Inpainting using airy diffusion
NASA Astrophysics Data System (ADS)
Lorduy Hernandez, Sara
2015-09-01
One inpainting procedure based on Airy diffusion is proposed, implemented via Maple and applied to some digital images. Airy diffusion is a partial differential equation with spatial derivatives of third order in contrast with the usual diffusion with spatial derivatives of second order. Airy diffusion generates the Airy semigroup in terms of the Airy functions which can be rewritten in terms of Bessel functions. The Airy diffusion can be used to smooth an image with the corresponding noise elimination via convolution. Also the Airy diffusion can be used to erase objects from an image. We build an algorithm using the Maple package ImageTools and such algorithm is tested using some images. Our results using Airy diffusion are compared with the similar results using standard diffusion. We observe that Airy diffusion generates powerful filters for image processing which could be incorporated in the usual packages for image processing such as ImageJ and Photoshop. Also is interesting to consider the possibility to incorporate the Airy filters as applications for smartphones and smart-glasses.
Bohmian trajectories of Airy packets
Nassar, Antonio B.; Miret-Artés, Salvador
2014-09-15
The discovery of Berry and Balazs in 1979 that the free-particle Schrödinger equation allows a non-dispersive and accelerating Airy-packet solution has taken the folklore of quantum mechanics by surprise. Over the years, this intriguing class of wave packets has sparked enormous theoretical and experimental activities in related areas of optics and atom physics. Within the Bohmian mechanics framework, we present new features of Airy wave packet solutions to Schrödinger equation with time-dependent quadratic potentials. In particular, we provide some insights to the problem by calculating the corresponding Bohmian trajectories. It is shown that by using general space–time transformations, these trajectories can display a unique variety of cases depending upon the initial position of the individual particle in the Airy wave packet. Further, we report here a myriad of nontrivial Bohmian trajectories associated to the Airy wave packet. These new features are worth introducing to the subject’s theoretical folklore in light of the fact that the evolution of a quantum mechanical Airy wave packet governed by the Schrödinger equation is analogous to the propagation of a finite energy Airy beam satisfying the paraxial equation. Numerous experimental configurations of optics and atom physics have shown that the dynamics of Airy beams depends significantly on initial parameters and configurations of the experimental set-up.
Airy beam optical parametric oscillator
NASA Astrophysics Data System (ADS)
Aadhi, A.; Chaitanya, N. Apurv; Jabir, M. V.; Vaity, Pravin; Singh, R. P.; Samanta, G. K.
2016-05-01
Airy beam, a non-diffracting waveform, has peculiar properties of self-healing and self-acceleration. Due to such unique properties, the Airy beam finds many applications including curved plasma wave-guiding, micro-particle manipulation, optically mediated particle clearing, long distance communication, and nonlinear frequency conversion. However, many of these applications including laser machining of curved structures, generation of curved plasma channels, guiding of electric discharges in a curved path, study of nonlinear propagation dynamics, and nonlinear interaction demand Airy beam with high power, energy, and wavelength tunability. Till date, none of the Airy beam sources have all these features in a single device. Here, we report a new class of coherent sources based on cubic phase modulation of a singly-resonant optical parametric oscillator (OPO), producing high-power, continuous-wave (cw), tunable radiation in 2-D Airy intensity profile existing over a length >2 m. Based on a MgO-doped periodically poled LiNbO3 crystal pumped at 1064 nm, the Airy beam OPO produces output power more than 8 W, and wavelength tunability across 1.51–1.97 μm. This demonstration gives new direction for the development of sources of arbitrary structured beams at any wavelength, power, and energy in all time scales (cw to femtosecond).
Airy beam optical parametric oscillator.
Aadhi, A; Chaitanya, N Apurv; Jabir, M V; Vaity, Pravin; Singh, R P; Samanta, G K
2016-05-04
Airy beam, a non-diffracting waveform, has peculiar properties of self-healing and self-acceleration. Due to such unique properties, the Airy beam finds many applications including curved plasma wave-guiding, micro-particle manipulation, optically mediated particle clearing, long distance communication, and nonlinear frequency conversion. However, many of these applications including laser machining of curved structures, generation of curved plasma channels, guiding of electric discharges in a curved path, study of nonlinear propagation dynamics, and nonlinear interaction demand Airy beam with high power, energy, and wavelength tunability. Till date, none of the Airy beam sources have all these features in a single device. Here, we report a new class of coherent sources based on cubic phase modulation of a singly-resonant optical parametric oscillator (OPO), producing high-power, continuous-wave (cw), tunable radiation in 2-D Airy intensity profile existing over a length >2 m. Based on a MgO-doped periodically poled LiNbO3 crystal pumped at 1064 nm, the Airy beam OPO produces output power more than 8 W, and wavelength tunability across 1.51-1.97 μm. This demonstration gives new direction for the development of sources of arbitrary structured beams at any wavelength, power, and energy in all time scales (cw to femtosecond).
Airy beam optical parametric oscillator
Aadhi, A.; Chaitanya, N. Apurv; Jabir, M. V.; Vaity, Pravin; Singh, R. P.; Samanta, G. K.
2016-01-01
Airy beam, a non-diffracting waveform, has peculiar properties of self-healing and self-acceleration. Due to such unique properties, the Airy beam finds many applications including curved plasma wave-guiding, micro-particle manipulation, optically mediated particle clearing, long distance communication, and nonlinear frequency conversion. However, many of these applications including laser machining of curved structures, generation of curved plasma channels, guiding of electric discharges in a curved path, study of nonlinear propagation dynamics, and nonlinear interaction demand Airy beam with high power, energy, and wavelength tunability. Till date, none of the Airy beam sources have all these features in a single device. Here, we report a new class of coherent sources based on cubic phase modulation of a singly-resonant optical parametric oscillator (OPO), producing high-power, continuous-wave (cw), tunable radiation in 2-D Airy intensity profile existing over a length >2 m. Based on a MgO-doped periodically poled LiNbO3 crystal pumped at 1064 nm, the Airy beam OPO produces output power more than 8 W, and wavelength tunability across 1.51–1.97 μm. This demonstration gives new direction for the development of sources of arbitrary structured beams at any wavelength, power, and energy in all time scales (cw to femtosecond). PMID:27143582
Generation of electron Airy beams.
Voloch-Bloch, Noa; Lereah, Yossi; Lilach, Yigal; Gover, Avraham; Arie, Ady
2013-02-21
Within the framework of quantum mechanics, a unique particle wave packet exists in the form of the Airy function. Its counterintuitive properties are revealed as it propagates in time or space: the quantum probability wave packet preserves its shape despite dispersion or diffraction and propagates along a parabolic caustic trajectory, even though no force is applied. This does not contradict Newton's laws of motion, because the wave packet centroid propagates along a straight line. Nearly 30 years later, this wave packet, known as an accelerating Airy beam, was realized in the optical domain; later it was generalized to an orthogonal and complete family of beams that propagate along parabolic trajectories, as well as to beams that propagate along arbitrary convex trajectories. Here we report the experimental generation and observation of the Airy beams of free electrons. These electron Airy beams were generated by diffraction of electrons through a nanoscale hologram, which imprinted on the electrons' wavefunction a cubic phase modulation in the transverse plane. The highest-intensity lobes of the generated beams indeed followed parabolic trajectories. We directly observed a non-spreading electron wavefunction that self-heals, restoring its original shape after passing an obstacle. This holographic generation of electron Airy beams opens up new avenues for steering electronic wave packets like their photonic counterparts, because the wave packets can be imprinted with arbitrary shapes or trajectories.
Hybrid Airy plasmons with dynamically steerable trajectories.
Li, Rujiang; Imran, Muhammad; Lin, Xiao; Wang, Huaping; Xu, Zhiwei; Chen, Hongsheng
2017-01-26
With their intriguing diffraction-free, self-accelerating, and self-healing properties, Airy plasmons show promise for use in the trapping, transporting, and sorting of micro-objects, imaging, and chip scale signal processing. However, high dissipative loss and lack of dynamical steerability restrict the implementation of Airy plasmons in these applications. Here we reveal hybrid Airy plasmons for the first time by taking a hybrid graphene-based plasmonic waveguide in the terahertz (THz) domain as an example. Due to coupling between optical modes and plasmonic modes, the hybrid Airy plasmons can have large propagation lengths and effective transverse deflections, where the transverse waveguide confinements are governed by the hybrid modes with moderate quality factors. Meanwhile, the propagation trajectories of the hybrid Airy plasmons are dynamically steerable by changing the chemical potential of graphene. These hybrid Airy plasmons may promote the further discovery of non-diffracting beams along with the emerging developments of optical tweezers and tractor beams.
Acoustic non-diffracting Airy beam
Lin, Zhou; Guo, Xiasheng Tu, Juan; Ma, Qingyu; Wu, Junru; Zhang, Dong
2015-03-14
The acoustic non-diffracting Airy beam as its optical counterpart has unique features of self-bending and self-healing. The complexity of most current designs handicaps its applications. A simple design of an acoustic source capable of generating multi-frequency and broad-band acoustic Airy beam has been theoretically demonstrated by numerical simulations. In the design, a piston transducer is corrugated to induce spatial phase variation for transducing the Airy function. The piston's surface is grooved in a pattern that the width of each groove corresponds to the half wavelength of Airy function. The resulted frequency characteristics and its dependence on the size of the piston source are also discussed. This simple design may promote the wide applications of acoustic Airy beam particularly in the field of medical ultrasound.
Spatiotemporal dynamics of counterpropagating Airy beams
Wiersma, Noémi; Marsal, Nicolas; Sciamanna, Marc; Wolfersberger, Delphine
2015-01-01
We analyse theoretically the spatiotemporal dynamics of two incoherent counterpropagating Airy beams interacting in a photorefractive crystal under focusing conditions. For a large enough nonlinearity strength the interaction between the two Airy beams leads to light-induced waveguiding. The stability of the waveguide is determined by the crystal length, the nonlinearity strength and the beam’s intensities and is improved when comparing to the situation using Gaussian beams. We further identify the threshold above which the waveguide is no longer static but evolves dynamically either time-periodically or even chaotically. Above the stability threshold, each Airy-soliton moves erratically between privileged output positions that correspond to the spatial positions of the lobes of the counterpropagating Airy beam. These results suggest new ways of creating dynamically varying waveguides, optical logic gates and chaos-based computing. PMID:26315530
Ultrafast Airy beam optical parametric oscillator.
Apurv Chaitanya, N; Kumar, S Chaitanya; Aadhi, A; Samanta, G K; Ebrahim-Zadeh, M
2016-08-01
We report on the first realization of an ultrafast Airy beam optical parametric oscillator (OPO). By introducing intracavity cubic phase modulation to the resonant Gaussian signal in a synchronously-pumped singly-resonant OPO cavity and its subsequent Fourier transformation, we have generated 2-dimensional Airy beam in the output signal across a 250 nm tuning range in the near-infrared. The generated Airy beam can be tuned continuously from 1477 to 1727 nm, providing an average power of as much as 306 mW at 1632 nm in pulses of ~23 ps duration with a spectral bandwidth of 1.7 nm.
Ultrafast Airy beam optical parametric oscillator
Apurv Chaitanya, N.; Kumar, S. Chaitanya; Aadhi, A.; Samanta, G. K.; Ebrahim-Zadeh, M.
2016-01-01
We report on the first realization of an ultrafast Airy beam optical parametric oscillator (OPO). By introducing intracavity cubic phase modulation to the resonant Gaussian signal in a synchronously-pumped singly-resonant OPO cavity and its subsequent Fourier transformation, we have generated 2-dimensional Airy beam in the output signal across a 250 nm tuning range in the near-infrared. The generated Airy beam can be tuned continuously from 1477 to 1727 nm, providing an average power of as much as 306 mW at 1632 nm in pulses of ~23 ps duration with a spectral bandwidth of 1.7 nm. PMID:27476910
Ultrafast Airy beam optical parametric oscillator
NASA Astrophysics Data System (ADS)
Apurv Chaitanya, N.; Kumar, S. Chaitanya; Aadhi, A.; Samanta, G. K.; Ebrahim-Zadeh, M.
2016-08-01
We report on the first realization of an ultrafast Airy beam optical parametric oscillator (OPO). By introducing intracavity cubic phase modulation to the resonant Gaussian signal in a synchronously-pumped singly-resonant OPO cavity and its subsequent Fourier transformation, we have generated 2-dimensional Airy beam in the output signal across a 250 nm tuning range in the near-infrared. The generated Airy beam can be tuned continuously from 1477 to 1727 nm, providing an average power of as much as 306 mW at 1632 nm in pulses of ~23 ps duration with a spectral bandwidth of 1.7 nm.
Airy, Sir George Biddell (1801-92)
NASA Astrophysics Data System (ADS)
Murdin, P.
2000-11-01
A brilliant Cambridge mathematician (Senior Wrangler 1823, i.e. leader of the graduating mathematics class), Airy became the seventh Astronomer Royal in 1835 after a brief period as Lucasian Professor at Cambridge. His output was prodigious, and he published nearly 400 scientific papers and 150 reports on various scientific issues, such as the gauge of railways, spectacles to correct astigmatism,...
Generation of attenuation-compensating Airy beams.
Preciado, Miguel A; Dholakia, Kishan; Mazilu, Michael
2014-08-15
We present an attenuation-corrected "nondiffracting" Airy beam. The correction factor can be adjusted to deliver a beam that exhibits an adjustable exponential intensity increase or decrease over a finite distance. A digital micromirror device that shapes both amplitude and phase is used to experimentally verify the propagation of these beams through air and partially absorbing media.
Airy acoustical-sheet spinner tweezers
NASA Astrophysics Data System (ADS)
Mitri, F. G.
2016-09-01
The Airy acoustical beam exhibits parabolic propagation and spatial acceleration, meaning that the propagation bending angle continuously increases before the beam trajectory reaches a critical angle where it decays after a propagation distance, without applying any external bending force. As such, it is of particular importance to investigate its properties from the standpoint of acoustical radiation force, spin torque, and particle dynamics theories, in the development of novel particle sorting techniques and acoustically mediated clearing systems. This work investigates these effects on a two-dimensional (2D) circular absorptive structure placed in the field of a nonparaxial Airy "acoustical-sheet" (i.e., finite beam in 2D), for potential applications in surface acoustic waves and acousto-fluidics. Based on the characteristics of the acoustic field, the beam is capable of manipulating the circular cylindrical fluid cross-section and guides it along a transverse or parabolic trajectory. This feature of Airy acoustical beams could lead to a unique characteristic in single-beam acoustical tweezers related to acoustical sieving, filtering, and removal of particles and cells from a section of a small channel. The analysis developed here is based on the description of the nonparaxial Airy beam using the angular spectrum decomposition of plane waves in close association with the partial-wave series expansion method in cylindrical coordinates. The numerical results demonstrate the ability of the nonparaxial Airy acoustical-sheet beam to pull, propel, or accelerate a particle along a parabolic trajectory, in addition to particle confinement in the transverse direction of wave propagation. Negative or positive radiation force and spin torque causing rotation in the clockwise or the anticlockwise direction can occur depending on the nondimensional parameter ka (where k is the wavenumber and a is the radius) and the location of the cylinder in the beam. Applications in
Airy beam self-focusing in a photorefractive medium
Wiersma, Noémi; Marsal, Nicolas; Sciamanna, Marc; Wolfersberger, Delphine
2016-01-01
The unique bending and shape-preserving properties of optical Airy beams offer a large range of applications in for example beam routing, optical waveguiding, particle manipulation and plasmonics. In these applications and others, the Airy beam may experience nonlinear light-matter interactions which in turn modify the Airy beam properties and propagation. A well-known example is light self-focusing that leads to the formation of spatial soliton. Here, we unveil experimentally the self-focusing properties of a 1D-Airy beam in a photorefractive crystal under focusing conditions. The transient evolution involves both self-bending and acceleration of the initially launched Airy beam due to the onset of an off-shooting soliton and the resulting nonlocal refractive index perturbation. Both the transient and stationary self-focusing properties can be tuned by varying the bias electric field, the injected Airy beam power and the background illumination. PMID:27731356
Airy beam self-focusing in a photorefractive medium
NASA Astrophysics Data System (ADS)
Wiersma, Noémi; Marsal, Nicolas; Sciamanna, Marc; Wolfersberger, Delphine
2016-10-01
The unique bending and shape-preserving properties of optical Airy beams offer a large range of applications in for example beam routing, optical waveguiding, particle manipulation and plasmonics. In these applications and others, the Airy beam may experience nonlinear light-matter interactions which in turn modify the Airy beam properties and propagation. A well-known example is light self-focusing that leads to the formation of spatial soliton. Here, we unveil experimentally the self-focusing properties of a 1D-Airy beam in a photorefractive crystal under focusing conditions. The transient evolution involves both self-bending and acceleration of the initially launched Airy beam due to the onset of an off-shooting soliton and the resulting nonlocal refractive index perturbation. Both the transient and stationary self-focusing properties can be tuned by varying the bias electric field, the injected Airy beam power and the background illumination.
Creating Airy beams employing a transmissive spatial light modulator.
Latychevskaia, Tatiana; Schachtler, Daniel; Fink, Hans-Werner
2016-08-01
We present a detailed study of two novel methods for shaping the light optical wavefront by employing a transmissive spatial light modulator (SLM). Conventionally, optical Airy beams are created by employing SLMs in the so-called all-phase mode. In the first method, a numerically simulated lens phase distribution is loaded directly onto the SLM, together with the cubic phase distribution. An Airy beam is generated at the focal plane of the numerical lens. We provide for the first time, to the best of our knowledge, quantitative properties of the formed Airy beam. We derive the formula for deflection of the intensity maximum of the so-formed Airy beam, which is different from the quadratic deflection typical of Airy beams. We cross-validate the derived formula by both simulations and experiment. The second method is based on the fact that a system consisting of a transmissive SLM sandwiched between two polarizers can create a transmission function with negative values. This observation alone has the potential for various other wavefront modulations where the transmission function requires negative values. As an example for this method, we demonstrate that a wavefront can be modulated by passing the SLM system with transmission function with negative values by loading an Airy function distribution directly onto the SLM. Since the Airy function is a real-valued function but also with negative values, an Airy beam can be generated by direct transfer of the Airy function distribution onto such an SLM system. In this way, an Airy beam is generated immediately behind the SLM. As both new methods do not employ a physical lens, the two setups are more compact than conventional setups for creating Airy beams. We compare the performance of the two novel methods and the properties of the created Airy beams.
Autobiography of Sir George Biddell Airy
NASA Astrophysics Data System (ADS)
Airy, George Biddell; Airy, Wilfred
2010-06-01
Preface; 1. Personal sketch of George Biddell Airy; 2. From his birth to his taking his B.A. degree; 3. At Trinity College, Cambridge; 4. At Cambridge Observatory; 5. At Greenwich Observatory, 1836-1846; 6. At Greenwich Observatory, 1846-1856; 7. At Greenwich Observatory, 1856-1866; 8. At Greenwich Observatory, 1866-1876; 9. At Greenwich Observatory to his resignation in 1881; 10. At the White House, Greewich, to his death; Appendix: List of printed papers; Index.
The structure of Airy's stress function in multiply connected regions
NASA Technical Reports Server (NTRS)
Grioli, Giusippe
1951-01-01
In solving two-dimensional problems using Airy's stress function for multiply connected regions, the form of the function depends on the dislocations and boundary forces present. The structure of Airy's function is shown to consist of a part expressible in terms of boundary forces and a part expressible in the manner of Poincare. Meanings of the constants occurring in Poincare's expression are discussed.
Evaluation of the AIRIS Standoff Hyperspectral Imaging System
2011-01-01
6,600 3. DESCRIPTION OF THE AIRIS SENSOR The AIRIS-WAD technical concept is based on the insertion of a tunable Fabry - Perot interferometer (etalon...CLASSIFICATION OF: a. REPORT U b. ABSTRACT U c. THIS PAGE U 17. LIMITATION OF ABSTRACT UL 18. NUMBER OF PAGES 2 A 19a. NAME OF RESPONSIBLE PERSON
Airy structure in 16O+14C nuclear rainbow scattering
NASA Astrophysics Data System (ADS)
Ohkubo, S.; Hirabayashi, Y.
2015-08-01
The Airy structure in 16 O +14 C rainbow scattering is studied with an extended double-folding (EDF) model that describes all the diagonal and off-diagonal coupling potentials derived from the microscopic realistic wave functions for 16 O by using a density-dependent nucleon-nucleon force. The experimental angular distributions at EL=132 , 281, and 382.2 MeV are well reproduced by the calculations. By studying the energy evolution of the Airy structure, the Airy minimum around θ =76∘ in the angular distribution at EL=132 MeV is assigned as the second-order Airy minimum A 2 in contrast to the recent literature which assigns it as the third order A 3 . The Airy minima in the 90∘ excitation function is investigated in comparison with well-known 16 O +16 O and 12 C +12 C systems. Evolution of the Airy structure into the molecular resonances with the 16 O +14 C cluster structure in the low-energy region around Ec .m .=30 MeV is discussed. It is predicted theoretically for the first time for a non-4 N 16O +14 C system that Airy elephants in the 90∘ excitation function are present.
Plasmonic Airy beam generated by in-plane diffraction.
Li, L; Li, T; Wang, S M; Zhang, C; Zhu, S N
2011-09-16
We report an experimental realization of a plasmonic Airy beam, which is generated thoroughly on a silver surface. With a carefully designed nanoarray structure, such Airy beams come into being from an in-plane propagating surface plasmon polariton wave, exhibiting nonspreading, self-bending, and self-healing properties. Besides, a new phase-tuning method based on nonperfectly matched diffraction processes is proposed to generate and modulate the beam almost at will. This unique plasmonic Airy beam as well as the generation method would significantly promote the evolutions in in-plane surface plasmon polariton manipulations and indicate potential applications in lab-on-chip photonic integrations.
Accelerating Airy beams in the presence of inhomogeneities
NASA Astrophysics Data System (ADS)
Besieris, Ioannis M.; Shaarawi, Amr M.; Zamboni-Rached, Michel
2016-06-01
Studies have already been made of accelerating Airy beams in the presence of deterministic inhomogeneities, illustrating, in particular, that the inherent self-healing properties of such beams are preserved. The cases of a range-dependent linear transverse potential and a converging GRIN structure (harmonic oscillator) have been examined thoroughly. Examples will be given in this article of novel accelerating Airy beams in the presence of five other types of potential functions. Three of the resulting exact analytical solutions have a common salient characteristic property: they are constructed using the free-space accelerating Airy beam solution as a seed.
Controllable Airy-like beams induced by tunable phase patterns
NASA Astrophysics Data System (ADS)
Li, D.; Qian, Y.
2016-01-01
We propose and experimentally observe a novel family of Airy-like beams. First, we theoretically investigate the physical generation of our proposed controllable Airy-like beams by introducing a rotation angle factor into the phase function, which can regulate and flexibly control the beam wavefront. Meanwhile we can also readily control the main lobes of these beams to follow appointed parabolic trajectories using the rotation angle factor. We also demonstrate that the controllable Airy-like beams lack the properties of being diffraction-free and self-healing. The experiments are performed and the results are in accord with the theoretical simulations. We believe that the intriguing characteristics of our proposed Airy-like beams could provide more degrees of freedom, and are likely to give rise to new applications and lend versatility to the emerging field.
Efficient and accurate computation of the incomplete Airy functions
NASA Technical Reports Server (NTRS)
Constantinides, E. D.; Marhefka, R. J.
1993-01-01
The incomplete Airy integrals serve as canonical functions for the uniform ray optical solutions to several high-frequency scattering and diffraction problems that involve a class of integrals characterized by two stationary points that are arbitrarily close to one another or to an integration endpoint. Integrals with such analytical properties describe transition region phenomena associated with composite shadow boundaries. An efficient and accurate method for computing the incomplete Airy functions would make the solutions to such problems useful for engineering purposes. In this paper a convergent series solution for the incomplete Airy functions is derived. Asymptotic expansions involving several terms are also developed and serve as large argument approximations. The combination of the series solution with the asymptotic formulae provides for an efficient and accurate computation of the incomplete Airy functions. Validation of accuracy is accomplished using direct numerical integration data.
Continuum Statistics of the Airy2 Process
NASA Astrophysics Data System (ADS)
Corwin, Ivan; Quastel, Jeremy; Remenik, Daniel
2013-01-01
We develop an exact determinantal formula for the probability that the Airy_2 process is bounded by a function g on a finite interval. As an application, we provide a direct proof that {sup({A}2(x)-x^2)} is distributed as a GOE random variable. Both the continuum formula and the GOE result have applications in the study of the end point of an unconstrained directed polymer in a disordered environment. We explain Johansson's (Commun. Math. Phys. 242(1-2):277-329, 2003) observation that the GOE result follows from this polymer interpretation and exact results within that field. In a companion paper (Moreno Flores et al. in Commun. Math. Phys. 2012) these continuum statistics are used to compute the distribution of the endpoint of directed polymers.
NASA Astrophysics Data System (ADS)
Chapman, A.
2012-01-01
One major research development in the history of astronomy, pioneered in particular by the SHA, is a shift from the concern with what the ÔgiantsÕ, such as Galileo or Newton, achieved to an examination of the wider spectrum of astronomical personnel. And one rich field of inquiry here is that body of men, and later of women, who earned their livings as assistant astronomers. It is, in fact, an abundantly documented area, including figures employed in Grand Amateur, university, and civic observatories, though without doubt the richest and longest-running body of data pertaining to what might be called the ÔAstronomersÕ GentlemenÕ comes from the archives of the Royal Observatory, Greenwich, especially for the years 1835 to 1881, when Sir George Biddell Airy was Astronomer Royal.
Vessel extraction using the Buckmaster-Airy filter
NASA Astrophysics Data System (ADS)
Sanchez, Valentina
2016-05-01
A new and powerful technique for vessel extraction from biomedical images using the so called Buckmaster- Airy Filter is designed, prototyped and tested. The design, the prototyping and the testing were performed using computer algebra software, specifically the Maple package ImageTools. Some preliminary experiments were performed ant the results were excellent. Our new technique is based on partial differential equations.. Specifically two dimensional Airy diffusion equation and the two dimensional Buckmaster equation were used for designing the new Buckmaster-Airy Filter. Such new filter is able to enhance the quality of an image, producing simultaneously noise elimination, but without altering the edges of the image. The new Bukmaster-Airy filter is applied to the target image via discrete convolution. The results of some experiments of vessel extraction will be presented; and some lines for future research such as the possible implementation of the Buckmaster-Airy Filter as a new plugging for the program ImageJ, will be proposed.
Propagation of an Airy beam through the atmosphere.
Ji, Xiaoling; Eyyuboğlu, Halil T; Ji, Guangming; Jia, Xinhong
2013-01-28
In this paper, the effect of thermal blooming of an Airy beam propagating through the atmosphere is examined, and the effect of atmospheric turbulence is not considered. The changes of the intensity distribution, the centroid position and the mean-squared beam width of an Airy beam propagating through the atmosphere are studied by using the four-dimensional (4D) computer code of the time-dependent propagation of Airy beams through the atmosphere. It is shown that an Airy beam can't retain its shape and the structure when the Airy beam propagates through the atmosphere due to thermal blooming except for the short propagation distance, or the short time, or the low beam power. The thermal blooming results in a central dip of the center lobe, and causes the center lobe to spread and decrease. In contrast with the center lobe, the side lobes are less affected by thermal blooming, such that the intensity maximum of the side lobe may be larger than that of the center lobe. However, the cross wind can reduce the effect of thermal blooming. When there exists the cross wind velocity vx in x direction, the dependence of centroid position in x direction on vx is not monotonic, and there exists a minimum, but the centroid position in y direction is nearly independent of vx.
On the asymptotic evolution of finite energy Airy wave functions.
Chamorro-Posada, P; Sánchez-Curto, J; Aceves, A B; McDonald, G S
2015-06-15
In general, there is an inverse relation between the degree of localization of a wave function of a certain class and its transform representation dictated by the scaling property of the Fourier transform. We report that in the case of finite energy Airy wave packets a simultaneous increase in their localization in the direct and transform domains can be obtained as the apodization parameter is varied. One consequence of this is that the far-field diffraction rate of a finite energy Airy beam decreases as the beam localization at the launch plane increases. We analyze the asymptotic properties of finite energy Airy wave functions using the stationary phase method. We obtain one dominant contribution to the long-term evolution that admits a Gaussian-like approximation, which displays the expected reduction of its broadening rate as the input localization is increased.
Improved Intrapulse Raman Scattering Control via Asymmetric Airy Pulses
NASA Astrophysics Data System (ADS)
Hu, Yi; Tehranchi, Amirhossein; Wabnitz, Stefan; Kashyap, Raman; Chen, Zhigang; Morandotti, Roberto
2015-02-01
We experimentally demonstrate the possibility of tuning the frequency of a laser pulse via the use of an Airy pulse-seeded soliton self-frequency shift. The intrinsically asymmetric nature of Airy pulses, typically featured by either leading or trailing oscillatory tails (relatively to the main lobe), is revealed through the nonlinear generation of both a primary and a secondary Raman soliton self-frequency shift, a phenomenon which is driven by the soliton fission processes. The resulting frequency shift can be carefully controlled by using time-reversed Airy pulses or, alternatively, by applying an offset to the cubic phase modulation used to generate the pulses. When compared with the use of conventional chirped Gaussian pulses, our technique brings about unique advantages in terms of both efficient frequency tuning and feasibility, along with the generation and control of multicolor Raman solitons with enhanced tunability. Our theoretical analysis agrees well with our experimental observations.
Generation of fiber-based plasmonic Airy beam
NASA Astrophysics Data System (ADS)
Guan, Chunying; Ding, Ming; Shi, Jinhui; Wang, Pengfei; Hua, Ping; Brambilla, Gilberto; Yuan, Libo
2014-05-01
Compact all-fiber plasmonic Airy-like beam generator is demonstrated. A single slit and a 1D groove array were fabricated by focused ion beam (FIB) milling on the end facet of a single mode optical fiber. The single slit excites the surface plasmonic polaritons (SPPs), which are decoupled into free space by the groove array. The phase of decoupling SPPs is adjusted by the grooves position. Experimental generation of the single Airy-like beam has good consistency with theoretical predictions. The transverse acceleration and nondiffraction properties are observed. The presented plasmonic Airy-like beam generator is of importance to realize all-fiber optical trapping, beam shaping, and fiber integrated devices.
Nonparaxial diffraction analysis of Airy and SAiry beams.
Carretero, Luis; Acebal, Pablo; Blaya, Salvador; García, Celia; Fimia, Antonio; Madrigal, Roque; Murciano, Angel
2009-12-07
We theoretically analyze Airy beams by solving the exact vectorial Helmholtz equation using boundary conditions at a diffraction aperture. As result, the diffracted beams are obtained in the whole space; thus, we demonstrate that the parabolic trajectories are larger than those previously reported, showing that the Airy beams start to form before the Fourier plane. We also demonstrate the possibility of using a new type of Airy beams (SAiry beams) with finite energy that can be generated at the focal plane of the lens due to diffraction by a circular aperture of a spherical wave modified by a cubic phase. The finite energy ensured by the principle of conservation of energy of a diffracted beam.
Optimal control of the ballistic motion of Airy beams.
Hu, Yi; Zhang, Peng; Lou, Cibo; Huang, Simon; Xu, Jingjun; Chen, Zhigang
2010-07-01
We demonstrate the projectile motion of two-dimensional truncated Airy beams in a general ballistic trajectory with controllable range and height. We show that the peak beam intensity can be delivered to any desired location along the trajectory as well as repositioned to a given target after displacement due to propagation through disordered or turbulent media.
Quantitative study on propagation and healing of Airy beams under experimental conditions.
Zhuang, Fei; Zhu, Ziyi; Margiewicz, Jessica; Shi, Zhimin
2015-03-01
We investigate the propagation and healing of Airy beams in two dimensions that are obtainable under practical experimental conditions. We introduce an intensity similarity factor to quantitatively describe how an Airy beam retains its original shape. Based on such a figure of merit, we define a shape-retaining distance to quantify how far an Airy beam can keep the shape of its main lobe upon propagation and a healing distance to quantify how soon an initially partially blocked Airy beam can restore its main lobe profile. We perform an analysis on how these two distances scale with experimental parameters. We further use an interference picture to interpret the healing phenomenon of an Airy beam. Our work can serve as a guideline for quantitative performance analysis for applications of Airy beams and can be extended to other special beams in a straightforward fashion.
Multi-focus of modulated polarized Airy beam
NASA Astrophysics Data System (ADS)
Zhao, Hongyang; Lin, Jie; Tan, Jiubin; Jin, Peng
2016-07-01
The focusing performance of a modulated polarized Airy beam is explored by using the Richards and Wolf vectorial diffraction model in a high numerical aperture system. The multiple foca appeared on the focal plane or along the optical axis when a complex amplitude modulating function was introduced. Two focusing spots with long-focal-depth were additionally observed due to the Airy beam and complex amplitude modulation. The distance between the focuses were changed from 1.15λ to 3.56λ with FWHM of 0.9λ for one-dimensional linear polarized incident beam and from 1.15λ to 3.64λ for two-dimensional beam. The multiple focusing spots are expected to apply in the field of optical trapping and particle acceleration.
Propagation of Airy Gaussian vortex beams in uniaxial crystals
NASA Astrophysics Data System (ADS)
Weihao, Yu; Ruihuang, Zhao; Fu, Deng; Jiayao, Huang; Chidao, Chen; Xiangbo, Yang; Yanping, Zhao; Dongmei, Deng
2016-04-01
The propagation dynamics of the Airy Gaussian vortex beams in uniaxial crystals orthogonal to the optical axis has been investigated analytically and numerically. The propagation expression of the beams has been obtained. The propagation features of the Airy Gaussian vortex beams are shown with changes of the distribution factor and the ratio of the extraordinary refractive index to the ordinary refractive index. The correlations between the ratio and the maximum intensity value during the propagation, and its appearing distance have been investigated. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374108, 11374107, 10904041, and 11547212), the Foundation of Cultivating Outstanding Young Scholars of Guangdong Province, China, the CAS Key Laboratory of Geospace Environment, University of Science and Technology of China, the National Training Program of Innovation and Entrepreneurship for Undergraduates (Grant No. 2015093), and the Science and Technology Projects of Guangdong Province, China (Grant No. 2013B031800011).
Propagation of an Airy beam with a spiral phase.
Chu, Xiuxiang
2012-12-15
The propagation of an Airy beam with a spiral phase is studied. The centroid position and spread of the beam are investigated analytically for different topological charges. Study shows that the centroid position of the Airy beam with a spiral phase keeps moving during propagation. The motion with positive topological charge is in the direction opposite to that with negative topological charge. The speed of the motion of the centroid position is proportional to the topological charge and the normalized distance. From the variation of the second moment of the beam, we can also see that the beam spread is speeded up by the spiral phase during propagation. The speed of the beam spread is proportional to the square of the topological charge.
Production of accelerating quad Airy beams and their optical characteristics.
Ren, Zhijun; Wu, Qiong; Shi, Yile; Chen, Chen; Wu, Jiangmiao; Wang, Hui
2014-06-16
Based on a geometric caustic argument and diffraction catastrophe theory, we generate a novel form of accelerating beams using a symmetric 3/2 phase-only pattern. Such beams can be called accelerating quad Airy beams (AQABs) because they look very much like four face-to-face combined Airy beams. Optical characteristics of AQABs are subsequently investigated. The research results show that the beams have axial-symmetrical and centrosymmetrical transverse intensity patterns and quasi-diffraction-free propagation features for their four main lobes while undergoing transverse shift along parabolic trajectories. Moreover, we also demonstrate that AQABs possess self-construction ability when local areas are blocked. The unique optical properties of these beams will make them useful tools for future scientific applications.
Interaction of Airy-Gaussian beams in saturable media
NASA Astrophysics Data System (ADS)
Zhou, Meiling; Peng, Yulian; Chen, Chidao; Chen, Bo; Peng, Xi; Deng, Dongmei
2016-08-01
Based on the nonlinear Schrödinger equation, the interactions of the two Airy-Gaussian components in the incidence are analyzed in saturable media, under the circumstances of the same amplitude and different amplitudes, respectively. It is found that the interaction can be both attractive and repulsive depending on the relative phase. The smaller the interval between two Airy-Gaussian components in the incidence is, the stronger the intensity of the interaction. However, with the equal amplitude, the symmetry is shown and the change of quasi-breathers is opposite in the in-phase case and out-of-phase case. As the distribution factor is increased, the phenomena of the quasi-breather and the self-accelerating of the two Airy-Gaussian components are weakened. When the amplitude is not equal, the image does not have symmetry. The obvious phenomenon of the interaction always arises on the side of larger input power in the incidence. The maximum intensity image is also simulated. Many of the characteristics which are contained within other images can also be concluded in this figure. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374108 and 10904041), the Foundation for the Author of Guangdong Province Excellent Doctoral Dissertation (Grant No. SYBZZXM201227), and the Foundation of Cultivating Outstanding Young Scholars (“Thousand, Hundred, Ten” Program) of Guangdong Province, China. CAS Key Laboratory of Geospace Environment, University of Science and Technology of China.
Generation of vortex circular Airy beam through binary amplitude digital hologram
NASA Astrophysics Data System (ADS)
Fang, Zhao-Xiang; Ren, Yu-Xuan; Lu, Rong-De
2016-02-01
Airy beam is a kind of wavepacket existing in the form of photons, electrons, and plasmonics. Well known as diffraction-free beam, optical Airy beam tends to accelerate in transverse space with a parabolic trajectory, and exhibits self-healing property when partially blocked. Those properties have attracted a great deal of research interests and applications. Circular Airy beam, exhibiting cylindrically symmetric intensity pattern and abruptly autofocusing characteristics in the linear media, is a variant of Airy-like wave. Optical vortex, on the other hand, is a kind of phase singularity. We present to shape the autofocusing Airy beam with a vortex phase structure, which was realized through the binary amplitude modulation with a digital micromirror device (DMD). Each mirror on the DMD could be electronically addressed to situate at either of the two solid positional states corresponding to on and off. Shaping the light into a specific mode requires the calculation of the amplitude pattern for display on the DMD. By reshaping individual DMD pixels into giant pixels, the complex field of the vortex Airy beam could be encoded with a super-pixel method. The propagation property of the vortex Airy beam was investigated through numerical simulation for different topological charges. Furthermore, the propagation characteristics of this beam in free space were verified and discussed through the experiments. We anticipate that the proposed vortex Airy beam in particle trapping, biological field and optical communications. This method with DMD can also be used to generate other beams with different characteristics.
Impacts of cross-phase modulation on modulation instability of Airy pulses
NASA Astrophysics Data System (ADS)
Cheng, Yingkai; Fu, Xiquan; Bai, Yanfeng
2016-10-01
The modulation instability (MI) of Airy pulses with the influence of cross-phase modulation is studied based on the coupled nonlinear Schrödinger equations in nonlinear media. The main lobe of Airy pulses can be manifested as breakup of MI under interaction with higher power pumped solitons, although the power of Airy pulses is small. By comparing the main lobe's gain spectrum of MI, the gain spectrum has gradually improved with the increase of power of pumped solitons. The gain spectrum of MI of the main lobe is inversely proportional to the truncation coefficient, and then it gradually approaches to that of Gauss pulses with the truncation coefficient increasing to 1. For the side lobes of Airy pulses, there are similar MI but smaller gain spectrum than the main lobe when the pumped solitons is overlapping with corresponding ones of Airy pulses.
>From alexander of aphrodisias to young and airy
NASA Astrophysics Data System (ADS)
Jackson, J. D.
1999-10-01
A didactic discussion of the physics of rainbows is presented, with some emphasis on the history, especially the contributions of Thomas Young nearly 200 years ago. We begin with the simple geometrical optics of Descartes and Newton, including the reasons for Alexander's dark band between the main and secondary bows. We then show how dispersion produces the familiar colorful spectacle. Interference between waves emerging at the same angle, but traveling different optical paths within the water drops, accounts for the existence of distinct supernumerary rainbows under the right conditions (small drops, uniform in size). Young's and Airy's contributions are given their due.
Higher-Order Airy Scaling in Deformed Dyck Paths
NASA Astrophysics Data System (ADS)
Haug, Nils; Olde Daalhuis, Adri; Prellberg, Thomas
2017-03-01
We introduce a deformed version of Dyck paths (DDP), where additional to the steps allowed for Dyck paths, `jumps' orthogonal to the preferred direction of the path are permitted. We consider the generating function of DDP, weighted with respect to their half-length, area and number of jumps. This represents the first example of an exactly solvable two-dimensional lattice vesicle model showing a higher-order multicritical point. Applying the generalized method of steepest descents, we see that the associated two-variable scaling function is given by the logarithmic derivative of a generalized (higher-order) Airy integral.
Quantum polarization fluctuations of an Airy beam in turbulent atmosphere in a slant path.
Yin, Xia; Zhang, Licheng
2016-07-01
Polarization of light has many applications in quantum information processing, including quantum teleportation and dense coding. In this paper, we investigate the polarization fluctuations of Airy beams propagating in a slant turbulent channel under the "few-photon" limit. Using the quantum Stokes parameters and the quantum degree of polarization, we demonstrate that the degree of polarization of Airy beams increases significantly with the large number of the detection photons, and a higher photon-number level can retain the stability of polarization. Numerical simulations show that the longer propagation distance and the stronger turbulence will lead to less oscillatory behaviors and a decrease in the polarization degree of Airy beams, but a bigger exponential truncation factor will cause an increase in the polarization degree of Airy beams. In contrast with Gaussian beams, the degree of polarization of Airy beams is less affected by atmospheric turbulence and propagation distance under the same conditions, which means that Airy beams possess a resilient ability against turbulence-induced perturbations. These results indicate that Airy beams have great potential for applications in long-distance free-space optical communications to improve the performance of a polarization-encoded free-space quantum communication system.
Generalized Airy functions for use in one-dimensional quantum mechanical problems
NASA Technical Reports Server (NTRS)
Eaves, J. O.
1972-01-01
The solution of the one dimensional, time independent, Schroedinger equation in which the energy minus the potential varies as the nth power of the distance is obtained from proper linear combinations of Bessel functions. The linear combinations called generalized Airy functions, reduce to the usual Airy functions Ai(x) and Bi(x) when n equals 1 and have the same type of simple asymptotic behavior. Expressions for the generalized Airy functions which can be evaluated by the method of generalized Gaussian quadrature are obtained.
Quantitative comparison of self-healing ability between Bessel–Gaussian beam and Airy beam
Wen, Wei; Chu, Xiuxiang
2015-09-15
The self-healing ability during propagation process is one of the most important properties of non-diffracting beams. This ability has crucial advantages to light sheet-based microscopy to reduce scattering artefacts, increase the quality of the image and enhance the resolution of microscopy. Based on similarity between two infinite-dimensional complex vectors in Hilbert space, the ability to a Bessel–Gaussian beam and an Airy beam have been studied and compared. Comparing the evolution of the similarity of Bessel–Gaussian beam with Airy beam under the same conditions, we find that Bessel–Gaussian beam has stronger self-healing ability and is more stable than that of Airy beam. To confirm this result, the intensity profiles of Bessel–Gaussian beam and Airy beam with different similarities are numerically calculated and compared.
NASA Technical Reports Server (NTRS)
Constantinides, E. D.; Marhefka, R. J.
1992-01-01
The incomplete Airy integrals serve as canonical functions for the uniform ray optical solutions to several high frequency scattering and diffraction problems that involve a class of integrals characterized by two stationary points that are arbitrarily close to one another or to an integration endpoint. Integrals of such analytical properties describe transition region phenomena associated with composite shadow boundaries. An efficient and accurate method for computing the incomplete Airy functions would make the solutions to such problems useful for engineering purposes. Here, a convergent series solution form for the incomplete Airy functions is derived. Asymptotic expansions involving several terms were also developed and serve as large argument approximations. The combination of the series solution form with the asymptotic formulae provides for an efficient and accurate computation of the incomplete Airy functions. Validation of accuracy is accomplished using direct numerical integration data.
Wei, Bing-Yan; Chen, Peng; Hu, Wei; Ji, Wei; Zheng, Li-Yang; Ge, Shi-Jun; Ming, Yang; Chigrinov, Vladimir; Lu, Yan-Qing
2015-01-01
Researches on Airy beams have grown explosively since the first demonstration in 2007 due to the distinguishing properties of nondiffraction, transverse acceleration and self-healing. To date, a simple and compact approach for generating Airy beams in high quality and efficiency has remained challenging. Here, we propose and demonstrate a liquid crystal (LC) polarization Airy mask (PAM) featured by spatially variant LC azimuthal director. The PAM is fabricated through photoaligning LC via a polarization-sensitive alignment agent suophonic azo dye SD1. Thanks to the special design, a novel feature of polarization-controllable switch between dual Airy beams of orthogonal circular polarization is presented. The molecular-level continuity of LC director significantly improves the quality and efficiency of resultant Airy beams. Besides, the PAM can handle intense light due to the absence of absorptive electrodes. Additional merits of compact size, low cost and broad wavelength tolerance are also exhibited. This work settles a fundamental requirement for Airy beam applications of optical manipulations, biology science and even some uncharted territories. PMID:26626737
Zhang, Yiqi; Belić, Milivoj R; Zhang, Lei; Zhong, Weiping; Zhu, Dayu; Wang, Ruimin; Zhang, Yanpeng
2015-04-20
We study periodic inversion and phase transition of normal, displaced, and chirped finite energy Airy beams propagating in a parabolic potential. This propagation leads to an unusual oscillation: for half of the oscillation period the Airy beam accelerates in one transverse direction, with the main Airy beam lobe leading the train of pulses, whereas in the other half of the period it accelerates in the opposite direction, with the main lobe still leading - but now the whole beam is inverted. The inversion happens at a critical point, at which the beam profile changes from an Airy profile to a Gaussian one. Thus, there are two distinct phases in the propagation of an Airy beam in the parabolic potential - the normal Airy and the single-peak Gaussian phase. The length of the single-peak phase is determined by the size of the decay parameter: the smaller the decay, the smaller the length. A linear chirp introduces a transverse displacement of the beam at the phase transition point, but does not change the location of the point. A quadratic chirp moves the phase transition point, but does not affect the beam profile. The two-dimensional case is discussed briefly, being equivalent to a product of two one-dimensional cases.
Airy pattern approximation of a phased microphone array response to a rotating point source.
Debrouwere, Maarten; Angland, David
2017-02-01
Deconvolution of phased microphone array source maps is a commonly applied technique in order to improve the dynamic range and resolution of beamforming. Most deconvolution algorithms require a point spread function (PSF). In this work, it is shown that the conventional definition of the PSF, based on steering vectors, is changed when the source is rotating. The effect of rotation results in an increase in the resolution and aperture of the array. The concept of virtual array positions created by source rotation is used to derive an approximation of the PSF based on an Airy pattern. The Airy pattern approximation is suitable for use in deconvolution of rotating source maps as it is more accurate and computationally less expensive than the conventional PSF definition. The proposed Airy pattern approximation was tested with both CLEAN and DAMAS deconvolution algorithms. On the same hardware, it was significantly faster when compared to the conventional definition. The limitations of the Airy pattern approximation are shown in a synthesized broadband test case with a high dynamic range. However, in most practical beamforming applications, the proposed Airy pattern approximated PSF for deconvolution is a suitable option considering its accuracy and speed.
Lossless Airy Surface Polaritons in a Metamaterial via Active Raman Gain
Zhang, Qi; Tan, Chaohua; Huang, Guoxiang
2016-01-01
We propose a scheme to realize a lossless propagation of linear and nonlinear Airy surface polaritons (SPs) via active Raman gain (ARG). The system we suggest is a planar interface superposed by a negative index metamaterial (NIMM) and a dielectric, where three-level quantum emitters are doped. By using the ARG from the quantum emitters and the destructive interference effect between the electric and magnetic responses from the NIMM, we show that not only the Ohmic loss of the NIMM but also the light absorption of the quantum emitters can be completely eliminated. As a result, non-diffractive Airy SPs may propagate for very long distance without attenuation. We also show that the Kerr nonlinearity of the system can be largely enhanced due to the introduction of the quantum emitters and hence lossless Airy surface polaritonic solitons with very low power can be generated in the system. PMID:26891795
Lossless Airy Surface Polaritons in a Metamaterial via Active Raman Gain
NASA Astrophysics Data System (ADS)
Zhang, Qi; Tan, Chaohua; Huang, Guoxiang
2016-02-01
We propose a scheme to realize a lossless propagation of linear and nonlinear Airy surface polaritons (SPs) via active Raman gain (ARG). The system we suggest is a planar interface superposed by a negative index metamaterial (NIMM) and a dielectric, where three-level quantum emitters are doped. By using the ARG from the quantum emitters and the destructive interference effect between the electric and magnetic responses from the NIMM, we show that not only the Ohmic loss of the NIMM but also the light absorption of the quantum emitters can be completely eliminated. As a result, non-diffractive Airy SPs may propagate for very long distance without attenuation. We also show that the Kerr nonlinearity of the system can be largely enhanced due to the introduction of the quantum emitters and hence lossless Airy surface polaritonic solitons with very low power can be generated in the system.
Lossless Airy Surface Polaritons in a Metamaterial via Active Raman Gain.
Zhang, Qi; Tan, Chaohua; Huang, Guoxiang
2016-02-19
We propose a scheme to realize a lossless propagation of linear and nonlinear Airy surface polaritons (SPs) via active Raman gain (ARG). The system we suggest is a planar interface superposed by a negative index metamaterial (NIMM) and a dielectric, where three-level quantum emitters are doped. By using the ARG from the quantum emitters and the destructive interference effect between the electric and magnetic responses from the NIMM, we show that not only the Ohmic loss of the NIMM but also the light absorption of the quantum emitters can be completely eliminated. As a result, non-diffractive Airy SPs may propagate for very long distance without attenuation. We also show that the Kerr nonlinearity of the system can be largely enhanced due to the introduction of the quantum emitters and hence lossless Airy surface polaritonic solitons with very low power can be generated in the system.
Bose-Einstein condensation of {alpha} particles and Airy structure in nuclear rainbow scattering
Ohkubo, S.; Hirabayashi, Y.
2004-10-01
It is shown that the dilute density distribution of {alpha} particles in nuclei can be observed in the Airy structure in nuclear rainbow scattering. We have analyzed {alpha}+{sup 12}C rainbow scattering to the 0{sub 2}{sup +} (7.65 MeV) state of {sup 12}C in a coupled-channel method with the precise wave functions for {sup 12}C. It is found that the enhanced Airy oscillations in the experimental angular distributions for the 0{sub 2}{sup +} state is caused by the dilute density distribution of this state in agreement for the idea of Bose-Einstein condensation of the three alpha particles.
Propagation characteristics of Airy beams: dependence upon spatial coherence and wavelength.
Morris, J E; Mazilu, M; Baumgartl, J; Cizmár, T; Dholakia, K
2009-07-20
We generate a broadband "white light" Airy beam and characterize the dependence of the beam properties on wavelength. Experimental results are presented showing that the beam's deflection coefficient and its characteristic length are wavelength dependent. In contrast the aperture coefficient is not wavelength dependent. However, this coefficient depends on the spatial coherence of the beam. We model this behaviour theoretically by extending the Gaussian-Schell model to describe the effect of spatial coherence on the propagation of Airy beams. The experimental results are compared to the model and good agreement is observed.
Nonparaxial scalar Airy light-sheets and their higher-order spatial derivatives
NASA Astrophysics Data System (ADS)
Mitri, F. G.
2017-02-01
Based on the angular spectrum decomposition method in plane waves, a generalized nonparaxial analytical solution for the electric field of a transverse electric Airy light-sheet including its spatial derivatives is formulated and presented. The beam-shape coefficients are expressed by an improper integral, which includes the generation of evanescent waves. The radiated component of the field is computed, and the cross-sectional plots display unique features of the nonparaxial Airy light-sheet and its higher-order derivatives. The results find important applications in predicting/computing the optical scattering, radiation force, and torque on an object using the multipole expansion method in cylindrical coordinates and particle dynamics.
Widely varying giant Goos-Hänchen shifts from Airy beams at nonlinear interfaces.
Chamorro-Posada, Pedro; Sánchez-Curto, Julio; Aceves, Alejandro B; McDonald, Graham S
2014-03-15
We present a numerical study of the giant Goos-Hänchen shifts (GHSs) obtained from an Airy beam impinging on a nonlinear interface. To avoid any angular restriction associated with the paraxial approximation, the analysis is based on the nonlinear Helmholtz equation. We report the existence of nonstandard nonlinear GHSs displaying an extreme sensitivity to the input intensity and the existence of multiple critical values. These intermittent and oscillatory regimes can be explained in terms of competition between critical coupling to a surface mode and soliton emission from the refracted beam component and how this interplay varies with localization of the initial Airy beam.
Schlichting, A.; Sproessig, W.
2008-09-01
We study versions of a generalized Teodorescu transform. In the 2-dimensional case we can describe the asymptotic behaviour by the help of modified Bessel functions. In 3-dimensional case we only have an upper estimate. Such estimates are necessary to prove the convergence of a semi-discretization method for a higher-dimensional analogue of an equation of Airy's type.
Integral representations for products of Airy functions Part 2. Cubic products
NASA Astrophysics Data System (ADS)
Reid, W. H.
Integral representations are obtained for some cubic products of the Airy functions Ai(z) and Bi(z). These integral representations are of the Laplace contour type but they involve the modified Bessel functions of order 16. From these results it is then possible to evaluate a number of definite integrals involving such cubic products.
Propagation of an Airy-Gaussian-Vortex beam in a chiral medium
NASA Astrophysics Data System (ADS)
Hua, Sen; Liu, Youwen; Zhang, Huijie; Tang, Liangzun; Feng, Yunxcai
2017-04-01
Based on the Huygens diffraction integral, the analytical expressions of electric field distribution of the Airy-Gaussian-Vortex (AiGV) beam in a chiral medium are derived, and its propagation properties are investigated. With increasing the value of chiral parameter γ, the parabolic deflection of the LCP light increases and the RCP light decreases respectively. For the first-order AiGV beam with only one positive or negative optical vortex (OV), a half-moon-shaped intensity profile can be observed because of overlap of the OV and the Airy main lobe, and then the main lobe will be reconstructed and the vortex could be recovered after the overlap position. The intensity distribution of AiGV beam, the deflection trajectories of central positions of Airy beam and OV under different competing parameters between Gaussian and Airy terms have been studied. Furthermore, for the second-order counterrotating AiGV beam with positive and negative vortexes, it could be considered the superposition of two first-order AiGV beams with respective positive and negative vortexes. Two vortexes can regenerate during propagation and the intensity distribution the AiGV beam in the far zone can be controlled by adjusting the coordinates of two vortexes.
Reflection and refraction of an Airy beam at a dielectric interface.
Chremmos, Ioannis D; Efremidis, Nikolaos K
2012-06-01
Reflection and refraction of a finite-power Airy beam at the interface between two dielectric media are investigated analytically and numerically. The formulation takes into account the paraxial nature of the optical beams to derive convenient field evolution equations in coordinate frames moving along Snell's refraction and reflection axes. Through numerical simulations, the self-accelerating dynamics of the Airy-like refracted and reflected beams are observed. Of special interest are the cases of critical incidence at Brewster and total-internal-reflection (TIR) angles. In the former case, we find that the reflected beam achieves self-healing, despite the severe suppression of a part of its spectrum, while, in the latter case, the beam remains nearly unaffected except for the Goos-Hänchen shift. The self-accelerating quality persists even if the beam is trapped by multiple TIRs inside a dielectric film. The grazing incidence of an Airy beam at the interface between two media with close refractive indices is also investigated, revealing that the interface can act as a filter depending on the beam scale and tilt. We finally consider reverse refraction and perfect imaging of an Airy beam into a left-handed medium.
Multi-gigahertz, femtosecond Airy beam optical parametric oscillator pumped at 78 MHz
NASA Astrophysics Data System (ADS)
Aadhi, A.; Sharma, Varun; Chaitanya, N. Apurv; Samanta, G. K.
2017-03-01
We report a high power ultrafast Airy beam source producing femtosecond pulses at multi-gigahertz (GHz) repetition rate (RR). Based on intra-cavity cubic phase modulation of an optical parametric oscillator (OPO) designed in high harmonic cavity configuration synchronous to a femtosecond Yb-fiber laser operating at 78 MHz, we have produced ultrafast 2D Airy beam at multi-GHz repetition rate through the fractional increment in the cavity length. While small (<1 mm) crystals are used in femtosecond OPOs to take the advantage of broad phase-matching bandwidth, here, we have exploited the extended phase-matching bandwidth of a 50-mm long Magnesium-oxide doped periodically poled LiNbO3 (MgO:PPLN) crystal for efficient generation of ultrafast Airy beam and broadband mid-IR radiation. Pumping the MgO:PPLN crystal of grating period, Λ = 30 μm and crystal temperature, T = 100 °C using a 5-W femtosecond laser centred at 1064 nm, we have produced Airy beam radiation of 684 mW in ~639 fs (transform limited) pulses at 1525 nm at a RR of ~2.5 GHz. Additionally, the source produces broadband idler radiation with maximum power of 510 mW and 94 nm bandwidth at 3548 nm in Gaussian beam profile. Using an indirect method (change in cavity length) we estimate maximum RR of the Airy beam source to be ~100 GHz.
Multi-gigahertz, femtosecond Airy beam optical parametric oscillator pumped at 78 MHz.
Aadhi, A; Sharma, Varun; Chaitanya, N Apurv; Samanta, G K
2017-03-06
We report a high power ultrafast Airy beam source producing femtosecond pulses at multi-gigahertz (GHz) repetition rate (RR). Based on intra-cavity cubic phase modulation of an optical parametric oscillator (OPO) designed in high harmonic cavity configuration synchronous to a femtosecond Yb-fiber laser operating at 78 MHz, we have produced ultrafast 2D Airy beam at multi-GHz repetition rate through the fractional increment in the cavity length. While small (<1 mm) crystals are used in femtosecond OPOs to take the advantage of broad phase-matching bandwidth, here, we have exploited the extended phase-matching bandwidth of a 50-mm long Magnesium-oxide doped periodically poled LiNbO3 (MgO:PPLN) crystal for efficient generation of ultrafast Airy beam and broadband mid-IR radiation. Pumping the MgO:PPLN crystal of grating period, Λ = 30 μm and crystal temperature, T = 100 °C using a 5-W femtosecond laser centred at 1064 nm, we have produced Airy beam radiation of 684 mW in ~639 fs (transform limited) pulses at 1525 nm at a RR of ~2.5 GHz. Additionally, the source produces broadband idler radiation with maximum power of 510 mW and 94 nm bandwidth at 3548 nm in Gaussian beam profile. Using an indirect method (change in cavity length) we estimate maximum RR of the Airy beam source to be ~100 GHz.
Anomalous change of Airy disk with changing size of spherical particles
NASA Astrophysics Data System (ADS)
Pan, Linchao; Zhang, Fugen; Meng, Rui; Xu, Jie; Zuo, Chenze; Ge, Baozhen
2016-02-01
Use of laser diffraction is considered as a method of reliable principle and mature technique in measurements of particle size distributions. It is generally accepted that for a certain relative refractive index, the size of the scattering pattern (also called Airy disk) of spherical particles monotonically decreases with increasing particle size. This fine structure forms the foundation of the laser diffraction method. Here we show that the Airy disk size of non-absorbing spherical particles becomes larger with increasing particle size in certain size ranges. To learn more about this anomalous change of Airy disk (ACAD), we present images of Airy disk and curves of Airy disk size versus particle size for spherical particles of different relative refractive indices by using Mie theory. These figures reveal that ACAD occurs periodically for non-absorbing particles and will disappear when the absorbing efficiency is higher than certain value. Then by using geometrical optics (GO) approximation, we derive the analytical formulae for the bounds of the size ranges where ACAD occurs. From the formulae, we obtain laws of ACAD as follows: (1) for non-absorbing particles, ACAD occurs periodically, and when the particle size tends to infinity, the period tends to a certain value. As the relative refractive index increases, (2) the particle size ranges where ACAD occurs shift to smaller values, (3) the period of ACAD becomes smaller, and (4) the width of the size ranges where ACAD occurs becomes narrower. In addition, we can predict from the formulae that ACAD also exists for particles whose relative refractive index is smaller than 1.
Multi-gigahertz, femtosecond Airy beam optical parametric oscillator pumped at 78 MHz
Aadhi, A.; Sharma, Varun; Chaitanya, N. Apurv; Samanta, G. K.
2017-01-01
We report a high power ultrafast Airy beam source producing femtosecond pulses at multi-gigahertz (GHz) repetition rate (RR). Based on intra-cavity cubic phase modulation of an optical parametric oscillator (OPO) designed in high harmonic cavity configuration synchronous to a femtosecond Yb-fiber laser operating at 78 MHz, we have produced ultrafast 2D Airy beam at multi-GHz repetition rate through the fractional increment in the cavity length. While small (<1 mm) crystals are used in femtosecond OPOs to take the advantage of broad phase-matching bandwidth, here, we have exploited the extended phase-matching bandwidth of a 50-mm long Magnesium-oxide doped periodically poled LiNbO3 (MgO:PPLN) crystal for efficient generation of ultrafast Airy beam and broadband mid-IR radiation. Pumping the MgO:PPLN crystal of grating period, Λ = 30 μm and crystal temperature, T = 100 °C using a 5-W femtosecond laser centred at 1064 nm, we have produced Airy beam radiation of 684 mW in ~639 fs (transform limited) pulses at 1525 nm at a RR of ~2.5 GHz. Additionally, the source produces broadband idler radiation with maximum power of 510 mW and 94 nm bandwidth at 3548 nm in Gaussian beam profile. Using an indirect method (change in cavity length) we estimate maximum RR of the Airy beam source to be ~100 GHz. PMID:28262823
Dynamics of Finite Energy Airy Beams Carrying Orbital Angular Momentum in Multilevel Atomic Vapors
NASA Astrophysics Data System (ADS)
Wu, Zhenkun; Wang, Shun; Hu, Weifei; Gu, Yuzong
2016-10-01
We numerically investigate the dynamics of inward circular finite-energy Airy beams carrying different orbital angular momentum (OAM) numbers in a close-Λ three-level atomic vapor with the electromagnetically induced transparency (EIT) window. We report that due to the EIT induced by the microwave field, the transverse intensity distribution properties of Airy beam can be feasibly manipulated and modulated through adjusting OAM numbers l and the frequency detuning, as well as the propagation distance, in the multi-level atomic systems. What's more, the rotation of the beam also can be observed with different positions in atomic ensembles. The investigation may provide a useful tool for studying particle manipulation, signal processing and propagation in graded-index (GRIN) fibers.
Wavelength estimation by using the Airy disk from a diffraction pattern with didactic purposes
NASA Astrophysics Data System (ADS)
Rivera-Ortega, Uriel; Pico-Gonzalez, Beatriz
2016-01-01
In this paper a simple and easy to implement method that uses the Airy disk generated from a Fraunhofer diffraction pattern due to a circular aperture will be used to estimate the wavelength of the illuminating laser source. This estimation is based on the measurement of the Airy disk diameter, whose approximation is directly proportional to the wavelength of the light source and to the distance between the aperture and the image plane; and inversely proportional to the diameter of the aperture. Due to the characteristics and versatility of the present proposal, this is perfectly suitable for use in graduate or undergraduate physics laboratories, or even in classrooms for educational and/or demonstrative purposes.
Three-dimensional ultrashort optical Airy beams in an inhomogeneous medium with carbon nanotubes
NASA Astrophysics Data System (ADS)
Zhukov, Alexander V.; Bouffanais, Roland; Belonenko, Mikhail B.; Dvuzhilov, Ilya S.
2017-03-01
In this Letter, we consider the problem of the dynamics of propagation of three-dimensional optical pulses (a.k.a. light bullets) with an Airy profile through a heterogeneous environment of carbon nanotubes. We show numerically that such beams exhibit sustained and stable propagation. Moreover, we demonstrate that by varying the density modulation period of the carbon nanotubes one can indirectly control the pulse velocity, which is a particularly valuable feature for the design and manufacturing of novel pulse delay devices.
Shaping symmetric Airy beam through binary amplitude modulation for ultralong needle focus
Fang, Zhao-Xiang; Gong, Lei; Ren, Yu-Xuan; Vaveliuk, Pablo; Chen, Yue; Lu, Rong-De
2015-11-28
Needle-like electromagnetic field has various advantages for the applications in high-resolution imaging, Raman spectroscopy, as well as long-distance optical transportation. The realization of such field often requires high numerical aperture (NA) objective lens and the transmission masks. We demonstrate an ultralong needle-like focus in the optical range produced with an ordinary lens. This is achieved by focusing a symmetric Airy beam (SAB) generated via binary spectral modulation with a digital micromirror device. Such amplitude modulation technique is able to shape traditional Airy beams, SABs, as well as the dynamic transition modes between the one-dimensional and two-dimensional (2D) symmetric Airy modes. The created 2D SAB was characterized through measurement of the propagating fields with one of the four main lobes blocked by an opaque mask. The 2D SAB was verified to exhibit self-healing property against propagation with the obstructed major lobe reconstructed after a certain distance. We further produced an elongated focal line by concentrating the SAB via lenses with different NAs and achieved an ultralong longitudinal needle focus. The produced long needle focus will be applied in optical, chemical, and biological sciences.
NASA Astrophysics Data System (ADS)
Akemann, G.; Bender, M.
2010-10-01
We consider a family of chiral non-Hermitian Gaussian random matrices in the unitarily invariant symmetry class. The eigenvalue distribution in this model is expressed in terms of Laguerre polynomials in the complex plane. These are orthogonal with respect to a non-Gaussian weight including a modified Bessel function of the second kind, and we give an elementary proof for this. In the large n limit, the eigenvalue statistics at the spectral edge close to the real axis are described by the same family of kernels interpolating between Airy and Poisson that was recently found by one of the authors for the elliptic Ginibre ensemble. We conclude that this scaling limit is universal, appearing for two different non-Hermitian random matrix ensembles with unitary symmetry. As a second result we give an equivalent form for the interpolating Airy kernel in terms of a single real integral, similar to representations for the asymptotic kernel in the bulk and at the hard edge of the spectrum. This makes its structure as a one-parameter deformation of the Airy kernel more transparent.
The software package AIRY 7.0: new efficient deconvolution methods for post-adaptive optics data
NASA Astrophysics Data System (ADS)
La Camera, Andrea; Carbillet, Marcel; Prato, Marco; Boccacci, Patrizia; Bertero, Mario
2016-07-01
The Software Package AIRY (acronym of Astronomical Image Restoration in interferometrY) is a complete tool for the simulation and the deconvolution of astronomical images. The data can be a post-adaptive-optics image of a single dish telescope or a set of multiple images of a Fizeau interferometer. Written in IDL and freely downloadable, AIRY is a package of the CAOS Problem-Solving Environment. It is made of different modules, each one performing a specific task, e.g. simulation, deconvolution, and analysis of the data. In this paper we present the last version of AIRY containing a new optimized method for the deconvolution problem based on the scaled-gradient projection (SGP) algorithm extended with different regularization functions. Moreover a new module based on our multi-component method is added to AIRY. Finally we provide a few example projects describing our multi-step method recently developed for deblurring of high dynamic range images. By using AIRY v.7.0, users have a powerful tool for simulating the observations and for reconstructing their real data.
Nylk, Jonathan; McCluskey, Kaley; Aggarwal, Sanya; Tello, Javier A.; Dholakia, Kishan
2016-01-01
We have investigated the effect of Airy illumination on the image quality and depth penetration of digitally scanned light-sheet microscopy in turbid neural tissue. We used Fourier analysis of images acquired using Gaussian and Airy light-sheets to assess their respective image quality versus penetration into the tissue. We observed a three-fold average improvement in image quality at 50 μm depth with the Airy light-sheet. We also used optical clearing to tune the scattering properties of the tissue and found that the improvement when using an Airy light-sheet is greater in the presence of stronger sample-induced aberrations. Finally, we used homogeneous resolution probes in these tissues to quantify absolute depth penetration in cleared samples with each beam type. The Airy light-sheet method extended depth penetration by 30% compared to a Gaussian light-sheet. PMID:27867712
Cottrell, Don M; Davis, Jeffrey A; Berg, Cassidy A; Freeman, Christopher Li
2014-04-01
There is great interest in Airy beams because they appear to propagate in a curved path. These beams are usually generated by inserting a cubic phase mask onto the input plane of a Fourier transform system. Here, we utilize a fast Fresnel diffraction algorithm to easily derive both the propagation dynamics and the Gouy phase shift for these beams. The trajectories of these beams can be modified by adding additional linear and quadratic phase terms onto the cubic phase mask. Finally, we have rewritten the equations regarding the propagating Airy beams completely in laboratory coordinates for use by experimentalists. Experimental results are included. We expect that these results will be of great importance in applications of Airy beams.
Results of the Pronghorn field test using passive infrared spectroradiometers: CATSI and AIRIS
NASA Astrophysics Data System (ADS)
Jensen, James O.; Theriault, Jean-Marc; Bradette, Claude; Gittins, Christopher M.; Marinelli, William J.
2002-08-01
The Pronghorn Field Tests were held at the Nevada Test Site for a two-week period in June 2001. Two passive infrared sensors were tested for inclusion into the Joint Service Wide Area Detection Program. The Adaptive InfraRed Imaging Spectroradiometer (AIRIS) and Compact Atmospheric Sounding Interferometer (CATSI) systems were tested with good results. This field test was a joint effort between the US (SBCCOM) and Canada (DREV). Various chemicals were detected and quantified from a distance of 1.5 kilometers. Passive ranging of Chemical Plumes was demonstrated.
Results from the Pronghorn field test using passive infrared spectroradiometers-CATSI and AIRIS
NASA Astrophysics Data System (ADS)
Jensen, James O.; Theriault, Jean-Marc; Bradette, Claude; Gittins, Christopher M.; Marinelli, William J.
2002-02-01
The Pronghorn Field Tests were held at the Nevada Test Site for a two-week period in June 2001. Two passive infrared sensors were tested for inclusion into the Joint Service Wide Area Detection Program. The Adaptive InfraRed Imaging Spectroradiometer (AIRIS) and Compact ATmospheric Sounding Interferometer (CATSI) systems were tested with good results. This field test was a joint effort between the U.S (SBCCOM) and Canada (DREV). Various chemicals were detected and quantified from a distance of 1.5 kilometers. Passive ranging of Chemical Plumes was demonstrated.
Proposal and design of Airy-based rocket pulses for invariant propagation in lossy dispersive media.
Preciado, Miguel A; Sugden, Kate
2012-12-01
A novel (to our knowledge) kind of Airy-based pulse with an invariant propagation in lossy dispersive media is proposed. The basic principle is based on an optical energy trade-off between different parts of the pulse caused by the chromatic dispersion, which is used to compensate the attenuation losses of the propagation medium. Although the ideal concept of the proposed pulses implies infinite pulse energy, the numerical simulations show that practical finite energy pulses can be designed to obtain a partially invariant propagation over a finite distance of propagation.
Test drilling and aquifer test in the Marburg schist near Mount Airy, Frederick County, Maryland
Meyer, Gerald
1955-01-01
This memorandum summarizes briefly the data obtained by test drilling and in an aquifer test at Mount Airy, Md. The tests were a part of the State - Federal cooperative study of the ground-water resources of Frederick County, and it is intended that a more complete analysis of the test data will be included in a future report describing the ground-water resource of Frederick County. The purpose of this memorandum is to make the test data immediately available to the general public. Mount Airy is located along the Carroll-Frederick County boundary bout 2 miles north of the intersection of U.S. Highway 40 with the county boundary. Its population is approximately 1,000. The municipal well field, consisting of two drilled wells (fig. 1) is in a valley about one-half mile west of the center of Mount Airy, within about 400 feet of a small stream, and north of Prospect Road. Well 1, about 40 feet north of Prospect Road, is 125 feet deep, 8 inches in diameter, and reportedly yielded 265 gallons per minute (gpm) in 1947 and 201 gpm in a half hour test in March 1955. The writer determined during the tests described in this memorandum that the well has about 34 feet of casing. Well 2, 85 feet north of well 1, is 96 feet deep, 8 inches in diameter, and reportedly yielded 120 gpm in 1947 and 127 gpm in a half hour test in March 1955. The wells are equipped with deep-well turbine pumps powered by electric motors. Cenorally only well 1 is used, and it is pumped for only a few short intervals each day to meet the water requirements of the town (about 75,000 - 80,000 gallons daily). The reported yields of these wells are considerably higher than the average for crystalline-rock wells in the Piedmont of Maryland. The test drilling was done under contract with Edward I. Brown, well driller, between May 3 and May 12, 1955. Water-supply facilities of the town of Mount Airy were kindly made available for the aquifer tests from May 22 to May 30, 1955. The pumping tests consisted of a
Chirped Airy-Gaussian beam in a medium with a parabolic potential
NASA Astrophysics Data System (ADS)
Zhang, Liping; Deng, Fu; Peng, Yulian; Chen, Bo; Peng, Xi; Li, Dongdong; Deng, Dongmei
2017-01-01
By solving the normalized dimensionless linear parabolic (Schrödinger-like) equations in the paraxial approximation, we can obtain the analytic solutions of the chirped Airy-Gaussian (CAiG) beam in a medium with a parabolic potential. We study the propagation properties of the finite energy CAiG beam in a parabolic potential and the influence of the distribution factor and the chirped factor on the CAiG beam. The propagation of the CAiG beam changes drastically with the distribution factor increasing: the CAiG beam tends to the chirped Airy beam when the distribution factor is very small; while as the distribution factor increases further, the CAiG beam tends to the chirped Gaussian beam. At the same time, the CAiG beam with a chirp has big changes when the chirped factor is increasing: the multi-peak structure is not obvious, the accelerated velocity and the peak intensity are larger, but the period does not change; when the CAiG beam has a quadratic chirp, the maximum intensity of the CAiG beam becomes smaller and the envelope is gradually smoother with the increasing of the chirped factor.
NASA Astrophysics Data System (ADS)
Konobeeva, Natalia N.; Belonenko, Mikhail B.
2017-01-01
Propagation of few-cycle optical Airy pulse through the array of semiconductor carbon nanotubes (CNTs) is considered. CNTs are supposed to contain multilevel impurities. In our study, we have neglected transitions between the valence and the conduction bands. As a result, we have revealed the dependence of the pulse form on the parameters of energy.
Fractional calculus transmutation for the Airy WKB solutions and Stokes phenomenon
NASA Astrophysics Data System (ADS)
Kiryakova, Virginia
2016-12-01
We apply the transmutation method to give a new explanation of the Stokes phenomenon for the Airy differential equation and of the change of the coeffcients in its asymptotic solutions for large values of argument in different parts of the complex plane. As a transmutation operator, a Weyl type fractional order integral is used. But this scheme is a special case of the so-called Poisson- Sonine-Dimovski transmutation operators related to the hyper-Bessel differential equations of arbitrary integer order, and of the generalized fractional calculus operators related to differential equations of fractional multi-order and their solutions, including a number of special functions. We analyze also the previous results of other authors and suggest some perspectives to use the same method in more general cases.
Predicting the past: ancient eclipses and Airy, Newcomb, and Huxley on the authority of science.
Stanley, Matthew
2012-06-01
Greek historical accounts of ancient eclipses were an important, if peculiar, focus of scientific attention in the nineteenth century. Victorian-era astronomers tried to correct the classical histories using scientific methods, then used those histories as data with which to calibrate their lunar theories, then rejected the histories as having any relevance at all. The specific dating of these eclipses--apparently a simple exercise in celestial mechanics--became bound up with tensions between scientific and humanistic approaches to the past as well as with wider social debates over the power and authority of science in general. The major figures discussed here, including G. B. Airy, Simon Newcomb, and T. H. Huxley, argued that the critical question was whether science could speak authoritatively about the past. To them, the ability of science to talk about the past indicated its power to talk about the future; it was also the fulcrum of fierce boundary disputes among science, history, and religion.
Quantum oscillations in the kinetic energy density: Gradient corrections from the Airy gas
NASA Astrophysics Data System (ADS)
Lindmaa, Alexander; Mattsson, Ann E.; Armiento, Rickard
2014-03-01
We show how one can systematically derive exact quantum corrections to the kinetic energy density (KED) in the Thomas-Fermi (TF) limit of the Airy gas (AG). The resulting expression is of second order in the density variation and we demonstrate how it applies universally to a certain class of model systems in the slowly varying regime, for which the accuracy of the gradient corrections of the extended Thomas-Fermi (ETF) model is limited. In particular we study two kinds of related electronic edges, the Hermite gas (HG) and the Mathieu gas (MG), which are both relevant for discussing periodic systems. We also consider two systems with finite integer particle number, namely non-interacting electrons subject to harmonic confinement as well as the hydrogenic potential. Finally we discuss possible implications of our findings mainly related to the field of functional development of the local kinetic energy contribution.
Ismail, Nur; Kores, Cristine Calil; Geskus, Dimitri; Pollnau, Markus
2016-07-25
We systematically characterize the Fabry-Pérot resonator. We derive the generic Airy distribution of a Fabry-Pérot resonator, which equals the internal resonance enhancement factor, and show that all related Airy distributions are obtained by simple scaling factors. We analyze the textbook approaches to the Fabry-Pérot resonator and point out various misconceptions. We verify that the sum of the mode profiles of all longitudinal modes is the fundamental physical function that characterizes the Fabry-Pérot resonator and generates the Airy distribution. Consequently, the resonator losses are quantified by the linewidths of the underlying Lorentzian lines and not by the measured Airy linewidth. Therefore, we introduce the Lorentzian finesse which provides the spectral resolution of the Lorentzian lines, whereas the usually considered Airy finesse only quantifies the performance of the Fabry-Pérot resonator as a scanning spectrometer. We also point out that the concepts of linewidth and finesse of the Airy distribution of a Fabry-Pérot resonator break down at low reflectivity. Furthermore, we show that a Fabry-Pérot resonator has no cut-off resonance wavelength. Finally, we investigate the influence of frequency-dependent mirror reflectivities, allowing for the direct calculation of its deformed mode profiles.
On the joint distribution of the maximum and its position of the Airy2 process minus a parabola
NASA Astrophysics Data System (ADS)
Baik, Jinho; Liechty, Karl; Schehr, Grégory
2012-08-01
The maximal point of the Airy2 process minus a parabola is believed to describe the scaling limit of the end-point of the directed polymer in a random medium. This was proved to be true for a few specific cases. Recently, two different formulas for the joint distribution of the location and the height of this maximal point were obtained, one by Moreno Flores, Quastel, and Remenik, and the other by Schehr. The first formula is given in terms of the Airy function and an associated operator, and the second formula is expressed in terms of the Lax pair equations of the Painlevé II equation. We give a direct proof that these two formulas are the same.
NASA Astrophysics Data System (ADS)
Gil, Amparo; Segura, Javier; Temme, Nico M.
2003-04-01
The use of a uniform Airy-type asymptotic expansion for the computation of the modified Bessel functions of the third kind of imaginary orders (Kia(x)) near the transition point x=a, is discussed. In A. Gil et al., Evaluation of the modified Bessel functions of the third kind of imaginary orders, J. Comput. Phys. 17 (2002) 398-411, an algorithm for the evaluation of Kia(x) was presented, which made use of series, a continued fraction method and nonoscillating integral representations. The range of validity of the algorithm was limited by the singularity of the steepest descent paths near the transition point. We show how uniform Airy-type asymptotic expansions fill the gap left by the steepest descent method.
NASA Astrophysics Data System (ADS)
Liu, Weiwei; Lu, Yao; Gong, Lei; Chu, Xiuxiang; Xue, Guosheng; Ren, Yuxuan; Zhong, Mincheng; Wang, Ziqiang; Zhou, Jinhua; Li, Yinmei
2016-07-01
A symmetric Airy beam (SAB) autofocuses during free space propagation. Such autofocusing SAB is useful in optical manipulation and biomedical imaging. However, its inherently limited autofocusing property may degrade the performance of the SAB in those applications. To enhance the autofocus, a symmetric apodization mask was proposed to regulate the SAB. In combination with the even cubic phase that shapes the SAB, this even exponential function mask with an adjustable parameter regulates the contribution of different frequency spectral components to the SAB. The propagation properties of this new amplitude modulated SAB (AMSAB) were investigated both theoretically and experimentally. Simulation shows that the energy distribution and autofocusing property of an AMSAB can be adjusted by the exponential amplitude modulation. Especially, the beam energy will be more concentrated in the central lobe once the even cubic phase is modulated by the mask with a higher proportion of high-frequency spectral components. Consequently, the autofocusing property and axial gradient force of AMSABs are efficiently enhanced. The experimental generation and characterization for AMSABs were implemented by modulating the collimated beam with a phase-only spatial light modulator. The experimental results well supported the theoretical predictions. With the ability to enhance the autofocus, the proposed exponential apodization modulation will make SAB more powerful in various applications, including optical trapping, fluorescence imaging and particle acceleration.
NASA Astrophysics Data System (ADS)
Zhi, Dong; Tao, Rumao; Zhou, Pu; Ma, Yanxing; Wu, Wuming; Wang, Xiaolin; Si, Lei
2017-03-01
A new ring Airy Gaussian (RAiG) vortex beam generation method by coherent combination of Gaussian beam array has been proposed. To validate the feasibility of this method, the propagation properties of the RAiG vortex beam and the coherent combining beam in vacuum have been studied and analyzed. From the comparisons of the intensity distributions and phase patterns along the propagation path, we can conclude that the coherent combining beam has the same properties as those of the ideal RAiG vortex beam. So this method can be used to obtain RAiG vortex beam in practice. Then the general analytical expression of the root-mean-square (RMS) beam width of the RAiG vortex beam, which is appropriately generated by coherent combining method, through anisotropic non-Kolmogorov turbulence has been derived. The influence of anisotropic turbulence on RMS beam width of the generated RAiG vortex beam has been numerically calculated. This generation method has good appropriation to the ideal RAiG vortex beam and is very useful for deriving the analytical expression of propagation properties through a random media. The conclusions are useful in practical applications, such as laser communication and remote sensing systems.
NASA Astrophysics Data System (ADS)
Perkins, Adam
2001-12-01
In the absence of a scientific civil service the governments of Victoria's reign had few public servants to consult when it came to the requirement for specialist scientific and technological advice - and this was at the height of the industrial revolution when the enormous changes wrought were affecting the whole population of Britain. So governments turned to one man of cast-iron probity and unparalleled credentials: George Airy. Though his formal scientific training was in mathematics and astronomy, not the engineering and thermodynamics that the industrial age might have called for, Airy gave of his time and energy to the full. But what were the purposes of the commissions? When did they sit? Who ran the Royal Observatory in Airy's absence? Only recently have the original papers in the RGO Archives been plumbed in any depth and the answers to these questions make an intriguing story.
NASA Astrophysics Data System (ADS)
Al Sdran, N.; Maiz, F.
2016-06-01
The numerical solutions of the time independent Schrödinger equation of different one-dimensional potentials forms are sometime achieved by the asymptotic iteration method. Its importance appears, for example, on its efficiency to describe vibrational system in quantum mechanics. In this paper, the Airy function approach and the Numerov method have been used and presented to study the oscillator anharmonic potential V(x) = Ax2α + Bx2, (A>0, B<0), with (α = 2) for quadratic, (α =3) for sextic and (α =4) for octic anharmonic oscillators. The Airy function approach is based on the replacement of the real potential V(x) by a piecewise-linear potential v(x), while, the Numerov method is based on the discretization of the wave function on the x-axis. The first energies levels have been calculated and the wave functions for the sextic system have been evaluated. These specific values are unlimited by the magnitude of A, B and α. It's found that the obtained results are in good agreement with the previous results obtained by the asymptotic iteration method for α =3.
NASA Astrophysics Data System (ADS)
Soloman Raju, Thokala
2015-07-01
We explore the exact optical similaritons of a generalized nonlinear Schrödinger equation (GNLSE) with space-time modulated dispersion, nonlinearity, external potential and inhomogeneous source. It is shown here that this equation appertains to the description of wave propagation through asymmetric twin-core fibers in which we control the dynamics of the pulse propagating through passive fiber by controlling the dynamics of the self-similar wave propagating through the active fiber, due to the linear coupling between them. By utilizing multivariate similarity transformation, we map the nonautonomous GNLSE to standard NLSE with a homogeneous external source. Furthermore, by using Möbius transformation, we find periodic waves, solitary waves, and pure cnoidal and pure snoidal solutions as exact solutions. As an application, we explicate the mechanism to control the dynamical behaviors of these similaritons for a spatial Airy and Bessel modulated nonlinearity.
Strehl-constrained reconstruction of post-adaptive optics data and the Software Package AIRY, v. 6.1
NASA Astrophysics Data System (ADS)
Carbillet, Marcel; La Camera, Andrea; Deguignet, Jérémy; Prato, Marco; Bertero, Mario; Aristidi, Éric; Boccacci, Patrizia
2014-08-01
We first briefly present the last version of the Software Package AIRY, version 6.1, a CAOS-based tool which includes various deconvolution methods, accelerations, regularizations, super-resolution, boundary effects reduction, point-spread function extraction/extrapolation, stopping rules, and constraints in the case of iterative blind deconvolution (IBD). Then, we focus on a new formulation of our Strehl-constrained IBD, here quantitatively compared to the original formulation for simulated near-infrared data of an 8-m class telescope equipped with adaptive optics (AO), showing their equivalence. Next, we extend the application of the original method to the visible domain with simulated data of an AO-equipped 1.5-m telescope, testing also the robustness of the method with respect to the Strehl ratio estimation.
NASA Astrophysics Data System (ADS)
Mirab, Hadi; Fathi, Reza; Jahangiri, Vahid; Ettefagh, Mir Mohammad; Hassannejad, Reza
2015-12-01
One of the new methods for powering low-power electronic devices at sea is a wave energy harvesting system. In this method, piezoelectric material is employed to convert the mechanical energy of sea waves into electrical energy. The advantage of this method is based on avoiding a battery charging system. Studies have been done on energy harvesting from sea waves, however, considering energy harvesting with random JONSWAP wave theory, then determining the optimum values of energy harvested is new. This paper does that by implementing the JONSWAP wave model, calculating produced power, and realistically showing that output power is decreased in comparison with the more simple airy wave model. In addition, parameters of the energy harvester system are optimized using a simulated annealing algorithm, yielding increased produced power.
NASA Astrophysics Data System (ADS)
Suhendi, Endi; Syariati, Rifki; Noor, Fatimah A.; Kurniasih, Neny; Khairurrijal
2014-03-01
We modeled a tunneling current in a p-n junction based on armchair graphene nanoribbons (AGNRs) by using an Airy function approach (AFA) and a transfer matrix method (TMM). We used β-type AGNRs, in which its band gap energy and electron effective mass depends on its width as given by the extended Huckel theory. It was shown that the tunneling currents evaluated by employing the AFA are the same as those obtained under the TMM. Moreover, the calculated tunneling current was proportional to the voltage bias and inversely with temperature.
Suhendi, Endi; Syariati, Rifki; Noor, Fatimah A.; Khairurrijal; Kurniasih, Neny
2014-03-24
We modeled a tunneling current in a p-n junction based on armchair graphene nanoribbons (AGNRs) by using an Airy function approach (AFA) and a transfer matrix method (TMM). We used β-type AGNRs, in which its band gap energy and electron effective mass depends on its width as given by the extended Huckel theory. It was shown that the tunneling currents evaluated by employing the AFA are the same as those obtained under the TMM. Moreover, the calculated tunneling current was proportional to the voltage bias and inversely with temperature.
NASA Astrophysics Data System (ADS)
Wu, Zhenkun; Gu, Yuzong
2016-12-01
The propagation of two-dimensional beams is analytically and numerically investigated in strongly nonlocal nonlinear media (SNNM) based on the ABCD matrix. The two-dimensional beams reported in this paper are described by the product of the superposition of generalized Laguerre-Gaussian (LG), Hermite-Gaussian (HG), Bessel-Gaussian (BG), and circular Airy (CA) beams, carrying an orbital angular momentum (OAM). Owing to OAM and the modulation of SNNM, we find that the propagation of these two-dimensional beams exhibits complete rotation and periodic inversion: the spatial intensity profile first extends and then diminishes, and during the propagation the process repeats to form a breath-like phenomenon.
NASA Astrophysics Data System (ADS)
Cheng, Ke; Jiao, Liyang; Zhong, Xianqiong
2016-05-01
Based on the vector angular spectrum representation and stationary phase method, the analytical far-field vectorial expressions of radial noncanonical vortex Airy beam arrays (NVAiBAs) and radial noncanonical vortex Gaussian beam arrays (NVGBAs) are derived, and used to investigate their far-field vectorial properties, e.g. center optical vortices and energy fluxes of these corresponding beams, where the effect of noncanonical strength, topological charge, initial phase index and the number of beamlet on far-field vectorial properties of these corresponding beams is emphasized, respectively. The results show that the topological charge of center optical vortices in the far field is equal to initial phase index for the case of the radial NVAiBAs, whereas for radial NVGBAs the topological charge not only lies on initial phase index, but also is closely related to the odevity and sign of optical vortices embedded in beamlet, where mathematical analysis is made to explain the topological charge of center optical vortices, and the limitation of the number of beamlet to the topological charge of center optical vortices is also discussed. In addition, energy fluxes of radial NVAiBAs and NVGBAs exhibit different space orientations by controlling noncancial strength and present larger dark zones by increasing topological charge of beamlet, respectively. Finally, the relationship between the center optical vortices and energy fluxes of radial NVAiBAs and NVGBAs in even or odd N beamlets is also revealed, respectively.
Korda, V. Yu.; Molev, A. S.; Klepikov, V. F.; Korda, L. P.
2009-02-15
We present the results of the model-independent analysis of Airy structures in the {sup 16}O+{sup 12}C and {sup 16}O+{sup 16}O elastic scattering differential cross sections at 13-22 MeV/nucleon. The analysis has been performed with help of a procedure based on the application of the evolutionary algorithm, which enables us to extract the nuclear part of the scattering matrix S{sub N}(l) as a complex function of angular momentum directly from the scattering data. Contrary to the commonly used model approaches, our procedure gives the better fits and leads to the S{sub N}(l) representations defined by the moduli and the nuclear phases exhibiting smooth monotonic dependencies on l.
NASA Astrophysics Data System (ADS)
Mitri, F. G.
2016-10-01
Stemming from the law of the conservation of energy in an elastic medium, this work extends the scope of the previous analysis for a scatterer immersed in a nonviscous liquid [F. G. Mitri, Ultrasonics 62, 20-26 (2015)] to the case of a (viscous) fluid circular cylinder cross-section encased in a homogeneous, isotropic, elastic matrix. Analytical expressions for the absorption, scattering, and extinction efficiencies (or cross-sections) are derived for "elastic-sheets" (i.e., finite beams in 2D propagating in elastic media) of arbitrary wavefront, in contrast to the ideal case of plane waves of infinite extent. The mathematical expressions are formulated in generalized partial-wave series expansions in cylindrical coordinates involving the beam-shape coefficients of finite elastic-sheet beams with arbitrary wavefront, and the scattering coefficients of the fluid cylinder encased in the elastic matrix. The analysis shows that in elastodynamic scattering, both the scattered L-wave as well as the scattered T-wave contribute to the time-averaged scattered efficiency (or power). However, the extinction efficiency only depends on the scattering coefficients characterizing the same type (L or T) as the incident wave. Numerical computations for the (non-dimensional energy) efficiency factors such as the absorption, scattering, and extinction efficiencies of a circular cylindrical viscous fluid cavity embedded in an elastic aluminum matrix are performed for nonparaxial focused Gaussian and Airy elastic-sheet beams with arbitrary longitudinal and transverse normally-polarized (shear) wave incidences in the Rayleigh and resonance regimes. A series of elastic resonances are manifested in the plots of the efficiencies as the non-dimensional size parameters for the L- and T-waves are varied. As the beam waist for the nonparaxial Gaussian beam increases, the plane wave result is recovered, while for a tightly focused wavefront, some of the elastic resonances can be suppressed
Roberts, Jodie I; Beatty, Jennifer K; Peplowski, Michael A; Keough, Michael B; Yipp, Bryan G; Hollenberg, Morley D; Beck, Paul L
2015-12-04
The Leaders in Medicine (LIM) Program at the University of Calgary hosted its 6th Annual Research Symposium on November 14, 2014, showcasing the quality and breadth of work performed by students at the Cumming School of Medicine. Participation at this year's event was our most successful to date, with a total of six oral and 77 poster presentations during the afternoon symposium. For a detailed description of the work presented at the symposium, please see the Proceedings from the 6th Annual University of Calgary Leaders in Medicine Research Symposium published in this issue of Clinical and Investigative Medicine.
Atmospherics: A Look at the Earth's Airy Shell.
ERIC Educational Resources Information Center
Byalko, A. V.
1991-01-01
Describes differences in the composition, pressure, and temperature at distinct altitudes of the Earth's atmosphere from the point of view of physical laws. Discusses the genesis and importance of ozone, thermal radiation and the "layer cake" arrangement of the atmosphere, and solar energy in connection with thermal equilibrium. (JJK)
Pulse Capability of the AIRI Lead Chloride Electrode.
1979-11-01
DISCHARGE RATE ON PULSE BEHAVIOUR .. . 8 INFLUENCE OF PULSE LOAD ON PULSE BEHAVIOUR . ........... 10 CONCLUSION. ............................... 15 DESIGN OF A...source now in use is a seawater-activated battery in which the anode is a magnesium alloy and the cathode a silver chloride electrode. These batteries...in 3.25% NaCI (by weight) dissolved in distilled water. Temperatures ranged from 220 to 250. For the anode the magnesium alloy AZ61 was used (6
Psychometric Properties of the Affect Intensity and Reactivity Measure Adapted for Youth (AIR-Y)
ERIC Educational Resources Information Center
Jones, Rachel E.; Leen-Feldner, Ellen W.; Olatunji, Bunmi O.; Reardon, Laura E.; Hawks, Erin
2009-01-01
A valid and reliable instrument for measuring affect intensity does not exist for adolescents; such a measure may help to refine understanding of emotion among youths. The purpose of the current study was to evaluate the psychometric properties and clinical relevance of a measure of affect intensity adapted for youths. Two hundred five community…
No Time for the "Airy Fairy": Teacher Perspectives on Creative Writing in High Stakes Environments
ERIC Educational Resources Information Center
Frawley, Emily
2014-01-01
This paper discusses a research project undertaken to examine teachers' perceptions of creative writing in the senior English curriculum. It was a case study undertaken in a state high school in Melbourne under the Victorian Certificate of Education (VCE). The project investigated the challenges facing English teachers as they prepare students to…
Starch-based aerogels: airy materials from amylose-sodium palmitate inclusion complexes
Technology Transfer Automated Retrieval System (TEKTRAN)
Aerogels are a class of interesting low density porous materials prepared by replacing the water phase contained within a hydrogel with a gas phase while maintaining the three dimensional network structure of the gel. The investigation of starch and hydrocolloid-based aerogels has received attentio...
Two new cembranoids from the leaves of Croton longissimus Airy Shaw.
Kawakami, Susumu; Matsunami, Katsuyoshi; Otsuka, Hideaki; Lhieochaiphant, Duangporn; Lhieochaiphant, Sorasak
2013-04-01
Two new cembrane-type diterpenoids (1 and 2) along with five known compounds (3-7) were isolated from leaves of Croton longissimus collected in Thailand. Their structures were elucidated from spectroscopic evidence and compound 4 was found by HPLC analysis to be identical to oblongionoside B-a compound isolated from Croton oblongifolius-including the absolute configuration at the C-9 position.
2005-02-01
through the closely-coupled Fabry-Perot tunable filter, which is operated at ambient temperature. An integral Stirling -Cycle cryocooler maintains the...which about 70 watts is from the detector cryocooler and the remainder from the electronics. The sensor unit is air-cooled and uses a series of heat
Brooks, Ross
2015-01-01
The hegemony of the two-sex paradigm in the European scientific imagination and wider culture did not automatically equate to the hegemony of two discrete genders. In fact, two sexes facilitated a variety of gender choices: two singular and a number of double or otherwise intersexed (most commonly referred to as "hermaphrodite" or "bisexual" in its anatomical sense). This article explores some key British medical and allied scientific texts, with reference to associated Continental literature, as a means of illustrating the complexity of the two-sex paradigm and the unexpected transformation of gender possibilities that it helped produce through the early and middle decades of the nineteenth century. Discourses surrounding the first direct observations of the earliest development of fetal urinogenital anatomy were pivotal. The prevailing view that the incipient embryo was sexually undifferentiated (a paragon of the one-sex paradigm) was challenged by the Edinburgh anatomist Robert Knox, initially as he sought to bolster his professional reputation at the height of the Burke and Hare "body-snatching" scandal. Knox suggested that every embryo began life in an essentially dual-sexed state, an individual's sex anatomy depending on the greater or lesser development of component female and male structures. Greater clarification on the contested status of the homology-hermaphrodite distinction was achieved with the discovery of the early co-existence of the excretory duct of the Wolffian body (mesonephric duct) and the Müllerian duct (paramesonephric duct), an observation that made anatomical bisexuality difficult to ignore. The nineteenth-century's greatest champion of primordial hermaphroditism was Charles Darwin who was pivotal in phylogenizing the principle and establishing the premise that (in his own words) "Every man & woman is hermaphrodite," a foundation stone of late-nineteenth-century sexology.
2012-09-01
λ2= airiairi airi airi p MM T D , 2 , 3 24 , 11 109542.5 Ω + ×= σ 2 , , airii airi σσσ += airiiairi εεε ×=, 15 ti e and i is the sur ace free...tube temperature. 6. During numerous combustor and full scale engine tests in SAMPLE III, volatile particles appear to exist throughout the
Effects of Photon Noise on Unconstrained Minimization Techniques for Iterative Blind Deconvolution.
1994-12-01
the Airy disk, these zeros correspond to the radial points where the irradiance for an Airy function is zero. Sir George Biddell Airy (1801-1892) first...radial distance from the center of the array to the first zero in the true PSF, when the PSF is an Airy function. If the PSF remains constant for all...correlation of support region size with definable areas within the impulse response or true PSF. Since a single PSF in the form of an Airy function is used
Federal Register 2010, 2011, 2012, 2013, 2014
2012-11-06
... Robotics, Sherman Oaks, CA; Global Technical Systems, Virginia Beach, VA; Hurley IR, Mount Airy, MD; ICx Tactical Platforms, Forest Park, GA; Innovative Signal Analysis, Inc., Richardson, TX; Liquid...
Generation of self-healing and transverse accelerating optical vortices
NASA Astrophysics Data System (ADS)
Wei, Bing-Yan; Chen, Peng; Ge, Shi-Jun; Duan, Wei; Hu, Wei; Lu, Yan-Qing
2016-09-01
Self-healing and transverse accelerating optical vortices are generated via modulating Gaussian beams through subsequent liquid crystal q-plate and polarization Airy mask. We analyze the propagation dynamics of these vortex Airy beams, and find that they possess the features of both optical vortices and Airy beams. Topological charges and characteristics of nondiffraction, self-healing, and transverse acceleration are experimentally verified. In addition, vortex Airy beams with both topological charge and radial index are demonstrated and mode switch among Gaussian, vortex, vector, Airy beams and their combinations can be acquired easily. Our design provides a flexible and highly efficient way to generate unique optical vortices with self-healing and transverse acceleration properties, and facilitates prospective applications in optics and photonics.
An Update to the Budget and Economic Outlook: 2014 to 2024
2014-08-01
with contributions from analysts in other divisions; that work was supervised by Peter Fontaine, Theresa Gullo, Holly Harvey, Janet Airis, Tom Bradley ...Assistance Program, refugee assistance Emily Stern Disability Insurance, Supplemental Security Income Natural and Physical Resources Megan Carroll Energy
Multiple Beam Optical Processing
1989-12-01
with these characteristics are applicable in telecommunication switches, parallel processor interconnections, and database machines . Many materials...Bistability occurs where the straight line has three intersections. The upper branch of a bistable loop in Fig. 2.3 corresponds to the, negative-slope side ...of the Airy-function curve in Fig. 2.2, while the unstable state shown in dashed line in Fig. 2.3 corresponds to the positive-slope side of the Airy
Computer program for Bessel and Hankel functions
NASA Technical Reports Server (NTRS)
Kreider, Kevin L.; Saule, Arthur V.; Rice, Edward J.; Clark, Bruce J.
1991-01-01
A set of FORTRAN subroutines for calculating Bessel and Hankel functions is presented. The routines calculate Bessel and Hankel functions of the first and second kinds, as well as their derivatives, for wide ranges of integer order and real or complex argument in single or double precision. Depending on the order and argument, one of three evaluation methods is used: the power series definition, an Airy function expansion, or an asymptotic expansion. Routines to calculate Airy functions and their derivatives are also included.
NASA Astrophysics Data System (ADS)
Chapman, Allan
2003-06-01
A careful study of the detailed archives of the Victorian Royal Observatory makes it possible to build up a picture of the employment and working conditions not only of the astronomical staff who worked at Greenwich, but also of the labourers, watchmen, and gate porters. Indeed, the archives open up a window on to how the Observatory was run on a daily basis: how its non-scientific staff were recruited and paid, and what were their terms of employment. They also say a great deal about how Sir George Biddell Airy directed and controlled every aspect of the Observatory's life. Yet while Airy was a strict employer, he emerges as a man who was undoubtedly fair-minded and sometimes even generous to his non-scientific work-force. A study of the Observatory staff files also reveals the relationship between the Observatory labouring staff and the Airy family's domestic servants. And of especial interest is the robbery committed by William Sayers, the Airy family footman in 1868, bringing to light as it does Sir George and Lady Richarda Airy's views on crime and its social causes and consequences, the prison rehabilitation service in 1868, and their opinions on the reform of offenders. Though this paper is not about astronomy as such, it illuminates a fascinating interface where the world of astronomical science met and worked alongside the world of ordinary Victorian people within the walls of one of the nineteenth century's most illustrious astronomical institutions.
Li, Yixiang; Qiu, Chunyin; Xu, Shengjun; Ke, Manzhu; Liu, Zhengyou
2015-08-17
Conventional microparticle transports by light or sound are realized along a straight line. Recently, this limit has been overcome in optics as the growing up of the self-accelerating Airy beams, which are featured by many peculiar properties, e.g., bending propagation, diffraction-free and self-healing. However, the bending angles of Airy beams are rather small since they are only paraxial solutions of the two-dimensional (2D) Helmholtz equation. Here we propose a novel micromanipulation by using acoustic Half-Bessel beams, which are strict solutions of the 2D Helmholtz equation. Compared with that achieved by Airy beams, the bending angle of the particle trajectory attained here is much steeper (exceeding 90(o)). The large-angle bending transport of microparticles, which is robust to complex scattering environment, enables a wide range of applications from the colloidal to biological sciences.
NASA Astrophysics Data System (ADS)
Li, Yixiang; Qiu, Chunyin; Xu, Shengjun; Ke, Manzhu; Liu, Zhengyou
2015-08-01
Conventional microparticle transports by light or sound are realized along a straight line. Recently, this limit has been overcome in optics as the growing up of the self-accelerating Airy beams, which are featured by many peculiar properties, e.g., bending propagation, diffraction-free and self-healing. However, the bending angles of Airy beams are rather small since they are only paraxial solutions of the two-dimensional (2D) Helmholtz equation. Here we propose a novel micromanipulation by using acoustic Half-Bessel beams, which are strict solutions of the 2D Helmholtz equation. Compared with that achieved by Airy beams, the bending angle of the particle trajectory attained here is much steeper (exceeding 90o). The large-angle bending transport of microparticles, which is robust to complex scattering environment, enables a wide range of applications from the colloidal to biological sciences.
Li, Yixiang; Qiu, Chunyin; Xu, Shengjun; Ke, Manzhu; Liu, Zhengyou
2015-01-01
Conventional microparticle transports by light or sound are realized along a straight line. Recently, this limit has been overcome in optics as the growing up of the self-accelerating Airy beams, which are featured by many peculiar properties, e.g., bending propagation, diffraction-free and self-healing. However, the bending angles of Airy beams are rather small since they are only paraxial solutions of the two-dimensional (2D) Helmholtz equation. Here we propose a novel micromanipulation by using acoustic Half-Bessel beams, which are strict solutions of the 2D Helmholtz equation. Compared with that achieved by Airy beams, the bending angle of the particle trajectory attained here is much steeper (exceeding 90o). The large-angle bending transport of microparticles, which is robust to complex scattering environment, enables a wide range of applications from the colloidal to biological sciences. PMID:26279478
Abnormal single or composite dissipative solitons generation
NASA Astrophysics Data System (ADS)
Zhong, Xianqiong; Liu, Dingyao; Cheng, Ke; Sheng, Jianan
2016-12-01
The evolution dynamics of the initial finite energy Airy pulses and Airy pulse pairs are numerically investigated in the cubic-quintic complex Ginzberg-Laudau equation governed dissipative system. Depending on different initial excitations and system parameters, abnormal double, triple, and quadruple composite dissipative solitons as well as single dissipative solitons can be observed. The composite dissipative solitons may consist of identical or different types of pulsating solitons. Moreover, the creeping solitons and the single ordinary pulsating solitons can even appear in the parameter regions where originally the other types of pulsating solitons exist. Besides, before evolving into each abnormal dissipative soliton, the initial finite energy Airy pulse or pulse pairs generally exhibit very interesting and unique early evolution behavior.
Richard Christopher Carrington: Briefly Among the Great Scientists of His Time
NASA Astrophysics Data System (ADS)
Cliver, Edward W.; Keer, Norman C.
2012-09-01
We recount the life and career of Richard Christopher Carrington (1826 - 1875) and explore his pivotal relationship with Astronomer Royal George Biddell Airy. Carrington was the pre-eminent solar astronomer of the 19th century. During a ten year span, he determined the position of the Sun's rotation axis and made the following discoveries: i) the latitude variation of sunspots over the solar cycle, ii) the Sun's differential rotation, and iii) the first solar flare (with Hodgson). Due to the combined effects of family responsibilities, failure to secure a funded position in astronomy (reflecting Airy's influence), and ill health, Carrington's productive period ended when he was at the peak of his powers.
Leidos Reclaims Defelice Cup at Annual Golf Tournament | Poster
By Ashley DeVine, Staff Writer Leidos Biomedical Research reclaimed the Defelice Cup trophy from NCI at the eighth annual Ronald H. Defelice golf tournament, held October 14. The final score was 15–7, with Leidos Biomed tying the series 4 to 4. Fourteen players on each team battled it out at Rattlewood golf course in Mount Airy, Md.
The Career Transition Cycle: Antecedents and Consequences of Career Events
1991-03-01
changes resulting from stress (e.g., serum uric acid and cholesterol levels). The longitudinal design of this study was also noteworthy. Measures of...in any way. It will beI - Piease do nc mame stra., maris Of airy kind us- eby the Navy Personnel Research and Development Center for INflORECT MARKS
FTIR-based airborne spectral imagery for target interrogation
NASA Astrophysics Data System (ADS)
Smithson, Tracy L.; St. Germain, Daniel; Nadeau, Denis
2007-09-01
DRDC Valcartier is continuing to developed infrared spectral imagery systems for a variety of military applications. Recently a hybrid airborne spectral imager / broadband imager system has been developed for ground target interrogation (AIRIS). This system employs a Fourier Transform Interferometer system coupled to two 8x8 element detector arrays to create spectral imagery in the region from 2.0 to 12 microns (830 to 5000 cm -1) at a spectral resolution of up to 1 cm -1. In addition, coupled to this sensor are three broadband imagers operating in the visible, mid-wave and long-wave infrared regions. AIRIS uses an on-board tracking capability to: dwell on a target, select multiple targets sequentially, or build a mosaic description of the environment around a specified target point. Currently AIRIS is being modified to include real-time spectral imagery calibration and application processing. In this paper the flexibility of the AIRIS system will be described, its concept of operation discussed and examples of measurements will be shown.
Integrable operators and the squares of Hankel operators
NASA Astrophysics Data System (ADS)
Blower, Gordon
2008-04-01
Integrable operators arise in random matrix theory, where they describe the asymptotic eigenvalue distribution of large self-adjoint random matrices from the generalized unitary ensembles. This paper gives sufficient conditions for an integrable operator to be the square of a Hankel operator, and applies the condition to the Airy, associated Laguerre, modified Bessel and Whittaker functions.
Comment on ''Solution of the Schroedinger equation for the time-dependent linear potential''
Bekkar, H.; Maamache, M.; Benamira, F.
2003-07-01
We present the correct way to obtain the general solution of the Schroedinger equation for a particle in a time-dependent linear potential following the approach used in the paper of Guedes [Phys. Rev. A 63, 034102 (2001)]. In addition, we show that, in this case, the solutions (wave packets) are described by the Airy functions.
Comment on ``Solution of the Schrödinger equation for the time-dependent linear potential''
NASA Astrophysics Data System (ADS)
Bekkar, H.; Benamira, F.; Maamache, M.
2003-07-01
We present the correct way to obtain the general solution of the Schrödinger equation for a particle in a time-dependent linear potential following the approach used in the paper of Guedes [Phys. Rev. A 63, 034102 (2001)]. In addition, we show that, in this case, the solutions (wave packets) are described by the Airy functions.
ERIC Educational Resources Information Center
Biemiller, Lawrence
2007-01-01
Charles Carroll Jr. would be long forgotten but for a single notable accomplishment: he built an exceedingly handsome house. Begun in 1801 with money from his wealthy father-- Charles Carroll of Carrollton, the only Roman Catholic signer of the Declaration of Independence-- the Federal-style home has near-perfect proportions and airy rooms. The…
Tracy-Widom at High Temperature
NASA Astrophysics Data System (ADS)
Allez, Romain; Dumaz, Laure
2014-09-01
We investigate the marginal distribution of the bottom eigenvalues of the stochastic Airy operator when the inverse temperature tends to . We prove that the minimal eigenvalue, whose fluctuations are governed by the Tracy-Widom law, converges weakly, when properly centered and scaled, to the Gumbel distribution. More generally we obtain the convergence in law of the marginal distribution of any eigenvalue with given index . Those convergences are obtained after a careful analysis of the explosion times process of the Riccati diffusion associated to the stochastic Airy operator. We show that the empirical measure of the explosion times converges weakly to a Poisson point process using estimates proved in Dumaz and Virág (Ann Inst H Poincaré Probab Statist 49(4):915-933, 2013). We further compute the empirical eigenvalue density of the stochastic Airy ensemble on the macroscopic scale when . As an application, we investigate the maximal eigenvalues statistics of -ensembles when the repulsion parameter when . We study the double scaling limit and argue with heuristic and numerical arguments that the statistics of the marginal distributions can be deduced following the ideas of Edelman and Sutton (J Stat Phys 127(6):1121-1165, 2007) and Ramírez et al. (J Am Math Soc 24:919-944, 2011) from our later study of the stochastic Airy operator.
Mars, the Meridian, and Mert: The Quest for Martian Longitude
NASA Astrophysics Data System (ADS)
Archinal, B. A.; Caplinger, M.
2002-12-01
From the mid 1960?s until his passing last year, Merton Davies of RAND was closely involved in establishing and maintaining the fundamental coordinate system for Mars. This included the establishment of the location of a modern 0-degree or Prime Meridian for Mars. In the early 1970's, images of the Martian surface became available via the Mariner 9 spacecraft. In 1973 G. de Vaucouleurs, Davies, and F. Sturms, Jr. proposed (JGR, 78, 4395) that a small easily identifiable crater in the area of Sinus Meridiani - the previously accepted origin - be used to define the Meridian. H. Masursky, de Vaucouleurs, and Davies selected an ~500 m diameter crater to serve this purpose. They proposed a name of Airy-0 for the crater in honor of Sir George Airy, who installed the transit instrument at the Greenwich Observatory, which for many years defined the Prime Meridian of the Earth. In a photogrammetric adjustment of Mariner 9 images Davies (Photo. Eng., 39, 1297; JGR, 78, 4355) held the longitude of Airy-0 fixed at 0-degrees, and thereby tied the entire Martian coordinate system to this crater. Davies and colleagues at RAND continued through 2001 in revising this coordinate system. All the while, these improved coordinate systems continued to be tied to Airy-0 and provided revised values for W0, the angle relating surface longitudes to inertial space coordinates. In 2001, the NASA Mars Geodesy and Cartography Working Group, chaired by T. Duxbury, and having as members many scientists (representing e.g. NASA, USGS, Malin SSS, DLR) interested in Martian coordinate system problems, assessed all available information on the location of Airy-0. This included solutions from Davies and Colvin and others, an evaluation of spacecraft lander locations, a Mars Global Surveyor Mars Orbiter Camera (MOC) image of Airy-0, and MOLA data in the vicinity of Airy-0. A value of W0 = 176.630 degrees was adopted for use, and this value has now in turn been adopted by the IAU (Seidelmann et al., Cel
The Martian Prime Meridian -- Longitude 'Zero'
NASA Technical Reports Server (NTRS)
2001-01-01
[figure removed for brevity, see original site]
On Earth, the longitude of the Royal Observatory in Greenwich, England is defined as the 'prime meridian,' or the zero point of longitude. Locations on Earth are measured in degrees east or west from this position. The prime meridian was defined by international agreement in 1884 as the position of the large 'transit circle,' a telescope in the Observatory's Meridian Building. The transit circle was built by Sir George Biddell Airy, the 7th Astronomer Royal, in 1850. (While visual observations with transits were the basis of navigation until the space age, it is interesting to note that the current definition of the prime meridian is in reference to orbiting satellites and Very Long Baseline Interferometry (VLBI) measurements of distant radio sources such as quasars. This 'International Reference Meridian' is now about 100 meters east of the Airy Transit at Greenwich.)
For Mars, the prime meridian was first defined by the German astronomers W. Beer and J. H. Madler in 1830-32. They used a small circular feature, which they designated 'a,' as a reference point to determine the rotation period of the planet. The Italian astronomer G. V. Schiaparelli, in his 1877 map of Mars, used this feature as the zero point of longitude. It was subsequently named Sinus Meridiani ('Middle Bay') by Camille Flammarion.
When Mariner 9 mapped the planet at about 1 kilometer (0.62 mile) resolution in 1972, an extensive 'control net' of locations was computed by Merton Davies of the RAND Corporation. Davies designated a 0.5-kilometer-wide crater (0.3 miles wide), subsequently named 'Airy-0' (within the large crater Airy in Sinus Meridiani) as the longitude zero point. (Airy, of course, was named to commemorate the builder of the Greenwich transit.) This crater was imaged once by Mariner 9 (the 3rd picture taken on its 533rd orbit, 533B03) and once by the Viking 1 orbiter in 1978 (the 46th image on that spacecraft's 746th orbit
Plasma deposition of antimicrobial coating on organic polymer
NASA Astrophysics Data System (ADS)
Rżanek-Boroch, Zenobia; Dziadczyk, Paulina; Czajkowska, Danuta; Krawczyk, Krzysztof; Fabianowski, Wojciech
2013-02-01
Organic materials used for packing food products prevent the access of microorganisms or gases, like oxygen or water vapor. To prolong the stability of products, preservatives such as sulfur dioxide, sulfites, benzoates, nitrites and many other chemical compounds are used. To eliminate or limit the amount of preservatives added to food, so-called active packaging is sought for, which would limit the development of microorganisms. Such packaging can be achieved, among others, by plasma modification of a material to deposit on its surface substances inhibiting the growth of bacteria. In this work plasma modification was carried out in barrier discharge under atmospheric pressure. Sulfur dioxide or/and sodium oxide were used as the coating precursors. As a result of bacteriological studies it was found that sulfur containing coatings show a 16% inhibition of Salmonella bacteria growth and 8% inhibition of Staphylococcus aureus bacteria growth. Sodium containing coatings show worse (by 10%) inhibiting properties. Moreover, films with plasma deposited coatings show good sealing properties against water vapor. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.
NASA Astrophysics Data System (ADS)
Koval'ová, Zuzana; Tarabová, Kataŕna; Hensel, Karol; Machala, Zdenko
2013-02-01
Cold air plasmas of DC and pulsed corona discharges: positive streamers and negative Trichel pulses were used for bio-decontamination of Streptococci biofilm and Bacillus cereus spores on polypropylene plastic surfaces. The reduction of bacterial population (evaluated as log10) in the biofilm on plastic surfaces treated by DC corona reached 2.4 logs with 10 min treatment time and 3.3 logs with 2 min treatment time with water spraying. The enhancement of plasma biocidal effects on the biofilm by electro-spraying of water through a hollow needle high-voltage electrode was investigated. No significant polarity effect was found with DC corona. Pulsed corona was demonstrated slightly more bactericidal for spores, especially in the negative polarity where the bacterial population reduction reached up to 2.2 logs at 10 min exposure time. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.
Free fatty acids degradation in grease trap purification using ozone bubbling and sonication
NASA Astrophysics Data System (ADS)
Piotr Kwiatkowski, Michal; Satoh, Saburoh; Fukuda, Shogo; Yamabe, Chobei; Ihara, Satoshi; Nieda, Masanori
2013-02-01
The oil and fat were treated at first by only ozone bubbling and it was confirmed that the collection efficiency of them became 98.4% when the aeration was used. It showed that the aeration method in a grease trap cleared the standard value of 90% and there was no worry on the oil and fat outflow from a grease trap. The characteristics of sonication process were studied for free fatty acids degradation. The free saturated fatty acids are the most hard-degradable compounds of the fats, oils and greases (FOGs) in the grease trap. The influence of various parameters such as immersion level of an ultrasound probe in the liquid and bubbling of various gases (Ar, O2, air, O3) on the sonochemical and energy efficiency of the sonication process was investigated. The most effective degradation treatment method for saturated free fatty acids was the combination of sonication and low flow rate argon bubbling. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.
Ozone-mist spray sterilization for pest control in agricultural management
NASA Astrophysics Data System (ADS)
Ebihara, Kenji; Mitsugi, Fumiaki; Ikegami, Tomoaki; Nakamura, Norihito; Hashimoto, Yukio; Yamashita, Yoshitaka; Baba, Seiji; Stryczewska, Henryka D.; Pawlat, Joanna; Teii, Shinriki; Sung, Ta-Lun
2013-02-01
We developed a portable ozone-mist sterilization system to exterminate pests (harmful insects) in agricultural field and greenhouse. The system is composed of an ozone generator, an ozone-mist spray and a small container of ozone gas. The ozone generator can supply highly concentrated ozone using the surface dielectric barrier discharge. Ozone-mist is produced using a developed nozzle system. We studied the effects of ozone-mist spray sterilization on insects and agricultural plants. The sterilization conditions are estimated by monitoring the behavior of aphids and observing the damage of the plants. It was shown that aphids were exterminated in 30 s without noticeable damages of the plant leaves. The reactive radicals with strong oxidation potential such as hydroxyl radical (*OH), hydroperoxide radical (*HO2), the superoxide ion radical (*O2‒) and ozonide radical ion (*O3‒) can increase the sterilization rate for aphids. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.
Dakhil, Hala A; Hammad, Efat Abou-Fakhr; El-Mohtar, Choaa; Abou-Jawdah, Yusuf
2011-01-01
Leafhoppers (Hemiptera: Auchenorrhyncha: Cicadellidae) account for more than 80% of all "Auchenorrhynchous" vectors that transmit phytoplasmas. The leafhopper populations in two almond witches'-broom phytoplasma (AlmWB) infected sites: Tanboureet (south of Lebanon) and Bourj El Yahoudieh (north of Lebanon) were surveyed using yellow sticky traps. The survey revealed that the most abundant species was Asymmetrasca decedens, which represented 82.4% of all the leafhoppers sampled. Potential phytoplasma vectors in members of the subfamilies Aphrodinae, Deltocephalinae, and Megophthalminae were present in very low numbers including: Aphrodes makarovi, Cicadulina bipunctella, Euscelidius mundus, Fieberiella macchiae, Allygus theryi, Circulifer haematoceps, Neoaliturus transversalis, and Megophthalmus scabripennis. Allygus theryi (Horváth) (Deltocephalinae) was reported for the first time in Lebanon. Nested PCR analysis and sequencing showed that Asymmetrasca decedens, Empoasca decipiens, Fieberiella macchiae, Euscelidius mundus, Thamnottetix seclusis, Balclutha sp., Lylatina inexpectata, Allygus sp., and Annoplotettix danutae were nine potential carriers of AlmWB phytoplasma. Although the detection of phytoplasmas in an insect does not prove a definite vector relationship, the technique is useful in narrowing the search for potential vectors. The importance of this information for management of AlmWB is discussed.
Fourth Bionanotox and Applications Research Conference, 2009
NASA Astrophysics Data System (ADS)
Camp, Judy
2010-04-01
"Anticipating the future" seemed the common challenge for scientists attending the 4th BioNanoTox and Applications Research Conference in Little Rock, AR, October 21-22, 2009. Over 50 participants in multi-disciplines such as biology, chemistry, physics, medicine, medical diagnostics, computer science and informatics, nanotechnology, toxicology, and pharmaceutical science gathered to share their research data. From topics on water and food resources to space exploration to conservation to understanding biological activities and using instruments and computers that process enormous data, participants shared research approaches from different fields to find common themes in this integrated field. Presentations aimed at preventing the harmful effects of scientific discoveries to animals, humans, plants, and environment; at controlling infections; and at optimizing health care. The conference included addresses from Thomas Flammang, PhD, of the Food and Drug Administration, National Center for Toxicological Research in Jefferson, AR; Little Rock City Mayor Mark Stodola; and two keynote speakers. Keynote lectures by Danuta Leszczynska, PhD, from the Department of Civil and Environmental Engineering, Interdisciplinary Nanotoxicity Center, in Jackson, MS, and by Keith Cowan, PhD, from the Institute for Environmental Biotechnology in Grahamstown, South Africa, highlighted current trends and future challenges of nanoparticle research and of bioprocess technologies. Additionally, 25 graduate and undergraduate students presented research posters, resulting in valuable discussion among the varied participants; three student projects were selected for awards.
NASA Astrophysics Data System (ADS)
Nakamiya, Toshiyuki; Mitsugi, Fumiaki; Iwasaki, Yoichiro; Ikegami, Tomoaki; Tsuda, Ryoichi; Sonoda, Yoshito; Danuta Stryczewska, Henryka
2013-02-01
The phase modulation of transparent gas can be detected using Fraunhofer diffraction technique, which we call optical wave microphone (OWM). The OWM is suitable for the detection of sonic wave from audible sound to ultrasonic wave. Because this technique has no influence on sound field or electric field during the measurement, we have applied it to the sound detection for the electric discharges. There is almost no research paper that uses the discharge sound to examine the electrical discharge phenomenon. Two-dimensional visualization of the sound field using the OWM is also possible when the computerized tomography (CT) is combined. In this work, coplanar dielectric barrier discharge sin different gases of Ar, N2, He were characterized via the OWM as well as applied voltage and discharge current. This is the first report to investigate the influence of the type of the atmospheric gas on the two-dimensional sound field distribution for the coplanar dielectric barrier discharge using the OWM with CT. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.
Atmospheric pressure low-power microwave microplasma source for deactivation of microorganisms
NASA Astrophysics Data System (ADS)
Mizeraczyk, Jerzy; Dors, Mirosław; Jasiński, Mariusz; Hrycak, Bartosz; Czylkowski, Dariusz
2013-02-01
This work was aimed at experimental investigations of deactivation of different types of microorganisms by using atmospheric pressure low-temperature microwave microplasma source (MmPS). The MmPS was operated at standard microwave frequency of 2.45 GHz. Its main advantages are simple and cheap construction, portability and possibility of penetrating into small cavities. The microplasma deactivation concerned two types of bacteria (Escherichia coli, Bacillus subtilis) and one fungus (Aspergillus niger). The quality as well as quantity tests were performed. The influence of the microorganism type, oxygen concentration, absorbed microwave power, microplasma treatment time and MmPS distance from the treated sample on the microorganism deactivation efficiency was investigated. All experiments were performed for Ar microplasma and Ar/O2 microplasma with up to 3% of O2. Absorbed microwave power was up to 50 W. The Ar flow rate was up to 10 L/min. The sample treatment time was up to 10 s. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.
Generation of high pressure homogeneous dielectric barrier discharge in air
NASA Astrophysics Data System (ADS)
Osawa, Naoki; Takashi, Ami; Yoshioka, Yoshio; Hanaoka, Ryoichi
2013-02-01
We succeeded in generating an atmospheric pressure Townsend discharge (APTD) in air by using a simple DBD device that consists of alumina barriers and plane electrodes. So far, we applied the APTD to an ozonizer and found that the ozone generation efficiency was higher by the APTD mode than by the conventional DBD mode in larger specific input energy region. It is well known that an operation under an optimized high gas pressure is advantageous for efficient ozone generation from air. In this paper, we investigated whether the Townsend discharge (TD) in dry air in high pressure up to 0.17 MPa can be generated or not. From the observation results of current waveforms and discharge photographs, we found that (1) the discharge currents flow continuously and have only one peak in every half cycle in all gas pressure and (2) filamentary discharges are not recognized between barriers in all gas pressure. These features completely agree with the features of the APTD we reported. Therefore, we concluded that our TD can be generated even in dry air in the pressure range of 0.1 and 0.17 MPa. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.
On numerical solutions to the QCD ’t Hooft equation in the limit of large quark mass
Zubov, Roman; Prokhvatilov, Evgeni
2016-01-22
First we give a short informal introduction to the theory behind the ’t Hooft equation. Then we consider numerical solutions to this equation in the limit of large fermion masses. It turns out that the spectrum of eigenvalues coincides with that of the Airy differential equation. Moreover when we take the Fourier transform of eigenfunctions, they look like the corresponding Airy functions with appropriate symmetry. It is known that these functions correspond to solutions of a one dimensional Schrodinger equation for a particle in a triangular potential well. So we find the analogy between this problem and the ’t Hooft equation. We also present a simple intuition behind these results.
Self-reconstruction of diffraction-free and accelerating laser beams in scattering media
NASA Astrophysics Data System (ADS)
Ersoy, T.; Yalizay, B.; Akturk, S.
2012-12-01
We experimentally investigate propagation of laser beams with different intensity profiles in highly scattering media. We generate transverse laser amplitude profiles with Gaussian, Bessel and Airy function envelopes. We then propagate these beams through optical phantoms formed with variable density intralipid solutions. At the sample exit, we compare change in maximum intensities, as well as beam profile reconstruction. We show that self-reconstruction properties of Bessel and Airy beams bring about slower decrease in maximum intensity with increasing scatterer density. On the other hand, the beam profiles deteriorate faster, as compared to reference Gaussian beams. Slower decrease in the intensity can be attributed to the wavevector spectra providing a continuous flow of energy to the beam center, while beam deterioration is linked to total beam volume in the scattering medium. These results show that beam shaping methods can significantly enhance delivery of intense light deeper into turbid media, but this enhancement is compromised by stronger speckling of beam profiles.
Accelerating Airy–Gauss–Kummer localized wave packets
Zhong, Wei-Ping; Belić, Milivoj; Zhang, Yiqi; Huang, Tingwen
2014-01-15
A general approach to generating three-dimensional nondiffracting spatiotemporal solutions of the linear Schrödinger equation with an Airy-beam time-dependence is reported. A class of accelerating optical pulses with the structure of Airy–Gauss–Kummer vortex beams is obtained. Our results demonstrate that the optical field contributions to the Airy–Gauss–Kummer accelerating optical wave packets of the cylindrical symmetry can be characterized by the radial and angular mode numbers. -- Highlights: •A general solution of 3D linear Schrödinger equation with an Airy time-dependence is reported. •We find that the Airy–Kummer spatiotemporal wave packets can carry infinite energy. •A class of the accelerating spatiotemporal optical pulses with special structures was found. •The spatiotemporal wave packets retain their energy features over several Rayleigh lengths.
Automatic Fourier transform and self-Fourier beams due to parabolic potential
Zhang, Yiqi; Liu, Xing; Belić, Milivoj R.; Zhong, Weiping; Petrović, Milan S.; Zhang, Yanpeng
2015-12-15
We investigate the propagation of light beams including Hermite–Gauss, Bessel–Gauss and finite energy Airy beams in a linear medium with parabolic potential. Expectedly, the beams undergo oscillation during propagation, but quite unexpectedly they also perform automatic Fourier transform, that is, periodic change from the beam to its Fourier transform and back. In addition to oscillation, the finite-energy Airy beams exhibit periodic inversion during propagation. The oscillating period of parity-asymmetric beams is twice that of the parity-symmetric beams. Based on the propagation in parabolic potential, we introduce a class of optically-interesting beams that are self-Fourier beams—that is, the beams whose Fourier transforms are the beams themselves.
NASA Astrophysics Data System (ADS)
Goyal, Amit; Raju, Thokala Soloman; Kumar, C. N.; Panigrahi, Prasanta K.
2016-04-01
We analytically explore optical rogue waves in a nonlinear graded-index waveguide, with spatially modulated dispersion, nonlinearity, and linear refractive-index. We study the evolution of first-order rogue wave and rogue wave triplet on Airy-Bessel, sech2, and tanh background beams, and reveal that the characteristics of RWs are well maintained while the amplitude of the first-order RW gets enhanced three times the maximum value of the Airy-Bessel and sech2 background beams and five times in the case of RW triplet. These results could be of great interest in realizing the RWs in experimentally realizable situations on small-amplitude background beams in nonlinear optics.
Test and Evaluation of a Pilot Two-Stage Precipitator for Jet Engine Test Cell Exhaust Gas Cleaning
1976-04-01
then available for emission control . A two- stage electrostatic precipitator was recommended as .j he most viable alternative to a concept then being...TEST AND EVALUATION OF A "PILOT TWO* STAGE PRECIPITATOR FOR JET ENGINE TEST CELL 0 EXHAUST GA, S CLEANING C44 NAVAL AIR REWORK FACILITY NAVAL AIR...is the release you requested in your telephone conversation of 20 July 1976 with the undersigned. Yourn very tru~ly, Head Specifications Branch a 21
Superresolved Imaging Using the Hartley Transform and a Hemispherical Object Space
1988-12-01
in the far field is a Bessel function - the intensity being later called an Airy pattern (6:419). In 1896, Lord John William Strutt Rayleigh ...April 1968). 13. Walker John G. "Optical Imaging with Resolution Exceeding the Rayleigh Criterion," Optica ACTA, 30: 1197-1202 (1983). 14. Joyce...for challenging my work; Bruce Hornsby, Pink Floyd and Rush for inspiration; and John T. Kelly, my father, for always asking me "Why?". Aoesifoln d/or
Alpha particle condensation in {sup 12}C and nuclear rainbow scattering
Ohkubo, S.; Hirabayashi, Y.
2008-05-12
It is shown that the large radius of the Hoyle state of {sup 12}C with a dilute density distribution in an {alpha} particle condensate can be clearly seen in the shift of the rainbow angle (therefore the Airy minimum) to a larger angle in {alpha}+{sup 12}C rainbow scattering at the high energy region and prerainbow oscillations in {sup 3}He+{sup 12}C scattering at the lower energy region.
2012-03-07
Radiation Patterns Predicted and measured Beam Steering integration to Shadow Harvest Sensor Pod Lockheed Martin and OSU 29 DISTRIBUTION A...spatial filtering system, with an appropriate phase mask, can produce an Airy beam 18 DISTRIBUTION A: Approved for public release; distribution is...ES) arrays attain 7 dB realizable gain, 5 dB higher than any previous ES antenna . • Can be used to replace much larger Yagi antennas . • Paves
NASA Astrophysics Data System (ADS)
Luther, P.
In this bibliography a concise biographical chronology of the following astronomers is given: George Biddell Airy (1801 - 1892), Robert Stawell Ball (1840 - 1913), George Phillips Bond (1825 - 1865), William Cranch Bond (1789 - 1859), Agnes Mary Clerke (1842 - 1907), John Frederick William Herschel (1792 - 1871), Edward Singleton Holden (1846 - 1914), Joseph Norman Lockyer (1836 - 1920), Percival Lowell (1855 - 1916), Ormsby MacKnight Mitchel (1809 - 1862), Simon Newcomb (1835 - 1909), Richard Anthony Proctor (1837 - 1888), Mary Fairfax Greig Somerville (1780 - 1872).
Precise evaluation of the Helmholtz equation for optical propagation.
Pond, John E; Sutton, George W
2015-01-01
A precise computational integration of the Helmholtz equation was performed for laser propagation of an electromagnetic wave with no approximations or linearization. This computation integration was performed using 64-bit processors. This is illustrated for a uniform monochromatic beam from a circular aperture that has a uniform intensity. It predicts many Arago spots and near-field intensity fluctuations for a large ratio of aperture size to wavelength and converges to the usual Airy pattern in the far field.
NASA Astrophysics Data System (ADS)
Krisch, J. P.; Glass, E. N.
2014-10-01
A set of cylindrical solutions to Einstein's field equations for power law densities is described. The solutions have a Bessel function contribution to the metric. For matter cylinders regular on axis, the first two solutions are the constant density Gott-Hiscock string and a cylinder with a metric Airy function. All members of this family have the Vilenkin limit to their mass per length. Some examples of Bessel shells and Bessel motion are given.
Earth's isostatic gravity anomaly field: Contributions to National Geodetic Satellite Program
NASA Technical Reports Server (NTRS)
Khan, M. A.
1973-01-01
On the assumption that the compensation for the topographic load is achieved in the manner of Airy-Heiskenenan hypothesis at a compensation depth of 30 kilometers, the spherical harmonic coefficients of the isostatic reduction potential U are computed. The degree power spectra of these coefficients are compared with the power spectra of the isostatic reduction coefficients given by Uotila. Results are presented in tabular form.
Application of boundary integral method to elastic analysis of V-notched beams
NASA Technical Reports Server (NTRS)
Rzasnicki, W.; Mendelson, A.; Albers, L. U.
1973-01-01
A semidirect boundary integral method, using Airy's stress function and its derivatives in Green's boundary integral formula, is used to obtain an accurate numerical solution for elastic stress and strain fields in V-notched beams in pure bending. The proper choice of nodal spacing on the boundary is shown to be necessary to achieve an accurate stress field in the vicinity of the tip of the notch. Excellent agreement is obtained with the results of the collocation method of solution.
NASA Astrophysics Data System (ADS)
Krisch, J. P.; Glass, E. N.
2014-11-01
A set of cylindrical solutions to Einstein's field equations for power law densities is described. The solutions have a Bessel function contribution to the metric. For matter cylinders regular on axis, the first two solutions are the constant density Gott-Hiscock string and a cylinder with a metric Airy function. All members of this family have the Vilenkin limit to their mass per length. Some examples of Bessel shells and Bessel motion are given.
The Budget and Economic Outlook: 2015 to 2025
2015-01-01
analysts in other divisions; that work was supervised by Peter Fontaine, Theresa Gullo, Holly Harvey, Janet Airis, Tom Bradley , Kim Cawley, Chad Chirico...justice, science and space exploration, recreational resources Megan Carroll Energy, air transportationCBO 176 THE BUDGET AND ECONOMIC OUTLOOK: 2015 TO...2. Christina Hawley Anthony, Megan Carroll , Avi Lerner, and Amber Marcellino wrote Chapter 3. Mark Booth, Pamela Greene, Joshua Shakin, and David
What Brown saw and you can too
NASA Astrophysics Data System (ADS)
Pearle, Philip; Collett, Brian; Bart, Kenneth; Bilderback, David; Newman, Dara; Samuels, Scott
2010-12-01
A discussion of Robert Brown's original observations of particles ejected by pollen of the plant Clarkia pulchella undergoing what is now called Brownian motion is given. We consider the nature of those particles and how he misinterpreted the Airy disk of the smallest particles to be universal organic building blocks. Relevant qualitative and quantitative investigations with a modern microscope and with a "homemade" single lens microscope similar to Brown's are presented.
Solitons and the Inverse Scattering Transform
1980-01-01
the Airy equation ; it arises in certain problems in optics. Part (b) is the time - dependent Schr6dinger equation , with no potential. Part (c) is the...of these special nonlinear evolution equations are quite predictable, and can be computed explicitly (especially for large times ) once the initial data...ifferertial equations , even before time - dependence is brought into the picture! Fortunately, another miracle occurs, and there is a change of variables
Terahertz beam shaping with metasurface
NASA Astrophysics Data System (ADS)
He, Jingwen; Wang, Sen; Zhang, Yan
2016-11-01
Based on metasurface, two beam shapers are designed to modulate the wavefront of the terahertz beam. One of the beam shapers is THz ring-Airy beam generator and the other is THz four-focus lens. Each beam shaper is composed of a serious of C-shaped slot antennas, which can be used to modulate the phase and amplitude of the cross-polarized scattered wave. A THz holographic imaging system is utilized to measure the field of the generated beams. The ring- Airy beam shaper is designed by replacing both the phase and amplitude of its initial electric field with the corresponding antennas. In the experiment, an abrupt focus following a parabolic trajectory is subsequently observed. This method can be expanded to other wavebands, such as the visible band, in which the ring-Airy beam shaper can replace traditional computer-generated holography to avoid undesirable multiple diffraction orders. The phase distribution of the four-focus lens is obtained by using the Yang-Gu amplitude-phase retrieval algorithm and then encoded to the antennas. Both the focusing and imaging properties are demonstrated. A clear image can be obtained with a bandwidth of 110 GHz. This type of transmissive metasurface beam shaper serves as an attractive alternative to conventional diffractive optical elements based on its small size, ease of fabrication, and low cost.
Interface fluctuations for deposition on enlarging flat substrates
NASA Astrophysics Data System (ADS)
Carrasco, I. S. S.; Takeuchi, K. A.; Ferreira, S. C.; Oliveira, T. J.
2014-12-01
We investigate solid-on-solid models that belong to the Kardar-Parisi-Zhang (KPZ) universality class on substrates that expand laterally at a constant rate by duplication of columns. Despite the null global curvature, we show that all investigated models have asymptotic height distributions and spatial covariances in agreement with those expected for the KPZ subclass for curved surfaces. In 1 + 1 dimensions, the height distribution and covariance are given by the GUE Tracy-Widom distribution and the Airy2 process instead of the GOE and Airy1 foreseen for flat interfaces. These results imply that when the KPZ class splits into curved and flat subclasses, as conventionally considered, the expanding substrate may play a role equivalent to, or perhaps more important than, the global curvature. Moreover, the translational invariance of the interfaces evolving on growing domains allowed us to accurately determine, in 2 + 1 dimensions, the analog of the GUE Tracy-Widom distribution for height distribution and that of the Airy2 process for spatial covariance. Temporal covariance is also calculated and shown to be universal in each dimension and in each of the two subclasses. A logarithmic correction associated with the duplication of columns is observed and theoretically elucidated. Finally, crossover between regimes with fixed-size and enlarging substrates is also investigated.
Isostatic compensation of equatorial highlands on Venus
NASA Technical Reports Server (NTRS)
Kucinskas, Algis B.; Turcotte, Donald L.
1994-01-01
Spherical harmonic models for Venus' global topography and gravity incorporating Magellan data are used to test isostatic compensation models in five 30 deg x 30 deg regions representative of the main classes of equatorial highlands. The power spectral density for the harmonic models obeys a power-law scaling with spectral slope Beta approximately 2 (Brown noise) for the topography and Beta approximately 3 (Kaula's law) for the geoid, similar to what is observed for Earth. The Venus topography spectrum has lower amplitudes than Earth's which reflects the dominant lowland topography on Venus. Observed degree geoid to topography ratios (GTRs) on Venus are significantly smaller than degree GTRs for uncompensated topography, indicative of substantial compensation. Assuming a global Airy compensation, most of the topography is compensated at depths greater than 100 km, suggesting a thick lithosphere on Venus. For each region considered we obtain a regional degree of compensation C from a linear regression of Bouguer anomaly versus Bouguer gravity data. Geoid anomaly (N) versus topography variation (h) data for each sample were compared, in the least-squares sense, to theoretical correlations for Pratt, Airy, and thermal thinning isostasy models yielding regional GTR, zero-elevation crustal thickness (H), and zero elevation thermal lithosphere thickness (y(sub L(sub 0)), respectively. We find the regional compensation to be substantial (C approximately 52-80%), and the h, N data correlations in the chosen areas can be explained by isostasy models applicable on the Earth and involving variations in crustal thickness (Airy) and/or lithospheric (thermal thinning) thickness. However, a thick crust and lithosphere (y(sub L(sub 0)) approximately 300 km) must be assumed for Venus.
NCI Holds on to Defelice Cup | Poster
NCI kept the Defelice Cup trophy this year after beating Leidos Biomedical Research, 15 to 9, at the 10th annual Ronald H. Defelice Golf Tournament held on Columbus Day. Sixteen players on each team battled it out at the yearly contractor vs. government tournament held at Rattlewood Golf Course in Mount Airy, Md. NCI leads the series 6–4. “The score was the highest NCI margin of victory in the 10-year series,” said Denny Dougherty, retired senior subcontracts advisor at what was formerly SAIC-Frederick. “The intensity of the annual competition has increased each year and has become...
Prediction of noise field of a propfan at angle of attack
NASA Technical Reports Server (NTRS)
Envia, Edmane
1991-01-01
A method for predicting the noise field of a propfan operating at an angle of attack to the oncoming flow is presented. The method takes advantage of the high-blade-count of the advanced propeller designs to provide an accurate and efficient formula for predicting their noise field. The formula, which is written in terms of the Airy function and its derivative, provides a very attractive alternative to the use of numerical integration. A preliminary comparison shows rather favorable agreement between the predictions from the present method and the experimental data.
A New Way to Demonstrate the Rainbow
NASA Astrophysics Data System (ADS)
Ivanov, Dragia Trifonov; Nikolov, Stefan Nikolaev
2016-11-01
The rainbow is a beautiful optical phenomenon that has fascinated humankind since antiquity. It is caused by a huge number of water droplets in the atmosphere illuminated by the Sun. Many noted physicists have contributed to the explanation of the rainbow. The wave theory of the rainbow was developed by George Airy, and modern descriptions are based on Mie scattering as developed by Gustav Mie. For educational purposes the simpler theory by Descartes, which is based solely on geometrical optics and is much more accessible, is used.
NASA Astrophysics Data System (ADS)
Bendahma, F.; Djelti, R.; Bentata, S.
2016-08-01
The aperiodic GaAs/AlxGa1-xAs superlattices (SL) with trimer disorder have been studied in this paper. The transfer-matrix technique and the exact Airy function formalism have been used to determine the miniband structure, the transmission coefficient, the resonance energy and resonant tunneling time (RTT). Although the disorder localizes the states on average, our numerical calculations show that the localization length of the states becomes more extended when the disorder is correlated (trimer case). We have also found that the RTT is of the order of several femtoseconds.
Hybrid pupil filter design using Bessel series
NASA Astrophysics Data System (ADS)
Ochoa, Noé Alcalá; García-Márquez, J.; González-Vega, A.
2011-09-01
We propose a simple method of designing pupil filters for transverse super-resolution. For this end we represent the amplitude Point Spread Function (PSF) as a series expansion, constructed from the Fourier transform of a basis of Bessel functions. With this representation we optimize the intensity PSF according to certain desired characteristics, such as a smaller disk diameter than the corresponding, clear aperture, Airy disk. It is proved that by using few basis functions, it is possible to design pupils with similar or better PSF characteristics than previously reported.
Spin-polarized transport through ZnMnSe/ZnSe/ZnBeSe heterostructures
NASA Astrophysics Data System (ADS)
Ming, Y.; Gong, J.; Zhang, R. Q.
2011-11-01
Using the transfer matrix method and Airy function, the spin-dependent tunneling through the ZnMnSe/ZnSe/ZnBeSe structure was investigated theoretically. The electron tunneling determined by the applied bias, external magnetic field, and spin orientations exhibited some interesting and complex features. It was found that the magnetic field could suppress the spin-up current, but enhance the spin-down current. Furthermore the spin-flip of current could be realized by changing the applied bias slightly. Therefore, it can be believed that our structure could behave as a good spin-filter.
Improved coordinates of features in the vicinity of the Viking lander site on Mars
NASA Astrophysics Data System (ADS)
Davies, M. E.; Dole, S. H.
1980-03-01
The measurement of longitude of the Viking 1 landing site and the accuracy of the coordinates of features in the area around the landing site are discussed. The longitude must be measured photogrammatically from the small crater, Airy 0, which defines the 0 deg meridian on Mars. The computer program, GIANT, which was used to perform the analytical triangulations, and the photogrammetric computation of the longitude of the Viking 1 lander site are described. Improved coordinates of features in the vicinity of the Viking 1 lander site are presented.
Rejoice in the hubris: useful things biologists could do for physicists.
Austin, Robert H
2014-10-08
Political correctness urges us to state how wonderful it is to work with biologists and how, just as the lion will someday lie down with the lamb, so will interdisciplinary work, where biologists and physicists are mixed together in light, airy buildings designed to force socialization, give rise to wonderful new science. But it has been said that the only drive in human nature stronger than the sex drive is the drive to censor and suppress, and so I claim that it is OK for physicists and biologists to maintain a wary distance from each other, so that neither one censors or suppresses the wild ideas of the other.
Model calculations of spectral transmission for the CLAES etalons
NASA Technical Reports Server (NTRS)
James, T. C.; Roche, A. E.; Kumer, J. B.
1989-01-01
This paper describes models for calculating spectral transmission for the Cryogenic-Limb-Array-Etalon-Spectrometer (CLAES) etalons. These models involve a convolution of the Airy function for a given thickness with the distribution of surface thicknesses, the effect of absorption in the substrate, and the field of view broadening as a function of etalon tilt angle. A comparison of model calculations with experimental transmission data for CLAES etalons centered at 3.52, 5.72, 8.0, and 11.86 microns showed that these models are able to provide a good description of the CLAES etalons.
Design, Construction, Testing and Evaluation of a Residential Ice Storage Air Conditioning System.
1982-11-01
FuseI.Size: 40 Amps Shipping Weight: 550 lbs. 19 Aok *l 4. - ’j-A .~ % --4. L 94 Table 9 Model PA�C Compressor 3 P Semi Hermetic Condensor Air... hermetic compressor , airI cooled condenser, drier, 2 evaporators, and thermostatic expansion valve refrigerant feed with a low side accumulator with...50% V •water. The tank provided storage for 12,730 pounds of ice. The system used a 25 ton compressor (rated 0 40"F suction) which would freeze the
Approximate Symmetry Reduction Approach: Infinite Series Reductions to the KdV-Burgers Equation
NASA Astrophysics Data System (ADS)
Jiao, Xiaoyu; Yao, Ruoxia; Zhang, Shunli; Lou, Sen Y.
2009-11-01
For weak dispersion and weak dissipation cases, the (1+1)-dimensional KdV-Burgers equation is investigated in terms of approximate symmetry reduction approach. The formal coherence of similarity reduction solutions and similarity reduction equations of different orders enables series reduction solutions. For the weak dissipation case, zero-order similarity solutions satisfy the Painlevé II, Painlevé I, and Jacobi elliptic function equations. For the weak dispersion case, zero-order similarity solutions are in the form of Kummer, Airy, and hyperbolic tangent functions. Higher-order similarity solutions can be obtained by solving linear variable coefficients ordinary differential equations.
Report of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements: 2006
2007-01-01
Additional decimal places are given in the expressions for Mercury, the Moon, Mars, Saturn, and Uranus , reflecting the greater confidence in their accuracy...Saturn α0 = 40.589− 0.036T δ0 = 83.537− 0.004T W = 38.90+ 810.7939024d (e) Uranus α0 = 257.311 δ0 = −15.175 W = 203.81− 501.1600928d (e) Neptune α0...crater Airy-0 (e) The equations forW for Jupiter, Saturn, Uranus andNeptune refer to the rotation of theirmagnetic fields (System III). On Jupiter, System
Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2009
2011-01-01
Saturn, and Uranus , reflecting the greater confidence in their accuracy. Expres- sions for the Sun and Earth are given to a similar precision as...0.004T W = 38.90 + 810.7939024d (e) Uranus α0 = 257.311 δ0 = −15.175 W = 203.81 − 501.1600928d (e) Neptune α0 = 299.36 + 0.70 sin N δ0 = 43.46 − 0.51 cos...defined by the central peak in the crater Ariadne (d) The 0◦ meridian is defined by the crater Airy-0 (e) The equations for W for Jupiter, Saturn, Uranus
Detection of stress concentrations around a defect by magnetic Barkhausen noise measurements
Mandal, K.; Dufour, D.; Sabet-Sharghi, R.; Sijgers, B.; Micke, D.; Krause, T.W.; Clapham, L.; Atherton, D.L.
1996-12-01
The stress distribution around a 50{percent} blind-hole pit in a steel pipe with a 9 mm wall has been studied using high-resolution magnetic Barkhausen noise (MBN) measurements. A magnetic disk read-head is used as the pick up coil in the MBN probe. The study shows a stress concentration factor of {approximately}2 at the defect edge perpendicular to the direction of applied stress and {approximately}{minus}0.6 at the edge parallel to the same. The experimental results are consistent with the analytical solutions obtained by the Airy{close_quote}s stress function approach. {copyright} {ital 1996 American Institute of Physics.}
Development of Nanomechanical Sensors for Breast Cancer Biomarkers
2005-06-01
Fretnlliotenl•lry Vacuntim 0 () 0 2.18 MHz Airi 7.$ juk.W/mr 26.2 IiN 2.29 nr -,0.9 MNITZ Wat-r (Mood) I rnikels 78.5 p*i 6&W8 nrm +-63 kMYz Glycc°ol 1.5 kg!fm...the nanowire surface is done by the application of a 2% APTES solution of methanol for 3 hours. After multiple rinsing of the device by methanol , the
Aircraft Structural Design Handbook for Lower Cost Maintenance and Repair
1977-03-01
treatment, and product Precipitation hardening 17-4PH 15 - 5PH High High form AM355 High AM330 High - ^- -- ■ - ■ i i - 6-52...Naval™ fS ^^SJ3"^- 15 ^^ t0 th0Se ^^ ^" a* who pxovlw Se s^p^taJ ass^srt^(. C’MPanieS’ ^ airi;raft «"ftcturers vaiuabie lnfor«tloTpSd ^ St^diS...Corrosion Protection Deficiencies Material Selection Deficiencies Detail Design Deficiencies Fatigue Design Deficiencies 5.0 GENERAL DESIGN
The Greenland gravitational constant experiment.
NASA Astrophysics Data System (ADS)
Zumberge, M. A.; Ander, M. E.; Lautzenhiser, T. V.; Parker, R. L.; Aiken, C. L. V.; Gorman, M. R.; Nieto, M. M.; Cooper, A. P. R.; Ferguson, J. F.; Fisher, E.; Greer, J.; Hammer, P.; Hansen, B. L.; McMechan, G. A.; Sasagawa, G. S.; Sidles, C.; Stevenson, J. M.; Wirtz, J.
1990-09-01
An Airy-type geophysical experiment was conducted in a 2-km-deep hole in the Greenland ice cap at depths between 213 m and 1673 m to test for possible violations of Newton's inverse square law. Gravity measurements were made at eight depths in 183-m intervals with a LaCoste & Romberg borehole gravity meter. An anomalous variation in gravity totaling 3.87 mGal (3.87x10-5m/s2) in the depth interval of 1460 m was observed. This may be attributed either to a breakdown of Newtonian gravity or to unexpected density variations in the rock below the ice.
Metrology system for the Terrestrial Planet Finder Coronagraph
NASA Technical Reports Server (NTRS)
Shaklin, Stuart; Marchen, Luis; Zhao, Feng; Peters, Robert D.; Ho, Tim; Holmes, Buck
2004-01-01
The Terrestrial Planet Finder (TPF) employs an aggressive coronagraph designed to obtain better than 1e-10 contrast inside the third Airy ring. Minute changes in low-order aberration content scatter significant light at this position. One implication is the requirement to control low-order aberrations induced by motion of the secondary mirror relative to the primary mirror; sub-nanometer relative positional stability is required. We propose a 6-beam laser truss to monitor the relative positions of the two mirrors. The truss is based on laser metrology developed for the Space Interferometry Mission.
Asymptotic analysis of noisy fitness maximization, applied to metabolism & growth
NASA Astrophysics Data System (ADS)
De Martino, Daniele; Masoero, Davide
2016-12-01
We consider a population dynamics model coupling cell growth to a diffusion in the space of metabolic phenotypes as it can be obtained from realistic constraints-based modeling. In the asymptotic regime of slow diffusion, that coincides with the relevant experimental range, the resulting non-linear Fokker-Planck equation is solved for the steady state in the WKB approximation that maps it into the ground state of a quantum particle in an Airy potential plus a centrifugal term. We retrieve scaling laws for growth rate fluctuations and time response with respect to the distance from the maximum growth rate suggesting that suboptimal populations can have a faster response to perturbations.
Self-accelerating fronts in passively-mode-locked fiber lasers
NASA Astrophysics Data System (ADS)
Derevyanko, Stanislav A.
2017-01-01
We present a family of self-accelerating stable pulses propagating in optical fiber and connecting a slowly-modulated quasi-cw background to an unstable zero level. Such solutions represent a generalization of the self-accelerating Airy beams observed in the linear regime to a nonlinear dissipative system modeled by a standard complex cubic Ginzburg-Landau equation corresponding to linear gain and a (fast) saturable absorber. They can also be viewed as a generalization of the well-studied problem of pulled fronts to include acceleration.
1986-01-01
DISTRIBUTION UNLIMITED .9 17. DISTRIBUTION STATEMENT (of the abstract entered in Block 20, If different from Report) 18. SUPPLEMENTARY NOTES &.0V...studies are still 1I 2 r-equired to ttst tha, e ti eori s nd Letter exp ain te unom lies in these correlations and to determine if there are other yet...e~j . .ajs an important role in determining the -a -gei:./ a-I tumorgenicity of these molecules. Pre. i~’ai-ry zar:inogenicity tests have shown that
Calculating the energy spectrum of complex low-dimensional heterostructures in the electric field.
Khonina, Svetlana N; Volotovsky, Sergey G; Kharitonov, Sergey I; Kazanskiy, Nikolay L
2013-01-01
An algorithm for solving the steady-state Schrödinger equation for a complex piecewise-constant potential in the presence of the E-field is developed and implemented. The algorithm is based on the consecutive matching of solutions given by the Airy functions at the band boundaries with the matrix rank increasing by no more than two orders, which enables the characteristic solution to be obtained in the convenient form for search of the roots. The algorithm developed allows valid solutions to be obtained for the electric field magnitudes larger than the ground-state energy level, that is, when the perturbation method is not suitable.
1981-01-26
The final design of the Mount Airy Public Library is given. Incremental passive design costs are discussed. Performance and economic analyses are made and the results reported. The design process is thoroughly documented. Considerations discussed are: (1) building energy needs; (2) site energy potentials, (3) matching energy needs with site energy potentials, (4) design indicators for best strategies and concepts, (5) schematic design alternatives, (6) performance testing of the alternatives, (7) design selection, and (8) design development. Weather data and Duke Power electric rates are included. (LEW)
Generation of terahertz hollow beams by a photonic quasi-crystal flat lens
NASA Astrophysics Data System (ADS)
Feng, Bo; Liu, Exian; Wang, Ziming; Cai, Weicheng; Liu, Hongfei; Wang, Shuo; Liang, Taiyuan; Xiao, Wei; Liu, Jianjun
2016-06-01
We have designed a decagonal photonic quasi-crystal (PQC) flat lens, which turns an incident terahertz (THz) plane wave into a hollow beam easily and flexibly. The features of the THz hollow beam can be controlled by varying the parameters of a point defect in the center of the lens, i.e., the PQC flat lens can be used as a flexible tool for THz optical captivity or optical tweezer. The results showing that an airy disk, whose mean beam width is similar to the incident wavelength and power-in-the-bucket (PIB) is more than 96%, can be generated in the far field.
Fractional Schrödinger equation in optics.
Longhi, Stefano
2015-03-15
In quantum mechanics, the space-fractional Schrödinger equation provides a natural extension of the standard Schrödinger equation when the Brownian trajectories in Feynman path integrals are replaced by Levy flights. Here an optical realization of the fractional Schrödinger equation, based on transverse light dynamics in aspherical optical cavities, is proposed. As an example, a laser implementation of the fractional quantum harmonic oscillator is presented in which dual Airy beams can be selectively generated under off-axis longitudinal pumping.
The discoveries of Neptune and Triton.
NASA Astrophysics Data System (ADS)
Moore, P.
The story of the tracking-down of Neptune has been told many times, but even today there are still discrepancies in the various accounts, to say nothing of conflicting opinions. To some people, John Couch Adams is a shining hero and George Biddell Airy a black villain; to others it is Le Verrier who is the hero, and Adams an unimportant member of the supporting cast. Of course, all this is absurd. In the author's view, the true discoverers of Neptune were Johann Gottfried Galle and Heinrich D'Arrest.
2011-08-16
operating at 1064 nm wavelength. The maximum pulse energy of the heater laser is 3.3 J. The heater pulses are combined with femtosecond igniter pulses...properties of the optical fiber where lasers pulses propagate. Figure 3: Top row, left: Temporal waveforms of the Airy pulse with -60,000 fs3...γ equals 105 (W·m)−1, and the zero dispersion wavelength of the fiber is 745 nm. The coupling efficiency of the shaped laser pulses into the fiber in
Improved coordinates of features in the vicinity of the Viking lander site on Mars
NASA Technical Reports Server (NTRS)
Davies, M. E.; Dole, S. H.
1980-01-01
The measurement of longitude of the Viking 1 landing site and the accuracy of the coordinates of features in the area around the landing site are discussed. The longitude must be measured photogrammatically from the small crater, Airy 0, which defines the 0 deg meridian on Mars. The computer program, GIANT, which was used to perform the analytical triangulations, and the photogrammetric computation of the longitude of the Viking 1 lander site are described. Improved coordinates of features in the vicinity of the Viking 1 lander site are presented.
Rejoice in the hubris: useful things biologists could do for physicists
NASA Astrophysics Data System (ADS)
Austin, Robert H.
2014-10-01
Political correctness urges us to state how wonderful it is to work with biologists and how, just as the lion will someday lie down with the lamb, so will interdisciplinary work, where biologists and physicists are mixed together in light, airy buildings designed to force socialization, give rise to wonderful new science. But it has been said that the only drive in human nature stronger than the sex drive is the drive to censor and suppress, and so I claim that it is OK for physicists and biologists to maintain a wary distance from each other, so that neither one censors or suppresses the wild ideas of the other.
Sutton, G W; Weiner, M M; Mani, S A
1976-09-01
Theoretical Fraunhofer diffraction patterns are presented for uniformly illuminated square apertures with noncentered square obscurations. The energy within a given subtended solid angle in the far field is calculated. It is shown that the cornered-off-axis obscuration provides much more far-field energy in a given spot size than the centered obscuration for the same clear aperture area and total energy, for example, 82% more far-field energy in the first Airy square for 50% obscuration, thus providing superior performance for practical systems.
Quantitative void characterization in structural ceramics using scanning laser acoustic microscopy
NASA Technical Reports Server (NTRS)
Roth, D. J.; Generazio, E. R.; Baaklini, G. Y.
1986-01-01
The ability of scanning laser acoustic microscopy (SLAM) to characterize artificially seeded voids in sintered silicon nitride structural ceramic specimens was investigated. Using trigonometric relationships and Airy's diffraction theory, predictions of internal void depth and size were obtained from acoustic diffraction patterns produced by the voids. Agreement was observed between actual and predicted void depths. However, predicted void diameters were generally much greater than actual diameters. Precise diameter predictions are difficult to obtain due to measurement uncertainty and the limitations of 100 MHz SLAM applied to typical ceramic specimens.
Experimental study of spatial coherence diffraction based on full-field coherence visualization.
Zhao, Juan; Wang, Wei
2014-10-01
A novel optical geometry for direct visualization of the optical coherence function is proposed. The diffractions of partially coherent light by apertures with various forms are experimentally investigated, and the full-field spatial coherence functions have been observed by using the proposed interferometric system. Similar to the well-known Airy disk stemming from optical diffraction, we studied the spatial coherence function near the coherence focal plane on the analogy of the Fraunhofer and Fresnel diffraction integrals. Following the conventional definitions for the optical resolutions in the optical imaging system, the lateral and longitudinal resolutions for spatial coherence imaging have been proposed.
Kardar-Parisi-Zhang universality class and the anchored Toom interface
NASA Astrophysics Data System (ADS)
Barkema, G. T.; Ferrari, P. L.; Lebowitz, J. L.; Spohn, H.
2014-10-01
We revisit the anchored Toom interface and use Kardar-Parisi-Zhang scaling theory to argue that the interface fluctuations are governed by the Airy1 process with the role of space and time interchanged. The predictions, which contain no free parameter, are numerically well confirmed for space-time statistics in the stationary state. In particular, the spatial fluctuations of the interface computed numerically agree well with those given by the GOE edge distribution of Tracy and Widom [Commun. Math. Phys. 177, 727 (1996), 10.1007/BF02099545].
Nonlinear steady-state coupling of LH waves
Ko, K.; Krapchev, V.B.
1981-02-01
The coupling of lower hybrid waves at the plasma edge by a two waveguide array with self-consistent density modulation is solved numerically. For a linear density profile, the governing nonlinear Klein-Gordon equation for the electric field can be written as a system of nonlinearly modified Airy equations in Fourier k/sub z/-space. Numerical solutions to the nonlinear system satisfying radiation condition are obtained. Spectra broadening and modifications to resonance cone trajectories are observed with increase of incident power.
Nuclear mean field and double-folding model of the nucleus-nucleus optical potential
NASA Astrophysics Data System (ADS)
Khoa, Dao T.; Phuc, Nguyen Hoang; Loan, Doan Thi; Loc, Bui Minh
2016-09-01
Realistic density dependent CDM3Yn versions of the M3Y interaction have been used in an extended Hartree-Fock (HF) calculation of nuclear matter (NM), with the nucleon single-particle potential determined from the total NM energy based on the Hugenholtz-van Hove theorem that gives rise naturally to a rearrangement term (RT). Using the RT of the single-nucleon potential obtained exactly at different NM densities, the density and energy dependence of the CDM3Yn interactions was modified to account properly for both the RT and observed energy dependence of the nucleon optical potential. Based on a local density approximation, the double-folding model of the nucleus-nucleus optical potential has been extended to take into account consistently the rearrangement effect and energy dependence of the nuclear mean-field potential, using the modified CDM3Yn interactions. The extended double-folding model was applied to study the elastic 12C+12C and 16O+12C scattering at the refractive energies, where the Airy structure of the nuclear rainbow has been well established. The RT was found to affect significantly the real nucleus-nucleus optical potential at small internuclear distances, giving a potential strength close to that implied by the realistic optical model description of the Airy oscillation.
Fabrication and testing of a silicon immersion grating for infrared spectroscopy
Kuzmenko, P.J.; Ciarlo, D.R.; Stevens, C.G.
1994-07-25
Recent advances in silicon micromachining techniques (e.g. anisotropic etching) allow the fabrication of very coarse infrared echelle gratings. When used in immersion mode, the dispersion is increased proportionally to the refractive index. This permits a very significant reduction in the overall size of a spectrometer while maintaining the same resolution. We have fabricated a right triangular prism (30{times}60{times}67 mm with a rectangular entrance face 30{times}38 mm) from silicon with a grating etched into the face of the hypotenuse. The grating covers an area of 32 mm by 64 mm and has a 97.5 PM periodicity with a blaze angle of 63.4{sup o}. The groove surfaces are very smooth with a roughness of a few manometers. Random defects in the silicon are the dominant source of grating scatter ({approx} 12% at 3.39 {mu}m). We measure a grating ghost intensity of 1.2%. The diffraction peak is quite narrow, slightly larger than the Airy disc diameter at F/12. However due to wavefront aberrations, perhaps 15--20% of the diffracted power is in the peak with the rest distributed in a diameter roughly five times the Airy disc.
Palik, E D; Boukari, H; Gammon, R W
1996-01-01
While investigating the instrumental function of a Fabry-Perot interferometer [Appl. Opt. 34, 58 (1995), we noticed some variation in finesse and contrast in the measured spectra when a 1.5-mm-diameter aperture was used at various spots within the standard 8-mm aperture. By comparing experimentally determined finesse versus contrast plots for many such spectra with calculated plots, we found spots on the plates that gave non-Airy-function line shapes over the entire order of interference, unlike the Airy line shape we determined previously by using the entire 8-mm aperture. We have reviewed several models that describe the effects of various types of surface defects, such as Gaussian-height distribution of roughness, curvature and tilt of plates, sinusoidal roughness, and asymmetrical roughness on the finesse and contrast. Our experimental results can be accounted for if we assume that the reflectivity is nonuniform over the Fabry-Perot plates and that there is some reasonable contribution that is due to Gaussian roughness, curvature, or tilt.
Torreão, José R A
2015-10-01
A signal-tuned approach has been recently introduced for modeling stimulus-dependent cortical receptive fields. The approach is based on signal-tuned Gabor functions, which are Gaussian-modulated sinusoids whose parameters are obtained from a "tuning" signal. Given a stimulus to a cell, it is taken as the tuning signal for the Gabor function modeling the cell's receptive field, and the inner product of the stimulus and the stimulus-dependent field produces the cell's response. Here, we derive and solve the equation of motion for the signal-tuned complex cell response r(x,τ), where x and τ are receptive-field parameters: its center, and the delay with which it adapts to a change in input. The motion equation can be mapped onto the Schrödinger equation for a system with time-dependent imaginary mass and time-dependent complex potential, and yields a plane-wave solution and an Airy-packet solution. The plane-wave solution replicates responses previously obtained for temporally modulated and translating signals, and yields responses which seem compatible with apparent-motion effects, when the stimulus is a pair of alternating pulses. The Airy-packet solution can lead to long-range propagating responses.
Improved detection and false alarm rejection for chemical vapors using passive hyperspectral imaging
NASA Astrophysics Data System (ADS)
Marinelli, William J.; Miyashiro, Rex; Gittins, Christopher M.; Konno, Daisei; Chang, Shing; Farr, Matt; Perkins, Brad
2013-05-01
Two AIRIS sensors were tested at Dugway Proving Grounds against chemical agent vapor simulants. The primary objectives of the test were to: 1) assess performance of algorithm improvements designed to reduce false alarm rates with a special emphasis on solar effects, and 3) evaluate performance in target detection at 5 km. The tests included 66 total releases comprising alternating 120 kg glacial acetic acid (GAA) and 60 kg triethyl phosphate (TEP) events. The AIRIS sensors had common algorithms, detection thresholds, and sensor parameters. The sensors used the target set defined for the Joint Service Lightweight Chemical Agent Detector (JSLSCAD) with TEP substituted for GA and GAA substituted for VX. They were exercised at two sites located at either 3 km or 5 km from the release point. Data from the tests will be presented showing that: 1) excellent detection capability was obtained at both ranges with significantly shorter alarm times at 5 km, 2) inter-sensor comparison revealed very comparable performance, 3) false alarm rates < 1 incident per 10 hours running time over 143 hours of sensor operations were achieved, 4) algorithm improvements eliminated both solar and cloud false alarms. The algorithms enabling the improved false alarm rejection will be discussed. The sensor technology has recently been extended to address the problem of detection of liquid and solid chemical agents and toxic industrial chemical on surfaces. The phenomenology and applicability of passive infrared hyperspectral imaging to this problem will be discussed and demonstrated.
Centroids computation and point spread function analysis for reverse Hartmann test
NASA Astrophysics Data System (ADS)
Zhao, Zhu; Hui, Mei; Liu, Ming; Dong, Liquan; Kong, Linqqin; Zhao, Yuejin
2017-03-01
This paper studies the point spread function (PSF) and centroids computation methods to improve the performance of reverse Hartmann test (RHT) in poor conditions, such as defocus, background noise, etc. In the RHT, we evaluate the PSF in terms of Lommel function and classify it as circle of confusion (CoC) instead of Airy disk. Approximation of a CoC spot with Gaussian or super-Gaussian profile to identify its centroid forms the basis of centroids algorithm. It is also effective for fringe pattern while the segmental fringe is served as a 'spot' with an infinite diameter in one direction. RHT experiments are conducted to test the fitting effects and centroiding performances of the methods with Gaussian and super-Gaussian approximations. The fitting results show that the super-Gaussian obtains more reasonable fitting effects. The super-Gauss orders are only slightly larger than 2 means that the CoC has a similar profile with Airy disk in certain conditions. The results of centroids computation demonstrate that when the signal to noise ratio (SNR) is falling, the centroid computed by super-Gaussian method has a less shift and the shift grows at a slower pace. It implies that the super-Gaussian has a better anti-noise capability in centroid computation.
NASA Astrophysics Data System (ADS)
Eliasson, B.; Milikh, G.; Shao, X.; Mishin, E. V.; Papadopoulos, K.
2015-04-01
We have numerically investigated the development of strong Langmuir turbulence (SLT) and associated electron acceleration at different angles of incidence of ordinary (O) mode pump waves. For angles of incidence within the Spitze cone, the turbulence initially develops within the first maximum of the Airy pattern near the plasma resonance altitude. After a few milliseconds, the turbulent layer shifts downwards by about 1 km. For injections outside the Spitze region, the turning point of the pump wave is at lower altitudes. Yet, an Airy-like pattern forms here, and the turbulence development is quite similar to that for injections within the Spitze. SLT leads to the acceleration of 10-20 eV electrons that ionize the neutral gas thereby creating artificial ionospheric layers. Our numerical modeling shows that most efficient electron acceleration and ionization occur at angles between the magnetic and geographic zenith, where SLT dominates over weak turbulence. Possible effects of the focusing of the electromagnetic beam on magnetic field-aligned density irregularities and the finite heating beam width at the magnetic zenith are also discussed. The results have relevance to ionospheric heating experiments using ground-based, high-power radio transmitters to heat the overhead plasma, where recent observations of artificial ionization layers have been made.
Holonomy, quantum mechanics and the signal-tuned Gabor approach to the striate cortex
NASA Astrophysics Data System (ADS)
Torreão, José R. A.
2016-02-01
It has been suggested that an appeal to holographic and quantum properties will be ultimately required for the understanding of higher brain functions. On the other hand, successful quantum-like approaches to cognitive and behavioral processes bear witness to the usefulness of quantum prescriptions as applied to the analysis of complex non-quantum systems. Here, we show that the signal-tuned Gabor approach for modeling cortical neurons, although not based on quantum assumptions, also admits a quantum-like interpretation. Recently, the equation of motion for the signal-tuned complex cell response has been derived and proven equivalent to the Schrödinger equation for a dissipative quantum system whose solutions come under two guises: as plane-wave and Airy-packet responses. By interpreting the squared magnitude of the plane-wave solution as a probability density, in accordance with the quantum mechanics prescription, we arrive at a Poisson spiking probability — a common model of neuronal response — while spike propagation can be described by the Airy-packet solution. The signal-tuned approach is also proven consistent with holonomic brain theories, as it is based on Gabor functions which provide a holographic representation of the cell’s input, in the sense that any restricted subset of these functions still allows stimulus reconstruction.
Optical antenna gain. 2: receiving antennas.
Degnan, J J; Klein, B J
1974-10-01
Expressions are derived for the gain of a centrally obscured, circular optical antenna when used as the collecting and focusing optics in a laser receiver which include losses due to (1) blockage of the incoming light by the central obscuration, (2) the spillover of energy at the detector, and (3) the effect of local oscillator distribution in the case of heterodyne or homodyne detection. Numerical results are presented for direct detection and for three types of local oscillator distributions (uniform, Gaussian, and matched) in the case of heterodyne or homodyne detection. The results are presented in several graphs that allow the rapid evaluation of receiver gain for an arbitrary set of telescope and detector parameters. It is found that, for uniform illumination by the LO, the optimum SNR is obtained when the detector radius is approximately 0.74 times the Airy disk radius. The use of an optimized Gaussian (spot size = 0.46 times the Airy disk radius) improves the receiver gain by less than 1 dB. Theuse results are insensitive to the size of the central obscuration.
IRAN: interferometric remapped array nulling
NASA Astrophysics Data System (ADS)
Aristidi, Eric; Vakili, Farrokh; Abe, Lyu; Belu, Adrian; Lopez, Bruno; Lanteri, Henri; Schutz, A.; Menut, Jean-Luc
2004-10-01
This paper describes a method of beam-combination in the so-called hypertelescope imaging technique recently introduced by Labeyrie in optical interferometry. The method we propose is an alternative to the Michelson pupil reconfiguration that suffers from the loss of the classical object-image convolution relation. From elementary theory of Fourier optics we demonstrate that this problem can be solved by observing in a combined pupil plane instead of an image plane. The point-source intensity distribution (PSID) of this interferometric "image" tends towards a psuedo Airy disc (similar to that of a giant monolithic telescope) for a sufficiently large number of telescopes. Our method is applicable to snap-shot imaging of extended sources with a field comparable to the Airy pattern of single telescopes operated in a co-phased multi-aperture interferometric array. It thus allows to apply conveniently pupil plane coronagraphy. Our technique called Interferometric Remapped Array Nulling (IRAN) is particularly suitable for high dynamic imaging of extra-solar planetary companions, circumstellar nebulosities or extra-galactic objects where long baseline interferometry would closely probe the central regions of AGNs for instance.
Interferometric Remapped Array Nulling
NASA Astrophysics Data System (ADS)
Vakili, F.; Aristidi, E.; Abe, L.; Lopez, B.
2004-07-01
This paper describes a method of beam-combination in the so-called hypertelescope imaging technique recently introduced by Labeyrie in optical interferometry. The method we propose is an alternative to the Michelson pupil reconfiguration that suffers from the loss of the classical object-image convolution relation. From elementary theory of Fourier optics we demonstrate that this problem can be solved by reconfiguring images instead of pupils. Imaging is performed in a combined pupil-plane where the point-source intensity distribution (PSID by comparison to the more commonly quoted point-spread function, PSF) tends towards a pseudo Airy disc for a sufficiently large number of telescopes. Our method is applicable to snap-shot imaging of extended sources with a field limited to the Airy pattern of single telescopes operated in a co-phased multi-aperture interferometric array. It thus allows to apply conveniently pupil plane coronagraphy. Our technique called Interferometric Remapped Array Nulling (IRAN) is particularly suitable for high dynamic imaging of extra-solar planetary companions or extra-galactic objects where long baseline interferometry would closely probe the central regions of AGNs for instance. We also discuss the application of IRAN to improve the performances of imaging and/or nulling interferometers like the full-fledged VLTI array or the DARWIN space-borne mission.
NASA Astrophysics Data System (ADS)
Cadio, Cécilia; Saraswati, Anita; Cattin, Rodolphe; Mazzotti, Stéphane
2016-11-01
Estimating how topography is maintained provides insights into the different factors responsible for surface deformations and their relative roles. Here, we develop a new and simple approach to assess the degree of isostatic compensation of continental topography at regional scale from GOCE gravity gradients. We calculate the ratio between the radial gradient observed by GOCE and that calculated from topography only. From analytical and statistical formulations, simple relationships between this ratio and the degree of compensation are obtained under the Airy-Heiskanen isostasy hypothesis. Then, a value of degree of compensation at each point of study area can be easily deduced. We apply our method to the Alaska-Canada Cordillera and validate our results by comparison with a standard isostatic gravity anomaly model and additional geophysical information for this area. Both our GOCE-based results and the isostatic anomaly show that Airy-Heiskanen isostasy prevails for the Yukon Plateau whereas additional mechanisms are required to support topography below the Northwest Territories Craton and the Yakutat collision zone.
Altimetry data and the elastic stress tensor of subduction zones
NASA Technical Reports Server (NTRS)
Caputo, M.
1985-01-01
The stress field in the lithosphere caused by the distribution of density anomalies associated to the geoidal undulations observed by the GEOS-3 and SEASAT Earth satellites in the Tonga region was studied. Different models of the lithosphere were generated with different assumptions on the density distribution and geometry, all generating a geoid profile almost identical to the observed one. The first model is the Airy isostatic hypothesis which consists of a crust of density 2.85 laying on a lithosphere of density 3.35. The models obtained with different compensation depths give residual shortwavelength anomalies of the order of several tens of mgal and several tens of meters geoidal undulations. It indicates that there is no isostasy of the Airy type in the Tonga region because the observed geoid has very smooth undulation of about 25 m over a distance of 2000 km. The Pratt isostatic hypothesis is used in a model consisting of a crust of variable density laying on a lithosphere of higher density. This model gives smaller residual anomalies but still shows that there is no isostasy of the Pratt type in the Tonga region because the observed geoidal undulation are much smaller and smoother than the residual undulations associated to the Pratt model of isostasy.
Assessment of a multibeam Fizeau wedge interferometer for Doppler wind lidar.
McKay, Jack A
2002-03-20
The Fabry-Perot interferometer is the standard instrument for the direct detection Doppler lidar measurement of atmospheric wind speeds. The multibeam Fizeau wedge has some practical advantages over the Fabry-Perot, such as the linear fringe pattern, and is evaluated for this application. The optimal Fizeau must have a resolving power of 10(6) or more. As the multibeam Fizeau wedge is pushed to such high resolving power, the interference fringes of the device become complicated by asymmetry and secondary maxima. A simple condition for the interferometer plate reflectance, optical gap, and wedge angle reveals whether a set of parameters will yield simple, Airy-like fringes or complex Fizeau fringes. Tilting of the Fizeau wedge improves the fringe shape and permits an extension of the regime of Airy-like fringes to higher resolving power. Sufficient resolving power for the wind lidar application is shown to be possible with a large-gap, low-finesse multibeam Fizeau wedge. Liabilities of the multibeam Fizeau wedge in the wind lidar application include a smaller acceptance solid angle and calibration sensitivity to localized deviations of the plates from the ideal.
Noor, Fatimah A. Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal
2015-04-16
In this paper, we discuss the electron transmittance and tunneling current in high-k-based-MOS capacitors with trapping charge by including the off-diagonal effective-mass tensor elements and the effect of coupling between transverse and longitudinal energies represented by an electron velocity in the gate. The HfSiO{sub x}N/SiO{sub 2} dual ultrathin layer is used as the gate oxide in an n{sup +} poly- Si/oxide/Si capacitor to replace SiO{sub 2}. The main problem of using HfSiO{sub x}N is the charge trapping formed at the HfSiO{sub x}N/SiO{sub 2} interface that can influence the performance of the device. Therefore, it is important to develop a model taking into account the presence of electron traps at the HfSiO{sub x}N/SiO{sub 2} interface in the electron transmittance and tunneling current. The transmittance and tunneling current in n{sup +} poly- Si/HfSiO{sub x}N/trap/SiO2/Si(100) capacitors are calculated by using Airy wavefunctions and a transfer matrix method (TMM) as analytical and numerical approaches, respectively. The transmittance and tunneling current obtained from the Airy wavefunction are compared to those computed by the TMM. The effects of the electron velocity on the transmittance and tunneling current are also discussed.
NASA Astrophysics Data System (ADS)
Bodzenta, Jerzy
2004-10-01
The 9th International Workshop on Photoacoustics and Photothermics was held in Szczyrk as a part of the 33rd Winter School on Molecular and Quantum Acoustics. Photoacoustic and Photothermal Workshops have been organized annually since 1996, by the Upper-Silesian Division of Polish Acoustical Society in co-operation with Institute of Physics, Silesian Technical University of Gliwice. Traditionally, the workshops take place in small towns in Beskidy Mountains. They always start on Thursday afternoon and end on Friday evening. The idea of these workshops is to give opportunities for direct contacts of scientists using photoacoustic and photothermal phenomena in their investigations. As a result participants are physicists, chemists and engineers interested in: theoretical backgrounds of photoacoustic and photothermal experiments, development of new measuring techniques, investigation of di?erent physical processes and determination of physical properties of various samples. So the thematic scope of the workshops is wide, but all contributions are connected with generation and propagation of non-stationary temperature fields. The workshop is a place where experienced researchers present review lectures, younger scientists and PhD students show their own, original results, and all of them have possibilities for discussions either during sessions or during informal meetings. These Proceedings contain 17 scientific papers. The most of them are printed versions of contributions presented during the 9th Workshop on Photoacoustics and Photothermics. One paper covers results showed in oral presentation and two posters. A few titles are slightly changed according to referee's suggestions. I would like to thank all participants for preparing manuscripts for these proceedings. Special thanks should be expressed for referees: Prof. Danuta Frackowiak, Prof. Robert E. Imhof, Dr. Kyril L. Muratikov, Prof. Antoni Śliwiński and Priv. Doz. Heinz-Günter Walther for their valuable
Proceedings from the 6th Annual University of Calgary Leaders in Medicine Research Symposium.
Roberts, Jodie I; Beatty, Jennifer K; Peplowski, Michael A; Keough, Michael B; Yipp, Bryan G; Hollenberg, Morley D; Beck, Paul L
2015-12-04
On November 14, 2014, the Leaders in Medicine (LIM) program at the Cumming School of Medicine, University of Calgary hosted its 6th Annual Research Symposium. Dr. Danuta Skowronski, Epidemiology Lead for Influenza and Emerging Respiratory Pathogens at the British Columbia Centre for Disease Control (BCCDC), was the keynote speaker and presented a lecture entitled "Rapid response research during emerging public health crises: influenza and reflections from the five year anniversary of the 2009 pandemic". The LIM symposium provides a forum for both LIM and non-LIM medical students to present their research work, either as an oral or poster presentation. There were a total of six oral presentations and 77 posters presented. The oral presentations included: Swathi Damaraju, "The role of cell communication and 3D Cell-Matrix environment in a stem cell-based tissue engineering strategy for bone repair"; Menglin Yang, "The proteolytic activity of Nepenthes pitcher fluid as a therapeutic for the treatment of celiac disease"; Amelia Kellar, "Monitoring pediatric inflammatory bowel disease - a retrospective analysis of transabdominal ultrasound"; Monica M. Faria-Crowder, "The design and application of a molecular profiling strategy to identify polymicrobial acute sepsis infections"; Waleed Rahmani, "Hair follicle dermal stem cells regenerate the dermal sheath, repopulate the dermal papilla and modulate hair type"; and, Laura Palmer, "A novel role for amyloid beta protein during hypoxia/ischemia". The article on the University of Calgary Leaders in Medicine Program, "A Prescription that Addresses the Decline of Basic Science Education in Medical School," in a previous issue of CIM (2014 37(5):E292) provides more details on the program. Briefly, the LIM Research Symposium has the following objectives: (1) to showcase the impressive variety of projects undertaken by students in the LIM Program as well as University of Calgary medical students; (2) to encourage medical
The Glacial BuzzSaw, Isostasy, and Global Crustal Models
NASA Astrophysics Data System (ADS)
Levander, A.; Oncken, O.; Niu, F.
2015-12-01
The glacial buzzsaw hypothesis predicts that maximum elevations in orogens at high latitudes are depressed relative to temperate latitudes, as maximum elevation and hypsography of glaciated orogens are functions of the glacial equilibrium line altitude (ELA) and the modern and last glacial maximum (LGM) snowlines. As a consequence crustal thickness, density, or both must change with increasing latitude to maintain isostatic balance. For Airy compensation crustal thickness should decrease toward polar latitudes, whereas for Pratt compensation crustal densities should increase. For similar convergence rates, higher latitude orogens should have higher grade, and presumably higher density rocks in the crustal column due to more efficient glacial erosion. We have examined a number of global and regional crustal models to see if these predictions appear in the models. Crustal thickness is straightforward to examine, crustal density less so. The different crustal models generally agree with one another, but do show some major differences. We used a standard tectonic classification scheme of the crust for data selection. The globally averaged orogens show crustal thicknesses that decrease toward high latitudes, almost reflecting topography, in both the individual crustal models and the models averaged together. The most convincing is the western hemisphere cordillera, where elevations and crustal thicknesses decrease toward the poles, and also toward lower latitudes (the equatorial minimum is at ~12oN). The elevation differences and Airy prediction of crustal thickness changes are in reasonable agreement in the North American Cordillera, but in South America the observed crustal thickness change is larger than the Airy prediction. The Alpine-Himalayan chain shows similar trends, however the strike of the chain makes interpretation ambiguous. We also examined cratons with ice sheets during the last glacial period to see if continental glaciation also thins the crust toward
The control network of Mars: April 1991
NASA Technical Reports Server (NTRS)
Davies, Merton E.; Rogers, Patricia G.
1991-01-01
The modern geodetic control network of Mars was first established based on Mariner 9 images with 1-2 km/pixel resolutions and covered almost the entire Martian surface. The introduction of higher resolution (10-200 meter/pixel) Viking Orbiter images greatly improved the accuracy and density of points in the control network. Analysis of the Viking Lander radio tracking data led to more accurate measurements of Mars' rotation period, spin axis direction, and the lander coordinates relative to the inertial reference frame. The prime meridian on Mars was defined by the Geodesy/Cartography Group of the Mariner 9 Television Team as the crater Airy-0, located about 5 degrees south of the equator. The Viking 1 Lander site was identified on a high resolution Viking frame. The control point measurements form the basis of a least squares solution determined by analytical triangulation after the pixel measurements are corrected for geometric distortions and converted to millimeter coordinates in the camera focal plane. Photogrammetric strips encircling Mars at the equator and at 60 degree north south were used to strengthen the overall net and improve the accuracy of the coordinates of points. In addition, photogrammetric strips along 0, 90, 180, and 270 degrees longitude to the Viking 1 Lander site have all significantly strengthened the control network. Most recently, photogrammetric strips were added to the net along 30 degrees north latitude between 0 and 180 degrees, and along 30 degrees between 180 and 360 degrees. The Viking 1 Lander site and Airy-0 are linked through photogrammetric strips occurring along the 0 degree meridian from Airy-0 to 65 degrees north, from that point through the Viking 1 Lander site to the equator, and along the equator to 180 degrees longitude. The Viking 1 lander site is thus a well calibrated area with coordinates of points accurate to approximately 200 meters relative to the J2000 inertial coordinate system. This will be a useful
Curved singular beams for three-dimensional particle manipulation
Zhao, Juanying; Chremmos, Ioannis D.; Song, Daohong; Christodoulides, Demetrios N.; Efremidis, Nikolaos K.; Chen, Zhigang
2015-01-01
For decades, singular beams carrying angular momentum have been a topic of considerable interest. Their intriguing applications are ubiquitous in a variety of fields, ranging from optical manipulation to photon entanglement, and from microscopy and coronagraphy to free-space communications, detection of rotating black holes, and even relativistic electrons and strong-field physics. In most applications, however, singular beams travel naturally along a straight line, expanding during linear propagation or breaking up in nonlinear media. Here, we design and demonstrate diffraction-resisting singular beams that travel along arbitrary trajectories in space. These curved beams not only maintain an invariant dark “hole” in the center but also preserve their angular momentum, exhibiting combined features of optical vortex, Bessel, and Airy beams. Furthermore, we observe three-dimensional spiraling of microparticles driven by such fine-shaped dynamical beams. Our findings may open up new avenues for shaped light in various applications. PMID:26166011
Composition measurements of binary mixture droplets by rainbow refractometry
Wilms, J.; Weigand, B
2007-04-10
So far, refractive index measurements by rainbow refractometry have been used to determine the temperature of single droplets and ensembles of droplets. Rainbow refractometry is, for the first time, to the best of our knowledge, applied to measure composition histories of evaporating, binary mixture droplets. An evaluation method is presented that makes use of Airy theory and the simultaneous size measurement by Mie scattering imaging. The method further includes an empirical correction function for a certain diameter and refractive index range. The measurement uncertainty was investigated by numerical simulations with Lorenz-Mie theory. For the experiments, an optical levitation setup was used allowing for long measurement periods. Temperature measurements of single-component droplets at different temperature levels are shown to demonstrate the accuracy of rainbow refractometry. Measurements of size and composition histories of binary mixture droplets are presented for two different mixtures. Experimental results show good agreement with numerical results using a rapid-mixing model.
Evidence for a dynamically refracted primary bow in weakly bound 9Be rainbow scattering from 16O
NASA Astrophysics Data System (ADS)
Ohkubo, S.; Hirabayashi, Y.
2016-09-01
We present for the first time evidence for the existence of a dynamically refracted primary bow for 9Be+16O scattering. This is demonstrated through the use of coupled channel calculations with an extended double folding potential derived from the density-dependent effective two-body force and precise microscopic cluster wave functions for 9Be. The calculations reproduce the experimental Airy structure in 9Be+16O scattering well. It is found that coupling of a weakly bound 9Be nucleus to excited states plays the role of a booster lens, dynamically enhancing the refraction over the static refraction due to the Luneburg lens mean field potential between the ground states of 9Be and 16O.
Nuclear rainbow in elastic scattering of {sup 9}Be nuclei
Glukhov, Yu. A. Ogloblin, A. A.; Artemov, K. P.; Rudakov, V. P.
2010-01-15
A systematic investigation of the elastic scattering of the {sup 9}Be nucleus, which is among themost loosely bound stable nuclei was performed.Differential cross sections for elastic {sup 9}Be + {sup 16}O scattering were measured at a c.m. energy of 47.5 MeV (beam of 132-MeV {sup 16}O nuclei). Available data at different energy values and data for neighboring nuclei were included in our analysis. As a result, the very fact of rainbow scattering was reliably established for the first time in systems involving {sup 9}Be. In addition, the analysis in question made it possible to identify Airy minima and to determine unambiguously the nucleus-nucleus potential with a high probability.
Method to mosaic gratings that relies on analysis of far-field intensity patterns in two wavelengths
NASA Astrophysics Data System (ADS)
Hu, Yao; Zeng, Lijiang; Li, Lifeng
2007-01-01
We propose an experimental method to coherently mosaic two planar diffraction gratings. The method uses a Twyman-Green interferometer to guarantee the planar parallelism of the two sub-aperture gratings, and obtains the in-plane rotational error and the two translational errors from analysis of the far-field diffraction intensity patterns in two alignment wavelengths. We adjust the relative attitude and position of the two sub-aperture gratings to produce Airy disk diffraction patterns in both wavelengths. In our experiment, the repeatability of in-plane rotation adjustment was 2.35 μrad and that of longitudinal adjustment was 0.11 μm. The accuracy of lateral adjustment was about 2.9% of the grating period.
Gravity study of the Pitcairn-Easter hotline
NASA Astrophysics Data System (ADS)
Maia, M.; Dehghani, G. A.; Diament, M.; Francheteau, J.; Stoffers, P.
1994-11-01
Shipboard free air gravity and bathymetric anomalies with an extension of 400 km were identified across the Pitcairn-Easter hotline in the South Pacific. The anomalies are associated with one of the positive geoid undulations observed in the area from satellite data. Several smaller topographic features, volcano-tectonic ridges oriented N 65 deg E, are superimposed on the topographic hig. Admittance computations and direct modeling show that the swell topography is compensated by a low density zone within the lithosphere, 4 to 8 km below the crust. The volcano tectonic ridges are locally compensated in a classical Airy sense. The swell and the associated ridges were probably created by the action of a thermal anomaly resulting from the interaction of the Easter Island hotspot and of the Easter Microplate accretion centers.
Computer simulation of super-resolution point source image detection
NASA Astrophysics Data System (ADS)
Fillard, Jean-Pierre; M'timet, H.; Lussert, Jean-Marc; Castagne, Michel
1993-11-01
We present a computer simulation of the analysis of an `in-focus' 2D Airy disk. Two competing methods are used to calculate the coordinates of the center of this point spread function image. The first one is the classical technique that relies on the 2D `centroid' of the image, and the second one is a more original method that uses the frequency dependence of the argument of the Fourier transform. Comparative simulations show that the latter technique [Fourier phase shift (FPS)] allows us to obtain a very good precision of better than 1% of a pixel spacing after quantization. Perturbations such as dc offset reduction, quantization noise, and additive Gaussian noise are introduced in the simulation. The results show that there is an improved perturbation immunity for the FPS method.
Bending light via adiabatic optical transition in longitudinally modulated photonic lattices.
Han, Bin; Xu, Lei; Dou, Yiling; Xu, Jingjun; Zhang, Guoquan
2015-10-29
Bending light in a controllable way is desired in various applications such as beam steering, navigating and cloaking. Different from the conventional way to bend light by refractive index gradient, transformation optics or special beams through wavefront design such as Airy beams and surface plasmons, we proposed a mechanism to bend light via resonant adiabatic optical transition between Floquet-Bloch (FB) modes from different FB bands in longitudinally modulated photonic lattices. The band structure of longitudinally modulated photonic lattices was calculated by employing the concept of quasi-energy based on the Floquet-Bloch theory, showing the existence of band discontinuities at specific resonant points which cannot be revealed by the coupled-mode theory. Interestingly, different FB bands can be seamlessly connected at these resonant points in longitudinally modulated photonic lattices driven by adiabatically varying the longitudinal modulation period along the propagation direction, which stimulates the adiabatic FB mode transition between different FB bands.
NASA Astrophysics Data System (ADS)
Bornemann, Folkmar
2016-08-01
By applying an idea of Borodin and Olshanski [J. Algebra 313 (2007), 40-60], we study various scaling limits of determinantal point processes with trace class projection kernels given by spectral projections of selfadjoint Sturm-Liouville operators. Instead of studying the convergence of the kernels as functions, the method directly addresses the strong convergence of the induced integral operators. We show that, for this notion of convergence, the Dyson, Airy, and Bessel kernels are universal in the bulk, soft-edge, and hard-edge scaling limits. This result allows us to give a short and unified derivation of the known formulae for the scaling limits of the classical random matrix ensembles with unitary invariance, that is, the Gaussian unitary ensemble (GUE), the Wishart or Laguerre unitary ensemble (LUE), and the MANOVA (multivariate analysis of variance) or Jacobi unitary ensemble (JUE).
NASA Astrophysics Data System (ADS)
Courtmanche, Amanda; McLeod, Roger; McLeod, David
2006-10-01
A healthy eye has its large set of diffraction patterns, generated by the viewed scene, spread across the visible spectrum. Only the two of these simultaneously coincident with foveal cones, and rods, or with extra-foveal cones, are visually useful. This fact and pupil diameter changes with illumination, which cause proportional wavelength changes, drives the healthy visual state. A quasi-monochromatic interval is coincident with foveal cones, and rods. A shorter, partially overlapping interval aligns with extrafoveal cones, with about twenty nanometers separation. Wavelengths follow the Airy disk radius formula. An unhealthy eye is an eyeball deformed by self- induced vision abuse. Incorrect and effectively static stresses in the large external eye muscles displace and distort the patterns. Rebalancing the proper vision and muscle state are safely, quickly and rapidly restored by mimicking natural eye and head movements with naturoptics.
Covariance of lucky images: performance analysis
NASA Astrophysics Data System (ADS)
Cagigal, Manuel P.; Valle, Pedro J.; Cagigas, Miguel A.; Villó-Pérez, Isidro; Colodro-Conde, Carlos; Ginski, C.; Mugrauer, M.; Seeliger, M.
2017-01-01
The covariance of ground-based lucky images is a robust and easy-to-use algorithm that allows us to detect faint companions surrounding a host star. In this paper, we analyse the relevance of the number of processed frames, the frames' quality, the atmosphere conditions and the detection noise on the companion detectability. This analysis has been carried out using both experimental and computer-simulated imaging data. Although the technique allows us the detection of faint companions, the camera detection noise and the use of a limited number of frames reduce the minimum detectable companion intensity to around 1000 times fainter than that of the host star when placed at an angular distance corresponding to the few first Airy rings. The reachable contrast could be even larger when detecting companions with the assistance of an adaptive optics system.
NASA Astrophysics Data System (ADS)
Zhou, Jianqin; Shen, Jun; Neill, W. Stuart
2016-07-01
A method of frequency analysis for the measurement of the temperature coefficient of refractive index (dn/dT) using a Fabry-Perot interferometer was developed and tested against ethanol and water. The temperature-dependent interferometric signal described by Airy's formula was analyzed in both the temperature and frequency domains. By fast Fourier transform, a low-pass filter was designed and employed to eliminate the noise superimposed on the signal. dn/dT was determined accurately from the noise-removed signal by peak analysis. Furthermore, the signal frequency parameters may be utilized for the material thermophysical property characterization. This method lays the foundation for an online dn/dT instrument for monitoring chemical processes.
Crustal volumes of the continents and of oceanic and continental submarine plateaus
NASA Technical Reports Server (NTRS)
Schubert, G.; Sandwell, D.
1989-01-01
Using global topographic data and the assumption of Airy isostasy, it is estimated that the crustal volume of the continents is 7182 X 10 to the 6th cu km. The crustal volumes of the oceanic and continental submarine plateaus are calculated at 369 X 10 to the 6th cu km and 242 X 10 to the 6th cu km, respectively. The total continental crustal volume is found to be 7581 X 10 to the 6th cu km, 3.2 percent of which is comprised of continental submarine plateaus on the seafloor. An upper bound on the contintental crust addition rate by the accretion of oceanic plateaus is set at 3.7 cu km/yr. Subduction of continental submarine plateaus with the oceanic lithosphere on a 100 Myr time scale yields an upper bound to the continental crustal subtraction rate of 2.4 cu km/yr.
Numerical algorithms for highly oscillatory dynamic system based on commutator-free method
NASA Astrophysics Data System (ADS)
Li, Wencheng; Deng, Zichen; Zhang, Suying
2007-04-01
In the present paper, an efficiently improved modified Magnus integrator algorithm based on commutator-free method is proposed for the second-order dynamic systems with time-dependent high frequencies. Firstly, the second-order dynamic systems are transferred to the frame of reference by introducing new variable so that highly oscillatory behaviour inherited from the entries. Then the modified Magnus integrator method based on local linearization is appropriately designed for solving the above new form. And some optimized strategies for reducing the number of function evaluations and matrix operations are also suggested. Finally, several numerical examples for highly oscillatory dynamic systems, such as Airy equation, Bessel equation, Mathieu equation, are presented to demonstrate the validity and effectiveness of the proposed method.
Lithospheric structure in the Pacific geoid
NASA Technical Reports Server (NTRS)
Marsh, B. D.
1984-01-01
In order that sub-lithospheric density variations be revealed with the geoid, the regional geoid anomalies associated with bathymetric variations must first be removed. Spectral techniques were used to generate a synthetic geoid by filtering the residual bathymetry assuming an Airy-type isostatic compensation model. An unbiased estimated of the admittances show that for region under study, no single compensation mechanism will explain all of the power in the geoid. Nevertheless, because topographic features are mainly coherent with the geoid, to first order an isostationally compensated lithosphere cut by major E-W fracture zones accounts for most of the power in the high degree and other SEASAT geoid in the Pacific.
Extreme fluctuations in stochastic network coordination with time delays
NASA Astrophysics Data System (ADS)
Hunt, D.; Molnár, F.; Szymanski, B. K.; Korniss, G.
2015-12-01
We study the effects of uniform time delays on the extreme fluctuations in stochastic synchronization and coordination problems with linear couplings in complex networks. We obtain the average size of the fluctuations at the nodes from the behavior of the underlying modes of the network. We then obtain the scaling behavior of the extreme fluctuations with system size, as well as the distribution of the extremes on complex networks, and compare them to those on regular one-dimensional lattices. For large complex networks, when the delay is not too close to the critical one, fluctuations at the nodes effectively decouple, and the limit distributions converge to the Fisher-Tippett-Gumbel density. In contrast, fluctuations in low-dimensional spatial graphs are strongly correlated, and the limit distribution of the extremes is the Airy density. Finally, we also explore the effects of nonlinear couplings on the stability and on the extremes of the synchronization landscapes.
Structural characteristics and tectonics of northeastern Tellus Regio and Meni Tessera
NASA Technical Reports Server (NTRS)
Toermaenen, T.
1992-01-01
The Tellus Regio-Meni Tessera region is an interesting highland area characterized by large areas of complex ridged terrain or tessera terrain. The area was previously studied from the Venera 15/16 data, typical characteristics of complex tessera terrain of Tellus Regio were analyzed, and a formation mechanism was proposed. Apparent depths of compensation of approximately 30-50 km were calculated from Pioneer Venus gravity and topography data. These values indicate predominant Airy compensation for the area. Regional stresses and lithospheric structures were defined from analysis of surface structures, topography, and gravity data. In this work we concentrate on northeastern Tellus Regio and Meni Tessera, which are situated north and west of Tellus Regio. Structural features and relationships are analyzed in order to interpret tectonic history of the area. Study area was divided into three subareas: northeastern Tellus Regio, Meni Tessera, and the deformed plain between them.
Variable beamwidth monopulse feed for Tracking and Data Relay Satellite (TDRS)
NASA Technical Reports Server (NTRS)
Schmidt, R. F.
1974-01-01
The Tracking and Data Relay Satellite with a set of circularly-polarized, amplitude-sensing monopulse patterns suitable for acquiring and tracking user spacecraft at Ku-band (15.0 GHz) is discussed. The possibility of increasing the less than 0.4-degree half-power beamwidth of the data beam to almost 1.0 degree during the acquisition phase is predicated on the use of feeds situated in the first bright-ring of the Airy diffraction structure. A complex-vector simulation equivalent to the Kirchhoff-Kottler or Franz formulations is used to compute transmitted and received field information for a dual-reflector (Cassegrain) antenna configuration in a three-dimensional space.
Amplitude image processing by diffractive optics.
Cagigal, Manuel P; Valle, Pedro J; Canales, V F
2016-02-22
In contrast to the standard digital image processing, which operates over the detected image intensity, we propose to perform amplitude image processing. Amplitude processing, like low pass or high pass filtering, is carried out using diffractive optics elements (DOE) since it allows to operate over the field complex amplitude before it has been detected. We show the procedure for designing the DOE that corresponds to each operation. Furthermore, we accomplish an analysis of amplitude image processing performances. In particular, a DOE Laplacian filter is applied to simulated astronomical images for detecting two stars one Airy ring apart. We also check by numerical simulations that the use of a Laplacian amplitude filter produces less noisy images than the standard digital image processing.
NASA Astrophysics Data System (ADS)
Berry, M. V.
2005-01-01
By applying the technique of uniform asymptotic approximation to the oscillatory integrals representing tsunami wave profiles, the form of the travelling wave far from the source is calculated for arbitrary initial disturbances. The approximations reproduce the entire profiles very accurately, from the front to the tail, and their numerical computation is much faster than that of the oscillatory integrals. For one-dimensional propagation, the uniform asymptotics involve Airy functions and their derivatives; for two-dimensional propagation, the uniform asymptotics involve products of these functions. Separate analyses are required when the initial disturbance is specified as surface elevation or surface velocity as functions of position, and when these functions are even or odd. 'There was an awful rainbow once in heaven' (John Keats, 1820)
Dynamic compensation of Venus's geoid: A comparison with Earth
NASA Technical Reports Server (NTRS)
Kiefer, W. S.; Hager, B. H.; Richards, M. A.
1985-01-01
Unlike Earth, on Venus long wavelength geoid anomalies correlate well with topography. Venus's admittance curve between harmonic degrees 3 and 18 is inconsistent with Airy isostasy but is consistent with dynamic support from convection being the dominant mechanism of compensation on Venus. We model dynamic compensation on Venus using simple flow models which assume a spherically symmetric Newtonian mantle viscosity profile. Preliminary models parameterize the viscosity variation with depth as a 2 layer model with a boundary at 720 km depth. A model in which viscosity in the lower mantle is a factor of 10 lower than in the upper mantle can explain Venus's observed admittance curve for degrees 3 through 18. Dynamic models which include a chemical boundary between the upper and lower mantle do not successfully explain the observed admittance curve, indicating that Venus does not have a chemically layered mantle.
Plouff, Donald
1992-01-01
A residual isostatic gravity map (sheet 2) was prepared so that the regional effect of isostatic compensation present on the Bouguer gravity anomaly map (sheet 1) would be minimized. Isostatic corrections based on the Airy-Heiskanen system (Heiskanen and Vening Meinesz, 1958, p. 135-137) were estimated by using 3-minute topographic digitization and applying the method of Jachens and Roberts (1981). Parameters selected for the isostatic model were 25 km for the normal crustal thickness at sea level, 2.67 g/cm3 for the density of the crust, and 0.4 g/cm3 for the contrast in density between the crust and the upper mantle. These parameters were selected so that the isostatic residual gravity map would be consistent with isostatic residual gravity maps of the adjacent Walker Lake quadrangle (Plouff, 1987) and the state of Nevada (Saltus, 1988c).
Production of isoflavonoids in callus cultures of Pueraria candollei var. mirifica.
Udomsuk, Latiporn; Jarukamjorn, Kanokwan; Tanaka, Hiroyuki; Putalun, Waraporn
2009-01-01
Pueraria candollei Wall. ex Benth. var. mirifica (Airy Shaw & Suvat.) Niyomdham was investigated for callus induction using Murashige and Skoog (MS) medium containing different plant growth regulators. After 8 weeks of culture, 66-100% of leaf or stem explants formed calli. Calli from stem explants cultured on MS medium supplemented with 0.5 mg/l thidiazuron (TDZ) gave the maximum of shoot induction (16%) and the highest level of total isoflavonoids [(50.39 +/- 7.06) mg/g dry wt], which was 7-fold higher than that of the native tuber [(7.04 +/- 0.29) mg/g dry wt]. These results suggest that addition of TDZ to the culture medium markedly enhances the production of isoflavonoids in calli induced from stem explants of P. candollei var. mirifica.
Is Mc Leod's Patent Pending Naturoptic Method for Restoring Healthy Vision Easy and Verifiable?
NASA Astrophysics Data System (ADS)
Niemi, Paul; McLeod, David; McLeod, Roger
2006-10-01
RDM asserts that he and people he has trained can assign visual tasks from standard vision assessment charts, or better replacements, proceeding through incremental changes and such rapid improvements that healthy vision can be restored. Mc Leod predicts that in visual tasks with pupil diameter changes, wavelengths change proportionally. A longer, quasimonochromatic wavelength interval is coincident with foveal cones, and rods. A shorter, partially overlapping interval separately aligns with extrafoveal cones. Wavelengths follow the Airy disk radius formula. Niemi can evaluate if it is true that visual health merely requires triggering and facilitating the demands of possibly overridden feedback signals. The method and process are designed so that potential Naturopathic and other select graduate students should be able to self-fund their higher- level educations from preferential franchising arrangements of earnings while they are in certain programs.
Aharony-Bergman-Jafferis-Maldacena Wilson Loops in the Fermi Gas Approach
NASA Astrophysics Data System (ADS)
Klemm, Albrecht; Mariño, Marcos; Soroush, Masoud
2013-02-01
The matrix model of the Aharony-Bergman-Jafferis-Maldacena theory can be formulated in terms of an ideal Fermi gas with a non-trivial one-particle Hamiltonian. We show that, in this formalism, vacuum expectation values (vevs) of Wilson loops correspond to averages of operators in the statistical-mechanical problem. This makes it possible to calculate these vevs at all orders in 1/N, up to exponentially small corrections, and for arbitrary Chern-Simons coupling, by using the Wentzel- Kramer-Brillouin expansion.We present explicit results for the vevs of 1/6 and the 1/2 Bogomolnyi- Prasad-Sommerfield Wilson loops, at any winding number, in terms of Airy functions. Our expressions are shown to reproduce the low genus results obtained previously in the 't Hooft expansion.
Curved singular beams for three-dimensional particle manipulation.
Zhao, Juanying; Chremmos, Ioannis D; Song, Daohong; Christodoulides, Demetrios N; Efremidis, Nikolaos K; Chen, Zhigang
2015-07-13
For decades, singular beams carrying angular momentum have been a topic of considerable interest. Their intriguing applications are ubiquitous in a variety of fields, ranging from optical manipulation to photon entanglement, and from microscopy and coronagraphy to free-space communications, detection of rotating black holes, and even relativistic electrons and strong-field physics. In most applications, however, singular beams travel naturally along a straight line, expanding during linear propagation or breaking up in nonlinear media. Here, we design and demonstrate diffraction-resisting singular beams that travel along arbitrary trajectories in space. These curved beams not only maintain an invariant dark "hole" in the center but also preserve their angular momentum, exhibiting combined features of optical vortex, Bessel, and Airy beams. Furthermore, we observe three-dimensional spiraling of microparticles driven by such fine-shaped dynamical beams. Our findings may open up new avenues for shaped light in various applications.
Holographic superconductors near the Breitenlohner-Freedman bound
NASA Astrophysics Data System (ADS)
Siopsis, George; Therrien, Jason; Musiri, Suphot
2012-04-01
We discuss holographic superconductors in an arbitrary dimension whose dual black holes have a scalar hair of mass near the Breitenlohner-Freedman bound. We concentrate on low temperatures in the probe limit. We show analytically that when the bound is saturated, the condensate diverges at low temperatures as |ln T|δ, where δ depends on the dimension. This mild divergence was missed in earlier numerical studies. We calculate the conductivity analytically and show that at low temperatures, all poles move toward the real axis. We obtain an increasingly large number of poles which approach the zeroes of the Airy function in 2+1 dimensions and of the Gamma function in 3+1 dimensions. Our analytic results are in good agreement with numerical results whenever the latter are available.
Two-layer interfacial flows beyond the Boussinesq approximation: a Hamiltonian approach
NASA Astrophysics Data System (ADS)
Camassa, R.; Falqui, G.; Ortenzi, G.
2017-02-01
The theory of integrable systems of Hamiltonian PDEs and their near-integrable deformations is used to study evolution equations resulting from vertical-averages of the Euler system for two-layer stratified flows in an infinite two-dimensional channel. The Hamiltonian structure of the averaged equations is obtained directly from that of the Euler equations through the process of Hamiltonian reduction. Long-wave asymptotics together with the Boussinesq approximation of neglecting the fluids’ inertia is then applied to reduce the leading order vertically averaged equations to the shallow-water Airy system, albeit in a non-trivial way. The full non-Boussinesq system for the dispersionless limit can then be viewed as a deformation of this well known equation. In a perturbative study of this deformation, a family of approximate constants of the motion are explicitly constructed and used to find local solutions of the evolution equations by means of hodograph-like formulae.
Mars - Gravity data analysis of the crater Antoniadi
NASA Technical Reports Server (NTRS)
Sjogren, W. L.; Ritke, S. J.
1982-01-01
Topography and gravity information for this 370-km crater are analyzed to determine a depth of compensation with an Airy isostatic model. A least squares fit to the gravity profile gives an estimate of 115 km for the depth of compensation. It is noted that Antoniadi is the only large Martian crater for which both topographic and gravity data are available for analysis. The goal here is to reduce these geophysical data for additional information on the internal structure of Mars. The results show that if Antoniadi had fully isostatically adjusted, the additional mass material would have been about 100 km below the surface. This is regarded as another data point for geophysicists developing the internal structure of Mars.
Transport of inertial anisotropic particles under surface gravity waves
NASA Astrophysics Data System (ADS)
Dibenedetto, Michelle; Koseff, Jeffrey; Ouellette, Nicholas
2016-11-01
The motion of neutrally and almost-neutrally buoyant particles under surface gravity waves is relevant to the transport of microplastic debris and other small particulates in the ocean. Consequently, a number of studies have looked at the transport of spherical particles or mobile plankton in these conditions. However, the effects of particle-shape anisotropy on the trajectories and behavior of irregularly shaped particles in this type of oscillatory flow are still relatively unknown. To better understand these issues, we created an idealized numerical model which simulates the three-dimensional behavior of anisotropic spheroids in flow described by Airy wave theory. The particle's response is calculated using a simplified Maxey-Riley equation coupled with Jeffery's equation for particle rotation. We show that the particle dynamics are strongly dependent on their initial conditions and shape, with some some additional dependence on Stokes number.
The Green function for the BFKL pomeron and the transition to DGLAP evolution
NASA Astrophysics Data System (ADS)
Kowalski, H.; Lipatov, L. N.; Ross, D. A.
2014-06-01
We consider the (process-independent) Green function for the BFKL equation with running coupling, and explain how, within the semi-classical approximation, it is related to Green function of the Airy equation. The unique Green function is obtained from a combination of its required ultraviolet behaviour compatible with asymptotic freedom and an infrared limit phase imposed by the non-perturbative sector of QCD. We show that at sufficiently large gluon transverse momenta the corresponding gluon density matches that of the DGLAP analysis, whereas for relatively small values of the gluon transverse momentum the gluon distribution is sensitive to the Regge poles, whose positions are determined both by the non-perturbative QCD dynamics and physics at large transverse momenta.
IRAN: Interferometric Remapped Array Nulling
NASA Astrophysics Data System (ADS)
Aristidi, E.; Vakili, F.; Schutz, A.; Lanteri, H.; Abe, L.; Belu, A.; Gori, P. M.; Lardière, O.; Lopez, B.; Menut, J. L.; Patru, F.
IRAN is a method of beam-combination in the hypertelescope imaging technique recently introduced by Labeyrie in optical interferometry. We propose to observe the interferometric image in the pupil plane, performing multi-axial pupil plane interferometry. Imaging is performed in a combined pupil-plane where the point-source intensity distribution (PSID) tends towards a pseudo Airy disc for a sufficiently large number of telescopes. The image is concentrated into the limited support of the output pupil of the individual telescopes, in which the object-image convolution relation is conserved. Specific deconvolution algorithms have been developped for IRAN hypertelescope imagery, based upon Lucy-like iterative techniques. We show that the classical (image plane) and IRAN (pupil plane) hypertelescope imaging techniques are equivalent if one uses optical fibers for beam transportation. An application to the VLT/VIDA concept is presented.
NASA Technical Reports Server (NTRS)
Head, James W.
1990-01-01
Processes of crustal formation and evolution are examined, and the role of crustal thickness variation in the production of topography is assessed. Evidence for crustal composition, age, average crustal thickness, and total crustal volume on Venus is reviewed. It is shown that the present crustal volume of Venus is comparable to that of the present earth. The geologic evidence for variations in crustal thickness on Venus are outlined, and specific examples of regions of apparent crustal thickening are assessed. These observations are compared to a simple model of Airy isostasy using global Venus topography and the end-member hypothesis (that the topography of Venus could result solely from crustal thickness variations). Models to account for these observations are proposed.
Experimental observation of sub-Rayleigh quantum imaging with a two-photon entangled source
Xu, De-Qin; Song, Xin-Bing; Li, Hong-Guo; Zhang, De-Jian; Wang, Hai-Bo; Xiong, Jun Wang, Kaige
2015-04-27
It has been theoretically predicted that N-photon quantum imaging can realize either an N-fold resolution improvement (Heisenberg-like scaling) or a √(N)-fold resolution improvement (standard quantum limit) beyond the Rayleigh diffraction bound, over classical imaging. Here, we report the experimental study on spatial sub-Rayleigh quantum imaging using a two-photon entangled source. Two experimental schemes are proposed and performed. In a Fraunhofer diffraction scheme with a lens, two-photon Airy disk pattern is observed with subwavelength diffraction property. In a lens imaging apparatus, however, two-photon sub-Rayleigh imaging for an object is realized with super-resolution property. The experimental results agree with the theoretical prediction in the two-photon quantum imaging regime.
Critical-current diffraction patterns of grain-boundary Josephson weak links
Peterson, R.L.; Ekin, J.W. )
1990-11-01
We discuss the diffraction patterns and other characteristics of the critical current as a function of magnetic field in grain-boundary Josephson barriers. Diffraction patterns occur not just for {ital SIS} junctions but for all types of Josephson links, including {ital SNS} junctions, which may be present at grain boundaries in high-{Tc} superconductors. We discuss the generality of the Airy diffraction pattern, which is expected to characterize grain-boundary barriers in bulk material more accurately than the Fraunhofer pattern. The transport critical-current density in many bulk, granular high-{ital T}{sub {ital c}} superconductors has a power-law dependence on very low magnetic fields, characteristic of averaged diffraction patterns, and cannot be fitted by an exponential magnetic-field dependence, which may result from the material properties of the barriers.
Anomalous behaviors of the Fraunhofer diffraction patterns for a class of partially coherent light.
Pu, Jixiong; Nemoto, Shojiro
2003-02-24
In this paper, we investigate the Fraunhofer diffraction of a class of partially coherent light diffracted by a circular aperture. It is shown that by the illumination of partially coherent light of the special spatial correlation function, the anomalous behaviors of the diffraction patterns are found. We find that the decrease of the spatial coherence of the light in the aperture leads to the drastic changes of the diffraction pattern. Specifically, when the light in the aperture is fully coherent, the diffraction pattern is just an Airy disc. However, as the coherence decreases, the diffraction pattern becomes an annulus, and the radius of the annulus increases with the decrease of the coherence. Flattened annuli can be achieved, when the parameters characterizing the correlation of the partially coherent light are chosen with suitable values. Potential applications of modulating the coherence to achieve desired diffraction patterns are discussed.
Geometrical-numerical approach to diffraction phenomena.
Bosch, S; Ferré-Borrull, J
2001-02-15
The calculation of diffracted fields is considered by means of a geometrical analysis of the incoming wave into semiperiodic zones in the aperture plane, followed by a numerical process for addition of the contributions corresponding to the semiperiodic zones. This general approach constitutes a novel interpretation of diffraction phenomena that permits exact evaluation of the mathematical expressions of diffraction theory and overcomes the limitations of any approximation. The method is illustrated by analysis of two important configuration in optics: the pinhole camera, for which we deduce the optimum radius for imaging, and the diffraction of a spherical converging wave through a circular aperture, from which we determine the limit of the validity of the Fraunhofer approximation (i.e., of the Airy pattern) and the influence of the obliquity factor.
Experimental observation of sub-Rayleigh quantum imaging with a two-photon entangled source
NASA Astrophysics Data System (ADS)
Xu, De-Qin; Song, Xin-Bing; Li, Hong-Guo; Zhang, De-Jian; Wang, Hai-Bo; Xiong, Jun; Wang, Kaige
2015-04-01
It has been theoretically predicted that N-photon quantum imaging can realize either an N-fold resolution improvement (Heisenberg-like scaling) or a √{ N } -fold resolution improvement (standard quantum limit) beyond the Rayleigh diffraction bound, over classical imaging. Here, we report the experimental study on spatial sub-Rayleigh quantum imaging using a two-photon entangled source. Two experimental schemes are proposed and performed. In a Fraunhofer diffraction scheme with a lens, two-photon Airy disk pattern is observed with subwavelength diffraction property. In a lens imaging apparatus, however, two-photon sub-Rayleigh imaging for an object is realized with super-resolution property. The experimental results agree with the theoretical prediction in the two-photon quantum imaging regime.
Generalized Jinc functions and their application to focusing and diffraction of circular apertures.
Cao, Qing
2003-04-01
A family of generalized Jinc functions is defined and analyzed. The zero-order one is just the traditional Jinc function. In terms of these functions, series-form expressions are presented for the Fresnel diffraction of a circular aperture illuminated by converging spherical waves or plane waves. The leading term is nothing but the Airy formula for the Fraunhofer diffraction of circular apertures, and those high-order terms are directly related to those high-order Jinc functions. The truncation error of the retained terms is also analytically investigated. We show that, for the illumination of a converging spherical wave, the first 19 terms are sufficient for describing the three-dimensional field distribution in the whole focal region.
Current density in generalized Fibonacci superlattices under a uniform electric field.
Panchadhyayee, P; Biswas, R; Khan, Arif; Mahapatra, P K
2008-07-09
We present an exhaustive study on tunneling and electrical conduction in an electrically biased GaAs-Al(y)Ga(1-y)As generalized Fibonacci superlattice. The study is based on transfer matrix formalism using an Airy function approach and provides an exact calculation of the current density in the case of quasi-periodic multibarrier systems. The results suggest the use of such quasi-periodic systems in perfect band-pass or band-eliminator (of extremely low width) circuitry. We have clearly demonstrated the resonance-type peaks and negative differential conductivity regimes in such systems. It has also been found that quasi-periodicity favors sharp negative differential conductivity peaks compared to those in periodic superlattices and thus have profound importance in device applications.
Lieb-Liniger gas in a constant-force potential
Jukic, D.; Galic, S.; Buljan, H.; Pezer, R.
2010-08-15
We use Gaudin's Fermi-Bose mapping operator to calculate exact solutions for the Lieb-Liniger model in a linear (constant-force) potential (the constructed exact stationary solutions are referred to as the Lieb-Liniger-Airy wave functions). The ground-state properties of the gas in the wedgelike trapping potential are calculated in the strongly interacting regime by using Girardeau's Fermi-Bose mapping and the pseudopotential approach in the 1/c approximation (c denotes the strength of the interaction). We point out that quantum dynamics of Lieb-Liniger wave packets in the linear potential can be calculated by employing an N-dimensional Fourier transform as in the case of free expansion.
Quantum-classical correspondence for a particle in a homogeneous field
NASA Astrophysics Data System (ADS)
Singh, Sumita; Suman, Smriti P.; Singh, Vijay A.
2016-11-01
The correspondence principle provides a prescription to connect quantum physics to classical. It asserts that the physical quantities evaluated quantum mechanically approach their respective classical values for large quantum numbers. This has been shown for the pedagogically important cases of the particle in a box and a harmonic oscillator. However, a particle in a constant field has a wave function related to the Airy function and has at best been treated numerically. Employing energy eigenstates we obtain the expectation values of the position, the momentum and their moments upto fourth order, rigorously and without resorting to numerical or graphical techniques. We compare them with the corresponding classical values. We also examine the uncertainty product for the system.
Beam-shaping via femtosecond laser-modified optical fibre end faces
NASA Astrophysics Data System (ADS)
Ioannou, A.; Polis, M.; Lacraz, A.; Theodosiou, A.; Kalli, K.
2016-04-01
We present the results of investigations regarding laser micro-structuring of single mode optical fibres by direct access of the fibre end face and compare this with inscription in planar samples. We combine a high numerical aperture objective and femtosecond laser radiation at visible wavelengths to examine the spatial limits of direct writing and structuring at the surface of the optical fibre. We realise a number of interesting devices from one- and two-dimensional grating structures, to Bessel, Airy and vortex beam generators. We show the versatility of this simple but effective inscription method, where we demonstrate classic multiple slit diffraction patterns and patterns for non-diffracting beams, confirming that the flexible direct write method using femtosecond lasers can be to produce binary masks that can lead to beam shaping using a method that is applicable to all types of planar samples and through fine control of laser parameters to multi-mode and singlemode optical fibres.
Enhanced Photoacoustic Beam Profiling of Pulsed Lasers
NASA Astrophysics Data System (ADS)
González, M.; Santiago, G.; Paz, M.; Slezak, V.; Peuriot, A.
2013-09-01
An improved version of a photoacoustic beam profiler of pulsed lasers is presented. The new model resorts to high-bandwidth condenser microphones to register higher-order, excited acoustic modes, thus enabling more accurate profiling. In addition, Xe was used as a buffer gas since its high atomic weight further reduces the eigenfrequencies. Furthermore, a new gas-handling system makes up for some deficiencies found in the first model. The system was calibrated using the Airy pattern generated with a pinhole illuminated by a frequency-doubled Nd:YAG laser that excited traces. Once calibrated, the beam profile of a TEA laser was obtained, using ethylene as the absorbing species. This profiler returns more accurate profiles than thermal paper.
Three-dimensional coherence of light speckles: Experiment
Magatti, D.; Gatti, A.; Ferri, F.
2009-05-15
We provide an experimental detailed study of the three-dimensional coherence properties of light speckles produced by different tunable pseudothermal sources. Our findings confirm the theoretical prediction of the companion article [A. Gatti et al., Phys. Rev. A 78, 063806 (2008)], according to which the longitudinal coherence of the speckles is ruled by ordinary diffraction laws only in the deep-Fresnel zone close to the source, deviates from this behavior in the Fresnel zone, and tends to become infinite when approaching the Fraunhofer zone. A quantitative comparison with theory is presented for Gaussian speckles in all the three regimes and for Airy speckles in the deep-Fresnel zone. Potential applications to three-dimensional imaging techniques are briefly discussed.
Mid-pacific mountains revisited
NASA Astrophysics Data System (ADS)
Kroenke, Loren W.; Kellogg, James N.; Nemoto, Kenji
1985-06-01
The Mid-Pacific Mountains are guyots whose volcanic pedestals have been constructed on a broad basement plateau, the flanks of which are downfaulted. Edifice construction may have been controlled by an orthogonal system of intersecting faults trending roughly ENE and NNW. Low amplitude gravity anomalies observed over the Mid-Pacific Mountains indicate complete Airy-Heiskanen isostatic compensation, crustal thickening, and eruption on thin elastic lithosphere. Tholeiites of the Mid-Pacific Mountains resemble lavas of Iceland and the Galapagos Islands. The orthogonal fault system, low gravity anomalies, and lava chemistry of the Mid-Pacific Mountains can be explained by eruption on or near a great ENE-trending rift system.
Further insight into the tunneling contribution to the vibrational relaxation of NO in Ar.
Dashevskaya, E I; Litvin, I; Nikitin, E E; Troe, J
2015-04-28
Tunneling corrections to Landau-Zener rate coefficients for the vibrational relaxation NO(X(2)Π, v = 1) + Ar → NO(X(2)Π, v = 0) + Ar between 300 and 2000 K are determined employing ab initio potential energy surfaces calculated by the code provided by Alexander [J. Chem. Phys. 111, 7426 (1999)]. The calculations use a reaction coordinate approach and lead to vibronically nonadiabatic transition probabilities within the generalized Airy approximation as extended to the WKB underbarrier Landau-Lifshitz limit. The calculations confirm experimental evidence for an onset of major tunneling contributions to the relaxation rate at temperatures below about 900 K and rationalize large tunneling contributions at 300 K. These effects increase the rate coefficients by several orders of magnitude over the uncorrected Landau-Zener values and remove the large gap between the latter and experimental results.
The control net of Mars - May 1977. [from Viking lander spacecraft radio tracking data
NASA Technical Reports Server (NTRS)
Davies, M. E.
1978-01-01
The development of planet-wide control nets of Mars is reviewed, and the May 1977 update is described. This updated control net was computed by means of a large single-block analytical triangulation incorporating the new direction of the spin axis and the new rotation rate of Mars, as determined from radio tracking data provided by the Viking lander spacecraft. The analytical triangulation adjusts for planimetric control only (areocentric latitude and longitude) and for the camera orientation angles. Most of the areocentric radii at the control points were interpolated from radio occultation measurements, but a few were determined photogrammetically, and a substantial number were derived from elevation contours on the 1976 USGS topographic series of Mars maps. A value of V, measured from Mars' vernal equinox along the equator to the prime meridian (Airy-0) is presented.
Bending light via adiabatic optical transition in longitudinally modulated photonic lattices
Han, Bin; Xu, Lei; Dou, Yiling; Xu, Jingjun; Zhang, Guoquan
2015-01-01
Bending light in a controllable way is desired in various applications such as beam steering, navigating and cloaking. Different from the conventional way to bend light by refractive index gradient, transformation optics or special beams through wavefront design such as Airy beams and surface plasmons, we proposed a mechanism to bend light via resonant adiabatic optical transition between Floquet-Bloch (FB) modes from different FB bands in longitudinally modulated photonic lattices. The band structure of longitudinally modulated photonic lattices was calculated by employing the concept of quasi-energy based on the Floquet-Bloch theory, showing the existence of band discontinuities at specific resonant points which cannot be revealed by the coupled-mode theory. Interestingly, different FB bands can be seamlessly connected at these resonant points in longitudinally modulated photonic lattices driven by adiabatically varying the longitudinal modulation period along the propagation direction, which stimulates the adiabatic FB mode transition between different FB bands. PMID:26511890
The far field diffraction pattern for corner reflectors with complex reflection coefficients
NASA Technical Reports Server (NTRS)
Chang, R. F.; Currie, D. G.; Alley, C. O.; Pittman, M. E.
1970-01-01
The far field diffraction pattern of a geometrically perfect corner reflector is examined analytically for normally incident monochromatic light. The states of polarization and the complex amplitudes of the emerging light are expressed through transformation matrices in terms of those of the original incident light for each sextant of the face in a single coordinate system. The analytic expression of the total diffraction pattern is obtained for a circular face. This expression consists of three component functions in addition to the basic Airy function. The coefficient of each function is expressed in terms of complex coefficients of reflectance of the reflecting surface. Some numerical results for different reflecting surfaces, including total internal reflection, are presented. The iso-intensity contours of the diffraction pattern evaluated from the analytical expressions for an uncoated solid corner reflector are also presented along with the photographs of the pattern.
Laser line shape and spectral density of frequency noise
Stephan, G.M.; Blin, S.; Besnard, P.; Tam, T.T.; Tetu, M.
2005-04-01
Published experimental results show that single-mode laser light is characterized in the microwave range by a frequency noise which essentially includes a white part and a 1/f (flicker) part. We theoretically show that the spectral density (the line shape) which is compatible with these results is a Voigt profile whose Lorentzian part or homogeneous component is linked to the white noise and the Gaussian part to the 1/f noise. We measure semiconductor laser line profiles and verify that they can be fit with Voigt functions. It is also verified that the width of the Lorentzian part varies like 1/P where P is the laser power while the width of the Gaussian part is more of a constant. Finally, we theoretically show from first principles that laser line shapes are also described by Voigt functions where the Lorentzian part is the laser Airy function and the Gaussian part originates from population noise.
Refractive beam shapers for focused laser beams
NASA Astrophysics Data System (ADS)
Laskin, Alexander; Laskin, Vadim; Ostrun, Aleksei
2016-09-01
Focusing of laser radiation is most often used approach in various industrial micromachining applications like scribing, PCB drilling, and is important in scientific researches like laser heating in geophysics experiments with diamond anvil cells (DAC). Control of intensity distribution in focal spot is important task since optimum intensity profiles are rather flat-top, doughnut or "inverse-Gauss" than typical for lasers Gaussian profile. Because of high intensity of modern CW and pulsed lasers it is advisable to use refractive beam shaping optics with smooth optical surfaces providing high radiation resistance. Workable optical solutions can be built on the base of diffraction theory conclusion that flat-top intensity profile in focal plane of a lens is created when input beam has Airy-disk intensity distribution. It is suggested to apply refractive beam shapers converting, with minimum wavefront deformation, Gaussian profile of TEM00 beam to a beam with Airy disk intensity distribution, thereby optimizing conditions of interference near the focal plane of a lens after the beam shaper and providing flat-top, doughnut, "inverse-Gauss" profiles. This approach allows operation with CW and ultra-short pulse lasers, using F-theta lenses and objectives, mirror scanners, provides extended depth of field similar to Rayleigh length of comparable TEM00 beam, easy integration in industrial equipment, simple adjustment procedure and switching between profiles, telescope and collimator implementations. There will be considered design basics of beam shapers, analysis of profile behaviour near focal plane, examples of implementations in micromachining systems and experimental DAC setups, results of profile measurements and material processing.
Crustal-thickness variations in the central Andes
NASA Astrophysics Data System (ADS)
Beck, Susan L.; Zandt, George; Myers, Stephen C.; Wallace, Terry C.; Silver, Paul G.; Drake, Lawrence
1996-05-01
We estimated the crustal thickness along an east-west transect across the Andes at lat 20°S and along a north-south transect along the eastern edge of the Altiplano from data recorded on two arrays of portable broadband seismic stations (BANJO and SEDA). Waveforms of deep regional events in the downgoing Nazca slab and teleseismic earthquakes were processed to isolate the P-to-S converted phases from the Moho in order to compute the crustal thickness. We found crustal-thickness variations of nearly 40 km across the Andes. Maximum crustal thicknesses of 70 74 km under the Western Cordillera and the Eastern Cordillera thin to 32 38 km 200 km east of the Andes in the Chaco Plain. The central Altiplano at 20°S has crustal thicknesses of 60 to 65 km. The crust also appears to thicken from north (16°S, 55 60 km) to south (20°S, 70 74 km) along the Eastern Cordillera. The Subandean zone crust has intermediate thicknesses of 43 to 47 km. Crustal-thickness predictions for the Andes based on Airy-type isostatic behavior show remarkable overall correlation with observed crustal thickness in the regions of high elevation. In contrast, at the boundary between the Eastern Cordillera and the Subandean zone and in the Chaco Plain, the crust is thinner than predicted, suggesting that the crust in these regions is supported in part by the flexural rigidity of a strong lithosphere. With additional constraints, we conclude that the observation of Airy-type isostasy is consistent with thickening associated with compressional shortening of a weak lithosphere squeezed between the stronger lithosphere of the subducting Nazca plate and the cratonic lithosphere of the Brazilian craton.
The vibrational relaxation of NO in Ar: tunneling in a curve-crossing mechanism.
Dashevskaya, E I; Nikitin, E E; Troe, J
2015-01-07
Experimental data for the vibrational relaxation NO(X(2)Π, v = 1) + Ar → NO(X(2)Π, v = 0) + Ar between 300 and 2000 K are analyzed. The measured rate coefficients k10 greatly exceed Landau-Teller values (LT)k10. This observation can be attributed to a mechanism involving curve-crossing of the (A'', v = 1) and (A', v = 0) vibronic states of the collision system. At high temperatures, the rate coefficients k10 are well represented by the thermally averaged Landau-Zener rate constant (LZ)k10 with an apparent Arrhenius activation energy Ea/kB near 4500 K. At intermediate temperatures, around T = 900 K, the measured k10 values are a factor of two higher than the extrapolated (LZ)k10 values. This deviation is attributed to tunneling in nonadiabatic curve-crossing transitions, which are analyzed within the Airy approximation (linear model for crossing diabatic curves) and an effective mass approach. This suggests a substantial contribution of hindered rotation of NO to the nonadiabatic perturbation. The extrapolation of the Airy probabilities to even lower temperatures (by the Landau-Lifshitz WKB tunneling expression for simple nonlinear model potentials) indicates a further marked increase of the tunneling contribution beyond the extrapolated (LZ)k10. Near 300 K, the k10 can be two to three orders of magnitude higher than the extrapolated (LZ)k10. This agrees with the limited available experimental data for NO-Ar relaxation near room temperature.
NASA Astrophysics Data System (ADS)
Singer, Werner; Gausa, Michael; Latteck, Ralph; Honary, Farideh; Friedrich, Martin
Electron densities of the lower ionosphere are estimated using the Saura MF Doppler radar data since summer 2003. The radar is located near Andenes, Norway (69.3N, 16.0E) and operates at 3.17 MHz. The experiment utilizes partial reflections of ordinary and extraordinary component waves from scatterers in the altitude range 50-90 km to estimate electron number densities from differential absorption (DAE) and differential phase (DPE) measurements. Height profiles of electron density are obtained between about 55 km and 90 km with a height resolution of 1 km. The diurnal and seasonal variability of electron densities as well as the response of D-region electron densities to solar activity storms, solar proton events, and geomagnetic disturbances have been estimated. The imaging riometer AIRIS near Andenes monitors excessive radio wave absorption due to precipitating energetic particles. The vertical beam of the Saura MF radar coincides with the volume observed with the vertical AIRIS beam. The data from both systems allow the verification of the lower part of the neural network-based ionospheric model for the Auroral zone IMAZ-2. The model provides electron density profiles between 60 and 140 km for a given riometer absorption, time, and ionospheric state. It is based on electron density profiles from EISCAT UHF/VHF radars for altitudes above about 85 km and high-latitude rocket measurements, but the data below 70 km is almost exclusively due to sounding rockets. Comparisons of the IMAZ model with measured electron density profiles are discussed for different levels of solar activity and various particle precipitation events.
Crustal-thickness variations in the central Andes
Beck, S.L.; Myers, S.C.; Wallace, T.C.; Zandt, G. |; Silver, P.G.; Drake, L.
1996-05-01
We estimated the crustal thickness along an east-west transect across the Andes at lat 20{degree}S and along a north-south transect along the eastern edge of the Altiplano from data recorded on two arrays of portable broadband seismic stations (BANJO and SEDA). We found crustal-thickness variations of nearly 40 km across the Andes. Maximum crustal thicknesses of 70-74 km under the Western Cordillera and the Eastern Cordillera thin to 32-38 km 200 km east of the Andes in the Chaco Plain. The central Altiplano at 20{degree}S has crustal thicknesses of 60 to 65 km. The crust also appears to thicken from north (16{degree}S, 55-60 km) to south (20{degree}S, 70-74 km) along the Eastern Cordillera. The Subandean zone crust has intermediate thicknesses of 43 to 47 km. Crustal-thickness predictions for the Andes based on Airy-type isostatic behavior show remarkable overall correlation with observed crustal thickness in the regions of high elevation. In contrast, at the boundary between the Eastern Cordillera and the Subandean zone and in the Chaco Plain, the crust is thinner than predicted, suggesting that the crust in these regions is supported in part by the flexural rigidity of a strong lithosphere. With additional constraints, we conclude that the observation of Airy-type isostasy is consistent with thickening associated with compressional shortening of a weak lithosphere squeezed between the stronger lithosphere of the subducting Nazca plate and the cratonic lithosphere of the Brazilian craton. 26 refs., 4 figs.
NASA Astrophysics Data System (ADS)
2011-07-01
Chairman:Jozef Spałek (Kraków) Program Committee:Stephen Blundell (Oxford), J Michael D Coey (Dublin), Dominique Givord (Grenoble), Dariusz Kaczorowski (Wrocław), Roman Micnas (Poznań), Marek Przybylski (Halle), Ludiwig Schultz (Dresden), Vladimir Sechovsky (Prague), Jozef Spałek (Kraków), Henryk Szymczak (Warszawa), Manuel Vázquez (Madrid) Publication Committee:Dariusz Kaczorowski, Robert Podsiadły, Jozef Spałek, Henryk Szymczak, Andrzej Szytuła Local committee:Maria Bałanda, Anna Majcher, Robert Podsiadły, Michał Rams, Andrzej Ślebarski, Krzysztof Tomala Editors of the Proceedings:Jozef Spałek, Krzysztof Tomala, Danuta Goc-Jagło, Robert Podsiadły, Michał Rams, Anna Majcher Plenary, semi-plenary and tutorial speakers:Ernst Bauer (Wien)Stephen Blundell (Oxford)J Michael D Coey (Dublin)Russell P Cowburn (London)Burkard Hillebrands (Kaiserslautern)Claudine Lacroix (Grenoble)Lluís Mañosa (Barcelona)María del Carmen Muñoz (Madrid)Bernard Raveau (Caen)Pedro Schlottmann (Tallahassee)Frank Steglich (Dresden)Oliver Waldmann (Freiburg) Invited speakers within symposia: R Ahuja (Uppsala)A Kirilyuk (Nijmegen) M Albrecht (Vienna)L Theil Kuhn (Roskilde) K Bärner (Göttingen)J Liu (Dresden) U Bovensiepen (Duisburg)G Lorusso (Modena) V Buchelnikov (Chelyabinsk)M M Maska (Katowice) B Chevalier (Bordeaux)Y Mukovskii (Moscow) O Chubykalo-Fesenko (Madrid)M Pannetier-Lecoeur (Saclay) A V Chumak (Kaiserslautern)G Papavassiliou (Athens) J M D Coey (Dublin)K R Pirota (Campinas) B Dabrowski (DeKalb)P Przyslupski (Warszawa) S Das (Aveiro)M Reiffers (Košice) A del Moral (Zaragoza)K Sandeman (London) V E Demidov (Muenster)D Sander (Halle) B Djafari-Rouhani (Lille)M Sawicki (Sendai/Warsaw) H A Dürr (Menlo Park)J Schaefer (Würzburg) J Fassbender (Dresden)H Schmidt (Wetzikon) J Fontcuberta (Barcelona)J Spałek (Kraków) V Garcia (Orsay)L Straka (Helsinki) J N Gonçalves (Aveiro)A Szewczyk (Warszawa) M E Gruner (Duisburg)Y Taguchi (Wako) G Gubbiotti (Perugia)A Thiaville
Progress report of southeastern monazite exploration, 1952
Overstreet, W.C.; Theobald, P.K.; White, A.M.; Cuppels, N.P.; Caldwell, D.W.; Whitlow, J.W.
1953-01-01
Reconnaissance of placer monazite during the field season of 1952 covered 6,600 square miles drained by streams in the western Piedmont of Virginia 5 North Carolina, South Carolina,, and Georgia. Emphasis during this investigation was placed on the area between the Savannah River at the border of South Carolina and Georgia and the Catawba River in North Carolina because it contains most of the placers formerly mined for monaziteo Four other areas along the strike of the monazite-bearing crystalline rocks were also studied, They center around Mt. Airy, N.C., Athens, Ga. Griffin, Ga. and LaGrange, Ga. In the Savannah River Catawba River district, studies indicate that even the highest grade stream deposits of more than 10 million cubic yards of alluvium contain less than 1 pound of monazite per cubic yard. The average grade of the better deposits is about 0 0 5 pound of monazite per cubic yard. Only trace amounts of niobium, tantalum, and tin have been detected in the placers. Tungsten is absent. Locally gold adds a few cents per cubic yard to the value of placer ground. The best deposits range in size from 1 to 5 million cubic yards and contain 1 to 2 pounds of monazite to the cubic yard. Hundreds of placers smaller than 1 million cubic yards exceed 2 pounds of monazite to the cubic yard and locally attain an average of 10 pounds Monazite deposits around Athens, Ga., are similar to the smaller deposits in the central part of the Savannah River - Catawba River district. A few small very low-grade monazite placers were found near Mt. Airy, N.C., Griffin, Ga., and LaGrange Ga., but they are of no economic value. The larger the flood plain and the farther it lies from the source of the stream, the lower is the monazite content of the sediment. Monazite cannot be profitably mined .from the crystalline rocks in the five areas. The alluvial placers are in stream sediments of post-Wisconsin age. Some pre-Wisconsin terrace gravel of small areal extent is exposed but it
Analysis of the seismic wavefield in the Moesian Platform (Bucharest area)
NASA Astrophysics Data System (ADS)
-Florinela Manea, Elena; Hobiger, Manuel-Thomas; Michel, Clotaire; Fäh, Donat; -Ortanza Cioflan, Carmen
2016-04-01
Bucharest is located in the center of the Moesian platform, in a large and deep sedimentary basin (450 km long, 300 km wide and in some places up to 20 km depth). During large earthquakes generated by the Vrancea seismic zone, located approximately 140 km to the North, the ground motion recorded in Bucharest area is characterized by predominant long periods and large amplification. This phenomenon has been explained by the influence of both source mechanism (azimuth and type of incident waves) and mechanical properties of the local structure (geological layering and geometry). The main goal of our study is to better characterize and understand the seismic wave field produced by earthquakes in the area of Bucharest. We want to identify the contribution of different seismic surface waves, such as the ones produced at the edges of the large sedimentary basin or multipath interference waves (Airy phases of Love and Rayleigh waves) to the ground motion. The data from a 35 km diameter array (URS experiment) installed by the National Institute for Earth Physics during 10 months in 2003 and 2004 in the urban area of Bucharest and adjacent zones was used. In order to perform the wave field characterization of the URS array, the MUSIQUE technique was used. This technique consists in a combination of the classical MUSIC and the quaternion-MUSIC algorithms and analyzes the three-component signals of all sensors of a seismic array together in order to analyze the Love and Rayleigh wave dispersion curves as well as the Rayleigh wave ellipticity curve. The analysis includes 20 regional earthquakes with Mw >3 and 5 teleseismic events with Mw> 7 that have enough energy at low frequency (0.1 - 1 Hz), i.e. in the resolution range of the array. For all events, the greatest energy is coming from the backazimuth of the source and the wave field is dominated by Love waves. The results of the array analyses clearly indicate a significant scattering corresponding to 2D or 3D effects in the
NASA Technical Reports Server (NTRS)
Allison, Michael; McEwen, Megan
1999-01-01
The accurate determination of the Mars pole vector derived from Pathfinder and Viking Lander radio data, together with the VSOP87 representation of planetary orbits, have been applied to a new evaluation of the right ascension of the "fictitious mean sun" (FMS) at Mars. With DELTA t (sub J2000) the elapsed time in days from the J2000 epoch (J.D.2451545.0 (sup TT), alpha FMS = 270 degrees.3863 + 0.52403840(degrees/d) (raised dot) DELTA T (sub j2000) - 4 x 10 (exp -13) (degrees/d (sup 2)) (raised dot) DELTA t (sup 2) (sub J2000) represents a best least-squares quadratic fit of the FMS, including aberration, to each instance of the four equinox and solstice passages for each of 134 Mars orbits spanning the calendar years 1874-2127. The implied tropical orbit period for Mars, 686.9726 (sup d), closely agrees with the recent evaluations. Together with the Pathfinder radio determination of the Mars sidereal rotation, the derived FMS rate corresponds to a mean solar day (or "sol") of 1.027491251 (sup d). The new FMS determination would serve to define the Mean Solar Time at Mars to the nearest tenth-second, according to historical conventions originally established for terrestrial time keeping, once the Mars prime meridian defined by the crater Airy-O is navigated to the same accuracy. For convenient reference to current epochs, 2000 Jan 06 00:00 UTC (= MJD 51549.000 (sup UTC)) corresponds to a coincidence of (alpha (sub FMS)) and the rotation angle of the crater Airy-O measured with respect to the Mars equinox (i.e. "mean solar midnight" on the planet's prime meridian), to within the current uncertainty of several seconds in the locational definition of the planet's cartographic grid. As a further result of the analysis, the consistently derived Mars obliquity of date is epsilon = 25 degrees.192 + 3.45 x l0 (exp -7)(degrees/d)(raised dot) DELTA t (sub J2000). An improved analytic recipe for the calculation of the solar areocentric longitude (L (sub s)) of Mars to an
NASA Astrophysics Data System (ADS)
Maruyama, Takashi; Yusupov, Kamil; Akchurin, Adel
2015-04-01
It is well known that atmospheric waves excited by intense earthquakes induce ionospheric disturbances. At remote distances greater than ~500 km, Rayleigh waves are the major source of infrasounds that propagate upward in the atmosphere. Acoustic waves interact with the ionospheric plasma through collision between neutral particles and ions. Ionospheric disturbances caused by Rayleigh waves near the low frequency part of the Airy phase (a period of several minutes) are detected as a change in the total electron content since the wavelength of induced acoustic waves in the thermosphere is comparable to the ionospheric slab thickness. On the other hand, Rayleigh waves near the high frequency part of the Airy phase (a period of several tens of seconds) cause distortion of ionogram traces characterized by a multiple cusp signature (MCS). The vertical separation of the ledge corresponding to each cusp is the wavelength of the infrasound in the thermosphere. Thus, the MCS ionogram is considered to be a snapshot of the wave that propagates upward. We conducted rapid run operation of ionosonde with a frame rate of 1 min at Kazan, Russia. After the 2010 M8.8 Chile earthquake (epicentral distance was 15,162 km), ionospheric disturbances showing MCSs on ionograms were observed for several tens of minutes. The sound speed calculated by a model was 500~700 m/s at the height of the bottomside ionosphere and wavefronts should propagate 30~42 km upward during the intervals of ionograms, which is smaller than the bottomside depth of the ionosphere. The seismogram obtained at Obninsk near Moscow, Russia (epicentral distance was 14,369 km) recorded Rayleigh waves with a period of ~17 s responsible for the ionospheric disturbances showing MCS, when the plot was shifted by the time corresponding to the difference of epicentral distances between the two locations by assuming a Rayleigh wave speed of 3 km/s. The vertical wavelength of the acoustic waves launched by the Rayleigh waves was
On-going scientific and development projects involving rare-isotope beams at ATLAS
NASA Astrophysics Data System (ADS)
Kay, Benjamin
2016-09-01
The ATLAS Facility, located at Argonne National Laboratory, provides both radioactive and stable ion beams at energies around the Coulomb barrier (<20 MeV/u). Beams of this nature facilitate measurements related to nuclear structure, astrophysics, reactions, fundamental symmetries, and beyond. Along with the ability to accelerate nearly all stable ions from protons to Uranium, the facility also holds the capability to produce radioactive beams using the two-accelerator method, an in-flight production facility, or through the collection of spontaneous fission fragments at the CARIBU facility. The in-flight technique, in particular, is utilized to produce short-lived beams that are typically one to two-nucleons away from stability, and lighter than mass 40. The CARIBU facility, however, provides access to very neutron-rich isotopes, ranging from the vicinity of doubly-magic 132Sn, to regions of large deformation near A 150 . CARIBU beams are available in both stopped and re-accelerated fashions, and therefore, measurement techniques involving trapping or stopping of the ions, as well as reactions requiring beam energies at or beyond the Coulomb barrier, are possible. In this presentation, highlights from various scientific results which have hinged on radioactive beams produced at ATLAS are to be shown. Also, introductions to, and descriptions of, the on-going technical initiatives aimed at enhancing the radioactive ion-beam production at ATLAS will be given. Finally, exciting future avenues for rare-isotope research, made possible because of the new initiative, is to be discussed. For example, installation of an electron beam ion source (EBIS) has recently been completed to increase both the purity and intensities of re-accelerated CARIBU beams. In addition, expansion of the isotopes produced in-flight, both mass and isospin, is going to occur with the construction of a dedicated separator, AIRIS. AIRIS is designed to highly suppress the intense un-reacted primary
Scattering and the Point Spread Function of the New Generation Space Telescope
NASA Technical Reports Server (NTRS)
Schreur, Julian J.
1996-01-01
Preliminary design work on the New Generation Space Telescope (NGST) is currently under way. This telescope is envisioned as a lightweight, deployable Cassegrain reflector with an aperture of 8 meters, and an effective focal length of 80 meters. It is to be folded into a small-diameter package for launch by an Atlas booster, and unfolded in orbit. The primary is to consist of an octagon with a hole at the center, and with eight segments arranged in a flower petal configuration about the octagon. The comers of the petal-shaped segments are to be trimmed so that the package will fit atop the Atlas booster. This mirror, along with its secondary will focus the light from a point source into an image which is spread from a point by diffraction effects, figure errors, and scattering of light from the surface. The distribution of light in the image of a point source is called a point spread function (PSF). The obstruction of the incident light by the secondary mirror and its support structure, the trimmed corners of the petals, and the grooves between the segments all cause the diffraction pattern characterizing an ideal point spread function to be changed, with the trimmed comers causing the rings of the Airy pattern to become broken up, and the linear grooves causing diffraction spikes running radially away from the central spot, or Airy disk. Any figure errors the mirror segments may have, or any errors in aligning the petals with the central octagon will also spread the light out from the ideal point spread function. A point spread function for a mirror the size of the NGST and having an incident wavelength of 900 nm is considered. Most of the light is confined in a circle with a diameter of 0.05 arc seconds. The ring pattern ranges in intensity from 10(exp -2) near the center to 10(exp -6) near the edge of the plotted field, and can be clearly discerned in a log plot of the intensity. The total fraction of the light scattered from this point spread function is called
How predictable is the anomaly pattern of the Indian summer rainfall?
NASA Astrophysics Data System (ADS)
Li, Juan; Wang, Bin
2016-05-01
Century-long efforts have been devoted to seasonal forecast of Indian summer monsoon rainfall (ISMR). Most studies of seasonal forecast so far have focused on predicting the total amount of summer rainfall averaged over the entire India (i.e., all Indian rainfall index-AIRI). However, it is practically more useful to forecast anomalous seasonal rainfall distribution (anomaly pattern) across India. The unknown science question is to what extent the anomalous rainfall pattern is predictable. This study attempted to address this question. Assessment of the 46-year (1960-2005) hindcast made by the five state-of-the-art ENSEMBLE coupled dynamic models' multi-model ensemble (MME) prediction reveals that the temporal correlation coefficient (TCC) skill for prediction of AIRI is 0.43, while the area averaged TCC skill for prediction of anomalous rainfall pattern is only 0.16. The present study aims to estimate the predictability of ISMR on regional scales by using Predictable Mode Analysis method and to develop a set of physics-based empirical (P-E) models for prediction of ISMR anomaly pattern. We show that the first three observed empirical orthogonal function (EOF) patterns of the ISMR have their distinct dynamical origins rooted in an eastern Pacific-type La Nina, a central Pacific-type La Nina, and a cooling center near dateline, respectively. These equatorial Pacific sea surface temperature anomalies, while located in different longitudes, can all set up a specific teleconnection pattern that affects Indian monsoon and results in different rainfall EOF patterns. Furthermore, the dynamical models' skill for predicting ISMR distribution primarily comes primarily from these three modes. Therefore, these modes can be regarded as potentially predictable modes. If these modes are perfectly predicted, about 51 % of the total observed variability is potentially predictable. Based on understanding the lead-lag relationships between the lower boundary anomalies and the
Noninteracting fermions at finite temperature in a d -dimensional trap: Universal correlations
NASA Astrophysics Data System (ADS)
Dean, David S.; Le Doussal, Pierre; Majumdar, Satya N.; Schehr, Grégory
2016-12-01
We study a system of N noninteracting spinless fermions trapped in a confining potential, in arbitrary dimensions d and arbitrary temperature T . The presence of the confining trap breaks the translational invariance and introduces an edge where the average density of fermions vanishes. Far from the edge, near the center of the trap (the so-called "bulk regime"), where the fermions do not feel the curvature of the trap, physical properties of the fermions have traditionally been understood using the local density (or Thomas-Fermi) approximation. However, these approximations drastically fail near the edge where the density vanishes and thermal and quantum fluctuations are thus enhanced. The main goal of this paper is to show that, even near the edge, novel universal properties emerge, independently of the details of the shape of the confining potential. We present a unified framework to investigate both the bulk and the edge properties of the fermions. We show that for large N , these fermions in a confining trap, in arbitrary dimensions and at finite temperature, form a determinantal point process. As a result, any n -point correlation function, including the average density profile, can be expressed as an n ×n determinant whose entry is called the kernel, a central object for such processes. Near the edge, we derive the large-N scaling form of the kernels, parametrized by d and T . In d =1 and T =0 , this reduces to the so-called Airy kernel, that appears in the Gaussian unitary ensemble (GUE) of random matrix theory. In d =1 and T >0 we show a remarkable connection between our kernel and the one appearing in the (1 +1 )-dimensional Kardar-Parisi-Zhang equation at finite time. Consequently, our result provides a finite-T generalization of the Tracy-Widom distribution, that describes the fluctuations of the position of the rightmost fermion at T =0 , or those of the largest single-fermion momentum. In d >1 and T ≥0 , while the connection to GUE no longer holds
Method of Global Transformation and its Role in Turning Point Problems
NASA Astrophysics Data System (ADS)
McArthur, Raymond Peter
In this monograph, we introduce an asymptotic technique which can be used to obtain uniform asymptotic solutions of certain types of second-order, linear ordinary differential equations which may arise in wave propagation problems in non-homogeneous media. Of particular interest are those physical phenomenon which lead to simple and non-simple turning point problems where the nature of the fundamental solution undergoes a sudden metamorphosis of character at the turning point. We begin by giving a few examples which under certain conditions admit turning point behavior. The general theory of the method of global transformation is then introduced. After giving a preview of the method, a historical account of the idea of comparison equation is given which systematically leads to our generalization of the concept. Next, we transform the original problem to an appropriate comparison equation using new dependent and independent variables. This leads to a non-linear differential equation in the transformed coordinate. This non-linear equation has the property that its solution can be determined in the form of uniformly convergent series. We take advantage of this unique property and develop an iterative technique to obtain the solution of the original problem. In applying our iterative technique, the zero -order solution so obtained reproduces exactly the dominant solutions as given by WKBJ or method of stationary phase. We then obtain the higher-order solutions of the non-linear equation which yield new transformations. Use of these transformations in conjunction with the comparison equation give us higher-order correction terms in the asymptotic series solution of the original problem. These higher -order terms correspond to the higher-order terms which one would obtain by using the method of steepest descent. After giving an account of the well-known connection problem using our zero-order solution of the Airy equation, we conclude by giving an illustrative example of
A 10 km-resolution synthetic Venus gravity field model based on topography
NASA Astrophysics Data System (ADS)
Li, Fei; Yan, Jianguo; Xu, Luyuan; Jin, Shuanggen; Rodriguez, J. Alexis P.; Dohm, James H.
2015-02-01
A high resolution gravity field model is extremely important in the exploration of Venus. In this paper, we present a 3-dimensional Venus gravity field VGM2014 constructed by using the latest gravity and topography models, residual terrain model (RTM) and the Airy-Heiskanen isostatic compensation model. The VGM2014 is the first 10 km scale Venus gravity field model; the final results are representations of the 3-dimensional surface gravity accelerations and gravity disturbances for Venus. We found that the optimal global compensation depth of Venus is about 60 km, and the crustal density is potentially less than the commonly accepted value of 2700-2900 kg m-3. This model will be potentially beneficial for the precise orbit determination and landing navigation of spacecraft around Venus, and may be utilized as a priori model for Venus gravity field simulation and inversion studies. The VGM2014 does not incorporate direct gravity information beyond degree 70 and it is not recommended for small-scale geophysical interpretation.
Universality of the topological string at large radius and NS-brane resurgence
NASA Astrophysics Data System (ADS)
Couso-Santamaría, Ricardo
2017-02-01
We show that there is a natural universal limit of the topological string free energies at the large radius point. The new free energies keep a nonholomorphic dependence on the complex structure moduli space and their functional form is the same for all Calabi-Yau geometries, compact and noncompact alike. The asymptotic nature of the free energy expansion changes in this limit due to a milder factorial growth of its coefficients, and this implies a transseries extension with instanton effects in exp (- 1/g_s^2), of NS-brane type, rather than exp (-1/g_s), of D-brane type. We show a relation between the instanton action of NS-brane type and the volume of the Calabi-Yau manifold which points to a possible interpretation in terms of NS5-branes. A similar rescaling limit has been considered recently leading to an Airy equation for the partition function which is here used to explain the resurgent properties of the rescaled transseries.
High-index asymptotics of spherical Bessel products averaged with modulated Gaussian power laws
NASA Astrophysics Data System (ADS)
Tomaschitz, Roman
2014-12-01
Bessel integrals of type are investigated, where the kernel g( k) is a modulated Gaussian power-law distribution , and the jl ( m) are multiple derivatives of spherical Bessel functions. These integrals define the multipole moments of Gaussian random fields on the unit sphere, arising in multipole fits of temperature and polarization power spectra of the cosmic microwave background. Two methods allowing efficient numerical calculation of these integrals are presented, covering Bessel indices l in the currently accessible multipole range 0 ≤ l ≤ 104 and beyond. The first method is based on a representation of spherical Bessel functions by Lommel polynomials. Gaussian power-law averages can then be calculated in closed form as finite Hankel series of parabolic cylinder functions, which allow high-precision evaluation. The second method is asymptotic, covering the high- l regime, and is applicable to general distribution functions g( k) in the integrand; it is based on the uniform Nicholson approximation of the Bessel derivatives in conjunction with an integral representation of squared Airy functions. A numerical comparison of these two methods is performed, employing Gaussian power laws and Kummer distributions to average the Bessel products.
Upwarp of anomalous asthenosphere beneath the Rio Grande rift
Parker, E.C.; Davis, P.M.; Evans, J.R.; Iyer, H.M.; Olsen, K.H.
1984-01-01
Continental rifts are possible analogues of mid-ocean ridges, although major plate tectonic features are less clearly observed1. Current thermal models of mid-ocean ridges2-4 consist of solid lithospheric plates overlying the hotter, less viscous asthenosphere, with plate thickness increasing away from the ridge axis. The lithospheric lower boundary lies at or near the melting point isotherm, so that at greater depths higher temperatures account for lower viscosity, lower seismic velocities and possibly partial melting. Upwarp of this boundary at the ridge axis concentrates heat there, thus lowering densities by expansion and raising the sea floor to the level of thermal isostatic equilibrium. At slow spreading ridges, a major central graben forms owing to the mechanics of magma injection into the crust5. Topography, heat flow, gravity and seismic studies support these models. On the continents, a low-velocity channel has been observed, although it is poorly developed beneath ancient cratons6-9. Plate tectonic models have been applied to continental basins and margins10-12, but further similarities to the oceanic models remain elusive. Topographic uplift is often ascribed to Airy type isostatic compensation caused by crustal thickening, rather than thermal compensation in the asthenosphere. Here we discuss the Rio Grande rift, in southwestern United States. Teleseismic P-wave residuals show that regional uplift is explained by asthenosphere uplift rather than crustal thickening. ?? 1984 Nature Publishing Group.
Mercury's Global Topography from Radar Ranging Data
NASA Technical Reports Server (NTRS)
Anderson, J. D.; Schubert, G.; Asmar, S. W.; Jurgens, R. F.; Lau, E. L.; Moore, W. B.; Slade, M. A., III; Standish, E. M., Jr.
2001-01-01
When Mercury's radius is expanded in Legendre functions to the second degree and order, the systematic error in radar ranging data is reduced substantially. Previously, data spanning an observing interval from 1966 to 1990 were used to infer an equatorial ellipticity (a - b)/a = (540 +/- 54) X 10(exp -6) and a center-of-figure minus center-of-mass offset of (640 +/- 78) m. The magnitude of this equatorial center of figure offset implies an excess crustal thickness of 12 km or less, comparable to the Moon's excess. By comparing the equatorial ellipticity with the Mariner 10 gravity field, and assuming Airy isostatic compensation, bounds on crustal thickness can be derived. Mercury's crustal thickness is in the range from 100 to 300 km. The Mercury radar ranging observing interval has been extended from 1966 to the present. In addition, improvements in data reduction techniques have resulted in a set of Mercury ranging data less affected by systematic error, in particular the biases introduced by local topographic variations. We use this new set of reduced ranging data to improve Mercury's global topography and center-of-figure minus center-of-mass offset. New results on crustal thickness are derived, and prospects for further improvement with Mercury Orbiter data are discussed.
An approach for characterizing and comparing hyperspectral microscopy systems.
Annamdevula, Naga S; Sweat, Brenner; Favreau, Peter; Lindsey, Ashley S; Alvarez, Diego F; Rich, Thomas C; Leavesley, Silas J
2013-07-19
Hyperspectral imaging and analysis approaches offer accurate detection and quantification of fluorescently-labeled proteins and cells in highly autofluorescent tissues. However, selecting optimum acquisition settings for hyperspectral imaging is often a daunting task. In this study, we compared two hyperspectral systems-a widefield system with acoustic optical tunable filter (AOTF) and charge coupled device (CCD) camera, and a confocal system with diffraction gratings and photomultiplier tube (PMT) array. We measured the effects of system parameters on hyperspectral image quality and linear unmixing results. Parameters that were assessed for the confocal system included pinhole diameter, laser power, PMT gain and for the widefield system included arc lamp intensity, and camera gain. The signal-to-noise ratio (SNR) and the root-mean-square error (RMS error) were measured to assess system performance. Photobleaching dynamics were studied. Finally, theoretical sensitivity studies were performed to estimate the incremental response (sensitivity) and false-positive detection rates (specificity). Results indicate that hyperspectral imaging assays are highly dependent on system parameters and experimental conditions. For detection of green fluorescent protein (GFP)-expressing cells in fixed lung tissues, a confocal pinhole of five airy disk units, high excitation intensity and low detector gain were optimal. The theoretical sensitivity studies revealed that widefield hyperspectral microscopy was able to detect GFP with fewer false positive occurrences than confocal microscopy, even though confocal microscopy offered improved signal and noise characteristics. These studies provide a framework for optimization that can be applied to a variety of hyperspectral imaging systems.
Remanent magnetization model for the broken ridge satellite magnetic anomaly
NASA Technical Reports Server (NTRS)
Johnson, B. D.
1983-01-01
A crustal model for the interpretation of the Broken Ridge satellite magnetic anomaly was constructed from bathymetric data assuming an Airy-type isostatic compensation. An average crustal magnetization of 6 A.m is required to account for the observed anomaly amplitudes provided that the whole crust is homogeneously magnetized. In contrast, a model representing only the topographic expression of the Broken Ridge, above the surrounding sea floor, requires a magnetization of the order of 40 A.m-1. Since this latter figure is much higher than is to be expected from studies of magnetic properties of oceanic rocks, it is concluded that the majority of the crustal volume of Broken Ridge is magnetized relatively uniformly. The direction of the source magnetization is consistent with an inclination shallower than the present geomagnetic field and close to that of an axial dipole. Since a more northerly source location for Broken Ridge is contrary to the paleolatitude data it is though that the magnetization represents a magnetization obtained by averaging the geomagnetic field direction over a sufficient time to remove secular variation effects. This pattern is indicative of viscous magnetization.
Internal resonance of axially moving laminated circular cylindrical shells
NASA Astrophysics Data System (ADS)
Wang, Yan Qing; Liang, Li; Guo, Xing Hui
2013-11-01
The nonlinear vibrations of a thin, elastic, laminated composite circular cylindrical shell, moving in axial direction and having an internal resonance, are investigated in this study. Nonlinearities due to large-amplitude shell motion are considered by using Donnell's nonlinear shallow-shell theory, with consideration of the effect of viscous structure damping. Differently from conventional Donnell's nonlinear shallow-shell equations, an improved nonlinear model without employing Airy stress function is developed to study the nonlinear dynamics of thin shells. The system is discretized by Galerkin's method while a model involving four degrees of freedom, allowing for the traveling wave response of the shell, is adopted. The method of harmonic balance is applied to study the nonlinear dynamic responses of the multi-degrees-of-freedom system. When the structure is excited close to a resonant frequency, very intricate frequency-response curves are obtained, which show strong modal interactions and one-to-one-to-one-to-one internal resonance phenomenon. The effects of different parameters on the complex dynamic response are investigated in this study. The stability of steady-state solutions is also analyzed in detail.
NASA Astrophysics Data System (ADS)
Dakshinamurthy, Surendramohan; Quick, Nathaniel R.; Kar, Aravinda
2006-05-01
Crystalline silicon carbide is a chemically inert wide band gap semiconductor with good mechanical strength and oxidation-resistant properties at elevated temperatures, which make it a good sensor material for harsh environments such as combustion chambers and turbine systems. For such cases, optical sensors are generally superior to electrical sensors in many aspects such as responsivity, detectivity, and sensitivity. This paper presents a wireless technique for pressure and chemical sensing based on the pressure-and temperature-dependent refractive indices of silicon carbide. A helium-neon laser with a wavelength of 632.8 nm was used as a probe laser to obtain the complementary Airy pattern of the laser power reflected off a silicon carbide wafer segment at high temperatures (up to 300 °C) and pressures (up to 400 psi). The interference patterns revealed unique characteristics for nitrogen and argon test gases. This pattern is different at the same pressure and temperature for the two gases, indicating the chemical sensing selectivity capability of silicon carbide. Also the pattern changes with pressures for the same gas, indicating the pressure sensing capability. The refractive index of silicon carbide has been obtained for different pressures and temperatures using the interference pattern. A three-layer model has been employed to determine the refractive indices of the gases using the reflected power data.
How is the artist role affected when artists are participating in projects in work life?
Stenberg, Henrik
2016-01-01
In Sweden, during the last decade, the artist has come to function as a creative resource in workplaces. There are two organisations, Skiss (Contemporary Artist in the Contemporary Society) and Airis (Artist in Residence), that organise projects for artists and coworkers. These projects are intended to have a positive effect on the well-being of organisations and their employees through artistic means, and the artist often focuses on the social interaction between the employees in their work. The artists' work involves frequent interaction with coworkers. The aim of this article was to describe how visual artists' roles as artists are affected by their engagement in artistic and social projects at workplaces in Sweden. The focus in the article is on the social interaction between artists and employees. The study is a qualitative narrative interview study with fine artists participating in different projects in work life. Since the artist's intervention is usually directed towards social relations in the workplaces, a social perspective on well-being is from a micro-sociological point of view. The categories in the interviews were how the artists worked with the projects, how the social interaction between artists and coworkers worked out, and how the artists evaluated the projects in relation to their ambitions. The results show that, many times, the artistic projects promote well-being in organisations and to some extent benefit the artist, but that the ability of the artists to actually function as artists can be problematic.
TASEP on a Ring in Sub-relaxation Time Scale
NASA Astrophysics Data System (ADS)
Baik, Jinho; Liu, Zhipeng
2016-12-01
Interacting particle systems in the KPZ universality class on a ring of size L with O( L) number of particles are expected to change from KPZ dynamics to equilibrium dynamics at the so-called relaxation time scale t=O(L^{3/2}). In particular the system size is expected to have little effect to the particle fluctuations in the sub-relaxation time scale 1≪ t≪ L^{3/2}. We prove that this is indeed the case for the totally asymmetric simple exclusion process (TASEP) with two types of initial conditions. For flat initial condition, we show that the particle fluctuations are given by the Airy_1 process as in the infinite TASEP with flat initial condition. On the other hand, the TASEP on a ring with step initial condition is equivalent to the periodic TASEP with a certain shock initial condition. We compute the fluctuations explicitly both away from and near the shocks for the infinite TASEP with same initial condition, and then show that the periodic TASEP has same fluctuations in the sub-relaxation time scale.
Fresnel equations and transmission line analogues for diffraction gratings
Kaushik, S.
1995-08-01
A simple and intuitive formalism is presented to describe diffraction in multi-layered periodic structures. We use the well known results from scalar analysis (wave propagation in homogeneous layered media) and show that they can be generalized rather readily to vector problems such as diffraction analysis. Specifically, we derive: (1) generalized Fresnel equations appropriate for reflection and transmission from an infinitely thick grating, (2) a generalized Airy formula for thin-film to describe reflection and transmission of light through a lamellar grating and (3) a matrix propagation method akin to that used for multi-layer thin film analysis. The results developed here complement the recent work on R-matrix and S-matrix propagation algorithms that have been used in connection with modal and differential grating theories. These algorithms have proven to be numerically stable for calculating diffraction efficiencies from deep groove gratings. The formalism developed here expands upon the earlier literature by providing important details that are hitherto unavailable.
Scattering of wave packets with phases
NASA Astrophysics Data System (ADS)
Karlovets, Dmitry V.
2017-03-01
A general problem of 2 → N f scattering is addressed with all the states being wave packets with arbitrary phases. Depending on these phases, one deals with coherent states in (3 + 1) D, vortex particles with orbital angular momentum, the Airy beams, and their generalizations. A method is developed in which a number of events represents a functional of the Wigner functions of such states. Using width of a packet σ p /< p> as a small parameter, the Wigner functions, the number of events, and a cross section are represented as power series in this parameter, the first non-vanishing corrections to their plane-wave expressions are derived, and generalizations for beams are made. Although in this regime the Wigner functions turn out to be everywhere positive, the cross section develops new specifically quantum features, inaccessible in the plane-wave approximation. Among them is dependence on an impact parameter between the beams, on phases of the incoming states, and on a phase of the scattering amplitude. A model-independent analysis of these effects is made. Two ways of measuring how a Coulomb phase and a hadronic one change with a transferred momentum t are discussed.
NASA Technical Reports Server (NTRS)
Macenka, Steven A.; Chipman, Russell A.; Daugherty, Brian J.; McClain, Stephen C.
2012-01-01
A report discusses the difficulty of measuring scattering properties of coated mirrors extremely close to the specular reflection peak. A prototype Optical Hetero dyne Near-angle Scatterometer (OHNS) was developed. Light from a long-coherence-length (>150 m) 532-nm laser is split into two arms. Acousto-optic modulators frequency shift the sample and reference beams, establishing a fixed beat frequency between the beams. The sample beam is directed at very high f/# onto a mirror sample, and the point spread function (PSF) formed after the mirror sample is scanned with a pinhole. This light is recombined by a non-polarizing beam splitter and measured through heterodyne detection with a spectrum analyzer. Polarizers control the illuminated and analyzed polarization states, allowing the polarization dependent scatter to be measured. The bidirectional reflective or scattering distribution function is normally measured through use of a scattering goniometer instrument. The instrumental beam width (collection angle span) over which the scatterometer responds is typically many degrees. The OHNS enables measurement at angles as small as the first Airy disk diameter.
NASA Astrophysics Data System (ADS)
Tomaschitz, Roman
2014-06-01
Weber integrals {int_0^infty {k^{2+μ}{e}^{-ak2}j_n^{2} (pk)dk}} and Beltrami integrals {int_0^infty {k^{2+μ}{e}^{-bk}j_n^{2} (pk)dk}} are studied, which arise in the multipole expansions of spherical random fields. These integrals define spectral averages of squared spherical Bessel functions j {/n 2} with Gaussian or exponentially cut power-law densities. Finite series representations of the integrals are derived for integer power-law index Î¼, which admit high-precision evaluation at low and moderate Bessel index n. At high n, numerically tractable uniform asymptotic approximations are obtained, based on the Debye expansion of modified spherical Bessel functions in the case of Weber integrals. The high-n approximation of Beltrami integrals can be reduced to Legendre asymptotics. The Airy approximation of Weber and Beltrami integrals is derived as well, and numerical tests are performed over a wide range of Bessel indices, by comparing the exact finite series expansions of the integrals to their high-index asymptotics.
A modified Variable-Phase algorithm for multichannel scattering with long-range potentials
NASA Astrophysics Data System (ADS)
Martinazzo, R.; Bodo, E.; Gianturco, F. A.
2003-03-01
A new Variable-Phase (VP) algorithm for solving the close coupled equations of inelastic scattering in atom-molecule collisions driven by a strong long range potential is presented. The proposed method allows for a rigorous, gradual reduction of the number of closed channels during the outward propagation of the solution of the VP equations. In this way it allows a considerable saving of CPU time when dealing with strong, long-range potentials. A further saving of computational time is achieved by the use of a zero order effective potential in the reference problem which avoids the calculation of the computationally expensive Bessel functions. The K matrix version of the VP equations are solved with a standard Runge-Kutta integrator with adaptive step size. The low-energy, rotational excitation process in the LiH-H + system is used to test the resulting algorithm and we show that the present method once applied to long-range interactions, can be orders of magnitude faster than the widely used, adaptive-step size LogDerivative/Airy propagator while keeping the same level of accuracy.
Bacterial contamination of anaesthetic gases.
Nielsen, H; Vasegaard, M; Stokke, D B
1978-08-01
The bacterial content of oxygen and nitrous oxide immediately before and after passing through clean and used breathing systems (circuits) was measured using a specially constructed agar chamber (Bourdillon's slit sampler). The content per litre of oxygen from the outlet of the anaesthetic machine was 4.0 X 10-2, and 2.9 X 10-2 for nitrous oxide, corresponding to 3.5 X 10-2 for a 50% mixture of the gases. After passing through cleaned circuits, the bacterial pollution of the gas mixture had increased by 30%, but more than elevenfold after passing through used circuits. The content from cleaned circuits was less than that measured previously in the air of hospital wards and operating theatres, whereas gases from used circuits were polluted to approximately the same extent. It is concluded that used circuits may increase the risk of cross-infection. The cleaning method employed by us (dish-washer--hot airy drying) appeared to be acceptable.
How is the artist role affected when artists are participating in projects in work life?
Stenberg, Henrik
2016-01-01
In Sweden, during the last decade, the artist has come to function as a creative resource in workplaces. There are two organisations, Skiss (Contemporary Artist in the Contemporary Society) and Airis (Artist in Residence), that organise projects for artists and coworkers. These projects are intended to have a positive effect on the well-being of organisations and their employees through artistic means, and the artist often focuses on the social interaction between the employees in their work. The artists’ work involves frequent interaction with coworkers. The aim of this article was to describe how visual artists’ roles as artists are affected by their engagement in artistic and social projects at workplaces in Sweden. The focus in the article is on the social interaction between artists and employees. The study is a qualitative narrative interview study with fine artists participating in different projects in work life. Since the artist's intervention is usually directed towards social relations in the workplaces, a social perspective on well-being is from a micro-sociological point of view. The categories in the interviews were how the artists worked with the projects, how the social interaction between artists and coworkers worked out, and how the artists evaluated the projects in relation to their ambitions. The results show that, many times, the artistic projects promote well-being in organisations and to some extent benefit the artist, but that the ability of the artists to actually function as artists can be problematic. PMID:27167555
[Tuberculosis and the modern ideal of living].
Medici, T C
2003-08-20
Sunlight and fresh air belong to the everyday life's myths. It has influenced our times and personal lives as much as industrialization. Today we are hardly aware of the multiple and omnipresent consequences of this myth. The modern movement with all its facets including modern architecture is barely conceivable without it. What is the link between this triad with all its effects and tuberculosis, the oldest and most important infectious disease which still claims more than 3 million deaths per year worldwide? Tuberculosis was treated by sunlight and fresh air at all times. This treatment was at its zenith during the second half of the 19th century after Hermann Brehmer had initiated this treatment within sanatoria in 1862. The sanatorium vogue lasted until the middle of the last century when streptomycin was isolated by Selman Waksman 1943. A new type of hospital was necessary for treating the patients with sunlight and fresh air: the sanatorium with its wide windows, sheltered open balconies, terraces and "Liegehallen". In return, this airy type of building was the forrunner of a new architectural style, called "Neues Bauen". The latter has profoundly influenced our modern ideal of living since Le Corbusiier built the Villa Savoye, one of the architectural highlights of the 20th century.
Generalized non-separable two-dimensional Dammann encoding method
NASA Astrophysics Data System (ADS)
Yu, Junjie; Zhou, Changhe; Zhu, Linwei; Lu, Yancong; Wu, Jun; Jia, Wei
2017-01-01
We generalize for the first time, to the best of our knowledge, the Dammann encoding method into non-separable two-dimensional (2D) structures for designing various pure-phase Dammann encoding gratings (DEGs). For examples, three types of non-separable 2D DEGs, including non-separable binary Dammann vortex gratings, non-separable binary distorted Dammann gratings, and non-separable continuous-phase cubic gratings, are designed theoretically and demonstrated experimentally. Correspondingly, it is shown that 2D square arrays of optical vortices with topological charges proportional to the diffraction orders, focus spots shifting along both transversal and axial directions with equal spacings, and Airy-like beams with controllable orientation for each beam, are generated in symmetry or asymmetry by these three DEGs, respectively. Also, it is shown that a more complex-shaped array of modulated beams could be achieved by this non-separable 2D Dammann encoding method, which will be a big challenge for those conventional separable 2D Dammann encoding gratings. Furthermore, the diffractive efficiency of the gratings can be improved around ∼10% when the non-separable structure is applied, compared with their conventional separable counterparts. Such improvement in the efficiency should be of high significance for some specific applications.
Raman and the mirage revisited: confusions and a rediscovery
NASA Astrophysics Data System (ADS)
Berry, M. V.
2013-11-01
Raman argued that in a continuously varying layered medium, such as air above a hot road, a ray that bends so as to become horizontal must remain so, implying that the reflection familiar in the mirage cannot be explained by geometrical optics. This is a mistake, as standard ray curvature arguments demonstrate. But a simple limiting process, in which the smoothly varying refractive index is approximated by a stack of thin discrete layers, is not quite straightforward because it involves a curious singularity, related to the level ray envisaged by Raman. In contrast to individual rays, families of rays possess caustic (focal) singularities. These can be calculated explicitly for two families of rays that are relevant to the mirage. Only exceptionally does the locus of reflection (lowest points on the rays) coincide with the caustics. Caustics correspond to the ‘vanishing line’, representing the limiting height of objects that can be seen by reflection. For these two families, the waves that decorating mirage caustics are described by the universal Airy function, and can be calculated exactly.
Focal plane optics in far-infrared and submillimeter astronomy
NASA Technical Reports Server (NTRS)
Hildebrand, R. H.
1985-01-01
The construction of airborne observatories, high mountain-top observatories, and space observatories designed especially for infrared and submillimeter astronomy has opened fields of research requiring new optical techniques. A typical far-IR photometric study involves measurement of a continuum spectrum in several passbands between approx 30 microns and 1000 microns and diffraction-limited mapping of the source. At these wavelengths, diffraction effects strongly influence the design of the field optics systems which couple the incoming flux to the radiation sensors (cold bolometers). The Airy diffraction disk for a typical telescope at submillimeter wavelengths approx 100 microns-1000 microns is many millimeters in diameter; the size of the field stop must be comparable. The dilute radiation at the stop is fed through a Winston nonimaging concentrator to a small cavity containing the bolometer. The purpose of this paper is to review the principles and techniques of infrared field optics systems, including spectral filters, concentrators, cavities, and bolometers (as optical elements), with emphasis on photometric systems for wavelengths longer than 60 microns.
Focal plane optics in far-infrared and submillimeter astronomy
NASA Technical Reports Server (NTRS)
Hildebrand, R. H.
1986-01-01
The construction of airborne observatories, high mountain-top observatories, and space observatories designed especially for infrared and submillimeter astronomy has opened fields of research requiring new optical techniques. A typical far-IR photometric study involves measurement of a continuum spectrum in several passbands between approx 30 microns and 1000 microns and diffraction-limited mapping of the source. At these wavelengths, diffraction effects strongly influence the design of the field optics systems which couple the incoming flux to the radiation sensors (cold bolometers). The Airy diffraction disk for a typical telescope at submillimeter wavelengths approx 100 microns-1000 microns is many millimeters in diameter; the size of the field stop must be comparable. The dilute radiation at the stop is fed through a Winston nonimaging concentrator to a small cavity containing the bolometer. The purpose of this paper is to review the principles and techniques of infrared field optics systems, including spectral filters, concentrators, cavities, and bolometers (as optical elements), with emphasis on photometric systems for wavelengths longer than 60 microns.
Diffraction-free light droplets for axially-resolved volume imaging.
Antonacci, G; Domenico, G Di; Silvestri, S; DelRe, E; Ruocco, G
2017-12-01
An ideal direct imaging system entails a method to illuminate on command a single diffraction-limited region in a generally thick and turbid volume. The best approximation to this is the use of large-aperture lenses that focus light into a spot. This strategy fails for regions that are embedded deep into the sample, where diffraction and scattering prevail. Airy beams and Bessel beams are solutions of the Helmholtz Equation that are both non-diffracting and self-healing, features that make them naturally able to outdo the effects of distance into the volume but intrinsically do not allow resolution along the propagation axis. Here, we demonstrate diffraction-free self-healing three-dimensional monochromatic light spots able to penetrate deep into the volume of a sample, resist against deflection in turbid environments, and offer axial resolution comparable to that of Gaussian beams. The fields, formed from coherent mixtures of Bessel beams, manifest a more than ten-fold increase in their undistorted penetration, even in turbid milk solutions, compared to diffraction-limited beams. In a fluorescence imaging scheme, we find a ten-fold increase in image contrast compared to diffraction-limited illuminations, and a constant axial resolution even after four Rayleigh lengths. Results pave the way to new opportunities in three-dimensional microscopy.
A study of time harmonic guided Lamb waves and their caustics in composite plates.
Karmazin, Alexander; Kirillova, Evgenia; Seemann, Wolfgang; Syromyatnikov, Pavel
2013-01-01
Spatial steady-state Lamb wave propagation in an anisotropic composite plate excited by harmonic surface sources is modeled using a Green's matrix representation in a frequency-wavenumber domain. An approach based on a residue integration technique for two dimensional wavenumber integrals for the computation of displacements outside an excitation source is presented in this paper. In the far-field zone of the excitation source, the method of stationary phase is used, which gives an asymptotic expansion of the displacement vector as a sum of cylindrical waves. Near caustic directions, a far-field solution is computed in terms of Airy functions. The results obtained applying residue integration technique and asymptotic expansion are found to be coinciding with the results of the computation by using the adaptive quadratures. Moreover, these approaches agree well with experimental data. Then, the advantages and disadvantages of the various methods applied for modeling of Lamb wave propagation are discussed in this paper. Focussing and other properties of Lamb waves are studied using numerical examples.
Resolution limits for imaging through multi-mode fiber.
Mahalati, Reza Nasiri; Gu, Ruo Yu; Kahn, Joseph M
2013-01-28
We experimentally demonstrate endoscopic imaging through a multi-mode fiber (MMF) in which the number of resolvable image features approaches four times the number of spatial modes per polarization propagating in the fiber. In our method, a sequence of random field patterns is input to the fiber, generating a sequence of random intensity patterns at the output, which are used to sample an object. Reflected power values are returned through the fiber and linear optimization is used to reconstruct an image. The factor-of-four resolution enhancement is due to mixing of modes by the squaring inherent in field-to-intensity conversion. The incoherent point-spread function (PSF) at the center of the fiber output plane is an Airy disk equivalent to the coherent PSF of a conventional diffraction-limited imaging system having a numerical aperture twice that of the fiber. All previous methods for imaging through MMF can only resolve a number of features equal to the number of modes. Most of these methods use localized intensity patterns for sampling the object and use local image reconstruction.
Allgaier, D.E.
1986-04-07
Asymptotic solutions for the nonlinear, nonhomogeneous, Korteweg-deVries (KdV) partial differential equation with slowly varying coefficients are not, in general, uniformly valid. A uniform asymptotic expansion is obtained by finding separate expansions for different regions and matching. A KdV solitary wave propagating in slowly varying media is examined. Quasi-stationarity for the core reduces the problem to solving ordinary differential equations for that region. However, in the leading tail region, hyperbolic pde's must be solved to determine the amplitude and phase. The method of characteristics predicts triple valuedness after a caustic (penumbral or cusped) develops. Singular perturbation methods show the solution near first focusing satisfies the diffusion equation and involves either an incomplete Airy-type integral or an exponential integral similar to the Pearcey integral. Laplace's method shows that the critical points of the exponential phase satisfy the fundamental folding equation. A linear multi-phase solution is determined which does not become triple valued (break). Instead, a wave number shock develops, which separates two different solitary wave tails, and travels at the shock velocity predicted by conservation of waves. Thus, a unique uniform leading tail solution is obtained corresponding to a specified moving core (the problem is shown to be well-posed).
Detecting curvatures in digital images using filters derived from differential geometry
NASA Astrophysics Data System (ADS)
Toro Giraldo, Juanita
2015-09-01
Detection of curvature in digital images is an important theoretical and practical problem in image processing. Many important features in an image are associated with curvature and the detection of such features is reduced to detection and characterization of curvatures. Differential geometry studies many kinds of curvature operators and from these curvature operators is possible to derive powerful filters for image processing which are able to detect curvature in digital images and videos. The curvature operators are formulated in terms of partial differential operators which can be applied to images via convolution with generalized kernels derived from the the Korteweg- de Vries soliton . We present an algorithm for detection of curvature in digital images which is implemented using the Maple package ImageTools. Some experiments were performed and the results were very good. In a future research will be interesting to compare the results using the Korteweg-de Vries soliton with the results obtained using Airy derivatives. It is claimed that the resulting curvature detectors could be incorporated in standard programs for image processing.
Fine Guidance Sensing for Coronagraphic Observatories
NASA Technical Reports Server (NTRS)
Brugarolas, Paul; Alexander, James W.; Trauger, John T.; Moody, Dwight C.
2011-01-01
Three options have been developed for Fine Guidance Sensing (FGS) for coronagraphic observatories using a Fine Guidance Camera within a coronagraphic instrument. Coronagraphic observatories require very fine precision pointing in order to image faint objects at very small distances from a target star. The Fine Guidance Camera measures the direction to the target star. The first option, referred to as Spot, was to collect all of the light reflected from a coronagraph occulter onto a focal plane, producing an Airy-type point spread function (PSF). This would allow almost all of the starlight from the central star to be used for centroiding. The second approach, referred to as Punctured Disk, collects the light that bypasses a central obscuration, producing a PSF with a punctured central disk. The final approach, referred to as Lyot, collects light after passing through the occulter at the Lyot stop. The study includes generation of representative images for each option by the science team, followed by an engineering evaluation of a centroiding or a photometric algorithm for each option. After the alignment of the coronagraph to the fine guidance system, a "nulling" point on the FGS focal point is determined by calibration. This alignment is implemented by a fine alignment mechanism that is part of the fine guidance camera selection mirror. If the star images meet the modeling assumptions, and the star "centroid" can be driven to that nulling point, the contrast for the coronagraph will be maximized.
Comparisons of global topographic/isostatic models to the Earth's observed gravity field
NASA Technical Reports Server (NTRS)
Rummel, Reiner; Rapp, Richard H.; Suenkel, Hans; Tscherning, C. Christian
1988-01-01
The Earth's gravitational potential, as described by a spherical harmonic expansion to degree 180, was compared to the potential implied by the topography and its isostatic compensation using five different hypothesis. Initially, series expressions for the Airy/Heiskanen topographic isostatic model were developed to the third order in terms of (h/R), where h is equivalent rock topography and R is a mean Earth radius. Using actual topographic developments for the Earth, it was found that the second and third terms of the expansion contributed 30 and 3 percents, of the first of the expansion. With these new equations it is possible to compute depths (D) of compensation, by degree, using 3 different criteria. The results show that the average depth implied by criterion I is 60 km while it is about 33 km for criteria 2 and 3 with smaller compensation depths at the higher degrees. Another model examined was related to the Vening-Meinesz regional hypothesis implemented in the spectral domain. Finally, oceanic and continental response functions were derived for the global data sets and comparisons made to locally determined values.
Growth phenotype screening of Schizosaccharomyces pombe using a Lensless microscope.
Penwill, Lynsey A; Batten, Gwendoline E; Castagnetti, Stefania; Shaw, Andrew M
2014-04-15
The Lensless microscope has a large field of view and allows the capture of the diffraction pattern from a large number of cells simultaneously. A simple algorithm to measure intensity changes in the Airy Disc First Fringe (ADFF) has been derived to follow the growth characteristics of the unicellular yeast Schizosaccharomyces pombe. The performance of the algorithm is calibrated using comparison between optical image and ADFF analysis of polystyrene microspheres with known dimensions and has an accuracy of 5% over all lengths above the diffraction-limited measurements. We have observed the growth characteristics of S. pombe for N=100 cells to determine the growth phenotype distributions of Length (L(t=0)) and width (W(t=0)) on arrival at the surface, lag phase adjustment to the new growth conditions (B), the length at birth, LB, and cell cycle length, tcell. The observed cell width distribution has a median width of 3.9 (±0.1) µm, as expected, but a non-normal distribution. Similarly, all growth parameters studied, L(t=0), LB and cell cycle time are phenotypes with non-normal distributions but with medians consistent with the literature values.
A dynamic model of Venus's gravity field
NASA Technical Reports Server (NTRS)
Kiefer, W. S.; Richards, M. A.; Hager, B. H.; Bills, B. G.
1984-01-01
Unlike Earth, long wavelength gravity anomalies and topography correlate well on Venus. Venus's admittance curve from spherical harmonic degree 2 to 18 is inconsistent with either Airy or Pratt isostasy, but is consistent with dynamic support from mantle convection. A model using whole mantle flow and a high viscosity near surface layer overlying a constant viscosity mantle reproduces this admittance curve. On Earth, the effective viscosity deduced from geoid modeling increases by a factor of 300 from the asthenosphere to the lower mantle. These viscosity estimates may be biased by the neglect of lateral variations in mantle viscosity associated with hot plumes and cold subducted slabs. The different effective viscosity profiles for Earth and Venus may reflect their convective styles, with tectonism and mantle heat transport dominated by hot plumes on Venus and by subducted slabs on Earth. Convection at degree 2 appears much stronger on Earth than on Venus. A degree 2 convective structure may be unstable on Venus, but may have been stabilized on Earth by the insulating effects of the Pangean supercontinental assemblage.
Upper- Mantle Driven Dynamic Uplift in Central Anatolia
NASA Astrophysics Data System (ADS)
Sengul Uluocak, Ebru; Pysklywec, Russell; Hakan Gogus, Oguz
2016-04-01
Based on geological and geophysical observations and interpretations of the present-day geodynamics, we propose that mantle structures beneath the crust drive a non-isostatic component of topography in Central Anatolia. Topography residuals for the region were calculated from the isostatic component of topography according to the principle of Airy isostasy while assuming crustal block is in hydrostatic equilibrium in the mantle. For the geodynamic interpretations we ran numerous 2D thermo-mechanical models based on different temperature inputs and viscous creep strength coefficients and using available P-wave tomography data along a N-S directional profile (33oE) through Central Anatolia as an estimate on the regional mantle structure. Our models are uniformly affected by widespread NE-SW oriented mantle flow obtained in the shear-wave azimuthal anisotropy studies and predict dynamic topography based on vertical components of density-driven flow in the upper mantle mainly induced by 2D temperature variations. The dynamic topography results indicate ~1 km instantaneous uplift in concordance with the under-compensated topography in the region. The data and modelling results define the region as a plateau-like uplift, slightly inflated in southern part based on dynamic topography patterns. The dynamic topography induced by upper-mantle flow provides robust new information about the main geodynamic components by showing broad consistency with independent data sets and observables for the area; such as, asthenospheric source of volcanism, gravity data, and high surface heat flow distributions.
Present-day dynamic and residual topography in Central Anatolia
NASA Astrophysics Data System (ADS)
Şengül Uluocak, Ebru; Pysklywec, Russell; Göǧüş, Oǧuz H.
2016-09-01
The Central Anatolian orogenic plateau is represented by young volcanism, rapid plateau uplift and distinctive (past and active) tectonic deformation. In this study, we consider observational data in terms of regional present-day geodynamics in the region. The residual topography of Central Anatolia was derived to define the regional isostatic conditions according to Airy isostasy and infer the potential role of `dynamic topography'. 2-D thermomechanical forward models for coupled mantle-lithosphere flow/deformation were conducted along an N-S directional profile through the region (e.g. northern/Pontides, interior and southern/Taurides). These models were based on seismic tomography data that provide estimates about the present-day mantle thermal structure beneath the Anatolian plate. We compare the modelling results with calculated residual topography and independent data sets of geological deformation, gravity and high surface heat flow/widespread geothermal activity. Model results suggest that there is ˜1 km of mantle flow induced dynamic topography associated with the sublithospheric flow driven by the seismically inferred mantle structure. The uprising mantle may have also driven the asthenospheric source of volcanism in the north (e.g. Galatia volcanic province) and the Cappadocia volcanic province in the south while elevating the surface in the last 10 Myr. Our dynamic topography calculations emphasize the role of vertical forcing under other orogenic plateaux underlain by relatively thin crust and low-density asthenospheric mantle.
NASA Astrophysics Data System (ADS)
Glasgow, Ben J.
2016-02-01
A conventional fluorescence microscope was previously constructed for simultaneous imaging of two colors to gain sub-diffraction localization. The system is predicated on color separation of overlapping Airy discs, construction of matrices of Cartesian coordinates to determine locations as well as centers of the point spread functions of fluorophores. Quantum dots that are separated by as little as 10 nm were resolved in the x-y coordinates. Inter-fluorophore distances that vary by 10 nm could also be distinguished. Quantum dots are bright point light source emitters that excite with a single laser and can serve as a label for many biomolecules. Here, alterations in the method are described to test the ability to resolve Atto 488 and Atto 647 dyes attached to DNA origami at ~40 nm spacing intervals. Dual laser excitation is used in tandem with multi-wavelength bandpass filters. Notwithstanding challenges from reduced intensity in Atto labeled DNA origami helical bundles compared to quantum dots, preliminary data show a mean inter-fluorophore distance of 56 nm with a range (14-148 nm). The range closely matches published results with DNA origami with other methods of subdiffraction microscopy. Sub-diffraction simultaneous two-color imaging fluorescence microscopy acronymically christened (SSTIFM) is a simple, readily accessible, technique for measurement of inter-fluorophore distances in compartments less than 40 nm. Preliminary results with so called nanorulers are encouraging for use with other biomolecules.
NASA Astrophysics Data System (ADS)
Niemi, Paul R.; D., O.; Mc Leod, David M.; Mc Leod, Roger D.
2007-04-01
RDM taught a health professional how to recover her previously impaired near vision in one session, also bringing a similar male from 20/30 to 20/10, distance vision, in about ten minutes; another health professional's improvement went from 20/300 to 20/20 in three sessions. A former athlete achieved a distance improvement from 20/800 to 20/100, again, in three sessions. RDM offers to replicate these types of improvements, using patent-pending Naturoptics under monitored conditions, and non-disclosure restraints, to protect franchising and patent-pending rights. Evening atropine use, controlled, at Singapore's National Eye Center, demonstrated an effect against myopia. Does this actually constitute an experimental verification of Mc Leod's Airy-disk radius-formula explanation of how vision works, and predicts how it can be damaged/repaired? Evaluation and documentation is to be by close and distance vision standard charts, or their equivalents, with guaranteed ``chart'' improvements of one line per session, after the beginning visit, or the session is free. Patent-pending Naturoptics differs from all vision-boosting competitors by safely re-eliciting vision's feedback control self-repairs, including astigmatism and presbyopia. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.NES07.C2.4
Hyperspectral Infrared Imaging of Flames Using a Spectrally Scanning Fabry-Perot Filter
NASA Technical Reports Server (NTRS)
Rawlins, W. T.; Lawrence, W. G.; Marinelli, W. J.; Allen, M. G.; Piltch, N. (Technical Monitor)
2001-01-01
The temperatures and compositions of gases in and around flames can be diagnosed using infrared emission spectroscopy to observe molecular band shapes and intensities. We have combined this approach with a low-order scanning Fabry-Perot filter and an infrared camera to obtain spectrally scanned infrared emission images of a laboratory flame and exhaust plume from 3.7 to 5.0 micrometers, at a spectral resolution of 0.043 micrometers, and a spatial resolution of 1 mm. The scanning filter or AIRIS (Adaptive Infrared Imaging Spectroradiometer) is a Fabry-Perot etalon operating in low order (mirror spacing = wavelength) such that the central spot, containing a monochromatic image of the scene, is viewed by the detector array. The detection system is a 128 x 128 liquid-nitrogen-cooled InSb focal plane array. The field of view is controlled by a 50 mm focal length multielement lens and an V4.8 aperture, resulting in an image 6.4 x 6.4 cm in extent at the flame and a depth of field of approximately 4 cm. Hyperspectral images above a laboratory CH4/air flame show primarily the strong emission from CO2 at 4.3 micrometers, and weaker emissions from CO and H2O. We discuss techniques to analyze the spectra, and plans to use this instrument in microgravity flame spread experiments.
Deep rock damage in the San Andreas Fault revealed by P- and S-type fault-zone-guided waves
Ellsworth, William L.; Malin, Peter E.
2011-01-01
Damage to fault-zone rocks during fault slip results in the formation of a channel of low seismic-wave velocities. Within such channels guided seismic waves, denoted by Fg, can propagate. Here we show with core samples, well logs and Fg-waves that such a channel is crossed by the SAFOD (San Andreas Fault Observatory at Depth) borehole at a depth of 2.7 km near Parkfield, California, USA. This laterally extensive channel extends downwards to at least half way through the seismogenic crust, more than about 7 km. The channel supports not only the previously recognized Love-type- (FL) and Rayleigh-type- (FR) guided waves, but also a new fault-guided wave, which we name FF. As recorded 2.7 km underground, FF is normally dispersed, ends in an Airy phase, and arrives between the P- and S-waves. Modelling shows that FF travels as a leaky mode within the core of the fault zone. Combined with the drill core samples, well logs and the two other types of guided waves, FF at SAFOD reveals a zone of profound, deep, rock damage. Originating from damage accumulated over the recent history of fault movement, we suggest it is maintained either by fracturing near the slip surface of earthquakes, such as the 1857 Fort Tejon M 7.9, or is an unexplained part of the fault-creep process known to be active at this site.
Inverted Gabor holography principle for tailoring arbitrary shaped three-dimensional beams
NASA Astrophysics Data System (ADS)
Latychevskaia, Tatiana; Fink, Hans-Werner
2016-05-01
It is well known that by modifying the wavefront in a certain manner, the light intensity can be turned into a certain shape. However, all known light modulation techniques allow for limited light modifications only: focusing within a restricted region in space, shaping into a certain class of parametric curves along the optical axis or bending described by a quadratic-dependent deflection as in the case of Airy beams. We show a general case of classical light wavefront shaping that allows for intensity and phase redistribution into an arbitrary profile including pre-determined switching-off of the intensity. To create an arbitrary three-dimensional path of intensity, we represent the path as a sequence of closely packed individual point-like absorbers and simulate the in-line hologram of the created object set; when such a hologram is contrast inverted, thus giving rise to a diffractor, it creates the pre-determined three-dimensional path of intensity behind the diffractor under illumination. The crucial parameter for a smooth optical path is the sampling of the predetermined curves, which is given by the lateral and axial resolution of the optical system. We provide both, simulated and experimental results to demonstrate the power of this novel method.
Zhou, Zhi-Yuan; Li, Yan; Ding, Dong-Sheng; Jiang, Yun-Kun; Zhang, Wei; Shi, Shuai; Shi, Bao-Sen; Guo, Guang-Can
2014-01-01
Light beams with extraordinary spatial structures, such as the Airy beam (AB), the Bessel-Gaussian beam (BGB) and the Laguerre-Gaussian beam (LGB), are widely studied and applied in many optical scenarios. We report on preparation of light beams with controllable spatial structures through sum frequency generation (SFG) using two Gaussian pump beams in a quasi-phase matching (QPM) crystal. The spatial structures, including multi-ring-like BGB, donut-like LGB, and super-Gaussian-like beams, can be controlled periodically via crystal phase mismatching by tuning the pump frequency or crystal temperature. This phenomenon has not been reported or discussed previously. Additionally, we present numerical simulations of the phenomenon, which agree very well with the experimental observations. Our findings give further insight into the SFG process in QPM crystals, provide a new way to generate light with unusual spatial structures, and may find applications in the fields of laser optics, all-optical switching, and optical manipulation and trapping. PMID:25007780
Teaching Mathematical Modelling for Earth Sciences via Case Studies
NASA Astrophysics Data System (ADS)
Yang, Xin-She
2010-05-01
Mathematical modelling is becoming crucially important for earth sciences because the modelling of complex systems such as geological, geophysical and environmental processes requires mathematical analysis, numerical methods and computer programming. However, a substantial fraction of earth science undergraduates and graduates may not have sufficient skills in mathematical modelling, which is due to either limited mathematical training or lack of appropriate mathematical textbooks for self-study. In this paper, we described a detailed case-study-based approach for teaching mathematical modelling. We illustrate how essential mathematical skills can be developed for students with limited training in secondary mathematics so that they are confident in dealing with real-world mathematical modelling at university level. We have chosen various topics such as Airy isostasy, greenhouse effect, sedimentation and Stokes' flow,free-air and Bouguer gravity, Brownian motion, rain-drop dynamics, impact cratering, heat conduction and cooling of the lithosphere as case studies; and we use these step-by-step case studies to teach exponentials, logarithms, spherical geometry, basic calculus, complex numbers, Fourier transforms, ordinary differential equations, vectors and matrix algebra, partial differential equations, geostatistics and basic numeric methods. Implications for teaching university mathematics for earth scientists for tomorrow's classroom will also be discussed. Refereces 1) D. L. Turcotte and G. Schubert, Geodynamics, 2nd Edition, Cambridge University Press, (2002). 2) X. S. Yang, Introductory Mathematics for Earth Scientists, Dunedin Academic Press, (2009).
Moho Depth and Poisson's Ratio beneath Eastern-Central China and Its Tectonic Implications
NASA Astrophysics Data System (ADS)
Wei, Z.; Chen, L.; Li, Z.; Ling, Y.; Li, J.
2015-12-01
Eastern-central China comprises a complex amalgamation of geotectonic blocks of different ages and undergone significant modification of lithosphere during the Meso-Cenozoic time. To better characterize its deep structure, we estimated the Moho depth and average Poisson's ratio of eastern-central China by H-κ stacking of receiver functions using teleseismic data collected from 1196 broadband stations. A coexistence of modified and preserved crust was revealed in eastern-central China, which was generally in Airy-type isostatic equilibrium. Crust is obviously thicker to the west of the North-South Gravity Lineament but exhibits complex variations in Poisson's ratio with an overall felsic to intermediate bulk crustal composition. Moho depth and Poisson's ratio show striking differences as compared to the surrounding areas in the rifts and tectonic boundary zones, where earthquakes usually occur. Similarities and differences in the Moho depth and average Poisson's ratio were observed among the Northeast China, North China Craton, South China, and the Qinling-Dabie Orogen as well as different areas within these blocks, which may result from their different evolutionary histories and strong tectonic-magma events since the Mesozoic. In addition, we observed an alteration of Moho depth by ~6 km and of Poisson's ratio by ~0.03 as well as striking E-W difference beneath and across the Xuefeng Mountains, suggesting that the Xuefeng Mountains may be a deep tectonic boundary between the eastern Yangtze Craton and western Cathaysia Block.
Detection of extrasolar planets by the large deployable reflector
NASA Technical Reports Server (NTRS)
Hollenbach, D. J.; Takahashi, T.
1984-01-01
The best wavelength for observing Jupiter-size planetary companions to stars other than the Sun is one at which a planet's thermal emission is strongest; typically this would occur in the far-infrared region. It is assumed that the orbiting infrared telescope used is diffraction-limited so that the resolution of the planet from the central star is accomplished in the wings of the star's Airy pattern. Proxima Centauri, Barnard's Star, Wolf 359, and Epsilon Eridani are just a few of the many nearest main-sequence stars that could be studied with the large deployable relfector (LDR). The detectability of a planet improves for warmer planets and less luminous stars; therefore, planets around white dwarfs and those young planets which have sufficient internal gravitational energy release so as to cause a significant increase in their temperatures are considered. If white dwarfs are as old as they are usually assumed to be (5-10 billion yr), then only the nearest white dwarf (Sirius B) is within the range of LDR. The Ursa Major cluster and Perseu cluster are within LDR's detection range mainly because of their proximity and young age, respectively.
2016-01-01
A conventional fluorescence microscope was previously constructed for simultaneous imaging of two colors to gain subdiffraction localization. The system is predicated on color separation of overlapping Airy discs, construction of matrices of Cartesian coordinates to determine locations as well as centers of the point spread functions of fluorophores. Quantum dots that are separated by as little as 10 nm were resolved in the x-y coordinates. Inter-fluorophore distances that vary by 10 nm could also be distinguished. Quantum dots are bright point light source emitters that excite with a single laser and can serve as a label for many biomolecules. Here, alterations in the method are described to test the ability to resolve Atto 488 and Atto 647 dyes attached to DNA origami at ~40 nm spacing intervals. Dual laser excitation is used in tandem with multi-wavelength bandpass filters. Notwithstanding challenges from reduced intensity in Atto labeled DNA origami helical bundles compared to quantum dots, preliminary data show a mean inter-fluorophore distance of 56 nm with a range (14-148 nm). The range closely matches published results with DNA origami with other methods of subdiffraction microscopy. Sub-diffraction simultaneous two-color imaging fluorescence microscopy acronymically christened (SSTIFM) is a simple, readily accessible, technique for measurement of inter-fluorophore distances in compartments less than 40 nm. Preliminary results with so called nanorulers are encouraging for use with other biomolecules. PMID:27307653
From the classical to the generalized von Karman and Marguerre-von Karman equations
NASA Astrophysics Data System (ADS)
Ciarlet, Philippe G.; Gratie, Liliana
2006-06-01
In this work, we describe and analyze two models that were recently proposed for modeling generalized von Karman plates and generalized Marguerre-von Karman shallow shells.First, we briefly review the "classical" von Karman and Marguerre-von Karman equations, their physical meaning, and their mathematical justification. We then consider the more general situation where only a portion of the lateral face of a nonlinearly elastic plate or shallow shell is subjected to boundary conditions of von Karman type, while the remaining portion is free. Using techniques from formal asymptotic analysis, we obtain in each case a two-dimensional boundary value problem that is analogous to, but is more general than, the classical equations.In particular, it is remarkable that the boundary conditions for the Airy function can still be determined on the entire boundary of the nonlinearly elastic plate or shallow shell solely from the data.Following recent joint works, we then reduce these more general equations to a single "cubic" operator equation, which generalizes an equation introduced by Berger and Fife, and whose sole unknown is the vertical displacement of the shell. We next adapt an elegant compactness method due to Lions for establishing the existence of a solution to this operator equation.
Stress inversion method and analysis of GPS array data
NASA Astrophysics Data System (ADS)
Hori, Muneo; Iinuma, Takeshi; Kato, Teruyuki
2008-01-01
The stress inversion method is developed to find a stress field which satisfies the equation of equilibrium for a body in a state of plane stress. When one stress-strain relation is known and data on the strain distribution on the body and traction along the boundary are provided, the method solves a well-posed problem, which is a linear boundary value problem for Airy's stress function, with the governing equation being the Poisson equation and the boundary conditions being of the Neumann type. The stress inversion method is applied to the Global Positioning System (GPS) array data of the Japanese Islands. The stress increment distribution, which is associated with the displacement increment measured by the GPS array, is computed, and it is found that the distribution is not uniform over the islands and that some regions have a relatively large increment. The elasticity inversion method is developed as an alternative to the stress inversion method; it is based on the assumption of linear elastic deformation with unknown elastic moduli and does not need boundary traction data, which are usually difficult to measure. This method is applied to the GPS array data of a small region in Japan to which the stress inversion method is not applicable. To cite this article: M. Hori et al., C. R. Mecanique 336 (2008).
Light Scattered from Polished Optical Surfaces: Wings of the Point Spread Function
NASA Technical Reports Server (NTRS)
Kenknight, C. E.
1984-01-01
Random figure errors from the polishing process plus particles on the main mirrors in a telescope cause an extended point spread function (PSF) declining approximately as the inverse square of the sine of the angle from a star from about 100 micro-rad to a right angle. The decline in at least one case, and probably in general, proceeds as the inverse cube at smaller angles where the usual focal plane aperture radius is chosen. The photometric error due to misalignment by one Airy ring spacing with an aperture of n rings depends on the net variance in the figure. It is approximately 60/(n+1)(3) when using the data of Kormendy (1973). A typical value is 6 x 10 to the -5th power per ring of misalignment with n = 100 rings. The encircled power may be modulated on a time scale of hours by parts per thousand in a wavelength dependent manner due to relative humidity effects on mirror dust. The scattering according to an inverse power law is due to a random walk in aberration height caused by a multitude of facets and slope errors left by the polishing process. A deviation from such a law at grazing emergence may permit monitoring the dust effects.
NASA Astrophysics Data System (ADS)
Tian, Bo; Wei, Guang-Mei; Zhang, Chun-Yi; Shan, Wen-Rui; Gao, Yi-Tian
2006-07-01
The variable-coefficient Korteweg de Vries (KdV)-typed models, although often hard to be studied, are of current interest in describing various real situations. Under investigation hereby is a large class of the generalized variable-coefficient KdV models with external-force and perturbed/dissipative terms. Recent examples of this class include those in blood vessels and circulatory system, arterial dynamics, trapped Bose Einstein condensates related to matter waves and nonlinear atom optics, Bose gas of impenetrable bosons with longitudinal confinement, rods of compressible hyperelastic material and semiconductor heterostructures with positonic phenomena. In this Letter, based on symbolic computation, four transformations are proposed from this class either to the cylindrical or standard KdV equation when the respective constraint holds. The constraints have nothing to do with the external-force term. Under those transformations, such analytic solutions as those with the Airy, Hermit and Jacobian elliptic functions can be obtained, including the solitonic profiles. The roles for the perturbed and external-force terms to play are observed and discussed. Investigations on this class can be performed through the properties of solutions of cylindrical and standard KdV equations.
A theoretical discussion on Vening Meinesz-Moritz inverse problem of isostasy
NASA Astrophysics Data System (ADS)
Eshagh, Mehdi
2016-12-01
The Moho surface can be determined according to isostatic theories, and among them, the recent Vening Meinesz-Moritz (VMM) theory of isostasy has been successfully applied for this purpose. In this paper, this method is studied from a theoretical prospective and its connection to the Airy-Heiskanen (AH) and Vening Meinesz original theories are presented. Jeffrey's inverse solution to isostasy is developed according to the recent developments of the VMM method and both are compared in similar situations. It is shown that they are generalizations of the AH model in a global and continuous domain. In the VMM spherical harmonic solution for Moho depth, the mean Moho depth contributes only to the zero-degree term of the series, while in Jeffrey's solution it contributes to all frequencies. In addition, the VMM spherical harmonic series is improved further so that the mean Moho can contribute to all frequencies of the solution. This modification makes the VMM global solution superior to the Jeffrey one, but in a global scale, the difference between both solutions is less than 3 km. Both solutions are asymptotically convergent and we present two methods to obtain smooth solutions for Moho from them.
Photographic image enhancement
NASA Technical Reports Server (NTRS)
Hite, Gerald E.
1990-01-01
Deblurring capabilities would significantly improve the scientific return from Space Shuttle crew-acquired images of the Earth and the safety of Space Shuttle missions. Deblurring techniques were developed and demonstrated on two digitized images that were blurred in different ways. The first was blurred by a Gaussian blurring function analogous to that caused by atmospheric turbulence, while the second was blurred by improper focussing. It was demonstrated, in both cases, that the nature of the blurring (Gaussian and Airy) and the appropriate parameters could be obtained from the Fourier transformation of their images. The difficulties posed by the presence of noise necessitated special consideration. It was demonstrated that a modified Wiener frequency filter judiciously constructed to avoid over emphasis of frequency regions dominated by noise resulted in substantially improved images. Several important areas of future research were identified. Two areas of particular promise are the extraction of blurring information directly from the spatial images and improved noise abatement form investigations of select spatial regions and the elimination of spike noise.
Dubois, D.F.; Hanssen, A.; Rose, H.A.; Russell, D.
1993-10-01
The predictions of strong Langmuir turbulence (SLT) theory are compared with radar observations of HF induced turbulence at Arecibo and Tromso. The altitude distribution of turbulence observed in the cold start experiments of Fejer et al. imply that the ionospheric electron density profile is modified by the induced turbulence. The preconditioned observations at Arecibo and the Tromso observations also appear to require a {open_quotes}disturbed{close_quotes} profile with several percent density fluctuations. With such density modifications postulated the authors conclude the SLT theory is in, at least, qualitative agreement with a large body of observations. Specifically SLT theory predicts, as part of a unified theory, and in distinction to the weak turbulence approximation, at least four unique physical signatures which can be compared to observations: (1) A caviton continuum plus free mode peak in the plasma line power spectrum near reflection altitude for Arecibo conditions. (2) A truncated decay-cascade spectrum at lower altitudes (or densities). (3) A continuous spectrum underlying the decay-cascade spectrum. (4) A zero frequency feature in the ion line power spectrum directly related to caviton dynamics. The authors find that there is sufficient ponderomotive pressure due to the Airy-layered, induced Langmuir turbulence, to modify the electron density profile in a manner consistent with the time behavior of unpreconditioned Arecibo observations. 59 refs., 14 figs.
Frederik Kaiser (1808-1872) and the Modernisation of Dutch Astronomy
NASA Astrophysics Data System (ADS)
van der Heijden, Petra
Frederik Kaiser was the director of Leiden Observatory from 1837 until his death in 1872. Educated by his German-born uncle Johan Frederik Keyser (1766-1823), who was a proficient amateur astronomer, Kaiser proved to be a real observational talent. Despite the poor conditions in which he worked, his observations soon rivalled with the best in the world. Kaiser's contributions to astronomical practice include the foundation of a new, completely up-to-date observatory building in Leiden, and the introduction of statistics and precision measurements in daily practice at the observatory. Moreover he was the author of several bestselling books on popular astronomy. Kaiser had an extensive correspondence with colleagues all over Europe, mostly in Germany. Correpondents include Airy, Argelander, Von Auwers, Bessel, Encke, John Herschel, LeVerrier, Von Littrow, Schumacher, Otto W. Struve, as well as several geodesists and instrument makers. Preliminary research indicates that Frederik Kaiser played a crucial role in the revival of Dutch astronomy in the second half of the 19th century. This project aims at analysing and explaining Kaiser's activities in science, institutionalisation and popularisation, in the context of national and international developments in 19th-century astronomy and scientific culture.
Star testing: a novel evaluation of intraocular lens optical quality
Mitchell, L; Molteno, A C B; Bevin, T H; Sanderson, G
2006-01-01
Background Despite the importance of optical quality of an intraocular lens (IOL) on visual outcomes following cataract surgery, objective data on their optical quality are not readily available, and manufacturing standards are industry regulated. The star test is a classic test of optical quality based on examination of the Airy disc and expanded diffraction rings of a point source of light, used mainly for telescope and microscope objectives. Methods A physical model eye cell allowed star testing of IOLs under conditions similar to the optical environment in which they operate. 18 IOLs were tested and results compared to actual images produced by these lenses in the model eye cell. Quantitative measures of star testing performance were developed. Results The optical performance of the IOLs varied, some performing very poorly. Most lenses (13/17) performed better in reverse orientation, while aberrations induced by the haptics of foldable IOLs were also detected. There was excellent correlation between actual images formed and star testing parameters. Conclusion Star testing IOLs was a novel biomedical application of a centuries old, inexpensive method. A concerning variation of optical quality was found, suggesting IOL optical performance data should be more readily available. Independent, authority mandated IOL optical quality standards should be developed, and results readily available to ophthalmologists. PMID:16622088
NASA Astrophysics Data System (ADS)
Maruyama, Takashi; Yusupov, Kamil; Akchurin, Adel
2016-02-01
The vertical ground motion of seismic surface waves launches acoustic waves into the atmosphere and induces ionospheric disturbances. Disturbances due to Rayleigh waves near the short-period Airy phase appear as wavy fluctuations in the virtual height of an ionogram and have a multiple-cusp signature (MCS) when the fluctuation amplitude is increased. An extremely developed MCS was observed at Kazan, Russia, after the 2010 M 8.8 Chile earthquake. The ionogram exhibited steep satellite traces for which the virtual heights increased rapidly with frequency starting near the top of cusps and continuing for 0.1-0.2 MHz. This complicated ionogram was analyzed by applying a ray tracing technique to the radio wave propagation in the ionosphere that was perturbed by acoustic waves. Acoustic wavefronts were inclined by the effects of finite Rayleigh wave velocity and sound speed in the thermosphere. The satellite echo traces were reproduced by oblique returns from the inclined wavefronts, in addition to the nearly vertical returns that are responsible for the main trace.
Coronagraphy with the AEOS High Order Adaptive Optics System
NASA Astrophysics Data System (ADS)
Lloyd, J. P.; Graham, J. R.; Kalas, P.; Oppenheimer, B. R.; Sivaramakrishnan, A.; Makidon, R. B.; Macintosh, B. A.; Max, C. E.; Baudoz, P.; Kuhn, J. R.; Potter, D.
2001-05-01
Adaptive Optics has recently become a widely used technique to acquire sensitive, diffraction limited images in the near infrared with large ground based telescopes. Most astronomical targets are faint; driving astronomical AO systems towards large subapertures; resulting in a compromise between guide star brightness, observing wavelength, resolution and Strehl ratio. Space surveilance systems have recently been developed that exploit high order adaptive optics systems to take diffraction limited images in visible light on 4 meter class telescopes on bright (V<8) targets. There is, however, a particular niche that can be exploited by turning these visible light space surveillance systems to astronomical use at infrared wavelengths. At the longer wavelengths, the strehl ratio rises dramatically, thus placing more light into the diffracted Airy pattern at the expense of the atmospheric halo. A coronagraph can be used to suppress the diffracted light, and observe faint companions and debris disks around nearby, bright stars. Observations of these very high contrast objects benefit greatly from much higher order adaptive optics systems than are presently available to the astronomical commnunity. The National Science Foundation and Air Force Office of Scientific Research is sponsoring a program to conduct astronomical observations at the AEOS facility. We are presently developing an astronomical coronagraph to be deployed at the Air Force AEOS facility. We describe the coronagraph, and discuss the advantages and limitations of ground based high order AO for high contrast imaging.
Astronomical coronagraphy with high-order adaptive optics systems
NASA Astrophysics Data System (ADS)
Lloyd, James P.; Graham, James R.; Kalas, Paul; Oppenheimer, Ben R.; Sivaramakrishnan, Anand; Makidon, Russell B.; Macintosh, Bruce A.; Max, Claire E.; Baudoz, Pierre; Kuhn, Jeff R.; Potter, Dan
2001-12-01
Space surveillance systems have recently been developed that exploit high order adaptive optics systems to take diffraction limited images in visible light on 4 meter class telescopes. Most astronomical targets are faint, thus driving astronomical AO systems towards larger subapertures, and thus longer observing wavelengths for diffraction limited imaging at moderate Strehl ratio. There is, however, a particular niche that can be exploited by turning these visible light space surveillance systems to astronomical use at infrared wavelengths. At the longer wavelengths, the Strehl ratio rises dramatically, thus placing more light into the diffracted Airy pattern compared to the atmospheric halo. A Lyot coronagraph can be used to suppress the diffracted light from an on axis star, and observe faint companions and debris disks around nearby, bright stars. These very high contrast objects can only be observed with much higher order adaptive optics systems than are presently available to the astronomical community. We describe simulations of high order adaptive optics coronagraphs, and outline a project to deploy an astronomical coronagraph at the Air Force AEOS facility at the Maui Space Surveillance System.
A Documentary History of the Discovery of Neptune
NASA Astrophysics Data System (ADS)
Waff, C. B.; Kollerstrom, N.
2001-12-01
The discovery of the planet Neptune by Johann Gottfried Galle on 23 September 1846 near the positions predicted by Urbain Jean Joseph Le Verrier and John Couch Adams has been justly considered by many the greatest achievement of Newtonian celestial mechanics. Aside from communications to societies and journals and a selection of letters published shortly after the discovery by British Astronomer Royal George Biddell Airy, however, contemporary documents (especially letters) concerning the discovery have in large part remained unpublished and scattered in numerous archives in England, France, the United States, Germany, and elsewhere. Partially in response to the longtime disappearance and fortunate recent recovery of the Royal Greenwich Observatory file of documents on the discovery, the authors of this paper have formed the project of editing and annotating for publication a chronologically ordered collection of documents relating to the prediction, discovery, and orbit determination of Neptune. A lengthy introductory essay that would summarize research on the Neptune discovery that has been conducted by various historians would accompany such a collection. This paper will outline the criteria that have been used for selecting the documents that will be published in the edition and describe some of the preliminary associated research findings of the authors.
The gabbro-eclogite phase transition and the elevation of mountain belts on Venus
NASA Technical Reports Server (NTRS)
Namiki, Noriyuki; Solomon, Sean C.
1993-01-01
The hypothesis is explored that the crust-mantle boundary of Venus is not in phase equilibrium but rather is rate-limited by the temperature-dependent volume diffusion of the slowest ionic species. The 1D thermal evolution problem is solved assuming that the mountains formed by uniform horizontal shortening of the crust and the lithospheric mantle at a constant rate. The time-dependent density structure and surface elevation are calculated by assuming a temperature-dependent reaction rate and local Airy isostatic compensation. For a horizontal strain rate of 10 exp -15/s or greater, the temperature increase at the base of the crust during mountain formation is modest to negligible, the deepening lower crust is metastable, and the surface elevation increases as the crust thickens. For strain rates less than 10 exp -16/s, crustal temperature increases with time because of internal heat production and the lower crust is more readily transformed to the dense eclogite assemblage. For such models, a maximum elevation is reached during crustal shortening.
How the Term "Shock Waves" Came Into Being
NASA Astrophysics Data System (ADS)
Fomin, N. A.
2016-07-01
The present paper considers the history of works on shock waves beginning from S. D. Poisson's publication in 1808. It expounds on the establishment of the Polytechnic School in Paris and its fellows and teachers — Gaspard Monge, Lazare Carnot, Joseph Louis Gay-Lussac, Simeon Denis Poisson, Henri Navier, Augustin Louis Cauchy, Joseph Liouville, Ademar de Saint-Venant, Henri Regnault, Pierre Dulong, Emile Jouguet, Pierre Duhem, and others. It also describes the participation in the development of the shock wave theory of young scientists from the universities of Cambridge, among which were George Airy, James Challis, Samuel Earnshaw, George Stokes, Lord Rayleigh, Lord Kelvin, and James Maxwell, as well as of scientists from the Göttingen University, Germany — Bernhard Riemann and Ernst Heinrich Weber. The pioneer works on shock waves of the Scottish engineer William Renkin, the French artillerist Pierre-Henri Hugoniot, German scientists August Toepler and Ernst Mach, and a Hungarian scientist Gyözö Zemplén are also considered.
Inverted Gabor holography principle for tailoring arbitrary shaped three-dimensional beams
Latychevskaia, Tatiana; Fink, Hans-Werner
2016-01-01
It is well known that by modifying the wavefront in a certain manner, the light intensity can be turned into a certain shape. However, all known light modulation techniques allow for limited light modifications only: focusing within a restricted region in space, shaping into a certain class of parametric curves along the optical axis or bending described by a quadratic-dependent deflection as in the case of Airy beams. We show a general case of classical light wavefront shaping that allows for intensity and phase redistribution into an arbitrary profile including pre-determined switching-off of the intensity. To create an arbitrary three-dimensional path of intensity, we represent the path as a sequence of closely packed individual point-like absorbers and simulate the in-line hologram of the created object set; when such a hologram is contrast inverted, thus giving rise to a diffractor, it creates the pre-determined three-dimensional path of intensity behind the diffractor under illumination. The crucial parameter for a smooth optical path is the sampling of the predetermined curves, which is given by the lateral and axial resolution of the optical system. We provide both, simulated and experimental results to demonstrate the power of this novel method. PMID:27199254
Completed Beltrami-Michell Formulation for Analyzing Radially Symmetrical Bodies
NASA Technical Reports Server (NTRS)
Kaljevic, Igor; Saigal, Sunil; Hopkins, Dale A.; Patnaik, Surya N.
1994-01-01
A force method formulation, the completed Beltrami-Michell formulation (CBMF), has been developed for analyzing boundary value problems in elastic continua. The CBMF is obtained by augmenting the classical Beltrami-Michell formulation with novel boundary compatibility conditions. It can analyze general elastic continua with stress, displacement, or mixed boundary conditions. The CBMF alleviates the limitations of the classical formulation, which can solve stress boundary value problems only. In this report, the CBMF is specialized for plates and shells. All equations of the CBMF, including the boundary compatibility conditions, are derived from the variational formulation of the integrated force method (IFM). These equations are defined only in terms of stresses. Their solution for kinematically stable elastic continua provides stress fields without any reference to displacements. In addition, a stress function formulation for plates and shells is developed by augmenting the classical Airy's formulation with boundary compatibility conditions expressed in terms of the stress function. The versatility of the CBMF and the augmented stress function formulation is demonstrated through analytical solutions of several mixed boundary value problems. The example problems include a composite circular plate and a composite circular cylindrical shell under the simultaneous actions of mechanical and thermal loads.
NASA Astrophysics Data System (ADS)
Stolk, Ward; Kaban, Mikhail; Beekman, Fred; Tesauro, Magdala; Mooney, Walter D.; Cloetingh, Sierd
2013-08-01
We propose a new methodology to obtain crustal models in areas where data is sparse and data spreading is heterogeneous. This new method involves both interpolating the depth to the Moho discontinuity between observations and estimating a velocity-depth curve for the crust at each interpolation location. The Moho observations are interpolated using a remove-compute-restore technique, used in for instance geodesy. Observations are corrected first for Airy type isostasy. The residual observations show less variation than the original observations, making interpolation more reliable. After interpolation, the applied correction is restored to the solution, leading to the final estimate of Moho depth. The crustal velocities have been estimated by fitting a velocity-depth curve through available data at each interpolation location. Uncertainty of the model is assessed, both for the Moho and the velocity model. The method has been applied successfully to Asia. The resulting crustal model is provided in digital form and can be used in various geophysical applications, for instance in assessing rheological properties and strength profiles of the lithosphere, the correcting gravity for the crustal effects, seismic tomography and geothermal modelling.
Yaitskova, Natalia; Dohlen, Kjetil; Dierickx, Philippe; Montoya, Luzma
2005-06-01
A study is presented of a Mach-Zehnder interferometer for the measurement of phasing errors of the type found in segmented telescopes. We show that with a pinhole much larger than the Airy disk and an optical path difference between the arms equal to a quarter of the wavelength, the interferometric signal is related to the second derivative of the wave front. In this condition the signal is produced mostly by the segmentation errors and is marginally sensitive to other aberrations including atmospheric turbulence. The signal has distinguishable symmetric and antisymmetric properties that are related to segment aberrations. We suggest using the antisymmetric component of the signal to retrieve piston, tip, and tilt. The symmetric component of the signal serves as an estimate of the measurement error. In this way we proceed with a study of the errors associated with the misalignment of the interferometer, the segment edge imperfections, and the nonaveraged atmospheric perturbations. The entire study is performed on a theoretical basis, and numerical simulations are used to cross check the analytical results.
Density-Functional Study of the Two-Dimensional Electron Gas at the Perovskite Titanate Interface
NASA Astrophysics Data System (ADS)
Nanda, Ranjit; Popovic, Zoran; Thulasi, Sunita; Satpathy, Sashi
2006-03-01
Oxide superlattices and microstructures hold the promise for creating a new class of devices with unprecedented functionalities. Density-functional studies^1 of the recently fabricated, lattice-matched perovskite titanates^2 (SrTiO3)n/(LaTiO3)m reveal a classic wedge-shaped potential well for the monolayer structure, originating from the Coulomb potential of a charged La sheet. The potential in turn confines the electrons in the Airy-function-localized states. This resulting two-dimensional electron gas may be described in terms of the simplified jellium model^3 and it describes reasonably well the observed charge modulation of the Ti atoms near the interface. Concerning magnetism, it is suppressed for the monolayer LaTiO3 structure, while in structures with a thicker LaTiO3 part, bulk antiferromagnetism is recovered, with a narrow transition region separating the magnetic LaTiO3 and the non-magnetic SrTiO3. 1. Z. S. Popovic and S. Satpathy, Phys. Rev. Lett. 94, 176805 (2005) 2. A. Ohtomo et al., Nature 419, 378 (2002) 3. S. Thulasi and S. Satpathy, Phys. Rev. B (2006)
A heat-pipe mechanism for volcanism and tectonics on Venus
NASA Technical Reports Server (NTRS)
Turcotte, D. L.
1989-01-01
A heat-pipe mechanism is proposed for the transport of heat through the lithosphere of Venus. This mechanism allows the crust and lithosphere on Venus to be greater than 150 km. thick. A thick basaltic crust on Venus is expected to transform eclogite at a depth of 60 to 80 km; the dense eclogite would contribute to lithospheric delamination that returns the crust to the interior of the planet completing the heat-pipe cycle. Topography and the associated gravity anomalies can be explained by Airy compensation of the thick crust. The principal observation that is contrary to this hypothesis is the mean age of the surface that is inferred from crater statistics; the minimum mean age is about 130 Myr and this implies an upper limit of 2 cubic kilometers per year for the surface volcanic flux. If the heat-pipe mechanism was applicable on the Earth in the Archean it would provide the thick lithosphere implied by isotopic data from diamonds.
NASA Astrophysics Data System (ADS)
Lardiere, Olivier; Labeyrie, Antoine; Mourard, Denis; Riaud, Pierre; Arnold, Luc; Dejonghe, Julien; Gillet, Sophie
2003-02-01
Only in the recent years did it become realized that multi-aperture interferometric arrays could provide direct snapshot images and coronagraphic images in a non-Fizeau mode. Whereas homothetic mapping of entrance pupil to exit pupil is useless when the aperture is higly diluted, a "densified-pupil" or "hypertelescope" imaging mode can concentrate most light into a high-resolution Airy peak. In addition to the luminosity gain, there is a contrast gain particularly valuable for stellar coronagraphy and exoplanets finding. The current VLTI is able to combine light from two telescopes coherently. In subsequent phases, a combiner is planned for applying closure phase with up to eight telescopes (UT and AT). The small number of apertures currently considered at the VLTI, does not take full advantage of hypertelescope imaging, but still performs significantly better than other observing modes (+3.8mag gain in comparison with Fizeau mode). We propose some possible optical scheme for a densified-pupil combiner for the VLTI. Beyond its science value, the proposed instrument can serve as a precursor for many-element post-VLTI hypertelescopes.
New separators at the ATLAS facility
NASA Astrophysics Data System (ADS)
Back, Birger; Agfa Collaboration; Airis Team
2015-10-01
Two new separators are being built for the ATLAS facility. The Argonne Gas-Filled Analyzer (AGFA) is a novel design consisting of a single quadrupole and a multipole magnet that has both dipole and quadrupole field components. The design allows for placing Gammasphere at the target position while providing a solid angle of ~ 22 msr for capturing recoil products emitted at zero degrees. This arrangement enables studies of prompt gamma ray emission from weakly populated trans-fermium nuclei and those near the doubly-magic N = Z = 50 shell closure measured in coincidence with the recoils registered by AGFA. The Argonne In-flight Radioactive Ion Separator (AIRIS) is a magnetic chicane that will be installed immediately downstream of the last ATLAS cryostat and serve to separate radioactive ion beams generated in flight at an upstream high intensity production target. These beams will be further purified by a downstream RF sweeper and transported into a number of target stations including HELIOS, the Enge spectrograph, the FMA and Gammasphere. This talk will present the status of these two projects. This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
Medical applications of phytoestrogens from the Thai herb Pueraria mirifica.
Malaivijitnond, Suchinda
2012-03-01
Pueraria mirifica Airy Shaw et Suvatabandhu is a medicinal plant endemic to Thailand. It has been used in Thai folklore medicine for its rejuvenating qualities in aged women and men for nearly one hundred years. Indeed, it has been claimed that P. mirifica contains active phytoestrogens (plant substances with estrogen-like activity). Using high performance liquid chromatography, at least 17 phytoestrogens, mainly isoflavones, have been isolated. Thus, fairly considerable scientific researches, both in vitro in cell lines and in vivo in various species of animals including humans, have been conducted to date to address its estrogenic activity on the reproductive organs, bones, cardiovascular diseases and other climacteric related symptoms. The antioxidative capacity and antiproliferative effect on tumor cell lines have also been assessed. In general, P. mirifica could be applicable for preventing, or as a therapeutic for, the symptoms related to estrogen deficiency in menopausal women as well as in andropausal men. However, the optimal doses for each desirable effect and the balance to avoid undesired side effects need to be calculated before use.
Light scattered from polished optical surfaces: Wings of the point spread function
NASA Astrophysics Data System (ADS)
Kenknight, C. E.
1984-11-01
Random figure errors from the polishing process plus particles on the main mirrors in a telescope cause an extended point spread function (PSF) declining approximately as the inverse square of the sine of the angle from a star from about 100 micro-rad to a right angle. The decline in at least one case, and probably in general, proceeds as the inverse cube at smaller angles where the usual focal plane aperture radius is chosen. The photometric error due to misalignment by one Airy ring spacing with an aperture of n rings depends on the net variance in the figure. It is approximately 60/(n+1)(3) when using the data of Kormendy (1973). A typical value is 6 x 10 to the -5th power per ring of misalignment with n = 100 rings. The encircled power may be modulated on a time scale of hours by parts per thousand in a wavelength dependent manner due to relative humidity effects on mirror dust. The scattering according to an inverse power law is due to a random walk in aberration height caused by a multitude of facets and slope errors left by the polishing process. A deviation from such a law at grazing emergence may permit monitoring the dust effects.
Scattering of wave packets on atoms in the Born approximation
NASA Astrophysics Data System (ADS)
Karlovets, D. V.; Kotkin, G. L.; Serbo, V. G.
2015-11-01
It has recently been demonstrated experimentally that 200 -300 keV electrons with the unusual spatial profiles can be produced and even focused to a subnanometer scale—namely, electrons carrying nonzero orbital angular momentum and also the so-called Airy beams. Since the wave functions of such electrons do not represent plane waves, the standard Born formula for scattering of them off a potential field is no longer applicable and, hence, needs modification. In the present paper, we address the generic problem of elastic scattering of a wave packet of a fast nonrelativistic particle off a potential field. We obtain simple and convenient formulas for a number of events and an effective cross section in such a scattering, which represent generalization of the Born formula for a case when finite sizes and spatial inhomogeneity of the initial packet should be taken into account. As a benchmark, we consider two simple models corresponding to scattering of a Gaussian wave packet on a Gaussian potential and on a hydrogen atom, and perform a detailed analysis of the effects brought about by the limited sizes of the incident beam and by the finite impact parameter between the potential center and the packet's axis.
Size distribution of ring polymers
Medalion, Shlomi; Aghion, Erez; Meirovitch, Hagai; Barkai, Eli; Kessler, David A.
2016-01-01
We present an exact solution for the distribution of sample averaged monomer to monomer distance of ring polymers. For non-interacting and local-interaction models these distributions correspond to the distribution of the area under the reflected Bessel bridge and the Bessel excursion respectively, and are shown to be identical in dimension d ≥ 2, albeit with pronounced finite size effects at the critical dimension, d = 2. A symmetry of the problem reveals that dimension d and 4 − d are equivalent, thus the celebrated Airy distribution describing the areal distribution of the d = 1 Brownian excursion describes also a polymer in three dimensions. For a self-avoiding polymer in dimension d we find numerically that the fluctuations of the scaled averaged distance are nearly identical in dimension d = 2, 3 and are well described to a first approximation by the non-interacting excursion model in dimension 5. PMID:27302596
Nanoscale contact-radius determination by spectral analysis of polymer roughness images.
Knoll, Armin W
2013-11-12
In spite of the long history of atomic force microscopy (AFM) imaging of soft materials such as polymers, little is known about the detailed effect of a finite tip size and applied force on the imaging performance on such materials. Here we exploit the defined scaling of roughness amplitudes on amorphous polymer films to determine the transfer function imposed by the imaging tip. The finite indentation of the nanometer-scale tip into the comparatively soft polymer surface leads to a finite contact area, which in turn effectively acts as a moving average filter for the surface roughness. In the power spectral density (PSD), this leads to an attenuation of the roughness amplitudes related to the Airy pattern known from light diffraction of a circular aperture. This transfer function is affected by the roughness-induced local modulation of the tip height and contact area, which is studied by performing simulations of the polymer roughness and the imaging process. We find that for typical polymer parameters and sharp tips the contact radius of the tip-sample contact can be recovered from the roughness spectrum. We experimentally verify and demonstrate the method by measuring the nanoscale contact radius as a function of applied load and travel distance on a highly cross-linked model polymer. The data are consistent with the Johnson-Kendall-Roberts (JKR) contact model and verifies its applicability at the nanometer scale. Using the model, quantitative values of the elastic sample parameters can be determined.
NASA Astrophysics Data System (ADS)
Wang, Weilai; Wu, Jianping; Fang, Lihua; Lai, Guijuan; Cai, Yan
2017-03-01
The sedimentary and crustal thicknesses and Poisson's ratios of the NE Tibetan Plateau and its adjacent regions are estimated by the h- κ stacking and CCP image of receiver functions from the data of 1,317 stations. The horizontal resolution of the obtained results is as high as 0.5° × 0.5°, which can be used for further high resolution model construction in the region. The crustal thicknesses from Airy's equilibrium are smaller than our results in the Sichuan Basin, Qilian tectonic belt, northern Alxa block and Qaidam Basin, which is consistent with the high densities in the mantle lithosphere and may indicate that the high-density lithosphere drags crust down overall. High Poisson's ratios and low velocity zones are found in the mid- and lower crust beneath eastern Qilian tectonic belt and the boundary areas of the Ordos block, indicating that partial melting may exist in these regions. Low Poisson's ratios and low-velocity anomalies are observed in the crust in the NE Tibetan Plateau, implying that the mafic lower crust is thinning or missing and that the mid- and lower crust does not exhibit melting or partial melting in the NE Tibetan Plateau, and weak flow layers are not likely to exist in this region.
Elastic scattering of {sup 16}O+{sup 16}O at energies E/A between 5 and 8 MeV
Nicoli, M. P.; Haas, F.; Freeman, R. M.; Aissaoui, N.; Beck, C.; Elanique, A.; Nouicer, R.; Morsad, A.; Szilner, S.; Basrak, Z.
1999-12-01
The elastic scattering of {sup 16}O+{sup 16}O has been measured at nine energies between E{sub lab}=75 and 124 MeV. The data cover up to 100 degree sign in the c.m. and can be described in terms of phenomenological and folding model potentials which reproduce the main features observed. In agreement with studies at higher energies in this and similar systems, refractive effects are present in the angular distributions at all energies. In particular, the passage of Airy minima through 90 degree sign at E{sub c.m.}=40, 47.5, and 62 MeV explains the deep minima observed in the excitation function. The real part of the optical potential is found to vary very little with energy over the studied interval, but the imaginary part shows a rapid change in its shape at incident energy about 90 MeV. Nonetheless, the energy dependence of the volume integral of the real and imaginary parts is in agreement with dispersion relation predictions. (c) 1999 The American Physical Society.
NASA Astrophysics Data System (ADS)
Joshi, Narahari V.; Medina, Honorio; Barboza, J. M.; Colantuoni, Gladys; Quintero, Maritza
2004-07-01
Chondrocytes, obtained from testosterone treated human articular cartilage, were examined by a recently developed Multiple Beam Interference Microscopy (MBIM) attached to a confocal set up, Video-enhanced differential interference microphotography and also by cinematography. In the MBIM, the intensity of the transmitted pattern is given by the Airy function which increases the contrast dramatically as the coefficient of the reflectance of the parallel plates increases. Moreover, in this configuration, the beam passes several times through a specific organelle and increases its optical path difference both because of the increase in the trajectory and refractive index (high density) of the organelle. The improved contrast enhances the resolving power of the system and makes visible several structural details of sub micron dimensions like nucleolus, retraction fibers, podia, etc. which are not possible to reveal with such a clarity by conventional techniques such as bright field, phase contrast or DIC. This technique permits to detect the oscillatory and rotational motions of unstained cilia for the first time. The frequency of oscillations was found to be 0.8 Hz.
An extended UTD analysis for the scattering and diffraction from cubic polynomial strips
NASA Technical Reports Server (NTRS)
Constantinides, E. D.; Marhefka, R. J.
1993-01-01
Spline and polynomial type surfaces are commonly used in high frequency modeling of complex structures such as aircraft, ships, reflectors, etc. It is therefore of interest to develop an efficient and accurate solution to describe the scattered fields from such surfaces. An extended Uniform Geometrical Theory of Diffraction (UTD) solution for the scattering and diffraction from perfectly conducting cubic polynomial strips is derived and involves the incomplete Airy integrals as canonical functions. This new solution is universal in nature and can be used to effectively describe the scattered fields from flat, strictly concave or convex, and concave convex boundaries containing edges. The classic UTD solution fails to describe the more complicated field behavior associated with higher order phase catastrophes and therefore a new set of uniform reflection and first-order edge diffraction coefficients is derived. Also, an additional diffraction coefficient associated with a zero-curvature (inflection) point is presented. Higher order effects such as double edge diffraction, creeping waves, and whispering gallery modes are not examined. The extended UTD solution is independent of the scatterer size and also provides useful physical insight into the various scattering and diffraction processes. Its accuracy is confirmed via comparison with some reference moment method results.
Steinlechner, Jessica; Jensen, Lars; Krüger, Christoph; Lastzka, Nico; Steinlechner, Sebastian; Schnabel, Roman
2012-03-10
We propose and demonstrate a new measurement technique for the optical absorption of high-reflection coatings. Our technique is based on photothermal self-phase modulation and exploits the deformation of cavity Airy peaks that occurs due to coating absorption of intracavity light. The mirror whose coating is under investigation needs to be the input mirror of a high-finesse cavity. Our example measurements were performed on a high-reflection SiO2-Ta2O5 coating in a three-mirror ring-cavity setup at a wavelength of 1064 nm. The optical absorption of the coating was determined to be α=(23.9±2.0)·10(-6) per coating. Our result is in excellent agreement with an independently performed laser calorimetry measurement that gave a value of α=(24.4±3.2)·10(-6) per coating. Since the self-phase modulation in our coating-absorption measurement affects mainly the propagation through the cavity input mirror, our measurement result is practically uninfluenced by the optical absorption of the other cavity mirrors.
Velocity fluctuations and energy amplification in laminar fluid flows
NASA Astrophysics Data System (ADS)
Ortiz de Zarate, Jose M.; Sengers, Jan V.
2008-11-01
We present a systematic procedure for evaluating the intrinsic velocity fluctuations and the resulting intrinsic energy amplification that are always present in laminar fluid flows. For this purpose we formulate a stochastic Orr-Sommerfeld equation and a stochastic Squire equation by applying a fluctuation-dissipation theorem for the random part of the dissipative stresses. From the solution of the stochastic Orr- Sommerfeld and Squire equations the intrinsic energy amplification can be deduced. As an illustration of the procedure we present an explicit solution for the case of planar Couette flow. We first solve the fluctuating hydrodynamics equations in the bulk, obtaining an exact representation of the spatial spectrum of the velocity fluctuations valid for large wave numbers. The resulting energy amplification is proportional to Re^3/2. Next, we show how to a good approximation confinement can be incorporated by a simple Galerkin projection technique. The effect of the boundary conditions is to reduce the energy amplification to a logarithmic dependence on Re. We shall also indicate how an exact solution for the case of confined geometries can be obtained by an expansion into a set of hydrodynamic modes, conveniently expressed in terms of Airy functions.
NASA Astrophysics Data System (ADS)
Bourget, P.; Veiga, C. H.; Vieira Martins, R.; Assus, P.; Colas, F.
In order to optimize the occulting process of a Lyot coronagraph and to provide a high dynamic range imaging, a new kind of occulting disk has been developed at the National Observatory of Rio de Janeiro. A mercury (Hg) drop glued onto an optical window by molecular cohesion and compressed by a pellicle film is used as the occulting disk. The minimum of the superficial tension potential function provides an optical precision (lambda/100) of the toric free surface of the mercury. This process provides a size control for the adaptation to the seeing conditions and to the apparent diameter of a resolved object, and in the case of adaptive optics, to the Airy diameter fraction needed. The occultation is a three dimensional process near the focal plane on the toric free surface that provides an apodization of the occultation. The Hg-Mask coronagraph has been projected for astrometric observations of faint satellites near to Jovian planets and works since 2000 at the 1.6 m telescope of the Pico dos Dias Observatory (OPD - Brazil).
Random geometry and the Kardar-Parisi-Zhang universality class
NASA Astrophysics Data System (ADS)
Santalla, Silvia N.; Rodríguez-Laguna, Javier; LaGatta, Tom; Cuerno, Rodolfo
2015-03-01
We consider a model of a quenched disordered geometry in which a random metric is defined on {{{R}}2}, which is flat on average and presents short-range correlations. We focus on the statistical properties of balls and geodesics, i.e., circles and straight lines. We show numerically that the roughness of a ball of radius R scales as {{R}χ }, with a fluctuation exponent χ ≃ 1/3, while the lateral spread of the minimizing geodesic between two points at a distance L grows as {{L}ξ }, with wandering exponent value ξ ≃ 2/3. Results on related first-passage percolation problems lead us to postulate that the statistics of balls in these random metrics belong to the Kardar-Parisi-Zhang universality class of surface kinetic roughening, with ξ and χ relating to critical exponents characterizing a corresponding interface growth process. Moreover, we check that the one-point and two-point correlators converge to the behavior expected for the Airy-2 process characterized by the Tracy-Widom (TW) probability distribution function of the largest eigenvalue of large random matrices in the Gaussian unitary ensemble (GUE). Nevertheless extreme-value statistics of ball coordinates are given by the TW distribution associated with random matrices in the Gaussian orthogonal ensemble. Furthermore, we also find TW-GUE statistics with good accuracy in arrival times.
Vorontsov, Mikhail; Filimonov, Grigory; Ovchinnikov, Vladimir; Polnau, Ernst; Lachinova, Svetlana; Weyrauch, Thomas; Mangano, Joseph
2016-05-20
The performance of two prominent laser beam projection system types is analyzed through wave-optics numerical simulations for various atmospheric turbulence conditions, propagation distances, and adaptive optics (AO) mitigation techniques. Comparisons are made between different configurations of both a conventional beam director (BD) using a monolithic-optics-based Cassegrain telescope and a fiber-array BD that uses an array of densely packed fiber collimators. The BD systems considered have equal input power and aperture diameters. The projected laser beam power inside the Airy size disk at the target plane is used as the performance metric. For the fiber-array system, both incoherent and coherent beam combining regimes are considered. We also present preliminary results of side-by-side atmospheric beam projection experiments over a 7-km propagation path using both the AO-enhanced beam projection system with a Cassegrain telescope and the coherent fiber-array BD composed of 21 densely packed fiber collimators. Both wave-optics numerical simulation and experimental results demonstrate that, for similar system architectures and turbulence conditions, coherent fiber-array systems are more efficient in mitigation of atmospheric turbulence effects and generation of a hit spot of the smallest possible size on a remotely located target.
Peripheral Jet Air Cushion Landing System Spanloader Aircraft. Volume II
1979-12-01
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Three-dimensional gravity modeling of the geologic structure of Long Valley caldera
Carle, S.F.
1988-11-10
A 48-mGal gravity low coincides with Long Valley caldera and is mainly attributed to low-density caldera fill. Gravity measurements by Unocal Geothermal have been integrated with U.S. Geological Survey data, vastly improving gravity station coverage throughout the caldera. A strong regional gravity trend is mainly attributed to isostasy. A ''best fitting'' (based on regional control of basement densities) Airy-Heiskanen isostatic model was used for the regional correction. A three-dimensional, multiple-unit gravity modeling program with iterative capabilities was developed to model the residual gravity. The density structure of Long Valley caldera and vicinity was modeled with 22 discrete density units, most of which were based on geologic units. Information from drill hole lithologies, surface geology, and structural geology interpretations constrain the model. Some important points revealed by the three-dimensional gravity modeling are that (1) the volume of ejected magma associated with the Bishop Tuff eruption is greater than previously thought, (2) the caldera structure is strongly influenced by precaldera topography and the extensions of major, active faults, (3) the main west ring fracture is coincident with the Inyo Domes--Mono Craters fracture system, (4) a relatively low-density region probably underlies the caldera, and (5) a silicic magma chamber may underlie Devils Postpile. copyright American Geophysical Union 1988
A heat pipe mechanism for volcanism and tectonics on Venus
Turcotte, D.L. )
1989-12-01
A heat pipe mechanism is proposed for the transport of heat through the lithosphere on Venus. This mechanism allows the crust and lithosphere on Venus to be greater than 150 km thick. A thick crust and thick lithosphere can explain the high observed topography and large associated gravity anomalies. For a 150-km-thick lithosphere the required volcanic flux on Venus is 200 km{sup 3}/yr; this is compared with a flux of 17 km{sup 3}/yr associated with the formation of the oceanic crust on Earth. A thick basaltic crust on Venus is expected to transform to eclogite at a depth of 60 to 80 km; the dense eclogite would contribute the lithospheric delamination that returns the crust to the interior of the planet completing the heat pipe cycle. Topography and the associated gravity anomalies can be explained by Airy compensation of the thick crust. The principal observation that is contrary to this hypothesis is the mean age of the surface that is inferred from crater statistics; the minimum mean age is about 130 Ma, and this implies an upper limit of 2 km{sup 3}/yr for the surface volcanic flux. If the heat pipe mechanism was applicable on Earth in the Archean, it would provide the thick lithosphere implied by isotopic data from diamonds.
The rainbow as interactive art: modeling the Elaisson Beauty installation at SFMOMA.
Sassen, Kenneth; Zhu, Jiang
2008-12-01
The rainbow has had an important role in religion, art, and science. Recently, artists have attempted to create indoor rainbow displays as interactive exhibitions of art, but based, nonetheless, on the principles of the scattering behavior of raindrops and the experience of experiment. Motivated by recently viewing the Beauty, 1993, installation at the San Francisco Museum of Modern Art (SFMOMA), we describe here a modeling program to explain the diversity of rainbow phenomena one can see visually in the gallery. The most significant impression gleaned in the museum is the acute spatial dependence of rainbow form on the viewing position in the presence of a local divergent light source (i.e., a floodlamp), in stark contrast to the unchangeable natural rainbow produced by an unimaginably distant Sun. This represents a case of the local (divergent) versus solar (parallel) light ray source distinction in atmospheric optical displays, which is one of a handful of anthropogenic versus natural situations responsible for optics displays that have been so far described. Through geometrical optics and Airy's theory simulations we show a rich relationship between the locally produced rainbow phenomena and the chamber equipment geometry and viewing position.
Dynamics of a plasma expanding into a uniform magnetic field
Gisler, G.; Lemons, D.S. )
1989-08-01
A heuristic model of an energetic plasma expanding into an initially uniform magnetic field is presented. In this model the plasma is cylindrically shaped, perfectly diamagnetic, and allowed to expand freely in the direction of the magnetic field. It results in a time evolution of the cylindrical radius described by Airy functions and parameterized by the plasma {beta}. For instance, the maximum extent of the radius scales as {beta}{sup 1/3} while the maximum radial deceleration scales as {beta}{sup {minus}1/3}. Time evolution and scaling are compared both with other models and with two-dimensional electromagnetic particle simulations. A spherically symmetric model is also found to agree well with the simulations and results in simpler expressions for the maximum radius and maximum radial deceleration. The larger deceleration obtained in these models, as compared with models that ignore the axial expansion, would shift toward longer wavelengths the peak growth of the instability thought to be responsible for the field-aligned structures seen in the Active Magnetospheric Particle Tracer Explorers (AMPTE) magnetotail releases. {copyright} American Geophysical Union 1989
Subsystem functional and the missing ingredient of confinement physics in density functionals.
Armiento, Rickard Roberto; Mattsson, Ann Elisabet; Hao, Feng
2010-08-01
The subsystem functional scheme is a promising approach recently proposed for constructing exchange-correlation density functionals. In this scheme, the physics in each part of real materials is described by mapping to a characteristic model system. The 'confinement physics,' an essential physical ingredient that has been left out in present functionals, is studied by employing the harmonic-oscillator (HO) gas model. By performing the potential {yields} density and the density {yields} exchange energy per particle mappings based on two model systems characterizing the physics in the interior (uniform electron-gas model) and surface regions (Airy gas model) of materials for the HO gases, we show that the confinement physics emerges when only the lowest subband of the HO gas is occupied by electrons. We examine the approximations of the exchange energy by several state-of-the-art functionals for the HO gas, and none of them produces adequate accuracy in the confinement dominated cases. A generic functional that incorporates the description of the confinement physics is needed.
Spherical harmonic modelling to ultra-high degree of Bouguer and isostatic anomalies
NASA Astrophysics Data System (ADS)
Balmino, G.; Vales, N.; Bonvalot, S.; Briais, A.
2012-07-01
The availability of high-resolution global digital elevation data sets has raised a growing interest in the feasibility of obtaining their spherical harmonic representation at matching resolution, and from there in the modelling of induced gravity perturbations. We have therefore estimated spherical Bouguer and Airy isostatic anomalies whose spherical harmonic models are derived from the Earth's topography harmonic expansion. These spherical anomalies differ from the classical planar ones and may be used in the context of new applications. We succeeded in meeting a number of challenges to build spherical harmonic models with no theoretical limitation on the resolution. A specific algorithm was developed to enable the computation of associated Legendre functions to any degree and order. It was successfully tested up to degree 32,400. All analyses and syntheses were performed, in 64 bits arithmetic and with semi-empirical control of the significant terms to prevent from calculus underflows and overflows, according to IEEE limitations, also in preserving the speed of a specific regular grid processing scheme. Finally, the continuation from the reference ellipsoid's surface to the Earth's surface was performed by high-order Taylor expansion with all grids of required partial derivatives being computed in parallel. The main application was the production of a 1' × 1' equiangular global Bouguer anomaly grid which was computed by spherical harmonic analysis of the Earth's topography-bathymetry ETOPO1 data set up to degree and order 10,800, taking into account the precise boundaries and densities of major lakes and inner seas, with their own altitude, polar caps with bedrock information, and land areas below sea level. The harmonic coefficients for each entity were derived by analyzing the corresponding ETOPO1 part, and free surface data when required, at one arc minute resolution. The following approximations were made: the land, ocean and ice cap gravity spherical
GMTNIRS: progress toward the Giant Magellan Telescope near-infrared spectrograph
NASA Astrophysics Data System (ADS)
Jaffe, Daniel T.; Barnes, Stuart; Brooks, Cynthia; Lee, Hanshin; Mace, Gregory; Pak, Soojong; Park, Byeong-Gon; Park, Chan
2016-08-01
GMTNIRS is a first-generation instrument for the Giant Magellan Telescope. It is a high-resolution spectrograph that will cover the 1.15-5.3 μm range in a single exposure with R=60,000 in the J, H, and K bands and R=85,000 in the L and M bands. It resides on the GMT's rotating instrument platform and employs the facility adaptive optics system. The GMTNIRS design is evolving in response to emerging science problems, particularly in the area of exoplanet atmospheres. Our design revisions also derive lessons from GMTNIRS' highly successful forerunner instrument, IGRINS. Technical changes also drive evolution of the design. It has proven impractical to manufacture 200mm long immersion gratings at the necessary precision. The success of primary mirror phasing efforts has removed the need for a very wide entrance slit that we would have needed to accommodate the Airy pattern of individual segments at the shortest operating wavelengths. The high efficiency of our double-side coated JWST grisms introduces the possibility of transmissive cross-dispersers at L and M. These changes move us toward a design with almost the same R as presented in our previous work but with a much more compact physical envelope. We will report on the optimization of the instrument design with these technical changes in mind. We are also producing the critical Si immersion gratings. The grating production is well under way and includes manufacture of H and K gratings and process development for the precision needed in the J band and for the manufacture of larger gratings for the L and M band. The development of GMTNIRS is on track with the results from IGRINS and the progress in the lab giving us substantial assurance that the new instrument can meet its performance goals.
Seismological implications of a lithospheric low seismic velocity zone in Mars
NASA Astrophysics Data System (ADS)
Zheng, Yingcai; Nimmo, Francis; Lay, Thorne
2015-03-01
Most seismological models for the interior of Mars lack an upper mantle low velocity zone. However, there is expected to be a large thermal gradient across the stagnant conductive lid (lithosphere) of Mars. This gradient should tend to decrease elastic wave velocities with increasing depth, with this effect dominating the opposing tendency caused by increasing pressure with depth because Mars has low gravity. An upper mantle lithosphere with a low velocity zone (LVZ) beneath a thin high velocity "seismic lid" is thus predicted. The upcoming NASA InSight mission includes a three-component seismometer, which should provide the first opportunity to directly detect any lithospheric LVZ in Mars. Seismic wavefields expected for Mars mantle velocity structures with or without a strong LVZ are very distinct. The LVZ models predict shadow zones for high-frequency seismic body wave phases such as P, S, PP and SS, etc. The most diagnostic waves that can be used to evaluate presence of a lithospheric LVZ given a single seismometer are intermediate-period global surface waves, which travel along the great circle from a seismic source to the seismometer. An LVZ produces distinctive dispersion, with a Rayleigh wave Airy phase around 100 s period and very different surface wave seismograms compared to a model with no LVZ. Even a single observation of long-period surface waves from a known range can be diagnostic of the lithospheric structure. Establishing the existence of an LVZ has major implications for thermal evolution, volatile content and internal dynamics of the planet.
InSight detection of a Lithospheric Low Seismic Velocity Zone in Mars
NASA Astrophysics Data System (ADS)
Zheng, Y.; Nimmo, F.; Lay, T.
2014-12-01
Most seismological models for the interior of Mars lack an upper mantle low velocity zone. However, there is expected to be a large thermal gradient across the stagnant conductive lid (lithosphere) of Mars. This gradient should tend to decrease elastic wave velocities with increasing depth, with this effect dominating the opposing tendency caused by increasing pressure with depth because Mars has low gravity. An upper mantle lithosphere with a low velocity zone (LVZ) beneath a thin high velocity "seismic lid" is thus predicted. The upcoming NASA InSight mission includes a three-component seismometer, which should provide the first opportunity to directly detect any lithospheric LVZ in Mars. Seismic wavefields expected for Mars mantle velocity structures with or without a strong LVZ are very distinct and may be distinguished by observing a modest number of seismic sources at different epicentral ranges. The LVZ models predict shadow zones for high-frequency seismic body wave phases such as P, S, PP and SS, etc. The most diagnostic waves that can be used to evaluate presence of a lithospheric LVZ given a single seismometer are intermediate period surface waves, which travel along the great circle from a seismic source to the seismometer along both minor- and (if the source is large enough) major-arc directions. An LVZ produces distinctive dispersion, with a Rayleigh wave Airy phase around 100 s period and very different surface wave seismograms compared to a model with no LVZ. Even a single observation of long-period surface waves from a known range can be diagnostic of the lithospheric structure. Establishing the existence of an LVZ has major implications for thermal evolution, volatile content and internal dynamics of the planet.
Lan, Gongpu; Li, Guoqiang
2017-01-01
Nonlinear sampling of the interferograms in wavenumber (k) space degrades the depth-dependent signal sensitivity in conventional spectral domain optical coherence tomography (SD-OCT). Here we report a linear-in-wavenumber (k-space) spectrometer for an ultra-broad bandwidth (760 nm–920 nm) SD-OCT, whereby a combination of a grating and a prism serves as the dispersion group. Quantitative ray tracing is applied to optimize the linearity and minimize the optical path differences for the dispersed wavenumbers. Zemax simulation is used to fit the point spread functions to the rectangular shape of the pixels of the line-scan camera and to improve the pixel sampling rates. An experimental SD-OCT is built to test and compare the performance of the k-space spectrometer with that of a conventional one. Design results demonstrate that this k-space spectrometer can reduce the nonlinearity error in k-space from 14.86% to 0.47% (by approximately 30 times) compared to the conventional spectrometer. The 95% confidence interval for RMS diameters is 5.48 ± 1.76 μm—significantly smaller than both the pixel size (14 μm × 28 μm) and the Airy disc (25.82 μm in diameter, calculated at the wavenumber of 7.548 μm−1). Test results demonstrate that the fall-off curve from the k-space spectrometer exhibits much less decay (maximum as −5.20 dB) than the conventional spectrometer (maximum as –16.84 dB) over the whole imaging depth (2.2 mm). PMID:28266502
Imaging of single-chromophore molecules in aqueous solution near a fused-silica interface
NASA Astrophysics Data System (ADS)
Davis, Lloyd M.; Parker, Wesley C.; Ball, David A.; Williams, John G.; Bashford, Greg R.; Sheaff, Pamela; Eckles, Robert D.; Lamb, Don T.; Middendorf, Lyle R.
2001-04-01
Single molecules of unconjugated Bodipy-Texas Red (BTR), BTR-dimer, and BTR conjugated to cysteine, in aqueous solutions are imaged using total-internal-reflection excitation and through-sample collection of fluorescence onto an intensified CCD camera, or a back-illuminated frame transfer CCD. The sample excitation is provided by the beam from a continuous-wave krypton ion laser, or a synchronously-pumped dye laser, operating at 568 nm. In order to essentially freeze molecular motion due to diffusion and thereby enhance image contrast, the laser beam is first passed through a mechanical shutter, which yields a 3-millisecond laser exposure for each camera frame. The laser beam strikes the fused-silica/sample interface at an angle exceeding the critical angle by about 1 degree. The resultant evanescent wave penetrates into the sample a depth of approximately 0.3 microns. Fluorescence from the thin plane of illumination is then imaged onto the camera by a water immersion apochromat (NA 1.2, WD 0.2mm). A Raman notch filter blocks Rayleigh and specular laser scatter and a band-pass-filter blocks most Raman light scatter that originates from the solvent. Single molecules that have diffused into the evanescent zone at the time of laser exposure yield near-diffraction-limited Airy disk images with diameters of ~5 pixels. While most molecules diffuse out of the evanescent zone before the next laser exposure, stationary or slowly moving molecules persisting over several frames, and blinking of such molecules are occasionally observed.
Energy-efficient heat recovery systems for air conditioning of indoor swimming pools
Elsayed, M.M.; El-Refaee, M.M.; Borhan, Y.A.
1997-12-31
Analysis of a conventional air-conditioning system for indoor swimming pools during the summer season is presented. The analysis showed that the cooling load is characterized by a large latent heat fraction. As a result, a reheating process must be used downstream of the cooling coil to achieve the proper design comfort condition in the pool area. This, in turn, increases the energy requirement per unit cooling load of the pool. Two heat recovery systems are proposed to reduce this energy. In the first system, ambient air is used for the reheating process in an air-to-air heat exchanger. In the second system, mixed air--recirculated and ambient air--is used for the reheating process. Heat recovery efficiency is defined as an index of the energy savings resulting from the use of the heat recovery system compared to that of a conventional air-conditioning system. At a wide range of ambient conditions it is found that the energy savings could be up to 70% of the energy required to operate a conventional air-conditioning system. A parametric study was carried out to size the air-to-air heat exchanger associated with these heat recovery systems, and the results showed that a heat exchanger having an effectiveness of 0.5 would give satisfactory results. The proposed heat recovery systems are also compared to the case of reheating using the heat rejection from the condenser of the refrigeration machine. The comparison showed that the proposed systems save more energy than reheating using the condenser heat. A typical case study is given to demonstrate the savings in energy consumption when these systems are used.
Analytic description of high-order harmonic generation by atoms in a two-color laser field
Frolov, M. V.; Manakov, N. L.; Silaev, A. A.; Vvedenskii, N. V.
2010-06-15
A closed-form analytic formula describing high-order harmonic generation (HHG) in a two-color field of frequencies {omega} and 2{omega} is derived quantum mechanically in the low-frequency (tunneling) limit for an electron bound by a short-range potential and generalized to the case of an active electron in a neutral atom. The HHG rates are presented as a product of an electron wave packet describing the ionization of an active electron and its propagation in a laser field up to the recombination event and an atom-specific cross section of the electron's photorecombination. In contrast to the case of a monochromatic laser pulse [Frolov et al., Phys. Rev. Lett. 102, 243901 (2009)], the two-color wave packet involves the interference of two terms (involving the Airy function) that describe the emission of harmonics during the first and second half-cycles of the fundamental laser cycle and give rise to the two-plateau structures in the HHG spectra. For the case of the H atom, we show that our analytic results are in good agreement with those obtained from a numerical solution of the three-dimensional time-dependent Schroedinger equation. The factorization formula is used for describing the dependence of HHG rates for inert gases on the relative phase and intensities of the {omega} and 2{omega} components of a laser field. It is shown that atomic structure (including electron correlation) effects can modify substantially the two-color HHG spectra of inert gases.
NASA Astrophysics Data System (ADS)
Rocco, Alessandra S.; Coppola, Giuseppe; Ferraro, Pietro; Foti, Giuseppe; Iodice, Mario
2004-09-01
Optical fiber sensors are the ideal system to monitor "smart structures" and on-site/real time stress measurements: they can be in fact easily embedded or attached to the structures under test and are not affected by electro- magnetic noise. In particular a signal from a Fiber Bragg grating sensor (FBG) may be processed such that its information remains immune to optical power fluctuations. Different interrogation methods can be used for reading out Bragg wavelength shifts. In this paper we propose a very simple interferometric method for interrogating FBG sensors, based on bi-polished silicon sample acting like an etalon tuneable filter (ETF). The Bragg wavelength shift can be evaluated by analyzing the spectral response of signal reflected by the FBG sensor and filtered by the ETF that is continuously and rapidly tuned. Tuning was obtained by rotating the ETF. Variation in the strain at the FBG causes a phase shift in the analyzed signal. The overall spectral signal, collected with time, consists in an interferometric figure which finesse and fringe contrast depending on the geometrical sizes and facets reflectivity of the silicon sample. The fringe pattern, expressed by the Airy's formula, depends on the wavelength l of the incident radiation and on the angle of incidence. The phase of fringe pattern can be retrieved by a standard FFT method giving quantitative measurements of the quasi-static strain variation sensed by the FBG. In this way, the method allows a valuable visualization of the time-evolution of the incremental strain applied to the FBG. Principle of functioning of this method is described and first results obtained employing such configuration, are reported.
Adaptive optics scanning ophthalmoscopy with annular pupils.
Sulai, Yusufu N; Dubra, Alfredo
2012-07-01
Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing of the autocorrelation central lobe (between 7 and 12%), and the increase in manual and automated photoreceptor counts (8 to 20% more cones and 11 to 29% more rods). It was observed that the use of annular pupils with large inner radii can result in multi-modal cone photoreceptor intensity profiles. The effect of the annular masks on the average photoreceptor intensity is consistent with the Stiles-Crawford effect (SCE). This indicates that combinations of images of the same photoreceptors with different apodization configurations and/or annular masks can be used to distinguish cones from rods, even when the former have complex multi-modal intensity profiles. In addition to narrowing the point spread function transversally, the use of annular apodizing masks also elongates it axially, a fact that can be used for extending the depth of focus of techniques such as adaptive optics optical coherence tomography (AOOCT). Finally, the positive results from this work suggest that annular pupil apodization could be used in refractive or catadioptric adaptive optics ophthalmoscopes to mitigate undesired back-reflections.
30 Doradus: The Low-Mass Stars
NASA Astrophysics Data System (ADS)
Zinnecker, H.; Brandl, B.; Brandner, W.; Moneti, A.; Hunter, D.
We have obtained HST/NICMOS H-band images of the central 1'x1' field around the R136 starburst cluster in the 30 Doradus HII region, in an attempt to reveal the presence (or absence) of a low-mass stellar population (M < 1 Mo). We will discuss the fascinating prospect of 30 Dor/R136 being a proto-globular cluster and a template starburst unit. At the time of writing, we are still working to determine which method and photometry package is best suited to our 0.15" NICMOS images, which are characterised by extreme crowding in the cluster center and a peculiar and slightly undersampled NICMOS PSF. The main difficulty with the PSF is identifying the many "dots" that appear outside the Airy ring as PSF features and not as faint stars. Prelimininary analysis suggests that the H-band luminosity function rises at least until H = 20 (2 Mo). We have detected numerous stars with 20.0 < H < 22.5 (the latter corresponding to 0.4 Mo) beyond about 7" from the cluster centre, but we have not yet determined the completeness in that magnitude range, and we are not yet in a position to make a statement about the shape of the H-band luminosity function there. We have combined our infrared data with the optical WFPC2 images of Hunter et al. (1995) to produce a VIH 3-colour image of the central 30" x 30" area. The result clearly shows unexpected patches of extinction, with one patch only about 5" from the cluster core.
NASA Astrophysics Data System (ADS)
Lan, Gongpu; Li, Guoqiang
2017-03-01
Nonlinear sampling of the interferograms in wavenumber (k) space degrades the depth-dependent signal sensitivity in conventional spectral domain optical coherence tomography (SD-OCT). Here we report a linear-in-wavenumber (k-space) spectrometer for an ultra-broad bandwidth (760 nm–920 nm) SD-OCT, whereby a combination of a grating and a prism serves as the dispersion group. Quantitative ray tracing is applied to optimize the linearity and minimize the optical path differences for the dispersed wavenumbers. Zemax simulation is used to fit the point spread functions to the rectangular shape of the pixels of the line-scan camera and to improve the pixel sampling rates. An experimental SD-OCT is built to test and compare the performance of the k-space spectrometer with that of a conventional one. Design results demonstrate that this k-space spectrometer can reduce the nonlinearity error in k-space from 14.86% to 0.47% (by approximately 30 times) compared to the conventional spectrometer. The 95% confidence interval for RMS diameters is 5.48 ± 1.76 μm—significantly smaller than both the pixel size (14 μm × 28 μm) and the Airy disc (25.82 μm in diameter, calculated at the wavenumber of 7.548 μm‑1). Test results demonstrate that the fall-off curve from the k-space spectrometer exhibits much less decay (maximum as ‑5.20 dB) than the conventional spectrometer (maximum as –16.84 dB) over the whole imaging depth (2.2 mm).
Structure and isostatic compensation of the Comorin Ridge, north central Indian Ocean
NASA Astrophysics Data System (ADS)
Sreejith, K. M.; Krishna, K. S.; Bansal, A. R.
2008-11-01
Bathymetry, gravity and magnetic data (about 9200 lkm) of the Comorin Ridge, north central Indian Ocean were investigated using the transfer function and forward model techniques to understand the mode of isostatic compensation and origin of the ridge. The ridge extends for about 500 km in NNW-SSE direction and associates with low-amplitude gravity anomalies ranging from 25 to 30 mGal compared to the ridge relief, suggesting that the anomalies are compensated at deeper depths. From Admittance analysis an Airy model or local compensation with an elastic plate thickness (Te) of about 3 km and crust thickness (t) of 15-20 km are suggested for the southern part of the Comorin Ridge (south of 5°N), whereas for the northern part a flexural plate model with an elastic thickness of about 15 km is obtained. Admittance analysis together with the results from gravity forward modelling reveal that the south part was emplaced on relatively weak oceanic crust with both surface and subsurface loading, while the north part was emplaced on the continental crust. Based on present studies and published plate kinematic models we interpret that the Comorin Ridge was evolved at about 90 Ma during the rift stage of Madagascar from the southwest of India. We have also demarcated the continent-ocean boundary (COB) west of Sri Lanka and southern tip of India, which runs across the strike of the ridge, placing the northern part of the ridge on continent and southern part on oceanic crust. On the southern part of the ridge eastern flank is steep-faulted up to 0.6 km and is controlled by the 79°E FZ and then by COB.
Tailoring complex optical fields via anisotropic microstructures (Presentation Recording)
NASA Astrophysics Data System (ADS)
Lu, Yan-Qing; Hu, Wei; Cui, Guo-Xin
2015-10-01
In recent years, complex optical fields with spatially inhomogeneous phases, polarizations and optical singularities have drawn many research interests. Many novel effects have been predicted and demonstrated for light beams with these unconventional states in both linear and nonlinear optics regimes. Although local optical phase could be controlled directly or through hologram structures in isotropic materials such as glasses, optical anisotropy is still required for manipulating polarization states and wavelengths. The anisotropy could be either intrinsic such as in crystals/liquid crystals (LCs) or the induced birefringence from dielectric or metallic structures. In this talk, we will briefly review some of our attempts in tailoring complex optical fields via anisotropic microstructures. We developed a micro-photo-patterning system that could generate complex micro-images then further guides the arbitrary local LC directors. Due to the electro-optically (EO) tunable anisotropy of LC, various reconfigurable complex optical fields such as optical vortices (OVs), multiplexed OVs, OV array, Airy beams and vector beams are obtained. Different LC modes such as homogeneous alignment nematic, hybrid alignment nematic and even blue phase LCs are adopted to optimize the static and dynamic beam characteristics depending on application circumstances. We are also trying to extend our approaches to new wavelength bands, such as mid-infrared and even THz ranges. Some preliminary results are obtained. In addition, based on our recently developed local poling techniques for ferroelectric crystals, we will also discuss and demonstrate the nonlinear complex optical field conversion in Lithium Niobate wafers with patterned ferroelectric domain structures.
Planet Formation Instrument for the Thirty Meter Telescope
Macintosh, B; Troy, M; Graham, J; Doyon, R
2006-02-22
In the closing years of the 20th Century humankind began its exploration of the planetary systems in the solar neighborhood. Precision radial velocity measurements have now yielded the discovery of over 160 planets. Direct imaging of these planets, as opposed to detection of the effects of orbital motion on their parent star, is now feasible, and the first young planet in a wide orbit may have been detected using adaptive optics systems. Gemini and the VLT are building the first generation of high contrast adaptive optics systems, which deliver planet-imaging performance within few Airy rings of the host star. These systems will make the first surveys of the outer regions of solar systems by detecting the self-luminous radiation of young planets. These instruments will establish whether Jovian planets form predominantly through 'top-down' (global gravitational instability) or 'bottom-up' (core accretion) processes. The 8-m 'extreme' AO systems cannot see close enough to the host stars to image Doppler planets, and they cannot reach the relatively distant, young clusters and associations where planets are forming. The Planet Formation Instrument will use the nearly four-fold improved angular resolution of TMT to peer into the inner solar systems of Doppler-planet bearing stars to yield a unified sample of planets with known Keplerian orbital elements and atmospheric properties. In star formation regions, where T Tauri stars (young solar type stars) are found in abundance, PFI can see into the snow line, where the icy cores of planets like Jupiter must have formed. Thus, TMT will be the first facility to witness the formation of new planets.
A very small astrometry satellite mission: Nano-JASMINE .
NASA Astrophysics Data System (ADS)
Kobayashi, Yukiyasu; Gouda, Naoteru; Tsujimoto, Takuji; Yano, Taihei; Suganuma, Masahiro; Yamauchi, Masahiro; Takato, Naruhisa; Miyazaki, Satoshi; Yamada, Yoshiyuki; Sako, Nobutada; Nakasuka, Shin'ichi
The current status of the nano-JASMINE project is presented. Nano-JASMINE-a very small satellite weighing less than 10 kg-aims to carry out astrometry measurements of nearby bright stars. This satellite adopts the same observation technique that was used by the HIPPARCOS satellite. In this technique, simultaneous measurements in two different fields of view separated by an angle that is greater than 90 degrees are carried out; these measurements are performed in the course of continuous scanning observations of the entire sky. This technique enables us to distinguish between an irregularity in the spin velocity and the distribution of stellar positions. There is a major technical difference between the nano-JASMINE and the HIPPARCOS satellites-the utilization of a CCD sensor in nano-JASMINE that makes it possible to achieve an astrometry accuracy comparable to that achieved by HIPPARCOS by using an extremely small telescope. We have developed a prototype of the observation system and evaluated its performance. The telescope (5cm) including a beam combiner composed entirely of aluminum. The telescope is based on the standard Ritchey-Chretien optical system and has a composite f-ratio of 33 that enables the matching of the Airy disk size to three times the CCD pixel size of 15um. A full depletion CCD will be used in the time delay integration (TDI) mode in order to efficiently survey the whole sky in wavelengths including the near infrared. The nano-JASMINE satellite is being developed as a piggyback system and is scheduled for launch in 2008. We expect the satellite to measure the position and proper motion of bright stars (mz < 8.3) with an accuracy of 1 mas, this is comparable to the accuracy achieved with the HIPPARCOS satellite.
A very small astrometry satellite mission: Nano-JASMINE
NASA Astrophysics Data System (ADS)
Kobayashi, Y.; Gouda, G.; Tsujimoto, T.; Yano, T.; Suganuma, M.; Yamauchi, M.; Takato, N.; Miyazaki, S.; Yamada, Y.; Sako, N.; Nakasuka, S.
2006-08-01
The current status of the nano-JASMINE project is presented. Nano-JASMINE--a very small satellite weighing less than 10 kg--aims to carry out astrometry measurements of nearby bright stars. This satellite adopts the same observation technique that was used by the HIPPARCOS satellite. In this technique, simultaneous measurements in two different fields of view separated by an angle that is greater than 90 degrees are carried out; these measurements are performed in the course of continuous scanning observations of the entire sky. This technique enables us to distinguish between an irregularity in the spin velocity and the distribution of stellar positions. There is a major technical difference between the nano-JASMINE and the HIPPARCOS satellites--the utilization of a CCD sensor in nano-JASMINE that makes it possible to achieve an astrometry accuracy comparable to that achieved by HIPPARCOS by using an extremely small telescope. We developed a prototype of the observation system and evaluated its performance. The telescope (5cm) including a beam combiner composed entirely of aluminum. The telescope is based on the standard Ritchey-Chretien optical system and has a composite f-ratio of 33 that enables the matching of the Airy disk size to three times the CCD pixel size of 15um. A full depletion CCD will be used in the time delay integration (TDI) mode in order to efficiently survey the whole sky in wavelengths including the near infrared. The nano-JASMINE satellite is being developed as a piggyback system and is [S: scheduled for launch in 2008. We expect the satellite to measure the position and proper motion of bright stars (mz< 8.3) with an accuracy of 1 mas, this is comparable to the accuracy achieved with the HIPPARCOS satellite.
Nano-JASMINE: a 10-kilogram satellite for space astrometry
NASA Astrophysics Data System (ADS)
Kobayashi, Yukiyasu; Gouda, Naoteru; Tsujimoto, Takuji; Yano, Taihei; Suganuma, Masahiro; Yamauchi, Masahiro; Takato, Naruhisa; Miyazaki, Satoshi; Yamada, Yoshiyuki; Sako, Nobutada; Nakasuka, Shin'ichi
2006-06-01
The current status of the nano-JASMINE project is presented. Nano-JASMINE - a very small satellite weighing less than 10 kg - aims to carry out astrometry measurements of nearby bright stars. This satellite adopts the same observation technique that was used by the HIPPARCOS satellite. In this technique, simultaneous measurements in two different fields of view separated by an angle that is greater than 90° are carried out; these measurements are performed in the course of continuous scanning observations of the entire sky. This technique enables us to distinguish between an irregularity in the spin velocity and the distribution of stellar positions. There is a major technical difference between the nano-JASMINE and the HIPPARCOS satellites-the utilization of a CCD sensor in nano-JASMINE that makes it possible to achieve an astrometry accuracy comparable to that achieved by HIPPARCOS by using an extremely small telescope. We developed a prototype of the observation system and evaluated its performance. The telescope (5cm) including a beam combiner composed entirely of aluminum. The telescope is based on the standard Ritchey- Chretien optical system and has a composite f-ratio of 33 that enables the matching of the Airy disk size to three times the CCD pixel size of 15μm. A full depletion CCD will be used in the time delay integration (TDI) mode in order to efficiently survey the whole sky in wavelengths including the near infrared. The nano-JASMINE satellite is being developed as a piggyback system and is hoped for launch in 2008. We expect the satellite to measure the position and proper motion of bright stars (m z < 8.3) with an accuracy of 1 mas, this is comparable to the accuracy achieved with the HIPPARCOS satellite.
Nano-JASMINE: A 10-kilogram Satellite For Space Astrometry
NASA Astrophysics Data System (ADS)
Kobayashi, Y.; Gouda, N.; Yano, T.; Suganuma, M.; Yamauchi, M.; Yamada, Y.
The current status of the nanoJASMINE project is presented Nano-JASMINE--a very small satellite weighing less than 10 kg -- aims to carry out astrometry measurements on nearby bright stars This satellite adopts the same observation technique used by the HIPPARCOS satellite In this technique simultanaeously measurements of two different fields separated by an angle that is greater than 90 degrees is carried out these measurements are carried out in the course of continuous scanning observations of the whole sky This technique enables us to distinguish between the irregularty in the spin velocity and stellar position distribution The major technical differrence between the nano-JASMINE and the HIPPARCOS satellite is the utilization of a CCD sensor device that makes it possible to achieve comparable astrometry accuracy by using an extremly smaller telescope We developed a prototype system and evaluated its performance The telescope is composed entirely of alminum A 5-cm telecsope including an aluminum beam combiner The telescope is based on the standard Richey-Chretian optical system and has a composit f ratio of 33 that enables the match of the Airy disk size to three times of the CCD pixel size of 15um The full depletion CCD will be used in the time delayed and integration TDI mode in order to efficiently survey the whole sky in the near-infrared wavelength The nano-JASMINE satellite is scheduled for launch in 2008 as a piggyback system We expected the satellite to measure the position and proper motion of bright stars mz 7 5 with an
NASA Astrophysics Data System (ADS)
Cowie, Leanne; Kusznir, Nick
2014-05-01
Subsidence analysis of sedimentary basins and rifted continental margins requires a correction for the anomalous uplift or subsidence arising from mantle dynamic topography. Whilst different global model predictions of mantle dynamic topography may give a broadly similar pattern at long wavelengths, they differ substantially in the predicted amplitude and at shorter wavelengths. As a consequence the accuracy of predicted mantle dynamic topography is not sufficiently good to provide corrections for subsidence analysis. Measurements of present day anomalous subsidence, which we attribute to mantle dynamic topography, have been made for three rifted continental margins; offshore Iberia, the Gulf of Aden and southern Angola. We determine residual depth anomaly (RDA), corrected for sediment loading and crustal thickness variation for 2D profiles running from unequivocal oceanic crust across the continental ocean boundary onto thinned continental crust. Residual depth anomalies (RDA), corrected for sediment loading using flexural backstripping and decompaction, have been calculated by comparing observed and age predicted oceanic bathymetries at these margins. Age predicted bathymetric anomalies have been calculated using the thermal plate model predictions from Crosby & McKenzie (2009). Non-zero sediment corrected RDAs may result from anomalous oceanic crustal thickness with respect to the global average or from anomalous uplift or subsidence. Gravity anomaly inversion incorporating a lithosphere thermal gravity anomaly correction and sediment thickness from 2D seismic reflection data has been used to determine Moho depth, calibrated using seismic refraction, and oceanic crustal basement thickness. Crustal basement thicknesses derived from gravity inversion together with Airy isostasy have been used to correct for variations of crustal thickness from a standard oceanic thickness of 7km. The 2D profiles of RDA corrected for both sediment loading and non-standard crustal
Uniform asymptotic approximations for transient waves due to an initial disturbance
NASA Astrophysics Data System (ADS)
Madsen, Per A.; Schäffer, Hemming A.; Fuhrman, David R.; Toledo, Yaron
2016-01-01
In this work, we first present a semianalytical method for the evolution of linear fully dispersive transient waves generated by an initial surface displacement and propagating over a constant depth. The procedure starts from Fourier and Hankel transforms and involves a combination of the method of stationary phase, the method of uniform asymptotic approximations and various Airy integral formulations. Second, we develop efficient convolution techniques expressed as single and double summations over the source area. These formulations are flexible, extremely fast, and highly accurate even for the dispersive tail of the transient waves. To verify the accuracy of the embedded dispersion properties, we consider test cases with sharp-edged disturbances in 1-D and 2-D. Furthermore, we consider the case of a relatively blunt Gaussian disturbance in 2-D. In all cases, the agreement between the convolution results and simulations with a high-order Boussinesq model is outstanding. Finally, we make an attempt to extend the convolution methods to geophysical tsunami problems taking into account, e.g., uneven bottom effects. Unfortunately, refraction/diffraction effects cannot easily be incorporated, so instead we focus on the incorporation of linear shoaling and its effect on travel time and temporal evolution of the surface elevation. The procedure is tested on data from the 2011 Japan tsunami. Convolution results are likewise compared to model simulations based on the nonlinear shallow water equations and both are compared with field observations from 10 deep water DART buoys. The near-field results are generally satisfactory, while the far-field results leave much to be desired.
Technology Advancement of the Visible Nulling Coronagraph
NASA Technical Reports Server (NTRS)
Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Thompson, Patrick; Bolcar, Matt; Madison, Timothy; Woodruff, Robert; Noecker, Charley; Kendrick, Steve
2010-01-01
The critical high contrast imaging technology for the Extrasolar Planetary Imaging Coronagraph (EPIC) mission concept is the visible nulling coronagraph (VNC). EPIC would be capable of imaging jovian planets, dust/debris disks, and potentially super-Earths and contribute to answering how bright the debris disks are for candidate stars. The contrast requirement for EPIC is 10(exp 9) contrast at 125 milli-arseconds inner working angle. To advance the VNC technology NASA/Goddard Space Flight Center, in collaboration with Lockheed-Martin, previously developed a vacuum VNC testbed, and achieved narrowband and broadband suppression of the core of the Airy disk. Recently our group was awarded a NASA Technology Development for Exoplanet Missions to achieve two milestones: (i) 10(exp 8) contrast in narrowband light, and, (ii) 10(ecp 9) contrast in broader band light; one milestone per year, and both at 2 Lambda/D inner working angle. These will be achieved with our 2nd generation testbed known as the visible nulling testbed (VNT). It contains a MEMS based hex-packed segmented deformable mirror known as the multiple mirror array (MMA) and coherent fiber bundle, i.e. a spatial filter array (SFA). The MMA is in one interferometric arm and works to set the wavefront differences between the arms to zero. Each of the MMA segments is optically mapped to a single mode fiber of the SFA, and the SFA passively cleans the sub-aperture wavefront error leaving only piston, tip and tilt error to be controlled. The piston degree of freedom on each segment is used to correct the wavefront errors, while the tip/tilt is used to simultaneously correct the amplitude errors. Thus the VNT controls both amplitude and wavefront errors with a single MMA in closed-loop in a vacuum tank at approx.20 Hz. Herein we will discuss our ongoing progress with the VNT.
Tunable coherent radiation at soft X-ray wavelengths: Generation and interferometric applications
Rosfjord, Kristine Marie
2004-01-01
The availability of high power, spectrally and spatially coherent soft x-rays (SXR) would facilitate a wide variety of experiments as this energy region covers the primary resonances of many magnetic and biological materials. Specifically, there are the carbon and oxygen K-edges that are critical for biological imaging in the water window and the L-edges of iron, nickel, and cobalt for which imaging and scattering studies can be performed. A new coherent soft X-ray branchline at the Advanced Light Source has begun operation (beamline 12.0.2). Using the third harmonic from an 8 cm period undulator, this branch delivers coherent soft x-rays with photon energies ranging from 200eV to 1keV. This branchline is composed of two sub-branches one at 14X demagnification and the other 8X demagnification. The former is optimized for use at 500eV and the latter at 800eV. Here the expected power from the third harmonic of this undulator and the beamline design and characterization is presented. The characterization includes measurements on available photon flux as well as a series of double pinhole experiments to determine the coherence factor with respect to transverse distance. The first high quality Airy patterns at SXR wavelengths are created with this new beamline. The operation of this new beamline allows for interferometry to be performed in the SXR region. Here an interferometric experiment designed to directly determine the index of refraction of a material under test is performed. Measurements are first made in the EUV region using an established beamline (beamline12.0.1) to measure silicon, ruthenium and tantalum silicon nitride. This work is then extended to the SXR region using beamline 12.0.2 to test chromium and vanadium.
NASA Astrophysics Data System (ADS)
Miller, K. G.; Browning, J. V.; Kulpecz, A. A.; Kominz, M. A.; Naish, T.; Rosenthal, Y.; Peltier, W. R.; Sosdian, S. M.; Wright, J. D.
2010-12-01
The eustatic peak of the Pliocene (ca. 3 Ma) allows evaluation of sea-level response to conditions warmer than present and with atmospheric carbon dioxide levels similar to the early 21st century. We provide new eustatic estimates for the Pliocene from backstripping shallow-marine, siliciclastic sections in Virginia, U.S.A., and New Zealand, accounting for the effects of compaction, Airy loading, and thermal subsidence. We compare our backstripped eustatic estimates with previously published estimates from a carbonate atoll (Enewetak), deep sea benthic foraminiferal oxygen isotopes, Mg-Ca, and uplifted marine terraces in the Carolinas and Alaska and conclude that the peak was 19±5 m, significantly lower than previously published estimates of 30-40 m derived from uplifted terraces. The 19-m peak implies not only the loss of the total equivalent of Greenland and West Antarctic ice sheets, but suggests volume loss of the East Antarctic Ice Sheet (EAIS) of ~4 m of sea-level equivalent. Our estimates provide helps resolve the long-standing controversy of the stability of the EAIS during the warmer-than-present Pliocene climatic optimum. The sea-level fall at MIC 100 (ca. 2.7 Ma) associated with the growth of large northern hemisphere ice sheets was remarkably large (~100 m) and may have cause a glacial isotostatic adjustment the resulted in uplift of the otherwise tectonically stable New Jersey coastal plain. Despite uncertainties in pre-ice core CO2 and global temperature measurements, the Pliocene provides a critical sea level-atmospheric CO2 calibration point for climates significantly warmer than the last major interglacial, MIC 5e.
Upper-Mantle Flow Driven Dynamic Topography in Eastern Anatolia
NASA Astrophysics Data System (ADS)
Sengul Uluocak, Ebru; Pysklywec, Russell; Eken, Tuna; Hakan Gogus, Oguz
2016-04-01
Eastern Anatolia is characterized by 2 km plateau uplift -in the last 10 Myrs-, high surface heat flow distribution, shallow Curie-point depth, anomalous gravity field. Seismological observations indicate relatively high Pn and Sn attenuation and significant low seismic velocity anomalies in the region. Moreover, the surface geology is associated predominantly with volcanic rocks in which melt production through mantle upwelling (following lithospheric delamination) has been suggested. It has been long known that the topographic loading in the region cannot be supported by crustal thickness (~45 km) based on the principle of Airy isostasy. Recent global geodynamic studies carried out for evaluating the post-collisional processes imply that there is an explicit dynamic uplift in Eastern Anatolia and its adjacent regions. In this study we investigate the instantaneous dynamic topography driven by 3-D upper-mantle flow in Eastern Anatolia. For this purpose we conducted numerous thermo-mechanical models using a 2-D Arbitrary Lagrangian Eulerian (ALE) finite element method. The available P-wave tomography data extracted along 10 profiles were used to obtain depth-dependent density anomalies in the region. We present resulting dynamic topography maps and estimated 3D mantle flow velocity vectors along these 2-D cross sections for each profile. The residual topography based on crustal thickness and observed topography was calculated and compared with other independent datasets concerning geological deformation and dynamic topography predictions. The results indicate an upper mantle driven dynamic uplift correlated with the under-compensated characteristic in Eastern Anatolia. We discuss our results combined with 3D mantle flow by considering seismic anisotropy studies in the region. Initial results indicate that high dynamic uplift and the localized low Pn velocities in concurrence with Pn anisotropy structures show nearly spatial coherence in Eastern Anatolia.
NASA Astrophysics Data System (ADS)
Olson, Donald W.
2009-01-01
How do astronomical methods make it possible to calculate dates and times for Vincent van Gogh's night-sky paintings? Why is there a blood-red sky in Edvard Munch's The Scream? How can the 18.6-year cycle of the lunar nodes and the Moon's declination on the night of August 29-30, 1857, explain a long-standing mystery about Abraham Lincoln's honesty in the murder case known as the almanac trial? Why is a bright star described in Act 1, Scene 1, of Hamlet? There is a long tradition of astronomical methods employed to analyze works of art, to understand historical events, and to elucidate passages in literature. Both Edmond Halley and George Biddell Airy calculated lunar phases and tide tables in attempts to determine the landing beach where Julius Caesar invaded Britain in 55 B.C. Henry Norris Russell computed configurations of Jupiter and Saturn to determine a date for a 14th-century celestial event mentioned in Chaucer's Troilus and Criseyde. In this tradition, our Texas State group has published a series of articles in Sky & Telescope over the last two decades, applying astronomy to art, history, and literature. Don Osterbrock worked with us 3 years ago when my students and I calculated dates for moonrise photographs taken by Ansel Adams in Yosemite National Park. The peaks of the Sierra Nevada crest in Yosemite are more than 125 miles from Lick Observatory, but the mountains can become visible from Lick on clear winter days and were photographed from there on early infrared-sensitive plates during the 1920s and 1930s. As we tested our topographic software by identifying the peaks that appear in the Lick plates, it was a pleasure to come to know Don, a former director of Lick Observatory and the person in whose honor this talk is dedicated.
The Greenland gravitational constant experiment
NASA Astrophysics Data System (ADS)
Ander, Mark E.; Parker, Robert L.; Aiken, Carlos L. V.; Gorman, Michael R.; Nieto, Michael Martin; Cooper, A. Paul R.; Ferguson, John F.; Fisher, Elizabeth; Greer, James; Hammer, Phil; Hansen, B. Lyle; McMechan, George A.; Sasagawa, Glenn S.; Sidles, Cyndi; Stevenson, J. Mark; Wirtz, Jim
1990-09-01
An Airy-type geophysical experiment was conducted in a 2-km-deep hole in the Greenland ice cap at depths between 213 m and 1673 m to test for possible violations of Newton's inverse square law. The experiment was done at Dye 3, the location of a Distant Early Warming Line radar dome and the site of the deepest of the Greenland Ice-Sheet Program (GISP) drill holes. Gravity measurements were made at eight depths in 183-m intervals with a LaCoste & Romberg borehole gravity meter. Prior to the experiment the borehole, gravity meter was calibrated with an absolute gravity meter, and the wireline depth-finding system used in the borehole logging was calibrated in a vertical mine-shaft against a laser geodimeter. The density of the ice in the region was calculated from measurements taken from ice cores obtained from earlier drilling observations. Ice penetrating radar was employed in order to correct the gravity data for the topography of the ice-rock interface. Surface gravity observations were made to assess the extent to which density variations in the sub-ice rock could affect the vertical gravity gradient. The locations of the gravity observation points were determined with a combination of GPS recording, first-order leveling, and EDM surveying. An anomalous variation in gravity totaling 3.87 mGal (3.87×10-5 m/s2) in a depth interval of 1460 m was observed. This may be attributed either to a breakdown of Newtonian gravity or to unexpected density variations in the rock below the ice.
Theoretical basis and application of vertical Z-component in-seam wave exploration
NASA Astrophysics Data System (ADS)
He, Wenxin; Ji, Guangzhong; Dong, Shouhua; Li, Gang
2017-03-01
Love seam waves are generally applied to the current in-seam wave explorations. Rayleigh seam waves, however, are rarely used. The dispersion and amplitude features of Rayleigh seam waves are investigated using frequency dispersion analysis and numerical simulations in this study. Firstly, we elucidate the advantages of using the vertical Z-component. Secondly, the theoretical basis standing behind its application to in-seam wave explorations is demonstrated. Furthermore, in order to compare the relative performances of Rayleigh and Love seam wave explorations, three-dimensional geological models with anomalies are numerically simulated. Thus, the feasibilities and actual exploration effects of Z-component in-seam waves are demonstrated for both theoretical models and practical applications. Our studies show that normal modes of Rayleigh seam waves always exist. Furthermore, the energy of the fundamental mode in-seam wave is concentrated in its Z-component for the middle of a coal seam. A compressional wave source primarily generates first-order mode Rayleigh seam waves whereas a shear wave source primarily excites fundamental mode Rayleigh seam waves, whose energy is concentrated in the Airy phase with the lowest velocity. The fundamental mode Z-components at the center of a coal seam are ideal for in-seam wave applications. Actually, fundamental and first-order mode in-seam waves can be recorded in most coal seams. The Z-component receivers can be placed at the location between 1/4 and 1/2 of the thickness of coal seam, where both wave modes could be detected.
Exploring shoreface dynamics and a mechanistic explanation for a morphodynamic depth of closure
NASA Astrophysics Data System (ADS)
Ortiz, Alejandra C.; Ashton, Andrew D.
2016-02-01
Using energetics-based formulations for wave-driven sediment transport, we develop a robust methodology for estimating the morphodynamic evolution of a cross-shore sandy coastal profile. In our approach, wave-driven cross-shore sediment flux depends on three components: two onshore-directed terms (wave asymmetry and wave streaming) and an offshore-directed slope term. In contrast with previous work, which applies shallow water wave assumptions across the transitional zone of the lower shoreface, we use linear Airy wave theory. The cross-shore sediment transport formulation defines a dynamic equilibrium profile and, by perturbing about this steady state profile, we present an advection-diffusion formula for profile evolution. Morphodynamic Péclet analysis suggests that the shoreface is diffusionally dominated. Using this depth-dependent characteristic diffusivity timescale, we distinguish a morphodynamic depth of closure for a given time envelope. Even though wave-driven sediment transport can (and will) occur at depths deeper than this morphodynamic closure depth, the rate of morphologic bed changes in response to shoreline change becomes asymptotically slow. Linear wave theory suggests a shallower shoreface depth of closure and much sharper break in processes than shallow water wave assumptions. Analyzing hindcasted wave data using a weighted frequency-magnitude approach, we determine representative wave conditions for selected sites along the U.S. coastline. Computed equilibrium profiles and depths of closure demonstrate reasonable similarities, except where inheritance is strong. The methodology espoused in this paper can be used to better understand the morphodynamics at the lower shoreface transition with relative ease across a variety of sites and with varied sediment transport equations.
NASA Astrophysics Data System (ADS)
Edwards, Wayne N.; Eaton, David W.; McCausland, Philip J.; Revelle, Douglas O.; Brown, Peter G.
2007-10-01
Shock waves produced by meteoroids are detectable by seismograph networks, but a lack of calibration has limited quantitative analysis of signal amplitudes. We report colocated seismic and infrasound observations from reentry of NASA's Stardust sample return capsule (SSRC) on 15 January 2006. The velocity of the SSRC (initially 12.5 km/s) was the highest ever for an artificial object, lying near the low end of the 11.2-72 km/s range typical of meteoroids. Our infrasonic/seismic recordings contain an initial N wave produced by the hypersonic shock front, followed ˜10 s later by an enigmatic series of weak, secondary pulses. The seismic signals also include an intervening dispersed wave train with the characteristics of an air-coupled Rayleigh wave. We determine an acoustic-seismic coupling coefficient of 7.3 ± 0.2 μm s-1/Pa. This represents an energy admittance of 2.13 ± 0.15%, several orders of magnitude larger than previous estimates derived from earthquake or explosive analogs. Theoretical seismic response was computed using in situ VP and VS measurements, together with laboratory density measurements from samples of the clay-rich playa. Treatment of the air-ground interface as an idealized air-solid contact correctly predicts the initial pulse shape but underestimates its seismic amplitude by a factor of ˜2. Full-wave synthetic seismograms simulate the air-coupled Rayleigh wave and suggest that the secondary arrivals are higher-order Airy phases. Part of the infrasound signal appears to arise from coupling of ground motion into the air, much like earthquake-induced sounds.
Asymptotics of bivariate generating functions with algebraic singularities
NASA Astrophysics Data System (ADS)
Greenwood, Torin
Flajolet and Odlyzko (1990) derived asymptotic formulae the coefficients of a class of uni- variate generating functions with algebraic singularities. Gao and Richmond (1992) and Hwang (1996, 1998) extended these results to classes of multivariate generating functions, in both cases by reducing to the univariate case. Pemantle and Wilson (2013) outlined new multivariate ana- lytic techniques and used them to analyze the coefficients of rational generating functions. After overviewing these methods, we use them to find asymptotic formulae for the coefficients of a broad class of bivariate generating functions with algebraic singularities. Beginning with the Cauchy integral formula, we explicity deform the contour of integration so that it hugs a set of critical points. The asymptotic contribution to the integral comes from analyzing the integrand near these points, leading to explicit asymptotic formulae. Next, we use this formula to analyze an example from current research. In the following chapter, we apply multivariate analytic techniques to quan- tum walks. Bressler and Pemantle (2007) found a (d + 1)-dimensional rational generating function whose coefficients described the amplitude of a particle at a position in the integer lattice after n steps. Here, the minimal critical points form a curve on the (d + 1)-dimensional unit torus. We find asymptotic formulae for the amplitude of a particle in a given position, normalized by the number of steps n, as n approaches infinity. Each critical point contributes to the asymptotics for a specific normalized position. Using Groebner bases in Maple again, we compute the explicit locations of peak amplitudes. In a scaling window of size the square root of n near the peaks, each amplitude is asymptotic to an Airy function.
Axial analysis of cones and adjacent retinal structures using AOSLO (Conference Presentation)
NASA Astrophysics Data System (ADS)
Papay, Joel A.; Johnston, Kirby D.; Sawides, Lucie; de Castro, Alberto; Burns, Stephen A.; Elsner, Ann E.
2016-03-01
We imaged the retina using the Indiana Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO). Our system uses two deformable mirrors to provide en face, high-resolution images of retinal structures at a 28 Hz frame rate. The wavelength of the sensor light was 850 nm and the imaging wavelength was 820 nm at 50 and 120 °W respectively. The confocal pinhole was located in a position conjugate with the retina allowed us to segment one retina plane. Two different confocal apertures of 75 μm and 100 μm (1.5 and 2 times the Airy disk size) were used to provide different amounts of confocal or scattered light. The imaging area was 1.4 x 1.2 deg which corresponds roughly to 400 x 350 μm. Using the large stroke deformable mirror, which provides the focusing capability of the confocal system, we imaged the same location at different planes. We moved from superficial layers to the retinal pigment epithelium in 0.3 D increments. The range of adjustments included the subjectively best overall image, and focal planes anterior and posterior to this. We imaged 10 subjects at approximately 7.5 deg temporal from the fovea. A video of individual frames was taken, and the individual frames were dewarped, aligned, and averaged. We measured 10 bright and 10 dim cones for each subject at the 10 depths, with brightness groupings based subjectively on the most superficial location. The function for amount of light reflected differed for the two groups of cones. Reflectivity varied as a function of depth.
Everall, Neil J; Priestnall, Ian M; Clarke, Fiona; Jayes, Linda; Poulter, Graham; Coombs, David; George, Michael W
2009-03-01
This paper describes preliminary investigations into the spatial resolution of macro attenuated total reflection (ATR) Fourier transform infrared (FT-IR) imaging and the distortions that arise when imaging intact, convex domains, using spheres as an extreme example. The competing effects of shallow evanescent wave penetration and blurring due to finite spatial resolution meant that spheres within the range 20-140 microm all appeared to be approximately the same size ( approximately 30-35 microm) when imaged with a numerical aperture (NA) of approximately 0.2. A very simple model was developed that predicted this extreme insensitivity to particle size. On the basis of these studies, it is anticipated that ATR imaging at this NA will be insensitive to the size of intact highly convex objects. A higher numerical aperture device should give a better estimate of the size of small spheres, owing to superior spatial resolution, but large spheres should still appear undersized due to the shallow sampling depth. An estimate of the point spread function (PSF) was required in order to develop and apply the model. The PSF was measured by imaging a sharp interface; assuming an Airy profile, the PSF width (distance from central maximum to first minimum) was estimated to be approximately 20 and 30 microm for IR bands at 1600 and 1000 cm(-1), respectively. This work has two significant limitations. First, underestimation of domain size only arises when imaging intact convex objects; if surfaces are prepared that randomly and representatively section through domains, the images can be analyzed to calculate parameters such as domain size, area, and volume. Second, the model ignores reflection and refraction and assumes weak absorption; hence, the predicted intensity profiles are not expected to be accurate; they merely give a rough estimate of the apparent sphere size. Much further work is required to place the field of quantitative ATR-FT-IR imaging on a sound basis.
NASA Astrophysics Data System (ADS)
Wang, Chao; Jiang, Lun; Hu, Yuan; Liu, Zhuang; Li, Ying-chao; Wang, Le
2016-10-01
In the free-space laser communication, there is a strong need for a technology that can decrease the size of the diffraction spot in the receiver port, because a smaller diffraction spot in the receive port makes the transmit data more secure. In this paper, instead of the usage of the larger size aperture lens in the free-space laser communication system, we introduce a diffractive superresolution technology that changing the received information laser beam into radially polarized beam which is focused on the detector array. In the paper, firstly, the conversion method of the information natural light which the optical antenna received to the radially polarized beam is discussed in detail. Then, in the focal plane, the transverse intensity distribution expression near the focal point for the radially polarized laser beam are presented, and the numerical simulation results of the intensity distributions around the focal point on different numerical apertures (NA) are given. The full width at half-maximum (FWHM) values of the main lobe are considered for the standard of the spot size. Through a comparison of the focal point FWHM values with the natural light and radially polarized beam, we judge the superresolution performance of the receiver optical system with radially polarized beam on different NA of 0.4, 0.6 and 0.75. We find that the method of focusing with radially polarized beam generates a smaller spot size than the Airy spot size when the NA is no less than 0.6; when the NA reach to 0.75, the resolution is 1.5 times than the diffraction limit. But it will decrease the light power in the process of natural light converted to radially polarized beam. When the communication laser is polarized laser, the energy loss can be reduced to around 20%. This technology can be applied when the laser energy is not the main concern in the communication.
NASA Astrophysics Data System (ADS)
Yu, C.; van der Hilst, R. D.; Chen, W. P.
2015-12-01
How surface topography is supported at depth is a long-standing question in geodynamics. Overall, the western United States (US) stands high compared to the North American craton, but it has remained a challenge to distinguish crustal and mantle support of this topography due to the complex tectonic history of the western US and inadequate knowledge of crustal structure. We provide new seismological constraints on crustal structure using virtual deep seismic sounding (VDSS). VDSS uses SV-to-P wave conversion at the free surface near each seismograph as a virtual source, which, in turn, generates a strong, post-critical reflection off the Moho. This signal remains robust even if the Moho is complex or transitional in nature. Compared to traditional receiver functions, VDSS is less prone to contamination by scattering from other crustal structures, such as thick sediments or intra-crustal discontinuities. More important, VDSS can provide simultaneous constraints on both the total thickness and the overall P-wave speed of the crust - two key parameters for estimating the crustal contribution to isostasy. Based on data from USArray (EarthScope), we estimate the residual topography (that is, the difference between observed elevation and that predicted from the Airy model given the inferred crustal structure) in the western US (Figure 1). Positive values, indicative of mantle-supported topography, are wide spread in the Great Basin, the southern Rocky Mountains, the Snake River Plain-Yellowstone system, and the High Lava Plains. The periphery of the Colorado Plateau, the Central Sierra Nevada batholith, and the Idaho batholith also show positive residual topography. In contrast, our analysis suggests that thick crust in the interior of the Colorado Plateau and the Wyoming craton provides more than enough support for the topography, consistent with a thick, cold lithospheric root below.
NASA Technical Reports Server (NTRS)
Kaljevic, Igor; Patnaik, Surya N.; Hopkins, Dale A.
1996-01-01
The Integrated Force Method has been developed in recent years for the analysis of structural mechanics problems. This method treats all independent internal forces as unknown variables that can be calculated by simultaneously imposing equations of equilibrium and compatibility conditions. In this paper a finite element library for analyzing two-dimensional problems by the Integrated Force Method is presented. Triangular- and quadrilateral-shaped elements capable of modeling arbitrary domain configurations are presented. The element equilibrium and flexibility matrices are derived by discretizing the expressions for potential and complementary energies, respectively. The displacement and stress fields within the finite elements are independently approximated. The displacement field is interpolated as it is in the standard displacement method, and the stress field is approximated by using complete polynomials of the correct order. A procedure that uses the definitions of stress components in terms of an Airy stress function is developed to derive the stress interpolation polynomials. Such derived stress fields identically satisfy the equations of equilibrium. Moreover, the resulting element matrices are insensitive to the orientation of local coordinate systems. A method is devised to calculate the number of rigid body modes, and the present elements are shown to be free of spurious zero-energy modes. A number of example problems are solved by using the present library, and the results are compared with corresponding analytical solutions and with results from the standard displacement finite element method. The Integrated Force Method not only gives results that agree well with analytical and displacement method results but also outperforms the displacement method in stress calculations.
Stable and Critical Noncohesive Coulomb Wedges: Exact Elastic Solutions
NASA Astrophysics Data System (ADS)
Wang, K.; Hu, Y.
2004-12-01
The theory of critically tapered Coulomb wedge has been successfully applied to model active fold-and-thrust belts or submarine accretionary prisms. Brittle mountain building is episodic in nature, controlled by changes in basal friction, erosion and sedimentation, and hydrogeology. Sediment accretion may be modulated by great subduction earthquakes. Between deformation episodes and/or during transition between compressional and extensional tectonics, the Coulomb wedges are stable (i.e., supercritical), to which the critical taper theory does not apply. In this work, we provide an exact elastic solution for stable wedges based on Airy stress functions. The stress equilibrium equation and definition of basal friction and basal and internal pore fluid pressure ratios are exactly the same as those used for Dahlen's [1984] exact solution for critical noncohesive Coulomb wedges, but internal friction μ becomes irrelevant. Given elastic - perfectly Coulomb-plastic rheology, for stresses in a wedge on the verge of Coulomb failure there must co-exist a critical taper solution involving μ and a unique equivalent elastic solution not involving μ . Our elastic solution precisely reduces to Dahlen's critical taper solution for critical conditions. For stable conditions, normal stress perpendicular to the surface slope σ z and shear stress τ xz are identical with those in a critical taper, but the slope-parallel normal stress is different. The elastic solution is also generally applicable to purely elastic wedges and useful for modeling geodetic observations. A stable noncohesive Coulomb wedge differs from a general elastic wedge in that its upper and lower surfaces stay at zero curvature during loading. Dahlen, F.A. (1984), Noncohesive critical Coulomb wedges: An exact solution, JGR, 89, 10,125-10,133.
Is there uniformitarian or catastrophic tectonics on Venus?
NASA Technical Reports Server (NTRS)
Turcotte, Donald L.
1993-01-01
The distribution and modification of craters on Venus favors a near global, volcanic resurfacing event about 500 Myrs ago. Such an event indicates that the tectonic evolution of Venus was catastrophic rather than uniformitarian. The creation of a global, single-plate lithosphere on Venus about 500 Myrs ago can explain a variety of tectonic features on Venus that are not consistent with the thin lithosphere required by a uniformitarian hypothesis. A lithosphere on Venus that has thickened for 500 Myrs has a present thickness of about 300 km whereas steady-state heat loss from Venus requires a mean lithospheric thickness near 40 km. A thick lithosphere on Venus can support the high plateaus (elevations of 3-4 km) and mountain belts (up to 9 km) using the same isostatic compensation concepts applicable to the earth. If a thick lithosphere is thinned by a mantle plume, elevation is caused by thermal isostasy. The elevation due to the thinning of a 300 km thick lithosphere is about 3 km. Thus the domal elevation of Beta Regio can be explained by the same mechanism responsible for the elevation of the Hawaiian Swell. While the broad highland plateaus on Venus may be associated with thermal isostasy, the mountain belts in Ishtar Terra clearly cannot be. The high topography of Freyja Montes is almost certainly associated with underthrusting and the likely compensation mechanism is Airy isostasy associated with a thickened crust. With a density contrast delta, of 500 kg m(exp -3) an elevation of 9 km requires a crustal thickening of about 70 km. With a thick lithosphere there is no difficulty in supporting such a thick crust.
The seismic Moho structure of Shatsky Rise oceanic plateau, northwest Pacific Ocean
NASA Astrophysics Data System (ADS)
Zhang, Jinchang; Sager, William W.; Korenaga, Jun
2016-05-01
Oceanic plateaus are large igneous provinces formed by extraordinary eruptions that create thick oceanic crust, whose structure is poorly known owing to the lack of deep-penetration seismic data. Multichannel seismic (MCS) reflection and wide-angle refraction data allow us to show Moho structure beneath a large part of the Shatsky Rise oceanic plateau in the northwest Pacific Ocean. Moho reflectors in the two data sets can be connected to trace the interface from the adjacent abyssal plain across much of the interior. The reflectors display varied character in continuity, shape, and amplitude, similar to characteristics reported in other locations. Beneath normal crust, the Moho is observed at ∼13 km depth (∼7 km below the seafloor) in MCS data and disappears at ∼20 km depth (∼17 km below the seafloor) beneath the high plateau. Moho at the distal flanks dips downward towards the center with slopes of ∼0.5°-1°, increasing to 3°-5° at the middle flanks. Seismic Moho topography is consistent with Airy isostasy, confirming this widely-applied assumption. Data from this study show that crustal thickness between the massifs in the interior of the plateau is nearly twice normal crustal thickness, despite the fact that this crust records apparently normal seafloor spreading magnetic lineations. The Moho model allows improved estimates of plateau area (5.33 ×105 km2) and volume (6.90 ×106 km3), the latter assuming that the entire crust was formed by Shatsky Rise volcanism because the massifs formed at spreading ridges. This study is unique in showing Moho depth and structure over an extraordinarily large area beneath an oceanic plateau, giving insight to plateau structure and formation.
Using Google Earth to Explore Strain Rate Models of Southern California
NASA Astrophysics Data System (ADS)
Richard, G. A.; Bell, E. A.; Holt, W. E.
2007-12-01
A series of strain rate models for the Transverse Ranges of southern California were developed based on Quaternary fault slip data and geodetic data from high precision GPS stations in southern California. Pacific-North America velocity boundary conditions are applied for all models. Topography changes are calculated using the model dilatation rates, which predict crustal thickness changes under the assumption of Airy isostasy and a specified rate of crustal volume loss through erosion. The models were designed to produce graphical and numerical output representing the configuration of the region from 3 million years ago to 3 million years into the future at intervals of 50 thousand years. Using a North American reference frame, graphical output for the topography and faults and numerical output for locations of faults and points on the crust marked by the locations on cities were used to create data in KML format that can be used in Google Earth to represent time intervals of 50 thousand years. As markers familiar to students, the cities provide a geographic context that can be used to quantify crustal movement, using the Google Earth ruler tool. By comparing distances that markers for selected cities have moved in various parts of the region, students discover that the greatest amount of crustal deformation has occurred in the vicinity of the boundary between the North American and Pacific plates. Students can also identify areas of compression or extension by finding pairs of city markers that have converged or diverged, respectively, over time. The Google Earth layers also reveal that faults that are not parallel to the plate boundary have tended to rotate clockwise due to the right lateral motion along the plate boundary zone. KML TimeSpan markup was added to two versions of the model, enabling the layers to be displayed in an automatic sequenced loop for a movie effect. The data is also available as QuickTime (.mov) and Graphics Interchange Format (.gif
Zhang, Ming-Ying; Fritsch, Peter W; Ma, Peng-Fei; Wang, Hong; Lu, Lu; Li, De-Zhu
2017-02-16
Gaultheria series Trichophyllae Airy Shaw is an angiosperm clade of high-alpine shrublets endemic to the Himalaya-Hengduan Mountains and characterized by recent species divergence and convergent character evolution that has until recently caused much confusion in species circumscription. Although multiple DNA sequence regions have been employed previously, phylogenetic relationships among species in the group have remained largely unresolved. Here we examined the effectiveness of plastid genome for improving phylogenetic resolution within the G. series Trichophyllae clade. Plastid genomes of 31 samples representing all 19 recognized species of the series and three outgroup species were sequenced with Illumina Sequencing. Maximum likelihood (ML), maximum parsimony (MP) and Bayesian inference (BI) phylogenetic analyses were performed with various datasets, i.e., that from the whole plastid genome, coding regions, noncoding regions, large single-copy region (LSC) and inverted-repeat region a (IRa). The partitioned whole plastid genome with inverted-repeat region b (IRb) excluded was also analyzed with ML and BI. Tree topologies based on the whole plastid genome, noncoding regions, and LSC region datasets across all analyses, and that based on the partitioned dataset with ML and BI analyses, are identical and generally strongly supported. Gaultheria series Trichophyllae form a clade with three species and one variety that is sister to a clade of the remaining 16 species; the latter comprises seven main subclades. Interspecific relationships within the series are strongly supported except for those based on the coding-region and IRa-region datasets. Eight divergence hotspot regions, each possessing > 5% percent variable sites, were screened across the whole plastid genome of the 28 individuals sampled in the series. Results of morphological character evolution reconstruction diagnose several clades, and a hypothesis of adaptive evolution for plant habit is postulated.
NASA Astrophysics Data System (ADS)
Lindlein, Norbert; Loosen, Florian; Fries, Sebastian
2015-09-01
The electromagnetic field in the focus of an ideal aplanatic lens with high numerical aperture, which is illuminated by an ultrashort optical pulse and plane wave front, is simulated by taking the vectorial Debye integral and the coherent superposition of a frequency spectrum of monochromatic waves. The behavior of the principal maxima and the first secondary maxima as function of the numerical aperture (NA) and the pulse duration T is investigated systematically for light incident with linear polarization. First, one would not expect remarkable deviations from the stationary case. But also this simple system of an ideal aplanatic lens without any chromatic or monochromatic aberrations (of course only simple from the point of theory, but not at all from the point of practical realization) shows some remarkable results. If the NA (in vacuum) tends to the limiting case of 1.0 the maximum value of |E|2 increases faster than expected from the scalar theory (Airy disc) with a maximum deviation of about 13%. The second effect really comes from very short pulses, i.e. very small values T. Then, the value of |E|2 compared to the expected linear increase with 1/T decreases slightly (only less than 2%), but systematically for all NAs. Even more interesting is the dependence of the height of the first secondary maxima along the x-axis and y-axis on the NA and 1/T. It can be seen that along both axes the first secondary maxima nearly vanish for very short pulses, i.e. large values 1/T.
Diffraction and Dissipation of Atmospheric Waves in the Vicinity of Caustics
NASA Astrophysics Data System (ADS)
Godin, O. A.
2015-12-01
A large and increasing number of ground-based and satellite-borne instruments has been demonstrated to reliably reveal ionospheric manifestations of natural hazards such as large earthquakes, strong tsunamis, and powerful tornadoes. To transition from detection of ionospheric manifestations of natural hazards to characterization of the hazards for the purposes of improving early warning systems and contributing to disaster recovery, it is necessary to relate quantitatively characteristics of the observed ionospheric disturbances and the underlying natural hazard and, in particular, accurately model propagation of atmospheric waves from the ground or ocean surface to the ionosphere. The ray theory has been used extensively to model propagation of atmospheric waves and proved to be very efficient in elucidating the effects of atmospheric variability on ionospheric signatures of natural hazards. However, the ray theory predicts unphysical, divergent values of the wave amplitude and needs to be modified in the vicinity of caustics. This paper presents an asymptotic theory that describes diffraction, focusing and increased dissipation of acoustic-gravity waves in the vicinity of caustics and turning points. Air temperature, viscosity, thermal conductivity, and wind velocity are assumed to vary gradually with height and horizontal coordinates, and slowness of these variations determines the large parameter of the problem. Uniform asymptotics of the wave field are expressed in terms of Airy functions and their derivatives. The geometrical, or Berry, phase, which arises in the consistent WKB approximation for acoustic-gravity waves, plays an important role in the caustic asymptotics. In addition to the wave field in the vicinity of the caustic, these asymptotics describe wave reflection from the caustic and the evanescent wave field beyond the caustic. The evanescent wave field is found to play an important role in ionospheric manifestations of tsunamis.
Evidence and models for lower crustal flow beneath the Galápagos platform
NASA Astrophysics Data System (ADS)
Orellana-Rovirosa, Felipe; Richards, Mark
2016-01-01
The volcanic Galápagos Islands are constructed upon a broad platform, with their active westernmost islands marking the current position of the hotspot. Built upon young oceanic lithosphere (<15 Ma), this platform exhibits unique morphologic features including a system of stepped terraces on the southwestern escarpment with 3 km relief, contrasting with gentle slopes off the eastern platform toward the Carnegie Ridge. Considering horizontal lithostatic pressure differences associated with this relief, along with high temperatures within the young, hotspot-affected lithosphere, it is likely that lower crustal flow contributes significantly to crustal deformation within the Galápagos platform. Using a 2-D, isostatic, thin-sheet approximation for the Stokes flow equation with (Newtonian) space-time-dependent viscosity, we suggest that the bathymetric rim along the eastern platform region (where gravimetry indicates Airy isostasy) near Española Island may be the expression of a mature lower crustal flow front developed over the last ˜3 Myr; horizontal mass displacements (˜50 km) associated with this crustal flow episode may have advected mantle plume geochemical signatures toward the southeast, and in directions not necessarily parallel to the hotspot track. Also, the stepped terraces along the southwestern platform may be explained by lower crustal flow-associated backward tilting of the bathymetric surface that, although resulting in small angular changes (˜0.1°), effectively hinders the horizontal flow of lava sheets. This backward-tilting process was likely restricted to the last ˜1 Ma or less, and may be a unique event involving extrusion of lavas from within the southwestward-marching lower-crustal flow front.
New Insights into the Morphology of the Galapagos Platform from Lower Crustal Flow Models
NASA Astrophysics Data System (ADS)
Orellana Rovirosa, F.; Richards, M. A.
2014-12-01
The volcanically-active Galapagos Islands are constructed upon a broad platform, with the westernmost islands being the most active, marking the present-day position of the Galapagos hotspot (mantle plume). This volcanic platform overlies relatively young oceanic lithosphere (<15 Myr) and exhibits unique morphologic features along its boundaries. The most spectacular of these features is a system of stepped terraces on the southwestern escarpment, with very large vertical relief (>3 km), and contrasting with relatively gentle slopes off the eastern platform edge toward the Carnegie ridge. Considering the horizontal lithostatic pressure differences associated with this bathymetric relief, along with the high temperatures within this young, hotspot-affected oceanic lithosphere and crust; it is likely that lower crustal flow contributes significantly, perhaps even dominantly, to lithospheric and crustal deformation within the Galapagos Platform. Using 2D numerical models that invoke a thin-sheet approximation for the Stokes' equation for a Newtonian fluid with space- and time-dependent viscosity, and assuming isostatic conditions, we show that: (1) the pronounced bathymetric rim along the Eastern platform region (where gravimetric studies indicate Airy isostasy) near Española Island may be the expression of a mature stage of a lower crustal flow front evolving asymptotically during the last ~3 Myr; (2) the spectacular system of stepped terraces along the southwestern edge of the platform may be explained by lower crustal flow-associated backward tilting of the bathymetric surface that, even with small amounts of angular change (~0.1 deg) and potentially occurring in non-isostatic regimes, effectively hinders the horizontal flow of lava. This process of backward-tilting may have been largely restricted to the last ~1 Myr of platform growth, and hence may be a unique event that may involve horizontal extrusion of large lava sheets from within the southwestward
Surface magnetic field mapping on high albedo marking areas of the moon
NASA Astrophysics Data System (ADS)
Shibuya, H.; Aikawa, K.; Tsunakawa, H.; Takahashi, F.; Shimizu, H.; Matsushima, M.
2009-12-01
The correlation between high albedo markings (HAM) on the surface of the moon and strong magnetic anomalies has been claimed since the early time of the lunar magnetic field study (Hood and Schubert, 1980). Hood et al. (1989) mapped the smoothed magnetic field over the Reiner Gamma region using Lunar Prospector magnetometer (LP-MAG) data, and showed that the position of them matches well. We have developed a method to recover the 3-d magnetic field from satellite field observations (EPR method which stands for Equivalent Pole Reduction; Toyoshima et al. 2008). Applying EPR to the several areas of strong magnetic anomalies, we calculated the magnetic anomaly maps of near surface regions, to see how the anomaly and the HAM correlate each other. The data used is of the Lunar Prospector magnetometer (LP-MAG). They are selected from low altitude observations performed in 1998 to 1999. The areas studied are Reiner Gamma, Airy, Descartes, Abel, and Crisium Antipode regions. The EPR determines a set of magnetic monopoles at the moon surface which produce the magnetic field of the observation. In each studied area, we put poles in 0.1° intervals of both latitude and longitude, then the magnetic field at 5km in altitude is calculated. The field distribution is superimposed with the albedo map made from Clementine data. The total force (Bf) maps indicate that the HMA occurs at the strong anomaly regions, but their shape does not quite overlie. However, taking horizontal component (Bh), not only position but the shape and size of the anomalies coincide with HMA regions. It is particularly true for the Reiner Gamma, and Descartes regions. The shape of HMA fits in a Bh contour. The HMA is argued to be formed by the reduction of solar wind particles which are shielded by the magnetic field. Since the deflection of the charged particle becomes large at large horizontal component, the Bh distribution showed here support the argument.
NASA Astrophysics Data System (ADS)
Richmond, N. C.; Hood, L. L.
2008-02-01
Previous processing of the Lunar Prospector magnetometer (LP-MAG) data has yielded ~40% coverage of the Moon. Here, new mapping of the low-altitude LP-MAG data is reported with the goal of producing the first global vector map of the lunar crustal magnetic field. By considering all data regardless of the external plasma environment and using less restrictive editing criteria, 2360 partial and complete passes have been identified that can be used to investigate the lunar crustal magnetic anomalies. The cleanest global coverage is provided using 329 low-altitude nightside and terminator passes. An inverse power method has been used to continue the final mapping data to constant altitude. Using the 329 optimal passes, global maps of the lunar crustal magnetic field are constructed at 30 and 40 km. Consistent with previous studies: (1) the largest concentrations of anomalies are mapped antipodal to the Crisium, Serenitatis, Imbrium, and Orientale basins and (2) isolated anomalies at Reiner Gamma, Rima Sirsalis, Descartes, and Airy are mapped. Anomalies previously unmapped by the LP-MAG experiment include (1) isolated anomalies near the craters Abel and Hartwig, (2) weak magnetization within the Nectarian-aged Crisium and Moscoviense basins, and (3) a relatively weak anomaly in an area dominated by crater chains associated with the formation of Nectaris. Future work with the new low-altitude data set is discussed and will include determining whether the lunar anomalies are capable of deflecting the solar wind and investigating directions of magnetization to evaluate a possible former core dynamo.
Transverse intensity transformation by laser amplifiers
NASA Astrophysics Data System (ADS)
Litvin, Igor A.; King, Gary; Collett, Oliver J. P.; Strauss, Hencharl J.
2015-03-01
Lasers beams with a specific intensity profile such as super-Gaussian, Airy or Dougnut-like are desirable in many applications such as laser materials processing, medicine and communications. We propose a new technique for laser beam shaping by amplifying a beam in an end-pumped bulk amplifier that is pumped with a beam that has a modified intensity profile. Advantages of this method are that it is relatively easy to implement, has the ability to reshape multimode beams and is naturally suited to high power/energy beams. Both three and four level gain materials can be used as amplifier media. However, a big advantage of using three level materials is their ability to attenuate of the seed beam, which enhances the contrast of the shaping. We first developed a numerical method to obtain the required pump intensity for an arbitrary beam transformation. This method was subsequently experimentally verified using a three level system. The output of a 2.07 μm seed laser was amplified in a Ho:YLF bulk amplifier which was being pumped by a 1.89 μm Tm:YLF laser which had roughly a TEM10 Hermit Gaussian intensity profile. The seed beam was amplified from 0.3 W to 0.55 W at the full pump power of 35 W. More importantly, the beam profile in one transverse direction was significantly shaped from Gaussian to roughly flat-top, as the model predicted. The concept has therefore been shown to be viable and can be used to optimise the beam profile for a wide range of applications.
Isostatic Model and Isostatic Gravity Anomalies of the Arabian Plate and Surroundings
NASA Astrophysics Data System (ADS)
Kaban, Mikhail K.; El Khrepy, Sami; Al-Arifi, Nassir
2016-04-01
The isostatic modeling represents one of the most useful "geological" reduction methods of the gravity field. With the isostatic correction, it is possible to remove a significant part of the effect of deep density heterogeneity, which dominates in the Bouguer gravity anomalies. Although there exist several isostatic compensation schemes, it is usually supposed that a choice of the model is not an important factor to first order, since the total weight of compensating masses remains the same. We compare two alternative models for the Arabian plate and surrounding area. The Airy model gives very significant regional isostatic anomalies, which cannot be explained by the upper crust structure or disturbances of the isostatic equilibrium. Also, the predicted "isostatic" Moho is very different from existing seismic observations. The second isostatic model includes the Moho, which is based on seismic determinations. Additional compensation is provided by density variations within the lithosphere (chiefly in the upper mantle). According to this model, the upper mantle under the Arabian Shield is less dense than under the Platform. In the Arabian platform, the maximum density coincides with the Rub' al Khali, one of the richest oil basin in the world. This finding agrees with previous studies, showing that such basins are often underlain by dense mantle, possibly related to an eclogite layer that has caused their subsidence. The mantle density variations might be also a result of variations of the lithosphere thickness. With the combined isostatic model, it is possible to minimize regional anomalies over the Arabian plate. The residual local anomalies correspond well to tectonic structure of the plate. Still very significant anomalies, showing isostatic disturbances of the lithosphere, are associated with the Zagros fold belt, the collision zone of the Arabian and Eurasian plates.
Study of the Nortern polar ionosphere by all-sky imager, riometer and magnetometer data
NASA Astrophysics Data System (ADS)
Guineva, Veneta; Trondsen, Espen; Marple, Steve; Dahle, Kolbjorn; Stauning, Peter
The variety of the auroral forms and their behaviour, as a result of the complexity of the processes in the upper atmosphere at high latitudes and the connection between them as well as the large number of influencing factors give a lot of possibilities for new investigations. The opportunity for simultaneous multi-instrument observations by different instruments, as well by sets of instruments of the same kind, nowadays is a precondition for an extensive research of the polar ionosphere phenomena. For this study, simultaneous observations' data of the OI 5577 ´˚ and 6300 ´˚ emissions, the electron precipitation flux and the terrestrial magnetic A A field have been used from the following instruments: the All-Sky Imager (ASI), ALOMAR Imaging Riometer for Ionospheric Studies (AIRIS) and the magnetometer, positioned at Andøya Rocket Range (ARR), Andenes (69.3° N, 16.03° E); ASI, 64-beam Imaging Riometer and the magnetometer at the Auroral Observatory, Longyearbyen, Svalbard (78.20° N, 15.83° E); IRIS at Kilpisj¨rvi, Finland (69.05° N, 20.79° E). The fields of view of the instruments cover a large a area of the auroral oval and the polar cap. The distribution and the behaviour of the optical emissions and the absorption features have been analysed. A good correlation between the spatial and temporal evolutions of the optical emissions, the precipitating electron fluxes and the terrestrial magnetic field has been observed. The response of the ionosphere to the solar and geomagnetic activity changes has been studied. Data access has been provided under the Project "ALOMAR eARI" (RITA-CT-2003-506208), Andenes, Norway. This Project received research funding from the European Community's 6th Framework Program.
NASA Astrophysics Data System (ADS)
Guineva, Veneta; Despirak, Irina; Werner, Rolf; Trondsen, Espen; Honary, Farideh; Marple, Steve; Stauning, Peter; Dahle, Kolbjorn
The behaviour of the auroral emissions 5577˚ and 6300˚, the ratio I6300/I5577 and the ab-A A sorption at 38.2 MHz during substorms occurred at the time of recurrent streams (RS) has been examined. The development of the substorm bulge is followed up. The variations of the emissions and the absorption at 38.2 MHZ depending on the different locations of the substorm bulge with respect to the point of observation have been studied. Estimations of the particle precipitation spectra at the polar edge of the auroral bulge and inside it have been obtained. For the study, data from the All-Sky Imagers at Andøya Rocket Range (ARR), Andenes, Nor-way (69.3N, 16.03E) and at the Auroral Observatory, Longyearbyen, Svalbard (78.20N, 15.83E) from the observational season 2005-2006 have been used, and simultaneous measurements from the ALOMAR Imaging Riometer for Ionospheric Studies (AIRIS), 64-beam Imaging Riome-ter at the Auroral Observatory, Longyearbyen, Svalbard (78.20N, 15.83E); IRIS at Kilpisjürvi, a Finland (69.05N, 20.79E).. Additional data concerning the solar wind parameters, IMF, the precipitating particles and the magnetic field are used from the WIND and DMSP satellites and the IMAGE magnetometer network to determine the recurrent streams, the substorms during RS and the boundaries of the precipitating electrons. Data access has been provided under the Project "ALOMAR eARI" (RITA-CT-2003-506208), Andenes, Norway. This Project received research funding from the European Community's 6th Framework Program.
Zoulinakis, Georgios; Esteve-Taboada, Jose Juan; Ferrer-Blasco, Teresa; Madrid-Costa, David; Montés-Micó, Robert
2017-01-01
AIM To simulate and compare accommodation in accommodative and non-accommodative human eye models. METHODS Ray tracing and optical design program was used. Three eye models were designed and studied: the Navarro, the Arizona and the Liou-Brennan. In order to make the Navarro and Liou-Brennan models to accommodate, specific geometric parameters of the models were altered with values that were chosen from the literature. For the Arizona model, its' mathematical functions for accommodation were used for the same accommodative demands. The simulation included four distances of accommodation for each model: at infinity, 3, 1 and 0.5 m.The results were diffraction images of a “letter F” for graphical comparison, spot diagrams on the retinal field and Modulation Transfer Function (MTF) graphs. RESULTS Zernike coefficients for the aberrations, Airy disk diameter, root mean square (RMS) error diameter and total axial length of the model were provided from the program. These were compared between them in all distances. The Navarro model had the smallest axial length change as a simple model. The Arizona did not change its axial length because it is designed to be accommodative. The Liou-Brennan model had different results concerning the aberrations because of the decentration of the pupil. The MTF graphs showed small differences between the models because of the differences in their designs. CONCLUSION All the three models are able to simulate accommodation with the expected results. There is no model that can be assumed as the best choice. Accommodation can be simulated in non-accommodativemodels and in customized ones. PMID:28149775
Ice flow velocities and elevation change at Fleming Glacier, Wordie Ice Shelf, Antarctic Peninsula
NASA Astrophysics Data System (ADS)
Wendt, A.; Wendt, J.; Bown, F.; Rivera, A.; Zamora, R.; Bravo, C.; Casassa, G.
2009-04-01
Glaciers in the Antarctic Peninsula have been responding to the pronounced atmospheric warming in the region (Vaughan et al. 2003) with frontal retreat (Cook et al. 2005), ice shelf collapse (Rott et al. 1996) and ice flow acceleration and thinning (Rignot et al. 2004; Shepherd et al. 2003; Pritchard & Vaughan 2007). These trends have progressively migrated southwards along the Antarctic Peninsula causing, for instance, a substantial retreat of Wilkins Ice Shelf (70.2Ë S) in 2008. At 69.3Ë S, but 300 km to the east, Wordie Ice Shelf experienced a major reduction in size in the 1980s (Doake & Vaughan 1991). Available information about this ice shelf and its feeding glaciers dates back to the 1970s when ice thickness and velocity measurements were carried out on Fleming Glacier (Doake 1975). Although initially it was thought that the post-collapse conditions of the feeding glaciers remained unchanged (Vaughan 1993), more recent evidence shows that glaciers accelerated after the ice shelf collapse and substantial glacier thinning has occurred (Rignot et al. 2005). We present data acquired during two field expeditions to Fleming Glacier. During the first season in November 2007, we installed an Automatic Weather Station (AWS) and a permanent GPS site. Additional data including a local GPS network, ground penetrating radar measurements and snow densities were collected. In December 2008, during the second field campaign, surface elevation data were acquired using an airborne laser scanner along a trajectory between Gibbs Glacier and Airy Glacier, along the ice divide between both sides of the Peninsula and on Fleming Glacier. The AWS was found protruding only 20 cm above the snow surface, demonstrating the high snow accumulation in the area, which was sufficient to cover the 4 m high tower installed in 2007 and that annual variability in the mass accumulation is significant. The station collected data for 250 days. The permanent GPS stopped collecting data after
NASA Astrophysics Data System (ADS)
Muñoz, M.; Fournier, H.; Mamani, M.; Febrer, J.; Borzotta, E.; Maidana, A.
The first magnetotelluric deep soundings in Chile were carried out during 1986 in the Villarrica active volcano zone (39°25'S, 71°57'W). In the TM mode of polarization, the curves show a distorted segment with dispersion. A static distortion at long periods is observed in curves in the TE mode of polarization; the segment was shifted vertically to fit the geomagnetic global model values at daily periods. This modified curve was used for 1D modelling to determine the electrical structure in the study area. The upper level of the intermediate conducting layer of resistivity 20-60 ω m is found to be at 35-50 km depth. A higher resistivity layer (600 ω m), starting at 100 km depth, may be resolved in the intermediate conducting layer. A sharp decrease in the resistivity is shown by the model at 500 km. Large heterogeneities at the level of the conducting layer encountered in the 1D modelling, and increased resistivity of the ultimate layer, may account for distortion observed at long periods. Two-dimensional test models show that the conducting layer in the area of Villarrica volcano may be an anomalous heated layer surrounded by rocks of higher resistivity of about 2 × 10 3 ω m. These features correspond to the interaction with a subsiding oceanic lithosphere resulting in a complex thermal structure and perturbed resistivity distribution in transition zones of the Pacific type such as Chile, and to the existence of a megafault and a system of fractures in the sounding area. These facts make it difficult to determine the conductance of the electrical asthenosphere. The parameters of the model structure correlate well with geophysical and geochemical results obtained in the area by other workers. Gravity studies indicate a maximum crustal thickness of about 37 km, which implies a non-full compensation according to the Airy hypothesis. The morphology of the Wadati-Benioff zone clearly shows a sharp decrease of earthquake foci at 50 km depth, and a reinitiation of
Scattering resonance of elastic wave and low-frequency equivalent slow wave
NASA Astrophysics Data System (ADS)
Meng, X.; Liu, H.; Hu, T.; Yang, L.
2015-12-01
. Using quaternion and Pfaffian(Dyson 1970) techniques, the matrix's exponential mapping solution is further solved as the hyperbolic trigonometric functions or trigonometric matrix elements. Using the Fourier transform, slow wave's Airy-like function can be obtained. This study shows that slow waves only occur in the case of strong scattering.
NASA Astrophysics Data System (ADS)
Krishna, K. S.; Bull, J. M.; Ishizuka, O.; Scrutton, R. A.; Jaishankar, S.; Banakar, V. K.
2014-02-01
The Afanasy Nikitin seamount (ANS) is a major structural feature (400 km-long and 150 km-wide) in the Central Indian Basin, situated at the southern end of the so-called 85°E Ridge. Combined analyses of new multibeam bathymetric, seismic reflection and geochronological data together with previously described magnetic data provide new insights into the growth of the ANS through time, and its relationship with the 85°E Ridge. The ANS comprises a main plateau, rising 1200 m above the surrounding ocean floor (4800 m), and secondary elevated seamount highs, two of which (lie at 1600 and 2050 m water depths) have the morphology of a guyot, suggesting that they were formed above or close to sea-level. An unbroken sequence of spreading anomalies 34 through 32n.1 identified over the ANS reveal that the main plateau of the ANS was formed at 80-73 Ma, at around the same time as that of the underlying oceanic crust. The 40Ar/39Ar dates for two basalt samples dredged from the seamount highs are consistent, within error, at 67 Ma. These results, together with published results of late Cretaceous to early Cenozoic Indian Ocean plate reconstructions, indicate that the Conrad Rise hotspot emplaced both the main plateau of the ANS and Conrad Rise (including the Marion Dufresne, Ob and Lena seamounts) at 80-73 Ma, close to the India-Antarctica Ridge system. Subsequently, the seamount highs were formed by late-stage volcanism c. 6-13 Myr after the main constructional phase of the seamount plateau. Flexural analysis indicates that the main plateau and seamount highs of the ANS are consistent with Airy-type isostatic compensation, which suggest emplacement of the entire seamount in a near spreading-center setting. This is contrary to the flexural compensation of the 85°E Ridge further north, which is interpreted as being emplaced in an intraplate setting, i.e., 25-35 Myr later than the underlying oceanic crust. Therefore, we suggest that the ANS and the 85°E Ridge appear to be
Empirical Measurement and Model Validation of Infrared Spectra of Contaminated Surfaces
NASA Astrophysics Data System (ADS)
Archer, Sean
The goal of this thesis was to validate predicted infrared spectra of liquid contaminated surfaces from a micro-scale bi-directional reflectance distribution function (BRDF) model through the use of empirical measurement. Liquid contaminated surfaces generally require more sophisticated radiometric modeling to numerically describe surface properties. The Digital Image and Remote Sensing Image Generation (DIRSIG) model utilizes radiative transfer modeling to generate synthetic imagery for a variety of applications. Aside from DIRSIG, a micro-scale model known as microDIRSIG has been developed as a rigorous ray tracing physics-based model that could predict the BRDF of geometric surfaces that are defined as micron to millimeter resolution facets. The model offers an extension from the conventional BRDF models by allowing contaminants to be added as geometric objects to a micro-facet surface. This model was validated through the use of Fourier transform infrared spectrometer measurements. A total of 18 different substrate and contaminant combinations were measured and compared against modeled outputs. The substrates used in this experiment were wood and aluminum that contained three different paint finishes. The paint finishes included no paint, Krylon ultra-flat black, and Krylon glossy black. A silicon based oil (SF96) was measured out and applied to each surface to create three different contamination cases for each surface. Radiance in the longwave infrared region of the electromagnetic spectrum was measured by a Design and Prototypes (D&P) Fourier transform infrared spectrometer and a Physical Sciences Inc. Adaptive Infrared Imaging Spectroradiometer (AIRIS). The model outputs were compared against the measurements quantitatively in both the emissivity and radiance domains. A temperature emissivity separation (TES) algorithm had to be applied to the measured radiance spectra for comparison with the microDIRSIG predicted emissivity spectra. The model predicted
Cenozoic erosion and the preglacial uplift of the Svalbard Barents Sea region
NASA Astrophysics Data System (ADS)
Dimakis, Panagiotis; Braathen, Bjørn Inge; Faleide, Jan Inge; Elverhøi, Anders; Gudlaugsson, Steinar T.
1998-12-01
The creation of the huge fans observed in the western Barents Sea margin can only be explained by assuming extremely high glacial erosion rates in the Barents Sea area. Glacial processes capable of producing such high erosion rates have been proposed, but require the largest part of the preglacial Barents Sea to be subaerial. To investigate the validity of these proposals we have attempted to reconstruct the western preglacial Barents Sea. Our approach was to combine erosion maps based on prepublished data into a single mean valued erosion map covering the whole western Barents Sea and consequently use it together with a simple Airy isostatic model to obtain a first rough estimate of the preglacial topography and bathymetry of the western Barents Sea margin. The mean valued erosion map presented herein is in good volumetric agreement with the sediments deposited in the western Barents Sea margin areas, and as a direct consequence of the averaging procedures employed in its construction we can safely assume that it is the most reliable erosion map based on the available information. By comparing the preglacial sequences with the glacial sequences in the fans we have concluded that 1/2 to 2/3 of the total Cenozoic erosion was glacial in origin and therefore a rough reconstruction of the preglacial relief of the western Barents Sea could be obtained. The results show a subaerial preglacial Barents Sea. Thus, during interglacials and interstadials the area may have been partly glaciated and intensively eroded up to 1 mm/y, while during relatively brief periods of peak glaciation with grounded ice extending to the shelf edge, sediments have been evacuated and deposited at the margins at high rates. The interplay between erosion and uplift represents a typical chicken and egg problem; initial uplift is followed by intensive glacial erosion, compensated by isostatic uplift, which in turn leads to the maintenance of an elevated, and glaciated, terrain. The information we
NASA Astrophysics Data System (ADS)
Clénet, Y.; Gendron, E.; Gratadour, D.; Rousset, G.; Vidal, F.
2015-11-01
arcsec and consequently very low Strehl ratios. We also studied the impact of the outer scale on the point spread function profile, demonstrating that the aforementioned Airy-like pattern is observable even when the outer scale is larger than the telescope diameter. Conclusions: These results could push for the preservation over a large field of the optical quality of any common path optics between the telescope and the instruments in single conjugate adaptive optics mode. This could offer some astrometric capabilities to these instruments operating in this adaptive optics mode.
Constraining the Mean Crustal Thickness on Mercury
NASA Technical Reports Server (NTRS)
Nimmo, F.
2001-01-01
The topography of Mercury is poorly known, with only limited radar and stereo coverage available. However, radar profiles reveal topographic contrasts of several kilometers over wavelengths of approximately 1000 km. The bulk of Mercury's geologic activity took place within the first 1 Ga of the planet's history), and it is therefore likely that these topographic features derive from this period. On Earth, long wavelength topographic features are supported either convectively, or through some combination of isostasy and flexure. Photographic images show no evidence for plume-like features, nor for plate tectonics; I therefore assume that neither convective support nor Pratt isostasy are operating. The composition and structure of the crust of Mercury are almost unknown. The reflectance spectrum of the surface of Mercury is similar to that of the lunar highlands, which are predominantly plagioclase. Anderson et al. used the observed center-of-mass center-of-figure offset together with an assumption of Airy isostasy to infer a crustal thickness of 100-300 km. Based on tidal despinning arguments, the early elastic thickness (T(sub e)) of the (unfractured) lithosphere was approximately equal to or less than 100 km. Thrust faults with lengths of up to 500 km and ages of about 4 Ga B.P. are known to exist on Mercury. Assuming a semicircular slip distribution and a typical thrust fault angle of 10 degrees, the likely vertical depth to the base of these faults is about 45 km. More sophisticated modelling gives similar or slightly smaller answers. The depth to the base of faulting and the elastic layer are usually similar on Earth, and both are thought to be thermally controlled. Assuming that the characteristic temperature is about 750 K, the observed fault depth implies that the heat flux at 4 Ga B.P. is unlikely to be less than 20 mW m(exp -2) for a linear temperature gradient. For an elastic thickness of 45 km, topography at 1000 km wavelength is likely to be about 60
Space Geodesy: The Cross-Disciplinary Earth science (Vening Meinesz Medal Lecture)
NASA Astrophysics Data System (ADS)
Shum, C. K.
2012-04-01
Geodesy during the onset of the 21st Century is evolving into a transformative cross-disciplinary Earth science field. The pioneers before or after the discipline Geodesy was defined include Galileo, Descartes, Kepler, Newton, Euler, Bernoulli, Kant, Laplace, Airy, Kelvin, Jeffreys, Chandler, Meinesz, Kaula, and others. The complicated dynamic processes of the Earth system manifested by interactions between the solid Earth and its fluid layers, including ocean, atmosphere, cryosphere and hydrosphere, and their feedbacks are linked with scientific problems such as global sea-level rise resulting from natural and anthropogenic climate change. Advances in the precision and stability of geodetic and fundamental instrumentations, including clocks, satellite or quasar tracking sensors, altimetry and lidars, synthetic aperture radar interferometry (InSAR), InSAR altimetry, gravimetry and gradiometry, have enabled accentuate and transformative progress in cross-disciplinary Earth sciences. In particular, advances in the measurement of the gravity with modern free-fall methods have reached accuracies of 10-9 g (~1 μGal or 10 nm/s2) or better, allowing accurate measurements of height changes at ~3 mm relative to the Earth's center of mass, and mass transports within the Earth interior or its geophysical fluids, enabling global quantifications of climate-change signals. These contemporary space geodetic and in situ sensors include, but not limited to, satellite radar and laser altimetry/lidars, GNSS/SLR/VLBI/DORIS, InSAR, spaceborne gravimetry from GRACE (Gravity Recovery And Climate Experiment twin-satellite mission) and gradiometry from GOCE (Global Ocean Circulation Experiment), tide gauges, and hydrographic data (XBT/MBT/Argo). The 2007 Intergovernmental Panel for Climate Change (IPCC) study, the Fourth Assessment Report (AR4), substantially narrowed the discrepancy between observation and the known geophysical causes of sea-level rise, but significant uncertainties
NASA Astrophysics Data System (ADS)
Diehl, Theresa Marie
The West Antarctic Ice Sheet (WAIS) is mostly grounded in broad, deep basins (down to 2.5 km below sea level) that are stretched between five crustal blocks. The geometry of the bedrock, being mostly below sea level, induces a fundamental instability in the WAIS through the possibility of runaway grounding line retreat. The crustal environment of the WAIS further influences the ice sheet's fast flow through conditions at the ice-bedrock boundary. This study focuses on understanding the WAIS by examining the subglacial geology (such as volcanoes and sedimentary basins) at the ice-bedrock boundary and the continent's deeper crustal structure- primarily using airborne gravity anomalies. The keystone of this study is a 2004-2005 aerogeophysical survey over one of the most negative mass balance glaciers on the continent: Thwaites Glacier (TG). The gravity anomalies derived from this dataset- as well as gravity-based modeling and spectral crustal boundary depth estimates- reveal a heterogeneous crustal environment beneath the glacier. The widespread Mesozoic rifting observed in the Ross Sea Embayment (RSE) of West Antarctica extends beneath TG, where the crust is ˜27 km thick and cool. Adjacent to TG, spectrally-derived shallow Moho depths for the Marie Byrd Land (MBL) crustal block can be explained by thermal support from warm mantle. I assemble here new compilations of free-air and Bouguer gravity anomalies across West Antarctica (from both airborne and satellite datasets) and re-interpret the extents of West Antarctic crustal block and their boundaries with the rift system. Airy isostatic gravity anomalies reveal that TG is relatively sediment starved, in contrast to the sediment-rich RSE. TG's fast flow velocities could be sustained in this sediment poor environment if higher heat flux in MBL was providing an ample source of subglacial melt water to the glacier. The isostatic anomalies also indicate that TG's outlet rests on a bedrock sill that will impede future
Internal polarization limits coronagraph contrast
NASA Astrophysics Data System (ADS)
Breckinridge, James Bernard; Lam, Wai Sze T.; Chipman, Russell A.
2015-08-01
% encircled energy of this ghost PSF image is centered on the axis and twice as large as the Airy diffraction pattern. 6. This ~1E-5 scattered light level is to be compared to the 1E-9 scattered light level required for terrestrial exoplanet imaging coronagraphy.
NASA Astrophysics Data System (ADS)
Osterbrock, D. E.
2002-12-01
In the years before television, videos, radio. movies, or even loudspeakers, Ormsby MacKnight Mitchel (1809-1862) was the best-known popularizer of astronomy and the scientific study of the universe in nineteenth-century America. Each winter he traveled the country by railroad, steamer, and stagecoach, speaking to large paying crowds in principal cities from Boston, New York, and Philadelphia through Cincinnati to New Orleans on the cosmos and our place in it, with special attention to possible inhabitants of planers orbiting other stars. Mitchel had much the same attraction as Sagan did in our time, and awakened many people's interest in astronomy through the human angle, as Carl did. His argument was simple, and according to Frank Triplett goes back thousands of years: other stars are suns, our sun has planets with people on one of them, why should not other stars also have populated planets? But first Mitchel, like Sagan, always explained clearly the discoveries of astronomy that fleshed out this argument with facts. He emphasized the ``clockwork universe", governed by gravity, that Newton, Herschel, and Laplace had investigated and found to be stable. There were many other similarities between these two great popularizers. Mitchel's base was the Cincinnati Observatory, which he had founded, raising the funds for it himself in small contributions from hundreds of ``members", which he publicised as far more democratic than support from European kings and lords. He went abroad to get a telescope, and finally found his ``Great [12-inch] Refractor" in Munich, with help from John Quincy Adams, Astronomer Royal George Biddle Airy, and Paris Observatory Director Fracois Arago, in spite of a rebuff by President John Tyler. These episodes have similarities in Sagan's lobbying NASA for close-up images of Mars. Views of other American professional astronomers on life on other worlds will also be described briefly, from Denison Olmsted, Elias Loomis, Charles A. Young (who
NASA Astrophysics Data System (ADS)
Nunn, Jeffrey A.
1990-04-01
With few unconstrained assumptions, a simple quantitative model for flexural isostasy between two crustal blocks of different thickness that subsequently undergoes partial relaxation of accumulated stress can explain reactivation of the Sabine Uplift in the mid-Cretaceous. Thin salt over the Sabine Uplift indicates that it was a positive area in the Middle Jurassic but began to subside during the Late Jurassic. During the Late Jurassic and Early Cretaceous, the Sabine Uplift had no topographic expression and was the center of a large, flat bottomed basin covering most of east Texas and north Louisiana. Reactivation of the Sabine Uplift in the mid-Cretaceous caused a minimum of 150 m of uplift and extensive erosion of Lower Cretaceous rocks. During the Late Cretaceous and Tertiary, the Sabine Uplift resumed subsiding but at a slower rate than the adjacent basins. Since the mid-Cretaceous, the Sabine Uplift has risen more than 1 km relative to the East Texas Basin. We suggest that this structural history is consistent with the following simple quantitative model for flexural isostasy. During formation of the Gulf of Mexico in the Late Triassic-Early Jurassic by rifting and extension of the lithosphere, brittle deformation of the crust created small-scale wavelength of tens of kilometers, lateral variations in crustal thickness. Initially, the newly formed margin was in point-wise Airy isostatic equilibrium. Thus synrift and/or early postrift subsidence was characterized by a series of rift valleys or half grabens separated by uplifts. However, as the margin cooled and contracted, the lithosphere became stronger, and subsequent loading was regionally compensated. Thus postrift subsidence was characterized by a broad regional downwarp. If, at some later point in time, the rigid portion of the lithosphere was weakened or relaxed, then lateral density variations would have been recompensated at shorter wavelengths. Thus areas of little or no crustal extension would have
NASA Astrophysics Data System (ADS)
Quartini, E.; Powell, E. M.; Richter, T.; Damiani, T.; Burris, S. G.; Young, D. A.; Blankenship, D. D.
2013-12-01
-air disturbance. Airy isostatic corrections are applied to the Bouguer anomaly where permissible to set the foundation for the identification and discrimination of sedimentary basins and intrusive/extrusive complexes beneath the West Antarctic Ice Sheet. This analysis also provides a framework for interpreting POLENET seismic studies in the region. Successful integration of the gravity and seismic results will ultimately be necessary for understanding the thermal evolution of Marie Byrd Land and its context within the West Antarctic Rift System.
NASA Astrophysics Data System (ADS)
Jordan, Tom; Ferraccioli, Fausto; Armadillo, Egidio; Bozzo, Emanuele
2013-04-01
The Wilkes Subglacial Basin, in the hinterland of the Transantarctic Mountains, represents one of the least understood continental-scale features in Antarctica. Aeromagnetic data suggests that this basin was imposed on a much earlier Ross age back arc region that developed along the former active margin of the East Antarctic Craton (Ferraccioli et al., 2009, Tectonophysics). However, the deeper crustal structure of the basin and its relation with tectonic evolution remains both disputed and poorly constrained. Here, we present new airborne gravity data that reveal the crustal architecture of the northern Wilkes Subglacial Basin. Our gravity models indicate that the crust under the northern Wilkes Subglacial Basin is likely to be 30-35 km thick, i.e. 5-10 km thinner than imaged under the adjacent Transantarctic Mountains, and ~15 km thinner than predicted from some previous flexural and passive seismic models beneath the southern Wilkes Subglacial Basin region. We infer that crustal thickening under northern Victoria Land reflects Ross-age (ca 500 Ma) orogenic events and accretion, followed by partial preservation of the orogenic root since then, as opposed to reflecting the edge of a Mesozoic plateau, which has previously been inferred to have occupied West Antarctica (Bialas et al. 2007, Geology). Airy isostatic anomalies along both flanks of the Wilkes Basin reveal major inherited tectonic structures, which likely controlled the basin location and hence support aeromagnetic interpretations of the Wilkes Subglacial Basin as a structurally controlled basin. The positive anomaly along the western margin of the basin appears to define the tectonic boundary between the East Antarctic Craton and the Ross Orogen, and the anomaly along its eastern flank is interpreted as reflecting high-grade and denser rocks of the central Wilson Terran,e with respect to lower grade meta-sediments and magmatic arc rocks of the western Wilson Terrane and Wilkes Basin region. Our forward
An Integrated Geophysical Analysis of the Western High Atlas/Rif Region of Morocco
NASA Astrophysics Data System (ADS)
Worthington, C.; Keller, G. R.; Beauchamp, W.
2009-12-01
processes including delamination and typical Airy isostasy. Seismic ray tracing is being used to model the seismic reflection lines in the study area to test how well the area’s complicated structure can be imaged.
Cyclic Emergence of Venice During The Brunhes
NASA Astrophysics Data System (ADS)
Kent, D. V.; Rio, D.; Massari, F.; Kukla, G.; Lanci, L.
Milankovitch cycle stratigraphy has become an important method of calibrating the geomagnetic polarity time scale in the Neogene. The resulting geochronological con- straints can be used to interpret the timing of sea level changes and the long-term rate of subsidence in the Venice area, which is located at the northern end of the Adri- atic Sea in a foreland setting between the eastern Southern Alps and the Apennines, the venue of the classic magnetostratigraphic work of Bill Lowrie, Walter Alvarez, and their colleagues. For the Venice region, the Pleistocene history of sea-level change was reconstructed using an integrated magnetobiocyclostratigraphy of lithofacies, includ- ing magnetic susceptibility variations, and a published palynofloral analysis of con- tinuously cored sediments in a 950 meter-deep drill core. A reference glacioeustatic curve was obtained by scaling the astronomically-calibrated ODP677/SPECMAP ben- thic oxygen isotope record from Shackleton (1995). A simple Airy compensation model was used to account for the effect of isostatic loading. Following slow sediment accumulation in a deeper-water starved basin during most of the Matuyama reverse polarity chron, the Venice area shoaled rapidly in the early and middle Brunhes normal polarity chron in response to a major phase of deltaic progradation. The initial transition to continental sediments occurred during a promi- nent glacioeustatic low-stand that is likely to be Marine Isotope Stage 12 (~0.43 Ma) but could be as young as MIS 8 (~0.25 Ma). The Venice area oscillated from below sea level during subsequent major glacioeustatic high-stands to becoming increasingly emergent during major low-stands as the basin continued to fill with marine and con- tinental sediments. Some parts of the Venice area are now emergent for the first time during a glacioeustatic high-stand (i.e., MIS 1 or the Holocene). The total long-term subsidence rate estimated from the Venice deep core record is less than 0.5 mm
On possible plume-guided seismic waves
Julian, B.R.; Evans, J.R.
2010-01-01
Hypothetical thermal plumes in the Earth's mantle are expected to have low seismic-wave speeds and thus would support the propagation of guided elastic waves analogous to fault-zone guided seismic waves, fiber-optic waves, and acoustic waves in the oceanic SOund Fixing And Ranging channel. Plume-guided waves would be insensitive to geometric complexities in the wave guide, and their dispersion would make them distinctive on seismograms and would provide information about wave-guide structure that would complement seismic tomography. Detecting such waves would constitute strong evidence of a new kind for the existence of plumes. A cylindrical channel embedded in an infinite medium supports two classes of axially symmetric elastic-wave modes, torsional and longitudinal-radial. Torsional modes have rectilinear particle motion tangent to the cylinder surface. Longitudinal-radial modes have elliptical particle motion in planes that include the cylinder axis, with retrograde motion near the axis. The direction of elliptical particle motion reverses with distance from the axis: once for the fundamental mode, twice for the first overtone, and so on. Each mode exists only above its cut-off frequency, where the phase and group speeds equal the shear-wave speed in the infinite medium. At high frequencies, both speeds approach the shear-wave speed in the channel. All modes have minima in their group speeds, which produce Airy phases on seismograms. For shear wave-speed contrasts of a few percent, thought to be realistic for thermal plumes in the Earth, the largest signals are inversely dispersed and have dominant frequencies of about 0.1-1 Hz and durations of 15-30 sec. There are at least two possible sources of observable plume waves: (1) the intersection of mantle plumes with high-amplitude core-phase caustics in the deep mantle; and (2) ScS-like reflection at the core-mantle boundary of downward-propagating guided waves. The widespread recent deployment of broadband
NASA Astrophysics Data System (ADS)
Wei, Zigen; Chen, Ling; Li, Zhiwei; Ling, Yuan; Li, Jing
2016-01-01
Eastern China comprises a complex amalgamation of geotectonic blocks of different ages and undergone significant modification of lithosphere during the Meso-Cenozoic time. To better characterize its deep structure, we conducted H-κ stacking of receiver functions using teleseismic data collected from 1143 broadband stations and produced a unified and detailed map of Moho depth and average Poisson's ratio (σ) of eastern China. A coexistence of modified and preserved crust with generally in Airy-type isostatic equilibrium was revealed in eastern China, which correlates well with regional geological and tectonic features. Crust is obviously thicker to the west of the North-South Gravity Lineament but exhibits complex variations in σ with an overall felsic to intermediate bulk crustal composition. Moho depth and σ values show striking differences as compared to the surrounding areas in the rifts and tectonic boundary zones, where earthquakes usually occur. Systematic comparison of Moho depth and σ values demonstrated that there are both similarities and differences in the crustal structure among the Northeast China, North China Craton, South China, and the Qinling-Dabie Orogen as well as different areas within these blocks, which may result from their different evolutionary histories and strong tectonic-magma events since the Mesozoic. Using new data from dense temporary arrays, we observed a change of Moho depth by ∼3 km and of σ by ∼0.04 beneath the Tanlu Fault Zone and an alteration of Moho depth by ∼5 km and of σ by ∼0.05 beneath the Xuefeng Mountains. In addition, striking E-W difference in crustal structure occur across the Xuefeng Mountains: to the east, the Moho depth is overall <35 km and σ has values of <0.26; to the west, the Moho depth is generally >40 km and σ shows complex and large-range variation with values between 0.22 and 0.32. These, together with waveform inversion of receiver functions and SKS shear-wave splitting measurements
Bunmanop, S; Sakuanrungsirikul, S; Manakasem, Y
2011-07-01
White Kwao Krua [Pueraria candollei Grah. var. mirifica (Airy Shaw et Suvatabandhu) Niyomdham] is a herb used as an ingredient in supplementary and cosmetic. The tuberous roots of White Kwao Krua (WKK) contain estrogen-like substances. Seeds of WKK, collected from Prachuab Khiri Khan, were planted and propagated in the farm of Suranaree University of Technology, and their genetic backgrounds were ambiguous. Thirty six plants of WKK in the same age were sampled for classification using 7 botanical characteristics and DNA fingerprint by ISSR-Touchdown PCR technique. The relationship of the 7 botanical characteristics, using principle component analysis (PCA), showed the WKK plants fell into 3 groups. In the first group was plant number 34, which was distinguished from the other plants by its small leaf size. The second group consisted of 23 plants with elliptic leaf shape, acute leaf base, and acuminate leaf apex. The third group consisted of 12 plants with ovate leaf shape, obtuse leaf base, and cuspidate leaf apex. The ISSR-Touchdown PCR technique with 41 primers detected 355 loci of DNA with an average of 8.6 loci per primer. The sizes of DNA ranged between 280 bp to 1550 bp. Two hundred ninety three loci exhibited polymorphisms (82.54%) and the rest 62 loci were monomorphic (17.46%). The polymorphism information content (PIC) was between 0.0315-0.9779 (average 0.4779) and number of effective alleles per locus (Ne) ranged between 1.1250-1.8541 (average 1.5544). Unweighted pair group method with arithmetic mean (UPGMA), Jaccard similarity coefficient and PCA were used to find the construction of genetic relationship of WKK. The genetic similarity (GS) of WKK ranged between 0.50-0.86 (average 0.77). At the GS of 0.56 from cluster analysis, the WKK varieties could be divided into 2 major groups. The first group comprised of plant number 34 and 7, and the second group could be further divided in 2 subgroups at GS of 0.69. None of the WKK plants was identical in
NASA Astrophysics Data System (ADS)
Hueckel, T.; Hu, M.
2015-12-01
Crack propagation in a subcritically stressed rock subject to chemically aggressive environment is analyzed and numerically simulated. Chemically induced weakening is often encountered in hydraulic fracturing of low-permeability oil/gas reservoirs and heat reservoirs, during storage of CO2 and nuclear waste corroding canisters, and other circumstances when rock matrix acidizing is involved. Upon acidizing, mineral mass dissolution is substantially enhanced weakening the rock and causing crack propagation and eventually permeability changes in the medium. The crack process zone is modeled mathematically via a chemo-plastic coupling and chemo-elastic coupling model. In plasticity a two-way coupling is postulated between mineral dissolution and a yield limit of rock matrix. The rate of dissolution is described by a rate law, but the mineral mass removal per unit volume is also a function of a variable internal specific surface area, which is in turn affected by the micro-cracking (treated as a plastic strain). The behavior of the rock matrix is modeled as rigid-plastic adding a chemical softening capacity to Cam-Clay model. Adopting the Extended Johnson's approximation of processes around the crack tip, the evolution of the stress field and deformation as a function of the chemically enhanced rock damage is modeled in a simplified way. In addition, chemical reactive transport is made dependent on plastic strain representing micro-cracking. Depending on mechanical and chemical boundary conditions, the area of enhanced chemical softening is near or somewhat away from the crack tip.In elasticity, chemo-mechanical effect is postulated via a chemical volumetric shrinkage strain proportional to mass removal variable, conceived analogously to thermal expansion. Two versions are considered: of constant coefficient of shrinkage and a variable one, coupled to deviatoric strain. Airy Potential approach used for linear elasticity is extended considering an extra term, which is
NASA Astrophysics Data System (ADS)
Gu, Y. J.; Chen, Y.
2015-12-01
The rapid expansion of regional broadband seismic arrays in Alberta provides an unprecedented opportunity to map the subsurface seismic structure. In this study, we compute the P-to-S receiver functions from 5 regional seismic networks and 62 stations to determine the crustal properties beneath southern-central Alberta, a boundary zone between the Mesozoic Canadian Cordillera and the Precambrian craton(s). The optimal Moho depth and Vp/Vs ratio at each receiver are determined by tracing the direct P, converted (Pms) and reverberated (PpPms and PpSms+PsPms) phases through a three-dimensional shear velocity model. The resulting Moho depth-Vp/Vs ratio (H-K) image shows more coherent stacking amplitudes than the traditional H-K method. The map of Moho depth shows an increase of crustal thickness from an average of 41 km in Precambrian domains to ~50 km beneath the foothills of the Rocky Mountains, which indicates a strong crustal gradient across the craton-domain boundary in the Western Canada Sedimentary Basin (WCSB). The surface elevations along the foreland belt of the Rockies are isostatically compensated by a thickened crustal root, which is consistent with thick-skinned deformation likely sustained during the Laramide phase of the Farallon subduction. To the west of the foreland belt, however, a relatively thin crust with an average thickness of ~36 km is mapped beneath the extreme topography of southern Canadian Rockies. The lack of a deep crustal root is inconsistent with the Airy isostasy model, implying very high temperatures beneath the Cordillera upper mantle. Ratios of average crustal velocities (Vp/Vs) vary from 1.61 to 1.91 across the study region. The smallest values are observed near the northern Snowbird Tectonic Zone (STZ) and Taltson magmatic arc, which suggest a felsic crust resulted from crustal thickening and melting during the early Proterozoic. On the other hand, the Vp/Vs ratio shows the highest value (~1.9) in the vicinity of the Vulcan
Kinematics to dynamics in the New Zealand plate-boundary zone
NASA Astrophysics Data System (ADS)
Lamb, S. H.
2013-12-01
New Zealand straddles the boundary between the Australian and Pacific plate, with a transition from subduction of Pacific oceanic lithosphere beneath North Island, to oblique continental collision in South Island. Cenozoic relative plate motion has resulted in a complex pattern of faulting and block rotation in a zone up to 250 km wide, with displacements on individual faults up to 100s of kilometres. Active deformation must be driven by a combination of plate-boundary forces and internal buoyancy forces. I use a compilation of seismic reflection/refraction studies and high quality receiver function analyses, together with simple Airy isostasy, to determine regional crustal and mantle structure. Integration of the vertical normal stress to the base of the deforming layer yields the buoyancy stress. Horizontal gradients of this can be compared with horizontal gradients of strain rate, using the method of England & Molnar (1997), in the context of a simple thin sheet model of deformation. Thus, if deformation is that of a Newtonian fluid, then appropriate combinations of the horizontal gradients of vorticity and dilatation are related to gradients of buoyancy stress by the fluid viscosity. However, the short term geodetic deformation is strongly biased by elastic strain accumulation related to locking on the plate interface, and cannot be used to determine the plate-boundary velocity field averaged over many seismic cycles (see Lamb & Smith 2013). Therefore, I derive here a velocity field for the plate-boundary zone, which is representative of deformation over tens of thousands of years. This is based on an inversion of fault slip, strain rate azimuth and paleomagnetic data, in the context of the short term relative plate motions, solved in a network of triangles spanning the plate-boundary, using the method of Lamb (2000). A comparison of gradients of buoyancy stress with the appropriate combinations of gradients of vorticity and dilatation shows that deformation in
Long-term Observation of Seafloor Disturbances by Array of Pressure Gauges
NASA Astrophysics Data System (ADS)
Fukao, Y.; Sugioka, H.; Ito, A.; Shiobara, H.
2015-12-01
We developed a seafloor array system of pressure gauges to record disturbances on both the oceanic and solid-Earth sides. The array consists of 10 high-resolution pressure gauges (PARO-8B7000-I-005) in a regular triangle configuration with site intervals of 10 km. The targeted disturbances on the oceanic side include infragravity waves, tsunamis and low-mode internal tides. Those on the solid-Earth side include P-wave families and Rayleigh waves, in particular, the Airy phase of suboceanic Rayleigh waves at periods around 10 s. We confirmed using data from the Nankai Trough seafloor network of pressure gauges (DONET) that our system should enable us to retrieve accurately the first-mode internal tides with the signal power four orders of magnitude smaller than the corresponding semidiurnal surface tides. We installed this system around (32.4N, 140.3E, 1500-2200m depths) on the upper slope of the Izu-Bonin Trench in May 2014. The system was recovered in May-June 2015 and reinstalled around (31.2N, 141.7E, 4700-5700m depths) on the lower slope of this trench in a hope to recover in June 2016 (see Figure). The already recovered data contains records of the tsunami earthquake of May 02, 2015, at epicentral distances around 90 km. Its seismic magnitude was only 5.7, yet the tsunami height was 0.5 m at the 170km-distant island. Our pressure records show P-wave families followed by dispersive tsunami wave trains with amplitudes about 200 Pa successively passing through the array. Although P-wave families of comparable amplitudes were recorded by the M5.6 near-trench low-angle thrust earthquake of May 10, 2015, at epicentral distances around 160 km, they were not followed by any visible tsunami signals. These observations imply merits of sea-bottom pressure array, including easiness of comparing amplitudes of seismic waves and tsunamis on the same record and capability of tracing two-dimensional tsunami propagation through the array as a function of period.
Predicting gravity and sediment thickness in Afghanistan
NASA Astrophysics Data System (ADS)
Jung, W.; Brozena, J.; Peters, M.
2013-02-01
The US Naval Research Laboratory conducted comprehensive high-altitude (7 km above mean sea level) aero-geophysical surveys over Afghanistan in 2006 (Rampant Lion I). The surveys were done in collaboration with the US Geological Survey and upon the request of Islamic Republic of Afghanistan Ministry of Mines. In this study, we show that a best fitting admittance between topography and airborne gravity in western Afghanistan can be used to predict airborne gravity for the no-data area of eastern Afghanistan where the mountains are too high to conduct airborne surveys, due to the threat of ground fire. The differences between the airborne and the predicted gravity along a tie-track through the no-data area were found to be within ±12 mGal range with rms difference 7.3 mGal, while those between the predicted gravity from a simple Airy model (with compensation depth of 32 km and crustal density of 2.67 g cm-3) and the airborne gravity were within ±22 mGal range with rms difference 10.3 mGal. A combined airborne free-air anomaly has been constructed by merging the predicted gravity with the airborne data. We also demonstrate that sediment thickness can be estimated for basin areas where surface topography and airborne free-air anomaly profiles do not show a correlation presumably because of thick sediments. In order to estimate sediment thickness, we first determine a simple linear relationship from a scatter plot of the airborne gravity points and the interpolated Shuttle Radar Topography Mission (SRTM) topography along the Rampant Lion I tracks, and computed corresponding quasi-topography tracks by multiplying the linear relationship with the airborne free-air anomalies. We then take the differences between the SRTM and quasi-topography as a first-order estimate of sediment thickness. A global gravity model (GOCO02S), upward continued to the same altitude (7 km above mean sea level) as the data collection, was compared with the low-pass filtered (with cutoff
Regional-residual separation of bathymetry and revised estimates of Hawaii plume flux
NASA Astrophysics Data System (ADS)
Wessel, Paul
2016-02-01
Observations of the temporal variations in the volume flux of a plume can provide useful constraints on geodynamic models of plumes and plume-plate interactions. Furthermore, they can be compared with observations at other plumes and may be analysed further to understand the nature and cause of the variations. The volume plume flux is typically derived from a sum of edifice and compensation root volumes. The former can be obtained via the application of regional-residual separation procedures that split the observed relief into regional (swell) and residual (edifice) components, while the latter is generally inferred from the former using local (Airy) or regional (flexural) compensation models. Most regional-residual techniques used in past studies give non-unique results and provide no estimates of the uncertainty in the separation, which impacts the significance of the results. Here, the optimal robust separator (ORS) method achieves a unique separation for the swell and edifice components of the Hawaiian Ridge and furthermore obtain confidence bounds on the total volume flux. A fast spectral method for plate flexure with different edifice and infill densities is used to determine compensation volumes. Although my flux estimates have assigned confidence bounds, these are much smaller than the flux estimates themselves. A comparison of my new results to published volume flux curves shows that my revised flux estimates are lower by a factor of 2-3. Reproducing the prior higher results demonstrates that these discrepancies appear to be related to shortcomings in the implementation of the methodology used in the separation. The variability in the Hawaiian plume flux occurs at two different time scales: A short (1-2 Myr) periodicity related to the spacing of islands and seamounts, which ultimately is related to plume-plate flexural interactions, and a much longer (10-15 Myr) periodicity that may be related to plate kinematic changes. Superimposed on these trends may
3D Gravity Field Modelling of the Lithosphere along the Dead Sea Transform (DESERT 2002)
NASA Astrophysics Data System (ADS)
Götze, H.-J.; Ebbing, J.; Schmidt, S.; Rykakov, M.; Hassouneh, M.; Hrahsha, M.; El-Kelani, R.; Desert Group
2003-04-01
From March to May 2002 a gravity field campaign has to be conducted in the area of Dead Sea Rift/Dead Sea Transform with regard to the isostatic state, the crustal density structure of the transform and the lithospheric rigidity in the Central Arava Valley (Jordan). Our multi-national and interdisciplinary gravity group with participants from the Geophysical Institute of Israel, the Natural Resources Authority (Jordan), and the An-Najah National University (Palestine), takes part in the interdisciplinary and international DESERT program which is coordinated by the GeoForschungsZentrum (GFZ, Potsdam, Germany). The study area is located about 100 km away from both the basin of the Dead Sea and the Gulf of Elat/Aqaba basin, respectively. Between March and May 2002 some 800 new gravity observations were recorded at a local scale in the Arava valley and at regional scale along the DESERT seismic line. Station spacing in the area of the Arava valley was 100 - 300 m and in the nearest neighbourhood of the fault 50 m only. The survey of detailed observations covered an area of 10 by 10 km and was completed by a likewise dense survey at the western side of the valley in Israel. All gravity data were tied to the IGSN -71 gravity datum and are terrain-corrected as well. The station complete Bouguer gravity field, Free air anomaly and residual isostatic anomalies (based on both Airy and Vening-Meinesz models) were merged with the existing regional gravity data bases of the region. Constraining information for the 3D density models came from recent geophysical field data acquisition and consist of seismic, seismological, electromagnetic studies, and geological mapping which represent the integrated part of the interdisciplinary research program. Novel methods e.g. curvature techniques, and Euler deconvolution of the gravity fields shed new insight into the structure of upper and lower crust and the causing density domains. In particular the "dip-curvature" reveal a clear course
Gravity Field Analysis and 3D Density Modeling of the Lithosphere Along the Dead Sea Transform
NASA Astrophysics Data System (ADS)
Goetze, H.; Ebbing, J.; Hese, F.; Kollersberger, T.; Schmidt, S.; Rybakov, M.; Hassouneh, M.; Hrahsha, M.; El Kelani, R.
2002-12-01
The gravity field of Dead Sea Rift / Dead Sea Transform was investigated with regard to the isostatic state, the crustal density structure of the orogeny and the rigidity of the lithosphere in the Central Arava Valley. Our multi-national and interdisciplinary gravity group with participants from the Geophysical Institute of Israel, the Natural Resources Authority (Jordan), and the An-Najah National University (Palestine), is aiming to study the crustal density structure, the isostatic state of the lithosphere and mechanical properties of the Dead Sea Rift system under the framework of the international DESERT program which is coordinated by the GeoForschungsZentrum (GFZ, Potsdam, Germany). The study area is located about 100 km away from both the basin of the Dead Sea and the Gulf of Elat/Aqaba basin, respectively. Between March and May 2002 some 800 new gravity observations were recorded at a local (Arava valley) and regional scale (along the DESERT seismic line). Station spacing in the Arava valley was 100 - 300 m and in the nearest neighborhood of the fault 50 m only. The survey of detailed observations covered an area of 10 by 10 km and was completed by a likewise dense survey at the western side of the valley in Israel. All gravity data were tied to the IGSN -71 gravity datum and are terrain-corrected as well. The station complete Bouguer gravity field, Free air anomaly and residual isostatic anomalies (based on both Airy and Vening-Meinesz models) were merged with the existing regional gravity data bases of the region. Constraining information for the 3D density models at regional and local came from recent geophysical field data acquisition and consist of seismic, seismological, electromagnetic, and geologic studies which represent the integrated part of the interdisciplinary research program. Novel methods e.g. curvature techniques, and Euler deconvolution of the gravity fields shed new insight into the structure of upper and lower crust and the causing
Abraham, Thomas; Allan, Sarah E; Levings, Megan K
2010-08-01
In the realm of multi-dimensional confocal microscopy, colocalization analysis of fluorescent emission signals has proven to be an invaluable tool for detecting molecular interactions between biological macromolecules at the subcellular level. We show here that image processing operations such as the deconvolution and chromatic corrections play a crucial role in the accurate determination of colocalization between biological macromolecules particularly when the fluorescent signals are faint, and when the fluorescent signals are in the blue and red emission regions. The cellular system presented here describes quantification of an activated forkhead box P3 (FOXP3) transcription factor in three-dimensional (3D) cellular space. 293T cells transfected with a conditionally active form of FOXP3 were stained for anti-FOXP3 conjugated to a fluorescent red dye (Phycoerythrin), and counterstained for DNA (nucleus) with fluorescent blue dye (Hoechst). Due to the broad emission spectra of these dyes, the fluorescent signals were collected only from peak regions and were acquired sequentially. Since the PE signal was weak, a confocal pinhole size of two Airy size was used to collect the 3D image data sets. The raw images supplemented with the spectral data show the preferential association of activated FOXP3 molecules with the nucleus. However, the PE signals were found to be highly diffusive and colocalization quantification from these raw images was not possible. In order to deconvolve the 3D raw image data set, point spread functions (PSFs) of these emissions were measured. From the measured PSF, we found that chromatic shifts between the blue and red colors were quite considerable. Followed by the applications of both the axial and lateral chromatic corrections, colocalization analysis performed on the deconvolved-chromatic corrected-3D image data set showed that 98% of DNA molecules were associated with FOXP3 molecules, whereas only 66% of FOXP3 molecules were colocalized
Color-coded contour map of Mars M 25M RKN
,
2002-01-01
the International Astronomical Union (IAU) and the International Association of Geodesy (IAG) (Seidelmann and others, 2002), these inertial coordinates were converted into the planet-fixed coordinates (longitude and latitude) used on this map. These values include the orientation of the north pole of Mars (including the effects of precession), the rotation rate of Mars, and a value for W0 of 176.630°, where W0 is the angle along the equator to the east, between the 0° meridian and the equator's intersection with the celestial equator at the standard epoch J2000.0 (Seidelmann and others, 2002). This value of W0 was chosen (Duxbury and others, 2002) in order to place the 0° meridian through the center of the small (~500 m) crater Airy-0, located in the crater Airy (de Vaucouleurs and others, 1973; Seidelmann and others, 2002). Longitude increases to the east, and latitude is planetocentric as allowed by IAU/IAG standards (Seidelmann and others, 2002) and in accordance with current NASA and USGS standards (Duxbury and others, 2002). A secondary grid (printed in red) has been added to the map as a reference to the west longitude/planetographic latitude system that is also allowed by IAU/IAG standards (Seidelmann and others, 2002) and has also been used for Mars. The figure adopted to compute this secondary grid is an oblate spheroid with an equatorial radius of 3,396.19 km and a polar radius of 3,376.2 km (Duxbury and others, 2002; Seidelmann and others, 2002). MAPPING TECHNIQUES To create the topographic base image, the original DEM produced by the MOLA team in Simple Cylindrical projection with a resolution of 64 pixels per degree was projected into the Mercator and Polar Stereographic pieces. A shaded relief was generated from each DEM with a sun angle of 30° from horizontal and a sun azimuth of 270°, as measured clockwise from north, and a vertical exaggeration of 100%. Illumination is from the west, which follows a long-standing USGS tradition for planetary maps
Topographic map of Mars M 25M RKN
,
2002-01-01
the International Astronomical Union (IAU) and the International Association of Geodesy (IAG) (Seidelmann and others, 2002), these inertial coordinates were converted into the planet-fixed coordinates (longitude and latitude) used on this map. These values include the orientation of the north pole of Mars (including the effects of precession), the rotation rate of Mars, and a value for W0 of 176.630°, where W0 is the angle along the equator to the east, between the 0° meridian and the equator's intersection with the celestial equator at the standard epoch J2000.0 (Seidelmann and others, 2002). This value of W0 was chosen (Duxbury and others, 2002) in order to place the 0° meridian through the center of the small (~500 m) crater Airy-0, located in the crater Airy (de Vaucouleurs and others, 1973; Seidelmann and others, 2002). Longitude increases to the east, and latitude is planetocentric as allowed by IAU/IAG standards (Seidelmann and others, 2002) and in accordance with current NASA and USGS standards (Duxbury and others, 2002). A secondary grid (printed in red) has been added to the map as a reference to the west longitude/planetographic latitude system that is also allowed by IAU/IAG standards (Seidelmann and others, 2002) and has also been used for Mars. The figure adopted to compute this secondary grid is an oblate spheroid with an equatorial radius of 3,396.19 km and a polar radius of 3,376.2 km (Duxbury and others, 2002; Seidelmann and others, 2002). MAPPING TECHNIQUES To create the topographic base image, the original DEM produced by the MOLA team in Simple Cylindrical projection with a resolution of 64 pixels per degree was projected into the Mercator and Polar Stereographic pieces. A shaded relief was generated from each DEM with a sun angle of 30° from horizontal and a sun azimuth of 270°, as measured clockwise from north, and a vertical exaggeration of 100%. Illumination is from the west, which follows a long-standing USGS tradition for planetary maps
NASA Astrophysics Data System (ADS)
Teixell, Antonio; Labaume, Pierre; Lagabrielle, Yves
2016-04-01
The evolution of the Pyrenean-Cantabrian orogenic system at the crustal scale is currently reformulated in the light of new concepts of continental hyperextension and mantle exhumation applied to the preorogenic stages. Major advances are being obtained in the frame of programs as TOPOIBERIA, TOPOEUROPE, GDR Marge, PYRAMID, PYROPE and BRGM-RGF. Crustal models developed in the 80's and 90's after the ECORS reflection profiles depicted a precursor Mesozoic rift basin floored by a strongly thinned, but entirely continental substratum, using Airy isostasy. In the past years, a restatement of the significance of the Pyrenean peridotites and the application of concepts from passive continental margins has led to scenarios of extreme crustal attenuation and mantle exhumation during mid-Cretaceous times. New paleothermometrical databases show a generalized high heat flow during the mid and late Cretaceous that accounts for thermal isostasy and explains the apparent disequilibrium between extreme crustal thinning and not so great synrift sedimentary thickness and paleobathymetry. Models for the evolution of the Pyrenean orogeny must consider feedbacks between the Cretaceous hyperextension and the late Cretaceous to Cenozoic inversion. A key challenge is to identify the ancient continental margins of the European and Iberian plates and their suture. New sequential restorations of the compressional structure to selected steps allow a reassessment of the style of convergence through time. In preorogenic reconstructions, end-member models show a tilted-block structure vs. smoothly thinned (boudinaged) margins, overlain by a sedimentary lid detached in the Triassic evaporites. As for the Pyrenees, different models agree that the early stages of convergence involved the subduction of the peridotite "ocean", which was followed by early collision of the thinned continental margins until the crust regained thickness. Late collision involved northward subduction of decoupled lower
Mathematics of tsunami: modelling and identification
NASA Astrophysics Data System (ADS)
Krivorotko, Olga; Kabanikhin, Sergey
2015-04-01
Tsunami (long waves in the deep water) motion caused by underwater earthquakes is described by shallow water equations ( { ηtt = div (gH (x,y)-gradη), (x,y) ∈ Ω, t ∈ (0,T ); η|t=0 = q(x,y), ηt|t=0 = 0, (x,y) ∈ Ω. ( (1) Bottom relief H(x,y) characteristics and the initial perturbation data (a tsunami source q(x,y)) are required for the direct simulation of tsunamis. The main difficulty problem of tsunami modelling is a very big size of the computational domain (Ω = 500 × 1000 kilometres in space and about one hour computational time T for one meter of initial perturbation amplitude max|q|). The calculation of the function η(x,y,t) of three variables in Ω × (0,T) requires large computing resources. We construct a new algorithm to solve numerically the problem of determining the moving tsunami wave height S(x,y) which is based on kinematic-type approach and analytical representation of fundamental solution. Proposed algorithm of determining the function of two variables S(x,y) reduces the number of operations in 1.5 times than solving problem (1). If all functions does not depend on the variable y (one dimensional case), then the moving tsunami wave height satisfies of the well-known Airy-Green formula: S(x) = S(0)° --- 4H (0)/H (x). The problem of identification parameters of a tsunami source using additional measurements of a passing wave is called inverse tsunami problem. We investigate two different inverse problems of determining a tsunami source q(x,y) using two different additional data: Deep-ocean Assessment and Reporting of Tsunamis (DART) measurements and satellite altimeters wave-form images. These problems are severely ill-posed. The main idea consists of combination of two measured data to reconstruct the source parameters. We apply regularization techniques to control the degree of ill-posedness such as Fourier expansion, truncated singular value decomposition, numerical regularization. The algorithm of selecting the truncated number of
The Scientific Papers of James Clerk Maxwell
NASA Astrophysics Data System (ADS)
Clerk Maxwell, James; Niven, W. D.
2011-01-01
27. On the viscosity or internal friction of air and other gases; 28. On the dynamical theory of gases; 29. On the theory of the maintenance of electric currents by mechanical work without the use of permanent magnets; 30. On the equilibrium of a spherical envelope; 31. On the best arrangement for producing a pure spectrum on a screen; 32. The construction of stereograms of surfaces; 33. On reciprocal diagrams in space and their relation to Airy's function of stress; 34. On governors; 35. Experiment in magneto-electric induction; 36. On a method of making a direct comparison of electrostatic with electromagnetic force; 37. On the cyclide; 38. On a bow seen on the surface of ice; 39. On reciprocal figures, frames, and diagrams of forces; 40. On the displacement in a case of fluid motion; 41. Address to the mathematical and physical sections of the British Association, 1870; 42. On colour-vision at different points of the retina; 43. On hills and dales; 44. Introductory lecture on experimental physics; 45. On the solution of electrical problems by the transformation of conjugate functions; 46. On the mathematical classification of physical quantities; 47. On colour vision; 48. On the geometrical mean distance of two figures on a plane; 49. On the induction of electric currents in an infinite plane sheet of uniform conductivity; 50. On the condition that, in the transformation of any figure by curvilinear co-ordinates in three dimensions, every angle in the new figure shall be equal to the corresponding angle in the original figure; 51. Reprint of Papers on electrostatics and magnetism. By Sir W. Thomson. (Review); 52. On the proof of the equations of motion of a connected system; 53. On a problem in the calculus of variations in which the solution is discontinuous; 54. On action at a distance; 55. Elements of natural philosophy. By Sir W. Thomson and P. G. Tait. (Review); 56. On the theory of a system of electrified conductors, and other physical theories involving
Two lithospheric profiles across southern California derived from gravity and seismic data
Romanyuk, T.; Mooney, W.D.; Detweiler, S.
2007-01-01
with mostly basaltic composition. This contradicts the observed, lower Vp/Vs-ratio in the Mojave Desert associated with mostly felsic and low-density crust. Models with lower b coefficients (0.1-0.2) are characterized by an absence of local Airy compensation beneath the San Gabriel Mountains at the LARSE-1 profile. These, and other non-gravity arguments, suggest optimal solutions to the mantle ??-V relation of b ??? 0.2-0.4. This, in turn, means that both thermal and petrological effects occur inside the downwelling of the uppermost mantle high velocity body located beneath the Transverse Ranges. During the development of this mantle downwelling, the basaltic layer of the Mojave block was likely eroded and pulled down into the high velocity body. Those basaltic fragments may have been transformed into eclogites, and this metamorphic change implies a higher b-coefficient density-velocity relationship than would be expected for a purely thermal process.
Fast algorithm for calculation of the moving tsunami wave height
NASA Astrophysics Data System (ADS)
Krivorotko, Olga; Kabanikhin, Sergey
2014-05-01
One of the most urgent problems of mathematical tsunami modeling is estimation of a tsunami wave height while a wave approaches to the coastal zone. There are two methods for solving this problem, namely, Airy-Green formula in one-dimensional case ° --- S(x) = S(0) 4 H(0)/H (x), and numerical solution of an initial-boundary value problem for linear shallow water equations ( { ηtt = div (gH (x,y)gradη), (x,y,t) ∈ ΩT := Ω ×(0,T); ( η|t=0 = q(x,y), ηt|t=0 = 0, (x,y ) ∈ Ω := (0,Lx)× (0,Ly ); (1) η|δΩT = 0. Here η(x,y,t) is the free water surface vertical displacement, H(x,y) is the depth at point (x,y), q(x,y) is the initial amplitude of a tsunami wave, S(x) is a moving tsunami wave height at point x. The main difficulty problem of tsunami modeling is a very big size of the computational domain ΩT. The calculation of the function η(x,y,t) of three variables in ΩT requires large computing resources. We construct a new algorithm to solve numerically the problem of determining the moving tsunami wave height which is based on kinematic-type approach and analytical representation of fundamental solution (2). The wave is supposed to be generated by the seismic fault of the bottom η(x,y,0) = g(y) ·θ(x), where θ(x) is a Heaviside theta-function. Let τ(x,y) be a solution of the eikonal equation 1 τ2x +τ2y = --, gH (x,y) satisfying initial conditions τ(0,y) = 0 and τx(0,y) = (gH (0,y))-1/2. Introducing new variables and new functions: ° -- z = τ(x,y), u(z,y,t) = ηt(x,y,t), b(z,y) = gH(x,y). We obtain an initial-boundary value problem in new variables from (1) ( 2 2 (2 bz- ) { utt = uzz + b uyy + 2b τyuzy + b(τxx + τyy) + 2b + 2bbyτy uz+ ( +2b(bzτy + by)uy, z,y- >2 0,t > 0,2 -1/2 u|t 0,t > 0. Then after some mathematical transformation we get the structure of the function u(x,y,t) in the form u(z,y,t) = S(z,y)·θ(t - z) + ˜u(z,y,t). (2) Here Å©(z,y,t) is a smooth function, S(z,y) is the solution of the problem: { S + b2τ S + (1b2(τ +
Mert Davies: Pioneer in the Use of Spacecraft to Map Earth and Mars
NASA Astrophysics Data System (ADS)
Murray, B.; Augenstein, B.
2002-12-01
-based television teams invented the world?s first digital television cameras using primitive slow-scan vidicon sensors in order to overcome the 200-fold greater distance to Mars. Spacecraft mapping and geodesy was initiated by the dual flybys Mariner 6 and 7 of 1969, each carrying a moderately high resolution optical system, but one plagued by the geometric limitations of a vidicon sensor necessarily using imprecise electro-optical imaging internally. He understood clearly that the number of resolution elements on the Mariner 6/7 cameras were too small for good photogrammetric solutions. Each picture contained only 70,000 resolution elements compared to a standard aerial photograph with about a third of a billion of comparable elements. Despite such limitations, Mert was able to exploit especially the far encounter imaging from Mariners 6/7 to create the first Mars surface control net based on topographic features, and to solve for the position of the rotational pole. Under his leadership, the Mariner 9 orbiter mission greatly expanded that coverage, providing the evolving basis of USGS Mars mapping practically until the present. Furthermore, Mert, in conjunction with Harold Masursky and Gerard de Vaucoleurs, established the topocentric reference point for the prime meridian on Mars as the small crater Airy-O, which thus occupies a role analogous to that of Greenwich, England for the Earth. He was to play that historic prime meridian role for nearly all the solid bodies in the Solar System over the ensuing decades as well as a continuing role on the IAU committee that named officially the surface features of Mercury, Venus, Mars, and the satellites of Jupiter, Saturn, Uranus.
A History of Regression and Related Model-Fitting in the Earth Sciences (1636?-2000)
Howarth, Richard J.
2001-12-15
The (statistical) modeling of the behavior of a dependent variate as a function of one or more predictors provides examples of model-fitting which span the development of the earth sciences from the 17th Century to the present. The historical development of these methods and their subsequent application is reviewed. Bond's predictions (c. 1636 and 1668) of change in the magnetic declination at London may be the earliest attempt to fit such models to geophysical data. Following publication of Newton's theory of gravitation in 1726, analysis of data on the length of a 1{sup o} meridian arc, and the length of a pendulum beating seconds, as a function of sin{sup 2}(latitude), was used to determine the ellipticity of the oblate spheroid defining the Figure of the Earth. The pioneering computational methods of Mayer in 1750, Boscovich in 1755, and Lambert in 1765, and the subsequent independent discoveries of the principle of least squares by Gauss in 1799, Legendre in 1805, and Adrain in 1808, and its later substantiation on the basis of probability theory by Gauss in 1809 were all applied to the analysis of such geodetic and geophysical data. Notable later applications include: the geomagnetic survey of Ireland by Lloyd, Sabine, and Ross in 1836, Gauss's model of the terrestrial magnetic field in 1838, and Airy's 1845 analysis of the residuals from a fit to pendulum lengths, from which he recognized the anomalous character of measurements of gravitational force which had been made on islands. In the early 20th Century applications to geological topics proliferated, but the computational burden effectively held back applications of multivariate analysis. Following World War II, the arrival of digital computers in universities in the 1950s facilitated computation, and fitting linear or polynomial models as a function of geographic coordinates, trend surface analysis, became popular during the 1950-60s. The inception of geostatistics in France at this time by Matheron had
Worldwide complete spherical Bouguer and isostatic anomaly maps
NASA Astrophysics Data System (ADS)
Bonvalot, S.; Balmino, G.; Briais, A.; Peyrefitte, A.; Vales, N.; Biancale, R.; Gabalda, G.; Reinquin, F.
2011-12-01
We present here a set of digital maps of the Earth's gravity anomalies (surface "free air", Bouguer and isostatic), computed at Bureau Gravimetric International (BGI) as a contribution to the Global Geodetic Observing Systems (GGOS) and to the global geophysical maps published by the Commission for the Geological Map of the World (CGMW). The free air and Bouguer anomaly concept is extensively used in geophysical interpretation to investigate the density distributions in the Earth's interior. Complete Bouguer anomalies (including terrain effects) are usually computed at regional scales by integrating the gravity attraction of topography elements over and beyond a given area (under planar or spherical approximations). Here, we developed and applied a worldwide spherical approach aimed to provide a set of homogeneous and high resolution gravity anomaly maps and grids computed at the Earth's surface, taking into account a realistic Earth model and reconciling geophysical and geodetic definitions of gravity anomalies. This first version (1.0) has been computed by spherical harmonics analysis / synthesis of the Earth's topography-bathymetry up to degree 10800. The detailed theory of the spherical harmonics approach is given in Balmino et al., (Journal of Geodesy, submitted). The Bouguer and terrain corrections have thus been computed in spherical geometry at 1'x1' resolution using the ETOPO1 topography/bathymetry, ice surface and bedrock models from the NOAA (National Oceanic and Atmospheric Administration) and taking into account precise characteristics (boundaries and densities) of major lakes, inner seas, polar caps and of land areas below sea level. Isostatic corrections have been computed according to the Airy Heiskanen model in spherical geometry for a constant depth of compensation of 30km. The gravity information given here is provided by the Earth Geopotential Model (EGM2008), developed at degree 2160 by the National Geospatial Intelligence Agency (NGA) (Pavlis
World Gravity Map: a set of global complete spherical Bouguer and isostatic anomaly maps and grids
NASA Astrophysics Data System (ADS)
Bonvalot, S.; Balmino, G.; Briais, A.; Kuhn, M.; Peyrefitte, A.; Vales, N.; Biancale, R.; Gabalda, G.; Reinquin, F.
2012-04-01
We present here a set of digital maps of the Earth's gravity anomalies (surface free air, Bouguer and isostatic), computed at Bureau Gravimetric International (BGI) as a contribution to the Global Geodetic Observing Systems (GGOS) and to the global geophysical maps published by the Commission for the Geological Map of the World (CGMW) with support of UNESCO and other institutions. The Bouguer anomaly concept is extensively used in geophysical interpretation to investigate the density distributions in the Earth's interior. Complete Bouguer anomalies (including terrain effects) are usually computed at regional scales by integrating the gravity attraction of topography elements over and beyond a given area (under planar or spherical approximations). Here, we developed and applied a worldwide spherical approach aimed to provide a set of homogeneous and high resolution gravity anomaly maps and grids computed at the Earth's surface, taking into account a realistic Earth model and reconciling geophysical and geodetic definitions of gravity anomalies. This first version (1.0) has been computed by spherical harmonics analysis / synthesis of the Earth's topography-bathymetry up to degree 10800. The detailed theory of the spherical harmonics approach is given in Balmino et al., (Journal of Geodesy, 2011). The Bouguer and terrain corrections have thus been computed in spherical geometry at 1'x1' resolution using the ETOPO1 topography/bathymetry, ice surface and bedrock models from the NOAA (National Oceanic and Atmospheric Administration) and taking into account precise characteristics (boundaries and densities) of major lakes, inner seas, polar caps and of land areas below sea level. Isostatic corrections have been computed according to the Airy-Heiskanen model in spherical geometry for a constant depth of compensation of 30km. The gravity information given here is provided by the Earth Geopotential Model (EGM2008), developed at degree 2160 by the National Geospatial
The gravity field of the U.S. Atlantic continental margin
Grow, A.J.; Bowin, C.O.; Hutchinson, D.O.
1979-01-01
Approximately 39,000 km of marine gravity data collected during 1975 and 1976 have been integrated with U.S. Navy and other available data over the U.S. Atlantic continental margin between Florida and Maine to obtain a 10 mgal contour free-air gravity anomaly map. A maximum typically ranging from 0 to +70 mgal occurs along the edge of the shelf and Blake Plateau, while a minimum typically ranging from -20 to -80 mgal occurs along the base of the continental slope, except for a -140 mgal minimum at the base of the Blake Escarpment. Although the maximum and minimum free-air gravity values are strongly influenced by continental slope topography and by the abrupt change in crustal thickness across the margin, the peaks and troughs in the anomalies terminate abruptly at discrete transverse zones along the margin. These zones appear to mark major NW-SE fractures in the subsided continental margin and adjacent deep ocean basin, which separate the margin into a series of segmented basins and platforms. Rapid differential subsidence of crustal blocks on either side of these fractures during the early stages after separation of North America and Africa (Jurassic and Early Cretaceous) is inferred to be the cause of most of the gravity transitions along the length of margin. The major transverse zones are southeast of Charleston, east of Cape Hatteras, near Norfolk Canyon, off Delaware Bay, just south of Hudson Canyon and south of Cape Cod. Local Airy isostatic anomaly profiles (two-dimensional, without sediment corrections) were computed along eight multichannel seismic profiles. The isostatic anomaly values over major basins beneath the shelf and rise are generally between -10 and -30 mgal while those over the platform areas are typically 0 to +20 mgal. While a few isostatic anomaly profiles show local 10-20 mgal increases seaward of the East Coast Magnetic Anomaly (ECMA: inferred to mark the ocean-continent boundary), the lack of a consistent correlation indicates that the
The influence of organic substances type on the properties of mineral-organic fertilizers
NASA Astrophysics Data System (ADS)
Huculak-Mä Czka, Marta; Hoffmann, Krystyna; Hoffmann, Józef
2010-05-01
In presented research the lignite coal, peat, poultry droppings and their composts were suggested as a components of mineral-organic fertilizers. Fertility of soil is conditioned by an ability to supply plants with water and nutrients essential to their growth and development. The soil is described as tri-phase system consisting of solid, liquid and gas phase. In solid phase the soil minerals and organic matter can be distinguished. The content of micro-organisms contained in the soil i.e. microfauna and microflora is indispensable for high soil fertility. Nutrients should occur in the forms available for plants in order to obtain high yields of the high quality crops. Organic fertilizing has versatile activity. Increasing contents of humus, providing mineral nutrients included in organic substance and the improvement in physical properties of the soil belong to its main purposes. Due to applying organic fertilizers heavy soils is getting loosen and in consequence become more airy what probably influences stimulation of soil micro-organisms activity. An aqueous as well as sorption capacity of light soils is also increasing, buffer range and the stabilization of the proper level of pH value of the soil, plants are provided with basic macro and micronutrients. Conventional organic fertilizers applied in an arable farms are manure, dung, green manures and composts of different kind. Within compost group the following types can be distinguished: compost from farming, urban wastes, shredded straw, poultry droppings, industrial wastes, bark of coniferous tree etc. Properly developed fertilizer formulas should contain in their composition both mineral as well as organic elements. Such fertilizer should fit its composition to the soil and plant requirements. It should contain organic substance being characterized by a high aqueous and cations sorption capacity, substance undergoing the fast mineralization with the large calcium content. Inorganic substances e.g. bentonites
Apodization in high-contrast long-slit spectroscopy. Closer, deeper, fainter, cooler
NASA Astrophysics Data System (ADS)
Vigan, A.; N'Diaye, M.; Dohlen, K.
2013-07-01
effective temperatures (Teff) and surface gravities (log g) into the data at angular separations of 0.3'' to 1.5'' and with contrast ratios from 6 to 18 mag. Using the SD method to subtract the speckles, we show that the ALSC brings a gain in sensitivity of up to ~3 mag at 0.3'' over the LSC and that both concepts are essentially equivalent for separations larger than 0.5''. The gain at small separation is the result of suppressing of the bright Airy rings that are difficult to estimate at very small angular separations because of the point spread function chromaticity. The improved sensitivity is confirmed by extracting the simulated companions spectra from the data and comparing them to libraries of models to determine their Teff and log g. Using a restoration factor that quantitatively compares the input and output spectra, we show that the ALSC data systematically leads to better quality spectra below 0.5''. In terms of Teff, we demonstrate that at small angular separations the limit with the ALSC is always lower by at least 100 K, inducing an increase in sensitivity of a factor up to 1.8 in objects' masses at young ages. Finally, for the determination of log g, we show that the ALSC provides a less biased estimation than the LSC.
NASA Astrophysics Data System (ADS)
Molnar, P.
1988-09-01
The Tibetan Plateau, the Himalaya and the Karakoram are the most spectacular consequences of the collision of the Indian subcontinent with the rest of Eurasia in Cainozoic time. Accordingly, the deep structures beneath them provide constraints on both the tectonic history of the region and on the dynamic processes that have created these structures. The dispersion of seismic surface waves requires that the crust beneath Tibet be thick: nowhere less than 50 km, at least 65 km, in most areas, but less than 80 km in all areas that have been studied. Wide-angle reflections of P-waves from explosive sources in southern Tibet corroborate the existence of a thick crust but also imply the existence of marked lateral variations in that thickness, or in the velocity structure of the crust. Thus isostatic compensation occurs largely by an Airy-type mechanism, unlike that, for instance, of the Basin and Range Province of western North America where a hot upper mantle buoys up a thin crust. The P-wave and S-wave velocities in the uppermost mantle of most of Tibet are relatively high and typical of those of Precambrian shields and stable platforms: Vp = 8.1 km s-1 or higher, and Vs≈ 4.7 km s-1. Travel times and waveforms of S-waves passing through the uppermost mantle of much of Tibet, however, require a much lower average velocity in the uppermost mantle than that of the Indian, or other, shields. They indicate a thick low-velocity zone in the upper mantle beneath Tibet, reminiscent of tectonically active regions. These data rule out a shield structure beneath northern Tibet and suggest that if such a structure does underlie part of the plateau, it does so only beneath the southern part. Lateral variations in the upper-mantle structure of Tibet are apparent from differences in travel times of S-waves from earthquakes in different parts of Tibet, in the attenuation of short-period phases, Pn and Sn, that propagate through the uppermost mantle of Tibet, and in surface
The Black Canyon of the Gunnison: Today and Yesterday
Hansen, Wallace R.
1965-01-01
Since the early visit of Captain John William Gunnison in the middle of the last century, the Black Canyon of the Gunnison has stirred mixed apprehension and wonder in the hearts of its viewers. It ranks high among the more awesome gorges of North America. Many great western canyons are as well remembered for their brightly colored walls as for their airy depths. Not so the Black Canyon. Though it is assuredly not black, the dark-gray tones of its walls and the hazy shadows of its gloomy depths join together to make its name well deserved. Its name conveys an impression, not a picture. After the first emotional impact of the canyon, the same questions come to the minds of most reflective viewers and in about the following order: How deep is the Black Canyon, how wide, how does it compare with other canyons, what are the rocks, how did it form, and how long did it take? Several western canyons exceed the Black Canyon in overall size. Some are longer; some are deeper; some are narrower; and a few have walls as steep. But no other canyon in North American combines the depth, narrowness, sheerness, and somber countenance of the Black Canyon. In many places the Black Canyon is as deep as it is wide. Between The Narrows and Chasm View in the Black Canyon of the Gunnison National Monument (fig. 15) it is much deeper than wide. Average depth in the monument is about 2,000 feet, ranging from a maximum of about 2,700 feet, north of Warner Point (which also is the greatest depth anywhere in the canyon), to a minimum of about 1,750 feet at The Narrows. The stretch of canyon between Pulpit Rock and Chasm View, including The Narrows, though the shallowest in the monument, is also the narrowest, has some of the steepest walls, and is, therefore, among the most impressive segments of the canyon (fig. 3). Profiles of several well-known western canyons are shown in figure 1. Deepest of these by far is Hells Canyon of the Snake, on the Idaho-Oregon border. Clearly, it dwarfs the
NASA Astrophysics Data System (ADS)
2002-09-01
sensitivity of the VLTI by a factor of almost 100. First results with four Unit Telescopes ESO PR Photo 22b/02 ESO PR Photo 22b/02 [Preview - JPEG: 573 x 400 pix - 78k] [Normal - JPEG: 1145 x 800 pix - 232k] Caption : PR Photo 22b/02 : The left panel shows the rather incomplete set of "baselines" used during the present, short interferometric test exposures (in interferometric terminology: the "UV-plane coverage"). Each baseline is represented by two opposite, short arcs, symmetric around the origin (centre) of the diagram. The colour-coded pattern reflects the telescope pairs (ANTU-KUEYEN = magenta, ANTU-MELIPAL = red, ANTU-YEPUN = green, KUEYEN-MELIPAL = cyan, KUEYEN-YEPUN = blue), as seen from the observed object. Due to the limited time available, this distribution is far from uniform and is quite elongated in one direction. To the right is shown the reconstructed, two-dimensional interferometric point-spread function (PSF) of the star Achernar (in "negative" - with most light in the darkest areas). It is the result of subsequent computer processing of the measurements with the different baselines. On the largest scale, the image consists of an inner, round distribution of light, 0.057 arcsec wide, surrounded by an outer, much weaker, broad "ring" and with a "white" zone between these two areas. This is the "Airy disk" for a single 8.2-m telescope at this infrared wavelength (the K-band at 2.2 µm). It represents the maximum resolution (image sharpness) obtainable when observing with a single telescope. As explained in the text, the interferometric "addition" of more telescopes greatly improves that resolution. The width of the individual - slightly S-shaped - lines ("fringes") in the inclined pattern visible in the inner area, about 0.003 arcsec, represents the achieved interferometric resolution in one direction (with an angular diameter of about 0.002 arcsec, the disk of Achernar is not resolved, making it a suitable object for this resolution test). The resolution in