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Sample records for negative index cavity

  1. Gap solitons in a nonlinear quadratic negative-index cavity.

    PubMed

    Scalora, Michael; de Ceglia, Domenico; D'Aguanno, Giuseppe; Mattiucci, Nadia; Akozbek, Neset; Centini, Marco; Bloemer, Mark J

    2007-06-01

    We predict the existence of gap solitons in a nonlinear, quadratic Fabry-Pérot negative index cavity. A peculiarity of a single negative index layer is that if magnetic and electric plasma frequencies are different it forms a photonic band structure similar to that of a multilayer stack composed of ordinary, positive index materials. This similarity also results in comparable field localization and enhancement properties that under appropriate conditions may be used to either dynamically shift the band edge, or for efficient energy conversion. We thus report that an intense, fundamental pump pulse is able to shift the band edge of a negative index cavity, and make it possible for a weak second harmonic pulse initially tuned inside the gap to be transmitted, giving rise to a gap soliton. The process is due to cascading, a well-known phenomenon that occurs far from phase matching conditions that limits energy conversion rates, it resembles a nonlinear third-order process, and causes pulse compression due to self-phase modulation. The symmetry of the equations of motion under the action of either an electric or a magnetic nonlinearity suggests that both nonlinear polarization and magnetization, or a combination of both, can lead to solitonlike pulses. More specifically, the antisymmetric localization properties of the electric and magnetic fields cause a nonlinear polarization to generate a dark soliton, while a nonlinear magnetization spawns a bright soliton. PMID:17677375

  2. Microwave gain medium with negative refractive index

    NASA Astrophysics Data System (ADS)

    Ye, Dexin; Chang, Kihun; Ran, Lixin; Xin, Hao

    2014-12-01

    Artificial effective media are attractive because of the fantastic applications they may enable, such as super lensing and electromagnetic invisibility. However, the inevitable loss due to their strongly dispersive nature is one of the fundamental challenges preventing such applications from becoming a reality. In this study, we demonstrate an effective gain medium based on negative resistance, to overcompensate the loss of a conventional passive metamaterial, meanwhile keeping its original negative-index property. Energy conservation-based theory, full-wave simulation and experimental measurement show that a fabricated sample consisting of conventional sub-wavelength building blocks with embedded microwave tunnel diodes exhibits a band-limited Lorentzian dispersion simultaneously with a negative refractive index and a net gain. Our work provides experimental evidence to the assertion that a stable net gain in negative-index gain medium is achievable, proposing a potential solution for the critical challenge current metamateiral technology faces in practical applications.

  3. Electromagnetic Wave Chaos in Gradient Refractive Index Optical Cavities

    SciTech Connect

    Wilkinson, P. B.; Fromhold, T. M.; Taylor, R. P.; Micolich, A. P.

    2001-06-11

    Electromagnetic wave chaos is investigated using two-dimensional optical cavities formed in a cylindrical gradient refractive index lens with reflective surfaces. When the planar ends of the lens are cut at an angle to its axis, the geometrical ray paths are chaotic. In this regime, the electromagnetic mode spectrum of the cavity is modulated by both real and ghost periodic ray paths, which also {open_quotes}scar{close_quotes} the electric field intensity distributions of many modes. When the cavity is coupled to waveguides, the eigenmodes generate complex series of resonant peaks in the electromagnetic transmission spectrum.

  4. Structures with negative index of refraction

    DOEpatents

    Soukoulis, Costas M.; Zhou, Jiangfeng; Koschny, Thomas; Zhang, Lei; Tuttle, Gary

    2011-11-08

    The invention provides simplified negative index materials (NIMs) using wire-pair structures, 4-gap single ring split-ring resonator (SRR), fishnet structures and overleaf capacitor SRR. In the wire-pair arrangement, a pair of short parallel wires and continuous wires are used. In the 4-gap single-ring SRR, the SRRs are centered on the faces of a cubic unit cell combined with a continuous wire type resonator. Combining both elements creates a frequency band where the metamaterial is transparent with simultaneously negative .di-elect cons. and .mu.. In the fishnet structure, a metallic mesh on both sides of the dielectric spacer is used. The overleaf capacitor SRR changes the gap capacities to small plate capacitors by making the sections of the SRR ring overlap at the gaps separated by a thin dielectric film. This technique is applicable to conventional SRR gaps but it best deploys for the 4-gap single-ring structures.

  5. Inhomogeneous field in cavities of zero index metamaterials

    NASA Astrophysics Data System (ADS)

    Fu, Yangyang; Xu, Yadong; Chen, Huangyang

    2015-06-01

    In common media, electromagnetic wave always possesses a fluctuant field variation, analogous to an undulant surface of sea. While electromagnetic wave in the media with zero index metamaterials (ZIMs), whose refractive indices are near zero, homogeneous or constant field distribution will emerge, resembling a tranquil surface of lake. Such impression almost could be found in all previous literatures related to ZIMs. However, in this letter, we theoretically and numerically find that, in a cavity structure with ZIMs, when higher order modes (e.g., dipole modes) are excited inside cavity, inhomogeneous field could take place in ZIMs. Such a finding challenges the common perception in ZIMs: It is generally considered that homogeneous or constant field is generated in ZIMs. In addition, the proposed cavity structure herein could be used to manipulate radiation of light, such as enhancing or suppressing radiation, controlling radiation pattern and achieving isotropic or directive radiation, thereby potential applications are expected. These effects are well confirmed by numerical simulations.

  6. Inhomogeneous field in cavities of zero index metamaterials

    PubMed Central

    Fu, Yangyang; Xu, Yadong; Chen, Huangyang

    2015-01-01

    In common media, electromagnetic wave always possesses a fluctuant field variation, analogous to an undulant surface of sea. While electromagnetic wave in the media with zero index metamaterials (ZIMs), whose refractive indices are near zero, homogeneous or constant field distribution will emerge, resembling a tranquil surface of lake. Such impression almost could be found in all previous literatures related to ZIMs. However, in this letter, we theoretically and numerically find that, in a cavity structure with ZIMs, when higher order modes (e.g., dipole modes) are excited inside cavity, inhomogeneous field could take place in ZIMs. Such a finding challenges the common perception in ZIMs: It is generally considered that homogeneous or constant field is generated in ZIMs. In addition, the proposed cavity structure herein could be used to manipulate radiation of light, such as enhancing or suppressing radiation, controlling radiation pattern and achieving isotropic or directive radiation, thereby potential applications are expected. These effects are well confirmed by numerical simulations. PMID:26080276

  7. Simulations of ferrite-dielectric-wire composite negative index materials.

    PubMed

    Rachford, Frederic J; Armstead, Douglas N; Harris, Vincent G; Vittoria, Carmine

    2007-08-01

    We perform extensive finite difference time domain simulations of ferrite based negative index of refraction composites. A wire grid is employed to provide negative permittivity. The ferrite and wire grid interact to provide both negative and positive index of refraction transmission peaks in the vicinity of the ferrite resonance. Notwithstanding the extreme anisotropy in the index of refraction of the composite, negative refraction is seen at the composite air interface allowing the construction of a focusing concave lens with a magnetically tunable focal length. PMID:17930783

  8. Symmetry breaking and optical negative index of closed nanorings

    NASA Astrophysics Data System (ADS)

    Kanté, Boubacar; Park, Yong-Shik; O'Brien, Kevin; Shuldman, Daniel; Lanzillotti-Kimura, Norberto D.; Jing Wong, Zi; Yin, Xiaobo; Zhang, Xiang

    2012-11-01

    Metamaterials have extraordinary abilities, such as imaging beyond the diffraction limit and invisibility. Many metamaterials are based on split-ring structures, however, like atomic orbital currents, it has long been believed that closed rings cannot produce negative refractive index. Here we report a low-loss and polarization-independent negative-index metamaterial made solely of closed metallic nanorings. Using symmetry breaking that negatively couples the discrete nanorings, we measured negative phase delay in our composite ‘chess metamaterial’. The formation of an ultra-broad Fano-resonance-induced optical negative-index band, spanning wavelengths from 1.3 to 2.3 μm, is experimentally observed in this structure. This discrete and mono-particle negative-index approach opens exciting avenues towards symmetry-controlled topological nanophotonics with on-demand linear and nonlinear responses.

  9. Symmetry Breaking and Optical Negative Index of Closed Nanorings

    NASA Astrophysics Data System (ADS)

    Kante, Boubacar; Park, Yong-Shik; O'Brien, Kevin; Shuldman, Daniel; Lanzillotti-Kimura, Norberto; Wong, Zi; Yin, Xiaobo; Zhang, Xiang; UC Berkeley Team

    2013-03-01

    We report the first experimental demonstration of broadband negative-index metamaterial made solely of closed metallic nanorings. Using symmetry breaking that negatively couples the discrete nanorings, we measured negative phase delay in our composite chess metamaterial. Our approach open avenues towards topological nanophotonics with on demand linear and non-linear responses.

  10. Evanescent field sensing: cavity-coupled refractive index sensor (CRIS)

    NASA Astrophysics Data System (ADS)

    Lindvold, Lars R.; Lading, Lars

    1998-03-01

    A new concept for the detection of very small changes in the refractive index of a small sample of transparent material is given. The concept is based on measuring the frequency difference between two modes of a laser (possibly a twin- laser), where the evanescent field of one mode is affected by small refractive index changes. Intracavity sensing allows for orders of magnitude greater sensitivity than with external sensing. The frequency difference is obtained by light beating of the two modes. An imbedded diffractive element ensures proper modematching for the light beating. The relative frequency change is equal to the relative change in refractive index properly averaged over the waveguide. The performance of the intracavity system is compared with a system based on a Mach-Zehnder interferometer. The intracavity system may achieve a resolution that is 104 - 106 higher than the sensitivity of a system based on an external interferometer. The effect of thermal instability is investigated and it is discussed how the required very low thermal off-set can be maintained. Injection locking can be a problem. The problem may be solved by either introducing a fixed frequency off- set or by proper design of the cavity structure. An implementation based on III-V materials with a waveguide configuration and Bragg-mirrors is possible with existing technologies. A concept based on a polymer configuration is proposed.

  11. Tamm plasmon-polariton with negative group velocity induced by a negative index meta-material capping layer at metal-Bragg reflector interface.

    PubMed

    Liu, Cunding; Kong, Mingdong; Li, Bincheng

    2014-05-01

    Influence of a negative refractive index meta-material (NIM) capping layer on properties of Tamm plasmon-polariton at the interface of metal-Bragg reflector structure is investigated. Conditions for excitation of the plasmon-polariton is determined from reflectivity mapping calculation and analyzed with cavity mode theory. For specific thicknesses of capping layers, Tamm plasmon-polariton with negative group velocity is revealed in a wide region of frequency. Different from backward optical propagation induced by negative effective-group-refractive-index in dispersive media, negative group velocity of Tamm plasmon-polariton results from opposite signs of cross-section-integrated field energy and Poynting vector. PMID:24921834

  12. Direct observation of negative-index microwave surface waves.

    PubMed

    Dockrey, J A; Horsley, S A R; Hooper, I R; Sambles, J R; Hibbins, A P

    2016-01-01

    Waves propagating in a negative-index material have wave-front propagation (wavevector, k) opposite in direction to that of energy flow (Poynting vector, S). Here we present an experimental realisation at microwave frequencies of an analogous surface wave phenomenon whereby a metasurface supports a surface mode that has two possible wavevector eigenstates within a narrow band of frequencies: one that supports surface waves with positive mode index, and another that supports surface waves with negative mode index. Phase sensitive measurements of the near-field of surface waves across the metasurface show the contrasting spatial evolution of the two eigenstates, providing a unique opportunity to directly observe the negative-index phenomenon. PMID:26903284

  13. Direct observation of negative-index microwave surface waves

    NASA Astrophysics Data System (ADS)

    Dockrey, J. A.; Horsley, S. A. R.; Hooper, I. R.; Sambles, J. R.; Hibbins, A. P.

    2016-02-01

    Waves propagating in a negative-index material have wave-front propagation (wavevector, k) opposite in direction to that of energy flow (Poynting vector, S). Here we present an experimental realisation at microwave frequencies of an analogous surface wave phenomenon whereby a metasurface supports a surface mode that has two possible wavevector eigenstates within a narrow band of frequencies: one that supports surface waves with positive mode index, and another that supports surface waves with negative mode index. Phase sensitive measurements of the near-field of surface waves across the metasurface show the contrasting spatial evolution of the two eigenstates, providing a unique opportunity to directly observe the negative-index phenomenon.

  14. Direct observation of negative-index microwave surface waves

    PubMed Central

    Dockrey, J. A.; Horsley, S. A. R.; Hooper, I. R.; Sambles, J. R.; Hibbins, A. P.

    2016-01-01

    Waves propagating in a negative-index material have wave-front propagation (wavevector, k) opposite in direction to that of energy flow (Poynting vector, S). Here we present an experimental realisation at microwave frequencies of an analogous surface wave phenomenon whereby a metasurface supports a surface mode that has two possible wavevector eigenstates within a narrow band of frequencies: one that supports surface waves with positive mode index, and another that supports surface waves with negative mode index. Phase sensitive measurements of the near-field of surface waves across the metasurface show the contrasting spatial evolution of the two eigenstates, providing a unique opportunity to directly observe the negative-index phenomenon. PMID:26903284

  15. Soft 3D acoustic metamaterial with negative index.

    PubMed

    Brunet, Thomas; Merlin, Aurore; Mascaro, Benoit; Zimny, Kevin; Leng, Jacques; Poncelet, Olivier; Aristégui, Christophe; Mondain-Monval, Olivier

    2015-04-01

    Many efforts have been devoted to the design and achievement of negative-refractive-index metamaterials since the 2000s. One of the challenges at present is to extend that field beyond electromagnetism by realizing three-dimensional (3D) media with negative acoustic indices. We report a new class of locally resonant ultrasonic metafluids consisting of a concentrated suspension of macroporous microbeads engineered using soft-matter techniques. The propagation of Gaussian pulses within these random distributions of 'ultra-slow' Mie resonators is investigated through in situ ultrasonic experiments. The real part of the acoustic index is shown to be negative (up to almost - 1) over broad frequency bandwidths, depending on the volume fraction of the microbeads as predicted by multiple-scattering calculations. These soft 3D acoustic metamaterials open the way for key applications such as sub-wavelength imaging and transformation acoustics, which require the production of acoustic devices with negative or zero-valued indices. PMID:25502100

  16. Cavity Ring-Down System for Density Measurement of Negative Hydrogen Ion on Negative Ion Source

    SciTech Connect

    Nakano, Haruhisa; Tsumori, Katsuyoshi; Nagaoka, Kenichi; Shibuya, Masayuki; Kisaki, Masashi; Ikeda, Katsunori; Osakabe, Masaki; Kaneko, Osamu; Asano, Eiji; Kondo, Tomoki; Sato, Mamoru; Komada, Seiji; Sekiguchi, Haruo; Takeiri, Yasuhiko; Fantz, Ursel

    2011-09-26

    A Cavity Ring-Down (CRD) system was applied to measure the density of negative hydrogen ion (H{sup -}) in vicinity of extraction surface in the H{sup -} source for the development of neutral beam injector on Large Helical Device (LHD). The density measurement with sampling time of 50 ms was carried out. The measured density with the CRD system is relatively good agreement with the density evaluated from extracted beam-current with applying a similar relation of positive ion sources. In cesium seeded into ion-source plasma, the linearity between an arc power of the discharge and the measured density with the CRD system was observed. Additionally, the measured density was proportional to the extracted beam current. These characteristics indicate the CRD system worked well for H{sup -} density measurement in the region of H{sup -} and extraction.

  17. Negative-Index Metamaterials in the Visible Range

    NASA Astrophysics Data System (ADS)

    Shalaev, Vladimir

    2007-03-01

    In conventional materials, out of the two field components of light, electric and magnetic, only the electric one (``electric hand'') efficiently couples to and probes the atoms of a material while its ``magnetic hand'' remains almost unused because the interaction of atoms with the magnetic filed component of light is normally very week. Metamaterials, i.e. artificial materials with rationally designed properties, can enable the coupling of both field components of light to meta-atoms, enabling entirely new optical properties and exciting applications with such ``two-handed'' light. Metamaterials are expected to open a gateway to unprecedented electromagnetic properties and functionality unattainable from naturally occurring materials. Negative-refractive index metamaterials create entirely new prospects for guiding light on the nanoscale, some of which may have revolutionary impact on present-day optical technologies. The extraordinary nonlinear optical properties of negative-index metamaterials are also discussed. We review this new emerging field of metamaterials and recent progress in demonstrating a negative refractive index in the optical and visible range, where applications can be particularly important, including sub-wavelength imaging and cloaking objects, i.e. making them invisible.

  18. Measurement of air refractive index fluctuation based on interferometry with two different reference cavity lengths.

    PubMed

    Chen, Qianghua; Luo, Huifu; Wang, Sumei; Wang, Feng; Chen, Xinhua

    2012-09-01

    A measurement method based on interferometry with two different reference cavity lengths is presented and applied in air refractive index measurement in which the two cavity lengths and a laser wavelength are combined to generate two wavelength equivalents of cavity. Corresponding calculation equations are derived, and the optical path configuration is designed, which is inspired by the traditional synthetic wavelength method. Theoretical analyses indicate that the measurement uncertainty of the determined index of refraction is about 2.3×10(-8), which is mainly affected by the length precision of the long vacuum cavity and the ellipticity of polarization components of the dual-frequency laser, and the range of nonambiguity is 3.0×10(-5), which is decided by the length difference of the two cavities. Experiment results show that the accuracy of air refractive index measurement is better than 5.0×10(-8) when the laboratory conditions changes slowly. The merit of the presented method is that the classical refractometry can be also used without evacuation of the gas cavity during the experiment. Furthermore, the application of the traditional synthetic wavelength method may be extended by using the wavelength equivalents of cavity, any value of which can be easily acquired by changing cavity length rather than using actual wavelengths whose number is limited. PMID:22945157

  19. Tunable negative-index photonic crystals using colloidal magnetic fluids

    NASA Astrophysics Data System (ADS)

    Geng, Tao; Wang, Xin; Wang, Yan; Dong, Xiang-Mei

    2015-12-01

    The model of using colloidal magnetic fluid to build tunable negative-index photonic crystal is established. The effective permittivity ɛe and permeability μe of the two-dimensional photonic crystal are investigated in detail. For transverse magnetic polarization, both ɛe and μe exhibit a Lorentz-type anomalous dispersion, leading to a region where ɛe and μe are simultaneously negative. Then, considering a practical case, in which the thickness of photonic crystal is finite, the band structures for odd modes are calculated by the plane wave expansion method and the finite-difference time-domain method. The results suggest that reducing the external magnetic field strength or slab thickness will weaken the periodic modulation strength of the photonic crystal. Simulation results prove that the negative-index can be tuned by varying the external magnetic field strength or the slab thickness. The work presented in this paper gives a guideline for realizing the flat photonic crystal lens with tunable properties at optical frequencies, which may have potential applications in tunable near-field imaging systems. Project supported by the National Basic Research Program of China (Grant No. 2015CB352001), the Shanghai Rising-Star Program, China (Grant No. 12QA1402300), the China Scholarship Council (CSC) Program, and the Basic Research Program of Shanghai, China (Grant No. 14ZR1428500).

  20. All-semiconductor negative-index plasmonic absorbers.

    PubMed

    Law, S; Roberts, C; Kilpatrick, T; Yu, L; Ribaudo, T; Shaner, E A; Podolskiy, V; Wasserman, D

    2014-01-10

    We demonstrate epitaxially grown all-semiconductor thin-film midinfrared plasmonic absorbers and show that absorption in these structures is linked to the excitation of highly confined negative-index surface plasmon polaritons. Strong (>98%) absorption is experimentally observed, and the spectral position and intensity of the absorption resonances are studied by reflection and transmission spectroscopy. Numerical models as well as an analytical description of the excited guided modes in our structures are presented, showing agreement with experiment. The structures investigated demonstrate a wavelength-flexible, all-semiconductor, plasmonic architecture with potential for both sensing applications and enhanced interaction of midinfrared radiation with integrated semiconductor optoelectronic elements. PMID:24483930

  1. Modulation instability in nonlinear negative-index material.

    PubMed

    Wen, Shuangchun; Wang, Youwen; Su, Wenhua; Xiang, Yuanjiang; Fu, Xiquan; Fan, Dianyuan

    2006-03-01

    We investigate modulation instability (MI) in negative-index material (NIM) with a Kerr nonlinear polarization based on a derived (3+1)-dimensional nonlinear Schrödinger equation for ultrashort pulse propagation. By a standard linear stability analysis, we obtain the expression for instability gain, which unifies the temporal, spatial, and spatiotemporal MI. It is shown that negative refraction not only brings some new features to MI, but also makes MI possible in ordinary material in which it is otherwise impossible. For example, spatial MI can occur in the defocusing regime, while it only occurs in the focusing regime in ordinary material. Spatiotemporal MI can appear in NIM in the case of anomalous dispersion and defocusing nonlinearity, while it cannot appear in ordinary material in the same case. We believe that the difference between the MI in NIM and in ordinary material is due to the fact that negative refraction reverses the sign of the diffraction term, with the signs of dispersion and nonlinearity unchanged. The most notable property of MI in NIM is that it can be manipulated by engineering the self-steepening effect by choosing the size of split-ring resonator circuit elements. To sum up the MI in ordinary material and in NIM, MI may occur for all the combinations of dispersion and nonlinearity. PMID:16605687

  2. Negative refractive index and acoustic superlens from multiple scattering in single negative metamaterials

    NASA Astrophysics Data System (ADS)

    Kaina, Nadège; Lemoult, Fabrice; Fink, Mathias; Lerosey, Geoffroy

    2015-09-01

    Metamaterials, man-made composite media structured on a scale much smaller than a wavelength, offer surprising possibilities for engineering the propagation of waves. One of the most interesting of these is the ability to achieve superlensing--that is, to focus or image beyond the diffraction limit. This originates from the left-handed behaviour--the property of refracting waves negatively--that is typical of negative index metamaterials. Yet reaching this goal requires the design of `double negative' metamaterials, which act simultaneously on the permittivity and permeability in electromagnetics, or on the density and compressibility in acoustics; this generally implies the use of two different kinds of building blocks or specific particles presenting multiple overlapping resonances. Such a requirement limits the applicability of double negative metamaterials, and has, for example, hampered any demonstration of subwavelength focusing using left-handed acoustic metamaterials. Here we show that these strict conditions can be largely relaxed by relying on media that consist of only one type of single resonant unit cell. Specifically, we show with a simple yet general semi-analytical model that judiciously breaking the symmetry of a single negative metamaterial is sufficient to turn it into a double negative one. We then demonstrate that this occurs solely because of multiple scattering of waves off the metamaterial resonant elements, a phenomenon often disregarded in these media owing to their subwavelength patterning. We apply our approach to acoustics and verify through numerical simulations that it allows the realization of negative index acoustic metamaterials based on Helmholtz resonators only. Finally, we demonstrate the operation of a negative index acoustic superlens, achieving subwavelength focusing and imaging with spot width and resolution 7 and 3.5 times better than the diffraction limit, respectively. Our findings have profound implications for the

  3. Negative refractive index and acoustic superlens from multiple scattering in single negative metamaterials.

    PubMed

    Kaina, Nadège; Lemoult, Fabrice; Fink, Mathias; Lerosey, Geoffroy

    2015-09-01

    Metamaterials, man-made composite media structured on a scale much smaller than a wavelength, offer surprising possibilities for engineering the propagation of waves. One of the most interesting of these is the ability to achieve superlensing--that is, to focus or image beyond the diffraction limit. This originates from the left-handed behavior--the property of refracting waves negatively--that is typical of negative index metamaterials. Yet reaching this goal requires the design of 'double negative' metamaterials, which act simultaneously on the permittivity and permeability in electromagnetics, or on the density and compressibility in acoustics; this generally implies the use of two different kinds of building blocks or specific particles presenting multiple overlapping resonances. Such a requirement limits the applicability of double negative metamaterials, and has, for example, hampered any demonstration of subwavelength focusing using left-handed acoustic metamaterials. Here we show that these strict conditions can be largely relaxed by relying on media that consist of only one type of single resonant unit cell. Specifically, we show with a simple yet general semi-analytical model that judiciously breaking the symmetry of a single negative metamaterial is sufficient to turn it into a double negative one. We then demonstrate that this occurs solely because of multiple scattering of waves off the metamaterial resonant elements, a phenomenon often disregarded in these media owing to their subwavelength patterning. We apply our approach to acoustics and verify through numerical simulations that it allows the realization of negative index acoustic metamaterials based on Helmholtz resonators only. Finally, we demonstrate the operation of a negative index acoustic superlens, achieving subwavelength focusing and imaging with spot width and resolution 7 and 3.5 times better than the diffraction limit, respectively. Our findings have profound implications for the

  4. Negative and positive hysteresis in double-cavity optical bistability in a three-level atom

    SciTech Connect

    Babu, H. Aswath; Wanare, Harshawardhan

    2011-03-15

    We present dual hysteretic behavior of a three-level ladder system exhibiting optical bistability in a double-cavity configuration in the mean-field limit. The two fields coupling the atomic system experience competing cooperative effects along the two transitions. We observe a hump-like feature in the bistable curve arising due to cavity-induced inversion, which transforms into a negative-hysteresis loop. Apart from negative- and positive-hysteresis regions, the system offers a variety of controllable nonlinear dynamical features, ranging from switching, periodic self-pulsing to chaos.

  5. Stability criterion for Gaussian pulse propagation through negative index materials

    SciTech Connect

    Joseph, Ancemma; Porsezian, K.

    2010-02-15

    We analyze the dynamics of propagation of a Gaussian light pulse through a medium having a negative index of refraction employing the recently reported projection operator technique. The governing modified nonlinear Schroedinger equation, obtained by taking into account the Drude dispersive model, is expressed in terms of the parameters of Gaussian pulse, called collective variables, such as width, amplitude, chirp, and phase. This approach yields a system of ordinary differential equations for the evolution of all the pulse parameters. We demonstrate the dependence of stability of the fixed-point solutions of these ordinary differential equations on the linear and nonlinear dispersion parameters. In addition, we validate the analytical approach numerically utilizing the method of split-step Fourier transform.

  6. Measuring the refractive index of thin transparent films using an extended cavity diode laser

    NASA Astrophysics Data System (ADS)

    Luetjen, Christopher; Hallsted, Jonathan; Kleinert, Michaela

    2013-12-01

    We report on a novel method for determining refractive indices of thin layers of liquids or gases, based on the use of extended cavity diode lasers. Measurements for air, water, and vegetable oil show excellent agreement with accepted values. Applications in determining the refractive index of thin optical coatings and biological cells are discussed.

  7. Microwave Propagation in Negative Index and Artificial Dielectric Media

    NASA Astrophysics Data System (ADS)

    Parimi, Patanjali; Vodo, Plarenta; Lu, Wentao; Sridhar, Srinivas

    2003-03-01

    Negative index media (NIM) are fabricated by interleaving arrays of split ring resonators and wire strips. Microwave (X-band) waveguide measurements on the NIM yield quantitative information on the material parameters, % tilden(ω)=n^' +in^' ', tilde\\varepsilon% (ω )=\\varepsilon ^' +i\\varepsilon ^' ' and tilde% μ(ω )=μ ^' +iμ ^' ' . Typical NIM features such as passband in the NIM region expected from the theoretical analysis are observed in the measured data. The n^'(ω) determined from the waveguide transmission parameters (tildeS_11,tildeS_21) is found to vary from -4.8 to-0.3 in the passband region 9.6-10.5GHz. The results show that transmission is optimized for n^' (ω ) -1 and low n^' ' . A detailed investigation of several NIM materials suggests that the characteristic properties of the NIM are dependent on the length of the material, choice of the substrate material, and continuity in the wire strips. Artificial dielectric media fabricated with arrays of wire strips exhibit a characteristic microwave plasmon mode in the X-band region, below which \\varepsilon ^' (ω )<0. Work supported by the National Science Foundation and the Air Force Research Labs, Hanscom.

  8. Mismatch Negativity (MMN) as an Index of Cognitive Dysfunction

    PubMed Central

    Näätänen, Risto; Sussman, Elyse S.; Salisbury, Dean; Shafer, Valerie L.

    2014-01-01

    Cognition is often affected in a variety of neuropsychiatric, neurological, and neurodevelopmental disorders. The neural discriminative response, reflected in mismatch negativity (MMN) and its magnetoencephalographic equivalent (MMNm), has been used as a tool to study a variety of disorders involving auditory cognition. MMN/MMNm is an involuntary brain response to auditory change or, more generally, to pattern regularity violation. For a number of disorders, MMN/MMNm amplitude to sound deviance has been shown to be attenuated or the peak-latency of the component prolonged compared to controls. This general finding suggests that while not serving as a specific marker to any particular disorder, MMN may be useful for understanding factors of cognition in various disorders, and has potential to serve as an indicator of risk. This review presents a brief history of the MMN, followed by a description of how MMN has been used to index auditory processing capability in a range of neuropsychiatric, neurological, and neurodevelopmental disorders. Finally, we suggest future directions for research to further enhance our understanding of the neural substrate of deviance detection that could lead to improvements in the use of MMN as a clinical tool. PMID:24838819

  9. Sub-picosecond optical switching with a negative index metamaterial

    SciTech Connect

    Dani, Keshav M; Upadhya, Prashant C; Zahyum, Ku

    2009-01-01

    Development of all-optical signal processing, eliminating the performance and cost penalties of optical-electrical-optical conversion, is important for continu,ing advances in Terabits/sec (Tb/s) communications.' Optical nonlinearities are generally weak, traditionally requiring long-path, large-area devicesl,2 or very high-Q, narrow-band resonator structures.3 Optical metamaterials offer unique capabilities for optical-optical interactions. Here we report 600 femtosecond (fs) all-optical modulation using a fIShnet (2D-perforated metallamorphous-Si (a-Si)/metal film stack) negative-index meta material with a structurally tunable broad-band response near 1.2 {micro}m. Over 20% modulation (experimentally limited) is achieved in a path length of only 116 nm by photo-excitation of carriers in the a-Si layer. This has the potential for Tb/s aU-optical communication and will lead to other novel, compact, tunable sub-picosecond (ps) photonic devices.

  10. Cavity Ringdown Technique for negative-hydrogen-ion measurement in ion source for neutral beam injector

    NASA Astrophysics Data System (ADS)

    Nakano, H.; Tsumori, K.; Shibuya, M.; Geng, S.; Kisaki, M.; Ikeda, K.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.

    2016-03-01

    The Cavity Ringdown Technique (CRD) is applied for negative hydrogen ion (H-) density measurement in H- source for the neutral beam injector. The CRD is one of the laser absorption techniques. Nd:YAG pulse laser was utilized for negative-hydrogen-ion photodetachment. The H- density related to extracted H- beam was successfully observed by a fixed position CRD. A two-dimensional movable CRD has been developed to measure the H- density profile. Measured profiles were consistent with expected profiles from the H- production area in pure hydrogen and cesium seeded plasmas. By applying absorption saturation in the optical cavity, negative hydrogen ion temperature was evaluated and was confirmed as being a similar value measured with other diagnostics.

  11. Differential refractive index sensor based on photonic molecules and defect cavities.

    PubMed

    Andueza, Ángel; Pérez-Conde, Jesús; Sevilla, Joaquín

    2016-08-01

    We present a novel differential refractive index sensor prototype based on a matrix of photonic molecules (PM) of soda-lime glass cylinders (εc = 4.5) and two defect cavities. The measured and simulated spectra in the microwave range (8-12 GHz) show a wide photonic stop band with two localized states: the reference state, bound to a decagonal ring of cylinders and the sensing state, bound to the defect cavities. The defect mode is very sensitive to the permittivity of the material inserted in the cavity while the state in the PM remains unperturbed. We find that the response of the sensor is linear. These results can be extrapolated to the visible range due to scale invariance of Maxwell equations. PMID:27505844

  12. Effective index model predicts modal frequencies of vertical-cavity lasers

    SciTech Connect

    SERKLAND,DARWIN K.; HADLEY,G. RONALD; CHOQUETTE,KENT D.; GEIB,KENT M.; ALLERMAN,ANDREW A.

    2000-04-18

    Previously, an effective index optical model was introduced for the analysis of lateral waveguiding effects in vertical-cavity surface-emitting lasers. The authors show that the resultant transverse equation is almost identical to the one typically obtained in the analysis of dielectric waveguide problems, such as a step-index optical fiber. The solution to the transverse equation yields the lateral dependence of the optical field and, as is recognized in this paper, the discrete frequencies of the microcavity modes. As an example, they apply this technique to the analysis of vertical-cavity lasers that contain thin-oxide apertures. The model intuitively explains the experimental data and makes quantitative predictions in good agreement with a highly accurate numerical model.

  13. Optical fiber Fabry-Perot interferometer cavity fabricated by femtosecond laser micromachining and fusion splicing for refractive index sensing.

    PubMed

    Liao, C R; Hu, T Y; Wang, D N

    2012-09-24

    We demonstrate a fiber in-line Fabry-Perot interferometer cavity sensor for refractive index measurement. The interferometer cavity is formed by drilling a micro-hole at the cleaved fiber end facet, followed by fusion splicing. A micro-channel is inscribed by femtosecond laser micromachining to vertically cross the cavity to allow liquid to flow in. The refractive index sensitivity obtained is ~994 nm/RIU (refractive index unit). Such a device is simple in configuration, easy for fabrication and reliable in operation due to extremely low temperature cross sensitivity of ~4.8 × 10(-6) RIU/°C. PMID:23037431

  14. Apoptotic Index and Proliferative Index in Premalignant and Malignant Squamous Cell Lesions of the Oral Cavity

    PubMed Central

    Viswanathan, Vidya; Juluri, Ravichandra; Goel, Seema; Madan, Jyotsna; Mitra, Subir K; Gopalakrishnan, Dharmarajan

    2015-01-01

    Background: Oral squamous cell lesions are most commonly diagnosed lesions in India. Both premalignant and malignant lesions are frequently encountered. In this study, we evaluated the role and significance of apoptotic indices (AI) and proliferative indices (PI) in premalignant and malignant squamous cell lesions of the oral cavity. Materials and Methods: A total of 62 histologically proven cases of premalignant and malignant oral squamous cell lesions were analyzed. The biopsies were stained with hematoxylin and eosin and also with monoclonal antibody Ki-67. AI and PI were assessed using a light microscope. Results: AI was found to increase gradually from normal to dysplasia to carcinoma. The highest AI was seen in well-differentiated squamous cell carcinomas (SCCs). PI also was found to increase significantly from normal to dysplasia to carcinoma. The highest PI was seen in poorly differentiated SCC. Conclusion: AI in conjunction with the PI offers an accurate idea as to the nature and course of the lesion and may help to plan timely surgical intervention that results in better clinical prognosis and outcome. PMID:25709366

  15. Impact of a large negative gain-to-cavity wavelength detuning on the performance of InGaAlAs oxide-confined vertical-cavity surface-emitting lasers

    NASA Astrophysics Data System (ADS)

    Blokhin, Sergey A.; Bobrov, Mikhail A.; Maleev, Nikolai A.; Kuzmenkov, Alexander G.; Sakharov, Alexey V.; Blokhin, Alexey A.; Moser, Philip; Lott, James A.; Bimberg, Dieter; Ustinov, Viktor M.

    2015-03-01

    Vertical-cavity surface-emitting lasers (VCSELs) based on the InGaAlAs-materials system on GaAs substrates are the key component for short-reach data and computer communications systems. Several different modulation schemes have been developed to realize high data bit rates based on various oxide-confined near-infrared VCSEL designs operated under direct current modulation. However, one open question to resolve is the optimal gain-to-cavity wavelength detuning to employ for temperature-stable high-speed performance. We investigate the static and dynamic characteristics of 850 nm high-speed oxide-confined VCSELs with different negative gain-to-cavity wavelength detunings. Our oxideconfined 850 nm VCSELs with a more common ~10 nm negative gain-to-cavity detuning demonstrate the conventional optical mode behavior with a classical single-resonance frequency response. With a larger (≥ 20 nm) negative detuning, our devices with large oxide-aperture size (>6 μm) show an anomalous start of lasing via higher order modes with a subsequent switching to lasing via the lowest order modes at higher currents. At intermediate currents, co-lasing via two types of transverse modes and a two-resonance modulation response is observed. The increase of operation temperature as well as the reduction in the oxide-aperture area resulted in classical lasing of index-guided VCSELs. The observed optical mode behavior can be attributed to the specific index guiding profile caused by the oxide-apertures, low internal optical losses, and the large gain-to-cavity detuning. Moreover, one can suggest that the complex shape of the modulation response results from the mode competition for the available gain during an interesting co-lasing operating regime.

  16. Differential refractive index sensor based on photonic molecules and defect cavities

    NASA Astrophysics Data System (ADS)

    Andueza, Ángel; Pérez-Conde, Jesús; Sevilla, Joaquín

    2016-08-01

    We present a novel differential refractive index sensor based on arrays of photonic molecules (PM) of dielectric cylinders and two structural defect cavities. The transmission spectrum of the photonic proposed structure as sensor shows a wide photonic stop band with two localized states. One of them, the reference state, is bound to a decagonal ring of cylinders and the other, the sensing state, to the defect cavities of the lattice. It is shown that defect mode is very sensitive to the presence of materials with dielectric permittivity different from that of the surrounding cylinders while the state in the PM is not affected by their presence. This behavior allows to design a device for sensing applications. A prototype of the sensor, in the microwave region, was built using a matrix of 3x2 PM arrays made of soda-lime glass cylinders (dielectric permittivity of 4.5). The transmission spectra was measured in the microwave range (8-12 GHz) with samples of different refractive index inserted in the defect cavities. Simulations with Finite Integration time-domain Method are in good agreement with experiments. We find that the response of the sensor is linear. Device measurement range is determined by the dielectric constant of the cylinders that make up the device. The results here presented in the microwave region can be extrapolated to the visible range due to scale invariance of Maxwell equations. This make our prototype a promising structure as sensor also in the optical range.

  17. Are the anterior negativities to grammatical violations indexing working memory?

    PubMed

    Martín-Loeches, Manuel; Muñoz, Francisco; Casado, Pilar; Melcón, A; Fernández-Frías, C

    2005-09-01

    Anterior negativities obtained when a grammatical rule is violated may reflect highly automatic first-pass parsing processes, the detection of a morphosyntactic mismatch, and/or the inability to assign the incoming word to the current phrase structure. However, for some theorists these negativities rather reflect some aspect of working memory processes. Event-related brain potentials (ERPs) obtained for word category and morphosyntactic violations were directly compared with effects obtained when working memory is particularly demanded (embedding subject- or object-relative clauses), yielding a significant dissociation in terms of topography. Even though, the anterior negativities for grammatical violations vanished when relative clauses were embedded, suggesting that the processes reflected by anterior negativities related to grammatical violations and those related to working memory manipulations, even if different, are placing demands on a common pool of limited resources. PMID:16176373

  18. Low-loss negative index metamaterials for X, Ku, and K microwave bands

    SciTech Connect

    Lee, David A.; Vedral, L. James; Smith, David A.; Pinchuk, Anatoliy O.; Musselman, Randall L.

    2015-04-15

    Low-loss, negative-index of refraction metamaterials were designed and tested for X, Ku, and K microwave frequency bands. An S-shaped, split-ring resonator was used as a unit cell to design homogeneous slabs of negative-index metamaterials. Then, the slabs of metamaterials were cut unto prisms to measure experimentally the negative index of refraction of a plane electromagnetic wave. Theoretical simulations using High-Frequency Structural Simulator, a finite element equation solver, were in good agreement with experimental measurements. The negative index of refraction was retrieved from the angle- and frequency-dependence of the transmitted intensity of the microwave beam through the metamaterial prism and compared well to simulations; in addition, near-field electromagnetic intensity mapping was conducted with an infrared camera, and there was also a good match with the simulations for expected frequency ranges for the negative index of refraction.

  19. Negative-index media for matter-wave optics.

    PubMed

    Baudon, J; Hamamda, M; Grucker, J; Boustimi, M; Perales, F; Dutier, G; Ducloy, M

    2009-04-10

    We consider the extension of optical metamaterials to matter waves and then the down scaling of metaoptics to nanometric wavelengths. We show that the generic property of pulsed comoving magnetic fields allows us to fashion the wave-number dependence of the atomic phase shift. It can be used to produce a transient negative group velocity of an atomic wave packet, which results into a negative refraction of the matter wave. Application to slow metastable argon atoms Ar(3P2) shows that the device is able to operate either as an efficient beam splitter or an atomic metalens. PMID:19392417

  20. Photonic crystal nanoslotted parallel quadrabeam integrated cavity for refractive index sensing with high figure of merit

    NASA Astrophysics Data System (ADS)

    Yang, Daquan; Tian, Huiping; Ji, Yuefeng

    2015-06-01

    Sensitivities (S) and quality factors (Q) have been trade-offs in optical resonator sensors, and optimal geometry that maximizes both factors is under active development. In this paper, we experimentally demonstrate an optical sensor based on photonic crystal (PhC) nanoslotted parallel quadrabeam integrated cavity (NPQIC) with high figure of merit (FOM). Both high sensitivity (S) of 451 nm/RIU (refractive index unit) and Q-factor >7000 in water at telecom wavelength range have been achieved simultaneously, which features a sensor figure of merit (FOM) >2000, an order of magnitude improvement over previous photonic crystal sensors.

  1. High efficiency quantum dot and organic LEDs with a back-cavity and a high index substrate

    NASA Astrophysics Data System (ADS)

    Liang, Haowen; Luo, Zhenyue; Zhu, Ruidong; Dong, Yajie; Lee, Jiun-Haw; Zhou, Jianying; Wu, Shin-Tson

    2016-04-01

    We report a back-cavity design to enhance the optical efficiency of a quantum dot light-emitting diode (QLED) or an organic light-emitting diode (OLED) for display and lighting applications. Our simulation results show that the back-cavity design exhibits two major advantages: (1) the transparent electrode helps to increase the transmittance of backward light despite using a semi-transparent metal electrode, and (2) the thickness of the low index optical buffer layer can be optimized to modify the proportion of each optical channel. The proposed back-cavity also helps to lower the refractive index of the high-index substrate from ~2.0 to ~1.8 for achieving high optical efficiency. Finally, the introduced back-cavity does not degrade the color performance of the QLED/OLED.

  2. Design of a cavity ring-down spectroscopy diagnostic for negative ion rf source SPIDER

    SciTech Connect

    Pasqualotto, R.; Alfier, A.; Lotto, L.

    2010-10-15

    The rf source test facility SPIDER will test and optimize the source of the 1 MV neutral beam injection systems for ITER. Cavity ring-down spectroscopy (CRDS) will measure the absolute line-of-sight integrated density of negative (H{sup -} and D{sup -}) ions, produced in the extraction region of the source. CRDS takes advantage of the photodetachment process: negative ions are converted to neutral hydrogen atoms by electron stripping through absorption of a photon from a laser. The design of this diagnostic is presented with the corresponding simulation of the expected performance. A prototype operated without plasma has provided CRDS reference signals, design validation, and results concerning the signal-to-noise ratio.

  3. On the resolution of lenses made of a negative-index material

    SciTech Connect

    Petrin, A B

    2013-09-30

    Resolution of the lenses made of a negative-index material is considered. It is shown that the super-resolution concept is untenable and the possibility of obtaining a perfect image on its own eventually contradicts Maxwell's equations in vacuum. It is also shown that known limitations of the diffraction theory on resolution of optical instruments hold true for the resolution of lenses of a negative-index material, in particular, the resolution of a Veselago lens. (nanogradient dielectric coatings and metamaterials)

  4. Optically pumped GaN vertical cavity surface emitting laser with high index-contrast nanoporous distributed Bragg reflector.

    PubMed

    Lee, Seung-Min; Gong, Su-Hyun; Kang, Jin-Ho; Ebaid, Mohamed; Ryu, Sang-Wan; Cho, Yong-Hoon

    2015-05-01

    Laser operation of a GaN vertical cavity surface emitting laser (VCSEL) is demonstrated under optical pumping with a nanoporous distributed Bragg reflector (DBR). High reflectivity, approaching 100%, is obtained due to the high index-contrast of the nanoporous DBR. The VCSEL system exhibits low threshold power density due to the formation of high Q-factor cavity, which shows the potential of nanoporous medium for optical devices. PMID:25969197

  5. Air cavity-based Fabry-Perot interferometer sensor fabricated using a sawing technique for refractive index measurement

    NASA Astrophysics Data System (ADS)

    Jung, Eun Joo; Lee, Woo-Jin; Kim, Myoung Jin; Hwang, Sung Hwan; Rho, Byung Sup

    2014-01-01

    We have demonstrated a refractive index sensor based on a fiber optic Fabry-Perot (FP) interferometer with an open air cavity fabricated using a one-step mechanical sawing technique. The sensor head consists of a short FP cavity near the fiber patch cord tip, which was assembled by joining a ceramic ferrule and a single-mode fiber together. Owing to the open air cavity in the sensor head, various liquid samples with different refractive index can fill in-line air cavity, which makes the device usable as a refractometer. Moreover, due to the sensor head encircled with the robust ceramic ferrule, the device is attractive for sensing measurement in harsh environments. The sensor was tested in different refractive index solutions. The experimental result shows that the attenuation peak wavelength of the sensor is shifted toward a shorter wavelength with increasing refractive index, and the refractive index sensitivity is ˜92.5 nm/refractive index unit (RIU) and 73.75 dB/RIU. The proposed sensor can be used as an in-line refractometer for many potential applications in the sensing field.

  6. Self-organization of dissipationless solitons in positive- and negative-refractive-index materials

    SciTech Connect

    Skarka, V.; Aleksic, N. B.; Berezhiani, V. I.

    2010-04-15

    A generalized Ginzburg-Landau equation describing dissipative solitons dynamics in negative-refractive-index materials is derived from Maxwell equations. This equation having only real terms with opposite sign differs from the usual Ginzburg-Landau equation for positive-refractive-index media. A cross-compensation between the saturating nonlinearity excess, losses, and gain makes obtained self-organized solitons dissipationless and exceptionally robust. In the presence of such solitons medium becomes effectively dissipationless. The compensation of losses is of particular interest for media with resonant character of interactions like negative-refractive-index materials.

  7. Cavities

    MedlinePlus

    ... The tooth may hurt even without stimulation (spontaneous toothache). If irreversible damage to the pulp occurs and ... To detect cavities early, a dentist inquires about pain, examines the teeth, probes the teeth with dental instruments, and may take x-rays. People should ...

  8. A point radiator parallel to a plane layer with negative refractive index

    SciTech Connect

    Petrin, A. B.

    2008-09-15

    Focusing of an electromagnetic wave radiated by a point source and transmitted through a plane layer filled with a medium with negative refractive index is considered. An elementary electric Hertzian dipole located in the air (or vacuum) parallel to the boundaries of the layer is considered as a point source of radiation. It is rigorously shown that, after transmitting through a layer with negative refractive index, the electromagnetic wave of the dipole is focused into a certain domain. The dimensions of the focusing region are investigated. The results of the investigation show that the use of homogeneous materials with negative refraction does not allow one to overcome the diffraction limit.

  9. Age estimation standards for a Western Australian population using the coronal pulp cavity index.

    PubMed

    Karkhanis, Shalmira; Mack, Peter; Franklin, Daniel

    2013-09-10

    Age estimation is a vital aspect in creating a biological profile and aids investigators by narrowing down potentially matching identities from the available pool. In addition to routine casework, in the present global political scenario, age estimation in living individuals is required in cases of refugees, asylum seekers, human trafficking and to ascertain age of criminal responsibility. Thus robust methods that are simple, non-invasive and ethically viable are required. The aim of the present study is, therefore, to test the reliability and applicability of the coronal pulp cavity index method, for the purpose of developing age estimation standards for an adult Western Australian population. A total of 450 orthopantomograms (220 females and 230 males) of Australian individuals were analyzed. Crown and coronal pulp chamber heights were measured in the mandibular left and right premolars, and the first and second molars. These measurements were then used to calculate the tooth coronal index. Data was analyzed using paired sample t-tests to assess bilateral asymmetry followed by simple linear and multiple regressions to develop age estimation models. The most accurate age estimation based on simple linear regression model was with mandibular right first molar (SEE ±8.271 years). Multiple regression models improved age prediction accuracy considerably and the most accurate model was with bilateral first and second molars (SEE ±6.692 years). This study represents the first investigation of this method in a Western Australian population and our results indicate that the method is suitable for forensic application. PMID:23664550

  10. Negative running of the spectral index, hemispherical asymmetry and the consistency of Planck with large r

    SciTech Connect

    McDonald, John

    2014-11-01

    Planck favours a negative running of the spectral index, with the likelihood being dominated by low multipoles l ∼< 50 and no preference for running at higher l. A negative spectral index is also necessary for the 2- Planck upper bound on the tensor-to-scalar ratio r to be consistent with values significantly larger than 0.1. Planck has also observed a hemispherical asymmetry of the CMB power spectrum, again mostly at low multipoles. Here we consider whether the physics responsible for the hemispherical asymmetry could also account for the negative running of the spectral index and the consistency of Planck with a large value of r. A negative running of the spectral index can be generated if the hemispherical asymmetry is due to a scale- and space-dependent modulation which suppresses the CMB power spectrum at low multipoles. We show that the observed hemispherical asymmetry at low l can be generated while satisfying constraints on the asymmetry at higher l and generating a negative spectral index of the right magnitude to account for the Planck observation and to allow Planck to be consistent with a large value of r.

  11. Whispering gallery mode selective reflector with a high azimuthal index for the input cavity of a gyroklystron

    NASA Astrophysics Data System (ADS)

    Danilov, Yu. Yu.

    2014-07-01

    A selective reflector in the form of a resonance extension is suggested for the input cavity of a 8-mm-wave gyroklystron operating at whispering gallery mode H m, 1 with an azimuthal index of several tens. Simulation data for the selective reflector are presented.

  12. A cluster of many small holes with negative imaginary surface impedances may generate a negative refraction index

    NASA Astrophysics Data System (ADS)

    Alsaedi, Ahmed; Ahmad, Bashir; Challa, Durga Prasad; Kirane, Mokhtar; Sini, Mourad

    2016-09-01

    We deal with the scattering of an acoustic medium modeled by an index of refraction $n$ varying in a bounded region $\\Omega$ of $\\mathbb{R}^3$ and equal to unity outside $\\Omega$. This region is perforated with an extremely large number of small holes $D_m$'s of maximum radius $a$, $a<<1$, modeled by surface impedance functions. Precisely, we are in the regime described by the number of holes of the order $M:=O(a^{\\beta-2})$, the minimum distance between the holes is $d\\sim a^t$ and the surface impedance functions of the form $\\lambda_m \\sim \\lambda_{m,0} a^{-\\beta}$ with $\\beta >0$ and $\\lambda_{m,0}$ being constants and eventually complex numbers. Under some natural conditions on the parameters $\\beta, t$ and $\\lambda_{m,0}$, we characterize the equivalent medium generating, approximately, the same scattered waves as the original perforated acoustic medium. We give an explicit error estimate between the scattered waves generated by the perforated medium and the equivalent one respectively, as $a \\rightarrow 0$. As applications of these results, we discuss the following findings: 1. If we choose negative valued imaginary surface impedance functions, attached to each surface of the holes, then the equivalent medium behaves as a passive acoustic medium only if it is an acoustic metamaterial with index of refraction $\\tilde{n}(x)=-n(x),\\; x \\in \\Omega$ and $\\tilde{n}(x)=1,\\; x \\in \\mathbb{R}^3\\setminus{\\overline{\\Omega}}$. This means that, with this process, we can switch the sign of the index of the refraction from positive to negative values. 2. We can choose the surface impedance functions attached to each surface of the holes so that the equivalent index of refraction $\\tilde{n}$ is $\\tilde{n}(x)=1,\\; x \\in \\mathbb{R}^3$. This means that the region $\\Omega$ modeled by the original index of refraction $n$ is approximately cloaked.

  13. Focus modulation of cylindrical vector beams through negative-index grating lenses

    NASA Astrophysics Data System (ADS)

    Wang, Shengming; Xu, Ji; Zhong, Yi; Ren, Rong; Lu, Yunqing; Wan, Hongdan; Wang, Jin; Ding, Jianping

    2016-08-01

    A cylindrically symmetric negative-index grating lens composed of unitary material is proposed as an effective method to modulate the focusing of cylindrical vector beams (CVBs). The grating parameters are designed to obtain an appropriate negative index, and the lens profile is tailored to realize the constructive interference. The plano-concave lens is parameterized to achieve desired focal length and the plano-cone lens is proposed to obtain large depth of focus. An optical needle is generated with radially polarized incidence, and an optical tube is achieved with incidence of azimuthal polarization. Moreover, the presented modulation methods can be applied for any arbitrary polarized CVBs. This work offers a more flexible and effective approach to design negative-index lenses for subwavelength focusing of CVBs, which has potential application value in related areas, such as optical trapping, and other nano-optics fields.

  14. Negative-index gratings formed by femtosecond laser overexposure and thermal regeneration

    PubMed Central

    He, Jun; Wang, Yiping; Liao, Changrui; Wang, Chao; Liu, Shen; Yang, Kaiming; Wang, Ying; Yuan, Xiaocong; Wang, Guo Ping; Zhang, Wenjing

    2016-01-01

    We demonstrate a method for the preparation of negative-index fibre Bragg gratings (FBGs) using 800 nm femtosecond laser overexposure and thermal regeneration. A positive-index type I-IR FBG was first inscribed in H2-free single-mode fibre using a femtosecond laser directed through a phase mask, and then a highly polarization dependant phase-shifted FBG (P-PSFBG) was fabricated from the type I-IR FBG by overexposure to the femtosecond laser. Subsequently, the P-PSFBG was thermally annealed at 800 °C for 12 hours. Grating regeneration was observed during thermal annealing, and a negative-index FBG was finally obtained with a high reflectivity of 99.22%, an ultra-low insertion loss of 0.08 dB, a blueshift of 0.83 nm in the Bragg wavelength, and an operating temperature of up to 1000 °C for more than 10 hours. Further annealing tests showed that the thermal stability of the negative-index FBG was lower than that of a type II-IR FBG, but much higher than that of a type I-IR FBG. Moreover, the formation of such a negative-index grating may result from thermally regenerated type IIA photosensitivity. PMID:26979090

  15. Modulation instability in a triangular three-core coupler with a negative-index material channel

    NASA Astrophysics Data System (ADS)

    Shafeeque Ali, A. K.; Nithyanandan, K.; Porsezian, K.; Maimistov, Andrei I.

    2016-03-01

    A theoretical investigation of the modulation instability (MI) in the three core triangular oppositely directed coupler with negative index material channel is presented. This class of couplers have an effective feedback mechanism due to the opposite directionality of the phase velocities in the negative and positive index channels. It is found that the MI in the nonlinear three core triangular oppositely directed coupler is significantly influenced by the ratio of the forward- to backward-propagating wave power and nonlinearity. Also, in the case of the normal dispersion regime a threshold-like behavior is observed, whereas this behavior is not identified in the anomalous dispersion regime. For the asymmetric case (h\

  16. Three-dimensional negative index of refraction at optical frequencies by coupling plasmonic waveguides.

    PubMed

    Verhagen, Ewold; de Waele, René; Kuipers, L; Polman, Albert

    2010-11-26

    We identify a route towards achieving a negative index of refraction at optical frequencies based on coupling between plasmonic waveguides that support backwards waves. We show how modal symmetry can be exploited in metal-dielectric waveguide pairs to achieve negative refraction of both phase and energy. Control of waveguide coupling yields a metamaterial consisting of a one-dimensional multilayer stack that exhibits an isotropic index of -1 at a free-space wavelength of 400 nm. The concepts developed here may inspire new low-loss metamaterial designs operating close to the metal plasma frequency. PMID:21231386

  17. Three-Dimensional Negative Index of Refraction at Optical Frequencies by Coupling Plasmonic Waveguides

    NASA Astrophysics Data System (ADS)

    Verhagen, Ewold; de Waele, René; Kuipers, L.; Polman, Albert

    2010-11-01

    We identify a route towards achieving a negative index of refraction at optical frequencies based on coupling between plasmonic waveguides that support backwards waves. We show how modal symmetry can be exploited in metal-dielectric waveguide pairs to achieve negative refraction of both phase and energy. Control of waveguide coupling yields a metamaterial consisting of a one-dimensional multilayer stack that exhibits an isotropic index of -1 at a free-space wavelength of 400 nm. The concepts developed here may inspire new low-loss metamaterial designs operating close to the metal plasma frequency.

  18. Tunable resonant-cavity-enhanced photodetector with double high-index-contrast grating mirrors

    NASA Astrophysics Data System (ADS)

    Learkthanakhachon, Supannee; Yvind, Kresten; Chung, Il-Sug

    2013-03-01

    In this paper, we propose a broadband-tunable resonant-cavity-enhanced photodetector (RCE-PD) structure with double high-index-contrast grating (HCG) mirrors and numerically investigate its characteristics. The detector is designed to operate at 1550-nm wavelength. The detector structure consists of a top InP HCG mirror, a p-i-n photodiode embedding multiple quantum wells, and a Si HCG mirror formed in the Si layer of a silicon-on-insulator wafer. The detection wavelength can be changed by moving the top InP HCG mirror suspended in the air. High reflectivity and small penetration length of HCGs lead to a narrow absorption linewidth of 0.38 nm and a broad tuning range of 111 nm. The peak absorption efficiency is 76-84% within the tuning range. This broadband-tunable and narrow-absorption-linewidth RCE-PD is desirable for applications where selective wavelength demultiplexing is required. Furthermore, the fact that it can be fabricated on a silicon platform offers us a possibility of integration with electronics.

  19. Boosting figures of merit of cavity plasmon resonance based refractive index sensing in dielectric-metal core-shell resonators.

    PubMed

    Li, Zhiqin; Sun, Ren; Zhang, Chi; Wan, Mingjie; Gu, Ping; Shen, Qi; Chen, Zhuo; Wang, Zhenling

    2016-08-22

    We theoretically investigate the sensing performance of the dielectric-metal core-shell resonators (DMCSRs) that support multipolar sharp magnetic and electric-based cavity plasmon resonances. We show that at the cavity resonances the ability of the DMCSRs to strongly confine the optical fields inside the cavity is robust against the existence of nano-openings in the metal shell layer. As a result, both the perfect DMCSRs having a complete metal shell layer and the non-perfect DMCSRs with nano-openings in the metal shell layers exhibit high refractive index sensitivities of 700 ~1200 nm/RIU. Furthermore, we demonstrate that such high refractive index sensitivities could be well maintained in an array of interconnected non-perfect DMCSRs. The narrow linewidths of the cavity plasmon resonances coupled with their high index sensitivities make the array of non-perfect DMCSRs possess high figure of merit (FOM) values up to ~88, approaching the theoretically estimated upper limit (FOM ≈108) for gold standard prism coupled surface-plasmon sensors. PMID:27557265

  20. Chiral metamaterials with negative refractive index based on four “U” split ring resonators

    SciTech Connect

    Li, Zhaofeng; Zhao, Rongkuo; Koschny, Thomas; Kafesaki, Maria; Alici, Kamil Boratay; Colak, Evrim; Caglayan, Humeyra; Ozbay, Ekmel; Soukoulis, C.M.

    2010-08-23

    A uniaxial chiral metamaterial is constructed by double-layered four 'U' split ring resonators mutually twisted by 90{sup o}. It shows a giant optical activity and circular dichroism. The retrieval results reveal that a negative refractive index is realized for circularly polarized waves due to the large chirality. The experimental results are in good agreement with the numerical results.

  1. Negative refractive index, perfect lenses and checkerboards: Trapping and imaging effects in folded optical spaces

    NASA Astrophysics Data System (ADS)

    Guenneau, Sébastien; Ramakrishna, S. Anantha

    2009-06-01

    Newly discovered metamaterials have opened new vistas for better control of light via negative refraction, whereby light refracts in the "wrong" manner. These are dielectric and metallic composite materials structured at subwavelength lengthscales. Their building blocks consist of local resonators such as conducting thin bars and split rings driving the material parameters such as the dielectric permittivity and magnetic permeability to negative (complex) values. Combined together, these structural elements can bring about a (complex valued) negative effective refractive index for the Snell-Descartes law and result in negative refraction of radiation. Negative refractive index materials can support a host of surface plasmon states for both polarizations of light. This makes possible unique effects such as imaging with subwavelength image resolution through the Pendry-Veselago slab lens. Other geometries have also been investigated, such as cylindrical or spherical lenses that enable a magnification of images with subwavelength resolution. Superlenses of three-fold (equilateral triangle), four-fold (square) and six-fold (hexagonal) geometry allow for multiple images, respectively two, three, and five. Generalization to rectangular and triangular checkerboards consisting of alternating cells of positive and negative refractive index represents a very singular situation in which the density of modes diverges at the corners, with an infinity of images. Sine-cosecant anisotropic heterogeneous square and triangular checkerboards can be respectively mapped onto three-dimensional cubic and icosahedral corner lenses consisting of alternating positive and negative refractive regions. All such systems with corners between negative and positive refractive media display very singular behavior with the local density of states becoming infinitely large at the corner, in the limit of no dissipation. We investigate all of these, using the unifying viewpoint of transformation optics

  2. Optical fiber Fabry-Perot interferometer cavity fabricated by femtosecond laser-induced water breakdown for refractive index sensing.

    PubMed

    Liu, Yi; Qu, Shiliang

    2014-01-20

    The Fabry-Perot interferometer (FPI) cavity in a single-mode fiber with two open faces was fabricated by using the method of femtosecond laser-induced water breakdown. Then the FPI cavity was annealed by the arc discharge to greatly smooth its internal surface. The whole fabrication process features simple operation and high efficiency. The fabricated FPI cavity exhibits a perfect interferometer spectrum with reflection loss of only -3 dB and fringe visibility of almost 30 dB. It can be used as a perfectly reliable liquid refractive index sensor, as it exhibits high sensitivity (1147.48 nm/RIU), good linearity (99.93%), good repeatability, high actual measurement accuracy (1.29×10(-4)RIU), large measurement range, and good temperature insensitive characteristic. PMID:24514135

  3. A single-layer wide-angle negative-index metamaterial at visible freque

    SciTech Connect

    Burgos, Stanley P.; de Waele, Rene; Polman, Albert; Atwater, Harry A.

    2010-04-18

    Metamaterials are materials with artificial electromagnetic properties defined by their sub-wavelength structure rather than their chemical composition. Negative-index materials (NIMs) are a special class of metamaterials characterized by an effective negative index that gives rise to such unusual wave behaviour as backwards phase propagation and negative refraction. These extraordinary properties lead to many interesting functions such as sub-diffraction imaging and invisibility cloaking. So far, NIMs have been realized through layering of resonant structures, such as split-ring resonators, and have been demonstrated at microwave to infrared frequencies over a narrow range of angles-of-incidence and polarization. However, resonant-element NIM designs suffer from the limitations of not being scalable to operate at visible frequencies because of intrinsic fabrication limitations, require multiple functional layers to achieve strong scattering and have refractive indices that are highly dependent on angle of incidence and polarization. Here we report a metamaterial composed of a single layer of coupled plasmonic coaxial waveguides that exhibits an effective refractive index of -2 in the blue spectral region with a figure-of-merit larger than 8. The resulting NIM refractive index is insensitive to both polarization and angle-of-incidence over a ±50° angular range, yielding a wide-angle NIM at visible frequencies.

  4. A single-layer wide-angle negative-index metamaterial at visible frequencies.

    PubMed

    Burgos, Stanley P; de Waele, Rene; Polman, Albert; Atwater, Harry A

    2010-05-01

    Metamaterials are materials with artificial electromagnetic properties defined by their sub-wavelength structure rather than their chemical composition. Negative-index materials (NIMs) are a special class of metamaterials characterized by an effective negative index that gives rise to such unusual wave behaviour as backwards phase propagation and negative refraction. These extraordinary properties lead to many interesting functions such as sub-diffraction imaging and invisibility cloaking. So far, NIMs have been realized through layering of resonant structures, such as split-ring resonators, and have been demonstrated at microwave to infrared frequencies over a narrow range of angles-of-incidence and polarization. However, resonant-element NIM designs suffer from the limitations of not being scalable to operate at visible frequencies because of intrinsic fabrication limitations, require multiple functional layers to achieve strong scattering and have refractive indices that are highly dependent on angle of incidence and polarization. Here we report a metamaterial composed of a single layer of coupled plasmonic coaxial waveguides that exhibits an effective refractive index of -2 in the blue spectral region with a figure-of-merit larger than 8. The resulting NIM refractive index is insensitive to both polarization and angle-of-incidence over a +/-50 degree angular range, yielding a wide-angle NIM at visible frequencies. PMID:20400955

  5. Active suppression of air refractive index fluctuation using a Fabry-Perot cavity and a piezoelectric volume actuator

    SciTech Connect

    Banh, Tuan Quoc; Ohkubo, Yuria; Murai, Yoshinosuke; Aketagawa, Masato

    2011-01-01

    Air refractive index fluctuation ({Delta}n{sub air}) is one of the largest uncertainty sources in precision interferometry systems that require a resolution of nanometer order or less. We introduce a method for the active suppression of {Delta}n{sub air} inside a normal air-environment chamber using a Fabry-Perot cavity and a piezoelectric volume actuator. The temporal air refractive index (n{sub air}) at a local point is maintained constant with an expanded uncertainty of {approx}4.2x10{sup -9} (k=2), a sufficiently low uncertainty for precise measurements unaffected by {Delta}n{sub air} to be made inside a chamber.

  6. Low-loss multilayered metamaterial exhibiting a negative index of refraction at visible wavelengths

    NASA Astrophysics Data System (ADS)

    Garcia-Meca, Carlos

    2012-02-01

    Over the last decade, metamaterials have attracted a great interest thanks to their potential to expand the range of electromagnetic properties found in natural materials. In particular, the possibility of achieving negative refractive index media (NIM) enables us to implement superlenses and optical storing devices. Since the first experimental demonstration at microwave frequencies, much effort has been put in extending negative refraction to the visible spectrum, where we can take full advantage of NIM properties. For instance, the superior imaging ability of NIM would be essential for visible microscopy. The desired features for NIM are low loss and isotropy. This last property includes polarization independence and negative-index behavior in all spatial directions. None of these features have been attained in previous experiments. Thus, the current challenge is to improve such aspects in order to make NIM suitable for practical applications. In this work, we experimentally demonstrate a low-loss multilayer metamaterial exhibiting a double-negative index in the visible spectrum, while presenting polarization independence at normal incidence. This has been achieved by exploiting the properties of a second-order magnetic resonance of the so-called fishnet structure, in contrast to previous works that used first-order magnetic resonances, both related to gap surface plasmon polariton (SPP) modes. The low-loss nature of the employed magnetic resonance, together with the effect of the interacting adjacent layers, results in a figure of merit as high as 3.34. A wide spectral range of negative index is achieved, covering the wavelength region between 620 and 806 nm with only two different designs. The fabricated metamaterials are the first experimental multilayer NIM in the visible spectrum, which entails an important step towards homogeneous NIM in this range. Finally, we found that the SPP modes determining the permeability resonance display weak angular dispersion.

  7. Simultaneous measurement of temperature and refractive index using focused ion beam milled Fabry-Perot cavities in optical fiber micro-tips.

    PubMed

    André, Ricardo M; Warren-Smith, Stephen C; Becker, Martin; Dellith, Jan; Rothhardt, Manfred; Zibaii, M I; Latifi, H; Marques, Manuel B; Bartelt, Hartmut; Frazão, Orlando

    2016-06-27

    Optical fiber micro-tips are promising devices for sensing applications in small volume and difficult to access locations, such as biological and biomedical settings. The tapered fiber tips are prepared by dynamic chemical etching, reducing the size from 125 μm to just a few μm. Focused ion beam milling is then used to create cavity structures on the tapered fiber tips. Two different Fabry-Perot micro-cavities have been prepared and characterized: a solid silica cavity created by milling two thin slots and a gap cavity. A third multi-cavity structure is fabricated by combining the concepts of solid silica cavity and gap cavity. This micro-tip structure is analyzed using a fast Fourier transform method to demultiplex the signals of each cavity. Simultaneous measurement of temperature and external refractive index is then demonstrated, presenting sensitivities of - 15.8 pm/K and -1316 nm/RIU, respectively. PMID:27410566

  8. Natural media with negative index of refraction: Perspectives of complex transition metal oxides (Review Article)

    NASA Astrophysics Data System (ADS)

    Fertman, E. L.; Beznosov, A. B.

    2011-07-01

    The capabilities of perovskite-like compounds with the effect of colossal magnetoresistance (CMR) and some other complex oxides to have a negative index of refraction (NIR) are considered. Physical properties of these compounds are also analyzed from the standpoint of designing tunable metamaterials on their base. Of particular interest are temperature and magnetic field driven first-order transformations in oxides with perovskite structure and in spinels. These transformations give rise to nanophase separated states, using which the properties of negative refraction can be affected. The magnetic-field controlled metamaterials with CMR oxides as a boundary NIR media for a photonic crystal are discussed.

  9. 2-D isotropic negative refractive index in a N-type four-level atomic system

    NASA Astrophysics Data System (ADS)

    Zhao, Shun-Cai; Wu, Qi-Xuan; Ma, Kun

    2015-11-01

    2-D(Two-dimensional) isotropic negative refractive index (NRI) is explicitly realized via the orthogonal signal and coupling standing-wave fields coupling the Ntype four-level atomic system. Under some key parameters of the dense vapour media, the atomic system exhibits isotropic NRI with simultaneous negative permittivity and permeability (i.e. left-handedness) in the 2-D x-y plane. Compared with other 2-D NRI schemes, the coherent atomic vapour media in our scheme may be an ideal 2-D isotropic NRI candidate and has some potential advantages, significance or applications in the further investigation.

  10. Modulation instability of structured-light beams in negative-index metamaterials

    NASA Astrophysics Data System (ADS)

    Silahli, Salih Z.; Walasik, Wiktor; Litchinitser, Natalia M.

    2016-05-01

    One of the most fundamental properties of isotropic negative-index metamaterials (NIMs), namely opposite directionality of the Poynting vector and the wavevector, enable many novel linear and nonlinear regimes of light–matter interactions. Here, we predict distinct characteristics of azimuthal modulation instability (MI) of optical vortices with different topological charges in NIMs with Kerr-type and saturable nonlinearity. We derive an analytical expression for the spatial modulation-instability gain for the Kerr-nonlinearity case and show that a specific condition relating the diffraction and the nonlinear lengths must be fulfilled for the azimuthal MI to occur. Finally, we investigate the rotation of the necklace beams due to the transfer of orbital angular momentum of the generating vortex on the movement of solitary necklace beams. We show that the direction of rotation is opposite in positive- and negative-index materials.

  11. Symmetry relations in the generalized Lorenz-Mie theory for lossless negative refractive index media

    NASA Astrophysics Data System (ADS)

    André Ambrosio, Leonardo

    2016-09-01

    In this paper we present a theoretical analysis of the generalized Lorenz-Mie theory for negative refractive index (NRI) media and spherical scatterers, extending the well-known concepts and definitions found in the literature involving dielectric or positive refractive index (PRI) particles. The consequences of a negative phase velocity and an anti-parallelism of the wave vector with respect to the Poynting vector are investigated and interpreted in this framework and, together with the symmetries found for the beam-shape coefficients when compared to the conventional PRI case, it is shown that the description of plane waves, Gaussian beams and, more generally, on-axis azimuthally symmetric waves along a NRI medium, their fields and all physical properties can be conveniently correlated with that of dielectric media once the electromagnetic response functions are replaced by their corresponding dielectric counterparts.

  12. Specific absorption rate analysis of broadband mobile antenna with negative index metamaterial

    NASA Astrophysics Data System (ADS)

    Alam, Touhidul; Faruque, Mohammad Rashed Iqbal; Islam, Mohammad Tariqul

    2016-03-01

    This paper presents a negative index metamaterial-inspired printed mobile wireless antenna that can support most mobile applications such as GSM, UMTS, Bluetooth and WLAN frequency bands. The antenna consists of a semi-circular patch, a 50Ω microstrip feed line and metamaterial ground plane. The antenna occupies a very small space of 37 × 47 × 0.508 mm3, making it suitable for mobile wireless application. The perceptible novelty shown in this proposed antenna is that reduction of specific absorption rate using the negative index metamaterial ground plane. The proposed antenna reduced 72.11 and 75.53 % of specific absorption rate at 1.8 and 2.4 GHz, respectively.

  13. Tunable band gap near the Dirac point in nonlinear negative-zero-positive index metamaterial waveguide

    SciTech Connect

    Shen Ming; Ruan Linxu; Shi Jielong; Wang Qi; Wang Xinglin

    2011-04-15

    We make theoretical investigations of the nonlinear guided modes near the Dirac point (DP) in nonlinear negative-zero-positive index metamaterial (NZPIM) waveguide. When the nonlinearity is self-focusing, an asymmetric forbidden band exists near the DP that can be modulated by the strength of the nonlinearity. However, the self-defocusing nonlinearity can completely eliminate the asymmetric band gap. We also study the nonlinear surface waves in such nonlinear NZPIM waveguide. These results may predict analogous phenomena in nonlinear graphene.

  14. Nonlinear excitations in negative index materials: Modulational instability and solitary wave solutions

    NASA Astrophysics Data System (ADS)

    Sharma, Vivek Kumar; Goyal, Amit

    2016-05-01

    We explore the modulational instability and existence of dark, bright solitary wave solutions in negative index-materials (NIMs) modeled by generalized nonlinear Schrödinger equation with competing cubic-quintic and higher-order nonlinearities with dispersive permittivity and permeability. Parameter domains are delineated in which these ultrashort pulses exist in NIMs. Unlike the ordinary materials, these novel excitations occur for different signs of dispersion, Kerr and non-Kerr nonlinearities.

  15. Large-area flexible 3D optical negative index metamaterial formed by nanotransfer printing

    NASA Astrophysics Data System (ADS)

    Chanda, Debashis; Shigeta, Kazuki; Gupta, Sidhartha; Cain, Tyler; Carlson, Andrew; Mihi, Agustin; Baca, Alfred J.; Bogart, Gregory R.; Braun, Paul; Rogers, John A.

    2011-07-01

    Negative-index metamaterials (NIMs) are engineered structures with optical properties that cannot be obtained in naturally occurring materials. Recent work has demonstrated that focused ion beam and layer-by-layer electron-beam lithography can be used to pattern the necessary nanoscale features over small areas (hundreds of µm2) for metamaterials with three-dimensional layouts and interesting characteristics, including negative-index behaviour in the optical regime. A key challenge is in the fabrication of such three-dimensional NIMs with sizes and at throughputs necessary for many realistic applications (including lenses, resonators and other photonic components). We report a simple printing approach capable of forming large-area, high-quality NIMs with three-dimensional, multilayer formats. Here, a silicon wafer with deep, nanoscale patterns of surface relief serves as a reusable stamp. Blanket deposition of alternating layers of silver and magnesium fluoride onto such a stamp represents a process for `inking' it with thick, multilayer assemblies. Transfer printing this ink material onto rigid or flexible substrates completes the fabrication in a high-throughput manner. Experimental measurements and simulation results show that macroscale, three-dimensional NIMs (>75 cm2) nano-manufactured in this way exhibit a strong, negative index of refraction in the near-infrared spectral range, with excellent figures of merit.

  16. Negative spectral index of f{sub NL} in the axion-type curvaton model

    SciTech Connect

    Huang, Qing-Guo

    2010-11-01

    We derive the spectral index of f{sub NL} and its running from isocurvature single field and investigate the curvaton models with a negative spectral index of f{sub NL} in detail. In particular, a numerical study of the axion-type curvaton model is illustrated, and we find that the spectral index of f{sub NL} is negative and its absolute value is maximized around σ{sub *} = πf/2 for the potential V(σ) = m{sup 2}f{sup 2}(1−cos (σ/f)). The spectral index of f{sub NL} can be O(−0.1) for the axion-type curvaton model. A convincing detection of a positive n{sub f{sub N{sub L}}} will rule out the axion-type curvaton model. In addition, we also give a general discussion about the detectable parameter space for the curvaton model with a polynomial potential.

  17. Microstructured Air Cavities as High-Index Contrast Substrates with Strong Diffraction for Light-Emitting Diodes.

    PubMed

    Moon, Yoon-Jong; Moon, Daeyoung; Jang, Jeonghwan; Na, Jin-Young; Song, Jung-Hwan; Seo, Min-Kyo; Kim, Sunghee; Bae, Dukkyu; Park, Eun Hyun; Park, Yongjo; Kim, Sun-Kyung; Yoon, Euijoon

    2016-05-11

    Two-dimensional high-index-contrast dielectric gratings exhibit unconventional transmission and reflection due to their morphologies. For light-emitting devices, these characteristics help guided modes defeat total internal reflections, thereby enhancing the outcoupling efficiency into an ambient medium. However, the outcoupling ability is typically impeded by the limited index contrast given by pattern media. Here, we report strong-diffraction, high-index-contrast cavity engineered substrates (CESs) in which hexagonally arranged hemispherical air cavities are covered with a 80 nm thick crystallized alumina shell. Wavelength-resolved diffraction measurements and Fourier analysis on GaN-grown CESs reveal that the high-index-contrast air/alumina core/shell patterns lead to dramatic excitation of the low-order diffraction modes. Large-area (1075 × 750 μm(2)) blue-emitting InGaN/GaN light-emitting diodes (LEDs) fabricated on a 3 μm pitch CES exhibit ∼39% enhancement in the optical power compared to state-of-the-art, patterned-sapphire-substrate LEDs, while preserving all of the electrical metrics that are relevant to LED devices. Full-vectorial simulations quantitatively demonstrate the enhanced optical power of CES LEDs and show a progressive increase in the extraction efficiency as the air cavity volume is expanded. This trend in light extraction is observed for both lateral- and flip-chip-geometry LEDs. Measurements of far-field profiles indicate a substantial beaming effect for CES LEDs, despite their few-micron-pitch pattern. Near-to-far-field transformation simulations and polarization analysis demonstrate that the improved extraction efficiency of CES LEDs is ascribed to the increase in emissions via the top escape route and to the extraction of transverse-magnetic polarized light. PMID:27045458

  18. Determination of refractive index of a simple negative, positive, or zero power lens using wedged plated interferometer

    NASA Technical Reports Server (NTRS)

    Shukla, R. P.; Perera, G. M.; George, M. C.; Venkateswarlu, P.

    1990-01-01

    A nondestructive technique for measuring the refractive index of a negative lens using a wedged plate interferometer is described. The method can be also used for measuring the refractive index of convex or zero power lenses. Schematic diagrams are presented for the use of a wedged plate interferometer for measuring the refractive index of a concave lens and of a convex lens.

  19. Simultaneous measurement of refractive index and temperature with micro silica sphere cavity hybrid Fabry Perot optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Ranjbar Naeini, O. R.; Latifi, H.; Zibaii, M. I.

    2015-09-01

    In this article, a novel Micro Silica Sphere Cavity Hybrid Fabry Perot optical fiber sensor is reported where refractive index (RI) and temperature can be simultaneously measured. The sensor is based on Micro Silica Sphere that was fabricated using a capillary tube. The micro silica sphere and optical fiber form a Hybrid Fabry Perot cavity. The temperature cross sensitivity of this sensor is small enough to be used for accurate RI measurement. The temperature sensitivity and RI sensitivity are -0.0028 dBm/ºC, -0.0044 dBm/ºC , -24.09 dBm/RIU and -20.6 dBm/RIU respectively, using two selected resonances.

  20. Influence of birefringence in the instability spectra of oppositely directed coupler with negative index material channel

    NASA Astrophysics Data System (ADS)

    Shafeeque Ali, A. K.; Nithyanandan, K.; Porsezian, K.; Maimistov, Andrei I.

    2016-02-01

    A theoretical investigation on the influence of birefringence in the modulational instability (MI) spectra of an oppositely directed coupler (ODC) with a negative index material (NIM) channel is presented. We study the effect of birefringence on MI in linear and circular birefringent ODCs for both normal and anomalous dispersion regimes. It is found that besides the instability band due to nonlinear positive index material (PIM) and negative index material (NIM) channels, new symmetric instability regions are observed as a result of birefringent effects. Also defocusing nonlinearity suppresses the NIM band in the normal dispersion regime, but in the anomalous dispersion regime the defocusing nonlinearity enhances the gain of the NIM band. In contrast to the case of linear birefringence, in terms of MI gain from circular birefringence, only two birefringent bands dominate: the inherently PIM and NIM bands. This preponderance is attributed to the fact that the cross-phase modulation effect for the case of circular birefringence is stronger, thus allowing a better coupling between the beams, which results in the enhancement of the gain. Therefore, the manipulation of MI and solitons in an ODC is better performed when the birefringence is circular rather than linear. Here we report how to generate and manipulate MI and solitons in birefringent ODCs with a particular emphasis on a NIM channel.

  1. Development of Negative Index of Refraction Metamaterials with Split Ring Resonators and Wires for RF Lens Applications

    NASA Astrophysics Data System (ADS)

    Parazzoli, Claudio G.; Greegor, Robert B.; Tanielian, M. H.

    Metamaterials are engineered ring and wire composites whose response to an incident electromagnetic wave can be described by an effective negative dielectric permittivity ɛ and magnetic permeability μ. Simultaneous negative ɛ and μ within a given frequency band of a metamaterial gives rise to a negative index of refraction n. This has been demonstrated via a Snell's law experiment. The electromagnetic properties of many metamaterial structures in the microwave region are investigated through numerical simulations and experiments. A negative index of refraction, n, allows lenses with reduced primary (Seidel) aberrations compared to equivalent positive index lens. This is demonstrated both for cylindrical lenses and spherical lenses, as well as for the gradient index lenses. Detailed field maps of the focal region of the metamaterials lenses are made and compared to a comparable positive index of refraction lens.

  2. Optic-null space medium for cover-up cloaking without any negative refraction index materials

    PubMed Central

    Sun, Fei; He, Sailing

    2016-01-01

    With the help of optic-null medium, we propose a new way to achieve invisibility by covering up the scattering without using any negative refraction index materials. Compared with previous methods to achieve invisibility, the function of our cloak is to cover up the scattering of the objects to be concealed by a background object of strong scattering. The concealed object can receive information from the outside world without being detected. Numerical simulations verify the performance of our cloak. The proposed method will be a great addition to existing invisibility technology. PMID:27383833

  3. Optic-null space medium for cover-up cloaking without any negative refraction index materials.

    PubMed

    Sun, Fei; He, Sailing

    2016-01-01

    With the help of optic-null medium, we propose a new way to achieve invisibility by covering up the scattering without using any negative refraction index materials. Compared with previous methods to achieve invisibility, the function of our cloak is to cover up the scattering of the objects to be concealed by a background object of strong scattering. The concealed object can receive information from the outside world without being detected. Numerical simulations verify the performance of our cloak. The proposed method will be a great addition to existing invisibility technology. PMID:27383833

  4. Optic-null space medium for cover-up cloaking without any negative refraction index materials

    NASA Astrophysics Data System (ADS)

    Sun, Fei; He, Sailing

    2016-07-01

    With the help of optic-null medium, we propose a new way to achieve invisibility by covering up the scattering without using any negative refraction index materials. Compared with previous methods to achieve invisibility, the function of our cloak is to cover up the scattering of the objects to be concealed by a background object of strong scattering. The concealed object can receive information from the outside world without being detected. Numerical simulations verify the performance of our cloak. The proposed method will be a great addition to existing invisibility technology.

  5. Switchable zero-index metamaterials by loading positive-intrinsic-negative diodes

    SciTech Connect

    Xiang, Nan; Cheng, Qiang Zhao, Jie; Jun Cui, Tie Feng Ma, Hui; Xiang Jiang, Wei

    2014-02-03

    We propose switchable zero-index metamaterials (ZIMs) implemented by split ring resonators (SRRs) loaded with positive-intrinsic-negative (PIN) diode switching elements. We demonstrate that ZIMs can be achieved at around 10 GHz when the PIN diode is switched off. When the PIN diode is switched on, however, the designed metamaterials have impedance matching to the free space, which is useful to reduce the reflections at the interface of two media. The switchable ZIMs are suitable for a wide variety of applications like the beam forming and directive radiation. Experimental results validate the switching ability of the proposed ZIMs.

  6. Triangular lattice of carbon nanotube arrays for negative index of refraction and subwavelength lensing effect

    SciTech Connect

    Wang, Y.; Wang, X.; Rybczynski, J.; Wang, D.Z.; Kempa, K.; Ren, Z.F.

    2005-04-11

    Self-assembly of polystyrene microspheres has been utilized in a two-step masking technique to prepare triangular lattices of catalytic nanodots at low cost. Subsequent triangular lattices of aligned carbon nanotubes on a silicon substrate are achieved by plasma-enhanced chemical vapor deposition. Nickel is used both in the nanodots and in the secondary mask. The triangular lattices of carbon nanotube arrays as two-dimensional photonic crystals show higher geometrical symmetry than the hexagonal lattices previously reported, enabling broader applications including negative index of refraction and subwavelength lensing effect.

  7. Intra-connected three-dimensionally isotropic bulk negative index photonic metamaterial

    SciTech Connect

    Guney, Durdu; Koschny, Thomas; Soukoulis, Costas

    2010-05-26

    Isotropic negative index metamaterials (NIMs) are highly desired, particularly for the realization of ultra-high resolution lenses. However, existing isotropic NIMs function only two-dimensionally and cannot be miniaturized beyond microwaves. Direct laser writing processes can be a paradigm shift toward the fabrication of three-dimensionally (3D) isotropic bulk optical metamaterials, but only at the expense of an additional design constraint, namely connectivity. Here, we demonstrate with a proof-of-principle design that the requirement connectivity does not preclude fully isotropic left-handed behavior. This is an important step towards the realization of bulk 3D isotropic NIMs at optical wavelengths.

  8. Validity and reliability of the Korean version of the Speech Handicap Index in patients with oral cavity cancer.

    PubMed

    Park, S S; Choi, S H; Hong, J A; Hong, Y H; Jeong, N G; Lee, S Y; Sung, M-W; Hah, J H

    2016-04-01

    The aims of this study were to evaluate the cross-cultural adaptation of the Speech Handicap Index (SHI) for Korean subjects and to determine its reliability and utility in patients with oral cavity cancer. The Korean version of the SHI was administered to 50 healthy subjects and 56 patients with speech problems resulting from treatment for oral cavity cancers. The content and construct validity, internal consistency, and test-retest reliability were examined. Healthy subject and patient group scores were compared, and the Mann-Whitney U-test was used to determine discriminatory ability. The Korean version of the SHI had high internal consistency (Cronbach's alpha=0.99) and test-retest reliability for the total and subscales: total (T) 0.98, speech (S) 0.99, and psychosocial (P) 0.97. Mean scores in the healthy group were 0.5 (T), 0.2 (S), and 0.2 (P), whereas those in the patient group were 34.3 (T), 16.6 (S), and 15.5 (P). The scores differed significantly between the groups (P<0.05). The Korean version of the SHI can be a useful tool to evaluate a patient's self-perception of their speech dysfunction in daily life and to better understand postoperative speech disorders in patients with oral cavity cancer. PMID:26701323

  9. Spatial mapping of the internal and external electromagnetic fields of negative index metamaterials.

    PubMed

    Justice, Bryan J; Mock, Jack J; Guo, Liheng; Degiron, Aloyse; Schurig, David; Smith, David R

    2006-09-18

    We perform an experimental study of the phase and amplitude of microwaves interacting with and scattered by two-dimensional negative index metamaterials. The measurements are performed in a parallel plate waveguide apparatus at X-band frequencies (8-12 GHz), thus constraining the electromagnetic fields to two dimensions. A detection antenna is fixed to one of the plates, while a second plate with a fixed source antenna or waveguide is translated relative to the first plate. The detection antenna is inserted into, but not protruding below, the stationary plate so that fields internal to the metamaterial samples can be mapped. From the measured mappings of the electric field, the interplay between the microstructure of the metamaterial lattice and the macroscopic averaged response is revealed. For example, the mapped phase fronts within a metamaterial having a negative refractive index are consistent with a macroscopic phase-in accordance with the effective medium predictions-which travels in a direction opposite to the direction of propagation. The field maps are in excellent agreement with finite element numerical simulations performed assuming homogeneous metamaterial structures. PMID:19529250

  10. Properties of Defect Modes in Periodic Lossy Multilayer with Negative-Index-Materials

    NASA Astrophysics Data System (ADS)

    Alireza, Aghajamali; Mahmood, Barati

    2013-07-01

    Employing the characteristic matrix method, this study investigates transmission properties of one-dimensional defective lossy photonic crystals composed of negative and positive refractive index layers with one lossless defect layer at the center of the crystal. The results of the study show that as the refractive index and thickness of the defect layer increase, the frequency of the defect mode decreases. In addition, the study shows that the frequency of the defect mode is sensitive to the incidence angle, polarization, and physical properties of the defect layer, but it is insensitive to the small lattice loss factor. The peak of the defect mode is very sensitive to the loss factor, incidence angle, polarization, refractive index, and thickness of the defect layer. This study also shows that the peak and the width of the defect mode are affected by the numbers of the lattice period and the loss factor. The results can lead to designing new types of narrow filter structures and other optical devices.

  11. The role of absorption and dispersion in resonant tunnelling through a negative index medium

    NASA Astrophysics Data System (ADS)

    Golla, D.; Deb, S.; Dutta Gupta, S.

    2011-01-01

    We study resonant tunneling through a layered medium with a passive negative index medium (NIM) slab as a constituent layer. Using a causal model for susceptibilities with the parameters of a recently reported metamaterial [G. Dolling, C. Enkrich, M. Wegener, C.M. Soukoulis, S. Linden, Opt. Lett. 31, 1800 (2006)] we show that resonant tunnelling and the associated delay are mostly suppressed. This is in sharp contrast with the naive approach of retaining phase velocity dispersion with arbitrary low losses, predicting sharp resonances with large associated delays. This is shown to be a nontrivial issue because of the necessity of losses for NIM behaviour, while their presence spoils the quality factor of the resonant devices.

  12. Flexible chiral metamaterials with dynamically optical activity and high negative refractive index

    NASA Astrophysics Data System (ADS)

    Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Akgol, Oguzhan; Sabah, Cumali

    2015-06-01

    We demonstrate numerically and experimentally chiral metamaterials (MTMs) based on gammadion-bilayer cross-wires that uniaxially create giant optical activity and tunable circular dichroism as a result of the dynamic design. In addition, the suggested structure gives high negative refractive index due to the large chirality in order to obtain an efficient polarization converter. We also present a numerical analysis in order to show the additional features of the proposed chiral MTM in detail. Therefore, a MTM sensor application of the proposed chiral MTM is introduced and discussed. The presented chiral designs offer a much simpler geometry and more efficient outlines. The experimental results are in a good agreement with the numerical simulation. It can be seen from the results that, the suggested chiral MTM can be used as a polarization converter, sensor, etc. for several frequency regimes.

  13. Metamaterial lens made of fully printed resonant-type negative-refractive-index transmission lines

    NASA Astrophysics Data System (ADS)

    Xu, He-Xiu; Wang, Guang-Ming; Qing Qi, Mei; Lv, Yuan-Yuan; Gao, Xi

    2013-05-01

    We studied a well-resolved lens based on planar fully printed resonant-type negative-refractive-index transmission lines made of complementary split ring resonators. The lens goes beyond previous lens in terms of moderate loss and compactness. The focusing has been demonstrated by the circuit theory simulation and full-wave simulation and finally confirmed by the experiments, showing that that the lens is able to overcome the diffraction limit of 0.5 effective wavelengths and exhibits a super resolution as small as 0.348 effective wavelengths inside the lens. The superlens free of any lumped elements opens an easy and inexpensive avenue toward imaging devices with super performances.

  14. The Assessment of Positivity and Negativity in Social Networks: The Reliability and Validity of the Social Relationships Index

    ERIC Educational Resources Information Center

    Campo, Rebecca A.; Uchino, Bert N.; Holt-Lunstad, Julianne; Vaughn, Allison; Reblin, Maija; Smith, Timothy W.

    2009-01-01

    The Social Relationships Index (SRI) was designed to examine positivity and negativity in social relationships. Unique features of this scale include its brevity and the ability to examine relationship positivity and negativity at the level of the specific individual and social network. The SRI's psychometric properties were examined in three…

  15. Index of problematic online experiences: item characteristics and correlation with negative symptomatology.

    PubMed

    Mitchell, Kimberly J; Sabina, Chiara; Finkelhor, David; Wells, Melissa

    2009-12-01

    This exploratory study aimed to develop and test a quick, easily administered instrument, the Index of Problematic Online Experiences (I-POE). The goal of the I-POE extends beyond assessing for Internet overuse to broadly assess problematic Internet use across several domains and activities. Data was collected from 563 college students from a Northern New England university using an online survey methodology. Results indicated the I-POE has adequate construct validity and is highly correlated with a variety of relevant constructs: depression, anger/irritability, tension-reduction behavior, sexual concerns, and dysfunctional sexual behavior as measured by the Trauma Symptom Inventory; as well as amount of Internet use and permissive attitudes toward engaging in a variety of sexual activities. Early flagging of online experiences could mitigate the negative effects associated with problematic use. The I-POE, as an easy-to-administer, short screening index, holds promise in this regard. Initial testing of the instrument points to its utility in identifying persons who are experiencing a broad range of Internet-related problems. PMID:19591618

  16. Intrinsic Fabry-Pérot cavity sensor based on chemical etching of a multimode graded index fiber spliced to a single mode fiber

    NASA Astrophysics Data System (ADS)

    Tafulo, Paula A. R.; Frazão, O.; Jorge, P. A. S.; Araújo, F. M.

    2010-09-01

    An intrinsic Fabry-Pérot cavity for high temperature and strain measurement is presented. The in-fibre cavity is formed by a chemical etched graded index optical fiber spliced to a single mode fiber. The intrinsic sensor obtained shows high sensitivity to strain (6.2 pm/μɛ) and rather low sensitivity to temperature (0.9 pm/°C), being suitable for applications as a strain gauge at high temperature.

  17. Identification and methicillin resistance of coagulase-negative staphylococci isolated from nasal cavity of healthy horses.

    PubMed

    Karakulska, Jolanta; Fijałkowski, Karol; Nawrotek, Paweł; Pobucewicz, Anna; Poszumski, Filip; Czernomysy-Furowicz, Danuta

    2012-06-01

    The aim of this study was an analysis of the staphylococcal flora of the nasal cavity of 42 healthy horses from 4 farms, along with species identification of CoNS isolates and determination of resistance to 18 antimicrobial agents, particularly phenotypic and genotypic methicillin resistance. From the 81 swabs, 87 staphylococci were isolated. All isolates possessed the gap gene but the coa gene was not detected in any of these isolates. Using PCR-RFLP of the gap gene, 82.8% of CoNS were identified: S. equorum (14.9%), S. warneri (14.9%), S. sciuri (12.6%), S. vitulinus (12.6%), S. xylosus (11.5%), S. felis (5.7%), S. haemolyticus (3.4%), S. simulans (3.4%), S. capitis (1.1%), S. chromogenes (1.1%), and S. cohnii subsp. urealyticus (1.1%). To our knowledge, this was the first isolation of S. felis from a horse. The species identity of the remaining Staphylococcus spp. isolates (17.2%) could not be determined from the gap gene PCR-RFLP analysis and 16S rRNA gene sequencing data. Based on 16S-23S intergenic transcribed spacer PCR, 11 different ITS-PCR profiles were identified for the 87 analyzed isolates. Results of API Staph were consistent with molecular identification of 17 (19.5%) isolates. Resistance was detected to only 1 or 2 of the 18 antimicrobial agents tested in the 17.2% CoNS isolates, including 6.9% MRCoNS. The mecA gene was detected in each of the 5 (5.7%) phenotypically cefoxitin-resistant isolates and in 12 (13.8%) isolates susceptible to cefoxitin. In total, from 12 horses (28.6%), 17 (19.5%) MRCoNS were isolated. The highest percentage of MRCoNS was noted among S. sciuri isolates (100%). PMID:22752908

  18. Superlensing effect for surface acoustic waves in a pillar-based phononic crystal with negative refractive index

    SciTech Connect

    Addouche, Mahmoud Al-Lethawe, Mohammed A. Choujaa, Abdelkrim Khelif, Abdelkrim

    2014-07-14

    We demonstrate super resolution imaging for surface acoustic waves using a phononic structure displaying negative refractive index. This phononic structure is made of a monolithic square lattice of cylindrical pillars standing on a semi-infinite medium. The pillars act as acoustic resonator and induce a surface propagating wave with unusual dispersion. We found, under specific geometrical parameters, one propagating mode that exhibits negative refraction effect with negative effective index close to −1. Furthermore, a flat lens with finite number of pillars is designed to allow the focusing of an acoustic point source into an image with a resolution of (λ)/3 , overcoming the Rayleigh diffraction limit.

  19. Experimental realization of an open cavity

    PubMed Central

    Ge, Xiaochen; He, Sailing

    2014-01-01

    The design and experimental demonstration of an open cavity in the microwave region is presented. The resonance condition is achieved through the cancellation of lightpaths in positive and negative refractive index materials. The positive index material is a structured aluminium surface supporting a spoof surface plasmon mode, and the negative index material is a photonic crystal made of alumina. A resonance peak is observed in the measured spectrum at which the electric field distribution agrees with numerical simulation. PMID:25096927

  20. Comparison of Optical Emission Spectroscopy and Cavity Ring-Down Spectroscopy in Large-Scaled Negative-Ion Source

    SciTech Connect

    Ikeda, K.; Nakano, H.; Tsumori, K.; Kaneko, O.; Kisaki, M.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Fantz, U.

    2011-09-26

    Optical emission spectroscopy (OES) and cavity ring-down spectroscopy (CRDS) systems are installed in a 1/3-scaled negative hydrogen-ion source at the National Institute for Fusion Science testbed to investigate the dynamics of H{sup -} ions in the extraction region near the plasma grid. The signal form of the H{sup -} ion density rapidly drops after beam extraction on applying a low-bias voltage. A similar signal drop appears in the intensity of the hydrogen Balmer-line emission measured by OES and is caused by decreasing atomic hydrogen produced by mutual neutralization effects between H{sup -} and H{sup +}. Shot trend of the beam currents are similar to the H{sup -} density and H{sub {alpha}}/H{sub {beta}} in the extraction region, which increases twice as large immediately after Cs seeding. We observe a linear correlation between the H{sup -} density and the inclination of H{sub {alpha}}/H{sub {beta}} which allows for experimentally benchmarking the OES measurement with that of CRDS. Thus, this approach is used for estimating the H{sup -} density by OES in negative-ion sources for high-energy neutral beam injector.

  1. PT -symmetry-induced evolution of sharp asymmetric line shapes and high-sensitivity refractive index sensors in a three-cavity array

    NASA Astrophysics Data System (ADS)

    Li, Jiahua; Yu, Rong; Ding, Chunling; Wu, Ying

    2016-02-01

    It is important to control and tune the Fano-resonance spectra to achieve a large slope with, in addition, a relatively high extinction ratio for low-power optical switching and high-sensitivity sensing. Here, we explore the evolution of sharp asymmetric Fano-like line shapes in a three-cavity array with local parity-time (PT ) symmetry. In this three-cavity configuration, a single cavity is coupled to a PT -symmetric combination of two cavities via a common waveguide. The influences of local PT symmetry on the asymmetric Fano-like line shapes are investigated by monitoring the output transmission spectra at various system parameters. It is found that both the slope and the extinction ratio within the sharp asymmetric line shapes can be significantly enhanced by introducing the PT -symmetric unit, compared with the configuration of two indirectly coupled cavities. Subsequently we discuss the application of such a PT -assisted configuration as a family of high-sensitivity refractive index sensors by numerical analysis. For practical parameters based on microring resonators, the best sensitivity of refractive index sensors is more than five orders of magnitude larger than two indirectly coupled lossy cavities. The proposed scheme can be implemented in current state-of-the-art experiments. This investigation can help us to understand the interplay between the Fano resonance and PT symmetry.

  2. Coexistence of positive and negative refractive index sensitivity in the liquid-core photonic crystal fiber based plasmonic sensor.

    PubMed

    Shuai, Binbin; Xia, Li; Liu, Deming

    2012-11-01

    We present and numerically characterize a liquid-core photonic crystal fiber based plasmonic sensor. The coupling properties and sensing performance are investigated by the finite element method. It is found that not only the plasmonic mode dispersion relation but also the fundamental mode dispersion relation is rather sensitive to the analyte refractive index (RI). The positive and negative RI sensitivity coexist in the proposed design. It features a positive RI sensitivity when the increment of the SPP mode effective index is larger than that of the fundamental mode, but the sensor shows a negative RI sensitivity once the increment of the fundamental mode gets larger. A maximum negative RI sensitivity of -5500nm/RIU (Refractive Index Unit) is achieved in the sensing range of 1.50-1.53. The effects of the structural parameters on the plasmonic excitations are also studied, with a view of tuning and optimizing the resonant spectrum. PMID:23187403

  3. Negative refractive index of metallic cross-I-shaped pairs: origin and evolution with pair gap width.

    PubMed

    Ma, Y G; Wang, X C; Ong, C K

    2008-07-01

    A structured composite of the negative index of refraction was fabricated by one layer of cross-I-shaped metal pairs. In this structure, the electric and magnetic inclusions were effectively integrated into one small unit. We varied the spacing of the cross pair to control the location of the magnetic resonance mode and their intercoupling with the electric mode. The frequency dependences of permittivity, permeability, and refractive indices with different gap widths of the pairs were systematically discussed by free-space measurement as well as numerical simulation. A spacing window dependent on the geometrical parameters was found in which the real part of the refractive index could have a negative value. The one-layer cross-pair pattern proposed in this work can be extended to three-dimensional structures with well-controlled interlayer coupling that will greatly facilitate the fabrication and measurement of negative-index materials in high frequencies. PMID:18764072

  4. Surface polaritons in a negative-index metamaterial with active Raman gain

    NASA Astrophysics Data System (ADS)

    Tan, Chaohua; Huang, Guoxiang

    2015-02-01

    We propose a scheme to realize stable propagation of linear and nonlinear surface polaritons (SPs) by placing a N -type four-level quantum emitters at the interface between a dielectric and a negative-index metamaterial (NIMM). We show that in linear propagation regime SPs can acquire an active Raman gain (ARG) from a pump field and a gain doublet appears in the gain spectrum of a signal field induced by the quantum interference effect from a control field. The ARG can be used not only to completely compensate the Ohmic loss in the NIMM but also to acquire a superluminal group velocity for the SPs. We also show that in the nonlinear propagation regime a huge enhancement of the Kerr nonlinearity of the SPs can be obtained. As a result, ARG-assisted (1 + 1 )- and (2 + 1 )- dimensional superluminal surface polaritonic solitons with extremely low generation power may be produced based on the strong confinement of the electric field at the dielectric-NIMM interface.

  5. The mismatch negativity as an index of cognitive decline for the early detection of Alzheimer's disease.

    PubMed

    Ruzzoli, Manuela; Pirulli, Cornelia; Mazza, Veronica; Miniussi, Carlo; Brignani, Debora

    2016-01-01

    Evidence suggests that Alzheimer's disease (AD) is part of a continuum, characterized by long preclinical phases before the onset of clinical symptoms. In several cases, this continuum starts with a syndrome, defined as mild cognitive impairment (MCI), in which daily activities are preserved despite the presence of cognitive decline. The possibility of having a reliable and sensitive neurophysiological marker that can be used for early detection of AD is extremely valuable because of the incidence of this type of dementia. In this study, we aimed to investigate the reliability of auditory mismatch negativity (aMMN) as a marker of cognitive decline from normal ageing progressing from MCI to AD. We compared aMMN elicited in the frontal and temporal locations by duration deviant sounds in short (400 ms) and long (4000 ms) inter-trial intervals (ITI) in three groups. We found that at a short ITI, MCI showed only the temporal component of aMMN and AD the frontal component compared to healthy elderly who presented both. At a longer ITI, aMMN was elicited only in normal ageing subjects at the temporal locations. Our study provides empirical evidence for the possibility to adopt aMMN as an index for assessing cognitive decline in pathological ageing. PMID:27616726

  6. Ultra low-loss, isotropic optical negative-index metamaterial based on hybrid metal-semiconductor nanowires

    PubMed Central

    Paniagua-Domínguez, R.; Abujetas, D. R.; Sánchez-Gil, J. A.

    2013-01-01

    Recently, many fascinating properties predicted for metamaterials (negative refraction, superlensing, electromagnetic cloaking,…) were experimentally demonstrated. Unfortunately, the best achievements have no direct translation to the optical domain, without being burdened by technological and conceptual difficulties. Of particular importance within the realm of optical negative-index metamaterials (NIM), is the issue of simultaneously achieving strong electric and magnetic responses and low associated losses. Here, hybrid metal-semiconductor nanowires are proposed as building blocks of optical NIMs. The metamaterial thus obtained, highly isotropic in the plane normal to the nanowires, presents a negative index of refraction in the near-infrared, with values of the real part well below −1, and extremely low losses (an order of magnitude better than present optical NIMs). Tunability of the system allows to select the operating range in the whole telecom spectrum. The design is proven in configurations such as prisms and slabs, directly observing negative refraction. PMID:23514968

  7. Measurement of refractive index and size of microparticles by optical traps generated by vertical cavity surface emitting lasers

    NASA Astrophysics Data System (ADS)

    Flynn, Richard A.

    Optical trapping is a powerful tool in the biological sciences for manipulating cells, bacteria, viruses and organelles within cells. Optical traps can measure tiny biological forces on the order of picoNewtons or less. Currently particle manipulation and force measurement are the two main applications of optical traps. Conventional optical traps are generated by large expensive lasers aligned to full sized laboratory microscopes. In this era lab-on-a-chip bioanalysis technologies, the trapping laser must be miniaturized while the analysis capabilities of optical traps should be expanded to address a larger span of applications. The research that forms the basis of this dissertation involves the use of Vertical Cavity Surface Emitting Lasers (VCSELs) that are compact and arrayable for optical trapping and toward the development of a new and parallel method to measure the refractive index and size of a particle within an optical trap. The current best technique for measuring refractive index of a microparticle, refractometry, requires changing the fluid composition of the sample. The proposed optical trap technique works with any transparent fluid, a significant advantage for biological analysis. VCSEL arrays are applied to create arrays of optical traps. VCSEL arrays offer a low cost, low power, compact and arrayable solution to creating many simultaneous optical traps in parallel. VCSEL traps are shown to manipulate 3x3 arrays of biological cells. Cell types manipulated include red blood cells, yeast cells, NIH 3T3 Murine fibroblasts and rat primary hepatocytes. Forces exerted by VCSEL traps are quantified. Scaling of the array size is analyzed. VCSEL traps are applied to creating a co-culture of fibroblasts and hepatocytes, enabling the study of intracellular communication. Finally, VCSELS are shown to cause negligible damage to hepatocytes after 5 min exposure. The counter-propagating optical trap measurement (COTM) system extends the capabilities of optical

  8. Body mass index and risk of luminal, HER2-overexpressing, and triple negative breast cancer.

    PubMed

    Chen, Lu; Cook, Linda S; Tang, Mei-Tzu C; Porter, Peggy L; Hill, Deirdre A; Wiggins, Charles L; Li, Christopher I

    2016-06-01

    Triple negative (TN, tumors that do not express estrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor 2 (HER2)) and HER2-overexpressing (H2E, ER-/HER2+) tumors are two particularly aggressive subtypes of breast cancer. There is a lack of knowledge regarding the etiologies of these cancers and in particular how anthropometric factors are related to risk. We conducted a population-based case-case study consisting of 2659 women aged 20-69 years diagnosed with invasive breast cancer from 2004 to 2012. Four case groups defined based on joint ER/PR/HER2 status were included: TN, H2E, luminal A (ER+/HER2-), and luminal B (ER+/HER2+). Polytomous logistic regression was used to estimate odds ratios (ORs) and associated 95 % confidence intervals (CIs) where luminal A patients served as the reference group. Obese premenopausal women [body mass index (BMI) ≥30 kg/m(2)] had an 82 % (95 % CI 1.32-2.51) increased risk of TN breast cancer compared to women whose BMI <25 kg/m(2), and those in the highest weight quartile (quartiles were categorized based on the distribution among luminal A patients) had a 79 % (95 % CI 1.23-2.64) increased risk of TN disease compared to those in the lowest quartile. Among postmenopausal women obesity was associated with reduced risks of both TN (OR = 0.74, 95 % CI 0.54-1.00) and H2E (OR = 0.47, 95 % CI 0.32-0.69) cancers. Our results suggest obesity has divergent impacts on risk of aggressive subtypes of breast cancer in premenopausal versus postmenopausal women, which may contribute to the higher incidence rates of TN cancers observed among younger African American and Hispanic women. PMID:27220749

  9. Second-harmonic generation at angular incidence in a negative-positive index photonic band-gap structure.

    PubMed

    D'Aguanno, Giuseppe; Mattiucci, Nadia; Scalora, Michael; Bloemer, Mark J

    2006-08-01

    In the spectral region where the refractive index of the negative index material is approximately zero, at oblique incidence, the linear transmission of a finite structure composed of alternating layers of negative and positive index materials manifests the formation of a new type of band gap with exceptionally narrow band-edge resonances. In particular, for TM-polarized (transverse magnetic) incident waves, field values that can be achieved at the band edge may be much higher compared to field values achievable in standard photonic band-gap structures. We exploit the unique properties of these band-edge resonances for applications to nonlinear frequency conversion, second-harmonic generation, in particular. The simultaneous availability of high field localization and phase matching conditions may be exploited to achieve second-harmonic conversion efficiencies far better than those achievable in conventional photonic band-gap structures. Moreover, we study the role played by absorption within the negative index material, and find that the process remains efficient even for relatively high values of the absorption coefficient. PMID:17025558

  10. Wide band negative magnetic permeability materials (NMPM) with composite metalsemiconductor structures based on the Drude model, and applications to negative-refractive index (NIM).

    PubMed

    Benedetti, A; Sibilia, C; Bertolotti, M

    2007-05-28

    Composite structures based on metal open rings and thin wires are well established, for obtaining efficient negative index materials (NIM), acting as metamaterials in the long wavelength regime. The main losses are due both to metal absorption and to the inner electric resistance of metals; to overcome this latter loss we propose a new metal-semiconductor structure dimensioned by direct synthesis method, which offers an almost perfect Drude-like effective magnetic permeability. The choice of particular semiconductor components allows to get a negative resistance for the current induced by the electromagnetic field, which cancels that of the metal but puts a limit to the spectral response of the metamaterial. We consider some parasite effects, such as bianisotropy and incorrect values of structural parameters, to see limitations and features of this new NIM technology. PMID:19546961

  11. Record low-threshold index-guided InGaAs/GaAlAs vertical-cavity surface-emitting laser with a native oxide confinement structure

    NASA Astrophysics Data System (ADS)

    Hayashi, Y.; Mukaihara, T.; Hatori, N.; Ohnoki, N.; Matsutani, A.; Koyama, F.; Iga, K.

    1995-03-01

    An index-guided InGaAs/GaAlAs vertical-cavity surface-emitting laser with a native oxide confinement structure has been proposed and fabricated. A record threshold current of 70 micro A was achieved with a 5 micron-diameter core device. The proposed structure provides strong electrical and optical confinements. Also a reduction in nonradiative recombination and an improvement in the thermal resistance can be expected.

  12. Negative index of refraction in a four-level system with magnetoelectric cross coupling and local field corrections

    SciTech Connect

    Bello, F.

    2011-07-15

    This research focuses on a coherently driven four-level atomic medium with the aim of inducing a negative index of refraction while taking into consideration local field corrections as well as magnetoelectric cross coupling (i.e.,chirality) within the material's response functions. Two control fields are used to render the medium transparent for a probe field which simultaneously couples to an electric and a magnetic dipole transition, thus allowing one to test the permittivity and permeability of the material at the same time. Numerical simulations show that a negative index of refraction with low absorption can be obtained for a range of probe detunings while depending on number density and the ratio between the intensities of the control fields.

  13. Nanosphere dispersed liquid crystals for tunable negative-zero-positive index of refraction in the optical and terahertz regimes.

    PubMed

    Khoo, I C; Werner, D H; Liang, X; Diaz, A; Weiner, B

    2006-09-01

    An analysis of aligned nematic liquid crystal cells containing core-shell nanospheres shows that it is possible to devise a new type of metamaterial whose index of refraction is tunable from negative, through zero, to positive values. The design parameters for the constituents can be scaled for application in the optical as well as very long wavelength (e.g., terahertz and microwave) regions. PMID:16902629

  14. Dispersion, spatial growth rate, and start current of a Cherenkov free-electron laser with negative-index material

    SciTech Connect

    Wang, Yuanyuan; Wei, Yanyu; Jiang, Xuebing; Tang, Xianfeng; Shi, Xianbao; Gong, Yubin; Li, Dazhi; Takano, Keisuke; Nakajima, Makoto; Feng, Jinjun; Miyamoto, Shuji

    2015-08-15

    We present an analysis of a Cherenkov free-electron laser based on a single slab made from negative-index materials. In this system, a flat electron beam with finite thickness travelling close to the surface of the slab interacts with the copropagating electromagnetic surface mode. The dispersion equation for a finitely thick slab is worked out and solved numerically to study the dispersion relation of surface modes supported by negative-index materials, and the calculations are in good agreement with the simulation results from a finite difference time domain code. We find that under suitable conditions there is inherent feedback in such a scheme due to the characteristics of negative-index materials, which means that the system can oscillate without external reflectors when the beam current exceeds a threshold value, i.e., start current. Using the hydrodynamic approach, we setup coupled equations for this system, and solve these equations analytically in the small signal regime to obtain formulas for the spatial growth rate and start current.

  15. Dual frequency optical cavity

    DOEpatents

    George, E.V.; Schipper, J.F.

    Method and apparatus for generating two distinct laser frequencies in an optical cavity, using a T configuration laser cavity and means for intermittently increasing or decreasing the index of refraction n of an associated transmission medium in one arm of the optical cavity to enhance laser action in one arm or the second arm of the cavity.

  16. Dual frequency optical cavity

    DOEpatents

    George, E. Victor; Schipper, John F.

    1985-01-01

    Method and apparatus for generating two distinct laser frequencies in an optical cavity, using a "T" configuration laser cavity and means for intermittently increasing or decreasing the index of refraction n of an associated transmission medium in one arm of the optical cavity to enhance laser action in one arm or the second arm of the cavity.

  17. Development of Preparatory Activity Indexed by the Contingent Negative Variation in Children

    ERIC Educational Resources Information Center

    Flores, Angelica B.; Digiacomo, Marcia R.; Meneres, Susana; Trigo, Eva; Gomez, Carlos M.

    2009-01-01

    Objectives: The present study investigated the effect of age on task-specific preparatory activation induced by a spatial cue using the central cue Posner's paradigm. The behavioral responses and the contingent negative variation (CNV) generated between S1 (the warning stimulus) and S2 (the imperative stimulus) were compared between 16 healthy…

  18. Indexes to anticipate negative impacts of heat waves in urban Mediterranean environments

    NASA Astrophysics Data System (ADS)

    Monteiro, A. M.; Carvalho, C. V.; Velho, S. V.; Sousa, C. S.

    2012-04-01

    This study intention is to understand what might be the better indexes to anticipate health deterioration during temperature extreme events in a urban Mediterranean environment like Porto. To do this we look to the effects of the July 2006 Heat Wave using the Heat Index on the Mortality (All Causes) and Morbidity (All Causes, Respiratory and Circulatory diseases) in general, and in people over 74 years and by Gender, in Porto. The Poisson Generalized Additive Regression model was used in order to estimate the impact of Apparent Temperature (Heat Index) and Daily Mortality and Morbidity during the July 2006 Heat Wave. Daily Mortality, Morbidity and Heat Index was correlated with lags of Apparent Temperature up to 7 days using Pearson correlation. For a 1°C increase in mean Apparent Temperature we observed a 2.7% (95%CI:1.7-3.6%) increase in Mortality (for All Causes), 1.7% (95%CI:0.6-2.9%) in Respiratory Morbidity, 2,2% (95%CI:0.4-4.1%) in Women Respiratory Morbidity, 5,4% (95%CI:1.1-6.6%) in Chronic Obstructive Pulmonary Morbidity and 7,5% (95%CI:1.3-14.1%) in Women Chronic Obstructive Pulmonary Morbidity, for the entire population. For people ≥ 75 years, our work showed a 3,3% increase (95%CI:1.7-5.0%) in Respiratory Morbidity, 2,7% (95%CI:0.4-5.1%) in Men Respiratory Morbidity, 3,9% (95%CI:1.6-6.3%) in Women Respiratory Morbidity, 7.0% (95%CI:1.1-13.2%) in Chronic Obstructive Pulmonary Disease and 9.0% (95%CI:0.3-18.5%) in Women Chronic Obstructive Pulmonary Disease. We conclude that the use of Heat Index in a Mediterranean Tempered Climate enabled the identification of the effects of the July 2006 Heat Wave in Mortality due to All Causes and in Respiratory Morbidity of the General Population, as well as in Respiratory Morbidity of individuals with more than 74 years of age.

  19. Shear-mediated contributions to the effective properties of soft acoustic metamaterials including negative index

    PubMed Central

    Forrester, Derek Michael; Pinfield, Valerie J.

    2015-01-01

    Here we show that, for sub-wavelength particles in a fluid, viscous losses due to shear waves and their influence on neighbouring particles significantly modify the effective acoustic properties, and thereby the conditions at which negative acoustic refraction occurs. Building upon earlier single particle scattering work, we adopt a multiple scattering approach to derive the effective properties (density, bulk modulus, wavenumber). We show,through theoretical prediction, the implications for the design of “soft” (ultrasonic) metamaterials based on locally-resonant sub-wavelength porous rubber particles, through selection of particle size and concentration, and demonstrate tunability of the negative speed zones by modifying the viscosity of the suspending medium. For these lossy materials with complex effective properties, we confirm the use of phase angles to define the backward propagation condition in preference to “single-” and “double-negative” designations. PMID:26686414

  20. Numerical analysis of a near-infrared plasmonic refractive index sensor with high figure of merit based on a fillet cavity.

    PubMed

    Chen, Lei; Liu, Yumin; Yu, Zhongyuan; Wu, Dong; Ma, Rui; Zhang, Yang; Ye, Han

    2016-05-01

    A near-infrared plasmonic refractive index (RI) sensor with figure of merit (FOM) as high as 124.6 is proposed and investigated numerically. The RI sensing is realized by employing the linear relation between resonant wavelength and RI of the material under detecting. Based on the fillet cavity coupled with two metal-insulator-metal waveguides, transmission efficiency (T) and optical resolution (FWHM) of the RI sensor are both improved to a great extent with T = 95% and FWHM = 12nm, keeping acceptable wavelength sensitivity of 1496nm/RIU within the near-infrared region. In addition, a sensitivity as high as 3476nm/RIU is obtained by optimizing the shape and size of fillet cavity. In general, the high FOM, transmittance and sensitivity achieved by our design may get further applications in biomedical science and nanophotonic circuits. PMID:27137607

  1. Resonant tunneling of a wave through a structure that contains a layer with a negative refractive index

    NASA Astrophysics Data System (ADS)

    Afanas'ev, S. A.; Sementsov, D. I.; Yakimov, Ya. V.

    2016-05-01

    We have investigated the transmission ability of a layered structure the central layer of which is made of a "left-handed" material (its refractive index is negative) and is separated by two air slabs from a "right-handed" dielectric medium that surrounds the structure. We consider tunneling of energy fluxes through the structure and determine conditions for the complete (reflectionless) transmission of the power of the incident wave through it. We show that this effect is resonant and is observed when the tangential component of the wave vector of the incident wave coincides with the longitudinal wave vector of one of waveguiding eigenmodes of the left-handed layer.

  2. Generalized nonlinear Schrödinger equation for dispersive susceptibility and permeability: application to negative index materials.

    PubMed

    Scalora, Michael; Syrchin, Maxim S; Akozbek, Neset; Poliakov, Evgeni Y; D'Aguanno, Giuseppe; Mattiucci, Nadia; Bloemer, Mark J; Zheltikov, Aleksei M

    2005-07-01

    A new generalized nonlinear Schrödinger equation describing the propagation of ultrashort pulses in bulk media exhibiting frequency dependent dielectric susceptibility and magnetic permeability is derived and used to characterize wave propagation in a negative index material. The equation has new features that are distinct from ordinary materials (mu=1): the linear and nonlinear coefficients can be tailored through the linear properties of the medium to attain any combination of signs unachievable in ordinary matter, with significant potential to realize a wide class of solitary waves. PMID:16090616

  3. Tightly coupled tripole conductor pairs as constituents for a planar 2D-isotropic negative refractive index metamaterial.

    PubMed

    Vallecchi, Andrea; Capolino, Filippo

    2009-08-17

    A metamaterial, arranged by stacking layers of planar constituents suitably shaped to be responsive to arbitrarily linearly polarized incident waves is here shown to exhibit 2D-isotropic effective negative refractive index (NRI). The general concept underlying this metamaterial design consists of closely pairing two metallic particles to accomplish, as a result of their tight coupling, both symmetric and antisymmetric resonance modes, whose proper superposition can lead to an effective negative refraction response. The proposed structure is composed by layers of periodically arranged pairs of face coupled loaded tripoles printed on the opposite sides of a single dielectric substrate. Through a comprehensive characterization of the transmission properties of such metamaterial, together with the analysis of its dispersion diagram, conclusive evidence that the medium exhibits effective NRI properties as well as good impedance matching to free space is provided. We also describe some guidelines to design the proposed metamaterial with a prescribed operational frequency bandwidth, dependently on the structure parameters. PMID:19688000

  4. DNA repair prognostic index modelling reveals an essential role for base excision repair in influencing clinical outcomes in ER negative and triple negative breast cancers.

    PubMed

    Abdel-Fatah, Tarek M A; Arora, Arvind; Moseley, Paul M; Perry, Christina; Rakha, Emad A; Green, Andrew R; Chan, Stephen Y T; Ellis, Ian O; Madhusudan, Srinivasan

    2015-09-01

    Stratification of oestrogen receptor (ER) negative and triple negative breast cancers (TNBCs) is urgently needed. In the current study, a cohort of 880 ER- (including 635 TNBCs) was immuno-profiled for a panel of DNA repair proteins including: Pol β, FEN1, APE1, XRCC1, SMUG1, PARP1, BRCA1, ATR, ATM, DNA-PKcs, Chk1, Chk2, p53, and TOPO2. Multivariate Cox proportional hazards models (with backward stepwise exclusion of these factors, using a criterion of p < 0.05 for retention of factors in the model) were used to identify factors that were independently associated with clinical outcomes. XRCC1 (p = 0.002), pol β (p = 0.032) FEN1 (p = 0.001) and BRCA1 (p = 0.040) levels were independently associated with poor BCSS. Subsequently, DNA repair index prognostic (DRPI) scores for breast cancer specific survival (BCSS) were calculated and two prognostic groups (DRPI-PGs) were identified. Patients in prognostic group 2 (DRPI-PG2) have higher risk of death (p < 0.001). Furthermore, in DRPI-PG2 patients, exposure to anthracycline reduced the risk of death [(HR (95% CI) = 0.79 (0.64-0.98), p = 0.032) by 21-26%. In addition, DRPI-PG2 patients have adverse clinicopathological features including higher grade, lympho-vascular invasion, Her-2 positive phenotype, compared to those in DRPI-PG1 (p < 0.01). Receiver operating characteristic (ROC) curves indicated that the DRPI outperformed the currently used prognostic factors and adding DRPI to lymph node stage significantly improved their performance as a predictor for BCSS [p < 0.00001, area under curve (AUC) = 0.70]. BER strongly influences pathogenesis of ER- and TNBCs. The DRPI accurately predicts BCSS and can also serve as a valuable prognostic and predictive tool for TNBCs. PMID:26267318

  5. Two-dimensional fluid-filled closed-cell cellular solid as an acoustic metamaterial with negative index

    NASA Astrophysics Data System (ADS)

    Dorodnitsyn, V.; Van Damme, B.

    2016-04-01

    A concept for acoustic metamaterials consisting of a cellular medium with fluid-filled cells is fabricated and studied experimentally. In such a system, the fluid and solid structure explicitly interact, and elastic wave propagation is coupled to both phases. Focusing here on shear wave behavior, we confirm previous numerical studies in three steps. We first measure the material deformations pertaining to three qualitatively different shear wave modes in the frequency range below 3.5 kHz. We then measure the group velocity and demonstrate that, within a certain frequency interval, the group and phase velocity have opposite signs. This shows that the system acts as a negative-index metamaterial. Finally, we confirm the presence of band gaps due to the locally resonant behavior of the cell walls. The demonstrated concept of a closed, fluid-filled cellular material as an acoustic metamaterial opens a wide space for applications.

  6. Anomalous lasing of high-speed 850 nm InGaAlAs oxide-confined vertical-cavity surface-emitting lasers with a large negative gain-to-cavity wavelength detuning

    SciTech Connect

    Blokhin, S. A. Bobrov, M. A.; Maleev, N. A.; Sakharov, A. V.; Ustinov, V. M.; Kuzmenkov, A. G.; Blokhin, A. A.; Moser, P.; Lott, J. A.; Bimberg, D.

    2014-08-11

    The impact of a large negative quantum well gain-to-cavity etalon wavelength detuning on the static and dynamic characteristics of 850 nm InGaAlAs high-speed oxide-confined vertical-cavity surface-emitting lasers (VCSELs) was investigated. Three distinct lasing regimes were revealed in large square aperture (≥7 μm per side) devices with large detuning including: (1) an anomalous lasing via higher order Hermite–Gaussian modes at low forward bias current; (2) lasing via the lowest order Hermite–Gaussian modes at high bias current; and (3) simultaneous lasing via both types of transverse modes at intermediate bias currents. In contrast to conventional multimode VCSELs a two-resonance modulation response was observed for the case of co-lasing via multiple transverse modes with high spectral separation. The reduction in the oxide aperture area resulted in classical lasing via the lowest order modes with a conventional single-resonance frequency response.

  7. Negative refractive index electron `optics', pseudospintronics and chiral tunneling in graphene pn junction -- beating the Landauer switching limit?

    NASA Astrophysics Data System (ADS)

    Sajjad, Redwan; Pan, Chenyun; Naeemi, Azad; Ghosh, Avik

    2013-03-01

    We use atomistic quantum kinetic calculations to demonstrate how graphene PN junctions can switch with high ON currents, low OFF currents, steep gate transfer characteristics and unipolar rectification. The physics of such unconventional switching relies on (a) field-engineering with patterned gates to create a transmission gap, by sequential filtering of all propagating modes, and (b) using tilted junctions to suppress Klein tunneling under appropriate gate biasing, making that transmission gap gate tunable. The doping ratio of the junction dictates the energy range over which the tilt angle exceeds the critical angle for transmission, generating thereby a gate tunable transmission gap that enables switching at voltages less than the Landauer-Shannon thermal limit. The underlying physics involves a combination of `electron optics' driven by Snell's law, negative index metamaterial with a PN junction, and pseudospin driven chiral tunneling, for which we also present experimental verification. [Sajjad et al, APL 99, 123101 (2011); Sajjad et al, PRB 86, 155412 (2012)]. Authors acknowledge financial grant from NRI-INDEX

  8. Lasing-Polarization-Dependent Output from Orthogonal Waveguides in High-Index-Contrast Subwavelength Grating Vertical-Cavity Surface-Emitting Laser

    NASA Astrophysics Data System (ADS)

    Tsunemi, Yoshihiro; Ikeda, Kazuhiro; Kawaguchi, Hitoshi

    2013-09-01

    We propose a high-index-contrast subwavelength grating vertical-cavity surface-emitting laser (HCG-VCSEL) incorporating a polarization-independent HCG coupled with two orthogonal in-plane output waveguides and numerically investigate the optical output characteristics from the waveguides using a three-dimensional finite-difference time-domain method. The light coupled more strongly to the waveguide in the direction perpendicular to the polarization of the resonant mode than to that in the parallel direction. The extinction ratio between the waveguides was 11.9, indicating that the output waveguide can be switched by changing the lasing polarization. The propagating modes in the strongly and weakly coupled waveguides were the TE and TM modes, respectively.

  9. Triple-negative breast cancers are increased in black women regardless of age or body mass index

    PubMed Central

    Stead, Lesley A; Lash, Timothy L; Sobieraj, Jerome E; Chi, Dorcas D; Westrup, Jennifer L; Charlot, Marjory; Blanchard, Rita A; Lee, John C; King, Thomas C; Rosenberg, Carol L

    2009-01-01

    Introduction We investigated clinical and pathologic features of breast cancers (BC) in an unselected series of patients diagnosed in a tertiary care hospital serving a diverse population. We focused on triple-negative (Tneg) tumours (oestrogen receptor (ER), progesterone receptor (PR) and HER2 negative), which are associated with poor prognosis. Methods We identified female patients with invasive BC diagnosed between 1998 and 2006, with data available on tumor grade, stage, ER, PR and HER2 status, and patient age, body mass index (BMI) and self-identified racial/ethnic group. We determined associations between patient and tumour characteristics using contingency tables and multivariate logistic regression. Results 415 cases were identified. Patients were racially and ethnically diverse (born in 44 countries, 36% white, 43% black, 10% Hispanic and 11% other). 47% were obese (BMI > 30 kg/m2). 72% of tumours were ER+ and/or PR+, 20% were Tneg and 13% were HER2+. The odds of having a Tneg tumour were 3-fold higher (95% CI 1.6, 5.5; p = 0.0001) in black compared with white women. Tneg tumours were equally common in black women diagnosed before and after age 50 (31% vs 29%; p = NS), and who were obese and non-obese (29% vs 31%; p = NS). Considering all patients, as BMI increased, the proportion of Tneg tumours decreased (p = 0.08). Conclusions Black women of diverse background have 3-fold more Tneg tumours than non-black women, regardless of age and BMI. Other factors must determine tumour subtype. The higher prevalence of Tneg tumours in black women in all age and weight categories likely contributes to black women's unfavorable breast cancer prognosis. PMID:19320967

  10. Material parameter retrieval procedure for general bi-isotropic metamaterials and its application to optical chiral negative-index metamaterial design.

    PubMed

    Kwon, Do-Hoon; Werner, Douglas H; Kildishev, Alexander V; Shalaev, Vladimir M

    2008-08-01

    A chiral optical negative-index metamaterial design of doubly periodic construction for the near-infrared spectrum is presented. The chirality is realized by incorporating sub-wavelength planar silver-aluminasilver resonators and arranging them in a left-handed helical (i.e., stair-step) configuration as a wave propagates through the metamaterial. An effective material parameter retrieval procedure is developed for general bi-isotropic metamaterials. A numerical design example is presented and the retrieved effective material parameters exhibiting a negative index of refraction are provided. PMID:18679454

  11. Measurement of air-refractive-index fluctuation from frequency change using a phase modulation homodyne interferometer and an external cavity laser diode

    NASA Astrophysics Data System (ADS)

    Ishige, Masashi; Aketagawa, Masato; Banh Quoc, Tuan; Hoshino, Yuta

    2009-08-01

    We present a method for air-refractive-index (nair) fluctuation measurement using a laser interferometer. The method is based on a combination of a phase modulation homodyne interferometer (PMHI), an external cavity laser diode (ECLD) and an ultralow thermal expansion material (ULTEM). The PMHI utilizes a Michelson interferometer which is constructed on the ULTEM plate under the condition of an air temperature fluctuation of less than 10 mK, so that the optical path change or the air-refractive-index fluctuation (Δnair) caused by the thermal disturbance can be neglected. Meanwhile, the ECLD is controlled by adjusting its frequency to track some of the dark fringes of the interferometer, so that Δnair can be derived from the ECLD frequency change. The uncertainty of the Δnair measurement in the experiment is of 10-8 order. However, it will be possible to decrease the uncertainty to 10-9 or less if the signal-to-noise ratio (SNR) of the control system is improved.

  12. Characteristics of 40 primary extranodal non-Hodgkin lymphomas of the oral cavity in perspective of the new WHO classification and the International Prognostic Index.

    PubMed

    van der Waal, R I F; Huijgens, P C; van der Valk, P; van der Waal, I

    2005-06-01

    Non-Hodgkin lymphomas (NHLs) are often present outside the lymph nodes. Although primary extranodal NHLs (PE-NHL) form a substantial part of all NHLs, reports on oral PE-NHLs are rare. Forty patients with PE-NHL of the oral cavity have been studied for the distribution of gender, age, oral subsite and presenting complaint, histological subtype according to the WHO classification, clinical stage, treatment, and follow-up. The data are reviewed against the background of the literature. Furthermore, the International Prognostic Index has been taken into consideration. All patients had a lymphoma of B-cell lineage. Two-thirds of patients presented with locoregional disease. Mean survival time was 38 months, with a mean recurrence-free survival time of 31 months. There was no statistically significant difference in survival time between patients with bone versus soft tissue localisation of the PE-NHL. In view of the rarity of PE-NHL involving the oral region multicenter studies are needed for evaluation of the usefulness of the International Prognostic Index for non-Hodgkin lymphoma in this particular part of the body. PMID:16053848

  13. Abdominal Cavity Eventration Treated by Means of the "Open Abdomen" Technique Using the Negative Pressure Therapy System--Case Report and Literature Review.

    PubMed

    Trzeciak, Piotr W; Porzeżyńska, Joanna; Ptasińska, Karolina; Walczak, Dominik A

    2015-11-01

    Wound dehiscence is a surgical complication in which the wound ruptures along the surgical suture with abdominal cavity bowel displacement. It is observed in 0.2-6% of operated patients. The extensive wound is a gateway for infection. Moreover, increased secretion of serous fluid induces a hygienic problem and may lead to secondary skin infections or bedsores. The negative pressure wound therapy (NPWT) system is an innovative therapeutic method. It perfectly executes the TIME strategy, receiving more and more recognition. The study presented a case of a 62-year old male patient after several consecutive wound dehiscence episodes who was primarily treated for rectal cancer by means of low anterior resection of the rectum. Due to acute respiratory insufficiency after several operations, wound necrosis with dehiscence was observed. Considering the high risk of perioperative death we abandoned surgical treatment and introduced conservative management using negative pressure wound therapy until the patient's health improved. Literature regarding the above-mentioned issue was also reviewed. PMID:26816408

  14. A Negative Index Metamaterial-Inspired UWB Antenna with an Integration of Complementary SRR and CLS Unit Cells for Microwave Imaging Sensor Applications

    PubMed Central

    Islam, Mohammad Tariqul; Islam, Md. Moinul; Samsuzzaman, Md.; Faruque, Mohammad Rashed Iqbal; Misran, Norbahiah

    2015-01-01

    This paper presents a negative index metamaterial incorporated UWB antenna with an integration of complementary SRR (split-ring resonator) and CLS (capacitive loaded strip) unit cells for microwave imaging sensor applications. This metamaterial UWB antenna sensor consists of four unit cells along one axis, where each unit cell incorporates a complementary SRR and CLS pair. This integration enables a design layout that allows both a negative value of permittivity and a negative value of permeability simultaneous, resulting in a durable negative index to enhance the antenna sensor performance for microwave imaging sensor applications. The proposed MTM antenna sensor was designed and fabricated on an FR4 substrate having a thickness of 1.6 mm and a dielectric constant of 4.6. The electrical dimensions of this antenna sensor are 0.20 λ × 0.29 λ at a lower frequency of 3.1 GHz. This antenna sensor achieves a 131.5% bandwidth (VSWR < 2) covering the frequency bands from 3.1 GHz to more than 15 GHz with a maximum gain of 6.57 dBi. High fidelity factor and gain, smooth surface-current distribution and nearly omni-directional radiation patterns with low cross-polarization confirm that the proposed negative index UWB antenna is a promising entrant in the field of microwave imaging sensors. PMID:26007721

  15. A Negative Index Metamaterial-Inspired UWB Antenna with an Integration of Complementary SRR and CLS Unit Cells for Microwave Imaging Sensor Applications.

    PubMed

    Islam, Mohammad Tariqul; Islam, Md Moinul; Samsuzzaman, Md; Faruque, Mohammad Rashed Iqbal; Misran, Norbahiah

    2015-01-01

    This paper presents a negative index metamaterial incorporated UWB antenna with an integration of complementary SRR (split-ring resonator) and CLS (capacitive loaded strip) unit cells for microwave imaging sensor applications. This metamaterial UWB antenna sensor consists of four unit cells along one axis, where each unit cell incorporates a complementary SRR and CLS pair. This integration enables a design layout that allows both a negative value of permittivity and a negative value of permeability simultaneous, resulting in a durable negative index to enhance the antenna sensor performance for microwave imaging sensor applications. The proposed MTM antenna sensor was designed and fabricated on an FR4 substrate having a thickness of 1.6 mm and a dielectric constant of 4.6. The electrical dimensions of this antenna sensor are 0.20 λ × 0.29 λ at a lower frequency of 3.1 GHz. This antenna sensor achieves a 131.5% bandwidth (VSWR < 2) covering the frequency bands from 3.1 GHz to more than 15 GHz with a maximum gain of 6.57 dBi. High fidelity factor and gain, smooth surface-current distribution and nearly omni-directional radiation patterns with low cross-polarization confirm that the proposed negative index UWB antenna is a promising entrant in the field of microwave imaging sensors. PMID:26007721

  16. Early peripheral lymph node involvement of human herpesvirus 8-associated, body cavity-based lymphoma in a human immunodeficiency virus-negative patient.

    PubMed

    Ariad, S; Benharroch, D; Lupu, L; Davidovici, B; Dupin, N; Boshoff, C

    2000-05-01

    Human herpesvirus 8 (HHV-8), or Kaposi sarcoma-associated herpesvirus, is a gamma herpesvirus first detected in a specimen of Kaposi sarcoma from a human immunodeficiency virus (HIV)-positive patient. Human herpesvirus 8 is also found in an unusual clinicopathologic form of body cavity-based B-cell lymphoma, which has been named primary effusion lymphoma (PEL) and occurs primarily in HIV-positive patients. PEL is characterized by the formation of lymphomatous effusions, without obvious lymphadenopathy, tumor masses, or bone marrow involvement. Only a few cases of PEL in HIV-seronegative patients have been reported. We describe a case of an HHV-8-associated lymphoma, with ascites, pleural effusion, and axillary lymphadenopathy in an HIV-negative patient. The patient was a 68-year-old Jewish man of North African extraction, with a previous history of coronary bypass surgery and multiple blood transfusions. The pleural fluid contained large atypical lymphoid cells and was suggestive of lymphoma but could not provide a conclusive diagnosis of PEL. The lymph node contained groups of large anaplastic lymphoid cells. Polymerase chain reaction for HHV-8 performed on the lymph node specimen was positive, establishing the diagnosis of PEL. Polymerase chain reaction for Epstein-Barr virus was negative. Results of a gallium scan were normal. The patient did not respond to combination chemotherapy with cyclophosphamide, doxorubicin, vincristine sulfate, and prednisone and progressively developed, massive intra-abdominal solid tumor formation. To our knowledge, this is the first report of a case of PEL that demonstrates peripheral lymph node involvement at diagnosis and the first report of PEL in an Israeli patient. PMID:10782162

  17. New insights into the prognostic value of Ki-67 labeling index in patients with triple-negative breast cancer.

    PubMed

    Hao, Shuang; He, Zhi-Xian; Yu, Ke-Da; Yang, Wen-Tao; Shao, Zhi-Min

    2016-04-26

    The clinicopathological importance of the Ki-67 labeling index (LI) in breast cancer has been studied intensely; however, its prognostic significance in triple-negative breast cancer (TNBC) is unclear. We aimed to determine the optimal Ki-67 cut-off point to demonstrate its prognostic relevance for breast-cancer-specific survival (BCSS) in TNBC patients. A total of 571 female TNBC patients underwent diagnosis and surgery at our institution from January 2002 to June 2011. Clinicopathological information for all patients was available and categorized by Ki-67 LI and age at diagnosis. The cut-off values for Ki-67 LI and age were selected using the medians. A varying-coefficient Cox model was used to describe the effect of Ki-67 LI on BCSS outcomes changing with age after adjustment for disease characteristics. For survival analysis, the Kaplan-Meier method and the log-rank test were used. Cox proportional hazards models were applied to determine the association of Ki-67 LI and age with BCSS outcomes after adjustment for disease characteristics. Median age was 50 years, and median Ki-67 LI was 35% (range, 0 - 97.5%). There was no prognostic significance of stratification by Ki-67 LI in all patients. When analyzing age at diagnosis as a continuous variable, the log-transformed HRKi67 > 35% vs. ≤ 35% for BCSS increased in an S-shaped curve with increasing age up to about 50 years-old and remained higher-risk for high Ki-67 LI. After adjusting for clinicopathological risk factors, low Ki-67 LI was a poor prognostic factor for BCSS (HR: 0.36, 95% CI: 0.14-0.96, P = 0.042) in patients of ≤ 50 years, but not in patients diagnosed at > 50 years (hazard ratio [HR]: 1.57, 95% CI: 0.76-3.22, P = 0.241). In conclusion, lower Ki-67 LI has poor prognosis relevance in TNBC patients diagnosed at ≤ 50 years-old. Further validation of the clinical significance of Ki-67 LI in TNBC is required. PMID:27050075

  18. Fresnel reflection from a cavity with net roundtrip gain

    SciTech Connect

    Mansuripur, Tobias S.; Mansuripur, Masud

    2014-03-24

    A planewave incident on an active etalon with net roundtrip gain may be expected to diverge in field amplitude, yet applying the Fresnel formalism to Maxwell's equations admits a convergent solution. We describe this solution mathematically and provide additional insight by demonstrating the response of such a cavity to an incident beam of light. Cavities with net roundtrip gain have often been overlooked in the literature, and a clear understanding of their behavior yields insight to negative refraction in nonmagnetic media, a duality between loss and gain, amplified total internal reflection, and the negative-index lens.

  19. Negative Impact and Positive Value in Caregiving: Validation of the COPE Index in a Six-Country Sample of Carers

    ERIC Educational Resources Information Center

    Balducci, Cristian; Mnich, Eva; McKee, Kevin J.; Lamura, Giovanni; Beckmann, Anke; Krevers, Barbro; Wojszel, Z. Beata; Nolan, Mike; Prouskas, Constantinos; Bien, Barbara; Oberg, Birgitta

    2008-01-01

    Purpose: The present study attempts to further validate the COPE Index on a large sample of carers drawn from six European countries. Design and Methods: We used a cross-sectional survey, with approximately 1,000 carers recruited in each of six countries by means of a common standard evaluation protocol. Our saturation recruitment of a designated…

  20. Transmission gap, Bragg-like reflection, and Goos-Haenchen shifts near the Dirac point inside a negative-zero-positive index metamaterial slab

    SciTech Connect

    Chen Xi; Wang Ligang; Li Chunfang

    2009-10-15

    Motivated by the realization of the Dirac point (DP) with a double-cone structure for optical field in the negative-zero-positive index metamaterial (NZPIM), the reflection, transmission, and Goos-Haenchen (GH) shifts inside the NZPIM slab are investigated. Due to the linear Dirac dispersion, the transmission as the function of the frequency has a gap, thus, the corresponding reflection has a frequency or wavelength window for the perfect reflection, which is similar to the Bragg reflection in the one-dimensional photonic crystals. Near the DP, the associated GH shifts in the transmission and reflection can be changed from positive to negative with increasing the wavelength. These negative and positive shifts can also be enhanced by transmission resonances when the frequency is far from that at the DP. All these phenomena will lead to some potential applications in the integrated optics and optical devices.

  1. Preattentive processing of lexical tone perception by the human brain as indexed by the mismatch negativity paradigm.

    PubMed

    Sittiprapaporn, Wichian; Chindaduangratn, Chittin; Tervaniemi, Mari; Khotchabhakdi, Naiphinich

    2003-11-01

    Mismatch negativity (MMN) was used to investigate the processing of the discrimination between native and non-native CV syllables in tonal languages. MMN elicited by the native word was greater than that elicited by the non-native word. Hearing a native-language deviant significantly altered the elicited MMN in both amplitude and scalp voltage field distribution, reflecting the presence of a long-term memory trace for spoken words in tonal languages. PMID:14681141

  2. Fundamentals of negative refractive index optical trapping: forces and radiation pressures exerted by focused Gaussian beams using the generalized Lorenz-Mie theory

    PubMed Central

    Ambrosio, Leonardo A.; Hernández-Figueroa, Hugo E.

    2010-01-01

    Based on the generalized Lorenz-Mie theory (GLMT), this paper reveals, for the first time in the literature, the principal characteristics of the optical forces and radiation pressure cross-sections exerted on homogeneous, linear, isotropic and spherical hypothetical negative refractive index (NRI) particles under the influence of focused Gaussian beams in the Mie regime. Starting with ray optics considerations, the analysis is then extended through calculating the Mie coefficients and the beam-shape coefficients for incident focused Gaussian beams. Results reveal new and interesting trapping properties which are not observed for commonly positive refractive index particles and, in this way, new potential applications in biomedical optics can be devised. PMID:21258549

  3. Large enhancement of interface second-harmonic generation near the zero-n(-) gap of a negative-index Bragg grating.

    PubMed

    D'Aguanno, Giuseppe; Mattiucci, Nadia; Bloemer, Mark J; Scalora, Michael

    2006-03-01

    We predict a large enhancement of interface second-harmonic generation near the zero-n(-) gap of a Bragg grating made of alternating layers of negative- and positive-index materials. Field localization and coherent oscillations of the nonlinear dipoles located at the structure's interfaces conspire to yield conversion efficiencies at least an order of magnitude greater than those achievable in the same length of nonlinear, phase-matched bulk material. These findings thus point to a new class of second-harmonic-generation devices made of standard centrosymmetric materials. PMID:16605673

  4. Role of phase matching in pulsed second-harmonic generation: Walk-off and phase-locked twin pulses in negative-index media

    SciTech Connect

    Roppo, Vito; Centini, Marco; Sibilia, Concita; Bertolotti, Mario; De Ceglia, Domenico; Scalora, Michael; Akozbek, Neset; Bloemer, Mark J.; Haus, Joseph W.; Kosareva, Olga G.; Kandidov, Valery P.

    2007-09-15

    The present investigation is concerned with the study of pulsed second-harmonic generation under conditions of phase and group velocity mismatch, and generally low conversion efficiencies and pump intensities. In positive-index, nonmetallic materials, we generally find qualitative agreement with previous reports regarding the presence of a double-peaked second harmonic signal, which comprises a pulse that walks off and propagates at the nominal group velocity one expects at the second-harmonic frequency, and a second pulse that is 'captured' and propagates under the pump pulse. We find that the origin of the double-peaked structure resides in a phase-locking mechanism that characterizes not only second-harmonic generation, but also {chi}{sup (3)} processes and third-harmonic generation. The phase-locking mechanism that we describe occurs for arbitrarily small pump intensities, and so it is not a soliton effect, which usually relies on a threshold mechanism, although multicolor solitons display similar phase locking characteristics. Thus, in second harmonic generation a phase-matched component is always generated, even under conditions of material phase mismatch: This component is anomalous, because the material does not allow energy exchange between the pump and the second-harmonic beam. On the other hand, if the material is phase matched, phase locking and phase matching are indistinguishable, and the conversion process becomes efficient. We also report a similar phase-locking phenomenon in negative index materials. A spectral analysis of the pump and the generated signals reveals that the phase-locking phenomenon causes the forward moving, phase-locked second-harmonic pulse to experience the same negative index as the pump pulse, even though the index of refraction at the second-harmonic frequency is positive. Our analysis further shows that the reflected second-harmonic pulse generated at the interface and the forward-moving, phase-locked pulse appear to be part

  5. Mismatch negativity indexes illness-specific impairments of cortical plasticity in schizophrenia: a comparison with bipolar disorder and Alzheimer's disease.

    PubMed

    Baldeweg, Torsten; Hirsch, Steven R

    2015-02-01

    Cognitive impairment is an important predictor of functional outcome in patients with schizophrenia, yet its neurobiology is still incompletely understood. Neuropathological evidence of impaired synaptic connectivity and NMDA receptor-dependent transmission in superior temporal cortex motivated us to explore the correlation of in vivo mismatch negativity (MMN) with cognitive status in patients with schizophrenia. MMN elicited in a roving stimulus paradigm displayed a response proportional to the number of stimulus repetitions (memory trace effect). Preliminary evidence in patients with chronic schizophrenia suggests that attenuation of this MMN memory trace effect was correlated with the degree of neuropsychological memory dysfunction. Here we present data from a larger confirmatory study in patients with schizophrenia, bipolar disorder, probable Alzheimer's disease and healthy controls. We observed that the diminution of the MMN memory trace effect and its correlation with memory impairment was only found in the schizophrenia group. Recent pharmacological studies using the roving paradigm suggest that attenuation of the MMN trace effect can be understood as abnormal modulation of NMDA receptor-dependent plasticity. We suggest that the convergence of the previously identified synaptic pathology in supragranular cortical layers with the intracortical locus of MMN generation accounts for the remarkable robustness of MMN impairments in schizophrenia. We further speculate that this layer-specific synaptic pathology identified in supragranular neurons plays a pivotal computational role, by weakening the encoding and propagation of prediction errors to higher cortical modules. According to predictive coding theory such breakdown will have grave implications not only for perception, but also for higher-order cognition and may thus account for the MMN-cognition correlations observed here. Finally, MMN is a sensitive and specific biomarker for detecting the early prodromal

  6. Relationship between the Rorschach Perceptual Thinking Index (PTI) and the Positive and Negative Syndrome Scale (PANSS) in psychotic patients: a validity study.

    PubMed

    Biagiarelli, Mario; Roma, Paolo; Comparelli, Anna; Andraos, Maria Paola; Di Pomponio, Ileana; Corigliano, Valentina; Curto, Martina; Masters, Grace Allison; Ferracuti, Stefano

    2015-02-28

    The aim of this study is to demonstrate the validity of the Rorschach Perceptual Thinking Index (PTI) in the assessment of reality testing in patients with psychosis. We evaluated the relationship between the PTI criteria and the Positive and Negative Syndrome Scale (PANSS) scores in 98 psychotic disorder affected patients. Thirty four were evaluated during the acute episode (AP) and 64 were chronically treated and stable (CP). The PANSS positive score resulted significantly higher in AP than in CP group, but no significant difference was found in the PTI score. The PTI positively correlated with the PANSS total score. The PTI1 and PTI2 criteria significantly correlated with the PANSS negative score, the PTI4 and PTI5 with the positive. The Rorschach variable X-% significantly correlated with the negative symptoms; the WSum6 with thought disorders; and the M- with delusions. PTI score, X-% and WSum6 predicted impaired judgment and insight. These results suggest that PTI is a valid instrument to assess impairment in reality testing, regardless of the patient׳s current psychiatric presentation. The presence of conceptual disorganization, delusions, lack of judgment and insight don׳t have effects on the PTI, supporting its strength as an assessment tool for psychotic disorders. PMID:25560479

  7. Revisiting the Balazs thought experiment in the case of a left-handed material: electromagnetic-pulse-induced displacement of a dispersive, dissipative negative-index slab.

    PubMed

    Chau, Kenneth J; Lezec, Henri J

    2012-04-23

    We propose a set of postulates to describe the mechanical interaction between a plane-wave electromagnetic pulse and a dispersive, dissipative slab having a refractive index of arbitrary sign. The postulates include the Abraham electromagnetic momentum density, a generalized Lorentz force law, and a model for absorption-driven mass transfer from the pulse to the medium. These opto-mechanical mechanisms are incorporated into a one-dimensional finite-difference time-domain algorithm that solves Maxwell's equations and calculates the instantaneous force densities exerted by the pulse onto the slab, the momentum-per-unit-area of the pulse and slab, and the trajectories of the slab and system center-of-mass. We show that the postulates are consistent with conservation of global energy, momentum, and center-of-mass velocity at all times, even for cases in which the refractive index of the slab is negative or zero. Consistency between the set of postulates and well-established conservation laws reinforces the Abraham momentum density as the one true electromagnetic momentum density and enables, for the first time, identification of the correct form of the electromagnetic mass density distribution and development of an explicit model for mass transfer due to absorption, for the most general case of a ponderable medium that is both dispersive and dissipative. PMID:22535106

  8. Performance of the Prostate Health Index in predicting prostate biopsy outcomes among men with a negative digital rectal examination and transrectal ultrasonography.

    PubMed

    Yu, Guo-Peng; Na, Rong; Ye, Ding-Wei; Qi, Jun; Liu, Fang; Chen, Hai-Tao; Wu, Yi-Shuo; Zhang, Gui-Ming; Sun, Jie-Lin; Zhu, Yao; Huang, Li-Qun; Ren, Shan-Cheng; Jiang, De-Ke; Zheng, S Lilly; Jiang, Hao-Wen; Sun, Ying-Hao; Ding, Qiang; Xu, Jianfeng

    2016-01-01

    The [-2]proPSA (p2PSA) and its derivatives, the p2PSA-to-free PSA ratio (%p2PSA), and the Prostate Health Index (PHI) have greatly improved discrimination between men with and without prostate cancer (PCa) in prostate biopsies. However, little is known about their performance in cases where a digital rectal examination (DRE) and transrectal ultrasonography (TRUS) are negative. A prospective cohort of 261 consecutive patients in China with negative DRE and TRUS were recruited and underwent prostate biopsies. A serum sample had collected before the biopsy was used to measure various PSA derivatives, including total prostate-specific antigen (tPSA), free PSA, and p2PSA. For each patient, the free-to-total PSA ratio (%fPSA), PSA density (PSAD), p2PSA-to-free PSA ratio (%p2PSA), and PHI were calculated. Discriminative performance was assessed using the area under the receiver operating characteristic curve (AUC) and the biopsy rate at 91% sensitivity. The AUC scores within the entire cohort with respect to age, tPSA, %fPSA, PSAD, p2PSA, %p2PSA, and PHI were 0.598, 0.751, 0.646, 0.789, 0.814, 0.808, and 0.853, respectively. PHI was the best predictor of prostate biopsy results, especially in patients with a tPSA of 10.1-20 ng ml-1 . Compared with other markers, at a sensitivity of 91%, PHI was the most useful for determining which men did not need to undergo biopsy, thereby avoiding unnecessary procedures. The use of PHI could improve the accuracy of PCa detection by predicting prostate biopsy outcomes among men with a negative DRE and TRUS in China. PMID:26975483

  9. Performance of the Prostate Health Index in predicting prostate biopsy outcomes among men with a negative digital rectal examination and transrectal ultrasonography

    PubMed Central

    Yu, Guo-Peng; Na, Rong; Ye, Ding-Wei; Qi, Jun; Liu, Fang; Chen, Hai-Tao; Wu, Yi-Shuo; Zhang, Gui-Ming; Sun, Jie-Lin; Zhu, Yao; Huang, Li-Qun; Ren, Shan-Cheng; Jiang, De-Ke; Zheng, S L; Jiang, Hao-Wen; Sun, Ying-Hao; Ding, Qiang; Xu, Jianfeng

    2016-01-01

    The [-2]proPSA (p2PSA) and its derivatives, the p2PSA-to-free PSA ratio (%p2PSA), and the Prostate Health Index (PHI) have greatly improved discrimination between men with and without prostate cancer (PCa) in prostate biopsies. However, little is known about their performance in cases where a digital rectal examination (DRE) and transrectal ultrasonography (TRUS) are negative. A prospective cohort of 261 consecutive patients in China with negative DRE and TRUS were recruited and underwent prostate biopsies. A serum sample had collected before the biopsy was used to measure various PSA derivatives, including total prostate-specific antigen (tPSA), free PSA, and p2PSA. For each patient, the free-to-total PSA ratio (%fPSA), PSA density (PSAD), p2PSA-to-free PSA ratio (%p2PSA), and PHI were calculated. Discriminative performance was assessed using the area under the receiver operating characteristic curve (AUC) and the biopsy rate at 91% sensitivity. The AUC scores within the entire cohort with respect to age, tPSA, %fPSA, PSAD, p2PSA, %p2PSA, and PHI were 0.598, 0.751, 0.646, 0.789, 0.814, 0.808, and 0.853, respectively. PHI was the best predictor of prostate biopsy results, especially in patients with a tPSA of 10.1–20 ng ml−1. Compared with other markers, at a sensitivity of 91%, PHI was the most useful for determining which men did not need to undergo biopsy, thereby avoiding unnecessary procedures. The use of PHI could improve the accuracy of PCa detection by predicting prostate biopsy outcomes among men with a negative DRE and TRUS in China. PMID:26975483

  10. Plasma bile acids show a positive correlation with body mass index and are negatively associated with cognitive restraint of eating in obese patients

    PubMed Central

    Prinz, Philip; Hofmann, Tobias; Ahnis, Anne; Elbelt, Ulf; Goebel-Stengel, Miriam; Klapp, Burghard F.; Rose, Matthias; Stengel, Andreas

    2015-01-01

    Bile acids may be involved in the regulation of food intake and energy metabolism. The aim of the study was to investigate the association of plasma bile acids with body mass index (BMI) and the possible involvement of circulating bile acids in the modulation of physical activity and eating behavior. Blood was obtained in a group of hospitalized patients with normal weight (BMI 18.5–25 kg/m2), underweight (anorexia nervosa, BMI < 17.5 kg/m2) and overweight (obesity with BMI 30–40, 40–50 and >50 kg/m2, n = 14–15/group) and plasma bile acid concentrations assessed. Physical activity and plasma bile acids were measured in a group of patients with anorexia nervosa (BMI 14.6 ± 0.3 kg/m2, n = 43). Lastly, in a population of obese patients (BMI 48.5 ± 0.9 kg/m2, n = 85), psychometric parameters related to disordered eating and plasma bile acids were assessed. Plasma bile acids showed a positive correlation with BMI (r = 0.26, p = 0.03) in the population of patients with broad range of BMI (9–85 kg/m2, n = 74). No associations were observed between plasma bile acids and different parameters of physical activity in anorexic patients (p > 0.05). Plasma bile acids were negatively correlated with cognitive restraint of eating (r = −0.30, p = 0.008), while no associations were observed with other psychometric eating behavior-related parameters (p > 0.05) in obese patients. In conclusion, these data may point toward a role of bile acids in the regulation of body weight. Since plasma bile acids are negatively correlated with the cognitive restraint of eating in obese patients, this may represent a compensatory adaptation to prevent further overeating. PMID:26089773

  11. Changeability of Oral Cavity Environment

    PubMed Central

    Surdacka, Anna; Strzyka³a, Krystyna; Rydzewska, Anna

    2007-01-01

    Objectives In dentistry, the results of in vivo studies on drugs, dental fillings or prostheses are routinely evaluated based on selected oral cavity environment parameters at specific time points. Such evaluation may be confounded by ongoing changes in the oral cavity environment induced by diet, drug use, stress and other factors. The study aimed to confirm oral cavity environment changeability. Methods 24 healthy individuals aged 20–30 had their oral cavity environment prepared by having professional hygiene procedures performed and caries lesions filled. Baseline examination and the examination two years afterwards, evaluated clinical and laboratory parameters of oral cavity environment. Caries incidence was determined based on DMFT and DMFS values, oral cavity hygiene on Plaque Index (acc. Silness & Loe) and Hygiene Index (acc. O’Leary), and the gingival status on Gingival Index (acc. Loe & Silness) and Gingival Bleeding Index (acc. Ainamo & Bay). Saliva osmolarity, pH and concentrations of Ca2+, Pi, Na+, Cl−, total protein, albumins, F− and Sr2+ were determined. Results The results confirmed ongoing changeability of the oral cavity environment. After 2 years of the study reduction in oral cavity hygiene parameters PLI and HI (P<0.1), and gingival indices as well as lower saliva concentration of Ca2+ (P<.001), Pi (P<.06), K+ (P<.04), Sr2+ (P<.03), Na+ (P<.1), against the baseline values, were observed. Total protein and albumin saliva concentrations were also significantly lower. Conclusion Physiological oral cavity environment is subject to constant, individually different, changes which should be considered when analysing studies that employ oral cavity environment parameters. PMID:19212491

  12. Detecting negative response bias with the Fake Bad Scale, Response Bias Scale, and Henry-Heilbronner Index of the Minnesota Multiphasic Personality Inventory-2.

    PubMed

    Dionysus, Kimberly E; Denney, Robert L; Halfaker, Dale A

    2011-03-01

    The 28-item Response Bias Scale (RBS) and 15-item Henry-Heilbronner Index (HHI) are new validity scales within the Minnesota Multiphasic Personality Inventory-2, designed to detect over-reporting of cognitive and somatic symptomology, respectively. The 43-item Lees-Haley Fake Bad Scale (FBS) was designed to detect noncredible symptom presentations within a personal injury setting. The current study examined the predictive validity of these scales in a criterion-groups design involving head-injured litigants. Archival data were collected and two groups were created using the Slick, Sherman, and Iverson ([1999]. Diagnostic criteria for malingered neurocognitive dysfunction: Proposed standards for clinical practice and research. The Clinical Neuropsychologist, 13, 545-561) Criteria for Probable Negative Response Bias. Results yielded excellent to acceptable discrimination ability for the validity scales, including an area under the curve of 0.83 for FBS, 0.82 for RBS, and 0.73 for HHI. Findings suggest that the FBS, RBS, and HHI perform as well as the other validity scales in discriminating over-reporting within a head-injured litigant setting. PMID:21148668

  13. Cavity Self-Stabilization and Enhancement of Laser Gyroscopes by (Coupled) Optical Resonators

    NASA Technical Reports Server (NTRS)

    Smith, David D.

    2006-01-01

    We analyze the effect of a highly dispersive element placed inside a modulated optical cavity on the frequency and amplitude of the modulation to determine the conditions for cavity self-stabilization and enhanced gyroscopic sensitivity. Hence, we model cavity rotation or instability by an arbitrary AM/FM modulation, and the dispersive element as a phase and amplitude filter. We find that anomalous dispersion may be used to self-stabilize a laser cavity, provided the magnitude of the group index of refraction is smaller than the phase index of refraction in the cavity. The optimal stabilization is found to occur when the group index is zero. Group indices with magnitudes larger than the phase index (both normal and anomalous dispersion) are found to enhance the sensitivity of a laser gyroscope to rotation. Furthermore, our results indicate that atomic media, even coherent superpositions in multilevel atoms, are not useful for these applications, because the amplitude and phase filters work against one another, i.e., decreasing the modulation frequency increases its amplitude and vice versa, with one exception: negative group indices whose magnitudes are larger than the phase index result in negative, but enhanced, beat frequencies. On the other hand, for optical resonators the dispersion reversal associated with critical coupling enables the amplitude and phase filters to work together under a greater variety of circumstances than for atomic media. We find that for single over-coupled resonators, or in the case of under-coupled coupled-resonator-induced absorption, the absorption and normal dispersion on-resonance increase the contrast and frequency of the beat-note, respectively, resulting in a substantial enhancement of the gyroscopic response. Moreover, for cavity self-stabilization, we propose the use of a variety of coupled-resonator induced transparency that is accompanied by anomalous dispersion.

  14. Cavity magnomechanics.

    PubMed

    Zhang, Xufeng; Zou, Chang-Ling; Jiang, Liang; Tang, Hong X

    2016-03-01

    A dielectric body couples with electromagnetic fields through radiation pressure and electrostrictive forces, which mediate phonon-photon coupling in cavity optomechanics. In a magnetic medium, according to the Korteweg-Helmholtz formula, which describes the electromagnetic force density acting on a medium, magneostrictive forces should arise and lead to phonon-magnon interaction. We report such a coupled phonon-magnon system based on ferrimagnetic spheres, which we term as cavity magnomechanics, by analogy to cavity optomechanics. Coherent phonon-magnon interactions, including electromagnetically induced transparency and absorption, are demonstrated. Because of the strong hybridization of magnon and microwave photon modes and their high tunability, our platform exhibits new features including parametric amplification of magnons and phonons, triple-resonant photon-magnon-phonon coupling, and phonon lasing. Our work demonstrates the fundamental principle of cavity magnomechanics and its application as a new information transduction platform based on coherent coupling between photons, phonons, and magnons. PMID:27034983

  15. Cavity magnomechanics

    PubMed Central

    Zhang, Xufeng; Zou, Chang-Ling; Jiang, Liang; Tang, Hong X.

    2016-01-01

    A dielectric body couples with electromagnetic fields through radiation pressure and electrostrictive forces, which mediate phonon-photon coupling in cavity optomechanics. In a magnetic medium, according to the Korteweg-Helmholtz formula, which describes the electromagnetic force density acting on a medium, magneostrictive forces should arise and lead to phonon-magnon interaction. We report such a coupled phonon-magnon system based on ferrimagnetic spheres, which we term as cavity magnomechanics, by analogy to cavity optomechanics. Coherent phonon-magnon interactions, including electromagnetically induced transparency and absorption, are demonstrated. Because of the strong hybridization of magnon and microwave photon modes and their high tunability, our platform exhibits new features including parametric amplification of magnons and phonons, triple-resonant photon-magnon-phonon coupling, and phonon lasing. Our work demonstrates the fundamental principle of cavity magnomechanics and its application as a new information transduction platform based on coherent coupling between photons, phonons, and magnons. PMID:27034983

  16. Vertical-cavity surface-emitting laser device

    DOEpatents

    Hadley, G. Ronald; Lear, Kevin L.; Awyoung, Adelbert; Choquette, Kent D.

    1999-01-01

    A vertical-cavity surface-emitting laser device. The vertical-cavity surface-emitting laser (VCSEL) device comprises one or more VCSELs with each VCSEL having a mode-control region thereabout, with the mode-control region forming an optical cavity with an effective cavity length different from the effective cavity length within each VCSEL. Embodiments of the present invention can be formed as single VCSELs and as one- or two-dimensional arrays of VCSELs, with either an index-guided mode of operation or an index anti-guided mode of operation being defined by a sign of the difference in the two effective cavity lengths.

  17. Geometry-invariant resonant cavities

    NASA Astrophysics Data System (ADS)

    Liberal, I.; Mahmoud, A. M.; Engheta, N.

    2016-03-01

    Resonant cavities are one of the basic building blocks in various disciplines of science and technology, with numerous applications ranging from abstract theoretical modelling to everyday life devices. The eigenfrequencies of conventional cavities are a function of their geometry, and, thus, the size and shape of a resonant cavity is selected to operate at a specific frequency. Here we demonstrate theoretically the existence of geometry-invariant resonant cavities, that is, resonators whose eigenfrequencies are invariant with respect to geometrical deformations of their external boundaries. This effect is obtained by exploiting the unusual properties of zero-index metamaterials, such as epsilon-near-zero media, which enable decoupling of the temporal and spatial field variations in the lossless limit. This new class of resonators may inspire alternative design concepts, and it might lead to the first generation of deformable resonant devices.

  18. Geometry-invariant resonant cavities

    PubMed Central

    Liberal, I.; Mahmoud, A. M.; Engheta, N.

    2016-01-01

    Resonant cavities are one of the basic building blocks in various disciplines of science and technology, with numerous applications ranging from abstract theoretical modelling to everyday life devices. The eigenfrequencies of conventional cavities are a function of their geometry, and, thus, the size and shape of a resonant cavity is selected to operate at a specific frequency. Here we demonstrate theoretically the existence of geometry-invariant resonant cavities, that is, resonators whose eigenfrequencies are invariant with respect to geometrical deformations of their external boundaries. This effect is obtained by exploiting the unusual properties of zero-index metamaterials, such as epsilon-near-zero media, which enable decoupling of the temporal and spatial field variations in the lossless limit. This new class of resonators may inspire alternative design concepts, and it might lead to the first generation of deformable resonant devices. PMID:27010103

  19. Cavity magnomechanics

    NASA Astrophysics Data System (ADS)

    Zou, Chang-Ling; Zhang, Xufeng; Jiang, Liang; Tang, Hong

    2016-05-01

    Recently, cavity magnonics has attracted much attention for potential applications of coherent information transduction and hybrid quantum devices. The magnon is a collective spin wave excitation in ferromagnetic material. It is magnetically tunability, with long coherence time and non-reciprocical interaction with electro-magnetic fields. We report the coherent coupling between magnon, microwave photon and phonon. First, we demonstrate strong coupling and ultrastrong coupling between the magnon in YIG sphere and microwave photon in three-dimensional cavity. Then, based on the hybridized magnon-photon modes, we observe the triply resonant magnon-mcirowave photon-phonon coupling, where the ultrahigh-Q mechanical vibration of YIG sphere is dispersively coupled with the magnon via magnetostrictive interaction. We observe interesting phenomena, including electromagnetically induced transparency/absorption and parametric amplification. In particular, benefit from the large tunability of the magnon, we demonstrate a tunable microwave amplifier with gain as high as 30 dB. The single crystal YIG also has excellent optical properties, and thus provide a unique platform bridging MHz, GHz and THz information carriers. Finally, we present the latest progress towards coherent magnon to optical photon conversion.

  20. Fano-like resonances in split concentric nanoshell dimers in designing negative-index metamaterials for biological-chemical sensing and spectroscopic purposes.

    PubMed

    Ahmadivand, Arash; Karabiyik, Mustafa; Pala, Nezih

    2015-05-01

    In this study, we investigated numerically the plasmon response of a dimer configuration composed of a couple of split and concentric Au nanoshells in a complex orientation. We showed that an isolated composition of two concentric split nanoshells could be tailored to support strong plasmon resonant modes in the visible wavelengths. After determining the accurate geometric dimensions for the presented antisymmetric nanostructure, we designed a dimer array that shows complex behavior during exposure to different incident polarizations. We verified that the examined dimer was able to support destructive interference between dark and bright plasmon modes, which resulted in a pronounced Fano-like dip. Observation of a Fano minimum in such a simple molecular orientation of subwavelength particles opens new avenues for employing this structure in designing various practical plasmonic devices. Depositing the final dimer in a strong coupling condition on a semiconductor metasurface and measuring the effective refractive index at certain wavelengths, we demonstrate that each one of dimer units can be considered a meta-atom due to the high aspect ratio in the geometric parameters. Using this method, by extending the number of dimers periodically and illuminating the structure, we examined the isotropic, polarization-dependent, and transmission behavior of the metamaterial configuration. Using numerical methods and calculating the effective refractive indices, we computed and sketched corresponding figure of merit over the transmission window, where the maximum value obtained was 42.3 for Si and 54.6 for gallium phosphide (GaP) substrates. PMID:25811974

  1. Phonetic training and non-native speech perception--New memory traces evolve in just three days as indexed by the mismatch negativity (MMN) and behavioural measures.

    PubMed

    Tamminen, Henna; Peltola, Maija S; Kujala, Teija; Näätänen, Risto

    2015-07-01

    Language-specific, automatically responding memory traces form the basis for speech sound perception and new neural representations can also evolve for non-native speech categories. The aim of this study was to find out how a three-day phonetic listen-and-repeat training affects speech perception, and whether it generates new memory traces. We used behavioural identification, goodness rating, discrimination, and reaction time tasks together with mismatch negativity (MMN) brain response registrations to determine the training effects on native Finnish speakers. We trained the subjects the voicing contrast in fricative sounds. Fricatives are not differentiated by voicing in Finnish, i.e., voiced fricatives do not belong to the Finnish phonological system. Therefore, they are extremely hard for Finns to learn. However, only after three days of training, the native Finnish subjects had learned to perceive the distinction. The results show striking changes in the MMN response; it was significantly larger on the second day after two training sessions. Also, the majority of the behavioural indicators showed improvement during training. Identification altered after four sessions of training and discrimination and reaction times improved throughout training. These results suggest remarkable language-learning effects both at the perceptual and pre-attentive neural level as a result of brief listen-and-repeat training in adult participants. PMID:25956191

  2. A systematic review of the mismatch negativity as an index for auditory sensory memory: From basic research to clinical and developmental perspectives.

    PubMed

    Bartha-Doering, Lisa; Deuster, Dirk; Giordano, Vito; am Zehnhoff-Dinnesen, Antoinette; Dobel, Christian

    2015-09-01

    Auditory sensory memory is an important ability for successful language acquisition and processing. The mismatch negativity (MMN) in response to auditory stimuli has been proposed as an objective tool to measure the existence of auditory sensory memory traces. By increasing interstimulus intervals, attenuation of MMN peak amplitude and increased MMN peak latency have been suggested to reflect duration and decay of sensory memory traces. The aim of the present study is to conduct a systematic review of studies investigating sensory memory duration with MMN. Searches of electronic databases yielded 743 articles. Of these, 37 studies met final eligibility criteria. Results point to maturational changes in the time span of auditory sensory memory from birth on with a peak in young adulthood, as well as to a decrease of sensory memory duration in healthy aging. Furthermore, this review suggests that sensory memory decline is related to diverse neurological, psychiatric, and pediatric diseases, including Alzheimer's disease, alcohol abuse, schizophrenia, and language disorders. This review underlines that the MMN provides a unique window to the cognitive processes of auditory sensory memory. However, further studies combining electrophysiological and behavioral data, and further studies in clinical populations are needed, also on individual levels, to validate the MMN as a clinical tool for the assessment of sensory memory duration. PMID:26096130

  3. Cavity magnomechanics

    NASA Astrophysics Data System (ADS)

    Zhang, Xufeng; Zou, Changling; Jiang, Liang; Tang, Hong X.

    Mechanical oscillators have been recently widely utilized to couple with optical and microwave photons in a variety of hybrid quantum systems, but they all lack the tunability. The magnetostrictive force provides an alternative mechanism to allow phonon to couple with a different type of information carrier-magnon, the collective excitation of magnetization whose frequency can be tuned by a bias magnetic field. Here, we demonstrate an intriguing hybrid system that consists of a magnonic, a mechanical, and a microwave resonator. The magnon-phonon interaction results in hallmark coherent phenomena such as magnomechanically induced transparency/absorption and magnomechanical parametric amplification. The magnetic field dependence of magnon provides our system with unprecedented tunability. Moreover, the great flexibility of our system allows us to achieve triple resonance among magnon, phonon and photon, which drastically enhances the magnomechanical interaction. Our work demonstrates the fundamental principle of cavity magnetomechanics, opening up great opportunities in various applications, such as tunable microwave filter and amplifier, long-lifetime quantum memories, microwave-to-optics conversion.

  4. RESONANT CAVITY EXCITATION SYSTEM

    DOEpatents

    Baker, W.R.

    1959-08-01

    A cavity excitation circuit is described for rapidly building up and maintaining high-level oscillations in a resonant cavity. The circuit overcomes oscillation buildup slowing effects such as ion locking in the cavity by providing for the selective application of an amplified accelerating drive signal to the main cavity exciting oscillator during oscillation buildup and a direct drive signal to the oscillator thereafter.

  5. Photon storage cavities

    SciTech Connect

    Kim, K.J.; Sessler, A.M.

    1991-08-01

    A general analysis is presented of a photon storage cavity, coupled to free-electron laser (FEL) cavity. It is shown that if the coupling between the FEL cavity and the storage cavity is unidirectional (for example, a ring resonator storage cavity) then storage is possible, but that if the coupling is bi-directional then storage is not possible. Parameters are presented for an infra-red FEL storage cavity giving an order of magnitude increase in the instantaneous photon power within the storage cavity. 4 refs., 3 figs.

  6. Segmented trapped vortex cavity

    NASA Technical Reports Server (NTRS)

    Grammel, Jr., Leonard Paul (Inventor); Pennekamp, David Lance (Inventor); Winslow, Jr., Ralph Henry (Inventor)

    2010-01-01

    An annular trapped vortex cavity assembly segment comprising includes a cavity forward wall, a cavity aft wall, and a cavity radially outer wall there between defining a cavity segment therein. A cavity opening extends between the forward and aft walls at a radially inner end of the assembly segment. Radially spaced apart pluralities of air injection first and second holes extend through the forward and aft walls respectively. The segment may include first and second expansion joint features at distal first and second ends respectively of the segment. The segment may include a forward subcomponent including the cavity forward wall attached to an aft subcomponent including the cavity aft wall. The forward and aft subcomponents include forward and aft portions of the cavity radially outer wall respectively. A ring of the segments may be circumferentially disposed about an axis to form an annular segmented vortex cavity assembly.

  7. Goos-Hänchen shifts of partially coherent light beams from a cavity with a four-level Raman gain medium

    NASA Astrophysics Data System (ADS)

    Ziauddin; Lee, Ray-Kuang; Qamar, Sajid

    2016-09-01

    We theoretically investigate spatial and angular Goos-Hänchen (GH) shifts (both negative and positive) in the reflected light for a partial coherent light incident on a cavity. A four-level Raman gain atomic medium is considered in a cavity. The effects of spatial coherence, beam width, and mode index of partial coherent light fields on spatial and angular GH shifts are studied. Our results reveal that a large magnitude of negative and positive GH shifts in the reflected light is achievable with the introduction of partial coherent light fields. Furthermore, the amplitude of spatial (negative and positive) GH shifts are sharply affected by the partial coherent light beam as compared to angular (negative and positive) GH shifts in the reflected light.

  8. Experimental study of Rabi-type oscillation induced by tunneling modes in effective near-zero-index metamaterials.

    PubMed

    Zhang, Liwei; Zhang, Yewen; Yang, Yaping; Chen, Hong

    2011-04-01

    A special cavity based on effective near-zero-index paired structures containing ɛ-negative and μ-negative materials is realized by using composite right- or left-handed transmission lines. When an artificial magnetic "atom" is put into the cavity, unusual Rabi-type splitting appears because of the strong coupling between the artificial atom and the localized tunneling mode. The direct time domain energy exchanges between the cavity and the "atom" are experimentally observed after excited by a short pulse signal. Within the "atom" field attenuation time, more than one oscillations appear. Rabi-type splitting and the Rabi-type oscillation period are invariant with the scaling changes of the length but vary with the positions where the "atom" is put with different field intensity. Moreover, the decay time of Rabi-type oscillation becomes longer when the tunneling mode possesses smaller linewidth, which is in good agreement with numerical simulations. PMID:21599323

  9. Vertical-cavity surface-emitting laser device

    DOEpatents

    Hadley, G.R.; Lear, K.L.; Awyoung, A.; Choquette, K.D.

    1999-05-11

    A vertical-cavity surface-emitting laser device is disclosed. The vertical-cavity surface-emitting laser (VCSEL) device comprises one or more VCSELs with each VCSEL having a mode-control region thereabout, with the mode-control region forming an optical cavity with an effective cavity length different from the effective cavity length within each VCSEL. Embodiments of the present invention can be formed as single VCSELs and as one- or two-dimensional arrays of VCSELs, with either an index-guided mode of operation or an index anti-guided mode of operation being defined by a sign of the difference in the two effective cavity lengths. 10 figs.

  10. Stability Study of Coronal Cavities and Prominences

    NASA Astrophysics Data System (ADS)

    de Toma, Giuliana; Gibson, Sarah

    2016-05-01

    Cavity/prominence systems are large-scale coronal structures that can live for many weeks and even months and often end their life in the form of large coronal eruptions. To determine the role of the surrounding ambient coronal field in stabilizing thesesystems against eruption, we examined the extent to which the decline with height of the external coronal magnetic field influences their evolution and likelihood to erupt. We selected coronal cavities observed with SDO/AIA during the rising phase of cycle 24 and divided them in two groups, eruptive and non-eruptive. The height of the cavity, both at the cavity center and top, was directly measured from the SDO/AIA images. The ambient coronal field was derived from a PFSS extrapolation of SDO/HMI magnetograms. We find that the decay index of the potential field above the coronal cavity varies significantly in value for both eruptive and non-eruptive cases but stable cavity systems have, on average, a lower decay index and less complex topology than the eruptive ones.

  11. The Prevalence of Human Immunodeficiency Virus Infection among Pregnant Women in Labour with Unknown Status and those with Negative Status Early in the Index Pregnancy in a Tertiary Hospital in Nigeria.

    PubMed

    Ukaire, Binyerem C; Agboghoroma, Chris O; Durojaiye, Korede W

    2015-09-01

    Rapid HIV test in labour provide an opportunity for the identification of HIV positive pregnant women who should benefit from interventions to reduce the risk of mother-to-child transmission (MTCT) of HIV. Between November 2013 and June 2014 we conducted rapid HIV testing of pregnant women in labour at the National Hospital Abuja to determine the HIV seroconversion rate in pregnancy and the prevalence of HIV in pregnant women in labour with previously unknown status. HIV testing and counseling (HTC) was acceptable to 224 (99.6%) of the pregnant women who met the study criteria. The mean 'turnaround' time for test result was 288 minutes and 16.2 minutes for tests performed in the hospital laboratory and those performed at the point-of-care (labour ward) respectively. HIV seroconversion was detected in 2(1.2%) of the 165 parturients with initial HIV negative result early in the index pregnancy. HIV infection was detected in four (2.7%) of the 59 parturients with unknown HIV status. Secondary school level education was significantly associated with HIV seroconversion in pregnancy P < 0.001. HTC in labour using rapid testing strategy is feasible and acceptable in our setting. The introduction of HCT will lead to the diagnosis of HIV positive women in labour, appropriate interventions and prevention of MTCT of HIV. PMID:26897922

  12. Indexing Images.

    ERIC Educational Resources Information Center

    Rasmussen, Edie M.

    1997-01-01

    Focuses on access to digital image collections by means of manual and automatic indexing. Contains six sections: (1) Studies of Image Systems and their Use; (2) Approaches to Indexing Images; (3) Image Attributes; (4) Concept-Based Indexing; (5) Content-Based Indexing; and (6) Browsing in Image Retrieval. Contains 105 references. (AEF)

  13. Vacuum field energy and spontaneous emission in anomalously dispersive cavities

    SciTech Connect

    Bradshaw, Douglas H.; Di Rosa, Michael D.

    2011-05-15

    Anomalously dispersive cavities, particularly white-light cavities, may have larger bandwidth to finesse ratios than their normally dispersive counterparts. Partly for this reason, they have been proposed for use in laser interferometer gravitational-wave observatory (LIGO)-like gravity-wave detectors and in ring-laser gyroscopes. In this paper we analyze the quantum noise associated with anomalously dispersive cavity modes. The vacuum field energy associated with a particular cavity mode is proportional to the cavity-averaged group velocity of that mode. For anomalously dispersive cavities with group index values between 1 and 0, this means that the total vacuum field energy associated with a particular cavity mode must exceed ({h_bar}/2{pi}){omega}/2. For white-light cavities in particular, the group index approaches zero and the vacuum field energy of a particular spatial mode may be significantly enhanced. We predict enhanced spontaneous emission rates into anomalously dispersive cavity modes and broadened laser linewidths when the linewidth of intracavity emitters is broader than the cavity linewidth.

  14. Cavity turnover and equilibrium cavity densities in a cottonwood bottomland

    USGS Publications Warehouse

    Sedgwick, James A.; Knopf, Fritz L.

    1992-01-01

    A fundamental factor regulating the numbers of secondary cavity nesting (SCN) birds is the number of extant cavities available for nesting. The number of available cavities may be thought of as being in an approximate equilibrium maintained by a very rough balance between recruitment and loss of cavities. Based on estimates of cavity recruitment and loss, we ascertained equilibrium cavity densities in a mature plains cottonwood (Populus sargentii) bottomland along the South Platte River in northeastern Colorado. Annual cavity recruitment, derived from density estimates of primary cavity nesting (PCN) birds and cavity excavation rates, was estimated to be 71-86 new cavities excavated/100 ha. Of 180 active cavities of 11 species of cavity-nesting birds found in 1985 and 1986, 83 were no longer usable by 1990, giving an average instantaneous rate of cavity loss of r = -0.230. From these values of cavity recruitment and cavity loss, equilibrium cavity density along the South Platte is 238-289 cavities/100 ha. This range of equilibrium cavity density is only slightly above the minimum of 205 cavities/100 ha required by SCN's and suggests that cavity availability may be limiting SCN densities along the South Platte River. We submit that snag management alone does not adequately address SCN habitat needs, and that cavity management, expressed in terms of cavity turnover and cavity densities, may be more useful.

  15. Botryomycosis in a lung cavity

    PubMed Central

    Vinay, D; Ramasubramanian, V; Gopalakrishnan, Ram; Jessani, Laxman G

    2016-01-01

    Botryomycosis is a rare pyogranulomatous disease characterized by suppurative and often granulomatous bacterial infection of the skin, soft tissues and viscera. Only about 90 cases have been reported in world literature till date: 75% of them are cases of cutaneous botryomycosis. Of the 18 reported cases of primary pulmonary botryomycosis, only one had histologically proven botryomycosis in a lung cavity. We report here a case of primary pulmonary botryomycosis occurring in a lung cavity, which is to the best of our knowledge first such case from India. The index case was a 62 year old female who presented to us with recurrent episodes of non-massive streaky hemoptysis with CT chest revealing ‘Air Crescent’ sign with a probable fungal ball in a left upper lobe cavity. Left upper pulmonary lobectomy was done and histopathology of the cavitary tissue revealed Splendore-Hoeppli phenomenon and features suggestive of Botryomycosis. Tissue culture from the cavitary specimen grew Pseudomonas aeruginosa. Botryomycosis can mimic Aspergilloma radiologically as was seen in our case, but therapy is often a combination of both medical and surgical measures unlike Aspergilloma. PMID:27625451

  16. Botryomycosis in a lung cavity.

    PubMed

    Vinay, D; Ramasubramanian, V; Gopalakrishnan, Ram; Jessani, Laxman G

    2016-01-01

    Botryomycosis is a rare pyogranulomatous disease characterized by suppurative and often granulomatous bacterial infection of the skin, soft tissues and viscera. Only about 90 cases have been reported in world literature till date: 75% of them are cases of cutaneous botryomycosis. Of the 18 reported cases of primary pulmonary botryomycosis, only one had histologically proven botryomycosis in a lung cavity. We report here a case of primary pulmonary botryomycosis occurring in a lung cavity, which is to the best of our knowledge first such case from India. The index case was a 62 year old female who presented to us with recurrent episodes of non-massive streaky hemoptysis with CT chest revealing 'Air Crescent' sign with a probable fungal ball in a left upper lobe cavity. Left upper pulmonary lobectomy was done and histopathology of the cavitary tissue revealed Splendore-Hoeppli phenomenon and features suggestive of Botryomycosis. Tissue culture from the cavitary specimen grew Pseudomonas aeruginosa. Botryomycosis can mimic Aspergilloma radiologically as was seen in our case, but therapy is often a combination of both medical and surgical measures unlike Aspergilloma. PMID:27625451

  17. Nonlinear all-optical switch based on a white-light cavity

    NASA Astrophysics Data System (ADS)

    Li, Na; Xu, Jingping; Song, Ge; Zhu, Chengjie; Xie, Shuangyuan; Yang, Yaping; Zubairy, M. Suhail; Zhu, Shi-Yao

    2016-04-01

    It is well known that there is a bottleneck for nonlinear all-optical switching, namely, the switching power and the switching time cannot be lowered simultaneously. A lower switching power requires a resonator with a high quality (Q ) factor, but leads to a longer switching time. We propose to overcome this bottleneck by replacing the nonlinear cavity in such an all-optical switch by a white-light cavity. This can be done by doping three-level atoms in the ring resonator and applying incoherent pump and coherent driving fields on it. The white-light cavity possesses broadband resonance in a linear region. Therefore, for the incident pulse, a broad range of frequency components can take part in the nonlinear process, and so it requires lower power to achieve switching compared to the conventional ring resonator. On the other hand, the refractive index of a white-light cavity has negative dispersion, leading to a fast group velocity. This results in a shorter time to build up the resonant response, yielding a short switching time.

  18. Electromagnetic SCRF Cavity Tuner

    SciTech Connect

    Kashikhin, V.; Borissov, E.; Foster, G.W.; Makulski, A.; Pischalnikov, Y.; Khabiboulline, T.; /Fermilab

    2009-05-01

    A novel prototype of SCRF cavity tuner is being designed and tested at Fermilab. This is a superconducting C-type iron dominated magnet having a 10 mm gap, axial symmetry, and a 1 Tesla field. Inside the gap is mounted a superconducting coil capable of moving {+-} 1 mm and producing a longitudinal force up to {+-} 1.5 kN. The static force applied to the RF cavity flanges provides a long-term cavity geometry tuning to a nominal frequency. The same coil powered by fast AC current pulse delivers mechanical perturbation for fast cavity tuning. This fast mechanical perturbation could be used to compensate a dynamic RF cavity detuning caused by cavity Lorentz forces and microphonics. A special configuration of magnet system was designed and tested.

  19. Degenerate astigmatic cavities

    NASA Astrophysics Data System (ADS)

    Courtois, Jérémie; Mohamed, Ajmal; Romanini, Daniele

    2013-10-01

    At the output of a high-finesse cavity a succession of Lissajous patterns may be observed as the cavity length is finely tuned inside a “degenerate region” around a reentrant spherical configuration. This behavior is ascribed to a small parasitic astigmatism of the cavity mirrors. Simple geometrical optics modeling confirms this hypothesis, and then a more realistic analysis using transverse Gaussian modes reveals that the Lissajous patterns correspond to an organization of the astigmatism-split modes into a finer substructure of degenerate modes relative to that of a reentrant spherical cavity. This provides a thorough understanding of the field patterns observed in the degenerate region, including an intriguing spatial symmetry of the patterns corresponding to opposite displacements with respect to a specific central cavity length. This investigation represents a generalization of the theory of reentrant spherical cavities to the astigmatic case.

  20. Negative mass

    NASA Astrophysics Data System (ADS)

    Hammond, Richard T.

    2015-03-01

    Some physical aspects of negative mass are examined. Several unusual properties, such as the ability of negative mass to penetrate any armor, are analysed. Other surprising effects include the bizarre system of negative mass chasing positive mass, naked singularities and the violation of cosmic censorship, wormholes, and quantum mechanical results as well. In addition, a brief look into the implications for strings is given.

  1. Cavity enhanced terahertz modulation

    SciTech Connect

    Born, N.; Scheller, M.; Moloney, J. V.; Koch, M.

    2014-03-10

    We present a versatile concept for all optical terahertz (THz) amplitude modulators based on a Fabry-Pérot semiconductor cavity design. Employing the high reflectivity of two parallel meta-surfaces allows for trapping selected THz photons within the cavity and thus only a weak optical modulation of the semiconductor absorbance is required to significantly damp the field within the cavity. The optical switching yields to modulation depths of more than 90% with insertion efficiencies of 80%.

  2. Characterization of cavity wakes

    NASA Astrophysics Data System (ADS)

    Kidd, James A.

    Scope and Method of Study. This research focused on flow over deep cavities at subsonic speeds with emphasis on the wake downstream of the cavity. Cavity wake behaviors have not been studied in detail and are a major concern for air vehicles with cavities and in particular for optical sensor systems installed in cavities. Other key behaviors for sensor survival and performance are cavity resonance and turbulence scales in the shear layer. A wind tunnel test apparatus was developed to explore cavity and wake characteristics. It consisted of a test section insert for the OSU Indraft Wind Tunnel with an additional contraction cone for significantly increased speed. The test section included a variable depth cavity in a boundary layer splitter plate/fairing assembly, a Y-Z traverse and pitot rake with in-situ pressure transducers for high frequency response. Flows were measured over clean cavities with length to depth (L/D) ratios of 4 to 1/2 and on cavities with a porous fence for resonance suppression. Measurements were taken in streamwise and cross-stream sections to three cavity lengths downstream of the cavity trailing edge. Flow visualization using laser sheet and smoke injection was also used. Findings and Conclusions. The high speed insert demonstrated a significant new capability for the OSU wind tunnel, reaching speeds of 0.35 Mach (390 feet/second) in a 14"x14" test section. Inlet room flow was found to be quite unsteady and recommendations are made for improved flow and quantitative visualization. Key findings for cavity wake flow include its highly three dimensional nature with asymmetric peaks in cross section with boundary layer thicknesses and integral length scales several times that of a normal flat plate turbulent boundary layer (TBL). Turbulent intensities (TI) of 35% to 55% of freestream speeds were measured for the clean configuration. Fence configuration TI's were 20% to 35% of free stream and, in both configurations, TI's decayed to

  3. Optically measuring interior cavities

    DOEpatents

    Stone, Gary Franklin

    2009-11-03

    A method of measuring the three-dimensional volume or perimeter shape of an interior cavity includes the steps of collecting a first optical slice of data that represents a partial volume or perimeter shape of the interior cavity, collecting additional optical slices of data that represents a partial volume or perimeter shape of the interior cavity, and combining the first optical slice of data and the additional optical slices of data to calculate of the three-dimensional volume or perimeter shape of the interior cavity.

  4. Optically measuring interior cavities

    DOEpatents

    Stone, Gary Franklin

    2008-12-21

    A method of measuring the three-dimensional volume or perimeter shape of an interior cavity includes the steps of collecting a first optical slice of data that represents a partial volume or perimeter shape of the interior cavity, collecting additional optical slices of data that represents a partial volume or perimeter shape of the interior cavity, and combining the first optical slice of data and the additional optical slices of data to calculate of the three-dimensional volume or perimeter shape of the interior cavity.

  5. Linear negative dispersion with a gain doublet via optomechanical interactions.

    PubMed

    Qin, Jiayi; Zhao, Chunnong; Ma, Yiqiu; Ju, Li; Blair, David G

    2015-05-15

    Optical cavities containing a negative dispersion medium have been proposed as a means of improving the sensitivity of laser interferometric gravitational wave detectors through the creation of white-light signal recycling cavities. Here we demonstrate that negative dispersion can be realized using an optomechanical cavity pumped by a blue detuned doublet. We used an 85-mm cavity with an intracavity silicon nitride membrane. Tunable negative dispersion is demonstrated, with a phase derivative dφ/df from -0.14  Deg·Hz(-1) to -4.2×10(-3)  Deg·Hz(-1). PMID:26393733

  6. Liquid laser cavities

    NASA Technical Reports Server (NTRS)

    Bjorklund, S.; Filipescu, N.; Kellermeyer, G. L.; Mc Avoy, N.

    1969-01-01

    Liquid laser cavities have plenum chambers at the ends of the capillary cell which are terminated in transparent optical flats. By use of these cavities, several new europium chelates and a terbium chelate can provide laser action in solution at room temperature.

  7. Passivated niobium cavities

    DOEpatents

    Myneni, Ganapati Rao; Hjorvarsson, Bjorgvin; Ciovati, Gianluigi

    2006-12-19

    A niobium cavity exhibiting high quality factors at high gradients is provided by treating a niobium cavity through a process comprising: 1) removing surface oxides by plasma etching or a similar process; 2) removing hydrogen or other gases absorbed in the bulk niobium by high temperature treatment of the cavity under ultra high vacuum to achieve hydrogen outgassing; and 3) assuring the long term chemical stability of the niobium cavity by applying a passivating layer of a superconducting material having a superconducting transition temperature higher than niobium thereby reducing losses from electron (cooper pair) scattering in the near surface region of the interior of the niobium cavity. According to a preferred embodiment, the passivating layer comprises niobium nitride (NbN) applied by reactive sputtering.

  8. CAVITY EXCITATION CIRCUIT

    DOEpatents

    Franck, J.V.

    1959-10-20

    An electronic oscillator is described for energizing a resonant cavity and to a system for stabilizing the operatin g frequency of the oscillator at the particular frequency necessary to establish a particular preferred field configuration or mode in the cavity, in this instance a linear accelerator. A freely rnnning oscillator has an output coupled to a resonant cavity wherein a field may be built up at any one of several adjacent frequencies. A pickup loop in the cavity is suitably shielded and positioned in the cavity so that only energy at the panticular desired frequency is fed back to stabilize the oscillator. A phase and gain control is in cluded in the feedback line.

  9. Cavity coupling of atomic spin and motion

    NASA Astrophysics Data System (ADS)

    Kohler, Jonathan; Gerber, Justin; Spethmann, Nicolas; Schreppler, Sydney; Stamper-Kurn, Dan

    2016-05-01

    Optical cavities have been used to realize sensitive, quantum limited measurements of both the spin and mechanical degrees of freedom of atomic ensembles. We have previously demonstrated cavity assisted measurement and control of a spin-oscillator, where the total atomic spin precesses around an external magnetic field. The spin-oscillator can realize an effective negative mass oscillator, for excitations around its highest energy state. In this talk, I will present our most recent work toward coupling the mechanical and spin degree of freedom of one or more atomic ensembles, with the goal of realizing Coherent Quantum Noise Cancelation for back-action evading measurements.

  10. Hydroforming of elliptical cavities

    DOE PAGESBeta

    Singer, W.; Singer, X.; Jelezov, I.; Kneisel, Peter

    2015-02-27

    Activities of the past several years in developing the technique of forming seamless (weldless) cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with resultsmore » of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients Eacc up to 35 MV/m after buffered chemical polishing (BCP) and up to 42 MV/m after electropolishing (EP). More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients Eacc of 30–35 MV/m were measured after BCP and Eacc up to 40 MV/m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of Eacc = 30–35 MV/m. One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and double-cell cavities of the TESLA shape have

  11. Hydroforming of elliptical cavities

    NASA Astrophysics Data System (ADS)

    Singer, W.; Singer, X.; Jelezov, I.; Kneisel, P.

    2015-02-01

    Activities of the past several years in developing the technique of forming seamless (weldless) cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with results of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients Eacc up to 35 MV /m after buffered chemical polishing (BCP) and up to 42 MV /m after electropolishing (EP). More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients Eacc of 30 - 35 MV /m were measured after BCP and Eacc up to 40 MV /m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of Eacc=30 - 35 MV /m . One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and double-cell cavities of the TESLA shape have been

  12. Tuned optical cavity magnetometer

    DOEpatents

    Okandan, Murat; Schwindt, Peter

    2010-11-02

    An atomic magnetometer is disclosed which utilizes an optical cavity formed from a grating and a mirror, with a vapor cell containing an alkali metal vapor located inside the optical cavity. Lasers are used to magnetically polarize the alkali metal vapor and to probe the vapor and generate a diffracted laser beam which can be used to sense a magnetic field. Electrostatic actuators can be used in the magnetometer for positioning of the mirror, or for modulation thereof. Another optical cavity can also be formed from the mirror and a second grating for sensing, adjusting, or stabilizing the position of the mirror.

  13. Hydroforming of elliptical cavities

    SciTech Connect

    Singer, W.; Singer, X.; Jelezov, I.; Kneisel, Peter

    2015-02-27

    Activities of the past several years in developing the technique of forming seamless (weldless) cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with results of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients Eacc up to 35 MV/m after buffered chemical polishing (BCP) and up to 42 MV/m after electropolishing (EP). More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients Eacc of 30–35 MV/m were measured after BCP and Eacc up to 40 MV/m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of Eacc = 30–35 MV/m. One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and double

  14. Prognostic value of Ki67 and p53 in patients with estrogen receptor-positive and human epidermal growth factor receptor 2-negative breast cancer: Validation of the cut-off value of the Ki67 labeling index as a predictive factor

    PubMed Central

    OHARA, MASAHIRO; MATSUURA, KAZUO; AKIMOTO, ETSUSHI; NOMA, MIDORI; DOI, MIHOKO; NISHIZAKA, TAKASHI; KAGAWA, NAOKI; ITAMOTO, TOSHIYUKI

    2016-01-01

    The aim of this study was to evaluate the significance of the Ki67 labeling index and p53 status as prognostic and predictive indicators of operable estrogen receptor (ER)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Among 697 consecutive patients with primary breast cancer who underwent curative surgery between 2002 and 2013, 308 patients with ER-positive and HER2-negative breast cancer were assessed. The results of the multivariate Cox analysis demonstrated that a high Ki67 labeling index was significantly associated with a short recurrence-free interval (RFI) (p=0.004) and was marginally associated with a worse overall survival (p=0.074). A positive p53 status was not associated with worse outcomes. To validate the cut-off values of the Ki67 labeling index for identifying patients who may benefit from additional chemotherapy, prognostic factors were investigated in breast cancer patients treated postoperatively with endocrine therapy alone. Analysis of receiver operating characteristic curves demonstrated that a Ki67 labeling index cut-off of 20.0% was optimal for predicting recurrence among patients who did not receive adjuvant chemotherapy. The 5-year RFIs for patients with Ki67 <20 and ≥20% were 97.2 and 86.6%, respectively (p=0.0244). A high Ki67 labeling index (≥20%) was significantly associated with large tumors (p<0.01), lymph node metastasis (p=0.0236) and positive p53 status (p<0.001). The univariate analysis demonstrated that Ki67 labeling index ≥20%, lymph node metastasis and progesterone receptor negativity were significant worse prognostic factors for RFI (p=0.0333, 0.0116 and 0.0573, respectively). The Ki67 labeling index was found to be a useful prognostic factor in patients with ER-positive and HER2-negative breast cancer and the cut-off values of the Ki67 labeling index for making a decision regarding adjuvant treatment were validated. PMID:27073684

  15. CIRCULAR CAVITY SLOT ANTENNA

    DOEpatents

    Kerley, P.L.

    1959-01-01

    A small-size antenna having a doughnut-shaped field pattern and which can act both as an antenna and a resonant circuit is described. The antenna is of the slotted type and comprises a resonant cavity with a center hole. A circular slot is provided in one wall of the cavity concentric with the hole and a radio frequency source is connected across the slot. The pattern and loading of the antenna are adjusted by varying the position and shape of a center element slidably disposed within the hole and projecting from the slotted side of the resonant cavity. The disclosed structure may also be used to propagate the oscillator signal down a transniission line by replacing the center element with one leg of the transmission line in a spaced relation from the walls of the cavity.

  16. Observing spin optodynamical analog of cavity optomechanics

    NASA Astrophysics Data System (ADS)

    Gerber, Justin; Kohler, Jonathan; Spethmann, Nicolas; Schreppler, Sydney; Stamper-Kurn, Dan

    2016-05-01

    Cavity Optomechanics has been realized in many diverse systems and led to many interesting results such as ponderomotive squeezing of light, beyond-SQL measurement sensitivity, and squeezing of mechanical oscillators. Optical cavities also allow sensitive measurements of the spin of an atomic ensemble. It has been proposed to utilize this sensitivity to realize an analog of optomechanics by measuring the precession of small excitations of a spin-oscillator around a transverse magnetic field. I will present our recent work in which we realize optomechanical analogs in our system such as cavity-assisted cooling and amplification and optical spring shifts. In addition, the presence of a high-energy `ground state' of the spin oscillator allows the realization of an effective negative mass oscillator which is demonstrated by an inverted sideband asymmetry. In our ongoing work we attempt to realize coherent quantum noise cancelation by coupling spin oscillation with mechanical oscillation.

  17. Passive cavity surface-emitting lasers: option of temperature-insensitive lasing wavelength for uncooled dense wavelength division multiplexing systems

    NASA Astrophysics Data System (ADS)

    Shchukin, V. A.; Ledentsov, N. N.; Slight, T.; Meredith, W.; Gordeev, N. Y.; Nadtochy, A. M.; Payusov, A. S.; Maximov, M. V.; Blokhin, S. A.; Blokhin, A. A.; Zadiranov, Yu. M.; Maleev, N. A.; Ustinov, V. M.; Choquette, K. D.

    2016-03-01

    A concept of passive cavity surface-emitting laser is proposed aimed to control the temperature shift of the lasing wavelength. The device contains an all-semiconductor bottom distributed Bragg reflector (DBR), in which the active medium is placed, a dielectric resonant cavity and a dielectric top DBR, wherein at least one of the dielectric materials has a negative temperature coefficient of the refractive index, dn/dT < 0. This is shown to be the case for commonly used dielectric systems SiO2/TiO2 and SiO2/Ta2O5. Two SiO2/TiO2 resonant structures having a cavity either of SiO2 or TiO2 were deposited on a substrate, their optical power reflectance spectra were measured at various temperatures, and refractive index temperature coefficients were extracted, dn/dT = 0.0021 K-1 for SiO2 and dn/dT = -0.0092 K-1 for TiO2. Using such dielectric materials allows designing passive cavity surface-emitting lasers having on purpose either positive, or zero, or negative temperature shift of the lasing wavelength dλ/dT. A design for temperature-insensitive lasing wavelength (dλ/dT = 0) is proposed. Employing devices with temperature-insensitive lasing wavelength in wavelength division multiplexing systems may allow significant reducing of the spectral separation between transmission channels and an increase in number of channels for a defined spectral interval enabling low cost energy efficient uncooled devices.

  18. Temperature switching of cavity modes in InN microcrystals

    SciTech Connect

    Kazanov, D. R. Kaibyshev, V. H.; Davydov, V. Yu.; Smirnov, A. N.; Jmerik, V. N.; Kuznetsova, N. V.; Kopiev, P. S.; Ivanov, S. V.; Shubina, T. V.

    2015-11-15

    InN optical cavities supporting low-order whispering-gallery modes up to room temperature are formed by molecular-beam epitaxy on patterned substrates. The observed switching of the mode type with increasing temperature is explained in terms of changes in the optical parameters due to a shift of the absorption edge and modification of its shape. Modeling taking into account a variation in the refractive index reproduces the typical distributions of the electromagnetic-field intensity in the cavities.

  19. Millimeter-long fiber Fabry-Perot cavities.

    PubMed

    Ott, Konstantin; Garcia, Sebastien; Kohlhaas, Ralf; Schüppert, Klemens; Rosenbusch, Peter; Long, Romain; Reichel, Jakob

    2016-05-01

    We demonstrate fiber Fabry-Perot (FFP) cavities with concave mirrors that can be operated at cavity lengths as large as 1.5 mm without significant deterioration of the finesse. This is achieved by using a laser dot machining technique to shape spherical mirrors with ultralow roughness and employing single-mode fibers with large mode area for good mode matching to the cavity. Additionally, in contrast to previous FFPs, these cavities can be used over an octave-spanning frequency range with adequate coatings. We also show directly that shape deviations caused by the fiber's index profile lead to a finesse decrease as observed in earlier attempts to build long FFP cavities, and show a way to overcome this problem. PMID:27137597

  20. Ring resonant cavities for spectroscopy

    DOEpatents

    Zare, Richard N.; Martin, Juergen; Paldus, Barbara A.; Xie, Jinchun

    1999-01-01

    Ring-shaped resonant cavities for spectroscopy allow a reduction in optical feedback to the light source, and provide information on the interaction of both s- and p-polarized light with samples. A laser light source is locked to a single cavity mode. An intracavity acousto-optic modulator may be used to couple light into the cavity. The cavity geometry is particularly useful for Cavity Ring-Down Spectroscopy (CRDS).

  1. Ring resonant cavities for spectroscopy

    DOEpatents

    Zare, R.N.; Martin, J.; Paldus, B.A.; Xie, J.

    1999-06-15

    Ring-shaped resonant cavities for spectroscopy allow a reduction in optical feedback to the light source, and provide information on the interaction of both s- and p-polarized light with samples. A laser light source is locked to a single cavity mode. An intracavity acousto-optic modulator may be used to couple light into the cavity. The cavity geometry is particularly useful for Cavity Ring-Down Spectroscopy (CRDS). 6 figs.

  2. Chemical Sensing Using Fiber Cavity Ring-Down Spectroscopy

    PubMed Central

    Waechter, Helen; Litman, Jessica; Cheung, Adrienne H.; Barnes, Jack A.; Loock, Hans-Peter

    2010-01-01

    Waveguide-based cavity ring-down spectroscopy (CRD) can be used for quantitative measurements of chemical concentrations in small amounts of liquid, in gases or in films. The change in ring-down time can be correlated to analyte concentration when using fiber optic sensing elements that change their attenuation in dependence of either sample absorption or refractive index. Two types of fiber cavities, i.e., fiber loops and fiber strands containing reflective elements, are distinguished. Both types of cavities were coupled to a variety of chemical sensor elements, which are discussed and compared. PMID:22294895

  3. Evolution of Rising Magnetic Cavities and UHECR Acceleration

    NASA Astrophysics Data System (ADS)

    Gourgouliatos, Konstantinos

    2011-08-01

    GN jets produce low density cavities in clusters of galaxies. Stability requires the presence of magnetic fields. We find self-consistent analytical structure of cavities containing large-scale electromagnetic fields and plasma expanding self-similarly. These solutions have no surface currents and, thus, are less susceptible to resistive decay, while they can be confined by a uniform pressure without deformation. If the adiabatic index of the plasma within the cavity is Γ>4/3, the expansion leads to the sudden formation of large-scale current sheets. We demonstrate that the ensuing explosive reconnection of the magnetic field can accelerate UHECRs.

  4. Video Toroid Cavity Imager

    SciTech Connect

    Gerald, Rex E. II; Sanchez, Jairo; Rathke, Jerome W.

    2004-08-10

    A video toroid cavity imager for in situ measurement of electrochemical properties of an electrolytic material sample includes a cylindrical toroid cavity resonator containing the sample and employs NMR and video imaging for providing high-resolution spectral and visual information of molecular characteristics of the sample on a real-time basis. A large magnetic field is applied to the sample under controlled temperature and pressure conditions to simultaneously provide NMR spectroscopy and video imaging capabilities for investigating electrochemical transformations of materials or the evolution of long-range molecular aggregation during cooling of hydrocarbon melts. The video toroid cavity imager includes a miniature commercial video camera with an adjustable lens, a modified compression coin cell imager with a fiat circular principal detector element, and a sample mounted on a transparent circular glass disk, and provides NMR information as well as a video image of a sample, such as a polymer film, with micrometer resolution.

  5. Metasurface external cavity laser

    SciTech Connect

    Xu, Luyao Curwen, Christopher A.; Williams, Benjamin S.; Hon, Philip W. C.; Itoh, Tatsuo; Chen, Qi-Sheng

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  6. Metasurface external cavity laser

    NASA Astrophysics Data System (ADS)

    Xu, Luyao; Curwen, Christopher A.; Hon, Philip W. C.; Chen, Qi-Sheng; Itoh, Tatsuo; Williams, Benjamin S.

    2015-11-01

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  7. Multicolor cavity soliton.

    PubMed

    Luo, Rui; Liang, Hanxiao; Lin, Qiang

    2016-07-25

    We show a new class of complex solitary wave that exists in a nonlinear optical cavity with appropriate dispersion characteristics. The cavity soliton consists of multiple soliton-like spectro-temporal components that exhibit distinctive colors but coincide in time and share a common phase, formed together via strong inter-soliton four-wave mixing and Cherenkov radiation. The multicolor cavity soliton shows intriguing spectral locking characteristics and remarkable capability of spectrum management to tailor soliton frequencies, which would be very useful for versatile generation and manipulation of multi-octave spanning phase-locked Kerr frequency combs, with great potential for applications in frequency metrology, optical frequency synthesis, and spectroscopy. PMID:27464131

  8. The auroral plasma cavity

    NASA Technical Reports Server (NTRS)

    Calvert, W.

    1981-01-01

    A region of diminished plasma density has been found to occur at the source of auroral kilometric radiation (AKR). The density within this auroral plasma cavity, determined from limited Hawkeye wave data, was less than 1/cu cm from 1.8 to 3 earth radii geocentric, at 70 deg + or - 3 deg invariant magnetic latitude. The altitude variation of the magnetic field produces a minimum in the ratio of plasma frequency to cyclotron frequency within the cavity which accounts for the observed spectrum of AKR.

  9. INDEXING MECHANISM

    DOEpatents

    Kock, L.J.

    1959-09-22

    A device is presented for loading and unloading fuel elements containing material fissionable by neutrons of thermal energy. The device comprises a combination of mechanical features Including a base, a lever pivotally attached to the base, an Indexing plate on the base parallel to the plane of lever rotation and having a plurality of apertures, the apertures being disposed In rows, each aperture having a keyway, an Index pin movably disposed to the plane of lever rotation and having a plurality of apertures, the apertures being disposed in rows, each aperture having a keyway, an index pin movably disposed on the lever normal to the plane rotation, a key on the pin, a sleeve on the lever spaced from and parallel to the index pin, a pair of pulleys and a cable disposed between them, an open collar rotatably attached to the sleeve and linked to one of the pulleys, a pin extending from the collar, and a bearing movably mounted in the sleeve and having at least two longitudinal grooves in the outside surface.

  10. Melatonin and Oral Cavity

    PubMed Central

    Cengiz, Murat İnanç; Cengiz, Seda; Wang, Hom-Lay

    2012-01-01

    While initially the oral cavity was considered to be mainly a source of various bacteria, their toxins and antigens, recent studies showed that it may also be a location of oxidative stress and periodontal inflammation. Accordingly, this paper focuses on the involvement of melatonin in oxidative stress diseases of oral cavity as well as on potential therapeutic implications of melatonin in dental disorders. Melatonin has immunomodulatory and antioxidant activities, stimulates the proliferation of collagen and osseous tissue, and acts as a protector against cellular degeneration associated with aging and toxin exposure. Arising out of its antioxidant actions, melatonin protects against inflammatory processes and cellular damage caused by the toxic derivates of oxygen. As a result of these actions, melatonin may be useful as a coadjuvant in the treatment of certain conditions of the oral cavity. However, the most important effect of melatonin seems to result from its potent antioxidant, immunomodulatory, protective, and anticancer properties. Thus, melatonin could be used therapeutically for instance, locally, in the oral cavity damage of mechanical, bacterial, fungal, or viral origin, in postsurgical wounds caused by tooth extractions and other oral surgeries. Additionally, it can help bone formation in various autoimmunological disorders such as Sjorgen syndrome, in periodontal diseases, in toxic effects of dental materials, in dental implants, and in oral cancers. PMID:22792106

  11. Optical modeling of certical-cavity surface-emitting lasers

    SciTech Connect

    Hadley, G.R.

    1996-12-31

    Vertical-cavity surface-emitting lasers (VCSELs) are presently the subject of intense research due to their potential as compact, efficient, astigmatic laser sources for a number of important applications. Of special interest are the selectively-oxidized VCSELs that have recently set records for threshold current and wall-plug efficiency. The onset of higher-order modes at powers of a few milliWatts, however, presently limits the wide utilization of these devices and indicates the need for improvements in design. Unfortunately, their complexity precludes optimization based solely upon empirical methods, and points instead to the need for better numerical models. Modeling the optical field in a vertical-cavity laser, however, is especially difficult due to both the high Q of the optical cavity and the distributed reflectivity of the mirrors. Our approach to this dilemma has been the development of modeling techniques on two complexity scales. We first derived an effective- index model that is numerically efficient and thus can be included together with carrier transport and thermal models to make up a self-consistent modeling package. In addition to its use in the overall VCSEL model, this simplified optical model has been extremely valuable in elucidating the basic principles of waveguiding in VCSELs that in turn have led to new ideas in device design. More specifically, the derived expression for the effective index shows clearly that index guiding in a VCSEL depends only on variations in optical cavity length, and thus can be engineered without the need to alter the material index of refraction. Also, we have designed index- guided and antiguided devices whose cavity lengths are modified in certain regions by etching of the cavity material prior to growth of the second mirror. Fabrication of these new device designs is presently in progress.

  12. Broadband cavity electromagnetically induced transparency

    SciTech Connect

    Wei Xiaogang; Wang Yanhua; Zhang Jiepeng; Zhu Yifu

    2011-10-15

    Cavity electromagnetically induced transparency (EIT) is created in a three-level atomic system confined in a cavity and coupled to a free-space control laser and is manifested as a narrow transmission peak of a probe laser coupled into the cavity mode and tuned to the two-photon Raman resonance with the control laser. Cavity EIT can be observed with a control laser detuned from the atomic transition frequency in a range limited by the vacuum Rabi splitting of two cavity-atom normal modes. This leads to the broadband cavity EIT obtained in the coupled-cavity-atom system with a free-space, broadband control laser. We report an experimental observation of broadband cavity EIT in cold Rb atoms with a frequency-modulated control laser and discuss its application in multichannel and multifrequency light memory.

  13. Seamless/bonded niobium cavities

    NASA Astrophysics Data System (ADS)

    Singer, W.

    2006-07-01

    Technological aspects and performance of seamless cavities produced by hydroforming are presented. Problems related to the fabrication of seamless cavities from bulk niobium are mainly solved thanks to the progress of the last years. The highest achieved accelerating gradients are comparable for both seamless and welded versions (ca. 40 MV/m) Nevertheless further development of seamless cavities is desirable in order to avoid the careful preparation of parts for welding and get reliable statistic. Fabrication of NbCu clad cavities from bimetallic tubes is an interesting option that gives new opportunity to the seamless technique. On the one hand it allows reducing the niobium costs contribution; on the other hand it increases the thermal stability of the cavity. The highest accelerating gradient achieved on seamless NbCu clad single cell cavities (ca. 40 MV/m) is comparable to the one reached on bulk Nb cavities. Fabrication of multi-cell NbCu cavities by hydroforming was recently proven.

  14. Effective Cavity Length of Gyrotrons

    NASA Astrophysics Data System (ADS)

    Thumm, Manfred

    2014-12-01

    Megawatt-class gyrotron oscillators for electron cyclotron heating and non-inductive current drive (ECH&CD) in magnetically confined thermonuclear fusion plasmas have relatively low cavity quality factors in the range of 1000 to 2000. The effective length of their cavities cannot be simply deduced from the cavity electric field profile, since this has by far not a Gaussian shape. The present paper presents a novel method to estimate the effective length of a gyrotron cavity just from the eigenvalue of the operating TEm,n mode, the cavity radius and the exact oscillation frequency which may be numerically computed or precisely measured. This effective cavity length then can be taken to calculate the Fresnel parameter in order to confirm that the cavity is not too short so that the transverse structure of any mode in the cavity is the same as that of the corresponding mode in a long circular waveguide with the same diameter.

  15. Negative refraction and superconductivity

    NASA Astrophysics Data System (ADS)

    Amariti, Antonio; Forcella, Davide; Mariotti, Alberto; Siani, Massimo

    2011-10-01

    We discuss exotic properties of charged hydrodynamical systems, in the broken superconducting phase, probed by electromagnetic waves. Motivated by general arguments from hydrodynamics, we observe that negative refraction, namely the propagation in opposite directions of the phase velocities and of the energy flux, is expected for low enough frequencies. We corroborate this general idea by analyzing a holographic superconductor in the AdS/CFT correspondence, where the response functions can be explicitly computed. We study the dual gravitational theory both in the probe and in the backreacted case. We find that, while in the first case the refractive index is positive at every frequency, in the second case there is negative refraction at low enough frequencies. This is in agreement with hydrodynamic considerations.

  16. Hollow waveguide cavity ringdown spectroscopy

    NASA Technical Reports Server (NTRS)

    Dreyer, Chris (Inventor); Mungas, Greg S. (Inventor)

    2012-01-01

    Laser light is confined in a hollow waveguide between two highly reflective mirrors. This waveguide cavity is used to conduct Cavity Ringdown Absorption Spectroscopy of loss mechanisms in the cavity including absorption or scattering by gases, liquid, solids, and/or optical elements.

  17. Nitrogen Index

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a need to improve the management of nitrogen inputs to agricultural systems because they increase the potential for losses of reactive nitrogen to the environment, resulting in negative impacts to water and air resources. There is a need to reduce nitrate leaching, emissions of N2O from agr...

  18. Digital Cavity Resonance Monitor, alternative method of measuring cavity microphonics

    SciTech Connect

    Tomasz Plawski; G. Davis; Hai Dong; J. Hovater; John Musson; Thomas Powers

    2005-09-20

    As is well known, mechanical vibration or microphonics in a cryomodule causes the cavity resonance frequency to change at the vibration frequency. One way to measure the cavity microphonics is to drive the cavity with a Phase Locked Loop. Measurement of the instantaneous frequency or PLL error signal provides information about the cavity microphonic frequencies. Although the PLL error signal is available directly, precision frequency measurements require additional instrumentation, a Cavity Resonance Monitor (CRM). The analog version of such a device has been successfully used for several cavity tests [1]. In this paper we present a prototype of a Digital Cavity Resonance Monitor designed and built in the last year. The hardware of this instrument consists of an RF downconverter, digital quadrature demodulator and digital processor motherboard (Altera FPGA). The motherboard processes received data and computes frequency changes with a resolution of 0.2 Hz, with a 3 kHz output bandwidth.

  19. Cesium injection system for negative ion duoplasmatrons

    DOEpatents

    Kobayashi, Maasaki; Prelec, Krsto; Sluyters, Theodorus J

    1978-01-01

    Longitudinally extending, foraminous cartridge means having a cylindrical side wall forming one flat, circular, tip end surface and an opposite end; an open-ended cavity, and uniformly spaced orifices for venting the cavity through the side wall in the annulus of a plasma ring for uniformly ejecting cesium for coating the flat, circular, surface. To this end, the cavity is filled with a cesium containing substance and attached to a heater in a hollow-discharge duoplasmatron. By coating the flat circular surface with a uniform monolayer of cesium and locating it in an electrical potential well at the end of a hollow-discharge, ion duoplasmatron source of an annular hydrogen plasma ring, the negative hydrogen production from the duoplasmatron is increased. The negative hydrogen is produced on the flat surface of the cartridge and extracted by the electrical potential well along a trajectory coaxial with the axis of the plasma ring.

  20. CAVITY CONTROL ALGORITHM

    SciTech Connect

    Tomasz Plawski, J. Hovater

    2010-09-01

    A digital low level radio frequency (RF) system typically incorporates either a heterodyne or direct sampling technique, followed by fast ADCs, then an FPGA, and finally a transmitting DAC. This universal platform opens up the possibilities for a variety of control algorithm implementations. The foremost concern for an RF control system is cavity field stability, and to meet the required quality of regulation, the chosen control system needs to have sufficient feedback gain. In this paper we will investigate the effectiveness of the regulation for three basic control system algorithms: I&Q (In-phase and Quadrature), Amplitude & Phase and digital SEL (Self Exciting Loop) along with the example of the Jefferson Lab 12 GeV cavity field control system.

  1. Cavity enhanced atomic magnetometry

    PubMed Central

    Crepaz, Herbert; Ley, Li Yuan; Dumke, Rainer

    2015-01-01

    Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations. PMID:26481853

  2. Cavity enhanced atomic magnetometry.

    PubMed

    Crepaz, Herbert; Ley, Li Yuan; Dumke, Rainer

    2015-01-01

    Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations. PMID:26481853

  3. Cavity enhanced atomic magnetometry

    NASA Astrophysics Data System (ADS)

    Crepaz, Herbert; Ley, Li Yuan; Dumke, Rainer

    2015-10-01

    Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations.

  4. What Are Oral Cavity and Oropharyngeal Cancers?

    MedlinePlus

    ... about oral cavity and oropharyngeal cancers? What are oral cavity and oropharyngeal cancers? Cancer starts when cells in ... the parts of the mouth and throat. The oral cavity (mouth) and oropharynx (throat) The oral cavity includes ...

  5. Gyromultiplier with sectioned cavity

    SciTech Connect

    Bandurkin, I. V.; Mishakin, S. V.

    2010-11-15

    A novel scheme of a self-exciting single-cavity terahertz gyromultiplier is proposed and theoretically investigated. Simulations predict a possibility to obtain a power of 75 W at the frequency of 1.3 THz from the 80 kV/0.7 A electron beam when operating at the fourth cyclotron harmonic at the relatively low magnetic field of 14 T.

  6. Single mode cavity laser

    SciTech Connect

    Martin, D.W.; Levy, J.L.

    1984-01-17

    This external cavity laser utilizes an unstable resonator in conjuction with a high reflectivity stripe end mirror which is oriented substantially parallel to the plane of the maximum divergence of the laser diode output beam and whose axis is substantially parallel to the plane of the junction of the laser diode. This configuration operates with high efficiency to select only the fundamental mode of the laser diode with a minimal divergence in the output beam.

  7. Controlling interactions between coupled photonic crystal cavities using photochromic tuning

    NASA Astrophysics Data System (ADS)

    Cai, Tao; Bose, Ranojoy; Solomon, Glenn; Waks, Edo

    2013-03-01

    Strongly coupled photonic crystal (PhC) resonator systems provide a promising platform for studying cavity quantum electrodynamics (QED) using semiconductor quantum dots (QDs). These device structures enable important applications such as photon blockade, quantum simulation, quantum-optical Josephson interferometer, and quantum phase transition of light. Many of these applications require the ability to accurately tune the resonant frequencies of individual cavities in the array, which provides a method to control their coupling interactions. This tuning method must be sufficiently local to address individual cavities spaced by less than 1 micron spatial separation. Here, we present a method for controlling the coupling interaction of photonic crystal cavity arrays by using a local and reversible photochromic tuning technique. By locally altering the refractive index of the photochromic material all-optically, the coupling interaction between two cavity modes could be modified over a tuning range as large as 700 GHz. By using this technique, we demonstrate the ability to couple photonic crystal cavities with a normal mode splitting of only 31.50 GHz. We further demonstrate that this tuning method can be extended to control the coupling interaction in larger cavity arrays.

  8. Elevated Patient Body Mass Index Does Not Negatively Affect Self-Reported Outcomes of Thoracolumbar Surgery: Results of a Comparative Observational Study with Minimum 1-Year Follow-Up.

    PubMed

    Manson, Neil A; Green, Alana J; Abraham, Edward P

    2016-03-01

    Study Design Retrospective study. Objective Quantify the effect of obesity on elective thoracolumbar spine surgery patients. Methods Five hundred consecutive adult patients undergoing thoracolumbar spine surgery to treat degenerative pathologies with minimum follow-up of at least 1 year were included. Primary outcome measures included Numerical Rating Scales for back and leg pain, the Short Form 36 Physical Component Summary and Mental Component Summary, the modified Oswestry Disability Index, and patient satisfaction scores collected preoperatively and at 3, 6, 12, and 24 months postoperatively. Secondary outcome measures included perioperative and postoperative adverse events, postoperative emergency department presentation, hospital readmission, and revision surgeries. Patients were grouped according to World Health Organization body mass index (BMI) guidelines to isolate the effect of obesity on primary and secondary outcome measures. Results Mean BMI was 30 kg/m(2), reflecting a significantly overweight population. Each BMI group reported statistically significant improvement on all self-reported outcome measures. Contrary to our hypothesis, however, there was no association between BMI group and primary outcome measures. Patients with BMI of 35 to 39.99 visited the emergency department with complaints of pain significantly more often than the other groups. Otherwise, we did not detect any differences in the secondary outcome measures between BMI groups. Conclusions Patients of all levels of obesity experienced significant improvement following elective thoracolumbar spine surgery. These outcomes were achieved without increased risk of postoperative complications such as infection and reoperation. A risk-benefit algorithm to assist with surgical decision making for obese patients would be valuable to surgeons and patients alike. PMID:26933611

  9. Elevated Patient Body Mass Index Does Not Negatively Affect Self-Reported Outcomes of Thoracolumbar Surgery: Results of a Comparative Observational Study with Minimum 1-Year Follow-Up

    PubMed Central

    Manson, Neil A.; Green, Alana J.; Abraham, Edward P.

    2015-01-01

    Study Design Retrospective study. Objective Quantify the effect of obesity on elective thoracolumbar spine surgery patients. Methods Five hundred consecutive adult patients undergoing thoracolumbar spine surgery to treat degenerative pathologies with minimum follow-up of at least 1 year were included. Primary outcome measures included Numerical Rating Scales for back and leg pain, the Short Form 36 Physical Component Summary and Mental Component Summary, the modified Oswestry Disability Index, and patient satisfaction scores collected preoperatively and at 3, 6, 12, and 24 months postoperatively. Secondary outcome measures included perioperative and postoperative adverse events, postoperative emergency department presentation, hospital readmission, and revision surgeries. Patients were grouped according to World Health Organization body mass index (BMI) guidelines to isolate the effect of obesity on primary and secondary outcome measures. Results Mean BMI was 30 kg/m2, reflecting a significantly overweight population. Each BMI group reported statistically significant improvement on all self-reported outcome measures. Contrary to our hypothesis, however, there was no association between BMI group and primary outcome measures. Patients with BMI of 35 to 39.99 visited the emergency department with complaints of pain significantly more often than the other groups. Otherwise, we did not detect any differences in the secondary outcome measures between BMI groups. Conclusions Patients of all levels of obesity experienced significant improvement following elective thoracolumbar spine surgery. These outcomes were achieved without increased risk of postoperative complications such as infection and reoperation. A risk–benefit algorithm to assist with surgical decision making for obese patients would be valuable to surgeons and patients alike. PMID:26933611

  10. Graded-index magnonics

    NASA Astrophysics Data System (ADS)

    Davies, C. S.; Kruglyak, V. V.

    2015-10-01

    The wave solutions of the Landau-Lifshitz equation (spin waves) are characterized by some of the most complex and peculiar dispersion relations among all waves. For example, the spin-wave ("magnonic") dispersion can range from the parabolic law (typical for a quantum-mechanical electron) at short wavelengths to the nonanalytical linear type (typical for light and acoustic phonons) at long wavelengths. Moreover, the long-wavelength magnonic dispersion has a gap and is inherently anisotropic, being naturally negative for a range of relative orientations between the effective field and the spin-wave wave vector. Nonuniformities in the effective field and magnetization configurations enable the guiding and steering of spin waves in a deliberate manner and therefore represent landscapes of graded refractive index (graded magnonic index). By analogy to the fields of graded-index photonics and transformation optics, the studies of spin waves in graded magnonic landscapes can be united under the umbrella of the graded-index magnonics theme and are reviewed here with focus on the challenges and opportunities ahead of this exciting research direction.

  11. RF Cavity Characterization with VORPAL

    SciTech Connect

    C. Nieter, C. Roark, P. Stoltz, C.D. Zhou, F. Marhauser

    2011-03-01

    When designing a radio frequency (RF) accelerating cavity structure various figures of merit are considered before coming to a final cavity design. These figures of merit include specific field and geometry based quantities such as the ratio of the shunt impedance to the quality factor (R/Q) or the normalized peak fields in the cavity. Other important measures of cavity performance include the peak surface fields as well as possible multipacting resonances in the cavity. High fidelity simulations of these structures can provide a good estimate of these important quantities before any cavity prototypes are built. We will present VORPAL simulations of a simple pillbox structure where these quantities can be calculated analytically and compare them to the results from the VORPAL simulations. We will then use VORPAL to calculate these figures of merit and potential multipacting resonances for two cavity designs under development at Jefferson National Lab for Project X.

  12. Crab Cavities for Linear Colliders

    SciTech Connect

    Burt, G.; Ambattu, P.; Carter, R.; Dexter, A.; Tahir, I.; Beard, C.; Dykes, M.; Goudket, P.; Kalinin, A.; Ma, L.; McIntosh, P.; Shulte, D.; Jones, Roger M.; Bellantoni, L.; Chase, B.; Church, M.; Khabouline, T.; Latina, A.; Adolphsen, C.; Li, Z.; Seryi, Andrei; /SLAC

    2011-11-08

    Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both the ILC and CLIC linear colliders for bunch alignment. Consideration of bunch structure and size constraints favour a 3.9 GHz superconducting, multi-cell cavity as the solution for ILC, whilst bunch structure and beam-loading considerations suggest an X-band copper travelling wave structure for CLIC. These two cavity solutions are very different in design but share complex design issues. Phase stabilisation, beam loading, wakefields and mode damping are fundamental issues for these crab cavities. Requirements and potential design solutions will be discussed for both colliders.

  13. Superconducting cavities and modulated RF

    SciTech Connect

    Farkas, Z.D.

    1981-02-01

    If a cavity has an infinite Q/sub o/, 81.5% of the energy contained in a pulse incident upon the cavity is transferred into the cavity by the end of the pulse if the cavity Q/sub e/ is chosen so that the cavity time constant is 0.796 pulse width (T/sub a/). As Q/sug o/ decreases, the energy in the cavity at the end of the pulse decreases very slowly as long as T/sub a/ is much less than the unloaded cavity time constant, T/sub co/. SC cavities with very high Q/sub o/ enable one to obtain very high gradients with a low power cw source. At high gradients, however, one often does not attain the high Q/sub o/ predicted by theory. Therefore, if one is inteerested in attaining maximum energy in the cavity, as is the case for RF processing and diagnostics, for a given available source energy there is no point in keeping the power on for longer than 0.1 T/sub co/ because the energy expended after 0.1 T/sub co/ is wasted. Therefore, to attain high fields at moderate Q/sub o/, pulsed operation is indicated. This note derives the fields and energy stored and dissipated in the cavity when Q/sub e/ is optimized for a given T/sub a/. It shows how to use this data to measure Q/sub o/ of an SC cavity as a function of field level, how to process the cavity with high RF fields, how to operate SC cavities in the pulsed mode to obtain higher efficiencies and gradients. Experimental results are also reported.

  14. Effects of cavity-entrance restrictors on red-cockaded woodpeckers

    USGS Publications Warehouse

    Raulston, B.E.; James, D.A.; Johnson, J.E.

    1996-01-01

    The U.S. Forest Service has installed restrictors on cavity entrances of red-cockaded woodpeckers to limit access by larger cavity-dwelling competitors. This study tested the hypothesis that restrictors have no adverse effects on red-cockaded woodpeckers. Entrance restrictors were placed on openings to 20 cavities used by roosting red-cockaded woodpeckers, and 20 were left nonrestricted in the Bienville National Forest, Mississippi. No difference was found between treatments in subsequent cavity use by red-cockaded woodpeckers. We examined possible effects on bill wear of birds using cavities with the metal restrictors. We recorded evidence of damage to bills and measured bill lengths of 14 birds captured from cavities with restrictor plates compared to 20 birds from cavities without restrictors. No significant difference was found. These data indicate restrictors do not negatively affect red-cockaded woodpeckers.

  15. High-sensitivity and high-Q-factor glass photonic crystal cavity and its applications as sensors.

    PubMed

    Siraji, Ashfaqul Anwar; Zhao, Yang

    2015-04-01

    We investigate the properties of a planar photonic crystal cavity on glass and its applications as sensors. An airbridged twofold defect cavity on Schott glass background and Gorilla glass substrate has been designed for high Q-factor up to 4459. The average sensitivity of the cavity resonance to background refractive index is 388 nm/Refractive Index Unit. The resonant wavelength is sensitive to background temperature by 18.5 pm/°C. The designed sensors show much higher sensitivity than those based on waveguide interferometers or photonic bandgap structures without cavity resonance. The results are also useful for experimental studies of glass photonic devices. PMID:25831371

  16. Plasmonic external cavity laser refractometric sensor

    PubMed Central

    Zhang, Meng; Lu, Meng; Ge, Chun; Cunningham, Brian T.

    2014-01-01

    Combining the high sensitivity properties of surface plasmon resonance refractive index sensing with a tunable external cavity laser, we demonstrate a plasmonic external cavity laser (ECL) for high resolution refractometric sensing. The plasmonic ECL utilizes a plasmonic crystal with extraordinary optical transmission (EOT) as the wavelength-selective element, and achieves single mode lasing at the transmission peak of the EOT resonance. The plasmonic ECL refractometric sensor maintains the high sensitivity of a plasmonic crystal sensor, while simultaneously providing a narrow spectral linewidth through lasing emission, resulting in a record high figure of merit for refractometric sensing with an active or passive optical resonator. We demonstrate single-mode and continuous-wave operation of the electrically-pumped laser system, and show the ability to measure refractive index changes with a 3σ detection limit of 1.79 × 10−6 RIU. The demonstrated approach is a promising path towards label-free optical biosensing with enhanced signal-to-noise ratios for challenging applications in small molecule drug discovery and pathogen sensing. PMID:25321243

  17. Applications of cavity optomechanics

    SciTech Connect

    Metcalfe, Michael

    2014-09-15

    Cavity-optomechanics” aims to study the quantum properties of mechanical systems. A common strategy implemented in order to achieve this goal couples a high finesse photonic cavity to a high quality factor mechanical resonator. Then, using feedback forces such as radiation pressure, one can cool the mechanical mode of interest into the quantum ground state and create non-classical states of mechanical motion. On the path towards achieving these goals, many near-term applications of this field have emerged. After briefly introducing optomechanical systems and describing the current state-of-the-art experimental results, this article summarizes some of the more exciting practical applications such as ultra-sensitive, high bandwidth accelerometers and force sensors, low phase noise x-band integrated microwave oscillators and optical signal processing such as optical delay-lines, wavelength converters, and tunable optical filters. In this rapidly evolving field, new applications are emerging at a fast pace, but this article concentrates on the aforementioned lab-based applications as these are the most promising avenues for near-term real-world applications. New basic science applications are also becoming apparent such as the generation of squeezed light, testing gravitational theories and for providing a link between disparate quantum systems.

  18. Multicolor cavity metrology.

    PubMed

    Izumi, Kiwamu; Arai, Koji; Barr, Bryan; Betzwieser, Joseph; Brooks, Aidan; Dahl, Katrin; Doravari, Suresh; Driggers, Jennifer C; Korth, W Zach; Miao, Haixing; Rollins, Jameson; Vass, Stephen; Yeaton-Massey, David; Adhikari, Rana X

    2012-10-01

    Long-baseline laser interferometers used for gravitational-wave detection have proven to be very complicated to control. In order to have sufficient sensitivity to astrophysical gravitational waves, a set of multiple coupled optical cavities comprising the interferometer must be brought into resonance with the laser field. A set of multi-input, multi-output servos then lock these cavities into place via feedback control. This procedure, known as lock acquisition, has proven to be a vexing problem and has reduced greatly the reliability and duty factor of the past generation of laser interferometers. In this article, we describe a technique for bringing the interferometer from an uncontrolled state into resonance by using harmonically related external fields to provide a deterministic hierarchical control. This technique reduces the effect of the external seismic disturbances by 4 orders of magnitude and promises to greatly enhance the stability and reliability of the current generation of gravitational-wave detectors. The possibility for using multicolor techniques to overcome current quantum and thermal noise limits is also discussed. PMID:23201656

  19. Observation of Cavity Rydberg Polaritons

    NASA Astrophysics Data System (ADS)

    Georgakopoulos, Alexandros; Jia, Ningyuan; Ryou, Albert; Schine, Nathan; Sommer, Ariel; Simon, Jonathan

    2016-05-01

    We demonstrate hybridization of optical cavity photons with atomic Rydberg excitations using electromagnetically induced transparency (EIT). The resulting dark state Rydberg polaritons exhibit a compressed frequency spectrum and enhanced lifetime indicating strong light-matter mixing. We study the coherence properties of cavity Rydberg polaritons and identify the generalized EIT linewidth for optical cavities. Strong collective coupling suppresses polariton losses due to inhomogeneous broadening, which we demonstrate by using different Rydberg levels with a range of polarizabilities. Our results point the way towards using cavity Rydberg polaritons as a platform for creating photonic quantum materials.

  20. Cavity coalescence in superplastic deformation

    SciTech Connect

    Stowell, M.J.; Livesey, D.W.; Ridley, N.

    1984-01-01

    An analysis of the probability distribution function of particles randomly dispersed in a solid has been applied to cavitation during superplastic deformation and a method of predicting cavity coalescence developed. Cavity size distribution data were obtained from two microduplex nickel-silver alloys deformed superplastically to various extents at elevated temperature, and compared to theoretical predictions. Excellent agreement occurred for small void sizes but the model underestimated the number of voids in the largest size groups. It is argued that the discrepancy results from a combination of effects due to non-random cavity distributions and to enhanced growth rates and incomplete spheroidization of the largest cavities.

  1. Nanofriction in Cavity Quantum Electrodynamics.

    PubMed

    Fogarty, T; Cormick, C; Landa, H; Stojanović, Vladimir M; Demler, E; Morigi, Giovanna

    2015-12-01

    The dynamics of cold trapped ions in a high-finesse resonator results from the interplay between the long-range Coulomb repulsion and the cavity-induced interactions. The latter are due to multiple scatterings of laser photons inside the cavity and become relevant when the laser pump is sufficiently strong to overcome photon decay. We study the stationary states of ions coupled with a mode of a standing-wave cavity as a function of the cavity and laser parameters, when the typical length scales of the two self-organizing processes, Coulomb crystallization and photon-mediated interactions, are incommensurate. The dynamics are frustrated and in specific limiting cases can be cast in terms of the Frenkel-Kontorova model, which reproduces features of friction in one dimension. We numerically recover the sliding and pinned phases. For strong cavity nonlinearities, they are in general separated by bistable regions where superlubric and stick-slip dynamics coexist. The cavity, moreover, acts as a thermal reservoir and can cool the chain vibrations to temperatures controlled by the cavity parameters and by the ions' phase. These features are imprinted in the radiation emitted by the cavity, which is readily measurable in state-of-the-art setups of cavity quantum electrodynamics. PMID:26684118

  2. Extremely Large Cusp Diamagnetic Cavities

    NASA Astrophysics Data System (ADS)

    Chen, J.; Fritz, T. A.

    2002-05-01

    Extremely large diamagnetic cavities with a size of as large as 6 Re have been observed in the dayside high-altitude cusp regions. Some of the diamagnetic cavities were independent of the IMF directions, which is unexpected by the current MHD (or ISM) models, suggesting that the cusp diamagnetic cavities are different from the magnetospheric sash, which provides a challenge to the existing MHD (or ISM) models. Associated with these cavities are ions with energies from 40 keV up to 8 MeV. The charge state distribution of these cusp cavity ions was indicative of their seed populations being a mixture of the ionospheric and the solar wind particles. The intensities of the cusp cavity energetic ions were observed to increase by as large as four orders of the magnitudes. During high solar wind pressure period on April 21, 1999, the POLAR spacecraft observed lower ion flux in the dayside high-latitude magnetosheath than that in the neighbouring cusp cavities. These observations indicate that the dayside high-altitude cusp diamagnetic cavity is a key region for transferring the solar wind energy, mass, and momentum into the Earth's magnetosphere. These energetic particles in the cusp diamagnetic cavity together with the cusp's connectivity have significant global impacts on the geospace environment research and will be shedding light on the long-standing unsolved fundamental issue about the origins of the energetic particles in the ring current and in upstream ion events.

  3. Extremely large cusp diamagnetic cavities

    NASA Astrophysics Data System (ADS)

    Chen, J.; Fritz, T.; Siscoe, G.

    Extremely large diamagnetic cavities with a size of as large as 6 Re have been observed in the dayside high-altitude cusp regions. These diamagnetic cavities are always there day by day. Some of the diamagnetic cavities have been observed in the morningside during intervals when the IMF By component was positive (duskward), suggesting that the cusp diamagnetic cavities are different from the magnetospheric sash predicted by MHD simulations. Associated with these cavities are ions with energies from 40 keV up to 8 MeV. The charge state distribution of these cusp cavity ions was indicative of their seed populations being a mixture of the ionospheric and the solar wind particles. The intensities of the cusp cavity energetic ions were observed to increase by as large as four orders of the magnitudes. These observations indicate that the dayside high-altitude cusp diamagnetic cavity is a key region for transferring the solar wind energy, mass, and momentum into the Earth's magnetosphere. These energetic particles in the cusp diamagnetic cavity together with the cusp's connectivity to the entire magnetopause may have significant global impacts on the geospace environment. They will possibly be shedding light on the long-standing unsolved fundamental issue about the origins of the energetic particles in the ring current and in the regions upstream of the subsolar magnetopause where energetic ion events frequently are observed.

  4. Nanofriction in Cavity Quantum Electrodynamics

    NASA Astrophysics Data System (ADS)

    Fogarty, T.; Cormick, C.; Landa, H.; Stojanović, Vladimir M.; Demler, E.; Morigi, Giovanna

    2015-12-01

    The dynamics of cold trapped ions in a high-finesse resonator results from the interplay between the long-range Coulomb repulsion and the cavity-induced interactions. The latter are due to multiple scatterings of laser photons inside the cavity and become relevant when the laser pump is sufficiently strong to overcome photon decay. We study the stationary states of ions coupled with a mode of a standing-wave cavity as a function of the cavity and laser parameters, when the typical length scales of the two self-organizing processes, Coulomb crystallization and photon-mediated interactions, are incommensurate. The dynamics are frustrated and in specific limiting cases can be cast in terms of the Frenkel-Kontorova model, which reproduces features of friction in one dimension. We numerically recover the sliding and pinned phases. For strong cavity nonlinearities, they are in general separated by bistable regions where superlubric and stick-slip dynamics coexist. The cavity, moreover, acts as a thermal reservoir and can cool the chain vibrations to temperatures controlled by the cavity parameters and by the ions' phase. These features are imprinted in the radiation emitted by the cavity, which is readily measurable in state-of-the-art setups of cavity quantum electrodynamics.

  5. [INVITED] New advances in fiber cavity ring-down technology

    NASA Astrophysics Data System (ADS)

    Silva, S. O.; Magalhães, R.; Marques, M. B.; Frazão, O.

    2016-04-01

    A brief review in the cavity ring-down technique (CRD) is presented. In this review, there will only be considered the conventional fiber CRD configuration, i.e., there will only be presented researches involving cavities with two couplers with 99:1 ratios, due to the large amount of publications involving this spectroscopy method. The presented survey is divided in different topics related to the measurement of physical parameters, such as strain and temperature, curvature, pressure, refractive index, gas and biochemical sensing.

  6. A scanning cavity microscope.

    PubMed

    Mader, Matthias; Reichel, Jakob; Hänsch, Theodor W; Hunger, David

    2015-01-01

    Imaging the optical properties of individual nanosystems beyond fluorescence can provide a wealth of information. However, the minute signals for absorption and dispersion are challenging to observe, and only specialized techniques requiring sophisticated noise rejection are available. Here we use signal enhancement in a high-finesse scanning optical microcavity to demonstrate ultra-sensitive imaging. Harnessing multiple interactions of probe light with a sample within an optical resonator, we achieve a 1,700-fold signal enhancement compared with diffraction-limited microscopy. We demonstrate quantitative imaging of the extinction cross-section of gold nanoparticles with a sensitivity less than 1 nm(2); we show a method to improve the spatial resolution potentially below the diffraction limit by using higher order cavity modes, and we present measurements of the birefringence and extinction contrast of gold nanorods. The demonstrated simultaneous enhancement of absorptive and dispersive signals promises intriguing potential for optical studies of nanomaterials, molecules and biological nanosystems. PMID:26105690

  7. Accessory oral cavity

    PubMed Central

    Gnaneswaran, Manica Ramamoorthy; Varadarajan, Usha; Srinivasan, Ramesh; Kamatchi, Sangeetha

    2012-01-01

    This is a rare case report of a patient around 11 years with the complaint of extra mouth who reported to the hospital for removal of that extra mouth. On examination there was accessory oral cavity with small upper and lower lips, seven teeth and saliva was drooling out. Under general anesthesia crevicular incision from 32 to 43 was put and labial gingiva with alveolar mucosa was reflected completely and bone exposed to lower border of mandible. There were seven teeth resembling lower permanent anterior teeth in the accessory mouth, which was excised with the accessory lips. 41 extracted and osteotomy carried out extending the incision from the extracted site and osteotomy carried out. Dermoid cyst both below and above the mylohyoid muscle and rudimentary tongue found and excised and the specimen sent for histopathological examination. The wound was closed and uneventful healing noted to the satisfaction of the patient. This is a rare and interesting case which has been documented. PMID:23833508

  8. A scanning cavity microscope

    PubMed Central

    Mader, Matthias; Reichel, Jakob; Hänsch, Theodor W.; Hunger, David

    2015-01-01

    Imaging the optical properties of individual nanosystems beyond fluorescence can provide a wealth of information. However, the minute signals for absorption and dispersion are challenging to observe, and only specialized techniques requiring sophisticated noise rejection are available. Here we use signal enhancement in a high-finesse scanning optical microcavity to demonstrate ultra-sensitive imaging. Harnessing multiple interactions of probe light with a sample within an optical resonator, we achieve a 1,700-fold signal enhancement compared with diffraction-limited microscopy. We demonstrate quantitative imaging of the extinction cross-section of gold nanoparticles with a sensitivity less than 1 nm2; we show a method to improve the spatial resolution potentially below the diffraction limit by using higher order cavity modes, and we present measurements of the birefringence and extinction contrast of gold nanorods. The demonstrated simultaneous enhancement of absorptive and dispersive signals promises intriguing potential for optical studies of nanomaterials, molecules and biological nanosystems. PMID:26105690

  9. Quench studies of ILC cavities

    SciTech Connect

    Eremeev, Grigory; Geng, Rongli; Palczewski, Ari; Dai, Jin

    2011-07-01

    Quench limits accelerating gradient in SRF cavities to a gradient lower than theoretically expected for superconducting niobium. Identification of the quenching site with thermometry and OST, optical inspection, and replica of the culprit is an ongoing effort at Jefferson Lab aimed at better understanding of this limiting phenomenon. In this contribution we present our finding with several SRF cavities that were limited by quench.

  10. Trislot-cavity microstrip antenna

    NASA Technical Reports Server (NTRS)

    Ellis, H., Jr.

    1981-01-01

    Flush-mountable assembly composed of disk radiator sandwiched between planes of metal-clad dielectric board has greater bandwidths and beamwidths than simple disk antenna. Conducting planes connect so that disk is enclosed in cavity with Y-shaped slot in top plane. Cavity is excited by microwave energy from disk and radiates from trislot aperature.

  11. Addressing a single spin in diamond with a macroscopic dielectric microwave cavity

    SciTech Connect

    Le Floch, J.-M.; Tobar, M. E.; Bradac, C.; Nand, N.; Volz, T.; Castelletto, S.

    2014-09-29

    We present a technique for addressing single nitrogen-vacancy (NV) center spins in diamond over macroscopic distances using a tunable dielectric microwave cavity. We demonstrate optically detected magnetic resonance (ODMR) for a single negatively charged NV center (NV{sup –}) in a nanodiamond (ND) located directly under the macroscopic microwave cavity. By moving the cavity relative to the ND, we record the ODMR signal as a function of position, mapping out the distribution of the cavity magnetic field along one axis. In addition, we argue that our system could be used to determine the orientation of the NV{sup –} major axis in a straightforward manner.

  12. Self-organization of frozen light in near-zero-index media with cubic nonlinearity

    PubMed Central

    Marini, A.; García de Abajo, F. J.

    2016-01-01

    Optical beams are generally unbound in bulk media, and propagate with a velocity approximately amounting to the speed of light in free-space. Guidance and full spatial confinement of light are usually achieved by means of waveguides, mirrors, resonators, and photonic crystals. Here we theoretically demonstrate that nonlinear self-organization can be exploited to freeze optical beams in bulk near-zero-index media, thus enabling three-dimensional self-trapping of still light without the need of optical resonators. Light is stopped to a standstill owing to the divergent wavelength and the vanishing group velocity, effectively rendering, through nonlinearity, a positive-epsilon trapping cavity carved in an otherwise slightly-negative-epsilon medium. By numerically solving Maxwell’s equations, we find a soliton-like family of still azimuthal doughnuts, which we further study through an adiabatic perturbative theory that describes soliton evaporation in lossy media or condensation in actively pumped materials. Our results suggest applications in optical data processing and storage, quantum optical memories, and soliton-based lasers without cavities. Additionally, near-zero-index conditions can also be found in the interplanetary medium and in the atmosphere, where we provide a complementary explanation to the rare phenomenon of ball-lightning. PMID:26847877

  13. Self-organization of frozen light in near-zero-index media with cubic nonlinearity.

    PubMed

    Marini, A; de Abajo, F J García

    2016-01-01

    Optical beams are generally unbound in bulk media, and propagate with a velocity approximately amounting to the speed of light in free-space. Guidance and full spatial confinement of light are usually achieved by means of waveguides, mirrors, resonators, and photonic crystals. Here we theoretically demonstrate that nonlinear self-organization can be exploited to freeze optical beams in bulk near-zero-index media, thus enabling three-dimensional self-trapping of still light without the need of optical resonators. Light is stopped to a standstill owing to the divergent wavelength and the vanishing group velocity, effectively rendering, through nonlinearity, a positive-epsilon trapping cavity carved in an otherwise slightly-negative-epsilon medium. By numerically solving Maxwell's equations, we find a soliton-like family of still azimuthal doughnuts, which we further study through an adiabatic perturbative theory that describes soliton evaporation in lossy media or condensation in actively pumped materials. Our results suggest applications in optical data processing and storage, quantum optical memories, and soliton-based lasers without cavities. Additionally, near-zero-index conditions can also be found in the interplanetary medium and in the atmosphere, where we provide a complementary explanation to the rare phenomenon of ball-lightning. PMID:26847877

  14. Self-organization of frozen light in near-zero-index media with cubic nonlinearity

    NASA Astrophysics Data System (ADS)

    Marini, A.; García de Abajo, F. J.

    2016-02-01

    Optical beams are generally unbound in bulk media, and propagate with a velocity approximately amounting to the speed of light in free-space. Guidance and full spatial confinement of light are usually achieved by means of waveguides, mirrors, resonators, and photonic crystals. Here we theoretically demonstrate that nonlinear self-organization can be exploited to freeze optical beams in bulk near-zero-index media, thus enabling three-dimensional self-trapping of still light without the need of optical resonators. Light is stopped to a standstill owing to the divergent wavelength and the vanishing group velocity, effectively rendering, through nonlinearity, a positive-epsilon trapping cavity carved in an otherwise slightly-negative-epsilon medium. By numerically solving Maxwell’s equations, we find a soliton-like family of still azimuthal doughnuts, which we further study through an adiabatic perturbative theory that describes soliton evaporation in lossy media or condensation in actively pumped materials. Our results suggest applications in optical data processing and storage, quantum optical memories, and soliton-based lasers without cavities. Additionally, near-zero-index conditions can also be found in the interplanetary medium and in the atmosphere, where we provide a complementary explanation to the rare phenomenon of ball-lightning.

  15. Mechanical Properties of Niobium Cavities

    SciTech Connect

    Ciovati, Gianluigi; Dhakal, Pashupati; Matalevich, Joseph R.; Myneni, Ganapati Rao

    2015-09-01

    The mechanical stability of bulk Nb cavity is an important aspect to be considered in relation to cavity material, geometry and treatments. Mechanical properties of Nb are typically obtained from uniaxial tensile tests of small samples. In this contribution we report the results of measurements of the resonant frequency and local strain along the contour of single-cell cavities made of ingot and fine-grain Nb of different purity subjected to increasing uniform differential pressure, up to 6 atm. Measurements have been done on cavities subjected to different heat treatments. Good agreement between finite element analysis simulations and experimental data in the elastic regime was obtained with a single set of values of Young’s modulus and Poisson’s ratio. The experimental results indicate that the yield strength of medium-purity ingot Nb cavities is higher than that of fine-grain, high-purity Nb.

  16. Superconducting Storage Cavity for RHIC

    SciTech Connect

    Ben-Zvi,I.

    2009-01-02

    This document provides a top-level description of a superconducting cavity designed to store hadron beams in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. It refers to more detailed documents covering the various issues in designing, constructing and operating this cavity. The superconducting storage cavity is designed to operate at a harmonic of the bunch frequency of RHIC at a relatively low frequency of 56 MHz. The current storage cavities of RHIC operate at 197 MHz and are normal-conducting. The use of a superconducting cavity allows for a high gap voltage, over 2 MV. The combination of a high voltage and low frequency provides various advantages stemming from the resulting large longitudinal acceptance bucket.

  17. Monochromatic radio frequency accelerating cavity

    DOEpatents

    Giordano, Salvatore

    1985-01-01

    A radio frequency resonant cavity having a fundamental resonant frequency and characterized by being free of spurious modes. A plurality of spaced electrically conductive bars are arranged in a generally cylindrical array within the cavity to define a chamber between the bars and an outer solid cylindrically shaped wall of the cavity. A first and second plurality of mode perturbing rods are mounted in two groups at determined random locations to extend radially and axially into the cavity thereby to perturb spurious modes and cause their fields to extend through passageways between the bars and into the chamber. At least one body of lossy material is disposed within the chamber to damp all spurious modes that do extend into the chamber thereby enabling the cavity to operate free of undesired spurious modes.

  18. Monochromatic radio frequency accelerating cavity

    DOEpatents

    Giordano, S.

    1984-02-09

    A radio frequency resonant cavity having a fundamental resonant frequency and characterized by being free of spurious modes. A plurality of spaced electrically conductive bars are arranged in a generally cylindrical array within the cavity to define a chamber between the bars and an outer solid cylindrically shaped wall of the cavity. A first and second plurality of mode perturbing rods are mounted in two groups at determined random locations to extend radially and axially into the cavity thereby to perturb spurious modes and cause their fields to extend through passageways between the bars and into the chamber. At least one body of lossy material is disposed within the chamber to damp all spurious modes that do extend into the chamber thereby enabling the cavity to operate free of undesired spurious modes.

  19. Dusty plasma cavities: Probe-induced and natural

    NASA Astrophysics Data System (ADS)

    Harris, B. J.; Matthews, L. S.; Hyde, T. W.

    2015-06-01

    A comprehensive exploration of regional dust evacuation in complex plasma crystals is presented. Voids created in three-dimensional crystals on the International Space Station have provided a rich foundation for experiments, but cavities in dust crystals formed in ground-based experiments have not received as much attention. Inside a modified Gaseous Electronics Conference rf cell, a powered vertical probe was used to clear the central area of a dust crystal, producing a cavity with high cylindrical symmetry. Cavities generated by three mechanisms are examined. First, repulsion of micrometer-sized particles by a negatively charged probe is investigated. A model of this effect developed for a dc plasma is modified and applied to explain experimental data in rf plasma. Second, the formation of natural cavities is surveyed; a radial ion drag proposed to occur due to a curved sheath is considered in conjunction with thermophoresis and a flattened confinement potential above the center of the electrode. Finally, cavity formation upon increasing the probe potential above the plasma floating potential is justified by a combination of ion drag and sheath edge modification. The cavities produced by these methods appear similar, but each is shown to be facilitated by fundamentally different processes.

  20. Dusty plasma cavities: Probe-induced and natural.

    PubMed

    Harris, B J; Matthews, L S; Hyde, T W

    2015-06-01

    A comprehensive exploration of regional dust evacuation in complex plasma crystals is presented. Voids created in three-dimensional crystals on the International Space Station have provided a rich foundation for experiments, but cavities in dust crystals formed in ground-based experiments have not received as much attention. Inside a modified Gaseous Electronics Conference rf cell, a powered vertical probe was used to clear the central area of a dust crystal, producing a cavity with high cylindrical symmetry. Cavities generated by three mechanisms are examined. First, repulsion of micrometer-sized particles by a negatively charged probe is investigated. A model of this effect developed for a dc plasma is modified and applied to explain experimental data in rf plasma. Second, the formation of natural cavities is surveyed; a radial ion drag proposed to occur due to a curved sheath is considered in conjunction with thermophoresis and a flattened confinement potential above the center of the electrode. Finally, cavity formation upon increasing the probe potential above the plasma floating potential is justified by a combination of ion drag and sheath edge modification. The cavities produced by these methods appear similar, but each is shown to be facilitated by fundamentally different processes. PMID:26172806

  1. Pressure Gradient Effects on Hypersonic Cavity Flow Heating

    NASA Technical Reports Server (NTRS)

    Everhart, Joel L.; Alter, Stephen J.; Merski, N. Ronald; Wood, William A.; Prabhu, Ramdas K.

    2007-01-01

    The effect of a pressure gradient on the local heating disturbance of rectangular cavities tested at hypersonic freestream conditions has been globally assessed using the two-color phosphor thermography method. These experiments were conducted in the Langley 31-Inch Mach 10 Tunnel and were initiated in support of the Space Shuttle Return-To-Flight Program. Two blunted-nose test surface geometries were developed, including an expansion plate test surface with nearly constant negative pressure gradient and a flat plate surface with nearly zero pressure gradient. The test surface designs and flow characterizations were performed using two-dimensional laminar computational methods, while the experimental boundary layer state conditions were inferred using the measured heating distributions. Three-dimensional computational predictions of the entire model geometry were used as a check on the design process. Both open-flow and closed-flow cavities were tested on each test surface. The cavity design parameters and the test condition matrix were established using the computational predictions. Preliminary conclusions based on an analysis of only the cavity centerline data indicate that the presence of the pressure gradient did not alter the open cavity heating for laminar-entry/laminar-exit flows, but did raise the average floor heating for closed cavities. The results of these risk-reduction studies will be used to formulate a heating assessment of potential damage scenarios occurring during future Space Shuttle flights.

  2. Pressure Gradient Effects on Hypersonic Cavity Flow Heating

    NASA Technical Reports Server (NTRS)

    Everhart, Joel L.; Alter, Stephen J.; Merski, N. Ronald; Wood, William A.; Prabhu, Ramadas K.

    2006-01-01

    The effect of a pressure gradient on the local heating disturbance of rectangular cavities tested at hypersonic freestream conditions has been globally assessed using the two-color phosphor thermography method. These experiments were conducted in the Langley 31-Inch Mach 10 Tunnel and were initiated in support of the Space Shuttle Return-To-Flight Program. Two blunted-nose test surface geometries were developed, including an expansion plate test surface with nearly constant negative pressure gradient and a flat plate surface with nearly zero pressure gradient. The test surface designs and flow characterizations were performed using two-dimensional laminar computational methods, while the experimental boundary layer state conditions were inferred using the measured heating distributions. Three-dimensional computational predictions of the entire model geometry were used as a check on the design process. Both open-flow and closed-flow cavities were tested on each test surface. The cavity design parameters and the test condition matrix were established using the computational predictions. Preliminary conclusions based on an analysis of only the cavity centerline data indicate that the presence of the pressure gradient did not alter the open cavity heating for laminar-entry/laminar-exit flows, but did raise the average floor heating for closed cavities. The results of these risk-reduction studies will be used to formulate a heating assessment of potential damage scenarios occurring during future Space Shuttle flights.

  3. Coupling and single-photon purity of a quantum dot-cavity system studied using hydrostatic pressure

    SciTech Connect

    Zhou, P. Y.; Wu, X. F.; Ding, K.; Dou, X. M.; Zha, G. W.; Ni, H. Q.; Niu, Z. C.; Zhu, H. J.; Jiang, D. S.; Zhao, C. L.; Sun, B. Q.

    2015-01-07

    We propose an approach to tune the emission of a single semiconductor quantum dot (QD) to couple with a planar cavity using hydrostatic pressure without inducing temperature variation during the process of measurement. Based on this approach, we studied the influence of cavity mode on the single-photon purity of an InAs/GaAs QD. Our measurement demonstrates that the single-photon purity degrades when the QD emission resonates with the cavity mode. This negative influence of the planar cavity is mainly caused by the cavity feeding effect.

  4. Stages of Lip and Oral Cavity Cancer

    MedlinePlus

    ... Cavity and Oropharyngeal Cancer Screening Research Lip and Oral Cavity Cancer Treatment (PDQ®)–Patient Version General Information About Lip and Oral Cavity Cancer Go to Health Professional Version Key Points ...

  5. Resonance frequencies of a cavity containing a compressible viscous fluid

    NASA Astrophysics Data System (ADS)

    Conca, C.; Planchard, J.; Vanninathan, M.

    1993-03-01

    The aim of this paper is to study the resonance spectrum of a cavity containing a compressible viscous fluid. This system admits a discrete infinite sequence of eigenvalues whose real parts are negative, which is interpreted as the damping effect introduced by viscosity. Only a finite number of them have non-zero imaginary parts and this number depends on viscosity; a simple criterion is given for their position in the complex plane. The case of a cavity containing an elastic mechanical system immersed in the fluid is also examined; from a qualitative point of view, the nature of the resonance spectrum remains unchanged.

  6. Frequency-feedback cavity enhanced spectrometer

    DOEpatents

    Hovde, David Christian; Gomez, Anthony

    2015-08-18

    A spectrometer comprising an optical cavity, a light source capable of producing light at one or more wavelengths transmitted by the cavity and with the light directed at the cavity, a detector and optics positioned to collect light transmitted by the cavity, feedback electronics causing oscillation of amplitude of the optical signal on the detector at a frequency that depends on cavity losses, and a sensor measuring the oscillation frequency to determine the cavity losses.

  7. Deterministic coupling of delta-doped nitrogen vacancy centers to a nanobeam photonic crystal cavity

    SciTech Connect

    Lee, Jonathan C.; Cui, Shanying; Zhang, Xingyu; Russell, Kasey J.; Magyar, Andrew P.; Hu, Evelyn L.; Bracher, David O.; Ohno, Kenichi; McLellan, Claire A.; Alemán, Benjamin; Bleszynski Jayich, Ania; Andrich, Paolo; Awschalom, David; Aharonovich, Igor

    2014-12-29

    The negatively charged nitrogen vacancy center (NV) in diamond has generated significant interest as a platform for quantum information processing and sensing in the solid state. For most applications, high quality optical cavities are required to enhance the NV zero-phonon line (ZPL) emission. An outstanding challenge in maximizing the degree of NV-cavity coupling is the deterministic placement of NVs within the cavity. Here, we report photonic crystal nanobeam cavities coupled to NVs incorporated by a delta-doping technique that allows nanometer-scale vertical positioning of the emitters. We demonstrate cavities with Q up to ∼24 000 and mode volume V ∼ 0.47(λ/n){sup 3} as well as resonant enhancement of the ZPL of an NV ensemble with Purcell factor of ∼20. Our fabrication technique provides a first step towards deterministic NV-cavity coupling using spatial control of the emitters.

  8. Composite resonator vertical cavity laser diode

    SciTech Connect

    Choquette, K.D.; Hou, H.Q.; Chow, W.W.; Geib, K.M.; Hammons, B.E.

    1998-05-01

    The use of two coupled laser cavities has been employed in edge emitting semiconductor lasers for mode suppression and frequency stabilization. The incorporation of coupled resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the interaction between the cavities. Composite resonators can be utilized to control spectral and temporal properties within the laser; previous studies of coupled cavity vertical cavity lasers have employed photopumped structures. The authors report the first composite resonator vertical cavity laser diode consisting of two optical cavities and three monolithic distributed Bragg reflectors. Cavity coupling effects and two techniques for external modulation of the laser are described.

  9. Progressive cavity pump

    SciTech Connect

    Mueller, J.W.

    1989-04-04

    A progressive cavity pump is described, comprising: a first housing portion defining an inlet; a second housing portion attachable to the first housing portion and defining an outlet; a substantially elastomeric stator comprising an outer portion removably attached to the first and second housing portions, having a first end and a second end spaced from the first end, an inner portion defining a pumping chamber and spaced an annular end portion interconnecting the first ends of the outer and inner portions; a rotor disposed in the inner portion of the stator and extending through the pumping chamber for pumping fluid from the inlet to the outlet in response to rotation of the rotor; and an elongated member disposed in the housing portions and generally annularly between the inner and outer portions of the stator and longitudinally between the annular end portion of the stator and a portion of the second housing portion, the member being removable from the housing portions and separable from the stator.

  10. Nonlocal Intracranial Cavity Extraction

    PubMed Central

    Manjón, José V.; Eskildsen, Simon F.; Coupé, Pierrick; Romero, José E.; Collins, D. Louis; Robles, Montserrat

    2014-01-01

    Automatic and accurate methods to estimate normalized regional brain volumes from MRI data are valuable tools which may help to obtain an objective diagnosis and followup of many neurological diseases. To estimate such regional brain volumes, the intracranial cavity volume (ICV) is often used for normalization. However, the high variability of brain shape and size due to normal intersubject variability, normal changes occurring over the lifespan, and abnormal changes due to disease makes the ICV estimation problem challenging. In this paper, we present a new approach to perform ICV extraction based on the use of a library of prelabeled brain images to capture the large variability of brain shapes. To this end, an improved nonlocal label fusion scheme based on BEaST technique is proposed to increase the accuracy of the ICV estimation. The proposed method is compared with recent state-of-the-art methods and the results demonstrate an improved performance both in terms of accuracy and reproducibility while maintaining a reduced computational burden. PMID:25328511

  11. Running spectral index from inflation with modulations

    SciTech Connect

    Kobayashi, Takeshi; Takahashi, Fuminobu E-mail: fuminobu.takahashi@ipmu.jp

    2011-01-01

    We argue that a large negative running spectral index, if confirmed, might suggest that there are abundant structures in the inflaton potential, which result in a fairly large (both positive and negative) running of the spectral index at all scales. It is shown that the center value of the running spectral index suggested by the recent CMB data can be easily explained by an inflaton potential with superimposed periodic oscillations. In contrast to cases with constant running, the perturbation spectrum is enhanced at small scales, due to the repeated modulations. We mention that such features at small scales may be seen by 21 cm observations in the future.

  12. Novel Crab Cavity RF Design

    SciTech Connect

    Dudas, A.; Neubauer, M. L.; Sah, R.; Rimmer, B.; Wang, H.

    2011-03-01

    A 20-50 MV integrated transverse voltage is required for the Electron-Ion Collider. The most promising of the crab cavity designs that have been proposed in the last five years are the TEM type crab cavities because of the higher transverse impedance. The TEM design approach is extended here to a hybrid crab cavity that includes the input power coupler as an integral part of the design. A prototype was built with Phase I monies and tested at JLAB. The results reported on, and a system for achieving 20-50 MV is proposed.

  13. Call for Papers: Cavity QED

    NASA Astrophysics Data System (ADS)

    Lange, W.; Gerard, J.-M.

    2003-06-01

    Cavity QED interactions of light and matter have been investigated in a wide range of systems covering the spectrum from microwaves to optical frequencies, using media as diverse as single atoms and semiconductors. Impressive progress has been achieved technologically as well as conceptually. This topical issue of Journal of Optics B: Quantum and Semiclassical Optics is intended to provide a comprehensive account of the current state of the art of cavity QED by uniting contributions from researchers active across this field. As Guest Editors of this topical issue, we invite manuscripts on current theoretical and experimental work on any aspects of cavity QED. The topics to be covered will include, but are not limited to: bulletCavity QED in optical microcavities bulletSemiconductor cavity QED bulletQuantum dot cavity QED bulletRydberg atoms in microwave cavities bulletPhotonic crystal cavity QED bulletMicrosphere resonators bulletMicrolasers and micromasers bulletMicrodroplets bulletDielectric cavity QED bulletCavity QED-based quantum information processing bulletQuantum state engineering in cavities The DEADLINE for submission of contributions is 31 July 2003 to allow the topical issue to appear in about February 2004. All papers will be peer-reviewed in accordance with the normal refereeing procedures and standards of Journal of Optics B: Quantum and Semiclassical Optics. Advice on publishing your work in the journal may be found at www.iop.org/journals/authors/jopb. Submissions should ideally be in either standard LaTeX form or Microsoft Word. There are no page charges for publication. In addition to the usual 50 free reprints, the corresponding author of each paper published will receive a complimentary copy of the topical issue. Contributions to the topical issue should if possible be submitted electronically at www.iop.org/journals/jopb. or by e-mail to jopb@iop.org. Authors unable to submit online or by e-mail may send hard copy contributions (enclosing the

  14. A Overmoded Gyroklystron with Tuning of the Penultimate Cavity

    NASA Astrophysics Data System (ADS)

    Tantawi, Sami Gamal El-Din

    The design and performance of a 10GHz TE _{01}^circ mode three -cavity gyroklystron with a tunable penultimate cavity is presented. The electron beam was produced by a pulse line modulator and a magnetron injection gun which operates to 430kV and 225A with 1 mus flat -top. Two different three-cavity tubes have been tested. The final model produced a peak power of 27MW with efficiency of 32%, 36dB gain and pulse energy of 39J. A maximum gain of 50dB was achieved at a peak power of 20MW and a maximum efficiency of 39% was achieved at a peak power of 15MW. This performance surpasses in significant ways the performance of a previously studied 2-cavity gyroklystron. The theoretical design procedure is described. Since the device is overmoded, it required loading with lossy dielectric to suppress higher and lower order modes. Theoretical and experimental procedures used to design the drift sections between the cavities are reported. The loading schemes for the input and buncher cavity, such that all modes but the operating mode are suppressed, are presented. We describe in detail the schemes used to excite the operating mode in the input cavity and to realize the tunability of the buncher cavity. The experimental procedures and diagnostics used in characterizing the two tubes are described. A detailed study of the stability and amplification, including the phase characteristics of the tubes are reported. The negative detuning of the buncher cavity enhanced both gain and efficiency. The effects of buncher cavity detuning and magnetic field tapering on the enhancement of the device performance are investigated. Finally, we compare the results with available theory. Although both tubes operated efficiently, they operated with a low value of beam alpha (ratio between perpendicular to axial velocities). The devices operated with an alpha between 0.66 to 0.8 in contrast with conventional gyrotrons which operate with an alpha between 1.5 and 2. The original simulation codes did

  15. Indexing Consistency and Quality.

    ERIC Educational Resources Information Center

    Zunde, Pranas; Dexter, Margaret E.

    A measure of indexing consistency is developed based on the concept of 'fuzzy sets'. It assigns a higher consistency value if indexers agree on the more important terms than if they agree on less important terms. Measures of the quality of an indexer's work and exhaustivity of indexing are also proposed. Experimental data on indexing consistency…

  16. CRAB Cavity in CERN SPS

    SciTech Connect

    Kim, H.J.; Sen, T.; /Fermilab

    2010-05-01

    Beam collisions with a crossing angle at the interaction point are often necessary in colliders to reduce the effects of parasitic collisions which induce emittance growth and decrease beam lifetime. The crossing angle reduces the geometrical overlap of the beams and hence the luminosity. Crab cavity offer a promising way to compensate the crossing angle and to realize effective head-on collisions. Moreover, the crab crossing mitigates the synchro-betatron resonances due to the crossing angle. A crab cavity experiment in SPS is proposed as a proof of principle before deciding on a full crab-cavity implementation in the LHC. In this paper, we investigate the effects of a single crab cavity on beam dynamics in the SPS and life time.

  17. [Radiotherapy for oral cavity cancers].

    PubMed

    Lapeyre, M; Biau, J; Racadot, S; Moreira, J F; Berger, L; Peiffert, D

    2016-09-01

    Intensity modulated radiation therapy (IMRT) and brachytherapy are standard techniques for the irradiation of oral cavity cancers. These techniques are detailed in terms of indication, preparation, delineation and selection of the volumes, dosimetry and patient positioning control. PMID:27521039

  18. Tuning the Sensitivity of an Optical Cavity with Slow and Fast Light

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Myneni, Krishna; Chang, H.; Toftul, A.; Schambeau, C.; Odutola, J. A.; Diels, J. C.

    2012-01-01

    We have measured mode pushing by the dispersion of a rubidium vapor in a Fabry-Perot cavity and have shown that the scale factor and sensitivity of a passive cavity can be strongly enhanced by the presence of such an anomalous dispersion medium. The enhancement is the result of the atom-cavity coupling, which provides a positive feedback to the cavity response. The cavity sensitivity can also be controlled and tuned through a pole by a second, optical pumping, beam applied transverse to the cavity. Alternatively, the sensitivity can be controlled by the introduction of a second counter-propagating input beam that interferes with the first beam, coherently increasing the cavity absorptance. We show that the pole in the sensitivity occurs when the sum of the effective group index and an additional cavity delay factor that accounts for mode reshaping goes to zero, and is an example of an exceptional point, commonly associated with coupled non-Hermitian Hamiltonian systems. Additionally we show that a normal dispersion feature can decrease the cavity scale factor and can be generated through velocity selective optical pumping

  19. III-nitride tunable cup-cavities supporting quasi whispering gallery modes from ultraviolet to infrared

    NASA Astrophysics Data System (ADS)

    Shubina, T. V.; Pozina, G.; Jmerik, V. N.; Davydov, V. Yu.; Hemmingsson, C.; Andrianov, A. V.; Kazanov, D. R.; Ivanov, S. V.

    2015-12-01

    Rapidly developing nanophotonics needs microresonators for different spectral ranges, formed by chip-compatible technologies. In addition, the tunable ones are much in demand. Here, we present site-controlled III-nitride monocrystal cup-cavities grown by molecular beam epitaxy. The cup-cavities can operate from ultraviolet to near-infrared, supporting quasi whispering gallery modes up to room temperature. Besides, their energies are identical in large ’ripened’ crystals. In these cavities, the refractive index variation near an absorption edge causes the remarkable effect of mode switching, which is accompanied by the spatial redistribution of electric field intensity with concentration of light into a subwavelength volume. Our results shed light on the mode behavior in semiconductor cavities and open the way for single-growth-run manufacturing the devices comprising an active region and a cavity with tunable mode frequencies.

  20. III-nitride tunable cup-cavities supporting quasi whispering gallery modes from ultraviolet to infrared

    PubMed Central

    Shubina, T. V.; Pozina, G.; Jmerik, V. N.; Davydov, V. Yu.; Hemmingsson, C.; Andrianov, A. V.; Kazanov, D. R.; Ivanov, S. V.

    2015-01-01

    Rapidly developing nanophotonics needs microresonators for different spectral ranges, formed by chip-compatible technologies. In addition, the tunable ones are much in demand. Here, we present site-controlled III-nitride monocrystal cup-cavities grown by molecular beam epitaxy. The cup-cavities can operate from ultraviolet to near-infrared, supporting quasi whispering gallery modes up to room temperature. Besides, their energies are identical in large ’ripened’ crystals. In these cavities, the refractive index variation near an absorption edge causes the remarkable effect of mode switching, which is accompanied by the spatial redistribution of electric field intensity with concentration of light into a subwavelength volume. Our results shed light on the mode behavior in semiconductor cavities and open the way for single-growth-run manufacturing the devices comprising an active region and a cavity with tunable mode frequencies. PMID:26656267

  1. Resident aerobic microbiota of the adult human nasal cavity.

    PubMed

    Rasmussen, T T; Kirkeby, L P; Poulsen, K; Reinholdt, J; Kilian, M

    2000-10-01

    Recent evidence strongly suggests that the microbiota of the nasal cavity plays a crucial role in determining the reaction patterns of the mucosal and systemic immune system. However, little is known about the normal microbiota of the nasal cavity. The purpose of this study was to determine the microbiota in different parts of the nasal cavity and to develop and evaluate methods for this purpose. Samples were collected from 10 healthy adults by nasal washes and by swabbing of the mucosa through a sterile introduction device. Both methods gave results that were quantitatively and qualitatively reproducible, and revealed significant differences in the density of the nasal microbiota between individuals. The study revealed absence of gram-negative bacteria that are regular members of the commensal microbiota of the pharynx. Likewise, viridans type streptococci were sparsely represented. The nasal microbiota was dominated by species of the genera Corynebacterium, Aureobacterium, Rhodococcus, and Staphylococcus, including S. epidermis, S. capitis, S. hominis, S. haemolyticus, S. lugdunensis and S. warneri. These studies show that the microbiota of the nasal cavity of adults is strikingly different from that of the pharynx, and that the nasal cavity is a primary habitat for several species of diphtheroids recognized as opportunistic pathogens. Under special circumstances, single species, including IgA1 protease-producing bacteria, may become predominant in a restricted area of the nasal mucosa. PMID:11200821

  2. Meningitis - gram-negative

    MedlinePlus

    Gram-negative meningitis ... Acute bacterial meningitis can be caused by Gram-negative bacteria. Meningococcal and H. influenzae meningitis are caused by Gram-negative bacteria and are covered in detail in other articles. This article ...

  3. Normal Conducting RF Cavity for MICE

    SciTech Connect

    Li, D.; DeMello, A.; Virostek, S.; Zisman, M.; Summers, D.

    2010-05-23

    Normal conducting RF cavities must be used for the cooling section of the international Muon Ionization Cooling Experiment (MICE), currently under construction at Rutherford Appleton Laboratory (RAL) in the UK. Eight 201-MHz cavities are needed for the MICE cooling section; fabrication of the first five cavities is complete. We report the cavity fabrication status including cavity design, fabrication techniques and preliminary low power RF measurements.

  4. Semi-monolithic cavity for external resonant frequency doubling and method of performing the same

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid (Inventor)

    1999-01-01

    The fabrication of an optical cavity for use in a laser, in a frequency doubling external cavity, or any other type of nonlinear optical device, can be simplified by providing the nonlinear crystal in combination with a surrounding glass having an index of refraction substantially equal to that of the nonlinear crystal. The closed optical path in this cavity is formed in the surrounding glass and through the nonlinear crystal which lies in one of the optical segments of the light path. The light is transmitted through interfaces between the surrounding glass in the nonlinear crystal through interfaces which are formed at the Brewster-angle to minimize or eliminate reflection.

  5. Coupling of an overdriven cavity

    SciTech Connect

    Garbin, H.D.

    1993-11-01

    It is well known that when a nuclear test is conducted in a sufficiently large cavity, the resulting seismic signal is sharply reduced when compared to a normal tamped event. Cavity explosions are of interest in the seismic verification community because of this possibility of reducing the seismic energy generated which can lower signal amplitudes and make detection difficult. Reduced amplitudes would also lower seismic yield estimates which has implications in a Threshold Test Ban Treaty (TTBT). In the past several years, there have been a number of nuclear tests at NTS (Nevada Test Site) inside hemispherical cavities. Two such tests were MILL YARD and MISTY ECHO which had instrumentation at the surface and in the free-field. These two tests differ in one important aspect. MILL YARD was completely decoupled i.e., the cavity wall behaved in an elastic manner. It was estimated that MILL YARD`s ground motion was reduced by a factor of at least 70. In contrast, MISTY ECHO was detonated in a hemispherical cavity with the same dimensions as MILL YARD, but with a much larger device yield. This caused an inelastic behavior on the wall and the explosion was not fully decoupled.

  6. The ESS spoke cavity cryomodules

    SciTech Connect

    Bousson, Sebastien; Duthil, Patxi; Reynet, Denis; Thermeau, Jean-Pierre

    2014-01-29

    The European Spallation Source (ESS) is a multi-disciplinary research centre under design and construction in Lund, Sweden. This new facility is funded by a collaboration of 17 European countries and is expected to be up to 30 times brighter than today’s leading facilities and neutron sources. The ESS will enable new opportunities for researchers in the fields of life sciences, energy, environmental technology, cultural heritage and fundamental physics. A 5 MW long pulse proton accelerator is used to reach this goal. The pulsed length is 2.86 ms, the repetition frequency is 14 Hz (4 % duty cycle), and the beam current is 62.5 mA. It is composed of one string of spoke cavity cryomodule and two strings of elliptical cavity cryomodules. This paper introduces the thermo-mechanical design and expected operation of the ESS spoke cavity cryomodules. These cryomodules contain two double spoke bulk Niobium cavities operating at 2 K and at a frequency of 352.21 MHz. The superconducting section of the Spoke Linac accelerates the beam from 90 MeV to 220 MeV. A Spoke Cavity Cryomodule Technology Demonstrator will be built and tested in order to validate the ESS series production.

  7. The ESS elliptical cavity cryomodules

    NASA Astrophysics Data System (ADS)

    Darve, Christine; Bosland, Pierre; Devanz, Guillaume; Olivier, Gilles; Renard, Bertrand; Thermeau, Jean-Pierre

    2014-01-01

    The European Spallation Source (ESS) is a multi-disciplinary research centre under design and construction in Lund, Sweden. This new facility is funded by a collaboration of 17 European countries and is expected to be up to 30 times brighter than today's leading facilities and neutron sources. The ESS will enable new opportunities for researchers in the fields of life sciences, energy, environmental technology, cultural heritage and fundamental physics. A 5 MW long pulse proton accelerator is used to reach this goal. The pulsed length is 2.86 ms, the repetition frequency is 14 Hz (4 % duty cycle), and the beam current is 62.5 mA. The superconducting section of the Linac accelerates the beam from 80 MeV to 2.0 GeV. It is composed of one string of spoke cavity cryomodule and two strings of elliptical cavity cryomodules. These cryomodules contain four elliptical Niobium cavities operating at 2 K and at a frequency of 704.42 MHz. This paper introduces the thermo-mechanical design, the prototyping and the expected operation of the ESS elliptical cavity cryomodules. An Elliptical Cavity Cryomodule Technology Demonstrator (ECCTD) will be built and tested in order to validate the ESS series production.

  8. The ESS spoke cavity cryomodules

    NASA Astrophysics Data System (ADS)

    Bousson, Sebastien; Darve, Christine; Duthil, Patxi; Elias, Nuno; Molloy, Steve; Reynet, Denis; Thermeau, Jean-Pierre

    2014-01-01

    The European Spallation Source (ESS) is a multi-disciplinary research centre under design and construction in Lund, Sweden. This new facility is funded by a collaboration of 17 European countries and is expected to be up to 30 times brighter than today's leading facilities and neutron sources. The ESS will enable new opportunities for researchers in the fields of life sciences, energy, environmental technology, cultural heritage and fundamental physics. A 5 MW long pulse proton accelerator is used to reach this goal. The pulsed length is 2.86 ms, the repetition frequency is 14 Hz (4 % duty cycle), and the beam current is 62.5 mA. It is composed of one string of spoke cavity cryomodule and two strings of elliptical cavity cryomodules. This paper introduces the thermo-mechanical design and expected operation of the ESS spoke cavity cryomodules. These cryomodules contain two double spoke bulk Niobium cavities operating at 2 K and at a frequency of 352.21 MHz. The superconducting section of the Spoke Linac accelerates the beam from 90 MeV to 220 MeV. A Spoke Cavity Cryomodule Technology Demonstrator will be built and tested in order to validate the ESS series production.

  9. The ESS elliptical cavity cryomodules

    SciTech Connect

    Darve, Christine; Bosland, Pierre; Devanz, Guillaume; Renard, Bertrand; Olivier, Gilles; Thermeau, Jean-Pierre

    2014-01-29

    The European Spallation Source (ESS) is a multi-disciplinary research centre under design and construction in Lund, Sweden. This new facility is funded by a collaboration of 17 European countries and is expected to be up to 30 times brighter than today’s leading facilities and neutron sources. The ESS will enable new opportunities for researchers in the fields of life sciences, energy, environmental technology, cultural heritage and fundamental physics. A 5 MW long pulse proton accelerator is used to reach this goal. The pulsed length is 2.86 ms, the repetition frequency is 14 Hz (4 % duty cycle), and the beam current is 62.5 mA. The superconducting section of the Linac accelerates the beam from 80 MeV to 2.0 GeV. It is composed of one string of spoke cavity cryomodule and two strings of elliptical cavity cryomodules. These cryomodules contain four elliptical Niobium cavities operating at 2 K and at a frequency of 704.42 MHz. This paper introduces the thermo-mechanical design, the prototyping and the expected operation of the ESS elliptical cavity cryomodules. An Elliptical Cavity Cryomodule Technology Demonstrator (ECCTD) will be built and tested in order to validate the ESS series production.

  10. Cavity optomechanics and its applications

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Mishkatul

    2009-05-01

    Cavity optomechanics is an emerging field at the intersection of quantum optics, atomic physics, nanoscience and gravitational wave interferometry. It involves cavities (with one or more mechanical degrees of freedom) driven by laser radiation. The ensuing optical control of macroscopic mechanical motion may have implications for precision sensing, coherent control of atoms and molecules, and quantum information processing. Due to recent innovations optomechanical physics has been realized in a variety of experimental systems spanning many orders of magnitude in mass and time-scales. In this talk, I will first introduce the basic paradigm of a laser-driven two mirror cavity used for cooling a vibrational mode. A three-mirror configuration recently implemented using a partially transmissive dielectric membrane in a high finesse cavity will then be discussed, and shown to be superior to the two-mirror design in a number of ways. One implication of the three-mirror configuration is the possibility of scaling optomechanical techniques to multiple oscillators. This topic will be explored by analysing the case of two membranes in a cavity where it will be shown that the collective(center-of-mass and breathing) modes of vibration can be cooled independently, analogous to a chain of trapped ions. Finally, future directions for possible applications to the control of atoms and molecules will be indicated briefly.

  11. Nucleic acid indexing

    DOEpatents

    Guilfoyle, Richard A.; Guo, Zhen

    1999-01-01

    A restriction site indexing method for selectively amplifying any fragment generated by a Class II restriction enzyme includes adaptors specific to fragment ends containing adaptor indexing sequences complementary to fragment indexing sequences near the termini of fragments generated by Class II enzyme cleavage. A method for combinatorial indexing facilitates amplification of restriction fragments whose sequence is not known.

  12. Nucleic acid indexing

    DOEpatents

    Guilfoyle, Richard A.; Guo, Zhen

    2001-01-01

    A restriction site indexing method for selectively amplifying any fragment generated by a Class II restriction enzyme includes adaptors specific to fragment ends containing adaptor indexing sequences complementary to fragment indexing sequences near the termini of fragments generated by Class II enzyme cleavage. A method for combinatorial indexing facilitates amplification of restriction fragments whose sequence is not known.

  13. KSC Construction Cost Index

    NASA Technical Reports Server (NTRS)

    Brown, J. A.

    1983-01-01

    Kennedy Space Center cost Index aids in conceptual design cost estimates. Report discusses development of KSC Cost Index since January 1974. Index since January 1974. Index provides management, design engineers, and estimators an up-to-data reference for local labor and material process. Also provides mount and rate of change in these costs used to predict future construction costs.

  14. Phoxonic crystals and cavity optomechanics

    NASA Astrophysics Data System (ADS)

    Djafari-Rouhani, Bahram; El-Jallal, Said; Pennec, Yan

    2016-05-01

    Phoxonic crystals are dual phononic/photonic crystals exhibiting simultaneously band gaps for both types of excitations. Therefore, they have the ability to confine phonons and photons in the same cavity and in turn allow the enhancement of their interaction. In this paper, we review some of our theoretical works on cavity optomechanical interactions in different types of phoxonic crystals, including two-dimensional, slab, and nanobeam structures. Two mechanisms are behind the phonon-photon interaction, namely the photoelastic and the moving interface effects. Coupling rates of a few MHz are obtained with high-frequency phonons of a few GHz. Finally, we give some preliminary results about the optomechanical interaction when a metallic nanoparticle is introduced into the cavity, giving rise to coupled photon-plasmon modes or, in the case of very small particles, to an enhancement of the electric field at the position of the particle. xml:lang="fr"

  15. RRR Characteristics for SRF cavities

    NASA Astrophysics Data System (ADS)

    Jung, Yoochul; Hyun, Myungook; Joung, Mijoung

    2015-10-01

    The first heavy ion accelerator is being constructed by the rare isotope science project (RISP) launched by the Institute of Basic Science (IBS) in South Korea. Four different types of superconducting cavities were designed, and prototypes such as a quarter-wave resonator (QWR), a half-wave resonator (HWR) and a single-spoke resonator (SSR) were fabricated. One of the critical factors determining the performances of superconducting cavities is the residual resistance ratio (RRR). The RRR values essentially represent how pure niobium is and how fast niobium can transmit heat. In general, the RRR degrades during electron beam welding due to impurity incorporation. Thus, it is important to maintain the RRR above a certain value at which a niobium cavity shows target performance. In this study, RRR degradation related with electron beam welding conditions, for example, the welding power, welding speed, and vacuum level, will be discussed.

  16. Nonlinear negative refraction by difference frequency generation

    NASA Astrophysics Data System (ADS)

    Cao, Jianjun; Shen, Dongyi; Feng, Yaming; Wan, Wenjie

    2016-05-01

    Negative refraction has attracted much interest for its promising capability in imaging applications. Such an effect can be implemented by negative index meta-materials, however, which are usually accompanied by high loss and demanding fabrication processes. Recently, alternative nonlinear approaches like phase conjugation and four wave mixing have shown advantages of low-loss and easy-to-implement, but associated problems like narrow accepting angles can still halt their practical applications. Here, we demonstrate theoretically and experimentally a scheme to realize negative refraction by nonlinear difference frequency generation with wide tunability, where a thin Beta barium borate slice serves as a negative refraction layer bending the input signal beam to the idler beam at a negative angle. Furthermore, we realize optical focusing effect using such nonlinear negative refraction, which may enable many potential applications in imaging science.

  17. Experimental cavity pressure distributions at supersonic speeds

    NASA Technical Reports Server (NTRS)

    Stallings, Robert L., Jr.; Wilcox, Floyd J., Jr.

    1987-01-01

    An investigation was conducted to define pressure distributions for rectangular cavities over a range of free-stream Mach numbers and cavity dimensions. These pressure distributions together with schlieren photographs are used to define the critical values of cavity length-to-depth ratio that separate open type cavity flows from closed type cavity flows. For closed type cavity flow, the shear layer expands over the cavity leading edge and impinges on the cavity floor, whereas for open type cavity flow, the shear layer bridges the cavity. The tests were conducted by using a flat-plate model permitting the cavity length to be remotely varied from 0.5 to 12 in. Cavity depths and widths were varied from 0.5 to 2.5 in. The flat-plate boundary layer approaching the cavity was turbulent and had a thickness of approximately 0.2 in. at the cavity front face for the range of test Mach numbers from 1.5 to 2.86. Presented are a discussion of the results and a complete tabulation of the experimental data.

  18. Synchronization in an optomechanical cavity.

    PubMed

    Shlomi, Keren; Yuvaraj, D; Baskin, Ilya; Suchoi, Oren; Winik, Roni; Buks, Eyal

    2015-03-01

    We study self-excited oscillations (SEO) in an on-fiber optomechanical cavity. Synchronization is observed when the optical power that is injected into the cavity is periodically modulated. A theoretical analysis based on the Fokker-Planck equation evaluates the expected phase space distribution (PSD) of the self-oscillating mechanical resonator. A tomography technique is employed for extracting PSD from the measured reflected optical power. Time-resolved state tomography measurements are performed to study phase diffusion and phase locking of the SEO. The detuning region inside which synchronization occurs is experimentally determined and the results are compared with the theoretical prediction. PMID:25871175

  19. Classical and wave chaos in asymmetric resonant cavities

    NASA Astrophysics Data System (ADS)

    Stone, A. Douglas

    2000-12-01

    Deformed cylindrical and spherical dielectric optical resonators are analyzed from the perspective of non-linear dynamics and quantum chaos theory. In the short-wavelength limit such resonators behave like billiard systems with non-zero escape probability due to refraction. A ray model is introduced to predict the resonance lifetimes and emission patterns from such a cavity. A universal wavelength-independent broadening is predicted and found for large deformations of the cavity, however there are significant wave-chaotic corrections as well. Highly directional emission is predicted from chaotic “whispering gallery” modes for index of refraction less than two. The detailed nature of the emission pattern can be understood from the nature of the phase space flow in the billiard, and a dramatic variation of this pattern with index of refraction is found due to an effect called “dynamical eclipsing”. Semiconductor resonators of this type also show highly directional emission and high output power but from different modes associated with periodic orbits. A semiclassical approach to these modes is briefly reviewed. These asymmetric resonant cavities (ARCs) show promise as components in future integrated optical devices.

  20. CAVITY LIKE COMPLETIONS IN WEAK SANDS PREFERRED UPSTREAM MANAGEMENT PRACTICES

    SciTech Connect

    Ian Palmer; John McLennan

    2004-04-30

    The technology referred to as Cavity Like Completions (CLC) offers a new technique to complete wells in friable and unconsolidated sands. A successfully designed CLC provides significant increases in well PI (performance index) at lower costs than alternative completion techniques. CLC technology is being developed and documented by a partnership of major oil and gas companies through a GPRI (Global Petroleum Research Institute) joint venture. Through the DOE-funded PUMP program, the experiences of the members of the joint venture will be described for other oil and gas producing companies. To date six examples of CLC completions have been investigated by the JV. The project was performed to introduce a new type of completion (or recompletion) technique to the industry that, in many cases, offers a more cost effective method to produce oil and gas from friable reservoirs. The project's scope of work included: (1) Further develop theory, laboratory and field data into a unified model to predict performance of cavity completion; (2) Perform at least one well test for cavity completion (well provided by one of the sponsor companies); (3) Provide summary of geo-mechanical models for PI increase; and (4) Develop guidelines to evaluate success of potential cavity completion. The project tracks the experiences of a joint industry consortium (GPRI No. 17) over a three year period and compiles results of the activities of this group.

  1. Progress on a Be Cavity Design

    SciTech Connect

    Li, D.; Palmer, R.; Stratakis, D.; Virostek, S.; Zisman, Michael S.

    2010-12-24

    Previous RF experiments with normal-conducting cavities have demonstrated that there is a significant degradation in maximum gradient when the cavity is subjected to a strong axial magnetic field. We have developed a model suggesting that a cavity with beryllium walls may perform better than copper cavities. In this paper we outline the issues that led us to propose fabricating a Be-wall cavity. We also discuss a concept for fabricating such a cavity and mention some of the manufacturing issues we expect to face.

  2. Analog detection for cavity lifetime spectroscopy

    DOEpatents

    Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

    2003-01-01

    An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

  3. Analog detection for cavity lifetime spectroscopy

    DOEpatents

    Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

    2001-05-15

    An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

  4. Accuracy of a teleported squeezed coherent-state superposition trapped into a high-Q cavity

    SciTech Connect

    Sales, J. S.; Silva, L. F. da; Almeida, N. G. de

    2011-03-15

    We propose a scheme to teleport a superposition of squeezed coherent states from one mode of a lossy cavity to one mode of a second lossy cavity. Based on current experimental capabilities, we present a calculation of the fidelity demonstrating that accurate quantum teleportation can be achieved for some parameters of the squeezed coherent states superposition. The signature of successful quantum teleportation is present in the negative values of the Wigner function.

  5. Accuracy of a teleported squeezed coherent-state superposition trapped into a high-Q cavity

    NASA Astrophysics Data System (ADS)

    Sales, J. S.; da Silva, L. F.; de Almeida, N. G.

    2011-03-01

    We propose a scheme to teleport a superposition of squeezed coherent states from one mode of a lossy cavity to one mode of a second lossy cavity. Based on current experimental capabilities, we present a calculation of the fidelity demonstrating that accurate quantum teleportation can be achieved for some parameters of the squeezed coherent states superposition. The signature of successful quantum teleportation is present in the negative values of the Wigner function.

  6. CENDI Indexing Workshop

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The CENDI Indexing Workshop held at NASA Headquarters, Two Independence Square, 300 E Street, Washington, DC, on September 21-22, 1994 focused on the following topics: machine aided indexing, indexing quality, an indexing pilot project, the MedIndEx Prototype, Department of Energy/Office of Scientific and Technical Information indexing activities, high-tech coding structures, category indexing schemes, and the Government Information Locator Service. This publication consists mostly of viewgraphs related to the above noted topics. In an appendix is a description of the Government Information Locator Service.

  7. Large-mode enhancement cavities.

    PubMed

    Carstens, Henning; Holzberger, Simon; Kaster, Jan; Weitenberg, Johannes; Pervak, Volodymyr; Apolonski, Alexander; Fill, Ernst; Krausz, Ferenc; Pupeza, Ioachim

    2013-05-01

    In passive enhancement cavities the achievable power level is limited by mirror damage. Here, we address the design of robust optical resonators with large spot sizes on all mirrors, a measure that promises to mitigate this limitation by decreasing both the intensity and the thermal gradient on the mirror surfaces. We introduce a misalignment sensitivity metric to evaluate the robustness of resonator designs. We identify the standard bow-tie resonator operated close to the inner stability edge as the most robust large-mode cavity and implement this cavity with two spherical mirrors with 600 mm radius of curvature, two plane mirrors and a round trip length of 1.2 m, demonstrating a stable power enhancement of near-infrared laser light by a factor of 2000. Beam radii of 5.7 mm × 2.6 mm (sagittal × tangential 1/e(2) intensity radius) on all mirrors are obtained. We propose a simple all-reflective ellipticity compensation scheme. This will enable a significant increase of the attainable power and intensity levels in enhancement cavities. PMID:23670017

  8. Facing rim cavities fluctuation modes

    NASA Astrophysics Data System (ADS)

    Casalino, Damiano; Ribeiro, André F. P.; Fares, Ehab

    2014-06-01

    Cavity modes taking place in the rims of two opposite wheels are investigated through Lattice-Boltzmann CFD simulations. Based on previous observations carried out by the authors during the BANC-II/LAGOON landing gear aeroacoustic study, a resonance mode can take place in the volume between the wheels of a two-wheel landing gear, involving a coupling between shear-layer vortical fluctuations and acoustic modes resulting from the combination of round cavity modes and wheel-to-wheel transversal acoustic modes. As a result, side force fluctuations and tonal noise side radiation take place. A parametric study of the cavity mode properties is carried out in the present work by varying the distance between the wheels. Moreover, the effects due to the presence of the axle are investigated by removing the axle from the two-wheel assembly. The azimuthal properties of the modes are scrutinized by filtering the unsteady flow in narrow bands around the tonal frequencies and investigating the azimuthal structure of the filtered fluctuation modes. Estimation of the tone frequencies with an ad hoc proposed analytical formula confirms the observed modal properties of the filtered unsteady flow solutions. The present study constitutes a primary step in the description of facing rim cavity modes as a possible source of landing gear tonal noise.

  9. Fibre ring cavity semiconductor laser

    SciTech Connect

    Duraev, V P; Medvedev, S V

    2013-10-31

    This paper presents a study of semiconductor lasers having a polarisation maintaining fibre ring cavity. We examine the operating principle and report main characteristics of a semiconductor ring laser, in particular in single- and multiple-frequency regimes, and discuss its application areas. (lasers)

  10. "Grinding" cavities in polyurethane foam

    NASA Technical Reports Server (NTRS)

    Brower, J. R.; Davey, R. E.; Dixon, W. F.; Robb, P. H.; Zebus, P. P.

    1980-01-01

    Grinding tool installed on conventional milling machine cuts precise cavities in foam blocks. Method is well suited for prototype or midsize production runs and can be adapted to computer control for mass production. Method saves time and materials compared to bonding or hot wire techniques.

  11. ADPF spoke cavity cryomodule concept

    SciTech Connect

    Kelley, J. P.; Roybal, P. L.; La Fave, R. P.; Waynert, J. A.; Schrage, D. L.; Schmierer, E. N.; Krawczyk, F. L.; Garnett, R. W.

    2001-01-01

    The Accelerator Driven Test Facility (ADTF) is being developed as a reactor concepts test bed for transmutation of nuclear waste. A 13.3 mA continuous-wave (CW) proton beam will be accelerated to 600 MeV and impinged on a spallation target. The subsequent neutron shower is used to create a nuclear reaction within a subcritical assembly of waste material that reduces the waste half-life from the order of 10{sup 5} years to 10{sup 2} years. Additionally, significant energy is produced that can be used to generate electrical power. The ADTF proton accelerator consists of room-temperature (RT) structures that accelerate the beam to 6.7-MeV and superconducting (SC) elements that boost the beam's energy to 600-MeV. Traditional SC elliptical cavities experience structural difficulties at low energies due to their geometry. Therefore, stiff-structured SC spoke cavities have been adopted for the energy range between 6.7 and 109 MeV. Elliptical cavities are used at the higher energies. This paper describes a multi-spoke-cavity cryomodule concept for ADTF.

  12. Nanobeam cavities for Reconfigurable Photonics

    NASA Astrophysics Data System (ADS)

    Deotare, Parag B.

    We investigate the design, fabrication, and experimental characterization of high quality factor photonic crystal nanobeam cavities, with theoretical quality factors of 1.4 x 107 in silicon, operating at ˜ 1550 nm. By detecting the cross-polarized resonantly scattered light from a normally incident laser beam, we measure a quality factor of nearly 7.5 x 105. We show on-chip integration of the cavities using waveguides and an inverse taper geometry based mode size converters, and also demonstrate tuning of the optical resonance using thermo-optic effect. We also study coupled cavities and show that the single nanobeam cavity modes are coupled into even and odd superposition modes. Using electrostatic force and taking advantage of the highly dispersive nature of the even mode to the nanobeam separation, we demonstrate dynamically reconfigurable optical filters tunable continuously and reversibly over a 9.5 nm wavelength range. The electrostatic force, obtained by applying bias voltages directly to the nanobeams, is used to control the spacing between the nanobeams, which in turn results in tuning of the cavity resonance. The observed tuning trends were confirmed through simulations that modeled the electrostatic actuation as well as the optical resonances in our reconfigurable geometries. Finally we demonstrate reconfiguration of coupled cavities by using optical gradient force induced mechanical actuation. Propagating waveguide modes that exist over wide wavelength range are used to actuate the structures and in that way control the resonance of a localized cavity mode. Using this all-optical approach, more than 18 linewidths of tuning range is demonstrated. Using an on-chip temperature self-referencing method that we developed, we determined that 20% of the total tuning was due to optomechanical reconfiguration and the rest due to thermo-optic effects. By operating the device at frequencies higher than the thermal cut-off, we show high speed operation dominated by

  13. Extinction measurement with open-path cavity ring-down technique of variable cavity length.

    PubMed

    Cui, Hao; Li, Bincheng; Han, Yanling; Wang, Jing; Gao, Chunming; Wang, Yafei

    2016-06-13

    Open-path cavity ring down (OPCRD) technique with variable cavity length was developed to measure optical extinction including scattering and absorption of air in laboratory environment at 635 nm wavelength. By moving the rear cavity mirror of the ring-down cavity to change cavity length, ring-down time with different cavity lengths was experimentally obtained and the dependence of total cavity loss on cavity length was determined. The extinction coefficient of air was determined by the slope of linear dependence of total cavity loss on cavity length. The extinction coefficients of air with different particle concentrations at 635 nm wavelength were measured to be from 10.46 to 84.19 Mm-1 (ppm/m) in a normal laboratory environment. This variable-cavity-length OPCRD technique can be used for absolute extinction measurement and real-time environmental monitoring without closed-path sample cells and background measurements. PMID:27410351

  14. Biosensors based on GaN nanoring optical cavities

    NASA Astrophysics Data System (ADS)

    Kouno, Tetsuya; Takeshima, Hoshi; Kishino, Katsumi; Sakai, Masaru; Hara, Kazuhiko

    2016-05-01

    Biosensors based on GaN nanoring optical cavities were demonstrated using room-temperature photoluminescence measurements. The outer diameter, height, and thickness of the GaN nanorings were approximately 750–800, 900, and 130–180 nm, respectively. The nanorings functioned as whispering-gallery-mode (WGM)-type optical cavities and exhibited sharp resonant peaks like lasing actions. The evanescent component of the WGM was strongly affected by the refractive index of the ambient environment, the type of liquid, and the sucrose concentration of the analyzed solution, resulting in shifts of the resonant wavelengths. The results indicate that the GaN nanorings can potentially be used in sugar sensors of the biosensors.

  15. Optical cavity furnace for semiconductor wafer processing

    DOEpatents

    Sopori, Bhushan L.

    2014-08-05

    An optical cavity furnace 10 having multiple optical energy sources 12 associated with an optical cavity 18 of the furnace. The multiple optical energy sources 12 may be lamps or other devices suitable for producing an appropriate level of optical energy. The optical cavity furnace 10 may also include one or more reflectors 14 and one or more walls 16 associated with the optical energy sources 12 such that the reflectors 14 and walls 16 define the optical cavity 18. The walls 16 may have any desired configuration or shape to enhance operation of the furnace as an optical cavity 18. The optical energy sources 12 may be positioned at any location with respect to the reflectors 14 and walls defining the optical cavity. The optical cavity furnace 10 may further include a semiconductor wafer transport system 22 for transporting one or more semiconductor wafers 20 through the optical cavity.

  16. 21 CFR 872.3260 - Cavity varnish.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DENTAL DEVICES Prosthetic Devices § 872.3260 Cavity varnish. (a) Identification. Cavity varnish is a... restorative materials. The device is intended to prevent penetration of restorative materials, such as...

  17. Body mass index

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/007196.htm Body mass index To use the sharing features on this ... your height is to figure out your body mass index (BMI). You and your health care provider ...

  18. Body Mass Index Table

    MedlinePlus

    ... Families ( We Can! ) Health Professional Resources Body Mass Index Table 1 for BMI greater than 35, go ... to content Twitter Facebook YouTube Google+ SEARCH | SITE INDEX | ACCESSIBILITY | PRIVACY STATEMENT | FOIA | OIG | CONTACT US National ...

  19. Negative-ion states

    SciTech Connect

    Compton, R.N.

    1982-01-01

    In this brief review, we discuss some of the properties of atomic and molecular negative ions and their excited states. Experiments involving photon reactions with negative ions and polar dissociation are summarized. 116 references, 14 figures.

  20. Negative Pressure Wound Therapy

    PubMed Central

    2006-01-01

    traditional or conventional therapy in the literature, although they typically are not the first line of treatment in Ontario. Modern moist interactive dressings are foams, calcium alginates, hydrogels, hydrocolloids, and films. Topical antibacterial agents—antiseptics, topical antibiotics, and newer antimicrobial dressings—are used to treat infection. The Technology Being Reviewed Negative pressure wound therapy is not a new concept in wound therapy. It is also called subatmospheric pressure therapy, vacuum sealing, vacuum pack therapy, and sealing aspirative therapy. The aim of the procedure is to use negative pressure to create suction, which drains the wound of exudate (i.e., fluid, cells, and cellular waste that has escaped from blood vessels and seeped into tissue) and influences the shape and growth of the surface tissues in a way that helps healing. During the procedure, a piece of foam is placed over the wound, and a drain tube is placed over the foam. A large piece of transparent tape is placed over the whole area, including the healthy tissue, to secure the foam and drain the wound. The tube is connected to a vacuum source, and fluid is drawn from the wound through the foam into a disposable canister. Thus, the entire wound area is subjected to negative pressure. The device can be programmed to provide varying degrees of pressure either continuously or intermittently. It has an alarm to alert the provider or patient if the pressure seal breaks or the canister is full. Negative pressure wound therapy may be used for patients with chronic and acute wounds; subacute wounds (dehisced incisions); chronic, diabetic wounds or pressure ulcers; meshed grafts (before and after); or flaps. It should not be used for patients with fistulae to organs/body cavities, necrotic tissue that has not been debrided, untreated osteomyelitis, wound malignancy, wounds that require hemostasis, or for patients who are taking anticoagulants. Review Strategy The inclusion criteria were as

  1. Understanding cavity resonances with intracavity dispersion properties

    SciTech Connect

    Sheng Jiteng; Wu Haibin; Mumba, M.; Gea-Banacloche, J.; Xiao Min

    2011-02-15

    We experimentally study the strongly coupled three-level atom-cavity system at both cavity and coupling frequency detuning cases. Side peak splitting and anti-crossing-like phenomena are observed under different experimental conditions. Intracavity dispersion properties are used to explain qualitatively the complicated cavity resonance structures in the composite system of inhomogeneously broadened three-level atoms inside an optical ring cavity with relatively strong driving intensities.

  2. Negative ion generator

    DOEpatents

    Stinnett, R.W.

    1984-05-08

    A negative ion generator is formed from a magnetically insulated transmission line having a coating of graphite on the cathode for producing negative ions and a plurality of apertures on the opposed anode for the release of negative ions. Magnetic insulation keeps electrons from flowing from the cathode to the anode. A transverse magnetic field removes electrons which do escape through the apertures from the trajectory of the negative ions. 8 figs.

  3. Negative ion generator

    DOEpatents

    Stinnett, Regan W.

    1984-01-01

    A negative ion generator is formed from a magnetically insulated transmission line having a coating of graphite on the cathode for producing negative ions and a plurality of apertures on the opposed anode for the release of negative ions. Magnetic insulation keeps electrons from flowing from the cathode to the anode. A transverse magnetic field removes electrons which do escape through the apertures from the trajectory of the negative ions.

  4. [Negative symptoms: which antipsychotics?].

    PubMed

    Maurel, M; Belzeaux, R; Adida, M; Azorin, J-M

    2015-12-01

    Treating negative symptoms of schizophrenia is a major issue and a challenge for the functional and social prognosis of the disease, to which they are closely linked. First- and second-generation antipsychotics allow a reduction of all negative symptoms. The hope of acting directly on primary negative symptoms with any antipsychotic is not supported by the literature. However, the effectiveness of first- and second-generation antipsychotics is demonstrated on secondary negative symptoms. PMID:26776390

  5. Slow light in dual-periodic photonic crystals based slotted-waveguide coupled cavity

    NASA Astrophysics Data System (ADS)

    Zhu, Na; Li, Yuanyuan; Chen, Cheng; Yan, Shu

    2016-09-01

    Considering the capacity of the nanoscale width area with the low-refractive index can confine light waves, the dual-periodic slotted photonic crystals, which is constructed by coupling low-refractive index's slotted-waveguide with high-refractive index's cavity is proposed in this paper. The best slow light properties and the optimal slotted-waveguide coupled cavity are achieved by adjusting the slotted-width and the period of cavity respectively. In this structure, the slow-light properties are simulated by Plane Wave Expansion (PWE), the result reveals that the group velocities are all three orders of magnitude smaller than the speed of light in vacuum, the slowest value is 7.96 ×10-4 c when the slotted-width is 0.54a and the period of cavity is 0.95a. Moreover, the corresponding Normalized Delay-Bandwidth Product (NDBP) values are larger than 0.24. Besides, the slotted-waveguide coupled cavity can be reconfigured, which accordingly changes the corresponding slow-light property. At last, the numerical results provide a new thought and method for decreasing group velocity and potential application for optical buffer in photonic crystals field.

  6. California Nitrogen Index

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The California N Index User Manual is designed to help you become accustomed to the software environment in which the N Index runs. This manual will use an example scenario to demonstrate how to use the N Index to assess nitrogen losses. The objective of this theoretical example is to guide you towa...

  7. The Europe 2020 Index

    ERIC Educational Resources Information Center

    Pasimeni, Paolo

    2013-01-01

    This paper presents a new index to quantify, measure and monitor the progress towards the objectives of the Europe 2020 strategy. This index is based on a set of relevant, accepted, credible, easy to monitor and robust indicators presented by the European Commission at the time the strategy was launched. The internal analysis of the index shows…

  8. Negative-Refraction Metamaterials: Fundamental Principles and Applications

    NASA Astrophysics Data System (ADS)

    Eleftheriades, G. V.; Balmain, K. G.

    2005-06-01

    Learn about the revolutionary new technology of negative-refraction metamaterials Negative-Refraction Metamaterials: Fundamental Principles and Applications introduces artificial materials that support the unusual electromagnetic property of negative refraction. Readers will discover several classes of negative-refraction materials along with their exciting, groundbreaking applications, such as lenses and antennas, imaging with super-resolution, microwave devices, dispersion-compensating interconnects, radar, and defense. The book begins with a chapter describing the fundamentals of isotropic metamaterials in which a negative index of refraction is defined. In the following chapters, the text builds on the fundamentals by describing a range of useful microwave devices and antennas. Next, a broad spectrum of exciting new research and emerging applications is examined, including: Theory and experiments behind a super-resolving, negative-refractive-index transmission-line lens 3-D transmission-line metamaterials with a negative refractive index Numerical simulation studies of negative refraction of Gaussian beams and associated focusing phenomena Unique advantages and theory of shaped lenses made of negative-refractive-index metamaterials A new type of transmission-line metamaterial that is anisotropic and supports the formation of sharp steerable beams (resonance cones) Implementations of negative-refraction metamaterials at optical frequencies Unusual propagation phenomena in metallic waveguides partially filled with negative-refractive-index metamaterials Metamaterials in which the refractive index and the underlying group velocity are both negative This work brings together the best minds in this cutting-edge field. It is fascinating reading for scientists, engineers, and graduate-level students in physics, chemistry, materials science, photonics, and electrical engineering.

  9. Sentential Negation in English

    ERIC Educational Resources Information Center

    Mowarin, Macaulay

    2009-01-01

    This paper undertakes a detailed analysis of sentential negation in the English language with Chomsky's Government-Binding theory of Transformational Grammar as theoretical model. It distinguishes between constituent and sentential negation in English. The essay identifies the exact position of Negation phrase in an English clause structure. It…

  10. The Investigation of Angular Effects of Laser Polarization on the Photodetachment of H‑ near a Spherical Cavity

    NASA Astrophysics Data System (ADS)

    Haneef, Muhammad; Fakhr-E-Alam; Bakhtawar; Akbar, Jehan

    2016-05-01

    Angular effects of the laser polarization on the photodetachment of H‑ near a spherical cavity is investigated. The photodetachment cross section of this system has been derived and calculated based on theoretical imaging method. The laser polarization angle θL has significant effect on the photodetachment cross section of H‑ near spherical cavity. In addition, for a given spherical cavity, the peaks in the cross-section shift with the increase in rc. Hence, we can control the photodetachment of H‑ near a spherical cavity by changing the laser polarization angle and radius of the spherical cavity. This study gives new understanding on the photodetachment process of negative ions in the presence of spherical cavities or surfaces.

  11. Power coupler for the ILC crab cavity

    SciTech Connect

    Burt, G.; Dexter, A.; Jenkins, R.; Beard, C.; Goudket, P.; McIntosh, P.A.; Bellantoni, Leo; /Fermilab

    2007-06-01

    The ILC crab cavity will require the design of an appropriate power coupler. The beam-loading in dipole mode cavities is considerably more variable than accelerating cavities, hence simulations have been performed to establish the required external Q. Simulations of a suitable coupler were then performed and were verified using a normal conducting prototype with variable coupler tips.

  12. Computer codes for RF cavity design

    SciTech Connect

    Ko, K.

    1992-08-01

    In RF cavity design, numerical modeling is assuming an increasingly important role with the help of sophisticated computer codes and powerful yet affordable computers. A description of the cavity codes in use in the accelerator community has been given previously. The present paper will address the latest developments and discuss their applications to cavity toning and matching problems.

  13. The nasal cavity microbiota of healthy adults

    PubMed Central

    2014-01-01

    Background The microbiota of the nares has been widely studied. However, relatively few studies have investigated the microbiota of the nasal cavity posterior to the nares. This distinct environment has the potential to contain a distinct microbiota and play an important role in health. Results We obtained 35,142 high-quality bacterial 16S rRNA-encoding gene sequence reads from the nasal cavity and oral cavity (the dorsum of the tongue and the buccal mucosa) of 12 healthy adult humans and deposited these data in the Sequence Read Archive (SRA) of the National Center for Biotechnology Information (NCBI) (Bioproject: PRJNA248297). In our initial analysis, we compared the bacterial communities of the nasal cavity and the oral cavity from ten of these subjects. The nasal cavity bacterial communities were dominated by Actinobacteria, Firmicutes, and Proteobacteria and were statistically distinct from those on the tongue and buccal mucosa. For example, the same Staphylococcaceae operational taxonomic unit (OTU) was present in all of the nasal cavity samples, comprising up to 55% of the community, but Staphylococcaceae was comparatively uncommon in the oral cavity. Conclusions There are clear differences between nasal cavity microbiota and oral cavity microbiota in healthy adults. This study expands our knowledge of the nasal cavity microbiota and the relationship between the microbiota of the nasal and oral cavities. PMID:25143824

  14. 21 CFR 872.3260 - Cavity varnish.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cavity varnish. 872.3260 Section 872.3260 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3260 Cavity varnish. (a) Identification. Cavity varnish is...

  15. 21 CFR 872.3260 - Cavity varnish.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cavity varnish. 872.3260 Section 872.3260 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3260 Cavity varnish. (a) Identification. Cavity varnish is...

  16. 21 CFR 872.3260 - Cavity varnish.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cavity varnish. 872.3260 Section 872.3260 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3260 Cavity varnish. (a) Identification. Cavity varnish is...

  17. 21 CFR 872.3260 - Cavity varnish.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Cavity varnish. 872.3260 Section 872.3260 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3260 Cavity varnish. (a) Identification. Cavity varnish is...

  18. Non-reacting flow visualization of supersonic combustor based on cavity and cavity-strut flameholder

    NASA Astrophysics Data System (ADS)

    Zhao, Yanhui; Liang, Jianhan; Zhao, Yuxin

    2016-04-01

    Nano-particle planer laser scattering and particle image velocimetry technology are employed to observe the flow field of scramjet combustors based on cavity and cavity-strut flameholder. Density field and velocity distribution inside combustors are obtained. Mainstream fluid enters into cavity nearby side wall in experimental observation because side wall shock waves interact with bottom wall boundary layer. Cavity fluid is entrained into mainstream in the middle of combustor meanwhile. Flow past cavity displays obvious three dimensional characteristics in both combustors. But cavity-strut combustor displays asymmetrical flow field because of strut configuration. Mass exchange between mainstream and cavity fluid is evaluated by statistic mass flow rate into cavity. Mass flow rate near side wall is raised to 6.62 times of the value in the middle of cavity combustor while it is 5.1 times in cavity-strut combustor. Further study is needed to injection strategies and realistic flow characteristics on condition of combustion.

  19. Status of the ILC Crab Cavity Development

    SciTech Connect

    Burt, G.; Dexter, A.; Beard, C.; Goudket, P.; McIntosh, P.; Bellantoni, L.; Grimm, T.; Li, Z.; Xiao, L.; /SLAC

    2011-10-20

    The International Linear Collider (ILC) will require two dipole cavities to 'crab' the electron and positron bunches prior to their collision. It is proposed to use two 9 cell SCRF dipole cavities operating at a frequency of 3.9 GHz, with a transverse gradient of 3.8MV/m in order to provide the required transverse kick. Extensive numerical modelling of this cavity and its couplers has been performed. Aluminium prototypes have been manufactured and tested to measure the RF properties of the cavity and couplers. In addition single cell niobium prototypes have been manufactured and tested in a vertical cryostat. The International Collider (ILC) [1] collides bunches of electrons and positrons at a crossing angle of 14 mrad. The angle between these bunches causes a loss in luminosity due to geometric effects [2]. The luminosity lost from this geometric effect can be recovered by rotating the bunches into alignment prior to collision. One possible method of rotating the bunches is to use a crab cavity [3]. A crab cavity is a transverse defecting cavity, where the phase of the cavity is such that the head and tail of the bunch receive equal and opposite kicks. As the bunches are only 500 nm wide in the horizontal plane, the cavity phase must be strictly controlled to avoid the bunch centre being deflected too much. In order to keep the phase stability within the required limits it is required that the cavity be superconducting to avoid thermal effects in both the cavity and its RF source. At the location of the crab cavity in the ILC there is only 23 cm separation between the centre of the cavity and the extraction line, hence the cavity must be small enough to fit in this space. This, along with the difficulty of making high frequency SRF components, set the frequency of the cavity to 3.9 GHz.

  20. A micropillar for cavity optomechanics

    NASA Astrophysics Data System (ADS)

    Kuhn, Aurélien; Neuhaus, Leonhard; Van Brackel, Emmanuel; Chartier, Claude; Ducloux, Olivier; Le Traon, Olivier; Michel, Christophe; Pinard, Laurent; Flaminio, Raffaele; Deléglise, Samuel; Briant, Tristan; Cohadon, Pierre-François; Heidmann, Antoine

    2014-12-01

    Demonstrating the quantum ground state of a macroscopic mechanical object is a major experimental challenge in physics, at the origin of the rapid emergence of cavity optomechanics. We have developed a new generation of optomechanical devices, based on a microgram quartz micropillar with a very high mechanical quality factor. The structure is used as end mirror in a Fabry-Perot cavity with a high optical finesse, leading to ultra-sensitive interferometric measurement of the resonator displacement. We expect to reach the ground state of this optomechanical resonator by combining cryogenic cooling in a dilution fridge at 30 mK and radiation-pressure cooling. We have already carried out a quantum-limited measurement of the micropillar thermal noise at low temperature.

  1. A micropillar for cavity optomechanics

    SciTech Connect

    Kuhn, Aurélien; Neuhaus, Leonhard; Deléglise, Samuel; Briant, Tristan; Cohadon, Pierre-François; Heidmann, Antoine; Van Brackel, Emmanuel; Chartier, Claude; Ducloux, Olivier; Le Traon, Olivier; Michel, Christophe; Pinard, Laurent; Flaminio, Raffaele

    2014-12-04

    Demonstrating the quantum ground state of a macroscopic mechanical object is a major experimental challenge in physics, at the origin of the rapid emergence of cavity optomechanics. We have developed a new generation of optomechanical devices, based on a microgram quartz micropillar with a very high mechanical quality factor. The structure is used as end mirror in a Fabry-Perot cavity with a high optical finesse, leading to ultra-sensitive interferometric measurement of the resonator displacement. We expect to reach the ground state of this optomechanical resonator by combining cryogenic cooling in a dilution fridge at 30 mK and radiation-pressure cooling. We have already carried out a quantum-limited measurement of the micropillar thermal noise at low temperature.

  2. RF cavity vacuum interlock system

    NASA Astrophysics Data System (ADS)

    Jordan, K.; Crawford, K.; Bundy, R.; Dylla, H. F.; Heckman, J.; Marshall, J.; Nichols, R.; Osullivan, S.; Preble, J.; Robb, J.

    1992-03-01

    The Continuous Electron Beam Accelerator Facility (CEBAF), a continuous wave (CW) 4 GeV Electron Accelerator is undergoing construction in Newport News, Virginia. When completed in 1994, the accelerator will be the largest installation of radio-frequency superconductivity. Production of cryomodules, the fundamental building block of the machine, has started. A cryomodule consists of four sets of pairs of 1497 MHz, 5 cell niobium cavities contained in separate helium vessels and mounted in a cryostat with appropriate end caps for helium supply and return. Beam vacuum of the cavities, the connecting beam piping, the waveguides, and the cryostat insulating vacuum are crucial to the performance of the machine. The design and initial experience of the vacuum systems for the first 2 1/4 cryomodules that makeup the 45 MEV injector are discussed.

  3. Extrinsic fiber-optic Fabry-Perot interferometer sensor for refractive index measurement of optical glass

    SciTech Connect

    Chen Jihuan; Zhao Jiarong; Huang Xuguang; Huang Zhenjian

    2010-10-10

    A simple fiber-optic sensor based on Fabry-Perot interference for refractive index measurement of optical glass is investigated both theoretically and experimentally. A broadband light source is coupled into an extrinsic fiber Fabry-Perot cavity formed by the surfaces of a sensing fiber end and the measured sample. The interference signals from the cavity are reflected back into the same fiber. The refractive index of the sample can be obtained by measuring the contrast of the interference fringes. The experimental data meet with the theoretical values very well. The proposed technique is a new method for glass refractive index measurement with a simple, solid, and compact structure.

  4. Grinding Inside A Toroidal Cavity

    NASA Technical Reports Server (NTRS)

    Mayer, Walter; Adams, James F.; Burley, Richard K.

    1987-01-01

    Weld lines ground smooth within about 0.001 in. Grinding tool for smoothing longitudinal weld lines inside toroidal cavity includes curved tunnel jig to guide grinding "mouse" along weld line. Curvature of tunnel jig matched to shape of toroid so grinding ball in mouse follows circular arc of correct radius as mouse is pushed along tunnel. Tool enables precise control of grindout shape, yet easy to use.

  5. [Estimation of antimicrobial means action efficacy in children oral cavities by pH-test].

    PubMed

    Guliamov, S S

    2009-01-01

    Possibility of mixed saliva pH determination in the efficacy of antimicrobial mean action was assessed using fluctuations in hydrogen index (pH following consumption of sweets in teenagers according to Stephan curve). Antimicrobial activity of chlorhexidine-containing preparation Eludrile and Elgidium-tooth paste, as well as furacillin solution in oral cavities of teenagers was estimated. PMID:19365352

  6. Role of geometry in optothermal response of toroidal ultra-high-Q cavities

    NASA Astrophysics Data System (ADS)

    Soltani, Soheil; Armani, Andrea M.

    2015-03-01

    Ultra-high quality factor (UHQ) resonant cavities are able to store light for long periods of time, resulting in high circulating intensities. As a result, numerous nonlinear optical phenomena appear, such as radiation pressure oscillations and lasing. However, deleterious behaviors also occur, such as optothermal broadening of the resonant linewidth. The degree of distortion is directly related to the circulating power in the cavity, the material absorption, and the thermo-optic coefficient of the cavity material. Specifically, a portion of the circulating power is absorbed by the material and converted to heat. This thermal energy is able to induce a refractive index change in the cavity which is experimentally observed as a resonant wavelength change. This behavior has been observed in numerous cavities, but one interesting case is the toroidal cavity, as it has a particularly complex geometry providing multiple thermal transport pathways. To accurately capture this complex behavior, we have developed a COMSOL Multiphysics model which combines the thermal and optical components. The model uses the non-uniform optical mode profile as the heat source. As such, changes in device geometry and wavelength are inherently captured. To verify the modeling, we characterize the optothermal threshold for a series of toroidal cavities across a range of wavelengths and device geometries. Additionally, the thermal time constant of the structure is explored. Of note, the membrane thickness is shown to play a critical role in the optothermal behaviors.

  7. Modeling of optically controlled reflective bistability in a vertical cavity semiconductor saturable absorber

    NASA Astrophysics Data System (ADS)

    Mishra, L.

    2015-05-01

    Bistability switching between two optical signals has been studied theoretically utilizing the concept of cross absorption modulation in a vertical cavity semiconductor saturable absorber (VCSSA). The probe beam is fixed at a wavelength other than the low power cavity resonance wavelength, which exhibits bistable characteristic by controlling the power of a pump beam (λpump≠λprobe). The cavity nonlinear effects that arises simultaneously from the excitonic absorption bleaching, and the carrier induced nonlinear index change has been considered in the model. The high power absorption in the active region introduces thermal effects within the nonlinear cavity due to which the effective cavity length changes. This leads to a red-shift of the cavity resonance wavelength, which results a change in phase of the optical fields within the cavity. In the simulation, the phase-change due to this resonance shifting is considered to be constant over time, and it assumes the value corresponding to the maximum input power. Further, an initial phase detuning of the probe beam has been considered to investigate its effect on switching. It is observed from the simulated results that, the output of the probe beam exhibits either clockwise or counter-clockwise bistability, depending on its initial phase detuning.

  8. Microwave energy storage in resonant cavities

    SciTech Connect

    Alvarez, R.A.

    1983-02-01

    One method of generating short, high-power microwave pulses is to store rf energy in a resonant cavity over a relatively long fill time and extract is rapidly. A power gain roughly equal to the ratio of fill time to extraction time can be obtained. During the filling of a resonant cavity some of the energy is lost in heating the cavity walls, and some will generally be reflected at the input coupling of the cavity. In this paper we discuss the time dependence of the stored energy and related quantities and the way in which it depends on the coupling of the source to the cavity.

  9. Controlled directional scattering cavity for tubular absorbers

    DOEpatents

    Winston, Roland

    1982-01-01

    A specular cavity is provided in which an optical receiver is emplaced. The cavity is provided with a series of V groove-like indentations (or pyramidal-type indentations) which redirect energy entering between the receiver and cavity structure onto the receiver. The aperture opening of each V groove is less than half the cavity opening and in most preferred embodiments, much less than half. This enables the optical receiver to be emplaced a distance g from the cavity wherein 0.414r

  10. LHC crab-cavity aspects and strategy

    SciTech Connect

    Calaga, R.; Tomas, R.; Zimmermann, F.

    2010-05-23

    The 3rd LHC Crab Cavity workshop (LHC-CC09) took place at CERN in October 2009. It reviewed the current status and identified a clear strategy towards a future crab-cavity implementation. Following the success of crab cavities in KEK-B and the strong potential for luminosity gain and leveling, CERN will pursue crab crossing for the LHC upgrade. We present a summary and outcome of the variousworkshop sessions which have led to the LHC crab-cavity strategy, covering topics like layout, cavity design, integration, machine protection, and a potential validation test in the SPS.

  11. Vented Cavity Radiant Barrier Assembly And Method

    DOEpatents

    Dinwoodie, Thomas L.; Jackaway, Adam D.

    2000-05-16

    A vented cavity radiant barrier assembly (2) includes a barrier (12), typically a PV module, having inner and outer surfaces (18, 22). A support assembly (14) is secured to the barrier and extends inwardly from the inner surface of the barrier to a building surface (14) creating a vented cavity (24) between the building surface and the barrier inner surface. A low emissivity element (20) is mounted at or between the building surface and the barrier inner surface. At least part of the cavity exit (30) is higher than the cavity entrance (28) to promote cooling air flow through the cavity.

  12. Cavity lining in primary teeth.

    PubMed

    Chauhan, Ravi

    2016-03-01

    Data sourcesEmbase, Medline, Cochrane Central, Biomed Central and Open Grey databases and bibliographies of identified studies.Study selectionRandomised controlled trials investigating humans with primary caries lesions receiving operative treatment involving caries removal and restoration, with minimum two treatment groups comparing different cavity treatments before restoration (no lining versus lining) were included.Data extraction and synthesisData were extracted independently by two reviewers and study quality assessed using the Cochrane risk of bias tool. Random effect meta-analysis was carried out.ResultsThree studies involving a total of 89 patients were included. All the studies involved primary teeth and were conducted in Brazil. Follow-up periods ranged from 26-53 months. All the studies were considered to be at high risk of bias. Restoring the cavity without lining did not significantly affect the risk of failure. The quality of the evidence was low.ConclusionsCurrent evidence does not support strong recommendations to use or not to use liners after caries removal and before restoring cavities. Our findings are restricted to primary teeth after selective excavation, with only one liner (calcium hydroxide) being used for comparison. PMID:27012571

  13. Optomechanic interactions in phoxonic cavities

    SciTech Connect

    Djafari-Rouhani, Bahram; Oudich, Mourad; Pennec, Yan; El-Jallal, Said

    2014-12-15

    Phoxonic crystals are periodic structures exhibiting simultaneous phononic and photonic band gaps, thus allowing the confinement of both excitations in the same cavity. The phonon-photon interaction can be enhanced due to the overlap of both waves in the cavity. In this paper, we discuss some of our recent theoretical works on the strength of the optomechanic coupling, based on both photoelastic and moving interfaces mechanisms, in different (2D, slabs, strips) phoxonic crystals cavities. The cases of two-dimensional infinite and slab structures will enable us to mention the important role of the symmetry and degeneracy of the modes, as well as the role of the materials whose photoelastic constants can be wavelength dependent. Depending on the phonon-photon pair, the photoelastic and moving interface mechanisms can contribute in phase or out-of-phase. Then, the main part of the paper will be devoted to the optomechanic interaction in a corrugated nanobeam waveguide exhibiting dual phononic/photonic band gaps. Such structures can provide photonic modes with very high quality factor, high frequency phononic modes of a few GHz inside a gap and optomechanical coupling rate reaching a few MHz.

  14. Angioleiomyoma of the Nasal Cavity

    PubMed Central

    Arruda, Milena Moreira; Monteiro, Daniela Yasbek; Fernandes, Atilio Maximino; Menegatti, Vanessa; Thomazzi, Emerson; Hubner, Ricardo Arthur; Lima, Luiz Guilherme Cernaglia Aureliano de

    2014-01-01

    Introduction Vascular leiomyoma of the nasal cavity is an extremely rare tumor that represents less than 1% of all vascular leiomyomas. It is more prevalent in women between the fourth and sixth decades, reaching primarily the inferior nasal turbinates. Objectives Reporting and assisting the systematization of more accurate diagnostic methods in clinical and complementary investigation of vascular leiomyoma in the nasal cavity. Resumed Report We present the case of a 49-year-old woman diagnosed with vascular leiomyoma in the nasal cavity, which manifested mainly with nasal obstruction. During investigation, computer tomography was not diagnostic, the cytologic study was not conclusive, and according to the biopsy, it was a squamous papilloma. Conclusion We suggest that the technical difficulty in obtaining an adequate amount of material for preoperative biopsy, associated with the topography of the lesion in the vestibular nasal region, may have contributed to changing the postoperative diagnosis. Thus, pathologic study of the surgical fragment is the more accurate method for diagnosis. PMID:25992133

  15. Filling cavities or restoring teeth?

    PubMed

    Versluis, Antheunis; Versluis-Tantbirojn, Daranee

    2011-01-01

    Teeth seldom fracture under normal functional loading. This indicates that the natural tooth design is optimized for the distribution of regular masticatory forces by means of its properties and structure. When a tooth is restored with an intracoronal restoration, however, the incidence of tooth fracture increases. Since remaining tissues do not change, the restorative actions apparently alter the original stress distributions. In this study, the effect of different restoration types (unbonded amalgam and bonded composite restorations) were compared with the original stress conditions of the intact tooth, using finite element analysis. It was shown that an unbonded amalgam restoration did not restore the original stress conditions but led to much higher stresses in the buccal and lingual enamel and to higher tensile stresses in the cavity floor. The unbonded amalgam thus filled the cavity but did not restore the tooth. In contrast, a bonded composite restoration restored the original stress pattern in the tooth if there was no polymerization shrinkage. Polymerization shrinkage causes residual tensile stresses in the dentin around the cavity and in the buccal and lingual enamel. Residual tensile stresses in the buccal and lingual enamel are momentary compensated by compressive stress components during occlusal loading. It was concluded that bonding and elimination of residual stresses are prerequisites for restoring the original tooth integrity. PMID:21748978

  16. External cavity diode laser with very-low frequency drift

    NASA Astrophysics Data System (ADS)

    Takamizawa, Akifumi; Yanagimachi, Shinya; Ikegami, Takeshi

    2016-03-01

    An external cavity diode laser with significant mechanical robustness was installed in a housing that was sealed from outside for eliminating variations in the refractive index of air. Using the feedback signal for a frequency lock, it was found that the variation in the laser frequency under free running was suppressed to 275 MHz over one month and depended on the room temperature. Moreover, the upper limit of the linear frequency drift rate was evaluated as intrinsically 40 Hz/s. The frequency lock is expected to be sustainable for more than 110 days with temperature-controlled housing.

  17. Topological polaritons in a quantum spin Hall cavity

    NASA Astrophysics Data System (ADS)

    Janot, Alexander; Rosenow, Bernd; Refael, Gil

    2016-04-01

    We study the topological structure of matter-light excitations, so-called polaritons, in a quantum spin Hall insulator coupled to photonic cavity modes. We identify a topological invariant in the presence of time reversal (TR) symmetry, and demonstrate the existence of a TR-invariant topological phase. We find protected helical edge states with energies below the lower polariton branch and characteristic uncoupled excitonic states, both detectable by optical techniques. Applying a Zeeman field allows us to relate the topological index to the double coverage of the Bloch sphere by the polaritonic pseudospin.

  18. Novel Geometries for the LHC Crab Cavity

    SciTech Connect

    Hall, B.; Burt, G.; Smith, J. D.A.; Rimmer, R.; Wang, H.; Delayen, J.; Calaga, R.

    2009-05-01

    In 2017 the LHC is envisioned to increase its luminosity via an upgrade. This upgrade is likely to require a large crossing angle hence a crab cavity is required to align the bunches prior to collision. There are two possible schemes for crab cavity implementation, global and local. In a global crab cavity the crab cavity is far from the IP and the bunch rotates back and forward as it traverses around the accelerator in a closed orbit. For this scheme a two-cell elliptical squashed cavity at 800 MHz is preferred. To avoid any potential beam instabilities all the parasitic modes of the cavities must be damped strongly, however crab cavities have lower order and same order modes in addition to the usual higher order modes and hence a novel damping scheme must be used to provide sufficient damping of these modes. In the local scheme two crab cavities are placed at each side of the IP two start and stop rotation of the bunches. This would require crab cavities much smaller transversely than in the global scheme but the frequency cannot be increased any higher due to the long bunch length of the LHC beam. This will require a novel compact crab cavity design. A superconducting version of a two rod coaxial deflecting cavity as a suitable design is proposed in this paper.

  19. Control of Cavity Resonance Using Oscillatory Blowing

    NASA Technical Reports Server (NTRS)

    Scarfe, Alison Lamp; Chokani, Ndaona

    2000-01-01

    The near-zero net mass oscillatory blowing control of a subsonic cavity flow has been experimentally investigated. An actuator was designed and fabricated to provide both steady and oscillatory blowing over a range of blowing amplitudes and forcing frequencies. The blowing was applied just upstream of the cavity front Wall through interchangeable plate configurations These configurations enabled the effects of hole size, hole shape, and blowing angle to be examined. A significant finding is that in terms of the blowing amplitude, the near zero net mass oscillatory blowing is much more effective than steady blowing; momentum coefficients Lip two orders of magnitude smaller than those required for steady blowing are sufficient to accomplish the same control of cavity resonance. The detailed measurements obtained in the experiment include fluctuating pressure data within the cavity wall, and hot-wire measurements of the cavity shear layer. Spectral and wavelet analysis techniques are applied to understand the dynamics and mechanisms of the cavity flow with control. The oscillatory blowing, is effective in enhancing the mixing in the cavity shear layer and thus modifying the feedback loop associated with the cavity resonance. The nonlinear interactions in the cavity flow are no longer driven by the resonant cavity modes but by the forcing associated with the oscillatory blowing. The oscillatory blowing does not suppress the mode switching behavior of the cavity flow, but the amplitude modulation is reduced.

  20. Novel Geometries for the LHC Crab Cavity

    SciTech Connect

    B. Hall,G. Burt,C. Lingwood,Robert Rimmer,Haipeng Wang; Hall, B.; Burt, G.; Lingwood, C.; Rimmer, Robert; Wang, Haipeng

    2010-05-01

    The planned luminosity upgrade to LHC is likely to necessitate a large crossing angle and a local crab crossing scheme. For this scheme crab cavities align bunches prior to collision. The scheme requires at least four such cavities, a pair on each beam line either side of the interaction point (IP). Upstream cavities initiate rotation and downstream cavities cancel rotation. Cancellation is usually done at a location where the optics has re-aligned the bunch. The beam line separation near the IP necessitates a more compact design than is possible with elliptical cavities such as those used at KEK. The reduction in size must be achieved without an increase in the operational frequency to maintain compatibility with the long bunch length of the LHC. This paper proposes a suitable superconducting variant of a four rod coaxial deflecting cavity (to be phased as a crab cavity), and presents analytical models and simulations of suitable designs.

  1. Highly stable piezoelectrically tunable optical cavities

    NASA Astrophysics Data System (ADS)

    Möhle, Katharina; Kovalchuk, Evgeny V.; Döringshoff, Klaus; Nagel, Moritz; Peters, Achim

    2013-05-01

    We have implemented highly stable and tunable frequency references using optical high finesse cavities which incorporate a piezo actuator. As piezo material we used ceramic PZT, crystalline quartz, or PZN-PT single crystals. Lasers locked to these cavities show a relative frequency stability better than 1× 10^{-14}, which is most likely not limited by the piezo actuators. The piezo cavities can be electrically tuned over more than one free spectral range (>1.5 GHz) with only a minor decrease in frequency stability. Furthermore, we present a novel cavity design, where the piezo actuator is prestressed between the cavity spacer components. This design features a hermetically sealable intra cavity volume suitable for, e.g., cavity enhanced spectroscopy.

  2. Scaled experiments of explosions in cavities

    NASA Astrophysics Data System (ADS)

    Grun, J.; Cranch, G. A.; Lunsford, R.; Compton, S.; Walton, O. R.; Weaver, J.; Dunlop, W.; Fournier, K. B.

    2016-05-01

    Consequences of an explosion inside an air-filled cavity under the earth's surface are partly duplicated in a laboratory experiment on spatial scales 1000 smaller. The experiment measures shock pressures coupled into a block of material by an explosion inside a gas-filled cavity therein. The explosion is generated by suddenly heating a thin foil that is located near the cavity center with a short laser pulse, which turns the foil into expanding plasma, most of whose energy drives a blast wave in the cavity gas. Variables in the experiment are the cavity radius and explosion energy. Measurements and GEODYN code simulations show that shock pressures measured in the block exhibit a weak dependence on scaled cavity radius up to ˜25 m/kt1/3, above which they decrease rapidly. Possible mechanisms giving rise to this behavior are described. The applicability of this work to validating codes used to simulate full-scale cavity explosions is discussed.

  3. Shape Determination for Deformed Electromagnetic Cavities

    SciTech Connect

    Akcelik, Volkan; Ko, Kwok; Lee, Lie-Quan; Li, Zhenghai; Ng, Cho-Kuen; Xiao, Liling; /SLAC

    2007-12-10

    The measured physical parameters of a superconducting cavity differ from those of the designed ideal cavity. This is due to shape deviations caused by both loose machine tolerances during fabrication and by the tuning process for the accelerating mode. We present a shape determination algorithm to solve for the unknown deviations from the ideal cavity using experimentally measured cavity data. The objective is to match the results of the deformed cavity model to experimental data through least-squares minimization. The inversion variables are unknown shape deformation parameters that describe perturbations of the ideal cavity. The constraint is the Maxwell eigenvalue problem. We solve the nonlinear optimization problem using a line-search based reduced space Gauss-Newton method where we compute shape sensitivities with a discrete adjoint approach. We present two shape determination examples, one from synthetic and the other from experimental data. The results demonstrate that the proposed algorithm is very effective in determining the deformed cavity shape.

  4. Novel Geometries for the LHC Crab Cavity

    SciTech Connect

    B. Hall, G. Burt, C. Lingwood, R. Rimmer, H. Wang

    2010-05-23

    The planned luminosity upgrade to LHC is likely to necessitate a large crossing angle and a local crab crossing scheme. For this scheme crab cavities align bunches prior to collision. The scheme requires at least four such cavities, a pair on each beam line either side of the interaction point (IP). Upstream cavities initiate rotation and downstream cavities cancel rotation. Cancellation is usually done at a location where the optics has re-aligned the bunch. The beam line separation near the IP necessitates a more compact design than is possible with elliptical cavities such as those used at KEK. The reduction in size must be achieved without an increase in the operational frequency to maintain compatibility with the long bunch length of the LHC. This paper proposes a suitable superconducting variant of a four rod coaxial deflecting cavity (to be phased as a crab cavity), and presents analytical models and simulations of suitable designs.

  5. Chirped-cavity dispersion-compensation filter design

    NASA Astrophysics Data System (ADS)

    Li, Ya-Ping; Chen, Sheng-Hui; Lee, Cheng-Chung

    2006-03-01

    A new basic structure of a dispersive-compensation filter, called a chirped-cavity dispersion-compensator (CCDC) filter, was designed to offer the advantages of small ripples in both reflectance and group-delay dispersion (GDD). This filter provides a high dispersion compensation, like the Gires-Tournois interferometer (GTI) filter, and a wide working bandwidth, like the chirped mirror (CM). The structure of the CCDC is a cavity-type Fabry-Perot filter with a spacer layer (2 mH or 2 mL) and a chirped high reflector. The CCDC filter can provide a negative GDD of -50 fs2 over a bandwidth of 56 THz with half the optical thickness of the CM or the GTI.

  6. Bringing in the negative reinforcements: the avoidance feedback-related negativity.

    PubMed

    Crowley, Michael J; Wu, Jia; Bailey, Christopher A; Mayes, Linda C

    2009-11-25

    The feedback-related negativity (FRN) is an event-related potential thought to reflect a reward prediction error, when an outcome is worse than expected. Behavior motivated by the avoidance of negative outcomes is sustained through negative reinforcement processes. Escaping or avoiding a negative outcome may be successful or not, resulting in an analogous situation to that which elicits the FRN. We observed that when expected avoidance of an aversive outcome fails to occur, there occurs a negative deflection in the frontocentral event-related potential at approximately 350 ms, but with a slow wave following. We suggest that the FRN may be considered an index of a broader class of reward-based learning that also includes avoiding negative outcomes as well as expecting positive ones. PMID:19829164

  7. Thermodynamics of cavity formation in water and n-hexane using the Widom particle insertion method

    NASA Astrophysics Data System (ADS)

    Tomás-Oliveira, Isabel; Wodak, Shoshana J.

    1999-11-01

    The Widom particle insertion (WPI) method is used to compute the free energy, enthalpy, and entropy associated with the creation of empty cavities of different sizes in water and n-hexane. These thermodynamic parameters are computed from the likelihood of encountering such cavities in thermally equilibrated configurations from 4 ns (1 ns=10-9 s) molecular dynamics trajectories of the neat liquids. The obtained free energy values are in excellent agreement with those computed previously, using the same or other methods. We find that the entropy term is large and unfavorable in both liquids, but more so in water than in hexane. The change in internal energy is, on the other hand, virtually zero in hexane and slightly favorable in water. Comparison with scaled particle theory (SPT) predictions shows good agreement for the free energy values for small cavities, but the theory systematically underestimates these values for large cavities. In contrast, the free energy components obtained by the two methods show several significant differences. With WPI, the entropy of cavity formation is unfavorable in both liquids for all cavity sizes. SPT yields an unfavorable entropy only for water. In hexane, however, the predicted entropy is negative for small cavities, but changes sign for cavity radii >1.1 Å. In addition, SPT yields an unfavorable enthalpy of cavity formation in water, whereas with WPI this term is small but favorable. Taking n-hexane as a model for organic solvents, our calculations thus suggest that the process of cavity formation is similar in water and these solvents, a conclusion which seems to make good physical sense. SPT reaches an opposite conclusion, which seems harder to rationalize, and probably arises from the highly simplified solvent model used by this theory.

  8. Cavity Optomechanics at Millikelvin Temperatures

    NASA Astrophysics Data System (ADS)

    Meenehan, Sean Michael

    The field of cavity optomechanics, which concerns the coupling of a mechanical object's motion to the electromagnetic field of a high finesse cavity, allows for exquisitely sensitive measurements of mechanical motion, from large-scale gravitational wave detection to microscale accelerometers. Moreover, it provides a potential means to control and engineer the state of a macroscopic mechanical object at the quantum level, provided one can realize sufficiently strong interaction strengths relative to the ambient thermal noise. Recent experiments utilizing the optomechanical interaction to cool mechanical resonators to their motional quantum ground state allow for a variety of quantum engineering applications, including preparation of non-classical mechanical states and coherent optical to microwave conversion. Optomechanical crystals (OMCs), in which bandgaps for both optical and mechanical waves can be introduced through patterning of a material, provide one particularly attractive means for realizing strong interactions between high-frequency mechanical resonators and near-infrared light. Beyond the usual paradigm of cavity optomechanics involving isolated single mechanical elements, OMCs can also be fashioned into planar circuits for photons and phonons, and arrays of optomechanical elements can be interconnected via optical and acoustic waveguides. Such coupled OMC arrays have been proposed as a way to realize quantum optomechanical memories, nanomechanical circuits for continuous variable quantum information processing and phononic quantum networks, and as a platform for engineering and studying quantum many-body physics of optomechanical meta-materials. However, while ground state occupancies (that is, average phonon occupancies less than one) have been achieved in OMC cavities utilizing laser cooling techniques, parasitic absorption and the concomitant degradation of the mechanical quality factor fundamentally limit this approach. On the other hand, the high

  9. Negative Ion Density Fronts

    SciTech Connect

    Igor Kaganovich

    2000-12-18

    Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas.

  10. [Production and law of variation of the pleural cavity intrinsic pressure and the pressure of alveolar wall during respiratory process].

    PubMed

    Zhang, Shenghua; Qin, Renjia

    2012-04-01

    All physiologic textbooks deal with pleural cavity pressure, alveolar wall pressure and pressure inside the lung, but they have not stated these ideas clearly. The present study reveals production and Law of variation of the intrinsic pressure of pleural cavity, the pressure of alveolar wall and the intrinsic pressure in the alveoli. Pleural cavity intrinsic pressure is produced by the pressure from pleura expanding or compressing force of the lungs. When the lungs calmly inhale, the thorax expands, pleural cavity negative pressure increase. When the lungs calmly exhale, thorax reduces, but thorax and lungs are still in the extended state, pleural cavity is still in negative pressure. With thorax reducing, negative pressure decreases. When the lungs are at the forced expiration, the lung pleura and wall pleura extrude pleural cavity, only to produce positive pressure. The pressure of alveolar wall is the algebraic sum of the intrinsic pressure of pleural cavity, the intrinsic pressure of pulmonary tissue and the additional pressure of alveolar wall. We did the calculation of additional pressure on the alveolar wall by using Laplace formula of spherical elastic membrane. The intrinsic pressure of alveoli depends on the moving speed or slowness of expansion or compression of alveolar wall and the size of trachea resistance. PMID:22616171

  11. Observation and characterization of cavity Rydberg polaritons

    NASA Astrophysics Data System (ADS)

    Ningyuan, Jia; Georgakopoulos, Alexandros; Ryou, Albert; Schine, Nathan; Sommer, Ariel; Simon, Jonathan

    2016-04-01

    We experimentally demonstrate the emergence of a robust quasiparticle, the cavity Rydberg polariton, when an optical cavity photon hybridizes with a collective Rydberg excitation of a laser-cooled atomic ensemble. Free-space Rydberg polaritons have recently drawn intense interest as tools for quantum information processing and few-body quantum science. Here, we explore the properties of their cavity counterparts in the single-particle sector, observing an enhanced lifetime and slowed dynamics characteristic of cavity dark polaritons. We measure the range of cavity frequencies over which the polaritons persist, corresponding to the spectral width available for polariton quantum dynamics, and the speed limit for quantum information processing. Further, we observe a cavity-induced suppression of inhomogeneous broadening channels and demonstrate the formation of Rydberg polaritons in a multimode cavity. In conjunction with recent demonstrations of Rydberg-induced cavity nonlinearities, our results point the way towards using cavity Rydberg polaritons as a platform for creating high-fidelity photonic quantum materials and, more broadly, indicate that cavity dark polaritons offer enhanced stability and control uniquely suited to optical quantum information processing applications beyond the Rydberg paradigm.

  12. The addiction to negativity.

    PubMed

    Lane, R C; Hull, J W; Foehrenbach, L M

    1991-01-01

    In this paper, we have described a type of resistance that has attracted increasing psychoanalytic attention in recent years. Patients exposed to intense negativity during early life may develop an addiction to negative experience as adolescents and adults, and this may constitute a central organizing feature of their personality. In almost all patients, however, some moments of negativity may be observed. We have traced the developmental origins of an attachment to negativity, drawing especially on psychoanalytic investigations of preoedipal pathology. Manifestations and derivatives of early negativity include anhedonia, attachment to physical pain, fear of success, masochism, deprivation of self and others, and negative voyeurism. In discussing the dynamic functions of negativity, we place particular emphasis on two motives: the patient's desires for revenge against early objects that have been a source of deprivation and frustration; and the defensive function of negativity in helping to express as well as ward off dangerous wishes to merge with the object. Deviant forms of autoerotism are likely to be used by these patients to deal with the reactivation of early experiences of neglect and rejection. When negativity is used as a defense or method of relating to others it can lead to a severe disruption of the psychotherapeutic relationship. We have reviewed suggestions for the management of extreme negativity in treatment. Resolution of the therapist's countertransference reactions, especially induced feelings of frustration, rage, and helplessness, is crucial. Emphasis also has been placed on the patient's desires for revenge against self and object, and the manner in which these may be understood and eventually resolved. Only when patient and therapist begin to investigate the adaptive functions of extreme negativity can this pathological symptom be resolved and the patient's awareness of self and sense of autonomy be enhanced. PMID:1763149

  13. Use of a variable frequency source with a single-mode cavity to process ceramic filaments

    SciTech Connect

    Vogt, G.J.; Regan, A.H.; Rohlev, A.S.; Curtin, M.T.

    1995-05-01

    =Rapid feedback control is needed for practical microwave processing of continuous ceramic oxide filaments to regulate the process temperature where the dielectric properties of the filaments change rapidly with temperature. A broadband traveling wave tube (TWT) amplifier provides a highly versatile process control platform for filament processing. By comparing a rf signal from the cavity to a reference signal from the TWT, phase information can be used in a negative feedback loop to allow the oscillator to track the cavity frequency as it shifts due to the changing dielectric constant in the filaments being heated. By sampling the field level in the cavity with a detector, amplitude control can be done to maintain a consistent electric field level in the cavity, which is important for controlling the filament heating and temperature. The system design will be discussed along with application data for commercial ceramic samples.

  14. Mismatch Negativity: Translating the Potential

    PubMed Central

    Todd, Juanita; Harms, Lauren; Schall, Ulrich; Michie, Patricia T.

    2013-01-01

    The mismatch negativity (MMN) component of the auditory event-related potential has become a valuable tool in cognitive neuroscience. Its reduced size in persons with schizophrenia is of unknown origin but theories proposed include links to problems in experience-dependent plasticity reliant on N-methyl-d-aspartate glutamate receptors. In this review we address the utility of this tool in revealing the nature and time course of problems in perceptual inference in this illness together with its potential for use in translational research testing animal models of schizophrenia-related phenotypes. Specifically, we review the reasons for interest in MMN in schizophrenia, issues pertaining to the measurement of MMN, its use as a vulnerability index for the development of schizophrenia, the pharmacological sensitivity of MMN and the progress in developing animal models of MMN. Within this process we highlight the challenges posed by knowledge gaps pertaining to the tool and the pharmacology of the underlying system. PMID:24391602

  15. Sound pressure level gain in an acoustic metamaterial cavity.

    PubMed

    Song, Kyungjun; Kim, Kiwon; Hur, Shin; Kwak, Jun-Hyuk; Park, Jihyun; Yoon, Jong Rak; Kim, Jedo

    2014-01-01

    The inherent attenuation of a homogeneous viscous medium limits radiation propagation, thereby restricting the use of many high-frequency acoustic devices to only short-range applications. Here, we design and experimentally demonstrate an acoustic metamaterial localization cavity which is used for sound pressure level (SPL) gain using double coiled up space like structures thereby increasing the range of detection. This unique behavior occurs within a subwavelength cavity that is 1/10(th) of the wavelength of the incident acoustic wave, which provides up to a 13 dB SPL gain. We show that the amplification results from the Fabry-Perot resonance of the cavity, which has a simultaneously high effective refractive index and effective impedance. We also experimentally verify the SPL amplification in an underwater environment at higher frequencies using a sample with an identical unit cell size. The versatile scalability of the design shows promising applications in many areas, especially in acoustic imaging and underwater communication. PMID:25502279

  16. Outbursts from cavities in comets

    NASA Astrophysics Data System (ADS)

    Ipatov, S.

    2014-07-01

    In 2005 the impact module of the Deep Impact (DI) spacecraft collided with Comet 9P/Tempel 1. Based on analysis of the images made during the first 13 minutes after the collision of the DI impact module with the comet, Ipatov and A'Hearn [1] studied time variations of ejection of material after this impact. Observed brightness of the cloud of ejected material was mainly due to particles with diameters d<3 micron, and so we discussed ejection of such particles. It was shown that, besides the normal ejection of material from the crater, at time t_{e} after the DI collision between 8 s and 60 s there was a considerable additional ejection (a triggered outburst) of small (micron size) particles. It increased the mean velocities of observed small ejected particles (compared with the normal ejection). It is difficult to explain the time variations in the brightness of the DI cloud at distance 1cavity with dust and gas under pressure. Though the model of a layered target can play some role in an explanation of the variation in brightness of the DI cloud, it cannot explain all details of such variation (for example, at t_{e} sim 10 s there was simultaneously a jump in the direction from the place of ejection to the brightest pixel in an image of the DI cloud by 50 degrees, an increase in the rate of ejection of small particles, and an increase in the brightness of the brightest pixel; at t_{e} ≈ 60 s there was a sharp decrease in the rate of ejection of small particles, and at t_{e} ≈ 60 s the direction from the place of ejection to the brightest pixel returned to the direction at 1 < t_{e} <12 s; the mean ejection velocities of observed particles were almost the same at t_{e} about 10-20 s, etc.). In [1] it was concluded that particles could not increase their velocities by more than a few meters per second during those

  17. Broadband tuning of optomechanical cavities

    NASA Astrophysics Data System (ADS)

    Wiederhecker, Gustavo S.; Manipatruni, Sasikanth; Lee, Sunwoo; Lipson, Michal

    2011-01-01

    We demonstrate broadband tuning of an optomechanical microcavity optical resonance by exploring the large optomechanical coupling of a double-wheel microcavity and its uniquely low mechanical stiffness. Using a pump laser with only 13 mW at telecom wavelengths we show tuning of the silicon nitride microcavity resonances over 32 nm. This corresponds to a tuning power efficiency of only 400 $\\mu$W/nm. By choosing a relatively low optical Q resonance ($\\approx$18,000) we prevent the cavity from reaching the regime of regenerative optomechanical oscillations. The static mechanical displacement induced by optical gradient forces is estimated to be as large as 60 nm.

  18. A terahertz plasmon cavity detector

    SciTech Connect

    Dyer, G. C.; Vinh, N. Q.; Allen, S. J.; Aizin, G. R.; Mikalopas, J.; Reno, J. L.; Shaner, E. A.

    2010-11-08

    Sensitivity of a plasmonic detector is enhanced by integrating a broadband log-periodic antenna with a two-dimensional plasma cavity that is defined by source, drain, and multiple gates of a GaAs/AlGaAs high electron mobility transistor. Both narrow-band terahertz detection and a rich harmonic spectrum are evident. With a bolometric sensor in the channel, we report responsivity, on resonance at 235-240 GHz and at 20 K, of up to 7 kV/W and a noise equivalent power of 5x10{sup -10} W/Hz{sup 1/2}.

  19. Basketballs as spherical acoustic cavities

    NASA Astrophysics Data System (ADS)

    Russell, Daniel A.

    2010-06-01

    The sound field resulting from striking a basketball is found to be rich in frequency content, with over 50 partials in the frequency range of 0-12 kHz. The frequencies are found to closely match theoretical expectations for standing wave patterns inside a spherical cavity. Because of the degenerate nature of the mode shapes, explicit identification of the modes is not possible without internal investigation with a microphone probe. A basketball proves to be an interesting application of a boundary value problem involving spherical coordinates.

  20. Cavity quantum electro-optics

    SciTech Connect

    Tsang, Mankei

    2010-06-15

    The quantum dynamics of the coupling between a cavity optical field and a resonator microwave field via the electro-optic effect is studied. This coupling has the same form as the optomechanical coupling via radiation pressure, so all previously considered optomechanical effects can in principle be observed in electro-optic systems as well. In particular, I point out the possibilities of laser cooling of the microwave mode, entanglement between the optical mode and the microwave mode via electro-optic parametric amplification, and back-action-evading optical measurements of a microwave quadrature.

  1. Mass renormalization in cavity QED

    SciTech Connect

    Matloob, Reza

    2011-01-15

    We show that the presence of a background medium and a boundary surface or surfaces in cavity QED produces no change in the energy shift of a free charged particle due to its coupling to the fluctuating electromagnetic field of the vacuum. This clarifies that the electromagnetic and the observed mass of the charged particle are not affected by the modification of the field of the vacuum. The calculations are nonrelativistic and restricted to the dipole approximation but are otherwise based on the general requirements of causality.

  2. The Evolution of Negation.

    ERIC Educational Resources Information Center

    Croft, William

    1991-01-01

    Discusses a method for extrapolation of diachronic processes from synchronic states, the dynamicization of synchronic typologies, to propose a hitherto unobserved historical source for markers of verbal negation, namely irregular negative existential predicate forms. Explanations are proposed for the occurrence of the attested processes in this…

  3. Learning from Negative Morality.

    ERIC Educational Resources Information Center

    Oser, Fritz K.

    1996-01-01

    Identifies and discusses the elements and applications of learning from negative morality. Negative morality refers to the experience of learning from mistakes thereby creating a body of personal knowledge about "what not to do." This knowledge not only protects individuals but steers them to the right behavior. (MJP)

  4. Stent hypersensitivity and infection in sinus cavities

    PubMed Central

    Soufras, George D.; Hahalis, George

    2013-01-01

    Persistent mucosal inflammation, granulation tissue formation, hypersensitivity, and multifactorial infection are newly described complications of retained drug-eluting stents from endoscopic sinus surgery for refractory rhinosinusitis. In an important report published in Allergy and Rhinology, a 45-year-old male patient suffering from recalcitrant chronic rhinosinusitis underwent functional endoscopic sinus surgery and was found, for the first time, to have steroid-eluting catheters that were inadvertently left in the ethmoid and frontal sinuses. The retained catheters had caused persistent mucosal inflammation and formation of granulation tissue denoting hypersensitivity reaction. These consequences had induced perpetuation of symptoms of chronic rhinosinusitis. Meticulous removal of the retained stents with the nitinol wings from inflamed tissues of the frontal, ethmoidal, and sphenoethmoidal recesses in which they were completely imbedded was successfully performed without polypoid regrowth. Cultures of specimens taken from both left and right stents showed heavy growth of Stenotrophomonas maltophilia and moderate growth of Klebsiella oxytoca, coagulase negative Staphylococcus, and beta-hemolytic Streptococcus anginosus. Fungal infection was not detected. The current knowledge and experience regarding stent hypersensitivity and infection in relation with the use of stents in sinus cavities is reviewed. PMID:24498522

  5. On Negative Mass

    NASA Astrophysics Data System (ADS)

    Belletête, Jonathan; Paranjape, M. B.

    2013-06-01

    The Schwarzschild solution to the matter free, spherically symmetric Einstein equations has one free parameter, the mass. But the mass can be of any sign. What is the meaning of the negative mass solutions? The answer to this question for the case of a pure Schwarzschild negative mass black solution is still elusive, however, in this essay, we will consider negative mass solutions within a Schwarzschild-de Sitter geometry. We show that there exist reasonable configurations of matter, bubbles of distributions of matter, that satisfy the dominant energy condition everywhere, that are nonsingular and well behaved everywhere, but correspond to the negative mass Schwarzschild-de Sitter geometry outside the matter distribution. These negative mass bubbles could occur as the end state of a quantum tunneling transition.

  6. EMMSE Media Index.

    ERIC Educational Resources Information Center

    Hewitt, Clifford A., Comp.; McKinstry, Herbert A., Comp.

    This index provides a topical taxonomy of media which have been selected for their relevance in the teaching of materials science and engineering. The index is keyed to a matrix which matches topical and/or class material with six classifications of media: print, 16mm film, super 8 film, slide/tape, videotape, and other (including interactive…

  7. Exploring Volumetrically Indexed Cups

    ERIC Educational Resources Information Center

    Jones, Dustin L.

    2011-01-01

    This article was inspired by a set of 12 cylindrical cups, which are volumetrically indexed; that is to say, the volume of cup "n" is equal to "n" times the volume of cup 1. Various sets of volumetrically indexed cylindrical cups are explored. I demonstrate how this children's toy is ripe for mathematical investigation, with connections to…

  8. HUMAN USE INDEX (FUTURE)

    EPA Science Inventory

    Human land uses may have major impacts on ecosystems, affecting biodiversity, habitat, air and water quality. The human use index (also known as U-index) is the percentage of human land use in an area, including agriculture, urban and suburban development, and mining. Low values ...

  9. HUMAN USE INDEX

    EPA Science Inventory

    Human land uses may have major impacts on ecosystems, affecting biodiversity, habitat, air and water quality. The human use index (also known as U-index) is the percentage of human land use in an area, including agriculture, urban and suburban development, and mining. Low values ...

  10. Children's Stress Index.

    ERIC Educational Resources Information Center

    Sherman, Dianne, Ed.

    1993-01-01

    This double issue of the "ZPG Reporter" focuses on the theme of ZPG's Children's Stress Index", the first national survey of children's well-being based on population- related pressures. Using an extensive list of social, economic, and environmental factors that affect the lives of children, the index ranks 828 cities, counties, and metropolitan…

  11. Drought Frequency Index

    NASA Astrophysics Data System (ADS)

    Gonzalez, J.; Valdes, J. B.

    2003-04-01

    Droughts are related with prolonged time periods during moisture is significantly below normal situation. Drought indexes try to scale the main drought features based on similar definitions. The Standard Precipitation Index (SPI) is a well-known index, which for a given aggregation-time measures the deviation from the normality of the precipitation. One of the SPI weak points in the representation of drought phenomenon is that drought duration should be analyzed by using different aggregation-times. In this work, a new index is presented, which simultaneously characterize droughts based on the deviation from the normal precipitation regime and the drought persistence, both from the statistical point of view. The new index does not require aggregation at different time-lengths. Instead droughts are treated as multivariate events, whose dimensionality depends on the duration. Probabilistic events with different dimensionalities are compared on a common dimension of interest. In this case the dimension chosen is the mean frequency of recurrence. The derived index, named Drought Frequency Index (DFI) may be used to characterize historical droughts or current situation. It can be apply not only over precipitation but also over flows or other hydroclimatic variables. The new index was applied to several places in USA and Spain both for precipitation and flow historical sequences, and compared with SPI. The DFI allows the representation of the main drought characteristics in a single value, based on the stochastic feature of the phenomenon, and scaled on the mean frequency of recurrence.

  12. Transfer Index: One Definition.

    ERIC Educational Resources Information Center

    Heinselman, James L.

    A transfer index of the proportion of students in California's community colleges transferring to the University of California (UC) and the California State University (CSU) system for fall 1982, 1983, and 1984 is presented in this report. Introductory material provides one definition of an appropriate index of transfer rates, i.e., the ratio of…

  13. A Computer Calculated Index.

    ERIC Educational Resources Information Center

    Brown, Francis J.

    The Gunning Fog Index of readability indicates both the average length of words and the difficult words (three or more syllables) in written material. This document describes a business communication course at Wayne State University in which students calculate the Gunning Fog Index of two of their writing assignments with the aid of the…

  14. Gradient index retroreflector

    DOEpatents

    Layne, Clyde B.

    1988-01-01

    A retroreflector is formed of a graded index lens with a reflective coating at one end. The lens has a length of an odd multiple of a quarter period thereof. Hexagonally shaped graded index lenses may be closely packed in an array to form a retroreflecting surface.

  15. Turbine disk cavity aerodynamics and heat transfer

    NASA Astrophysics Data System (ADS)

    Johnson, B. V.; Daniels, W. A.

    1992-07-01

    Experiments were conducted to define the nature of the aerodynamics and heat transfer for the flow within the disk cavities and blade attachments of a large-scale model, simulating the Space Shuttle Main Engine (SSME) turbopump drive turbines. These experiments of the aerodynamic driving mechanisms explored the following: (1) flow between the main gas path and the disk cavities; (2) coolant flow injected into the disk cavities; (3) coolant density; (4) leakage flows through the seal between blades; and (5) the role that each of these various flows has in determining the adiabatic recovery temperature at all of the critical locations within the cavities. The model and the test apparatus provide close geometrical and aerodynamic simulation of all the two-stage cavity flow regions for the SSME High Pressure Fuel Turbopump and the ability to simulate the sources and sinks for each cavity flow.

  16. Rebuild of Capture Cavity 1 at Fermilab

    SciTech Connect

    Harms, E.; Arkan, T.; Borissov, E.; Dhanaraj, N.; Hocker, A.; Orlov, Y.; Peterson, T.; Premo, K.

    2014-01-01

    The front end of the proposed Advanced Superconducting Test Accelerator at Fermilab employs two single cavity cryomodules, known as 'Capture Cavity 1' and 'Capture Cavity 2', for the first stage of acceleration. Capture Cavity 1 was previously used as the accelerating structure for the A0 Photoinjector to a peak energy of ~14 MeV. In its new location a gradient of ~25 MV/m is required. This has necessitated a major rebuild of the cryomodule including replacement of the cavity with a higher gradient one. Retrofitting the cavity and making upgrades to the module required significant redesign. The design choices and their rationale, summary of the rebuild, and early test results are presented.

  17. Tunable-cavity QED with phase qubits

    NASA Astrophysics Data System (ADS)

    Whittaker, Jed D.; da Silva, Fabio; Allman, Michael Shane; Lecocq, Florent; Cicak, Katarina; Sirois, Adam; Teufel, John; Aumentado, Jose; Simmonds, Raymond W.

    2014-03-01

    We describe a tunable-cavity QED architecture with an rf SQUID phase qubit inductively coupled to a single-mode, resonant cavity with a tunable frequency that allows for both tunneling and dispersive measurements. Dispersive measurement is well characterized by a three-level model, strongly dependent on qubit anharmonicity, qubit-cavity coupling and detuning. The tunable cavity frequency provides dynamic control over the coupling strength and qubit-cavity detuning helping to minimize Purcell losses and cavity-induced dephasing during qubit operation. The maximum decay time T1 = 1 . 5 μs is limited by dielectric losses from a design geometry similar to planar transmon qubits. This work supported by NIST and NSA grant EAO140639.

  18. An Experimental Investigation of Supersonic Cavity Flows

    NASA Astrophysics Data System (ADS)

    Zhuang, Ning; Alvi, Farrukh. S.; Shih, Chiang; Krothapalli, Anjaneyulu; Alkislar, Mehmet. B.

    2003-11-01

    A series of experiments were conducted on supersonic, Mach = 2, cavity flow over variable length / depth ratios, L/D=1 ˜5. Large-scale structures in the cavity shear layer were clearly captured by particle image velocimetry method. The convective velocities of the structures were measured around 60% of the freestream velocity. Supersonic microjets at the leading edge of the cavity were implemented to control the flow-induced resonance in the cavities. The size and strength of the large-scale structure were also significant altered by the microjets. More than 9 dB reduction in Prms and more than 20 dB reduction in cavity tones were obtained with an extremely low mass flux, the cavity blowing ratio Bc < 0.2%.

  19. Coupled-cavity drift-tube linac

    DOEpatents

    Billen, J.H.

    1996-11-26

    A coupled-cavity drift-tube linac (CCDTL) combines features of the Alvarez drift-tube linac (DTL) and the {pi}-mode coupled-cavity linac (CCL). In one embodiment, each accelerating cavity is a two-cell, 0-mode DTL. The center-to-center distance between accelerating gaps is {beta}{lambda}, where {lambda} is the free-space wavelength of the resonant mode. Adjacent accelerating cavities have oppositely directed electric fields, alternating in phase by 180 degrees. The chain of cavities operates in a {pi}/2 structure mode so the coupling cavities are nominally unexcited. The CCDTL configuration provides an rf structure with high shunt impedance for intermediate velocity charged particles, i.e., particles with energies in the 20-200 MeV range. 5 figs.

  20. Coupled-cavity drift-tube linac

    DOEpatents

    Billen, James H.

    1996-01-01

    A coupled-cavity drift-tube linac (CCDTL) combines features of the Alvarez drift-tube linac (DTL) and the .pi.-mode coupled-cavity linac (CCL). In one embodiment, each accelerating cavity is a two-cell, 0-mode DTL. The center-to-center distance between accelerating gaps is .beta..lambda., where .lambda. is the free-space wavelength of the resonant mode. Adjacent accelerating cavities have oppositely directed electric fields, alternating in phase by 180 degrees. The chain of cavities operates in a .pi./2 structure mode so the coupling cavities are nominally unexcited. The CCDTL configuration provides an rf structure with high shunt impedance for intermediate velocity charged particles, i.e., particles with energies in the 20-200 MeV range.

  1. Cavity-Dumped Communication Laser Design

    NASA Technical Reports Server (NTRS)

    Roberts, W. T.

    2003-01-01

    Cavity-dumped lasers have significant advantages over more conventional Q-switched lasers for high-rate operation with pulse position modulation communications, including the ability to emit laser pulses at 1- to 10-megahertz rates, with pulse widths of 0.5 to 5 nanoseconds. A major advantage of cavity dumping is the potential to vary the cavity output percentage from pulse to pulse, maintaining the remainder of the energy in reserve for the next pulse. This article presents the results of a simplified cavity-dumped laser model, establishing the requirements for cavity efficiency and projecting the ultimate laser efficiency attainable in normal operation. In addition, a method of reducing or eliminating laser dead time is suggested that could significantly enhance communication capacity. The design of a laboratory demonstration laser is presented with estimates of required cavity efficiency and demonstration potential.

  2. Mounting system for optical frequency reference cavities

    NASA Technical Reports Server (NTRS)

    Notcutt, Mark (Inventor); Hall, John L. (Inventor); Ma, Long-Sheng (Inventor)

    2008-01-01

    A technique for reducing the vibration sensitivity of laser-stabilizing optical reference cavities is based upon an improved design and mounting method for the cavity, wherein the cavity is mounted vertically. It is suspended at one plane, around the spacer cylinder, equidistant from the mirror ends of the cavity. The suspension element is a collar of an extremely low thermal expansion coefficient material, which surrounds the spacer cylinder and contacts it uniformly. Once the collar has been properly located, it is cemented in place so that the spacer cylinder is uniformly supported and does not have to be squeezed at all. The collar also includes a number of cavities partially bored into its lower flat surface, around the axial bore. These cavities are support points, into which mounting base pins will be inserted. Hence the collar is supported at a minimum of three points.

  3. Quantum coherence in a coupled-cavity array

    NASA Astrophysics Data System (ADS)

    Cao, De-Wei; Zhang, Yixin; Wang, Jicheng; Hu, Zheng-Da

    2016-05-01

    The dynamical properties of quantum coherence in the system of two-coupled-cavities, each of which resonantly interacts with a two-level atom, is investigated via the relative entropy measure. We focus on the coherences for the atom-atom, atom-cavity and cavity-cavity subsystems and find that the dynamical behaviors of these coherences depend largely on the cavity-cavity coupling, which may indicate the Mott insulator-superfluid transition in the thermodynamic limit. We also study the influences of the initial cavity-cavity correlation on the coherences and show that the initial correlation of the cavity-cavity subsystem can enhance the revival ability for the atom-atom and cavity-cavity coherences while reduce that for the atom-cavity coherence. Besides, we demonstrate the qualitative difference of dynamics between coherence and entanglement. Finally, the influences of dissipations including cavity losses and atomic decays on the coherence are explored.

  4. Visible light emitting vertical cavity surface emitting lasers

    DOEpatents

    Bryan, R.P.; Olbright, G.R.; Lott, J.A.; Schneider, R.P. Jr.

    1995-06-27

    A vertical cavity surface emitting laser that emits visible radiation is built upon a substrate, then having mirrors, the first mirror on top of the substrate; both sets of mirrors being a distributed Bragg reflector of either dielectrics or other materials which affect the resistivity or of semiconductors, such that the structure within the mirror comprises a plurality of sets, each having a thickness of {lambda}/2n where n is the index of refraction of each of the sets; each of the mirrors adjacent to spacers which are on either side of an optically active bulk or quantum well layer; and the spacers and the optically active layer are from one of the following material systems: In{sub z}(Al{sub y}Ga{sub 1{minus}y}){sub 1{minus}z}P, InAlGaAs, AlGaAs, InGaAs, or AlGaP/GaP, wherein the optically active region having a length equal to m {lambda}/2n{sub eff} where m is an integer and n{sub eff} is the effective index of refraction of the laser cavity, and the spacer layer and one of the mirrors being transmissive to radiation having a wavelength of {lambda}/n, typically within the green to red portion of the visible spectrum. 10 figs.

  5. Visible light emitting vertical cavity surface emitting lasers

    DOEpatents

    Bryan, Robert P.; Olbright, Gregory R.; Lott, James A.; Schneider, Jr., Richard P.

    1995-01-01

    A vertical cavity surface emitting laser that emits visible radiation is built upon a substrate, then having mirrors, the first mirror on top of the substrate; both sets of mirrors being a distributed Bragg reflector of either dielectrics or other materials which affect the resistivity or of semiconductors, such that the structure within the mirror comprises a plurality of sets, each having a thickness of .lambda./2n where n is the index of refraction of each of the sets; each of the mirrors adjacent to spacers which are on either side of an optically active bulk or quantum well layer; and the spacers and the optically active layer are from one of the following material systems: In.sub.z (Al.sub.y Ga.sub.1-y).sub.1-z P, InAlGaAs, AlGaAs, InGaAs, or AlGaP/GaP, wherein the optically active region having a length equal to m .lambda./2n.sub.eff where m is an integer and n.sub.eff is the effective index of refraction of the laser cavity, and the spacer layer and one of the mirrors being transmissive to radiation having a wavelength of .lambda./n, typically within the green to red portion of the visible spectrum.

  6. Negative refraction using Raman transitions and chirality

    SciTech Connect

    Sikes, D. E.; Yavuz, D. D.

    2011-11-15

    We present a scheme that achieves negative refraction with low absorption in far-off resonant atomic systems. The scheme utilizes Raman resonances and does not require the simultaneous presence of an electric-dipole transition and a magnetic-dipole transition near the same wavelength. We show that two interfering Raman tran-sitions coupled to a magnetic-dipole transition can achieve a negative index of refraction with low absorption through magnetoelectric cross-coupling. We confirm the validity of the analytical results with exact numerical simulations of the density matrix. We also discuss possible experimental implementations of the scheme in rare-earth metal atomic systems.

  7. Negative refraction using Raman transitions and chirality

    NASA Astrophysics Data System (ADS)

    Sikes, D. E.; Yavuz, D. D.

    2011-11-01

    We present a scheme that achieves negative refraction with low absorption in far-off resonant atomic systems. The scheme utilizes Raman resonances and does not require the simultaneous presence of an electric-dipole transition and a magnetic-dipole transition near the same wavelength. We show that two interfering Raman tran-sitions coupled to a magnetic-dipole transition can achieve a negative index of refraction with low absorption through magnetoelectric cross-coupling. We confirm the validity of the analytical results with exact numerical simulations of the density matrix. We also discuss possible experimental implementations of the scheme in rare-earth metal atomic systems.

  8. Breakthrough: Record-Setting Cavity

    ScienceCinema

    Ciovati, Gianluigi

    2014-05-21

    Gianluigi "Gigi" Ciovati, a superconducting radiofrequency scientist, discusses how scientists at the U.S. Department of Energy's Jefferson Lab in Newport News, VA, used ARRA funds to fabricate a niobium cavity for superconducting radiofrequency accelerators that has set a world record for energy efficiency. Jefferson Lab's scientists developed a new, super-hot treatment process that could soon make it possible to produce cavities more quickly and at less cost, benefitting research and healthcare around the world. Accelerators are critical to our efforts to study the structure of matter that builds our visible universe. They also are used to produce medical isotopes and particle beams for diagnosing and eradicating disease. And they offer the potential to power future nuclear power plants that produce little or no radioactive waste.around the world. Accelerators are critical to our efforts to study the structure of matter that builds our visible universe. They also are used to produce medical isotopes and particle beams for diagnosing and eradicating disease. And they offer the potential to power future nuclear power plants that produce little or no radioactive waste.

  9. Silicon Integrated Cavity Optomechanical Transducer

    NASA Astrophysics Data System (ADS)

    Zou, Jie; Miao, Houxun; Michels, Thomas; Liu, Yuxiang; Srinivasan, Kartik; Aksyuk, Vladimir

    2013-03-01

    Cavity optomechanics enables measurements of mechanical motion at the fundamental limits of precision imposed by quantum mechanics. However, the need to align and couple devices to off-chip optical components hinders development, miniaturization and broader application of ultrahigh sensitivity chip-scale optomechanical transducers. Here we demonstrate a fully integrated and optical fiber pigtailed optomechanical transducer with a high Q silicon micro-disk cavity near-field coupled to a nanoscale cantilever. We detect the motion of the cantilever by measuring the resonant frequency shift of the whispering gallery mode of the micro-disk. The sensitivity near the standard quantum limit can be reached with sub-uW optical power. Our on-chip approach combines compactness and stability with great design flexibility: the geometry of the micro-disk and cantilever can be tailored to optimize the mechanical/optical Q factors and tune the mechanical frequency over two orders of magnitudes. Electrical transduction in addition to optical transduction was also demonstrated and both can be used to effectively cool the cantilever. Moreover, cantilevers with sharp tips overhanging the chip edge were fabricated to potentially allow the mechanical cantilever to be coupled to a wide range of off-chip systems, such as spins, DNA, nanostructures and atoms on clean surfaces.

  10. SPINNING MOTIONS IN CORONAL CAVITIES

    SciTech Connect

    Wang, Y.-M.; Stenborg, G. E-mail: guillermo.stenborg.ctr.ar@nrl.navy.mi

    2010-08-20

    In movies made from Fe XII 19.5 nm images, coronal cavities that graze or are detached from the solar limb appear as continually spinning structures, with sky-plane projected flow speeds in the range 5-10 km s{sup -1}. These whirling motions often persist in the same sense for up to several days and provide strong evidence that the cavities and the immediately surrounding streamer material have the form of helical flux ropes viewed along their axes. A pronounced bias toward spin in the equatorward direction is observed during 2008. We attribute this bias to the poleward concentration of the photospheric magnetic flux near sunspot minimum, which leads to asymmetric heating along large-scale coronal loops and tends to drive a flow from higher to lower latitudes; this flow is converted into an equatorward spinning motion when the loops pinch off to form a flux rope. As sunspot activity increases and the polar fields weaken, we expect the preferred direction of the spin to reverse.

  11. Breakthrough: Record-Setting Cavity

    SciTech Connect

    Ciovati, Gianluigi

    2012-03-01

    Gianluigi "Gigi" Ciovati, a superconducting radiofrequency scientist, discusses how scientists at the U.S. Department of Energy's Jefferson Lab in Newport News, VA, used ARRA funds to fabricate a niobium cavity for superconducting radiofrequency accelerators that has set a world record for energy efficiency. Jefferson Lab's scientists developed a new, super-hot treatment process that could soon make it possible to produce cavities more quickly and at less cost, benefitting research and healthcare around the world. Accelerators are critical to our efforts to study the structure of matter that builds our visible universe. They also are used to produce medical isotopes and particle beams for diagnosing and eradicating disease. And they offer the potential to power future nuclear power plants that produce little or no radioactive waste.around the world. Accelerators are critical to our efforts to study the structure of matter that builds our visible universe. They also are used to produce medical isotopes and particle beams for diagnosing and eradicating disease. And they offer the potential to power future nuclear power plants that produce little or no radioactive waste.

  12. Resonant-cavity antenna for plasma heating

    DOEpatents

    Perkins, Jr., Francis W.; Chiu, Shiu-Chu; Parks, Paul; Rawls, John M.

    1987-01-01

    Disclosed is a resonant coil cavity wave launcher for energizing a plasma immersed in a magnetic field. Energization includes launching fast Alfven waves to excite ion cyclotron frequency resonances in the plasma. The cavity includes inductive and capacitive reactive members spaced no further than one-quarter wavelength from a first wall confinement chamber of the plasma. The cavity wave launcher is energized by connection to a waveguide or transmission line carrying forward power from a remote radio frequency energy source.

  13. Compact Superconducting Crabbing and Deflecting Cavities

    SciTech Connect

    De Silva, Payagalage Subashini Uddika

    2012-09-01

    Recently, new geometries for superconducting crabbing and deflecting cavities have been developed that have significantly improved properties over those the standard TM{sub 110} cavities. They are smaller, have low surface fields, high shunt impedance and, more importantly for some of them, no lower-order-mode with a well-separated fundamental mode. This talk will present the status of the development of these cavities.

  14. Dither Cavity Length Controller with Iodine Locking

    NASA Astrophysics Data System (ADS)

    Lawson, Marty; Eloranta, Ed

    2016-06-01

    A cavity length controller for a seeded Q-switched frequency doubled Nd:YAG laser is constructed. The cavity length controller uses a piezo-mirror dither voltage to find the optimum length for the seeded cavity. The piezo-mirror dither also dithers the optical frequency of the output pulse. [1]. This dither in optical frequency is then used to lock to an Iodine absorption line.

  15. Grating cavity dual wavelength dye laser.

    PubMed

    Zapata-Nava, Oscar Javier; Rodríguez-Montero, Ponciano; Iturbe-Castillo, M David; Treviño-Palacios, Carlos Gerardo

    2011-02-14

    We report simultaneous dual wavelength dye laser emission using Littman-Metcalf and Littrow cavity configurations with minimum cavity elements. Dual wavelength operation is obtained by laser operation in two optical paths inside the cavity, one of which uses reflection in the circulating dye cell. Styryl 14 laser dye operating in the 910 nm to 960 nm was used in a 15%:85% PC/EG solvent green pumped with a Q-switched doubled Nd3+:YAG laser. PMID:21369171

  16. Optical microfiber-based photonic crystal cavity

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Sun, Yi-zhi; Andrews, Steve; Li, Zhi-yuan; Ding, Wei

    2016-01-01

    Using a focused ion beam milling technique, we fabricate broad stop band (∼10% wide) photonic crystal (PhC) cavities in adiabatically-tapered silica fibers. Abrupt structural design of PhC mirrors efficiently reduces radiation loss, increasing the cavity finesse to ∼7.5. Further experiments and simulations verify that the remaining loss is mainly due to Ga ion implantation. Such a microfiber PhC cavity probably has potentials in many light-matter interaction applications.

  17. Analysis of photonic crystal double heterostructure resonant cavities

    NASA Astrophysics Data System (ADS)

    Mock, Adam

    Two-dimensional photonic crystals represent a versatile technology platform for constructing photonic integrated circuits. Low-loss and small footprint waveguides and cavities can be combined to make delay lines, modulators, filters and lasers for efficient optical signal processing. However, this diverse functionality comes at the expense of higher complexity in both the fabrication and themodeling of these devices. This Thesis discusses the finite-difference time-domain numerical modeling of large quality factor photonic crystal cavities for chip-scale laser applications. In Chapter 2 the role of the quality factor in estimating laser threshold is derived starting from Maxwell's equations. Expressions for modal loss and gain are derived. Chapter 3 discusses methods for extracting the quality factor from finite-difference time-domain simulations. Even with large-scale parallel computing, only a short record of the time evolution of the fields can be recorded. To get around this issue, Pade functions are fitted to the available data in the frequency domain. Once the analysis tools have been described and demonstrated, they are applied to the photonic crystal double heterostructure cavity which has been shown to have quality factors in excess of one million and mode volumes on the order of a cubic wavelength. A detailed description of the spectral and modal properties of heterostructure cavities is presented, and a method for mode discrimination is discussed. The effect of heat sinking dielectric lower substrates on the optical loss of the heterostructure cavity is investigated, and it is seen that the quality factor is significantly reduced as the index of the lower substrate is increased. A modified heterostructure cavity with glide plane symmetry is shown to have significantly reduced out-of-plane leakage. An optimized design is proposed for continuous wave edge-emitting laser operation. Finally, a novel approach for laser simulation is introduced in which a

  18. Outbursts and cavities in comets

    NASA Astrophysics Data System (ADS)

    Ipatov, Sergei

    Based on analysis of the images made during the first 13 minutes after the collision of the impact module of the Deep Impact (DI) spacecraft with Comet 9P/Tempel 1, Ipatov & A'Hearn [1] studied time variations of ejection of material after this impact. They showed that, besides the normal ejection, at time t_{e} after the DI collision between 8 s and 60 s there was a considerable additional ejection (a triggered outburst) of small (micron size) particles. It increased the mean velocities of observed small ejected particles (compared with the normal ejection). The outburst could be caused by excavation of a large cavity with dust and gas under pressure. The largest cavity excavated after the collision could be relatively deep because a considerable excess ejection lasted during about 50 s. Schultz et al. [2] concluded that the diameter d_{tc} of the DI transient crater was about 200 m. Some authors support smaller values of d_{tc}. The depth of the DI crater at t_{e}=8 s was estimated in [3] to be about 6 m for d_{tc}=200 m and 4 m for d_{tc}=100 m. The distance between the pre-impact surface of Comet 9P/Tempel 1 and the upper border of the largest excavated cavity equal to about 4-6 m, and sizes of particles inside the cavities of a few microns are in good agreement with the results obtained by Kossacki & Szutowicz [4]. In their models of the explosion of Comet 17P/Holmes, the initial sublimation front of the CO ice was located at a depth of 4 m, 10 m, or 20 m, and calculations were finished when the CO pressure exceeded the threshold value 10 kPa. It was shown that the pressure of CO vapor can rise to this value only when the nucleus is composed of very fine grains, a few microns in radius. The porous structure of comets provides enough space for sublimation. The projection of the velocity of the leading edge of the DI cloud (onto the plane perpendicular to the line of sight) was about 100-200 m/s and is typical for outburst particles ejected from comets

  19. Design of the ILC Crab Cavity System

    SciTech Connect

    Adolphsen, C.; Beard, C.; Bellantoni, L.; Burt, G.; Carter, R.; Chase, B.; Church, M.; Dexter, A.; Dykes, M.; Edwards, H.; Goudket, P; Jenkins, R.; Jones, R.M.; Kalinin, A.; Khabiboulline, T.; Ko, K.; Latina, A.; Li, Z.; Ma, L.; McIntosh, P.; Ng, C.; /SLAC /Daresbury /Fermilab /Cockcroft Inst. Accel. Sci. Tech. /CERN

    2007-08-15

    The International Linear Collider (ILC) has a 14 mrad crossing angle in order to aid extraction of spent bunches. As a result of the bunch shape at the interaction point, this crossing angle at the collision causes a large luminosity loss which can be recovered by rotating the bunches prior to collision using a crab cavity. The ILC baseline crab cavity is a 9-cell superconducting dipole cavity operating at a frequency of 3.9 GHz. In this paper the design of the ILC crab cavity and its phase control system, as selected for the RDR in February 2007 is described in fuller detail.

  20. Cavity-locked ring down spectroscopy

    DOEpatents

    Zare, Richard N.; Paldus, Barbara A.; Harb, Charles C.; Spence, Thomas

    2000-01-01

    Distinct locking and sampling light beams are used in a cavity ring-down spectroscopy (CRDS) system to perform multiple ring-down measurements while the laser and ring-down cavity are continuously locked. The sampling and locking light beams have different frequencies, to ensure that the sampling and locking light are decoupled within the cavity. Preferably, the ring-down cavity is ring-shaped, the sampling light is s-polarized, and the locking light is p-polarized. Transmitted sampling light is used for ring-down measurements, while reflected locking light is used for locking in a Pound-Drever scheme.

  1. Optically coupled cavities for wavelength switching

    NASA Astrophysics Data System (ADS)

    Costazo-Caso, Pablo A.; Granieri, Sergio; Siahmakoun, Azad

    2011-01-01

    An optical bistable device which presents hysteresis behavior is proposed and experimentally demonstrated. The system finds applications in wavelength switching, pulse reshaping and optical bistability. It is based on two optically coupled cavities named master and slave. Each cavity includes a semiconductor optical amplifier (SOA), acting as the gain medium of the laser, and two pair of fiber Bragg gratings (FBG) which define the lasing wavelength (being different in each cavity). Finally, a variable optical coupler (VOC) is employed to couple both cavities. Experimental characterization of the system performance is made analyzing the effects of the coupling coefficient between the two cavities and the driving current in each SOA. The properties of the hysteretic bistable curve and switching can be controlled by adjusting these parameters and the loss in the cavities. By selecting the output wavelength (λ1 or λ2) with an external filter it is possible to choose either the invert or non-invert switched signal. Experiments were developed employing both optical discrete components and a photonic integrated circuit. They show that for 8 m-long cavities the maximum switching frequency is about 500 KHz, and for 4 m-long cavities a minimum rise-time about 21 ns was measured. The switching time can be reduced by shortening the cavity lengths and using photonic integrated circuits.

  2. Quantum teleportation with atoms trapped in cavities

    SciTech Connect

    Cho, Jaeyoon; Lee, Hai-Woong

    2004-09-01

    We propose a scheme to implement the quantum teleportation protocol with single atoms trapped in cavities. The scheme is based on the adiabatic passage and the polarization measurement. We show that it is possible to teleport the internal state of an atom trapped in a cavity to an atom trapped in another cavity with the success probability of 1/2 and the fidelity of 1. The scheme is resistant to a number of considerable imperfections such as the violation of the Lamb-Dicke condition, weak atom-cavity coupling, spontaneous emission, and detection inefficiency.

  3. Theory of clustered-cavity gyroklystron

    NASA Astrophysics Data System (ADS)

    Nusinovich, G. S.; Antonsen, T. M.; Guo, H.; Granatstein, V. L.

    2002-09-01

    An analytical theory of a new device configuration, a clustered-cavity gyroklystron, is developed. The device considered has two clusters of cavities: an input cluster and an output cluster. The results show that, by using a cluster cavity concept, the bandwidth of gyroklystrons can be enlarged significantly without sacrifice of gain or efficiency which may lead to the development of a new type of high power, moderate bandwidth millimeter-wave amplifier. The theory has also been used to analyze the effect of stagger tuning between cavity frequencies within a single cluster, as well as between different clusters on the bandwidth and gain of the device.

  4. Mechanical Properties of Ingot Nb Cavities

    SciTech Connect

    Ciovati, Gianluigi; Dhakal, Pashupati; Kneisel, Peter; Mammosser, John; Matalevich, Joseph; Rao Myneni, Ganapati

    2014-07-01

    This contribution presents the results of measurements of the resonant frequency and of strain along the contour of a single-cell cavity made of ingot Nb subjected to increasing uniform differential pressure, up to 6 atm. The data were used to infer mechanical properties of this material after cavity fabrication, by comparison with the results from simulation calculations done with ANSYS. The objective is to provide useful information about the mechanical properties of ingot Nb cavities which can be used in the design phase of SRF cavities intended to be built with this material.

  5. Negative Dielectric Constant Material Based on Ion Conducting Materials

    NASA Technical Reports Server (NTRS)

    Gordon, Keith L. (Inventor); Kang, Jin Ho (Inventor); Park, Cheol (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

    2014-01-01

    Metamaterials or artificial negative index materials (NIMs) have generated great attention due to their unique and exotic electromagnetic properties. One exemplary negative dielectric constant material, which is an essential key for creating the NIMs, was developed by doping ions into a polymer, a protonated poly(benzimidazole) (PBI). The doped PBI showed a negative dielectric constant at megahertz (MHz) frequencies due to its reduced plasma frequency and an induction effect. The magnitude of the negative dielectric constant and the resonance frequency were tunable by doping concentration. The highly doped PBI showed larger absolute magnitude of negative dielectric constant at just above its resonance frequency than the less doped PBI.

  6. Contextual Risk, Maternal Negative Emotionality, and the Negative Emotion Dysregulation of Preschool Children from Economically Disadvantaged Families

    ERIC Educational Resources Information Center

    Brown, Eleanor D.; Ackerman, Brian P.

    2011-01-01

    Research Findings: This study examined relations between contextual risk, maternal negative emotionality, and preschool teacher reports of the negative emotion dysregulation of children from economically disadvantaged families. Contextual risk was represented by cumulative indexes of family and neighborhood adversity. The results showed a direct…

  7. Kriging without negative weights

    SciTech Connect

    Szidarovszky, F.; Baafi, E.Y.; Kim, Y.C.

    1987-08-01

    Under a constant drift, the linear kriging estimator is considered as a weighted average of n available sample values. Kriging weights are determined such that the estimator is unbiased and optimal. To meet these requirements, negative kriging weights are sometimes found. Use of negative weights can produce negative block grades, which makes no practical sense. In some applications, all kriging weights may be required to be nonnegative. In this paper, a derivation of a set of nonlinear equations with the nonnegative constraint is presented. A numerical algorithm also is developed for the solution of the new set of kriging equations.

  8. Negative birefringent polyimide films

    NASA Technical Reports Server (NTRS)

    Harris, Frank W. (Inventor); Cheng, Stephen Z. D. (Inventor)

    1994-01-01

    A negative birefringent film, useful in liquid crystal displays, and a method for controlling the negative birefringence of a polyimide film is disclosed which allows the matching of an application to a targeted amount of birefringence by controlling the degree of in-plane orientation of the polyimide by the selection of functional groups within both the diamine and dianhydride segments of the polyimide which affect the polyimide backbone chain rigidity, linearity, and symmetry. The higher the rigidity, linearity and symmetry of the polyimide backbone, the larger the value of the negative birefringence of the polyimide film.

  9. Characterization of oscillatory instability in lid driven cavity flows using lattice Boltzmann method

    PubMed Central

    Anupindi, Kameswararao; Lai, Weichen; Frankel, Steven

    2014-01-01

    In the present work, lattice Boltzmann method (LBM) is applied for simulating flow in a three-dimensional lid driven cubic and deep cavities. The developed code is first validated by simulating flow in a cubic lid driven cavity at 1000 and 12000 Reynolds numbers following which we study the effect of cavity depth on the steady-oscillatory transition Reynolds number in cavities with depth aspect ratio equal to 1, 2 and 3. Turbulence modeling is performed through large eddy simulation (LES) using the classical Smagorinsky sub-grid scale model to arrive at an optimum mesh size for all the simulations. The simulation results indicate that the first Hopf bifurcation Reynolds number correlates negatively with the cavity depth which is consistent with the observations from two-dimensional deep cavity flow data available in the literature. Cubic cavity displays a steady flow field up to a Reynolds number of 2100, a delayed anti-symmetry breaking oscillatory field at a Reynolds number of 2300, which further gets restored to a symmetry preserving oscillatory flow field at 2350. Deep cavities on the other hand only attain an anti-symmetry breaking flow field from a steady flow field upon increase of the Reynolds number in the range explored. As the present work involved performing a set of time-dependent calculations for several Reynolds numbers and cavity depths, the parallel performance of the code is evaluated a priori by running the code on up to 4096 cores. The computational time required for these runs shows a close to linear speed up over a wide range of processor counts depending on the problem size, which establishes the feasibility of performing a thorough search process such as the one presently undertaken. PMID:24587561

  10. Characterization of oscillatory instability in lid driven cavity flows using lattice Boltzmann method.

    PubMed

    Anupindi, Kameswararao; Lai, Weichen; Frankel, Steven

    2014-03-20

    In the present work, lattice Boltzmann method (LBM) is applied for simulating flow in a three-dimensional lid driven cubic and deep cavities. The developed code is first validated by simulating flow in a cubic lid driven cavity at 1000 and 12000 Reynolds numbers following which we study the effect of cavity depth on the steady-oscillatory transition Reynolds number in cavities with depth aspect ratio equal to 1, 2 and 3. Turbulence modeling is performed through large eddy simulation (LES) using the classical Smagorinsky sub-grid scale model to arrive at an optimum mesh size for all the simulations. The simulation results indicate that the first Hopf bifurcation Reynolds number correlates negatively with the cavity depth which is consistent with the observations from two-dimensional deep cavity flow data available in the literature. Cubic cavity displays a steady flow field up to a Reynolds number of 2100, a delayed anti-symmetry breaking oscillatory field at a Reynolds number of 2300, which further gets restored to a symmetry preserving oscillatory flow field at 2350. Deep cavities on the other hand only attain an anti-symmetry breaking flow field from a steady flow field upon increase of the Reynolds number in the range explored. As the present work involved performing a set of time-dependent calculations for several Reynolds numbers and cavity depths, the parallel performance of the code is evaluated a priori by running the code on up to 4096 cores. The computational time required for these runs shows a close to linear speed up over a wide range of processor counts depending on the problem size, which establishes the feasibility of performing a thorough search process such as the one presently undertaken. PMID:24587561

  11. Optical bistability and second-harmonic generation in thin film coupled cavity photonic crystal structures

    NASA Astrophysics Data System (ADS)

    Diao, Liyong

    This thesis deals with design, fabrication and modeling of bistable and multi-stable switching dynamics and second-harmonic generation in two groups of thin film coupled cavity photonic crystal structures. The first component studies optical bistability and multistability in such structures. Optical bistability and multistability are modelled by a nonlinear transfer matrix method. The second component is focused on the modelling and experimental measurement of second-harmonic generation in such structures. It is found that coupled cavity structures can reduce the threshold and index change for bistable operation, but single cavity structures can do the same. However, there is a clear advantage in using coupled cavity structures for multistability in that the threshold for multistability can be reduced. Second-harmonic generation is enhanced by field localization due to the resonant effect at the fundamental wavelength in single and coupled cavity structures by simulated and measured results. The work in this thesis makes three significant contributions. First, in the successful fabrication of thin film coupled cavity structures, the simulated linear transmissions of such structures match those of the fabricated structures almost exactly. Second, the newly defined figure of merit at the maximum transmission point on the bistable curve can be used to compare the material damage tolerance to any other Kerr effect nonlinear gate. Third, the simulated second-harmonic generation agrees excellently with experimental results. More generally optical thin film fabrication has commercial applications in many industry sections, such as electronics, opto-electronics, optical coating, solar cell and MEMS.

  12. [The influence of breathing mode on the oral cavity].

    PubMed

    Surtel, Anna; Klepacz, Robert; Wysokińska-Miszczuk, Joanna

    2015-12-01

    Nose breathing is one of the key factors in the proper development and functioning of the oral cavity. The air passing through the nasal cavity is warmed and humidified while dust and other particulate matter is removed. It is also important as far as bone formation is concerned. The obstruction or congestions of the upper respiratory tract may negatively affect the correct and most optimal (nasal) respiratory tract. The switch from nasal to mouth breathing may lead to serious clinical consequences. Children with the clinical diagnosis of mouth breathing are usually pale, apathetic and they lack concentration and often get tired. Disorders resulting from hypoxy may also be the reason from sleep disturbances, such as frequent waking-up, nocturia, difficulties falling aslee. The main clinical manifestations of mouth breathing appear in the craniofacial structures. Mouth breathers frequently suffer from dental malocclusions and craniofacial bone abnormalities. Chronic muscle tension around the oral cavity could result in the widening of cranio-vertebral angle, posterior position of mandibula and narrow maxillary arch. Among dental alterations the most common are class II malocclusion (total or partial) with the protrusion of the anterior teeth, cross bite (unilateral or bilateral), anterior open bite and primary crowded teeth. Apart from malocclusion, chronic gingivitis, periodontitis, candida infections and halitosis are frequently present in mouth--breathing patients. PMID:26802697

  13. Mode selectivity study of vertical-cavity surface-emitting lasers

    SciTech Connect

    Liu, G.; Seurin, J.; Chuang, S.L.; Babic, D.I.; Corzine, S.W.; Tan, M.; Barnes, D.C.; Tiouririne, T.N.

    1998-08-01

    Mode selectivity of an air-post index-guided vertical-cavity surface-emitting laser structure operating at 1550 nm is investigated using a full-vector Maxwell-equation solver with a finite-difference time-domain method. The resonance wavelengths, quality factors, and spatial field distributions are calculated for the three lowest-order modes. Transverse-mode competition is quantitatively described as a function of the cavity size and the pillar etch depth. {copyright} {ital 1998 American Institute of Physics.}

  14. Higher order mode damping in a five-cell superconducting rf cavity with a photonic band gap coupler cell

    NASA Astrophysics Data System (ADS)

    Arsenyev, Sergey A.; Temkin, Richard J.; Shchegolkov, Dmitry Yu.; Simakov, Evgenya I.; Boulware, Chase H.; Grimm, Terry L.; Rogacki, Adam R.

    2016-08-01

    We present a study of higher order mode (HOM) damping in the first multicell superconducting radio-frequency (SRF) cavity with a photonic band gap (PBG) coupler cell. Achieving higher average beam currents is particularly desirable for future light sources and particle colliders based on SRF energy-recovery linacs (ERLs). Beam current in ERLs is limited by the beam breakup instability, caused by parasitic HOMs interacting with the beam in accelerating cavities. A PBG cell incorporated in an accelerating cavity can reduce the negative effect of HOMs by providing a frequency selective damping mechanism, thus allowing significantly higher beam currents. The five-cell cavity with a PBG cell was designed and optimized for HOM damping. Monopole and dipole HOMs were simulated. The SRF cavity was fabricated and tuned. External quality factors for some HOMs were measured in a cold test. The measurements agreed well with the simulations.

  15. Highly sensitive temperature sensor based on cascaded polymer-microbubble cavities by employing a subtraction between reciprocal thermal responses.

    PubMed

    Cao, Kunjian; Liu, Yi; Qu, Shiliang

    2016-09-01

    A miniature, robust, and highly sensitive optical fiber temperature sensor based on cascaded polymer-microbubble cavities was fabricated by polymer-filling and subsequent heat-curing process. The expansion of polymer cavity results in the compression of microbubble cavity when the sensor is heated. We demodulated the interference spectrum by means of the fast-Fourier transform (FFT) and signal filtering. Since the thermal response of the polymer cavity is positive and that of the microbubble cavity is negative, a high sensitivity of the temperature sensor is achieved by a subtraction between the two reciprocal thermal responses. Experimental results show that the sensitivity of the temperature sensor is as high as 5.013 nm/°C in the measurement range between 20 °C and 55 °C. Meanwhile, such a sensor has potential for mass production, owing to the simple, nontoxic, and cost-effective process of fabrication. PMID:27607669

  16. Negative electrode composition

    DOEpatents

    Kaun, Thomas D.; Chilenskas, Albert A.

    1982-01-01

    A secondary electrochemical cell and a negative electrode composition for use therewith comprising a positive electrode containing an active material of a chalcogen or a transiton metal chalcogenide, a negative electrode containing a lithium-aluminum alloy and an amount of a ternary alloy sufficient to provide at least about 5 percent overcharge capacity relative to a negative electrode solely of the lithium-aluminum alloy, the ternary alloy comprising lithium, aluminum, and iron or cobalt, and an electrolyte containing lithium ions in contact with both of the positive and the negative electrodes. The ternary alloy is present in the electrode in the range of from about 5 percent to about 50 percent by weight of the electrode composition and may include lithium-aluminum-nickel alloy in combination with either the ternary iron or cobalt alloys. A plurality of series connected cells having overcharge capacity can be equalized on the discharge side without expensive electrical equipment.

  17. Logo and Negative Numbers.

    ERIC Educational Resources Information Center

    Strawn, Candace A.

    1998-01-01

    Describes LOGO's turtle graphics capabilities based on a sixth-grade classroom's activities with negative numbers and Logo programming. A sidebar explains LOGO and offers suggestions to teachers for using LOGO effectively. (LRW)

  18. Atomic negative ions

    SciTech Connect

    Brage, T.

    1991-01-01

    We review some of the recent progress in the studies of alkaline-earth, negative ions. Computations of autodetachment rates, electron affinities and transition wavelengths are discussed and some new and improved results are given.

  19. Atomic negative ions

    SciTech Connect

    Brage, T.

    1991-12-31

    We review some of the recent progress in the studies of alkaline-earth, negative ions. Computations of autodetachment rates, electron affinities and transition wavelengths are discussed and some new and improved results are given.

  20. Negative affixes in medical English.

    PubMed

    Dzuganova, B

    2006-01-01

    Many medical terms have negative meaning expressed by means of a negative prefix or suffix. The most frequently used negative prefixes are: a-, dis-, in-, non-, and un-. There is only one negative suffix -less (Ref. 15). PMID:17125069

  1. A non-uniform three-gap buncher cavity with suppression of transverse-electromagnetic mode leakage in the triaxial klystron amplifier

    SciTech Connect

    Qi, Zumin; Zhang, Jun Zhong, Huihuang; Zhu, Danni; Qiu, Yongfeng

    2014-01-15

    The triaxial klystron amplifier is an efficient high power relativistic klystron amplifier operating at high frequencies due to its coaxial structure with large radius. However, the coaxial structures result in coupling problems among the cavities as the TEM mode is not cut-off in the coaxial tube. Therefore, the suppression of the TEM mode leakage, especially the leakage from the buncher cavity to the input cavity, is crucial in the design of a triaxial klystron amplifier. In this paper, a non-uniform three-gap buncher cavity is proposed to suppress the TEM mode leakage. The cold cavity analysis shows that the non-uniform three-gap buncher cavity can significantly suppress the TEM mode generation compared to a uniform three-gap buncher cavity. Particle-in-cell simulation shows that the power leakage to the input cavity is less than 1.5‰ of the negative power in the buncher cavity and the buncher cavity can efficiently modulate an intense relativistic electron beam free of self-oscillations. A fundamental current modulation depth of 117% is achieved by employing the proposed non-uniform buncher cavity into an X-band triaxial amplifier, which results in the high efficiency generation of high power microwave.

  2. Articulation index and hearing handicap.

    PubMed

    Holcomb, L M; Nerbonne, M A; Konkle, D F

    2000-04-01

    This investigation examined the relationship between perceived hearing handicap and the Articulation Index (AI) and the extent to which this relationship was influenced by the variables age, gender, degree of hearing loss, and audiometric slope. Subject age, gender, pure-tone thresholds, and scores for the Self-Assessment of Communication (SAC) and the Significant Other Assessment of Communication (SOAC) were extracted retrospectively from 373 patient files (194 males, 179 females). Correlation analysis revealed a significant (p < .01) negative relationship between AI values and both measures of hearing handicap, and also indicated that SAC/SOAC total scores correlated significantly (p < .01) with each other. Partial correlation analyses revealed that degree of hearing loss was the only variable under study that had substantial influence on the strength of AI/hearing handicap correlations. PMID:10783925

  3. FXR accelerator cavity impedance experiments

    SciTech Connect

    Avalle, C.A.

    1998-01-05

    One of the goals of the present Flash X-Ray (FXR) accelerator upgrade effort [1][2] at Lawrence Livermore National Laboratory (LLNL) is to reduce the cavity transverse impedance, since it has been shown that beam stability is significantly affected by this parameter [3]. Recently, we have evaluated various techniques and cell modifications to accomplish that, both through lab measurements and computer models. A spare cell, identical in every way to cells in the accelerator, was specially modified for the experiments. The impedance measurements were done without the beam, by applying twin-wire techniques. This report describes the results of these experiments and suggests possible cell modifications to improve their performance. The techniques and modifications which are suggested might also be applicable to AHF and DARHT-2 long-pulse accelerator development.

  4. Wigner rotations in laser cavities.

    PubMed

    Başkal, S; Kim, Y S

    2002-08-01

    The Wigner rotation is important in many branches of physics, chemistry, and engineering sciences. It is a group theoretical effect resulting from two Lorentz boosts. The net effect is one boost followed or preceded by a rotation. While the term "Wigner rotation" is derived from Wigner's little group whose transformations leave the four-momentum of a given particle invariant, it is shown that the Wigner rotation is different from the rotations in the little group. This difference is clearly spelled out, and it is shown to be possible to construct the corresponding Wigner rotation from the little-group rotation. It is shown also that the ABCD matrix for light beams in a laser cavity shares the same mathematics as the little-group rotation, from which the Wigner rotation can be constructed. PMID:12241308

  5. Cavity approximation for graphical models.

    PubMed

    Rizzo, T; Wemmenhove, B; Kappen, H J

    2007-07-01

    We reformulate the cavity approximation (CA), a class of algorithms recently introduced for improving the Bethe approximation estimates of marginals in graphical models. In our formulation, which allows for the treatment of multivalued variables, a further generalization to factor graphs with arbitrary order of interaction factors is explicitly carried out, and a message passing algorithm that implements the first order correction to the Bethe approximation is described. Furthermore, we investigate an implementation of the CA for pairwise interactions. In all cases considered we could confirm that CA[k] with increasing k provides a sequence of approximations of markedly increasing precision. Furthermore, in some cases we could also confirm the general expectation that the approximation of order k , whose computational complexity is O(N(k+1)) has an error that scales as 1/N(k+1) with the size of the system. We discuss the relation between this approach and some recent developments in the field. PMID:17677405

  6. Mini-cavity-dumped laser

    NASA Technical Reports Server (NTRS)

    Reed, E.

    1981-01-01

    Lasers for use in high precision satellite ranging systems consist typically of an oscillator followed by several amplifier stages. While the shortest optical pulses are achieved by using a mode locked oscillator, such an oscillator is incompatible with the compact design needed in future, highly mobile systems. The laser oscillator achieves pulse lengths approaching those obtainable by mode locking, but in a much more compact and stable design. The oscillator uses two LiNbO3 Pockels cells inside the resonator. One Q-switches the oscillator, and the other is used in a pulse slicing scheme to cavity dump a portion of the circulating optical energy. The length of the optical output pulse measured at 425 + or - 50 picoseconds.

  7. NASA 1981 photography index

    NASA Technical Reports Server (NTRS)

    1982-01-01

    An index of representative photographs is presented. Color transparencies and black and white glossies of major launches, Mariner spacecraft, Pioneer spacecraft, planets and other space phenomena, Skylab, space shuttle, Viking spacecraft, and Voyager spacecraft are included.

  8. Geophysical observations at cavity collapse

    NASA Astrophysics Data System (ADS)

    Jousset, Philippe; Bazargan-Sabet, Behrooz; Lebert, François; Bernardie, Séverine; Gourry, Jean-Christophe

    2010-05-01

    In Lorraine region (France) salt layers at about 200 meters depth are exploited by Solvay using solution mining methodology which consists in extracting the salt by dissolution, collapsing the cavern overburden during the exploitation phase and finally reclaiming the landscape by creating a water area. In this process, one of the main challenges for the exploiting company is to control the initial 120-m diameter collapse so as to minimize possible damages. In order to detect potential precursors and understand processes associated with such collapses, a wide series of monitoring techniques including micro seismics, broad-band seismology, hydro-acoustic, electromagnetism, gas probing, automatic leveling, continuous GPS, continuous gravity and borehole extensometry was set-up in the frame of an in-situ study carried out by the "Research Group for the Impact and Safety of Underground Works" (GISOS, France). Equipments were set-up well before the final collapse, giving a unique opportunity to analyze a great deal of information prior to and during the collapse process which has been successfully achieved on February the 13th, 2009 by controlling the cavity internal pressure. In this work, we present the results of data recorded by a network of 3 broadband seismometers, 2 accelerometers, 2 tilt-meters and a continuously gravity meter. We relate the variations of the brine pumping rate with the evolutions of the induced geophysical signals and finally we propose a first mechanical model for describing the controlled collapse. Beyond the studied case, extrapolation of the results obtained might contribute to the understanding of uncontrolled cavity collapses, such as pit-craters or calderas at volcanoes.

  9. Helicobacter pylori colonization of the oral cavity: A milestone discovery

    PubMed Central

    Yee, John KC

    2016-01-01

    Over the past several years, the severity of Helicobacter pylori (H. pylori) infections has not significantly diminished. After successful eradication, the annual H. pylori recurrence rate is approximately 13% due to oral H. pylori infection. Established clinical diagnostic techniques do not identify an oral etiologic basis of H. pylori prior to gastric infection. There has been disagreement as to whether oral infection of H. pylori exists or not, with no definite conclusion. In medical practice, negative results with the urea breath test suggest that the stomach infection of H. pylori is cured in these patients. In fact, patients can present negative urea breath test results and yet exhibit H. pylori infection due to oral infection. The present paper provides evidence that H. pylori oral infection is nonetheless present, and the oral cavity represents a secondary site for H. pylori colonization. PMID:26811613

  10. Exploring volumetrically indexed cups

    NASA Astrophysics Data System (ADS)

    Jones, Dustin L.

    2011-03-01

    This article was inspired by a set of 12 cylindrical cups, which are volumetrically indexed; that is to say, the volume of cup n is equal to n times the volume of cup 1. Various sets of volumetrically indexed cylindrical cups are explored. I demonstrate how this children's toy is ripe for mathematical investigation, with connections to geometry, algebra and differential calculus. Students with an understanding of these topics should be able to complete the analysis and related exercises contained herein.

  11. JSC document index

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The Johnson Space Center (JSC) document index is intended to provide a single source listing of all published JSC-numbered documents their authors, and the designated offices of prime responsibility (OPR's) by mail code at the time of publication. The index contains documents which have been received and processed by the JSC Technical Library as of January 13, 1988. Other JSC-numbered documents which are controlled but not available through the JSC Library are also listed.

  12. Folded cavity design for a ruby resonator

    NASA Technical Reports Server (NTRS)

    Arunkumar, K. A.; Trolinger, James D.

    1988-01-01

    A folded cavity laser resonator operating in the TEM(00) mode has been built and tested. The new oscillator configuration leads to an increase in efficiency and to better line narrowing due to the increased number of passes through the laser rod and tuning elements, respectively. The modification is shown to lead to cavity ruggedization.

  13. High-current SRF cavity design

    NASA Astrophysics Data System (ADS)

    Meidlinger, D.; Grimm, T. L.; Hartung, W.

    2006-07-01

    For high current applications, it is desirable for the cavity shape to have a low longitudinal loss factor and to have a high beam-breakup threshold current. This paper briefly describes three different cavities designed for this purpose: a six-cell elliptical cavity for particles traveling at the speed of light, a two-cell elliptical cavity for subluminal particle speeds, and a single cell cavity which uses the TM012 mode for acceleration. SUPERFISH simulations predict the peak fields in both of the elliptical cavities will not exceed the TeSLA values by more than 10% but both will have 28.7% larger apertures. The elliptical designs assume the bunch frequency equals the accelerating mode frequency. The beam pipe radius is chosen so that the cutoff frequency is less than twice that of the accelerating mode. Hence all of the monopole and dipole higher-order modes (HOMs) that can be driven by the beam have low loaded Q values. This simplifies the problem of HOM damping. The TM012 cavity is predicted to have much higher peak fields than a π-mode elliptical cavity, but offers potential advantages from its simplified shape; it is essentially a circular waveguide with curved end plates. This basic shape results in easier fabrication and simplified tuning.

  14. Fast tuning of superconducting microwave cavities

    SciTech Connect

    Sandberg, M.; Wilson, C. M.; Persson, F.; Johansson, G.; Shumeiko, V.; Bauch, T.; Duty, T.; Delsing, P.

    2008-11-07

    Photons are fundamental excitations of electromagnetic fields and can be captured in cavities. For a given cavity with a certain size, the fundamental mode has a fixed frequency f which gives the photons a specific 'color'. The cavity also has a typical lifetime {tau}, which results in a finite linewidth {delta}f. If the size of the cavity is changed fast compared to {tau}, and so that the frequency change {delta}f>>{delta}f, then it is possible to change the 'color' of the captured photons. Here we demonstrate superconducting microwave cavities, with tunable effective lengths. The tuning is obtained by varying a Josephson inductance at one end of the cavity. We show data on four different samples and demonstrate tuning by several hundred linewidths in a time {delta}t<<{tau}. Working in the few photon limit, we show that photons stored in the cavity at one frequency will leak out from the cavity with the new frequency after the detuning. The characteristics of the measured devices make them suitable for different applications such as dynamic coupling of qubits and parametric amplification.

  15. Design of multilamp nonimaging laser pump cavities

    SciTech Connect

    Kuppenheimer, J.D. Jr.

    1989-12-01

    A technique has been developed to design single laser rod, multiple flash lamp pump cavities that allow all of the energy generated by the lamp to pass through the laser rod before entering another lamp cavity. The effective lamp and rod perimeters are matched, guaranteeing maximal concentration and uniformity of pumping.

  16. Geometric Model of a Coronal Cavity

    NASA Technical Reports Server (NTRS)

    Kucera, Therese A.; Gibson, S. E.; Ratawicki, D.; Dove, J.; deToma, G.; Hao, J.; Hudson, H. S.; Marque, C.; McIntosh, P. S.; Reeves, K. K.; Schmidt, D. J.; Sterling, A. C.; Tripathi, D. K.; Williams, D. R.; Zhang, M.

    2010-01-01

    We observed a coronal cavity from August 8-18 2007 during a multi-instrument observing campaign organized under the auspices of the International Heliophysical Year (IHY). Here we present initial efforts to model the cavity with a geometrical streamer-cavity model. The model is based the white-light streamer mode] of Gibson et a]. (2003 ), which has been enhanced by the addition of a cavity and the capability to model EUV and X-ray emission. The cavity is modeled with an elliptical cross-section and Gaussian fall-off in length and width inside the streamer. Density and temperature can be varied in the streamer and cavity and constrained via comparison with data. Although this model is purely morphological, it allows for three-dimensional, multi-temperature analysis and characterization of the data, which can then provide constraints for future physical modeling. Initial comparisons to STEREO/EUVI images of the cavity and streamer show that the model can provide a good fit to the data. This work is part of the effort of the International Space Science Institute International Team on Prominence Cavities

  17. Long Josepshon Junction in a Resonant Cavity

    NASA Astrophysics Data System (ADS)

    Tornes, Ivan

    2005-03-01

    We present a model for an underdamped long Josephson junction coupled to a single-mode electromagnetic cavity, and carry out numerical calculations using this model in various regimes. The coupling may occur through either the electric or the magnetic field of the cavity mode. When a current is injected into the junction, we find that the time-averaged voltage exhibits self-induced resonant steps due to coupling between the current in the junction and the electric field of the cavity mode. These steps are similar to those observed and calculated in small Josephson junctions. When a soliton is present in the junction (corresponding to a quantum of magnetic flux parallel to the junction plates), the SIRS's disappear if the electric field in the cavity is spatially uniform. If the cavity mode has a spatially varying electric field, there is a strong coupling between the soliton and the cavity mode. This coupling causes the soliton to become phase-locked to the cavity mode, and produces step-like anomalies on the soliton branch of the IV characteristics. If the coupling is strong enough, the frequency of the cavity mode is greatly red-shifted from its uncoupled value. We present simple geometrical arguments and a simple analytical model which account for this behavior. This work was supported by NSF grant DMR04-13395.

  18. Developing of superconducting niobium cavities for accelerators

    NASA Astrophysics Data System (ADS)

    Pobol, I. L.; Yurevich, S. V.

    2015-11-01

    The results of a study of structure and mechanical properties of welding joints, superconducting characteristics of the material after joining of welded components of superconducting radio frequency cavities are presented. The paper also describes the results of testing of the RF 1.3 GHz single-cell niobium cavity manufactured in the PTI NAS Belarus.

  19. Large grain cavities from pure niobium ingot

    DOEpatents

    Myneni, Ganapati Rao; Kneisel, Peter; Cameiro, Tadeu

    2012-03-06

    Niobium cavities are fabricated by the drawing and ironing of as cast niobium ingot slices rather than from cold rolled niobium sheet. This method results in the production of niobium cavities having a minimum of grain boundaries at a significantly reduced cost as compared to the production of such structures from cold rolled sheet.

  20. Mode suppression means for gyrotron cavities

    DOEpatents

    Chodorow, Marvin; Symons, Robert S.

    1983-08-09

    In a gyrotron electron tube of the gyro-klystron or gyro-monotron type, having a cavity supporting an electromagnetic mode with circular electric field, spurious resonances can occur in modes having noncircular electric field. These spurious resonances are damped and their frequencies shifted by a circular groove in the cavity parallel to the electric field.

  1. Compact microwave cavity for hydrogen atomic clock

    NASA Technical Reports Server (NTRS)

    Zhang, Dejun; Zhang, Yan; Fu, Yigen; Zhang, Yanjun

    1992-01-01

    A summary is presented that introduces the compact microwave cavity used in the hydrogen atomic clock. Special emphasis is placed on derivation of theoretical calculating equations of main parameters of the microwave cavity. A brief description is given of several methods for discriminating the oscillating modes. Experimental data and respective calculated values are also presented.

  2. New generic indexing technology

    NASA Technical Reports Server (NTRS)

    Freeston, Michael

    1996-01-01

    There has been no fundamental change in the dynamic indexing methods supporting database systems since the invention of the B-tree twenty-five years ago. And yet the whole classical approach to dynamic database indexing has long since become inappropriate and increasingly inadequate. We are moving rapidly from the conventional one-dimensional world of fixed-structure text and numbers to a multi-dimensional world of variable structures, objects and images, in space and time. But, even before leaving the confines of conventional database indexing, the situation is highly unsatisfactory. In fact, our research has led us to question the basic assumptions of conventional database indexing. We have spent the past ten years studying the properties of multi-dimensional indexing methods, and in this paper we draw the strands of a number of developments together - some quite old, some very new, to show how we now have the basis for a new generic indexing technology for the next generation of database systems.

  3. Cavity cooling a single charged levitated nanosphere.

    PubMed

    Millen, J; Fonseca, P Z G; Mavrogordatos, T; Monteiro, T S; Barker, P F

    2015-03-27

    Optomechanical cavity cooling of levitated objects offers the possibility for laboratory investigation of the macroscopic quantum behavior of systems that are largely decoupled from their environment. However, experimental progress has been hindered by particle loss mechanisms, which have prevented levitation and cavity cooling in a vacuum. We overcome this problem with a new type of hybrid electro-optical trap formed from a Paul trap within a single-mode optical cavity. We demonstrate a factor of 100 cavity cooling of 400 nm diameter silica spheres trapped in vacuum. This paves the way for ground-state cooling in a smaller, higher finesse cavity, as we show that a novel feature of the hybrid trap is that the optomechanical cooling becomes actively driven by the Paul trap, even for singly charged nanospheres. PMID:25860743

  4. Casimir forces of metallic microstructures into cavities

    NASA Astrophysics Data System (ADS)

    Kenanakis, George; Soukoulis, Costas M.; Economou, Eleftherios N.

    2015-08-01

    A theoretical estimate of the Casimir force of a metallic structure embedded into a cubic cavity is proposed. We demonstrate that by calculating the eigenmodes of the system we can determine the Casimir force, which can be either attractive or repulsive, by simply changing the geometry of the structures relative to the walls of the cavity. In this analysis, several cases of structures are taken into account, from rectangular slabs to chiral "omega" particles, and the predicted data are consistent with recent literature. We demonstrate that the sidewalls of the studied cavity contribute decisively to the repulsive Casimir force between the system and the nearby top surface of the cavity. Finally, we provide evidence that the medium embedded into the studied cavity (and especially its permittivity) can change the intensity of the Casimir force, while its repulsive nature, once established (owing to favorable geometrical features), remains quite robust.

  5. Cavity cooling below the recoil limit.

    PubMed

    Wolke, Matthias; Klinner, Julian; Keßler, Hans; Hemmerich, Andreas

    2012-07-01

    Conventional laser cooling relies on repeated electronic excitations by near-resonant light, which constrains its area of application to a selected number of atomic species prepared at moderate particle densities. Optical cavities with sufficiently large Purcell factors allow for laser cooling schemes, avoiding these limitations. Here, we report on an atom-cavity system, combining a Purcell factor above 40 with a cavity bandwidth below the recoil frequency associated with the kinetic energy transfer in a single photon scattering event. This lets us access a yet-unexplored regime of atom-cavity interactions, in which the atomic motion can be manipulated by targeted dissipation with sub-recoil resolution. We demonstrate cavity-induced heating of a Bose-Einstein condensate and subsequent cooling at particle densities and temperatures incompatible with conventional laser cooling. PMID:22767925

  6. Large Grain Superconducting RF Cavities at DESY

    SciTech Connect

    Singer, W.; Brinkmann, A.; Ermakov, A.; Iversen, J.; Kreps, G.; Matheisen, A.; Proch, D.; Reschke, D.; Singer, X.; Spiwek, M.; Wen, H.; Brokmeier, H. G.

    2007-08-09

    The DESY R and D program on cavities fabricated from large grain niobium explores the potential of this material for the production of approx. 1000 nine-cell cavities for the European XFEL. The program investigates basic material properties, comparing large grain material to standard sheet niobium, as well as fabrication and preparation aspects. Several single-cell cavities of TESLA shape have been fabricated from large grain niobium. A gradient up to 41 MV/m at Q0 = 1.4{center_dot}1010 (TB = 2K) was measured after electropolishing. The first three large grain nine-cell cavities worldwide have been produced under contract of DESY with ACCEL Instruments Co. The first tests have shown that all three cavities reach an accelerating gradient up to 30 MV/m after BCP (Buffered Chemical Polishing) treatment, what exceeds the XFEL requirements for RF test in the vertical cryostat.

  7. Performance of 3-cell Seamless Niobium cavities

    SciTech Connect

    Kneisel, Peter K.; Ciovati, Gianluigi; Jelezov, I.; Singer, W.; Singer, X.

    2009-11-01

    In the last several months we have surface treated and cryogenically tested three TESLA-type 3-cell cavities, which had been manufactured at DESY as seamless assemblies by hydroforming. The cavities were completed at JLab with beam tube/flange assemblies. All three cavities performed very well after they had been post-purified with titanium at 1250C for 3 hrs. The cavities, two of which consisted of an end cell and 2 center cells and one was a center cell assembly, achieved gradients of Eacc = 32 MV/m, 34 MV/m and 35 MV/m without quenches. The performance was limited by the appearance of the “Q-drop” in the absence of field emission. This contribution reports about the various measurements undertaken with these cavities.

  8. Voltage control of cavity magnon polariton

    NASA Astrophysics Data System (ADS)

    Kaur, S.; Yao, B. M.; Rao, J. W.; Gui, Y. S.; Hu, C.-M.

    2016-07-01

    We have experimentally investigated the microwave transmission of the cavity-magnon-polariton (CMP) generated by integrating a low damping magnetic insulator onto a 2D microwave cavity. The high tunability of our planar cavity allows the cavity resonance frequency to be precisely controlled using a DC voltage. By appropriately tuning the voltage and magnetic bias, we can observe the cavity photon magnon coupling and the magnetic coupling between a magnetostatic mode and the generated CMP. The dispersion of the generated CMP was measured by either tuning the magnetic field or the applied voltage. This electrical control of CMP may open up avenues for designing advanced on-chip microwave devices that utilize light-matter interaction.

  9. Fast thermometry for superconducting rf cavity testing

    SciTech Connect

    Orris, Darryl; Bellantoni, Leo; Carcagno, Ruben H.; Edwards, Helen; Harms, Elvin Robert; Khabiboulline, Timergali N.; Kotelnikov, Sergey; Makulski, Andrzej; Nehring, Roger; Pischalnikov, Yuriy; /Fermilab

    2007-06-01

    Fast readout of strategically placed low heat capacity thermometry can provide valuable information of Superconducting RF (SRF) cavity performance. Such a system has proven very effective for the development and testing of new cavity designs. Recently, several resistance temperature detectors (RTDs) were installed in key regions of interest on a new 9 cell 3.9 GHz SRF cavity with integrated HOM design at FNAL. A data acquisition system was developed to read out these sensors with enough time and temperature resolution to measure temperature changes on the cavity due to heat generated from multipacting or quenching within power pulses. The design and performance of the fast thermometry system will be discussed along with results from tests of the 9 cell 3.9GHz SRF cavity.

  10. Microphonics Measurements in SRF Cavities for RIA

    SciTech Connect

    Kelly, M.P.; Fuerst, Joel; Kedzie, M.; Sharamentov, S.I.; Shepard, Kenneth; Delayen, Jean

    2003-05-01

    Phase stabilization of the RIA drift tube cavities in the presence of microphonics will be a key issue for RIA. Due to the relatively low beam currents (lte 0.5 pmA) required for the RIA driver, microphonics will impact the rf power required to control the cavity fields. Microphonics measurements on the ANL Beta=0.4 single spoke cavity and on the ANL Beta=0.4 two-cell spoke cavity have been performed many at high fields and using a new "cavity resonance monitor" device developed in collaboration with JLAB. Tests on a cold two-cell spoke are the first ever on a multi-cell spoke geometry. The design is essentially a production model with an integral stainless steel housing to hold the liquid helium bath.

  11. [Hemangiopericytoma in nasal cavity: a case report].

    PubMed

    Hu, Honghai; Shi, Qifeng; Chen, Jidong

    2015-05-01

    We report a case of a 46 year old female patient with nasal hemangiopericytoma. She complained of left nasal congestion, pus snot for 10 years, sometimes with left nasal bleeding. Physical examination: in the left nasal tract saw red soft neoplasm, roughness surface, easy bleeding when touched. Sinus CT shows: bilateral maxillary sinus, ethmoid sinus, sphenoid sinus and the left posterior nasal cavity lesions, considering inflammation with the formation of polyps, tumor not excluded. The left nasal cavity neoplasm biopsy shows: hemangioma of left nasal cavity. After admission in general anesthesia, we do transnasal endoscopic sinus openning operation and the left nasal cavity neoplasm resection. Postoperative pathological examination shows: the left nasal cavity hemangiopericytoma. Immunohistochemical showed: Vimentin(+), Smooth muscle actin(+), Desmin(-), endothelial cells CD31(-) and CD34(-). No postoperative radiotherapy or chemotherapy, no tumor recurrence. After one year of follow-up, the contact was lost. PMID:26281069

  12. Vertical-Cavity Surface-Emitting Lasers

    NASA Astrophysics Data System (ADS)

    Wilmsen, Carl W.; Temkin, Henryk; Coldren, Larry A.

    2002-01-01

    1. Introduction to VCSELs L. A. Coldren, C. W. Wilmsen and H. Temkin; 2. Fundamental issues in VCSEL design L. A. Coldren and Eric R. Hegblom; 3. Enhancement of spontaneous emission in microcavities E. F. Schubert and N. E. J. Hunt; 4. Epitaxy of vertical-cavity lasers R. P. Schneider Jr and Y. H. Young; 5. Fabrication and performance of vertical-cavity surface-emitting lasers Kent D. Choquette and Kent Geib; 6. Polarization related properties of vertical cavity lasers Dmitri Kuksenkov and Henryk Temkin; 7. Visible light emitting vertical cavity lasers Robert L. Thornton; 8. Long-wavelength vertical-cavity lasers Dubrakovo I. Babic, Joachim Piprek and John E. Bowers; 9. Overview of VCSEL applications Richard C. Williamson; 10. Optical interconnection applications and required characteristics Kenichi Kasahara; 11. VCSEL-based fiber-optic data communications Kenneth Hahn and Kirk Giboney; 12. VCSEL-based smart pixels for free space optoelectronic processing C. W. Wilmsen.

  13. Optical nanofiber-based photonic crystal cavity.

    PubMed

    Nayak, K P; Zhang, Pengfei; Hakuta, K

    2014-01-15

    We demonstrate the fabrication of photonic crystal (PhC) cavities on optical nanofibers using femtosecond laser ablation. PhC cavities with cavity lengths varying from 0.54 to 3.43 mm are fabricated by controlling the profile of the nanocrater array formed on the nanofiber. Such PhC cavities show high transmission of 87% for a finesse of 39. For higher finesse values from 150 to 500, the transmission can still be maintained at 20%-25%. Due to the strong confinement of the field and the efficient coupling to single-mode optical fibers, such nanofiber-based PhC cavities may become an interface between quantum and classical networks. PMID:24562114

  14. Aligning a reflection cavity by Anderson's method.

    PubMed

    Reasenberg, Robert D

    2012-06-01

    The sounding rocket principle of equivalence measurement uses a set of four laser gauges operating in Fabry-Perot cavities to determine the relative acceleration of two test masses that are chemically different. One end of each cavity is a flat mirror on a test mass. Because the test masses are unconstrained and thus expected to rotate slightly during measurement, and because the distance measurements are made at the sub-picometer level, it is essential to have real-time alignment of the beam entering the cavity. However, the cavity must be used in reflection and space is limited. We show that Anderson's alignment method can be used in reflection, but that it requires that the Fabry-Perot cavity have mirrors with significantly unequal reflectivities. PMID:22695543

  15. Low Froude number water entry cavity dynamics

    NASA Astrophysics Data System (ADS)

    Kominiarczuk, Jakub K.

    2005-11-01

    We analyze the dynamics of the projectile and the water entry cavity in low Froude number water impact where both kinetic and gravitational potential energy play a role. An experimental investigation is conducted where the impact and cavity development of billiard balls hitting a calm water surface at Froude number of O(10) are captured using high speed video camera at 1000 to 2000 frames per second. The phenomena associated with water entry at low impact speeds are complex as gravity, cavity pressure, flow separation, and splash generation significantly influence the cavity shape, surface closure and pinch off. For comparison, an existing analytical theory for the dynamics of water entry cavities for very high speeds is generalized and extended to low Froude number regime. In particular, this closed-form solution now accounts for effects of gravity and flow separation around the projectile. The comparison between the analytic solution and experimental results is excellent.

  16. Negative running can prevent eternal inflation

    SciTech Connect

    Kinney, William H.; Freese, Katherine E-mail: ktfreese@umich.edu

    2015-01-01

    Current data from the Planck satellite and the BICEP2 telescope favor, at around the 2 σ level, negative running of the spectral index of curvature perturbations from inflation. We show that for negative running α < 0, the curvature perturbation amplitude has a maximum on scales larger than our current horizon size. A condition for the absence of eternal inflation is that the curvature perturbation amplitude always remain below unity on superhorizon scales. For current bounds on n{sub S} from Planck, this corresponds to an upper bound of the running α < −9 × 10{sup −5}, so that even tiny running of the scalar spectral index is sufficient to prevent eternal inflation from occurring, as long as the running remains negative on scales outside the horizon. In single-field inflation models, negative running is associated with a finite duration of inflation: we show that eternal inflation may not occur even in cases where inflation lasts as long as 10{sup 4} e-folds.

  17. A parametric study on the PD pulses activity within micro-cavities

    NASA Astrophysics Data System (ADS)

    Ganjovi, Alireza A.

    2016-03-01

    A two-dimensional kinetic model has been used to parametric investigation of the spark-type partial discharge pulses inside the micro-cavities. The model is based on particle-in-cell methods with Monte Carlo Collision techniques for modeling of collisions. Secondary processes like photo-emission and cathode-emission are considered. The micro-cavity may be sandwiched between two metallic conductors or two dielectrics. The discharge within the micro-cavity is studied in conjunction with the external circuit. The model is used to successfully simulate the evolution of the discharge and yield useful information about the build-up of space charge within the micro-cavity and the consequent modification of the applied electric field. The phase-space scatter plots for electrons, positive, and negative ions are obtained in order to understand the manner in which discharge progresses over time. The rise-time and the magnitude of the discharge current pulse are obtained and are seen to be affected by micro-cavity dimensions, gas pressure within the micro-cavity, and the permittivity of surrounding dielectrics. The results have been compared with existing experimental, theoretical, and computational results, wherever possible. An attempt has been made to understand the nature of the variations in terms of the physical processes involved.

  18. Superconducting cavity tuner performance at CEBAF

    SciTech Connect

    Marshall, J.; Preble, J.; Schneider, W.

    1993-06-01

    At the Continuous Electron Beam Accelerator Facility (CEBAF), a 4 GeV, multipass CW electron beam is to be accelerated by 338 SRF, 5-cell niobium cavities operating at a resonant frequency of 1497 MHz. Eight cavities arranged as four pairs comprise a cyromodule, a croygenically isolated linac subdivision. The frequency is controlled by a mechanical tune attached to the first and fifth cell of the cavity which elastically deforms the cavity and thereby alters its resonant frequency. The tuner is driven by a stepper motor mounted external to the cryomodule that transfers torque through two rotary feedthroughs. A linear variable differential transducer (LVDT) mounted on the tuner monitors the displacement, and two limit switches interlock the movement beyond a 400 kHz bandwidth. Since the cavity has a loaded Q of 6.6 {center_dot} 10{sup 6}, the control system must maintain the frequency of the cavity to within {plus_minus} 50 Hz of the drive frequency for efficient coupling. This requirement is somewhat difficult to achieve since the difference in thermal contractions of the cavity and the tuner creates a frequency hystersis of approximately 10 kHz. The cavity is also subject to frequency shifts due to pressure fluctuations of the helium bath as well as radiation pressure. This requires that each cavity be characterized in terms of frequency change as a function of applied motor steps to allow proper tuning operations. This paper describes the electrical and mechanical performance of the cavity tuner during the commissioning and operation of the cryomodulus manufactured to date.

  19. Design of half-reentrant SRF cavities

    NASA Astrophysics Data System (ADS)

    Meidlinger, M.; Grimm, T. L.; Hartung, W.

    2006-07-01

    The shape of a TeSLA inner cell can be improved to lower the peak surface magnetic field at the expense of a higher peak surface electric field by making the cell reentrant. Such a single-cell cavity was designed and tested at Cornell, setting a world record accelerating gradient [V. Shemelin et al., An optimized shape cavity for TESLA: concept and fabrication, 11th Workshop on RF Superconductivity, Travemünde, Germany, September 8-12, 2003; R. Geng, H. Padamsee, Reentrant cavity and first test result, Pushing the Limits of RF Superconductivity Workshop, Argonne National Laboratory, September 22-24, 2004]. However, the disadvantage to a cavity is that liquids become trapped in the reentrant portion when it is vertically hung during high pressure rinsing. While this was overcome for Cornell’s single-cell cavity by flipping it several times between high pressure rinse cycles, this may not be feasible for a multi-cell cavity. One solution to this problem is to make the cavity reentrant on only one side, leaving the opposite wall angle at six degrees for fluid drainage. This idea was first presented in 2004 [T.L. Grimm et al., IEEE Transactions on Applied Superconductivity 15(6) (2005) 2393]. Preliminary designs of two new half-reentrant (HR) inner cells have since been completed, one at a high cell-to-cell coupling of 2.1% (high- kcc HR) and the other at 1.5% (low- kcc HR). The parameters of a HR cavity are comparable to a fully reentrant cavity, with the added benefit that a HR cavity can be easily cleaned with current technology.

  20. Cavity solitons and localized patterns in a finite-size optical cavity

    SciTech Connect

    Kozyreff, G.; Gelens, L.

    2011-08-15

    In appropriate ranges of parameters, laser-driven nonlinear optical cavities can support a wide variety of optical patterns, which could be used to carry information. The intensity peaks appearing in these patterns are called cavity solitons and are individually addressable. Using the Lugiato-Lefever equation to model a perfectly homogeneous cavity, we show that cavity solitons can only be located at discrete points and at a minimal distance from the edges. Other localized states which are attached to the edges are identified. By interpreting these patterns in an information coding frame, the information capacity of this dynamical system is evaluated. The results are explained analytically in terms of the the tail characteristics of the cavity solitons. Finally, the influence of boundaries and of cavity imperfections on cavity solitons are compared.

  1. Negative pressure wound therapy.

    PubMed

    Thompson, James T; Marks, Malcolm W

    2007-10-01

    Negative pressure wound therapy has become an increasingly important part of wound management. Over the last decade, numerous uses for this method of wound management have been reported, ranging from acute and chronic wounds, to closure of open sternal and abdominal wounds, to assistance with skin grafts. The biophysics behind the success of this treatment largely have focused on increased wound blood flow, increased granulation tissue formation, decreased bacterial counts, and stimulation of wound healing pathways through shear stress mechanisms. The overall success of negative pressure wound therapy has led to a multitude of clinical applications, which are discussed in this article. PMID:17967622

  2. Enhanced sensitivity of a passive optical cavity by an intracavity dispersive medium

    SciTech Connect

    Smith, David D.; Myneni, Krishna; Odutola, Jamiu A.; Diels, J. C.

    2009-07-15

    The pushing of the modes of a Fabry-Perot cavity by an intracavity rubidium cell is measured. The scale factor of the modes is increased by the anomalous dispersion and is inversely proportional to the sum of the effective group index and an additional cavity delay factor that arises from the variation of the Rb absorption over a free spectral range. This additional positive feedback further increases the effect of the anomalous dispersion and goes to zero at the lasing threshold. The mode width does not grow as fast as the scale factor as the intracavity absorption is increased resulting in enhanced measurement sensitivities. For absorptions larger than the scale factor pole, the atom-cavity response is multivalued and mode splitting occurs.

  3. Treatment Options for Recurrent Lip and Oral Cavity Cancer

    MedlinePlus

    ... Cavity and Oropharyngeal Cancer Screening Research Lip and Oral Cavity Cancer Treatment (PDQ®)–Patient Version General Information About Lip and Oral Cavity Cancer Go to Health Professional Version Key Points ...

  4. Treatment Options by Stage (Lip and Oral Cavity Cancer)

    MedlinePlus

    ... Cavity and Oropharyngeal Cancer Screening Research Lip and Oral Cavity Cancer Treatment (PDQ®)–Patient Version General Information About Lip and Oral Cavity Cancer Go to Health Professional Version Key Points ...

  5. Treatment Option Overview (Lip and Oral Cavity Cancer)

    MedlinePlus

    ... Cavity and Oropharyngeal Cancer Screening Research Lip and Oral Cavity Cancer Treatment (PDQ®)–Patient Version General Information About Lip and Oral Cavity Cancer Go to Health Professional Version Key Points ...

  6. Calculate Your Body Mass Index

    MedlinePlus

    ... Can! ) Health Professional Resources Calculate Your Body Mass Index Body mass index (BMI) is a measure of body fat based ... to content Twitter Facebook YouTube Google+ SEARCH | SITE INDEX | ACCESSIBILITY | PRIVACY STATEMENT | FOIA | OIG | CONTACT US National ...

  7. Quarantine document system indexing procedure

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The Quarantine Document System (QDS) is described including the indexing procedures and thesaurus of indexing terms. The QDS consists of these functional elements: acquisition, cataloging, indexing, storage, and retrieval. A complete listing of the collection, and the thesaurus are included.

  8. Low-Level RF Control of Microphonics in Superconducting Spoke-Loaded Cavities

    SciTech Connect

    Conway, Z.A.; Kelly, M.P.; Sharamentov, S.I.; Shepard, K.W.; Davis, G.; Delayen, Jean; Doolittle, Lawrence

    2007-10-01

    This paper presents the results of cw RF frequency control and RF phase-stabilization experiments performed with a piezoelectric fast tuner mechanically coupled to a superconducting, 345 MHz, Ë = 0.5 triple-spoke-loaded cavity operating at 4.2K. The piezoelectric fast tuner damped low-frequency microphonic-noise by an order of magnitude. Two methods of RF phase-stabilization were characterized: overcoupling with negative phase feedback, and also fast mechanical tuner feedback. The Ë = 0.5 triple-spoke-loaded cavity RF field amplitude and phase errors were controlled to ±0.5% and ±30 respectively.

  9. Dynamics of three qubits interacting with electromagnetic field in a lossless cavity

    NASA Astrophysics Data System (ADS)

    Averchenko, Ekaterina; Bashkirov, Eugene K.

    2016-04-01

    We investigated the entanglement dynamics in a quantum system consisting of three two-level atoms resonantly coupled to a single mode electromagnetic field. We considered the dynamics of the system under consideration for Fock and thermal initial cavity states. An explicit analytical solution of the system has been obtained and the entanglement has been studied with the help of the two-qubit negativity. It was also shown that for both initial cavity states the sudden death of two-qubit entanglement takes place.

  10. The Negative Repetition Effect

    ERIC Educational Resources Information Center

    Mulligan, Neil W.; Peterson, Daniel J.

    2013-01-01

    A fundamental property of human memory is that repetition enhances memory. Peterson and Mulligan (2012) recently documented a surprising "negative repetition effect," in which participants who studied a list of cue-target pairs twice recalled fewer targets than a group who studied the pairs only once. Words within a pair rhymed, and…

  11. [Chemotherapies of negative schizophrenia].

    PubMed

    Petit, M; Dollfus, S

    1991-01-01

    Five years ago, Goldberg claimed that negative symptoms of schizophrenia do respond to neuroleptics. This apparent discovery is, in fact, a very common way of thinking for European schools of psychiatry, specially the French one guided by Delay and Deniker. Initially focused on reserpine and some alerting phenothiazines such as thioproperazine, this opinion has been extended to benzamides in the 1970s. The analysis of the publications devoted to this point indicates that several drugs are actually considered as potent disinhibitors (i.e. active on negative symptoms of schizophrenia): Phenothiazines: As shown in the controlled studies by Itil (1971), Poirier-Littré (1988), fluphenazine and pipotiazine improve the BPRS anergia factor and the SANS score. Butyrophenones: The first description of the "imipramine like" effect of trifluperidol by Janssen (1959) initiated the studies by Gallant (1960), Fox (1963). They compared trifluperidol at low doses versus haloperidol and chlorpromazine at medium and high doses, BPRS anergia factor improved only at low doses. Diphenylbutylpiperidines (DPBP): Meltzer's review (1986) concluded to the efficacy of such drugs on negative symptoms appearing as a specific biochemical relationship effect. A definite analysis about doses leads to a very different interpretation: DPBP low doses and only low doses improved negative symptoms as much as some low doses of phenothiazines. On the opposite, DPBP, phenothiazines and butyrophenones high doses are inefficient.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1683624

  12. Forward Modeling of a Coronal Cavity

    NASA Technical Reports Server (NTRS)

    Kucera, T. A.; Gibson, S. E.; Schmit, D. J.

    2011-01-01

    We apply a forward model of emission from a coronal cavity in an effort to determine the temperature and density distribution in the cavity. Coronal cavities are long, low-density structures located over filament neutral lines and are often seen as dark elliptical features at the solar limb in white light, EUV and X-rays. When these structures erupt they form the cavity portions of CMEs The model consists of a coronal streamer model with a tunnel-like cavity with elliptical cross-section and a Gaussian variation of height along the tunnel length. Temperature and density can be varied as a function of altitude both in the cavity and streamer. We apply this model to a cavity observed in Aug. 2007 by a wide array of instruments including Hinode/EIS, STEREO/EUVI and SOHO/EIT. Studies such as these will ultimately help us understand the the original structures which erupt to become CMEs and ICMES, one of the prime Solar Orbiter objectives.

  13. A selection of high gradient cavity experiments

    SciTech Connect

    Peter Kneisel

    1998-01-01

    In the two years since the 7th SRF workshop, a variety of cavity tests have been carried out with the objective to reproducibly achieve surface electric rf fields above 40 MV/m with no or only very little electron loading. This paper reports about a collection of tests on single cell and multi-cell cavities, which received standard surface treatments such as buffered chemical polishing and high pressure ultrapure water rinsing, but no heat treatments. Often the cavities were limited by quenches, posting a limit of 700 to 1,000 Oersted on achievable peak magnetic fields of high purity niobium RRR values between 200 and 250. In a seamless single cell cavity fabricated by V. Palmieri of INFN Legnaro by spinning, a very promising gradient of E{sub acc}=25 MV/m was measured. In collaboration with CERN, several tests on sputtering niobium prepared at CERN were also carried out, and accelerating gradients up to 25 MV/m were achieved. A single cell cavity, electron beam welded after electrochemical buffing, showed only good performance--E{sub p} > 50 MV/m--after the removal of more than 100 {micro}m of material. However, this cavity showed rather heavy Q disease even when cooled down rapidly; the Q degradation could be partially reversed by diffusing the oxygen from an anodized Nb{sub 2}O{sub 5} layer into the niobium by heating the cavity in-situ at T=250 C.

  14. Hydroforming of Tesla Cavities at Desy

    SciTech Connect

    W. Singer; H. Kaiser; X. Singer; I. Gonin; I. Zhelezov; T. Khabibullin; P. Kneisel; K. Saito

    2000-07-01

    Since several years the development of seamless niobium cavity fabrication by hydro forming is being pursued at DESY. This technique offers the possibility of lower cost of fabrication and perhaps better rf performance of the cavities because of the elimination of electron-beam welds, which in the standard fabrication technique have sometimes lead to inferior cavity performance due to defects. Several single cell 1300 MHz cavities have been formed from high purity seamless niobium tubes, which are under computer control expanded with internal pressure while simultaneously being swaged axially. The seamless tubes have been made by either back extrusion and flow forming or by spinning or deep drawing. Standard surface treatment techniques such as high temperature post purification, buffered chemical polishing (BCP), electropolishing (EP) and high pressure ultra pure water rinsing (HPR) have been applied to these cavities. The cavities exhibited high Q - values of 2 x 10{sup 10} at 2K and residual resistances as low as 3 n{Omega} after the removal of a surface layer of app. 100 {micro}m by BCP. Surprisingly, even at high gradients up to the maximum measured values of E{sub acc} {approx} 33 MV/m the Q-value did not decrease in the absence of field emission as often observed. After electropolishing of additional 100 {micro}m one of the cavities reached an accelerating gradient of E{sub acc} {ge} 42 MV/m.

  15. Optimized Multi-Ion Cavity Coupling

    NASA Astrophysics Data System (ADS)

    Begley, Stephen; Vogt, Markus; Gulati, Gurpreet Kaur; Takahashi, Hiroki; Keller, Matthias

    2016-06-01

    Recent technological advances in cavity quantum electrodynamics (CQED) are paving the way to utilize multiple quantum emitters confined in a single optical cavity. In such systems, it is crucially important to control the quantum mechanical coupling of individual emitters to the cavity mode. In this regard, combining ion trap technologies with CQED provides a particularly promising approach due to the well-established motional control over trapped ions. Here, we experimentally demonstrate coupling of up to five trapped ions in a string to a high-finesse optical cavity. By changing the axial position and spacing of the ions in a fully deterministic manner, we systematically characterize their coupling to the cavity mode through visibility measurements of the cavity emission. In good agreement with the theoretical model, the results demonstrate that the geometrical configuration of multiple trapped ions can be manipulated to obtain optimal cavity coupling. Our system presents a new ground for exploring CQED with multiple quantum emitters, enabled by the highly controllable collective light-matter interaction.

  16. Optimized Multi-Ion Cavity Coupling.

    PubMed

    Begley, Stephen; Vogt, Markus; Gulati, Gurpreet Kaur; Takahashi, Hiroki; Keller, Matthias

    2016-06-01

    Recent technological advances in cavity quantum electrodynamics (CQED) are paving the way to utilize multiple quantum emitters confined in a single optical cavity. In such systems, it is crucially important to control the quantum mechanical coupling of individual emitters to the cavity mode. In this regard, combining ion trap technologies with CQED provides a particularly promising approach due to the well-established motional control over trapped ions. Here, we experimentally demonstrate coupling of up to five trapped ions in a string to a high-finesse optical cavity. By changing the axial position and spacing of the ions in a fully deterministic manner, we systematically characterize their coupling to the cavity mode through visibility measurements of the cavity emission. In good agreement with the theoretical model, the results demonstrate that the geometrical configuration of multiple trapped ions can be manipulated to obtain optimal cavity coupling. Our system presents a new ground for exploring CQED with multiple quantum emitters, enabled by the highly controllable collective light-matter interaction. PMID:27314716

  17. Sustainability index for Taipei

    SciTech Connect

    Lee, Y.-J. . E-mail: yungjaanlee@pchome.com.tw; Huang Chingming . E-mail: michael@everwin.com.tw

    2007-08-15

    Sustainability indicators are an effective means of determining whether a city is moving towards sustainable development (SD). After considering the characteristics of Taipei, Taiwan, discussions with experts, scholars and government departments and an exhaustive literature review, this study selected 51 sustainability indicators corresponding to the socio-economic characteristic of Taipei City. Such indicators should be regarded as a basis for assessing SD in Taipei City. The 51 indicators are classified into economic, social, environmental and institutional dimensions. Furthermore, statistical data is adopted to identify the trend of SD from 1994 to 2004. Moreover, the sustainability index is calculated for the four dimensions and for Taipei as a whole. Analysis results demonstrate that social and environmental indicators are moving towards SD, while economic and institutional dimensions are performing relatively poorly. However, since 2002, the economic sustainability index has gradually moved towards SD. Overall, the Taipei sustainability index indicates a gradual trend towards sustainable development during the past 11 years.

  18. Beyond the Kubler index

    USGS Publications Warehouse

    Eberl, D.D.; Velde, B.

    1989-01-01

    The value of peak width at half-height for the illite 001 XRD reflection is known as the Kubler index or the illite "crystallinity' index. This measurement, which has been related to the degree of metamorphism of very low-grade, pelitic rocks, is a function of at least two crystal-chemical factors: 1) illite X-ray scattering domain size; and 2) illite structural distortions (especially swelling). Reynolds' NEWMOD computer program is used to construct a grid with which these two contributions to illite peak width can be determined independently from measurements of the 001 peak width at half-height and the Srodon intensity ratio. This method yields more information about changes undergone by illite during metamorphism than application of the Kubler index method alone. -Authors

  19. Upgraded cavities for the positron accumulator ring of the APS

    SciTech Connect

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

    1997-08-01

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

  20. Demonstration of superconducting micromachined cavities

    SciTech Connect

    Brecht, T. Reagor, M.; Chu, Y.; Pfaff, W.; Wang, C.; Frunzio, L.; Devoret, M. H.; Schoelkopf, R. J.

    2015-11-09

    Superconducting enclosures will be key components of scalable quantum computing devices based on circuit quantum electrodynamics. Within a densely integrated device, they can protect qubits from noise and serve as quantum memory units. Whether constructed by machining bulk pieces of metal or microfabricating wafers, 3D enclosures are typically assembled from two or more parts. The resulting seams potentially dissipate crossing currents and limit performance. In this letter, we present measured quality factors of superconducting cavity resonators of several materials, dimensions, and seam locations. We observe that superconducting indium can be a low-loss RF conductor and form low-loss seams. Leveraging this, we create a superconducting micromachined resonator with indium that has a quality factor of two million, despite a greatly reduced mode volume. Inter-layer coupling to this type of resonator is achieved by an aperture located under a planar transmission line. The described techniques demonstrate a proof-of-principle for multilayer microwave integrated quantum circuits for scalable quantum computing.