandwidth of 58.6% corresponding to ultra-wideband technology. The proposed ZOR antenna was modeled by utilizing a composite right- and left-handed (CRLH) transmission line and provided 4 to 9.3 dBi of the antenna gain with reduced size as compared to conventional microstrip antennas at Ku- to K-band frequencies.

TANGLED MAGNETIC FIELDS IN SOLAR PROMINENCES

International Nuclear Information System (INIS)

Van Ballegooijen, A. A.; Cranmer, S. R.

2010-01-01

Solar prominences are an important tool for studying the structure and evolution of the coronal magnetic field. Here we consider so-called hedgerow prominences, which consist of thin vertical threads. We explore the possibility that such prominences are supported by tangled magnetic fields. A variety of different approaches are used. First, the dynamics of plasma within a tangled field is considered. We find that the contorted shape of the flux tubes significantly reduces the flow velocity compared to the supersonic free fall that would occur in a straight vertical tube. Second, linear force-free models of tangled fields are developed, and the elastic response of such fields to gravitational forces is considered. We demonstrate that the prominence plasma can be supported by the magnetic pressure of a tangled field that pervades not only the observed dense threads but also their local surroundings. Tangled fields with field strengths of about 10 G are able to support prominence threads with observed hydrogen density of the order of 10 11 cm -3 . Finally, we suggest that the observed vertical threads are the result of Rayleigh-Taylor instability. Simulations of the density distribution within a prominence thread indicate that the peak density is much larger than the average density. We conclude that tangled fields provide a viable mechanism for magnetic support of hedgerow prominences.

Ultra-small v-shaped gold split ring resonators for biosensing using fundamental magnetic resonance in the visible spectrum

Science.gov (United States)

Mauluidy Soehartono, Alana; Mueller, Aaron David; Tobing, Landobasa Yosef Mario; Chan, Kok Ken; Zhang, Dao Hua; Yong, Ken-Tye

2017-10-01

Strong light localization within metal nanostructures occurs by collective oscillations of plasmons in the form of electric and magnetic resonances. This so-called localized surface plasmon resonance (LSPR) has gained much interest in the development of low-cost sensing platforms in the visible spectrum. However, demonstrations of LSPR-based sensing are mostly limited to electric resonances due to the technological limitations for achieving magnetic resonances in the visible spectrum. In this work, we report the first demonstration of LSPR sensing based on fundamental magnetic resonance in the visible spectrum using ultrasmall gold v-shaped split ring resonators. Specifically, we show the ability for detecting adsorption of bovine serum albumin and cytochrome c biomolecules at monolayer levels, and the selective binding of protein A/G to immunoglobulin G.

Interior and exterior resonances in acoustic scattering. pt. 2 - Targets of arbitrary shape (T-matrix approach)

International Nuclear Information System (INIS)

Uberall, H.; Gaunaurd, G.C.; Tanglis, E.

1983-01-01

The T-matrix approach, which describes the scattering of acoustic waves (or of other waves) from objects of arbitrary shape and geometry, is here 'married' to the resonance scattering theory in order to obtain the (complex) resonance frequencies of an arbitrary shaped target. For the case of nearly impenetrable targets the partial-wave scattering amplitudes are splitted into terms corresponding to 'internal' resonances, plus an apparently nonresonant background amplitude which, however, contains the broad resonances caused by 'external' diffracted (or Franz-type, creeping) waves, in addition to geometrically reflected and refracted (ray) contributions

Analysis of acoustic resonator with shape deformation using finite ...

Indian Academy of Sciences (India)

G M KALMSEa, AJAY CHAUDHARIb and P B PATILb a Science College, PB No. 62, Nanded 431603, India b Department of Physics, Dr B A M University, Aurangabad 431 004, India e-mail: bamuaur@bom4.vsnl.net.in. MS received 23 September 1999. Abstract. An acoustic resonator with shape deformation has been ...

Feshbach shape resonance for high Tc superconductivity in superlattices of nanotubes

International Nuclear Information System (INIS)

Bianconi, Antonio

2006-01-01

The case of a Feshbach shape resonance in the pairing mechanism for high T c superconductivity in a crystalline lattice of doped metallic nanotubes is described. The superlattice of doped metallic nanotubes provides a superconductor with a strongly asymmetric gap. The disparity and different spatial locations of the wave functions of electrons in different subbands at the Fermi level should suppress the single electron impurity interband scattering giving multiband superconductivity in the clean limit. The Feshbach resonances will arise from the component single-particle wave functions out of which the electron pair wave function is constructed: pairs of wave functions which are time inverse of each other. The Feshbach shape resonance increases the critical temperature by tuning the chemical potential at the Lifshitz electronic topological transition (ETT) where the Fermi surface of one of the bands changes from the one dimensional (1D) to the two dimensional (2D) topology (1D/2D ETT). (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Method of shaping fields of controlled extension in a resonator with a large electrical length

International Nuclear Information System (INIS)

Bomko, V.A.; Rudiak, B.I.

A method is discussed for controlling the energy of particles accelerated in a linear accelerator consisting of a volume resonator with drift tubes. Results are described for experimental studies of problems with field shaping of controlled extension of fields in an accelerating structure having drift tubes and a large electrical length. The possibility of shaping the field in a resonator using a stabilizing system of the ''antipode'' type is considered

A new design of dielectric elastomer membrane resonator with tunable resonant frequencies and mode shapes

Science.gov (United States)

Li, Yunlong; Oh, Inkyu; Chen, Jiehao; Hu, Yuhang

2018-06-01

Conventional membrane resonators are bulky, and once the geometries and materials are fixed in the fabricated device, the resonators’ characteristics are fixed. In this work, we introduce the active membrane, dielectric elastomer (DE), into the resonator design. Attaching a stiffer passive membrane onto the active DE membrane forms a two-layer system, which generates an out-of-plane deformation when the DE is actuated through a DC voltage applied across the thickness of the DE membrane. When an AC voltage is applied, the two-layer system can generate an out-of-plane oscillation which enables its use as membrane resonators. Both experiments and simulations are carried out to study the dynamic characteristics of the system. The resonant frequencies and mode shapes of the resonator can be tuned through the passive layer properties such as the modulus, thickness, density, and size. The effective stiffness of the DE film changes as the magnitude of the voltage applied on the film changes, which provides an active way to tune the dynamic characteristics of the two-layer resonator even after the device is set. The system is also light weight, low cost, and easy to fabricate, and has great potential in many engineering applications.

Research on Bell-Shaped Vibratory Angular Rate Gyro’s Character of Resonator

Directory of Open Access Journals (Sweden)

Hong Liu

2013-04-01

Full Text Available Bell-shaped vibratory angular rate gyro (abbreviated as BVG is a new type Coriolis vibratory gyro that was inspired by Chinese traditional clocks. The resonator fuses based on a variable thickness axisymmetric multicurved surface shell. Its characteristics can directly influence the performance of BVG. The BVG structure not only has capabilities of bearing high overload, high impact and, compared with the tuning fork, vibrating beam, shell and a comb structure, but also a higher frequency to overcome the influence of the disturbance of the exterior environment than the same sized hemispherical resonator gyroscope (HRG and the traditional cylinder vibratory gyroscope. It can be widely applied in high dynamic low precision angular rate measurement occasions. The main work is as follows: the issue mainly analyzes the structure and basic principle, and investigates the bell-shaped resonator’s mathematical model. The reasonable structural parameters are obtained from finite element analysis and an intelligent platform. Using the current solid vibration gyro theory analyzes the structural characteristics and principles of BVG. The bell-shaped resonator is simplified as a paraboloid of the revolution mechanical model, which has a fixed closed end and a free opened end. It obtains the natural frequency and vibration modes based on the theory of elasticity. The structural parameters are obtained from the orthogonal method by the research on the structural parameters of the resonator analysis. It obtains the modal analysis, stress analysis and impact analysis with the chosen parameters. Finally, using the turntable experiment verifies the gyro effect of the BVG.

Shape of the Hα emission line in non resonant charge exchange in hydrogen plasmas

International Nuclear Information System (INIS)

Susino Bueno, A.; Zurro Hernandez, B.

1977-01-01

The Hα line shape emitted from a maxwellian hydrogen plasma and produced by non resonant change exchange has been calculated. Its explicit shape depends on the ion temperature, on background neutral energy and on the relative shape of the collision cross section. A comparison between theoretical and experimental shapes of the Hα line is carried out to check the model and to deduce the ion plasma temperature. (author) [es

Experimental verification of the line-shape distortion in resonance Auger spectra

International Nuclear Information System (INIS)

Aksela, S.; Kukk, E.; Aksela, H.; Svensson, S.

1995-01-01

When the mean excitation energy and the width of a broad photon band are varied the Kr 3d 5/2 -1 5p→4p -2 5p resonance Auger electron lines show strong asymmetry and their average kinetic energies shift. Even extra peaks appear. Our results demonstrate experimentally, for the first time, that the incident photon energy distribution has very crucial importance on the resonance Auger line shape and thus on the reliable data analysis of complicated Auger spectra

Shape resonance in K-shell photodetachment from C-

International Nuclear Information System (INIS)

Walter, C. W.; Gibson, N. D.; Bilodeau, R. C.; Berrah, N.; Bozek, J. D.; Ackerman, G. D.; Aguilar, A.

2006-01-01

The core-excited (1s2s 2 2p 4 4 P) negative ion shape resonance of C - near 281.7 eV has been investigated using the merged ion beam--photon beam photodetachment technique on the Advanced Light Source beamline 10.0.1. C + ions formed by double detachment were detected as a function of photon energy. Higher resolution spectra yield more precise values for the energy and width of the resonance than our previous measurements [N. D. Gibson et al., Phys. Rev. A 67, 030703(R) (2003)]. The absolute cross section for double detachment from C - following 1s photoexcitation is measured for the first time and the spectrum is compared to previous theoretical calculations. These measurements also provide information on the lowest core-excited state of neutral carbon (1s2s 2 2p 3 5 S)

Morphology Of A Hot Prominence Cavity Observed with Hinode/XRT and SDO/AIA

Science.gov (United States)

Weber, Mark A.; Reeves, K. K.; Gibson, S. E.; Kucera, T. A.

2012-01-01

Prominence cavities appear as circularly shaped voids in coronal emission over polarity inversion lines where a prominence channel is straddling the solar limb. The presence of chromospheric material suspended at coronal altitudes is a common but not necessary feature within these cavities. These voids are observed to change shape as a prominence feature rotates around the limb. We use a morphological model projected in cross-sections to fit the cavity emission in Hinode/XRT passbands, and then apply temperature diagnostics to XRT and SDO/AIA data to investigate the thermal structure. We find significant evidence that the prominence cavity is hotter than the corona immediately outside the cavity boundary. This investigation follows upon "Thermal Properties of A Solar Coronal Cavity Observed with the X-ray Telescope on Hinode" by Reeves et al., 2012, ApJ, in press.

An unusual π* shape resonance in the near-threshold photoionization of S1 para-difluorobenzene

Science.gov (United States)

Bellm, Susan M.; Davies, Julia A.; Whiteside, Paul T.; Guo, Jingwei; Powis, Ivan; Reid, Katharine L.

2005-06-01

Previously reported dramatic changes in photoelectron angular distributions (PADs) as a function of photoelectron kinetic energy following the ionization of S1p-difluorobenzene are shown to be explained by a shape resonance in the b2g symmetry continuum. The characteristics of this resonance are clearly demonstrated by a theoretical multiple-scattering treatment of the photoionization dynamics. New experimental data are presented which demonstrate an apparent insensitivity of the PADs to both vibrational motion and prepared molecular alignment, however, the calculations suggest that strong alignment effects may nevertheless be recognized in the detail of the comparison with experimental data. The apparent, but unexpected, indifference to vibrational excitation is rationalized by considering the nature of the resonance. The correlation of this shape resonance in the continuum with a virtual π* antibonding orbital is considered. Because this orbital is characteristic of the benzene ring, the existence of similar resonances in related substituted benzenes is discussed.

Mutual Coupling Reduction of E-Shaped MIMO Antenna with Matrix of C-Shaped Resonators

Directory of Open Access Journals (Sweden)

Raghad Ghalib Saadallah Alsultan

2018-01-01

Full Text Available E-shaped multiple-input-multiple-output (MIMO microstrip antenna systems operating in WLAN and WiMAX bands (between 5 and 7.5 GHz are proposed with enhanced isolation features. The systems are comprised of two antennas that are placed parallel and orthogonal to each other, respectively. According to the simulation results, the operating frequency of the MIMO antenna system is 6.3 GHz, and mutual coupling is below −18 dB in a parallel arrangement, whereas they are 6.4 GHz and −25 dB, respectively, in the orthogonal arrangement. The 2 × 3 matrix of C-shaped resonator (CSR is proposed and placed between the antenna elements over the substrate, to reduce the mutual coupling and enhance the isolation between the antennas. More than 30 dB isolation between the array elements is achieved at the resonant frequency for both of the configurations. The essential parameters of the MIMO array such as mutual coupling, surface current distribution, envelop correlation coefficient (ECC, diversity gain (DG, and the total efficiency have been simulated to verify the reliability and the validity of the MIMO system in both parallel and orthogonal configurations. The experimental results are also provided and compared for the mutual coupling with simulated results. An adequate match between the measured and simulated results is achieved.

Effect of the Potential Shape on the Stochastic Resonance Processes

Science.gov (United States)

Kenmoé, G. Djuidjé; Ngouongo, Y. J. Wadop; Kofané, T. C.

2015-10-01

The stochastic resonance (SR) induced by periodic signal and white noises in a periodic nonsinusoidal potential is investigated. This phenomenon is studied as a function of the friction coefficient as well as the shape of the potential. It is done through an investigation of the hysteresis loop area which is equivalent to the input energy lost by the system to the environment per period of the external force. SR is evident in some range of the shape parameter of the potential, but cannot be observed in the other range. Specially, variation of the shape potential affects significantly and not trivially the heigh of the potential barrier in the Kramers rate as well as the occurrence of SR. The finding results show crucial dependence of the temperature of occurrence of SR on the shape of the potential. It is noted that the maximum of the input energy generally decreases when the friction coefficient is increased.

Two Categories of Apparent Tornado-like Prominences

Science.gov (United States)

Martin, Sara F.; Venkataramanasastry, Aparna

2014-06-01

Two categories of solar prominences have been described in the literature as having a pattern of mass motions and/or a shape similar to terrestrial tornados. We first identify the two categories associated with prominences in the historic literature and then show that counterparts do exist for both in recent literature but one has not been called a tornado prominence. One category described as being similar to tornados is associated with the barbs of quiescent filaments but barbs appear to have rotational motion only under special conditions. H alpha Doppler observations from Helio Research confirm that this category is an illusion in our mind’s eye resulting from counterstreaming in the large barbs of quiescent filaments. The second category is a special case of rotational motion occurring during the early stages of some erupting prominences, in recent years called the roll effect in erupting prominences. In these cases, the eruption begins with the sideways rolling of the top of a prominence. As the eruption proceeds the rolling motion propagates down one leg or both legs of an erupting prominence depending on whether the eruption is asymmetric or symmetric respectively. As an asymmetric eruption proceeds, the longer lasting leg becomes nearly vertical and has true rotational motion. If only this phase of the eruption was observed, as in the historic cases, it was called a tornado prominence and spectra recorded in these cases provide proof of the rotational motion. When one observes an entire eruption which exhibits the rolling motion, as accomplished at Helio Research, the similarity to a tornado is lost because the event as a whole has quite a different nature and the analogy to a terrestrial tornado not longer appears suitable or helpful in understanding the observed and deduced physical processes. Our conclusion is that there are no solar prominences with motions that are usefully described as tornado or tornado-like events aside from the fun of observing

Morphology and Dynamics of Solar Prominences from 3D MHD Simulations

Science.gov (United States)

Terradas, J.; Soler, R.; Luna, M.; Oliver, R.; Ballester, J. L.

2015-01-01

In this paper we present a numerical study of the time evolution of solar prominences embedded in sheared magnetic arcades. The prominence is represented by a density enhancement in a background-stratified atmosphere and is connected to the photosphere through the magnetic field. By solving the ideal magnetohydrodynamic equations in three dimensions, we study the dynamics for a range of parameters representative of real prominences. Depending on the parameters considered, we find prominences that are suspended above the photosphere, i.e., detached prominences, but also configurations resembling curtain or hedgerow prominences whose material continuously connects to the photosphere. The plasma-β is an important parameter that determines the shape of the structure. In many cases magnetic Rayleigh-Taylor instabilities and oscillatory phenomena develop. Fingers and plumes are generated, affecting the whole prominence body and producing vertical structures in an essentially horizontal magnetic field. However, magnetic shear is able to reduce or even to suppress this instability.

MORPHOLOGY AND DYNAMICS OF SOLAR PROMINENCES FROM 3D MHD SIMULATIONS

Energy Technology Data Exchange (ETDEWEB)

Terradas, J.; Soler, R.; Oliver, R.; Ballester, J. L. [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Luna, M., E-mail: jaume.terradas@uib.es [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain)

2015-01-20

In this paper we present a numerical study of the time evolution of solar prominences embedded in sheared magnetic arcades. The prominence is represented by a density enhancement in a background-stratified atmosphere and is connected to the photosphere through the magnetic field. By solving the ideal magnetohydrodynamic equations in three dimensions, we study the dynamics for a range of parameters representative of real prominences. Depending on the parameters considered, we find prominences that are suspended above the photosphere, i.e., detached prominences, but also configurations resembling curtain or hedgerow prominences whose material continuously connects to the photosphere. The plasma-β is an important parameter that determines the shape of the structure. In many cases magnetic Rayleigh-Taylor instabilities and oscillatory phenomena develop. Fingers and plumes are generated, affecting the whole prominence body and producing vertical structures in an essentially horizontal magnetic field. However, magnetic shear is able to reduce or even to suppress this instability.

A Near-Threshold Shape Resonance in the Valence-Shell Photoabsorption of Linear Alkynes

Energy Technology Data Exchange (ETDEWEB)

Jacovella, U.; Holland, D. M. P.; Boyé-Péronne, S.; Gans, Bérenger; de Oliveira, N.; Ito, K.; Joyeux, D.; Archer, L. E.; Lucchese, R. R.; Xu, Hong; Pratt, S. T.

2015-12-17

The room-temperature photoabsorption spectra of a number of linear alkynes with internal triple bonds (e.g., 2-butyne, 2-pentyne, and 2- and 3-hexyne) show similar resonances just above the lowest ionization threshold of the neutral molecules. These features result in a substantial enhancement of the photoabsorption cross sections relative to the cross sections of alkynes with terminal triple bonds (e.g., propyne, 1-butyne, 1-pentyne,...). Based on earlier work on 2-butyne [Xu et al., J. Chem. Phys. 2012, 136, 154303], these features are assigned to excitation from the neutral highest occupied molecular orbital (HOMO) to a shape resonance with g (l = 4) character and approximate pi symmetry. This generic behavior results from the similarity of the HOMOs in all internal alkynes, as well as the similarity of the corresponding g pi virtual orbital in the continuum. Theoretical calculations of the absorption spectrum above the ionization threshold for the 2- and 3-alkynes show the presence of a shape resonance when the coupling between the two degenerate or nearly degenerate pi channels is included, with a dominant contribution from l = 4. These calculations thus confirm the qualitative arguments for the importance of the l = 4 continuum near threshold for internal alkynes, which should also apply to other linear internal alkynes and alkynyl radicals. The 1-alkynes do not have such high partial waves present in the shape resonance. The lower l partial waves in these systems are consistent with the broader features observed in the corresponding spectra.

TORNADO-LIKE EVOLUTION OF A KINK-UNSTABLE SOLAR PROMINENCE

Energy Technology Data Exchange (ETDEWEB)

Wang, Wensi; Liu, Rui; Wang, Yuming, E-mail: rliu@ustc.edu.cn [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei 230026 (China)

2017-01-01

We report on the tornado-like evolution of a quiescent prominence on 2014 November 1. The eastern section of the prominence first rose slowly, transforming into an arch-shaped structure as high as ∼150 Mm above the limb; the arch then writhed moderately in a left-handed sense, while the original dark prominence material emitted in the Fe ix 171 Å passband, and a braided structure appeared at the eastern edge of the warped arch. The unraveling of the braided structure was associated with a transient brightening in the EUV and apparently contributed to the formation of a curtain-like structure (CLS). The CLS consisted of myriad thread-like loops rotating counterclockwise about the vertical if viewed from above. Heated prominence material was observed to slide along these loops and land outside the filament channel. The tornado eventually disintegrated and the remaining material flew along a left-handed helical path constituting approximately a full turn, as corroborated through stereoscopic reconstruction, into the cavity of the stable, western section of the prominence. We suggest that the tornado-like evolution of the prominence was governed by the helical kink instability, and that the CLS formed through magnetic reconnections between the prominence field and the overlying coronal field.

Scalable nanofabrication of U-shaped nanowire resonators with tunable optical magnetism.

Science.gov (United States)

Zhou, Fan; Wang, Chen; Dong, Biqin; Chen, Xiangfan; Zhang, Zhen; Sun, Cheng

2016-03-21

Split ring resonators have been studied extensively in reconstituting the diminishing magnetism at high electromagnetic frequencies in nature. However, breakdown in the linear scaling of artificial magnetism is found to occur at the near-infrared frequency mainly due to the increasing contribution of self-inductance while reducing dimensions of the resonators. Although alternative designs have enabled artificial magnetism at optical frequencies, their sophisticated configurations and fabrication procedures do not lend themselves to easy implementation. Here, we report scalable nanofabrication of U-shaped nanowire resonators (UNWRs) using the high-throughput nanotransfer printing method. By providing ample area for conducting oscillating electric current, UNWRs overcome the saturation of the geometric scaling of the artificial magnetism. We experimentally demonstrated coarse and fine tuning of LC resonances over a wide wavelength range from 748 nm to 1600 nm. The added flexibility in transferring to other substrates makes UNWR a versatile building block for creating functional metamaterials in three dimensions.

Far from Equilibrium Percolation, Stochastic and Shape Resonances in the Physics of Life

Directory of Open Access Journals (Sweden)

Antonio Bianconi

2011-10-01

Full Text Available Key physical concepts, relevant for the cross-fertilization between condensed matter physics and the physics of life seen as a collective phenomenon in a system out-of-equilibrium, are discussed. The onset of life can be driven by: (a the critical fluctuations at the protonic percolation threshold in membrane transport; (b the stochastic resonance in biological systems, a mechanism that can exploit external and self-generated noise in order to gain efficiency in signal processing; and (c the shape resonance (or Fano resonance or Feshbach resonance in the association and dissociation processes of bio-molecules (a quantum mechanism that could play a key role to establish a macroscopic quantum coherence in the cell.

Synthesis of Au@Ag core-shell nanocubes containing varying shaped cores and their localized surface plasmon resonances.

Science.gov (United States)

Gong, Jianxiao; Zhou, Fei; Li, Zhiyuan; Tang, Zhiyong

2012-06-19

We have synthesized Au@Ag core-shell nanocubes containing Au cores with varying shapes and sizes through modified seed-mediated methods. Bromide ions are found to be crucial in the epitaxial growth of Ag atoms onto Au cores and in the formation of the shell's cubic shape. The Au@Ag core-shell nanocubes exhibit very abundant and distinct localized surface plasmon resonance (LSPR) properties, which are core-shape and size-dependent. With the help of theoretical calculation, the physical origin and the resonance mode profile of each LSPR peak are identified and studied. The core-shell nanocrystals with varying shaped cores offer a new rich category for LSPR control through the plasmonic coupling effect between core and shell materials.

Time-dependent shape fluctuations and the giant dipole resonance in hot nuclei: Realistic calculations

International Nuclear Information System (INIS)

Alhassid, Y.; Bush, B.; Yale Univ., New Haven, CT

1990-01-01

The effects of time-dependent shape fluctuations on the giant dipole resonance (GDR) in hot rotating nuclei are investigated. Using the framework of the Landau theory of shape transitions we develop a realistic macroscopic stochastic model to describe the quadrupole time-dependent shape fluctuations and their coupling to the dipole degrees of freedom. In the adiabatic limit the theory reduces to a previous adiabatic theory of static fluctuations in which the GDR cross section is calculated by averaging over the equilibrium distribution with the unitary invariant metric. Nonadiabatic effects are investigated in this model and found to cause structural changes in the resonance cross section and motional narrowing. Comparisons with experimental data are made and deviations from the adiabatic calculations can be explained. In these cases it is possible to determine from the data the damping of the quadrupole motion at finite temperature. (orig.)

Multi-resonant wideband energy harvester based on a folded asymmetric M-shaped cantilever

Energy Technology Data Exchange (ETDEWEB)

Wu, Meng; Mao, Haiyang; Li, Zhigang; Liu, Ruiwen; Ming, Anjie [Key laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academic of Sciences, Beijing 100029 (China); Ou, Yi; Ou, Wen [Key laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academic of Sciences, Beijing 100029 (China); Smart Sensor Engineering Center, Jiangsu R& D Center for Internet of Things, Wuxi 214315 (China)

2015-07-15

This article reports a compact wideband piezoelectric vibration energy harvester consisting of three proof masses and an asymmetric M-shaped cantilever. The M-shaped beam comprises a main beam and two folded and dimension varied auxiliary beams interconnected through the proof mass at the end of the main cantilever. Such an arrangement constitutes a three degree-of-freedom vibrating body, which can tune the resonant frequencies of its first three orders close enough to obtain a utility wide bandwidth. The finite element simulation results and the experimental results are well matched. The operation bandwidth comprises three adjacent voltage peaks on account of the frequency interval shortening mechanism. The result shows that the proposed piezoelectric energy harvester could be efficient and adaptive in practical vibration circumstance based on multiple resonant modes.

Multi-resonant wideband energy harvester based on a folded asymmetric M-shaped cantilever

International Nuclear Information System (INIS)

Wu, Meng; Mao, Haiyang; Li, Zhigang; Liu, Ruiwen; Ming, Anjie; Ou, Yi; Ou, Wen

2015-01-01

This article reports a compact wideband piezoelectric vibration energy harvester consisting of three proof masses and an asymmetric M-shaped cantilever. The M-shaped beam comprises a main beam and two folded and dimension varied auxiliary beams interconnected through the proof mass at the end of the main cantilever. Such an arrangement constitutes a three degree-of-freedom vibrating body, which can tune the resonant frequencies of its first three orders close enough to obtain a utility wide bandwidth. The finite element simulation results and the experimental results are well matched. The operation bandwidth comprises three adjacent voltage peaks on account of the frequency interval shortening mechanism. The result shows that the proposed piezoelectric energy harvester could be efficient and adaptive in practical vibration circumstance based on multiple resonant modes

Magnetohydrodynamic interpretation of the motion of prominences

International Nuclear Information System (INIS)

Sakurai, Takashi

1976-01-01

We study three types of prominence eruptions, which we will call the arch type, the loop type, and the gigantic arch type, respectively, from their shapes. If we regard the prominence as a magnetic flux tube, the onset of its ascending motion can be interpreted as the motion due to the screw-mode instability, which is the most unstable mode of instabilities of a magnetofluid column (pinch). The growth rate of this mode is evaluated and is shown to be consistent with the time scale of the initial stage of the eruption. In order to study the nonlinear stage of the instability, we propose a method of numerical calculation based on a variational technique known as Ritz's method. The result shows that the characteristic motion of the arch-, loop-, and gigantic arch-type eruptions may be reproduced by perturbing a model sequence with decreasing pitch angles of the unperturbed helical magnetic field lines. This conclusion seems to be supported by the pitch angles of observed threads in each type of prominence and also by the fact that the observed time profiles of the rising velocity of the prominences of each type agree well with those predicted from model calculations. (auth.)

The giant resonance and the shape of hot nuclei

Energy Technology Data Exchange (ETDEWEB)

Bracco, A; Camera, F; Million, B; Pignanelli, M [Milan Univ. (Italy). Ist. di Fisica; Gaardhoje, J J; Maj, A; Atac, A [Niels Bohr Inst., Copenhagen (Denmark)

1992-08-01

The gamma decay of the giant dipole resonance is a sensitive tool for investigating how nuclear shape changes with spin and excitation energy, but the information is coded in a subtle way, inasmuch as the shape and orientation of nuclei at finite temperature display large fluctuations. At the time of the conference, the three systems {sup 109-110}Sn, {sup 161-162}Yb and {sup 165-167}Er had recently been studied on the HECTOR spectrometer. The Sn nuclei are spherical in their ground states, and are expected to become oblate under the stress of rotation. The Yb and Er nuclei are prolate, and are expected to become first spherical, then oblate. While the patterns of the measured angular anisotropies are consistent with this general picture, many questions still remain open. 3 refs., 1 tab., 3 figs.

The static and dynamic behavior of MEMS arch resonators near veering and the impact of initial shapes

KAUST Repository

Hajjaj, Amal Z.

2017-07-19

We investigate experimentally and analytically the effect of initial shapes, arc and cosine wave, on the static and dynamic behavior of microelectromechanical systems (MEMS) arch resonators. We show that by carefully choosing the geometrical parameters and the initial shape of the arch, the veering phenomenon (avoided-crossing) among the first two symmetric modes can be strongly activated. To demonstrate this, we study electrothermally tuned and electrostatically driven initially curved MEMS resonators. Upon changing the electrothermal voltage, we demonstrate high frequency tunability of arc resonators compared to the cosine-configuration resonators for the first and third resonance frequencies. For arc beams, we show that the first resonance frequency increases up to twice its fundamental value and the third resonance frequency decreases until getting very close to the first resonance frequency triggering the veering phenomenon. Around the veering regime, we study experimentally and analytically the dynamic behavior of the arc beam for different electrostatic loads. The analytical study is based on a reduced order model of a nonlinear Euler–Bernoulli shallow arch beam model. The veering phenomenon is also confirmed through a finite-element multi-physics and nonlinear model.

Resonant infiltration of an opal: Reflection line shape and contribution from in-depth regions.

Science.gov (United States)

Maurin, Isabelle; Bloch, Daniel

2015-06-21

We analyze the resonant variation of the optical reflection on an infiltrated artificial opal made of transparent nanospheres. The resonant infiltration is considered as a perturbation in the frame of a previously described one-dimensional model based upon a stratified effective index. We show that for a thin slice of resonant medium, the resonant response oscillates with the position of this slice. We derive that for adequate conditions of incidence angle, this spatially oscillating behavior matches the geometrical periodicity of the opal and hence the related density of resonant infiltration. Close to these matching conditions, the resonant response of the global infiltration varies sharply in amplitude and shape with the incidence angle and polarization. The corresponding resonant reflection originates from a rather deep infiltration, up to several wavelengths or layers of spheres. Finally, we discuss the relationship between the present predictions and our previous observations on an opal infiltrated with a resonant vapor.

Electrode-shaping for the excitation and detection of permitted arbitrary modes in arbitrary geometries in piezoelectric resonators.

Science.gov (United States)

Pulskamp, Jeffrey S; Bedair, Sarah S; Polcawich, Ronald G; Smith, Gabriel L; Martin, Joel; Power, Brian; Bhave, Sunil A

2012-05-01

This paper reports theoretical analysis and experimental results on a numerical electrode shaping design technique that permits the excitation of arbitrary modes in arbitrary geometries for piezoelectric resonators, for those modes permitted to exist by the nonzero piezoelectric coefficients and electrode configuration. The technique directly determines optimal electrode shapes by assessing the local suitability of excitation and detection electrode placement on two-port resonators without the need for iterative numerical techniques. The technique is demonstrated in 61 different electrode designs in lead zirconate titanate (PZT) thin film on silicon RF micro electro-mechanical system (MEMS) plate, beam, ring, and disc resonators for out-of-plane flexural and various contour modes up to 200 MHz. The average squared effective electromechanical coupling factor for the designs was 0.54%, approximately equivalent to the theoretical maximum value of 0.53% for a fully electroded length-extensional mode beam resonator comprised of the same composite. The average improvement in S(21) for the electrode-shaped designs was 14.6 dB with a maximum improvement of 44.3 dB. Through this piezoelectric electrodeshaping technique, 95% of the designs showed a reduction in insertion loss.

Shape resonances in low-energy-electron collisions with halopyrimidines

Energy Technology Data Exchange (ETDEWEB)

Barbosa, Alessandra Souza; Bettega, Márcio H. F., E-mail: bettega@fisica.ufpr.br [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-990 Curitiba, Paraná (Brazil)

2013-12-07

We report calculated cross sections for elastic collisions of low-energy electrons with halopyrimidines, namely, 2-chloro, 2-bromo, and 5-bromopyrimidine. We employed the Schwinger multichannel method with pseudopotentials to compute the cross sections in the static-exchange and static-exchange plus polarization levels of approximation for energies up to 10 eV. We found four shape resonances for each molecule: three of π* nature localized on the ring and one of σ* nature localized along the carbon–halogen bond. We compared the calculated positions of the resonances with the electron transmission spectroscopy data measured by Modelli et al. [J. Phys. Chem. A 115, 10775 (2011)]. In general the agreement between theory and experiment is good. In particular, our results show the existence of a π* temporary anion state of A{sub 2} symmetry for all three halopyrimidines, in agreement with the dissociative electron attachment spectra also reported by Modelli et al. [J. Phys. Chem. A 115, 10775 (2011)].

Line shapes and time dynamics of the Förster resonances between two Rydberg atoms in a time-varying electric field

KAUST Repository

Yakshina, E. A.

2016-10-21

The observation of the Stark-tuned Förster resonances between Rydberg atoms excited by narrowband cw laser radiation requires usage of a Stark-switching technique in order to excite the atoms first in a fixed electric field and then to induce the interactions in a varied electric field, which is scanned across the Förster resonance. In our experiments with a few cold Rb Rydberg atoms, we have found that the transients at the edges of the electric pulses strongly affect the line shapes of the Förster resonances, since the population transfer at the resonances occurs on a time scale of ∼100 ns, which is comparable with the duration of the transients. For example, a short-term ringing at a certain frequency causes additional radio-frequency-assisted Förster resonances, while nonsharp edges lead to asymmetry. The intentional application of the radio-frequency field induces transitions between collective states, whose line shape depends on the interaction strengths and time. Spatial averaging over the atom positions in a single interaction volume yields a cusped line shape of the Förster resonance. We present a detailed experimental and theoretical analysis of the line shape and time dynamics of the Stark-tuned Förster resonances Rb(nP3/2)+Rb(nP3/2)→Rb(nS1/2)+Rb([n+1]S1/2) for two Rb Rydberg atoms interacting in a time-varying electric field.

Line shapes and time dynamics of the Förster resonances between two Rydberg atoms in a time-varying electric field

KAUST Repository

Yakshina, E. A.; Tretyakov, D. B.; Beterov, I. I.; Entin, V. M.; Andreeva, C.; Cinins, A.; Markovski, A.; Iftikhar, Z.; Ekers, Aigars; Ryabtsev, I. I.

2016-01-01

The observation of the Stark-tuned Förster resonances between Rydberg atoms excited by narrowband cw laser radiation requires usage of a Stark-switching technique in order to excite the atoms first in a fixed electric field and then to induce the interactions in a varied electric field, which is scanned across the Förster resonance. In our experiments with a few cold Rb Rydberg atoms, we have found that the transients at the edges of the electric pulses strongly affect the line shapes of the Förster resonances, since the population transfer at the resonances occurs on a time scale of ∼100 ns, which is comparable with the duration of the transients. For example, a short-term ringing at a certain frequency causes additional radio-frequency-assisted Förster resonances, while nonsharp edges lead to asymmetry. The intentional application of the radio-frequency field induces transitions between collective states, whose line shape depends on the interaction strengths and time. Spatial averaging over the atom positions in a single interaction volume yields a cusped line shape of the Förster resonance. We present a detailed experimental and theoretical analysis of the line shape and time dynamics of the Stark-tuned Förster resonances Rb(nP3/2)+Rb(nP3/2)→Rb(nS1/2)+Rb([n+1]S1/2) for two Rb Rydberg atoms interacting in a time-varying electric field.

Solar prominences

CERN Document Server

Engvold, Oddbjørn

2015-01-01

This volume presents the latest research results on solar prominences, including new developments on e.g. chirality, fine structure, magnetism, diagnostic tools and relevant solar plasma physics. In 1875 solar prominences, as seen out of the solar limb, were described by P.A. Secchi in his book Le Soleil as "gigantic pink or peach-flower coloured flames". The development of spectroscopy, coronagraphy and polarimetry brought tremendous observational advances in the twentieth century. The authors present and discuss exciting new challenges (resulting from observations made by space and ground-based telescopes in the 1990s and the first decade of the 21st century) concerning the diagnostics of prominences, their formation, their life time and their eruption along with their impact in the heliosphere (including the Earth). The book starts with a general introduction of the prominence “object” with some historical background on observations and instrumentation. In the next chapter, the various forms of promine...

Cylindrical prominences and the magnetic influence of the photospheric boundary

International Nuclear Information System (INIS)

Lerche, I.; Chicago Univ., IL; Low, B.C.

1980-01-01

We construct exact, non-linear, solutions for an horizontal, cylindrical, current-carrying, prominence supported against solar gravity by the action of a Lorentz force. The solutions incorporate the photosphere boundary condition, proposed by van Tend and Kuperus (1978), and analyzed by them for line filaments. Our solutions have finite radius for the prominence material and, as well as satisfying the equations of magnetostatic equilibrium, they allow for the continuity of gas pressure, and of the normal and tangential components of magnetic field across the circular prominence boundary. We show that an infinity of solutions is possible and we illustrate the basic behavior by investigation of a special case. We also give a prescription for constructing equilibrium fields for any horizontal prominence with arbitrary cross-section and with an arbitrary external magnetic field. The prescription is ideally suited for numerical codes and we suggest that both the equilibrium of such shapes can easily be accomplished numerically together with their evolutionary history. (orig.)

Neural - levelset shape detection segmentation of brain tumors in dynamic susceptibility contrast enhanced and diffusion weighted magnetic resonance images

International Nuclear Information System (INIS)

Vijayakumar, C.; Bhargava, Sunil; Gharpure, Damayanti Chandrashekhar

2008-01-01

A novel Neuro - level set shape detection algorithm is proposed and evaluated for segmentation and grading of brain tumours. The algorithm evaluates vascular and cellular information provided by dynamic contrast susceptibility magnetic resonance images and apparent diffusion coefficient maps. The proposed neural shape detection algorithm is based on the levels at algorithm (shape detection algorithm) and utilizes a neural block to provide the speed image for the level set methods. In this study, two different architectures of level set method have been implemented and their results are compared. The results show that the proposed Neuro-shape detection performs better in differentiating the tumor, edema, necrosis in reconstructed images of perfusion and diffusion weighted magnetic resonance images. (author)

3-D Printed Fabry–Pérot Resonator Antenna with Paraboloid-Shape Superstrate for Wide Gain Bandwidth

Directory of Open Access Journals (Sweden)

Qiang Chen

2017-11-01

Full Text Available A three-dimensional (3-D printed Fabry–Pérot resonator antenna (FPRA, which designed with a paraboloid-shape superstrate for wide gain bandwidth is proposed. In comparison with the commonly-adopted planar superstrate, the paraboloid-shape superstrate is able to provide multiple resonant heights and thus satisfy the resonant condition of the FPRA in a wide frequency band. A FPRA working at 6 GHz is designed, fabricated, and tested. Considering the fabrication difficulty caused by its complex structure, the prototype antenna was fabricated by using the 3-D printing technology, i.e., all components of the prototype antenna were printed with photopolymer resin and then treated by the surface metallization process. Measurement results agree well with the simulation results, and show the 3-D printed FPRA has a |S11| < −10 dB impedance bandwidth of 12.4%, and a gain of 16.8 dBi at its working frequency of 6 GHz. Moreover, in comparison with the planar superstrate adopted in traditional FPRAs, the paraboloid-shape superstrate of the proposed FPRA significantly improves the 3-dB gain bandwidth from 6% to 22.2%.

Nano-polarization-converter based on magnetic plasmon resonance excitation in an L-shaped slot antenna.

Science.gov (United States)

Yang, Jing; Zhang, Jiasen

2013-04-08

We propose a nano-polarization-converter made of a resonant L-shaped slot antenna in a gold film and study its optical properties using the finite-difference time-domain method. Phase retardation between the fast and slow axes of the nano-polarization-converter originates from the simultaneous excitation of both single-surface first-order magnetic plasmon resonance mode and second-order magnetic plasmon resonance mode at the working wavelength. By adjusting the size of the slot antenna, which is still much smaller than the wavelength, the working wavelength can be tuned within a large wavelength range.

EUV lines observed with EIS/Hinode in a solar prominence

Science.gov (United States)

Labrosse, N.; Schmieder, B.; Heinzel, P.; Watanabe, T.

2011-07-01

Context. During a multi-wavelength observation campaign with Hinode and ground-based instruments, a solar prominence was observed for three consecutive days as it crossed the western limb of the Sun in April 2007. Aims: We report on observations obtained on 26 April 2007 using EIS (Extreme ultraviolet Imaging Spectrometer) on Hinode. They are analysed to provide a qualitative diagnostic of the plasma in different parts of the prominence. Methods: After correcting for instrumental effects, the rasters at different wavelengths are presented. Several regions within the same prominence are identified for further analysis. Selected profiles for lines with formation temperatures between log (T) = 4.7 and log (T) = 6.3, as well as their integrated intensities, are given. The profiles of coronal, transition region, and He ii lines are discussed. We pay special attention to the He ii line, which is blended with coronal lines. Results: Some quantitative results are obtained by analysing the line profiles. They confirm that depression in EUV lines can be interpreted in terms of two mechanisms: absorption of coronal radiation by the hydrogen and neutral helium resonance continua, and emissivity blocking. We present estimates of the He ii line integrated intensity in different parts of the prominence according to different scenarios for the relative contribution of absorption and emissivity blocking to the coronal lines blended with the He ii line. We estimate the contribution of the He ii 256.32 Å line to the He ii raster image to vary between ~44% and 70% of the raster's total intensity in the prominence according to the different models used to take into account the blending coronal lines. The inferred integrated intensities of the He ii 256 Å line are consistent with the theoretical intensities obtained with previous 1D non-LTE radiative transfer calculations, yielding a preliminary estimate of the central temperature of 8700 K, a central pressure of 0.33 dyn cm-2, and a

Shape resonances and the excitation of helium autoionising states by electrons in the 57-66 eV region

International Nuclear Information System (INIS)

Burgt, P.J.M. van der; Eck, J. van; Heideman, H.G.M.

1986-01-01

Optical excitation functions of singly excited helium states are presented, measured by detecting the yield of emitted photons as a function of the incident electron energy from 56 to 66 eV. Many structures are observed, which are caused by negative-ion resonances and by the decay of autoionising states followed by post-collision interaction. Some of the structures are interpreted as being caused by hitherto unknown shape resonances lying very close to the thresholds of a particular class of autoionising states. As these shape resonances almost exclusively decay to their respective parent (autoionising) states, thereby considerably enhancing the threshold excitation cross sections of these states, they can only be observed via the PCI effect on the excitation functions of (higher lying) singly excited states. Using the recently introduced supermultiplet classification for doubly excited states a selection rule for the near-threshold excitation of doubly excited states by electron impact is deduced from the measurements. Only states with large probabilities in the Wannier region of configuration space (where the two electrons are at nearly equal distances and on opposite sides of the nucleus) are strongly excited. It is pointed out that these states are precisely the states that can support the above mentioned shape resonances at their thresholds. (author)

Experimental investigation of shaping disturbance observer design for motion control of precision mechatronic stages with resonances

Science.gov (United States)

Yang, Jin; Hu, Chuxiong; Zhu, Yu; Wang, Ze; Zhang, Ming

2017-08-01

In this paper, shaping disturbance observer (SDOB) is investigated for precision mechatronic stages with middle-frequency zero/pole type resonance to achieve good motion control performance in practical manufacturing situations. Compared with traditional standard disturbance observer (DOB), in SDOB a pole-zero cancellation based shaping filter is cascaded to the mechatronic stage plant to meet the challenge of motion control performance deterioration caused by actual resonance. Noting that pole-zero cancellation is inevitably imperfect and the controller may even consequently become unstable in practice, frequency domain stability analysis is conducted to find out how each parameter of the shaping filter affects the control stability. Moreover, the robust design criterion of the shaping filter, and the design procedure of SDOB, are both proposed to guide the actual design and facilitate practical implementation. The SDOB with the proposed design criterion is applied to a linear motor driven stage and a voice motor driven stage, respectively. Experimental results consistently validate the effectiveness nature of the proposed SDOB scheme in practical mechatronics motion applications. The proposed SDOB design actually could be an effective unit in the controller design for motion stages of mechanical manufacture equipments.

Modelling and characterization of the roof tile-shaped modes of AlN-based cantilever resonators in liquid media

International Nuclear Information System (INIS)

Ruiz-Díez, V; Hernando-García, J; Toledo, J; Manzaneque, T; Sánchez-Rojas, J L; Kucera, M; Pfusterschmied, G; Schmid, U

2016-01-01

In this work, roof tile-shaped modes of MEMS (micro electro-mechanical systems) cantilever resonators with various geometries and mode orders are analysed. These modes can be efficiently excited by a thin piezoelectric film and a properly designed top electrode. The electrical and optical characterization of the resonators are performed in liquid media and the device performance is evaluated in terms of quality factor, resonant frequency and motional conductance. A quality factor as high as 165 was measured in isopropanol for a cantilever oscillating in the seventh order roof tile-shaped mode at 2 MHz. To support the results of the experimental characterization, a 2D finite element method simulation model is presented and studied. An analytical model for the estimation of the motional conductance was also developed and validated with the experimental measurements. (paper)

Vibrational structures in electron-CO2 scattering below the 2Πu shape resonance

International Nuclear Information System (INIS)

Allan, Michael

2002-01-01

Structures of vibrational origin were discovered in vibrationally inelastic electron-CO 2 cross sections in the energy range 0.4-0.9 eV, well below the 2 Π u shape resonance. They appear in the excitation of higher vibrational levels, in particular the highest members of the Fermi polyads of the type (n, 2m, 0) with n+m=2-4. The lowest two structures, at 0.445 and 0.525 eV, are narrow; higher-lying structures are broader and boomerang-like. The structures are absent when the antisymmetric stretch is co-excited. The structures are interpreted in terms of a wavepacket of the nuclei reflected from a potential surface of the CO 2 - anion in a bent and stretched geometry. A state emerging from the virtual state upon bending and stretching and the state resulting from bending the 2 Π u shape resonance are discussed as possibly being responsible for the structures. (author). Letter-to-the-editor

Dual and tri-band bandpass filters based on novel Π-shaped resonator

Science.gov (United States)

Xiao, Jian-Kang; Zhu, Wen-Jun; Zhao, Wei

2014-05-01

A novel Π-shaped resonator is proposed, and compact dual-band and tri-band bandpass filters that meet IEEE 802.11 application requirements by using the new resonator are designed. The dual-band bandpass filter centres at 2.45 and 5.6 GHz with a simulated passband insertion loss of no more than 0.8 dB, and the tri-band bandpass filter which is got by two-path coupling achieves simulated passband insertion loss of no more than 1.1 dB. The new designs are demonstrated by experiment. The new filters have advantages of simple and compact structures, low passband insertion losses, good frequency selectivity and miniature circuit sizes. All these have prospect to be applied in future wireless communication systems.

Extreme-ultraviolet limb spectra of a prominence observed from SKYLAB

International Nuclear Information System (INIS)

Mariska, J.T.; Doschek, G.A.; Feldman, U.

1979-01-01

Line profiles of extreme ultraviolet emission lines observed in a solar prominence at positions above the white-light limb with the NRL slit spectrograph on Skylab are discussed. Absolute line intensities and full widths at half-maximum are presented for lines formed over the temperature range approx.1 x 10 4 to 2.2 x 10 5 K. The volume emission measures calculated using resonance line intensities are greater than quiet-Sun emission measures at the same height above the limb and indicate a somewhat different distribution of material with temperature in the prominence compared to the quiet-Sun emission measure at +8''. Electron densities in the prominence determined using the calculated emission measures and the intensities of density-sensitive intersystem lines are between the quiet-Sun electron density and half the quiet-Sun electron density. Random mass-motion velocities calculated from the measured full widths at half-maximum show a range of velocities. For T/sub e/> or approx. =4 x 10 4 K, the nonthermal velocity decreases with increasing height in the prominence. For T/sub e/ 4 K, the calculated mass motions are near zero. From the He II 1640 A line profile we derive an average temperature of 27,000 K for the region in which He II is emitted

Formation and support of prominence

International Nuclear Information System (INIS)

Forbes, T.G.

1986-01-01

A short introduction is given to the concepts discussed by the group on the formation and support of prominences. Only quiescent and long-lived active region prominences were considered, since transient prominence phenomena, such as sprays, surges, H alpha flare-loops, and coronal rain, are dynamically distinct from long-lived, prominences. Stable prominences (which are often referred to as filaments when seen against the disk) can be subdivided into three categories, namely active region prominences, quiescent prominences and polar crown prominences. The third category is closely related to the second since a quiescent prominence will eventually evolve into a polar crown prominence if it lasts long enough. The distinction between the first and second categories is not sharp either since intermediates exist here as well (Martin, 1973)

Comparative analysis of magnetic resonance in the polaron pair recombination and the triplet exciton-polaron quenching models

Science.gov (United States)

Mkhitaryan, V. V.; Danilović, D.; Hippola, C.; Raikh, M. E.; Shinar, J.

2018-01-01

We present a comparative theoretical study of magnetic resonance within the polaron pair recombination (PPR) and the triplet exciton-polaron quenching (TPQ) models. Both models have been invoked to interpret the photoluminescence detected magnetic resonance (PLDMR) results in π -conjugated materials and devices. We show that resonance line shapes calculated within the two models differ dramatically in several regards. First, in the PPR model, the line shape exhibits unusual behavior upon increasing the microwave power: it evolves from fully positive at weak power to fully negative at strong power. In contrast, in the TPQ model, the PLDMR is completely positive, showing a monotonic saturation. Second, the two models predict different dependencies of the resonance signal on the photoexcitation power, PL. At low PL, the resonance amplitude Δ I /I is ∝PL within the PPR model, while it is ∝PL2 crossing over to PL3 within the TPQ model. On the physical level, the differences stem from different underlying spin dynamics. Most prominently, a negative resonance within the PPR model has its origin in the microwave-induced spin-Dicke effect, leading to the resonant quenching of photoluminescence. The spin-Dicke effect results from the spin-selective recombination, leading to a highly correlated precession of the on-resonance pair partners under the strong microwave power. This effect is not relevant for TPQ mechanism, where the strong zero-field splitting renders the majority of triplets off resonance. On the technical level, the analytical evaluation of the line shapes for the two models is enabled by the fact that these shapes can be expressed via the eigenvalues of a complex Hamiltonian. This bypasses the necessity of solving the much larger complex linear system of the stochastic Liouville equations. Our findings pave the way towards a reliable discrimination between the two mechanisms via cw PLDMR.

Shape of a clamped stiff harpsichord wire driven at a resonant frequency

Science.gov (United States)

Hanson, Roger J.; Macomber, Hilliard Kent; Boucher, Mathew A.

2002-05-01

A wire transversely driven by a sinusoidal force at the resonant frequency of a vibrational mode vibrates at the driving frequency and at harmonics generated by nonlinear processes in the wire. If the amplitude of a harmonic is measured as a function of position along the wire, its shape is revealed. It differs significantly from a sinusoid in the vicinity of either end of the wire because the ends are clamped and the wire has significant stiffness. The shapes of various harmonics have been determined for a brass harpsichord wire, 70 cm long, from optical detector measurements made at different distances from a clamped end. Knowledge of shape facilitates the determination of antinode amplitudes of harmonics when the gross motion of the wire is so large that the detectors must be positioned near an end of the wire because of their very limited dynamic range. Some observations of harmonics and related phenomena were reported previously [Hanson et al., J. Acoust Soc. Am. 108, 2592 (2000); 106, 2141 (1999)]. The shape information is also needed to help separate nonlinear effects possibly occurring in the detectors from those of interest, occurring in the wire itself.

Air Damping in a Fan-Shaped Rotational Resonator with Comb Electrodes

Science.gov (United States)

Uchida, Yuki; Sugano, Koji; Tsuchiya, Toshiyuki; Tabata, Osamu; Ikehara, Tsuyoshi

We theoretically and experimentally evaluated the damping effect in a rotational resonator with a comb-drive actuator and sensor. The resonator was fabricated from an SOI wafer and has a fan-shaped mass. The underlying substrate was removed using back side deep reactive ion etching. One set of comb electrodes was attached to each side of the mass: one for electrostatic driving and the other for capacitive detection. In our theoretical analysis, the dynamics of the resonator were simplified so that they could be represented by a lumped system. In this lumped system, the damping coefficient was estimated by assuming the damping to be slide film damping and the air flow to be a Stokes flow. The phase shift due to the slide film damping of thick air layers was included in the lumped system. In the experimental evaluation, one side of the rotational combs was removed step-by-step and a half of the mass using a laser trimming tool so that the individual damping effects caused by the comb electrodes and mass could be determined quantitatively. We compared the experimental results with the results of the theoretical analysis and found that the difference in the damping coefficients between the experimental results and results of the theoretical analysis was less than 40%.

The static and dynamic behavior of MEMS arch resonators near veering and the impact of initial shapes

KAUST Repository

Hajjaj, Amal Z.; Alcheikh, Nouha; Younis, Mohammad I.

2017-01-01

We investigate experimentally and analytically the effect of initial shapes, arc and cosine wave, on the static and dynamic behavior of microelectromechanical systems (MEMS) arch resonators. We show that by carefully choosing the geometrical

Hippocampus shape analysis for temporal lobe epilepsy detection in magnetic resonance imaging

Science.gov (United States)

Kohan, Zohreh; Azmi, Reza

2016-03-01

There are evidences in the literature that Temporal Lobe Epilepsy (TLE) causes some lateralized atrophy and deformation on hippocampus and other substructures of the brain. Magnetic Resonance Imaging (MRI), due to high-contrast soft tissue imaging, is one of the most popular imaging modalities being used in TLE diagnosis and treatment procedures. Using an algorithm to help clinicians for better and more effective shape deformations analysis could improve the diagnosis and treatment of the disease. In this project our purpose is to design, implement and test a classification algorithm for MRIs based on hippocampal asymmetry detection using shape and size-based features. Our method consisted of two main parts; (1) shape feature extraction, and (2) image classification. We tested 11 different shape and size features and selected four of them that detect the asymmetry in hippocampus significantly in a randomly selected subset of the dataset. Then, we employed a support vector machine (SVM) classifier to classify the remaining images of the dataset to normal and epileptic images using our selected features. The dataset contains 25 patient images in which 12 cases were used as a training set and the rest 13 cases for testing the performance of classifier. We measured accuracy, specificity and sensitivity of, respectively, 76%, 100%, and 70% for our algorithm. The preliminary results show that using shape and size features for detecting hippocampal asymmetry could be helpful in TLE diagnosis in MRI.

Computing resonant frequency of C-shaped compact microstrip antennas by using ANFIS

Science.gov (United States)

Akdagli, Ali; Kayabasi, Ahmet; Develi, Ibrahim

2015-03-01

In this work, the resonant frequency of C-shaped compact microstrip antennas (CCMAs) operating at UHF band is computed by using the adaptive neuro-fuzzy inference system (ANFIS). For this purpose, 144 CCMAs with various relative dielectric constants and different physical dimensions were simulated by the XFDTD software package based on the finite-difference time domain (FDTD) method. One hundred and twenty-nine CCMAs were employed for training, while the remaining 15 CCMAs were used for testing of the ANFIS model. Average percentage error (APE) values were obtained as 0.8413% and 1.259% for training and testing, respectively. In order to demonstrate its validity and accuracy, the proposed ANFIS model was also tested over the simulation data given in the literature, and APE was obtained as 0.916%. These results show that ANFIS can be successfully used to compute the resonant frequency of CCMAs.

Quiescent and Eruptive Prominences at Solar Minimum: A Statistical Study via an Automated Tracking System

Science.gov (United States)

Loboda, I. P.; Bogachev, S. A.

2015-07-01

We employ an automated detection algorithm to perform a global study of solar prominence characteristics. We process four months of TESIS observations in the He II 304Å line taken close to the solar minimum of 2008-2009 and mainly focus on quiescent and quiescent-eruptive prominences. We detect a total of 389 individual features ranging from 25×25 to 150×500 Mm2 in size and obtain distributions of many of their spatial characteristics, such as latitudinal position, height, size, and shape. To study their dynamics, we classify prominences as either stable or eruptive and calculate their average centroid velocities, which are found to rarely exceed 3 km/s. In addition, we give rough estimates of mass and gravitational energy for every detected prominence and use these values to estimate the total mass and gravitational energy of all simultaneously existing prominences (1012 - 1014 kg and 1029 - 1031 erg). Finally, we investigate the form of the gravitational energy spectrum of prominences and derive it to be a power-law of index -1.1 ± 0.2.

Resonant transmission and mode modulation of acoustic waves in H-shaped metallic gratings

International Nuclear Information System (INIS)

Deng, Yu-Qiang; Fan, Ren-Hao; Zhang, Kun; Peng, Ru-Wen; Qi, Dong-Xiang

2015-01-01

In this work, we demonstrate that resonant full transmission of acoustic waves exists in subwavelength H-shaped metallic gratings, and transmission peaks can be efficiently tuned by adjusting the grating geometry. We investigate this phenomenon through both numerical simulations and theoretical calculations based on rigorous-coupled wave analysis. The transmission peaks are originated from Fabry-Perot resonances together with the couplings between the diffractive wave on the surface and the multiple guided modes in the slits. Moreover, the transmission modes can be efficiently tuned by adjusting the cavity geometry, without changing the grating thickness. The mechanism is analyzed based on an equivalent circuit model and verified by both the theoretical calculations and the numerical simulations. This research has potential application in acoustic-device miniaturization over a wide range of wavelengths

Apparent Solar Tornado-Like Prominences

Science.gov (United States)

Panasenco, Olga; Martin, Sara F.; Velli, Marco

2014-02-01

Recent high-resolution observations from the Solar Dynamics Observatory (SDO) have reawakened interest in the old and fascinating phenomenon of solar tornado-like prominences. This class of prominences was first introduced by Pettit ( Astrophys. J. 76, 9, 1932), who studied them over many years. Observations of tornado prominences similar to the ones seen by SDO had already been documented by Secchi ( Le Soleil, 1877). High-resolution and high-cadence multiwavelength data obtained by SDO reveal that the tornado-like appearance of these prominences is mainly an illusion due to projection effects. We discuss two different cases where prominences on the limb might appear to have a tornado-like behavior. One case of apparent vortical motions in prominence spines and barbs arises from the (mostly) 2D counterstreaming plasma motion along the prominence spine and barbs together with oscillations along individual threads. The other case of apparent rotational motion is observed in a prominence cavity and results from the 3D plasma motion along the writhed magnetic fields inside and along the prominence cavity as seen projected on the limb. Thus, the "tornado" impression results either from counterstreaming and oscillations or from the projection on the plane of the sky of plasma motion along magnetic-field lines, rather than from a true vortical motion around an (apparent) vertical or horizontal axis. We discuss the link between tornado-like prominences, filament barbs, and photospheric vortices at their base.

Quasibound levels and shape resonances of 39K2(B 1Pi/sub u/) crossed laser-molecular beam studies and analytical interpretation

International Nuclear Information System (INIS)

Heinze, J.; Kowalczyk, P.; Engelke, F.

1988-01-01

Quasibound levels and shape resonances in the (B 1 Pi/sub u/ -X 1 Σ + /sub g/) band system of 39 K 2 have been recorded by crossed laser-molecular beam techniques. Using optical--optical double resonance, individual rovibrational levels (v'' = 15--18, J'' = 3--25) of the K 2 state are prepared by Franck--Condon pumping (FCP) in a supersonic nozzle beam. Excitation into quasibound levels below and above the (B 1 Pi/sub u/) state barrier is detected as molecular and atomic (K4 2 P 3 /sub // 2 →4 2 S 1 /sub // 2 only) fluorescence. The resonance transition frequencies and shapes are measured and the results are used (a) to determine the scattering resonance energies, widths, and lifetimes; (b) to compare them with values obtained by a ''maximum internal amplitude'' approach [R. J. LeRoy and R. B. Bernstein, J. Chem. Phys. 54, 5114 (1971)]; and (c) to check the agreement with exact calculations of the B state potential using the ''inverted perturbation approach (IPA).'' The bound and quasibound part of the B 1 Pi/sub u/ state including the locus (R = 8.08 +- 0.05 A) of the barrier maximum (298 +- 8 cm -1 above the adiabatic dissociation limit) is found in excellent agreement with previous results. The shape resonances are not highly sensitive to the long-range interatomic forces, here the repulsive dipole--dipole resonance interaction

EVIDENCE FOR ROTATIONAL MOTIONS IN THE FEET OF A QUIESCENT SOLAR PROMINENCE

International Nuclear Information System (INIS)

Orozco Suárez, D.; Asensio Ramos, A.; Trujillo Bueno, J.

2012-01-01

We present observational evidence of apparent plasma rotational motions in the feet of a solar prominence. Our study is based on spectroscopic observations taken in the He I 1083.0 nm multiplet with the Tenerife Infrared Polarimeter attached to the German Vacuum Tower Telescope. We recorded a time sequence of spectra with 34 s cadence placing the slit of the spectrograph almost parallel to the solar limb and crossing two feet of an intermediate size, quiescent hedgerow prominence. The data show opposite Doppler shifts, ±6 km s –1 , at the edges of the prominence feet. We argue that these shifts may be interpreted as prominence plasma rotating counterclockwise around the vertical axis to the solar surface as viewed from above. The evolution of the prominence seen in EUV images taken with the Solar Dynamics Observatory provided us with clues to interpret the results as swirling motions. Moreover, time-distance images taken far from the central wavelength show plasma structures moving parallel to the solar limb with velocities of about 10-15 km s –1 . Finally, the shapes of the observed intensity profiles suggest the presence of, at least, two components at some locations at the edges of the prominence feet. One of them is typically Doppler shifted (up to ∼20 km s –1 ) with respect to the other, thus suggesting the existence of supersonic counter-streaming flows along the line of sight.

Mechanical detection and mode shape imaging of vibrational modes of micro and nanomechanical resonators by dynamic force microscopy

International Nuclear Information System (INIS)

Paulo, A S; GarcIa-Sanchez, D; Perez-Murano, F; Bachtold, A; Black, J; Bokor, J; Esplandiu, M J; Aguasca, A

2008-01-01

We describe a method based on the use of higher order bending modes of the cantilever of a dynamic force microscope to characterize vibrations of micro and nanomechanical resonators at arbitrarily large resonance frequencies. Our method consists on using a particular cantilever eigenmode for standard feedback control in amplitude modulation operation while another mode is used for detecting and imaging the resonator vibration. In addition, the resonating sample device is driven at or near its resonance frequency with a signal modulated in amplitude at a frequency that matches the resonance of the cantilever eigenmode used for vibration detection. In consequence, this cantilever mode is excited with an amplitude proportional to the resonator vibration, which is detected with an external lock-in amplifier. We show two different application examples of this method. In the first one, acoustic wave vibrations of a film bulk acoustic resonator around 1.6 GHz are imaged. In the second example, bending modes of carbon nanotube resonators up to 3.1 GHz are characterized. In both cases, the method provides subnanometer-scale sensitivity and the capability of providing otherwise inaccessible information about mechanical resonance frequencies, vibration amplitude values and mode shapes

Re-interpreting Prominences Classified as Tornadoes

Science.gov (United States)

Martin, Sara F.; Venkataramanasastry, Aparna

2015-04-01

Some papers in the recent literature identify tornado prominences with barbs of quiescent prominences while papers in the much older historic literature include a second category of tornado prominence that does not correspond to a barb of a quiescent prominence. The latter are described as prominence mass rotating around a nearly vertical axis prior to its eruption and the rotation was verified by spectral measurements. From H alpha Doppler-shifted mass motions recorded at Helio Research or the Dutch Open Telescope, we illustrate how the apparent tornado-like motions, identified with barbs, are illusions in our mind’s eye resulting from poorly resolved counterstreaming threads of mass in the barbs of quiescent prominences. In contrast, we confirm the second category of rotational motion in prominences shortly before and during eruption. In addition, we identify this second category as part of the late phase of a phenomenon called the roll effect in erupting prominences. In these cases, the eruption begins with the sideways rolling of the top of a prominence. As the eruption proceeds the rolling motion propagates down one leg or both legs of the prominence depending on whether the eruption is asymmetric or symmetric respectively. As an asymmetric eruption continues, the longer lasting leg becomes nearly vertical and its rotational motion also continues. If only this phase of the eruption was observed, as in some historic cases, it was called a tornado prominence. However, when we now observe entire eruptions in time-lapse sequences, the similarity to terrestrial tornadoes is lost. We conclude that neither prominence barbs, that give the illusion of rotation, nor the cases of true rotational motion, in the legs of erupting prominences, are usefully described as tornado prominences when the complete prominence structure or complete erupting event is observed.

Fast automated segmentation of multiple objects via spatially weighted shape learning

Science.gov (United States)

Chandra, Shekhar S.; Dowling, Jason A.; Greer, Peter B.; Martin, Jarad; Wratten, Chris; Pichler, Peter; Fripp, Jurgen; Crozier, Stuart

2016-11-01

Active shape models (ASMs) have proved successful in automatic segmentation by using shape and appearance priors in a number of areas such as prostate segmentation, where accurate contouring is important in treatment planning for prostate cancer. The ASM approach however, is heavily reliant on a good initialisation for achieving high segmentation quality. This initialisation often requires algorithms with high computational complexity, such as three dimensional (3D) image registration. In this work, we present a fast, self-initialised ASM approach that simultaneously fits multiple objects hierarchically controlled by spatially weighted shape learning. Prominent objects are targeted initially and spatial weights are progressively adjusted so that the next (more difficult, less visible) object is simultaneously initialised using a series of weighted shape models. The scheme was validated and compared to a multi-atlas approach on 3D magnetic resonance (MR) images of 38 cancer patients and had the same (mean, median, inter-rater) Dice’s similarity coefficients of (0.79, 0.81, 0.85), while having no registration error and a computational time of 12-15 min, nearly an order of magnitude faster than the multi-atlas approach.

ON THE RELATIONSHIP BETWEEN A HOT-CHANNEL-LIKE SOLAR MAGNETIC FLUX ROPE AND ITS EMBEDDED PROMINENCE

International Nuclear Information System (INIS)

Cheng, X.; Ding, M. D.; Zhang, J.; Guo, Y.; Chen, P. F.; Sun, J. Q.; Srivastava, A. K.

2014-01-01

A magnetic flux rope (MFR) is a coherent and helical magnetic field structure that has recently been found likely to appear as an elongated hot channel prior to a solar eruption. In this Letter, we investigate the relationship between the hot channel and the associated prominence through analysis of a limb event on 2011 September 12. In the early rise phase, the hot channel was initially cospatial with the prominence. It then quickly expanded, resulting in a separation of the top of the hot channel from that of the prominence. Meanwhile, they both experienced an instantaneous morphology transformation from a Λ shape to a reversed-Y shape and the top of these two structures showed an exponential increase in height. These features are a good indication of the occurrence of kink instability. Moreover, the onset of kink instability is found to coincide in time with the impulsive enhancement of flare emission underneath the hot channel, suggesting that ideal kink instability likely also plays an important role in triggering fast flare reconnection besides initiating the impulsive acceleration of the hot channel and distorting its morphology. We conclude that the hot channel is most likely the MFR system and the prominence only corresponds to the cool materials that are collected in the bottom of the helical field lines of the MFR against gravity

Prominence mass supply and the cavity

Energy Technology Data Exchange (ETDEWEB)

Schmit, Donald J.; Innes, D. [Max Planck Institute for Solar System Research, D-37191 Katlenburg-Lindau (Germany); Gibson, S. [High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO 80307 (United States); Luna, M. [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Karpen, J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2013-12-20

A prevalent but untested paradigm is often used to describe the prominence-cavity system: the cavity is under-dense because it is evacuated by supplying mass to the condensed prominence. The thermal non-equilibrium (TNE) model of prominence formation offers a theoretical framework to predict the thermodynamic evolution of the prominence and the surrounding corona. We examine the evidence for a prominence-cavity connection by comparing the TNE model with diagnostics of dynamic extreme ultraviolet (EUV) emission surrounding the prominence, specifically prominence horns. Horns are correlated extensions of prominence plasma and coronal plasma which appear to connect the prominence and cavity. The TNE model predicts that large-scale brightenings will occur in the Solar Dynamics Observatory Atmospheric Imaging Assembly 171 Å bandpass near the prominence that are associated with the cooling phase of condensation formation. In our simulations, variations in the magnitude of footpoint heating lead to variations in the duration, spatial scale, and temporal offset between emission enhancements in the other EUV bandpasses. While these predictions match well a subset of the horn observations, the range of variations in the observed structures is not captured by the model. We discuss the implications of our one-dimensional loop simulations for the three-dimensional time-averaged equilibrium in the prominence and the cavity. Evidence suggests that horns are likely caused by condensing prominence plasma, but the larger question of whether this process produces a density-depleted cavity requires a more tightly constrained model of heating and better knowledge of the associated magnetic structure.

Connections between molecular photoionization and electron-molecule scattering with emphasis on shape resonances

International Nuclear Information System (INIS)

Dehmer, J.L.; Dill, D.

1979-01-01

Most of our detailed information on the spectroscopy and dynamics of the electronic continuum of molecules is based on the complementary probes - photoionization and electron scattering. Though usually studied separately, it is most useful to appreciate the connections between these two processes since our understanding of one is often the key to interpreting or even generating new results in the other. We approach this subject in two steps. First, we very briefly outline the well-established connections, e.g., the Bethe-Born theory and comparisons of isoelectronic systems. Then we focus on a point of contact - the role of shape resonances in molecular photoionization and electron-molecule scattering - for which a substantial amount of new information has become available. Specific topics include mapping of resonances from the neutral (hν + molecule) to the negative ion (e + molecule) system, angular distributions, and interaction with vibration

Prominence Mass Supply and the Cavity

Science.gov (United States)

Schmit, Donald J.; Gibson, S.; Luna, M.; Karpen, J.; Innes, D.

2013-01-01

A prevalent but untested paradigm is often used to describe the prominence-cavity system; the cavity is under-dense because it it evacuated by supplying mass to the condensed prominence. The thermal non-equilibrium (TNE) model of prominence formation offers a theoretical framework to predict the thermodynamic evolutin of the prominence and the surrounding corona. We examine the evidence for a prominence-cavity connection by comparing the TNE model and diagnostics of dynamic extreme ultraviolet (EUV) emission surrounding the prominence, specifically prominence horns. Horns are correlated extensions of prminence plasma and coronal plasma which appear to connect the prominence and cavity. The TNE model predicts that large-scale brightenings will occur in the Solar Dynamics Observatory Atmospheric Imaging Assembly 171 A badpass near he prominence that are associated with the cooling phase of condensation formation. In our simulations, variations in the magnitude of footpoint heating lead to variations in the duration, spatial scale, and temporal offset between emission enhancements in the other EUV bandpasses. While these predictions match well a subset of the horn observations, the range of variations in the observed structures is not captured by the model. We discuss the implications of one-dimensional loop simulations for the three-dimensional time-averaged equilibrium in the prominence and the cavity. Evidence suggests that horns are likely caused by condensing prominence plasma, but the larger question of whether this process produces a density-depleted cavity requires a more tightly constrained model of heating and better knowledge of the associated magnetic structure.

Gap plasmon resonator arrays for unidirectional launching and shaping of surface plasmon polaritons

Energy Technology Data Exchange (ETDEWEB)

Lei, Zeyu; Yang, Tian, E-mail: tianyang@sjtu.edu.cn [State Key Laboratory of Advanced Optical Communication Systems and Networks, Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, UM-SJTU Joint Institute, Shanghai Jiao Tong University, Shanghai 200240 (China)

2016-04-18

We report the design and experimental realization of a type of miniaturized device for efficient unidirectional launching and shaping of surface plasmon polaritons (SPPs). Each device consists of an array of evenly spaced gap plasmon resonators with varying dimensions. Particle swarm optimization is used to achieve a theoretical two-dimensional launching efficiency of about 51%, under the normal illumination of a 5-μm waist Gaussian beam at 780 nm. By modifying the wavefront of the SPPs, unidirectional SPPs with focused, Bessel, and Airy profiles are launched and imaged with leakage radiation microscopy.

Enhanced optical transmission through a star-shaped bull's eye at dual resonant-bands in UV and the visible spectral range.

Science.gov (United States)

Nazari, Tavakol; Khazaeinezhad, Reza; Jung, Woohyun; Joo, Boram; Kong, Byung-Joo; Oh, Kyunghwan

2015-07-13

Dual resonant bands in UV and the visible range were simultaneously observed in the enhanced optical transmission (EOT) through star-shaped plasmonic structures. EOTs through four types of polygonal bull's eyes with a star aperture surrounded by the concentric star grooves were analyzed and compared for 3, 4, 5, and 6 corners, using finite difference time domain (FDTD) method. In contrast to plasmonic resonances in the visible range, the UV-band resonance intensity was found to scale with the number of corners, which is related with higher order multipole interactions. Spectral positions and relative intensities of the dual resonances were analyzed parametrically to find optimal conditions to maximize EOT in UV-visible dual bands.

Effects of diffusion and surface interactions on the line shape of electron paramagnetic resonances in the presence of a magnetic field gradient

International Nuclear Information System (INIS)

Schaden, M.; Zhao, K. F.; Wu, Z.

2007-01-01

In an evanescent wave magnetometer the Zeeman polarization is probed at micrometer to submicrometer distances from the cell surface. The electron paramagnetic resonance lines of an evanescent wave magnetometer in the presence of a magnetic field gradient exhibit edge enhancement seen previously in nuclear magnetic resonance lines. We present a theoretical model that describes quantitatively the shape of the magnetic resonance lines of an evanescent wave magnetometer under a wide range of experimental conditions. It accounts for diffusion broadening in the presence of a magnetic field gradient as well as interactions of spin polarized Rb atoms with the coated Pyrex glass surfaces. Depending on the field gradient, cell thickness, and buffer gas pressure, the resonance line may have the form of a single asymmetric peak or two peaks localized near the front and back surfaces in frequency space. The double-peaked response depends on average characteristics of the surface interactions. Its shape is sensitive to the dwell time, relaxation probability, and average phase shift of adsorbed spin polarized Rb atoms

A three-dimensional model for solar prominences

International Nuclear Information System (INIS)

Demoulin, P.; Priest, E.R.; Anzer, U.

1989-01-01

Prominences have been modelled largely as one-or two-dimensional structures, and yet observations show them to possess important variations in the third dimension along the prominence axis with great arches with feet reaching down towards the solar surface. As an initial attempt to understand this structure we consider a three-dimensional linear force-free field model for the global magnetic field around a quiescent prominence. It consists of a fundamental together with a harmonic that is periodic along the prominence. At the solar surface there is a series of flux concentrations spaced out periodically on both sides of the prominence. Between a pair of oppositely directed flux concentration, the magnetic field in the prominence is stronger and tends to be less highly sheared than elsewhere. This modulation of the field strength and shear angle along the prominence decreases with height and almost disappears above 10 Mm. Prominence fields that increase with height occur when the shear is large and the length-scale for field variations perpendicular to the prominence exceeds that along it. The variation of the prominence height along the prominence is calculated and it is suggested that feet occur where the prominence sags down to low heights. For prominences of Normal polarity this tends to occur near supergranule centres where the transverse field is least, whereas for those of Inverse polarity it usually takes place near the chromospheric network where the transverse field is greatest. The effect of concentrating the base flux by including extra harmonics is also included. For Normal polarity prominences it tends to make the foot wider, and for Inverse polarity configurations, it usually creates deeper and narrower feet

QUIESCENT PROMINENCES IN THE ERA OF ALMA: SIMULATED OBSERVATIONS USING THE 3D WHOLE-PROMINENCE FINE STRUCTURE MODEL

Energy Technology Data Exchange (ETDEWEB)

Gunár, Stanislav; Heinzel, Petr [Astronomical Institute, The Czech Academy of Sciences, 25165 Ondřejov (Czech Republic); Mackay, Duncan H. [School of Mathematics and Statistics, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom); Anzer, Ulrich [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85740 Garching bei München (Germany)

2016-12-20

We use the detailed 3D whole-prominence fine structure model to produce the first simulated high-resolution ALMA observations of a modeled quiescent solar prominence. The maps of synthetic brightness temperature and optical thickness shown in the present paper are produced using a visualization method for synthesis of the submillimeter/millimeter radio continua. We have obtained the simulated observations of both the prominence at the limb and the filament on the disk at wavelengths covering a broad range that encompasses the full potential of ALMA. We demonstrate here extent to which the small-scale and large-scale prominence and filament structures will be visible in the ALMA observations spanning both the optically thin and thick regimes. We analyze the relationship between the brightness and kinetic temperature of the prominence plasma. We also illustrate the opportunities ALMA will provide for studying the thermal structure of the prominence plasma from the cores of the cool prominence fine structure to the prominence–corona transition region. In addition, we show that detailed 3D modeling of entire prominences with their numerous fine structures will be important for the correct interpretation of future ALMA observations of prominences.

Pulse-bandwidth dependence of coherent phase control of resonance-mediated (2+1) three-photon absorption

International Nuclear Information System (INIS)

Gandman, Andrey; Chuntonov, Lev; Rybak, Leonid; Amitay, Zohar

2007-01-01

We study in detail coherent phase control of femtosecond resonance-mediated (2+1) three-photon absorption and its dependence on the spectral bandwidth of the excitation pulse. The regime is the weak-field regime of third perturbative order. The corresponding interference mechanism involves a group of three-photon excitation pathways that are on resonance with the intermediate state and a group of three-photon excitation pathways that are near resonant with it. The model system of the study is atomic sodium (Na), for which experimental and numerical-theoretical results are obtained. Prominent among the results is our finding that with simple proper pulse shaping an increase in the excitation bandwidth leads to a corresponding increase in the enhancement of the three-photon absorption over the absorption induced by the (unshaped) transform-limited pulse. For example, here, a 40 nm bandwidth leads to an order-of-magnitude enhancement over the transform-limited absorption

Solar Features - Prominences and Filaments

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Prominences and filaments are two manifestations of the same phenomenon. Both prominences and filaments are features formed above the chromosphere by cool dense...

New perspectives on solar prominences

Science.gov (United States)

Schmieder, B.; Aulanier, G.

2012-06-01

Recent observations of prominences obtained with high spatial and temporal resolution instruments, on board satellites (Hinode, SDO) as well as on the ground (SST) have provided very intriguing movies and open a new area for understanding the nature of prominences. The main topics are still debate: formation, dynamics, and characteristics of the plasma in the core and in the transition zone between the prominence and corona. We will review briefly the recent advances made in these topics, observationally as well as theoretically.

Resonant non-Gaussianity with equilateral properties

International Nuclear Information System (INIS)

Gwyn, Rhiannon; Rummel, Markus

2012-11-01

We discuss the effect of superimposing multiple sources of resonant non-Gaussianity, which arise for instance in models of axion inflation. The resulting sum of oscillating shape contributions can be used to ''Fourier synthesize'' different non-oscillating shapes in the bispectrum. As an example we reproduce an approximately equilateral shape from the superposition of O(10) oscillatory contributions with resonant shape. This implies a possible degeneracy between the equilateral-type non-Gaussianity typical of models with non-canonical kinetic terms, such as DBI inflation, and an equilateral-type shape arising from a superposition of resonant-type contributions in theories with canonical kinetic terms. The absence of oscillations in the 2-point function together with the structure of the resonant N-point functions, imply that detection of equilateral non-Gaussianity at a level greater than the PLANCK sensitivity of f NL ∝O(5) will rule out a resonant origin. We comment on the questions arising from possible embeddings of this idea in a string theory setting.

Surface vibrational modes in disk-shaped resonators.

Science.gov (United States)

Dmitriev, A V; Gritsenko, D S; Mitrofanov, V P

2014-03-01

The natural frequencies and distributions of displacement components for the surface vibrational modes in thin isotropic elastic disks are calculated. In particular, the research is focused on even solutions for low-lying resonant vibrations with large angular wave numbers. Several families of modes are found which are interpreted as modified surface modes of an infinitely long cylinder and Lamb modes of a plate. The results of calculation are compared with the results of the experimental measurements of vibrational modes generated by means of resonant excitation in duraluminum disk with radius of ≈90 mm and thickness of 16 mm in the frequency range of 130-200 kHz. An excellent agreement between the calculated and measured frequencies is found. Measurements of the structure of the resonant peaks show splitting of some modes. About a half of the measured modes has splitting Δfsplit/fmode at the level of the order of 10(-5). The Q-factors of all modes measured in vacuum lie in the interval (2…3)×10(5). This value is typical for duraluminum mechanical resonators in the ultrasonic frequency range. Copyright © 2013 Elsevier B.V. All rights reserved.

A novel C-shaped, gold nanoparticle coated, embedded polymer waveguide for localized surface plasmon resonance based detection.

Science.gov (United States)

Prabhakar, Amit; Mukherji, Soumyo

2010-12-21

In this study, a novel embedded optical waveguide based sensor which utilizes localized surface plasmon resonance of gold nanoparticles coated on a C-shaped polymer waveguide is being reported. The sensor, as designed, can be used as an analysis chip for detection of minor variations in the refractive index of its microenvironment, which makes it suitable for wide scale use as an affinity biosensor. The C-shaped waveguide coupled with microfluidic channel was fabricated by single step patterning of SU8 on an oxidized silicon wafer. The absorbance due to the localized surface plasmon resonance (LSPR) of SU8 waveguide bound gold nano particle (GNP) was found to be linear with refractive index changes between 1.33 and 1.37. A GNP coated C-bent waveguide of 200 μ width with a bend radius of 1 mm gave rise to a sensitivity of ~5 ΔA/RIU at 530 nm as compared to the ~2.5 ΔA/RIU (refractive index units) of the same dimension bare C-bend SU8 waveguide. The resolution of the sensor probe was ~2 × 10(-4) RIU.

Exploiting NiTi shape memory alloy films in design of tunable high frequency microcantilever resonators

Science.gov (United States)

Stachiv, I.; Sittner, P.; Olejnicek, J.; Landa, M.; Heller, L.

2017-11-01

Shape memory alloy (SMA) films are very attractive materials for microactuators because of their high energy density. However, all currently developed SMA actuators utilize martensitic transformation activated by periodically generated heating and cooling; therefore, they have a slow actuation speed, just a few Hz, which restricts their use in most of the nanotechnology applications such as high frequency microcantilever based physical and chemical sensors, atomic force microscopes, or RF filters. Here, we design tunable high frequency SMA microcantilevers for nanotechnology applications. They consist of a phase transforming NiTi SMA film sputtered on the common elastic substrate material; in our case, it is a single-crystal silicon. The reversible tuning of microcantilever resonant frequencies is then realized by intentionally changing the Young's modulus and the interlayer stress of the NiTi film by temperature, while the elastic substrate guarantees the high frequency actuation (up to hundreds of kHz) of the microcantilever. The experimental results qualitatively agree with predictions obtained from the dedicated model based on the continuum mechanics theory and a phase characteristic of NiTi. The present design of SMA microcantilevers expands the capability of current micro-/nanomechanical resonators by enabling tunability of several consecutive resonant frequencies.

Resonant non-Gaussianity with equilateral properties

Energy Technology Data Exchange (ETDEWEB)

Gwyn, Rhiannon [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Potsdam (Germany); Rummel, Markus [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Westphal, Alexander [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-11-15

We discuss the effect of superimposing multiple sources of resonant non-Gaussianity, which arise for instance in models of axion inflation. The resulting sum of oscillating shape contributions can be used to ''Fourier synthesize'' different non-oscillating shapes in the bispectrum. As an example we reproduce an approximately equilateral shape from the superposition of O(10) oscillatory contributions with resonant shape. This implies a possible degeneracy between the equilateral-type non-Gaussianity typical of models with non-canonical kinetic terms, such as DBI inflation, and an equilateral-type shape arising from a superposition of resonant-type contributions in theories with canonical kinetic terms. The absence of oscillations in the 2-point function together with the structure of the resonant N-point functions, imply that detection of equilateral non-Gaussianity at a level greater than the PLANCK sensitivity of f{sub NL} {proportional_to}O(5) will rule out a resonant origin. We comment on the questions arising from possible embeddings of this idea in a string theory setting.

Multiquark Resonances

CERN Document Server

Esposito, A.; Polosa, A.D.

2016-01-01

Multiquark resonances are undoubtedly experimentally observed. The number of states and the amount of details on their properties has been growing over the years. It is very recent the discovery of two pentaquarks and the confirmation of four tetraquarks, two of which had not been observed before. We mainly review the theoretical understanding of this sector of particle physics phenomenology and present some considerations attempting a coherent description of the so called X and Z resonances. The prominent problems plaguing theoretical models, like the absence of selection rules limiting the number of states predicted, motivate new directions in model building. Data are reviewed going through all of the observed resonances with particular attention to their common features and the purpose of providing a starting point to further research.

Magnetohydrodynamic (MHD) simulation of solar prominence formation

International Nuclear Information System (INIS)

Bao, J.

1987-01-01

Formation of Kippenhahn-Schluter type solar prominences by chromospheric mass injection is studied via numerical simulation. The numerical model is based on a two-dimensional, time-dependent magnetohydrodynamic (MHD) theory. In addition, an analysis of gravitational thermal MHD instabilities related to condensation is performed by using the small-perturbation method. The conclusions are: (1) Both quiescent and active-region prominences can be formed by chromospheric mass injection, provided certain optimum conditions are satisfied. (2) Quiescent prominences cannot be formed without condensation, though enough mass is supplied from chromosphere. The mass of a quiescent prominence is composed of both the mass injected from the chromosphere and the mass condensed from the corona. On the other hand, condensation is not important to active region prominence formation. (3) In addition to channeling and supporting effects, the magnetic field plays another important role, i.e. containing the prominence material. (4) In the model cases, prominences are supported by the Lorentz force, the gas-pressure gradient and the mass-injection momentum. (5) Due to gravity, more MHD condensation instability modes appear in addition to the basic condensation mode

Relative humidity sensor based on surface plasmon resonance of D-shaped fiber with polyvinyl alcohol embedding Au grating

Science.gov (United States)

Yan, Haitao; Han, Daofu; Li, Ming; Lin, Bo

2017-01-01

This paper presents the design, fabrication, and characterization of a D-shaped fiber coated with polyvinyl alcohol (PVA) embedding an Au grating-based relative humidity (RH) sensor. The Au grating is fabricated on a D-shaped fiber to match the wave-vector and excite the surface plasmon, and the PVA is embedded in the Au grating as a sensitive cladding film. The refractive index of PVA changes with the ambient humidity. Measurements in a controlled environment show that the RH sensor can achieve a sensitivity of 5.4 nm per relative humidity unit in the RH range from 0% to 70% RH. Moreover, the surface plasmon resonance can be realized and used for RH sensing at the C band of optical fiber communication instead of the visible light band due to the metallic grating microstructure on the D-shaped fiber.

Nonlinear MHD Waves in a Prominence Foot

Science.gov (United States)

Ofman, L.; Knizhnik, K.; Kucera, T.; Schmieder, B.

2015-11-01

We study nonlinear waves in a prominence foot using a 2.5D MHD model motivated by recent high-resolution observations with Hinode/Solar Optical Telescope in Ca ii emission of a prominence on 2012 October 10 showing highly dynamic small-scale motions in the prominence material. Observations of Hα intensities and of Doppler shifts show similar propagating fluctuations. However, the optically thick nature of the emission lines inhibits a unique quantitative interpretation in terms of density. Nevertheless, we find evidence of nonlinear wave activity in the prominence foot by examining the relative magnitude of the fluctuation intensity (δI/I ˜ δn/n). The waves are evident as significant density fluctuations that vary with height and apparently travel upward from the chromosphere into the prominence material with quasi-periodic fluctuations with a typical period in the range of 5-11 minutes and wavelengths <2000 km. Recent Doppler shift observations show the transverse displacement of the propagating waves. The magnetic field was measured with the THEMIS instrument and was found to be 5-14 G. For the typical prominence density the corresponding fast magnetosonic speed is ˜20 km s-1, in qualitative agreement with the propagation speed of the detected waves. The 2.5D MHD numerical model is constrained with the typical parameters of the prominence waves seen in observations. Our numerical results reproduce the nonlinear fast magnetosonic waves and provide strong support for the presence of these waves in the prominence foot. We also explore gravitational MHD oscillations of the heavy prominence foot material supported by dipped magnetic field structure.

NONLINEAR MHD WAVES IN A PROMINENCE FOOT

Energy Technology Data Exchange (ETDEWEB)

Ofman, L. [Catholic University of America, Washington, DC 20064 (United States); Knizhnik, K.; Kucera, T. [NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States); Schmieder, B. [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris-Diderot, Sorbonne Paris Cit, 5 place Jules Janssen, F-92195 Meudon (France)

2015-11-10

We study nonlinear waves in a prominence foot using a 2.5D MHD model motivated by recent high-resolution observations with Hinode/Solar Optical Telescope in Ca ii emission of a prominence on 2012 October 10 showing highly dynamic small-scale motions in the prominence material. Observations of Hα intensities and of Doppler shifts show similar propagating fluctuations. However, the optically thick nature of the emission lines inhibits a unique quantitative interpretation in terms of density. Nevertheless, we find evidence of nonlinear wave activity in the prominence foot by examining the relative magnitude of the fluctuation intensity (δI/I ∼ δn/n). The waves are evident as significant density fluctuations that vary with height and apparently travel upward from the chromosphere into the prominence material with quasi-periodic fluctuations with a typical period in the range of 5–11 minutes and wavelengths <2000 km. Recent Doppler shift observations show the transverse displacement of the propagating waves. The magnetic field was measured with the THEMIS instrument and was found to be 5–14 G. For the typical prominence density the corresponding fast magnetosonic speed is ∼20 km s{sup −1}, in qualitative agreement with the propagation speed of the detected waves. The 2.5D MHD numerical model is constrained with the typical parameters of the prominence waves seen in observations. Our numerical results reproduce the nonlinear fast magnetosonic waves and provide strong support for the presence of these waves in the prominence foot. We also explore gravitational MHD oscillations of the heavy prominence foot material supported by dipped magnetic field structure.

Acoustic Fano resonators

KAUST Repository

Amin, Muhammad; Farhat, Mohamed; Bagci, Hakan

2014-01-01

The resonances with asymmetric Fano line-shapes were originally discovered in the context of quantum mechanics (U. Fano, Phys. Rev., 124, 1866-1878, 1961). Quantum Fano resonances were generated from destructive interference of a discrete state

Feshbach shape resonance for high Tc pairing in superlattices of quantum stripes and quantum wells

Directory of Open Access Journals (Sweden)

A Bianconi

2006-09-01

Full Text Available   The Feshbach shape resonances in the interband pairing in superconducting superlattices of quantum wells or quantum stripes is shown to provide the mechanism for high Tc superconductivity. This mechanism provides the Tc amplification driven by the architecture of material: superlattices of quantum wells (intercalated graphite or diborides and superlattices of quantum stripes (doped high Tc cuprate perovskites where the chemical potential is tuned to a Van Hove-Lifshitz singularity (vHs in the electronic energy spectrum of the superlattice associated with the change of the Fermi surface dimensionality in one of the subbands.

Signs of helicity in solar prominences and related features

Science.gov (United States)

Martin, S.

This review illustrates several ways to identify the chirality (handedness) of solar prominences (filaments) from their structure and the structure of their surrounding magnetic fields in the chromosphere and corona. For prominences, these structural elements include the axial magnetic field direction, orientation of barbs, and direction of the prominence fine structure. The surrounding structures include the pattern of fibrils beneath the prominences and the pattern of coronal loops above the prominences. These ways of identifying chirality are then interpreted in terms of the formal definitions of helicity to yield a consistent set of one-to-one helicity relationships for all features. The helicity of some prominences can also be independently determined during their eruption by their fine structure, apparent crossings in the line-of-sight of different parts of the same prominence, and by large- scale twist of the prominence structure. Unlike observations of prominences (filaments) observed prior to eruption, in some cases evidence of both signs of helicity are found within the same erupting prominence. This indicates the continued application of forces on the prominences during the eruption process or the possible introduction of force(s) not present during earlier stages of their evolution.

The multielectron character of the S 2p → 4e{sub g} shape resonance in the SF{sub 6} molecule studied via detection of soft X-ray emission and neutral high-Rydberg fragments

Energy Technology Data Exchange (ETDEWEB)

Kivimäki, A., E-mail: kivimaki@iom.cnr.it [CNR—Istituto Officina dei Materiali (IOM), Laboratorio TASC, 34149 Trieste (Italy); Coreno, M. [CNR—Istituto di Struttura della Materia (ISM), Basovizza Area Science Park, 34149 Trieste (Italy); Miotti, P.; Frassetto, F.; Poletto, L. [CNR—Istituto di Fotonica e Nanotecnologie (IFN), via Trasea 7, 35131 Padova (Italy); Stråhlman, C. [MAX IV Laboratory, Lund University, P.O. Box 118, 22100 Lund (Sweden); Simone, M. de [CNR—Istituto Officina dei Materiali (IOM), Laboratorio TASC, 34149 Trieste (Italy); Richter, R. [Elettra-Sincrotrone Trieste, Area Science Park Basovizza, 34149 Trieste (Italy)

2016-05-15

Highlights: • The soft X-ray emission spectrum of SF{sub 6} changes at the S 2p → 4e{sub g} shape resonance. • The emission band around 172 eV indicates the population of the 6a{sub 1g} orbital. • Shake-up processes accompanying S 2p ionization can explain the new emissions. • Field ionization of neutral high Rydberg (HR) fragments reveals F and S atoms. • The yield of neutral HR fragments increases at the S 2p → 4e{sub g} shape resonance. - Abstract: We have studied the nature of the S 2p → 4e{sub g} shape resonance in the SF{sub 6} molecule by performing two different experiments. Soft X-ray emission spectra measured at the 4e{sub g} shape resonance reveal features that do not originate from the S 2p{sup −1} states. One of the features can be assigned to the 6a{sub 1g} → S 2p transition. The 6a{sub 1g} orbital, which is empty in the molecular ground state, can be populated either in core–valence double excitations or in S 2p shake-up transitions. Both these channels are considered. We have also studied the fragmentation of SF{sub 6} molecule after the decay of the S 2p core-hole states by observing neutral fragments in high-Rydberg states, where an electron occupies an orbital with n ≥ 20 (n is the principal quantum number). Such neutral fragments become, in relative terms, more abundant at the S 2p → 4e{sub g} shape resonance with respect to the S 2p → 2t{sub 2g} shape resonance, which is a pure one-electron phenomenon.

Controlling the shapes and sizes of metallic nanoantennas for detection of biological molecules using hybridization phase of plasmon resonances and photonic lattice modes

Science.gov (United States)

Gutha, Rithvik R.; Sharp, Christina; Wing, Waylin J.; Sadeghi, Seyed M.

2018-02-01

Chemical sensing based on Localized Surface Plasmonic Resonances (LSPR) and the ultra-sharp optical features of surface lattice resonances (SLR) of arrays of metallic nanoantennas have attracted much attention. Recently we studied biosensing based on the transition between LSPR and SLR (hybridization phase), demonstrating significantly higher refractive index sensitivity than each of these resonances individually. In this contribution we study the impact of size and shape of the metallic nanoantennas on the hybridization process and the way they influence application of this process for biosensing, wherein miniscule variation of the refractive index of the environment leads to dramatic changes in the spectral properties of the arrays.

Stark-shift induced resonances in multiphoton ionization

International Nuclear Information System (INIS)

Potvliege, R M; Vuci, Svetlana

2006-01-01

The resonance enhancements marking the ATI spectrum of argon are discussed in the light of a recently compiled map of the quasienergies of this atom. Many of the dressed excited states of interest shift nonponderomotively in complicated ways, but keep an ionization width narrow enough to produce sharp substructures of both low and high ATI peaks through Stark-shift induced resonances. The most prominent enhancement observed in the high-order ATI peaks originates from ionization from the dressed ground state perturbed by the influence of neighbouring resonant dressed states

Automated image based prominent nucleoli detection.

Science.gov (United States)

Yap, Choon K; Kalaw, Emarene M; Singh, Malay; Chong, Kian T; Giron, Danilo M; Huang, Chao-Hui; Cheng, Li; Law, Yan N; Lee, Hwee Kuan

2015-01-01

Nucleolar changes in cancer cells are one of the cytologic features important to the tumor pathologist in cancer assessments of tissue biopsies. However, inter-observer variability and the manual approach to this work hamper the accuracy of the assessment by pathologists. In this paper, we propose a computational method for prominent nucleoli pattern detection. Thirty-five hematoxylin and eosin stained images were acquired from prostate cancer, breast cancer, renal clear cell cancer and renal papillary cell cancer tissues. Prostate cancer images were used for the development of a computer-based automated prominent nucleoli pattern detector built on a cascade farm. An ensemble of approximately 1000 cascades was constructed by permuting different combinations of classifiers such as support vector machines, eXclusive component analysis, boosting, and logistic regression. The output of cascades was then combined using the RankBoost algorithm. The output of our prominent nucleoli pattern detector is a ranked set of detected image patches of patterns of prominent nucleoli. The mean number of detected prominent nucleoli patterns in the top 100 ranked detected objects was 58 in the prostate cancer dataset, 68 in the breast cancer dataset, 86 in the renal clear cell cancer dataset, and 76 in the renal papillary cell cancer dataset. The proposed cascade farm performs twice as good as the use of a single cascade proposed in the seminal paper by Viola and Jones. For comparison, a naive algorithm that randomly chooses a pixel as a nucleoli pattern would detect five correct patterns in the first 100 ranked objects. Detection of sparse nucleoli patterns in a large background of highly variable tissue patterns is a difficult challenge our method has overcome. This study developed an accurate prominent nucleoli pattern detector with the potential to be used in the clinical settings.

Automated image based prominent nucleoli detection

Directory of Open Access Journals (Sweden)

Choon K Yap

2015-01-01

Full Text Available Introduction: Nucleolar changes in cancer cells are one of the cytologic features important to the tumor pathologist in cancer assessments of tissue biopsies. However, inter-observer variability and the manual approach to this work hamper the accuracy of the assessment by pathologists. In this paper, we propose a computational method for prominent nucleoli pattern detection. Materials and Methods: Thirty-five hematoxylin and eosin stained images were acquired from prostate cancer, breast cancer, renal clear cell cancer and renal papillary cell cancer tissues. Prostate cancer images were used for the development of a computer-based automated prominent nucleoli pattern detector built on a cascade farm. An ensemble of approximately 1000 cascades was constructed by permuting different combinations of classifiers such as support vector machines, eXclusive component analysis, boosting, and logistic regression. The output of cascades was then combined using the RankBoost algorithm. The output of our prominent nucleoli pattern detector is a ranked set of detected image patches of patterns of prominent nucleoli. Results: The mean number of detected prominent nucleoli patterns in the top 100 ranked detected objects was 58 in the prostate cancer dataset, 68 in the breast cancer dataset, 86 in the renal clear cell cancer dataset, and 76 in the renal papillary cell cancer dataset. The proposed cascade farm performs twice as good as the use of a single cascade proposed in the seminal paper by Viola and Jones. For comparison, a naive algorithm that randomly chooses a pixel as a nucleoli pattern would detect five correct patterns in the first 100 ranked objects. Conclusions: Detection of sparse nucleoli patterns in a large background of highly variable tissue patterns is a difficult challenge our method has overcome. This study developed an accurate prominent nucleoli pattern detector with the potential to be used in the clinical settings.

On the evaluation of temperature dependence of elastic constants of martensitic phases in shape memory alloys from resonant ultrasound spectroscopy studies

Czech Academy of Sciences Publication Activity Database

Landa, Michal; Sedlák, Petr; Šittner, Petr; Seiner, Hanuš; Heller, Luděk

481-482, - (2008), s. 567-573 ISSN 0921-5093 R&D Projects: GA ČR GA101/06/0768 Institutional research plan: CEZ:AV0Z20760514; CEZ:AV0Z10100520 Keywords : modal resonant ultrasound spectroscopy * elastic properties * shape memory alloy s Subject RIV: BI - Acoustics Impact factor: 1.806, year: 2008

Human perception of shape from touch

NARCIS (Netherlands)

Kappers, Astrid M L

2011-01-01

In this paper, I focus on the role of active touch in three aspects of shape perception and discrimination studies. First an overview is given of curvature discrimination experiments. The most prominent result is that first-order stimulus information (that is, the difference in attitude or slope

Engineered SOI slot waveguide ring resonator V-shape resonance combs for refraction index sensing up to 1300nm/RIU (Conference Presentation)

Science.gov (United States)

Zhang, Weiwei; Serna, Samuel; Le Roux, Xavier; Vivien, Laurent; Cassan, Eric

2016-05-01

breakthrough of the performance of slot ring resonator sensing ability. Different from the normal sensing regime by monitoring one specific resonance (λres) peak shift, the proposed approach stems from the sensitivity of the RR critical coupling. The critical coupling peak is auto-selected out by matching the following condition: the ring resonator's round trip attenuation coefficient a(λ) being equal to the coupler self-coupling coefficient k(λ), thus resulting in the deepest extinction ratio (ER) among the spectrum RR comb. The obtained sensing comb, based on a V-shape spectrum envelop, is engineered by controlling a(λ) and k(λ) with opposite monotonicities. Both a(λ)and k(λ) are tuned to have a large dispersion along the wavelength, which means that |a(λ)-k(λ)| keeps rapidly increasing as λres is far away from λc, eliminating the resonance ER quickly down to 0. Experimentally, slot waveguide ring resonators with a radius of 50µm have been fabricated on a standard silicon platform with a Si thickness of 220nm, loaded by racetrack couplers with a straight coupling length of 20µm. Sensing experiments have been carried out by changing the top cladding material from a series of Cargille optical liquids with refraction index values ranging from 1.3 to 1.5. The Q factors of critical coupling resonances was monitored from 2,000 to 6,000, and measured wavelength shifts of this peak are from 1.41µm to 1.56µm. The maximum sensitivity of 1300nm/RIU is observed in the cladding index range 1.30-1.35. To conclude, a new sensing regime by tracking the critical coupling resonance λc of slot waveguide ring resonators is demonstrated. The reported sensitivity is up 1300nm/RIU around the water RI of 1.33, and the monitored sensing FOM is about 2300, which is very close to the FOM values achieved from nanobeam cavities. This work can thus contribute to future integrated optical sensing schemes based on slot RRs.

Dominance of Plasmonic Resonant Energy Transfer over Direct Electron Transfer in Substantially Enhanced Water Oxidation Activity of BiVO4 by Shape-Controlled Au Nanoparticles.

Science.gov (United States)

Lee, Mi Gyoung; Moon, Cheon Woo; Park, Hoonkee; Sohn, Woonbae; Kang, Sung Bum; Lee, Sanghan; Choi, Kyoung Jin; Jang, Ho Won

2017-10-01

The performance of plasmonic Au nanostructure/metal oxide heterointerface shows great promise in enhancing photoactivity, due to its ability to confine light to the small volume inside the semiconductor and modify the interfacial electronic band structure. While the shape control of Au nanoparticles (NPs) is crucial for moderate bandgap semiconductors, because plasmonic resonance by interband excitations overlaps above the absorption edge of semiconductors, its critical role in water splitting is still not fully understood. Here, first, the plasmonic effects of shape-controlled Au NPs on bismuth vanadate (BiVO 4 ) are studied, and a largely enhanced photoactivity of BiVO 4 is reported by introducing the octahedral Au NPs. The octahedral Au NP/BiVO 4 achieves 2.4 mA cm -2 at the 1.23 V versus reversible hydrogen electrode, which is the threefold enhancement compared to BiVO 4 . It is the highest value among the previously reported plasmonic Au NPs/BiVO 4 . Improved photoactivity is attributed to the localized surface plasmon resonance; direct electron transfer (DET), plasmonic resonant energy transfer (PRET). The PRET can be stressed over DET when considering the moderate bandgap semiconductor. Enhanced water oxidation induced by the shape-controlled Au NPs is applicable to moderate semiconductors, and shows a systematic study to explore new efficient plasmonic solar water splitting cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Topic prominence in Chinese EFL learners’ interlanguage

Directory of Open Access Journals (Sweden)

Shaopeng Li

2014-01-01

Full Text Available The present study aims to investigate the general characteristics of topicprominent typological interlanguage development of Chinese learners of English in terms of acquiring subject-prominent English structures from a discourse perspective. Topic structures mainly appear in Chinese discourse in the form of topic chains (Wang, 2002; 2004. The research target are the topic chain, which is the main topic-prominent structure in Chinese discourse, and zero anaphora, which is the most common topic anaphora in the topic chain. Two important findings emerged from the present study. First, the characteristics of Chinese topic chains are transferrable to the interlanguage of Chinese EFL learners, thus resulting in overgeneralization of the zero anaphora. Second, the interlanguage discourse of Chinese EFL learners reflects a change of the second language acquisition process from topic-prominence to subject-prominence, thus lending support to the discourse transfer hypothesis.

EUV observations of quiescent prominences from Skylab

International Nuclear Information System (INIS)

Moe, O.K.

1979-01-01

The authors report measurements of line intensities and line widths for three quiescent prominences observed with the Naval Research Laboratory slit spectrograph on ATM/Skylab. The wavelengths of the observed lines cover the range 1175 A to 1960 A. The measured intensities have been calibrated to within approximately a factor 2 and are average intensities over a 2 arc sec by 60 arc set slit. Nonthermal velocities are derived from the measured line widths. The nonthermal velocity is found to increase with temperature in the prominence transition zone. Electron densities and pressures are derived from density sensitive line ratios. Electron pressures for two of the prominences are found to lie in the range 0.04-0.08 dyn cm -2 , while values for the third and most intense and active of the three prominences are in the range 0.07-0.22 dyn cm -2 . (Auth.)

Localized surface plasmon resonance enhanced photoluminescence of CdSe QDs in PMMA matrix on silver colloids with different shapes

International Nuclear Information System (INIS)

Lu Liu; Xu Xiaoliang; Shi Chaoshu; Ming Hai

2010-01-01

Localized surface plasmon resonance (LSPR) enhanced photoluminescences (PL) from CdSe quantum dots (QDs) on worm-like or quasi-spherical silver colloids have been investigated. The shape of silver colloid film is controlled by annealing temperature (200 o C∼350 o C). Strong PL enhancements of CdSe QDs on both as-grown and annealed silver colloid films are observed. The results show that the PL enhancement factor of CdSe QDs on worm-like silver colloid film reaches as high as 15-fold. Moreover, the enhancement factor is 5 times larger than that obtained from the quasi-spherical silver colloids. The superiority of worm-like silver nanostructure on LSPR enhanced photoluminescence is attributed to its larger size, hot spots and multiple dipole resonance modes coupling, which are induced by aggregation effect.

The natural line shape of the giant dipole resonance

International Nuclear Information System (INIS)

Gordon, E.F.; Pitthan, R.

1977-01-01

Investigation of photoabsorption experiments in the spherical nucleus 141 Pr, the quasispherical dynamically deformed 197 Au, and the statically deformed 165 Ho showed that the function which describes best the energy dependence of the reduced transition probability is given by the Breit-Wigner form rather than the Lorentz form. However, the form of the resulting measured cross section is approximately of the Lorentz type. The dependence of the giant resonance width GAMMA on the excitation energy was also investigated, and found to be less than 1% per MeV if one considered the known isovector E2 resonance above the giant dipole resonance. Best fit values of the reduced transition probabilities for the three nuclei are given and compared to (e,e') results. (Auth.)

The Impact of Injector-Based Contrast Agent Administration on Bolus Shape and Magnetic Resonance Angiography Image Quality.

Science.gov (United States)

Jost, Gregor; Endrikat, Jan; Pietsch, Hubertus

2017-01-01

To compare injector-based contrast agent (CA) administration with hand injection in magnetic resonance angiography (MRA). Gadobutrol was administered in 6 minipigs with 3 protocols: (a) hand injection (one senior technician), (b) hand injection (6 less-experienced technicians), and (c) power injector administration. The arterial bolus shape was quantified by test bolus measurements. A head and neck MRA was performed for quantitative and qualitative comparison of signal enhancement. A significantly shorter time to peak was observed for protocol C, whereas no significant differences between protocols were found for peak height and bolus width. However, for protocol C, these parameters showed a much lower variation. The MRA revealed a significantly higher signal-to-noise ratio for injector-based administration. A superimposed strong contrast of the jugular vein was found in 50% of the hand injections. Injector-based CA administration results in a more standardized bolus shape, a higher vascular contrast, and a more robust visualization of target vessels.

The Impact of Injector-Based Contrast Agent Administration on Bolus Shape and Magnetic Resonance Angiography Image Quality

Directory of Open Access Journals (Sweden)

Gregor Jost

2017-04-01

Full Text Available Objective: To compare injector-based contrast agent (CA administration with hand injection in magnetic resonance angiography (MRA. Methods: Gadobutrol was administered in 6 minipigs with 3 protocols: (a hand injection (one senior technician, (b hand injection (6 less-experienced technicians, and (c power injector administration. The arterial bolus shape was quantified by test bolus measurements. A head and neck MRA was performed for quantitative and qualitative comparison of signal enhancement. Results: A significantly shorter time to peak was observed for protocol C, whereas no significant differences between protocols were found for peak height and bolus width. However, for protocol C, these parameters showed a much lower variation. The MRA revealed a significantly higher signal-to-noise ratio for injector-based administration. A superimposed strong contrast of the jugular vein was found in 50% of the hand injections. Conclusions: Injector-based CA administration results in a more standardized bolus shape, a higher vascular contrast, and a more robust visualization of target vessels.

Static current-sheet models of quiescent prominences

Science.gov (United States)

Wu, F.; Low, B. C.

1986-12-01

A particular class of theoretical models idealize the prominence to be a discrete flat electric-current sheet suspended vertically in a potential magnetic field. The weight of the prominence is supported by the Lorentz force in the current sheet. These models can be extended to have curved electric-current sheets and to vary three-dimensionally. The equation for force balance is 1 over 4 pi (del times B) times Bdel p- p9 z=zero. Using Cartesian coordinates we take, for simplicity, a uniform gravity with constant acceleration g in the direction -z. If we are interested not in the detailed internal structure of the prominence, but in the global magnetic configuration around the prominence, we may take prominence plasma to be cold. Consideration is given to how such equilibrium states can be constructed. To simplify the mathematical problem, suppose there is no electric current in the atmosphere except for the discrete currents in the cold prominence sheet. Let us take the plane z =0 to be the base of the atmosphere and restrict our attention to the domain z greater than 0. The task we have is to solve for a magnetic field which is everywhere potential except on some free surface S, subject to suit able to boundary conditions. The surface S is determined by requiring that it possesses a discrete electric current density such that the Lorentz force on it is everywhere vertically upward to balance the weight of the material m(S). Since the magnetic field is potential in the external atmosphere, the latter is decoupled from the magnetic field and its plane parallel hydrostatic pressure and density can be prescribed.

Neutral Atom Diffusion in a Partially Ionized Prominence Plasma

Science.gov (United States)

Gilbert, Holly

2010-01-01

The support of solar prominences is normally described in terms of a magnetic force on the prominence plasma that balances the solar gravitational force. Because the prominence plasma is only partially ionized. it is necessary to consider in addition the support of the neutral component of the prominence plasma. This support is accomplished through a frictional interaction between the neutral and ionized components of the plasma, and its efficacy depends strongly on the degree of ionization of the plasma. More specifically, the frictional force is proportional to the relative flow of neutral and ion species, and for a sufficiently weakly ionized plasma, this flow must be relatively large to produce a frictional force that balances gravity. A large relative flow, of course, implies significant draining of neutral particles from the prominence. We evaluate the importance of this draining effect for a hydrogen-helium plasma, and consider the observational evidence for cross-field diffusion of neutral prominence material,

Roof Box Shape Streamline Adaptation and the Impact towards Fuel Consumption

Directory of Open Access Journals (Sweden)

Abdul Latif M.F.

2017-01-01

Full Text Available The fuel price hike is currently a sensational national issue in Malaysia. Since the rationalization of fuel subsidies many were affected especially the middle income family. Vehicle aerodynamic were directly related to the fuel consumption, were extra frontal area result a higher drag force hence higher fuel consumption. Roof box were among the largest contributor to the extra drag, thus the roof box shape rationalization were prominent to reduce the extra drag. The idea of adopting water drop shape to the roof box design shows prominent result. The roof box has been simulated using MIRA virtual wind tunnel modelling via commercial computational fluid dynamic (CFD package. This streamline shape drastically reduce the drag force by 34% resulting to a 1.7% fuel saving compare to the conventional boxy roof box. This is an effort to reduce the carbon foot print for a sustainable green world.

On channel selection and shape co-existence

International Nuclear Information System (INIS)

Dracoulis, G.D.

1993-08-01

Ambivalence with respect to a favoured shape is emerging as a ubiquitous phenomenon in nuclei. Multiple minima in the nuclear potential well occur because of the delicate balance in nuclei between the long and short-range properties of the nuclear force and the contribution specific particle orbitals make in forcing the nucleus to a decision. Exploration of the dependence of the resulting shape co-existence on particle number and orbital is a prominent area of research. Experimental aspects of spectroscopy studies using heavy ion fusion, evaporation reactions and channel selection are discussed, with focus on shape co-existence in the light Os-Pt-Hg-Pb region. 42 refs., 8 figs

A novel L-shaped linear ultrasonic motor operating in a single resonance mode

Science.gov (United States)

Zhang, Bailiang; Yao, Zhiyuan; Liu, Zhen; Li, Xiaoniu

2018-01-01

In this study, a large thrust linear ultrasonic motor using an L-shaped stator is described. The stator is constructed by two mutually perpendicular rectangular plate vibrators, one of which is mounted in parallel with the slider to make the motor structure to be more compact. The symmetric and antisymmetric modes of the stator based on the first order bending vibration of two vibrators are adopted, in which each resonance mode is assigned to drive the slider in one direction. The placement of piezoelectric ceramics in a stator could be determined by finite element analysis, and the influence of slots in the head block on the vibration amplitudes of driving foot was studied as well. Three types of prototypes (non-slotted, dual-slot, and single-slot) were fabricated and experimentally investigated. Experimental results demonstrated that the prototype with one slot exhibited the best mechanical output performance. The maximum loads under the excitation of symmetric mode and antisymmetric mode were 65 and 90 N, respectively.

Theoretical and experimental study on electron interactions with chlorobenzene: Shape resonances and differential cross sections

Energy Technology Data Exchange (ETDEWEB)

Barbosa, Alessandra Souza [Departamento de Física, Universidade Federal do Paraná, CP 19044, 81531-990 Curitiba, Paraná (Brazil); Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Varella, Márcio T. do N. [Instituto de Física, Universidade de São Paulo, Rua do Matão 1731, 05508-090 São Paulo, SP (Brazil); Sanchez, Sergio d’A.; Bettega, Márcio H. F., E-mail: bettega@fisica.ufpr.br [Departamento de Física, Universidade Federal do Paraná, CP 19044, 81531-990 Curitiba, Paraná (Brazil); Ameixa, João; Limão-Vieira, Paulo; Ferreira da Silva, Filipe [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Blanco, Francisco [Departamento de Física Atómica, Molecular y Nuclear, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); and others

2016-08-28

In this work, we report theoretical and experimental cross sections for elastic scattering of electrons by chlorobenzene (ClB). The theoretical integral and differential cross sections (DCSs) were obtained with the Schwinger multichannel method implemented with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR). The calculations with the SMCPP method were done in the static-exchange (SE) approximation, for energies above 12 eV, and in the static-exchange plus polarization approximation, for energies up to 12 eV. The calculations with the IAM-SCAR method covered energies up to 500 eV. The experimental differential cross sections were obtained in the high resolution electron energy loss spectrometer VG-SEELS 400, in Lisbon, for electron energies from 8.0 eV to 50 eV and angular range from 7{sup ∘} to 110{sup ∘}. From the present theoretical integral cross section (ICS) we discuss the low-energy shape-resonances present in chlorobenzene and compare our computed resonance spectra with available electron transmission spectroscopy data present in the literature. Since there is no other work in the literature reporting differential cross sections for this molecule, we compare our theoretical and experimental DCSs with experimental data available for the parent molecule benzene.

Inductive Cross Shaped Metal Meshes in Silicon Substrate

National Research Council Canada - National Science Library

Sternberg, O; Moller, K. D; Grebel, H; Stewart, K. P; Henry, R. M

2002-01-01

.... The Micro-Stripes program was used for the calculation of resonance wavelength and width of resonance of cross shaped metal meshes and best- fit formulas were developed for the presentation of the data...

Characterization of the Bell-Shaped Vibratory Angular Rate Gyro

Directory of Open Access Journals (Sweden)

Junfang Fan

2013-08-01

Full Text Available The bell-shaped vibratory angular rate gyro (abbreviated as BVG is a novel shell vibratory gyroscope, which is inspired by the Chinese traditional bell. It sensitizes angular velocity through the standing wave precession effect. The bell-shaped resonator is a core component of the BVG and looks like the millimeter-grade Chinese traditional bell, such as QianLong Bell and Yongle Bell. It is made of Ni43CrTi, which is a constant modulus alloy. The exciting element, control element and detection element are uniformly distributed and attached to the resonator, respectively. This work presents the design, analysis and experimentation on the BVG. It is most important to analyze the vibratory character of the bell-shaped resonator. The strain equation, internal force and the resonator's equilibrium differential equation are derived in the orthogonal curvilinear coordinate system. When the input angular velocity is existent on the sensitive axis, an analysis of the vibratory character is performed using the theory of thin shells. On this basis, the mode shape function and the simplified second order normal vibration mode dynamical equation are obtained. The coriolis coupling relationship about the primary mode and secondary mode is established. The methods of the signal processing and control loop are presented. Analyzing the impact resistance property of the bell-shaped resonator, which is compared with other shell resonators using the Finite Element Method, demonstrates that BVG has the advantage of a better impact resistance property. A reasonable means of installation and a prototypal gyro are designed. The gyroscopic effect of the BVG is characterized through experiments. Experimental results show that the BVG has not only the advantages of low cost, low power, long work life, high sensitivity, and so on, but, also, of a simple structure and a better impact resistance property for low and medium angular velocity measurements.

New properties of giant resonances in highly excited nuclei

International Nuclear Information System (INIS)

Morsch, H.P.

1991-01-01

Studies on the giant dipole resonance in very hot nuclei investigated in heavy ion-induced particle-γ coincidence experiments are reviewed. A signature is found in the γ-decay of excited nuceli which shows direct decay of the giant dipole resonance. This provides a new dimension in giant resonance studies and the possibility to study the dependence of giant resonance energy, width and sum rule strength on excitation energy and rotation of the system. Further, the fact that the giant resonance splits in deformed nuclei provides a unique way to get information on the shape of hot nuclei. First results are obtained on the following questions: (i)What is the nuclear shape at high temperature (T≥2 MeV)? (ii)Is there a phase transition in the nuclear shape at T∼1.7 MeV? (iii)Does motional narrowing exist in hot nuclei? (author). 19 refs., 11 figs

Solar Tornado Prominences: Plasma Motions Along Filament Barbs

Science.gov (United States)

Panasenco, Olga; Velli, Marco; Martin, Sara F.; Rappazzo, Franco

2013-03-01

Recent high-resolution observations from the Solar Dynamic Observatory (SDO) have reawakened interest in the old and fascinating phenomenon of solar tornado prominences. This class of prominences was first introduced by E. Pettit in 1932, who studied them over many years up to 1950. High resolution and high cadence multi-wavelength data obtained by SDO reveal that the tornado-like properties of these prominences are mainly an illusion due to projection effects. We show that counterstreaming plasma motions with projected velocities up to +/- 45 km/sec along the prominence spine and barbs create a tornado-like impression when viewed at the limb. We demonstrate that barbs are often rooted at the intersection between 4-5 supergranular cells. We discuss the observed oscillations along the vertical parts of barbs and whether they may be related to vortex flows coming from the convection downdrafts at the intersection of supergranules (and possibly smaller convective cells) in the photosphere and their entrained magnetic field. The unwinding of magnetic threads near the photosphere via reconnection might be a source of the waves which are observed as oscillations in prominence barbs.

MAGNETIC FIELD IN ATYPICAL PROMINENCE STRUCTURES: BUBBLE, TORNADO, AND ERUPTION

Energy Technology Data Exchange (ETDEWEB)

Levens, P. J.; Labrosse, N. [SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Schmieder, B. [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, F-92195 Meudon (France); López Ariste, A. [IRAP—CNRS UMR 5277, 14, Av. E. Belin, F-31400 Toulouse (France); Dalmasse, K. [CISL/HAO, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Gelly, B., E-mail: p.levens.1@research.gla.ac.uk, E-mail: brigitte.schmieder@obspm.fr [CNRS UMR 3718 THEMIS, La Laguna, Tenerife (Spain)

2016-08-01

Spectropolarimetric observations of prominences have been obtained with the THEMIS telescope during four years of coordinated campaigns. Our aim is now to understand the conditions of the cool plasma and magnetism in “atypical” prominences, namely when the measured inclination of the magnetic field departs, to some extent, from the predominantly horizontal field found in “typical” prominences. What is the role of the magnetic field in these prominence types? Are plasma dynamics more important in these cases than the magnetic support? We focus our study on three types of “atypical” prominences (tornadoes, bubbles, and jet-like prominence eruptions) that have all been observed by THEMIS in the He i D{sub 3} line, from which the Stokes parameters can be derived. The magnetic field strength, inclination, and azimuth in each pixel are obtained by using the inversion method of principal component analysis on a model of single scattering in the presence of the Hanle effect. The magnetic field in tornadoes is found to be more or less horizontal, whereas for the eruptive prominence it is mostly vertical. We estimate a tendency toward higher values of magnetic field strength inside the bubbles than outside in the surrounding prominence. In all of the models in our database, only one magnetic field orientation is considered for each pixel. While sufficient for most of the main prominence body, this assumption appears to be oversimplified in atypical prominence structures. We should consider these observations as the result of superposition of multiple magnetic fields, possibly even with a turbulent field component.

The role of resonances in chiral perturbation theory

International Nuclear Information System (INIS)

Ecker, G.; Rafael, E. de

1988-09-01

The strong interactions of low-lying meson resonances (spin ≤ 1) with the octet of pseudoscalar mesons (π,Κ,η) are considered to lowest order in the derivative expansion of chiral SU(3). The resonance contributions to the coupling constants of the O(p 4 ) effective chiral lagrangian involving pseudoscalar fields only are determined. These low-energy coupling constants are found to be dominated by the resonance contributions. Although we do not treat the vector and axial-vector mesons as gauge bosons of local chiral symmetry, vector meson dominance emerges as a prominent result of our analysis. As a further application of chiral resonance couplings, we calculate the electromagnetic pion mass difference to lowest order in chiral perturbation theory with explicit resonance fields. 29 refs., 2 figs., 5 tabs. (Author)

Polarization insensitive metamaterial absorber based on E-shaped all-dielectric structure

Directory of Open Access Journals (Sweden)

Liyang Li

2015-03-01

Full Text Available In this paper, we designed a metamaterial absorber performed in microwave frequency band. This absorber is composed of E-shaped dielectrics which are arranged along different directions. The E-shaped all-dielectric structure is made of microwave ceramics with high permittivity and low loss. Within about 1 GHz frequency band, more than 86% absorption efficiency was observed for this metamaterial absorber. This absorber is polarization insensitive and is stable for incident angles. It is figured out that the polarization insensitive absorption is caused by the nearly located varied resonant modes which are excited by the E-shaped all-dielectric resonators with the same size but in the different direction. The E-shaped dielectric absorber contains intensive resonant points. Our research work paves a way for designing all-dielectric absorber.

The Computational Processing of Intonational Prominence: A Functional Prosody Perspective

OpenAIRE

Nakatani, Christine Hisayo

1997-01-01

Intonational prominence, or accent, is a fundamental prosodic feature that is said to contribute to discourse meaning. This thesis outlines a new, computational theory of the discourse interpretation of prominence, from a FUNCTIONAL PROSODY perspective. Functional prosody makes the following two important assumptions: first, there is an aspect of prominence interpretation that centrally concerns discourse processes, namely the discourse focusing nature of prominence; and second, the role of p...

Phase modulation and structural effects in a D-shaped all-solid photonic crystal fiber surface plasmon resonance sensor.

Science.gov (United States)

Tan, Zhixin; Hao, Xin; Shao, Yonghong; Chen, Yuzhi; Li, Xuejin; Fan, Ping

2014-06-16

We numerically investigate a D-shaped fiber surface plasmon resonance sensor based on all-solid photonic crystal fiber (PCF) with finite element method. In the side-polished PCF sensor, field leakage is guided to penetrate through the gap between the rods, causing a pronounced phase modulation in the deep polishing case. Taking advantage of these amplified phase shifts, a high-performance fiber sensor design is proposed. The significant enhancements arising from this new sensor design should lift the performance of the fiber SPR sensor into the range capable of detecting a wide range of biochemical interactions, which makes it especially attractive for many in vivo and in situ bioanalysis applications. Several parameters which influence the field leakage, such as the polishing position, the pitch of the PCF, and the rod diameter, are inspected to evaluate their impacts. Furthermore, we develop a mathematical model to describe the effects of varying the structural parameters of a D-shaped PCF sensor on the evanescent field and the sensor performance.

Observation of Point-Light-Walker Locomotion Induces Motor Resonance When Explicitly Represented; An EEG Source Analysis Study

Directory of Open Access Journals (Sweden)

Alberto Inuggi

2018-03-01

Full Text Available Understanding human motion, to infer the goal of others' actions, is thought to involve the observer's motor repertoire. One prominent class of actions, the human locomotion, has been object of several studies, all focused on manipulating the shape of degraded human figures like point-light walker (PLW stimuli, represented as walking on the spot. Nevertheless, since the main goal of the locomotor function is to displace the whole body from one position to the other, these stimuli might not fully represent a goal-directed action and thus might not be able to induce the same motor resonance mechanism expected when observing a natural locomotion. To explore this hypothesis, we recorded the event-related potentials (ERP of canonical/scrambled and translating/centered PLWs decoding. We individuated a novel ERP component (N2c over central electrodes, around 435 ms after stimulus onset, for translating compared to centered PLW, only when the canonical shape was preserved. Consistently with our hypothesis, sources analysis associated this component to the activation of trunk and lower legs primary sensory-motor and supplementary motor areas. These results confirm the role of own motor repertoire in processing human action and suggest that ERP can detect the associated motor resonance only when the human figure is explicitly involved in performing a meaningful action.

Magnetic Field-Vector Measurements in Quiescent Prominences via the Hanle Effect: Analysis of Prominences Observed at Pic-Du-Midi and at Sacramento Peak

Science.gov (United States)

Bommier, V.; Leroy, J. L.; Sahal-Brechot, S.

1985-01-01

The Hanle effect method for magnetic field vector diagnostics has now provided results on the magnetic field strength and direction in quiescent prominences, from linear polarization measurements in the He I E sub 3 line, performed at the Pic-du-Midi and at Sacramento Peak. However, there is an inescapable ambiguity in the field vector determination: each polarization measurement provides two field vector solutions symmetrical with respect to the line-of-sight. A statistical analysis capable of solving this ambiguity was applied to the large sample of prominences observed at the Pic-du-Midi (Leroy, et al., 1984); the same method of analysis applied to the prominences observed at Sacramento Peak (Athay, et al., 1983) provides results in agreement on the most probable magnetic structure of prominences; these results are detailed. The statistical results were confirmed on favorable individual cases: for 15 prominences observed at Pic-du-Midi, the two-field vectors are pointing on the same side of the prominence, and the alpha angles are large enough with respect to the measurements and interpretation inaccuracies, so that the field polarity is derived without any ambiguity.

Linear signal processing using silicon micro-ring resonators

DEFF Research Database (Denmark)

Peucheret, Christophe; Ding, Yunhong; Ou, Haiyan

2012-01-01

We review our recent achievements on the use of silicon micro-ring resonators for linear optical signal processing applications, including modulation format conversion, phase-to-intensity modulation conversion and waveform shaping.......We review our recent achievements on the use of silicon micro-ring resonators for linear optical signal processing applications, including modulation format conversion, phase-to-intensity modulation conversion and waveform shaping....

PROMINENCE ACTIVATION BY CORONAL FAST MODE SHOCK

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Takuya [Department of Astronomy, Kyoto University, Sakyo, Kyoto, 606-8502 (Japan); Asai, Ayumi [Unit of Synergetic Studies for Space, Kyoto University, Yamashina, Kyoto 607-8471 (Japan); Shibata, Kazunari, E-mail: takahashi@kwasan.kyoto-u.ac.jp [Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto 607-8471 (Japan)

2015-03-01

An X5.4 class flare occurred in active region NOAA11429 on 2012 March 7. The flare was associated with a very fast coronal mass ejection (CME) with a velocity of over 2500 km s{sup −1}. In the images taken with the Solar Terrestrial Relations Observatory-B/COR1, a dome-like disturbance was seen to detach from an expanding CME bubble and propagated further. A Type-II radio burst was also observed at the same time. On the other hand, in extreme ultraviolet images obtained by the Solar Dynamic Observatory/Atmospheric Imaging Assembly (AIA), the expanding dome-like structure and its footprint propagating to the north were observed. The footprint propagated with an average speed of about 670 km s{sup −1} and hit a prominence located at the north pole and activated it. During the activation, the prominence was strongly brightened. On the basis of some observational evidence, we concluded that the footprint in AIA images and the ones in COR1 images are the same, that is, the MHD fast mode shock front. With the help of a linear theory, the fast mode Mach number of the coronal shock is estimated to be between 1.11 and 1.29 using the initial velocity of the activated prominence. Also, the plasma compression ratio of the shock is enhanced to be between 1.18 and 2.11 in the prominence material, which we consider to be the reason for the strong brightening of the activated prominence. The applicability of linear theory to the shock problem is tested with a nonlinear MHD simulation.

V-shaped resonators for addition of broad-area laser diode arrays

Science.gov (United States)

Liu, Bo; Liu, Yun; Braiman, Yehuda Y.

2012-12-25

A system and method for addition of broad-area semiconductor laser diode arrays are described. The system can include an array of laser diodes, a V-shaped external cavity, and grating systems to provide feedback for phase-locking of the laser diode array. A V-shaped mirror used to couple the laser diode emissions along two optical paths can be a V-shaped prism mirror, a V-shaped stepped mirror or include multiple V-shaped micro-mirrors. The V-shaped external cavity can be a ring cavity. The system can include an external injection laser to further improve coherence and phase-locking.

FANAC - a shape analysis program for resonance parameter extraction from neutron capture data for light and medium-weight nuclei

International Nuclear Information System (INIS)

Froehner, F.H.

1977-11-01

A least-squares shape analysis program is described which is used at the Karlsruhe Nuclear Research Center for the extraction of resonance parameters from high-resolution capture data. The FORTRAN program was written for light to medium-weight or near-magic target nuclei whose cross sections are characterized on one hand by broad s-wave levels with negligible Doppler broadening but pronounced multi-level interference, on the other hand by narrow p-, d- ... wave resonances with negligible multi-level interference but pronounced Doppler broadening. Accordingly the Reich-Moore multi-level formalism without Doppler broadening is used for s-wave levels, and a single-level description with Doppler braodening for p-, d- ... wave levels. Calculated capture yields are resolution broadened. Multiple-collision events are simulated by Monte Carlo techniques. Up to five different time-of-flight capture data sets can be fitted simultaneously for samples containing up to ten isotopes. Input and output examples are given and a FORTRAN list is appended. (orig.)

Shape dependent resonance light scattering properties of gold nanorods

International Nuclear Information System (INIS)

Zhu Jian; Huang Liqing; Zhao Junwu; Wang Yongchang; Zhao Yanrui; Hao Limei; Lu Yimin

2005-01-01

Suspended gold nanorods with mean aspect ratio 2.5 have been synthesized via electrochemical method. Resonance scattering properties have been studied. Two scattering peaks fixed at 400 and 640 nm are due to the scattering of the gold nanorods via coupling to the transverse and longitudinal surface plasmon resonance. The quasi-static calculation results indicate that with the increasing aspect ratio of the nanorods, the longer wavelength scattering peak red shifts linearly and the shorter wavelength peak blue shifts non-linearly. When aspect ratio a/b = 1.0, ellipse degenerate to sphere and the two peaks unite into one peak at 450 nm

Modeling self-occlusions in dynamic shape and appearance tracking

KAUST Repository

Yang, Yanchao

2013-12-01

We present a method to track the precise shape of a dynamic object in video. Joint dynamic shape and appearance models, in which a template of the object is propagated to match the object shape and radiance in the next frame, are advantageous over methods employing global image statistics in cases of complex object radiance and cluttered background. In cases of complex 3D object motion and relative viewpoint change, self-occlusions and disocclusions of the object are prominent, and current methods employing joint shape and appearance models are unable to accurately adapt to new shape and appearance information, leading to inaccurate shape detection. In this work, we model self-occlusions and dis-occlusions in a joint shape and appearance tracking framework. Experiments on video exhibiting occlusion/dis-occlusion, complex radiance and background show that occlusion/dis-occlusion modeling leads to superior shape accuracy compared to recent methods employing joint shape/appearance models or employing global statistics. © 2013 IEEE.

Los resonance lines in promethiumlike heavy ions

International Nuclear Information System (INIS)

Nakamura, Nobuyuki; Kobayashi, Yusuke; Kato, Daiji; Sakaue, Hiroyuki A.; Murakami, Izumi

2016-01-01

Identifying the ns - np resonance lines in alkali-metal-like ions is an important issue in fusion plasma science in the view of spectroscopic diagnostics and radiation power loss. Whereas for n=2, 3 and 4 these resonances are prominent and well studied, so far no one could clearly identify the resonance lines for n=5 in the promethiumlike sequence. We have now experimentally clarified the reason for the 'lost resonance lines. In the present study, highly-charged bismuth ions have been studied using a compact electron beam ion trap (EBIT). Extreme ultraviolet emission from the bismuth ions produced and trapped in the EBIT is observed with a grazing-incidence flat-field spectrometer. The energy dependent spectra are compared with a collisional-radiative model calculation, and we show that the 5s - 5p resonance lines are very weak in plasma with a wide range of electron density due to the presence of a long-lived metastable state. (author)

Magnetic Resonance Flow Velocity and Temperature Mapping of a Shape Memory Polymer Foam Device

Energy Technology Data Exchange (ETDEWEB)

Small IV, W; Gjersing, E; Herberg, J L; Wilson, T S; Maitland, D J

2008-10-29

Interventional medical devices based on thermally responsive shape memory polymer (SMP) are under development to treat stroke victims. The goals of these catheter-delivered devices include re-establishing blood flow in occluded arteries and preventing aneurysm rupture. Because these devices alter the hemodynamics and dissipate thermal energy during the therapeutic procedure, a first step in the device development process is to investigate fluid velocity and temperature changes following device deployment. A laser-heated SMP foam device was deployed in a simplified in vitro vascular model. Magnetic resonance imaging (MRI) techniques were used to assess the fluid dynamics and thermal changes associated with device deployment. Spatial maps of the steady-state fluid velocity and temperature change inside and outside the laser-heated SMP foam device were acquired. Though non-physiological conditions were used in this initial study, the utility of MRI in the development of a thermally-activated SMP foam device has been demonstrated.

A prominent lactate peak as a potential key magnetic resonance spectroscopy (MRS feature of progressive multifocal leukoencephalopathy (PML: Spectrum pattern observed in three patients

Directory of Open Access Journals (Sweden)

Duško Kozić

2017-11-01

Full Text Available Progressive multifocal leukoencephalopathy (PML is a rare, often fatal, opportunistic infection, associated with demyelinating process. PML is caused by John Cunningham (JC polyomavirus, and predominantly affects patients with human immunodeficiency virus (HIV infection or other immunocompromised patients. The purpose of this study was to determine the role of magnetic resonance spectroscopy (MRS in establishing the diagnosis of PML. MRS with long and short echo time was performed in two patients with PML associated with HIV infection and in one PML patient associated with chronic lymphocytic leukemia. The most prominent peak on the obtained spectra was for lactate; it showed 2-3 times higher concentration of lactate compared to choline, almost 4-6 times higher lactate concentration compared to creatine, and 4-11 times higher lactate in comparison to N-acetylaspartate concentration. Similar spectrum pattern was observed in all patients. To the best of our knowledge, this is a new finding that might be useful in early diagnosis of PML. Nevertheless, further confirmation of our results is needed, since we analyzed the spectrum pattern only in three patients. Overall, our results could help in early detection of PML, especially in non-HIV patients, and thus prevent the fatal outcome of the disease. MRS could also be useful in detecting “tumefactive” demyelinating lesions in PML patients, associated with immune reconstitution inflammatory syndrome, to avoid misdiagnosis of neoplasm.

Listening to the Shape of a Drum

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 10. Listening to the Shape of a Drum - You Cannot Hear the Shape of a Drum! S Kesavan. General Article Volume 3 Issue 10 October 1998 pp 49-58. Fulltext. Click here to view fulltext PDF. Permanent link:

Autoionization spectral line shapes in dense plasmas

International Nuclear Information System (INIS)

Rosmej, F.B.; Hoffmann, D.H.H.; Faenov, A.Ya.; Pikuz, T.A.; Suess, W.; Geissel, M.

2001-01-01

The distortion of resonance line shapes due to the accumulation of a large number of satellite transitions is discovered by means of X-ray optical methods with simultaneous high spectral (λ/δλ≅8000) and spatial resolution (δx≅7 μm). Disappearance of the He α resonance line emission near the target surface is observed while Rydberg satellite intensity accumulates near the resonance line position. He β and He γ resonance line shapes are also shown to be seriously affected by opacity, higher-order line emissions from autoionizing states and inhomogeneous spatial emission. Opposite to resonance line emissions the He β satellites originate only from a very narrow spatial interval. New temperature and density diagnostics employing the 1s2131' and 1s3131'-satellites are developed. Moreover, even-J components of the satellite line emissions were resolved in the present high resolution experiments. Line transitions from the autoionizing states 1s2131' are therefore also proposed for space resolved Stark broadening analysis and local high density probing. Theorists are encouraged to provide accurate Stark broadening data for the transitions 1s2131 ' →1s 2 21+hv

Solar Magnetized Tornadoes: Rotational Motion in a Tornado-like Prominence

Science.gov (United States)

Su, Yang; Gömöry, Peter; Veronig, Astrid; Temmer, Manuela; Wang, Tongjiang; Vanninathan, Kamalam; Gan, Weiqun; Li, YouPing

2014-04-01

Su et al. proposed a new explanation for filament formation and eruption, where filament barbs are rotating magnetic structures driven by underlying vortices on the surface. Such structures have been noticed as tornado-like prominences when they appear above the limb. They may play a key role as the source of plasma and twist in filaments. However, no observations have successfully distinguished rotational motion of the magnetic structures in tornado-like prominences from other motions such as oscillation and counter-streaming plasma flows. Here we report evidence of rotational motions in a tornado-like prominence. The spectroscopic observations in two coronal lines were obtained from a specifically designed Hinode/EIS observing program. The data revealed the existence of both cold and million-degree-hot plasma in the prominence leg, supporting the so-called prominence-corona transition region. The opposite velocities at the two sides of the prominence and their persistent time evolution, together with the periodic motions evident in SDO/AIA dark structures, indicate a rotational motion of both cold and hot plasma with a speed of ~5 km s-1.

KIC 8164262: a heartbeat star showing tidally induced pulsations with resonant locking

Science.gov (United States)

Hambleton, K.; Fuller, J.; Thompson, S.; Prša, A.; Kurtz, D. W.; Shporer, A.; Isaacson, H.; Howard, A. W.; Endl, M.; Cochran, W.; Murphy, S. J.

2018-02-01

We present the analysis of KIC 8164262, a heartbeat star with a high-amplitude (∼1 mmag), tidally resonant pulsation (a mode in resonance with the orbit) at 229 times the orbital frequency and a plethora of tidally induced g-mode pulsations (modes excited by the orbit). The analysis combines Kepler light curves with follow-up spectroscopic data from the Keck telescope, KPNO (Kitt Peak National Observatory) 4-m Mayall telescope and the 2.7-m telescope at the McDonald observatory. We apply the binary modelling software, PHOEBE, to the Kepler light curve and radial velocity data to determine a detailed binary star model that includes the prominent pulsation and Doppler boosting, alongside the usual attributes of a binary star model (including tidal distortion and reflection). The results show that the system contains a slightly evolved F star with an M secondary companion in a highly eccentric orbit (e = 0.886). We use the results of the binary star model in a companion paper (Fuller) where we show that the prominent pulsation can be explained by a tidally excited oscillation mode held near resonance by a resonance locking mechanism.

Reconnection–Condensation Model for Solar Prominence Formation

Energy Technology Data Exchange (ETDEWEB)

Kaneko, Takafumi [Institute for Space-Earth Environmental Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601 (Japan); Yokoyama, Takaaki, E-mail: kaneko@isee.nagoya-u.ac.jp [Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2017-08-10

We propose a reconnection–condensation model in which topological change in a coronal magnetic field via reconnection triggers radiative condensation, thereby resulting in prominence formation. Previous observational studies have suggested that reconnection at a polarity inversion line of a coronal arcade field creates a flux rope that can sustain a prominence; however, they did not explain the origin of cool dense plasmas of prominences. Using three-dimensional magnetohydrodynamic simulations, including anisotropic nonlinear thermal conduction and optically thin radiative cooling, we demonstrate that reconnection can lead not only to flux rope formation but also to radiative condensation under a certain condition. In our model, this condition is described by the Field length, which is defined as the scale length for thermal balance between radiative cooling and thermal conduction. This critical condition depends weakly on the artificial background heating. The extreme ultraviolet emissions synthesized with our simulation results have good agreement with observational signatures reported in previous studies.

The effect of magnetic stress and stiffness modulus on resonant characteristics of Ni-Mn-Ga ferromagnetic shape memory alloy actuators

International Nuclear Information System (INIS)

Techapiesancharoenkij, Ratchatee; Kostamo, Jari; Allen, Samuel M.; O'Handley, Robert C.

2011-01-01

The prospect of using ferromagnetic shape memory alloys (FSMAs) is promising for a resonant actuator that requires large strain output and a drive frequency below 1 kHz. In this investigation, three FSMA actuators, equipped with tetragonal off-stoichiometric Ni 2 MnGa single crystals, were developed to study their frequency response and resonant characteristics. The first actuator, labeled as A1, was constructed with low-k bias springs and one Ni-Mn-Ga single crystal. The second actuator, labeled as A2, was constructed with high-k bias springs and one Ni-Mn-Ga crystal. The third actuator, labeled as A3, was constructed with high-k bias springs and two Ni-Mn-Ga crystals connected in parallel. The three actuators were magnetically driven over the frequency range of 10 Hz-1 kHz under 2 and 3.5 kOe magnetic-field amplitudes. The field amplitude of 2 kOe is insufficient to generate significant strain output from all three actuators; the maximum magnetic-field-induced strain (MFIS) at resonance is 2%. The resonant MFIS output improves to 5% under 3.5-kOe amplitude. The frequency responses of all three actuators show a strong effect of the spring k constant and the Ni-Mn-Ga modulus stiffness on the resonant frequencies. The resonant frequency of the Ni-Mn-Ga actuator was raised from 450 to 650 Hz by increasing bias spring k constant and/or the number of Ni-Mn-Ga crystals. The higher number of the Ni-Mn-Ga crystals not only increases the magnetic force output but also raises the total stiffness of the actuator resulting in a higher resonant frequency. The effective modulus of the Ni-Mn-Ga is calculated from the measured resonant frequencies using the mass-spring equation; the calculated modulus values for the three actuators fall in the range of 50-60 MPa. The calculated effective modulus appears to be close to the average modulus value between the low twinning modulus and high elastic modulus of the untwined Ni-Mn-Ga crystal. - Highlights: → Dynamic FSMA actuation shows

Neutron cross sections in the unresolved resonance region

International Nuclear Information System (INIS)

Janeva, N.; Lukyanov, A.; Koyumdjieva, N.; Volev, K.

2005-01-01

In this work a development of the characteristic function model, created to reveal the resonance cross section structure in the unresolved resonance region is presented. The main advantage of this model is the calculation of resonance averaged self-shielding factors analytically. To determine average values of the cross sections and their functionals the function of joint statistical distribution of the R-matrix real and imaginary parts should be used. The characteristic function of such distribution is determined and the resonance ladder for the unresolved region is optimized to calculate the group averaged functionals in the same way as it is in the resolved resonance region. The main advantage of this model is the calculation of resonance averaged self-shielding factors analytically. The neutron width energy dependence leads to some deformation in the shape of resonances. This deformation is most apparent near the inelastic scattering threshold. For the case when the inelastic channel momentum is zero we present the formula for level shape bellow and over the inelastic threshold and the calculated resonance deformation in dependence of the position of the resonance in respect to the threshold. (authors)

Spectra of resonance surface photoionization

Energy Technology Data Exchange (ETDEWEB)

Antsiferov, V.V.; Smirnov, G.I.; Telegin, G.G. [Budker Nuclear Physics Institute, Novosibirsk (Russian Federation)

1995-09-01

The theory of nonactivated electron transfer between atoms interacting reasonantly with coherent radiation and a metal surface is developed. The spectral resonances in photoabsorption and surface photoionization are found to be related to nonlinear interference effects in the interaction between discrete atomic levels and the continuum formed by the quasi-continuous electron spectrum of a normal metal. The asymmetry in the resonance surface photoionization spectrum is shown to have a shape typical of the Fano autoionization resonances. 18 refs.

Physics of solar prominences. Proceedings of the Colloquium, Oslo, Norway, August 14-18, 1978

Energy Technology Data Exchange (ETDEWEB)

Jensen, E; Maltby, P

1979-01-01

These papers deal with recent theoretical and observational studies of the physics of solar prominences. Specific topics include reviews of prominence spectra and their interpretation, polarimetric observations and magnetic-field determination in prominences, observations of the prominence-corona interface, theories on the formation and stability of quiescent prominences, prominence classifications, observations of active prominences, observations and interpretations of coronal manifestations of eruptive prominences, and models of prominence structure and dynamics. Other contributions discuss simultaneous observations of Ca II and hydrogen Balmer lines in quiescent prominences, recent results in quiescent-prominence spectroscopy, the solar helium abundance obtained from optical spectra of quiescent prominences, and Stokes polarimetry of quiescent prominences in the He I D3 line. Magnetic-field determination based on the Hanle effect is also examined, along with the orientation of prominence microstructure relative to magnetic-field direction, radio observations of quiescent-prominence filaments at centimeter and millimeter wavelengths, EUV observations of filaments, and a magnetic-field reconnection model of quiescent prominences.

Study of a Large Helical Eruptive Prominence Associated with ...

Indian Academy of Sciences (India)

2001-04-21

Apr 21, 2001 ... morphology of the event, energy budget of the prominence and associated. CMEs. ... magnetically driven and internally powered. Key words. ... Solar prominences are ribbons of cool (∼8000 K) dense gas (∼10. −11 gcm. −3. ) ...

SOLAR MAGNETIZED TORNADOES: ROTATIONAL MOTION IN A TORNADO-LIKE PROMINENCE

Energy Technology Data Exchange (ETDEWEB)

Su, Yang; Veronig, Astrid; Temmer, Manuela; Vanninathan, Kamalam [IGAM-Kanzelhöhe Observatory, Institute of Physics, University of Graz, Universitätsplatz 5, A-8010 Graz (Austria); Gömöry, Peter [Astronomical Institute of the Slovak Academy of Sciences, SK-05960 Tatranská Lomnica (Slovakia); Wang, Tongjiang [Department of Physics, the Catholic University of America, Washington, DC 20064 (United States); Gan, Weiqun; Li, YouPing, E-mail: yang.su@uni-graz.at [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

2014-04-10

Su et al. proposed a new explanation for filament formation and eruption, where filament barbs are rotating magnetic structures driven by underlying vortices on the surface. Such structures have been noticed as tornado-like prominences when they appear above the limb. They may play a key role as the source of plasma and twist in filaments. However, no observations have successfully distinguished rotational motion of the magnetic structures in tornado-like prominences from other motions such as oscillation and counter-streaming plasma flows. Here we report evidence of rotational motions in a tornado-like prominence. The spectroscopic observations in two coronal lines were obtained from a specifically designed Hinode/EIS observing program. The data revealed the existence of both cold and million-degree-hot plasma in the prominence leg, supporting the so-called prominence-corona transition region. The opposite velocities at the two sides of the prominence and their persistent time evolution, together with the periodic motions evident in SDO/AIA dark structures, indicate a rotational motion of both cold and hot plasma with a speed of ∼5 km s{sup –1}.

SOLAR MAGNETIZED TORNADOES: ROTATIONAL MOTION IN A TORNADO-LIKE PROMINENCE

International Nuclear Information System (INIS)

Su, Yang; Veronig, Astrid; Temmer, Manuela; Vanninathan, Kamalam; Gömöry, Peter; Wang, Tongjiang; Gan, Weiqun; Li, YouPing

2014-01-01

Su et al. proposed a new explanation for filament formation and eruption, where filament barbs are rotating magnetic structures driven by underlying vortices on the surface. Such structures have been noticed as tornado-like prominences when they appear above the limb. They may play a key role as the source of plasma and twist in filaments. However, no observations have successfully distinguished rotational motion of the magnetic structures in tornado-like prominences from other motions such as oscillation and counter-streaming plasma flows. Here we report evidence of rotational motions in a tornado-like prominence. The spectroscopic observations in two coronal lines were obtained from a specifically designed Hinode/EIS observing program. The data revealed the existence of both cold and million-degree-hot plasma in the prominence leg, supporting the so-called prominence-corona transition region. The opposite velocities at the two sides of the prominence and their persistent time evolution, together with the periodic motions evident in SDO/AIA dark structures, indicate a rotational motion of both cold and hot plasma with a speed of ∼5 km s –1

Autostereogram resonators

Science.gov (United States)

Leavey, Sean; Rae, Katherine; Murray, Adam; Courtial, Johannes

2012-09-01

Autostereograms, or "Magic Eye" pictures, are repeating patterns designed to give the illusion of depth. Here we discuss optical resonators that create light patterns which, when viewed from a suitable position by a monocular observer, are autostereograms of the three-dimensional shape of one of the mirror surfaces.

Prominence-corona interface compared with the chromosphere-corona transition region

Energy Technology Data Exchange (ETDEWEB)

Orrall, F Q; Schmahl, E J [Harvard Coll. Observatory, Cambridge, Mass. (USA)

1976-11-01

The intensities of 52 EUV emission lines from each of 9 hedgerow prominences observed at the limb with the Harvard experiment on ATM-Skylab have been compared with intensities from the interior of network cells at the center of the disk, in order to compare the prominence-corona (P-C) interface with the chromosphere-corona (C-C) transition region. The intensity ratio Isub(cell)/Isub(prominence) for each line varies systematically (in all of the prominences observed), with the temperature of formation of the line as approximately Tsup(-0.6). The density sensitive C III (formed at T approximately 9x10/sup 4/ K) line ratio Isub(lambda1175)/Isub(lambda977) implies an average density 1.3x10/sup 9/ electrons cm/sup -3/ in the P-C interface and approximately 4 times this value in the C-C transition of the cells. The total optical thickness at the head of the Lyman continuum is < approximately 10 in most of the prominences studied; in two of the prominences, however, the possibility that tau/sub 0/ is large cannot be rejected. Methods of analysis of these EUV data are developed assuming both a resolved and an unresolved internal prominence structure. Although the systematic differences between the P-C interface and the C-C transition are stressed, the similarities are probably more remarkable and may be a result of fine structure in the C-C transition.

The digital holographic interferometry in resonant acoustic spectroscopy

International Nuclear Information System (INIS)

GAPONOV, V.E.; AZAMATOV, Z.T.; REDKORECHEV, V.I.; ISAEV, A.M.

2014-01-01

The opportunities of application of digital holographic interferometry method for studies of shapes of resonant modes in resonant acoustic spectroscopy are shown. The results of experimental measurements and analytical calculations are submitted. (authors)

Acoustic Fano resonators

KAUST Repository

Amin, Muhammad

2014-07-01

The resonances with asymmetric Fano line-shapes were originally discovered in the context of quantum mechanics (U. Fano, Phys. Rev., 124, 1866-1878, 1961). Quantum Fano resonances were generated from destructive interference of a discrete state with a continuum one. During the last decade this concept has been applied in plasmonics where the interference between a narrowband polariton and a broader one has been used to generate electromagnetically induced transparency (EIT) (M. Rahmani, et al., Laser Photon. Rev., 7, 329-349, 2013).

New analytical calculations of the resonance modes in lens-shaped cavities: applications to the calculations of the energy levels and electronic wavefunctions in quantum dots

International Nuclear Information System (INIS)

Even, J; Loualiche, S

2003-01-01

The problem of the energy levels and electronic wavefunctions in quantum dots is studied in the parabolic coordinates system. A conventional effective mass Hamiltonian is written. For an infinite potential barrier, it is related to the more general problem of finding the resonance modes in a cavity. The problem is found to be separable for a biconvex-shaped cavity or quantum dot with an infinite potential barrier. This first shape of quantum dot corresponds to the intersection of two orthogonal confocal parabolas. Then plano-convex lens-shaped cavities or quantum dots are studied. This problem is no more separable in the parabolic coordinates but using symmetry properties, we show that the exact solutions of the problem are simple combinations of the previous solutions. The same approach is used for spherical coordinates and hemispherical quantum dots. It is finally shown that convex lens-shaped quantum dots give a good description of self-organized InAs quantum dots grown on InP

Incidentally diagnosed Takayasu arteritis on thyroid ultrasonography showing prominent collateral vessels of thyroidal arteries and common carotid artery occlusion

Energy Technology Data Exchange (ETDEWEB)

Nam, Se Jin; Kim, Eun Kyung [Dept. of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul (Korea, Republic of)

2014-10-15

We report a case of middle-aged woman incidentally diagnosed with Takayasu arteritis during the ultrasonography of a thyroid gland nodule. Prominent collaterals of the thyroidal arteries and a thin common carotid artery with mural thickening and deficient intraluminal flow signals were initially depicted on the ultrasonography with color Doppler. Subsequent magnetic resonance angiography and computed tomography aortography confirmed the diagnosis with the imaging features of a bilateral long segment common carotid artery occlusion and segmental stenosis of the left subclavian artery in addition to the suggestive physical findings.

Effect of non-ideal clamping shape on the resonance frequencies of silicon nanocantilevers

Energy Technology Data Exchange (ETDEWEB)

Guillon, Samuel; Saya, Daisuke; Mazenq, Laurent; Nicu, Liviu [CNRS, LAAS, 7 Avenue du Colonel Roche, F-31077 Toulouse Cedex 4 (France); Perisanu, Sorin; Vincent, Pascal [LPMCN, Universite Claude Bernard Lyon 1 et CNRS, 43 boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex (France); Lazarus, Arnaud; Thomas, Olivier, E-mail: sguillon@laas.fr [Structural Mechanics and Coupled Systems Laboratory, Conservatoire National des Arts et Metiers, 2 rue Conte, 75003 Paris (France)

2011-06-17

In this paper, we investigate the effects of non-ideal clamping shapes on the dynamic behavior of silicon nanocantilevers. We fabricated silicon nanocantilevers using silicon on insulator (SOI) wafers by employing stepper ultraviolet (UV) lithography, which permits a resolution of under 100 nm. The nanocantilevers were driven by electrostatic force inside a scanning electron microscope (SEM). Both lateral and out-of-plane resonance frequencies were visually detected with the SEM. Next, we discuss overhanging of the cantilever support and curvature at the clamping point in the silicon nanocantilevers, which generally arises in the fabrication process. We found that the fundamental out-of-plane frequency of a realistically clamped cantilever is always lower than that for a perfectly clamped cantilever, and depends on the cantilever width and the geometry of the clamping point structure. Using simulation with the finite-elements method, we demonstrate that this discrepancy is attributed to the particular geometry of the clamping point (non-zero joining curvatures and a flexible overhanging) that is obtained in the fabrication process. The influence of the material orthotropy is also investigated and is shown to be negligible.

MULTI-LINE STOKES INVERSION FOR PROMINENCE MAGNETIC-FIELD DIAGNOSTICS

International Nuclear Information System (INIS)

Casini, R.; Lopez Ariste, A.; Paletou, F.; Leger, L.

2009-01-01

We present test results on the simultaneous inversion of the Stokes profiles of the He I lines at 587.6 nm (D 3 ) and 1083.0 nm in prominences (90 deg. scattering). We created data sets of synthetic Stokes profiles for the case of quiescent prominences (B -3 of the peak intensity for the polarimetric sensitivity of the simulated observations. In this work, we focus on the error analysis for the inference of the magnetic field vector, under the usual assumption that the prominence can be assimilated to a slab of finite optical thickness with uniform magnetic and thermodynamic properties. We find that the simultaneous inversion of the two lines significantly reduces the errors on the inference of the magnetic field vector, with respect to the case of single-line inversion. These results provide a solid justification for current and future instrumental efforts with multi-line capabilities for the observations of solar prominences and filaments.

Physics of Solar Prominences: I-Spectral Diagnostics and Non-LTE Modelling

Science.gov (United States)

Labrosse, N.; Heinzel, P.; Vial, J.-C,; Kucera, T.; Parenti, S.; Gunar, S.; Schmieder, B.; Kilper, G.

2010-01-01

This review paper outlines background information and covers recent advances made via the analysis of spectra and images of prominence plasma and the increased sophistication of non-LTE (i.e. when there is a departure from Local Thermodynamic Equilibrium) radiative transfer models. We first describe the spectral inversion techniques that have been used to infer the plasma parameters important for the general properties of the prominence plasma in both its cool core and the hotter prominence-corona transition region. We also review studies devoted to the observation of bulk motions of the prominence plasma and to the determination of prominence mass. However, a simple inversion of spectroscopic data usually fails when the lines become optically thick at certain wavelengths. Therefore, complex

Open questions on prominences from coordinated observations by IRIS, Hinode, SDO/AIA, THEMIS, and the Meudon/MSDP

Science.gov (United States)

Schmieder, B.; Tian, H.; Kucera, T.; López Ariste, A.; Mein, N.; Mein, P.; Dalmasse, K.; Golub, L.

2014-09-01

-LTE radiative transfer modeling. This is a very surprising behavior for the Mg II line observed in prominences. Conclusions: Turbulent fields on top of the macroscopic horizontal component of the magnetic field supporting the prominence give rise to the complex dynamics of the plasma. The plasma with the high velocities (70 km s-1 to 100 km s-1 if we take into account the transverse velocities) may correspond to condensation of plasma along more or less horizontal threads of the arch-shape structure visible in 304 Å. The steady flows (5 km s-1) would correspond to a more quiescent plasma (cool and prominence-corona transition region) of the prominence packed into dips in horizontal magnetic field lines. The very weak secondary peaks in the Mg II profiles may reflect the turbulent nature of parts of the prominence. Movies are available in electronic form at http://www.aanda.org

Plasmonic EIT-like switching in bright-dark-bright plasmon resonators.

Science.gov (United States)

Chen, Junxue; Wang, Pei; Chen, Chuncong; Lu, Yonghua; Ming, Hai; Zhan, Qiwen

2011-03-28

In this paper we report the study of the electromagnetically induced transparency (EIT)-like transmission in the bright-dark-bright plasmon resonators. It is demonstrated that the interferences between the dark plasmons excited by two bright plasmon resonators can be controlled by the incident light polarization. The constructive interference strengthens the coupling between the bright and dark resonators, leading to a more prominent EIT-like transparency window of the metamaterial. In contrary, destructive interference suppresses the coupling between the bright and dark resonators, destroying the interference pathway that forms the EIT-like transmission. Based on this observation, the plasmonic EIT switching can be realized by changing the polarization of incident light. This phenomenon may find applications in optical switching and plasmon-based information processing.

Nuclear elasticity applied to giant resonances of fast rotating nuclei

International Nuclear Information System (INIS)

Jang, S.; Bouyssy, A.

1987-06-01

Isoscalar giant resonances in fast rotating nuclei are investigated within the framework of nuclear elasticity by solving the equation of motion of elastic nuclear medium in a rotating frame of reference. Both Coriolis and centrifugal forces are taken into account. The nuclear rotation removes completely the azimuthal degeneracy of the giant resonance energies. Realistic large values of the angular velocity, which are still small as compared to the giant resonance frequencies, are briefly reviewed in relation to allowed high angular momenta. It is shown that for the A=150 region, the Coriolis force is dominating for small values (< ∼ 0.05) of the ratio of angular velocity to resonance frequency, whereas the centrifugal force plays a prominent part in the shift of the split resonance energies for larger values of the ratio. Typical examples of the resonance energies and their fragmentation due to both rotation and deformation are given

Solar Prominence Modelling and Plasma Diagnostics at ALMA Wavelengths

Science.gov (United States)

Rodger, Andrew; Labrosse, Nicolas

2017-09-01

Our aim is to test potential solar prominence plasma diagnostics as obtained with the new solar capability of the Atacama Large Millimeter/submillimeter Array (ALMA). We investigate the thermal and plasma diagnostic potential of ALMA for solar prominences through the computation of brightness temperatures at ALMA wavelengths. The brightness temperature, for a chosen line of sight, is calculated using the densities of electrons, hydrogen, and helium obtained from a radiative transfer code under non-local thermodynamic equilibrium (non-LTE) conditions, as well as the input internal parameters of the prominence model in consideration. Two distinct sets of prominence models were used: isothermal-isobaric fine-structure threads, and large-scale structures with radially increasing temperature distributions representing the prominence-to-corona transition region. We compute brightness temperatures over the range of wavelengths in which ALMA is capable of observing (0.32 - 9.6 mm), however, we particularly focus on the bands available to solar observers in ALMA cycles 4 and 5, namely 2.6 - 3.6 mm (Band 3) and 1.1 - 1.4 mm (Band 6). We show how the computed brightness temperatures and optical thicknesses in our models vary with the plasma parameters (temperature and pressure) and the wavelength of observation. We then study how ALMA observables such as the ratio of brightness temperatures at two frequencies can be used to estimate the optical thickness and the emission measure for isothermal and non-isothermal prominences. From this study we conclude that for both sets of models, ALMA presents a strong thermal diagnostic capability, provided that the interpretation of observations is supported by the use of non-LTE simulation results.

ON THE MAGNETISM AND DYNAMICS OF PROMINENCE LEGS HOSTING TORNADOES

International Nuclear Information System (INIS)

Martínez González, M. J.; Ramos, A. Asensio; Arregui, I.; Collados, M.; Beck, C.; Rodríguez, J. de la Cruz

2016-01-01

Solar tornadoes are dark vertical filamentary structures observed in the extreme ultraviolet associated with prominence legs and filament barbs. Their true nature and relationship to prominences requires an understanding of their magnetic structure and dynamic properties. Recently, a controversy has arisen: is the magnetic field organized forming vertical, helical structures or is it dominantly horizontal? And concerning their dynamics, are tornadoes really rotating or is it just a visual illusion? Here we analyze four consecutive spectro-polarimetric scans of a prominence hosting tornadoes on its legs, which helps us shed some light on their magnetic and dynamical properties. We show that the magnetic field is very smooth in all the prominence, which is probably an intrinsic property of the coronal field. The prominence legs have vertical helical fields that show slow temporal variation that is probably related to the motion of the fibrils. Concerning the dynamics, we argue that (1) if rotation exists, it is intermittent, lasting no more than one hour, and (2) the observed velocity pattern is also consistent with an oscillatory velocity pattern (waves).

ON THE MAGNETISM AND DYNAMICS OF PROMINENCE LEGS HOSTING TORNADOES

Energy Technology Data Exchange (ETDEWEB)

Martínez González, M. J.; Ramos, A. Asensio; Arregui, I.; Collados, M. [Instituto de Astrofísica de Canarias, Vía Láctea s/n, E-38205 La Laguna, Tenerife (Spain); Beck, C. [National Solar Observatory, Sacramento Peak P.O. Box 62, Sunspot, NM 88349 (United States); Rodríguez, J. de la Cruz [Institute for Solar Physics, Department of Astronomy, Stockholm University, Albanova University Center, SE-10691 Stockholm (Sweden)

2016-07-10

Solar tornadoes are dark vertical filamentary structures observed in the extreme ultraviolet associated with prominence legs and filament barbs. Their true nature and relationship to prominences requires an understanding of their magnetic structure and dynamic properties. Recently, a controversy has arisen: is the magnetic field organized forming vertical, helical structures or is it dominantly horizontal? And concerning their dynamics, are tornadoes really rotating or is it just a visual illusion? Here we analyze four consecutive spectro-polarimetric scans of a prominence hosting tornadoes on its legs, which helps us shed some light on their magnetic and dynamical properties. We show that the magnetic field is very smooth in all the prominence, which is probably an intrinsic property of the coronal field. The prominence legs have vertical helical fields that show slow temporal variation that is probably related to the motion of the fibrils. Concerning the dynamics, we argue that (1) if rotation exists, it is intermittent, lasting no more than one hour, and (2) the observed velocity pattern is also consistent with an oscillatory velocity pattern (waves).

Effects of the volume and shape of voxels on the measurement of phantom volume using three-dimensional magnetic resonance imaging

International Nuclear Information System (INIS)

Mori, Koichi; Tonami, Syuichi; Nakamura, Mamoru; Kuranishi, Makoto; Hagino, Hirofumi; Saitou, Osamu; Yotsutsuji, Takashi

2002-01-01

Recently, an increasing number of volumetric studies of the human brain have been reported, using three-dimensional magnetic resonance imaging (3D-MRI). To our knowledge, however, there are few investigations on the relation of the volume and shape of voxels which constitute and MR image to the accuracy in volume measurement of an imaged object. The purpose of this study was to evaluate the effect of a different shape of voxel, that is, isotropic or anisotropic, as well as the volume of a voxel on the volume measurement based on the original image data and multiplanar reconstruction (MPR) data, respectively. In the experiment, we repeatedly acquired contiguous sagittal images of a single globe phantom with a known volume under the condition in which the volume and shape of voxels varied, on a 1.5 T MR scanner. We used a gradient echo sequence (3D FLASH). The volume of the globe phantom from both original images and MPR ones was measured on workstations employing a semi-automated local thresholding technique. As a result, the smaller volume of voxels tended to give us the more correct measurement, and an isotropic voxel reduced measurement errors as compared to an anisotropic one. Therefore, it is concluded that the setting of voxel with both an isotropic shape and small volume, e.g., a voxel of 1 mm x 1 mm x 1 mm at present, is recommended in order to get a precise volume measurement using 3D-MRI. (author)

[Effects of the volume and shape of voxels on the measurement of phantom volume using three-dimensional magnetic resonance imaging].

Science.gov (United States)

Mori, Koichi; Hagino, Hirofumi; Saitou, Osamu; Yotsutsuji, Takashi; Tonami, Syuichi; Nakamura, Mamoru; Kuranishi, Makoto

2002-01-01

Recently, an increasing number of volumetric studies of the human brain have been reported, using three-dimensional magnetic resonance imaging (3D-MRI). To our knowledge, however, there are few investigations on the relation of the volume and shape of voxels which constitute an MR image to the accuracy in volume measurement of an imaged object. The purpose of this study was to evaluate the effect of a different shape of voxel, that is, isotropic or anisotropic, as well as the volume of a voxel on the volume measurement based on the original image data and multiplanar reconstruction (MPR) data, respectively. In the experiment, we repeatedly acquired contiguous sagittal images of a single globe phantom with a known volume under the condition in which the volume and shape of voxels varied, on a 1.5T MR scanner. We used a gradient echo sequence (3D FLASH). The volume of the globe phantom from both original images and MPR ones was measured on workstations employing a semi-automated local thresholding technique. As a result, the smaller volume of voxels tended to give us the more correct measurement, and an isotropic voxel reduced measurement errors as compared to an anisotropic one. Therefore, it is concluded that the setting of voxel with both an isotropic shape and small volume, e.g., a voxel of 1 mm x 1 mm x 1 mm at present, is recommended in order to get a precise volume measurement using 3D-MRI.

First observation of the Λ(1405) line shape in electroproduction

Science.gov (United States)

Lu, H. Y.; Schumacher, R. A.; Adhikari, K. P.; Adikaram, D.; Aghasyan, M.; Amaryan, M. J.; Pereira, S. Anefalos; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Cole, P. L.; Collins, P.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; Egiyan, H.; Alaoui, A. El; Fassi, L. El; Eugenio, P.; Fedotov, G.; Fegan, S.; Fleming, J. A.; Gabrielyan, M.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Harrison, N.; Heddle, D.; Hicks, K.; Ho, D.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, A.; Kubarovsky, V.; Kuleshov, S. V.; Lewis, S.; Livingston, K.; MacGregor, I. J. D.; Martinez, D.; Mayer, M.; McKinnon, B.; Meyer, C. A.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moriya, K.; Moutarde, H.; Munevar, E.; Camacho, C. Munoz; Nadel-Turonski, P.; Nepali, C. S.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Park, S.; Pasyuk, E.; Peng, P.; Phelps, E.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Raue, B. A.; Rimal, D.; Ripani, M.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stoler, P.; Strauch, S.; Taiuti, M.; Tang, W.; Tian, Ye; Tkachenko, S.; Torayev, B.; Vernarsky, B.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Weygand, D. P.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.

2013-10-01

We report the first observation of the line shape of the Λ(1405) from electroproduction, and show that it is not a simple Breit-Wigner resonance. Electroproduction of K+Λ(1405) off the proton was studied by using data from CLAS at Jefferson Lab in the range 1.0resonance parameters, nor free parameters fitting to a single Breit-Wigner resonance represent the line shape. In our fits, the line shape corresponds approximately to predictions of a two-pole meson-baryon picture of the Λ(1405), with a lower mass pole near 1368 MeV/c2 and a higher mass pole near 1423 MeV/c2. Furthermore, with increasing photon virtuality the mass distribution shifts toward the higher mass pole.

Low losses left-handed materials with optimized electric and magnetic resonance

Science.gov (United States)

Zhou, Xin; Liu, Yahong; Zhao, Xiaopeng

2010-03-01

We propose that the losses in left-handed materials (LHMs) can be significantly affected by changing the coupling relationship between electric and magnetic resonance. A double bowknot shaped structure (DBS) is used to construct the LHMs. And the magnetic resonance of the DBS, which resonated in the case of lower and higher frequencies than the electric resonant dip, is studied in simulation and experiment by tailoring the structural parameters. The case of magnetic resonance located at low electric resonance frequencies band is confirmed to have relatively low losses. Using full wave simulation of prism shaped structure composed of DBS unit cells, we prove the negative refraction behavior in such a frame. This study can serve as a guide for designing other similar metal-dielectric-metal (MDM) in low losses at terahertz or higher frequencies.

Detecting global and local hippocampal shape changes in Alzheimer's disease using statistical shape models

NARCIS (Netherlands)

Shen, Kai-kai; Fripp, Jurgen; Mériaudeau, Fabrice; Chételat, Gaël; Salvado, Olivier; Bourgeat, Pierrick; Saradha, A.; Abdi, Hervé; Abdulkadir, Ahmed; Acharya, Deepa; Achuthan, Anusha; Adluru, Nagesh; Aghajanian, Jania; Agrusti, Antonella; Agyemang, Alex; Ahdidan, Jamila; Ahmad, Duaa; Ahmed, Shiek; Aisen, Paul; Akhondi-Asl, Alireza; Aksu, Yaman; Alberca, Roman; Alcauter, Sarael; Alexander, Daniel; Alin, Aylin; Almeida, Fabio; Alvarez-Lineara, Juan; Amlien, Inge; Anand, Shyam; Anderson, Dallas; Ang, Amma; Angersbach, Steve; Ansarian, Reza; Aoyama, Eiji; Appannah, Arti; Arfanakis, Konstantinos; Armor, Tom; Arrighi, Michael; Arumughababu, S. Vethanayaki; Arunagiri, Vidhya; Ashe-McNalley, Cody; Ashford, Wes; Le Page, Aurelie; Avants, Brian; Aviv, Richard; Awasthi, Sukrati; Ayache, Nicholas; Chen, Wei; Richard, Edo; Schmand, Ben

2012-01-01

The hippocampus is affected at an early stage in the development of Alzheimer's disease (AD). With the use of structural magnetic resonance (MR) imaging, we can investigate the effect of AD on the morphology of the hippocampus. The hippocampal shape variations among a population can be usually

Aesthetic Refinements in Patients with Prominent Eyes.

Science.gov (United States)

Richter, Dirk F; Schwaiger, Nina; Wiedner, Maria

2015-12-01

The treatment of prominent eyes is still a challenging task. As well as the surgery, proper preoperative diagnosis differentiating between patients with and without Graves ophthalmopathy plays an important role. In functionally asymptomatic patients with Graves disease suffering from the aesthetic impairment of prominent eyes, the transpalpebral decompression by intraorbital fat removal technique has been proved to be reliable, effective, safe, and easily performed by a trained and experienced oculoplastic surgeon. This technique provides long-lasting results, leading to improvement not only in visual function but also in personal well-being and in the patient's social life, with a high benefit-to-risk ratio. The most powerful tool to treat the lower lid deformity and malar bags in patients without Graves disease is the subperiosteal midface lift. It shortens the lid-cheek junction and blends the retaining periorbital ligaments. Furthermore, it adds volume to the lower lid and gives a stable support. By the nature of the procedure, it also turns a negative into a positive vector. In experienced hands, Olivari's orbital decompression and Hester's midface lift are ideal options for the treatment of prominent eyes. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Action in Perception: Prominent Visuo-Motor Functional Symmetry in Musicians during Music Listening.

Directory of Open Access Journals (Sweden)

Iballa Burunat

Full Text Available Musical training leads to sensory and motor neuroplastic changes in the human brain. Motivated by findings on enlarged corpus callosum in musicians and asymmetric somatomotor representation in string players, we investigated the relationship between musical training, callosal anatomy, and interhemispheric functional symmetry during music listening. Functional symmetry was increased in musicians compared to nonmusicians, and in keyboardists compared to string players. This increased functional symmetry was prominent in visual and motor brain networks. Callosal size did not significantly differ between groups except for the posterior callosum in musicians compared to nonmusicians. We conclude that the distinctive postural and kinematic symmetry in instrument playing cross-modally shapes information processing in sensory-motor cortical areas during music listening. This cross-modal plasticity suggests that motor training affects music perception.

Brandburg Prominance, Namibia, Africa

Science.gov (United States)

1993-01-01

The Brandburg Prominance, Namibia (21.0S, 14.5E) is a round basaltic plug and is the highest feature (over 8,000 ft) in the country. Wind streaks on the surface of the coastal desert, aligned northeast to southwest, are the result of frequent sand storms. Coastal stratus clouds provide most of the life supporting moisture as fog droplets in this arid land where annual rainfall may be less than a quarter of an inch for decades at a time.

Resonance control of mid-infrared metamaterials using arrays of split-ring resonator pairs

KAUST Repository

Yue, Weisheng

2016-01-11

We present our design, fabrication and characterization of resonance-controllable metamaterials operating at mid-infrared wavelengths. The metamaterials are composed of pairs of back-to-back or face-to-face U-shape split-ring resonators (SRRs). Transmission spectra of the metamaterials are measured using Fourier-transform infrared spectroscopy. The results show that the transmission resonance is dependent on the distance between the two SRRs in each SRR pair. The dips in the transmission spectrum shift to shorter wavelengths with increasing distance between the two SRRs for both the back-to-back and face-to-face SRR pairs. The position of the resonance dips in the spectrum can hence be controlled by the relative position of the SRRs. This mechanism of resonance control offers a promising way of developing metamaterials with tunability for optical filters and bio/chemical sensing devices in integrated nano-optics.

Resonance control of mid-infrared metamaterials using arrays of split-ring resonator pairs

KAUST Repository

Yue, Weisheng; Wang, Zhihong; Whittaker, John; Schedin, Fredrik; Wu, Zhipeng; Han, Jiaguang

2016-01-01

We present our design, fabrication and characterization of resonance-controllable metamaterials operating at mid-infrared wavelengths. The metamaterials are composed of pairs of back-to-back or face-to-face U-shape split-ring resonators (SRRs). Transmission spectra of the metamaterials are measured using Fourier-transform infrared spectroscopy. The results show that the transmission resonance is dependent on the distance between the two SRRs in each SRR pair. The dips in the transmission spectrum shift to shorter wavelengths with increasing distance between the two SRRs for both the back-to-back and face-to-face SRR pairs. The position of the resonance dips in the spectrum can hence be controlled by the relative position of the SRRs. This mechanism of resonance control offers a promising way of developing metamaterials with tunability for optical filters and bio/chemical sensing devices in integrated nano-optics.

FPSPH DFPSPF, Line Shape Function for Doppler Broadened Resonance Cross-Sections Calculation

International Nuclear Information System (INIS)

Ribon, P.

1982-01-01

1 - Description of problem or function: In the computation of Doppler- broadened resonance cross sections, use is made of the symmetric and anti-symmetric line shape functions. These functions usually denoted as Psi and Phi (Psi and Chi in Anglo-Saxon formalism) are defined in terms of the real and imaginary parts of the error function for complex arguments. They are the product of the convolution of a Gaussian function with the symmetric and anti-symmetric Breit-Wigner functions, respectively. FPSPH and DFPSPH compute these functions. 2 - Method of solution: For (1+x 2 ) > 20 Beta 2 , the calculation is based upon the asymptotic expansion: Psi+(i*Phi) = 1/(1-ix)*(1-t+3t 2 -3.5t 3 +3.5+7t 4 ---), with: t = 1/(2z 2 ); z = (1-ix)/Beta. The half-plane (Beta,x) is split in several parts, and use is made of PADE approximants. For 1 + x 2 2 , the calculation is based upon the relation with the erf function: Psi + i*Phi = SQRT(Pi)/Beta*(e (z 2 ) )*(1-erf(z)) (z = (1-ix)/Beta, and erf(z) being calculated from its analytic expansion: erf(z) = 2/SQRT(Pi)*z*e (-z 2 ) *(1+z 2 /3+z 4 /(3*5) + z 6 /(3*5*7)+---). PADE approximants are used to compute the expansion and e z 2

Neutron resonance parameters of CM isotopes

International Nuclear Information System (INIS)

Belanova, T.S.; Kolesov, A.G.; Poruchikov, V.A.

1977-01-01

The total neutron cross sections of isotopes 244, 245, 246, 248 Curium have been measured on reactor CM-2 using the time-of-flight method. Single-level Breit-Wigner resonance parameters: energy E 0 , neutron width 2g GITAn, total width GITA, total neutron cross section in resonance sigma 0 have been obtained by the shape and area methods

Free-vibration acoustic resonance of a nonlinear elastic bar

Science.gov (United States)

Tarumi, Ryuichi; Oshita, Yoshihito

2011-02-01

Free-vibration acoustic resonance of a one-dimensional nonlinear elastic bar was investigated by direct analysis in the calculus of variations. The Lagrangian density of the bar includes a cubic term of the deformation gradient, which is responsible for both geometric and constitutive nonlinearities. By expanding the deformation function into a complex Fourier series, we derived the action integral in an analytic form and evaluated its stationary conditions numerically with the Ritz method for the first three resonant vibration modes. This revealed that the bar shows the following prominent nonlinear features: (i) amplitude dependence of the resonance frequency; (ii) symmetry breaking in the vibration pattern; and (iii) excitation of the high-frequency mode around nodal-like points. Stability of the resonant vibrations was also addressed in terms of a convex condition on the strain energy density.

A STATISTICAL STUDY OF TRANSVERSE OSCILLATIONS IN A QUIESCENT PROMINENCE

Energy Technology Data Exchange (ETDEWEB)

Hillier, A. [Kwasan and Hida Observatories, Kyoto University, Kyoto 607-8471 (Japan); Morton, R. J. [Mathematics and Information Science, Northumbria University, Pandon Building, Camden Street, Newcastle upon Tyne NE1 8ST (United Kingdom); Erdélyi, R., E-mail: andrew@kwasan.kyoto-u.ac.jp [Solar Physics and Space Plasma Research Centre (SP2RC), University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

2013-12-20

The launch of the Hinode satellite has allowed for seeing-free observations at high-resolution and high-cadence making it well suited to study the dynamics of quiescent prominences. In recent years it has become clear that quiescent prominences support small-amplitude transverse oscillations, however, sample sizes are usually too small for general conclusions to be drawn. We remedy this by providing a statistical study of transverse oscillations in vertical prominence threads. Over a 4 hr period of observations it was possible to measure the properties of 3436 waves, finding periods from 50 to 6000 s with typical velocity amplitudes ranging between 0.2 and 23 km s{sup –1}. The large number of observed waves allows the determination of the frequency dependence of the wave properties and derivation of the velocity power spectrum for the transverse waves. For frequencies less than 7 mHz, the frequency dependence of the velocity power is consistent with the velocity power spectra generated from observations of the horizontal motions of magnetic elements in the photosphere, suggesting that the prominence transverse waves are driven by photospheric motions. However, at higher frequencies the two distributions significantly diverge, with relatively more power found at higher frequencies in the prominence oscillations. These results highlight that waves over a large frequency range are ubiquitous in prominences, and that a significant amount of the wave energy is found at higher frequency.

A STATISTICAL STUDY OF TRANSVERSE OSCILLATIONS IN A QUIESCENT PROMINENCE

International Nuclear Information System (INIS)

Hillier, A.; Morton, R. J.; Erdélyi, R.

2013-01-01

The launch of the Hinode satellite has allowed for seeing-free observations at high-resolution and high-cadence making it well suited to study the dynamics of quiescent prominences. In recent years it has become clear that quiescent prominences support small-amplitude transverse oscillations, however, sample sizes are usually too small for general conclusions to be drawn. We remedy this by providing a statistical study of transverse oscillations in vertical prominence threads. Over a 4 hr period of observations it was possible to measure the properties of 3436 waves, finding periods from 50 to 6000 s with typical velocity amplitudes ranging between 0.2 and 23 km s –1 . The large number of observed waves allows the determination of the frequency dependence of the wave properties and derivation of the velocity power spectrum for the transverse waves. For frequencies less than 7 mHz, the frequency dependence of the velocity power is consistent with the velocity power spectra generated from observations of the horizontal motions of magnetic elements in the photosphere, suggesting that the prominence transverse waves are driven by photospheric motions. However, at higher frequencies the two distributions significantly diverge, with relatively more power found at higher frequencies in the prominence oscillations. These results highlight that waves over a large frequency range are ubiquitous in prominences, and that a significant amount of the wave energy is found at higher frequency

Doubly excited P-wave resonance states of H− in Debye plasmas

International Nuclear Information System (INIS)

Jiao, L. G.; Ho, Y. K.

2013-01-01

We investigate the doubly excited P-wave resonance states of H − system in Debye plasmas modeled by static screened Coulomb potentials. The screening effects of the plasma environment on resonance parameters (energy and width) are investigated by employing the complex-scaling method with Hylleraas-type wave functions for both the shape and Feshbach resonances associated with the H(N = 2 to 6) thresholds. Under the screening conditions, the H(N) threshold states are no longer l degenerate, and all the H − resonance energy levels are shifted away from their unscreened values toward the continuum. The influence of Debye plasmas on resonance widths has also been investigated. The shape resonance widths are broadened with increasing plasma screening strength, whereas the Feshbach resonance widths would generally decrease. Our results associated with the H(N = 2) and H(N = 3) thresholds are compared with others in the literature

Quiescent Prominences in the Era of ALMA. II. Kinetic Temperature Diagnostics

Science.gov (United States)

Gunár, Stanislav; Heinzel, Petr; Anzer, Ulrich; Mackay, Duncan H.

2018-01-01

We provide the theoretical background for diagnostics of the thermal properties of solar prominences observed by the Atacama Large Millimeter/submillimeter Array (ALMA). To do this, we employ the 3D Whole-Prominence Fine Structure (WPFS) model that produces synthetic ALMA-like observations of a complex simulated prominence. We use synthetic observations derived at two different submillimeter/millimeter (SMM) wavelengths—one at a wavelength at which the simulated prominence is completely optically thin and another at a wavelength at which a significant portion of the simulated prominence is optically thick—as if these were the actual ALMA observations. This allows us to develop a technique for an analysis of the prominence plasma thermal properties from such a pair of simultaneous high-resolution ALMA observations. The 3D WPFS model also provides detailed information about the distribution of the kinetic temperature and the optical thickness along any line of sight. We can thus assess whether the measure of the kinetic temperature derived from observations accurately represents the actual kinetic temperature properties of the observed plasma. We demonstrate here that in a given pixel the optical thickness at the wavelength at which the prominence plasma is optically thick needs to be above unity or even larger to achieve a sufficient accuracy of the derived information about the kinetic temperature of the analyzed plasma. Information about the optical thickness cannot be directly discerned from observations at the SMM wavelengths alone. However, we show that a criterion that can identify those pixels in which the derived kinetic temperature values correspond well to the actual thermal properties in which the observed prominence can be established.

Fabrication of micro-prominences on PTFE surface using proton beam writing

Energy Technology Data Exchange (ETDEWEB)

Kitamura, Akane, E-mail: ogawa.akane@jaea.go.jp [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-Machi, Takasaki, Gunma 370-1292 (Japan); Satoh, Takahiro; Koka, Masashi [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-Machi, Takasaki, Gunma 370-1292 (Japan); Kobayashi, Tomohiro [Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 350-0198 (Japan); Kamiya, Tomihiro [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-Machi, Takasaki, Gunma 370-1292 (Japan)

2013-07-01

Polytetrafluoroethylene (PTFE) is a typical fluoropolymer and it has several desirable technological properties such as electrical insulation, solid lubrication etc. However, the conventional microstructuring methods have not been well applied to PTFE due to its chemical inertness. Some effective micromachining using synchrotron radiation or ion beam irradiation has been reported. In this study, we create micro-prominences by raising the original surface using proton beam writing (PBW) without chemical etching. A conical prominence was formed by spiral drawing from the center with a 3 MeV proton beam. The body was porous, and the bulk PTFE below the prominence changed to fragmented structures. With decreasing writing speed, the prominence became taller but the height peaked. The prominence gradually reduced in size after the speed reached the optimum value. We expect that these porous projections with high aspect ratio will be versatile in medical fields and microelectromechanical systems (MEMS) technology.

An analysis of concert saxophone vibrato through the examination of recordings by eight prominent soloists

Science.gov (United States)

Zinninger, Thomas

This study examines concert saxophone vibrato through the analysis of several recordings of standard repertoire by prominent soloists. The vibrato of Vincent Abato, Arno Bornkamp, Claude Delangle, Jean-Marie Londeix, Marcel Mule, Otis Murphy, Sigurd Rascher, and Eugene Rousseau is analyzed with regards to rate, extent, shape, and discretionary use. Examination of these parameters was conducted through both general observation and precise measurements with the aid of a spectrogram. Statistical analyses of the results provide tendencies for overall vibrato use, as well as the effects of certain musical attributes (note length, tempo, dynamic, range) on vibrato. The results of this analysis are also compared among each soloist and against pre-existing theories or findings in vibrato research.

Building CX peanut-shaped disk galaxy profiles. The relative importance of the 3D families of periodic orbits bifurcating at the vertical 2:1 resonance

Science.gov (United States)

Patsis, P. A.; Harsoula, M.

2018-05-01

Context. We present and discuss the orbital content of a rather unusual rotating barred galaxy model, in which the three-dimensional (3D) family, bifurcating from x1 at the 2:1 vertical resonance with the known "frown-smile" side-on morphology, is unstable. Aims: Our goal is to study the differences that occur in the phase space structure at the vertical 2:1 resonance region in this case, with respect to the known, well studied, standard case, in which the families with the frown-smile profiles are stable and support an X-shaped morphology. Methods: The potential used in the study originates in a frozen snapshot of an N-body simulation in which a fast bar has evolved. We follow the evolution of the vertical stability of the central family of periodic orbits as a function of the energy (Jacobi constant) and we investigate the phase space content by means of spaces of section. Results: The two bifurcating families at the vertical 2:1 resonance region of the new model change their stability with respect to that of most studied analytic potentials. The structure in the side-on view that is directly supported by the trapping of quasi-periodic orbits around 3D stable periodic orbits has now an infinity symbol (i.e. ∞-type) profile. However, the available sticky orbits can reinforce other types of side-on morphologies as well. Conclusions: In the new model, the dynamical mechanism of trapping quasi-periodic orbits around the 3D stable periodic orbits that build the peanut, supports the ∞-type profile. The same mechanism in the standard case supports the X shape with the frown-smile orbits. Nevertheless, in both cases (i.e. in the new and in the standard model) a combination of 3D quasi-periodic orbits around the stable x1 family with sticky orbits can support a profile reminiscent of the shape of the orbits of the 3D unstable family existing in each model.

Fano resonances in a high-Q terahertz whispering-gallery mode resonator coupled to a multi-mode waveguide.

Science.gov (United States)

Vogt, Dominik Walter; Leonhardt, Rainer

2017-11-01

We report on Fano resonances in a high-quality (Q) whispering-gallery mode (WGM) spherical resonator coupled to a multi-mode waveguide in the terahertz (THz) frequency range. The asymmetric line shape and phase of the Fano resonances detected with coherent continuous-wave (CW) THz spectroscopy measurements are in excellent agreement with the analytical model. A very high Q factor of 1600, and a finesse of 22 at critical coupling is observed around 0.35 THz. To the best of our knowledge this is the highest Q factor ever reported for a THz WGM resonator.

Magnetic resonance imaging of cold injury-induced brain edema in rats

International Nuclear Information System (INIS)

Houkin, Kiyohiro; Abe, Hiroshi; Hashiguchi, Yuji; Seri, Shigemi.

1996-01-01

The chronological changes of blood-brain barrier disruption, and diffusion and absorption of edema fluid were investigated in rats with cold-induced brain injury (vasogenic edema) using magnetic resonance imaging. Contrast medium was administered intravenously at 3 and 24 hours after lesioning as a tracer of edema fluid. Serial T 1 -weighted multiple-slice images were obtained for 180 minutes after contrast administration. Disruption of the blood-brain barrier was more prominent at 24 hours after lesioning than at 3 hours. Contrast medium leaked from the periphery of the injury and gradually diffused to the center of the lesion. Contrast medium diffused into the corpus callosum and the ventricular system (cerebrospinal fluid). Disruption of the blood-brain barrier induced by cold injury was most prominent at the periphery of the vasogenic edema. Edema fluid subsequently extended into the center of the lesion and was also absorbed by the ventricular system. Magnetic resonance imaging is a useful method to assess the efficacy of therapy for vasogenic edema. (author)

A numerical investigation of sub-wavelength resonances in polygonal metamaterial cylinders

DEFF Research Database (Denmark)

Arslanagic, Samel; Breinbjerg, Olav

2009-01-01

The sub-wavelength resonances, known to exist in metamaterial radiators and scatterers of circular cylindrical shape, are investigated with the aim of determining if these resonances also exist for polygonal cylinders and, if so, how they are affected by the shape of the polygon. To this end, a set...... of polygonal cylinders excited by a nearby electric line current is analyzed numerically and it is shown, through detailed analysis of the near-field distribution and radiation resistance, that these polygonal cylinders do indeed support sub-wavelength resonances similar to those of the circular cylinders...

On the evaluation of temperature dependence of elastic constants of martensitic phases in shape memory alloys from resonant ultrasound spectroscopy studies

International Nuclear Information System (INIS)

Landa, Michal; Sedlak, Petr; Sittner, Petr; Seiner, Hanus; Heller, Ludek

2008-01-01

Elastic constants of austenite and martensite phases in shape memory alloys reflect fundamental thermodynamic properties of these materials-i.e. important physical information can be deduced not just from the values of the constants but, mainly from their temperature and stress dependencies. As regards to the parent austenite phase, such information is available in the literature for most of the known shape memory alloys. For the martensitic phases, however, only few reliable experimental data exist, due to the experimental difficulties with the preparation of martensite single crystals as well as due to the difficulties with the ultrasonic measurement of elastic properties of strongly anisotropic media with low symmetry. In this work, the temperature dependence of all elastic constants of cubic austenite and orthorhombic 2H martensite phases in Cu-Al-Ni alloy determined by resonance ultrasound spectroscopy (RUS) is reported. Experimental and theoretical improvements of the RUS method which had to be made to perform the successful measurements on strongly anisotropic and martensitic phases are discussed

ARE TORNADO-LIKE MAGNETIC STRUCTURES ABLE TO SUPPORT SOLAR PROMINENCE PLASMA?

Energy Technology Data Exchange (ETDEWEB)

Luna, M.; Moreno-Insertis, F. [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Priest, E. [Mathematics Institute, University of St Andrews, St Andrews KY16 9SS (United Kingdom)

2015-07-20

Recent high-resolution and high-cadence observations have surprisingly suggested that prominence barbs exhibit apparent rotating motions suggestive of a tornado-like structure. Additional evidence has been provided by Doppler measurements. The observations reveal opposite velocities for both hot and cool plasma on the two sides of a prominence barb. This motion is persistent for several hours and has been interpreted in terms of rotational motion of prominence feet. Several authors suggest that such barb motions are rotating helical structures around a vertical axis similar to tornadoes on Earth. One of the difficulties of such a proposal is how to support cool prominence plasma in almost-vertical structures against gravity. In this work we model analytically a tornado-like structure and try to determine possible mechanisms to support the prominence plasma. We have found that the Lorentz force can indeed support the barb plasma provided the magnetic structure is sufficiently twisted and/or significant poloidal flows are present.

ARE TORNADO-LIKE MAGNETIC STRUCTURES ABLE TO SUPPORT SOLAR PROMINENCE PLASMA?

International Nuclear Information System (INIS)

Luna, M.; Moreno-Insertis, F.; Priest, E.

2015-01-01

Recent high-resolution and high-cadence observations have surprisingly suggested that prominence barbs exhibit apparent rotating motions suggestive of a tornado-like structure. Additional evidence has been provided by Doppler measurements. The observations reveal opposite velocities for both hot and cool plasma on the two sides of a prominence barb. This motion is persistent for several hours and has been interpreted in terms of rotational motion of prominence feet. Several authors suggest that such barb motions are rotating helical structures around a vertical axis similar to tornadoes on Earth. One of the difficulties of such a proposal is how to support cool prominence plasma in almost-vertical structures against gravity. In this work we model analytically a tornado-like structure and try to determine possible mechanisms to support the prominence plasma. We have found that the Lorentz force can indeed support the barb plasma provided the magnetic structure is sufficiently twisted and/or significant poloidal flows are present

Are Tornado-Like Magnetic Structures Able to Support Solar Prominence Plasma?

Science.gov (United States)

Ogunjo, S. T.; Luna Bennasar, M.; Moreno-Insertis, F.; Priest, E. R.

2015-12-01

Recent high-resolution and high-cadence observations have surprisingly suggested that prominence barbs exhibit apparent rotating motions suggestive of a tornado-like structure. Additional evidence has been provided by Doppler measurements. The observations reveal opposite velocities for both hot and cool plasma on the two sides of a prominence barb. This motion is persistent for several hours and has been interpreted in terms of rotational motion of prominence feet. Several authors suggest that such barb motions are rotating helical structures around a vertical axis similar to tornadoes on Earth. One of the difficulties of such a proposal is how to support cool prominence plasma in almost-vertical structures against gravity. In this work we model analytically a tornado-like structure and try to determine possible mechanisms to support the prominence plasma. We have found that the Lorentz force can indeed support the barb plasma provided the magnetic structure is sufficiently twisted and/or significant poloidal flows are present.

Photoionization of lanthanum and its ions in the region of the 'giant' resonance

International Nuclear Information System (INIS)

Amusia, M.Ya.

1989-01-01

The photoionization cross sections of outer and intermediate shells including 4d of La and its ions are calculated in the region of the 'giant' resonance. The prominent effects of both intershell correlational effects and rearrangement are demonstrated. (orig.)

Resonance-enhanced optical forces between coupled photonic crystal slabs.

Science.gov (United States)

Liu, Victor; Povinelli, Michelle; Fan, Shanhui

2009-11-23

The behaviors of lateral and normal optical forces between coupled photonic crystal slabs are analyzed. We show that the optical force is periodic with displacement, resulting in stable and unstable equilibrium positions. Moreover, the forces are strongly enhanced by guided resonances of the coupled slabs. Such enhancement is particularly prominent near dark states of the system, and the enhancement effect is strongly dependent on the types of guided resonances involved. These structures lead to enhancement of light-induced pressure over larger areas, in a configuration that is directly accessible to externally incident, free-space optical beams.

Unintended exposure in radiotherapy: Identification of prominent causes

International Nuclear Information System (INIS)

Boadu, Mary; Rehani, Madan Mohan

2009-01-01

Background and purpose: Unintended exposures in radiotherapy are likely to occur when certain conditions that favour such exposures exist. Based on the frequency of occurrence of various causes of 100 events of unintended exposures in radiotherapy as derived from the analysis of published reports, a checklist for assessing the vulnerability of radiotherapy facilities for potential accidents has been prepared. The list presents items to be considered for safety critical assessments of a radiotherapy department for the improvement of patient safety and the entire radiotherapy processes. Materials and methods: The resources used for this paper consist of 100 unintended radiotherapy exposures and were derived from existing published reports. The analysis was performed by forming two templates: one consisting of 10 initiating events and another of 35 contributing factors. Results: Four most prominent initiating events were identified and together accounted for about 70% of all the unintended exposure events. Ten most prominent contributing factors were also identified and together accounted for about 70% of all the radiotherapy unintended exposure events covered under this study. Conclusion: With this knowledge of high frequency of occurrences, the identified four prominent initiating events and the 10 most prominent contributing factors must be checked and dealt with as a matter of priority when assessing the safety of a radiotherapy facility. A simple checklist for checking the quality assurance programmes of a radiotherapy department for every aspect of the design and delivery of radiation have been provided.

Continuous neutron slowing down theory applied to resonances

International Nuclear Information System (INIS)

Segev, M.

1977-01-01

Neutronic formalisms that discretize the neutron slowing down equations in large numerical intervals currently account for the bulk effect of resonances in a given interval by the narrow resonance approximation (NRA). The NRA reduces the original problem to an efficient numerical formalism through two assumptions: resonance narrowness with respect to the scattering bands in the slowing down equations and resonance narrowness with respect to the numerical intervals. Resonances at low energies are narrow neither with respect to the slowing down ranges nor with respect to the numerical intervals, which are usually of a fixed lethargy width. Thus, there are resonances to which the NRA is not applicable. To stay away from the NRA, the continuous slowing down (CSD) theory of Stacey was invoked. The theory is based on a linear expansion in lethargy of the collision density in integrals of the slowing down equations and had notable success in various problems. Applying CSD theory to the assessment of bulk resonance effects raises the problem of obtaining efficient quadratures for integrals involved in the definition of the so-called ''moderating parameter.'' The problem was solved by two approximations: (a) the integrals were simplified through a rationale, such that the correct integrals were reproduced for very narrow or very wide resonances, and (b) the temperature-broadened resonant line shapes were replaced by nonbroadened line shapes to enable analytical integration. The replacement was made in such a way that the integrated capture and scattering probabilities in each resonance were preserved. The resulting formalism is more accurate than the narrow-resonance formalisms and is equally as efficient

Electron Cyclotron Resonances in Electron Cloud Dynamics

International Nuclear Information System (INIS)

Celata, Christine; Celata, C.M.; Furman, Miguel A.; Vay, J.-L.; Yu, Jennifer W.

2008-01-01

We report a previously unknown resonance for electron cloud dynamics. The 2D simulation code 'POSINST' was used to study the electron cloud buildup at different z positions in the International Linear Collider positron damping ring wiggler. An electron equilibrium density enhancement of up to a factor of 3 was found at magnetic field values for which the bunch frequency is an integral multiple of the electron cyclotron frequency. At low magnetic fields the effects of the resonance are prominent, but when B exceeds ∼(2 pi mec/(elb)), with lb = bunch length, effects of the resonance disappear. Thus short bunches and low B fields are required for observing the effect. The reason for the B field dependence, an explanation of the dynamics, and the results of the 2D simulations and of a single-particle tracking code used to elucidate details of the dynamics are discussed

Piecewise mass flows within a solar prominence observed by the New Vacuum Solar Telescope

Science.gov (United States)

Li, Hongbo; Liu, Yu; Tam, Kuan Vai; Zhao, Mingyu; Zhang, Xuefei

2018-06-01

The material of solar prominences is often observed in a state of flowing. These mass flows (MF) are important and useful for us to understand the internal structure and dynamics of prominences. In this paper, we present a high resolution Hα observation of MFs within a quiescent solar prominence. From the observation, we find that the plasma primarily has a circular motion and a downward motion separately in the middle section and legs of the prominence, which creates a piecewise mass flow along the observed prominence. Moreover, the observation also shows a clear displacement of MF's velocity peaks in the middle section of the prominence. All of these provide us with a detailed record of MFs within a solar prominence and show a new approach to detecting the physical properties of prominence.

Resonant filtered fiber amplifiers

DEFF Research Database (Denmark)

Alkeskjold, Thomas Tanggaard; Laurila, Marko; Olausson, Christina Bjarnal Thulin

2013-01-01

In this paper we present our recent result on utilizing resonant/bandgap fiber designs to achieve high performance ytterbium doped fiber amplifers for achieving diffraction limited beam quality in large mode area fibers, robust bending performance and gain shaping for long wavelength operation...

Magnetically coupled Fano resonance of dielectric pentamer oligomer

International Nuclear Information System (INIS)

Zhang, Fuli; Li, Chang; He, Xuan; Chen, Lei; Fan, Yuancheng; Zhao, Qian; Zhang, Weihong; Zhou, Ji

2017-01-01

We present magnetically induced Fano resonance inside a dielectric metamaterial pentamer composed of ceramic bricks. Unlike previous reports where different sizes of dielectric resonators were essential to produce Fano resonance, under external magnetic field excitation, central and outer dielectric bricks with identical sizes exhibit in-phase and out-of-phase magnetic Mie oscillations. An asymmetric line shape of Fano resonance along with enhanced group delay is observed due to the interference between the magnetic resonance of the central brick and the symmetric magnetic resonance of outer bricks. Besides, Fano resonance blueshifts with the increasing resonance of the smaller central brick. The thermal-dependent permittivity of ceramics allows Fano resonance to be reversibly tuned by 300 MHz when temperature varies by 60 °C. (paper)

Effect of Interface energy and electron transfer on shape, plasmon resonance and SERS activity of supported surfactant-free gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Giangregorio, Maria M. [Institute of Inorganic Methodologies and of Plasmas, CNR-IMIP; Dastmalchi, Babak [Ames Laboratory; Suvorova, Alexandra [University of Western Australia; Bianco, Giuseppe V. [Institute of Inorganic Methodologies and of Plasmas, CNR-IMIP; Hingerl, Kurt [Johannes Kepler University Linz; Bruno, Giovanni [Institute of Inorganic Methodologies and of Plasmas, CNR-IMIP; Losurdo, Maria [Institute of Inorganic Methodologies and of Plasmas, CNR-IMIP

2014-01-01

For device integration purposes plasmonic metal nanoparticles must be supported/deposited on substrates. Therefore, it is important to understand the interaction between surfactant-free plasmonic metal nanoparticles and different substrates, as well as to identify factors that drive nanoparticles nucleation and formation. Here we show that for nanoparticles grown directly on supports, the substrate/nanoparticle interfacial energy affects the equilibrium shape of nanoparticles. Therefore, oblate, spherical and prolate Au nanoparticles (NPs) with different shapes have been deposited by radiofrequency sputtering on substrates with different characteristics, namely a dielectric oxide Al2O3 (0001), a narrow bandgap semiconductor Si (100), and a polar piezoelectric wide bandgap semiconductor 4H–SiC (0001). We demonstrate that the higher the substrate surface energy, the higher the interaction with the substrate, resulting in flat prolate Au nanoparticles. The resulting localized surface plasmon resonance characteristics of Au NPs/Al2O3, Au NPs/Si and Au NPs/SiC have been determined by spectroscopic ellipsometry and correlated with their structure and shape studied by transmission electron microscopy. Finally, we have demonstrated the diverse response of the tailored plasmonic substrates as ultrasensitive SERS chemical sensors. Flat oblates Au NPs on SiC result in an enhanced and more stable SERS response. The experimental findings are validated by numerical simulations of electromagnetic fields.

Resonance properties of the biological objects in the RF field

International Nuclear Information System (INIS)

Cocherova, E; Kupec, P; Stofanik, V

2011-01-01

Irradiation of people with electromagnetic fields emitted from miscellaneous devices working in the radio-frequency (RF) range may have influence, for example may affect brain processes. The question of health impact of RF electromagnetic fields on population is still not closed. This article is devoted to an investigation of resonance phenomena of RF field absorption in the models of whole human body and body parts (a head) of different size and shape. The values of specific absorption rate (SAR) are evaluated for models of the different shapes: spherical, cylindrical, realistic shape and for different size of the model, that represents the case of new-born, child and adult person. In the RF frequency region, absorption depends nonlinearly on frequency. Under certain conditions (E-polarization), absorption reaches maximum at frequency, that is called r esonance frequency . The whole body absorption and the resonance frequency depends on many further parameters, that are not comprehensively clarified. The simulation results showed the dependence of the whole-body average SAR and resonance frequency on the body dimensions, as well as the influence of the body shape.

The most prominent safety guarantees

International Nuclear Information System (INIS)

Lucenet, G.

1978-01-01

The Creys-Malville Nuclear Centre has been designed using the safety analysis implemented since the beginning of the developments of breeder reactors in France and the Super Phenix follows almost the same safety regulations as its predecessor the Phenix reactor. These regulations are based on: 'Recommendations for the safety standards of the Super Phenix' drawn up by the French Safety Authorities in July 1973. The prominent points are summarised. (C.F.)

A Discourse Perspective of Topic-prominence in Chinese EFL Learners’ Interlanguage

Directory of Open Access Journals (Sweden)

Shaopeng Li

2014-07-01

Full Text Available The present study aims to investigate the general characteristics of topic-prominent typological interlanguage development of Chinese learners of English in terms of acquiring subject-prominent English structures from the discourse perspective. We have selected as the research target “topic chain” which is the main topic-prominent structure in Chinese discourse and “zero anaphora” which is the most common topic anaphor of topic chain. Topic structures mainly appear in Chinese discourse in the form of “topic chain” (Wang, 2002; 2004. Actually, in the event of a topic chain, research on topic structures should go into the typical range of discourse. Two important findings were yielded by the present study. First, the characteristics of Chinese topic chain are transferrable to the interlanguage of Chinese EFL learners, thus resulting in overgeneralization of zero anaphora; second, interlanguage discourse of Chinese EFL learners reflects the characteristics of a second language acquisition process from topic-prominence to subject-prominence, thus lending support to the discourse transfer hypothesis.

Prominence Bubbles and Plumes: Thermo-magnetic Buoyancy in Coronal Cavity Systems

Science.gov (United States)

Berger, Thomas; Hurlburt, N.

2009-05-01

The Hinode/Solar Optical Telescope continues to produce high spatial and temporal resolution images of solar prominences in both the Ca II 396.8 nm H-line and the H-alpha 656.3 nm line. Time series of these images show that many quiescent prominences produce large scale (50 Mm) dark "bubbles" that "inflate" into, and sometimes burst through, the prominence material. In addition, small-scale (2--5 Mm) dark plumes are seen rising into many quiescent prominences. We show typical examples of both phenomena and argue that they originate from the same mechanism: concentrated and heated magnetic flux that rises due to thermal and magnetic buoyancy to equilibrium heights in the prominence/coronal-cavity system. More generally, these bubbles and upflows offer a source of both magnetic flux and mass to the overlying coronal cavity, supporting B.C. Low's theory of CME initiation via steadily increasing magnetic buoyancy breaking through the overlying helmut streamer tension forces. Quiescent prominences are thus seen as the lowermost parts of the larger coronal cavity system, revealing through thermal effects both the cooled downflowing "drainage" from the cavity and the heated upflowing magnetic "plasmoids" supplying the cavity. We compare SOT movies to new 3D compressible MHD simulations that reproduce the dark turbulent plume dynamics to establish the magnetic and thermal character of these buoyancy-driven flows into the corona.

Prominent hypointense veins on susceptibility weighted image in the cat brain with acute infarction: DWI, SWI, and PWI.

Science.gov (United States)

Kim, Yong-Woo; Kim, Hak Jin; Choi, Seon Hee; Kim, Dong Chan

2014-10-01

The multiple prominent hypointense veins on susceptibility-weighted imaging (SWI) have been found in the ischemic territory of patients with acute ischemic stroke. Venous side is the unknown area in the hemodynamics of brain infarction. To evaluate the venous aspect in acute brain infarction through an animal study. The acute infarction in cat brains was induced with a bolus infusion of 0.25 mL of triolein through one side of the common carotid artery. The magnetic resonance (MR) images, including diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) map, SW, and perfusion-weighted (PWI) images, were obtained serially at 2 h (n = 17), 1 day (n = 11), and 4 days (n = 4) after triolein infusion. The obtained MR images were evaluated qualitatively and quantitatively. For qualitative assessment, the signal intensity of the serial MR images was evaluated. The presence or absence and the location with serial changes of infarction were identified on DWI and ADC map images. The presence or absence of prominent hypointense veins and the serial changes of cortical veins were also evaluated on SWI. Quantitative assessment was performed by comparing the relative cerebral blood volume (rCBV), cerebral blood flow (rCBF), and mean transit times (MTT) of the lesions with those of the contralateral normal side calculated on PWI. The serial changes of rCBV, rCBF, and MTT ratio were also evaluated. Acute infarction in the first and second medial gyrus of lesion hemisphere was found by qualitative evaluation of DWI and ADC map images. On the serial evaluation of SWI, the cortical veins of cat brain with infarction were obscured at 2 h and then re-appeared at 1 day. The hemorrhage transformation and prominent hypointense veins were seen at 4 days on SWI. The quantitative evaluation revealed increased MTT ratios and decreased rCBV and rCBF ratios on PWIs in the acute infarction of cat brain. The prominent hypointense veins on SWI were seen in the half of the acute

Shaping corporate social responsibility management and reporting through engagement : The role of advocacy organisations

NARCIS (Netherlands)

Clune, C.

2017-01-01

Advocacy organisations have traditionally played a prominent role in shaping corporate social responsibility (CSR) management and reporting practices through organisational-level and institutional-level engagement. Recent years have seen advocacy organisations expand the nature and content of their

Modeling of prominence threads in magnetic fields: Levitation by incompressible MHD waves

Science.gov (United States)

Pécseli, Hans; Engvold, OddbjØrn

2000-05-01

The nature of thin, highly inclined threads observed in quiescent prominences has puzzled solar physicists for a long time. When assuming that the threads represent truly inclined magnetic fields, the supporting mechanism of prominence plasma against gravity has remained an open issue. This paper examines the levitation of prominence plasma exerted by weakly damped MHD waves in nearly vertical magnetic flux tubes. It is shown that the wave damping, and resulting `radiation pressure', caused predominantly by ion-neutral collisions in the `cold' prominence plasma, may balance the acceleration of gravity provided the oscillation frequency is ω~ 2 rad s^-1 (f~0.5 Hz). Such short wave periods may be the result of small-scale magnetic reconnections in the highly fragmentary magnetic field of quiescent prominences. In the proposed model, the wave induced levitation acts predominantly on plasma - neutral gas mixtures.

Line-shape asymmetry of water vapor absorption lines in the 720-nm wavelength region

Science.gov (United States)

Grossmann, Benoist E.; Browell, Edward V.

1991-01-01

Spectral line-shape analyses were performed for water vapor lines broadened by argon, oxygen, and xenon in the 720-nm wavelength region. A line-shape asymmetry was observed, which is attributed to statistical dependence or correlation between velocity- and state-changing collisions. The generalized (asymmetric) Galatry profile, which results from the soft-collision profile and includes correlation between velocity- and state-changing collisions, was fitted to the observed line shapes and was found to compare favorably with the observed data. The most prominent asymmetries were observed with xenon as the buffer gas.

Automatic detection of prominence (as defined by listeners' judgements) in read aloud Dutch sentences

NARCIS (Netherlands)

Streefkerk, B.M.; Pols, L.C.W.; ten Bosch, L.F.M.

1998-01-01

This paper describes a first step towards the automatic classification of prominence (as defined by native listeners). As a result of a listening experiment each word in 500 sentences was marked with a rating scale between `0' (non-prominent) and `10' (very prominent). These prominence labels are

Formation of H_2^+ and its Isotopomers by Radiative Association: the Role of Shape and Feshbach Resonances

Science.gov (United States)

Beyer, Maximilian; Merkt, Frederic

2017-06-01

The recent observations [1,2] of shape and Feshbach resonances in the high-resolution photoelectron spectra of H_2, HD and D_2 in the vicinity of the dissociation thresholds of H_2^+, HD^+ and D_2^+ raise questions concerning their potential role in the formation of H_2^+ and its isotopomers in the early universe by radiative association, a topic of astrophysical interest [3]. Close-coupling calculations for the cross sections of the reactions {H}^+ + {H} &\\to {H}_2^+ + hν {H}^+ + {D} &\\to {HD}^+ + hν {D}^+ + {H} &\\to {HD}^+ + hν {D}^+ + {D} &\\to {D}_2^+ + hν, will be presented which take into account nonadiabatic couplings involving rovibronic and hyperfine interactions, as well as relativistic and radiative corrections. The calculated energies and widths will be compared with the experimental results of Ref. [1,2] for H_2^+ and new data for HD^+ and D_2^+. The effect of the resonances on the radiative association rate coefficients will be discussed, also in comparison with earlier studies [4]. [1] M. Beyer and F. Merkt, Phys. Rev. Lett. 116, 093001 (2016). [2] M. Beyer and F. Merkt, J. Mol. Spectrosc. 330, 147 (2016). [3] Molecule formation in dust-poor environments, J. F. Babb and K. P. Kirby, in "The molecular astrophysics of stars and galaxies", T. W. Hartquist and D. A. Williams, eds., Oxford University Press, Oxford, 1998, pp. 11-34. [4] D. E. Ramaker and J. M. Peek, Phys. Rev. A 13, 58 (1976).

Fabrication of nanoplate resonating structures via micro-masonry

International Nuclear Information System (INIS)

Bhaswara, A; Legrand, B; Mathieu, F; Nicu, L; Leichle, T; Keum, H; Rhee, S; Kim, S

2014-01-01

Advantages of using nanoscale membrane and plate resonators over more common cantilever shapes include higher quality factor (Q factor) for an equivalent mass and better suitability to mass sensing applications in fluid. Unfortunately, the current fabrication methods used to obtain such membranes and plates are limited in terms of materials and thickness range, and can potentially cause stiction. This study presents a new method to fabricate nanoplate resonating structures based on micro-masonry, which is the advanced form of the transfer printing technique. Nanoplate resonators were fabricated by transfer printing 0.34 µm thick square-shaped silicon plates by means of polydimethylsiloxane microtip stamps on top of silicon oxide base structures displaying 20 µm diameter cavities, followed by a thermal annealing step to create a rigid bond. Typical resulting suspended structures display vibration characteristics, i.e. a resonance frequency of a few MHz and Q factors above 10 in air at atmospheric pressure, which are in accordance with theory. Moreover, the presented fabrication method enables the realization of multiple suspended structures in a single step and on the same single base, without mechanical crosstalk between the resonators. This work thus demonstrates the suitability and the advantages of the micro-masonry technique for the fabrication of plate resonators for mass sensing purpose. (paper)

Mode Coupling and Nonlinear Resonances of MEMS Arch Resonators for Bandpass Filters

KAUST Repository

Hajjaj, Amal Z.

2017-01-30

We experimentally demonstrate an exploitation of the nonlinear softening, hardening, and veering phenomena (near crossing), where the frequencies of two vibration modes get close to each other, to realize a bandpass filter of sharp roll off from the passband to the stopband. The concept is demonstrated based on an electrothermally tuned and electrostatically driven MEMS arch resonator operated in air. The in-plane resonator is fabricated from a silicon-on-insulator wafer with a deliberate curvature to form an arch shape. A DC current is applied through the resonator to induce heat and modulate its stiffness, and hence its resonance frequencies. We show that the first resonance frequency increases up to twice of the initial value while the third resonance frequency decreases until getting very close to the first resonance frequency. This leads to the phenomenon of veering, where both modes get coupled and exchange energy. We demonstrate that by driving both modes nonlinearly and electrostatically near the veering regime, such that the first and third modes exhibit softening and hardening behavior, respectively, sharp roll off from the passband to the stopband is achievable. We show a flat, wide, and tunable bandwidth and center frequency by controlling the electrothermal actuation voltage.

Interaction between confined phonons and photons in periodic silicon resonators

Science.gov (United States)

Iskandar, A.; Gwiazda, A.; Younes, J.; Kazan, M.; Bruyant, A.; Tabbal, M.; Lerondel, G.

2018-03-01

In this paper, we demonstrate that phonons and photons of different momenta can be confined and interact with each other within the same nanostructure. The interaction between confined phonons and confined photons in silicon resonator arrays is observed by means of Raman scattering. The Raman spectra from large arrays of dielectric silicon resonators exhibited Raman enhancement accompanied with a downshift and broadening. The analysis of the Raman intensity and line shape using finite-difference time-domain simulations and a spatial correlation model demonstrated an interaction between photons confined in the resonators and phonons confined in highly defective regions prompted by the structuring process. It was shown that the Raman enhancement is due to collective lattice resonance inducing field confinement in the resonators, while the spectra downshift and broadening are signatures of the relaxation of the phonon wave vector due to phonon confinement in defective regions located in the surface layer of the Si resonators. We found that as the resonators increase in height and their shape becomes cylindrical, the amplitude of their coherent oscillation increases and hence their ability to confine the incoming electric field increases.

Wideband Bandpass Filter with High Selectivity and an Adjustable Notched-band Adopting a Multi-mode Resonator

Science.gov (United States)

Ma, Xing-Bing; Jiang, Ting

2018-04-01

A wideband bandpass filter (BPF) with an adjustable notched-band and high selectivity is proposed. The proposed BPF consists of a multi-mode resonator (MMR), two λ/2 resonators, and I/O feed lines with 50 ohm characteristic impedance. The MMR, connected as a whole by a wide stub, is composed of one I-shaped resonator and two open-loop resonators. Tightly coupling is built between MMR and λ/2 resonators. I/O feed lines are directly connected with two λ/2 resonators, respectively. Due to the use of tapped-line coupling, one transmission zero (TZ) is formed near low-edge of aim passband. High-edge of passband with one attendant TZ can be tuned to desired location by adjusting bottom-side position of used wide stub or bottom-side length of I-shaped resonator in MMR. The top-side length of I-shaped resonator is applied to improve upper stopband performance and shift undesired resonant mode of MMR near high-edge of aim passband to proper frequency point. The notched-band in aim passband is dominated by top-side position of wide stub in MMR. Good agreement is observed between simulated and measured results.

Design and fabrication of bandwidth tunable HTS transmit filter using {pi}-shaped waveguides

Energy Technology Data Exchange (ETDEWEB)

Sekiya, N., E-mail: nsekiya@yamanashi.ac.j [Department of Electrical Engineering, Yamanashi University, Nakagawa-Sekiya Laboratory, 4-3-11 Takeda, Kofu 400-8511 (Japan); Harada, H.; Nakagawa, Y. [Department of Electrical Engineering, Yamanashi University, Nakagawa-Sekiya Laboratory, 4-3-11 Takeda, Kofu 400-8511 (Japan); Ono, S.; Ohshima, S. [Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510 (Japan)

2010-11-01

We have developed a method for tuning the bandwidth of a high-temperature superconducting (HTS) microstrip filter. Several {pi}-shaped waveguides are placed between the resonators, and the bandwidth is tuned in discrete steps by changing the switch states of the waveguides, which changes the coupling coefficient between the resonators. The filter contains 3-pole half-wavelength straight-line resonators and two {pi}-shaped waveguides for bandwidth tuning. It also has several electrical pads distributed around the feed lines for trimming after tuning. The filter was fabricated by depositing YBa{sub 2}Cu{sub 3}O{sub 7} thin film on an MgO substrate and has a measured center frequency of 5.17 GHz and bandwidth of 220 MHz. Use of the {pi}-shaped waveguides to adjust the coupling coefficients and the electrical pads to adjust the external quality factors resulted in 80-MHz bandwidth tuning without increased insertion loss.

Multiple-band reflective polarization converter using U-shaped metamaterial

International Nuclear Information System (INIS)

Huang, Xiaojun; Yang, Dong; Yang, Helin

2014-01-01

A multiple-band metamaterial reflective polarization converter (RPC) is proposed, which is composed of the dielectric substrate sandwiched with U-shaped metallic patterns and continuous metal film. The proposed U-shaped metamaterial RPC (UMM-RPC) can convert a linearly polarized wave to its cross polarized wave at the three resonant frequencies, which also can convert the linearly polarized wave to circularly polarized wave at other three resonant frequencies. Furthermore, the proposed UMM-RPC can maintain the same conversional direction at the three resonant frequencies when incident on a circularly polarized wave. The simulated and measured results are in agreement in the entire frequency range, and the polarization conversion ratio is over 90% for both linear and circular polarizations. The surface current distributions of the UMM-RPC are discussed to look into the physical mechanism. The proposed UMM-RPC has simple geometry but more operating frequency bands compared to the previous designs and can be used in applications such as antenna radome, remote sensors, and radiometer

Multiple-band reflective polarization converter using U-shaped metamaterial

Energy Technology Data Exchange (ETDEWEB)

Huang, Xiaojun [College of Physical Science and Technology, Central China Normal University, Wuhan 430079 (China); Department of Physics, Kashgar Teachers College, Kashgar 844000 (China); Yang, Dong [College of Physics and Electronics Science, Hubei Normal University, Huangshi 435002 (China); Yang, Helin, E-mail: emyang@mail.ccnu.edu.cn [College of Physical Science and Technology, Central China Normal University, Wuhan 430079 (China)

2014-03-14

A multiple-band metamaterial reflective polarization converter (RPC) is proposed, which is composed of the dielectric substrate sandwiched with U-shaped metallic patterns and continuous metal film. The proposed U-shaped metamaterial RPC (UMM-RPC) can convert a linearly polarized wave to its cross polarized wave at the three resonant frequencies, which also can convert the linearly polarized wave to circularly polarized wave at other three resonant frequencies. Furthermore, the proposed UMM-RPC can maintain the same conversional direction at the three resonant frequencies when incident on a circularly polarized wave. The simulated and measured results are in agreement in the entire frequency range, and the polarization conversion ratio is over 90% for both linear and circular polarizations. The surface current distributions of the UMM-RPC are discussed to look into the physical mechanism. The proposed UMM-RPC has simple geometry but more operating frequency bands compared to the previous designs and can be used in applications such as antenna radome, remote sensors, and radiometer.

Design of bandwidth tunable HTS filter using H-shaped waveguides

Energy Technology Data Exchange (ETDEWEB)

Koike, Y. [Department of Electrical Engineering, University of Yamanashi, Nakagawa-Sekiya Laboratory, 4-3-11 Takeda, Kofu 400-8511 (Japan); Sekiya, N., E-mail: nsekiya@yamanashi.ac.j [Department of Electrical Engineering, University of Yamanashi, Nakagawa-Sekiya Laboratory, 4-3-11 Takeda, Kofu 400-8511 (Japan); Nakagawa, Y. [Department of Electrical Engineering, University of Yamanashi, Nakagawa-Sekiya Laboratory, 4-3-11 Takeda, Kofu 400-8511 (Japan); Ohshima, S. [Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510 (Japan)

2009-10-15

We have developed a bandwidth tuning method for use in high-temperature superconducting (HTS) microstrip filters. Several H-shaped waveguides are placed between the resonators, and the bandwidth is adjusted by changing the switch states of the waveguides. The coupling coefficients between the resonators are controlled by switching the connection or isolation of the center gaps of the waveguides so as to tune the bandwidth. The effects of using this method were evaluated by simulation using a filter composed of 3-pole half-wavelength straight-line resonators with an H-shaped waveguide between each pair and additional electric pads for post-tuning trimming. The filter was designed to have a center frequency of 5 GHz and a bandwidth of 100 MHz by using an electromagnetic simulator based on the moment method. The simulation showed that bandwidth tuning of 150 MHz can be obtained by using H-shaped waveguides to adjust the coupling coefficients. It also showed that using additional electric pads around the feed lines, which was previously shown to be useful for trimming to improve insertion loss after center-frequency tuning, is also useful for bandwidth tuning.

Intrinsic Energy Dissipation Limits in Nano and Micromechanical Resonators

Science.gov (United States)

Iyer, Srikanth Subramanian

Resonant microelectromechanical Systems (MEMS) have enabled miniaturization of high-performance inertial sensors, radio-frequency filters, timing references and mass-based chemical sensors. Despite the increasing prevalence of MEMS resonators for these applications, the energy dissipation in these structures is not well-understood. Accurate prediction of the energy loss and the resulting quality factor (Q) has significant design implications because it is directly related to device performance metrics including sensitivity for resonant sensors, bandwidth for radio-frequency filters and phase-noise for timing references. In order to assess the future potential for MEMS resonators it is critically important to evaluate the energy dissipation limits, which will dictate the ultimate performance resonant MEMS devices can achieve. This work focuses on the derivation and evaluation of the intrinsic mechanical energy dissipation limit for single-crystal nano and micromechanical resonators due to anharmonic phonon-phonon scattering in the Akhiezer regime. The energy loss is derived using perturbation theory and the linearized Boltzmann transport equation for phonons, and includes the direction and polarization dependent mode-Gruneisen parameters in order to capture the strain-induced anharmonicity among phonon branches. Evaluation of the quality factor limit reveals that Akhiezer damping, previously thought to depend only on material properties, has a strong dependence on crystal orientation and resonant mode shape. The robust model provides a dissipation limit for all resonant modes including shear-mode vibrations, which have significantly reduced energy loss because dissipative phonon-phonon scattering is restricted to volume-preserving phonon branches, indicating that Lame or wine-glass mode resonators will have the highest upper limit on mechanical efficiency. Finally, the analytical dissipation model is integrated with commercial finite element software in order to

Quantum Computation with Ultrafast Laser Pulse Shaping

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 6. Quantum Computation with Ultrafast Laser Pulse Shaping. Debabrata Goswami. General Article Volume 10 Issue 6 June 2005 pp 8-14. Fulltext. Click here to view fulltext PDF. Permanent link:

Computer aided design of Langasite resonant cantilevers: analytical models and simulations

Science.gov (United States)

Tellier, C. R.; Leblois, T. G.; Durand, S.

2010-05-01

Analytical models for the piezoelectric excitation and for the wet micromachining of resonant cantilevers are proposed. Firstly, computations of metrological performances of micro-resonators allow us to select special cuts and special alignment of the cantilevers. Secondly the self-elaborated simulator TENSOSIM based on the kinematic and tensorial model furnishes etching shapes of cantilevers. As the result the number of selected cuts is reduced. Finally the simulator COMSOL® is used to evaluate the influence of final etching shape on metrological performances and especially on the resonance frequency. Changes in frequency are evaluated and deviating behaviours of structures with less favourable built-ins are tested showing that the X cut is the best cut for LGS resonant cantilevers vibrating in flexural modes (type 1 and type 2) or in torsion mode.

Scattering analysis of asymmetric metamaterial resonators by the Riemann-Hilbert approach

DEFF Research Database (Denmark)

Kaminski, Piotr Marek; Ziolkowski, Richard W.; Arslanagic, Samel

2016-01-01

This work presents an analytical treatment of an asymmetric metamaterial-based resonator excited by an electric line source, and explores its beam shaping capabilities. The resonator consists of two concentric cylindrical material layers covered with an infinitely thin conducting shell with an ap......This work presents an analytical treatment of an asymmetric metamaterial-based resonator excited by an electric line source, and explores its beam shaping capabilities. The resonator consists of two concentric cylindrical material layers covered with an infinitely thin conducting shell...... with an aperture. Exact analytical solution of the problem is derived; it is based on the n-series approach which is casted into the equivalent Riemann-Hilbert problem. The examined configuration leads to large enhancements of the radiated field and to steerable Huygens-like directivity patterns. Particularly...

Modal optimization and filtering in piezoelectric microplate resonators

International Nuclear Information System (INIS)

Sanchez-Rojas, J L; Hernando, J; Donoso, A; Bellido, J C; Manzaneque, T; Ababneh, A; Seidel, H; Schmid, U

2010-01-01

A systematic design procedure to tailor the modal response of micro-resonators based on flexible plates with piezoelectric films is demonstrated. Sensors/actuators were designed by optimizing the surface electrode shapes in the plane dimensions. A numerical finite element procedure, which considers the effective surface electrode covering the piezoelectric film as a binary function on each element, has been implemented. Two design goals are considered: (i) optimized response (actuation or sensing) in a given mode; (ii) implementation of a modal transducer by filtering specific modes. For a given mode in a plate with arbitrary boundary conditions, our calculations allowed us to predict the top electrode layout reaching higher displacement in resonance than any other electrode design for the same structure. Microcantilevers and microbridges were fabricated and their modal response characterized by laser Doppler vibrometry. In comparison to a conventional square-shaped electrode, our experiments show that the implemented designs can increase the response in any desired resonant mode and simultaneously attenuate the contributions from other unwanted modes, by simply shaping the surface electrodes. Enhancement ratios as high as 42 dB, relative to a full-size electrode case, are demonstrated. The limitations imposed by the fabrication are also discussed.

Motions in Prominence Barbs as observed by Hinode/SOT and IRIS

Science.gov (United States)

Kucera, Therese A.; Ofman, Leon; Tarbell, Theodore D.

2016-05-01

We discuss observations of prominence barb dynamics as observed by Hinode/SOT and IRIS. Prominence barbs extend outwards to the side of the main prominence spine and downwards towards the chromosphere. Their properties, including the structure of their magnetic field and the nature of the motions observed in them are a subject of current debate. We use a combination of high cadence, high resolution imaging, H-alpha Doppler, and Mg II line profile data to analyze and understand waves and flows in barbs and discuss their ramifications in terms of a model of the barb magnetic field as collection of dipped field lines.

CRITICAL HEIGHT FOR THE DESTABILIZATION OF SOLAR PROMINENCES: STATISTICAL RESULTS FROM STEREO OBSERVATIONS

Energy Technology Data Exchange (ETDEWEB)

Liu Kai; Wang Yuming; Wang Shui; Shen Chenglong, E-mail: ymwang@ustc.edu.cn [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2012-01-10

At which height is a prominence inclined to be unstable, or where is the most probable critical height for the prominence destabilization? This question was statistically studied based on 362 solar limb prominences well recognized by Solar Limb Prominence Catcher and Tracker from 2007 April to the end of 2009. We found that there are about 71% disrupted prominences (DPs), among which about 42% of them did not erupt successfully and about 89% of them experienced a sudden destabilization process. After a comprehensive analysis of the DPs, we discovered the following: (1) Most DPs become unstable at a height of 0.06-0.14 R{sub Sun} from the solar surface, and there are two most probable critical heights at which a prominence is very likely to become unstable, the first one is 0.13 R{sub Sun} and the second one is 0.19 R{sub Sun }. (2) An upper limit for the erupting velocity of eruptive prominences (EPs) exists, which decreases following a power law with increasing height and mass; accordingly, the kinetic energy of EPs has an upper limit too, which decreases as the critical height increases. (3) Stable prominences are generally longer and heavier than DPs, and not higher than 0.4 R{sub Sun }. (4) About 62% of the EPs were associated with coronal mass ejections (CMEs); but there is no difference in apparent properties between EPs associated with CMEs and those that are not.

CRITICAL HEIGHT FOR THE DESTABILIZATION OF SOLAR PROMINENCES: STATISTICAL RESULTS FROM STEREO OBSERVATIONS

International Nuclear Information System (INIS)

Liu Kai; Wang Yuming; Wang Shui; Shen Chenglong

2012-01-01

At which height is a prominence inclined to be unstable, or where is the most probable critical height for the prominence destabilization? This question was statistically studied based on 362 solar limb prominences well recognized by Solar Limb Prominence Catcher and Tracker from 2007 April to the end of 2009. We found that there are about 71% disrupted prominences (DPs), among which about 42% of them did not erupt successfully and about 89% of them experienced a sudden destabilization process. After a comprehensive analysis of the DPs, we discovered the following: (1) Most DPs become unstable at a height of 0.06-0.14 R ☉ from the solar surface, and there are two most probable critical heights at which a prominence is very likely to become unstable, the first one is 0.13 R ☉ and the second one is 0.19 R ☉ . (2) An upper limit for the erupting velocity of eruptive prominences (EPs) exists, which decreases following a power law with increasing height and mass; accordingly, the kinetic energy of EPs has an upper limit too, which decreases as the critical height increases. (3) Stable prominences are generally longer and heavier than DPs, and not higher than 0.4 R ☉ . (4) About 62% of the EPs were associated with coronal mass ejections (CMEs); but there is no difference in apparent properties between EPs associated with CMEs and those that are not.

STRUCTURE OF PROMINENCE LEGS: PLASMA AND MAGNETIC FIELD

Energy Technology Data Exchange (ETDEWEB)

Levens, P. J.; Labrosse, N. [SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ (United Kingdom); Schmieder, B. [Observatoire de Paris, Meudon, F-92195 (France); Ariste, A. López, E-mail: p.levens.1@research.gla.ac.uk [Institut de Recherche en Astrophysique et Planétologie, Toulouse (France)

2016-02-10

We investigate the properties of a “solar tornado” observed on 2014 July 15, and aim to link the behavior of the plasma to the internal magnetic field structure of the associated prominence. We made multi-wavelength observations with high spatial resolution and high cadence using SDO/AIA, the Interface Region Imaging Spectrograph (IRIS) spectrograph, and the Hinode/Solar Optical Telescope (SOT) instrument. Along with spectropolarimetry provided by the Télescope Héliographique pour l’Etude du Magnétisme et des Instabilités Solaires telescope we have coverage of both optically thick emission lines and magnetic field information. AIA reveals that the two legs of the prominence are strongly absorbing structures which look like they are rotating, or oscillating in the plane of the sky. The two prominence legs, which are both very bright in Ca ii (SOT), are not visible in the IRIS Mg ii slit-jaw images. This is explained by the large optical thickness of the structures in Mg ii, which leads to reversed profiles, and hence to lower integrated intensities at these locations than in the surroundings. Using lines formed at temperatures lower than 1 MK, we measure relatively low Doppler shifts on the order of ±10 km s{sup −1} in the tornado-like structure. Between the two legs we see loops in Mg ii, with material flowing from one leg to the other, as well as counterstreaming. It is difficult to interpret our data as showing two rotating, vertical structures that are unrelated to the loops. This kind of “tornado” scenario does not fit with our observations. The magnetic field in the two legs of the prominence is found to be preferentially horizontal.

Non-LTE hydrogen-line formation in moving prominences

Science.gov (United States)

Heinzel, P.; Rompolt, B.

1986-01-01

The behavior of hydrogen-line brightness variations, depending on the prominence-velocity changes were investigated. By solving the NON-Local thermodynamic equilibrium (LTE) problem for hydrogen researchers determine quantitatively the effect of Doppler brightening and/or Doppler dimming (DBE, DDE) in the lines of Lyman and Balmer series. It is demonstrated that in low-density prominence plasmas, DBE in H alpha and H beta lines can reach a factor of three for velocities around 160 km/sec, while the L alpha line exhibits typical DDE. L beta brightness variations follow from a combined DBE in the H alpha and DDE in L alpha and L beta itself, providing that all relevant multilevel interlocking processes are taken into account.

Coherent enhancement of resonance-mediated multiphoton absorption

International Nuclear Information System (INIS)

Zhang, Shian; Zhang, Hui; Jia, Tianqing; Wang, Zugeng; Sun, Zhenrong

2010-01-01

In this paper, we theoretically investigate the coherent enhancement of resonance-mediated (2+2) four-photon absorption. It is found that by shaping the spectral phase with a π phase step, the resonance-mediated (2+2) four-photon transition probability can be enhanced. Furthermore, the coherent enhancement dependences on the detuning between the two two-photon absorptions, laser spectral bandwidth and laser centre frequency are explicitly discussed and analysed. We believe these theoretical results may play an important role in enhancing more complex resonance-mediated multiphoton absorption processes.

The '0.4 eV' shape resonance of electron scattering from mercury in a Franck-Hertz tube

International Nuclear Information System (INIS)

Nicoletopoulos, Peter

2004-01-01

The alternative version of the Franck-Hertz experiment with mercury, in which a two-grid tube is used as a combination of electron gun, equipotential collision space and detection cell, was analysed recently in considerable detail. In particular, it was inferred that, at optimal pressure, the formation of peaks in the anode current at inelastic thresholds is mediated inside the detection cell by the large variation, a maximum at 0.4 eV, in the cross section for elastic scattering. This variation is due to a shape resonance in the electron-mercury system and is observable persuasively at the onset of anode current as a sharp peak followed by a clear minimum. In this paper, the passage of electrons through the second grid to the anode region is analysed in terms of kinetic theory. The discussion is based on a simplified expression for the electron current derivable from an approximate form of the Boltzmann transport equation that maintains the spatial density gradient but omits elastic energy losses. The estimated range of pressure underlying this kind of idealization is in good agreement with experiment. An explicit solution is obtained by constructing an analytic expression for the momentum transfer cross section of mercury using a recent theory of generalized Fano profiles for overlapping resonances. This solution is used in order to model successfully the formation of peaks at the threshold of anode current and at excitation potentials, and to explain the dependence of the observed profiles on the pressure and on the sign and magnitude of the potential across the detection cell

A multilevel shape fit analysis of neutron transmission data

International Nuclear Information System (INIS)

Naguib, K.; Sallam, O.H.; Adib, M.

1989-01-01

A multilevel shape fit analysis of neutron transmission data is presented. A multilevel computer code SHAPE is used to analyse clean transmission data obtained from time-of-flight (TOF) measurements. The shape analysis deduces the parameters of the observed resonances in the energy region considered in the measurements. The shape code is based upon a least square fit of a multilevel Breit-Wigner formula and includes both instrumental resolution and Doppler broadenings. Operating the SHAPE code on a test example of a measured transmission data of 151 Eu, 153 Eu and natural Eu in the energy range 0.025-1 eV acquired a good result for the used technique of analysis. (author)

High Resolution, High-Speed Photography, an Increasingly Prominent Diagnostic in Ballistic Research Experiments

International Nuclear Information System (INIS)

Shaw, L.; Muelder, S.

1999-01-01

High resolution, high-speed photography is becoming a prominent diagnostic in ballistic experimentation. The development of high speed cameras utilizing electro-optics and the use of lasers for illumination now provide the capability to routinely obtain high quality photographic records of ballistic style experiments. The purpose of this presentation is to review in a visual manner the progress of this technology and how it has impacted ballistic experimentation. Within the framework of development at LLNL, we look at the recent history of large format high-speed photography, and present a number of photographic records that represent the state of the art at the time they were made. These records are primarily from experiments involving shaped charges. We also present some examples of current photographic technology, developed within the ballistic community, that has application to hydro diagnostic experimentation at large. This paper is designed primarily as an oral-visual presentation. This written portion is to provide general background, a few examples, and a bibliography

Nuclear magnetic resonance line-shape analysis and determination of exchange rates

International Nuclear Information System (INIS)

Rao, B.D.

1989-01-01

The fact that chemical exchange processes occur at rates that cover a broad range and produce readily detectable effects on the spectrum is one of the attractive features of high-resolution NMR. The description of these line shapes in the presence of spin-spin coupling requires the density matrix theory which is rather complex. Analysis of the line shapes usually needs computer simulations and is capable of providing reliable information on the exchange rates as well as spectral parameters in the absence of exchange. Simplified procedures, ignoring spin-spin coupling, often result in deviations in these exchange and spectral parameters determined. A step-by-step procedure is detailed in this chapter for setting up the matrices required for computing the line shapes of exchanges involving weakly coupled spin systems on the basis of the density matrix theory without the need for a detailed understanding of the theory. A knowledge of the energy level structure and allowed transitions in the NMR spectra of the individual weakly coupled spin systems is all that is required. The procedure is amenable to numerical computation. The group of illustrative examples chosen to demonstrate the development of the computational tools cover some of the commonly encountered cases of exchange from simple systems to rather complex ones. Such exchanges occur frequently in biological molecules, especially those involving enzyme-substrate complexes. In cases where the experimental line shapes are obtained with respectable precision, and the relevant exchange processes are unambiguously identifiable, the computer simulation method of line-shape analysis is capable of providing useful and incisive information. The example of the 31P exchanges in the adenylate kinase is illustrative of this point

Contribution to the study of solar prominences from observations performed on the LPSP instrument aboard the OSO-8 satellite

International Nuclear Information System (INIS)

Vial, Jean-Claude

1981-01-01

Notably by reprinting various documents and articles, this research reports works undertaken from the design of an experiment performed with the LPSP instrument aboard the OSO-8 satellite, to its data processing and interpretation. This experiment aimed at the study of the chromosphere fine structure by means of simultaneous high resolution observations of the L α, L β, Mg II, Ca II, H and K lines. The first part presents the on-board LPSP instrument. The second part reports observations of active and quiescent solar prominences. The third part reports the transfer calculation for five resonance lines (H Lα, Mg II H and K, Ca II H and K), and the comparison with observations performed on OSO-8

Magnetic resonance imaging of muscle tears

International Nuclear Information System (INIS)

De Smet, A.A.; Fisher, D.R.; Heiner, J.P.; Keene, J.S.

1990-01-01

Magnetic resonance scans were obtained on 17 patients with acute, subacute, or chronic muscle tears. These patients presented with complaints of persistent pain or a palpable mass. Magnetic resonance findings were characterized according to alterations in muscle shape and the presence of abnormal high signal within the injured muscle. These areas of high signal were noted on both T1-weighted and T2-weighted scans and were presumed to represent areas of intramuscular hemorrhage. (orig.)

Observation of electrons from the 1P0 resonance of D-

International Nuclear Information System (INIS)

Duncan, M.M.; Menendez, M.G.

1989-01-01

We have measured the electron energy spectra near 0 0 produced in collisions of D - with Ar. Using a 400-keV D - beam and with good experimental energy and angular resolution we have found structure in the ejected electron energy spectra which is due to the decay of the 1 P 0 shape resonance. The doubly differential cross sections (DDCS's) have been measured as a function of angle and it was found that this structure disappeared for laboratory angles greater than 1 0 as expected. A resonance contribution to the DDCS's was extracted at θ/sub L/ = 0 0 , transformed to the projectile frame, and fit with a Breit-Wigner shape. Our resonant energy is in reasonable agreement with other experiments. We also find a small asymmetry in the two resonant structures in the laboratory measurements at θ/sub L/ = 0 0

Chest roentgenographic findings of thymic size and shape in respiratory distress syndrome

International Nuclear Information System (INIS)

Oh, Young Ho; Yoon, Sung Do; Sung, Ki Yeal; Park, Seog Hee; Kim, Jong Woo; Bahk, Yong Whee

1984-01-01

Thymic size can be affected by both exogenous and endogenous glucocorticoids. Development of the respiratory distress syndrome (RDS) is influenced by adrenal cortical function. Thus, thymic size in RDS is considered to be enlarged due to decreased adrenal cortical function. To find whether the presence of RDS correlates with the thymus, the size and shape of the thymus were evaluated in the radiographs of premature infants with RDS, without RDS (control prematurity) and normal infants. The subjects were consisted of chest films of Korean premature infants, 120 with RDS, 60 without RDS, and 60 of normal infants taken at the Department of Radiology, Our Lady of Mercy Hospital during the period of 62 months since January 1978. Relative size of the thymus was determine by cardiothymic/thoracic ratio (CT /T ratio). Grading and location of the thymic prominence as well as incidence of the shape were examined. And all the relations among the radiographs of RDS, control prematurity and normal infants were analyzed. The results were as follows: 1. The CT/T ratio of premature infants with RDS was significantly greater than that of control prematurity and normal infants (P< 0.01). 2. The incidence of bilateral thymic prominence was more frequent in premature infant with RDS than in control prematurity and normal infants (P<0.05). 3. The frequency of thymic prominence was greater in the right than left side in all the three groups (P<0.05). 4. As in the shape of the thymus, a rounded type was most frequent, and a triangular type was least frequent in all three groups. 5. Incident of RDS was very low (9.8%) when the CT/T ratio is below 0.3 and it was very high (90.9%) when the CT/T ratio is above 0.49.

PATTERNS OF FLOWS IN AN INTERMEDIATE PROMINENCE OBSERVED BY HINODE

International Nuclear Information System (INIS)

Ahn, Kwangsu; Chae, Jongchul; Cao Wenda; Goode, Philip R.

2010-01-01

The investigation of plasma flows in filaments/prominences gives us clues to understanding their magnetic structures. We studied the patterns of flows in an intermediate prominence observed by Hinode/SOT. By examining a time series of Hα images and Ca II H images, we have found horizontal flows in the spine and vertical flows in the barb. Both of these flows have a characteristic speed of 10-20 km s -1 . The horizontal flows displayed counterstreaming. Our detailed investigation revealed that most of the moving fragments in fact reversed direction at the end point of the spine near a footpoint close to the associated active region. These returning flows may be one possible explanation of the well-known counterstreaming flows in prominences. In contrast, we have found vertical flows-downward and upward-in the barb. Most of the horizontal flows in the spine seem to switch into vertical flows when they approach the barb, and vice versa. We propose that the net force resulting from a small deviation from magnetohydrostatic equilibrium, where magnetic fields are predominantly horizontal, may drive these patterns of flow. In the prominence studied here, the supposed magnetohydrostatic configuration is characterized by magnetic field lines sagging with angles of 13 0 and 39 0 in the spine and the barb, respectively.

Enhanced spin polarization of elastic electron scattering from alkaline-earth-metal atoms in Ramsauer-Townsend and low-lying shape resonance regions

International Nuclear Information System (INIS)

Yuan, J.; Zhang, Z.

1993-01-01

Spin polarizations (SP's) of elastic electron scattering from alkaline-earth-metal atoms in Ramsauer-Townsend (RT) and low-lying shape resonance (SR) regions are calculated using a relativistic method. The detailed SP distributions both with scattering angle and with electron energy are presented via the energy- and angle-dependent surfaces of SP parameters. It is shown that the SP effects of the collisions of electrons with Ca, Sr, and Ba atoms in the RT region are significant in a considerable area on the energy-angle plane and that the spin-orbit interaction is well increased around the low-lying p-wave SR states of Be and Mg and the d-wave SR states of Ca, Sr, and Ba

Resonance – Journal of Science Education | Indian Academy of ...

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education. S Kesavan. Articles written in Resonance – Journal of Science Education. Volume 3 Issue 9 September 1998 pp 26-34 General Article. Listening to the Shape of a Drum - The Mathematics of Vibrating Drums · S Kesavan · More Details Fulltext PDF. Volume 3 ...

A parabolic model to control quantum interference in T-shaped molecular junctions

DEFF Research Database (Denmark)

Nozaki, Daijiro; Sevincli, Haldun; Avdoshenko, Stanislav M.

2013-01-01

Quantum interference (QI) effects in molecular devices have drawn increasing attention over the past years due to their unique features observed in the conductance spectrum. For the further development of single molecular devices exploiting QI effects, it is of great theoretical and practical...... interest to develop simple methods controlling the emergence and the positions of QI effects like anti-resonances or Fano line shapes in conductance spectra. In this work, starting from a well-known generic molecular junction with a side group (T-shaped molecule), we propose a simple graphical method...... to visualize the conditions for the appearance of quantum interference, Fano resonances or anti-resonances, in the conductance spectrum. By introducing a simple graphical representation (parabolic diagram), we can easily visualize the relation between the electronic parameters and the positions of normal...

A review of magnetic resonance imaging in spinal trauma

International Nuclear Information System (INIS)

Davis, S.J.; Khangure, M.S.

1994-01-01

One hundred and ninety-five magnetic resonance (MR) images of 167 patients with neurological impairment following spinal trauma were reviewed. Acute cord injury produces central haemorrhagic necrosis that extends transversely and longitudinally with time and increased injury severity. Oedema appears more homogeneous, extensive and dominant in minimal lesions. Magnetic resonance appearances correlate with neurological status and outcome. Patients with MR evidence of cord blood had severe clinical lesions and failed to show useful clinical improvement. Patients with homogeneous 'oedema' improved to useful function. Lesion signal inhomogeneity relates to a worse prognosis. The clinical level correlates closely with cord blood or signal in homogeneity but imprecisely with homogeneous oedema. Disc herniations require differentiation from epidural blood and venous engorgement, which are prominent with bone displacement. Magnetic resonance is recommended in incomplete cord syndromes and in cord injuries with no apparent fracture, particularly of clinically deteriorating. 18 ref., 2 figs., 3 tabs

Structural resonance and mode of flutter of hummingbird tail feathers.

Science.gov (United States)

Clark, Christopher J; Elias, Damian O; Girard, Madeline B; Prum, Richard O

2013-09-15

Feathers can produce sound by fluttering in airflow. This flutter is hypothesized to be aeroelastic, arising from the coupling of aerodynamic forces to one or more of the feather's intrinsic structural resonance frequencies. We investigated how mode of flutter varied among a sample of hummingbird tail feathers tested in a wind tunnel. Feather vibration was measured directly at ~100 points across the surface of the feather with a scanning laser Doppler vibrometer (SLDV), as a function of airspeed, Uair. Most feathers exhibited multiple discrete modes of flutter, which we classified into types including tip, trailing vane and torsional modes. Vibratory behavior within a given mode was usually stable, but changes in independent variables such as airspeed or orientation sometimes caused feathers to abruptly 'jump' from one mode to another. We measured structural resonance frequencies and mode shapes directly by measuring the free response of 64 feathers stimulated with a shaker and recorded with the SLDV. As predicted by the aeroelastic flutter hypothesis, the mode shape (spatial distribution) of flutter corresponded to a bending or torsional structural resonance frequency of the feather. However, the match between structural resonance mode and flutter mode was better for tip or torsional mode shapes, and poorer for trailing vane modes. Often, the 3rd bending structural harmonic matched the expressed mode of flutter, rather than the fundamental. We conclude that flutter occurs when airflow excites one or more structural resonance frequencies of a feather, most akin to a vibrating violin string.

Listening to the Shape of a Drum

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 9. Listening to the Shape of a Drum - The Mathematics of Vibrating Drums. S Kesavan. General Article Volume 3 Issue 9 September 1998 pp 26-34. Fulltext. Click here to view fulltext PDF. Permanent link:

Effect of Initial Curvature on the Static and Dynamic Behavior of MEMS Resonators

KAUST Repository

Hajjaj, Amal Z.

2017-11-03

In this paper, we investigate experimentally and analytically the effect of the initial shape, arc and cosine wave, on the static and dynamic behavior of microelectromechanical (MEMS) resonators. We show that by carefully choosing the geometrical parameters and the shape of curvature, the veering phenomenon (avoided-crossing) between the first two symmetric modes can be activated. To demonstrate this concept, we study electrothermally tuned and electrostatically driven MEMS initially curved resonators. Applying electrothermal voltage heats up the beams and then increases their curvature (stiffness) and controls their resonance frequencies. While changing the electrothermal voltage, we demonstrate high frequency tunability of arc resonators compared to the cosine-configuration resonators for the first and third resonance frequencies. For arc beams, we show that the first resonance frequency increases up to twice its fundamental value and the third resonance frequency decreases until getting very close to the first resonance frequency triggering the veering phenomenon. Around the veering regime, we study experimentally and analytically, using a reduced order model based on a nonlinear Euler-Bernoulli shallow arch beam model, the dynamic behavior of the arc beam for different electrostatic forcing.

On Lyman-line asymmetries in quiescent prominences

Czech Academy of Sciences Publication Activity Database

Gunár, Stanislav; Heinzel, Petr; Anzer, U.; Schmieder, B.

2008-01-01

Roč. 490, č. 1 (2008), s. 307-313 ISSN 0004-6361 Grant - others:EU(XE) ESA-PECS project No. 98030 Institutional research plan: CEZ:AV0Z10030501 Keywords : Sun prominences * radiative transfer * line profiles Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.153, year: 2008

Topic Prominence in Chinese EFL Learners' Interlanguage

Science.gov (United States)

Li, Shaopeng; Yang, Lianrui

2014-01-01

The present study aims to investigate the general characteristics of topicprominent typological interlanguage development of Chinese learners of English in terms of acquiring subject-prominent English structures from a discourse perspective. Topic structures mainly appear in Chinese discourse in the form of topic chains (Wang, 2002; 2004). The…

Tunable wavelength demultiplexer using modified graphene plasmonic split ring resonators for terahertz communication

Science.gov (United States)

Joshi, Neetu; Pathak, Nagendra P.

2018-02-01

This paper presents graphene modified ring resonator based wavelength demultiplexer (WDM) for THz device applications that is, a surface plasmon polaritons (SPPs) demultiplexer consisting of two nanostrip waveguides at input as well as output coupled to each other by a split ring resonator (SRR), which is modified in shape as compared to a simple ring-shaped resonator. A systematic analysis of the transmission spectra for the graphene based SRR poses clear insight on the demultiplexing phenomenon of the proposed nanodevice. The results show resonance peaks in the transmission spectrum, having a linear relationship with the chemical potential of graphene. The influence of structural parameters have also been analyzed. The tuning capability of graphene based tunable WDM, lays its foundation in the applications of optical switches, modulators, etc.

Calculation of the resonance cross section functions

International Nuclear Information System (INIS)

Slipicevic, K.F.

1967-11-01

This paper includes the procedure for calculating the Doppler broadened line shape functions ψ and χ which are needed for calculation of resonance cross section functions. The obtained values are given in tables

Calculation of the resonance cross section functions

Energy Technology Data Exchange (ETDEWEB)

Slipicevic, K F [Institute of nuclear sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

1967-11-15

This paper includes the procedure for calculating the Doppler broadened line shape functions {psi} and {chi} which are needed for calculation of resonance cross section functions. The obtained values are given in tables.

Spatiotemporal optical pulse transformation by a resonant diffraction grating

Energy Technology Data Exchange (ETDEWEB)

Golovastikov, N. V.; Bykov, D. A., E-mail: bykovd@gmail.com; Doskolovich, L. L., E-mail: leonid@smr.ru; Soifer, V. A. [Russian Academy of Sciences, Image Processing Systems Institute (Russian Federation)

2015-11-15

The diffraction of a spatiotemporal optical pulse by a resonant diffraction grating is considered. The pulse diffraction is described in terms of the signal (the spatiotemporal incident pulse envelope) passage through a linear system. An analytic approximation in the form of a rational function of two variables corresponding to the angular and spatial frequencies has been obtained for the transfer function of the system. A hyperbolic partial differential equation describing the general form of the incident pulse envelope transformation upon diffraction by a resonant diffraction grating has been derived from the transfer function. A solution of this equation has been obtained for the case of normal incidence of a pulse with a central frequency lying near the guided-mode resonance of a diffraction structure. The presented results of numerical simulations of pulse diffraction by a resonant grating show profound changes in the pulse envelope shape that closely correspond to the proposed theoretical description. The results of the paper can be applied in creating new devices for optical pulse shape transformation, in optical information processing problems, and analog optical computations.

Clinico-Epidemiological Comparison of Delusion-Prominent and Hallucination-Prominent Clinical Subgroups of Paranoid Schizophrenia.

Science.gov (United States)

Kreinin, Anatoly; Krishtul, Vladimir; Kirsh, Zvi; Menuchin, Michael

2015-01-01

Though hallucinations and delusions are prominent basic impairments in schizophrenia, reports of the relationship between hallucinatory and delusional symptoms among schizophrenia patients are scant. To examine the epidemiological and clinical differences between mainly hallucinatory and mainly delusional subgroups of paranoid schizophrenia patients. One hundred schizophrenia patients, paranoid type, were recruited. In a cross-sectional study, participants were divided into Mainly Hallucinatory (H) and Mainly Delusional (D) subgroups. Demographic variables were compared and clinical characteristics were evaluated using the Scale for the Assessment of Positive Symptoms, the Scale for the Assessment of Negative Symptoms, and the Clinical Global Impression Scale. The Quality-of-Life Enjoyment and Satisfaction Questionnaire-18 was used to assess quality of life. Clinically, the H group was more heterogeneous as expressed by the broader range of scores that described the clinical picture of patients in that subgroup (in 43 of 78 variables, 55.13%) and similar ranges of scores (31 of 78 variables, 39.74%) for patients in the D group. Duration of hospitalization was significantly longer in group H than in group D (p=0.047). There was no statistically significant difference between the H and D subgroups in demographic characteristics. There are distinct epidemiological and clinical differences between the H and D subgroups, with more severe positive and negative symptoms and greater functional impairment in the H group. Paranoid schizophrenia patients with prominent hallucinations have poorer prognosis and need intensive therapeutic rehabilitation beginning with onset-of-illness. Further genetic studies and comparisons of fMRI and/or PET findings are warranted to investigate additional distinctive characteristics of these subgroups.

Optical characterization of Jerusalem cross-shaped nanoaperture antenna arrays

Science.gov (United States)

Turkmen, Mustafa; Aslan, Ekin; Aslan, Erdem

2014-03-01

Recent advances in nanofabrication and computational electromagnetic design techniques have enabled the realization of metallic nanostructures in different shapes and sizes with adjustable resonance frequencies. To date, many metamaterial designs in various geometries with the used of different materials have been presented for the applications of surface plasmons, cloaking, biosensing, and frequency selective surfaces1-5. Surface plasmons which are collective electron oscillations on metal surfaces ensure that plasmonic nanoantennas can be used in many applications like biosensing at infrared (IR) and visible regions. The nanostructure that we introduce has a unit cell that consists of Jerusalem crossshaped nanoaperture on a gold layer, which is standing on suspended SiNx, Si or glass membranes. The proposed nanoaperture antenna array has a regular and stable spectral response. In this study, we present sensitivity of the resonance characteristics of Jerusalem cross-shaped nanoaperture antenna arrays to the changes in substrate parameters and metal thickness. We demonstrate that resonance frequency values can be adjusted by changing the thicknesses and types of the dielectric substrate and the metallic layer. Numerical calculations on spectral response of the nanoantenna array are performed by using Finite Difference Time Domain (FDTD) method6. The results of the simulations specify that resonance frequencies, the reflectance and transmittance values at resonances, and the band gap vary by the change of substrate parameters and metal thicknesses. These variations is a sign of that the proposed nanoantenna can be employed for sensing applications.

A parity checker circuit based on microelectromechanical resonator logic elements

KAUST Repository

Hafiz, Md Abdullah Al

2017-01-11

Micro/nano-electromechanical resonator based logic computation has attracted significant attention in recent years due to its dynamic mode of operation, ultra-low power consumption, and potential for reprogrammable and reversible computing. Here we demonstrate a 4-bit parity checker circuit by utilizing recently developed logic gates based on MEMS resonators. Toward this, resonance frequencies of shallow arch shaped micro resonators are electrothermally tuned by the logic inputs to constitute the required logic gates for the proposed parity checker circuit. This study demonstrates that by utilizing MEMS resonator based logic elements, complex digital circuits can be realized.

A parity checker circuit based on microelectromechanical resonator logic elements

KAUST Repository

Hafiz, Md Abdullah Al; Li, Ren; Younis, Mohammad I.; Fariborzi, Hossein

2017-01-01

Micro/nano-electromechanical resonator based logic computation has attracted significant attention in recent years due to its dynamic mode of operation, ultra-low power consumption, and potential for reprogrammable and reversible computing. Here we demonstrate a 4-bit parity checker circuit by utilizing recently developed logic gates based on MEMS resonators. Toward this, resonance frequencies of shallow arch shaped micro resonators are electrothermally tuned by the logic inputs to constitute the required logic gates for the proposed parity checker circuit. This study demonstrates that by utilizing MEMS resonator based logic elements, complex digital circuits can be realized.

Coherent control through near-resonant Raman transitions

International Nuclear Information System (INIS)

Dai Xingcan; Lerch, Eliza-Beth W.; Leone, Stephen R.

2006-01-01

The phase of an electronic wave function is shown to play an important role in coherent control experiments. By using a pulse shaping system with a femtosecond laser, we explore the phase relationships among resonant and off-resonant Raman transitions in Li 2 by measuring the phases of the resulting wave packets, or quantum beats. Specific pixels in a liquid-crystal spatial light modulator are used to isolate the resonant and off-resonant portions of the Raman transitions in Li 2 . The off-resonant Raman transitions have an approximately 90 degree sign phase shift with respect to the resonant Raman transition, and there is an approximately 180 degree sign phase shift between the blue-detuned and the red-detuned off-resonant Raman transitions. Calculations using second-order time-dependent perturbation theory for the electronic transitions agree with the experimental results for the laser pulse intensities used here. Interferences between the off-resonant Raman transitions as a function of detuning are used to demonstrate coherent control of the Raman quantum wave packet

2 µm high-power dissipative soliton resonance in a compact σ-shaped Tm-doped double-clad fiber laser

Science.gov (United States)

Du, Tuanjie; Li, Weiwei; Ruan, Qiujun; Wang, Kaijie; Chen, Nan; Luo, Zhengqian

2018-05-01

We report direct generation of a high-power, large-energy dissipative soliton resonance (DSR) in a 2 µm Tm-doped double-clad fiber laser. A compact σ-shaped cavity is formed by a fiber Bragg grating and a 10/90 fiber loop mirror (FLM). The 10/90 FLM is not only used as an output mirror, but also acts as a nonlinear optical loop mirror for initiating mode locking. The mode-locked laser can deliver high-power, nanosecond DSR pulses at 2005.9 nm. We further perform a comparison study of the effect of the FLM’s loop length on the mode-locking threshold, peak power, pulse energy, and optical spectrum of the DSR pulses. We achieve a maximum average output power as high as 1.4 W, a maximum pulse energy of 353 nJ, and a maximum peak power of 84 W. This is, to the best of our knowledge, the highest power for 2 µm DSR pulses obtained in a mode-locked fiber laser.

Analytic Solution of the Electromagnetic Eigenvalues Problem in a Cylindrical Resonator

Energy Technology Data Exchange (ETDEWEB)

Checchin, Mattia [Fermilab; Martinello, Martina [Fermilab

2016-10-06

Resonant accelerating cavities are key components in modern particles accelerating facilities. These take advantage of electromagnetic fields resonating at microwave frequencies to accelerate charged particles. Particles gain finite energy at each passage through a cavity if in phase with the resonating field, reaching energies even of the order of $TeV$ when a cascade of accelerating resonators are present. In order to understand how a resonant accelerating cavity transfers energy to charged particles, it is important to determine how the electromagnetic modes are exited into such resonators. In this paper we present a complete analytical calculation of the resonating fields for a simple cylindrical-shaped cavity.

Fundamental study on laser manipulation of contamination particles with determining shape, size and species

International Nuclear Information System (INIS)

Shimizu, Isao; Fujii, Taketsugu

1995-01-01

It has been desired to eliminate or collect the contamination particles of radioisotope in each sort of species or shape and size non-invasively. The shape and size of particle can be determined from the shape and distribution of diffraction pattern of particle in the parallel laser beam, the species of particle can be discriminated by the fluorescence from resonance of laser beam, or by the laser Raman scattering, and the particle suspended in the air or falling down in a vacuum can be levitated against the gravity and trapped by the radiation force and the trapping force of the focussed laser beam in the atmosphere or in a vacuum. For the purpose of the non-invasive manipulation of contamination particles, the laser manipulation technique, image processing technique with Multiplexed Matched Spatial Filter and the determination technique of laser Raman scattering or fluorescence from resonance of laser light were combined in the experiments. The shape, size and species of particles trapped in the focal plane of focused Ar laser beam can be determined simultaneously and instantaneously from the shape and intensity distributions of diffraction patterns of the particles in the irradiation of parallel coherent beam of He-Ne laser, and fluorescence from the resonance of YAG laser beam with variable wave length. In this research, a new technique is proposed to manipulate non-invasively the contamination particles determined with the shape, size and species in the atmosphere or in a vacuum, by laser beam. (author)

Quiescent Prominence Dynamics Observed with the Hinode Solar Optical Telescope. I. Turbulent Upflow Plumes

Science.gov (United States)

Berger, Thomas E.; Slater, Gregory; Hurlburt, Neal; Shine, Richard; Tarbell, Theodore; Title, Alan; Lites, Bruce W.; Okamoto, Takenori J.; Ichimoto, Kiyoshi; Katsukawa, Yukio; Magara, Tetsuya; Suematsu, Yoshinori; Shimizu, Toshifumi

2010-06-01

Hinode/Solar Optical Telescope (SOT) observations reveal two new dynamic modes in quiescent solar prominences: large-scale (20-50 Mm) "arches" or "bubbles" that "inflate" from below into prominences, and smaller-scale (2-6 Mm) dark turbulent upflows. These novel dynamics are related in that they are always dark in visible-light spectral bands, they rise through the bright prominence emission with approximately constant speeds, and the small-scale upflows are sometimes observed to emanate from the top of the larger bubbles. Here we present detailed kinematic measurements of the small-scale turbulent upflows seen in several prominences in the SOT database. The dark upflows typically initiate vertically from 5 to 10 Mm wide dark cavities between the bottom of the prominence and the top of the chromospheric spicule layer. Small perturbations on the order of 1 Mm or less in size grow on the upper boundaries of cavities to generate plumes up to 4-6 Mm across at their largest widths. All plumes develop highly turbulent profiles, including occasional Kelvin-Helmholtz vortex "roll-up" of the leading edge. The flows typically rise 10-15 Mm before decelerating to equilibrium. We measure the flowfield characteristics with a manual tracing method and with the Nonlinear Affine Velocity Estimator (NAVE) "optical flow" code to derive velocity, acceleration, lifetime, and height data for several representative plumes. Maximum initial speeds are in the range of 20-30 km s-1, which is supersonic for a ~10,000 K plasma. The plumes decelerate in the final few Mm of their trajectories resulting in mean ascent speeds of 13-17 km s-1. Typical lifetimes range from 300 to 1000 s (~5-15 minutes). The area growth rate of the plumes (observed as two-dimensional objects in the plane of the sky) is initially linear and ranges from 20,000 to 30,000 km2 s-1 reaching maximum projected areas from 2 to 15 Mm2. Maximum contrast of the dark flows relative to the bright prominence plasma in SOT images

QUIESCENT PROMINENCE DYNAMICS OBSERVED WITH THE HINODE SOLAR OPTICAL TELESCOPE. I. TURBULENT UPFLOW PLUMES

International Nuclear Information System (INIS)

Berger, Thomas E.; Slater, Gregory; Hurlburt, Neal; Shine, Richard; Tarbell, Theodore; Title, Alan; Lites, Bruce W.; Okamoto, Takenori J.; Ichimoto, Kiyoshi; Katsukawa, Yukio; Magara, Tetsuya; Suematsu, Yoshinori; Shimizu, Toshifumi

2010-01-01

Hinode/Solar Optical Telescope (SOT) observations reveal two new dynamic modes in quiescent solar prominences: large-scale (20-50 Mm) 'arches' or 'bubbles' that 'inflate' from below into prominences, and smaller-scale (2-6 Mm) dark turbulent upflows. These novel dynamics are related in that they are always dark in visible-light spectral bands, they rise through the bright prominence emission with approximately constant speeds, and the small-scale upflows are sometimes observed to emanate from the top of the larger bubbles. Here we present detailed kinematic measurements of the small-scale turbulent upflows seen in several prominences in the SOT database. The dark upflows typically initiate vertically from 5 to 10 Mm wide dark cavities between the bottom of the prominence and the top of the chromospheric spicule layer. Small perturbations on the order of 1 Mm or less in size grow on the upper boundaries of cavities to generate plumes up to 4-6 Mm across at their largest widths. All plumes develop highly turbulent profiles, including occasional Kelvin-Helmholtz vortex 'roll-up' of the leading edge. The flows typically rise 10-15 Mm before decelerating to equilibrium. We measure the flowfield characteristics with a manual tracing method and with the Nonlinear Affine Velocity Estimator (NAVE) 'optical flow' code to derive velocity, acceleration, lifetime, and height data for several representative plumes. Maximum initial speeds are in the range of 20-30 km s -1 , which is supersonic for a ∼10,000 K plasma. The plumes decelerate in the final few Mm of their trajectories resulting in mean ascent speeds of 13-17 km s -1 . Typical lifetimes range from 300 to 1000 s (∼5-15 minutes). The area growth rate of the plumes (observed as two-dimensional objects in the plane of the sky) is initially linear and ranges from 20,000 to 30,000 km 2 s -1 reaching maximum projected areas from 2 to 15 Mm 2 . Maximum contrast of the dark flows relative to the bright prominence plasma in

Experimental study of the influence of different resonators on thermoacoustic conversion performance of a thermoacoustic-Stirling heat engine.

Science.gov (United States)

Luo, E C; Ling, H; Dai, W; Yu, G Y

2006-12-22

In this paper, an experimental study of the effect of the resonator shape on the performance of a traveling-wave thermoacoustic engine is presented. Two different resonators were tested in the thermoacoustic-Stirling heat. One resonator is an iso-diameter one, and the other is a tapered one. To have a reasonable comparison reference, we keep the same traveling-wave loop, the same resonant frequency and the same operating pressure. The experiment showed that the resonator shape has significant influence on the global performance of the thermoacoustic-Stirling heat engine. The tapered resonator gives much better performance than the iso-diameter resonator. The tapered resonator system achieved a maximum pressure ratio of about 1.3, a maximum net acoustical power output of about 450 W and a highest thermoacoustic efficiency of about 25%.

Resonances for Obstacles in Hyperbolic Space

Science.gov (United States)

Hintz, Peter; Zworski, Maciej

2017-12-01

We consider scattering by star-shaped obstacles in hyperbolic space and show that resonances satisfy a universal bound { Im λ ≤ - 1/2 } , which is optimal in dimension 2. In odd dimensions we also show that { Im λ ≤ - μ/ρ } for a universal constant {μ} , where { ρ } is the radius of a ball containing the obstacle; this gives an improvement for small obstacles. In dimensions 3 and higher the proofs follow the classical vector field approach of Morawetz, while in dimension 2 we obtain our bound by working with spaces coming from general relativity. We also show that in odd dimensions resonances of small obstacles are close, in a suitable sense, to Euclidean resonances.

A 2:1 MUX Based on Multiple MEMS Resonators

KAUST Repository

Hafiz, Md Abdullah Al

2017-01-09

Micro/nano-electromechanical resonator based mechanical computing has recently attracted significant attention. This paper reports a realization of a 2:1 MUX, a concatenable digital logic element, based on electrothermal frequency tuning of electrically connected multiple arch resonators. Toward this, shallow arch shaped microresonators are electrically connected and their resonance frequencies are tuned based on an electrothermal frequency modulation scheme. This study demonstrates that by reconfiguring the same basic building block, the arch microresonator, complex logic circuits can be realized.

A 2:1 MUX Based on Multiple MEMS Resonators

KAUST Repository

Hafiz, Md Abdullah Al; Kosuru, Lakshmoji; Younis, Mohammad I.; Fariborzi, Hossein

2017-01-01

Micro/nano-electromechanical resonator based mechanical computing has recently attracted significant attention. This paper reports a realization of a 2:1 MUX, a concatenable digital logic element, based on electrothermal frequency tuning of electrically connected multiple arch resonators. Toward this, shallow arch shaped microresonators are electrically connected and their resonance frequencies are tuned based on an electrothermal frequency modulation scheme. This study demonstrates that by reconfiguring the same basic building block, the arch microresonator, complex logic circuits can be realized.

Prominence Bubble Shear Flows and the Coupled Kelvin-Helmholtz — Rayleigh-Taylor Instability

Science.gov (United States)

Berger, Thomas; Hillier, Andrew

2017-08-01

Prominence bubbles are large arched structures that rise from below into quiescent prominences, often growing to heights on the order of 10 Mm before going unstable and generating plume upflows. While there is general agreement that emerging flux below pre-existing prominences causes the structures, there is lack of agreement on the nature of the bubbles and the cause of the instability flows. One hypothesis is that the bubbles contain coronal temperature plasma and rise into the prominence above due to both magnetic and thermal buoyancy, eventually breaking down via a magnetic Rayleigh-Taylor (RT) instability to release hot plasma and magnetic flux and helicity into the overlying coronal flux rope. Another posits that the bubbles are actually just “arcades” in the prominence indicating a magnetic separator line between the bipole and the prominence fields with the observed upflows and downflows caused by reconnection along the separator. We analyze Hinode/SOT, SDO/AIA, and IRIS observations of prominence bubbles, focusing on characteristics of the bubble boundary layers that may discriminate between the two hypotheses. We find speeds on the order of 10 km/s in prominence plasma downflows and lateral shear flows along the bubble boundary. Inflows to the boundary gradually increase the thickness and brightness of the layer until plasma drains from there, apparently around the dome-like bubble domain. In one case, shear flow across the bubble boundary develops Kelvin-Helmholtz (KH) vortices that we use to infer flow speeds in the low-density bubble on the order of 100 km/sec. IRIS spectra indicate that plasma flows on the bubble boundary at transition region temperatures achieve Doppler speeds on the order of 50 km/s, consistent with this inference. Combined magnetic KH-RT instability analysis leads to flux density estimates of 10 G with a field angle of 30° to the prominence, consistent with vector magnetic field measurements. In contrast, we find no evidence

Shape resonances and EXAFS scattering in the $Pt L_{2,3}$ XANES from a Pt electrode

CERN Document Server

O'Grady, W E

1999-01-01

Atomic hydrogen and oxygen adsorption on a platinum electrode in H /sub 2/SO/sub 4/ and HClO/sub 4/ electrolytes were studied by Pt L /sub 23/ XANES. The Pt electrode was formed of highly dispersed 1.5-3.0 nm particles supported on $9 carbon. A difference procedure utilizing the L/sub 2/ and L/sub 3/ spectra at various applied voltages was used to isolate the electronic and geometric effects in the XANES spectra. At 0.54 V (relative to RHE) the Pt electrode in $9 HClO/sub 4/ is assumed to be "clean". By taking the difference between the spectra at 0.0 and 0.54 V, the Pt-H antibonding state (electronic effect) is isolated and found to have a Fano-resonance line shape. In addition, a $9 significant Pt-H EXAFS scattering (geometric effect) was found for photon energies 0 to 20 eV above the edge. The difference between the spectra at 1.14 and 0.54 V allows isolation of the Pt-O antibonding state and the Pt-O EXAFS $9 scattering. (7 refs).

Detecting hippocampal shape changes in Alzheimer's disease using statistical shape models

Science.gov (United States)

Shen, Kaikai; Bourgeat, Pierrick; Fripp, Jurgen; Meriaudeau, Fabrice; Salvado, Olivier

2011-03-01

The hippocampus is affected at an early stage in the development of Alzheimer's disease (AD). Using brain Magnetic Resonance (MR) images, we can investigate the effect of AD on the morphology of the hippocampus. Statistical shape models (SSM) are usually used to describe and model the hippocampal shape variations among the population. We use the shape variation from SSM as features to classify AD from normal control cases (NC). Conventional SSM uses principal component analysis (PCA) to compute the modes of variations among the population. Although these modes are representative of variations within the training data, they are not necessarily discriminant on labelled data. In this study, a Hotelling's T 2 test is used to qualify the landmarks which can be used for PCA. The resulting variation modes are used as predictors of AD from NC. The discrimination ability of these predictors is evaluated in terms of their classification performances using support vector machines (SVM). Using only landmarks statistically discriminant between AD and NC in SSM showed a better separation between AD and NC. These predictors also showed better correlation to the cognitive scores such as mini-mental state examination (MMSE) and Alzheimer's disease assessment scale (ADAS).

Eruptive prominences and long-delay geomagnetic storms

International Nuclear Information System (INIS)

Wright, C.S.

1983-01-01

The relationship between disappearing solar fragments and geomagnetic disturbances was investigated. It is shown that long-delay storms are associated with filaments well removed from the disc centre, and particularly in the case of large filaments and prominences, the proportion of events that produce long-delay storms increases with angular distance from the centre

Giant resonances: reaction theory approach

International Nuclear Information System (INIS)

Toledo Piza, A.F.R. de; Foglia, G.A.

1989-09-01

The study of giant resonances through the use of reaction theory approach is presented and discussed. Measurements of cross-sections to the many available decay channels following excitation of giant multipole resonances (GMR) led one to view these phenomena as complicated dynamical syndromes so that theoretical requirements for their study must be extended beyond the traditional bounds of nuclear structure models. The spectra of decay products following GMR excitation in heavy nuclei are well described by statistical model (Hauser-Feshback, HF) predictions indicated that spreading of the collective modes plays a major role in shaping exclusive cross-sections. (A.C.A.S.) [pt

Compact Dual-Band Zeroth-Order Resonance Antenna

International Nuclear Information System (INIS)

Xu He-Xiu; Wang Guang-Ming; Gong Jian-Qiang

2012-01-01

A novel microstrip zeroth-order resonator (ZOR) antenna and its equivalent circuit model are exploited with two zeroth-order resonances. It is constructed based on a resonant-type composite right/left handed transmission line (CRLH TL) using a Wunderlich-shaped extended complementary single split ring resonator pair (W-ECSSRRP) and a series capacitive gap. The gap either can be utilized for double negative (DNG) ZOR antenna or be removed to engineer a simplified elision-negative ZOR (ENG) antenna. For verification, a DNG ZOR antenna sample is fabricated and measured. Numerical and experimental results agree well with each other, indicating that the omnidirectional radiations occur at two frequency bands which are accounted for by two shunt branches in the circuit model. The size of the antenna is 49% more compact than its previous counterpart. The superiority of W-ECSSRRP over CSSRRP lies in the lower fundamental resonance of the antenna by 38.2% and the introduction of a higher zeroth-order resonance. (fundamental areas of phenomenology(including applications))

Electrothermally actuated tunable clamped-guided resonant microbeams

Science.gov (United States)

Alcheikh, N.; Hajjaj, A. Z.; Jaber, N.; Younis, M. I.

2018-01-01

We present simulation and experimental investigation demonstrating active alteration of the resonant and frequency response behavior of resonators by controlling the electrothermal actuation method on their anchors. In-plane clamped-guided arch and straight microbeams resonators are designed and fabricated with V-shaped electrothermal actuators on their anchors. These anchors not only offer various electrothermal actuation options, but also serve as various mechanical stiffness elements that affect the operating resonance frequency of the structures. We have shown that for an arch, the first mode resonance frequency can be increased up to 50% of its initial value. For a straight beam, we have shown that before buckling, the resonance frequency decreases to very low values and after buckling, it increases up to twice of its initial value. These results can be promising for the realization of different wide-range tunable microresonator. The experimental results have been compared to multi-physics finite-element simulations showing good agreement among them.

Electrothermally actuated tunable clamped-guided resonant microbeams

KAUST Repository

Alcheikh, Nouha

2017-06-11

We present simulation and experimental investigation demonstrating active alteration of the resonant and frequency response behavior of resonators by controlling the electrothermal actuation method on their anchors. In-plane clamped-guided arch and straight microbeams resonators are designed and fabricated with V-shaped electrothermal actuators on their anchors. These anchors not only offer various electrothermal actuation options, but also serve as various mechanical stiffness elements that affect the operating resonance frequency of the structures. We have shown that for an arch, the first mode resonance frequency can be increased up to 50% of its initial value. For a straight beam, we have shown that before buckling, the resonance frequency decreases to very low values and after buckling, it increases up to twice of its initial value. These results can be promising for the realization of different wide–range tunable microresonator. The experimental results have been compared to multi-physics finite-element simulations showing good agreement among them.

Observation of the Kelvin–Helmholtz Instability in a Solar Prominence

Science.gov (United States)

Yang, Heesu; Xu, Zhi; Lim, Eun-Kyung; Kim, Sujin; Cho, Kyung-Suk; Kim, Yeon-Han; Chae, Jongchul; Cho, Kyuhyoun; Ji, Kaifan

2018-04-01

Many solar prominences end their lives in eruptions or abrupt disappearances that are associated with dynamical or thermal instabilities. Such instabilities are important because they may be responsible for energy transport and conversion. We present a clear observation of a streaming kink-mode Kelvin–Helmholtz Instability (KHI) taking place in a solar prominence using the Hα Lyot filter installed at the New Vacuum Solar Telescope, Fuxian-lake Solar Observatory in Yunnan, China. On one side of the prominence, a series of plasma blobs floated up from the chromosphere and streamed parallel to the limb. The plasma stream was accelerated to about 20–60 km s‑1 and then undulated. We found that 2″- and 5″-size vortices formed, floated along the stream, and then broke up. After the 5″-size vortex, a plasma ejection out of the stream was detected in the Solar Dynamics Observatory/Atmospheric Imaging Assembly images. Just before the formation of the 5″-size vortex, the stream displayed an oscillatory transverse motion with a period of 255 s with the amplitude growing at the rate of 0.001 s‑1. We attribute this oscillation of the stream and the subsequent formation of the vortex to the KHI triggered by velocity shear between the stream, guided by the magnetic field and the surrounding media. The plasma ejection suggests the transport of prominence material into the upper layer by the KHI in its nonlinear stage.

Static electromagnetic properties of giant resonances

International Nuclear Information System (INIS)

Koo, W.K.

1986-03-01

Static electric monopole and quadrupole matrix elements, which are related to the mean square radius and quadrupole moment respectively, are derived for giant resonances of arbitrary multipolarity. The results furnish information on the size and shape of the nucleus in the excited giant states. (author)

Lines of MgI Detected in Solar Prominences

Czech Academy of Sciences Publication Activity Database

Heinzel, Petr; Kupryakov, Yu. A.; Schwartz, P.

2016-01-01

Roč. 40, č. 1 (2016), s. 87-91 ISSN 1845-8319. [Hvar Astrophysical Colloquium /14./. Hvar, 26.09.2016-30.09.2016] Institutional support: RVO:67985815 Keywords : prominences * limb-flare * MgI emession Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

New results form HST on fast, colimated outflows in dying stars - the primary mechanism for shaping planetary nebulae

Science.gov (United States)

Sahai, R.; Contreras, C.

2003-01-01

In this paper, we briefly describe the results from imaging surveys of young PNe and PPNe with HST, and then present new results from detailed kinematic studies of several prominent objects which support our hypothesis for shaping PNe.

Prominence and tornado dynamics observed with IRIS and THEMIS

Science.gov (United States)

Schmieder, Brigitte; Levens, Peter; Labrosse, Nicolas; Mein, Pierre; Lopez Ariste, Arturo; Zapior, Maciek

2017-08-01

Several prominences were observed during campaigns in September 2013 and July 2014 with the IRIS spectrometer and the vector magnetograph THEMIS (Tenerife). SDO/AIA and IRIS provided images and spectra of prominences and tornadoes corresponding to different physical conditions of the transition region between the cool plasma and the corona. The vector magnetic field was derived from THEMIS observations by using the He D3 depolarisation due to the magnetic field. The inversion code (PCA) takes into account the Hanle and Zeeman effects and allows us to compute the strength and the inclination of the magnetic field which is shown to be mostly horizontal in prominences as well as in tornadoes. Movies from SDO/AIA in 304 A and Hinode/SOT in Ca II show the highly dynamic nature of the fine structures. From spectra in Mg II and Si IV lines provided by IRIS and H-alpha observed by the Multi-channel Subtractive Double Pass (MSDP) spectrograph in the Meudon Solar Tower we derived the Doppler shifts of the fine structures and reconstructed the 3D structure of tornadoes. We conclude that the apparent rotation of AIA tornadoes is due to large-scale quasi-periodic oscillations of the plasma along more or less horizontal magnetic structures.

Symmetric metamaterials based on flower-shaped structure

International Nuclear Information System (INIS)

Tuong, P.V.; Park, J.W.; Rhee, J.Y.; Kim, K.W.; Cheong, H.; Jang, W.H.; Lee, Y.P.

2013-01-01

We proposed new models of metamaterials (MMs) based on a flower-shaped structure (FSS), whose “meta-atoms” consist of two flower-shaped metallic parts separated by a dielectric layer. Like the non-symmetric MMs based on cut-wire-pairs or electric ring resonators, the symmetrical FSS demonstrates the negative permeability at GHz frequencies. Employing the results, we designed a symmetric negative-refractive-index MM [a symmetric combined structure (SCS)], which is composed of FSSs and cross continuous wires. The MM properties of the FSS and the SCS are presented numerically and experimentally. - Highlights: • A new designed of sub-wavelength metamaterial, flower-shaped structure was proposed. • Flower-shaped meta-atom illustrated effective negative permeability. • Based on the meta-atom, negative refractive index was conventionally gained. • Negative refractive index was demonstrated with symmetric properties for electromagnetic wave. • Dimensional parameters were studied under normal electromagnetic wave

PROPAGATING WAVES TRANSVERSE TO THE MAGNETIC FIELD IN A SOLAR PROMINENCE

Energy Technology Data Exchange (ETDEWEB)

Schmieder, B. [Observatoire de Paris, LESIA, UMR 8109 (CNRS), F-92195 Meudon (France); Kucera, T. A.; Knizhnik, K. [Code 671, NASA' s GSFC, Greenbelt, MD 20771 (United States); Luna, M. [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Lopez-Ariste, A. [THEMIS, CNRS-UPS853, E-38205 La Laguna (Spain); Toot, D. [Alfred University, Alfred, NY 14802 (United States)

2013-11-10

We report an unusual set of observations of waves in a large prominence pillar that consist of pulses propagating perpendicular to the prominence magnetic field. We observe a huge quiescent prominence with the Solar Dynamics Observatory Atmospheric Imaging Assembly in EUV on 2012 October 10 and only a part of it, the pillar, which is a foot or barb of the prominence, with the Hinode Solar Optical Telescope (SOT; in Ca II and Hα lines), Sac Peak (in Hα, Hβ, and Na-D lines), and THEMIS ({sup T}élescope Héliographique pour l' Etude du Magnétisme et des Instabilités Solaires{sup )} with the MTR (MulTi-Raies) spectropolarimeter (in He D{sub 3} line). The THEMIS/MTR data indicates that the magnetic field in the pillar is essentially horizontal and the observations in the optical domain show a large number of horizontally aligned features on a much smaller scale than the pillar as a whole. The data are consistent with a model of cool prominence plasma trapped in the dips of horizontal field lines. The SOT and Sac Peak data over the four hour observing period show vertical oscillations appearing as wave pulses. These pulses, which include a Doppler signature, move vertically, perpendicular to the field direction, along thin quasi-vertical columns in the much broader pillar. The pulses have a velocity of propagation of about 10 km s{sup –1}, a period of about 300 s, and a wavelength around 2000 km. We interpret these waves in terms of fast magnetosonic waves and discuss possible wave drivers.

A twisted flux-tube model for solar prominences. I. General properties

International Nuclear Information System (INIS)

Priest, E.R.; Hood, A.W.; Anzer, U.

1989-01-01

It is proposed that a solar prominence consists of cool plasma supported in a large-scale curved and twisted magnetic flux tube. As long as the flux tube is untwisted, its curvature is concave toward the solar surface, and so it cannot support dense plasma against gravity. However, when it is twisted sufficiently, individual field lines may acquire a convex curvature near their summits and so provide support. Cool plasma then naturally tends to accumulate in such field line dips either by injection from below or by thermal condensation. As the tube is twisted up further or reconnection takes place below the prominence, one finds a transition from normal to inverse polarity. When the flux tube becomes too long or is twisted too much, it loses stability and its true magnetic geometry as an erupting prominence is revealed more clearly. 56 refs

Spectral shape of one-photon luminescence from single gold nanorods

Directory of Open Access Journals (Sweden)

Te Wen

2017-12-01

Full Text Available Light emission from gold nanoparticles was investigated with ultra-narrow-band notch filters to obtain the complete spectral shape. The anti-Stokes emission band was observed at all excitation wavelengths. The spectral shape of the anti-Stokes emission could be well fitted by a Fermi–Dirac-like line shape, while the spectral profile of the Stokes emission could be fitted by a Lorentzian line shape. The electron distribution and local surface plasmon resonance jointly determined the spectral shape. Additionally, we found that the anti-Stokes emission intensity increased more rapidly compared with that of the Stokes emission as illumination power was increased. This phenomenon can be understood from the temperature dependence of the electron distribution owing to photothermal effects.

Model for resonant plasma probe.

Energy Technology Data Exchange (ETDEWEB)

Warne, Larry Kevin; Johnson, William Arthur; Hebner, Gregory Albert; Jorgenson, Roy E.; Coats, Rebecca Sue

2007-04-01

This report constructs simple circuit models for a hairpin shaped resonant plasma probe. Effects of the plasma sheath region surrounding the wires making up the probe are determined. Electromagnetic simulations of the probe are compared to the circuit model results. The perturbing effects of the disc cavity in which the probe operates are also found.

DYNAMICS OF A PROMINENCE-HORN STRUCTURE DURING ITS EVAPORATION IN THE SOLAR CORONA

Energy Technology Data Exchange (ETDEWEB)

Wang, Bing; Chen, Yao; Fu, Jie; Li, Bo [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, and Institute of Space Sciences, Shandong University, Weihai 264209 (China); Li, Xing [Department of Physics, Aberystwyth University, Aberystwyth, Ceredigion, SY23 3BZ (United Kingdom); Liu, Wei, E-mail: yaochen@sdu.edu.cn [Stanford-Lockheed Institute for Space Research, Stanford University, Stanford, CA 94305 (United States)

2016-08-20

The physical connections among and formation mechanisms of various components of the prominence-horn cavity system remain elusive. Here we present observations of such a system, focusing on a section of the prominence that rises and separates gradually from the main body. This forms a configuration sufficiently simple to yield clues regarding the above issues. It is characterized by embedding horns, oscillations, and a gradual disappearance of the separated material. The prominence-horn structure exhibits a large-amplitude longitudinal oscillation with a period of ∼150 minutes and an amplitude of ∼30 Mm along the trajectory defined by the concave horn structure. The horns also experience a simultaneous transverse oscillation with a much smaller amplitude (∼3 Mm) and a shorter period (∼10–15 minutes), likely representative of a global mode of the large-scale magnetic structure. The gradual disappearance of the structure indicates that the horn, an observational manifestation of the field-aligned transition region separating the cool and dense prominence from the hot and tenuous corona, is formed due to the heating and diluting process of the central prominence mass; most previous studies suggested that it is the opposite process, i.e., the cooling and condensation of coronal plasmas, that formed the horn. This study also demonstrates how the prominence transports magnetic flux to the upper corona, a process essential for the gradual build-up of pre-eruption magnetic energy.

ARE GIANT TORNADOES THE LEGS OF SOLAR PROMINENCES?

Energy Technology Data Exchange (ETDEWEB)

Wedemeyer, Sven; Scullion, Eamon; Rouppe van der Voort, Luc; Bosnjak, Antonija [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Antolin, Patrick, E-mail: sven.wedemeyer@astro.uio.no [Centre for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, bus 2400, B-3001 Leuven (Belgium)

2013-09-10

Observations in the 171 A channel of the Atmospheric Imaging Assembly of the space-borne Solar Dynamics Observatory show tornado-like features in the atmosphere of the Sun. These giant tornadoes appear as dark, elongated, and apparently rotating structures in front of a brighter background. This phenomenon is thought to be produced by rotating magnetic field structures that extend throughout the atmosphere. We characterize giant tornadoes through a statistical analysis of properties such as spatial distribution, lifetimes, and sizes. A total number of 201 giant tornadoes are detected in a period of 25 days, suggesting that, on average, about 30 events are present across the whole Sun at a time close to solar maximum. Most tornadoes appear in groups and seem to form the legs of prominences, thus serving as plasma sources/sinks. Additional H{alpha} observations with the Swedish 1 m Solar Telescope imply that giant tornadoes rotate as a structure, although they clearly exhibit a thread-like structure. We observe tornado groups that grow prior to the eruption of the connected prominence. The rotation of the tornadoes may progressively twist the magnetic structure of the prominence until it becomes unstable and erupts. Finally, we investigate the potential relation of giant tornadoes to other phenomena, which may also be produced by rotating magnetic field structures. A comparison to cyclones, magnetic tornadoes, and spicules implies that such events are more abundant and short-lived the smaller they are. This comparison might help to construct a power law for the effective atmospheric heating contribution as a function of spatial scale.

ARE GIANT TORNADOES THE LEGS OF SOLAR PROMINENCES?

International Nuclear Information System (INIS)

Wedemeyer, Sven; Scullion, Eamon; Rouppe van der Voort, Luc; Bosnjak, Antonija; Antolin, Patrick

2013-01-01

Observations in the 171 Å channel of the Atmospheric Imaging Assembly of the space-borne Solar Dynamics Observatory show tornado-like features in the atmosphere of the Sun. These giant tornadoes appear as dark, elongated, and apparently rotating structures in front of a brighter background. This phenomenon is thought to be produced by rotating magnetic field structures that extend throughout the atmosphere. We characterize giant tornadoes through a statistical analysis of properties such as spatial distribution, lifetimes, and sizes. A total number of 201 giant tornadoes are detected in a period of 25 days, suggesting that, on average, about 30 events are present across the whole Sun at a time close to solar maximum. Most tornadoes appear in groups and seem to form the legs of prominences, thus serving as plasma sources/sinks. Additional Hα observations with the Swedish 1 m Solar Telescope imply that giant tornadoes rotate as a structure, although they clearly exhibit a thread-like structure. We observe tornado groups that grow prior to the eruption of the connected prominence. The rotation of the tornadoes may progressively twist the magnetic structure of the prominence until it becomes unstable and erupts. Finally, we investigate the potential relation of giant tornadoes to other phenomena, which may also be produced by rotating magnetic field structures. A comparison to cyclones, magnetic tornadoes, and spicules implies that such events are more abundant and short-lived the smaller they are. This comparison might help to construct a power law for the effective atmospheric heating contribution as a function of spatial scale

Molecular resonances, fusion reactions and surface transparency of interaction between heavy ions

International Nuclear Information System (INIS)

Abe, Yasuhisa.

1980-01-01

A review of the Band Crossing Model is given, including recent results on the 16 O + 16 O system. Surface Transparency is discussed in the light of the recent development in our understanding of the fusion reaction mechanisms and by calculating the number of open channels available to direct reactions. The existence of the Molecular Resonance Region is suggested in several systems by the fact that Band Crossing Region overlaps with the Transparent Region. A systematic study predicts molecular resonances in the 14 C + 14 C and 12 C + 14 C systems as prominent as those observed in the 16 O + 16 O and 12 C + 16 O systems

Processing of complex shapes with single-mode resonant frequency microwave applicators

International Nuclear Information System (INIS)

Fellows, L.A.; Delgado, R.; Hawley, M.C.

1994-01-01

Microwave processing is an alternative to conventional composite processing techniques. Single-mode microwave applicators efficiently couple microwave energy into the composite. The application of the microwave energy is greatly affected by the geometry of the composite. In the single mode microwave applicator, two types of modes are available. These modes are best suited to processing flat planar samples or cylindrical samples with geometries that align with the electric fields. Mode-switching is alternating between different electromagnetic modes with the intelligent selection of the modes to alleviate undesirable temperature profiles. This method has improved the microwave heating profiles of materials with complex shapes that do not align with either type of electric field. Parts with two different complex geometries were fabricated from a vinyl toluene/vinyl ester resin with a continuous glass fiber reinforcement by autoclaving and by microwave techniques. The flexural properties of the microwave processed samples were compared to the flexural properties of autoclaved samples. The trends of the mechanical properties for the complex shapes were consistent with the results of experiments with flat panels. This demonstrated that mode-switching techniques are as applicable for the complex shapes as they are for the simpler flat panel geometry

A Map for a Group of Resonant Cases in a Quartic Galactic ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

used in order to find the x − px Poincare phase plane for each resonance. ... tori give birth to families of regular orbits with similar shape to that of the parent resonant ..... of and the stability characteristics are the same for the two phase planes.

Multi-Wavelength Eclipse Observations of a Quiescent Prominence

Czech Academy of Sciences Publication Activity Database

Jejčič, S.; Heinzel, Petr; Zapiór, M.; Druckmüller, M.; Gunár, Stanislav; Kotrč, Pavel

2014-01-01

Roč. 289, č. 7 (2014), s. 2487-2501 ISSN 0038-0938 R&D Projects: GA ČR GAP209/12/0906 Institutional support: RVO:67985815 Keywords : eclipse observations * prominences * quiescent Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.039, year: 2014

Shape determinative slice localization for patient-specific masseter modeling using shape-based interpolation

Energy Technology Data Exchange (ETDEWEB)

Ng, H.P. [NUS Graduate School for Integrative Sciences and Engineering (Singapore); Biomedical Imaging Lab., Agency for Science Technology and Research (Singapore); Foong, K.W.C. [NUS Graduate School for Integrative Sciences and Engineering (Singapore); Dept. of Preventive Dentistry, National Univ. of Singapore (Singapore); Ong, S.H. [Dept. of Electrical and Computer Engineering, National Univ. of Singapore (Singapore); Div. of Bioengineering, National Univ. of Singapore (Singapore); Liu, J.; Nowinski, W.L. [Biomedical Imaging Lab., Agency for Science Technology and Research (Singapore); Goh, P.S. [Dept. of Diagnostic Radiology, National Univ. of Singapore (Singapore)

2007-06-15

The masseter plays a critical role in the mastication system. A hybrid method to shape-based interpolation is used to build the masseter model from magnetic resonance (MR) data sets. The main contribution here is the localizing of determinative slices in the data sets where clinicians are required to perform manual segmentations in order for an accurate model to be built. Shape-based criteria were used to locate the candidates for determinative slices and fuzzy-c-means (FCM) clustering technique was used to establish the determinative slices. Five masseter models were built in our work and the average overlap indices ({kappa}) achieved is 85.2%. This indicates that there is good agreement between the models and the manual contour tracings. In addition, the time taken, as compared to manually segmenting all the slices, is significantly lesser. (orig.)

Shape determinative slice localization for patient-specific masseter modeling using shape-based interpolation

International Nuclear Information System (INIS)

Ng, H.P.; Foong, K.W.C.; Ong, S.H.; Liu, J.; Nowinski, W.L.; Goh, P.S.

2007-01-01

The masseter plays a critical role in the mastication system. A hybrid method to shape-based interpolation is used to build the masseter model from magnetic resonance (MR) data sets. The main contribution here is the localizing of determinative slices in the data sets where clinicians are required to perform manual segmentations in order for an accurate model to be built. Shape-based criteria were used to locate the candidates for determinative slices and fuzzy-c-means (FCM) clustering technique was used to establish the determinative slices. Five masseter models were built in our work and the average overlap indices (κ) achieved is 85.2%. This indicates that there is good agreement between the models and the manual contour tracings. In addition, the time taken, as compared to manually segmenting all the slices, is significantly lesser. (orig.)

HELICAL MOTIONS OF FINE-STRUCTURE PROMINENCE THREADS OBSERVED BY HINODE AND IRIS

Energy Technology Data Exchange (ETDEWEB)

Okamoto, Takenori J. [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Liu, Wei [Bay Area Environmental Research Institute, 625 2nd Street, Suite 209, Petaluma, CA 94952 (United States); Tsuneta, Saku, E-mail: joten.okamoto@nao.ac.jp [ISAS/JAXA, Sagamihara, Kanagawa 252-5210 (Japan)

2016-11-10

Fine-structure dynamics in solar prominences holds critical clues to understanding their physical nature of significant space-weather implications. We report evidence of rotational motions of horizontal helical threads in two active-region prominences observed by the Hinode and/or Interface Region Imaging Spectrograph satellites at high resolution. In the first event, we found transverse motions of brightening threads at speeds up to 55 km s{sup -1} seen in the plane of the sky. Such motions appeared as sinusoidal space–time trajectories with a typical period of ∼390 s, which is consistent with plane-of-sky projections of rotational motions. Phase delays at different locations suggest the propagation of twists along the threads at phase speeds of 90–270 km s{sup -1}. At least 15 episodes of such motions occurred in two days, none associated with an eruption. For these episodes, the plane-of-sky speed is linearly correlated with the vertical travel distance, suggestive of a constant angular speed. In the second event, we found Doppler velocities of 30–40 km s{sup -1} in opposite directions in the top and bottom portions of the prominence, comparable to the plane-of-sky speed. The moving threads have about twice broader line widths than stationary threads. These observations, when taken together, provide strong evidence for rotations of helical prominence threads, which were likely driven by unwinding twists triggered by magnetic reconnection between twisted prominence magnetic fields and ambient coronal fields.

Liking goes with liking: An intuitive congruence between preference and prominence.

Science.gov (United States)

Morvinski, Coby; Amir, On

2018-03-26

In a series of 8 experiments, we demonstrate the existence of a "labeling effect" wherein people intuitively relate preferred choices to prominently labeled cues (such as heads as opposed to tails in a coin toss) and vice versa. Importantly, the observed congruence is asymmetric-it does not manifest for nonprominent cues and nonpreferred choices. This is because the congruence is driven by a process of evaluative matching: prominent cues are liked, but nonprominent cues are neutral or at most slightly negative in contrast. When we test prominent, yet truly negatively labeled cues, we indeed find a matching with less liked products. We discuss the theoretical contributions to the study of preferences and decision making, as well as demonstrate the practical implications to researchers and practitioners by using this process to assess intuitive preferences and reduce the compromise effect. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Topics and topic prominence in two sign languages

NARCIS (Netherlands)

Kimmelman, V.

2015-01-01

In this paper we describe topic marking in Russian Sign Language (RSL) and Sign Language of the Netherlands (NGT) and discuss whether these languages should be considered topic prominent. The formal markers of topics in RSL are sentence-initial position, a prosodic break following the topic, and

Shapes and dynamics from the time-dependent mean field

International Nuclear Information System (INIS)

Stevenson, P.D.; Goddard, P.M.; Rios, A.

2015-01-01

Explaining observed properties in terms of underlying shape degrees of freedom is a well-established prism with which to understand atomic nuclei. Self-consistent mean-field models provide one tool to understand nuclear shapes, and their link to other nuclear properties and observables. We present examples of how the time-dependent extension of the mean-field approach can be used in particular to shed light on nuclear shape properties, particularly looking at the giant resonances built on deformed nuclear ground states, and at dynamics in highly-deformed fission isomers. Example calculations are shown of 28 Si in the first case, and 240 Pu in the latter case

CUSP-SHAPED STRUCTURE OF A JET OBSERVED BY IRIS AND SDO

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yuzong; Zhang, Jun, E-mail: yuzong@nao.cas.cn, E-mail: zjun@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2017-01-01

On 2014 August 29, the trigger and evolution of a cusp-shaped jet were captured in detail at 1330 Å by the Interface Region Imaging Spectrograph . At first, two neighboring mini-prominences arose in turn from the low solar atmosphere and collided with a loop-like system over them. The collisions between the loop-like system and the mini-prominences lead to the blowout, and then a cusp-shaped jet formed with a spire and an arch-base. In the spire, many brightening blobs originating from the junction between the spire and the arch-base moved upward in a rotating manner and then in a straight line in the late phase of the jet. In the arch-base, dark and bright material simultaneously tracked in a fan-like structure, and the majority of the material moved along the fan's threads. At the later phase of the jet's evolution, bidirectional flows emptied the arch-base, while downflows emptied the spire, thus making the jet entirely vanish. The extremely detailed observations in this study shed new light on how magnetic reconnection alters the inner topological structure of a jet and provides a beneficial complement for understanding current jet models.

Differential Roles of the Fan-Shaped Body and the Ellipsoid Body in "Drosophila" Visual Pattern Memory

Science.gov (United States)

Pan, Yufeng; Zhou, Yanqiong; Guo, Chao; Gong, Haiyun; Gong, Zhefeng; Liu, Li

2009-01-01

The central complex is a prominent structure in the "Drosophila" brain. Visual learning experiments in the flight simulator, with flies with genetically altered brains, revealed that two groups of horizontal neurons in one of its substructures, the fan-shaped body, were required for "Drosophila" visual pattern memory. However,…

Embroidered Coils for Magnetic Resonance Sensors

Directory of Open Access Journals (Sweden)

Michael I. Newton

2013-04-01

Full Text Available Magnetic resonance imaging is a widely used technique for medical and materials imaging. Even though the objects being imaged are often irregularly shaped, suitable coils permitting the measurement of the radio-frequency signal in these systems are usually made of solid copper. One problem often encountered is how to ensure the coils are both in close proximity and conformal to the object being imaged. Whilst embroidered conductive threads have previously been used as antennae in mobile telecommunications applications, they have not previously been reported for use within magnetic resonance. In this paper we show that an embroidered single loop coil can be used in a commercial unilateral nuclear magnetic resonance system as an alternative to a solid copper. Data is presented showing the determination of both longitudinal (T1 and effective transverse (T2eff relaxation times for a flat fabric coil and the same coil conformed to an 8 cm diameter cylinder. We thereby demonstrate the principles required for the wider use of fabric based conformal coils within nuclear magnetic resonance and magnetic resonance imaging.

Class of analytic solutions for the thermally balanced magnetostatic prominence sheet

International Nuclear Information System (INIS)

Low, B.C.; Wu, S.T.

1981-01-01

This is a theoretical study of the nonlinear interplay between magnetostatic equilibrium and energy balance in a Kippenhahn-Schlueter type prominence sheet. The basic effects are illustrated explicitly with an analytic model in which a radiative loss proportional to rho 2 T balances against wave heating proportional to rho, with thermal conduction confined along magnetic field lines, where rho and T denote the plasma density and temperature, respectively. The particular choices of heat sink and source enable us to integrate the governing equations exactly while they are of the basic mathematical forms to simulate radiative loss in an optically thin plasma which is heated by wave dissipation. The steady solutions exhibit three different basic behaviors, characterized by the total wave heating in the prominence sheet being more than, equal to, or less than the total radiative loss. It is the compaction of the plasma along the field lines under its own weight combined with the effects of energy transport that determines which of the three basic behaviors obtains in a particular situation. The implications of the steady solutions for the formation of prominences are discussed. The exact solutions presented do not support the conclusion of Milne, Priest, and Roberts that there is an upper bound on the plasma beta for an equilibrium of the Kippenhahn-Schlueter prominence

Cyclotron resonant gas breakdown with a 1.22-nm 13CH3F laser

International Nuclear Information System (INIS)

Hacker, M.P.; Lax, B.; Metz, R.N.; Temkin, R.J.

1979-01-01

Cyclotron-resonant laser-induced gas breakdown has been studied for the first time in the transverse geometry, using 1.222-nm 13 CH 3 F laser radiation propagating perpendicular to the magnetic field axis. The line shape of absorbed laser radiation versus magnetic field near electron cyclotron resonance (87.75 kG) indicates a strong dependence of the line shape on the focused laser intensity. This dependence is not predicted by the standard equilibrium theory of high-frequency gas breakdown in a magnetic field. We have developed an analytic theory to explain the observed line shapes. The theory takes into account the laser propagation characteristics, in particular that there is nonuniform ionization due to strong resonant absorption of the laser radiation in a length comparable to or shorter than that of the laser focal volume. The transverse geometry simplifies the theoretical analysis because the observed line shapes are not significantly affected by Doppler broadening. Extensive data have been obtained on the fraction of laser pulse energy absorbed in the gas breakdown volume as a function of magnetic field, helium gas pressure, and incident laser pulse energy. Good quantitative agreement is obtained between the observed laser pulse absorption line shapes and the nonuniform ionization theory

Dependency of plasmon resonance sensitivity of colloidal gold nanoparticles on the identity of surrounding ionic media

Science.gov (United States)

Mehrdel, B.; Aziz, A. Abdul

2018-03-01

The plasmon resonance sensitivity of gold nanoparticles (AuNPs) in sodium chloride (NaCl) liquid in near-infrared to the visible spectral region was investigated. The correlation between NaCl concentration and refractive index was analyzed using concentration dependency and Lorenz-Lorenz methods. The first derivative method was applied to the measured absorption spectra to quantitatively evaluate the plasmon resonance sensitivity. To understand the influence of the identity of the surrounding medium on the plasmon resonance sensitivity, experiments were repeated by replacing NaCl with sodium hydroxide (NaOH), followed by phosphate buffered saline (PBS). Experimental results showed that NaCl is the most effective ionic surrounding medium, which gives prominent plasmon resonance response. AuNPs size can have a significant influence on the plasmon resonance sensitivity. For tiny AuNPs (∼10 nm AuNPs), the plasmon resonance is insensitive to the identity of the surrounding medium due to their low cross-section value.

Coupled-mode theory and Fano resonances in guided-mode resonant gratings: the conical diffraction mounting.

Science.gov (United States)

Bykov, Dmitry A; Doskolovich, Leonid L; Soifer, Victor A

2017-01-23

We study resonances of guided-mode resonant gratings in conical mounting. By developing 2D time-dependent coupled-mode theory we obtain simple approximations of the transmission and reflection coefficients. Being functions of the incident light's frequency and in-plane wave vector components, the obtained approximations can be considered as multi-variable generalizations of the Fano line shape. We show that the approximations are in good agreement with the rigorously calculated transmission and reflection spectra. We use the developed theory to investigate angular tolerances of the considered structures and to obtain mode excitation conditions. In particular, we obtain the cross-polarization mode excitation conditions in the case of conical mounting.

Heating of an Erupting Prominence Associated with a Solar Coronal Mass Ejection on 2012 January 27

Energy Technology Data Exchange (ETDEWEB)

Lee, Jin-Yi; Moon, Yong-Jae; Kim, Kap-Sung [Department of Astronomy and Space Science, Kyung Hee University, Yongin-si, Gyeonggi-do, 17104 (Korea, Republic of); Raymond, John C.; Reeves, Katharine K. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

2017-07-20

We investigate the heating of an erupting prominence and loops associated with a coronal mass ejection and X-class flare. The prominence is seen as absorption in EUV at the beginning of its eruption. Later, the prominence changes to emission, which indicates heating of the erupting plasma. We find the densities of the erupting prominence using the absorption properties of hydrogen and helium in different passbands. We estimate the temperatures and densities of the erupting prominence and loops seen as emission features using the differential emission measure method, which uses both EUV and X-ray observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and the X-ray Telescope on board Hinode . We consider synthetic spectra using both photospheric and coronal abundances in these calculations. We verify the methods for the estimation of temperatures and densities for the erupting plasmas. Then, we estimate the thermal, kinetic, radiative loss, thermal conduction, and heating energies of the erupting prominence and loops. We find that the heating of the erupting prominence and loop occurs strongly at early times in the eruption. This event shows a writhing motion of the erupting prominence, which may indicate a hot flux rope heated by thermal energy release during magnetic reconnection.

Observations of apparent superslow wave propagation in solar prominences

Science.gov (United States)

Raes, J. O.; Van Doorsselaere, T.; Baes, M.; Wright, A. N.

2017-06-01

Context. Phase mixing of standing continuum Alfvén waves and/or continuum slow waves in atmospheric magnetic structures such as coronal arcades can create the apparent effect of a wave propagating across the magnetic field. Aims: We observe a prominence with SDO/AIA on 2015 March 15 and find the presence of oscillatory motion. We aim to demonstrate that interpreting this motion as a magneto hydrodynamic (MHD) wave is faulty. We also connect the decrease of the apparent velocity over time with the phase mixing process, which depends on the curvature of the magnetic field lines. Methods: By measuring the displacement of the prominence at different heights to calculate the apparent velocity, we show that the propagation slows down over time, in accordance with the theoretical work of Kaneko et al. We also show that this propagation speed drops below what is to be expected for even slow MHD waves for those circumstances. We use a modified Kippenhahn-Schlüter prominence model to calculate the curvature of the magnetic field and fit our observations accordingly. Results: Measuring three of the apparent waves, we get apparent velocities of 14, 8, and 4 km s-1. Fitting a simple model for the magnetic field configuration, we obtain that the filament is located 103 Mm below the magnetic centre. We also obtain that the scale of the magnetic field strength in the vertical direction plays no role in the concept of apparent superslow waves and that the moment of excitation of the waves happened roughly one oscillation period before the end of the eruption that excited the oscillation. Conclusions: Some of the observed phase velocities are lower than expected for slow modes for the circumstances, showing that they rather fit with the concept of apparent superslow propagation. A fit with our magnetic field model allows for inferring the magnetic geometry of the prominence. The movie attached to Fig. 1 is available at http://www.aanda.org

Synthetic differential emission measure curves of prominence fine structures. II. The SoHO/SUMER prominence of 8 June 2004

Czech Academy of Sciences Publication Activity Database

Gunár, Stanislav; Parenti, S.; Anzer, U.; Heinzel, Petr; Vial, J. C.

2011-01-01

Roč. 535, November (2011), A122/1-A122/11 ISSN 0004-6361 R&D Projects: GA ČR GP205/09/P554; GA ČR GA205/09/1705; GA ČR GAP209/10/1706 Institutional research plan: CEZ:AV0Z10030501 Keywords : Sun * filaments * prominences Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.587, year: 2011

A parity checker circuit based on microelectromechanical resonator logic elements

Energy Technology Data Exchange (ETDEWEB)

Hafiz, Md Abdullah Al, E-mail: abdullah.hafiz@kaust.edu.sa [CEMSE Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia); Li, Ren [CEMSE Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia); Younis, Mohammad I. [PSE Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia); Fariborzi, Hossein [CEMSE Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

2017-03-03

Micro/nano-electromechanical resonator based logic computation has attracted significant attention in recent years due to its dynamic mode of operation, ultra-low power consumption, and potential for reprogrammable and reversible computing. Here we demonstrate a 4-bit parity checker circuit by utilizing recently developed logic gates based on MEMS resonators. Toward this, resonance frequencies of shallow arch shaped micro-resonators are electrothermally tuned by the logic inputs to constitute the required logic gates for the proposed parity checker circuit. This study demonstrates that by utilizing MEMS resonator based logic elements, complex digital circuits can be realized. - Highlights: • A 4-bit parity checker circuit is proposed and demonstrated based on MEMS resonator based logic elements. • Multiple copies of MEMS resonator based XOR logic gates are used to construct a complex logic circuit. • Functionality and feasibility of micro-resonator based logic platform is demonstrated.

Resonance effects in elastic cross sections for electron scattering on pyrimidine: Experiment and theory.

Science.gov (United States)

Regeta, Khrystyna; Allan, Michael; Winstead, Carl; McKoy, Vincent; Mašín, Zdeněk; Gorfinkiel, Jimena D

2016-01-14

We measured differential cross sections for elastic (rotationally integrated) electron scattering on pyrimidine, both as a function of angle up to 180(∘) at electron energies of 1, 5, 10, and 20 eV and as a function of electron energy in the range 0.1-14 eV. The experimental results are compared to the results of the fixed-nuclei Schwinger variational and R-matrix theoretical methods, which reproduce satisfactorily the magnitudes and shapes of the experimental cross sections. The emphasis of the present work is on recording detailed excitation functions revealing resonances in the excitation process. Resonant structures are observed at 0.2, 0.7, and 4.35 eV and calculations for different symmetries confirm their assignment as the X̃(2)A2, Ã(2)B1, and B̃(2)B1 shape resonances. As a consequence of superposition of coherent resonant amplitudes with background scattering the B̃(2)B1 shape resonance appears as a peak, a dip, or a step function in the cross sections recorded as a function of energy at different scattering angles and this effect is satisfactorily reproduced by theory. The dip and peak contributions at different scattering angles partially compensate, making the resonance nearly invisible in the integral cross section. Vibrationally integrated cross sections were also measured at 1, 5, 10 and 20 eV and the question of whether the fixed-nuclei cross sections should be compared to vibrationally elastic or vibrationally integrated cross section is discussed.

Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

Science.gov (United States)

Wu, Jiayang; Moein, Tania; Xu, Xingyuan; Moss, David J.

2018-04-01

We demonstrate advanced integrated photonic filters in silicon-on-insulator (SOI) nanowires implemented by cascaded Sagnac loop reflector (CSLR) resonators. We investigate mode splitting in these standing-wave (SW) resonators and demonstrate its use for engineering the spectral profile of on-chip photonic filters. By changing the reflectivity of the Sagnac loop reflectors (SLRs) and the phase shifts along the connecting waveguides, we tailor mode splitting in the CSLR resonators to achieve a wide range of filter shapes for diverse applications including enhanced light trapping, flat-top filtering, Q factor enhancement, and signal reshaping. We present the theoretical designs and compare the CSLR resonators with three, four, and eight SLRs fabricated in SOI. We achieve versatile filter shapes in the measured transmission spectra via diverse mode splitting that agree well with theory. This work confirms the effectiveness of using CSLR resonators as integrated multi-functional SW filters for flexible spectral engineering.

LARGE-SCALE FLOWS IN PROMINENCE CAVITIES

International Nuclear Information System (INIS)

Schmit, D. J.; Gibson, S. E.; Tomczyk, S.; Reeves, K. K.; Sterling, Alphonse C.; Brooks, D. H.; Williams, D. R.; Tripathi, D.

2009-01-01

Regions of rarefied density often form cavities above quiescent prominences. We observed two different cavities with the Coronal Multichannel Polarimeter on 2005 April 21 and with Hinode/EIS on 2008 November 8. Inside both of these cavities, we find coherent velocity structures based on spectral Doppler shifts. These flows have speeds of 5-10 km s -1 , occur over length scales of tens of megameters, and persist for at least 1 hr. Flows in cavities are an example of the nonstatic nature of quiescent structures in the solar atmosphere.

Prominent crista terminalis mimicking a right atrial mass: case report

Directory of Open Access Journals (Sweden)

Lange Peter

2010-10-01

Full Text Available Abstract The crista terminalis is a normal anatomical structure within the right atrium that is not normally visualised in the standard views obtained while performing a transthoracic echocardiogram. In this case report, transthoracic echocardiography suggested the presence of a right atrial mass in a patient with end stage renal disease. However, subsequent transesophageal echocardiography revealed that the right atrial mass was actually a thick muscular bridge in the right atrium consistent with a prominent crista terminalis. An understanding of the anatomy and the echocardiographic appearance of a prominent crista terminalis will minimize the misdiagnosis of this structure avoiding unnecessary expensive additional tests.

ERRATUM: Propagating Waves Transverse to the Magnetic Field in a Solar Prominence

Science.gov (United States)

Schmieder, B.; Kucera, T. A.; Knizhnik, K.; Luna, M.; Lopez-Ariste, A.; Toot, D.

2014-01-01

We report an unusual set of observations of waves in a large prominence pillar that consist of pulses propagating perpendicular to the prominence magnetic field. We observe a huge quiescent prominence with the Solar Dynamics Observatory Atmospheric Imaging Assembly in EUV on 2012 October 10 and only a part of it, the pillar, which is a foot or barb of the prominence, with the Hinode Solar Optical Telescope (SOT; in Ca II and Halpha lines), Sac Peak (in Ha, Hß, and Na-D lines), and THEMIS ("Télescope Héliographique pour l' Etude du Magnétisme et des Instabilités Solaires") with the MTR (MulTi-Raies) spectropolarimeter (in He D3 line). The THEMIS/MTR data indicates that the magnetic field in the pillar is essentially horizontal and the observations in the optical domain show a large number of horizontally aligned features on a much smaller scale than the pillar as a whole. The data are consistent with a model of cool prominence plasma trapped in the dips of horizontal field lines. The SOT and Sac Peak data over the four hour observing period show vertical oscillations appearing as wave pulses. These pulses, which include a Doppler signature, move vertically, perpendicular to the field direction, along thin quasi-vertical columns in the much broader pillar. The pulses have a velocity of propagation of about 10 km/s, a period of about 300 s, and a wavelength around 2000 km. We interpret these waves in terms of fast magnetosonic waves and discuss possible wave drivers.

The Fate of Cool Material in the Hot Corona: Solar Prominences and Coronal Rain

Science.gov (United States)

Liu, Wei; Antolin, Patrick; Sun, Xudong; Vial, Jean-Claude; Berger, Thomas

2017-08-01

As an important chain of the chromosphere-corona mass cycle, some of the million-degree hot coronal mass undergoes a radiative cooling instability and condenses into material at chromospheric or transition-region temperatures in two distinct forms - prominences and coronal rain (some of which eventually falls back to the chromosphere). A quiescent prominence usually consists of numerous long-lasting, filamentary downflow threads, while coronal rain consists of transient mass blobs falling at comparably higher speeds along well-defined paths. It remains puzzling why such material of similar temperatures exhibit contrasting morphologies and behaviors. We report recent SDO/AIA and IRIS observations that suggest different magnetic environments being responsible for such distinctions. Specifically, in a hybrid prominence-coronal rain complex structure, we found that the prominence material is formed and resides near magnetic null points that favor the radiative cooling process and provide possibly a high plasma-beta environment suitable for the existence of meandering prominence threads. As the cool material descends, it turns into coronal rain tied onto low-lying coronal loops in a likely low-beta environment. Such structures resemble to certain extent the so-called coronal spiders or cloud prominences, but the observations reported here provide critical new insights. We will discuss the broad physical implications of these observations for fundamental questions, such as coronal heating and beyond (e.g., in astrophysical and/or laboratory plasma environments).

Parametric resonance of intrinsic localized modes in coupled cantilever arrays

International Nuclear Information System (INIS)

Kimura, Masayuki; Matsushita, Yasuo; Hikihara, Takashi

2016-01-01

In this study, the parametric resonances of pinned intrinsic localized modes (ILMs) were investigated by computing the unstable regions in parameter space consisting of parametric excitation amplitude and frequency. In the unstable regions, the pinned ILMs were observed to lose stability and begin to fluctuate. A nonlinear Klein–Gordon, Fermi–Pasta–Ulam-like, and mixed lattices were investigated. The pinned ILMs, particularly in the mixed lattice, were destabilized by parametric resonances, which were determined by comparing the shapes of the unstable regions with those in the Mathieu differential equation. In addition, traveling ILMs could be generated by parametric excitation. - Highlights: • Destabilization of intrinsic localized modes (ILMs) by parametric excitation is investigated for FPU, NKG, and mixed lattices. • Frequency and amplitude of parametric excitation is determined based on characteristic multipliers of ILMs. • Unstable regions for the mixed lattice case show very similar shape to those of the Mathieu equation. • ILMs become unstable by causing parametric resonance.

Parametric resonance of intrinsic localized modes in coupled cantilever arrays

Energy Technology Data Exchange (ETDEWEB)

Kimura, Masayuki, E-mail: kimura.masayuki.8c@kyoto-u.ac.jp [Department of Electrical Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan); Matsushita, Yasuo [Advanced Mathematical Institute, Osaka City University, 3-3-138 Sughimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Hikihara, Takashi [Department of Electrical Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)

2016-08-19

In this study, the parametric resonances of pinned intrinsic localized modes (ILMs) were investigated by computing the unstable regions in parameter space consisting of parametric excitation amplitude and frequency. In the unstable regions, the pinned ILMs were observed to lose stability and begin to fluctuate. A nonlinear Klein–Gordon, Fermi–Pasta–Ulam-like, and mixed lattices were investigated. The pinned ILMs, particularly in the mixed lattice, were destabilized by parametric resonances, which were determined by comparing the shapes of the unstable regions with those in the Mathieu differential equation. In addition, traveling ILMs could be generated by parametric excitation. - Highlights: • Destabilization of intrinsic localized modes (ILMs) by parametric excitation is investigated for FPU, NKG, and mixed lattices. • Frequency and amplitude of parametric excitation is determined based on characteristic multipliers of ILMs. • Unstable regions for the mixed lattice case show very similar shape to those of the Mathieu equation. • ILMs become unstable by causing parametric resonance.

Design of etch holes to compensate spring width loss for reliable resonant frequencies

International Nuclear Information System (INIS)

Jang, Yun-Ho; Kim, Jong-Wan; Kim, Yong-Kweon; Kim, Jung-Mu

2012-01-01

A pattern width loss during the fabrication of lateral silicon resonators degrades resonant frequency reliability since such a width loss causes the significant deviation of spring stiffness. Here we present a design guide for etch holes to obtain reliable resonant frequencies by controlling etch holes geometries. The new function of an etch hole is to generate the comparable amount of the width loss between springs and etch holes, in turn to minimize the effect of the spring width loss on resonant frequency shift and deviation. An analytic expression reveals that a compensation factor (CF), defined by the circumference (C u ) of a unit etch hole divided by its silicon area (A u ), is a key parameter for reliable frequencies. The protrusive etch holes were proposed and compared with square etch holes to demonstrate the frequency reliability according to CF values and etch hole shapes. The normalized resonant frequency shift and deviation of the protrusive etch hole (−13.0% ± 6.9%) were significantly improved compared to those of a square etch hole with a small CF value (−42.8% ± 14.8%). The proposed design guide based on the CF value and protrusive shapes can be used to achieve reliable resonant frequencies for high performance silicon resonators. (technical note)

Hydrothermally synthesized PZT film grown in highly concentrated KOH solution with large electromechanical coupling coefficient for resonator

Science.gov (United States)

Feng, Guo-Hua; Lee, Kuan-Yi

2017-12-01

This paper presents a study of lead zirconate titanate (PZT) films hydrothermally grown on a dome-shaped titanium diaphragm. Few articles in the literature address the implementation of hydrothermal PZT films on curved-diaphragm substrates for resonators. In this study, a 50-μm-thick titanium sheet is embossed using balls of designed dimensions to shape a dome-shaped cavity array. Through single-process hydrothermal synthesis, PZT films are grown on both sides of the processed titanium diaphragm with good adhesion and uniformity. The hydrothermal synthesis process involves a high concentration of potassium hydroxide solution and excess amounts of lead acetate and zirconium oxychloride octahydrate. Varied deposition times and temperatures of PZT films are investigated. The grown films are characterized by X-ray diffraction and scanning electron microscopy. The 10-μm-thick PZT dome-shaped resonators with 60- and 20-μm-thick supporting layers are implemented and further tested. Results for both resonators indicate that large electromechanical coupling coefficients and a series resonance of 95 MHz from 14 MHz can be attained. The device is connected to a complementary metal-oxide-semiconductor integrated circuit for analysis of oscillator applications. The oscillator reaches a Q value of 6300 in air. The resonator exhibits a better sensing stability when loaded with water when compared with air.

Path-integral approach to resonant electron-molecule scattering

International Nuclear Information System (INIS)

Winterstetter, M.; Domcke, W.

1993-01-01

A path-integral formulation of resonant electron-molecule scattering is developed within the framework of the projection-operator formalism of scattering theory. The formation and decay of resonances is treated in real time as a quantum-mechanical electronic-tunneling process, modified by the coupling of the electronic motion with the nuclear degrees of freedom. It is shown that the electronic continuum can be summed over in the path-integral formulation, resulting formally in the path integral for an effective two-state system with coupling to vibrations. The harmonic-oscillator approximation is adopted for the vibrational motion in the present work. Approximation methods are introduced which render the numerical evaluation of the sum over paths feasible for up to ∼10 3 elementary time slices. The theory is numerically realized for simple but nontrivial models representing the 2 Π g d-wave shape resonance in e - +N 2 collisions and the 2 Σ u + p-wave shape resonance in e - +H 2 collisions, respectively. The accuracy of the path-integral results is assessed by comparison with exact numerical reference data for these models. The essential virtue of the path-integral approach is the fact that the computational effort scales at most linearly with the number of vibrational degrees of freedom. The path-integral method is thus well suited to treat electron collisions with polyatomic molecules and molecular aggregates

Vibration mode and vibration shape under excitation of a three phase model transformer core

Science.gov (United States)

Okabe, Seiji; Ishigaki, Yusuke; Omura, Takeshi

2018-04-01

Structural vibration characteristics and vibration shapes under three-phase excitation of a archetype transformer core were investigated to consider their influences on transformer noise. Acoustic noise and vibration behavior were measured in a three-limb model transformer core. Experimental modal analysis by impact test was performed. The vibration shapes were measured by a laser scanning vibrometer at different exciting frequencies. Vibration amplitude of the core in out-of-plane direction were relatively larger than those in other two in-plane directions. It was consistent with the result that the frequency response function of the core in out-of-plane direction was larger by about 20 dB or more than those in in-plane directions. There were many vibration modes having bending deformation of limbs in out-of-plane direction. The vibration shapes of the core when excited at 50 Hz and 60 Hz were almost the same because the fundamental frequencies of the vibration were not close to the resonance frequencies. When excitation frequency was 69 Hz which was half of one of the resonance frequencies, the vibration shape changed to the one similar to the resonance vibration mode. Existence of many vibration modes in out-of-plane direction of the core was presumed to be a reason why frequency characteristics of magnetostriction and transformer noise do not coincide.

Whole genome microarray analysis of chicken embryo facial prominences

Czech Academy of Sciences Publication Activity Database

Buchtová, Marcela; Kuo, W. P.; Nimmagadda, S.; Benson, S. L.; Geetha-Loganathan, P.; Logan, C.; Au-Yeung, T.; Chiang, E.; Fu, K.; Richman, J. M.

2010-01-01

Roč. 239, - (2010), s. 574-591 ISSN 1058-8388 Institutional research plan: CEZ:AV0Z50450515 Keywords : pharyngeal arch * mandibular arch * maxillary prominence Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.864, year: 2010

The Most Prominent Roles of an ESP Teacher

Science.gov (United States)

Ghafournia, Narjes; Sabet, Shokoofeh Ahmadian

2014-01-01

One prominent feature of many ESP (English for Specific Purposes) courses, which make them rather different from EGP (English for General Purposes) courses, is the presence of adult learners, who are primary workers and secondary learners. As ESP is a highly learner-cantered approach, paying close attention to the multidimensional needs of…

Further Validation of the Coach Identity Prominence Scale

Science.gov (United States)

Pope, J. Paige; Hall, Craig R.

2014-01-01

This study was designed to examine select psychometric properties of the Coach Identity Prominence Scale (CIPS), including the reliability, factorial validity, convergent validity, discriminant validity, and predictive validity. Coaches (N = 338) who averaged 37 (SD = 12.27) years of age, had a mean of 13 (SD = 9.90) years of coaching experience,…

SOLAR LIMB PROMINENCE CATCHER AND TRACKER (SLIPCAT): AN AUTOMATED SYSTEM AND ITS PRELIMINARY STATISTICAL RESULTS

International Nuclear Information System (INIS)

Wang Yuming; Cao Hao; Chen Junhong; Zhang Tengfei; Yu Sijie; Zheng Huinan; Shen Chenglong; Wang, S.; Zhang Jie

2010-01-01

In this paper, we present an automated system, which has the capability to catch and track solar limb prominences based on observations from the extreme-ultraviolet (EUV) 304 A passband. The characteristic parameters and their evolution, including height, position angle, area, length, and brightness, are obtained without manual interventions. By applying the system to the STEREO-B/SECCHI/EUVI 304 A data during 2007 April-2009 October, we obtain a total of 9477 well-tracked prominences and a catalog of these events available online. A detailed analysis of these prominences suggests that the system has a rather good performance. We have obtained several interesting statistical results based on the catalog. Most prominences appear below the latitude of 60 0 and at the height of about 26 Mm above the solar surface. Most of them are quite stable during the period they are tracked. Nevertheless, some prominences have an upward speed of more than 100 km s -1 , and some others show significant downward and/or azimuthal speeds. There are strong correlations among the brightness, area, and height. The expansion of a prominence is probably one major cause of its fading during the rising or erupting process.

Quantitative genetics of plastron shape in slider turtles (Trachemys scripta).

Science.gov (United States)

Myers, Erin M; Janzen, Fredric J; Adams, Dean C; Tucker, John K

2006-03-01

Shape variation is widespread in nature and embodies both a response to and a source for evolution and natural selection. To detect patterns of shape evolution, one must assess the quantitative genetic underpinnings of shape variation as well as the selective environment that the organisms have experienced. Here we used geometric morphometrics to assess variation in plastron shell shape in 1314 neonatal slider turtles (Trachemys scripta) from 162 clutches of laboratory-incubated eggs from two nesting areas. Multivariate analysis of variance indicated that nesting area has a limited role in describing plastron shape variation among clutches, whereas differences between individual clutches were highly significant, suggesting a prominent clutch effect. The covariation between plastron shape and several possible maternal effect variables (yolk hormone levels and egg dimensions) was assessed for a subset of clutches and found to be negligible. We subsequently employed several recently proposed methods for estimating heritability from shape variables, and generalized a univariate approach to accommodate unequal sample sizes. Univariate estimates of shape heritability based on Procrustes distances yielded large values for both nesting populations (h2 approximately 0.86), and multivariate estimates of maximal additive heritability were also large for both nesting populations (h2max approximately 0.57). We also estimated the dominant trend in heritable shape change for each nesting population and found that the direction of shape evolution was not the same for the two sites. Therefore, although the magnitude of shape evolution was similar between nesting populations, the manner in which plastron shape is evolving is not. We conclude that the univariate approach for assessing quantitative genetic parameters from geometric morphometric data has limited utility, because it is unable to accurately describe how shape is evolving.

Spectral shaping of an all-fiber torsional acousto-optic tunable filter.

Science.gov (United States)

Ko, Jeakwon; Lee, Kwang Jo; Kim, Byoung Yoon

2014-12-20

Spectral shaping of an all-fiber torsional acousto-optic (AO) tunable filter is studied. The technique is based on the axial modulation of AO coupling strength along a highly birefringent optical fiber, which is achieved by tailoring the outer diameter of the fiber along its propagation axis. Two kinds of filter spectral shaping schemes-Gaussian apodization and matched filtering with triple resonance peaks-are proposed and numerically investigated under realistic experimental conditions: at the 50-cm-long AO interaction length of the fiber and at half of the original fiber diameter as the minimum thickness of the tailored fiber section. The results show that the highest peak of sidelobe spectra in filter transmission is suppressed from 11.64% to 0.54% via Gaussian modulation of the AO coupling coefficient (κ). Matched filtering with triple resonance peaks operating with a single radio frequency signal is also achieved by cosine modulation of κ, of which the modulation period determines the spectral distance between two satellite peaks located in both wings of the main resonance peak. The splitting of two satellite peaks in the filter spectra reaches 48.2 nm while the modulation period varies from 7.7 to 50 cm. The overall peak power of two satellite resonances is calculated to be 22% of the main resonance power. The results confirm the validity and practicality of our approach, and we predict robust and stable operation of the designed all-fiber torsional AO filters.

Hydrogen line formation in the quescent prominences

International Nuclear Information System (INIS)

Tsovookhuu, Ch.

1980-01-01

Equations of transfer and statistical equilibrium for hydronen atom with eight bound levels and continuum are solved simultaneously. A plane-parallel layer located perpendicular to the Sun surface is taken as a geometrical model. Input parameters of the physical model are optical thickness in the center of Hsub(α) line, electron temperature and concentration in the layer center are well as temperature and density gradients. Functions of sources, line profiles, total energies and the Balmer decrements, which are compared with observations and theoretical calculations made by other authors, have been calculated. The comparison shows that the results are quite acceptable and can be used when analyzing the spectrum and determining physical parameters of solar prominences. Dependence of different performances of the line (equivalent width, central intensity, halfwidth, depth of central depression etc.) on values of initial model parameters is investigated. Line halfwidth is more sensitive to the temperatuu value in the layer center, while central intensity - to the value of temperature gradient and a depth of central depression - to electron concentration. Calculated were shares of primary sources responsible for different excitation mechanism depending on total optical thickness as well as mean probabilities of quantum yield out of a medium which can be used during parametric accountancy of radiation diffusion in solar prominences [ru

Influence of edge roughness on graphene nanoribbon resonant tunnelling diodes

International Nuclear Information System (INIS)

Liang Gengchiau; Khalid, Sharjeel Bin; Lam, Kai-Tak

2010-01-01

The edge roughness effects of graphene nanoribbons on their application in resonant tunnelling diodes with different geometrical shapes (S, H and W) were investigated. Sixty samples for each 5%, 10% and 15% edge roughness conditions of these differently shaped graphene nanoribbon resonant tunnelling diodes were randomly generated and studied. Firstly, it was observed that edge roughness in the barrier regions decreases the effective barrier height and thickness, which increases the broadening of the quantized states in the quantum well due to the enhanced penetration of the wave-function tail from the electrodes. Secondly, edge roughness increases the effective width of the quantum well and causes the lowering of the quantized states. Furthermore, the shape effects on carrier transport are modified by edge roughness due to different interfacial scattering. Finally, with the effects mentioned above, edge roughness has a considerable impact on the device performance in terms of varying the peak-current positions and degrading the peak-to-valley current ratio.

Microwave-Controlled Generation of Shaped Single Photons in Circuit Quantum Electrodynamics

Directory of Open Access Journals (Sweden)

M. Pechal

2014-10-01

Full Text Available Large-scale quantum information processors or quantum communication networks will require reliable exchange of information between spatially separated nodes. The links connecting these nodes can be established using traveling photons that need to be absorbed at the receiving node with high efficiency. This is achievable by shaping the temporal profile of the photons and absorbing them at the receiver by time reversing the emission process. Here, we demonstrate a scheme for creating shaped microwave photons using a superconducting transmon-type three-level system coupled to a transmission line resonator. In a second-order process induced by a modulated microwave drive, we controllably transfer a single excitation from the third level of the transmon to the resonator and shape the emitted photon. We reconstruct the density matrices of the created single-photon states and show that the photons are antibunched. We also create multipeaked photons with a controlled amplitude and phase. In contrast to similar existing schemes, the one we present here is based solely on microwave drives, enabling operation with fixed frequency transmons.

An analysis of stripping to isolated analog resonances

International Nuclear Information System (INIS)

Pessoa, E.F.; Toledo Piza, A.F.R. de.

1983-04-01

The Feshbach projection formalism is used to calculate the form factors for the (d,n) stripping process to isolated analog resonances. These are used in a standard DWBA stripping calculation in which the radial integration over all space is accomplished by including outerspace contributions evaluated along the complex contours of Vincent and Fortune. It turns out that the shape and magnitude of the predicted cross section is quite insensitive to the continuum proton wave emanating from the resonant residual state. (Author) [pt

Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

Directory of Open Access Journals (Sweden)

Jiayang Wu

2018-04-01

Full Text Available We demonstrate advanced integrated photonic filters in silicon-on-insulator (SOI nanowires implemented by cascaded Sagnac loop reflector (CSLR resonators. We investigate mode splitting in these standing-wave (SW resonators and demonstrate its use for engineering the spectral profile of on-chip photonic filters. By changing the reflectivity of the Sagnac loop reflectors (SLRs and the phase shifts along the connecting waveguides, we tailor mode splitting in the CSLR resonators to achieve a wide range of filter shapes for diverse applications including enhanced light trapping, flat-top filtering, Q factor enhancement, and signal reshaping. We present the theoretical designs and compare the CSLR resonators with three, four, and eight SLRs fabricated in SOI. We achieve versatile filter shapes in the measured transmission spectra via diverse mode splitting that agree well with theory. This work confirms the effectiveness of using CSLR resonators as integrated multi-functional SW filters for flexible spectral engineering.

Precision angle-resolved autoionization resonances in Ar and Ne

Energy Technology Data Exchange (ETDEWEB)

Berrah, N.; Langer, B.; Gorczyca, T.W. [Western Michigan Univ., Kalamazoo, MI (United States)] [and others

1997-04-01

Theoretical work has shown that the electron angular distribution and the shape of the autoionization resonances are crucial to the understanding of certain types of electron-electron correlation. Autoionization resonances in Ne (Ar) result from the decay of the excited discrete state Ne{sup *} 2s2p{sup 6} np (Ar{sup *} 3s3p{sup 6} np) into the continuum state Ne{sup +} 2s{sup 2}2p{sup 5} + e{sup {minus}} (ks,kd) (Ar{sup +} 3s{sup 2}3p{sup 5} + e{sup {minus}} (ks,kd)). Since the continuum can also be reached by direct photoionization, both paths add coherently, giving rise to interferences that produce the characteristic Beutler-Fano line shape. In this work, the authors report on quantitative angle-resolved electron spectrometry studies of (a) the Ne 2s{sup 2}2p{sup 6} {r_arrow} 2s2p{sup 6} np (n=3-5) autoionizing resonances and the 2s{sup 2}2p{sup 6} {r_arrow} 2p{sup 4}3s3p doubly excited resonance, (b) the Ar 3s{sup 2}3p{sup 6} {r_arrow} 3s3p{sup 6} np (n=4-9) autoionization resonances and extended R-matrix calculations of the angular-distribution parameters for both Ne and Ar measurements. Their results are compared with previous theoretical work by Taylor.

Recent Crystal Ball results on resonance formation in photon-photon collisions

International Nuclear Information System (INIS)

Karch, K.H.

1991-04-01

The Crystal Ball detector has been used to analyse the formation of resonances in photon-photon collisions. The π 2 (1670) resonance has been observed in the 3π 0 final state, as well as the η' (958) and X (1900) resonances in the ηπ 0 π 0 final state. The X (1900) decay distributions are consistent with the assumption that it is the J PC = 2 -+ η 2 meson. Preliminary analyses of the 8, 10 and 12γ final states are presented. The tensor meson f 2 (1270) is the most prominent structure in the energy dependence of the total cross section σ (γγ → π 0 π 0 ), but close investigation of the differential cross section indicates the presence of a sizeable S wave contribution. This observation is consistent with a broad scalar meson f 0 (1250), degenerate in mass with the f 2 . Indications for the f 0 (975) mesons have been found, too. (orig.)

SYNTHETIC HYDROGEN SPECTRA OF OSCILLATING PROMINENCE SLABS IMMERSED IN THE SOLAR CORONA

International Nuclear Information System (INIS)

Zapiór, M.; Heinzel, P.; Oliver, R.; Ballester, J. L.

2016-01-01

We study the behavior of H α and H β spectral lines and their spectral indicators in an oscillating solar prominence slab surrounded by the solar corona, using an MHD model combined with a 1D radiative transfer code taken in the line of sight perpendicular to the slab. We calculate the time variation of the Doppler shift, half-width, and maximum intensity of the H α and H β spectral lines for different modes of oscillation. We find a non-sinusoidal time dependence of some spectral parameters with time. Because H α and H β spectral indicators have different behavior for different modes, caused by differing optical depths of formation and different plasma parameter variations in time and along the slab, they may be used for prominence seismology, especially to derive the internal velocity field in prominences.

SYNTHETIC HYDROGEN SPECTRA OF OSCILLATING PROMINENCE SLABS IMMERSED IN THE SOLAR CORONA

Energy Technology Data Exchange (ETDEWEB)

Zapiór, M.; Heinzel, P. [Astronomical Institute, The Czech Academy of Sciences, 25165 Ondřejov, The Czech Republic (Czech Republic); Oliver, R.; Ballester, J. L. [Universitat de les Illes Balears. Cra. de Valldemossa, km 7.5. Palma (Illes Balears), E-07122 (Spain)

2016-08-20

We study the behavior of H α and H β spectral lines and their spectral indicators in an oscillating solar prominence slab surrounded by the solar corona, using an MHD model combined with a 1D radiative transfer code taken in the line of sight perpendicular to the slab. We calculate the time variation of the Doppler shift, half-width, and maximum intensity of the H α and H β spectral lines for different modes of oscillation. We find a non-sinusoidal time dependence of some spectral parameters with time. Because H α and H β spectral indicators have different behavior for different modes, caused by differing optical depths of formation and different plasma parameter variations in time and along the slab, they may be used for prominence seismology, especially to derive the internal velocity field in prominences.

False Memories for Shape Activate the Lateral Occipital Complex

Science.gov (United States)

Karanian, Jessica M.; Slotnick, Scott D.

2017-01-01

Previous functional magnetic resonance imaging evidence has shown that false memories arise from higher-level conscious processing regions rather than lower-level sensory processing regions. In the present study, we assessed whether the lateral occipital complex (LOC)--a lower-level conscious shape processing region--was associated with false…

The osseous external auditory canal : Surgery, shape, and sound

NARCIS (Netherlands)

van Spronsen, E.

2018-01-01

This thesis describes three aspects of the osseous external auditory canal (OEAC) which are related to each other: Surgery of the OEAC, the shape of the OEAC and the perceived sound quality due to the resonance function of the OEAC. Several aspects of the surgical intervention (Canalplasty) in

High-frequency performance for a spiral-shaped piezoelectric bimorph

Science.gov (United States)

Huang, Fang Sheng; Feng, Zhi Hua; Ma, Yu Ting; Pan, Qiao Sheng; Zhang, Lian Sheng; Liu, Yong Bin; He, Liang Guo

2018-04-01

Piezoelectric cantilever is suitable as an actuator for micro-flapping-wing aircraft. Higher resonant frequency brings about stronger flight energy, and the flight amplitude can be compensated by displacement-amplification mechanism, such as lever. To obtain a higher resonant frequency, straight piezoelectric bimorph was rolled into spiral-shaped piezoelectric bimorph with identical effective length in this study, which is verified in COMSOL simulations. Simulation results show that compared with the straight piezoelectric bimorph, the spiral-shaped piezoelectric bimorph with two turns has higher inherent frequencies (from 204.79 Hz to 504.84 Hz in terms of axial oscillation mode, and from 319.77 Hz to 704.48 Hz in terms of tangential torsional mode). The spiral-shaped piezoelectric bimorph is fabricated by a precise laser cutting process and consists of two turns with effective length of 60 mm, width of 2.5 mm, and thickness of 1.6 mm, respectively. With the excitation voltage of 100 Vpp applying an electric field across the thickness of the bimorph, the tip displacement of the actuator in the axial oscillation and tangential torsional modes are 85 μm and 15 μm, respectively.

Ancestral Variations in the Shape and Size of the Zygoma.

Science.gov (United States)

Oettlé, Anna C; Demeter, Fabrice P; L'abbé, Ericka N

2017-01-01

The variable development of the zygoma, dictating its shape and size variations among ancestral groups, has important clinical implications and valuable anthropological and evolutionary inferences. The purpose of the study was to review the literature regarding the variations in the zygoma with ancestry. Ancestral variation in the zygoma reflects genetic variations because of genetic drift as well as natural selection and epigenetic changes to adapt to diet and climate variations with possible intensification by isolation. Prominence of the zygoma, zygomaxillary tuberosity, and malar tubercle have been associated with Eastern Asian populations in whom these features intensified. Prominence of the zygoma is also associated with groups from Eastern Europe and the rest of Asia. Diffusion of these traits occurred across the Behring Sea to the Arctic areas and to North and South America. The greatest zygomatic projections are exhibited in Arctic groups as an adaptation to extreme cold conditions, while Native South American groups also present with other features of facial robusticity. Groups from Australia, Malaysia, and Oceania show prominence of the zygoma to a certain extent, possibly because of archaic occupations by undifferentiated Southeast Asian populations. More recent interactions with Chinese groups might explain the prominent cheekbones noted in certain South African groups. Many deductions regarding evolutionary processes and diversifications of early groups have been made. Cognisance of these ancestral variations also have implications for forensic anthropological assessments as well as plastic and reconstructive surgery. More studies are needed to improve accuracy of forensic anthropological identification techniques. Anat Rec, 300:196-208, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Screening Resonances In Plasmas

International Nuclear Information System (INIS)

Winkler, P.

1998-01-01

When it was suggested that a new recombination mechanism (Resonant Radiative Recombination (RRR)) which, based on very general physical arguments, should happen in dense plasmas and promises to provide useful information for the local temperature and density diagnostics of plasmas, they assumed the existence of screening resonances. For model potentials the existence of screening resonances has been demonstrated beyond reasonable doubt in a number of calculations. The key question, how well those potentials describe the dominant effects of a real plasma remains open. The relation of theoretical predictions to experimentally measurable effects is an important issue at the present stage of their research. In particular, RRR is expected to account for enhanced recombination rates of low energetic electrons with their ions, since the first stage is the resonant capture of a slow electron by an atom or ion. The mechanism that traps an electron is a combination of complicated many-body interactions of the ions and electrons. For clarity they start here, however, with a discussion in terms of local potential traps the shapes of which are determined predominantly and in an average way by two factors: the degree of screening present at the ionic site and the degree of short-range order in the immediate neighborhood of this ion

Multiband Split-Ring Resonator Based Planar Inverted-F Antenna for 5G Applications

Directory of Open Access Journals (Sweden)

Muhammad Kamran Ishfaq

2017-01-01

Full Text Available 5G, the fifth generation of wireless communications, is focusing on multiple frequency bands, such as 6 GHz, 10 GHz, 15 GHz, 28 GHz, and 38 GHz, to achieve high data rates up to 10 Gbps or more. The industry demands multiband antennas to cover these distant frequency bands, which is a task much more challenging. In this paper, we have designed a novel multiband split-ring resonator (SRR based planar inverted-F antenna (PIFA for 5G applications. It is composed of a PIFA, an inverted-L parasitic element, a rectangular shaped parasitic element, and a split-ring resonator (SRR etched on the top plate of the PIFA. The basic PIFA structure resonates at 6 GHz. An addition of a rectangular shaped parasitic element produces a resonance at 15 GHz. The introduction of a split-ring resonator produces a band notch at 8 GHz, and a resonance at 10 GHz, while the insertion of an inverted-L shaped parasitic element further enhances the impedance bandwidth in the 10 GHz band. The frequency bands covered, each with more than 1 GHz impedance bandwidth, are 6 GHz (5–7 GHz, 10 GHz (9–10.8 GHz, and 15 GHz (14-15 GHz, expected for inclusion in next-generation wireless communications, that is, 5G. The design is simulated using Ansys Electromagnetic Suite 17 simulation software package. The simulated and the measured results are compared and analyzed which are generally in good agreement.

Shape and size effects on layered Ni/PZT/Ni composites magnetoelectric performance

Energy Technology Data Exchange (ETDEWEB)

Pan, D A; Zhang, S G; Qiao, L J [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Volinsky, Alex A [Department of Mechanical Engineering, University of South Florida, Tampa FL 33620 (United States)], E-mail: lqiao@ustb.edu.cn

2008-09-07

This paper presents the magnetoelectric (ME) effect in trilayered Ni/PZT/Ni composites which is related to their size and shape. The ME composites with the same interfacial areas but different geometrical shapes have different ME voltage coefficients. Longitudinal resonant modes in the rectangular and triangular trilayered ME composites were studied. One should choose optimized size, shape and working frequency of the ME composites in order to gain the maximum ME effect. This study plays a guiding role for trilayered ME composites design for real applications. (fast track communication)

Prominent extraaxial CSF space on cranial ultrasound in infants: correlation with neurodevelopmental outcome

Energy Technology Data Exchange (ETDEWEB)

Kim, Bo Kyung; Lee, Mun Hyang; Yoon, Hye Kyung; Jung, Kyung Jae; Park, Won Soon; Chang, Yun Sil; Kim, Chan Gyo [Sungkyunkwan Univ. School of Medicine, Seoul (Korea, Republic of)

1999-08-01

To determine the clinical significance of prominent extra-axial CSF space (EACSFS) in infants, as seen on cranial ultrasound. Between March 1996 and November 1997, all infants who had undergone head ultrasound at our institution and were found to have prominent EACSFS were evaluated. The width of the interhemispheric fissure was measured at three locations at the level of the frontal horn, body and atrium of the lateral ventricles. The depth of the CSF space over the convexity was also measured. The average of these measurements was calculated and each patient was assigned to one of three groups: mild, moderate, or marked. Ultrasound findings were evaluated for other associated abnormalities. Clinical neurodevelopment was evaluated by a pediatric neurologist, and ultrasound and neurodevelopmental findings were correlated. Prominent EACSFS was found in 153 patients, and neurodevelopmental evaluation up to a corrected age of 9 months was available in 133. One hundred and eight of 117 infants with normal neurodevelopment had no other associated abnormality(n=81), or abnormality associated only with grade I subependymal hemorrhage or cyst(n=27). Twelve of 16 infants with an abnormal neurodevelopmental outcome had major abnormalities including PVL, grade IV hemorrhage, and marked ventriculomegaly. Prominent EACSFS alone does not appear to be clinically significant. An abnormal neurodevelopmental outcome is associated with major abnormalities seen on ultrasound. Follow-up examination for prominent EACSFS is not indicated unless the associated abnormality requires further evaluations.

Prominent extraaxial CSF space on cranial ultrasound in infants: correlation with neurodevelopmental outcome

International Nuclear Information System (INIS)

Kim, Bo Kyung; Lee, Mun Hyang; Yoon, Hye Kyung; Jung, Kyung Jae; Park, Won Soon; Chang, Yun Sil; Kim, Chan Gyo

1999-01-01

To determine the clinical significance of prominent extra-axial CSF space (EACSFS) in infants, as seen on cranial ultrasound. Between March 1996 and November 1997, all infants who had undergone head ultrasound at our institution and were found to have prominent EACSFS were evaluated. The width of the interhemispheric fissure was measured at three locations at the level of the frontal horn, body and atrium of the lateral ventricles. The depth of the CSF space over the convexity was also measured. The average of these measurements was calculated and each patient was assigned to one of three groups: mild, moderate, or marked. Ultrasound findings were evaluated for other associated abnormalities. Clinical neurodevelopment was evaluated by a pediatric neurologist, and ultrasound and neurodevelopmental findings were correlated. Prominent EACSFS was found in 153 patients, and neurodevelopmental evaluation up to a corrected age of 9 months was available in 133. One hundred and eight of 117 infants with normal neurodevelopment had no other associated abnormality(n=81), or abnormality associated only with grade I subependymal hemorrhage or cyst(n=27). Twelve of 16 infants with an abnormal neurodevelopmental outcome had major abnormalities including PVL, grade IV hemorrhage, and marked ventriculomegaly. Prominent EACSFS alone does not appear to be clinically significant. An abnormal neurodevelopmental outcome is associated with major abnormalities seen on ultrasound. Follow-up examination for prominent EACSFS is not indicated unless the associated abnormality requires further evaluations

Active Radiative Thermal Switching with Graphene Plasmon Resonators.

Science.gov (United States)

Ilic, Ognjen; Thomas, Nathan H; Christensen, Thomas; Sherrott, Michelle C; Soljačić, Marin; Minnich, Austin J; Miller, Owen D; Atwater, Harry A

2018-03-27

We theoretically demonstrate a near-field radiative thermal switch based on thermally excited surface plasmons in graphene resonators. The high tunability of graphene enables substantial modulation of near-field radiative heat transfer, which, when combined with the use of resonant structures, overcomes the intrinsically broadband nature of thermal radiation. In canonical geometries, we use nonlinear optimization to show that stacked graphene sheets offer improved heat conductance contrast between "ON" and "OFF" switching states and that a >10× higher modulation is achieved between isolated graphene resonators than for parallel graphene sheets. In all cases, we find that carrier mobility is a crucial parameter for the performance of a radiative thermal switch. Furthermore, we derive shape-agnostic analytical approximations for the resonant heat transfer that provide general scaling laws and allow for direct comparison between different resonator geometries dominated by a single mode. The presented scheme is relevant for active thermal management and energy harvesting as well as probing excited-state dynamics at the nanoscale.

Study of isovector resonances with pion charge exchange

International Nuclear Information System (INIS)

Baer, H.W.; Bolton, R.; Bowman, J.D.

1982-01-01

Studies with the pion charge exchange reactions (π/sup +-/,π 0 ) at 164 MeV using the LAMPF π 0 spectrometer are yielding new results on the existence and systematic features of isovector resonances in nuclei. These experiments possess an unusually high signal/background ratio for isovector resonances of low-multipolarity. Results obtained to date are: (1) observation and angular disribution measurement of the giant dipole resonance in nuclei 12 C, 40 Ca, 90 Zr, and 120 Sn; and (2) observation and angular distribution measurements in the (π - ,π 0 ) reaction on 90 Zr and 120 Sn of large signals possessing the expected angular distribution shapes and magnitudes for the isovector monopole resonance. Excitation energies are near the hydrodynamical model values 170 A - /sup 1/3/ MeV. Differential cross sections are approximately 0.7 J 1 2 (qR) mb/sr. An overview of this experimental program, with emphasis on new results and how they correlate with existing knowledge on the isovector resonances, is presented

An extension of command shaping methods for controlling residual vibration using frequency sampling

Science.gov (United States)

Singer, Neil C.; Seering, Warren P.

1992-01-01

The authors present an extension to the impulse shaping technique for commanding machines to move with reduced residual vibration. The extension, called frequency sampling, is a method for generating constraints that are used to obtain shaping sequences which minimize residual vibration in systems such as robots whose resonant frequencies change during motion. The authors present a review of impulse shaping methods, a development of the proposed extension, and a comparison of results of tests conducted on a simple model of the space shuttle robot arm. Frequency shaping provides a method for minimizing the impulse sequence duration required to give the desired insensitivity.

High-Q, in-plane modes of nanomechanical resonators operated in air

Science.gov (United States)

Waggoner, Philip S.; Tan, Christine P.; Bellan, Leon; Craighead, Harold G.

2009-05-01

Nanomechanical resonators have traditionally been limited to use in vacuum due to low quality factors that come as a result of viscous damping effects in air or liquid. We have fabricated arrays of 90 nm thick trampoline-shaped resonators, studied their resonant frequency spectrum as a function of pressure, and found that some high frequency modes exhibit quality factors over 2000 at atmospheric pressure. We have excited the in-plane resonances of these devices, verified their identities both experimentally and with finite element modeling, and demonstrated their advantageous characteristics for ambient sensing. Even after deposition of a relatively thick polymer layer, the in-plane resonant modes still boast quality factors on the order of 2000. These results show promise for the use of nanomechanical resonant sensors in real-time atmospheric sensing applications.

Three-stub quarter wave superconducting resonator design

Directory of Open Access Journals (Sweden)

N. R. Lobanov

2006-11-01

Full Text Available This paper describes a concept for superconducting resonators for the acceleration of ions in the velocity range β=v/c=0.015–0.04. Such a resonator operates in λ/4 mode with three loading elements and so can be thought of as a triple quarter wave resonator (3-QWR providing 4 accelerating gaps. The use of a column to support the three stubs provides a benefit beyond those of the two-stub design (2-QWR. In the 3-QWR, the rf mirror currents in the walls surrounding the stubs need only travel through 45° instead of the 90° in the 2-QWR thus further reducing the current in the demountable joints. As in the 2-QWR, the shape of the column allows control of the frequency splitting between the accelerating and other modes. The copper structure is designed to be coated by a thin superconducting film of niobium or lead for operation at 4.3 K. The particular device reported here operates at 150 MHz with an optimum β of 0.04. Its outer cylinder is the same size and shape as for the 2-QWR structure reported previously, in order to minimize construction and cryostat costs. A simple transmission line model is presented and the results of microwave studio and other numerical analyses are discussed. The 3-QWR resonators are appropriate for the upgrade of the low-velocity sections of the ANU Heavy Ion Accelerator Facility and other heavy ion accelerator boosters.

ENDOR with band-selective shaped inversion pulses

Science.gov (United States)

Tait, Claudia E.; Stoll, Stefan

2017-04-01

Electron Nuclear DOuble Resonance (ENDOR) is based on the measurement of nuclear transition frequencies through detection of changes in the polarization of electron transitions. In Davies ENDOR, the initial polarization is generated by a selective microwave inversion pulse. The rectangular inversion pulses typically used are characterized by a relatively low selectivity, with full inversion achieved only for a limited number of spin packets with small resonance offsets. With the introduction of pulse shaping to EPR, the rectangular inversion pulses can be replaced with shaped pulses with increased selectivity. Band-selective inversion pulses are characterized by almost rectangular inversion profiles, leading to full inversion for spin packets with resonance offsets within the pulse excitation bandwidth and leaving spin packets outside the excitation bandwidth largely unaffected. Here, we explore the consequences of using different band-selective amplitude-modulated pulses designed for NMR as the inversion pulse in ENDOR. We find an increased sensitivity for small hyperfine couplings compared to rectangular pulses of the same bandwidth. In echo-detected Davies-type ENDOR, finite Fourier series inversion pulses combine the advantages of increased absolute ENDOR sensitivity of short rectangular inversion pulses and increased sensitivity for small hyperfine couplings of long rectangular inversion pulses. The use of pulses with an almost rectangular frequency-domain profile also allows for increased control of the hyperfine contrast selectivity. At X-band, acquisition of echo transients as a function of radiofrequency and appropriate selection of integration windows during data processing allows efficient separation of contributions from weakly and strongly coupled nuclei in overlapping ENDOR spectra within a single experiment.

Solar Prominences Embedded in Flux Ropes: Morphological Features and Dynamics from 3D MHD Simulations

Science.gov (United States)

Terradas, J.; Soler, R.; Luna, M.; Oliver, R.; Ballester, J. L.; Wright, A. N.

2016-04-01

The temporal evolution of a solar prominence inserted in a three-dimensional magnetic flux rope is investigated numerically. Using the model of Titov & Démoulin under the regime of weak twist, the cold and dense prominence counteracts gravity by modifying the initially force-free magnetic configuration. In some cases a quasi-stationary situation is achieved after the relaxation phase, characterized by the excitation of standing vertical oscillations. These oscillations show a strong attenuation with time produced by the mechanism of continuum damping due to the inhomogeneous transition between the prominence and solar corona. The characteristic period of the vertical oscillations does not depend strongly on the twist of the flux rope. Nonlinearity is responsible for triggering the Kelvin-Helmholtz instability associated with the vertical oscillations and that eventually produces horizontal structures. Contrary to other configurations in which the longitudinal axis of the prominence is permeated by a perpendicular magnetic field, like in unsheared arcades, the orientation of the prominence along the flux rope axis prevents the development of Rayleigh-Taylor instabilities and therefore the appearance of vertical structuring along this axis.

HTS microstrip disk resonator with an upper dielectric layer for 4GHz

International Nuclear Information System (INIS)

Yamanaka, Kazunori; Kai, Manabu; Akasegawa, Akihiko; Nakanishi, Teru

2006-01-01

We propose HTS microstrip disk resonator with an upper dielectric layer as a candidate resonator structure of HTS compact power filter for 4GHz band. The electromagnetic simulations on the upper dielectric layer examined the current distributions of the HTS resonators that had TM 11 mode resonance of about 4 GHz. By the simulations, it is evaluated that of the maximum current density near the end portion of the disk-shape pattern of the resonator with the thick upper-layered structure decreases by roughly 30-50 percent, as compared with that of the resonator without it. Then, we designed and fabricated the resonator samples with and without the upper dielectrics. The RF power measurement results indicated that the upper dielectric layer leads to an increase in handling power

Automatic generation of 3D statistical shape models with optimal landmark distributions.

Science.gov (United States)

Heimann, T; Wolf, I; Meinzer, H-P

2007-01-01

To point out the problem of non-uniform landmark placement in statistical shape modeling, to present an improved method for generating landmarks in the 3D case and to propose an unbiased evaluation metric to determine model quality. Our approach minimizes a cost function based on the minimum description length (MDL) of the shape model to optimize landmark correspondences over the training set. In addition to the standard technique, we employ an extended remeshing method to change the landmark distribution without losing correspondences, thus ensuring a uniform distribution over all training samples. To break the dependency of the established evaluation measures generalization and specificity from the landmark distribution, we change the internal metric from landmark distance to volumetric overlap. Redistributing landmarks to an equally spaced distribution during the model construction phase improves the quality of the resulting models significantly if the shapes feature prominent bulges or other complex geometry. The distribution of landmarks on the training shapes is -- beyond the correspondence issue -- a crucial point in model construction.

Integral force feedback control with input shaping: Application to piezo-based scanning systems in ECDLs

Science.gov (United States)

Zhang, Meng; Liu, Zhigang; Zhu, Yu; Bu, Mingfan; Hong, Jun

2017-07-01

In this paper, a hybrid control system is developed by integrating the closed-loop force feedback and input shaping method to overcome the problem of the hysteresis and dynamic behavior in piezo-based scanning systems and increase the scanning speed of tunable external cavity diode lasers. The flexible hinge and piezoelectric actuators are analyzed, and a dynamic model of the scanning systems is established. A force sensor and an integral controller are utilized in integral force feedback (IFF) to directly augment the damping of the piezoelectric scanning systems. Hysteresis has been effectively eliminated, but the mechanical resonance is still evident. Noticeable residual vibration occurred after the inflection points and then gradually disappeared. For the further control of mechanical resonance, based on the theory of minimum-acceleration trajectory planning, the time-domain input shaping method was developed. The turning sections of a scanning trajectory are replaced by smooth curves, while the linear sections are retained. The IFF method is combined with the input shaping method to control the non-linearity and mechanical resonance in high-speed piezo-based scanning systems. Experiments are conducted, and the results demonstrate the effectiveness of the proposed control approach.

Integral force feedback control with input shaping: Application to piezo-based scanning systems in ECDLs.

Science.gov (United States)

Zhang, Meng; Liu, Zhigang; Zhu, Yu; Bu, Mingfan; Hong, Jun

2017-07-01

In this paper, a hybrid control system is developed by integrating the closed-loop force feedback and input shaping method to overcome the problem of the hysteresis and dynamic behavior in piezo-based scanning systems and increase the scanning speed of tunable external cavity diode lasers. The flexible hinge and piezoelectric actuators are analyzed, and a dynamic model of the scanning systems is established. A force sensor and an integral controller are utilized in integral force feedback (IFF) to directly augment the damping of the piezoelectric scanning systems. Hysteresis has been effectively eliminated, but the mechanical resonance is still evident. Noticeable residual vibration occurred after the inflection points and then gradually disappeared. For the further control of mechanical resonance, based on the theory of minimum-acceleration trajectory planning, the time-domain input shaping method was developed. The turning sections of a scanning trajectory are replaced by smooth curves, while the linear sections are retained. The IFF method is combined with the input shaping method to control the non-linearity and mechanical resonance in high-speed piezo-based scanning systems. Experiments are conducted, and the results demonstrate the effectiveness of the proposed control approach.

Light squeezing through arbitrarily shaped plasmonic channels and sharp bends

International Nuclear Information System (INIS)

Alu, Andrea; Engheta, Nader

2008-01-01

We propose a mechanism for optical energy squeezing and anomalous light transmission through arbitrarily-shaped plasmonic ultranarrow channels and bends connecting two larger plasmonic metal-insulator-metal waveguides. It is shown how a proper design of subwavelength optical channels at cutoff, patterned by plasmonic implants and connecting larger plasmonic waveguides, may allow enhanced resonant transmission inspired by the anomalous properties of epsilon-near-zero (ENZ) metamaterials. The resonant transmission is shown to be only weakly dependent on the channel length and its specific geometry, such as possible presence of abruptions and bends

Authentication Sensing System Using Resonance Evaluation Spectroscopy (ASSURES)

Science.gov (United States)

Trolinger, James D.; Dioumaev, Andrei K.; Lal, Amit K.; Dimas, Dave

2017-08-01

This paper describes an ongoing instrument development project to distinguish genuine manufactured components from counterfeit components; we call the instrument ASSURES (Authentication Sensing System Using Resonance Evaluation Spectroscopy). The system combines Laser Doppler Vibrometry with acoustical resonance spectroscopy, augmented with finite element analysis. Vibrational properties of components, such as resonant modes, damping, and spectral frequency response to various forcing functions depend strongly upon the mechanical properties of the material, including its size, shape, internal hardness, tensile strength, alloy/composite compositions, flaws, defects, and other internal material properties. Although acoustic resonant spectroscopy has seen limited application, the information rich signals in the vibrational spectra of objects provide a pathway to many new applications. Components with the same shape but made of different materials, different fatigue histories, damage, tampering, or heat treatment, will respond differently to high frequency stimulation. Laser Doppler Vibrometry offers high sensitivity and frequency bandwidth to measure the component's frequency spectrum, and overcomes many issues that limit conventional acoustical resonance spectroscopy, since the sensor laser beam can be aimed anywhere along the part as well as to multiple locations on a part in a non-contact way. ASSURES is especially promising for use in additive manufacturing technology by providing signatures as digital codes that are unique to specific objects and even to specific locations on objects. We believe that such signatures can be employed to address many important issues in the manufacturing industry. These include insuring the part meets the often very rigid specifications of the customer and being able to detect non-visible internal manufacturing defects or non-visible damage that has occurred after manufacturing.

Implementation of intra-cavity beam shaping technique to enhance pump efficiency

CSIR Research Space (South Africa)

Litvin, IA

2012-02-01

Full Text Available In this work the author proposes an implementation of a new intra-cavity beam shaping technique to vary the intensity distribution of the fundamental mode in a resonator cavity while maintaining a constant intensity distribution at the output...

Tuning the magnetic properties of GaAs:Mn/MnAs hybrids via the MnAs cluster shape

International Nuclear Information System (INIS)

Nidda, H-A Krug von; Kurz, T; Loidl, A; Hartmann, Th; Klar, P J; Heimbrodt, W; Lampalzer, M; Volz, K; Stolz, W

2006-01-01

We report a systematic study of ferromagnetic resonance in granular GaAs:Mn/MnAs hybrids grown on GaAs(001) substrates by metal-organic vapour-phase epitaxy. The ferromagnetic resonance of the MnAs clusters can be resolved at all temperatures below T c . An additional broad absorption is observed below 60 K and is ascribed to localized charge carriers of the GaAs:Mn matrix. The anisotropy of the MnAs ferromagnetic resonance field originates from the magneto-crystalline field and demagnetization effects of the ferromagnetic MnAs clusters embedded in the GaAs:Mn matrix. Its temperature dependence basically scales with magnetization. Comparison of the observed angular dependence of the resonance field with model calculations yields the preferential orientation and shape of the clusters formed in hybrid layers of different thickness (150-1000 nm) grown otherwise at the same growth conditions. The hexagonal axes of the MnAs clusters are oriented along the four cubic GaAs space diagonals. Thin layers contain lens-shaped MnAs clusters close to the surface, whereas thick layers also contain spherical clusters in the bulk of the layer. The magnetic properties of the hexagonal MnAs clusters can be tuned by a controlled variation of the cluster shape

Prominence modelling: from observed emission measures to temperature profiles

Czech Academy of Sciences Publication Activity Database

Anzer, U.; Heinzel, Petr

2008-01-01

Roč. 480, č. 2 (2008), s. 537-542 ISSN 0004-6361 Grant - others:EU(XE) ESA-PECS Project No. 98030 Institutional research plan: CEZ:AV0Z10030501 Keywords : Sun * prominences * transition region Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.153, year: 2008

Word-level prominence in Persian: An Experimental Study.

Science.gov (United States)

Sadeghi, Vahid

2017-12-01

Previous literature on the phonetics of stress in Persian has reported that fundamental frequency is the only reliable acoustic correlate of stress, and that stressed and unstressed syllables are not differentiated from each other in the absence of accentuation. In this study, the effects of lexical stress on duration, overall intensity and spectral tilt were examined in Persian both in the accented and unaccented conditions. Results showed that syllable duration is consistently affected by stress in Persian in both the accented and unaccented conditions across all vowel types. Unlike duration, the results for overall intensity and spectral tilt were significant only in the accented condition, suggesting that measures of intensity are not a correlate of stress in Persian but they are mainly caused by the presence of a pitch movement. The findings are phonologically interpreted as suggesting that word-level prominence in Persian is typologically similar to 'stress accent' languages, in which multiple phonetic cues are used to signal the prominence contrast in the accented condition, and stressed and unstressed syllables are different from each other even when the word is not pitch-accented.

Resonant Column Tests and Nonlinear Elasticity in Simulated Rocks

Science.gov (United States)

Sebastian, Resmi; Sitharam, T. G.

2018-01-01

Rocks are generally regarded as linearly elastic even though the manifestations of nonlinearity are prominent. The variations of elastic constants with varying strain levels and stress conditions, disagreement between static and dynamic moduli, etc., are some of the examples of nonlinear elasticity in rocks. The grain-to-grain contact, presence of pores and joints along with other compliant features induce the nonlinear behavior in rocks. The nonlinear elastic behavior of rocks is demonstrated through resonant column tests and numerical simulations in this paper. Resonant column tests on intact and jointed gypsum samples across varying strain levels have been performed in laboratory and using numerical simulations. The paper shows the application of resonant column apparatus to obtain the wave velocities of stiff samples at various strain levels under long wavelength condition, after performing checks and incorporating corrections to the obtained resonant frequencies. The numerical simulation and validation of the resonant column tests using distinct element method are presented. The stiffness reductions of testing samples under torsional and flexural vibrations with increasing strain levels have been analyzed. The nonlinear elastic behavior of rocks is reflected in the results, which is enhanced by the presence of joints. The significance of joint orientation and influence of joint spacing during wave propagation have also been assessed and presented using the numerical simulations. It has been found that rock joints also exhibit nonlinear behavior within the elastic limit.

Tic Tac TOE: Effects of Predictability and Importance on Acoustic Prominence in Language Production

Science.gov (United States)

Watson, Duane G.; Arnold, Jennifer E.; Tanenhaus, Michael K.

2008-01-01

Importance and predictability each have been argued to contribute to acoustic prominence. To investigate whether these factors are independent or two aspects of the same phenomenon, naive participants played a verbal variant of Tic Tac Toe. Both importance and predictability contributed independently to the acoustic prominence of a word, but in…

Electron densities in quiescent prominences derived from eclipse observations

Czech Academy of Sciences Publication Activity Database

Jejčič, S.; Heinzel, Petr

2009-01-01

Roč. 254, č. 1 (2009), s. 89-100 ISSN 0038-0938 Grant - others:EU(XE) ESA-PECS project No. 98030 Institutional research plan: CEZ:AV0Z10030501 Keywords : prominences quiescent * eclipse observations * visible spectrum Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.628, year: 2009

Detailed analysis of the resonant backscattering spectrum for deeply penetrating protons in carbon

International Nuclear Information System (INIS)

Tosaki, Mitsuo; Ito, Shin; Maeda, Nobuhiro

2000-01-01

In order to study the spectral response in Rutherford backscattering spectroscopy (RBS) for deeply penetrating ions in matter, the resonant backscattering spectra for 5.05-, 5.5- and 6.0-MeV proton incidence on solid carbon material have been measured at a scattering angle of 179.2 deg. (in lab.). Prominent peaks resulting from the sharp 4.8-MeV resonance in 12 C(p,p) 12 C nuclear elastic scattering are observed, even for a penetration depth of 79 μm. Detailed numerical calculations based on an algorithm of straightforward step-by-step evaluation have been made to simulate the observed spectra. The algorithm enables one to rigorously treat both the effect of sharp resonance structure and that of energy-dependent energy loss. Calculations with the SIMNRA code are also made. Through comparison of these calculations with the measured results, some conclusions on the two effects above are presented. In addition, it is demonstrated that the peak profile due to a sharp resonance is very sensitive to the degree of energy straggling

Tunable superconducting resonators with integrated trap structures for coupling with ultracold atomic gases

Energy Technology Data Exchange (ETDEWEB)

Ferdinand, Benedikt; Wiedmaier, Dominik; Koelle, Dieter; Kleiner, Reinhold [Physikalisches Institut and Center for Quantum Science in LISA+, Universitaet Tuebingen (Germany); Bothner, Daniel [Physikalisches Institut and Center for Quantum Science in LISA+, Universitaet Tuebingen (Germany); Kavli Institute of Nanoscience, Delft University of Technology, Delft (Netherlands)

2016-07-01

We intend to investigate a hybrid quantum system where ultracold atomic gases play the role of a long-living quantum memory, coupled to a superconducting qubit via a coplanar waveguide transmission line resonator. As a first step we developed a resonator chip containing a Z-shaped trapping wire for the atom trap. In order to suppress parasitic resonances due to stray capacitances, and to achieve good ground connection we use hybrid superconductor - normal conductor chips. As an additional degree of freedom we add a ferroelectric capacitor making the resonators voltage-tunable. We furthermore show theoretical results on the expected coupling strength between resonator and atomic cloud.

Cavity-enhanced resonant tunneling photodetector at telecommunication wavelengths

International Nuclear Information System (INIS)

Pfenning, Andreas; Hartmann, Fabian; Langer, Fabian; Höfling, Sven; Kamp, Martin; Worschech, Lukas

2014-01-01

An AlGaAs/GaAs double barrier resonant tunneling diode (RTD) with a nearby lattice-matched GaInNAs absorption layer was integrated into an optical cavity consisting of five and seven GaAs/AlAs layers to demonstrate cavity enhanced photodetection at the telecommunication wavelength 1.3 μm. The samples were grown by molecular beam epitaxy and RTD-mesas with ring-shaped contacts were fabricated. Electrical and optical properties were investigated at room temperature. The detector shows maximum photocurrent for the optical resonance at a wavelength of 1.29 μm. At resonance a high sensitivity of 3.1×10 4 A/W and a response up to several pA per photon at room temperature were found

SOLAR PROMINENCES EMBEDDED IN FLUX ROPES: MORPHOLOGICAL FEATURES AND DYNAMICS FROM 3D MHD SIMULATIONS

Energy Technology Data Exchange (ETDEWEB)

Terradas, J.; Soler, R.; Oliver, R.; Ballester, J. L. [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Luna, M. [Instituto de Astrofsíca de Canarias, E-38205 La Laguna, Tenerife (Spain); Wright, A. N., E-mail: jaume.terradas@uib.es [School of Mathematics and Statistics, University of St Andrews, St Andrews, KY16 9SS (United Kingdom)

2016-04-01

The temporal evolution of a solar prominence inserted in a three-dimensional magnetic flux rope is investigated numerically. Using the model of Titov and Démoulin under the regime of weak twist, the cold and dense prominence counteracts gravity by modifying the initially force-free magnetic configuration. In some cases a quasi-stationary situation is achieved after the relaxation phase, characterized by the excitation of standing vertical oscillations. These oscillations show a strong attenuation with time produced by the mechanism of continuum damping due to the inhomogeneous transition between the prominence and solar corona. The characteristic period of the vertical oscillations does not depend strongly on the twist of the flux rope. Nonlinearity is responsible for triggering the Kelvin–Helmholtz instability associated with the vertical oscillations and that eventually produces horizontal structures. Contrary to other configurations in which the longitudinal axis of the prominence is permeated by a perpendicular magnetic field, like in unsheared arcades, the orientation of the prominence along the flux rope axis prevents the development of Rayleigh–Taylor instabilities and therefore the appearance of vertical structuring along this axis.

Memory for shape reactivates the lateral occipital complex.

Science.gov (United States)

Karanian, Jessica M; Slotnick, Scott D

2015-04-07

Memory is thought to be a constructive process in which the cortical regions associated with processing event features are reactivated during retrieval. Although there is evidence for non-detailed cortical reactivation during retrieval (e.g., memory for visual or auditory information reactivates the visual or auditory processing regions, respectively), there is limited evidence that memory can reactivate cortical regions associated with processing detailed, feature-specific information. Such evidence is critical to our understanding of the mechanisms of episodic retrieval. The present functional magnetic resonance imaging (fMRI) study assessed whether the lateral occipital complex (LOC), a region that preferentially processes shape, is associated with retrieval of shape information. During encoding, participants were presented with colored abstract shapes that were either intact or scrambled. During retrieval, colored disks were presented and participants indicated whether the corresponding shape was previously "intact" or "scrambled". To assess whether conscious retrieval of intact shapes reactivated LOC, we conducted a conjunction of shape perception/encoding and accurate versus inaccurate retrieval of intact shapes, which produced many activations in LOC. To determine whether activity in LOC was specific to intact shapes, we conducted a conjunction of shape perception/encoding and intact versus scrambled shapes, which also produced many activations in LOC. Furthermore, memory for intact shapes in each hemifield produced contralateral activity in LOC (e.g., memory for left visual field intact shapes activated right LOC), which reflects the specific reinstatement of perception/encoding activity. The present results extend previous feature-specific memory reactivation evidence and support the view that memory is a constructive process. Copyright © 2015 Elsevier B.V. All rights reserved.

Microelectromechanical resonator based digital logic elements

KAUST Repository

Hafiz, Md Abdullah Al

2016-10-20

Micro/nano-electromechanical resonator based mechanical computing has recently attracted significant attention. However, its full realization has been hindered by the difficulty in realizing complex combinational logics, in which the logic function is constructed by cascading multiple smaller logic blocks. In this work we report an alternative approach for implementation of digital logic core elements, multiplexer and demultiplexer, which can be used to realize combinational logic circuits by suitable concatenation. Toward this, shallow arch shaped microresonators are electrically connected and their resonance frequencies are tuned based on an electrothermal frequency modulation scheme. This study demonstrates that by reconfiguring the same basic building block, the arch microresonator, complex logic circuits can be realized.

Microelectromechanical resonator based digital logic elements

KAUST Repository

Hafiz, Md Abdullah Al; Kosuru, Lakshmoji; Younis, Mohammad I.; Fariborzi, Hossein

2016-01-01

Micro/nano-electromechanical resonator based mechanical computing has recently attracted significant attention. However, its full realization has been hindered by the difficulty in realizing complex combinational logics, in which the logic function is constructed by cascading multiple smaller logic blocks. In this work we report an alternative approach for implementation of digital logic core elements, multiplexer and demultiplexer, which can be used to realize combinational logic circuits by suitable concatenation. Toward this, shallow arch shaped microresonators are electrically connected and their resonance frequencies are tuned based on an electrothermal frequency modulation scheme. This study demonstrates that by reconfiguring the same basic building block, the arch microresonator, complex logic circuits can be realized.

Magnetic field re-arrangement after prominence eruption

International Nuclear Information System (INIS)

Kopp, R.A.; Poletto, G.

1986-01-01

It has long been known that magnetic reconnection plays a fundamental role in a variety of solar events. Although mainly invoked in flare problems, large-scale loops interconnecting active regions, evolving coronal hole boundaries, the solar magnetic cycle itself, provide different evidence of phenomena which involve magnetic reconnection. A further example might be given by the magnetic field rearrangement which occurs after the eruption of a prominence. Since most often a prominence reforms after its disappearance and may be observed at about the same position it occupied before erupting, the magnetic field has to undergo a temporary disruption to relax back, via reconnection, to a configuration similar to the previous one. The above sequence of events is best observable in the case of two-ribbon (2-R) flares but most probably is associated with all filament eruptions. Even if the explanation of the magnetic field rearrangement after 2-R flares in terms of reconnection is generally accepted, the lack of a three-dimensional model capable of describing the field reconfiguration, has prevented, up to now, a thorough analysis of its topology as traced by Hα/x-ray loops. The purpose of the present work is to present a numerical technique which enables one to predict and visualize the reconnected configuration, at any time t, and therefore allows one to make a significant comparison of observations and model predictions throughout the whole process. 5 refs., 3 figs

Electromagnetically induced reflectance and Fano resonance in one dimensional superconducting photonic crystal

Science.gov (United States)

Athe, Pratik; Srivastava, Sanjay; Thapa, Khem B.

2018-04-01

In the present work, we demonstrate the generation of optical Fano resonance and electromagnetically induced reflectance (EIR) in one-dimensional superconducting photonic crystal (1D SPC) by numerical simulation using transfer matrix method as analysis tool. We investigated the optical response of 1D SPC structure consisting of alternate layer of two different superconductors and observed that the optical spectra of this structure exhibit two narrow reflectance peaks with zero reflectivity of sidebands. Further, we added a dielectric cap layer to this 1D SPC structure and found that addition of dielectric cap layer transforms the line shape of sidebands around the narrow reflectance peaks which leads to the formation of Fano resonance and EIR line shape in reflectance spectra. We also studied the effects of the number of periods, refractive index and thickness of dielectric cap layer on the lineshape of EIR and Fano resonances. It was observed that the amplitude of peak reflectance of EIR achieves 100% reflectance by increasing the number of periods.

Broadband reflective multi-polarization converter based on single-layer double-L-shaped metasurface

Science.gov (United States)

Mao, Chenyang; Yang, Yang; He, Xiaoxiang; Zheng, Jingming; Zhou, Chun

2017-12-01

In this paper, a broadband reflective multi-polarization converter based on single-layer double-L-shaped metasurface is proposed. The proposed metasurface can effectively convert linear-polarized (TE/TM) incident wave into the reflected wave with three different polarizations within the frequency bands of 5.5-22.75 GHz. Based on the electric and magnetic resonant features of the double-L-shaped structure, the proposed metasurface can convert linearly polarized waves into cross-polarized waves at three resonant frequency bands. Furthermore, the incident linearly polarized waves can be effectively converted into left/right handed circular-polarized (LHCP and RHCP) waves at other four non-resonance frequency bands. Thus, the proposed metasurface can be regarded as a seven-band multi-polarization converter. The prototype of the proposed polarization converter is analyzed and measured. Both simulated and measured results show the 3-dB axis ratio bandwidth of circular polarization bands and the high polarization conversion efficiency of cross-polarization bands when the incident wave changes from 0° to 30° at both TE and TM modes.

[Surface coils for magnetic-resonance images].

Science.gov (United States)

Rodríguez-González, Alfredo Odón; Amador-Baheza, Ricardo; Rojas-Jasso, Rafael; Barrios-Alvarez, Fernando Alejandro

2005-01-01

Since the introduction of magnetic resonance imaging in Mexico, the development of this important medical imaging technology has been almost non-existing in our country. The very first surface coil prototypes for clinical applications in magnetic resonance imaging has been developed at the Center of Research in Medical Imaging and Instrumentation of the Universidad Autónoma Metropolitana Iztapalapa (Metropolitan Autonomous University, Campus Iztapalapa). Two surface coil prototypes were built: a) a circular-shaped coil and b) a square-shaped coil for multiple regions of the body, such as heart, brain, knee, hands, and ankles. These coils were tested on the 1.5T imager of the ABC Hospital-Tacubaya, located in Mexico City. Brain images of healthy volunteers were obtained in different orientations: sagittal, coronal, and axial. Since images showed a good-enough clinical quality for diagnosis, it is fair to say that these coil prototypes can be used in the clinical environment, and with small modifications, they can be made compatible with almost any commercial scanner. This type of development can offer new alternatives for further collaboration between the research centers and the radiology community, in the search of new applications and developments of this imaging technique.

Fano resonance in anodic aluminum oxide based photonic crystals.

Science.gov (United States)

Shang, Guo Liang; Fei, Guang Tao; Zhang, Yao; Yan, Peng; Xu, Shao Hui; Ouyang, Hao Miao; Zhang, Li De

2014-01-08

Anodic aluminum oxide based photonic crystals with periodic porous structure have been prepared using voltage compensation method. The as-prepared sample showed an ultra-narrow photonic bandgap. Asymmetric line-shape profiles of the photonic bandgaps have been observed, which is attributed to Fano resonance between the photonic bandgap state of photonic crystal and continuum scattering state of porous structure. And the exhibited Fano resonance shows more clearly when the sample is saturated ethanol gas than air-filled. Further theoretical analysis by transfer matrix method verified these results. These findings provide a better understanding on the nature of photonic bandgaps of photonic crystals made up of porous materials, in which the porous structures not only exist as layers of effective-refractive-index material providing Bragg scattering, but also provide a continuum light scattering state to interact with Bragg scattering state to show an asymmetric line-shape profile.

Resonant ultrasound spectroscopy and non-destructive testing

Science.gov (United States)

Migliori, A.; Darling, T. W.

The use of mechanical resonances to test properties of materials is perhaps older than the industrial revolution. Early documented cases of British railroad engineers tapping the wheels of a train and using the sound to detect cracks perhaps mark the first real use of resonances to test the integrity of high-performance alloys. Attempts were made in the following years to understand the resonances of solids mathematically, based on the shape and composition. But Nobel Laureate Lord Rayleigh best summarized the state of affairs in 1894, stating 'the problem has, for the most part, resisted attack'. More recently, modern computers and electronics have enabled Anderson and co-workers with their work on minerals, and our work at Los Alamos on new materials and manufactured components to advance the use of resonances to a precision non-destructive testing tool that makes anisotropic modulus measurements, defect detection and geometry error detection routine. The result is that resonances can achieve the highest absolute accuracy for any dynamic modulus measurement technique, can be used on the smallest samples, and can also enable detection of errors in certain classes of precision manufactured components faster and more accurately than any other technique.

Light Scattering by a Dielectric Sphere: Perspectives on the Mie Resonances

Directory of Open Access Journals (Sweden)

Dimitrios Tzarouchis

2018-01-01

backscattering between the first magnetic and electric dipole contributions of a dielectric sphere. The presented results address several prominent functional features, aiming at readers with either theoretical or applied interest for the scattering aspects of a resonant sphere.

Evaluation of stable tungsten isotopes in the resolved resonance region

Directory of Open Access Journals (Sweden)

Schillebeeckx P.

2013-03-01

Full Text Available In the last decade benchmark experiments and simulations, together with newly obtained neutron cross section data, have pointed out deficiencies in evaluated data files of W isotopes. The role of W as a fundamental structural material in different nuclear applications fully justifies a new evaluation of 182, 183, 184, 186W neutron resonance parameters. In this regard transmission and capture cross section measurements on natural and enriched tungsten samples were performed at the GELINA facility of the EC-JRC-IRMM. A resonance parameter file used as input in the resonance shape analysis was prepared based on the available literature and adjusted in first instance to transmission data.

Vaginal orgasm is more prevalent among women with a prominent tubercle of the upper lip.

Science.gov (United States)

Brody, Stuart; Costa, Rui Miguel

2011-10-01

Recent studies have uncovered multiple markers of vaginal orgasm history (unblocked pelvic movement during walking, less use of immature psychological defense mechanisms, greater urethrovaginal space). Other markers (perhaps of prenatal origin) even without obvious mechanistic roles in vaginal orgasm might exist, and a clinical observation led to the novel hypothesis that a prominent tubercle of the upper lip is such a marker. To examine the hypothesis that a prominent tubercle of the upper lip is associated specifically with greater likelihood of experiencing vaginal orgasm (orgasm elicited by penile-vaginal intercourse [PVI] without concurrent masturbation). Women (N = 258, predominantly Scottish) completed an online survey reporting their frequencies of various sexual activities and corresponding orgasms, age, and the prominence of the tubercle of their upper lip. Social desirability response bias was also assessed. Multivariate associations of lip tubercle prominence with vaginal orgasm (ever and past month consistency) and with orgasm by other means. RESULTS.: A prominent and sharply raised lip tubercle was associated with greater odds (odds ratio = 12.3) of ever having a vaginal orgasm, and also with greater past month vaginal orgasm consistency (an effect driven by the women who never had a vaginal orgasm), than less prominent lip tubercle categories. Lip tubercle was not associated with social desirability responding, or with orgasm triggered by masturbation during PVI, solitary or partner clitoral or vaginal masturbation, vibrator, or cunnilingus. The results are discussed in light of the unique nature of vaginal orgasm and the possibility of prenatal developmental influences. © 2011 International Society for Sexual Medicine.

Determination of giant resonance strengths

International Nuclear Information System (INIS)

Serr, F.E.

1983-01-01

Using theoretical strength functions to describe the different giant resonances expected at excitation energies of the order of (60-85)/Asup(1/3) MeV, we calculate the double differential cross sections d 2 sigma/dΩ dE associated with the reactions 208 Pb(α, α') and 90 Zr(α, α') (Esub(α) = 152 MeV). The angular distributions for the giant quadrupole and giant monopole resonances obtained from fits to these spectra, making simple, commonly used assumptions for the peak shapes and background, are compared to the original angular distributions. The differences between them are an indication of some of the uncertainties affecting the giant resonance strengths extracted from hadron inelastic scattering data. Fits to limited angular regions lead to errors of up to 50% in the value of the energy-weighted sum rule, depending on the angles examined. While it seems possible to extract the correct EWSR for the GMR by carrying out the analyses at 0 0 , no single privileged angle seems to exist in the case of the GQR. (orig.)

Prominent cerebral veins on susceptibility-weighted imaging (SWI) in pulmonary embolism

Energy Technology Data Exchange (ETDEWEB)

Oeztoprak, Bilge [Cumhuriyet University School of Medicine, Department of Radiology, Sivas (Turkey)

2017-07-15

Clinical applications of susceptibility-weighted imaging (SWI) are increasing steadily. The aim of this study is to investigate the appearance of cerebral veins on SWI, which is very sensitive to the deoxyhaemoglobin level in vessels, in pulmonary embolism (PE). The cranial SWI images of 19 patients with PE and 22 controls from September 2013 through March 2016 were retrospectively examined for the presence of prominent cerebral veins. MRI findings were correlated with blood oxygen levels. 12 of 19 patients with PE had hypoxemia and SWI images of 11 of these hypoxemic patients depicted prominent cerebral veins in the form of increased number, diameter, and elongation. The mean PaO{sub 2} and SaO{sub 2} in these patients were 48.5 ± 9.1 mmHg and 75.2 ± 8.0 %, respectively. There was a significant correlation between the presence of prominent veins on SWI and hypoxemia (p < 0.05). Of the 7 patients with normal blood oxygen pressure and saturation, 1 also showed an augmented appearance of cerebral veins on SWI. In the presence of neurological symptoms suggestive of an intracranial pathology in patients with PE, a SWI added to the conventional MRI sequences may predict hypoxemia and exclude other intracranial pathologies. (orig.)

Resonant frequency function of thickness-shear vibrations of rectangular crystal plates.

Science.gov (United States)

Wang, Ji; Yang, Lijun; Pan, Qiaoqiao; Chao, Min-Chiang; Du, Jianke

2011-05-01

The resonant frequencies of thickness-shear vibrations of quartz crystal plates in rectangular and circular shapes are always required in the design and manufacturing of quartz crystal resonators. As the size of quartz crystal resonators shrinks, for rectangular plates we must consider effects of both length and width for the precise calculation of resonant frequency. Starting from the three-dimensional equations of wave propagation in finite crystal plates and the general expression of vibration modes, we obtained the relations between frequency and wavenumbers. By satisfying the major boundary conditions of the dominant thickness-shear mode, three wavenumber solutions are obtained and the frequency equation is constructed. It is shown the resonant frequency of thickness-shear mode is a second-order polynomial of aspect ratios. This conforms to known results in the simplest form and is applicable to further analytical and experimental studies of the frequency equation of quartz crystal resonators.

Perceptions of Social Responsibility of Prominent Animal Welfare Groups.

Science.gov (United States)

Widmar, Nicole J Olynk; Morgan, Carissa J; Croney, Candace C

2018-01-01

Nonhuman animal welfare is an increasingly important component of consumer expectations of corporate social responsibility (CSR). The extent to which prominent animal welfare or protection organizations may influence people's perceptions of food industry CSR may be related to an organization's perceived social responsibility. Data from an online survey of 300 U.S. residents were used to explore relationships between demographics/lifestyle choices and perceptions of prominent animal welfare organizations (using best-worst scaling methodology). Overall, the American Society for the Prevention of Cruelty to Animals was perceived to be the most socially responsible organization analyzed, followed by the Humane Society of the United States and the American Humane Association (AHA). Results suggest that the perceived social responsibility of animal protection organizations in this study was not strongly linked to personally (financially) supporting them, with 2 exceptions: the perceptions of People for the Ethical Treatment of Animals and AHA. Improved understanding of the perception of animal welfare or protection organizations can inform decision making by organizations interested in furthering animal welfare causes.

The EU and Climate Change Policy: Law, Politics and Prominence at Different Levels

Directory of Open Access Journals (Sweden)

Chad David Damro

2008-11-01

Full Text Available The European Union (EU is a prominent player in the politics of climate change, operating as an authoritative regional actor that influences policy-making at the national and international levels. The EU’s climate change policies are thus subjected to multiple pressures that arise from the domestic politics of its twenty-seven individual member states and the international politics of non-EU states with which it negotiates. Facing these multiple pressures, how and why could such a non-traditional actor develop into a prominent player at different levels of climate change policy-making? This article argues that the EU’s rise to prominence can be understood by tracking a number of historical-legal institutional developments at the domestic and international levels. The article also provides a preliminary investigation of the EU emissions trading scheme, a new institutional mechanism that illustrates the policy pressures arising from different levels.

Resonance magnetic x-ray scattering study of erbium

DEFF Research Database (Denmark)

Sanyal, M.K.; Gibbs, D.; Bohr, J.

1994-01-01

The magnetic phases of erbium have been studied by resonance x-ray-scattering techniques. When the incident x-ray energy is tuned near the L(III) absorption edge, large resonant enhancements of the magnetic scattering are observed above 18 K. We have measured the energy and polarization dependence...... of this magnetic scattering and analyzed it using a simple model based on electric dipole and quadrupole transitions among atomic orbitals. The line shapes can be fitted to a magnetic structure combining both c-axis-modulated and basal-plane components. Below 18 K, we have observed unusual behavior of the magnetic...

Characterization and Design of Zeolite Catalysts Solid Acidity, Shape Selectivity and Loading Properties

CERN Document Server

Niwa, Miki; Okumura, Kazu

2010-01-01

Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents. Zeolite-based catalysts are used by industrial chemical companies in the interconversion of hydrocarbons and the alkylation of aromatic compounds. The current book deals with the characterization of specific properties of Zeolites and calculations for the design of catalysts. Measurements and utilization of solid acidity, shape selectivity, and loading properties, that are three prominent properties of a Zeolite catalyst, are treated in detail. These features concern chemical vapor deposition of silica, shape selectivity, loading properties, solid activity, Brønsted or Lewis character, ammonia temperature programmed desorption, control of the pore-opening size by chemical vapor deposition of silica and XAFS analysis of metals being highly dispersed inside and outside a framework.

Post-fabrication voltage controlled resonance tuning of nanoscale plasmonic antennas.

Science.gov (United States)

Lumdee, Chatdanai; Toroghi, Seyfollah; Kik, Pieter G

2012-07-24

Voltage controlled wavelength tuning of the localized surface plasmon resonance of gold nanoparticles on an aluminum film is demonstrated in single particle microscopy and spectroscopy measurements. Anodization of the Al film after nanoparticle deposition forms an aluminum oxide spacer layer between the gold particles and the Al film, modifying the particle-substrate interaction. Darkfield microscopy reveals ring-shaped scattering images from individual Au nanoparticles, indicative of plasmon resonances with a dipole moment normal to the substrate. Single particle scattering spectra show narrow plasmon resonances that can be tuned from ~580 to ~550 nm as the anodization voltage increases to 12 V. All observed experimental trends could be reproduced in numerical simulations. The presented approach could be used as a general postfabrication resonance optimization step of plasmonic nanoantennas and devices.

Eliciting extra prominence in read-speech tasks: The effects of different text-highlighting methods on acoustic cues to perceived prominence

DEFF Research Database (Denmark)

Berger, Stephanie; Niebuhr, Oliver; Fischer, Kerstin

2018-01-01

The research initiative Innovating Speech EliCitation Techniques (INSPECT) aims to describe and quantify how recording methods, situations and materials influence speech produc-tion in lab-speech experiments. On this basis, INSPECT aims to develop methods that reliably stimulate specific patterns...... and styles of speech, like expressive or conversational speech or different types emphatic accents. The present study investigates if and how different text highlighting methods (yellow background, bold, capital letter, italics, and underlining) make speakers reinforce the level of perceived prominence...

Under the spell of Landau when theoretical physics was shaping destinies

CERN Document Server

2013-01-01

This invaluable collection of memoirs and reviews on scientific activities of the most prominent theoretical physicists belonging to the Landau School - Landau, Anselm, Gribov, Zeldovich, Kirzhnits, Migdal, Ter-Martirosyan and Larkin - are being published in English for the first time. The main goal is to acquaint readers with the life and work of outstanding Soviet physicists who, to a large extent, shaped theoretical physics in the 1950s - 70s. Many intriguing details have remained unknown beyond the "Iron Curtain" which was dismantled only with the fall of the USSR.

Resonances in photoabsorption: Predissociation line shapes in the 3pπD1Π+u ← Χ1Σg+ system in H2

International Nuclear Information System (INIS)

Mezei, J. Zs.; Schneider, I. F.; Glass-Maujean, M.; Jungen, Ch.

2014-01-01

The predissociation of the 3pπD 1 Π u + ,v≥3,N=1, N = 2, and N = 3 levels of diatomic hydrogen is calculated by ab initio multichannel quantum defect theory combined with a R-matrix type approach that accounts for interfering predissociation and autoionization. The theory yields absorption line widths and shapes that are in good agreement with those observed in the high-resolution synchrotron vacuum-ultraviolet absorption spectra obtained by Dickenson et al. [J. Chem. Phys. 133, 144317 (2010)] at the DESIRS beamline of the SOLEIL synchrotron. The theory predicts further that many of the D state resonances with v ⩾ 6 exhibit a complex fine structure which cannot be modeled by the Fano profile formula and which has not yet been observed experimentally

Environmentally friendly synthesis of highly monodisperse biocompatible gold nanoparticles with urchin-like shape.

Science.gov (United States)

Lu, Lehui; Ai, Kelong; Ozaki, Yukihiro

2008-02-05

We report a facile and environmentally friendly strategy for high-yield synthesis of highly monodisperse gold nanoparticles with urchin-like shape. A simple protein, gelatin, was first used for the control over shape and orientation of the gold nanoparticles. These nanoparticles, ready to use for biological systems, are promising in the optical imaging-based disease diagnostics and therapy because of their tunable surface plasmon resonance (SPR) and excellent surface-enhanced Raman scattering (SERS) activity.

Nonlinear resonant ultrasound spectroscopy (NRUS) applied to damage assessment in bone

Science.gov (United States)

Muller, Marie; Sutin, Alexander; Guyer, Robert; Talmant, Maryline; Laugier, Pascal; Johnson, Paul A.

2005-12-01

Nonlinear resonant ultrasound spectroscopy (NRUS) is a resonance-based technique exploiting the significant nonlinear behavior of damaged materials. In NRUS, the resonant frequency(ies) of an object is studied as a function of the excitation level. As the excitation level increases, the elastic nonlinearity is manifest by a shift in the resonance frequency. This study shows the feasibility of this technique for application to damage assessment in bone. Two samples of bovine cortical bone were subjected to progressive damage induced by application of mechanical cycling. Before cycling commenced, and at each step in the cycling process, NRUS was applied for damage assessment. For independent assessment of damage, high-energy x-ray computed tomography imaging was performed but was only useful in identifying the prominent cracks. As the integral quantity of damage increased, NRUS revealed a corresponding increase in the nonlinear response. The measured change in nonlinear response is much more sensitive than the change in linear modulus. The results suggest that NRUS could be a potential tool for micro-damage assessment in bone. Further work must be carried out for a better understanding of the physical nature of damaged bone and for the ultimate goal of the challenging in vivo implementation of the technique.

The relative cueing power of F0 and duration in German prominence perception

DEFF Research Database (Denmark)

Niebuhr, Oliver; Winkler, Jana

2017-01-01

hierarchy further by putting numbers on the interplay of duration and F0. German listeners indirectly judged through lexical identification the relative prominence levels of two neighboring syllables. Results show that an increase in F0 of between 0.49 and 0.76 st is required to outweigh the prominence...... effect of a 30% increase in duration of a neighboring syllable. These numbers are fairly stable across a large range of absolute F0 and duration levels and hence useful in speech technology....

Gain-assisted plasmon induced transparency in T-shaped metamaterials for slow light

International Nuclear Information System (INIS)

He, Jinna; Wang, Junqiao; Fan, Chunzhen; Liang, Erjun; Ding, Pei

2015-01-01

We theoretically investigate the gain-assisted plasmonic analog of electromagnetically induced transparency (EIT) in a novel planar metamaterial, whose unit cell consists of two perpendicularly connected metallic bars, forming a ‘T’ configuration. An EIT-like resonance can be achieved by introducing symmetry breaking into its shape. The results show that the group index is greatly enhanced at the optimum value of the gain due to a dramatic amplification of the EIT-like resonance. Furthermore, a trade-off between the group index and the transmittance at the EIT-like resonance, which always exists in passive systems with no gains, can be removed at an approximate gain level. E-field enhancements are used to understand the underlying physics. (paper)

Does the ground-state resonance of 10Li overlap neutron threshold

International Nuclear Information System (INIS)

McVoy, K.W.; Van Isacker, P.

1994-01-01

Recent measurements suggest that the ground state of 10 Li is a resonance which may well be wide enough to overlap the (n + 9 Li) threshold. In this context we recall some of the curious properties of resonances located near threshold and entered from a non-decay channel, including their asymmetry and the fact that the peak observed in the cross section occurs at neither the R-matrix nor the S-matrix energy, but rather between the two. Because of these and other complications, it does not seem likely that either the l-value of the resonance or the energy of the corresponding state can accurately be determined form the shape of the resonance peak alone. (authors). 5 refs., 4 figs., 2 tabs

Shape of the nuclear magnetic resonance line in anisotropic superconductors with an irregular vortex lattice

International Nuclear Information System (INIS)

Minkin, A.V.; Tsarevskij, S.L.

2006-01-01

For high-temperature superconductors the shape of a NMR spectrum line is built regarding for variation of inhomogeneity of irregular vortex lattice magnetic field near superconductor surface. It is shown that the shape of a NMR line is not simply widened but noticeably varies depending on the degree of irregularity of a superconductor vortex lattice. This variation is associated with a local symmetry decrease in an irregular vortex lattice of the superconductor. Taking into account these circumstances may considerably change conclusions about the type of a vortex lattice and superconductor parameters which are commonly gained from NMR line shape analysis [ru

Comparing UV/EUV line parameters and magnetic field in a quiescent prominence with tornadoes

Science.gov (United States)

Levens, P. J.; Labrosse, N.; Schmieder, B.; López Ariste, A.; Fletcher, L.

2017-10-01

Context. Understanding the relationship between plasma and the magnetic field is important for describing and explaining the observed dynamics of solar prominences. Aims: We determine if a close relationship can be found between plasma and magnetic field parameters, measured at high resolution in a well-observed prominence. Methods: A prominence observed on 15 July 2014 by the Interface Region Imaging Spectrograph (IRIS), Hinode, the Solar Dynamics Observatory (SDO), and the Télescope Héliographique pour l'Étude du Magnétisme et des Instabilités Solaires (THEMIS) is selected. We perform a robust co-alignment of data sets using a 2D cross-correlation technique. Magnetic field parameters are derived from spectropolarimetric measurements of the He I D3 line from THEMIS. Line ratios and line-of-sight velocities from the Mg II h and k lines observed by IRIS are compared with magnetic field strength, inclination, and azimuth. Electron densities are calculated using Fe xii line ratios from the Hinode Extreme-ultraviolet Imaging Spectrometer, which are compared to THEMIS and IRIS data. Results: We find Mg II k/h ratios of around 1.4 everywhere, similar to values found previously in prominences. Also, the magnetic field is strongest ( 30 G) and predominantly horizontal in the tornado-like legs of the prominence. The k3 Doppler shift is found to be between ±10 km s-1 everywhere. Electron densities at a temperature of 1.5 × 106 K are found to be around 109 cm-3. No significant correlations are found between the magnetic field parameters and any of the other plasma parameters inferred from spectroscopy, which may be explained by the large differences in the temperatures of the lines used in this study. Conclusions: This is the first time that a detailed statistical study of plasma and magnetic field parameters has been performed at high spatial resolution in a prominence. Our results provide important constraints on future models of the plasma and magnetic field in

Beat gestures and prosodic prominence: impact on learning

OpenAIRE

Kushch, Olga

2018-01-01

Previous research has shown that gestures are beneficial for language learning. This doctoral thesis centers on the effects of beat gestures– i.e., hand and arm gestures that are typically associated with prosodically prominent positions in speech - on such processes. Little is known about how the two central properties of beat gestures, namely how they mark both information focus and rhythmic positions in speech, can be beneficial for learning either a first or a second language. The main go...

Fluidic Manufacture of Star-Shaped Gold Nanoparticles.

Science.gov (United States)

Silvestri, Alessandro; Lay, Luigi; Psaro, Rinaldo; Polito, Laura; Evangelisti, Claudio

2017-07-21

Star-shaped gold nanoparticles (StarAuNPs) are extremely attractive nanomaterials, characterized by localized surface plasmon resonance which could be potentially employed in a large number of applications. However, the lack of a reliable and reproducible synthetic protocols for the production of StarAuNPs is the major limitation to their spreading. For the first time, here we present a robust protocol to manufacture reproducible StarAuNPs by exploiting a fluidic approach. Star-shaped AuNPs have been synthesized by means of a seed-less protocol, employing ascorbic acid as reducing agent at room temperature. Moreover, the versatility of the bench-top microfluidic protocol has been exploited to afford hydrophilic, hydrophobic and solid-supported engineered StarAuNPs, by avoiding intermediate NP purifications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal and particle size distribution effects on the ferromagnetic resonance in magnetic fluids

International Nuclear Information System (INIS)

Marin, C.N.

2006-01-01

Thermal and particle size distribution effects on the ferromagnetic resonance of magnetic fluids were theoretically investigated, assuming negligible interparticle interactions and neglecting the viscosity of the carrier liquid. The model is based on the usual approach for the ferromagnetic resonance description of single-domain magnetic particle systems, which was amended in order to take into account the finite particle size effect, the particle size distribution and the orientation mobility of the particles within the magnetic fluid. Under these circumstances the shape of the resonance line, the resonance field and the line width are found to be strongly affected by the temperature and by the particle size distribution of magnetic fluids

Tunable Fano resonance in MDM stub waveguide coupled with a U-shaped cavity

Science.gov (United States)

Yi, Xingchun; Tian, Jinping; Yang, Rongcao

2018-04-01

A new compact metal-dielectric-metal waveguide system consisting of a stub coupled with a U-cavity is proposed to produce sharp and asymmetric Fano resonance. The transmission properties of the proposed structure are numerically studied by the finite element method and verified by the coupled mode theory. Simulation results reveal that the spectral profile can be easily tuned by adjusting the geometric parameters of the structure. One of the potential application of the proposed structure as a highly efficient plasmonic refractive index nanosensor was investigated with its sensitivity of more than 1000 nm/RIU and a figure of merit of up to 5500. Another application is integrated slow-light device whose group index can be greater than 6. In addition, multiple Fano resonances will occur in the broadband transmission spectrum by adding another U-cavity or (and) stub. The characteristics of the proposed structure are very promising for the highly performance filters, on-chip nanosensors, and slow-light devices.

Application of Numerical Analysis of the Shape of Electron Paramagnetic Resonance Spectra for Determination of the Number of Different Groups of Radicals in the Burn Wounds

Directory of Open Access Journals (Sweden)

Paweł Olczyk

2017-01-01

Full Text Available Background. The evidence exists that radicals are crucial agents necessary for the wound regeneration helping to enhance the repair process. Materials and methods. The lineshape of the electron paramagnetic resonance (EPR spectra of the burn wounds measured with the low microwave power (2.2 mW was numerically analyzed. The experimental spectra were fitted by the sum of two and three lines. Results. The number of the lines in the EPR spectrum corresponded to the number of different groups of radicals in the natural samples after thermal treatment. The component lines were described by Gaussian and Lorentzian functions. The spectra of the burn wounds were superposition of three lines different in shape and in linewidths. The best fitting was obtained for the sum of broad Gaussian, broad Lorentzian, and narrow Lorentzian lines. Dipolar interactions between the unpaired electrons widened the broad Gaussian and broad Lorentzian lines. Radicals with the narrow Lorentzian lines existed mainly in the tested samples. Conclusions. The spectral shape analysis may be proposed as a useful method for determining the number of different groups of radicals in the burn wounds.

Piezoelectric transduction of flexural modes in pre-stressed microbeam resonators

Science.gov (United States)

Torri, G. B.; Janssen, N. M. A.; Zeng, Z.; Rottenberg, X.; Karabacak, D. M.; Vandecasteele, M.; Van Hoof, C.; Puers, R.; Tilmans, H. A. C.

2014-08-01

This paper reports on the optimization of the design of piezoelectric transducer elements integrated on doubly-clamped microbeam resonators utilized as (bio)chemical sensors. We report and emphasize the often forgotten influence of membrane stresses on defining the dimensions and optimal position of the piezoelectric transducer elements. The study takes into account stress induced structural changes and provides models for the equivalent motional parameters of resonators with particular shapes of the transducers matching the flexural modes of vibration. The above is analyzed theoretically using numerical models and is confirmed by impedance measurements and optical measurements of fabricated doubly-clamped beam resonators. We propose various transducer designs and highlight the advantages of using higher order vibration modes by implementing specially designed mode matching transducer elements. It is concluded that the paper describes and highlights the importance of accounting for the membrane stresses to optimize the resonator performance and the low power in electronic feedback of resonating sensing systems.

Piezoelectric transduction of flexural modes in pre-stressed microbeam resonators

International Nuclear Information System (INIS)

Torri, G B; Rottenberg, X; Hoof, C Van; Puers, R; Tilmans, H A C; Janssen, N M A; Zeng, Z; Karabacak, D M; Vandecasteele, M

2014-01-01

This paper reports on the optimization of the design of piezoelectric transducer elements integrated on doubly-clamped microbeam resonators utilized as (bio)chemical sensors. We report and emphasize the often forgotten influence of membrane stresses on defining the dimensions and optimal position of the piezoelectric transducer elements. The study takes into account stress induced structural changes and provides models for the equivalent motional parameters of resonators with particular shapes of the transducers matching the flexural modes of vibration. The above is analyzed theoretically using numerical models and is confirmed by impedance measurements and optical measurements of fabricated doubly-clamped beam resonators. We propose various transducer designs and highlight the advantages of using higher order vibration modes by implementing specially designed mode matching transducer elements. It is concluded that the paper describes and highlights the importance of accounting for the membrane stresses to optimize the resonator performance and the low power in electronic feedback of resonating sensing systems. (paper)

High data density and capacity in chipless radiofrequency identification (chipless-RFID) tags based on double-chains of S-shaped split ring resonators (S-SRRs)

Science.gov (United States)

Herrojo, Cristian; Mata-Contreras, Javier; Paredes, Ferran; Martín, Ferran

2017-11-01

The data density per surface (DPS) is a figure of merit in chipless radiofrequency identification (chipless-RFID) tags. In this paper, it is demonstrated that chipless-RFID tags with high DPS can be implemented by using double-chains of S-shaped split ring resonators (S-SRRs). Tag reading is achieved by near-field coupling between the tag and the reader, a CPW transmission line fed by a harmonic signal tuned to the resonance frequency of the S-SRRs. By transversally displacing the tag over the CPW, the transmission coefficient of the line is modulated by tag motion. This effectively modulates the amplitude of the injected (carrier) signal at the output port of the line, and the identification (ID) code, determined by the presence or absence of S-SRRs at predefined and equidistant positions in the chains, is contained in the envelope function. The DPS is determined by S-SRR dimensions and by the distance between S-SRRs in the chains. However, by using two chains of S-SRRs, the number of bits per unit length that can be accommodated is very high. This chipless-RFID system is of special interest in applications where the reading distance can be sacrificed in favor of data capacity (e.g., security and authentication). Encoding of corporate documents, ballots, exams, etc., by directly printing the proposed tags on the item product to prevent counterfeiting is envisaged.

Holdaway's analysis of the nose prominence of an adult Nigerian ...

African Journals Online (AJOL)

The nose prominence was assessed using Holdaway's analysis. Twenty radiographs randomly selected, were retraced to assess for errors. Data analysis included descriptive statistics, Student's t‑tests and analysis of variance using the Statistical Package for Social Sciences. Results: The mean value recorded for the nose ...

Silver nanostructures with well-controlled shapes: synthesis, characterization and growth mechanisms

International Nuclear Information System (INIS)

Kan Caixia; Zhu Jiejun; Zhu Xiaoguang

2008-01-01

This paper describes a poly(vinylpyrollidone)-directed polyol synthesis method for the fabrication of silver (Ag) nanostructures with well-controlled shapes (such as nanorods and nanocubes) by adjusting the synthesizing parameters. The structure characterizations suggest that the Ag nanorods grow from the five-fold twinned decahedral crystal nuclei. The nature of the {1 1 1} planes of Ag crystal and the highly selective poly(vinylpyrollidone) adsorption on the {100} planes of Ag crystal nuclei are favourable for the formation of Ag nanorods and Ag nanowires. The single crystalline Ag nanocubes obtained at optimum conditions are perfect in shape and are enclosed by the {1 0 0} facets. The optical properties of the Ag nanostructures show an attractive plasma resonance, displaying a considerable dependence on the shape and size. The formation of the Ag nanostructures with well-defined shapes is probably due to the fact that the nanostructures are controlled thermodynamically and kinetically. The ability to generate shape-controlled Ag nanostructures also provides an opportunity to experimentally and systematically study the relationship between their properties and geometric shapes

Silver nanostructures with well-controlled shapes: synthesis, characterization and growth mechanisms

Science.gov (United States)

Kan, Cai-Xia; Zhu, Jie-Jun; Zhu, Xiao-Guang

2008-08-01

This paper describes a poly(vinylpyrollidone)-directed polyol synthesis method for the fabrication of silver (Ag) nanostructures with well-controlled shapes (such as nanorods and nanocubes) by adjusting the synthesizing parameters. The structure characterizations suggest that the Ag nanorods grow from the five-fold twinned decahedral crystal nuclei. The nature of the {1 1 1} planes of Ag crystal and the highly selective poly(vinylpyrollidone) adsorption on the {100} planes of Ag crystal nuclei are favourable for the formation of Ag nanorods and Ag nanowires. The single crystalline Ag nanocubes obtained at optimum conditions are perfect in shape and are enclosed by the {1 0 0} facets. The optical properties of the Ag nanostructures show an attractive plasma resonance, displaying a considerable dependence on the shape and size. The formation of the Ag nanostructures with well-defined shapes is probably due to the fact that the nanostructures are controlled thermodynamically and kinetically. The ability to generate shape-controlled Ag nanostructures also provides an opportunity to experimentally and systematically study the relationship between their properties and geometric shapes.

Head turning as a prominent motor symptom in status epilepticus.

Science.gov (United States)

Bauer, Gerhard; Broessner, Gregor; Unterberger, Iris; Walser, Gerald; Pfausler, Bettina; Trinka, Eugen

2008-06-01

Head and eye turning is frequently observed during seizures. Versions with tonic and/or clonic symptoms can be differentiated from smooth head deviations. Head turning as a prominent symptom of status epilepticus has not previously been reported. We present eight case reports, (7 women/1 man, mean age 41 years, median 41.5, range 10 to 74), of status epilepticus (SE), with head turning as a prominent motor symptom. Six were accompanied by continuous frontal, occipital and temporal ictal epileptiform discharges. Furthermore, two patients had absence status with rhythmic and clonic head versions. While the localizing significance of head turnings in SE is low, in our cases, the direction was away from the discharging hemisphere in all cases of focal SE regardless of whether the turning was classified as version (three cases) or deviation (three cases). In this small series of SE, the classical observation of a patient looking away from the discharging hemisphere is still valid.

Heat dissipation and information flow for delayed bistable Langevin systems near coherence resonance.

Science.gov (United States)

Xiao, Tiejun

2016-11-01

In this paper, stochastic thermodynamics of delayed bistable Langevin systems near coherence resonance is discussed. We calculate the heat dissipation rate and the information flow of a delayed bistable Langevin system under various noise intensities. Both the heat dissipation rate and the information flow are found to be bell-shaped functions of the noise intensity, which implies that coherence resonance manifests itself in the thermodynamic properties.

A Multilevel Shape Fit Analysis of Neutron Transmission Data

Science.gov (United States)

Naguib, K.; Sallam, O. H.; Adib, M.; Ashry, A.

A multilevel shape fit analysis of neutron transmission data is presented. A multilevel computer code SHAPE is used to analyse clean transmission data obtained from time-of-flight (TOF) measurements. The shape analysis deduces the parameters of the observed resonances in the energy region considered in the measurements. The shape code is based upon a least square fit of a multilevel Briet-Wigner formula and includes both instrumental resolution and Doppler broadenings. Operating the SHAPE code on a test example of a measured transmission data of 151Eu, 153Eu and natural Eu in the energy range 0.025-1 eV accquired a good result for the used technique of analysis.Translated AbstractAnalyse von Neutronentransmissionsdaten mittels einer VielniveauformanpassungNeutronentransmissionsdaten werden in einer Vielniveauformanpassung analysiert. Dazu werden bereinigte Daten aus Flugzeitmessungen mit dem Rechnerprogramm SHAPE bearbeitet. Man erhält die Parameter der beobachteten Resonanzen im gemessenen Energiebereich. Die Formanpassung benutzt eine Briet-Wignerformel und berücksichtigt Linienverbreiterungen infolge sowohl der Meßeinrichtung als auch des Dopplereffekts. Als praktisches Beispiel werden 151Eu, 153Eu und natürliches Eu im Energiebereich 0.025 bis 1 eV mit guter Übereinstimmung theoretischer und experimenteller Werte behandelt.

77 FR 3779 - Guidance for Industry on Product Name Placement, Size, and Prominence in Advertising and...

Science.gov (United States)

2012-01-25

... Advertising and Promotional Labeling; Availability AGENCY: Food and Drug Administration, HHS. ACTION: Notice... entitled ``Product Name Placement, Size, and Prominence in Advertising and Promotional Labeling.'' The..., prominence, and frequency in promotional labeling and advertising for prescription human and animal drugs and...

Children’s responses to online advergames: the role of persuasion knowledge, brand prominence and game involvement

NARCIS (Netherlands)

van Reijmersdal, E.; Rozendaal, E.; Buijzen, M.

2011-01-01

This study examined the effects of three factors typically associated with advergames: brand prominence, game involvement, and (limited) persuasion knowledge on cognitive and affective responses. An experiment (N = 104, 7-12 year olds) showed that game involvement and brand prominence influenced

Shaping of few-cycle laser pulses via a subwavelength structure

International Nuclear Information System (INIS)

Guo Liang; Xie Xiao-Tao; Zhan Zhi-Ming

2013-01-01

We theoretically investigate the propagation of few-cycle laser pulses in resonant two-level dense media with a subwavelength structure, which is described by the full Maxwell—Bloch equations without the frame of slowly varying envelope and rotating wave approximations. The input pulses can be shaped into shorter ones with a single or less than one optical cycle. The effect of the parameters of the subwavelength structure and laser pulses is studied. Our study shows that the media with a subwavelength structure can significantly shape the few-cycle pulses into a subcycle pulse, even for the case of chirp pulses as input fields. This suggests that such subwavelength structures have potential application in the shaping of few-cycle laser pulses. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Nuclear magnetic resonance apparatus

International Nuclear Information System (INIS)

Lambert, R.

1991-01-01

In order to include the effect of a magnetic object in a subject under investigation, Nuclear Magnetic Resonance (NMR) apparatus is operable at more than one radio frequency (RF) frequency. The apparatus allows normal practice as far as obtaining an NMR response or image from a given nuclear species is concerned, but, in addition, interrogates the nuclear spin system at a frequency which is different from the resonance frequency normally used for the given nuclear species, as determined from the applied magnetic field. The magnetic field close to a magnetised or magnetisable object is modified and the given nuclear species gives a response at the different frequency. Thus detection of a signal at the frequency indicates the presence of the chosen nuclei close to the magnetised or magnetisable object. Applications include validation of an object detection or automatic shape inspection system in the presence of magnetic impurities, and the detection of magnetic particles which affect measurement of liquid flow in a pipe. (author)

Establishing the Thematic Structure and Investigating the most Prominent Theta Roles Used in Sindhi Language

Directory of Open Access Journals (Sweden)

Zahid Ali Veesar

2015-07-01

Full Text Available This study focuses on the thematic structure of the Sindhi verbs to find theta roles in the Sindhi language. The study tries to answer the research questions; “What are the thematic structures of Sindhi verbs?” and “What are the prominent theta roles in the Sindhi language?” It examines the argument/thematic structure of Sindhi verbs and also finds the theta roles assigned by the Sindhi verbs to their arguments along with the most prominent theta roles used in the Sindhi language. The data come from the two interviews taken from two young native Sindhi speakers, which consist of 2 hours conversation having 1,669 sentences in natural spoken version of the Sindhi language. Towards the end, it has been found that the Sindhi language has certain theta roles which are assigned by the verbs to their arguments in sentences. Each verb phrase in our data is thus examined and studied in detail in terms of Argument/Thematic structure in order to find theta roles in Sindhi language. Thus, in this regard, each verb phrase (in a sentence has been examined with the help of Carnie’s theoretical framework (Thematic Relation and Theta Roles: 2006 in order to find the prominent theta roles in the Sindhi language. The data have been examined and analysed on the basis of the Carnie’s theoretical framework. The study finds that the Sindhi language has all (09 theta roles which have been proposed by Carnie (2006. It has been found that six prominent theta roles out of nine are used prominently in Sindhi. The six prominent theta roles in Sindhi language are: agent, theme, beneficiary, recipient, locative and goal.

Resistively detected NMR line shapes in a quasi-one-dimensional electron system

Science.gov (United States)

Fauzi, M. H.; Singha, A.; Sahdan, M. F.; Takahashi, M.; Sato, K.; Nagase, K.; Muralidharan, B.; Hirayama, Y.

2017-06-01

We observe variation in the resistively detected nuclear magnetic resonance (RDNMR) line shapes in quantum Hall breakdown. The breakdown occurs locally in a gate-defined quantum point contact (QPC) region. Of particular interest is the observation of a dispersive line shape occurring when the bulk two-dimensional electron gas (2DEG) set to νb=2 and the QPC filling factor to the vicinity of νQPC=1 , strikingly resemble the dispersive line shape observed on a 2D quantum Hall state. This previously unobserved line shape in a QPC points to a simultaneous occurrence of two hyperfine-mediated spin flip-flop processes within the QPC. Those events give rise to two different sets of nuclei polarized in the opposite direction and positioned at a separate region with different degrees of electronic spin polarization.

Compact Microstrip Triple-Mode Bandpass Filters Using Dual-Stub-Loaded Spiral Resonators

Directory of Open Access Journals (Sweden)

K. D. Xu

2017-04-01

Full Text Available Two new microstrip triple-mode resonators loaded with T-shaped open stubs using axially and centrally symmetric spiral structures, respectively, are presented. Spiraled for circuit size reduction, these two half-wavelength resonators can both generate three resonant modes over a wide frequency band by loading two T-stubs with different lengths. Due to the structural symmetry, they can be analyzed by odd- and even-mode method. To validate the design concept, two compact bandpass filters (BPFs using these two novel resonators with center frequencies of 1.76 GHz and 2.44 GHz for the GSM1800 and WLAN/Zigbee applications, respectively, have been designed, fabricated and tested. The center frequencies and bandwidths can be tunable through the analysis of resonant frequency responses, fractional bandwidths and external quality factor versus the resonator parameters. The final measured results have achieved good consistence with the simulations of these two BPFs.

High resolution neurography of the brachial plexus by 3 Tesla magnetic resonance imaging.

Science.gov (United States)

Cejas, C; Rollán, C; Michelin, G; Nogués, M

2016-01-01

The study of the structures that make up the brachial plexus has benefited particularly from the high resolution images provided by 3T magnetic resonance scanners. The brachial plexus can have mononeuropathies or polyneuropathies. The mononeuropathies include traumatic injuries and trapping, such as occurs in thoracic outlet syndrome due to cervical ribs, prominent transverse apophyses, or tumors. The polyneuropathies include inflammatory processes, in particular chronic inflammatory demyelinating polyneuropathy, Parsonage-Turner syndrome, granulomatous diseases, and radiation neuropathy. Vascular processes affecting the brachial plexus include diabetic polyneuropathy and the vasculitides. This article reviews the anatomy of the brachial plexus and describes the technique for magnetic resonance neurography and the most common pathologic conditions that can affect the brachial plexus. Copyright © 2016 SERAM. Published by Elsevier España, S.L.U. All rights reserved.

Shape memory nanocomposite of poly(L-lactic acid/graphene nanoplatelets triggered by infrared light and thermal heating

Directory of Open Access Journals (Sweden)

S. Lashgari

2016-04-01

Full Text Available In this study, the effect of graphene nanoplatelets (GNPs on the shape memory properties of poly(L-lactic acid (PLLA was studied. In addition to thermal activation, the possibility of infrared actuating of thermo-responsive shape memory PLLA/GNPs nanocomposite was investigated. The incorporated GNPs were expected to absorb infrared wave’s energy and activate shape memory PLLA/GNPs. Different techniques such as differential scanning calorimetry (DSC, wide-angle X-ray diffraction (WAXD, field emission gun scanning electron microscope (FEG-SEM and dynamic mechanical thermal analysis (DMTA were used to characterize samples. DSC and WAXD results indicated that GNPs augmented crystallinity due to nucleating effect of graphene particles. GNPs improved both thermal and infrared activating shape memory properties along with faster response. Pure shape memory PLLA was slightly responsive to infrared light and its infrared actuated shape recovery ratio was 86% which increased to more than 95% with loading of GNPs. Drastic improvement in the crystallinity was obtained in nanocomposites with lower GNPs contents (0.5 and 1 wt% due to finer dispersion of graphene which resulted in more prominent mechanical and shape memory properties enhancement. Infrared activated shape memory PLLA/GNPs nanocomposites can be developed for wireless remote shape control of smart medical and bio-systems.

Evaluation of Resonant Damping Techniques for Z-Source Current-Type Inverter

DEFF Research Database (Denmark)

Blaabjerg, Frede; Loh, Poh Chiang; Gajanayake, C.J.

2008-01-01

For the renewable energy sources whose outputs vary continuously, a Z-source current-type inverter has been proposed as a possible buck-boost alternative for grid-interfacing. With a unique X-shaped LC network connected between its dc power source and inverter topology, Z-source current......-type inverter is however expected to suffer from compounded resonant complications in addition to those associated with its second-order output filter. To improve its damping performance, this paper proposes the careful integration of Posicast or three-step compensators before the inverter pulse-width modulator...... for damping triggered resonant oscillations. In total, two compensators are needed for wave-shaping the inverter boost factor and modulation ratio, and they can conveniently be implemented using first-in first-out stacks and embedded timers of modern digital signal processors widely used in motion control...

On-Demand Microwave Generator of Shaped Single Photons

Science.gov (United States)

Forn-Díaz, P.; Warren, C. W.; Chang, C. W. S.; Vadiraj, A. M.; Wilson, C. M.

2017-11-01

We demonstrate the full functionality of a circuit that generates single microwave photons on demand, with a wave packet that can be modulated with a near-arbitrary shape. We achieve such a high tunability by coupling a superconducting qubit near the end of a semi-infinite transmission line. A dc superconducting quantum interference device shunts the line to ground and is employed to modify the spatial dependence of the electromagnetic mode structure in the transmission line. This control allows us to couple and decouple the qubit from the line, shaping its emission rate on fast time scales. Our decoupling scheme is applicable to all types of superconducting qubits and other solid-state systems and can be generalized to multiple qubits as well as to resonators.

Energy release from a stream of infalling prominence debris on 2011 September 7-8

Science.gov (United States)

Inglis, A. R.; Gilbert, H. R.; Ofman, L.

2017-12-01

In recent years high-resolution and high-cadence EUV imaging has revealed a new phenomenon, impacting prominence debris, where prominence material from failed or partial eruptions can impact the lower atmosphere and release energy. We present a clear example of this phenomenon occurring on 2011 September 7-8. The initial eruption of prominence material was associated with an X1.8-class flare from AR11283, occurring at 22:30 UT on 2011 September 7, resulting in a semi-continuous stream of this material returning to the solar surface between 00:20 - 00:40 UT on 2011 September 8. A substantial area remote from the original active region experienced brightening in multiple EUV channels observed by SDO/AIA. Using the differential emission measure, we estimated the energetic properties of this event. We found that the radiated energy of the impacted plasma was of order 10^27 ergs, while the upper limit on the thermal energy peaked at 10^28 ergs. Based on these estimates we were able to determine the mass content of the debris to be in the range 2x10^14 energy release takes place during these events, and that such impacts may be used as a novel diagnostic tool for investigating prominence material properties.

EUV lines observed with EIS/Hinode in a solar prominence

Czech Academy of Sciences Publication Activity Database

Labrosse, N.; Schmieder, B.; Heinzel, Petr; Watanabe, T.

2011-01-01

Roč. 531, July (2011), A69/1-A69/11 ISSN 0004-6361 Grant - others:EU(XE) ESA- PECS project No. 98030 Institutional research plan: CEZ:AV0Z10030501 Keywords : Sun * filaments * prominences Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.587, year: 2011

Ground-plane-less bidirectional terahertz absorber based on omega resonators

NARCIS (Netherlands)

Balmakou, Alexei; Podalov, Maxim; Khakhomov, Sergei; Stavenga, Doekele; Semchenko, Igor

2015-01-01

We present a new ultrathin metamaterial that acts as a frequency-selective absorber of terahertz radiation. The absorber is a square array of pairs of omega-shaped micro-resonators made of high-ohmic-loss metal. The metamaterial provides significant suppression of transmitted and reflected radiation

Perspectives of shaped pulses for EPR spectroscopy

Science.gov (United States)

Spindler, Philipp E.; Schöps, Philipp; Kallies, Wolfgang; Glaser, Steffen J.; Prisner, Thomas F.

2017-07-01

This article describes current uses of shaped pulses, generated by an arbitrary waveform generator, in the field of EPR spectroscopy. We show applications of sech/tanh and WURST pulses to dipolar spectroscopy, including new pulse schemes and procedures, and discuss the more general concept of optimum-control-based pulses for applications in EPR spectroscopy. The article also describes a procedure to correct for experimental imperfections, mostly introduced by the microwave resonator, and discusses further potential applications and limitations of such pulses.

Double-charming Higgs boson identification using machine-learning assisted jet shapes

Science.gov (United States)

Lenz, Alexander; Spannowsky, Michael; Tetlalmatzi-Xolocotzi, Gilberto

2018-01-01

We study the possibility of identifying a boosted resonance that decays into a charm pair against different sources of background using QCD event shapes, which are promoted to jet shapes. Using a set of jet shapes as input to a boosted decision tree, we find that observables utilizing the simultaneous presence of two charm quarks can access complementary information compared to approaches relying on two independent charm tags. Focusing on Higgs associated production with subsequent H →c c ¯ decay and on a C P -odd scalar A with mA≤10 GeV we obtain the limits B r (H →c c ¯ )≤6.48 % and B r (H →A (→c c ¯ )Z )≤0.01 % at 95% C.L.

Effect of the prominent catalyst layer surface on reactant gas transport and cell performance at the cathodic side of a PEMFC

International Nuclear Information System (INIS)

Perng, Shiang-Wuu; Wu, Horng-Wen

2010-01-01

The cell performance enhancement of a proton exchange membrane fuel cell (PEMFC) has been numerically investigated with the prominence-like form catalyst layer surface of the same composition at the cathodic half-cell of a PEMFC. The geometries of the prominence-like form catalyst layer surface are assigned as one prominence, three prominences, and five prominences catalyst layer surfaces with constant distance between two prominences in the same gas diffusion layer (GDL) for the purpose of investigating the cell performance. To confine the current investigation to two-dimensional incompressible flows, we assume that the fluid flow is laminar with a low Reynolds number 15. The results indicate that the prominence-like form catalyst layer surface can effectively enhance the local cell performance of a PEMFC.

Convergent j-matrix calculation of electron-helium resonances

International Nuclear Information System (INIS)

Konovalov, D.A.; McCarthy, I.E.

1994-12-01

Resonance structures in n=2 and n=3 electron-helium excitation cross sections are calculated using the J-matrix method. The number of close-coupled helium bound and continuum states is taken to convergence, e.g. about 100 channels are coupled for each total spin and angular momentum. It is found that the present J-matrix results are in good shape agreement with recent 29-state R-matrix calculations. However the J-matrix absolute cross sections are slightly lower due to the influence of continuum channels included in the present method. Experiment and theory agree on the positions of n=2 and n=3 resonances. 22 refs., 1 tab.; 3 figs

Atlas-based analysis of cardiac shape and function: correction of regional shape bias due to imaging protocol for population studies.

Science.gov (United States)

Medrano-Gracia, Pau; Cowan, Brett R; Bluemke, David A; Finn, J Paul; Kadish, Alan H; Lee, Daniel C; Lima, Joao A C; Suinesiaputra, Avan; Young, Alistair A

2013-09-13

Cardiovascular imaging studies generate a wealth of data which is typically used only for individual study endpoints. By pooling data from multiple sources, quantitative comparisons can be made of regional wall motion abnormalities between different cohorts, enabling reuse of valuable data. Atlas-based analysis provides precise quantification of shape and motion differences between disease groups and normal subjects. However, subtle shape differences may arise due to differences in imaging protocol between studies. A mathematical model describing regional wall motion and shape was used to establish a coordinate system registered to the cardiac anatomy. The atlas was applied to data contributed to the Cardiac Atlas Project from two independent studies which used different imaging protocols: steady state free precession (SSFP) and gradient recalled echo (GRE) cardiovascular magnetic resonance (CMR). Shape bias due to imaging protocol was corrected using an atlas-based transformation which was generated from a set of 46 volunteers who were imaged with both protocols. Shape bias between GRE and SSFP was regionally variable, and was effectively removed using the atlas-based transformation. Global mass and volume bias was also corrected by this method. Regional shape differences between cohorts were more statistically significant after removing regional artifacts due to imaging protocol bias. Bias arising from imaging protocol can be both global and regional in nature, and is effectively corrected using an atlas-based transformation, enabling direct comparison of regional wall motion abnormalities between cohorts acquired in separate studies.

Comparison of shoulder positions at MR arthrography: change of labroligamentous complex shape and diagnosis of labral tears

International Nuclear Information System (INIS)

Kwak, Jin Young; Ha, Doo Hoe; Kim, Jeung Sook; Lee, Young Soo

2001-01-01

To compare the neutral, internal, and external rotation positions of the glenohumeral joint during magnetic resonance (MR) arthrography performed to assess changes in the shape of the labroligamentous complex (LLC) and in the labral tear. MR arthrography of the shoulder was retrospectively evaluated in 36 patients aged 14-66 (mean, 40) years. Fourteen cases were confirmed by arthroscopic surgery (7 SLAP lesions, 2 Bankart lesions, 1 both SLAP and Bankart lesions). Axial fat-suppressed T1-weighted spin-echo images were acquired with each shoulder in the neutral position, and with internal and external rotations. In each position, we measured the angle of rotation between the perpendicular line on the glenoid fossa and the long axis of the humeral head, analyzing the relationship between the rotational angle and changes in the shape of the LLC at each internal and external rotation, relative to the neutral position. In addition, labral tears in 14 arthroscopically confirmed joints were evaluated in each position. Mean angles of rotation relative to the neutral position were 44.1 and 45.3 degrees in internal and external rotation, respectively. Changes in the anterior LLC occurred in 25 and 24 cases of internal and external rotation, respectively. There was a significantly meaningful relationship between rotational angle and changes in the shape of the anterior LLC during external rotation, and when this changes was noticed, the rotational angle was wider (p<0.05). The posterior LLC changed in shape in 13 and 16 cases of internal and external rotation, respectively, but changes according to the angle of rotation were not statistically significant. In arthroscopically confirmed joints, diagnosis of the eight SLAP lesions at external rotation tended to become more accurate, but no statistically significant differences were noted (p=0.07). Two Bankart lesions were interpreted as a tear in all three positions, and one other such lesion was interpreted as a tear in the

Low frequency phononic band structures in two-dimensional arc-shaped phononic crystals

International Nuclear Information System (INIS)

Xu, Zhenlong; Wu, Fugen; Guo, Zhongning

2012-01-01

The low frequency phononic band structures of two-dimensional arc-shaped phononic crystals (APCs) were studied by the transfer matrix method in cylindrical coordinates. The results showed the first phononic band gaps (PBGs) of APCs from zero Hz with low modes. Locally resonant (LR) gaps were obtained with higher-order rotation symmetry, due to LR frequencies corresponding to the speeds of acoustic waves in the materials. These properties can be efficiently used in a structure for low frequencies that are forbidden, or in a device that permits a narrow window of frequencies. -- Highlights: ► We report a new class of quasi-periodic hetero-structures, arc-shaped phononic crystals (APCs). ► The results show the first PBGs start with zero Hz with low modes. ► Locally resonant (LR) gaps were obtained with higher-order rotation symmetry, due to LR frequencies corresponding to the speeds of acoustic waves in the materials.

Nucleon Resonance Physics

Energy Technology Data Exchange (ETDEWEB)

Burkert, Volker D.

2016-07-25

Recent results of meson photo-production at the existing electron machines with polarized real photon beams and the measurement of polarization observables of the final state baryons have provided high precision data that led to the discovery of new excited nucleon and $\\Delta$ states using multi-channel partial wave analyses procedures. The internal structure of several prominent excited states has been revealed employing meson electroproduction processes. On the theoretical front, lattice QCD is now predicting the baryon spectrum with very similar characteristics as the constituent quark model, and continuum QCD, such as is represented in the Dyson-Schwinger Equations approach and in light front relativistic quark models, describes the non-perturbative behavior of resonance excitations at photon virtuality of $Q^2 > 1.5GeV^2$. In this talk I discuss the need to continue a vigorous program of nucleon spectroscopy and the study of the internal structure of excited states as a way to reveal the effective degrees of freedom underlying the excited states and their dependence on the distance scale probed.

3-D analysis of Maxwell's equations for cavities of arbitrary shape

International Nuclear Information System (INIS)

Whealton, J.H.; Chen, G.L.; McGaffey, R.W.; Raridon, R.J.; Jaeger, E.F.; Bell, M.A.; Hoffman, D.J.

1986-03-01

A three-dimensional analysis of cavity antennas is presented. The analysis is based on the finite difference method with a successive overrelaxation convergence scheme. This method permits the calculation of resonance frequencies and corresponding electric and magnetic fields of eigenmodes in a cavity antenna with an arbitrary shape. 12 refs., 8 figs

A Coupled Resonator for Highly Tunable and Amplified Mixer/Filter

KAUST Repository

Ilyas, Saad; Jaber, Nizar; Younis, Mohammad I.

2017-01-01

We present an H-shaped resonator made of two clamped-clamped microbeams mechanically coupled at the middle with a strong coupler to achieve, in a single device, mechanical amplification of the response signal, filtering, and frequency conversion simultaneously. Using mechanical amplification combined with combination resonances generated from a mixed-frequency excitation, a wideband tunable filter, and a simultaneous frequency up and down convertors at multiple bands is demonstrated. The proposed coupled structure, when combined with the easy-to-implement technique of frequency mixing, is promising for applications in an RF chain.

A Coupled Resonator for Highly Tunable and Amplified Mixer/Filter

KAUST Repository

Ilyas, Saad

2017-04-25

We present an H-shaped resonator made of two clamped-clamped microbeams mechanically coupled at the middle with a strong coupler to achieve, in a single device, mechanical amplification of the response signal, filtering, and frequency conversion simultaneously. Using mechanical amplification combined with combination resonances generated from a mixed-frequency excitation, a wideband tunable filter, and a simultaneous frequency up and down convertors at multiple bands is demonstrated. The proposed coupled structure, when combined with the easy-to-implement technique of frequency mixing, is promising for applications in an RF chain.

Investigation of electron-atom/molecule scattering resonances: Two complex multiconfigurational self-consistent field approaches

Energy Technology Data Exchange (ETDEWEB)

Samanta, Kousik [Department of Chemistry, Rice University, Houston, TX 77005 (United States); Yeager, Danny L. [Department of Chemistry, Texas A and M University, College Station, TX 77843 (United States)

2015-01-22

Resonances are temporarily bound states which lie in the continuum part of the Hamiltonian. If the electronic coordinates of the Hamiltonian are scaled (“dilated”) by a complex parameter, η = αe{sup iθ} (α, θ real), then its complex eigenvalues represent the scattering states (resonant and non-resonant) while the eigenvalues corresponding to the bound states and the ionization and the excitation thresholds remain real and unmodified. These make the study of these transient species amenable to the bound state methods. We developed a quadratically convergent multiconfigurational self-consistent field method (MCSCF), a well-established bound-state technique, combined with a dilated Hamiltonian to investigate resonances. This is made possible by the adoption of a second quantization algebra suitable for a set of “complex conjugate biorthonormal” spin orbitals and a modified step-length constraining algorithm to control the walk on the complex energy hypersurface while searching for the stationary point using a multidimensional Newton-Raphson scheme. We present our computational results for the {sup 2}PBe{sup −} shape resonances using two different computationally efficient methods that utilize complex scaled MCSCF (i.e., CMCSCF). These two methods are to straightforwardly use CMCSCF energy differences and to obtain energy differences using an approximation to the complex multiconfigurational electron propagator. It is found that, differing from previous computational studies by others, there are actually two {sup 2}PBe{sup −} shape resonances very close in energy. In addition, N{sub 2} resonances are examined using one of these methods.

Analysis of specular resonance in dielectric bispheres using rigorous and geometrical-optics theories.

Science.gov (United States)

Miyazaki, Hideki T; Miyazaki, Hiroshi; Miyano, Kenjiro

2003-09-01

We have recently identified the resonant scattering from dielectric bispheres in the specular direction, which has long been known as the specular resonance, to be a type of rainbow (a caustic) and a general phenomenon for bispheres. We discuss the details of the specular resonance on the basis of systematic calculations. In addition to the rigorous theory, which precisely describes the scattering even in the resonance regime, the ray-tracing method, which gives the scattering in the geometrical-optics limit, is used. Specular resonance is explicitly defined as strong scattering in the direction of the specular reflection from the symmetrical axis of the bisphere whose intensity exceeds that of the scattering from noninteracting bispheres. Then the range of parameters for computing a particular specular resonance is specified. This resonance becomes prominent in a wide range of refractive indices (from 1.2 to 2.2) in a wide range of size parameters (from five to infinity) and for an arbitrarily polarized light incident within an angle of 40 degrees to the symmetrical axis. This particular scattering can stay evident even when the spheres are not in contact or the sizes of the spheres are different. Thus specular resonance is a common and robust phenomenon in dielectric bispheres. Furthermore, we demonstrate that various characteristic features in the scattering from bispheres can be explained successfully by using intuitive and simple representations. Most of the significant scatterings other than the specular resonance are also understandable as caustics in geometrical-optics theory. The specular resonance becomes striking at the smallest size parameter among these caustics because its optical trajectory is composed of only the refractions at the surfaces and has an exceptionally large intensity. However, some characteristics are not accounted for by geometrical optics. In particular, the oscillatory behaviors of their scattering intensity are well described by

Subcision Using a Spinal Needle Cannula and a Thread for Prominent Nasolabial Fold Correction

Directory of Open Access Journals (Sweden)

Sang-Yeul Lee

2013-05-01

Full Text Available Deepening of the nasolabial crease is an esthetically unpleasing aging phenomenon occurring in the midface. Various treatment modalities have been introduced to improve the appearance of prominent nasolabial folds, all of which have pros and cons. Currently, a minimally invasive technique using synthetic dermal fillers is most commonly used. A simple and easy subcision procedure using a wire scalpel has also been used and reported to be effective for prominent nasolabial fold correction, with minimal complications. As an alternative to the wire scalpel, we used a 20-gauge metal type spinal needle cannula (Hakko Co. and 4-0 Vicryl suture (Ethicon Inc. for subcision of nasolabial folds. This technique is less expensive than the use of a wire scalpel and easily available when needed. Therefore, on the basis of favorable results, our modified subcision technique may be considered effective for prominent nasolabial fold correction.

The role of prominence in determining the scope of boundary-related lengthening in Greek.

Science.gov (United States)

Katsika, Argyro

2016-03-01

This study aims at examining and accounting for the scope of the temporal effect of phrase boundaries. Previous research has indicated that there is an interaction between boundary-related lengthening and prominence such that the former extends towards the nearby prominent syllable. However, it is unclear whether this interaction is due to lexical stress and/or phrasal prominence (marked by pitch accent) and how far towards the prominent syllable the effect extends. Here, we use an electromagnetic articulography (EMA) study of Greek to examine the scope of boundary-related lengthening as a function of lexical stress and pitch accent separately. Boundaries are elicited by the means of a variety of syntactic constructions.. The results show an effect of lexical stress. Phrase-final lengthening affects the articulatory gestures of the phrase-final syllable that are immediately adjacent to the boundary in words with final stress, but is initiated earlier within phrase-final words with non-final stress. Similarly, the articulatory configurations during inter-phrasal pauses reach their point of achievement later in words with final stress than in words with non-final stress. These effects of stress hold regardless of whether the phrase-final word is accented or de-accented. Phrase-initial lengthening, on the other hand, is consistently detected on the phrase-initial constriction, independently of where the stress is within the preceding, phrase-final, word. These results indicate that the lexical aspect of prominence plays a role in determining the scope of boundary-related lengthening in Greek. Based on these results, a gestural account of prosodic boundaries in Greek is proposed in which lexical and phrasal prosody interact in a systematic and coordinated fashion. The cross-linguistic dimensions of this account and its implications for prosodic structure are discussed.

Dramatic distortion of the 4d giant resonance by the C{sub 60} fullerene shell

Energy Technology Data Exchange (ETDEWEB)

Amusia, M Ya [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Baltenkov, A S [Arifov Institute of Electronics, Akademgorodok, 700125 Tashkent (Uzbekistan); Chernysheva, L V [A F Ioffe Physical-Technical Institute, St Petersburg 194021 (Russian Federation); Felfli, Z [Department of Physics and Center for Theoretical Studies of Physical Systems, Clark Atlanta University, Atlanta, GA 30314 (United States); Msezane, A Z [Department of Physics and Center for Theoretical Studies of Physical Systems, Clark Atlanta University, Atlanta, GA 30314 (United States)

2005-05-28

The photoionization cross section for the endohedral Xe at C{sub 60} atom is investigated within the framework of representing the C{sub 60} by a delta-type potential. Results demonstrate that in Xe at C{sub 60}, the 4d giant resonance is distorted significantly when compared with that of the isolated Xe atom. The reflection of the photoelectron waves by the C{sub 60} causes strong oscillations in the photoionization cross section resulting in the replacement of the Xe 4d giant resonance by four prominent peaks. The approximation of C{sub 60} by an infinitely thin real potential preserves reasonably well the sum rule for the 4d electrons but modifies the dipole polarizability of the 4d shell. (letter to the editor)

Decay of the giant quadrupoles resonance and higher excitation states in 40Ca

International Nuclear Information System (INIS)

Alamanos, N.; Fernandez, B.; Gillibert, A.

1991-01-01

Light charged particles have been measured in coincidence with inelastically scattered fragments from the 40 Ca + 40 Ca reaction at 50 MeV/N. Such a measurement allows to unravel the different reaction mechanisms contributing to the inelastic spectrum: pick-up break-up reactions, knock out and inelastic excitations. The giant quadrupole resonance in 40 Ca is shown to present a 30% non statistical decay branch. A prominent structure at 34 MeV is attributed to target excitation, the decay of this structure is studied

COMPACT DUAL-BAND INVERTED L SHAPED MONOPOLE ANTENNA FOR WLAN APPLICATIONS

Directory of Open Access Journals (Sweden)

K Sumathi

2015-12-01

Full Text Available A highly compact and an optimized design of an Inverted L shaped printed monopole antenna with a simple compact ground plane is proposed. To make the designed antenna suitable for implantation it is embedded in FR-4 substrate and is presented. The antenna is designed for dual-band operation at 2.4GHz and 5.2GHz. It is suitable for Wireless Local Area Network (WLAN applications with return loss (S11 < -10dB. The antenna has two different resonant current paths that support two resonances at 2.44GHz and 5.18GHz (forming an F-shaped structure. The size of the antenna is 32.5mm × 19.6mm × 1.6mm. The antenna design is simulated using the tool Advanced Design System (ADS 2014. This antenna design has good return loss and radiation characteristics in both the required frequency bands. The radiation pattern obtained from the proposed antenna is an Omni directional radiation pattern in the E and H plane over the frequency ranges 2.4GHz and 5.2GHz.

On the absence of resonances for Schrodinger operators with non-trapping potentials in the classical limit

International Nuclear Information System (INIS)

Klein, M.

1985-01-01

We provide bounds on resolvents of dilated Schrodinger operators via exterior scaling. This depends crucially on a non-trapping condition on the potential which has a clear interpretation in classical mechanics. These bounds are a powerful tool to prove absence of resonances due to the tail of the potential in the shape resonance problem

Flotation process control optimisation at Prominent Hill

International Nuclear Information System (INIS)

Lombardi, Josephine; Muhamad, Nur; Weidenbach, M.

2012-01-01

OZ Minerals' Prominent Hill copper- gold concentrator is located 130 km south east of the town of Coober Pedy in the Gawler Craton of South Australia. The concentrator was built in 2008 and commenced commercial production in early 2009. The Prominent Hill concentrator is comprised of a conventional grinding and flotation processing plant with a 9.6 Mtpa ore throughput capacity. The flotation circuit includes six rougher cells, an IseMill for regrinding the rougher concentrate and a Jameson cell heading up the three stage conventional cell cleaner circuit. In total there are four level controllers in the rougher train and ten level controllers in the cleaning circuit for 18 cells. Generic proportional — integral and derivative (PID) control used on the level controllers alone propagated any disturbances downstream in the circuit that were generated from the grinding circuit, hoppers, between cells and interconnected banks of cells, having a negative impact on plant performance. To better control such disturbances, FloatStar level stabiliser was selected for installation on the flotation circuit to account for the interaction between the cells. Multivariable control was also installed on the five concentrate hoppers to maintain consistent feed to the cells and to the IsaMill. An additional area identified for optimisation in the flotation circuit was the mass pull rate from the rougher cells. FloatStar flow optimiser was selected to be installed subsequent to the FloatStar level stabiliser. This allowed for a unified, consistent and optimal approach to running the rougher circuit. This paper describes the improvement in the stabilisation of the circuit achieved by the FloatStar level stabiliser by using the interaction matrix between cell level controllers and the results and benefits of implementing the FloatStar flow optimiser on the rougher train.

Whispering-gallery-mode resonance sensor for dielectric sensing of drug tablets

International Nuclear Information System (INIS)

Neshat, Mohammad; Chen, Huanyu; Safavi-Naeini, Safieddin; Gigoyan, Suren; Saeedkia, Daryoosh

2010-01-01

We propose, for the first time, the application of whispering gallery mode (WGM) perturbation technique in dielectric analysis of disk shape pharmaceutical tablets. Based on WGM resonance, a low-cost high sensitivity sensor in milllimeter-wave frequency range is presented. A comprehensive sensitivity analysis was performed to show that a change in the order of 10 −4 in the sample permittivity can be detected by the proposed sensor. The results of various experiments carried out on drug tablets are reported to demonstrate the potential multifunctional capabilities of the sensor in moisture sensing, counterfeit drug detection and contamination screening. Analytically, two sample placement configurations, i.e. a tablet placed on top of a dielectric disk resonator and inside a dielectric ring resonator, have been studied to predict the resonance frequency and Q-factor of the combined sample-resonator structure. The accuracy of the analytical model was tested against full-wave simulations and experimental data

Time resolved resonance Raman spectra of anilino radical and aniline radical cation

International Nuclear Information System (INIS)

Tripathi, G.N.R.; Schuler, R.H.

1987-01-01

We report, in this paper, submicrosecond time resolved resonance Raman spectra of anilino radical and its radical cation as observed in pulse radiolytic studies of the oxidation of aniline in aqueous solution. By excitation in resonance with the broad and weak electronic transition of anilino radical at 400 nm (ε--1250 M -1 cm -1 ) we have observed, for the first time, the vibrational features of this radical. The Wilson ν 8 /sub a/ ring stretching mode at 1560 cm -1 is most strongly resonance enhanced. The ν 7 /sub a/ CN stretching band at 1505 cm -1 , which is shifted to higher frequency by 231 cm -1 with respect to aniline, is also prominent. The frequency of this latter mode indicates that the CN bond in the radical has considerable double bond character. The Raman spectrum of aniline radical cation, excited in resonance with the --425 nm electronic absorption (ε--4000 M -1 cm -1 ), shows features which are similar to phenoxyl radical. Most of the observed frequencies of this radical in solution are in good agreement with vibrational energies determined by recent laser photoelectron spectroscopic studies in the vapor phase. The bands most strongly enhanced in the resonance Raman spectrum are, however, weak in the photoelectron spectrum. While the vibrational frequencies observed for anilino radical and its isoelectronic cation are quite similar, the resonance enhancement patterns are very different. In particular the ν 14 b 2 mode of anilino radical observed at 1324 cm -1 is highly resonance enhanced because of strong vibronic coupling between the 400 nm 2 A 2 -- 2 B 1 and the higher 2 B 1 -- 2 B 1 electronic transitions

Magnetohydrodynamic waves in two-dimensional prominences embedded in coronal arcades

International Nuclear Information System (INIS)

Terradas, J.; Soler, R.; Díaz, A. J.; Oliver, R.; Ballester, J. L.

2013-01-01

Solar prominence models used so far in the analysis of MHD waves in two-dimensional structures are quite elementary. In this work, we calculate numerically magnetohydrostatic models in two-dimensional configurations under the presence of gravity. Our interest is in models that connect the magnetic field to the photosphere and include an overlying arcade. The method used here is based on a relaxation process and requires solving the time-dependent nonlinear ideal MHD equations. Once a prominence model is obtained, we investigate the properties of MHD waves superimposed on the structure. We concentrate on motions purely two-dimensional, neglecting propagation in the ignorable direction. We demonstrate how, by using different numerical tools, we can determine the period of oscillation of stable waves. We find that vertical oscillations, linked to fast MHD waves, are always stable and have periods in the 4-10 minute range. Longitudinal oscillations, related to slow magnetoacoustic-gravity waves, have longer periods in the range of 28-40 minutes. These longitudinal oscillations are strongly influenced by the gravity force and become unstable for short magnetic arcades.