Vortex Airy beams directly generated via liquid crystal q-Airy-plates

NASA Astrophysics Data System (ADS)

Wei, Bing-Yan; Liu, Sheng; Chen, Peng; Qi, Shu-Xia; Zhang, Yi; Hu, Wei; Lu, Yan-Qing; Zhao, Jian-Lin

2018-03-01

Liquid crystal q-Airy-plates with director distributions integrated by q-plates and polarization Airy masks are proposed and demonstrated via the photoalignment technique. Single/dual vortex Airy beams of opposite topological charges and orthogonal circular polarizations are directly generated with polarization-controllable characteristic. The singular phase of the vortex part is verified by both astigmatic transformation and digital holography. The trajectory of vortex Airy beams is investigated, manifesting separate propagation dynamics of optical vortices and Airy beams. Meanwhile, Airy beams still keep their intrinsic transverse acceleration, self-healing, and nondiffraction features. This work provides a versatile candidate for generating high-quality vortex Airy beams.

Generation of electron Airy beams.

PubMed

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.

Thermo-Electro-Mechanical Analysis of a Curved Functionally Graded Piezoelectric Actuator with Sandwich Structure

PubMed Central

Yan, Zhi; Zaman, Mostafa; Jiang, Liying

2011-01-01

In this work, the problem of a curved functionally graded piezoelectric (FGP) actuator with sandwich structure under electrical and thermal loads is investigated. The middle layer in the sandwich structure is functionally graded with the piezoelectric coefficient g31 varying continuously along the radial direction of the curved actuator. Based on the theory of linear piezoelectricity, analytical solutions are obtained by using Airy stress function to examine the effects of material gradient and heat conduction on the performance of the curved actuator. It is found that the material gradient and thermal load have significant influence on the electroelastic fields and the mechanical response of the curved FGP actuator. Without the sacrifice of actuation deflection, smaller internal stresses are generated by using the sandwich actuator with functionally graded piezoelectric layer instead of the conventional bimorph actuator. This work is very helpful for the design and application of curved piezoelectric actuators under thermal environment. PMID:28824130

Solitons shedding from Airy beams and bound states of breathing Airy solitons in nonlocal nonlinear media

PubMed Central

Shen, Ming; Gao, Jinsong; Ge, Lijuan

2015-01-01

We investigate the spatially optical solitons shedding from Airy beams and anomalous interactions of Airy beams in nonlocal nonlinear media by means of direct numerical simulations. Numerical results show that nonlocality has profound effects on the propagation dynamics of the solitons shedding from the Airy beam. It is also shown that the strong nonlocality can support periodic intensity distribution of Airy beams with opposite bending directions. Nonlocality also provides a long-range attractive force between Airy beams, leading to the formation of stable bound states of both in-phase and out-of-phase breathing Airy solitons which always repel in local media. PMID:25900878

Maximum nondiffracting propagation distance of aperture-truncated Airy beams

NASA Astrophysics Data System (ADS)

Chu, Xingchun; Zhao, Shanghong; Fang, Yingwu

2018-05-01

Airy beams have called attention of many researchers due to their non-diffracting, self-healing and transverse accelerating properties. A key issue in research of Airy beams and its applications is how to evaluate their nondiffracting propagation distance. In this paper, the critical transverse extent of physically realizable Airy beams is analyzed under the local spatial frequency methodology. The maximum nondiffracting propagation distance of aperture-truncated Airy beams is formulated and analyzed based on their local spatial frequency. The validity of the formula is verified by comparing the maximum nondiffracting propagation distance of an aperture-truncated ideal Airy beam, aperture-truncated exponentially decaying Airy beam and exponentially decaying Airy beam. Results show that the formula can be used to evaluate accurately the maximum nondiffracting propagation distance of an aperture-truncated ideal Airy beam. Therefore, it can guide us to select appropriate parameters to generate Airy beams with long nondiffracting propagation distance that have potential application in the fields of laser weapons or optical communications.

Closed-form analysis of fiber-matrix interface stresses under thermo-mechanical loadings

NASA Technical Reports Server (NTRS)

Naik, Rajiv A.; Crews, John H., Jr.

1992-01-01

Closed form techniques for calculating fiber matrix (FM) interface stresses, using repeating square and diamond regular arrays, were presented for a unidirectional composite under thermo-mechanical loadings. An Airy's stress function micromechanics approach from the literature, developed for calculating overall composite moduli, was extended in the present study to compute FM interface stresses for a unidirectional graphite/epoxy (AS4/3501-6) composite under thermal, longitudinal, transverse, transverse shear, and longitudinal shear loadings. Comparison with finite element results indicate excellent agreement of the FM interface stresses for the square array. Under thermal and longitudinal loading, the square array has the same FM peak stresses as the diamond array. The square array predicted higher stress concentrations under transverse normal and longitudinal shear loadings than the diamond array. Under transverse shear loading, the square array had a higher stress concentration while the diamond array had a higher radial stress concentration. Stress concentration factors under transverse shear and longitudinal shear loadings were very sensitive to fiber volume fraction. The present analysis provides a simple way to calculate accurate FM interface stresses for both the square and diamond array configurations.

Two kinds of Airy-related beams

NASA Astrophysics Data System (ADS)

Xu, Yiqing; Zhou, Guoquan; Zhang, Lijun; Ru, Guoyun

2015-08-01

Two kinds of Airy-related beams are introduced in this manuscript. The normalized intensity distribution in the x-direction of the two kinds of Airy-related beams is close to that of the Gaussian beam. The normalized intensity distribution in the y-direction of the two kinds of Airy-related beams is close to that of the second-order and the third-order elegant Hermite-Gaussian beams, respectively. Analytical expressions of the two kinds of Airy-related beams passing through an ABCD paraxial optical system are derived. The beam propagation factors for the two kinds of Airy-related beams are 1.933 and 2.125, respectively. Analytical expressions of the beam half widths and the kurtosis parameters of the two kinds of Airy-related beams passing through an ABCD paraxial optical system are also presented. As a numerical example, the propagation properties of the two kinds of Airy-related beams are demonstrated in free space. Moreover, the comparison between the two kinds of Airy-related beams and their corresponding elegant Hermite-Gaussian beams along the two transverse directions are performed in detail. Upon propagation, the former kind of Airy-related beam will evolve from the central bright beam into the dark hollow beam. Contrarily, the latter kind of Airy-related beam will evolve from the dark hollow beam into the central bright beam. These two kinds of Airy-related beams can be used to describe specially distributed beams.

Airy function approach and Numerov method to study the anharmonic oscillator potentials V(x) = Ax{sup 2α} + Bx{sup 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al Sdran, N.; Najran University, Faculty of Sciences and Arts, Najran; Maiz, F., E-mail: fethimaiz@gmail.com

2016-06-15

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) = Ax{sup 2α} + Bx{sup 2}, (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) bymore » 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.« less

Evolution of arbitrary moments of radiant intensity distribution for partially coherent general beams in atmospheric turbulence

NASA Astrophysics Data System (ADS)

Dan, Youquan; Xu, Yonggen

2018-04-01

The evolution law of arbitrary order moments of the Wigner distribution function, which can be applied to the different spatial power spectra, is obtained for partially coherent general beams propagating in atmospheric turbulence using the extended Huygens-Fresnel principle. A coupling coefficient of radiant intensity distribution (RID) in turbulence is introduced. Analytical expressions of the evolution of the first five-order moments, kurtosis parameter, coupling coefficient of RID for general beams in turbulence are derived, and the formulas are applied to Airy beams. Results show that there exist two types for general beams in turbulence. A larger value of kurtosis parameter for Airy beams also reveals that coupling effect due to turbulence is stronger. Both theoretical analysis and numerical results show that the maximum value of kurtosis parameter for an Airy beam in turbulence is independent of turbulence strength parameter and is only determined by inner scale of turbulence. Relative angular spread, kurtosis and coupling coefficient are less influenced by turbulence for Airy beams with a smaller decay factor and a smaller initial width of the first lobe.

Role of third-order dispersion in chirped Airy pulse propagation in single-mode fibers

NASA Astrophysics Data System (ADS)

Cai, Wangyang; Wang, Lei; Wen, Shuangchun

2018-04-01

The dynamic propagation of the initial chirped Airy pulse in single-mode fibers is studied numerically, special attention being paid to the role of the third-order dispersion (TOD). It is shown that for the positive TOD, the Airy pulse experiences inversion irrespective of the sign of initial chirp. The role of TOD in the dynamic propagation of the initial chirped Airy pulse depends on the combined sign of the group-velocity dispersion (GVD) and the initial chirp. If the GVD and chirp have the opposite signs, the chirped Airy pulse compresses first and passes through a breakdown area, then reconstructs a new Airy pattern with opposite acceleration, with the breakdown area becoming small and the main peak of the new Airy pattern becoming asymmetric with an oscillatory structure due to the positive TOD. If the GVD and chirp have the same signs, the finite-energy Airy pulse compresses to a focal point and then inverses its acceleration, in the case of positive TOD, the distance to the focal point becoming smaller. At zero-dispersion point, the finite-energy Airy pulse inverses to the opposite acceleration at a focal point, with the tight-focusing effect being reduced by initial chirp. Under the effect of negative TOD, the initial chirped Airy pulse disperses and the lobes split. In addition, in the anomalous dispersion region, for strong nonlinearity, the initial chirped Airy pulse splits and enters a soliton shedding regime.

On the dynamics of Airy beams in nonlinear media with nonlinear losses.

PubMed

Ruiz-Jiménez, Carlos; Nóbrega, K Z; Porras, Miguel A

2015-04-06

We investigate on the nonlinear dynamics of Airy beams in a regime where nonlinear losses due to multi-photon absorption are significant. We identify the nonlinear Airy beam (NAB) that preserves the amplitude of the inward Hänkel component as an attractor of the dynamics. This attractor governs also the dynamics of finite-power (apodized) Airy beams, irrespective of the location of the entrance plane in the medium with respect to the Airy waist plane. A soft (linear) input long before the waist, however, strongly speeds up NAB formation and its persistence as a quasi-stationary beam in comparison to an abrupt input at the Airy waist plane, and promotes the formation of a new type of highly dissipative, fully nonlinear Airy beam not described so far.

Wedge-shaped potential and Airy-function electron localization in oxide superlattices.

PubMed

Popovic, Z S; Satpathy, S

2005-05-06

Oxide superlattices and microstructures hold the promise for creating a new class of devices with unprecedented functionalities. Density-functional studies of the recently fabricated, lattice-matched perovskite titanates (SrTiO3)n/(LaTiO3)m reveal a classic wedge-shaped potential well for the monolayer (m = 1) structure, originating from the Coulomb potential of a two-dimensional charged La sheet. The potential in turn confines the electrons in the Airy-function-localized states. Magnetism is suppressed for the monolayer structure, while in structures with a thicker LaTiO3 part, bulk antiferromagnetism is recovered, with a narrow transition region separating the magnetic LaTiO3 and the nonmagnetic SrTiO3.

The robustness of truncated Airy beam in PT Gaussian potentials media

NASA Astrophysics Data System (ADS)

Wang, Xianni; Fu, Xiquan; Huang, Xianwei; Yang, Yijun; Bai, Yanfeng

2018-03-01

The robustness of truncated Airy beam in parity-time (PT) symmetric Gaussian potentials media is numerically investigated. A high-peak power beam sheds from the Airy beam due to the media modulation while the Airy wavefront still retain its self-bending and non-diffraction characteristics under the influence of modulation parameters. Increasing the modulation factor results in the smaller value of maximum power of the center beam, and the opposite trend occurs with the increment of the modulation depth. However, the parabolic trajectory of the Airy wavefront does not be influenced. By utilizing the unique features, the Airy beam can be used as a long distance transmission source under the PT symmetric Gaussian potentials medium.

Doubly-focused echos from spheres unfold into a hyperbolic umbilic diffraction catastrophe

NASA Astrophysics Data System (ADS)

Dzikowicz, Ben; Marston, Philip L.

2003-04-01

An underwater spherical target resides in an Airy field formed by reflection off a curved surface representing the sea floor or sea surface. In prior work [B. Dzikowicz and P. L. Marston, J. Acoust. Soc Am. 110, 2778 (2001)] direct returns of a tone burst from the surface reflection focused toward the target were shown to have a dependence on the target position described by an Airy function. The return echo can also be focused again by the surface onto the source and receive transducer. This gives the square of an Airy function for the case of a point target. With a finite sized target (as in the experiment) this goes over to a hyperbolic umbilic catastrophe with symmetric arguments. The arguments of the hyperbolic umbilic function are derived from only the relative return times of a transient pulse. Experiment confirms the predicted merging of transient echoes in the time domain, as well as the hyperbolic umbilic diffraction integral amplitudes for a tone burst. This method would allow for the observation of a target at a greater distance in the presence of a focusing surface. [Research supported by ONR.

Airy pulse shaping using time-dependent power-law potentials

NASA Astrophysics Data System (ADS)

Han, Tianwen; Chen, Hao; Qin, Chengzhi; Li, Wenwan; Wang, Bing; Lu, Peixiang

2018-06-01

We investigate the temporal and spectral evolutions of finite-energy Airy pulses in the presence of power-law optical potentials. The potentials are generated by the time-dependent pumped light, which propagates together with the Airy pulses in a highly nonlinear optical fiber. We show that the intrinsic acceleration of Airy pulses can be modified by an external force that stems from a linear potential, and hence unidirectional frequency shift can be realized. When a triangle potential is employed, the pulse will exhibit self-splitting both in temporal and spectral domains. Additionally, as a parabolic potential is utilized, both the temporal waveform and frequency spectrum of the Airy pulse will exchange alternately between the Airy and Gaussian profiles. By using higher-order power-law potentials, we also realize both revival and antirevival effects for the Airy pulses. The study may find wide applications in pulse reshaping and spectral-temporal imaging for both optical communication and signal processing.

Airy beam self-focusing in a photorefractive medium

PubMed Central

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

What's the matter with Enceladus' gravity?

NASA Astrophysics Data System (ADS)

Rivoldini, A.; Beuthe, M.; Trinh, A.

2016-12-01

Isostasy is clearly at work on Enceladus: long-wavelength gravity is positively correlated with topography, but also well compensated. If the influence of Enceladus' fast spin is taken into account, Airy isostasy implies a very thick crust (50 km) above a very thin ocean, in flat contradiction of the thin crust (20 km) implied by librations. In a desperate attempt to solve the problem, it was recently proposed to substitute flexural isostasy to Airy isostasy, using librations as a constraint on the crust thickness. However the huge lithospheric stresses required to support the load result in complete lithospheric failure. Here we propose a new isostatic model based on the sound physical principle of minimum crustal stress. We demonstrate that gravity combined with topography predicts a 20 km thick crust agreeing with - but independent from - the libration constraint. A consistent picture finally emerges from gravity-topography analysis, confirming that the south polar crust is only a few kilometres thick. Enceladus' resonant companion, Dione, is in a similar state of minimum stress isostasy. Its gravity and topography can be explained in terms of a 100 km thick isostatic crust overlying a 60 km thick global ocean, thus providing the first clear evidence for a present-day ocean within Dione.

Airy beams on two dimensional materials

NASA Astrophysics Data System (ADS)

Imran, Muhammad; Li, Rujiang; Jiang, Yuyu; Lin, Xiao; Zheng, Bin; Dehdashti, Shahram; Xu, Zhiwei; Wang, Huaping

2018-05-01

We propose that quasi-transverse-magnetic (quasi-TM) Airy beams can be supported on two dimensional (2D) materials. By taking graphene as a typical example, the solution of quasi-TM Airy beams is studied under the paraxial approximation. The analytical field intensity in a bilayer graphene-based planar plasmonic waveguide is confirmed by the simulation results. Due to the tunability of the chemical potential of graphene, the self-accelerating behavior of the quasi-TM Airy beam can be steered effectively. 2D materials thus provide a good platform to investigate the propagation of Airy beams.

Solitonic characteristics of Airy beam nonlinear propagation

NASA Astrophysics Data System (ADS)

Bouchet, Thomas; Marsal, Nicolas; Sciamanna, Marc; Wolfersberger, Delphine

2018-05-01

We analyze the nonlinear propagation of a one-dimensional Airy beam. Under nonlinear focusing conditions, the Airy beam splits into a weak accelerating structure and a beam that has been named an "off-shooting soliton." Experimental measurements and numerical results related to the off-shooting Airy beam are compared to soliton theoretical profiles and a good agreement is found in terms of transverse shape, width, and amplitude. We identify the different parameters to generate an Airy beam off-shooting soliton and demonstrate that its profile is also preserved through propagation over long distances.

Quantum polarization fluctuations of an Airy beam in turbulent atmosphere in a slant path.

PubMed

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.

Beam wander of coherent and partially coherent Airy beam arrays in a turbulent atmosphere

NASA Astrophysics Data System (ADS)

Wen, Wei; Jin, Ying; Hu, Mingjun; Liu, Xianlong; Cai, Yangjian; Zou, Chenjuan; Luo, Mi; Zhou, Liwang; Chu, Xiuxiang

2018-05-01

The beam wander properties of coherent and partially coherent Airy beam arrays in a turbulent atmosphere are investigated. Based on the analytical results, we find that the beam wander of partially coherent Airy beam arrays is significantly reduced compared with the wander of a partially coherent Airy beam by numerical simulation. Moreover, the beam wander of a 2 × 2 partially coherent Airy beam arrays is significantly reduced compared with the wander of a 2 × 2 partially coherent Gaussian beam arrays. By using the definition of beam wander arrays factor which is used to characterize the capability of beam arrays for reducing the beam wander effect compared with a single beam, we find that the arrays factor of partially coherent Airy beam arrays is significantly less than that of partially coherent Gaussian beam arrays with the same arrays order. We also find that an artificial reduction of the initial coherence of laser arrays can be used to decrease the beam wander effect. These results indicate that the partially coherent Airy beam arrays have potential applications in long-distance free-space optical communications.

Scattering of Airy elastic sheets by a cylindrical cavity in a solid.

PubMed

Mitri, F G

2017-11-01

The prediction of the elastic scattering by voids (and cracks) in materials is an important process in structural health monitoring, phononic crystals, metamaterials and non-destructive evaluation/imaging to name a few examples. Earlier analytical theories and numerical computations considered the elastic scattering by voids in plane waves of infinite extent. However, current research suggesting the use of (limited-diffracting, accelerating and self-healing) Airy acoustical-sheet beams for non-destructive evaluation or imaging applications in elastic solids requires the development of an improved analytical formalism to predict the scattering efficiency used as a priori information in quantitative material characterization. Based on the definition of the time-averaged scattered power flow density, an analytical expression for the scattering efficiency of a cylindrical empty cavity (i.e., void) encased in an elastic medium is derived for compressional and normally-polarized shear-wave Airy beams. The multipole expansion method using cylindrical wave functions is utilized. Numerical computations for the scattering energy efficiency factors for compressional and shear waves illustrate the analysis with particular emphasis on the Airy beam parameters and the non-dimensional frequency, for various elastic materials surrounding the cavity. The ratio of the compressional to the shear wave speed stimulates the generation of elastic resonances, which are manifested as a series of peaks in the scattering efficiency plots. The present analysis provides an improved method for the computations of the scattering energy efficiency factors using compressional and shear-wave Airy beams in elastic materials as opposed to plane waves of infinite extent. Copyright © 2017 Elsevier B.V. All rights reserved.

Dynamic Control of Collapse in a Vortex Airy Beam

PubMed Central

Chen, Rui-Pin; Chew, Khian-Hooi; He, Sailing

2013-01-01

Here we study systematically the self-focusing dynamics and collapse of vortex Airy optical beams in a Kerr medium. The collapse is suppressed compared to a non-vortex Airy beam in a Kerr medium due to the existence of vortex fields. The locations of collapse depend sensitively on the initial power, vortex order, and modulation parameters. The collapse may occur in a position where the initial field is nearly zero, while no collapse appears in the region where the initial field is mainly distributed. Compared with a non-vortex Airy beam, the collapse of a vortex Airy beam can occur at a position away from the area of the initial field distribution. Our study shows the possibility of controlling and manipulating the collapse, especially the precise position of collapse, by purposely choosing appropriate initial power, vortex order or modulation parameters of a vortex Airy beam. PMID:23518858

Dynamic propagation of symmetric Airy pulses with initial chirps in an optical fiber

NASA Astrophysics Data System (ADS)

Shi, Xiaohui; Huang, Xianwei; Deng, Yangbao; Tan, Chao; Bai, Yanfeng; Fu, Xiquan

2017-09-01

We analytically and numerically investigate the propagation dynamics of initially chirped symmetric Airy pulses in an optical fiber. The results show that the positive chirps act to promote the interference in generating a focal point on the propagation axis, while the negative chirps tend to suppress the focusing effect, as compared to conventional unchirped symmetric Airy pulses. The numerical results demonstrate that the linear propagation of chirped symmetric Airy pulses depend considerably on the chirp parameter and the primary lobe position. In the anomalous dispersion region, positively chirped symmetric Airy pulses first undergo an initial compression, and reach a foci due to the opposite acceleration, and then experience a lossy inversion transformation, and come to the opposite facing focal position. The impact of truncation coefficient and Kerr nonlinearity on the chirped symmetric Airy pulses propagation is also disclosed separately.

Modified fundamental Airy wave.

PubMed

Seshadri, S R

2014-01-01

The propagation characteristics of the fundamental Airy wave are obtained; the intensity distribution is the same as that for a point electric dipole situated at the origin and oriented normal to the propagation direction. The propagation characteristics of the modified fundamental Airy wave are determined. These characteristics are the same as those for the fundamental Gaussian wave provided that an equivalent waist is identified for the Airy wave. In general, the waves are localized spatially with the peak in the propagation direction.

On numerical solutions to the QCD ’t Hooft equation in the limit of large quark mass

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 Hooftmore » equation. We also present a simple intuition behind these results.« less

Quasi-Airy beams along tunable propagation trajectories and directions.

PubMed

Qian, Yixian; Zhang, Site

2016-05-02

We present a theoretical and experimental exhibit that accelerates quasi-Airy beams propagating along arbitrarily appointed parabolic trajectories and directions in free space. We also demonstrate that such quasi-Airy beams can be generated by a tunable phase pattern, where two disturbance factors are introduced. The topological structures of quasi-Airy beams are readily manipulated with tunable phase patterns. Quasi-Airy beams still possess the characteristics of non-diffraction, self-healing to some extent, although they are not the solutions for paraxial wave equation. The experiments show the results are consistent with theoretical predictions. It is believed that the property of propagation along arbitrarily desired parabolic trajectories will provide a broad application in trapping atom and living cell manipulation.

Computer processing of Mars Odyssey THEMIS IR imaging, MGS MOLA altimetry and Mars Express stereo imaging to locate Airy-0, the Mars prime meridian reference

NASA Astrophysics Data System (ADS)

Duxbury, Thomas; Neukum, Gerhard; Smith, David E.; Christensen, Philip; Neumann, Gregory; Albee, Arden; Caplinger, Michael; Seregina, N. V.; Kirk, Randolph L.

The small crater Airy-0 was selected from Mariner 9 images to be the reference for the Mars prime meridian. Initial analyses were made in year 2000 to tie Viking Orbiter and Mars Orbiter Camera images of Airy-0 to the evolving Mars Orbiter Laser Altimeter global digital terrain model to improve the location accuracy of Airy-0. Based upon this tie and radiometric tracking of landers / rovers from earth, new expressions for the Mars spin axis direction, spin rate and prime meridian epoch value were produced to define the orientation of the Martian surface in inertial space over time. Now that the Mars Global Surveyor mission and the Mars Orbiter Laser Altimeter global digital terrain model are complete, a more exhaustive study has been performed to determine the location of Airy-0 relative to the global terrain grid. THEMIS IR image cubes of the Airy and Gale crater regions were tied to the global terrain grid using precision stereo photogrammetric image processing techniques. The Airy-0 location was determined to be within 50 meters of the currently defined IAU prime meridian, with this offset at the limiting absolute accuracy of the global terrain grid. Additional outputs of this study were a controlled multi-band photomosaic of Airy, precision alignment and geometric models of the ten THEMIS IR bands and a controlled multi-band photomosaic of Gale crater used to validate the Mars Surface Laboratory operational map products supporting their successful landing on Mars.

Study on THz wave generation from air plasma induced by quasi-square Airy beam

NASA Astrophysics Data System (ADS)

Zhang, Shijing; Zhang, Liangliang; Jiang, Guangtong; Zhang, Cunlin; Zhao, Yuejin

2018-01-01

Terahertz (THz) wave has attracted considerable attention in recent years because of its potential applications. The intense THz waves generated from air plasma induced by two-color femtosecond laser are widely used due to its high generation efficiency and broad frequency bandwidth. The parameters of the laser change the distribution of the air plasma, and then affect the generation of THz wave. In this research, we investigate the THz wave generation from air plasma induced by quasi-square Airy beam. Unlike the common Gauss beam, the quasi-square Airy beam has ability to autofocus and to increase the maximum intensity at the focus. By using the spatial light modulator (SLM), we can change the parameters of phase map to control the shape of the Airy beam. We obtain the two-color laser field by a 100-um-thick BBO crystal, then use a Golay detector to record THz wave energy. By comparing terahertz generation at different modulation depths, we find that terahertz energy produced by quasi-square Airy beam is up to 3.1 times stronger than that of Gauss beam with identical laser energy. In order to understand the influence of quasi-square Airy beam on the BBO crystal, we record THz wave energy by changing the azimuthal angle of BBO crystal with Gauss beam and Airy beam at different modulation depths. We find that the trend of terahertz energy with respect to the azimuthal angle of the BBO crystal keeps the same for different laser beams. We believe that the quasi-square Airy beam or other auto focusing beam can significantly improve the efficiency of terahertz wave generation and pave the way for its applications.

Probing neural tissue with airy light-sheet microscopy: investigation of imaging performance at depth within turbid media

NASA Astrophysics Data System (ADS)

Nylk, Jonathan; McCluskey, Kaley; Aggarwal, Sanya; Tello, Javier A.; Dholakia, Kishan

2017-02-01

Light-sheet microscopy (LSM) has received great interest for fluorescent imaging applications in biomedicine as it facilitates three-dimensional visualisation of large sample volumes with high spatiotemporal resolution whilst minimising irradiation of, and photo-damage to the specimen. Despite these advantages, LSM can only visualize superficial layers of turbid tissues, such as mammalian neural tissue. Propagation-invariant light modes have played a key role in the development of high-resolution LSM techniques as they overcome the natural divergence of a Gaussian beam, enabling uniform and thin light-sheets over large distances. Most notably, Bessel and Airy beam-based light-sheet imaging modalities have been demonstrated. In the single-photon excitation regime and in lightly scattering specimens, Airy-LSM has given competitive performance with advanced Bessel-LSM techniques. Airy and Bessel beams share the property of self-healing, the ability of the beam to regenerate its transverse beam profile after propagation around an obstacle. Bessel-LSM techniques have been shown to increase the penetration-depth of the illumination into turbid specimens but this effect has been understudied in biologically relevant tissues, particularly for Airy beams. It is expected that Airy-LSM will give a similar enhancement over Gaussian-LSM. In this paper, we report on the comparison of Airy-LSM and Gaussian-LSM imaging modalities within cleared and non-cleared mouse brain tissue. In particular, we examine image quality versus tissue depth by quantitative spatial Fourier analysis of neural structures in virally transduced fluorescent tissue sections, showing a three-fold enhancement at 50 μm depth into non-cleared tissue with Airy-LSM. Complimentary analysis is performed by resolution measurements in bead-injected tissue sections.

What is the diffraction limit? From Airy to Abbe using direct numerical integration

NASA Astrophysics Data System (ADS)

Calm, Y. M.; Merlo, J. M.; Burns, M. J.; Kempa, K.; Naughton, M. J.

The resolution of a conventional optical microscope is sometimes taken from Airy's point spread function (PSF), 0 . 61 λ / NA , and sometimes from Abbe, λ / 2 NA , where NA is the numerical aperture, however modern fluorescence and near-field optical microscopies achieve spatial resolution far better than either of these limits. There is a new category of 2D metamaterials called planar optical elements (POEs), which have a microscopic thickness (< λ), macroscopic transverse dimensions (> 100 λ), and are composed of an array of nanostructured light scatterers. POEs are found in a range of micro- and nano-photonic technologies, and will influence the future optical nanoscopy. With this pretext, we shed some light on the 'diffraction limit' by numerically evaluating Kirchhoff's scalar formulae (in their exact form) and identifying the features of highly non-paraxial, 3D PSFs. We show that the Airy and Abbe criteria are connected, and we comment on the design rules for a particular type of POE: the flat lens. This work is supported by the W. M. Keck Foundation.

Generation and investigation of terahertz Airy beam realized using parallel-plate waveguides

NASA Astrophysics Data System (ADS)

Wu, Mengru; Lang, Tingting; Shi, Guohua; Han, Zhanghua

2018-03-01

In this paper, the launching of Airy beam in the terahertz region using waveguiding structures was proposed, designed and numerically characterized. By properly designing the waveguide slit width and the packing number in different sections of parallel-plate waveguides (PPWGs) array, arbitrary phase delay and lateral position-dependent amplitude transmission through the structure, required to realize the target Airy beam profile, can be easily fulfilled. Airy beams working at the frequency of 0.3 THz with good non-diffracting, self-bending, and self-healing features are demonstrated. This study represents a new alternative to scattering-based metasurface structures, and can be utilized in many modern applications.

Ultrafast Airy beam optical parametric oscillator

PubMed Central

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

Three-dimensional wave-induced current model equations and radiation stresses

NASA Astrophysics Data System (ADS)

Xia, Hua-yong

2017-08-01

After the approach by Mellor (2003, 2008), the present paper reports on a repeated effort to derive the equations for three-dimensional wave-induced current. Via the vertical momentum equation and a proper coordinate transformation, the phase-averaged wave dynamic pressure is well treated, and a continuous and depth-dependent radiation stress tensor, rather than the controversial delta Dirac function at the surface shown in Mellor (2008), is provided. Besides, a phase-averaged vertical momentum flux over a sloping bottom is introduced. All the inconsistencies in Mellor (2003, 2008), pointed out by Ardhuin et al. (2008) and Bennis and Ardhuin (2011), are overcome in the presently revised equations. In a test case with a sloping sea bed, as shown in Ardhuin et al. (2008), the wave-driving forces derived in the present equations are in good balance, and no spurious vertical circulation occurs outside the surf zone, indicating that Airy's wave theory and the approach of Mellor (2003, 2008) are applicable for the derivation of the wave-induced current model.

Statistical mechanics framework for static granular matter.

PubMed

Henkes, Silke; Chakraborty, Bulbul

2009-06-01

The physical properties of granular materials have been extensively studied in recent years. So far, however, there exists no theoretical framework which can explain the observations in a unified manner beyond the phenomenological jamming diagram. This work focuses on the case of static granular matter, where we have constructed a statistical ensemble which mirrors equilibrium statistical mechanics. This ensemble, which is based on the conservation properties of the stress tensor, is distinct from the original Edwards ensemble and applies to packings of deformable grains. We combine it with a field theoretical analysis of the packings, where the field is the Airy stress function derived from the force and torque balance conditions. In this framework, Point J characterized by a diverging stiffness of the pressure fluctuations. Separately, we present a phenomenological mean-field theory of the jamming transition, which incorporates the mean contact number as a variable. We link both approaches in the context of the marginal rigidity picture proposed by Wyart and others.

Spiral spectrum of Airy beams propagation through moderate-to-strong turbulence of maritime atmosphere.

PubMed

Zhu, Yun; Zhang, Yixin; Hu, Zhengda

2016-05-16

The spatial coherence radius in moderate-to-strong maritime turbulence is derived on the basis of the modified Rytov approximation. Models are developed to simulate the spiral spectrum of Airy beams propagating through moderate-to-strong maritime turbulence. In the moderate-to-strong irradiance fluctuation region, we analyze the effects of maritime turbulence on the spread of the spiral spectrum of Airy beams in a horizontal propagation path. Results indicate that the increment in the inner-scale significantly increases the received power. By contrast, the outer-scale elicits a negligible effect on the received power if the ratio of the inner-scale to the outer-scale is less than 0.01. The outer-scale affects the received power only if the ratio is greater than 0.01. The performance of a light source is essential for the received power of Airy beams carrying orbital angular momentum (OAM) through moderate-to-strong maritime turbulence. Airy beams with longer wavelengths, smaller OAM numbers, larger radii of the main ring, and smaller diameters of the circular aperture are less affected by maritime turbulence. Autofocusing of Airy beams is beneficial for the propagation of the spiral spectrum in a certain propagation distance. These results contribute to the design of optical communication systems with OAM encoding for moderate-to-strong maritime turbulence.

Propagation of an Airy beam through the atmosphere.

PubMed

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.

Self-accelerating Airy-Ince-Gaussian and Airy-Helical-Ince-Gaussian light bullets in free space.

PubMed

Peng, Yulian; Chen, Bo; Peng, Xi; Zhou, Meiling; Zhang, Liping; Li, Dongdong; Deng, Dongmei

2016-08-22

The evolution of the three-dimensional (3D) self-accelerating Airy-Ince-Gaussian (AiIG) and Airy-Helical-Ince-Gaussian (AiHIG) light bullets is investigated by solving the (3+1)D linear spatiotemporal evolution equation of an optical field analytically. As far as we know, the numerical experimental demonstrations of the Ince-Gaussian (IG) and Helical-Ince-Gaussian (HIG) beams in various modes are first developed to study the evolution characteristics of the different 3D spatiotemporal light bullets. A conclusion can be drawn that the different photoelastics, pulse stacked, boundary, elliptical ring and physically separated in-line vortices can be achieved by adjusting the ellipticity, the evolution distance and the mode-number of light bullets.

The location of Airy-0, the Mars prime meridian reference, from stereo photogrammetric processing of THEMIS IR imaging and digital elevation data

NASA Astrophysics Data System (ADS)

Duxbury, T. C.; Christensen, P.; Smith, D. E.; Neumann, G. A.; Kirk, R. L.; Caplinger, M. A.; Albee, A. A.; Seregina, N. V.; Neukum, G.; Archinal, B. A.

2014-12-01

The small crater Airy-0 was selected from Mariner 9 images to be the reference for the Mars prime meridian. Initial analyses in the year 2000 tied Viking Orbiter and Mars Orbiter Camera images of Airy-0 to the evolving Mars Orbiter Laser Altimeter global digital terrain model to update the location of Airy-0. Based upon this tie and radiometric tracking of landers/rovers from Earth, new expressions for the Mars spin axis direction, spin rate, and prime meridian epoch value were produced to define the orientation of the Martian surface in inertial space over time. Since the Mars Global Surveyor mission and Mars Orbiter Laser Altimeter global digital terrain model were completed some time ago, a more exhaustive study has been performed to determine the accuracy of the Airy-0 location and orientation of Mars at the standard epoch. Thermal Emission Imaging System (THEMIS) IR image cubes of the Airy and Gale crater regions were tied to the global terrain grid using precision stereo photogrammetric image processing techniques. The Airy-0 location was determined to be about 0.001° east of its predicted location using the currently defined International Astronomical Union (IAU) prime meridian location. Information on this new location and how it was derived will be provided to the NASA Mars Exploration Program Geodesy and Cartography Working Group for their assessment. This NASA group will make a recommendation to the IAU Working Group on Cartographic Coordinates and Rotational Elements to update the expression for the Mars spin axis direction, spin rate, and prime meridian location.

Obstacle evasion in free-space optical communications utilizing Airy beams.

PubMed

Zhu, Guoxuan; Wen, Yuanhui; Wu, Xiong; Chen, Yujie; Liu, Jie; Yu, Siyuan

2018-03-15

A high speed free-space optical communication system capable of self-bending signal transmission around line-of-sight obstacles is proposed and demonstrated. Airy beams are generated and controlled to achieve different propagating trajectories, and the signal transmission characteristics of these beams around the obstacle are investigated. Our results confirm that, by optimizing their ballistic trajectories, Airy beams are able to bypass obstacles with more signal energy and thus improve the communication performance compared with normal Gaussian beams.

Obstacle evasion in free-space optical communications utilizing Airy beams

NASA Astrophysics Data System (ADS)

Zhu, Guoxuan; Wen, Yuanhui; Wu, Xiong; Chen, Yujie; Liu, Jie; Yu, Siyuan

2018-03-01

A high speed free-space optical communication system capable of self-bending signal transmission around line-of-sight obstacles is proposed and demonstrated. Airy beams are generated and controlled to achieve different propagating trajectories, and the signal transmission characteristics of these beams around the obstacle are investigated. Our results confirm that, by optimising their ballistic trajectories, Airy beams are able to bypass obstacles with more signal energy and thus improve the communication performance compared with normal Gaussian beams.

Quantitative comparison of self-healing ability between Bessel–Gaussian beam and Airy beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wen, Wei; Chu, Xiuxiang, E-mail: xiuxiangchu@yahoo.com

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 Airymore » beam. To confirm this result, the intensity profiles of Bessel–Gaussian beam and Airy beam with different similarities are numerically calculated and compared.« less

Multi-gigahertz, femtosecond Airy beam optical parametric oscillator pumped at 78 MHz

PubMed Central

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

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.

Accelerating Airy beams with non-parabolic trajectories

NASA Astrophysics Data System (ADS)

Besieris, Ioannis M.; Shaarawi, Amr M.

2014-11-01

A class of Airy accelerating beams with non-parabolic trajectories are derived by means of a novel application of a conformal transformation originally due to Bateman. It is also shown that the salient features of these beams are very simply incorporated in a solution which is derived by applying a conventional conformal transformation together with a Galilean translation to the basic accelerating Airy beam solution of the two-dimensional paraxial equation. Motivation for the non-parabolic beam trajectories is provided and the effects of finite-energy requirements are discussed.

Airy Wave Packets Accelerating in Space-Time

NASA Astrophysics Data System (ADS)

Kondakci, H. Esat; Abouraddy, Ayman F.

2018-04-01

Although diffractive spreading is an unavoidable feature of all wave phenomena, certain waveforms can attain propagation invariance. A lesser-explored strategy for achieving optical self-similar propagation exploits the modification of the spatiotemporal field structure when observed in reference frames moving at relativistic speeds. For such an observer, it is predicted that the associated Lorentz boost can bring to a halt the axial dynamics of a wave packet of an arbitrary profile. This phenomenon is particularly striking in the case of a self-accelerating beam—such as an Airy beam—whose peak normally undergoes a transverse displacement upon free propagation. Here we synthesize an acceleration-free Airy wave packet that travels in a straight line by deforming its spatiotemporal spectrum to reproduce the impact of a Lorentz boost. The roles of the axial spatial coordinate and time are swapped, leading to "time diffraction" manifested in self-acceleration observed in the propagating Airy wave-packet frame.

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.

Hubert Airy, contemporary men of science and the migraine aura.

PubMed

Eadie, M J

2009-09-01

Although there had been occasional references to the visual aura of migraine even in ancient medicine, little attention was given to the phenomenon until the first half of the nineteenth century when French authors began to describe it. In the medicine of English-speaking countries, apart from a few descriptions, it went largely unnoticed until the British Astronomer Royal, Sir George Airy, described his own experience of the visual aura in 1865. Five years later his son, Hubert Airy, also described his experience of it and that of a number of eminent contemporary men of science. The topic of the migraine aura was almost immediately taken up by two of the younger Airy's contemporaries and fellow Cambridge medical graduates, Peter Wallrock Latham and Edward Liveing, in their monographs. Subsequently, migraine with aura quickly became a well-recognised clinical entity in British medicine.

Luigi Gatteschi's work on asymptotics of special functions and their zeros

NASA Astrophysics Data System (ADS)

Gautschi, Walter; Giordano, Carla

2008-12-01

A good portion of Gatteschi's research publications-about 65%-is devoted to asymptotics of special functions and their zeros. Most prominently among the special functions studied figure classical orthogonal polynomials, notably Jacobi polynomials and their special cases, Laguerre polynomials, and Hermite polynomials by implication. Other important classes of special functions dealt with are Bessel functions of the first and second kind, Airy functions, and confluent hypergeometric functions, both in Tricomi's and Whittaker's form. This work is reviewed here, and organized along methodological lines.

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.

Wavefronts, actions and caustics determined by the probability density of an Airy beam

NASA Astrophysics Data System (ADS)

Espíndola-Ramos, Ernesto; Silva-Ortigoza, Gilberto; Sosa-Sánchez, Citlalli Teresa; Julián-Macías, Israel; de Jesús Cabrera-Rosas, Omar; Ortega-Vidals, Paula; Alejandro Juárez-Reyes, Salvador; González-Juárez, Adriana; Silva-Ortigoza, Ramón

2018-07-01

The main contribution of the present work is to use the probability density of an Airy beam to identify its maxima with the family of caustics associated with the wavefronts determined by the level curves of a one-parameter family of solutions to the Hamilton–Jacobi equation with a given potential. To this end, we give a classical mechanics characterization of a solution of the one-dimensional Schrödinger equation in free space determined by a complete integral of the Hamilton–Jacobi and Laplace equations in free space. That is, with this type of solution, we associate a two-parameter family of wavefronts in the spacetime, which are the level curves of a one-parameter family of solutions to the Hamilton–Jacobi equation with a determined potential, and a one-parameter family of caustics. The general results are applied to an Airy beam to show that the maxima of its probability density provide a discrete set of: caustics, wavefronts and potentials. The results presented here are a natural generalization of those obtained by Berry and Balazs in 1979 for an Airy beam. Finally, we remark that, in a natural manner, each maxima of the probability density of an Airy beam determines a Hamiltonian system.

Autofocusing Airy beam STED microscopy with long focal distance

NASA Astrophysics Data System (ADS)

Hu, Di; Liang, Yao; Chen, Yin; Chen, Zan Hui; Huang, Xu Guang

2017-12-01

Stimulated emission depletion (STED) is a very important technique in super-resolution microscopy. Until now, while autofocusing Airy beam (AAB) has been an attractive theme for both theoretical and applied researches, there are almost no report on AABs being used in STED microscopy. In this paper, we propose a novel STED microscopy based on AABs. A radially symmetric 3/2 phase plate is involved to simultaneously generate autofocusing excitation- and depletion-Airy beams. Remarkably, the AAB can auto-focus to a wavelength-scale spot with a long focal depth (several millimeters): on the contrary, the working distance of a conventional high numerical aperture (NA) objective is usually very short (about 200 μm). Our calculations indicate that the AAB based STED microscopy can achieve a super-resolution spot with FWHM of 58 nm while the focal length is 4.638 mm. Moreover, with properties of non-diffracting and self-healing, the Airy beam could enable a reduction of the scattering distortion induced by the specimens and has a great potential in imaging thick specimens.

"Extraneous government business": the Astronomer Royal as government scientist: George Airy and his work on the commissions of state and other bodies, 1838-1880

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.

Generation of ultra-wideband achromatic Airy plasmons on a graphene surface.

PubMed

Guan, Chunying; Yuan, Tingting; Chu, Rang; Shen, Yize; Zhu, Zheng; Shi, Jinhui; Li, Ping; Yuan, Libo; Brambilla, Gilberto

2017-02-01

Tunable ultra-wideband achromatic plasmonic Airy beams are demonstrated on graphene surfaces. Surface plasmonic polaritons are excited using diffractive gratings. The phase and amplitude of plasmonic waves on the graphene surface are determined by the relative position between the grating arrays and the duty ratio of the grating unit cell, respectively. The transverse acceleration and nondiffraction properties of plasmonic waves are observed. The achromatic Airy plasmons with identical acceleration trajectory at different excited frequencies can be achieved by tuning dynamically the Fermi energy of graphene without reoptimizing the grating structures. The proposed devices may find applications in photonics integrations and surface optical manipulation.

Direct generation of abruptly focusing vortex beams using a 3/2 radial phase-only pattern.

PubMed

Davis, Jeffrey A; Cottrell, Don M; Zinn, Jonathan M

2013-03-20

Abruptly focusing Airy beams have previously been generated using a radial cubic phase pattern that represents the Fourier transform of the Airy beam. The Fourier transform of this pattern is formed using a system length of 2f, where f is the focal length of the Fourier transform lens. In this work, we directly generate these abruptly focusing Airy beams using a 3/2 radial phase pattern encoded onto a liquid crystal display. The resulting optical system is much shorter. In addition, we can easily produce vortex patterns at the focal point of these beams. Experimental results match theoretical predictions.

Development of Finite Elements for Two-Dimensional Structural Analysis Using the Integrated Force Method

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.

Relativistic Bessel cylinders

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.

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.

Plume-Surface Interaction Modeling for a Human-Scale Mars Lander

NASA Technical Reports Server (NTRS)

Hart, Kenneth

2017-01-01

Landing vehicles impart thermal and strain energy onto the landing site from the retrorocket exhaust. Depending on the design of the vehicle, the energy may be great enough to cause spallation at the landing site. This damage may be minor and repairable in the case of landing on a terrestrial landing pad. For missions to other planetary bodies, the spallation may cause the landing site to become uneven and unstable, as well as damage. Simulating this phenomenon in a laboratory or computationally would require a significant amount of time and other resources. These resources typically are not available during the design phase of a mission. This paper presents a computationally-efficient model for the temperature and stress distributions that arise during landing. These quantities can be used along with existing failure criteria, such as the Hoek-Brown criterion for geological materials, to quickly determine whether spallation will occur. The stress and temperature distributions at the landing site are inherently 3D; however, there is a plane of symmetry and in that plane the distributions are 2D. Both quantities are modeled using series solutions to their governing partial differential equations (PDEs). The stress is modeled using the Airy stress potential function and its governing PDE is the biharmonic equation. The temperature is governed by Fourier's law. The models assume that stress due to gravity can be neglected, the points in the plane do not accelerate, and that the material properties are constant.

The Martian Prime Meridian -- Longitude "Zero"

NASA Image and Video Library

2001-02-08

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. Mädler 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, 746A46), and these two images were the basis of the martian longitude system for the rest of the 20th Century. The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) has attempted to take a picture of Airy-0 on every close overflight since the beginning of the MGS mapping mission. It is a measure of the difficulty of hitting such a small target that nine attempts were required, since the spacecraft did not pass directly over Airy-0 until almost the end of the MGS primary mission, on orbit 8280 (January 13, 2001). In the left figure above, the outlines of the Mariner 9, Viking, and Mars Global Surveyor images are shown on a MOC wide angle context image, M23-00924. In the right figure, sections of each of the three images showing the crater Airy-0 are presented. A is a piece of the Mariner 9 image, B is from the Viking image, and C is from the MGS image. Airy-0 is the larger crater toward the top-center in each frame. The MOC observations of Airy-0 not only provide a detailed geological close-up of this historic reference feature, they will be used to improve our knowledge of the locations of all features on Mars, which will in turn enable more precise landings on the Red Planet by future spacecraft and explorers. http://photojournal.jpl.nasa.gov/catalog/PIA03207

Exact result in strong wave turbulence of thin elastic plates

NASA Astrophysics Data System (ADS)

Düring, Gustavo; Krstulovic, Giorgio

2018-02-01

An exact result concerning the energy transfers between nonlinear waves of a thin elastic plate is derived. Following Kolmogorov's original ideas in hydrodynamical turbulence, but applied to the Föppl-von Kármán equation for thin plates, the corresponding Kármán-Howarth-Monin relation and an equivalent of the 4/5 -Kolmogorov's law is derived. A third-order structure function involving increments of the amplitude, velocity, and the Airy stress function of a plate, is proven to be equal to -ɛ ℓ , where ℓ is a length scale in the inertial range at which the increments are evaluated and ɛ the energy dissipation rate. Numerical data confirm this law. In addition, a useful definition of the energy fluxes in Fourier space is introduced and proven numerically to be flat in the inertial range. The exact results derived in this Rapid Communication are valid for both weak and strong wave turbulence. They could be used as a theoretical benchmark of new wave-turbulence theories and to develop further analogies with hydrodynamical turbulence.

75 FR 14381 - Amendment of Class E Airspace; Mount Airy, NC

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-25

... triplicate to the Docket Management System (see ADDRESSES section for address and phone number). You may also... proposes to amend Class E Airspace at Mount Airy, NC, to accommodate the additional airspace needed for the... enhances the safety and airspace management of Instrument Flight Rules (IFR) operations at the airport...

Thermoacoustic focusing lens by symmetric Airy beams with phase manipulations

NASA Astrophysics Data System (ADS)

Liu, Chen; Xia, Jian-Ping; Sun, Hong-Xiang; Yuan, Shou-Qi

2017-12-01

We report the realization of broadband acoustic focusing lenses based on two symmetric thermoacoustic phased arrays of Airy beams, in which the units of thermoacoustic phase control are designed by employing air with different temperatures surrounded by rigid insulated boundaries and thermal insulation films. The phase delays of the transmitted and reflected units could cover a whole 2π interval, which arises from the change of the sound velocity of air induced by the variation of the temperature. Based on the units of phase control, we design the transmitted and reflected acoustic focusing lenses with two symmetric Airy beams, and verify the high self-healing focusing characteristic and the feasibility of the thermal insulation films. Besides, the influences of the bending angle of the Airy beam on the focusing performance are discussed in detail. The proposed acoustic lens has advantages of broad bandwidth (about 4.8 kHz), high focusing performance, self-healing feature, and simple structure, which enable it to provide more schemes for acoustic focusing. It has excellent potential applications in acoustic devices.

Sub-Airy Confocal Adaptive Optics Scanning Ophthalmoscopy.

PubMed

Sredar, Nripun; Fagbemi, Oladipo E; Dubra, Alfredo

2018-04-01

To demonstrate the viability of improving transverse image resolution in reflectance scanning adaptive optics ophthalmoscopy using sub-Airy disk confocal detection. The foveal cone mosaic was imaged in five human subjects free of known eye disease using two custom adaptive optics scanning light ophthalmoscopes (AOSLOs) in reflectance with 7.75 and 4.30 mm pupil diameters. Confocal pinholes of 0.5, 0.6, 0.8, and 1.0 Airy disk diameters (ADDs) were used in a retinal conjugate plane before the light detector. Average cone photoreceptor intensity profile width and power spectrum were calculated for the resulting images. Detected energy using a model eye was recorded for each pinhole size. The cone photoreceptor mosaic is better resolved with decreasing confocal pinhole size, with the high spatial frequency content of the images enhanced in both the large- and small-pupil AOSLOs. The average cone intensity profile width was reduced by ∼15% with the use of a 0.5 ADD pinhole when compared to a 1.0 ADD, with an accompanying reduction in signal greater than a factor of four. The use of sub-Airy disk confocal pinhole detection without increasing retinal light exposure results in a substantial improvement in image resolution at the cost of larger than predicted signal reduction. Improvement in transverse resolution using sub-Airy disk confocal detection is a practical and low-cost approach that is applicable to all point- and line-scanning ophthalmoscopes, including optical coherence tomographers.

Sub-Airy Confocal Adaptive Optics Scanning Ophthalmoscopy

PubMed Central

Sredar, Nripun; Fagbemi, Oladipo E.

2018-01-01

Purpose To demonstrate the viability of improving transverse image resolution in reflectance scanning adaptive optics ophthalmoscopy using sub-Airy disk confocal detection. Methods The foveal cone mosaic was imaged in five human subjects free of known eye disease using two custom adaptive optics scanning light ophthalmoscopes (AOSLOs) in reflectance with 7.75 and 4.30 mm pupil diameters. Confocal pinholes of 0.5, 0.6, 0.8, and 1.0 Airy disk diameters (ADDs) were used in a retinal conjugate plane before the light detector. Average cone photoreceptor intensity profile width and power spectrum were calculated for the resulting images. Detected energy using a model eye was recorded for each pinhole size. Results The cone photoreceptor mosaic is better resolved with decreasing confocal pinhole size, with the high spatial frequency content of the images enhanced in both the large- and small-pupil AOSLOs. The average cone intensity profile width was reduced by ∼15% with the use of a 0.5 ADD pinhole when compared to a 1.0 ADD, with an accompanying reduction in signal greater than a factor of four. Conclusions The use of sub-Airy disk confocal pinhole detection without increasing retinal light exposure results in a substantial improvement in image resolution at the cost of larger than predicted signal reduction. Translational Relevance Improvement in transverse resolution using sub-Airy disk confocal detection is a practical and low-cost approach that is applicable to all point- and line-scanning ophthalmoscopes, including optical coherence tomographers. PMID:29629239

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 acoustic levitation, long-distance particle transport and manipulation, as well as acousto-fluidics directly benefit from the results of this analysis.

Sensing of DNA by Graphene-on-Silicon FET Structures at DC and 101 GHz

DTIC Science & Technology

2015-01-01

For each G in Fig. 2, T displays the oscillatory Airy-function behavior characteristic of all parallel-plate etalons (and Fabry – Perot resonators) with...approximately 5 mm. The output signal from the Schottky rectifier is fed to a 1000-gain low-noise voltage ampli- fier, and then demodulated with a lock-in

Optimal control of the ballistic motion of Airy beams.

PubMed

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.

Selectively transporting small chiral particles with circularly polarized Airy beams.

PubMed

Lu, Wanli; Chen, Huajin; Guo, Sandong; Liu, Shiyang; Lin, Zhifang

2018-05-01

Based on the full wave simulation, we demonstrate that a circularly polarized vector Airy beam can selectively transport small chiral particles along a curved trajectory via the chirality-tailored optical forces. The transverse optical forces can draw the chiral particles with different particle chirality towards or away from the intensity maxima of the beam, leading to the selective trapping in the transverse plane. The transversely trapped chiral particles are then accelerated along a curved trajectory of the Airy beam by the chirality-tailored longitudinal scattering force, rendering an alternative way to sort and/or transport chiral particles with specified helicity. Finally, the underlying physics of the chirality induced transverse trap and de-trap phenomena are examined by the analytical theory within the dipole approximation.

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.

Porters, watchmen, and the crime of William Sayers: the non-scientific staff of the Royal Observatory, Greenwich, in Victorian times

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.

A comparative study of some mathematical models of the mean wind structure and aerodynamic drag of plant canopies

NASA Technical Reports Server (NTRS)

Massman, William

1987-01-01

A semianalytical method for describing the mean wind profile and shear stress within plant canopies and for estimating the roughness length and the displacement height is presented. This method incorporates density and vertical structure of the canopy and includes simple parameterizations of the roughness sublayer and shelter factor. Some of the wind profiles examined are consistent with first-order closure techniques while others are consistent with second-order closure techniques. Some profiles show a shearless region near the base of the canopy; however, none displays a secondary maximum there. Comparing several different analytical expressions for the canopy wind profile against observations suggests that one particular type of profile (an Airy function which is associated with the triangular foliage surface area density distribution) is superior to the others. Because of the numerical simplicity of the methods outlined, it is suggested that they may be profitably used in large-scale models of plant-atmosphere exchanges.

Shaping symmetric Airy beam through binary amplitude modulation for ultralong needle focus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Zhao-Xiang; Gong, Lei; Ren, Yu-Xuan, E-mail: yxren@ustc.edu.cn

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.more » 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.« less

Laser fabrication of diffractive optical elements based on detour-phase computer-generated holograms for two-dimensional Airy beams.

PubMed

Călin, Bogdan-Ştefăniţă; Preda, Liliana; Jipa, Florin; Zamfirescu, Marian

2018-02-20

We have designed, fabricated, and tested an amplitude diffractive optical element for generation of two-dimensional (2D) Airy beams. The design is based on a detour-phase computer-generated hologram. Using laser ablation of metallic films, we obtained a 2  mm×2  mm diffractive optical element with a pixel of 5  μm×5  μm and demonstrated a fast, cheap, and reliable fabrication process. This device can modulate 2D Airy beams or it can be used as a UV lithography mask to fabricate a series of phase holograms for higher energy efficiency. Tests according to the premise and an analysis of the transverse profile and propagation are presented.

Adjustable vector Airy light-sheet single optical tweezers: negative radiation forces on a subwavelength spheroid and spin torque reversal

NASA Astrophysics Data System (ADS)

Mitri, Farid G.

2018-01-01

Generalized solutions of vector Airy light-sheets, adjustable per their derivative order m, are introduced stemming from the Lorenz gauge condition and Maxwell's equations using the angular spectrum decomposition method. The Cartesian components of the incident radiated electric, magnetic and time-averaged Poynting vector fields in free space (excluding evanescent waves) are determined and computed with particular emphasis on the derivative order of the Airy light-sheet and the polarization on the magnetic vector potential forming the beam. Negative transverse time-averaged Poynting vector components can arise, while the longitudinal counterparts are always positive. Moreover, the analysis is extended to compute the optical radiation force and spin torque vector components on a lossless dielectric prolate subwavelength spheroid in the framework of the electric dipole approximation. The results show that negative forces and spin torques sign reversal arise depending on the derivative order of the beam, the polarization of the magnetic vector potential, and the orientation of the subwavelength prolate spheroid in space. The spin torque sign reversal suggests that counter-clockwise or clockwise rotations around the center of mass of the subwavelength spheroid can occur. The results find useful applications in single Airy light-sheet tweezers, particle manipulation, handling, and rotation applications to name a few examples.

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.

Evaluation of the AIRIS Standoff Hyperspectral Imaging System

DTIC Science & Technology

2011-01-01

desorption gas chromatography ( TD -GC). 13 4.4 Sensor Configuration For these measurements the AIRIS sensor was mounted on a lab bench opposite the fume...I J. ^4 5 . . ? J? s - » - ? ] g > > 1 ; j ’.’ S •; u] | 1 z | r 2 .• ^ z i ^ ^ ^’ i £ ^ | | i i 2 | Z I i i £ J: • in 1/1 c & <£• •: llJ 15 10

Creation of diffraction-limited non-Airy multifocal arrays using a spatially shifted vortex beam

NASA Astrophysics Data System (ADS)

Lin, Han; Gu, Min

2013-02-01

Diffraction-limited non-Airy multifocal arrays are created by focusing a phase-modulated vortex beam through a high numerical-aperture objective. The modulated phase at the back aperture of the objective resulting from the superposition of two concentric phase-modulated vortex beams allows for the generation of a multifocal array of cylindrically polarized non-Airy patterns. Furthermore, we shift the spatial positions of the phase vortices to manipulate the intensity distribution at each focal spot, leading to the creation of a multifocal array of split-ring patterns. Our method is experimentally validated by generating the predicted phase modulation through a spatial light modulator. Consequently, the spatially shifted circularly polarized vortex beam adopted in a dynamic laser direct writing system facilitates the fabrication of a split-ring microstructure array in a polymer material by a single exposure of a femtosecond laser beam.

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).

Theoretical Study of Large-Angle Bending Transport of Microparticles by 2D Acoustic Half-Bessel Beams.

PubMed

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.

Semiclassical propagator of the Wigner function.

PubMed

Dittrich, Thomas; Viviescas, Carlos; Sandoval, Luis

2006-02-24

Propagation of the Wigner function is studied on two levels of semiclassical propagation: one based on the Van Vleck propagator, the other on phase-space path integration. Leading quantum corrections to the classical Liouville propagator take the form of a time-dependent quantum spot. Its oscillatory structure depends on whether the underlying classical flow is elliptic or hyperbolic. It can be interpreted as the result of interference of a pair of classical trajectories, indicating how quantum coherences are to be propagated semiclassically in phase space. The phase-space path-integral approach allows for a finer resolution of the quantum spot in terms of Airy functions.

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.

Discrete Calculus as a Bridge between Scales

NASA Astrophysics Data System (ADS)

Degiuli, Eric; McElwaine, Jim

2012-02-01

Understanding how continuum descriptions of disordered media emerge from the microscopic scale is a fundamental challenge in condensed matter physics. In many systems, it is necessary to coarse-grain balance equations at the microscopic scale to obtain macroscopic equations. We report development of an exact, discrete calculus, which allows identification of discrete microscopic equations with their continuum equivalent [1]. This allows the application of powerful techniques of calculus, such as the Helmholtz decomposition, the Divergence Theorem, and Stokes' Theorem. We illustrate our results with granular materials. In particular, we show how Newton's laws for a single grain reproduce their continuum equivalent in the calculus. This allows introduction of a discrete Airy stress function, exactly as in the continuum. As an application of the formalism, we show how these results give the natural mean-field variation of discrete quantities, in agreement with numerical simulations. The discrete calculus thus acts as a bridge between discrete microscale quantities and continuous macroscale quantities. [4pt] [1] E. DeGiuli & J. McElwaine, PRE 2011. doi: 10.1103/PhysRevE.84.041310

Simulation of generation and dynamics of polarization singularities with circular Airy beams.

PubMed

Ye, Dong; Peng, Xinyu; Zhou, Muchun; Xin, Yu; Song, Minmin

2017-11-01

The generation and dynamics of polarization singularities have been underresearched for years, while the focusing property of the topological configuration has not been explored much. In this paper, we simulated the generation of low-order polarization singularities with a circular Airy beam and explored the focusing property of the synthetic light field during propagation due to the autofocusing of the component. Our work researched the focusing properties of the polarization singularity configuration, which may help to develop its application prospect.

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.

Time-spatial drift of decelerating electromagnetic pulses.

PubMed

Nerukh, Alexander G; Nerukh, Dmitry A

2013-07-15

A time dependent electromagnetic pulse generated by a current running laterally to the direction of the pulse propagation is considered in paraxial approximation. It is shown that the pulse envelope moves in the time-spatial coordinates on the surface of a parabolic cylinder for the Airy pulse and a hyperbolic cylinder for the Gaussian. These pulses propagate in time with deceleration along the dominant propagation direction and drift uniformly in the lateral direction. The Airy pulse stops at infinity while the asymptotic velocity of the Gaussian is nonzero.

Shear failure of granular materials

NASA Astrophysics Data System (ADS)

Degiuli, Eric; Balmforth, Neil; McElwaine, Jim; Schoof, Christian; Hewitt, Ian

2012-02-01

Connecting the macroscopic behavior of granular materials with the microstructure remains a great challenge. Recent work connects these scales with a discrete calculus [1]. In this work we generalize this formalism from monodisperse packings of disks to 2D assemblies of arbitrarily shaped grains. In particular, we derive Airy's expression for a symmetric, divergence-free stress tensor. Using these tools, we derive, from first-principles and in a mean-field approximation, the entropy of frictional force configurations in the Force Network Ensemble. As a macroscopic consequence of the Coulomb friction condition at contacts, we predict shear failure at a critical shear stress, in accordance with the Mohr-Coulomb failure condition well known in engineering. Results are compared with numerical simulations, and the dependence on the microscopic geometric configuration is discussed. [4pt] [1] E. DeGiuli & J. McElwaine, PRE 2011. doi: 10.1103/PhysRevE.84.041310

Controlling abruptly autofocusing vortex beams to mitigate crosstalk and vortex splitting in free-space optical communication.

PubMed

Yan, Xu; Guo, Lixin; Cheng, Mingjian; Li, Jiangting

2018-05-14

Orbital angular momentum (OAM) mode crosstalk induced by atmospheric turbulence is a challenging phenomenon commonly occurring in OAM-based free-space optical (FSO) communication. Recent advances have facilitated new practicable methods using abruptly autofocusing light beams for weakening the turbulence effect on the FSO link. In this work, we show that a circular phase-locked Airy vortex beam array (AVBA) with sufficient elements has the inherent ability to form an abruptly autofocusing light beam carrying OAM, and its focusing properties can be controlled on demand by adjusting the topological charge values and locations of these vortices embedded in the array elements. The performance of a tailored Airy vortex beam array (TAVBA) through atmospheric turbulence is numerically studied. In a comparison with the ring Airy vortex beam (RAVB), the results indicate that TAVBA can be a superior light source for effectively reducing the intermodal crosstalk and vortex splitting, thus leading to improvement in the FSO system performance.

Excitation of multipolar surface plasmon resonance in plasmonic nanoparticles by complex accelerating beams

NASA Astrophysics Data System (ADS)

Yang, Yang; Li, Jiafang; Li, Zhi-Yuan; Chen, Yue-Gang

2015-07-01

In this paper, through a vector-spherical harmonics approach, we investigate the optical spectra of plasmonic Au nanoparticles excited by two special accelerating beams: a non-paraxial Airy beam and a Bessel beam. We systematically analyze the impacts of the beam profile, phase, and helical wave front of the electromagnetic fields on the optical spectrum and the excitation of the surface plasmon resonance (SPR). We find that the high-order phase in the Airy beam would result in strong plasmonic oscillations in the optical spectra, while the cone angle and orbital angular momentum carried by the Bessel beam could be employed to engineer the plasmon modes excited in Au nanoparticles. Furthermore, the optical spectrum excited by a combined Airy-Bessel-Gauss beam is discussed. The study could help to deeply explore new ways to manipulate SPR in metal nanoparticles via the wave front engineering of optical beams for enhancing light-matter interaction and optical sensing performance.

Accelerated and Airy-Bloch oscillations

NASA Astrophysics Data System (ADS)

Longhi, Stefano

2016-09-01

A quantum particle subjected to a constant force undergoes an accelerated motion following a parabolic path, which differs from the classical motion just because of wave packet spreading (quantum diffusion). However, when a periodic potential is added (such as in a crystal) the particle undergoes Bragg scattering and an oscillatory (rather than accelerated) motion is found, corresponding to the famous Bloch oscillations (BOs). Here, we introduce an exactly-solvable quantum Hamiltonian model, corresponding to a generalized Wannier-Stark Hamiltonian Ĥ, in which a quantum particle shows an intermediate dynamical behavior, namely an oscillatory motion superimposed to an accelerated one. Such a novel dynamical behavior is referred to as accelerated BOs. Analytical expressions of the spectrum, improper eigenfunctions and propagator of the generalized Wannier-Stark Hamiltonian Ĥ are derived. Finally, it is shown that acceleration and quantum diffusion in the generalized Wannier-Stark Hamiltonian are prevented for Airy wave packets, which undergo a periodic breathing dynamics that can be referred to as Airy-Bloch oscillations.

On observation of neutron quantum states in the Earth's gravitational field

NASA Astrophysics Data System (ADS)

Vankov, Anatoli Andrei

2010-03-01

Observation of neutron gravitational quantum states En=mgzn in the peV energy range (z1 is about 10μm in the vertical direction) in the experiment conducted at Laue-Langevin Institute, Grenoble, with ultracold neutrons was recently reported in a series of publications. The purpose of the present work is to analyze the experiment. The experimental apparatus is designed to measure a transmission function T(za), namely, a horizontal flux of relatively fast neutrons (k≫kz in wavelength terms) passing through a slit of variable height za of upper absorbing wall. The quantum states in question are defined by the so-called Airy functions, which are solutions to the stationary 1D equation for a neutron “bouncing” above the perfect mirror in a linear potential field. The Airy functions describe the quantum bouncer (QB), the concept of which is subject to theoretical study of toy 1D models of gravitationally bound particles in nonrelativistic quantum mechanics (QM). This is essentially different from the 3D nonstationary QM object, “the running QB,” investigated in the experiment. The authors assume that there is a connection between T(za) and the probability density distribution P(z,za) for QB states. They devised the “phenomenological model,” in which the quantum pattern should be visible in the transmission curve. We argue, however, that the measured curve T(za) is not sensitive to QB states. Instead, it is sensitive to dynamics of neutron horizontal transport inside the absorbing slit for neutrons of energy values about 105 times greater than eigenvalues En. The latter are related to the neutron transverse mode kz and cannot be termed “energies of neutron gravitational quantum states.” We conclude that the experiment setup and real conditions are not adequate to the claimed objective, and the methodology of measured data treatment is flawed. The authors’ claim that “neutron gravitational quantum states are observed” is neither theoretically nor experimentally substantiated. Final, statistically significant results of the experiment are consistent with our physical reasoning that the experiment is not sensitive to “neutron gravitational quantum states” (in terms of Airy mode) and does not prove even their existence in rigorous quantum-mechanical terms.

A Curved, Elastostatic Boundary Element for Plane Anisotropic Structures

NASA Technical Reports Server (NTRS)

Smeltzer, Stanley S.; Klang, Eric C.

2001-01-01

The plane-stress equations of linear elasticity are used in conjunction with those of the boundary element method to develop a novel curved, quadratic boundary element applicable to structures composed of anisotropic materials in a state of plane stress or plane strain. The curved boundary element is developed to solve two-dimensional, elastostatic problems of arbitrary shape, connectivity, and material type. As a result of the anisotropy, complex variables are employed in the fundamental solution derivations for a concentrated unit-magnitude force in an infinite elastic anisotropic medium. Once known, the fundamental solutions are evaluated numerically by using the known displacement and traction boundary values in an integral formulation with Gaussian quadrature. All the integral equations of the boundary element method are evaluated using one of two methods: either regular Gaussian quadrature or a combination of regular and logarithmic Gaussian quadrature. The regular Gaussian quadrature is used to evaluate most of the integrals along the boundary, and the combined scheme is employed for integrals that are singular. Individual element contributions are assembled into the global matrices of the standard boundary element method, manipulated to form a system of linear equations, and the resulting system is solved. The interior displacements and stresses are found through a separate set of auxiliary equations that are derived using an Airy-type stress function in terms of complex variables. The capabilities and accuracy of this method are demonstrated for a laminated-composite plate with a central, elliptical cutout that is subjected to uniform tension along one of the straight edges of the plate. Comparison of the boundary element results for this problem with corresponding results from an analytical model show a difference of less than 1%.

Constraining Lithospheric Stress on Mars From Mars Global Surveyor (MGS) Topography, Gravity, and Crustal Thickness

NASA Astrophysics Data System (ADS)

Dimitrova, L. L.; Holt, W. E.; Haines, A. J.

2004-12-01

The quantification of lithospheric dynamics on Mars is of fundamental importance to the understanding of Martian geologic history and surface morphology. The global stress field associated with gravitational potential energy differences (GPE) constitutes a significant fraction of the total stress field. We have obtained 0.25 × 0.25 degree data sets of MOLA topography and crustal thickness from Zuber et al 2000. We calculate the GPE associated with the topography by vertically integrating density to a given lithospheric depth using either Airy isostasy assumptions or the crustal thickness model of Zuber et al 2000. Using a finite-element thin sheet method we solve the full 3-D force-balance equations for stress magnitudes and orientations within the lithosphere associated with the horizontal gradients in GPE. We assume ρ crust = 2900~ kg m-3, ~ρ mantle = 3500~ kg m-3, ~g = 3.7~ ms-2 and various lithospheric thicknesses. We explore both viscous and elastic rheologies. It is interesting to note that our solutions depend on the rheology only through the ratio of shear and bulk moduli for the elastic case or the shear and bulk viscosities for the viscous case. Finally, we also calculate the expected style and orientation of the associated elastic strain. To first order, all stress field solutions are consistent with a tectonically inactive region relaxing due to excess or deficit of mass. Thus topographic highs e.g., Tharsis Mons, Olympus Mons, and Alba Patera, are in deviatoric extension, while topographic lows e.g., Valles Marineras and impact basins, are in deviatoric compression. At short wavelengths, however, features are regionally supported and differences in the stress field solutions occur between the Airy isostasy and the crustal thickness models. For example, several lowlands e.g., Isidis and Argyre Planitae, are in deviatoric extension in the crustal thickness model. Increasing the lithospheric depth increases the magnitudes of stresses but does not change the deformation style. Comparisons of viscous and elastic solutions with the same ratio of the shear and bulk viscosities for the viscous case and shear and bulk moduli for the elastic case show small variations in stress magnitudes and orientations among the solutions. We compare our results with inferred fault styles and orientations e.g., Mege 2001, Montessi and Zuber 2003. The GPE variations appear to match the radial graben features on Tharsis, as well as the wrinkle ridges at lower elevations. However, they do not predict the wrinkle ridges on the flanks of Tharsis and some grabens around Alba Patera extend into the lower topography regions beyond the area where the GPE associated stresses predict extension. Calculations of Banerdt and Glombek 2000 show the importance of flexural loading on the stress field. Their flexural loading solution provides compression at higher elevations on Tharsis that may explain some of the wrinkle ridges not predicted by GPE variations. Therefore, it appears that a combined solution of GPE inferred vertically integrated deviatoric stresses and the flexurally produced stresses will provide a better fit to the fault styles and orientations observed on Mars.

Catastrophe optics of sharp-edge diffraction.

PubMed

Borghi, Riccardo

2016-07-01

A classical problem of diffraction theory, namely plane wave diffraction by sharp-edge apertures, is here reformulated from the viewpoint of the fairly new subject of catastrophe optics. On using purely geometrical arguments, properly embedded into a wave optics context, uniform analytical estimates of the diffracted wavefield at points close to fold caustics are obtained, within paraxial approximation, in terms of the Airy function and its first derivative. Diffraction from parabolic apertures is proposed to test reliability and accuracy of our theoretical predictions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suhendi, Endi; Syariati, Rifki; Noor, Fatimah A.

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.

Spatiotemporal Airy Ince-Gaussian wave packets in strongly nonlocal nonlinear media.

PubMed

Peng, Xi; Zhuang, Jingli; Peng, Yulian; Li, DongDong; Zhang, Liping; Chen, Xingyu; Zhao, Fang; Deng, Dongmei

2018-03-08

The self-accelerating Airy Ince-Gaussian (AiIG) and Airy helical Ince-Gaussian (AihIG) wave packets in strongly nonlocal nonlinear media (SNNM) are obtained by solving the strongly nonlocal nonlinear Schrödinger equation. For the first time, the propagation properties of three dimensional localized AiIG and AihIG breathers and solitons in the SNNM are demonstrated, these spatiotemporal wave packets maintain the self-accelerating and approximately non-dispersion properties in temporal dimension, periodically oscillating (breather state) or steady (soliton state) in spatial dimension. In particular, their numerical experiments of spatial intensity distribution, numerical simulations of spatiotemporal distribution, as well as the transverse energy flow and the angular momentum in SNNM are presented. Typical examples of the obtained solutions are based on the ratio between the input power and the critical power, the ellipticity and the strong nonlocality parameter. The comparisons of analytical solutions with numerical simulations and numerical experiments of the AiIG and AihIG optical solitons show that the numerical results agree well with the analytical solutions in the case of strong nonlocality.

Interplay between topological phase and self-acceleration in a vortex symmetric Airy beam.

PubMed

Fang, Zhao-Xiang; Chen, Yue; Ren, Yu-Xuan; Gong, Lei; Lu, Rong-De; Zhang, An-Qi; Zhao, Hong-Ze; Wang, Pei

2018-03-19

Photons in an optical vortex usually carry orbital angular momentum, which boosts the application of the micro-rotation of absorbing particles and quantum information encoding. Such photons propagate along a straight line in free space or follow a curved trace once guided by an optical fiber. Teleportation of an optical vortex using a beam with non-diffraction and self-healing is quite challenging. We demonstrate the manipulation of the propagation trace of an optical vortex with a symmetric Airy beam (SAB) and found that the SAB experiences self-rotation with the implementation of a topological phase structure of coaxial vortex. Slight misalignment of the vortex and the SAB enables the guiding of the vortex into one of the self-accelerating channels. Multiple off-axis vortices embedded in SAB are also demonstrated to follow the trajectory of the major lobe for the SAB beam. The Poynting vector for the beams proves the direction of the energy flow corresponding to the intensity distribution. Hence, we anticipate that the proposed vortex symmetric Airy beam (VSAB) will provide new possibilities for optical manipulation and optical communication.

Subcritical crack propagation due to chemical rock weakening: macroscale chemo-plasticity and chemo-elasticity modeling

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 uncoupled or coupled to strain. The later case requires iterations with solution of reactive transport equation. A decrease of stress intensity factor with time of reaction is well reproduced.

Tight focusing of radially polarized circular Airy vortex beams

NASA Astrophysics Data System (ADS)

Chen, Musheng; Huang, Sujuan; Shao, Wei

2017-11-01

Tight focusing properties of radially polarized circular Airy vortex beams (CAVB) are studied numerically. The light field expressions for the focused fields are derived based on vectorial Debye theory. We also study the relationship between focal profiles, such as light intensity distribution, radius of focal spot and focal length, and the parameters of CAVB. Numerical results demonstrate that we can generate a radially polarized CAVB with super-long focal length, super-strong longitudinal intensity or subwavelength focused spot at the focal plane by properly choosing the parameters of incident light and high numerical aperture (NA) lens. These results have potential applications for optical trapping, optical storage and particle acceleration.

Regeneration of Airy pulses in fiber-optic links with dispersion management of the two leading dispersion terms of opposite signs

NASA Astrophysics Data System (ADS)

Driben, R.; Meier, T.

2014-04-01

Dispersion management of periodically alternating fiber sections with opposite signs of two leading dispersion terms is applied for the regeneration of self-accelerating truncated Airy pulses. It is demonstrated that for such a dispersion management scheme, the direction of the acceleration of the pulse is reversed twice within each period. In this scheme the system features light hot spots in the center of each fiber section, where the energy of the light pulse is tightly focused in a short temporal slot. Comprehensive numerical studies demonstrate a long-lasting propagation also under the influence of a strong fiber Kerr nonlinearity.

Resonant tunneling in GaAs/Al xGa 1-xAs superlattices with aperiodic potential profiles

NASA Astrophysics Data System (ADS)

Djelti, R.; Aziz, Z.; Bentata, S.; Besbes, A.

2011-12-01

Using the exact Airy function formalism and the transfer-matrix technique, we have numerically investigated in this paper the effect of intentional correlations in spatial disorder on transmission properties of one-dimensional superlattices. Such systems consist of two different structures randomly distributed along the growth direction, with the additional constraint that barriers (wells) of one kind always appear in triply. It is shown that the intentional correlations in disorder and superlattices structural parameters are responsible to obtain resonant tunneling in aperiodic structure.

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.

Impurity States and diamagnetic susceptibility of a donor in a triangular quantum well

NASA Astrophysics Data System (ADS)

Kalpana, P.; Reuben, A. Merwyn Jasper D.; Nithiananthi, P.; Jayakumar, K.

2017-05-01

We have calculated the binding energy and the diamagnetic susceptibility(χdia) of the ground (1s) and few low lying excited states (2s and 2p±) in a GaAs/AlxGa1-xAs Triangular Quantum Well (TQW) for the Al composition of x = 0.3. Since the estimation of gives the carrier localization in nanostructured systems and also the calculation of (χdia) involves the , the same has also been estimated as a function of well width. The Schrodinger equation has been solved using variational technique involving Airy functions in the effective mass approximation. The results are presented and discussed.

Laguerre-Gaussian, Hermite-Gaussian, Bessel-Gaussian, and Finite-Energy Airy Beams Carrying Orbital Angular Momentum in Strongly Nonlocal Nonlinear Media

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.

Test drilling and aquifer test in the Marburg schist near Mount Airy, Frederick County, Maryland

USGS Publications Warehouse

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 step-drawdown and interference test on the public-supply wells on May 30, 1955, and aquifer test in which public-supply well 1 was pumped constantly for 48 hours and the effect of this pumpage was measured in all the wells and test holes on May 23-25.

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 higher latitudes. The glaciated North American and European cratons show a trend of modest thinning (~3km), and glaciated western Asia minor thinning (~1.5 km). These values are at the level of model uncertainties, but we note that cratons without ice sheets during the last glacial period show substantially different patterns.

Automatic Fourier transform and self-Fourier beams due to parabolic potential

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yiqi, E-mail: zhangyiqi@mail.xjtu.edu.cn; Liu, Xing; Belić, Milivoj R., E-mail: milivoj.belic@qatar.tamu.edu

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 Fouriermore » transforms are the beams themselves.« less

Spectral properties of the massless relativistic quartic oscillator

NASA Astrophysics Data System (ADS)

Durugo, Samuel O.; Lőrinczi, József

2018-03-01

An explicit solution of the spectral problem of the non-local Schrödinger operator obtained as the sum of the square root of the Laplacian and a quartic potential in one dimension is presented. The eigenvalues are obtained as zeroes of special functions related to the fourth order Airy function, and closed formulae for the Fourier transform of the eigenfunctions are derived. These representations allow to derive further spectral properties such as estimates of spectral gaps, heat trace and the asymptotic distribution of eigenvalues, as well as a detailed analysis of the eigenfunctions. A subtle spectral effect is observed which manifests in an exponentially tight approximation of the spectrum by the zeroes of the dominating term in the Fourier representation of the eigenfunctions and its derivative.

On the Mass Distribution of Animal Species

NASA Astrophysics Data System (ADS)

Redner, Sidney; Clauset, Aaron; Schwab, David

2009-03-01

We develop a simple diffusion-reaction model to account for the broad and asymmetric distribution of adult body masses for species within related taxonomic groups. The model assumes three basic evolutionary features that control body mass: (i) a fixed lower limit that is set by metabolic constraints, (ii) a species extinction risk that is a weakly increasing function of body mass, and (iii) cladogenetic diffusion, in which daughter species have a slight tendency toward larger mass. The steady-state solution for the distribution of species masses in this model can be expressed in terms of the Airy function. This solution gives mass distributions that are in good agreement with data on 4002 terrestrial mammal species from the late Quaternary and 8617 extant bird species.

Phase object imaging inside the airy disc

NASA Astrophysics Data System (ADS)

Tychinsky, Vladimir P.

1991-03-01

The possibility of phase objects superresoluton imaging is theoretically justifieth The measurements with CPM " AIRYSCAN" showed the reality of O structures observations when the Airy disc di ameter i s 0 86 j. . m SUMMARY It has been known that the amount of information contained in the image of any object is mostly determined by the number of points measured i ndependentl y or by spati al resol uti on of the system. From the classic theory of the optical systems it follows that for noncoherent sources the -spatial resolution is limited by the aperture dd 6LX/N. A. ( Rayleigh criterion where X is wave length NA numerical aperture. ) The use of this criterion is equivalent tO the statement that any object inside the Airy disc of radius d that is the difraction image of a point is practical ly unresolved. However at the coherent illumination the intensity distribution in the image plane depends also upon the phase iq (r) of the wave scattered by the object and this is the basis of the Zernike method of phasecontrast microscopy differential interference contrast (DIC) and computer phase microscopy ( CPM ). In theoretical foundation of these methods there was no doubt in the correctness of Rayleigh criterion since the phase information is derived out of intensity distribution and as we know there were no experiments that disproved this

AiryÕs Greenwich Staff

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.

Transmittance and Tunneling Current through a Trapezoidal Barrier under Spin Polarization Consideration

NASA Astrophysics Data System (ADS)

Noor, F. A.; Nabila, E.; Mardianti, H.; Ariani, T. I.; Khairurrijal

2018-04-01

The transmittance and tunneling current in heterostructures under spin polarization consideration were studied by employing a zinc-blended structure for the heterostructures. An electron tunnels through a potential barrier by applying a bias voltage to the barrier, which is called the trapezoidal potential barrier. In order to study the transmittance, an Airy wave function approach was employed to find the transmittance. The obtained transmittance was then utilized to compute the tunneling current by using a Gauss quadrature method. It was shown that the transmittances were asymmetric with the incident angle of the electron. It was also shown that the tunneling currents increased as the bias voltage increased.

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.

Reversible wavefront shaping between Gaussian and Airy beams by mimicking gravitational field

NASA Astrophysics Data System (ADS)

Wang, Xiangyang; Liu, Hui; Sheng, Chong; Zhu, Shining

2018-02-01

In this paper, we experimentally demonstrate reversible wavefront shaping through mimicking gravitational field. A gradient-index micro-structured optical waveguide with special refractive index profile was constructed whose effective index satisfying a gravitational field profile. Inside the waveguide, an incident broad Gaussian beam is firstly transformed into an accelerating beam, and the generated accelerating beam is gradually changed back to a Gaussian beam afterwards. To validate our experiment, we performed full-wave continuum simulations that agree with the experimental results. Furthermore, a theoretical model was established to describe the evolution of the laser beam based on Landau’s method, showing that the accelerating beam behaves like the Airy beam in the small range in which the linear potential approaches zero. To our knowledge, such a reversible wavefront shaping technique has not been reported before.

Energy harvesting from sea waves with consideration of airy and JONSWAP theory and optimization of energy harvester parameters

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.

Subsystem functional and the missing ingredient of confinement physics in density functionals.

DOE Office of Scientific and Technical Information (OSTI.GOV)

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,more » 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.« less

Broadband acoustic focusing by Airy-like beams based on acoustic metasurfaces

NASA Astrophysics Data System (ADS)

Chen, Di-Chao; Zhu, Xing-Feng; Wei, Qi; Wu, Da-Jian; Liu, Xiao-Jun

2018-01-01

An acoustic metasurface (AM) composed of space-coiling subunits is proposed to generate acoustic Airy-like beams (ALBs) by manipulating the transmitted acoustic phase. The self-accelerating, self-healing, and non-diffracting features of ALBs are demonstrated using finite element simulations. We further employ two symmetrical AMs to realize two symmetrical ALBs, resulting in highly efficient acoustic focusing. At the working frequency, the focal intensity can reach roughly 20 times that of the incident wave. It is found that the highly efficient acoustic focusing can circumvent obstacles in the propagating path and can be maintained in a broad frequency bandwidth. In addition, simply changing the separation between the two AMs can modulate the focal length of the proposed AM lens. ALBs generated by AMs and the corresponding AM lens may benefit applications in medical ultrasound imaging, biomedical therapy, and particle trapping and manipulation.

Semiclassical propagation of Wigner functions.

PubMed

Dittrich, T; Gómez, E A; Pachón, L A

2010-06-07

We present a comprehensive study of semiclassical phase-space propagation in the Wigner representation, emphasizing numerical applications, in particular as an initial-value representation. Two semiclassical approximation schemes are discussed. The propagator of the Wigner function based on van Vleck's approximation replaces the Liouville propagator by a quantum spot with an oscillatory pattern reflecting the interference between pairs of classical trajectories. Employing phase-space path integration instead, caustics in the quantum spot are resolved in terms of Airy functions. We apply both to two benchmark models of nonlinear molecular potentials, the Morse oscillator and the quartic double well, to test them in standard tasks such as computing autocorrelation functions and propagating coherent states. The performance of semiclassical Wigner propagation is very good even in the presence of marked quantum effects, e.g., in coherent tunneling and in propagating Schrodinger cat states, and of classical chaos in four-dimensional phase space. We suggest options for an effective numerical implementation of our method and for integrating it in Monte-Carlo-Metropolis algorithms suitable for high-dimensional systems.

A Generalized Technique in Numerical Integration

NASA Astrophysics Data System (ADS)

Safouhi, Hassan

2018-02-01

Integration by parts is one of the most popular techniques in the analysis of integrals and is one of the simplest methods to generate asymptotic expansions of integral representations. The product of the technique is usually a divergent series formed from evaluating boundary terms; however, sometimes the remaining integral is also evaluated. Due to the successive differentiation and anti-differentiation required to form the series or the remaining integral, the technique is difficult to apply to problems more complicated than the simplest. In this contribution, we explore a generalized and formalized integration by parts to create equivalent representations to some challenging integrals. As a demonstrative archetype, we examine Bessel integrals, Fresnel integrals and Airy functions.

Gaussian and Airy wave packets of massive particles with orbital angular momentum

NASA Astrophysics Data System (ADS)

Karlovets, Dmitry V.

2015-01-01

While wave-packet solutions for relativistic wave equations are oftentimes thought to be approximate (paraxial), we demonstrate, by employing a null-plane- (light-cone-) variable formalism, that there is a family of such solutions that are exact. A scalar Gaussian wave packet in the transverse plane is generalized so that it acquires a well-defined z component of the orbital angular momentum (OAM), while it may not acquire a typical "doughnut" spatial profile. Such quantum states and beams, in contrast to the Bessel states, may have an azimuthal-angle-dependent probability density and finite uncertainty of the OAM, which is determined by the packet's width. We construct a well-normalized Airy wave packet, which can be interpreted as a one-particle state for a relativistic massive boson, show that its center moves along the same quasiclassical straight path, and, which is more important, spreads with time and distance exactly as a Gaussian wave packet does, in accordance with the uncertainty principle. It is explained that this fact does not contradict the well-known "nonspreading" feature of the Airy beams. While the effective OAM for such states is zero, its uncertainty (or the beam's OAM bandwidth) is found to be finite, and it depends on the packet's parameters. A link between exact solutions for the Klein-Gordon equation in the null-plane-variable formalism and the approximate ones in the usual approach is indicated; generalizations of these states for a boson in the external field of a plane electromagnetic wave are also presented.

Crustal properties of the northern Scandinavian mountains and Fennoscandian shield from analysis of teleseismic Receiver Functions

NASA Astrophysics Data System (ADS)

Mansour, Walid Ben; England, Richard W.; Fishwick, Stewart; Moorkamp, Max

2018-04-01

The presence of high mountains along passive margins is not unusual, as shown by their presence in several regions (Scandinavia, Greenland, East US, SW Africa, Brazil, West India and SE Australia). However, the origin of this topography is not well understood. The mountain range between the Scandinavian passive margin and the Fennoscandian shield is a good example. A simple Airy isostatic model would predict a compensating root beneath the mountains but existing seismic measurements of variations in crustal thickness do not provide evidence of a root of sufficient size to produce the necessary compensation. In order to better constrain the physical properties of the crust in northern Scandinavia two broadband seismic networks were deployed between 2007 and 2009 and between 2013 and 2014. A new map of crustal thickness has been produced from P-receiver function analysis of teleseismic data recorded at 31 seismic stations. The map shows an increase in crustal thickness from the Atlantic coast (38.7 +/- 1.8 km) to the Gulf of Bothnia (43.5 +/- 2.4 km). This gradient in thickness demonstrates that the Moho topography does not mirror the variation in surface topography in this region. Thus, classical Airy isostatic models cannot explain how the surface topography is supported. New maps showing variation in Poisson's ratio and Moho sharpness together with forward and inverse modelling provide new information about the contrasting properties of the Fennoscandian shield and crust reworked by the Caledonian orogeny. A sharp Moho transition (R > 1) and low value of Vs (3.5 +/- 0.2 km.s-1) are observed beneath the orogen. The shield is characterised by a gradual transition across the Moho (R < 1) and Vs of (3.8 +/- 0.1 km.s-1) which is more typical of average continental crust. These observations are explained by a Fennoscandian shield underplated with a thick layer of high velocity, high density material. It is proposed that this layer has been removed or reworked beneath the orogen.

QBO of temperature in mesopause and lower thermosphere caused by solar activity variations

NASA Astrophysics Data System (ADS)

Shefov, N. N.; Semenov, A. I.

2003-04-01

On the basis of the data of the emission (hydroxyl, sodium and atomic oxygen 557.7 nm) and radiophysical (87-107 km) measurements some regularities of quasi-biennial oscillation (QBO) of the atmospheric temperature at heights of the mesopause and lower thermosphere are investigated. It is shown, that they are closely connected with quasi-biennial variations of solar activity and form within the limits of a cycle of solar activity the fading wave train of oscillations. Such behaviour of the wave train can be adequately described by the Airy function. As a result of the analysis of characteristics of QBO of solar activity during 17-23rd cycles it is shown, that to each 11-years cycle correspond its wave train of QBO. Amplitudes and periods of this wave train decrease during a cycle, i.e. it represents Not harmonious oscillation but it is a cyclic aperiodic oscillation (CAO). Therefore usual methods of Fourier analysis used earlier did not result in the same values of the period. The wave train of the current cycle begins at the end of previous and some time together with the subsequent cycle proceeds. Thus, the time sequence of activity during solar cycle represents superposition of three wave trains. Period of CAO in the beginning of a cycle has ~ 38 months and decreases to the end of a cycle up to ~ 21 months. The first wide negative minimum of Airy function describing of the wave train of CAO corresponds to solar activity minimum in the 11-year cycle. The time scale of the wave train varies from one cycle to another. Full duration of individual wave train is ~ 22 years. Owing to a mutual interference of the consecutive wave trains in the 11-year cycles the observable variations of solar activity are not identical. Structure of CAO obviously displays magnetohydrodynamic processes inside the Sun. This work was supported by the Grant No. 2274 of ISTC.

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 the total integrated scattering (TIS), and the fraction remaining is called the Strehl ratio. The angular distribution of the scattered light is called the angle resolved scattering (ARS), and it shows a strong spike centered on a scattering angle of zero, and a broad , less intense distribution at larger angles. It is this scattered light, and its effect on the point spread function which is the focus of this study.

Analysis of a photon assisted field emission device

NASA Astrophysics Data System (ADS)

Jensen, K. L.; Lau, Y. Y.; McGregor, D. S.

2000-07-01

A field emitter array held at the threshold of emission by a dc gate potential from which current pulses are triggered by the application of a laser pulse on the backside of the semiconductor may produce electron bunches ("density modulation") at gigahertz frequencies. We develop an analytical model of such optically controlled emission from a silicon tip using a modified Wentzel-Kramers-Brillouin and Airy function approach to solving Schrödinger's equation. Band bending and an approximation to the exchange-correlation effects on the image charge potential are included for an array of hyperbolic emitters with a distribution in tip radii and work function. For a simple relationship between the incident photon flux and the resultant electron density at the emission site, an estimation of the tunneling current is made. An example of the operation and design of such a photon-assisted field emission device is given.

Art form as an object of cognitive modeling (towards development of Vygotsky`s semiotic model)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dmitriev, V.; Perlovsky, L.I.

1996-12-31

We suggest a further development of Vygotsky`s esthetic-semiotic model. First, we discuss Vygotsky`s model originally developed for the analysis of Ivan Bunin`s story {open_quotes}Light Breath{close_quotes}. Vygotsky analyzes formal methods used by Bunin to achieve a specific esthetic effect of {open_quote}lightness{close_quotes} while describing {open_quotes}dirty{close_quotes} events of everyday life. According to Vygotsky, this effect is achieved by ordering of events in a non-linear fashion. Vygotsky creams an airy pattern of smooth lines connecting events of story that he first orders linearly in time. And, he insists that this airy pattern creates an impression of airy lightness. In the language of semiotics, themore » esthetic effect is created by a specific structural organization of signs. Second, we present our critique of Vygotsky`s model. Although, we do not agree with Vygotsky`s sometimes moralistic judgements, and we consider the dynamics between inner personal values and received moral values to be more complicated than implied in his judgements, our critique in this paper is limited to the structure of his semiotic model. We emphasize that Vygotsky`s model does not explicitly account for a hierarchy of multiple levels of semiotic analysis. His analysis regularly slips from one level to another: (1) a lever of cognitive perception by a regular reader is confused with a level of creative genius of a writer; (2) {open_quotes}open{close_quotes} time of real world is mixed up with {open_quote}closed{close_quote} time of the story; (3) events are not organized by the hierarchy of their importance, nor in real world, nor in the inner model of the personages, nor in the story.« less

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.

Minimal analytical model for undular tidal bore profile; quantum and Hawking effect analogies

NASA Astrophysics Data System (ADS)

Berry, M. V.

2018-05-01

Waves travelling up-river, driven by high tides, often consist of a smooth front followed by a series of undulations. A simple approximate theory gives the rigidly travelling profile of such ‘undular hydraulic jumps’, up to scaling, as the integral of the Airy function; applying self-consistency fixes the scaling. The theory combines the standard hydraulic jump with ideas borrowed from quantum physics: Hamiltonian operators and zero-energy eigenfunctions. There is an analogy between undular bores and the Hawking effect in relativity: both concern waves associated with horizons. ‘Physics is not just Concerning the Nature of Things, but Concerning the Interconnectedness of all the Natures of Things’(Sir Charles Frank, retirement speech 1976).

Radial restricted solid-on-solid and etching interface-growth models

NASA Astrophysics Data System (ADS)

Alves, Sidiney G.

2018-03-01

An approach to generate radial interfaces is presented. A radial network recursively obtained is used to implement discrete model rules designed originally for the investigation in flat substrates. I used the restricted solid-on-solid and etching models as to test the proposed scheme. The results indicate the Kardar, Parisi, and Zhang conjecture is completely verified leading to a good agreement between the interface radius fluctuation distribution and the Gaussian unitary ensemble. The evolution of the radius agrees well with the generalized conjecture, and the two-point correlation function exhibits also a good agreement with the covariance of the Airy2 process. The approach can be used to investigate radial interfaces evolution for many other classes of universality.

Radial restricted solid-on-solid and etching interface-growth models.

PubMed

Alves, Sidiney G

2018-03-01

An approach to generate radial interfaces is presented. A radial network recursively obtained is used to implement discrete model rules designed originally for the investigation in flat substrates. I used the restricted solid-on-solid and etching models as to test the proposed scheme. The results indicate the Kardar, Parisi, and Zhang conjecture is completely verified leading to a good agreement between the interface radius fluctuation distribution and the Gaussian unitary ensemble. The evolution of the radius agrees well with the generalized conjecture, and the two-point correlation function exhibits also a good agreement with the covariance of the Airy_{2} process. The approach can be used to investigate radial interfaces evolution for many other classes of universality.

Propagation properties of the chirped Airy beams through the gradient-index medium

NASA Astrophysics Data System (ADS)

Feng, Liyan; Zhang, Jianbin; Pang, Zihao; Wang, Linyi; Zhong, Tianfen; Yang, Xiangbo; Deng, Dongmei

2017-11-01

Through analytical derivation and numerical analysis, the propagation properties of the chirped Airy(CAi) beams in the gradient-index medium are investigated. The intensity and the phase distributions, the propagation trajectory and the Poynting vector of the CAi beams are demonstrated to investigate the propagation properties. Owing to the special and symmetrical refractive index profile of the gradient-index medium, the CAi beams propagate periodically. The effects of the distribution factor and the chirped parameter on the propagation of the CAi beams are analyzed. As the increasing of the distribution factor, the intensity distribution of the CAi beams is more scattering. However, with the chirped parameter increasing, the focusing property of the CAi beams strengthens. The variation of the chirped parameter can change the position of the peak intensity maximum, but it cannot alter the period of the peak intensity. The variations of the initial phase and the energy of the beams in the transverse plane expedite accordingly.

Huygens' optical vector wave field synthesis via in-plane electric dipole metasurface.

PubMed

Park, Hyeonsoo; Yun, Hansik; Choi, Chulsoo; Hong, Jongwoo; Kim, Hwi; Lee, Byoungho

2018-04-16

We investigate Huygens' optical vector wave field synthesis scheme for electric dipole metasurfaces with the capability of modulating in-plane polarization and complex amplitude and discuss the practical issues involved in realizing multi-modulation metasurfaces. The proposed Huygens' vector wave field synthesis scheme identifies the vector Airy disk as a synthetic unit element and creates a designed vector optical field by integrating polarization-controlled and complex-modulated Airy disks. The metasurface structure for the proposed vector field synthesis is analyzed in terms of the signal-to-noise ratio of the synthesized field distribution. The design of practical metasurface structures with true vector modulation capability is possible through the analysis of the light field modulation characteristics of various complex modulated geometric phase metasurfaces. It is shown that the regularization of meta-atoms is a key factor that needs to be considered in field synthesis, given that it is essential for a wide range of optical field synthetic applications, including holographic displays, microscopy, and optical lithography.

Effects of a modulated vortex structure on the diffraction dynamics of ring Airy Gaussian beams.

PubMed

Huang, Xianwei; Shi, Xiaohui; Deng, Zhixiang; Bai, Yanfeng; Fu, Xiquan

2017-09-01

The evolution of the ring Airy Gaussian beams with a modulated vortex in free space is numerically investigated. Compared with the unmodulated vortex, the unique property is that the beam spots first break up, and then gather. The evolution of the beams is influenced by the parameters of the vortex modulation, and the splitting phenomenon gets enhanced with multiple rings becoming light spots if the modulation depth increases. The symmetric branch pattern of the beam spots gets changed when the number of phase folds increases, and the initial modulation phase only impacts the angle of the beam spots. Moreover, a large distribution factor correlates to a hollow Gaussian vortex shape and weakens the splitting and gathering trend. By changing the initial parameters of the vortex modulation and the distribution factor, the peak intensity is greatly affected. In addition, the energy flow and the angular momentum are elucidated with the beam evolution features being confirmed.

Rainbows, supernumerary rainbows and interference effects in the angular scattering of chemical reactions: an investigation using Heisenberg's S matrix programme.

PubMed

Shan, Xiao; Xiahou, Chengkui; Connor, J N L

2018-01-03

In earlier research, we have demonstrated that broad "hidden" rainbows can occur in the product differential cross sections (DCSs) of state-to-state chemical reactions. Here we ask the question: can pronounced and localized rainbows, rather than broad hidden ones, occur in reactive DCSs? Further motivation comes from recent measurements by H. Pan and K. Liu, J. Phys. Chem. A, 2016, 120, 6712, of a "bulge" in a reactive DCS, which they conjecture is a rainbow. Our theoretical approach uses a "weak" version of Heisenberg's scattering matrix program (wHSMP) introduced by X. Shan and J. N. L. Connor, Phys. Chem. Chem. Phys., 2011, 13, 8392. This wHSMP uses four general physical principles for chemical reactions to suggest simple parameterized forms for the S matrix; it does not employ a potential energy surface. We use a parameterization in which the modulus of the S matrix is a smooth-step function of the total angular momentum quantum number, J, and (importantly) its phase is a cubic polynomial in J. We demonstrate for a Legendre partial wave series (PWS) the existence of pronounced rainbows, supernumerary rainbows, and other interference effects, in reactive DCSs. We find that reactive rainbows can be more complicated in their structure than the familiar rainbows of elastic scattering. We also analyse the angular scattering using Nearside-Farside (NF) PWS theory and NF PWS Local Angular Momentum (LAM) theory, including resummations of the PWS. In addition, we apply full and NF asymptotic (semiclassical) rainbow theories to the PWS - in particular, the uniform Airy and transitional Airy approximations for the farside scattering. This lets us prove that structure in the DCSs are indeed rainbows, supernumerary rainbows as well as other interference effects.

Starch-based aerogels: airy materials from amylose-sodium palmitate inclusion complexes

USDA-ARS?s Scientific Manuscript database

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...

At Home with History

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…

AIRIS Wide Area Detection System

DTIC Science & Technology

2003-07-01

herbicola, the chemical stimulant SF6, as well as the interferents kaolin clay dust, Dugway road dust, and diesel soot. In this paper we will report on...the SF6 column density of approximately 200 ppmv-m. In future work we hope to correlate this measurement with a Gaussian plume dispersion model of

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)

From Airy to Abbe: quantifying the effects of wide-angle focusing for scalar spherical waves

NASA Astrophysics Data System (ADS)

Calm, Yitzi M.; Merlo, Juan M.; Burns, Michael J.; Naughton, Michael J.

2017-10-01

Recent advances in optical microscopy have enabled imaging with spatial resolution beyond the diffraction limit. This limit is sometimes taken as one of several different criteria according to different conventions, including Rayleigh’s 0.61λ /NA, Abbe’s 0.5λ /NA, and Sparrow’s 0.47λ /NA. In this paper, we perform a parametric study, numerically integrating the scalar Kirchhoff diffraction integrals, and we propose new functional forms for the resolution limits derived from scalar focusing. The new expressions remain accurate under wide angle focusing, up to 90^\\circ . Our results could materially impact the design of high intensity focused ultrasound systems, and can be used as a qualitative guideline for the design of a particular type of planar optical element: the flat lens metasurface.

75 FR 36678 - Prestressed Concrete Steel Wire Strand From China; Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-28

... Concrete Steel Wire Strand From China; Determinations On the basis of the record \\1\\ developed in the... prestressed concrete steel wire strand (PC strand), provided for in subheading 7312.10.30 of the Harmonized... Spring Wire Corp. (Bedford Heights, OH); Insteel Wire Products Co. (Mt. Airy, NC); and Sumiden Wire...

Propagation properties of chirped Airy vortex beams with x-polarization through uniaxial crystals

NASA Astrophysics Data System (ADS)

Wang, Linyi; Zhang, Jianbin; Feng, Liyan; Pang, Zihao; Zhong, Tianfen; Deng, Dongmei

2018-05-01

Not Available Project supported by the National Natural Science Foundation of China (Grant Nos. 11775083 and 11374108), the National Training Program of Innovation and Entrepreneurship for Undergraduates, China, and Special Funds for the Cultivation of Guangdong College Students’ Scientific and Technological Innovation, China (Grant No. pdjh2017b0137).

A New Way to Demonstrate the Rainbow

ERIC Educational Resources Information Center

Ivanov, Dragia Trifonov; Nikolov, Stefan Nikolaev

2016-01-01

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…

Near-field plasmonic beam engineering with complex amplitude modulation based on metasurface

NASA Astrophysics Data System (ADS)

Song, Xu; Huang, Lingling; Sun, Lin; Zhang, Xiaomeng; Zhao, Ruizhe; Li, Xiaowei; Wang, Jia; Bai, Benfeng; Wang, Yongtian

2018-02-01

Metasurfaces have recently intrigued extensive interest due to their ability to locally manipulate electromagnetic waves, which provide great feasibility for tailoring both propagation waves and surface plasmon polaritons (SPPs). Manipulation of SPPs with arbitrary complex fields is an important issue in integrated nanophotonics due to their capability of guiding waves with subwavelength footprints. Here, an approach with metasurfaces composed of nanoaperture arrays is proposed and experimentally demonstrated which can effectively manipulate the complex amplitude of SPPs in the near-field regime. Tailoring the azimuthal angles of individual nanoapertures and simultaneously tuning their geometric parameters, the phase and amplitude are controlled based on the Pancharatnam-Berry phases and their individual transmission coefficients. For the verification of the concept, Airy plasmons and axisymmetric Airy-SPPs are generated. The results of numerical simulations and near-field imaging are consistent with each other. Besides the rigorous simulations, we applied a 2D dipole analysis for additional analysis. This strategy of complex amplitude manipulation with metasurfaces can be used for potential applications in plasmonic beam shaping, integrated optoelectronic systems, and surface wave holography.

Acoustics of finite asymmetric exotic beams: Examples of Airy and fractional Bessel beams

NASA Astrophysics Data System (ADS)

Mitri, F. G.

2017-12-01

The purpose of this investigation is to examine the properties of finite asymmetric exotic scalar (acoustic) beams with unusual properties using the angular spectrum decomposition in plane waves. Such beams possess intrinsic uncommon characteristics that make them attractive from the standpoint of particle manipulation, handling and rotation, and possibly other applications in particle clearing and separation. Assuming a specific apodization function at the acoustic source, the angular spectrum function is calculated and used to synthesize the radiated pressure field (i.e., excluding evanescent waves that decay away from the source) in the forward direction of wave motion (i.e., away from the source). Moreover, a generalized hybrid method combining the angular spectrum approach with the multipole expansion formalism in spherical coordinates is developed, which is applicable to any finite beam of arbitrary wavefront. The improved approach allows adequate computation of the resonance scattering, radiation force, and spin torque components on an object of arbitrary shape, located on or off the axis of the incident beam in space. Considering the illustrative example of a viscous fluid sphere submerged in a non-viscous liquid and illuminated by finite asymmetric beams such as the Airy and the Bessel vortex beam with fractional order, numerical computations for the scattering, radiation force, and torque components are performed with an emphasis on the distance from the source, the arbitrary location of the particle ,and the asymmetric nature of the incident field. Moreover, beamforming calculations are presented with supplementary animations for the pressure field distribution in space, with an emphasis on the intrinsic properties of the selected beams. The numerical predictions illustrate the scattering, radiation force, and spin torque properties depending on the beam parameters and the distance separating the sphere from the source. This study provides a generalized hybrid method to analyze quantitatively the scattering, radiation force, and spin torque by any finite asymmetric (or symmetric) acoustic beam with potential applications in various fields of applied physics (such as beam-forming, imaging, and mechanical effects of asymmetric sound beams).

Analytical time-domain Green’s functions for power-law media

PubMed Central

Kelly, James F.; McGough, Robert J.; Meerschaert, Mark M.

2008-01-01

Frequency-dependent loss and dispersion are typically modeled with a power-law attenuation coefficient, where the power-law exponent ranges from 0 to 2. To facilitate analytical solution, a fractional partial differential equation is derived that exactly describes power-law attenuation and the Szabo wave equation [“Time domain wave-equations for lossy media obeying a frequency power-law,” J. Acoust. Soc. Am. 96, 491–500 (1994)] is an approximation to this equation. This paper derives analytical time-domain Green’s functions in power-law media for exponents in this range. To construct solutions, stable law probability distributions are utilized. For exponents equal to 0, 1∕3, 1∕2, 2∕3, 3∕2, and 2, the Green’s function is expressed in terms of Dirac delta, exponential, Airy, hypergeometric, and Gaussian functions. For exponents strictly less than 1, the Green’s functions are expressed as Fox functions and are causal. For exponents greater than or equal than 1, the Green’s functions are expressed as Fox and Wright functions and are noncausal. However, numerical computations demonstrate that for observation points only one wavelength from the radiating source, the Green’s function is effectively causal for power-law exponents greater than or equal to 1. The analytical time-domain Green’s function is numerically verified against the material impulse response function, and the results demonstrate excellent agreement. PMID:19045774

Fisher, Sir Ronald Aylmer (1890-1962)

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

Statistician, born in London, England. After studying astronomy using AIRY's manual on the Theory of Errors he became interested in statistics, and laid the foundation of randomization in experimental design, the analysis of variance and the use of data in estimating the properties of the parent population from which it was drawn. Invented the maximum likelihood method for estimating from random ...

78 FR 25303 - Prestressed Concrete Steel Rail Tie Wire From China, Mexico, and Thailand

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-30

... Concrete Steel Rail Tie Wire From China, Mexico, and Thailand Institution of antidumping duty..., by reason of imports from prestressed concrete steel rail tie wire from China, Mexico, and Thailand... filed on April 23, 2013, by Davis Wire Corp. of Kent, WA and Insteel Wire Product Co. of Mount Airy, NC...

Venus - Ishtar gravity anomaly

NASA Technical Reports Server (NTRS)

Sjogren, W. L.; Bills, B. G.; Mottinger, N. A.

1984-01-01

The gravity anomaly associated with Ishtar Terra on Venus is characterized, comparing line-of-sight acceleration profiles derived by differentiating Pioneer Venus Orbiter Doppler residual profiles with an Airy-compensated topographic model. The results are presented in graphs and maps, confirming the preliminary findings of Phillips et al. (1979). The isostatic compensation depth is found to be 150 + or - 30 km.

Leidos Reclaims Defelice Cup at Annual Golf Tournament | Poster

Cancer.gov

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.

Maxwell, James Clerk (1831-79)

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

Born in Edinburgh, Scotland, worked at Cambridge on electric and magnetic fields and their interrelation. Entered a prize-winning essay for a competition on the subject `The Motion of Saturn's Rings' and showed that the rings could be stable only if they consisted of numerous small solid particles in Keplerian motion with the inner edge moving faster than the outer edge. GEORGE AIRY, a compet...

(3+1)-dimensional localized self-accelerating Airy elegant Ince-Gaussian wave packets and their radiation forces in free space

NASA Astrophysics Data System (ADS)

Li, Dongdong; Peng, Xi; Peng, Yulian; Zhang, Liping; Chen, Xingyu; Zhuang, Jingli; Zhao, Fang; Yang, Xiangbo; Deng, Dongmei

2017-12-01

Not Available Project supported by the National Natural Science Foundation of China (Grant Nos. 11374108, 11374107, and 11775083), the Funds from CAS Key Laboratory of Geospace Environment, University of Science and Technology of China, and the Innovation Project of Graduate School of South China Normal University (Grant No. 2016lkxm64).

Isostatic Compensation of the Lunar Highlands

NASA Astrophysics Data System (ADS)

Sori, Michael M.; James, Peter B.; Johnson, Brandon C.; Soderblom, Jason M.; Solomon, Sean C.; Wieczorek, Mark A.; Zuber, Maria T.

2018-02-01

The lunar highlands are isostatically compensated at large horizontal scales, but the specific compensation mechanism has been difficult to identify. With topographic data from the Lunar Orbiter Laser Altimeter and gravity data from the Gravity Recovery and Interior Laboratory, we investigate support of highland topography. Poor correlation between crustal density and elevation shows that Pratt compensation is not important in the highlands. Using spectrally weighted admittance, we compared observed values of geoid-to-topography ratio (GTR) with those predicted by isostatic models. Observed GTRs are 25.8+7.5-5.7 m/km for the nearside highlands and 39.3+5.7-6.2 m/km for the farside highlands. These values are not consistent with flexural compensation of long-wavelength topography or Airy isostasy defined under an assumption of equal mass in crustal columns. Instead, the observed GTR values are consistent with models of Airy compensation in which isostasy is defined under a requirement of equal pressures at equipotential surfaces at depth. The gravity and topography data thus reveal that long-wavelength topography on the Moon is most likely compensated by variations in crustal thickness, implying that highland topography formed early in lunar history before the development of a thick elastic lithosphere.

Efficacy and safety of Pueraria candollei var. mirifica (Airy Shaw & Suvat.) Niyomdham for menopausal women: A systematic review of clinical trials and the way forward.

PubMed

Kongkaew, Chuenjid; Scholfield, Norman C; Dhippayom, Teerapon; Dilokthornsakul, Piyameth; Saokaew, Surasak; Chaiyakunapruk, Nathorn

2018-04-24

Pueraria candollei var. mirifica (Airy Shaw & Suvat.) Niyomdham (commonly termed P. mirifica, PM) growing in upland Thailand has a long history as a postmenopausal rejuvenant therapy for indigenants. Its amelioration of menopause symptoms in clinical trials was assessed. International and Thai databases were searched from inception to February 2017. Clinical trials investigating effects of PM menopausal or postmenopausal women were included. Outcomes were self-reported menopausal symptoms, serum reproductive hormones, urino-genital tract function, and bone surrogates. Methodological quality was assessed by Cochrane risk-of-bias v2.0, and a 22-parameter quality score based on the CONSORT checklist for herbal medicines. Eight studies (9 articles) used data from 309 menopausal patients. Five-studies demonstrated that PM was associated with climacteric scores reduced by ~50% compared to baseline. Other PM studies using limited numbers of placebo participants suggested improved vaginal and other urogenital tract symptoms. Bone alkaline phosphatase halved (suggesting lowered bone turnover). Variable serum reproductive hormone levels suggested menopausal status differed between studies. PM active ingredients and sources were not defined. Adverse event rates (mastodynia, vaginal spotting, dizziness) were similar in all groups (PM, conjugated equine estrogen, and placebos) but serum C-reactive protein doubled. These studies had design and reporting deficiencies, high risks of biases, and low quality scores. The efficacy of PM on menopausal symptoms remains inconclusive because of methodological short-comings especially placebo effects inherent in self-assessment/recall questionnaires and no PM standardization. PM efficacy and safety need a fundamental re-appraisal by: (i) cohort (retro- and prospective) studies on current users to define its traditional use for rejuvenation; (ii) tightly coupling long-term efficacy to safety of well-defined PM and multiple end-points; (iii) using study design related to current understanding of menopause progression and estrogen pharmacology (iv) robust pharmacovigilance. Copyright © 2018 Elsevier B.V. All rights reserved.

Structure of Kinetic Alfvén Waves of Small Transverse Scale

NASA Astrophysics Data System (ADS)

Morales, G. J.; Maggs, J. E.

1996-11-01

This analytical study illustrates the spatial pattern of kinetic Alfvén waves excited by a current-modulating disk whose dimension R transverse to the confining magnetic field is comparable to cs / Ω_i. The radial structure of the wave azimuthal magnetic field consists of 3 regions: a Bessel function behavior for r < R, a near null at r ~ R, and a driven Airy pattern for r >> R. The pattern spreads at an angle given by tan θ = (ω/Ω_i)(c_s/V_A)/(2 \\cdot 6), where ω is the modulation frequency and VA the Alfvén speed. This arises because there is a maximum value at finite k_⊥ for the ratio of the perpendicular to parallel group velocity, which differs from the cone spreading(G.J. Morales, R.S. Loritsch, and J.E. Maggs, Phys. Plasmas) 1, 3765 (1994) associated with inertial Alfvén waves. Sponsored by ONR

Composition measurements of binary mixture droplets by rainbow refractometry.

PubMed

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.

[Variations of respiratory parameters in healthy men].

PubMed

Shishkin, G S; Ustiuzhaninova, N V

2006-01-01

The subjects of the study were 656 healthy men living in the south of West Siberia, in whom the basic parameters of gas exchange, lung ventilation, static lung volumes, and bronchial permeability were measured. The significance and incidence of non-pathological changes in the system of external respiration were defined on the basis of statistical and cluster analysis of these parameters. The study shows that individuals with functional changes can be divided into four groups with different characteristics: 1. Steady mobilization of the reserve tissue of the respiratory parts of the lungs as a physiological defense reaction to unfavorable ecological factors; 2. An increased airiness of the respiratory tissue as a sign of a compensatory reaction directed towards maintaining gas homeostasis in frequent and prominent overload of the system of external respiration; 3. Steady hyperventilation as a direct functional response of the organism to the slowing down of oxygen mass transfer in the respiratory parts of the lungs; 4. Restriction of external respiration due to respiratory diseases in the past. Despite differences in the origin, all the studied functional changes have one common feature, i.e. their association with a decrease in external respiratory reserve; all of them should be considered pulmonological risk manifestations.

Improved method to fully compensate the spatial phase nonuniformity of LCoS devices with a Fizeau interferometer.

PubMed

Lu, Qiang; Sheng, Lei; Zeng, Fei; Gao, Shijie; Qiao, Yanfeng

2016-10-01

Liquid crystal on silicon (LCoS) devices usually show spatial phase nonuniformity (SPNU) in applications of phase modulation, which comprises the phase retardance nonuniformity (PRNU) as a function of the applied voltage and inherent wavefront distortion (WFD) introduced by the device itself. We propose a multipoint calibration method utilizing a Fizeau interferometer to compensate SPNU of the device. Calibration of PRNU is realized by defining a grid of 3×6 cells onto the aperture and then calculating phase retardance of each cell versus a gradient gray pattern. With designing an adjusted gray pattern calculated by the calibrated multipoint phase retardance function, compensation of inherent WFD is achieved. The peak-to-valley (PV) value of the residual WFD compensated by the multipoint calibration method is significantly reduced from 2.5λ to 0.140λ, while the PV value of the residual WFD after global calibration is reduced to 0.364λ. Experimental results of the generated finite-energy 2D Airy beams in Fourier space demonstrate the effectiveness of this multipoint calibration method.

Aeroacoustic catastrophes: upstream cusp beaming in Lilley's equation.

PubMed

Stone, J T; Self, R H; Howls, C J

2017-05-01

The downstream propagation of high-frequency acoustic waves from a point source in a subsonic jet obeying Lilley's equation is well known to be organized around the so-called 'cone of silence', a fold catastrophe across which the amplitude may be modelled uniformly using Airy functions. Here we show that acoustic waves not only unexpectedly propagate upstream, but also are organized at constant distance from the point source around a cusp catastrophe with amplitude modelled locally by the Pearcey function. Furthermore, the cone of silence is revealed to be a cross-section of a swallowtail catastrophe. One consequence of these discoveries is that the peak acoustic field upstream is not only structurally stable but also at a similar level to the known downstream field. The fine structure of the upstream cusp is blurred out by distributions of symmetric acoustic sources, but peak upstream acoustic beaming persists when asymmetries are introduced, from either arrays of discrete point sources or perturbed continuum ring source distributions. These results may pose interesting questions for future novel jet-aircraft engine designs where asymmetric source distributions arise.

Quantum reflection in the linearly downward potential

NASA Astrophysics Data System (ADS)

Chamnan, N.; Krunavakarn, B.

2017-09-01

In this work, the motion of a particle in one dimension under the influence of the linearly downward potential well is studied within the context of the non-relativistic quantum mechanics. The attention is paid on the paradoxical phenomenon of the reflection of a particle that is in contrast between classical and quantum physics. Classically, the reflection effect occurs only at a potential barrier. To demonstrate such counter-intuitive phenomenon, the Schrödinger equation is solved to obtain the reflection coefficient in the scattering state by considering an incident particle that is represented by a monochromatic plane wave having an energy E > 0, propagates freely from left to right, pass through the potential well. The continuity conditions at boundaries give the desired result that is expressed in terms of the Airy functions which depends on the incident energy E, the strength jV 0 j and the range L of the well. The value of the reflection coefficient R lies in the interval 0 < R < 1, and its behavior is the decreasing function with respect to the range L.

Coherent Detector for Near-Angle Scattering and Polarization Characterization of Telescope Mirror Coatings

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.

The Effects of Sediment Properties on Low Frequency Acoustic Propagation

DTIC Science & Technology

2015-09-30

1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. The Effects of Sediment Properties on Low Frequency...investigations have indicated that water-borne acoustic arrival properties such as their Airy Phase are sensitive to sediment shear properties. Our major...goals of our research are to: • Improve inversion schemes for the estimation of sediment geoacoustic properties using low frequency broadband

Interferometric visualization and demodulation method for measuring quasi-static strain in fiber Bragg grating sensors by a simple rotating etalon filter

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.

Acoustic radiation force induced by two Airy-Gaussian beams on a cylindrical particle

NASA Astrophysics Data System (ADS)

Gao, Sha; Mao, Yiwei; Liu, Jiehui; Liu, Xiaozhou

2018-01-01

Not Available Project supported by the National Key R & D Program, China (Grant No. 2016YFF0203000), the National Natural Science Foundation of China (Grant Nos. 11774167 and 61571222), Fundamental Research Funds for the Central Universities, China (Grant No. 020414380001), State Key Laboratory of Acoustics, Chinese Academy of Sciences (Grant No. SKLA201609), and AQSIQ Technology R & D Program, China (Grant No. 2017QK125).

The Effects of Sediment Properties on Low Frequency Acoustic Propagation

DTIC Science & Technology

2013-09-30

Ballroom Music Spillover into a Beluga Whale Aquarium Exhibit,” Advances in Acoustics and Vibration, 2012 (doi:10.1155/2012/402130) [ refereed]. 12... Acoustic Propagation James H. Miller and Gopu R. Potty University of Rhode Island Department of Ocean Engineering Narragansett, RI 02881 Phone (401...investigations have indicated that water-borne acoustic arrival properties such as their Airy Phase are sensitive to sediment shear properties. Our major

Maunder, E W (1851-1928) and Maunder, Mrs A S D

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

Solar astronomers. Maunder became assistant for spectroscopic and solar observations at the Royal Observatory, Greenwich under GEORGE AIRY, aided by his wife. In 1890, while studying the numbers of sunspots over a 300 year time-span he noticed the scarcity of spots in the period 1645-1715. This so-called Maunder minimum was confirmed by Jack Eddy (1976) to be a real effect rather than simply a...

Long waves in parallel flow in Hele-Shaw cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeybek, M.; Yortsos, Y.C.

1991-09-09

The evolution of fluid interfaces in parallel flow in Hele-Shaw cells is studied theoretically and experimentally in the limit of large capillary number. It is shown that such interfaces support wave motion, the amplitude of which for long waves is governed by a set of Korteweg--de Vries and Airy equations. Experiments conducted in a long Hele-Shaw cell validate the theory in the symmetric case.

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.

NCI Holds on to Defelice Cup | Poster

Cancer.gov

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

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.

Prerequisite for Strategic Planning: A Concept of the National Interest.

DTIC Science & Technology

1984-12-01

nature of the American national character 11 conventional wisdom of political science that holds that, although there is no existential public interest... existential harmony of interests within the community which * possesses sufficient objectivity to yield concrete public policies which ought to be...ideas, which are mere airy nothings without mass or energy, the mere shadows of the existential world of substance and of force, of habits and desires, of

In vivo dark-field imaging of the retinal pigment epithelium cell mosaic

PubMed Central

Scoles, Drew; Sulai, Yusufu N.; Dubra, Alfredo

2013-01-01

Non-invasive reflectance imaging of the human RPE cell mosaic is demonstrated using a modified confocal adaptive optics scanning light ophthalmoscope (AOSLO). The confocal circular aperture in front of the imaging detector was replaced with a combination of a circular aperture 4 to 16 Airy disks in diameter and an opaque filament, 1 or 3 Airy disks thick. This arrangement reveals the RPE cell mosaic by dramatically attenuating the light backscattered by the photoreceptors. The RPE cell mosaic was visualized in all 7 recruited subjects at multiple retinal locations with varying degrees of contrast and cross-talk from the photoreceptors. Various experimental settings were explored for improving the visualization of the RPE cell boundaries including: pinhole diameter, filament thickness, illumination and imaging pupil apodization, unmatched imaging and illumination focus, wavelength and polarization. None of these offered an obvious path for enhancing image contrast. The demonstrated implementation of dark-field AOSLO imaging using 790 nm light requires low light exposures relative to light safety standards and it is more comfortable for the subject than the traditional autofluorescence RPE imaging with visible light. Both these factors make RPE dark-field imaging appealing for studying mechanisms of eye disease, as well as a clinical tool for screening and monitoring disease progression. PMID:24049692

Paraxial propagation of the first-order chirped Airy vortex beams in a chiral medium.

PubMed

Xie, Jintao; Zhang, Jianbin; Ye, Junran; Liu, Haowei; Liang, Zhuoying; Long, Shangjie; Zhou, Kangzhu; Deng, Dongmei

2018-03-05

We introduce the propagation of the first-order chirped Airy vortex beams (FCAiV) in a chiral medium analytically. Results show that the FCAiV beams split into the left circularly polarized vortex (LCPV) beams and the right circularly polarized vortex (RCPV) beams, which have totally different propagation trajectories in the chiral medium. In this paper, we investigate the effects of the first-order chirped parameter β, the chiral parameter γ and the optical vortex on the propagation process of the FCAiV beams. It is shown that the propagation trajectory of the FCAiV beams declines with the chirped parameter increasing. Besides, the increase of the chiral parameter acting on the LCPV beams makes the relative position between the main lobe and the optical vortex further while the effect on the RCPV beams is the opposite. Furthermore, the relative position between the main lobe and the optical vortex contributes to the position of the intensity focusing. Meanwhile, with the chiral parameter increasing, the maximum gradient and scattering forces of the LCPV beams decrease but those of the RCPV beams will increase during the propagation. It is significant that we can control the propagation trajectory, the intensity focusing position and the radiation forces of the FCAiV beams by varying the chirped parameter and the chiral parameter.

Optical force and torque on a dielectric Rayleigh particle by a circular Airy vortex beam

NASA Astrophysics Data System (ADS)

Chen, Musheng; Huang, Sujuan; Shao, Wei; Liu, Xianpeng

2018-03-01

Optical force and torque exerted on the Rayleigh particles by tightly focused circularly polarized circular Airy vortex beams (CAVB) in the far field are studied in this paper. The relation between parameters of circularly polarized CAVB and the trapping properties is numerically analyzed based on Rayleigh models and the Debye diffraction theory. The results show that both the high refractive index and low refractive index particles can be fully stably trapped in three dimensions by circularly polarized CAVB. The parameters of circularly polarized CAVB greatly affect the optical force. The longitudinal and transverse gradient force increase with the increase of decay factor and scaling factor, and decrease with the increase of the radius of the first primary ring and topological charges. The positions of the longitudinal stable equilibrium move toward the high numerical aperture lens when the scaling factor and the radius of the primary ring increase. The trapping range is broadened with the decrease of scaling factor. The optical orbital torque (OOT) of circularly polarized CAVB has circular symmetry and remains positive or negative. With the increase of topological charges, the peak value of OOT first increases and then decreases after reaches a maximum. These results are useful for optical trapping, optical levitation and particle acceleration.

Isostatic compensation of Ishtar Terra, Venus

NASA Astrophysics Data System (ADS)

Kucinskas, Algis B.; Turcotte, Donald L.; Arkani-Hamed, Jafar

We have used spherical harmonic representations of the Venus topography and geopotential, obtained from Magellan data, to evaluate isostatic support in several areas within the Ishtar Terra highlands, including the Lakshmi plateau, its surrounding mountain belts, namely Akna and Freyja, and Maxwell Montes, and the Fortuna Tessera province. We find that topography in Ishtar is largely isostatically compensated (>80%). Regional geoidtopography variations in the subregions can be explained by a combination of Airy (crustal thickening) and thermal (lithospheric thinning) mechanisms, provided Venus has a thick reference thermal lithosphere (~300-400 km). With the exception of eastern Fortuna, low elevation areas (h<3-4 km above the mean planetary radius, MPR) with large geoidtopography ratios (GTR) seem to be associated, to various degrees, with thermal isostasy, whereas the higher areas (h>4 km above MPR) with small GTRs are almost certainly Airy compensated via thickened crust. Relatively large (>60 km) total Airy crustal thicknesses obtained in the western Ishtar mountain belts, together with a probable basalt-eclogite phase change, suggest a possible silicic composition for these structures, provided they are older than ~25-50 Ma. Lakshmi Planum seems essentially thermally supported, with the thermal lithosphere thinned to ~100 km. We suggest, as one possibility, that the lithospheric thinning process under Lakshmi is delamination of a dense eclogite lower lithosphere layer into the mantle. The decrease in GTR observed in Ishtar between Lakshmi to the west (GTR ~20 m/km), Maxwell and west Fortuna (GTR~8 m/km), and eastern Fortuna (GTR~4 m/km) may correspond to a decay in thermal compensation attributed to lithospheric delamination, which would be fairly recent (~100 Ma) in Lakshmi, partially decayed in west Fortuna, and absent in east Fortuna, where a mostly Airy-supported topography is essentially relaxed with no thermal uplift. Alternatively, if surficial concentrations in radiogenic elements were prevalent throughout the crust, partial melting of a thickened crust could account for the thermal uplift in Lakshmi and west Fortuna. The zero-elevation basaltic crustal thickness H ~24 km obtained for the east Fortuna Tessera region may be representative of the ambient crustal thickness in the Venus lowlands. Our findings support multicomponent models for tectonic and volcanic activity in Ishtar. The thick ambient crust and thermal lithosphere implied by this study agree with observational constraints such as support of extreme elevations, large topographic slopes, unrelaxed craters, and the thick elastic lithosphere suggested by flexure studies. If the ambient thermal lithosphere on Venus were to be relatively thin (~100-200 km), with a cold mantle and radiogenic elements concentrated in the crust, then thermal evolution on Venus may be in quasi-steady state, with the geodynamic evolution in monotonic decline. However, if the ambient thermal lithosphere is very thick (~300-400 km), as suggested by our thermal model fits, then it is consistent with the predictions of strongly unsteady state thermal evolution models and an interior which is currently heating up. This would support the view that catastrophic resurfacing on Venus might be episodic.

Alpha particle condensation in {sup 12}C and nuclear rainbow scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.

A Kramers-Moyal approach to the analysis of third-order noise with applications in option valuation.

PubMed

Popescu, Dan M; Lipan, Ovidiu

2015-01-01

We propose the use of the Kramers-Moyal expansion in the analysis of third-order noise. In particular, we show how the approach can be applied in the theoretical study of option valuation. Despite Pawula's theorem, which states that a truncated model may exhibit poor statistical properties, we show that for a third-order Kramers-Moyal truncation model of an option's and its underlier's price, important properties emerge: (i) the option price can be written in a closed analytical form that involves the Airy function, (ii) the price is a positive function for positive skewness in the distribution, (iii) for negative skewness, the price becomes negative only for price values that are close to zero. Moreover, using third-order noise in option valuation reveals additional properties: (iv) the inconsistencies between two popular option pricing approaches (using a "delta-hedged" portfolio and using an option replicating portfolio) that are otherwise equivalent up to the second moment, (v) the ability to develop a measure R of how accurately an option can be replicated by a mixture of the underlying stocks and cash, (vi) further limitations of second-order models revealed by introducing third-order noise.

A Kramers-Moyal Approach to the Analysis of Third-Order Noise with Applications in Option Valuation

PubMed Central

Popescu, Dan M.; Lipan, Ovidiu

2015-01-01

We propose the use of the Kramers-Moyal expansion in the analysis of third-order noise. In particular, we show how the approach can be applied in the theoretical study of option valuation. Despite Pawula’s theorem, which states that a truncated model may exhibit poor statistical properties, we show that for a third-order Kramers-Moyal truncation model of an option’s and its underlier’s price, important properties emerge: (i) the option price can be written in a closed analytical form that involves the Airy function, (ii) the price is a positive function for positive skewness in the distribution, (iii) for negative skewness, the price becomes negative only for price values that are close to zero. Moreover, using third-order noise in option valuation reveals additional properties: (iv) the inconsistencies between two popular option pricing approaches (using a “delta-hedged” portfolio and using an option replicating portfolio) that are otherwise equivalent up to the second moment, (v) the ability to develop a measure R of how accurately an option can be replicated by a mixture of the underlying stocks and cash, (vi) further limitations of second-order models revealed by introducing third-order noise. PMID:25625856

A positive-definite form of bounce-averaged quasilinear velocity diffusion for the parallel inhomogeneity in a tokamak

NASA Astrophysics Data System (ADS)

Lee, Jungpyo; Smithe, David; Wright, John; Bonoli, Paul

2018-02-01

In this paper, the analytical form of the quasilinear diffusion coefficients is modified from the Kennel-Engelmann diffusion coefficients to guarantee the positive definiteness of its bounce average in a toroidal geometry. By evaluating the parallel inhomogeneity of plasmas and magnetic fields in the trajectory integral, we can ensure the positive definiteness and help illuminate some non-resonant toroidal effects in the quasilinear diffusion. When the correlation length of the plasma-wave interaction is comparable to the magnetic field variation length, the variation becomes important and the parabolic variation at the outer-midplane, the inner-midplane, and trapping tips can be evaluated by Airy functions. The new form allows the coefficients to include both resonant and non-resonant contributions, and the correlations between the consecutive resonances and in many poloidal periods. The positive-definite form is implemented in a wave code TORIC and we present an example for ITER using this form.

Composition measurements of binary mixture droplets by rainbow refractometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 wasmore » 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.« less

Simulated electron affinity tuning in metal-insulator-metal (MIM) diodes

NASA Astrophysics Data System (ADS)

Mistry, Kissan; Yavuz, Mustafa; Musselman, Kevin P.

2017-05-01

Metal-insulator-metal diodes for rectification applications must exhibit high asymmetry, nonlinearity, and responsivity. Traditional methods of improving these figures of merit have consisted of increasing insulator thickness, adding multiple insulator layers, and utilizing a variety of metal contact combinations. However, these methods have come with the price of increasing the diode resistance and ultimately limiting the operating frequency to well below the terahertz regime. In this work, an Airy Function Transfer Matrix simulation method was used to observe the effect of tuning the electron affinity of the insulator as a technique to decrease the diode resistance. It was shown that a small increase in electron affinity can result in a resistance decrease in upwards of five orders of magnitude, corresponding to an increase in operating frequency on the same order. Electron affinity tuning has a minimal effect on the diode figures of merit, where asymmetry improves or remains unaffected and slight decreases in nonlinearity and responsivity are likely to be greatly outweighed by the improved operating frequency of the diode.

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.

Dual behavior of caustic optical beams facing obstacles

NASA Astrophysics Data System (ADS)

Vaveliuk, Pablo; Martínez-Matos, Óscar; Ren, Yu-Xuan; Lu, Rong-De

2017-06-01

A full propagation analysis on both fold-type and cusp-type caustic optical beams under various setups of obstructions is theoretically and experimentally performed. It is demonstrated that the self-healing property of caustic optical beams that include the famous Airy beam is a quite relative property. In fact, fold-type and cusp-type beams cannot only behave as self-healing beams by blocking the main intensity peak, but also behave as self-breaking ones in a nonintuitive manner: by blocking a lateral side of the beam without touching the central intensity peak. The regeneration and rupture processes of caustic beams follow a nonlocal propagation dynamic unlike the other conventional beams. Moreover, deep differences between fold and cusp caustic beams are pointed out once facing certain obstructions. The cusp-caustic beam can be broken down by the obstacle placed in a dark zone outside the caustic region, while the fold-type one remains unaltered. This beam rupture confirms the key role of a hidden propagating field in the shadow region for cusp beams that coexist with the evanescent one. The obtained results cast down the established idea that the Airy beam is a robust self-healing beam since any caustic beam can behave in a dual manner depending on the obstruction location. These facts open up different perspectives for the applications in which the self-healing properties of the beam are relevant.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noor, Fatimah A., E-mail: fatimah@fi.itb.ac.id; Iskandar, Ferry; Abdullah, Mikrajuddin

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 modelmore » 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.« less

High-speed femtosecond laser beam shaping based on binary holography using a digital micromirror device.

PubMed

Cheng, Jiyi; Gu, Chenglin; Zhang, Dapeng; Chen, Shih-Chi

2015-11-01

In this Letter, we present a digital micromirror device (DMD)-based ultrafast beam shaper, i.e., DUBS. To our knowledge, the DUBS is the first binary laser beam shaper that can generate high-resolution (1140×912 pixels) arbitrary beam modes for femtosecond lasers at a rate of 4.2 kHz; the resolution and pattern rate are limited by the DMD. In the DUBS, the spectrum of the input pulsed laser is first angularly dispersed by a transmission grating and subsequently imaged to a DMD with beam modulation patterns; the transmission grating and a high-reflectivity mirror together compensate the angular dispersion introduced by the DMD. The mode of the output beam is monitored by a CCD camera. In the experiments, the DUBS is programmed to generate four different beam modes, including an Airy beam, Bessel beam, Laguerre-Gaussian (LG) beam, and a custom-designed "peace-dove" beam via the principle of binary holography. To verify the high shaping rate, the Airy beam and LG beam are generated alternately at 4.2 kHz, i.e., the maximum pattern rate of our DMD. The overall efficiency of the DUBS is measured to be 4.7%. With the high-speed and high-resolution beam-shaping capability, the DUBS may find important applications in nonlinear microscopy, optical manipulation, and microscale/nanoscale laser machining, etc.

Elegant Hermite-Airy beams

NASA Astrophysics Data System (ADS)

Zhou, Guoquan; Zhang, Lijun; Ru, Guoyun

2015-09-01

As Ai(x)Ai(-x) can be approximated by \\text{exp}≤ft(-{{x}2}/2\\right) , a kind of elegant Hermite-Airy (EHA) beam that is similar to the elegant Hermite-Gaussian (EHG) beam is introduced in this paper. Analytical expression of the EHA beams passing through an ABCD paraxial optical system is derived. By using the method of numerical fitting, the approximate expressions of 02> , 04> , <\\Thetaj2> , <\\Thetaj4> , and 02\\Thetaj2> for an EHA beam are presented, respectively. When the transverse mode number is larger than 2, 02> , 04> , <\\Thetaj2> , <\\Thetaj4> , and 02\\Thetaj2> of an EHA beam are all larger than those of the EHG beam. Based on the higher-order intensity moments, one can calculate the beam propagation factor, the beam half width, and the kurtosis parameter of the EHA beam passing through an ABCD paraxial optical system. As a numerical example, the propagation characteristics of the EHA beam are demonstrated in free space. Moreover, the propagation properties of the EHA beam are compared with those of the corresponding EHG beam. The evolutionary process of the EHA beam is far slower than that of the corresponding EHG beam. The research denotes that the EHA beams can be used to describe specially distributed optical beams that can not be characterized by the existing EHG beam model. The EHA beam model enriches and replenishes the existing beam model.

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.

Phase Memory Preserving Harmonics from Abruptly Autofocusing Beams.

PubMed

Koulouklidis, Anastasios D; Papazoglou, Dimitris G; Fedorov, Vladimir Yu; Tzortzakis, Stelios

2017-12-01

We demonstrate both theoretically and experimentally that the harmonics from abruptly autofocusing ring-Airy beams present a surprising property: They preserve the phase distribution of the fundamental beam. Consequently, this "phase memory" imparts to the harmonics the abrupt autofocusing behavior, while, under certain conditions, their foci coincide in space with the one of the fundamental. Experiments agree well with our theoretical estimates and detailed numerical calculations. Our findings open the way for the use of such beams and their harmonics in strong field science.

Review of the Probable Maximum Flood (PMF) Snowmelt Analysis for Success Dam

DTIC Science & Technology

2015-11-01

118.53994 36.11754 7200 1981–2014 CA Dept. of Water Resources EGL Eagle Creek Air Temp. Hourly −118.641 35.983 6700 1995–2009 USACE HSS Hossack Air...is in the form of “tiles” with each tile ap- proximately 1200 × 1200 km in area and containing approximately 2400 × 2400 pixels. Each pixel is...District, U.S. Army Corps of Engineers. REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of

Comparison of Three Combat Logistic Force Models

DTIC Science & Technology

1989-03-01

NAVAL POSTGRADUATE SCHOOL Monterey, California lip STATF.4 D TIC AD11S ELECTE S i MAY 3 0 1969 L P.THESIS V CO’:PARISON OF THREE COMBAT LOGISTIC...ORGAWI~ATiON Naval Postqraduante Schoo 55 Naval Postgraduate School 6( ADDRESS (City State anO Z’P C00e 7b ADDRESS (City, State, and ZIP Code) Monterey...OPERATIONS RESEARCH from the NAVAL POSTGRADUATE SCHOOL March 1989 Author: -- /S~in airi H ris Il Approved B\\:_ - (- -J. __ -__ ----- XZ p- Hughesh esis

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.

Shaping non-diffracting beams with a digital micromirror device

NASA Astrophysics Data System (ADS)

Ren, Yu-Xuan; Fang, Zhao-Xiang; Lu, Rong-De

2016-02-01

The micromechanical digital micromirror device (DMD) performs as a spatial light modulator to shape the light wavefront. Different from the liquid crystal devices, which use the birefringence to modulate the light wave, the DMD regulates the wavefront through an amplitude modulation with the digitally controlled mirrors switched on and off. The advantages of such device are the fast speed, polarization insensitivity, and the broadband modulation ability. The fast switching ability for the DMD not only enables the shaping of static light mode, but also could dynamically compensate for the wavefront distortion due to scattering medium. We have employed such device to create the higher order modes, including the Laguerre-Gaussian, Hermite-Gaussian, as well as Mathieu modes. There exists another kind of beam with shape-preservation against propagation, and self-healing against obstacles. Representative modes are the Bessel modes, Airy modes, and the Pearcey modes. Since the DMD modulates the light intensity, a series of algorithms are developed to calculate proper amplitude hologram for shaping the light. The quasi-continuous gray scale images could imitate the continuous amplitude hologram, while the binary amplitude modulation is another means to create the modulation pattern for a steady light field. We demonstrate the generation of the non-diffracting beams with the binary amplitude modulation via the DMD, and successfully created the non-diffracting Bessel beam, Airy beam, and the Pearcey beam. We have characterized the non-diffracting modes through propagation measurements as well as the self-healing measurements.

Paraxial propagation dynamics of the radially polarized Airy beams in uniaxial crystals orthogonal to the optical axis.

PubMed

Xie, Jintao; Zhang, Jianbin; Zheng, Xitao; Ye, Junran; Deng, Dongmei

2018-04-30

We study the paraxial propagation of the radially polarized Airy beams (RPAiBs) in uniaxial crystals orthogonal to the optical axis analytically and numerically. The propagation trajectory, the intensity and the radiation forces of the RPAiBs are investigated and the properties are elucidated by numerical examples in this paper. Results show that the RPAiBs evolve into the beams produced by the x-direction electric field (RPAiXBs) and the y-direction electric field (PRAiYBs) which are totally different in uniaxial crystals. During the propagation, the intensity of the RPAiXBs transfers from the side lobe in the x-direction to the main lobe and finally returns to the side lobe in the x-direction again, but that of the RPAiYBs transfers from the side lobe in the y-direction to the main lobe and flows to the side lobe in the x-direction at last. The effect of the intensity focusing for the RPAiXBs can be modulated by the ratio of the extraordinary index (ne) to the ordinary index (no) in anisotropic medium, which contributes to the intensity focusing of the RPAiBs in a short distance a lot. We can adjust the intensity distribution especially the focusing position, the propagation trajectory and the radiation forces distributions of the RPAiXBs through choosing an appropriate value of the ratio of ne to no to meet the actual usage accordingly.

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.

Asymptotic coincidence of the statistics for degenerate and non-degenerate correlated real Wishart ensembles

NASA Astrophysics Data System (ADS)

Wirtz, Tim; Kieburg, Mario; Guhr, Thomas

2017-06-01

The correlated Wishart model provides the standard benchmark when analyzing time series of any kind. Unfortunately, the real case, which is the most relevant one in applications, poses serious challenges for analytical calculations. Often these challenges are due to square root singularities which cannot be handled using common random matrix techniques. We present a new way to tackle this issue. Using supersymmetry, we carry out an anlaytical study which we support by numerical simulations. For large but finite matrix dimensions, we show that statistical properties of the fully correlated real Wishart model generically approach those of a correlated real Wishart model with doubled matrix dimensions and doubly degenerate empirical eigenvalues. This holds for the local and global spectral statistics. With Monte Carlo simulations we show that this is even approximately true for small matrix dimensions. We explicitly investigate the k-point correlation function as well as the distribution of the largest eigenvalue for which we find a surprisingly compact formula in the doubly degenerate case. Moreover we show that on the local scale the k-point correlation function exhibits the sine and the Airy kernel in the bulk and at the soft edges, respectively. We also address the positions and the fluctuations of the possible outliers in the data.

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.

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.

Observation of the enhanced backscattering of light by the end of a tilted dielectric cylinder owing to the caustic merging transition

NASA Astrophysics Data System (ADS)

Marston, Philip L.; Zhang, Yibing; Thiessen, David B.

2003-01-01

The scattering of light by obliquely illuminated circular dielectric cylinders was previously demonstrated to be enhanced by a merger of Airy caustics at a critical tilt angle. [Appl. Opt. 37, 1534 (1998)]. A related enhancement is demonstrated here for backward and near-backward scattering for cylinders cut with a flat end perpendicular to the cylinder's axis. It is expected that merged caustics will enhance the backscattering by clouds of randomly oriented circular cylinders that have appropriately flat ends.

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.

Structure of kinetic Alfvén waves with small transverse scale length

NASA Astrophysics Data System (ADS)

Morales, G. J.; Maggs, J. E.

1997-11-01

This analytical study illustrates the spatial pattern of kinetic Alfvén waves excited by a current-modulating disk whose dimension a, transverse to the confining magnetic field, is comparable to the ion sound gyroradius cs/Ωi, where cs is the sound speed and Ωi the ion cyclotron frequency. The radial structure of the wave azimuthal magnetic field is found to consist of four regions: a Bessel function behavior for r

Chromatic Dimensions Earthy, Watery, Airy, and Fiery.

PubMed

Albertazzi, Liliana; Koenderink, Jan J; van Doorn, Andrea

2015-01-01

In our study, for a small number of antonyms, we investigate whether they are cross-modally or ideaesthetically related to the space of colors. We analyze the affinities of seven antonyms (cold-hot, dull-radiant, dead-vivid, soft-hard, transparent-chalky, dry-wet, and acid-treacly) and their intermediate connotations (cool-warm, matt-shiny, numb-lively, mellow-firm, semi-transparent-opaque, semi-dry-moist, and sour-sweet) as a function of color. We find that some antonyms relate to chromatic dimensions, others to achromatic ones. The cold-hot antonym proves to be the most salient dimension. The dry-wet dimension coincides with the cold-hot dimension, with dry corresponding to hot and wet to cold. The acid-treacly dimension proves to be transversal to the cold-hot dimension; hence, the pairs mutually span the chromatic domain. The cold-hot and acid-treacly antonyms perhaps recall Hering's opponent color system. The dull-radiant, transparent-chalky, and dead-vivid pairs depend little upon chromaticity. Of all seven antonyms, only the soft-hard one turns out to be independent of the chromatic structure. © The Author(s) 2015.

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.

Detection, imaging, and kinetics of sub-micron organelles of chondrocytes by multiple beam interference microscopy

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.

Maximum of an Airy process plus Brownian motion and memory in Kardar-Parisi-Zhang growth

NASA Astrophysics Data System (ADS)

Le Doussal, Pierre

2017-12-01

We obtain several exact results for universal distributions involving the maximum of the Airy2 process minus a parabola and plus a Brownian motion, with applications to the one-dimensional Kardar-Parisi-Zhang (KPZ) stochastic growth universality class. This allows one to obtain (i) the universal limit, for large time separation, of the two-time height correlation for droplet initial conditions, e.g., C∞=limt2/t1→+∞h(t1) h (t2)¯c/h(t1)2¯c, with C∞≈0.623 , as well as conditional moments, which quantify ergodicity breaking in the time evolution; (ii) in the same limit, the distribution of the midpoint position x (t1) of a directed polymer of length t2; and (iii) the height distribution in stationary KPZ with a step. These results are derived from the replica Bethe ansatz for the KPZ continuum equation, with a "decoupling assumption" in the large time limit. They agree and confirm, whenever they can be compared, with (i) our recent tail results for two-time KPZ with the work by de Nardis and Le Doussal [J. Stat. Mech. (2017) 053212, 10.1088/1742-5468/aa6bce], checked in experiments with the work by Takeuchi and co-workers [De Nardis et al., Phys. Rev. Lett. 118, 125701 (2017), 10.1103/PhysRevLett.118.125701] and (ii) a recent result of Maes and Thiery [J. Stat. Phys. 168, 937 (2017), 10.1007/s10955-017-1839-2] on midpoint position.

Error Estimates for Approximate Solutions of the Riccati Equation with Real or Complex Potentials

NASA Astrophysics Data System (ADS)

Finster, Felix; Smoller, Joel

2010-09-01

A method is presented for obtaining rigorous error estimates for approximate solutions of the Riccati equation, with real or complex potentials. Our main tool is to derive invariant region estimates for complex solutions of the Riccati equation. We explain the general strategy for applying these estimates and illustrate the method in typical examples, where the approximate solutions are obtained by gluing together WKB and Airy solutions of corresponding one-dimensional Schrödinger equations. Our method is motivated by, and has applications to, the analysis of linear wave equations in the geometry of a rotating black hole.

HMI Data Corrected for Stray Light Now Available

NASA Astrophysics Data System (ADS)

Norton, A. A.; Duvall, T. L.; Schou, J.; Cheung, M. C. M.; Scherrer, P. H.

2016-10-01

The form of the point spread function (PSF) derived for HMI is an Airy function convolved with a Lorentzian. The parameters are bound by observational ground-based testing of the instrument conducted prior to launch (Wachter et al., 2012), by full-disk data used to evaluate the off-limb behavior of the scattered light, as well as by data obtained during the Venus transit. The PSF correction has been programmed in both C and cuda C and runs within the JSOC environment using either a CPU or GPU. A single full-disk intensity image can be deconvolved in less than one second. The PSF is described in more detail in Couvidat et al. (2016) and has already been used by Hathaway et al. (2015) to forward-model solar-convection spectra, by Krucker et al. (2015) to investigate footpoints of off-limb solar flares and by Whitney, Criscuoli and Norton (2016) to examine the relations between intensity contrast and magnetic field strengths. In this presentation, we highlight the changes to umbral darkness, granulation contrast and plage field strengths that result from stray light correction. A twenty-four hour period of scattered-light corrected HMI data from 2010.08.03, including the isolated sunspot NOAA 11092, is currently available for anyone. Requests for additional time periods of interest are welcome and will be processed by the HMI team.

On the MAF solution of the uniformly lengthening pendulum via change of independent variable in the Bessel's equation

NASA Astrophysics Data System (ADS)

Deniz, Coşkun

Common recipe for the Lengthening Pendulum (LP) involves some change of variables to give a relationship with the Bessel's equation. In this work, semiclassical MAF (Modified Airy Function) solution of the LP is being obtained by first transforming the related Bessel's equation into the normal form via the suggested change of independent variable just as one of our recent work regarding the JWKB solution of the LP in (Deniz, 2017). MAF approximation of the first order Bessel Functions (ν = 1) of both type along with their zeros are being obtained analytically with a very good accuracy as a result of the appropriately chosen associated initial values and they are extended to the neighbouring orders (ν = 0 and 2) by the recursion relations. Although common numerical methods given in the literature require adiabatic LP systems where the lengthening rate is small, MAF solution presented here can safely be used for higher lengthening rates and a criterion for its validity is determined via the use of MAF applicability criterion given in the literature. As a result, the semiclassical MAF method which is normally used for the quantum mechanical and optical waveguide systems is applied to the classical LP system successfully just as our previous work regarding the JWKB solution of the LP. Interestingly, we have very accurate results in the entire domain except for x ≈ 0 .

Isostatic Gravity Anomalies, Flexure and the Origin of Seaward Dipping Reflectors at Volcanic Rifted Margins

NASA Astrophysics Data System (ADS)

Morgan, R. L.; Watts, A. B.

2016-12-01

Seaward Dipping Reflectors (SDRs) are ubiquitous features of volcanic rifted continental margins where they comprise characteristic wedge-shaped packages of mainly extrusive lava flows. However, their origin has been disputed with some workers suggesting they form by progressive subsidence of extended crust while others propose they are accommodated within the crust by one or more continent-dipping normal faults. We present here a simple model in which SDRs are formed by successive dykes, which intrude and load the crust causing a surface flexure which is subsequently infilled and then loaded by volcanic material, including lava flows. The model explains the arcuate shape, limited offlap geometries and down-dip thickening of SDRs as observed in seismic reflection profiles. By comparing observed and calculated dips we have been able to constrain the elastic plate model type and the effective elastic thickness of rifted lithosphere, Te. Results suggest a broken rather than continuous plate model and Te in the range 3-15 km. The thickness of the resulting SDR package increases with decreasing Te and decreasing compensation density. Decreasing the Tefor successive loads as rifting progresses produces offlap of sub-packages. We have verified our results using process-oriented gravity modelling, in which the gravity effect of surface volcanic infill loads is calculated and combined with the gravity effect of buried dyke loads. Results show good general agreement between observed Airy isostatic anomalies and calculated gravity anomalies. This suggests that the steep gradient that is often observed in the Airy isostatic gravity anomaly at rifted margins is a useful proxy for the landward edge of the dykes that intrude the crust prior to seafloor spreading, rather than a change in basement elevation at the boundary between oceanic and continental crust, as proposed by previous workers.

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.

Three-dimensional infinite order sudden quantum theory for indirect photodissociation processes. Application to the photofragment yield spectrum of NOCl in the region of the T1(13A″) ←S0(11A') transition. Fragment rotational distributions and thermal averages

NASA Astrophysics Data System (ADS)

Grinberg, Horacio; Freed, Karl F.; Williams, Carl J.

1997-08-01

The analytical infinite order sudden (IOS) quantum theory of triatomic photodissociation, developed in paper I, is applied to study the indirect photodissociation of NOCl through a real or virtual intermediate state. The theory uses the IOS approximation for the dynamics in the final dissociative channels and an Airy function approximation for the continuum functions. The transition is taken as polarized in the plane of the molecule; symmetric top wave functions are used for both the initial and intermediate bound states; and simple semiempirical model potentials are employed for each state. The theory provides analytical expressions for the photofragment yield spectrum for producing particular final fragment ro-vibrational states as a function of the photon excitation energy. Computations are made of the photofragment excitation spectrum of NOCl in the region of the T1(13A″)←S0(11A') transition for producing the NO fragment in the vibrational states nNO=0, 1, and 2. The computed spectra for the unexcited nNO==0 and excited nNO=2 states are in reasonable agreement with experiment. However, some discrepancies are observed for the singly excited nNO=1 vibrational state, indicating deficiencies in the semiempirical potential energy surface. Computations for two different orientations of the in-plane transition dipole moment produce very similar excitation spectra. Calculations of fragment rotational distributions are performed for high values of the total angular momentum J, a feature that would be very difficult to perform with close-coupled methods. Computations are also made of the thermally averaged rotational energy distributions to simulate the conditions in actual supersonic jet experiments.

Localization of Nonlocal Symmetries and Symmetry Reductions of Burgers Equation

NASA Astrophysics Data System (ADS)

Wu, Jian-Wen; Lou, Sen-Yue; Yu, Jun

2017-05-01

The nonlocal symmetries of the Burgers equation are explicitly given by the truncated Painlevé method. The auto-Bäcklund transformation and group invariant solutions are obtained via the localization procedure for the nonlocal residual symmetries. Furthermore, the interaction solutions of the solition-Kummer waves and the solition-Airy waves are obtained. Supported by the Global Change Research Program China under Grant No. 2015CB953904, the National Natural Science Foundations of China under Grant Nos. 11435005, 11175092, and 11205092, Shanghai Knowledge Service Platform for Trustworthy Internet of Things under Grant No. ZF1213, and K. C. Wong Magna Fund in Ningbo University

Acoustic focusing by symmetrical self-bending beams with phase modulations

NASA Astrophysics Data System (ADS)

Gao, He; Gu, Zhong-ming; Liang, Bin; Zou, Xin-ye; Yang, Jing; Yang, Jun; Cheng, Jian-chun

2016-02-01

We propose a scheme for generating high-efficient acoustic focusing capable of circumventing obstacles in the propagating medium. This distinct feature that is highly desirable for practical applications is realized by employing two symmetrical Airy beams, and a different type of acoustic lens is designed by using a zero-index medium to provide the required phase profile with extremely high resolution. Furthermore, the scheme has the flexibility of generating tunable focal length. We anticipate our design to open possibilities for the design of acoustic lens and have potential applications in various important scenarios such as biomedical imaging/therapy and non-destructive evaluation.

Arbitrary optical wavefront shaping via spin-to-orbit coupling

NASA Astrophysics Data System (ADS)

Larocque, Hugo; Gagnon-Bischoff, Jérémie; Bouchard, Frédéric; Fickler, Robert; Upham, Jeremy; Boyd, Robert W.; Karimi, Ebrahim

2016-12-01

Converting spin angular momentum to orbital angular momentum has been shown to be a practical and efficient method for generating optical beams carrying orbital angular momentum and possessing a space-varying polarized field. Here, we present novel liquid crystal devices for tailoring the wavefront of optical beams through the Pancharatnam-Berry phase concept. We demonstrate the versatility of these devices by generating an extensive range of optical beams such as beams carrying ±200 units of orbital angular momentum along with Bessel, Airy and Ince-Gauss beams. We characterize both the phase and the polarization properties of the generated beams, confirming our devices’ performance.

Laser focal profiler based on forward scattering of a nanoparticle

NASA Astrophysics Data System (ADS)

Ota, Taisuke

2018-03-01

A laser focal intensity profiling method based on the forward scattering from a nanoparticle is demonstrated for in situ measurements using a laser focusing system with six microscope objective lenses with different numerical apertures ranging from 0.15 to 1.4. The measured profiles showed Airy disc patterns although their rings showed some imperfections due to aberrations and misalignment of the test system. The dipole radiation model revealed that the artefact of this method was much smaller than the influence of the deterioration in the experimental system; a condition where no artefact appears was predicted based on proper selection of measurement angles.

The naming of Neptune

NASA Astrophysics Data System (ADS)

Kollerstrom, Nicholas

2009-03-01

Le Verrier chose the name of Neptune immediately after hearing of the correctness of his prediction. This fact soon became obscured by François Arago's pledge made before the French Académie des Sciences, claiming that Le Verrier had entrusted him with the naming of the new planet. Then, British and German sources weighed in with differing names, and Britain's claim to co-prediction of the planet's position was expressed by their proposal of the name, `Oceanus'. Eventually in February of 1847 Airy urged upon Le Verrier that the name he had originally proposed, namely `Neptune' should be accepted, because it was the only one that could secure consensus.

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.

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 predictable modes, a set of P-E models is established to predict the principal component of each predictable mode, so that the ISMR anomaly pattern can be predicted by using the sum of the predictable modes. Three validation schemes are used to assess the performance of the P-E models' hindcast and independent forecast. The validated TCC skills of the P-E model here are more than doubled that of dynamical models' MME hindcast, suggesting a large room for improvement of the current dynamical prediction. The methodology proposed here can be applied to a wide range of climate prediction and predictability studies. The limitation and future improvement are also discussed.

Analysis of the seismic wavefield in the Moesian Platform (Bucharest area) for hazard assessment purposes

NASA Astrophysics Data System (ADS)

Manea, Elena Florinela; Michel, Clotaire; Hobiger, Manuel; Fäh, Donat; Cioflan, Carmen Ortanza; Radulian, Mircea

2017-09-01

During large earthquakes generated at intermediate depth in the Vrancea seismic zone, the ground motion recorded in Bucharest (Romania) is characterized by predominant long periods with strong amplification. Time-frequency analysis highlights the generation of low frequency surface waves (<1 Hz) for sufficiently strong and superficial events. This phenomenon has been explained by the influence of both source mechanism (radiation pattern, directivity effects) and mechanical properties of the local geological structure (geological layering and geometry). The main goal of our study is to better characterize and understand the seismic wavefield produced by earthquakes in the area of Bucharest, taking into account its location in the centre of the Moesian Platform, a large sedimentary basin (450 km long, 300 km wide and up to 20 km deep). To this aim, we identify the contribution of different seismic surface waves, such as the ones produced at the edges of this large sedimentary basin or multipath interference waves (Airy phases of Love and Rayleigh waves), on ground motion. The data from a 35 km diameter array (URS experiment) were used. The array was installed by the National Institute for Earth Physics in cooperation with the Karlsruhe Institute for Technology and operated during 10 months in 2003 and 2004 in the urban area of Bucharest and adjacent zones. The earthquake wavefield recorded by the URS array was analysed using the MUSIQUE technique. This technique analyses the three-component signals of all sensors of a seismic array together. The analysis includes 19 earthquakes with epicentral distances from 100 to 1560 km and with various backazimuths with enough energy at low frequencies (0.1-1 Hz), within the resolution range of the array. For all events, the largest portion of energy is arriving from the source direction and the wavefield is dominated by Love waves. The results of the array analyses clearly indicate a significant scattering corresponding to 2-D or 3-D effects of the Moesian Platform. The azimuthal distribution shows that the scattering comes primarily from the southern and northern edges of the basin. The Airy phase of Love waves was clearly identified as the main contributor in the range of the fundamental frequency of resonance of the basin (0.15-0.25 Hz), with directionality along the backazimuth and its opposite direction. Moreover, two further distinct frequency bands around 0.4 and 0.7 Hz with higher amplitudes were identified. Their complex nature is a combination of the higher modes of Rayleigh waves, Airy phases of Love waves and SH waves. Love and Rayleigh wave dispersion curves were successfully retrieved by combining the information of all events and show a good match with the ones obtained using ambient vibrations. Additionally, the first higher mode of Rayleigh waves could be retrieved using data from earthquakes. Also, the prograde and retrograde Rayleigh wave ellipticity was computed.

How is the artist role affected when artists are participating in projects in work life?

PubMed

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.

How is the artist role affected when artists are participating in projects in work life?

PubMed Central

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

Strehl-constrained iterative blind deconvolution for post-adaptive-optics data

NASA Astrophysics Data System (ADS)

Desiderà, G.; Carbillet, M.

2009-12-01

Aims: We aim to improve blind deconvolution applied to post-adaptive-optics (AO) data by taking into account one of their basic characteristics, resulting from the necessarily partial AO correction: the Strehl ratio. Methods: We apply a Strehl constraint in the framework of iterative blind deconvolution (IBD) of post-AO near-infrared images simulated in a detailed end-to-end manner and considering a case that is as realistic as possible. Results: The results obtained clearly show the advantage of using such a constraint, from the point of view of both performance and stability, especially for poorly AO-corrected data. The proposed algorithm has been implemented in the freely-distributed and CAOS-based Software Package AIRY.

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.

Amplitude image processing by diffractive optics.

PubMed

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.

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.

Wavelet-based tracking of bacteria in unreconstructed off-axis holograms.

PubMed

Marin, Zach; Wallace, J Kent; Nadeau, Jay; Khalil, Andre

2018-03-01

We propose an automated wavelet-based method of tracking particles in unreconstructed off-axis holograms to provide rough estimates of the presence of motion and particle trajectories in digital holographic microscopy (DHM) time series. The wavelet transform modulus maxima segmentation method is adapted and tailored to extract Airy-like diffraction disks, which represent bacteria, from DHM time series. In this exploratory analysis, the method shows potential for estimating bacterial tracks in low-particle-density time series, based on a preliminary analysis of both living and dead Serratia marcescens, and for rapidly providing a single-bit answer to whether a sample chamber contains living or dead microbes or is empty. Copyright © 2017 Elsevier Inc. All rights reserved.

Rejoice in the hubris: useful things biologists could do for physicists.

PubMed

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.

Rapidly accelerating Mathieu and Weber surface plasmon beams.

PubMed

Libster-Hershko, Ana; Epstein, Itai; Arie, Ady

2014-09-19

We report the generation of two types of self-accelerating surface plasmon beams which are solutions of the nonparaxial Helmholtz equation in two dimensions. These beams preserve their shape while propagating along either elliptic (Mathieu beam) or parabolic (Weber beam) trajectories. We show that owing to the nonparaxial nature of the Weber beam, it maintains its shape over a much larger distance along the parabolic trajectory, with respect to the corresponding solution of the paraxial equation-the Airy beam. Dynamic control of the trajectory is realized by translating the position of the illuminating free-space beam. Finally, the ability of these beams to self-heal after blocking obstacles is demonstrated as well.

Sedimentary and crustal thicknesses and Poisson's ratios for the NE Tibetan Plateau and its adjacent regions based on dense seismic arrays

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.

Optical system design of solar-blind UV target simulator with long focal length

NASA Astrophysics Data System (ADS)

Chen, Yu; Huo, Furong; Zheng, Liqin

2014-11-01

Ultraviolet (UV) radiation of 200nm-300nm waveband from the sun is absorbed by atmosphere, which is often referred to the solar-blind region of the solar spectrum. Solar-blind characteristics of this waveband have important application value, especially in military fields. The application of solar-blind waveband has developed very rapidly, which is receiving more and more attention. Sometimes, to test the performance of a UV optical system, a standard solar-blind UV target simulator is needed as the UV light source. In this paper, an optical system of a solar-blind UV target simulator is designed with waveband 240nm-280nm. To simulate a far UV target, the focal length of this UV optical system needs to be long. Besides, different field of view (FOV) of the system should meet aplanatic condition. The optional materials are very few for UV optical systems, in which only CaF2 and JGS1 are commonly used. Various aberrations are difficult to be corrected. To save production cost and enhance the precision of fabrication and test, aspheric surfaces and binary elements are not adopted in the system. Moreover, doublet or triplet cannot be used in UV optical system considering possible cracking for different thermal expansion coefficients of different materials. After optimization, the system is composed of 4 lenses with focal length 500mm. MTF curves of different FOV coincide together. The maximum RMS radius of the optimized system has almost the same size as Airy disk, which proves the good image quality after system optimization. The aplanatic condition is met very well in this system. In the spot diagram, root mean square (RMS) radius changes from 3 microns to 3.6 microns, which has similar size with Airy disk and meets aplanatic condition very well. This optical system of solar-blind UV target simulator also has relatively loose tolerance data, which can prove the system is designed in an optimal state.

Isostatic response of the Alula-Fartak and Owen transforms in the Eastern Gulf of Aden and the adjoining Arabian Sea

NASA Astrophysics Data System (ADS)

Radhakrishna, M.; Searle, R. C.

2006-04-01

The Alula-Fartak and Owen transforms are the active parts of major fracture zones with a distinct topographic expression in the Eastern Gulf of Aden and the Arabian Sea, respectively. While the Alula-Fartak transform offsets the Sheba Ridge by about 180 km and is associated with a broad steep-sided valley with a relief of nearly 3.5 km, the Owen transform offsets the Carlsberg Ridge by nearly 300 km and is associated with a broad step-like valley surrounded by deeper water depths. The gravity and topography data along several profiles selected across these two transforms have been analysed using cross-spectral analysis in order to investigate their isostatic compensation. The observed admittance estimates have been compared with three theoretical isostatic compensation models, two local compensation models (Airy I and II) and one regional compensation (plate) model. Comparing the longer wavelength admittance estimates suggests that the regional compensation model gives the best fit for both the Alula-Fartak transform and the Owen transform, with effective elastic thickness (Te) of 5 km and slightly less than 10 km, respectively. For the Alula-Fartak transform, the Airy II model might also be acceptable, though with large scatter in the observed values: it suggests a mean value of 9 km for the mantle layer with a 6 km thick crust. For the Owen transform, on the other hand, the two local compensation models failed. The difference in Te estimate between the two transforms could be ascribed to differences in thermal structure arising from their varied tectonic history. A comparison with the isostatic response estimates of transform/fracture zones along the slow-spreading Mid-Atlantic Ridge suggests that the regional compensation model is generally applicable for transform/fracture zone topography along such mid-ocean ridges.

Better executive function under stress mitigates the effects of recent life stress exposure on health in young adults

PubMed Central

Shields, Grant S.; Moons, Wesley G.; Slavich, George M.

2017-01-01

Executive function is a neuropsychological construct that enables controlled cognitive processing, which has been hypothesized to enhance individuals’ resilience to stress. However, little empirical work has directly examined how executive function under different conditions mitigates the negative effects of stress exposure on health. To address this issue, we recruited 110 healthy young adults and assessed their recent life stress exposure, executive function in either a stressful or non-stressful context, and current health complaints. Based on existing research, we hypothesized that individuals exhibiting better executive function following a laboratory-based stressor (but not a control task) would demonstrate weaker associations between recent stress exposure and health because they perceived recent life stressors as being less severe. Consistent with this hypothesis, better executive function during acute stress, but not in the absence of stress, was associated with an attenuated link between participants’ recent life stress exposure and their current health complaints. Moreover, this attenuating effect was mediated by lesser perceptions of stressor severity. Based on these data, we conclude that better executive function under stress is associated with fewer health complaints and that these effects may occur by reducing individuals’ perceptions of stressor severity. The data thus suggest the possibility of reducing stress-related health problems by enhancing executive function. PMID:28114849

Better executive function under stress mitigates the effects of recent life stress exposure on health in young adults.

PubMed

Shields, Grant S; Moons, Wesley G; Slavich, George M

2017-01-01

Executive function is a neuropsychological construct that enables controlled cognitive processing, which has been hypothesized to enhance individuals' resilience to stress. However, little empirical work has directly examined how executive function under different conditions mitigates the negative effects of stress exposure on health. To address this issue, we recruited 110 healthy young adults and assessed their recent life stress exposure, executive function in either a stressful or non-stressful context, and current health complaints. Based on existing research, we hypothesized that individuals exhibiting better executive function following a laboratory-based stressor (but not a control task) would demonstrate weaker associations between recent stress exposure and health because they perceived recent life stressors as being less severe. Consistent with this hypothesis, better executive function during acute stress, but not in the absence of stress, was associated with an attenuated link between participants' recent life stress exposure and their current health complaints. Moreover, this attenuating effect was mediated by lesser perceptions of stressor severity. Based on these data, we conclude that better executive function under stress is associated with fewer health complaints and that these effects may occur by reducing individuals' perceptions of stressor severity. The data thus suggest the possibility of reducing stress-related health problems by enhancing executive function.

Effect of stress hyperglycemia and intensive rehabilitation therapy in non-diabetic hemorrhagic stroke: Korean Stroke Cohort for Functioning and Rehabilitation.

PubMed

Yoon, J A; Kim, D Y; Sohn, M K; Lee, J; Lee, S-G; Lee, Y-S; Han, E Y; Joo, M C; Oh, G-J; Han, J; Lee, S W; Park, M; Chang, W H; Shin, Y-I; Kim, Y-H

2016-11-01

We investigated the effect of stress hyperglycemia on the functional outcomes of non-diabetic hemorrhagic stroke. In addition, we investigated the usefulness of intensive rehabilitation for improving functional outcomes in patients with stress hyperglycemia. Non-diabetic hemorrhagic stroke patients were recruited and divided into two groups: intracerebral hemorrhage (ICH) (n = 165) and subarachnoid hemorrhage (SAH) (n = 156). Each group was divided into non-diabetics with or without stress hyperglycemia. Functional assessments were performed at 7 days and 3, 6 and 12 months after stroke onset. The non-diabetic with stress hyperglycemia groups were again divided into two groups who either received or did not receive intensive rehabilitation treatment. Serial functional outcome was compared between groups. For the ICH group, patients with stress hyperglycemia had worse modified Rankin Scale, National Institutes of Health Stroke Scale, Functional Ambulatory Category and Korean Mini-Mental State Examination scores than patients without stress hyperglycemia. For the SAH group, patients with stress hyperglycemia had worse scores on all functional assessments than patients without stress hyperglycemia at all time-points. After intensive rehabilitation treatment of patients with stress hyperglycemia, the ICH group had better scores on Functional Ambulatory Category and the SAH group had better scores on all functional assessments than patients without intensive rehabilitation treatment. Stress hyperglycemia affects the long-term prognosis of non-diabetic hemorrhagic stroke patients. Among stress hyperglycemia patients, intensive rehabilitation can enhance functional improvement after stroke. © 2016 EAN.

A photoemission moments model using density functional and transfer matrix methods applied to coating layers on surfaces: Theory

NASA Astrophysics Data System (ADS)

Jensen, Kevin L.; Finkenstadt, Daniel; Shabaev, Andrew; Lambrakos, Samuel G.; Moody, Nathan A.; Petillo, John J.; Yamaguchi, Hisato; Liu, Fangze

2018-01-01

Recent experimental measurements of a bulk material covered with a small number of graphene layers reported by Yamaguchi et al. [NPJ 2D Mater. Appl. 1, 12 (2017)] (on bialkali) and Liu et al. [Appl. Phys. Lett. 110, 041607 (2017)] (on copper) and the needs of emission models in beam optics codes have lead to substantial changes in a Moments model of photoemission. The changes account for (i) a barrier profile and density of states factor based on density functional theory (DFT) evaluations, (ii) a Drude-Lorentz model of the optical constants and laser penetration depth, and (iii) a transmission probability evaluated by an Airy Transfer Matrix Approach. Importantly, the DFT results lead to a surface barrier profile of a shape similar to both resonant barriers and reflectionless wells: the associated quantum mechanical transmission probabilities are shown to be comparable to those recently required to enable the Moments (and Three Step) model to match experimental data but for reasons very different than the assumption by conventional wisdom that a barrier is responsible. The substantial modifications of the Moments model components, motivated by computational materials methods, are developed. The results prepare the Moments model for use in treating heterostructures and discrete energy level systems (e.g., quantum dots) proposed for decoupling the opposing metrics of performance that undermine the performance of advanced light sources like the x-ray Free Electron Laser. The consequences of the modified components on quantum yield, emittance, and emission models needed by beam optics codes are discussed.

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.

Vicarious Collecting: A Review of Some Notable Books about Books - and where to acquire them!

NASA Astrophysics Data System (ADS)

Koester, Jack

Reviews on Milestones of Science, Ruth A. Sparrow, Buffalo Museum of Science, 1972, The Face of the Moon, from the Linda Hall Library, Out of this World - The Golden Age of the Celestial Atlas, Linda Hall Library, including Bayer's Uranometria, Schiller's Coelum Christianum, Hevelius' Firmamentum, Flamsteed's Atlas Coelestis, and Bode's Uranographia, as well as Argelander, Bode, Cellarius, Coronelli, Doppelmaier, Kepler, La Caille, Messier, Piccolomini, and Wollaston, Heavenly Library, Angus MacDonald and A.D. Morrison-Low from Royal Observatory Edinburgh, Library, 1994, Catalogue of the Rare Astronomical Books in the San Diego State University Library, Louis A. Kenney, 1988, and Vanity Fair, from 1869 to 1914, including caricatures of famous astronomers and scientists, such as Airy, Ball, Huggins, and Proctor.

Nuclear rainbow in elastic scattering of {sup 9}Be nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glukhov, Yu. A., E-mail: gloukhov@inbox.ru; Ogloblin, A. A.; Artemov, K. 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 determinemore » unambiguously the nucleus-nucleus potential with a high probability.« less

Ada Compiler Validation Summary Report: Certificate Number: 891126I1. 10221 Telesoft TeleGen2 Ada Development System for HP 9000/340 x MVME133a-20.

DTIC Science & Technology

1989-11-26

e(rrors.only x - F(ie..only -.errs x -f(ormat x -G(raph x x -g(eierate..ofr x -l(nline x -i(nhibit x -k(eep x x -L( ist x -M(ap x -m(airi x -N(ame x...erbose -e(rrors-.only C -CmIe to object -c/pu.type 20 -d(ebug -kieep -O(ptiznize <key+,> - S(ource..asm -u(pdate-lib <key.-> -x(ecution-.profile -L( ist ...generate execution-profile code. 2.1.12 Listing options: -C(ontext <value> Include 1 line of context with error 2.1.13.1 message. -L( ist Do not

Heat trap - An optimized far infrared field optics system. [for astronomical sources

NASA Technical Reports Server (NTRS)

Harper, D. A.; Hildebrand, R. H.; Winston, R.; Stiening, R.

1976-01-01

The article deals with the design and performance of a heat trap IR system designed to maximize the concentration and efficient reception of far IR and submillimeter wavelength radiation. The test object is assumed to be extended and/or viewed at wavelengths much longer than the detector, and the entrance aperture is limited to the size of the telescope Airy diffraction disk. The design of lenses, cavity, bolometers, light collectors, and mirrors for the system is discussed. Advantages and feasibility of arrays of heat traps are considered. Beam patterns, flux concentration, and performance variation with wavelength are dealt with. The heat trap is recommended for sensing all types of far IR sources and particularly for extended far IR sources.-

Study of a coronagraphic mask using evanescent waves.

PubMed

Buisset, Christophe; Rabbia, Yves; Lepine, Thierry; Alagao, Mary-Angelie; Ducrot, Elsa; Poshyachinda, Saran; Soonthornthum, Boonrucksar

2017-04-03

The evanescent wave coronagraph (EvWaCo) is a specific kind of band-limited coronagraph using the frustrated total internal reflection phenomenon to produce the coronagraphic effect (removing starlight from the image plane in order to make the stellar environment detectable). In this paper, we present a theoretical and experimental study of the EvWaCo coronagraphic mask. First, we calculate the theoretical transmission and we show that this mask is partially achromatic. Then, we present the experimental results obtained in unpolarized light at the wavelength λ≈900 nm and relative spectral bandwidth Δλ/λ≈6%. In particular, we show that the coronagraph provides a contrast down to a few 10^-6 at an angular distance of about ten Airy radii.

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.

Laplace and the era of differential equations

NASA Astrophysics Data System (ADS)

Weinberger, Peter

2012-11-01

Between about 1790 and 1850 French mathematicians dominated not only mathematics, but also all other sciences. The belief that a particular physical phenomenon has to correspond to a single differential equation originates from the enormous influence Laplace and his contemporary compatriots had in all European learned circles. It will be shown that at the beginning of the nineteenth century Newton's "fluxionary calculus" finally gave way to a French-type notation of handling differential equations. A heated dispute in the Philosophical Magazine between Challis, Airy and Stokes, all three of them famous Cambridge professors of mathematics, then serves to illustrate the era of differential equations. A remark about Schrödinger and his equation for the hydrogen atom finally will lead back to present times.

On Certain Functionals of the Maximum of Brownian Motion and Their Applications

NASA Astrophysics Data System (ADS)

Perret, Anthony; Comtet, Alain; Majumdar, Satya N.; Schehr, Grégory

2015-12-01

We consider a Brownian motion (BM) x(τ ) and its maximal value x_{max } = max _{0 ≤ τ ≤ t} x(τ ) on a fixed time interval [0, t]. We study functionals of the maximum of the BM, of the form {O}_{max }(t)=int _0^t V(x_{max } - x(τ )) {d}τ where V( x) can be any arbitrary function and develop various analytical tools to compute their statistical properties. These tools rely in particular on (i) a "counting paths" method and (ii) a path-integral approach. In particular, we focus on the case where V(x) = δ (x-r), with r a real parameter, which is relevant to study the density of near-extreme values of the BM (the so called density of states), ρ (r,t), which is the local time of the BM spent at given distance r from the maximum. We also provide a thorough analysis of the family of functionals {T}_{α }(t)=int _0^t (x_{max } - x(τ ))^α {{d}}τ corresponding to V(x) = x^α with α real. As α is varied, T_α (t) interpolates between different interesting observables. For instance, for α =1, T_{α = 1}(t) is a random variable of the "area", or "Airy", type while for α =-1/2 it corresponds to the maximum time spent by a ballistic particle through a Brownian random potential. On the other hand, for α = -1, it corresponds to the cost of the optimal algorithm to find the maximum of a discrete random walk, proposed by Odlyzko. We revisit here, using tools of theoretical physics, the statistical properties of this algorithm which had been studied before using probabilistic methods. Finally, we extend our methods to constrained BM, including in particular the Brownian bridge, i.e., the Brownian motion starting and ending at the origin.

Cognitive reserve and self-efficacy as moderators of the relationship between stress exposure and executive functioning among spousal dementia caregivers.

PubMed

Pertl, M M; Hannigan, C; Brennan, S; Robertson, I H; Lawlor, B A

2017-04-01

A substantial literature has reported that stress negatively impacts on cognitive processes. As dementia caregiving can be stressful, it has been hypothesized that the challenges of dementia care may increase caregivers' own vulnerability to cognitive decline. Prefrontal processes are thought to be most vulnerable to stress; however, few studies have examined whether greater caregiver stress predicts poorer executive dysfunction, and no previous research has considered potential moderators of this relationship. We examined (1) whether greater psychological stress mediated a relationship between caregiver stress exposure and executive functioning and (2) whether greater self-efficacy and cognitive reserve (CR) moderated this relationship. Spousal dementia caregivers (n = 253) completed the Neuropsychiatric Inventory Questionnaire (stress exposure), the Perceived Stress Scale, the National Adult Reading Test (CR), the Fortinsky dementia-specific caregiver self-efficacy scale, and the Color Trails Test (executive functioning). Moderated mediation was tested using the PROCESS macro. Age, gender, and dementia risk factors were included as covariates. Greater stress exposure indirectly predicted executive functioning through psychological stress. Stronger relationships between greater psychological stress and poorer executive functioning were observed among caregivers with lower CR; there was no evidence that self-efficacy moderated the relationship between stress exposure and psychological stress. Our findings are in line with the idea that greater psychological stress in response to challenges associated with dementia care predicts poorer caregiver executive functioning, particularly among caregivers with low CR. However, these findings are cross sectional; it is also possible that poorer executive functioning contributes to greater caregiver stress.

The Role of Stress Exposure and Family Functioning in Internalizing Outcomes of Urban Families

PubMed Central

Henry, David B.; Tolan, Patrick H.; Strachan, Martha K.

2013-01-01

Although research suggests that stress exposure and family functioning are associated with internalizing problems in adolescents and caregivers, surprisingly few studies have investigated the mechanisms that underlie this association. To determine whether family functioning buffers the development of internalizing problems in stress-exposed families, we assessed the relation between stress exposure, family functioning, and internalizing symptoms among a large sample of inner-city male youth and their caregivers living in poverty across five waves of data collection. We hypothesized that stress exposure and family functioning would predict development of subsequent youth and caregiver internalizing problems and that family functioning would moderate this relation, with higher functioning families demonstrating greater resiliency to stress exposure. We used a longitudinal, prospective design to evaluate whether family functioning (assessed at waves one through four) activated or buffered the effects of stress exposure (assessed at wave one) on subsequent internalizing symptoms (assessed at waves four and five). Stress from Developmental Transitions and family functioning were significant predictors of depressive symptoms and anxiety in youth; however, family functioning did not moderate the relation. Family functioning mediated the relation between stress from Daily Hassles and internalizing outcomes suggesting that poor parenting practices, low structure, and low emotional cohesion activate depression and anxiety in youth exposed to chronic and frequent everyday stressors. Surprisingly, only family functioning predicted depressive symptoms in caregivers. Results validate the use of a comprehensive, multi-informant assessment of stress when investigating internalizing outcomes in youth and support using family-based interventions in the treatment and prevention of internalizing. PMID:25601821

The Role of Stress Exposure and Family Functioning in Internalizing Outcomes of Urban Families.

PubMed

Sheidow, Ashli J; Henry, David B; Tolan, Patrick H; Strachan, Martha K

2014-11-01

Although research suggests that stress exposure and family functioning are associated with internalizing problems in adolescents and caregivers, surprisingly few studies have investigated the mechanisms that underlie this association. To determine whether family functioning buffers the development of internalizing problems in stress-exposed families, we assessed the relation between stress exposure, family functioning, and internalizing symptoms among a large sample of inner-city male youth and their caregivers living in poverty across five waves of data collection. We hypothesized that stress exposure and family functioning would predict development of subsequent youth and caregiver internalizing problems and that family functioning would moderate this relation, with higher functioning families demonstrating greater resiliency to stress exposure. We used a longitudinal, prospective design to evaluate whether family functioning (assessed at waves one through four) activated or buffered the effects of stress exposure (assessed at wave one) on subsequent internalizing symptoms (assessed at waves four and five). Stress from Developmental Transitions and family functioning were significant predictors of depressive symptoms and anxiety in youth; however, family functioning did not moderate the relation. Family functioning mediated the relation between stress from Daily Hassles and internalizing outcomes suggesting that poor parenting practices, low structure, and low emotional cohesion activate depression and anxiety in youth exposed to chronic and frequent everyday stressors. Surprisingly, only family functioning predicted depressive symptoms in caregivers. Results validate the use of a comprehensive, multi-informant assessment of stress when investigating internalizing outcomes in youth and support using family-based interventions in the treatment and prevention of internalizing.

Latino Parent Acculturation Stress: Longitudinal Effects on Family Functioning and Youth Emotional and Behavioral Health

PubMed Central

Lorenzo-Blanco, Elma I.; Meca, Alan; Unger, Jennifer B.; Romero, Andrea; Gonzales-Backen, Melinda; Piña-Watson, Brandy; Cano, Miguel A.; Zamboanga, Byron L.; Des Rosiers, Sabrina E.; Soto, Daniel W.; Villamar, Juan A.; Lizzi, Karina M.; Pattarroyo, Monica; Schwartz, Seth J.

2016-01-01

Latino parents can experience acculturation stressors, and according to the Family Stress Model, parent stress can influence youth mental health and substance use by negatively affecting family functioning. To understand how acculturation stressors come together and unfold over time to influence youth mental health and substance use outcomes, the current study investigated the trajectory of a latent parent acculturation stress factor and its influence on youth mental health and substance use via parent-and youth-reported family functioning. Data came from a six-wave, school-based survey with 302 recent (< 5 years) immigrant Latino parents (74% mothers, M age = 41.09 years) and their adolescents (47% female, M age = 14.51 years). Parents’ reports of discrimination, negative context of reception, and acculturative stress loaded onto a latent factor of acculturation stress at each of the first four time points. Earlier levels of and increases in parent acculturation stress predicted worse youth-reported family functioning. Additionally, earlier levels of parent acculturation stress predicted worse parent-reported family functioning and increases in parent acculturation stress predicted better parent-reported family functioning. While youth-reported positive family functioning predicted higher self-esteem, lower symptoms of depression, lower aggressive and rule-breaking behavior in youth, parent-reported family positive functioning predicted lower youth alcohol and cigarette use. Findings highlight the need for Latino youth preventive interventions to target parent acculturation stress and family functioning. PMID:27819441

Racism-Related Stress, General Life Stress, and Psychological Functioning among Black American Women

ERIC Educational Resources Information Center

Pieterse, Alex L.; Carter, Robert T.; Ray, Kilynda V.

2013-01-01

The relationship between general life stress, perceived racism, and psychological functioning was explored in a sample of 118 Black American women. Findings indicate that racism-related stress was not a significant predictor of psychological functioning when controlling for general life stress. Perceived racism was positively associated with…

Minority stress and relationship functioning among young male same-sex couples: An examination of actor-partner interdependence models.

PubMed

Feinstein, Brian A; McConnell, Elizabeth; Dyar, Christina; Mustanski, Brian; Newcomb, Michael E

2018-05-01

In different-sex couples, individual and partner stress can both have a negative impact on relationship functioning (actor and partner effects). Gay and bisexual men experience unique stress (sexual minority stress), but few studies have examined the effects of this stress on relationship functioning among young male couples. The current study examined (a) actor and partner effects of general and minority stress (internalized stigma, microaggressions, victimization, and outness) on relationship functioning (relationship quality and negative relationship interactions), (b) interactions between individual and partner stress as predictors of relationship functioning, and (c) dyadic coping and relationship length as moderators of actor and partner effects. Actor-partner interdependence models were tested using data from 153 young male couples. There was strong support for actor effects. Higher general stress and internalized stigma were associated with lower relationship quality, but only for those in longer relationships. Additionally, higher general stress, internalized stigma, and microaggressions, and lower outness, were associated with more negative relationship interactions. There was limited support for partner effects. Having a partner with higher internalized stigma was associated with more negative relationship interactions, but none of the other partner effects were significant. There was no support for individual and partner stress interacting to predict relationship functioning or for dyadic coping as a stress buffer. Findings highlight the influence of one's own experiences of general and minority stress on relationship functioning, but raise questions about how partner stress influences relationship functioning among young male couples. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

The Arabidopsis PLAT domain protein1 is critically involved in abiotic stress tolerance.

PubMed

Hyun, Tae Kyung; van der Graaff, Eric; Albacete, Alfonso; Eom, Seung Hee; Großkinsky, Dominik K; Böhm, Hannah; Janschek, Ursula; Rim, Yeonggil; Ali, Walid Wahid; Kim, Soo Young; Roitsch, Thomas

2014-01-01

Despite the completion of the Arabidopsis genome sequence, for only a relatively low percentage of the encoded proteins experimental evidence concerning their function is available. Plant proteins that harbour a single PLAT (Polycystin, Lipoxygenase, Alpha-toxin and Triacylglycerol lipase) domain and belong to the PLAT-plant-stress protein family are ubiquitously present in monocot and dicots. However, the function of PLAT-plant-stress proteins is still poorly understood. Therefore, we have assessed the function of the uncharacterised Arabidopsis PLAT-plant-stress family members through a combination of functional genetic and physiological approaches. PLAT1 overexpression conferred increased abiotic stress tolerance, including cold, drought and salt stress, while loss-of-function resulted in opposite effects on abiotic stress tolerance. Strikingly, PLAT1 promoted growth under non-stressed conditions. Abiotic stress treatments induced PLAT1 expression and caused expansion of its expression domain. The ABF/ABRE transcription factors, which are positive mediators of abscisic acid signalling, activate PLAT1 promoter activity in transactivation assays and directly bind to the ABRE elements located in this promoter in electrophoretic mobility shift assays. This suggests that PLAT1 represents a novel downstream target of the abscisic acid signalling pathway. Thus, we showed that PLAT1 critically functions as positive regulator of abiotic stress tolerance, but also is involved in regulating plant growth, and thereby assigned a function to this previously uncharacterised PLAT domain protein. The functional data obtained for PLAT1 support that PLAT-plant-stress proteins in general could be promising targets for improving abiotic stress tolerance without yield penalty.

The Arabidopsis PLAT Domain Protein1 Is Critically Involved in Abiotic Stress Tolerance

PubMed Central

Eom, Seung Hee; Großkinsky, Dominik K.; Böhm, Hannah; Janschek, Ursula; Rim, Yeonggil; Ali, Walid Wahid; Kim, Soo Young; Roitsch, Thomas

2014-01-01

Despite the completion of the Arabidopsis genome sequence, for only a relatively low percentage of the encoded proteins experimental evidence concerning their function is available. Plant proteins that harbour a single PLAT (Polycystin, Lipoxygenase, Alpha-toxin and Triacylglycerol lipase) domain and belong to the PLAT-plant-stress protein family are ubiquitously present in monocot and dicots. However, the function of PLAT-plant-stress proteins is still poorly understood. Therefore, we have assessed the function of the uncharacterised Arabidopsis PLAT-plant-stress family members through a combination of functional genetic and physiological approaches. PLAT1 overexpression conferred increased abiotic stress tolerance, including cold, drought and salt stress, while loss-of-function resulted in opposite effects on abiotic stress tolerance. Strikingly, PLAT1 promoted growth under non-stressed conditions. Abiotic stress treatments induced PLAT1 expression and caused expansion of its expression domain. The ABF/ABRE transcription factors, which are positive mediators of abscisic acid signalling, activate PLAT1 promoter activity in transactivation assays and directly bind to the ABRE elements located in this promoter in electrophoretic mobility shift assays. This suggests that PLAT1 represents a novel downstream target of the abscisic acid signalling pathway. Thus, we showed that PLAT1 critically functions as positive regulator of abiotic stress tolerance, but also is involved in regulating plant growth, and thereby assigned a function to this previously uncharacterised PLAT domain protein. The functional data obtained for PLAT1 support that PLAT-plant-stress proteins in general could be promising targets for improving abiotic stress tolerance without yield penalty. PMID:25396746

Latino parent acculturation stress: Longitudinal effects on family functioning and youth emotional and behavioral health.

PubMed

Lorenzo-Blanco, Elma I; Meca, Alan; Unger, Jennifer B; Romero, Andrea; Gonzales-Backen, Melinda; Piña-Watson, Brandy; Cano, Miguel Ángel; Zamboanga, Byron L; Des Rosiers, Sabrina E; Soto, Daniel W; Villamar, Juan A; Lizzi, Karina M; Pattarroyo, Monica; Schwartz, Seth J

2016-12-01

Latino parents can experience acculturation stressors, and according to the Family Stress Model (FSM), parent stress can influence youth mental health and substance use by negatively affecting family functioning. To understand how acculturation stressors come together and unfold over time to influence youth mental health and substance use outcomes, the current study investigated the trajectory of a latent parent acculturation stress factor and its influence on youth mental health and substance use via parent-and youth-reported family functioning. Data came from a 6-wave, school-based survey with 302 recent (<5 years) immigrant Latino parents (74% mothers, Mage = 41.09 years) and their adolescents (47% female, Mage = 14.51 years). Parents' reports of discrimination, negative context of reception, and acculturative stress loaded onto a latent factor of acculturation stress at each of the first 4 time points. Earlier levels of and increases in parent acculturation stress predicted worse youth-reported family functioning. Additionally, earlier levels of parent acculturation stress predicted worse parent-reported family functioning and increases in parent acculturation stress predicted better parent-reported family functioning. While youth-reported positive family functioning predicted higher self-esteem, lower symptoms of depression, and lower aggressive and rule-breaking behavior in youth, parent-reported family positive functioning predicted lower youth alcohol and cigarette use. Findings highlight the need for Latino youth preventive interventions to target parent acculturation stress and family functioning. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Quantum-classical correspondence for the inverted oscillator

NASA Astrophysics Data System (ADS)

Maamache, Mustapha; Ryeol Choi, Jeong

2017-11-01

While quantum-classical correspondence for a system is a very fundamental problem in modern physics, the understanding of its mechanism is often elusive, so the methods used and the results of detailed theoretical analysis have been accompanied by active debate. In this study, the differences and similarities between quantum and classical behavior for an inverted oscillator have been analyzed based on the description of a complete generalized Airy function-type quantum wave solution. The inverted oscillator model plays an important role in several branches of cosmology and particle physics. The quantum wave packet of the system is composed of many sub-packets that are localized at different positions with regular intervals between them. It is shown from illustrations of the probability density that, although the quantum trajectory of the wave propagation is somewhat different from the corresponding classical one, the difference becomes relatively small when the classical excitation is sufficiently high. We have confirmed that a quantum wave packet moving along a positive or negative direction accelerates over time like a classical wave. From these main interpretations and others in the text, we conclude that our theory exquisitely illustrates quantum and classical correspondence for the system, which is a crucial concept in quantum mechanics. Supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2016R1D1A1A09919503)

Structure of the Flat Slab in Southern Peru

NASA Astrophysics Data System (ADS)

Ma, Y.; Clayton, R. W.

2014-12-01

We investigate the detailed structure of the flat-subduction portion of the subduction zone in Southern Peru using converted phases recorded by the PeruSE seismic array. The migrated image along a profile above the flat subduction is shown in the figure, overlain by the receiver functions of one well-recorded event. We see that the slab descends to 100 km depth at a distance of about 100 km inland from the coast, and then it rises to 90 km depth and remains flat for the next 300 km distance before diving into the mantle. The Moho itself has about 10 km relief above the flat slab, which is anti-correlated with the surface topography indicating Airy compensation. Interestingly, the flat slab image is missing under this part of Moho. The mid-crust structure is also evident. In the west, it coincides with the Andean Low Velocity Zone (ALVZ) mapped in this region (Ma and Clayton, 2014). In the east, it is related with the underthrusting Brazilian Shield (Phillips and Clayton, 2014). In this paper, we further investigate the causes of the missing or weak flat slab signal, possibly due to anomalous attenuation of S waves in the mantle wedge (but not P wave, since Moho is well imaged). We will also extend our study to the flat-normal transition area beneath the array.

Red rainbows at sunset/sunrise

NASA Astrophysics Data System (ADS)

Ricard, J. L.

2016-12-01

The rainbow model deveeloped at CEPAL is based on the Airy theory. The outputs show that a pure red rainbow could only observed from a hill or a mountain when the sun is below the horizon. When the sun is on the horizon, there should be a juxtaposition of a red band on the outside and of a yellow band on the inside (upper figures). However, observers report pure red bows at sea level (lower left figure). In these rare cases, it is possible to still see the sun after it has set. As sunlight passes through more and more dense atmosphere at sunset the light slows and bends closer and closer toward the normal. When the eye traces the light ray it appears to be higher in the sky (lower right figure).

Covariance of lucky images for increasing objects contrast: diffraction-limited images in ground-based telescopes

NASA Astrophysics Data System (ADS)

Cagigal, Manuel P.; Valle, Pedro J.; Colodro-Conde, Carlos; Villó-Pérez, Isidro; Pérez-Garrido, Antonio

2016-01-01

Images of stars adopt shapes far from the ideal Airy pattern due to atmospheric density fluctuations. Hence, diffraction-limited images can only be achieved by telescopes without atmospheric influence, e.g. spatial telescopes, or by using techniques like adaptive optics or lucky imaging. In this paper, we propose a new computational technique based on the evaluation of the COvariancE of Lucky Images (COELI). This technique allows us to discover companions to main stars by taking advantage of the atmospheric fluctuations. We describe the algorithm and we carry out a theoretical analysis of the improvement in contrast. We have used images taken with 2.2-m Calar Alto telescope as a test bed for the technique resulting that, under certain conditions, telescope diffraction limit is clearly reached.

Experimental observation of sub-Rayleigh quantum imaging with a two-photon entangled source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, De-Qin; School of Science, Tianjin University of Technology and Education, Tianjin 300222; Song, Xin-Bing

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 predictionmore » in the two-photon quantum imaging regime.« less

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.

The effect of surgical and psychological stress on learning and memory function in aged C57BL/6 mice.

PubMed

Zhang, C; Li, C; Xu, Z; Zhao, S; Li, P; Cao, J; Mi, W

2016-04-21

Postoperative cognitive dysfunction (POCD) is an important complication following major surgery and general anesthesia in older patients. However, the etiology of POCD remains largely to be determined. It is unknown how surgical stress and psychological stress affect the postoperative learning and memory function in geriatric patients. We therefore established a pre-clinical model in aged C57BL/6 mice and aimed to investigate the effects of surgical stress and psychological stress on learning and memory function and the possible roles of the protein kinase B/mammalian target of rapamycin (AKT/mTOR) pathway. The surgical stress was induced by abdominal surgery under local anesthesia, and the psychological stress was induced by a communication box. Cognitive functions and markers of the AKT/mTOR pathway were assessed at 1, 3 and 7 days following the stress. The impairments of learning and memory function existed for up to 7 days following surgical stress and surgical stress plus psychological stress, whereas the psychological stress did not affect the cognitive function alone or combined with surgical stress. Analysis of brain tissue revealed a significant involvement of the AKT/mTOR pathway in the impairment of cognition. These data suggested that surgical stress could induce cognitive impairment in aged mice and perioperative psychological stress is not a constitutive factor of POCD. The AKT/mTOR pathway is likely involved as one of the underlying mechanisms of the development of POCD. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Negative Social Evaluation Impairs Executive Functions in Adolescents With Excess Weight: Associations With Autonomic Responses.

PubMed

Padilla, María Moreno; Fernández-Serrano, María J; Verdejo García, Antonio; Reyes Del Paso, Gustavo A

2018-06-22

Adolescents with excess weight suffer social stress more frequently than their peers with normal weight. To examine the impact of social stress, specifically negative social evaluation, on executive functions in adolescents with excess weight. We also examined associations between subjective stress, autonomic reactivity, and executive functioning. Sixty adolescents (aged 13-18 years) classified into excess weight or normal weight groups participated. We assessed executive functioning (working memory, inhibition, and shifting) and subjective stress levels before and after the Trier Social Stress Task (TSST). The TSST was divided into two phases according to the feedback of the audience: positive and negative social evaluation. Heart rate and skin conductance were recorded. Adolescents with excess weight showed poorer executive functioning after exposure to TSST compared with adolescents with normal weight. Subjective stress and autonomic reactivity were also greater in adolescents with excess weight than adolescents with normal weight. Negative social evaluation was associated with worse executive functioning and increased autonomic reactivity in adolescents with excess weight. The findings suggest that adolescents with excess weight are more sensitive to social stress triggered by negative evaluations. Social stress elicited deterioration of executive functioning in adolescents with excess weight. Evoked increases in subjective stress and autonomic responses predicted decreased executive function. Deficits in executive skills could reduce cognitive control abilities and lead to overeating in adolescents with excess weight. Strategies to cope with social stress to prevent executive deficits could be useful to prevent future obesity in this population.

Plant Abiotic Stress Proteomics: The Major Factors Determining Alterations in Cellular Proteome

PubMed Central

Kosová, Klára; Vítámvás, Pavel; Urban, Milan O.; Prášil, Ilja T.; Renaut, Jenny

2018-01-01

HIGHLIGHTS: Major environmental and genetic factors determining stress-related protein abundance are discussed.Major aspects of protein biological function including protein isoforms and PTMs, cellular localization and protein interactions are discussed.Functional diversity of protein isoforms and PTMs is discussed. Abiotic stresses reveal profound impacts on plant proteomes including alterations in protein relative abundance, cellular localization, post-transcriptional and post-translational modifications (PTMs), protein interactions with other protein partners, and, finally, protein biological functions. The main aim of the present review is to discuss the major factors determining stress-related protein accumulation and their final biological functions. A dynamics of stress response including stress acclimation to altered ambient conditions and recovery after the stress treatment is discussed. The results of proteomic studies aimed at a comparison of stress response in plant genotypes differing in stress adaptability reveal constitutively enhanced levels of several stress-related proteins (protective proteins, chaperones, ROS scavenging- and detoxification-related enzymes) in the tolerant genotypes with respect to the susceptible ones. Tolerant genotypes can efficiently adjust energy metabolism to enhanced needs during stress acclimation. Stress tolerance vs. stress susceptibility are relative terms which can reflect different stress-coping strategies depending on the given stress treatment. The role of differential protein isoforms and PTMs with respect to their biological functions in different physiological constraints (cellular compartments and interacting partners) is discussed. The importance of protein functional studies following high-throughput proteome analyses is presented in a broader context of plant biology. In summary, the manuscript tries to provide an overview of the major factors which have to be considered when interpreting data from proteomic studies on stress-treated plants. PMID:29472941

PSF Rotation with Changing Defocus and Applications to 3D Imaging for Space Situational Awareness

NASA Astrophysics Data System (ADS)

Prasad, S.; Kumar, R.

2013-09-01

For a clear, well corrected imaging aperture in space, the point-spread function (PSF) in its Gaussian image plane has the conventional, diffraction-limited, tightly focused Airy form. Away from that plane, the PSF broadens rapidly, however, resulting in a loss of sensitivity and transverse resolution that makes such a traditional best-optics approach untenable for rapid 3D image acquisition. One must scan in focus to maintain high sensitivity and resolution as one acquires image data, slice by slice, from a 3D volume with reduced efficiency. In this paper we describe a computational-imaging approach to overcome this limitation, one that uses pupil-phase engineering to fashion a PSF that, although not as tight as the Airy spot, maintains its shape and size while rotating uniformly with changing defocus over many waves of defocus phase at the pupil edge. As one of us has shown recently [1], the subdivision of a circular pupil aperture into M Fresnel zones, with the mth zone having an outer radius proportional to m and impressing a spiral phase profile of form m? on the light wave, where ? is the azimuthal angle coordinate measured from a fixed x axis (the dislocation line), yields a PSF that rotates with defocus while keeping its shape and size. Physically speaking, a nonzero defocus of a point source means a quadratic optical phase in the pupil that, because of the square-root dependence of the zone radius on the zone number, increases on average by the same amount from one zone to the next. This uniformly incrementing phase yields, in effect, a rotation of the dislocation line, and thus a rotated PSF. Since the zone-to-zone phase increment depends linearly on defocus to first order, the PSF rotates uniformly with changing defocus. For an M-zone pupil, a complete rotation of the PSF occurs when the defocus-induced phase at the pupil edge changes by M waves. Our recent simulations of reconstructions from image data for 3D image scenes comprised of point sources at different focal depths have shown remarkable robustness of our rotating-PSF approach to achieve good transverse and longitudinal resolution even for moderate SNR. Additionally, the work seeks to clarify an important theoretical issue about 3D imaging, namely the detailed nature of the interplay between transverse and longitudinal resolutions, including 3D generalizations of the space-bandwidth product (SBP) and its dependence on image noise. An underlying transport equation, which we shall derive and analyze, describes the trade-off between the transverse and longitudinal blur processes in a manner analogous to the diffractive spreading of a light beam that is transversely confined. This work has immediate applications for space-based surveillance, particularly for 3D mapping and tracking of space debris flying in the vicinity of important AF space assets. Working with a well corrected conventional imager, our 3D computational imager can acquire with high sensitivity and speed an extended focal volume in which individual objects of interest can be subsequently probed and imaged with high resolution over smaller 2D field segments. [1] S. Prasad, Rotating Point Spread Function by Pupil Phase Engineering, Opt. Lett., vol. 38, pp. 585-587 (2013)

A photoemission moments model using density functional and transfer matrix methods applied to coating layers on surfaces: Theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jensen, Kevin L.; Finkenstadt, Daniel; Shabaev, Andrew

Recent experimental measurements of a bulk material covered with a small number of graphene layers reported by Yamaguchi et al. [NPJ 2D Mater. Appl. 1, 12 (2017)] (on bialkali) and Liu et al.[Appl. Phys. Lett. 110, 041607 (2017)] (on copper) and the needs of emission models in beam optics codes have lead to substantial changes in a Moments model of photoemission. The changes account for (i) a barrier profile and density of states factor based on density functional theory (DFT) evaluations, (ii) a Drude-Lorentz model of the optical constants and laser penetration depth, and (iii) a transmission probability evaluated bymore » an Airy Transfer Matrix Approach. Importantly, the DFT results lead to a surface barrier profile of a shape similar to both resonant barriers and reflectionless wells: the associated quantum mechanical transmission probabilities are shown to be comparable to those recently required to enable the Moments (and Three Step) model to match experimental data but for reasons very different than the assumption by conventional wisdom that a barrier is responsible. The substantial modifications of the Moments model components, motivated by computational materials methods, are developed. The results prepare the Moments model for use in treating heterostructures and discrete energy level systems (e.g., quantum dots) proposed for decoupling the opposing metrics of performance that undermine the performance of advanced light sources like the x-ray Free Electron Laser. The consequences of the modified components on quan-tum yield, emittance, and emission models needed by beam optics codes are discussed. Published by AIP Publishing. https://doi.org/10.1063/1.5008600« less

A photoemission moments model using density functional and transfer matrix methods applied to coating layers on surfaces: Theory

DOE PAGES

Jensen, Kevin L.; Finkenstadt, Daniel; Shabaev, Andrew; ...

2018-01-28

Recent experimental measurements of a bulk material covered with a small number of graphene layers reported by Yamaguchi et al. [NPJ 2D Mater. Appl. 1, 12 (2017)] (on bialkali) and Liu et al.[Appl. Phys. Lett. 110, 041607 (2017)] (on copper) and the needs of emission models in beam optics codes have lead to substantial changes in a Moments model of photoemission. The changes account for (i) a barrier profile and density of states factor based on density functional theory (DFT) evaluations, (ii) a Drude-Lorentz model of the optical constants and laser penetration depth, and (iii) a transmission probability evaluated bymore » an Airy Transfer Matrix Approach. Importantly, the DFT results lead to a surface barrier profile of a shape similar to both resonant barriers and reflectionless wells: the associated quantum mechanical transmission probabilities are shown to be comparable to those recently required to enable the Moments (and Three Step) model to match experimental data but for reasons very different than the assumption by conventional wisdom that a barrier is responsible. The substantial modifications of the Moments model components, motivated by computational materials methods, are developed. The results prepare the Moments model for use in treating heterostructures and discrete energy level systems (e.g., quantum dots) proposed for decoupling the opposing metrics of performance that undermine the performance of advanced light sources like the x-ray Free Electron Laser. The consequences of the modified components on quan-tum yield, emittance, and emission models needed by beam optics codes are discussed. Published by AIP Publishing. https://doi.org/10.1063/1.5008600« less

Subacute stress and chronic stress interact to decrease intestinal barrier function in rats.

PubMed

Lauffer, Adriana; Vanuytsel, Tim; Vanormelingen, Christophe; Vanheel, Hanne; Salim Rasoel, Shadea; Tóth, Joran; Tack, Jan; Fornari, Fernando; Farré, Ricard

2016-01-01

Psychological stress increases intestinal permeability, potentially leading to low-grade inflammation and symptoms in functional gastrointestinal disorders. We assessed the effect of subacute, chronic and combined stress on intestinal barrier function and mast cell density. Male Wistar rats were allocated to four experimental groups (n = 8/group): 1/sham; 2/subacute stress (isolation and limited movement for 24 h); 3/chronic crowding stress for 14 days and 4/combined subacute and chronic stress. Jejunum and colon were collected to measure: transepithelial electrical resistance (TEER; a measure of epithelial barrier function); gene expression of tight junction molecules; mast cell density. Plasma corticosterone concentration was increased in all three stress conditions versus sham, with highest concentrations in the combined stress condition. TEER in the jejunum was decreased in all stress conditions, but was significantly lower in the combined stress condition than in the other groups. TEER in the jejunum correlated negatively with corticosterone concentration. Increased expression of claudin 1, 5 and 8, occludin and zonula occludens 1 mRNAs was detected after subacute stress in the jejunum. In contrast, colonic TEER was decreased only after combined stress, and the expression of tight junction molecules was unaltered. Increased mast cell density was observed in the chronic and combined stress condition in the colon only. In conclusion, our data show that chronic stress sensitizes the gastrointestinal tract to the effects of subacute stress on intestinal barrier function; different underlying cellular and molecular alterations are indicated in the small intestine versus the colon.

Family functioning, parenting stress and quality of life in mothers and fathers of Polish children with high functioning autism or Asperger syndrome

PubMed Central

2017-01-01

The aim of the study was to investigate the perception of the family functioning in parents of children with autism spectrum disorders (ASD) with normal-range intelligence and the relationships between family functioning, parenting stress and quality of life. Dyads of parents of children with ASD without intellectual disability and parents of typically developing children (controls) completed a set of self-report questionnaires. Parents of children with ASD reported lower functioning of the family as a whole and their own functioning as family members; they exhibited higher levels of parenting stress and lower quality of life. Mothers of children with ASD experienced more stress in personal domain than fathers. Relationships between family functioning, parenting stress and quality of life have been established. There were also moderate to strong correlations in mother-father dyads between their assessments of family functioning, parenting stress and QoL in social relationships and environmental domains. PMID:29036188

Family functioning, parenting stress and quality of life in mothers and fathers of Polish children with high functioning autism or Asperger syndrome.

PubMed

Pisula, Ewa; Porębowicz-Dörsmann, Anna

2017-01-01

The aim of the study was to investigate the perception of the family functioning in parents of children with autism spectrum disorders (ASD) with normal-range intelligence and the relationships between family functioning, parenting stress and quality of life. Dyads of parents of children with ASD without intellectual disability and parents of typically developing children (controls) completed a set of self-report questionnaires. Parents of children with ASD reported lower functioning of the family as a whole and their own functioning as family members; they exhibited higher levels of parenting stress and lower quality of life. Mothers of children with ASD experienced more stress in personal domain than fathers. Relationships between family functioning, parenting stress and quality of life have been established. There were also moderate to strong correlations in mother-father dyads between their assessments of family functioning, parenting stress and QoL in social relationships and environmental domains.

Effects of the Cognitive-Behavioral Therapy for Stress Management on Executive Function Components.

PubMed

Santos-Ruiz, Ana; Robles-Ortega, Humbelina; Pérez-García, Miguel; Peralta-Ramírez, María Isabel

2017-02-13

This study aims to determine whether it is possible to modify executive function in stressed individuals by means of cognitive-behavioral therapy for stress management. Thirty-one people with high levels of perceived stress were recruited into the study (treatment group = 18; wait-list group = 13). The treatment group received 14 weeks of stress management program. Psychological and executive function variables were evaluated in both groups pre and post-intervention. The treatment group showed improved psychological variables of perceived stress (t = 5.492; p = .001), vulnerability to stress (t = 4.061; p = .001) and superstitious thinking (t = 2.961; p = .009). Likewise, the results showed statistically significant differences in personality variables related to executive function, positive urgency (t = 3.585; p = .002) and sensitivity to reward (t = -2.201; p = .042), which improved after the therapy. These variables showed a moderate to high effect size (oscillates between 1.30 for perceived stress and .566 for sensitivity to reward). The cognitive-behavioral therapy for stress management may be an appropriate strategy for improving personality construct components related to executive function, however effects of the therapy are not showed on performance on the tests of executive function applied, as presented studies previous.

The Effects of Acute Stress on Core Executive Functions: A Meta-Analysis and Comparison with Cortisol

PubMed Central

Shields, Grant S.; Sazma, Matthew A.; Yonelinas, Andrew P.

2016-01-01

Core executive functions such as working memory, inhibition, and cognitive flexibility are integral to daily life. A growing body of research has suggested that acute stress may impair core executive functions. However, there are a number of inconsistencies in the literature, leading to uncertainty about how or even if acute stress influences core executive functions. We addressed this by conducting a meta-analysis of acute stress effects on working memory, inhibition, and cognitive flexibility. We found that stress impaired working memory and cognitive flexibility, whereas it had nuanced effects on inhibition. Many of these effects were moderated by other variables, such as sex. In addition, we compared effects of acute stress on core executive functions to effects of cortisol administration and found some striking differences. Our findings indicate that stress works through mechanisms aside from or in addition to cortisol to produce a state characterized by more reactive processing of salient stimuli but greater control over actions. We conclude by highlighting some important future directions for stress and executive function research. PMID:27371161

The Relationship between Stress and Social Functioning in Adults with Autism Spectrum Disorder and without Intellectual Disability

PubMed Central

Bishop-Fitzpatrick, Lauren; Mazefsky, Carla A.; Minshew, Nancy J.; Eack, Shaun M.

2014-01-01

Scientific Abstract Adults with autism spectrum disorder (ASD) face substantial challenges accomplishing basic tasks associated with daily living, which are exacerbated by their broad and pervasive difficulties with social interactions. These challenges put people with ASD at increased risk for psychophysiological distress, which likely factors heavily into social functioning for adults with ASD, as suggested by a growing literature on stress in children that indicates that children with ASD have differential responses to stress than healthy children. We hypothesized that adults with ASD and without intellectual disability (n=38) would experience more stress than healthy volunteers (n=37) and that there would be an inverse relationship between stress and social functioning in individuals with ASD. Baseline, semi-structured interview data from a randomized-controlled trial of two treatments for adults with ASD were used to assess differences in stress between adults with ASD and healthy volunteers and to assess the relationship between stress response and social functioning in adults with ASD. Findings indicate that adults with ASD experience greater perceived and interviewer-observed stress than did healthy volunteers and that stress is significantly related to social functioning in adults with ASD. These findings highlight the role of stress in adult functioning and outcomes and suggest the need to develop and assess treatments designed to target stress and coping in adults with ASD. PMID:25524571

The Four-Quadrant Phase-Mask Coronagraph. I. Principle

NASA Astrophysics Data System (ADS)

Rouan, D.; Riaud, P.; Boccaletti, A.; Clénet, Y.; Labeyrie, A.

2000-11-01

We describe a new type of coronagraph, based on the principle of a phase mask as proposed by Roddier and Roddier a few years ago but using an original mask design found by one of us (D. R.), a four-quadrant binary phase mask (0, π) covering the full field of view at the focal plane. The mutually destructive interferences of the coherent light from the main source produce a very efficient nulling. The computed rejection rate of this coronagraph appears to be very high since, when perfectly aligned and phase-error free, it could in principle reduce the total amount of light from the bright source by a factor of 108, corresponding to a gain of 20 mag in brightness at the location of the first Airy ring, relative to the Airy peak. In the real world the gain is of course reduced by a strong factor, but nulling is still performing quite well, provided that the perturbation of the phase, for instance, due to the Earth's atmosphere, is efficiently corrected by adaptive optics. We show from simulations that a detection at a contrast of 10 mag between a star and a faint companion is achievable in excellent conditions, while 8 mag appears routinely feasible. This coronagraph appears less sensitive to atmospheric turbulence and has a larger dynamic range than other recently proposed nulling techniques: the phase-mask coronagraph (by Roddier and Roddier) or the Achromatic Interfero-Coronagraph (by Gay and Rabbia). We present the principle of the four-quadrant coronagraph and results of a first series of simulations. We compare those results with theoretical performances of other devices. We briefly analyze the different limitations in space or ground-based observations, as well as the issue of manufacturing the device. We also discuss several ways to improve the detection of a faint companion around a bright object. We conclude that, with respect to previous techniques, an instrument equipped with this coronagraph should have better performance and even enable the imaging of extrasolar giant planets at a young stage, when coupled with additional cleaning techniques.

Frequency and Wavevector Dependence of the Atomic Level Stress-Stress Correlation Function in a Model Supercooled Liquid

NASA Astrophysics Data System (ADS)

Levashov, Valentin A.; Morris, James R.; Egami, Takeshi

2012-02-01

Temporal and spatial correlations among the local atomic level shear stresses were studied for a model liquid iron by molecular dynamics simulation [PRL 106,115703]. Integration over time and space of the shear stress correlation function F(r,t) yields viscosity via Green-Kubo relation. The stress correlation function in time and space F(r,t) was Fourier transformed to study the dependence on frequency, E, and wave vector, Q. The results, F(Q,E), showed damped shear stress waves propagating in the liquid for small Q at high and low temperatures. We also observed additional diffuse feature that appears as temperature is reduced below crossover temperature of potential energy landscape at relatively low frequencies at small Q. We suggest that this additional feature might be related to dynamic heterogeneity and boson peaks. We also discuss a relation between the time-scale of the stress-stress correlation function and the alpha-relaxation time of the intermediate self-scattering function S(Q,E).

Biodiversity effects on ecosystem functioning change along environmental stress gradients.

PubMed

Steudel, Bastian; Hector, Andy; Friedl, Thomas; Löfke, Christian; Lorenz, Maike; Wesche, Moritz; Kessler, Michael; Gessner, Mark

2012-12-01

Positive relationship between biodiversity and ecosystem functioning has been observed in many studies, but how this relationship is affected by environmental stress is largely unknown. To explore this influence, we measured the biomass of microalgae grown in microcosms along two stress gradients, heat and salinity, and compared our results with 13 published case studies that measured biodiversity-ecosystem functioning relationships under varying environmental conditions. We found that positive effects of biodiversity on ecosystem functioning decreased with increasing stress intensity in absolute terms. However, in relative terms, increasing stress had a stronger negative effect on low-diversity communities. This shows that more diverse biotic communities are functionally less susceptible to environmental stress, emphasises the need to maintain high levels of biodiversity as an insurance against impacts of changing environmental conditions and sets the stage for exploring the mechanisms underlying biodiversity effects in stressed ecosystems. © 2012 Blackwell Publishing Ltd/CNRS.

The effect of stress induction on working memory in patients with psychogenic nonepileptic seizures.

PubMed

Bakvis, Patricia; Spinhoven, Philip; Putman, Peter; Zitman, Frans G; Roelofs, Karin

2010-11-01

Although psychogenic nonepileptic seizures (PNES) are considered a stress-induced paroxysmal disintegration of cognitive functions, it remains unknown whether stress indeed impairs cognitive integrative functions, such as working memory (WM), in patients with PNES. An N-back task with emotional distracters (angry, happy, and neutral faces) was administered at baseline and after stress induction (Cold Pressor Test) to 19 patients with PNES and 20 matched healthy controls. At baseline, patients displayed increased WM interference for the facial distracters. After stress induction, group differences generalized to the no-distracter condition. Within patients, high cortisol stress responses were associated with larger stress-induced WM impairments in the no-distracter condition. These findings demonstrate that patients' cognitive integrative functions are impaired by social distracters and stress induction. Moreover, the stress- and cortisol-related generalization of the relative WM impairments offers a promising experimental model for the characteristic paroxysmal disintegration of attentional and mnemonic functions in patients with PNES associated with stress. Copyright © 2010 Elsevier Inc. All rights reserved.

Oxidative stress markers, cognitive functions, and psychosocial functioning in bipolar disorder: an empirical cross-sectional study.

PubMed

Aydemir, Ömer; Çubukçuoğlu, Zeynep; Erdin, Soner; Taş, Cumhur; Onur, Ece; Berk, Michael

2014-01-01

This study aimed to evaluate the relationship between oxidative stress markers and cognitive functions and domains of psychosocial functioning in bipolar disorder. Oxidative stress markers, cognitive functions, and domains of psychosocial functioning were evaluated in 51 patients with bipolar disorder who were in remission. Correlation analyses between these parameters were calculated with data controlled for duration of illness and number of episodes. There was no statistically significant correlation between oxidative stress markers and cognitive functions. In terms of psychosocial functioning, significant correlations were found between malondialdehyde and sense of stigmatization (r = -0.502); household activities and superoxide dismutase (r = 0.501); participation in social activities and nitric oxide (r = 0.414); hobbies and leisure time activities and total glutathione (r = -0.567), superoxide dismutase (r = 0.667), and neurotrophin 4 (r = 0.450); and taking initiative and self-sufficiency and superoxide dismutase (r = 0.597). There was no correlation between other domains of psychosocial functioning and oxidative stress markers. These results imply that oxidative stress markers do not appear to correlate clearly with cognitive impairment and reduced psychosocial functioning. However, there were some associations between selected oxidative markers and activity-oriented functional markers. This may represent a true negative association, or may be an artifact of oxidative stress being a state rather than a trait marker.

Impaired Functional Connectivity in the Prefrontal Cortex: A Mechanism for Chronic Stress-Induced Neuropsychiatric Disorders

PubMed Central

Negrón-Oyarzo, Ignacio; Aboitiz, Francisco; Fuentealba, Pablo

2016-01-01

Chronic stress-related psychiatric diseases, such as major depression, posttraumatic stress disorder, and schizophrenia, are characterized by a maladaptive organization of behavioral responses that strongly affect the well-being of patients. Current evidence suggests that a functional impairment of the prefrontal cortex (PFC) is implicated in the pathophysiology of these diseases. Therefore, chronic stress may impair PFC functions required for the adaptive orchestration of behavioral responses. In the present review, we integrate evidence obtained from cognitive neuroscience with neurophysiological research with animal models, to put forward a hypothesis that addresses stress-induced behavioral dysfunctions observed in stress-related neuropsychiatric disorders. We propose that chronic stress impairs mechanisms involved in neuronal functional connectivity in the PFC that are required for the formation of adaptive representations for the execution of adaptive behavioral responses. These considerations could be particularly relevant for understanding the pathophysiology of chronic stress-related neuropsychiatric disorders. PMID:26904302

Finite Element Simulation and Experimental Verification of Internal Stress of Quenched AISI 4140 Cylinders

NASA Astrophysics Data System (ADS)

Liu, Yu; Qin, Shengwei; Hao, Qingguo; Chen, Nailu; Zuo, Xunwei; Rong, Yonghua

2017-03-01

The study of internal stress in quenched AISI 4140 medium carbon steel is of importance in engineering. In this work, the finite element simulation (FES) was employed to predict the distribution of internal stress in quenched AISI 4140 cylinders with two sizes of diameter based on exponent-modified (Ex-Modified) normalized function. The results indicate that the FES based on Ex-Modified normalized function proposed is better consistent with X-ray diffraction measurements of the stress distribution than FES based on normalized function proposed by Abrassart, Desalos and Leblond, respectively, which is attributed that Ex-Modified normalized function better describes transformation plasticity. Effect of temperature distribution on the phase formation, the origin of residual stress distribution and effect of transformation plasticity function on the residual stress distribution were further discussed.

Environmental stress, oxytocin receptor gene (OXTR) polymorphism, and mental health following collective stress.

PubMed

Lucas-Thompson, Rachel G; Holman, E Alison

2013-04-01

We examined whether the oxytocin receptor gene (OXTR) single nucleotide polymorphism (SNP) rs53576 genotype buffers the combined impact of negative social environments (e.g., interpersonal conflict/constraint) and economic stress on post-traumatic stress (PTS) symptoms and impaired daily functioning following collective stress (September 11th terrorist attacks). Saliva was collected by mail and used to genotype 704 respondents. Participants completed Web-based assessments of pre-9/11 mental health, acute stress 9-23 days after 9/11, the quality of social environments 1 year post-9/11, economic stress 18 months post-9/11, and PTS symptoms and impaired functioning 2 and 3 years post-9/11. Interactions between negative social environments and economic stress were examined separately based on OXTR rs53576 genotype (GG vs. any A allele). For individuals with an A allele, a negative social environment significantly increased PTS symptoms without regard to the level of economic stress experienced. However, for respondents with a GG genotype, negative social environments predicted elevated PTS symptoms only for those also experiencing high economic stress. Gender moderated associations between negative social environments, economic stress, and impaired functioning. The functioning of females was most affected by negative social environments regardless of genotype and economic stress, whereas the functioning of males was differentially susceptible to economic stress depending on OXTR genotype and negative social environments. These findings suggest that it is important to consider the combined impact of gender and ongoing stress in different domains as moderators of genetic vulnerability following collective stress. Copyright © 2013 Elsevier Inc. All rights reserved.

Effects of temperament, symptom severity and level of functioning on maternal stress in Greek children and youth with ASD.

PubMed

Konstantareas, M Mary; Papageorgiou, Vaya

2006-11-01

This study examined the effect of child temperament, symptom severity, verbal ability and level of functioning on maternal stress in 43 Greek mothers of children and young people with autism spectrum disorder. Symptom severity was assessed by the CARS, level of functioning by the PEP, temperament by the Dimensions of Temperament Scale (DOTS-R) and maternal stress by the Clarke Modification of Holroyd's Questionnaire on Resources and Stress (QRS). Lower-functioning children and those with high activity level, low flexibility and low mood scores were perceived to be more stressful. Counter to expectation, children with ASD who were rated high on rhythmicity and task orientation were perceived as more stressful. Best predictors of maternal stress were high activity level, low mood and high symptom severity. Mothers of non-verbal children were more stressed than those of verbal. The relevance of child temperament for understanding maternal stress is discussed with particular relevance to the Greek culture and available supports.

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.

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.

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.

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.

Fortuna Tessera, Venus - Evidence of horizontal convergence and crustal thickening

NASA Technical Reports Server (NTRS)

Vorder Bruegge, R. W.; Head, J. W.

1989-01-01

Structural and tectonic patterns mapped in Fortuna Tessera are interpreted to reflect a change in the style and intensity of deformation from east to west, beginning with simple tessera terrain at relatively low topographic elevations in the east and progressing through increasingly complex deformation patterns and higher topography to Maxwell Montes in the West. These morphologic and topographic patterns are consistent with east-to-west convergence and compression and the increasing elevations are interpreted to be due to crustal thickening processes associated with the convergent deformational environment. Using an Airy isostatic model, crustal thicknesses of approximately 35 km for the initial tessera terrain, and crustal thicknesses of over 100 km for the Maxwell Montes region are predicted. Detailed mapping with Magellan data will permit the deconvolution of individual components and structures in this terrain.

Simultaneous 3D tracking of passive tracers and microtubule bundles in an active gel

NASA Astrophysics Data System (ADS)

Fan, Yi; Breuer, Kenneth S.; Fluids Team

Kinesin-driven microtubule bundles generate a spontaneous flow in unconfined geometries. They exhibit properties of active matter, including the emergence of collective motion, reduction of apparent viscosity and consumption of local energy. Here we present results from 3D tracking of passive tracers (using Airy rings and 3D scanning) synchronized with 3D measurement of the microtubule bundles motion. This technique is applied to measure viscosity variation and collective flow in a confined geometry with particular attention paid to the self-pumping system recently reported by Wu et al. (2016). Results show that the viscosity in an equilibrium microtubule network is around half that of the isotropic unbundled microtubule solution. Cross-correlations of the active microtubule network and passive tracers define a neighborhood around microtubule bundles in which passive tracers are effectively transported. MRSEC NSF.

Executive function in cancer patients with posttraumatic stress disorder.

PubMed

Yang, Juan; Guo, Juncheng; Jiang, Xiangling

2017-03-01

Background Cancer patients with posttraumatic stress disorder can lead to their noncompliant behaviors. However, less is known about the neurocognitive functioning of posttraumatic stress disorder in general cancer types or patient populations. The current study attempted to examine the prevalence of posttraumatic stress disorder and their relationships with executive function in individuals with cancer. Methods A total of 285 cancer patients with posttraumatic stress disorder and 150 healthy individuals were recruited for the present study. The Clinician Administered PTSD Scale, Tower of Hanoi, Wisconsin Card Sorting Test, and Wechsler Adult Intelligence Scale-Revised Chinese revision were administered to all participants. Results Significant differences in the score of Tower of Hanoi, Wisconsin Card Sorting Test, and Wechsler Adult Intelligence Scale-Revised Chinese revision were observed between the posttraumatic stress disorder group and the healthy control group ( p < 0.001). Significant correlations were found between all posttraumatic stress disorder symptoms and executive function. Conclusions These findings suggest that individuals with cancer-related posttraumatic stress disorder exhibit more severe impairment in executive function than healthy controls do.

Parenting stress in pediatric IBD: relations with child psychopathology, family functioning, and disease severity.

PubMed

Gray, Wendy N; Graef, Danielle M; Schuman, Shana S; Janicke, David M; Hommel, Kevin A

2013-05-01

Parenting stress in pediatric inflammatory bowel disease (IBD) has been under-examined. Data validating use of the Pediatric Inventory for Parents (PIP), a measure of parenting stress associated with caring for a chronically ill child, in chronic diseases with intermittent, unpredictable disease courses, such as IBD, are needed. This study presents validity data in support of the PIP in pediatric IBD and examines relations between parenting stress and important psychosocial and medical outcomes. Adolescents (N = 130) with IBD and their caregivers across 3 sites completed measures of parenting stress, family functioning, and emotional/behavioral functioning. Disease severity was also assessed for each participant. The PIP demonstrates excellent internal consistency. Parenting stress was significantly higher among those with unhealthy general family functioning and those with children with borderline or clinically elevated internalizing symptoms. Caregiving stress was greater among parents of youth with more active Crohn's disease. Results supported the reliability and validity of the PIP for assessing caregiving stress in pediatric IBD. Routine assessment of parenting stress is recommended, particularly among parents reporting unhealthy family functioning and parents of youth with borderline or clinically elevated internalizing symptoms and more active disease.

Neural traces of stress: cortisol related sustained enhancement of amygdala-hippocampal functional connectivity

PubMed Central

Vaisvaser, Sharon; Lin, Tamar; Admon, Roee; Podlipsky, Ilana; Greenman, Yona; Stern, Naftali; Fruchter, Eyal; Wald, Ilan; Pine, Daniel S.; Tarrasch, Ricardo; Bar-Haim, Yair; Hendler, Talma

2013-01-01

Stressful experiences modulate neuro-circuitry function, and the temporal trajectory of these alterations, elapsing from early disturbances to late recovery, heavily influences resilience and vulnerability to stress. Such effects of stress may depend on processes that are engaged during resting-state, through active recollection of past experiences and anticipation of future events, all known to involve the default mode network (DMN). By inducing social stress and acquiring resting-state functional magnetic resonance imaging (fMRI) before stress, immediately following it, and 2 h later, we expanded the time-window for examining the trajectory of the stress response. Throughout the study repeated cortisol samplings and self-reports of stress levels were obtained from 51 healthy young males. Post-stress alterations were investigated by whole brain resting-state functional connectivity (rsFC) of two central hubs of the DMN: the posterior cingulate cortex (PCC) and hippocampus. Results indicate a ’recovery’ pattern of DMN connectivity, in which all alterations, ascribed to the intervening stress, returned to pre-stress levels. The only exception to this pattern was a stress-induced rise in amygdala-hippocampal connectivity, which was sustained for as long as 2 h following stress induction. Furthermore, this sustained enhancement of limbic connectivity was inversely correlated to individual stress-induced cortisol responsiveness (AUCi) and characterized only the group lacking such increased cortisol (i.e., non-responders). Our observations provide evidence of a prolonged post-stress response profile, characterized by both the comprehensive balance of most DMN functional connections and the distinct time and cortisol dependent ascent of intra-limbic connectivity. These novel insights into neuro-endocrine relations are another milestone in the ongoing search for individual markers in stress-related psychopathologies. PMID:23847492

A comparative study of the effect of stress on the cognitive parameters in women with increased body mass index before and after menopause.

PubMed

Ramesh, M B; Ammu, S; Nayanatara, A K; Vinodini, N A; Pratik, K C; Anupama, N; Bhagyalakshmi, K

2018-03-23

The increasing prevalence of overweight and obesity is a critical public health problem for women. The negative effect of stress on memory and cognitive functions has been widely explored for decades in numerous research projects using a wide range of methodology. Deterioration of memory and other brain functions is a hallmark of Alzheimer's disease. Estrogen fluctuations and withdrawal have myriad direct effects on the central nervous system that have the potential to influence cognitive functions. The present study aims to compare the effect of stress on the cognitive functions in overweight/obese women before and after menopause. A total of 142 female subjects constituting women before menopause between the ages of 18 and 44 years and women after menopause between the ages of 45 and 60 years were included in the sample. Participants were categorized into overweight/obese groups based on the body mass index. The major tool perceived stress scale was used for measuring the perception of stress. On the basis of the stress scale measurement, each group was classified into with stress and without stress. Addenbrooke's Cognitive Examination-III was used for measuring the cognitive functions. Premenopausal women with stress showed a significant (p<0.05) decrease in the cognitive parameters such as attention and orientation, fluency, language and visuospatial ability. Memory did not show any significant changes in this group. Whereas, in the postmenopausal stressed women, all the cognitive functions except fluency showed a significant (p<0.05) decrease. Stress is a significant factor on the cognitive functions of obese and overweight women before and after menopause. Practice of yoga and encouragement in activities like gardening, embroidery, games and relaxation techniques should be recommended to prevent stress. Insights into the neurobiology before and after menopause can be gained from future studies examining the effect on the hypothalamic-pituitary-adrenal axis in relation to cognition and stress.

Perceived stress and cognitive function in older adults: which aspect of perceived stress is important?

PubMed

Korten, Nicole C M; Comijs, Hannie C; Penninx, Brenda W J H; Deeg, Dorly J H

2017-04-01

Few studies examined the association between perceived stress and cognitive function in older adults. This study will examine which aspects of perceived stress especially impact cognitive function. Cross-sectional data of 1099 older adults between 64 and 100 years from the Longitudinal Aging Study Amsterdam were used. Perceived stress and its subscales perceived helplessness and perceived self-efficacy were measured with the Perceived Stress Scale. Cognitive function was assessed regarding memory, processing speed and executive function. Univariate and multivariate linear regression analyses were performed between the stress measures and the domains of cognitive function. Perceived stress was associated with worse processing speed, direct and delayed recall, semantic fluency and digit span backwards (range β = -0.10; -0.11; p < 0.01). The subscale perceived helplessness showed negative associations only with processing speed (β = -0.06, p < 0.05) and delayed recall (β = -0.06, p < 0.05), which became nonsignificant after the adjustment for depressive symptoms or sense of mastery. The subscale perceived self-efficacy was significantly associated with better cognitive function, also after adjustment for depressive symptoms or sense of mastery (range β = 0.10; 0.18; p < 0.01). In older adults, especially perceived self-efficacy showed independent associations with a broad range of cognitive functions. Perceived self-efficacy might be an important factor in reducing stress and the prevention of cognitive decline. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

A SAL1 Loss-of-Function Arabidopsis Mutant Exhibits Enhanced Cadmium Tolerance in Association with Alleviation of Endoplasmic Reticulum Stress.

PubMed

Xi, Hongmei; Xu, Hua; Xu, Wenxiu; He, Zhenyan; Xu, Wenzhong; Ma, Mi

2016-06-01

SAL1, as a negative regulator of stress response signaling, has been studied extensively for its role in plant response to environmental stresses. However, the role of SAL1 in cadmium (Cd) stress response and the underlying mechanism is still unclear. Using an Arabidopsis thaliana loss-of-function mutant of SAL1, we assessed Cd resistance and further explored the Cd toxicity mechanism through analysis of the endoplasmic reticulum (ER) stress response. The loss of SAL1 function greatly improved Cd tolerance and significantly attenuated ER stress in Arabidopsis. Exposure to Cd induced an ER stress response in Arabidopsis as evidenced by unconventional splicing of AtbZIP60 and up-regulation of ER stress-responsive genes. Damage caused by Cd was markedly reduced in the ER stress response double mutant bzip28 bzip60 or by application of the ER stress-alleviating chemical agents, tauroursodeoxycholic acid (TUDCA) and 4-phenyl butyric acid (4-PBA), in wild-type plants. The Cd-induced ER stress in Arabidopsis was also alleviated by loss of function of SAL1. These results identified SAL1 as a new component mediating Cd toxicity and established the role of the ER stress response in Cd toxicity. Additionally, the attenuated ER stress in the sal1 mutant might also shed new light on the mechanism of diverse abiotic stress resistance in the SAL1 loss-of-function mutants. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Maternal Parenting Stress and Child Perception of Family Functioning Among Families Affected by HIV.

PubMed

Schulte, Marya T; Armistead, Lisa; Marelich, William D; Payne, Diana L; Goodrum, Nada M; Murphy, Debra A

Mothers living with HIV (MLWH) experience stressors inherent to parenting, often within a context characterized by poverty, stigma, and/or limited social support. Our study assessed the relationship between parenting stress and child perceptions of family functioning in families with MLWH who have healthy school-age children. MLWH and their children (N = 102 pairs) completed measures addressing parenting stress and perceptions of family functioning (i.e., parent-child communication, family routines, and family cohesion). We used covariance structural modeling to evaluate the relationship between these factors, with results showing greater maternal parenting stress associated with poorer family functioning outcomes (reported by both the child and the mother). Findings offer support for the parenting stress-family functioning relationship by providing the child perspective along with the maternal perspective, and point to the need for interventions aimed at minimizing the impact of maternal parenting stress on family functioning. Copyright © 2017 Association of Nurses in AIDS Care. Published by Elsevier Inc. All rights reserved.

Mitigation of stress: new treatment alternatives.

PubMed

Subhani, Ahmad Rauf; Kamel, Nidal; Mohamad Saad, Mohamad Naufal; Nandagopal, Nanda; Kang, Kenneth; Malik, Aamir Saeed

2018-02-01

Complaints of stress are common in modern life. Psychological stress is a major cause of lifestyle-related issues, contributing to poor quality of life. Chronic stress impedes brain function, causing impairment of many executive functions, including working memory, decision making and attentional control. The current study sought to describe newly developed stress mitigation techniques, and their influence on autonomic and endocrine functions. The literature search revealed that the most frequently studied technique for stress mitigation was biofeedback (BFB). However, evidence suggests that neurofeedback (NFB) and noninvasive brain stimulation (NIBS) could potentially provide appropriate approaches. We found that recent studies of BFB methods have typically used measures of heart rate variability, respiration and skin conductance. In contrast, studies of NFB methods have typically utilized neurocomputation techniques employing electroencephalography, functional magnetic resonance imaging and near infrared spectroscopy. NIBS studies have typically utilized transcranial direct current stimulation methods. Mitigation of stress is a challenging but important research target for improving quality of life.

Social stress induces changes in urinary bladder function, bladder NGF content, and generalized bladder inflammation in mice

PubMed Central

Peterson, Abbey; Erickson, Cuixia Shi; Nelson, Mark T.; Vizzard, Margaret A.

2014-01-01

Social stress may play a role in urinary bladder dysfunction in humans, but the underlying mechanisms are unknown. In the present study, we explored changes in bladder function caused by social stress using mouse models of stress and increasing stress. In the stress paradigm, individual submissive FVB mice were exposed to C57BL/6 aggressor mice directly/indirectly for 1 h/day for 2 or 4 wk. Increased stress was induced by continuous, direct/indirect exposure of FVB mice to aggressor mice for 2 wk. Stressed FVB mice exhibited nonvoiding bladder contractions and a decrease in both micturition interval (increased voiding frequency) and bladder capacity compared with control animals. ELISAs demonstrated a significant increase in histamine protein expression with no change in nerve growth factor protein expression in the urinary bladder compared with controls. Unlike stressed mice, mice exposed to an increased stress paradigm exhibited increased bladder capacities and intermicturition intervals (decreased voiding frequency). Both histamine and nerve growth factor protein expression were significantly increased with increased stress compared with control bladders. The change in bladder function from increased voiding frequency to decreased voiding frequency with increased stress intensity suggests that changes in social stress-induced urinary bladder dysfunction are context and duration dependent. In addition, changes in the bladder inflammatory milieu with social stress may be important contributors to changes in urinary bladder function. PMID:25100077

4-Phenylbutyric Acid Reveals Good Beneficial Effects on Vital Organ Function via Anti-Endoplasmic Reticulum Stress in Septic Rats.

PubMed

Liu, Liangming; Wu, Huiling; Zang, JiaTao; Yang, Guangming; Zhu, Yu; Wu, Yue; Chen, Xiangyun; Lan, Dan; Li, Tao

2016-08-01

Sepsis and septic shock are the common complications in ICUs. Vital organ function disorder contributes a critical role in high mortality after severe sepsis or septic shock, in which endoplasmic reticulum stress plays an important role. Whether anti-endoplasmic reticulum stress with 4-phenylbutyric acid is beneficial to sepsis and the underlying mechanisms are not known. Laboratory investigation. State Key Laboratory of Trauma, Burns and Combined Injury. Sprague-Dawley rats. Using cecal ligation and puncture-induced septic shock rats, lipopolysaccharide-treated vascular smooth muscle cells, and cardiomyocytes, effects of 4-phenylbutyric acid on vital organ function and the relationship with endoplasmic reticulum stress and endoplasmic reticulum stress-mediated inflammation, apoptosis, and oxidative stress were observed. Conventional treatment, including fluid resuscitation, vasopressin, and antibiotic, only slightly improved the hemodynamic variable, such as mean arterial blood pressure and cardiac output, and slightly improved the vital organ function and the animal survival of septic shock rats. Supplementation of 4-phenylbutyric acid (5 mg/kg; anti-endoplasmic reticulum stress), especially administered at early stage, significantly improved the hemodynamic variables, vital organ function, such as liver, renal, and intestinal barrier function, and animal survival in septic shock rats. 4-Phenylbutyric acid application inhibited the endoplasmic reticulum stress and endoplasmic reticulum stress-related proteins, such as CCAAT/enhancer-binding protein homologous protein in vital organs, such as heart and superior mesenteric artery after severe sepsis. Further studies showed that 4-phenylbutyric acid inhibited endoplasmic reticulum stress-mediated cytokine release, apoptosis, and oxidative stress via inhibition of nuclear factor-κB, caspase-3 and caspase-9, and increasing glutathione peroxidase and superoxide dismutase expression, respectively. Anti-endoplasmic reticulum stress with 4-phenylbutyric acid is beneficial to septic shock. This beneficial effect of 4-phenylbutyric acid is closely related to the inhibition of endoplasmic reticulum stress-mediated oxidative stress, apoptosis, and cytokine release. This finding provides a potential therapeutic measure for clinical critical conditions, such as severe sepsis.

Magmatism and underplating, a broadband seismic perspective on the Proterozoic tectonics of the Great Falls and Snowbird Tectonic Zones

NASA Astrophysics Data System (ADS)

Chen, Y.; Gu, Y. J.; Dokht, R.; Wang, R.

2017-12-01

The crustal and lithospheric structures beneath the Western Canada Sedimentary Basin (WCSB) and northern Montana contain vital records of the Precambrian tectonic development of Laurentia. In this study, we analyze the broadband seismic data recorded by the USArray and the most complete set of regional seismic networks to date near the WCSB. We adopt an integrated approach to investigate crustal structure and history, based primarily on P-to-S receiver functions but incorporate results from noise correlation functions, finite-frequency tomography and potential field measurements. In comparison with existing regional and global models, our stacked receiver functions show considerable improvements in the resolution of both Moho depth and Vp/Vs ratio. We identify major variations in Moho depth from the WCSB to the adjacent Cordillera. The Moho deepens steeply from 40 km in the Alberta basin to 50 km beneath the foothills, following Airy isostasy, but thermal buoyancy may be responsible for a flat, shallow ( 35 km) Moho to the west of the Rocky Mountain Trench. The Moho depth also increases sharply near the Snowbird Tectonic Zone (STZ), which is consistent with earlier findings from active-source data. Multiple lower crustal phases, a high velocity shallow mantle and elevated Vp/Vs ratios along the westernmost STZ jointly suggest major Proterozoic subduction and magmatism along this collisional boundary. In northern Montana, the Moho deepens along the Great Falls Tectonic Zone (GFTZ), a proposed Proterozoic suture between the Medicine Hat Block and Wyoming craton. This transition occurs near the Little Belt Mountain, which is located south of the Great Falls Shear Zone, an extensive northeast striking fault system characterized by strong potential field gradients. Similar to the STZ, our receiver functions offer new evidence for Proterozoic underplating in the vicinity of the GFTZ. In view of similar rock ages near the collisional boundaries in all parts of northern Montana and the WCSB basement, we conjecture that the Rae, Hearn, Medicine Hat and Wyoming cratons were all active during the Paleoproterozoic era and their interactions, particularly coeval subductions and collisions, are largely responsible for the basement geology beneath western Laurentia.

Exploring the relationship between exposure to technological and gastrointestinal stress and probiotic functional properties of lactobacilli and bifidobacteria.

PubMed

Amund, O D

2016-09-01

Strains of Lactobacillus and Bifidobacterium are considered probiotic because of their associated potential health benefits. Probiotics are commonly administered orally via incorporation into food products. Microorganisms for use as probiotics encounter stress conditions, which include acid, bile, osmotic, oxidative, heat and cold stresses. These can occur during processing and storage and during passage through the gastrointestinal tract, and can affect viability. Probiotic bacteria have to remain viable to confer any health benefits. Therefore, the ability to withstand technological and gastrointestinal stresses is crucial probiotic selection criteria. While the stress tolerance mechanisms of lactobacilli and bifidobacteria are largely understood, the impact of exposure to stressful conditions on the functional properties of surviving probiotic microorganisms is not clear. This review explores the potentially positive and negative relationships between exposure to stress conditions and probiotic functional properties, such as resistance to gastric acid and bile, adhesion and colonization potential, and tolerance to antibiotics. Protective strategies can be employed to combat negative effects of stress on functional properties. However, further research is needed to ascertain synergistic relationships between exposure to stress and probiotic properties.

Regular voluntary exercise cures stress-induced impairment of cognitive function and cell proliferation accompanied by increases in cerebral IGF-1 and GST activity in mice.

PubMed

Nakajima, Sanae; Ohsawa, Ikuroh; Ohta, Shigeo; Ohno, Makoto; Mikami, Toshio

2010-08-25

Chronic stress impairs cognitive function and hippocampal neurogenesis. This impairment is attributed to increases in oxidative stress, which result in the accumulation of lipid peroxide. On the other hand, voluntary exercise enhances cognitive function, hippocampal neurogenesis, and antioxidant capacity in normal animals. However, the effects of voluntary exercise on cognitive function, neurogenesis, and antioxidants in stressed mice are unclear. This study was designed to investigate whether voluntary exercise cures stress-induced impairment of cognitive function accompanied by improvement of hippocampal neurogenesis and increases in antioxidant capacity. Stressed mice were exposed to chronic restraint stress (CRS), which consisted of 12h immobilization daily and feeding in a small cage, for 8 weeks. Exercised mice were allowed free access to a running wheel during their exposure to CRS. At the 6th week, cognitive function was examined using the Morris water maze (MWM) test. Daily voluntary exercise restored stress-induced impairment of cognitive function and the hippocampal cell proliferation of newborn cells but not cell survival. Voluntary exercise increased insulin-like growth factor 1 (IGF-1) protein and mRNA expression in the cerebral cortex and liver, respectively. In addition, CRS resulted in a significant increase in the number of 4-hydrosynonenal (4-HNE)-positive cells in the hippocampal dentate gyrus; whereas, voluntary exercise inhibited it and enhanced glutathione s-transferases (GST) activity in the brain. These findings suggest that voluntary exercise attenuated the stress-induced impairment of cognitive function accompanied by improvement of cell proliferation in the dentate gyrus. This exercise-induced improvement was attributed to exercise-induced enhancement of IGF-1 protein and GST activity in the brain. Copyright 2010 Elsevier B.V. All rights reserved.

Child Behavior Problems, Teacher Executive Functions, and Teacher Stress in Head Start Classrooms.

PubMed

Friedman-Krauss, Allison H; Raver, C Cybele; Neuspiel, Juliana M; Kinsel, John

2014-01-01

The current article explores the relationship between teachers' perceptions of child behavior problems and preschool teacher job stress, as well as the possibility that teachers' executive functions moderate this relationship. Data came from 69 preschool teachers in 31 early childhood classrooms in 4 Head Start centers and were collected using Web-based surveys and Web-based direct assessment tasks. Multilevel models revealed that higher levels of teachers' perceptions of child behavior problems were associated with higher levels of teacher job stress and that higher teacher executive function skills were related to lower job stress. However, findings did not yield evidence for teacher executive functions as a statistical moderator. Many early childhood teachers do not receive sufficient training for handling children's challenging behaviors. Child behavior problems increase a teacher's workload and consequently may contribute to feelings of stress. However, teachers' executive function abilities may enable them to use effective, cognitive-based behavior management and instructional strategies during interactions with students, which may reduce stress. Providing teachers with training on managing challenging behaviors and enhancing executive functions may reduce their stress and facilitate their use of effective classroom practices, which is important for children's school readiness skills and teachers' health.

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.

On the application of quantum transport theory to electron sources.

PubMed

Jensen, Kevin L

2003-01-01

Electron sources (e.g., field emitter arrays, wide band-gap (WBG) semiconductor materials and coatings, carbon nanotubes, etc.) seek to exploit ballistic transport within the vacuum after emission from microfabricated structures. Regardless of kind, all sources strive to minimize the barrier to electron emission by engineering material properties (work function/electron affinity) or physical geometry (field enhancement) of the cathode. The unique capabilities of cold cathodes, such as instant ON/OFF performance, high brightness, high current density, large transconductance to capacitance ratio, cold emission, small size and/or low voltage operation characteristics, commend their use in several advanced devices when physical size, weight, power consumption, beam current, and pulse repletion frequency are important, e.g., RF power amplifier such as traveling wave tubes (TWTs) for radar and communications, electrodynamic tethers for satellite deboost/reboost, and electric propulsion systems such as Hall thrusters for small satellites. The theoretical program described herein is directed towards models to evaluate emission current from electron sources (in particular, emission from WBG and Spindt-type field emitter) in order to assess their utility, capabilities and performance characteristics. Modeling efforts particularly include: band bending, non-linear and resonant (Poole-Frenkel) potentials, the extension of one-dimensional theory to multi-dimensional structures, and emission site statistics due to variations in geometry and the presence of adsorbates. Two particular methodologies, namely, the modified Airy approach and metal-semiconductor statistical hyperbolic/ellipsoidal model, are described in detail in their present stage of development.

The stress-buffering effects of functional social support on ambulatory blood pressure.

PubMed

Bowen, Kimberly S; Uchino, Bert N; Birmingham, Wendy; Carlisle, McKenzie; Smith, Timothy W; Light, Kathleen C

2014-11-01

Social support is a reliable predictor of cardiovascular health. According to the buffering hypothesis, stress is 1 mechanism by which support is able to affect physiological processes. However, most of the experimental evidence for the hypothesis comes from laboratory studies. Ambulatory blood pressure (ABP) protocols examine participants in their natural environment, where they are more likely to encounter personally relevant real-world stressors. Furthermore, prior work shows that examining support by its specific functional components reveals additional independent links to health. The current study aimed to examine the stress-buffering effects of functional social support on ABP. One hundred eighty-eight participants completed a 1-day ABP assessment along with measures of functional social support and both global perceived stress and momentary stress at time of reading. RESULTS indicated main effects for both stress measures. Global support, emotional, tangible, and informational support only moderated the effects of momentary stress, but not global stress, in predicting ABP. Informational support was the most consistent stress-buffering predictor of ABP, predicting both ambulatory systolic and diastolic blood pressure. The predicted values in ABP for informational support achieved health-relevant differences, emphasizing the value of examining functional support beyond global support alone. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Longitudinal and bulk viscosities of Lennard-Jones fluids

NASA Astrophysics Data System (ADS)

Tankeshwar, K.; Pathak, K. N.; Ranganathan, S.

1996-12-01

Expressions for the longitudinal and bulk viscosities have been derived using Green Kubo formulae involving the time integral of the longitudinal and bulk stress autocorrelation functions. The time evolution of stress autocorrelation functions are determined using the Mori formalism and a memory function which is obtained from the Mori equation of motion. The memory function is of hyperbolic secant form and involves two parameters which are related to the microscopic sum rules of the respective autocorrelation function. We have derived expressions for the zeroth-, second-and fourth- order sum rules of the longitudinal and bulk stress autocorrelation functions. These involve static correlation functions up to four particles. The final expressions for these have been put in a form suitable for numerical calculations using low- order decoupling approximations. The numerical results have been obtained for the sum rules of longitudinal and bulk stress autocorrelation functions. These have been used to calculate the longitudinal and bulk viscosities and time evolution of the longitudinal stress autocorrelation function of the Lennard-Jones fluids over wide ranges of densities and temperatures. We have compared our results with the available computer simulation data and found reasonable agreement.

The Influence of Work-Related Chronic Stress on the Regulation of Emotion and on Functional Connectivity in the Brain

PubMed Central

Golkar, Armita; Johansson, Emilia; Kasahara, Maki; Osika, Walter; Perski, Aleksander; Savic, Ivanka

2014-01-01

Despite mounting reports about the negative effects of chronic occupational stress on cognitive and emotional functions, the underlying mechanisms are unknown. Recent findings from structural MRI raise the question whether this condition could be associated with a functional uncoupling of the limbic networks and an impaired modulation of emotional stress. To address this, 40 subjects suffering from burnout symptoms attributed to chronic occupational stress and 70 controls were investigated using resting state functional MRI. The participants' ability to up- regulate, down-regulate, and maintain emotion was evaluated by recording their acoustic startle response while viewing neutral and negatively loaded images. Functional connectivity was calculated from amygdala seed regions, using explorative linear correlation analysis. Stressed subjects were less capable of down-regulating negative emotion, but had normal acoustic startle responses when asked to up-regulate or maintain emotion and when no regulation was required. The functional connectivity between the amygdala and the anterior cingulate cortex correlated with the ability to down-regulate negative emotion. This connectivity was significantly weaker in the burnout group, as was the amygdala connectivity with the dorsolateral prefrontal cortex and the motor cortex, whereas connectivity from the amygdala to the cerebellum and the insular cortex were stronger. In subjects suffering from chronic occupational stress, the functional couplings within the emotion- and stress-processing limbic networks seem to be altered, and associated with a reduced ability to down-regulate the response to emotional stress, providing a biological substrate for a further facilitation of the stress condition. PMID:25184294

A high-throughput virus-induced gene silencing protocol identifies genes involved in multi-stress tolerance

PubMed Central

2013-01-01

Background Understanding the function of a particular gene under various stresses is important for engineering plants for broad-spectrum stress tolerance. Although virus-induced gene silencing (VIGS) has been used to characterize genes involved in abiotic stress tolerance, currently available gene silencing and stress imposition methodology at the whole plant level is not suitable for high-throughput functional analyses of genes. This demands a robust and reliable methodology for characterizing genes involved in abiotic and multi-stress tolerance. Results Our methodology employs VIGS-based gene silencing in leaf disks combined with simple stress imposition and effect quantification methodologies for easy and faster characterization of genes involved in abiotic and multi-stress tolerance. By subjecting leaf disks from gene-silenced plants to various abiotic stresses and inoculating silenced plants with various pathogens, we show the involvement of several genes for multi-stress tolerance. In addition, we demonstrate that VIGS can be used to characterize genes involved in thermotolerance. Our results also showed the functional relevance of NtEDS1 in abiotic stress, NbRBX1 and NbCTR1 in oxidative stress; NtRAR1 and NtNPR1 in salinity stress; NbSOS1 and NbHSP101 in biotic stress; and NtEDS1, NbETR1, NbWRKY2 and NbMYC2 in thermotolerance. Conclusions In addition to widening the application of VIGS, we developed a robust, easy and high-throughput methodology for functional characterization of genes involved in multi-stress tolerance. PMID:24289810

Role stress, role reward, and mental health in a multiethnic sample of midlife women: results from the Study of Women's Health Across the Nation (SWAN).

PubMed

Lanza di Scalea, Teresa; Matthews, Karen A; Avis, Nancy E; Thurston, Rebecca C; Brown, Charlotte; Harlow, Sioban; Bromberger, Joyce T

2012-05-01

Little is known about the independent associations of reward and stress within specific roles with multiple measures of mental health in an ethnically diverse community sample of midlife women. The objective of this study is to examine if (1) role reward (within each role and across roles) contributes directly to mental health and buffers the negative impact of role stress and (2) associations among role occupancy, role stress, and role reward and mental health vary by race/ethnicity. With separate logistic regression analysis, we investigated cross-sectional relationships between role stress and role reward with presence/absence of high depressive symptoms (Center for Epidemiologic Studies Depression Scale [CES-D≥16]), anxiety symptoms (feeling tense or nervous, irritable or grouchy, fearful for no reason, and heart pounding or racing total score≥4), or low social functioning (bottom 25th percentile of the Short-Form-36 [SF-36] social functioning subscale) in 2549 women participating in the third visit of the Study of Women's Health Across the Nation (SWAN), a longitudinal population-based study of menopause. High reward across roles attenuated the negative impact of role stress on social functioning but not on anxiety or depression. High reward marriage buffered the impact of marital stress on depression, and high reward mothering buffered the effect of maternal stress on depression and social functioning. Compared to Caucasians, Hispanics and Chinese with high stress across roles had better social functioning, and African American mothers had lower odds of high depressive symptoms. Role reward buffers the negative impact of stress on social functioning and depression, but not on anxiety. Minorities may respond to role stress by seeking social support.

Role Stress, Role Reward, and Mental Health in a Multiethnic Sample of Midlife Women: Results from the Study of Women's Health Across the Nation (SWAN)

PubMed Central

Lanza di Scalea, Teresa; Matthews, Karen A.; Avis, Nancy E.; Thurston, Rebecca C.; Brown, Charlotte; Harlow, Sioban

2012-01-01

Abstract Background Little is known about the independent associations of reward and stress within specific roles with multiple measures of mental health in an ethnically diverse community sample of midlife women. The objective of this study is to examine if (1) role reward (within each role and across roles) contributes directly to mental health and buffers the negative impact of role stress and (2) associations among role occupancy, role stress, and role reward and mental health vary by race/ethnicity. Methods With separate logistic regression analysis, we investigated cross-sectional relationships between role stress and role reward with presence/absence of high depressive symptoms (Center for Epidemiologic Studies Depression Scale [CES-D≥16]), anxiety symptoms (feeling tense or nervous, irritable or grouchy, fearful for no reason, and heart pounding or racing total score≥4), or low social functioning (bottom 25th percentile of the Short-Form-36 [SF-36] social functioning subscale) in 2549 women participating in the third visit of the Study of Women's Health Across the Nation (SWAN), a longitudinal population-based study of menopause. Results High reward across roles attenuated the negative impact of role stress on social functioning but not on anxiety or depression. High reward marriage buffered the impact of marital stress on depression, and high reward mothering buffered the effect of maternal stress on depression and social functioning. Compared to Caucasians, Hispanics and Chinese with high stress across roles had better social functioning, and African American mothers had lower odds of high depressive symptoms. Conclusions Role reward buffers the negative impact of stress on social functioning and depression, but not on anxiety. Minorities may respond to role stress by seeking social support. PMID:22360697

Stress, Communication, and Marital Quality in Couples

ERIC Educational Resources Information Center

Ledermann, Thomas; Bodenmann, Guy; Rudaz, Myriam; Bradbury, Thomas N.

2010-01-01

The association between daily stress outside and inside of the relationship and marital functioning in the form of communication in conflict situations and marital quality was examined. We hypothesized that relationship stress mediates the association between external stress and marital functioning at the individual level, and that the association…

Psychological Stress and Mitochondria: A Systematic Review.

PubMed

Picard, Martin; McEwen, Bruce S

Mitochondria are multifunctional life-sustaining organelles that represent a potential intersection point between psychosocial experiences and biological stress responses. This article provides a systematic review of the effects of psychological stress on mitochondrial structure and function. A systematic review of the literature investigating the effects of psychological stress on mitochondrial function was conducted. The review focused on experimentally controlled studies allowing us to draw causal inference about the effect of induced psychological stress on mitochondria. A total of 23 studies met the inclusion criteria. All studies involved male laboratory animals, and most demonstrated that acute and chronic stressors influenced specific facets of mitochondrial function, particularly within the brain. Nineteen studies showed significant adverse effects of psychological stress on mitochondria and four found increases in function or size after stress. In humans, only six observational studies were available, none with experimental designs, and most only measured biological markers that do not directly reflect mitochondrial function, such as mitochondrial DNA copy number. Overall, evidence supports the notion that acute and chronic stressors influence various aspects of mitochondrial biology, and that chronic stress exposure can lead to molecular and functional recalibrations among mitochondria. Limitations of current animal and human studies are discussed. Maladaptive mitochondrial changes that characterize this subcellular state of stress are termed mitochondrial allostatic load. Prospective studies with sensitive measures of specific mitochondrial outcomes will be needed to establish the link between psychosocial stressors, emotional states, the resulting neuroendocrine and immune processes, and mitochondrial energetics relevant to mind-body research in humans.

Adapting to stress - chaperome networks in cancer.

PubMed

Joshi, Suhasini; Wang, Tai; Araujo, Thaís L S; Sharma, Sahil; Brodsky, Jeffrey L; Chiosis, Gabriela

2018-05-23

In this Opinion article, we aim to address how cells adapt to stress and the repercussions chronic stress has on cellular function. We consider acute and chronic stress-induced changes at the cellular level, with a focus on a regulator of cellular stress, the chaperome, which is a protein assembly that encompasses molecular chaperones, co-chaperones and other co-factors. We discuss how the chaperome takes on distinct functions under conditions of stress that are executed in ways that differ from the one-on-one cyclic, dynamic functions exhibited by distinct molecular chaperones. We argue that through the formation of multimeric stable chaperome complexes, a state of chaperome hyperconnectivity, or networking, is gained. The role of these chaperome networks is to act as multimolecular scaffolds, a particularly important function in cancer, where they increase the efficacy and functional diversity of several cellular processes. We predict that these concepts will change how we develop and implement drugs targeting the chaperome to treat cancer.

Non-invasive Imaging based Detection and Mapping of Brain Oxidative Stress and its Correlation with Cognitive Functions

DTIC Science & Technology

2017-05-14

AFRL-AFOSR-JP-TR-2017-0052 Non-invasive Imaging based Detection and Mapping of Brain Oxidative Stress and its Correlation with Cognative Functions...invasive Imaging based Detection and Mapping of Brain Oxidative Stress and its Correlation with Cognative Functions 5a.  CONTRACT NUMBER 5b.  GRANT...SUPPLEMENTARY NOTES 14. ABSTRACT Brain stress level measurement (non-invasively) in quantitative term is very helpful to correlate with various

Non invasive Imaging based Detection and Mapping of Brain Oxidative Stress and its Correlation with Cognative Functions

DTIC Science & Technology

2017-05-14

AFRL-AFOSR-JP-TR-2017-0052 Non-invasive Imaging based Detection and Mapping of Brain Oxidative Stress and its Correlation with Cognative Functions...invasive Imaging based Detection and Mapping of Brain Oxidative Stress and its Correlation with Cognative Functions 5a.  CONTRACT NUMBER 5b.  GRANT...SUPPLEMENTARY NOTES 14. ABSTRACT Brain stress level measurement (non-invasively) in quantitative term is very helpful to correlate with various

Attentional avoidance of fearful facial expressions following early life stress is associated with impaired social functioning.

PubMed

Humphreys, Kathryn L; Kircanski, Katharina; Colich, Natalie L; Gotlib, Ian H

2016-10-01

Early life stress is associated with poorer social functioning. Attentional biases in response to threat-related cues, linked to both early experience and psychopathology, may explain this association. To date, however, no study has examined attentional biases to fearful facial expressions as a function of early life stress or examined these biases as a potential mediator of the relation between early life stress and social problems. In a sample of 154 children (ages 9-13 years) we examined the associations among interpersonal early life stressors (i.e., birth through age 6 years), attentional biases to emotional facial expressions using a dot-probe task, and social functioning on the Child Behavior Checklist. High levels of early life stress were associated with both greater levels of social problems and an attentional bias away from fearful facial expressions, even after accounting for stressors occurring in later childhood. No biases were found for happy or sad facial expressions as a function of early life stress. Finally, attentional biases to fearful faces mediated the association between early life stress and social problems. Attentional avoidance of fearful facial expressions, evidenced by a bias away from these stimuli, may be a developmental response to early adversity and link the experience of early life stress to poorer social functioning. © 2016 Association for Child and Adolescent Mental Health.

Longitudinal Associations Between Parental Bonding, Parenting Stress, and Executive Functioning in Toddlerhood.

PubMed

de Cock, Evi S A; Henrichs, Jens; Klimstra, Theo A; Janneke B M Maas, A; Vreeswijk, Charlotte M J M; Meeus, Wim H J; van Bakel, Hedwig J A

2017-01-01

Early executive functioning is an important predictor for future development of children's cognitive skills and behavioral outcomes. Parenting behavior has proven to be a key environmental determinant of child executive functioning. However, the association of parental affect and cognitions directed to the child with child executive functioning has been understudied. Therefore, in the present study we examine the associations between parental bonding (i.e., the affective tie from parent to child), parenting stress, and child executive functioning. At 26 weeks of pregnancy, and at 6 months and 24 months postpartum the quality of the maternal (N = 335) and paternal (N = 261) bond with the infant was assessed. At 24 months, postnatal parenting stress and child executive functioning were measured by means of parent-report questionnaires. Results indicated that for both mothers and fathers feelings of bonding negatively predicted experienced parenting stress over time. In addition, for both parents a negative indirect effect of bonding on child executive functioning problems was found via experienced parenting stress. These findings indicate the importance of monitoring parents who experience a low level and quality of early parent-child bonding, as this makes them vulnerable to parenting stress, consequently putting their children at risk for developing executive functioning problems.

Regulation of the Adrenal Cortex Function During Stress

NASA Technical Reports Server (NTRS)

Soliman, K. F. A.

1978-01-01

A proposal to study the function of the adrenal gland in the rat during stress is presented. In the proposed project, three different phases of experimentation will be undertaken. The first phase includes establishment of the circadian rhythm of both brain amines and glucocoticoids, under normal conditions and under chronic and acute stressful conditions. The second phase includes the study of the pharmacokinetics of glucocorticoid binding under normal and stress conditions. The third phase includes brain uptake and binding under different experimental conditions. In the outlined experiments brain biogenic amines will be evaluated, adrenal functions will be measured and stress effect on those parameters will be studied. It is hoped that this investigation can explain some of the complex relationships between the brain neurotransmitter and adrenal function.

Sensitivity analysis of hybrid thermoelastic techniques

Treesearch

W.A. Samad; J.M. Considine

2017-01-01

Stress functions have been used as a complementary tool to support experimental techniques, such as thermoelastic stress analysis (TSA) and digital image correlation (DIC), in an effort to evaluate the complete and separate full-field stresses of loaded structures. The need for such coupling between experimental data and stress functions is due to the fact that...

Structural variations in prefrontal cortex mediate the relationship between early childhood stress and spatial working memory

PubMed Central

Hanson, Jamie L.; Chung, Moo K.; Avants, Brian B.; Rudolph, Karen D.; Shirtcliff, Elizabeth A.; Gee, James C.; Davidson, Richard J.; Pollak, Seth D.

2012-01-01

A large corpus of research indicates exposure to stress impairs cognitive abilities, specifically executive functioning dependent on the prefrontal cortex (PFC). We collected structural MRI scans (n=61), well-validated assessments of executive functioning, and detailed interviews assessing stress exposure in humans, to examine whether cumulative life stress affected brain morphometry and one type of executive functioning, spatial working memory, during adolescence—a critical time of brain development and reorganization. Analysis of variations in brain structure revealed that cumulative life stress and spatial working memory were related to smaller volumes in the PFC, specifically prefrontal gray and white matter between the anterior cingulate and the frontal poles. Mediation analyses revealed that individual differences in prefrontal volumes accounted for the association between cumulative life stress and spatial working memory. These results suggest that structural changes in the PFC may serve as a mediating mechanism through which greater cumulative life stress engenders decrements in cognitive functioning. PMID:22674267

Child Behavior Problems, Teacher Executive Functions, and Teacher Stress in Head Start Classrooms

PubMed Central

Friedman-Krauss, Allison H.; Raver, C. Cybele; Neuspiel, Juliana M.; Kinsel, John

2017-01-01

Research Findings The current article explores the relationship between teachers’ perceptions of child behavior problems and preschool teacher job stress, as well as the possibility that teachers’ executive functions moderate this relationship. Data came from 69 preschool teachers in 31 early childhood classrooms in 4 Head Start centers and were collected using Web-based surveys and Web-based direct assessment tasks. Multilevel models revealed that higher levels of teachers’ perceptions of child behavior problems were associated with higher levels of teacher job stress and that higher teacher executive function skills were related to lower job stress. However, findings did not yield evidence for teacher executive functions as a statistical moderator. Practice or Policy Many early childhood teachers do not receive sufficient training for handling children’s challenging behaviors. Child behavior problems increase a teacher’s workload and consequently may contribute to feelings of stress. However, teachers’ executive function abilities may enable them to use effective, cognitive-based behavior management and instructional strategies during interactions with students, which may reduce stress. Providing teachers with training on managing challenging behaviors and enhancing executive functions may reduce their stress and facilitate their use of effective classroom practices, which is important for children’s school readiness skills and teachers’ health. PMID:28596698

Association of social-environmental factors with cognitive function in children with sickle cell disease.

PubMed

Yarboi, Janet; Compas, Bruce E; Brody, Gene H; White, Desiree; Rees Patterson, Jenny; Ziara, Kristen; King, Allison

2017-04-01

The aim of this study was to examine the relationship between cognitive function in pediatric sickle cell disease (SCD) patients and mothers' reports of social-environmental stress, depressive symptoms, and parenting. A total of 65 children with SCD completed comprehensive neuropsychological testing to assess several domains of cognitive functioning, including general intellectual ability, academic achievement, and executive function. Mothers reported on demographics, social-environmental stress, depressive symptoms, and parenting. As predicted, children with SCD significantly underperformed relative to normative data on measures of cognitive function. Associations between maternal social-environmental stress, maternal depressive symptoms, and parenting were mixed. The results show partial support for the hypothesis that greater stress and depressive symptoms and less positive parenting are associated with poorer cognitive function in children with SCD. Linear regression analyses showed that maternal financial stress was the strongest predictor across all domains of cognitive function. The findings replicate and extend past research, reaffirming that children with SCD are at risk for cognitive impairment across multiple domains. Additionally, social-environmental stress, particularly financial strain, is linked to mothers' depressive symptoms and parenting behaviors as well as children's cognitive function. Future studies using direct observations of parenting behaviors are needed. These findings, along with recent research on parenting interventions, may inform the development of concrete, teachable parenting and coping skills to improve cognitive functioning in children with SCD.

Dependence of the atomic level Green-Kubo stress correlation function on wavevector and frequency: molecular dynamics results from a model liquid.

PubMed

Levashov, V A

2014-09-28

We report on a further investigation of a new method that can be used to address vibrational dynamics and propagation of stress waves in liquids. The method is based on the decomposition of the macroscopic Green-Kubo stress correlation function into the atomic level stress correlation functions. This decomposition, as was demonstrated previously for a model liquid studied in molecular dynamics simulations, reveals the presence of stress waves propagating over large distances and a structure that resembles the pair density function. In this paper, by performing the Fourier transforms of the atomic level stress correlation functions, we elucidate how the lifetimes of the stress waves and the ranges of their propagation depend on their frequency, wavevector, and temperature. These results relate frequency and wavevector dependence of the generalized viscosity to the character of propagation of the shear stress waves. In particular, the results suggest that an increase in the value of the frequency dependent viscosity at low frequencies with decrease of temperature is related to the increase in the ranges of propagation of the stress waves of the corresponding low frequencies. We found that the ranges of propagation of the shear stress waves of frequencies less than half of the Einstein frequency extend well beyond the nearest neighbor shell even above the melting temperature. The results also show that the crossover from quasilocalized to propagating behavior occurs at frequencies usually associated with the Boson peak.

Higher cortisol is associated with poorer executive functioning in preschool children: The role of parenting stress, parent coping and quality of daycare

PubMed Central

Wagner, Shannon L.; Cepeda, Ivan; Krieger, Dena; Maggi, Stefania; D’Angiulli, Amedeo; Weinberg, Joanne; Grunau, Ruth E.

2016-01-01

Child executive functions (cognitive flexibility, inhibitory control, working memory) are key to success in school. Cortisol, the primary stress hormone, is known to affect cognition; however, there is limited information about how child cortisol levels, parenting factors and child care context relate to executive functions in young children. The aim of this study was to examine relationships between child cortisol, parenting stress, parent coping, and daycare quality in relation to executive functions in children aged 3–5 years. We hypothesized that (1) poorer executive functioning would be related to higher child cortisol and higher parenting stress, and (2) positive daycare quality and positive parent coping style would buffer the effects of child cortisol and parenting stress on executive functions. A total of 101 children (53 girls, 48 boys, mean age 4.24 years ±0.74) with complete data on all measures were included. Three saliva samples to measure cortisol were collected at the child’s daycare/preschool in one morning. Parents completed the Behavior Rating Inventory of Executive Function – Preschool Version (BRIEF-P), Parenting Stress Index (PSI), and Ways of Coping Questionnaire (WCQ). The Early Childhood Environment Rating Scale – Revised (ECERS-R) was used to measure the quality of daycare. It was found that children with poorer executive functioning had higher levels of salivary cortisol, and their parents reported higher parenting stress. However, parent coping style and quality of daycare did not modulate these relationships. Identifying ways to promote child executive functioning is an important direction for improving school readiness. PMID:26335047

[Formula: see text]Higher cortisol is associated with poorer executive functioning in preschool children: The role of parenting stress, parent coping and quality of daycare.

PubMed

Wagner, Shannon L; Cepeda, Ivan; Krieger, Dena; Maggi, Stefania; D'Angiulli, Amedeo; Weinberg, Joanne; Grunau, Ruth E

2016-01-01

Child executive functions (cognitive flexibility, inhibitory control, working memory) are key to success in school. Cortisol, the primary stress hormone, is known to affect cognition; however, there is limited information about how child cortisol levels, parenting factors and child care context relate to executive functions in young children. The aim of this study was to examine relationships between child cortisol, parenting stress, parent coping, and daycare quality in relation to executive functions in children aged 3-5 years. We hypothesized that (1) poorer executive functioning would be related to higher child cortisol and higher parenting stress, and (2) positive daycare quality and positive parent coping style would buffer the effects of child cortisol and parenting stress on executive functions. A total of 101 children (53 girls, 48 boys, mean age 4.24 years ±0.74) with complete data on all measures were included. Three saliva samples to measure cortisol were collected at the child's daycare/preschool in one morning. Parents completed the Behavior Rating Inventory of Executive Function - Preschool Version (BRIEF-P), Parenting Stress Index (PSI), and Ways of Coping Questionnaire (WCQ). The Early Childhood Environment Rating Scale - Revised (ECERS-R) was used to measure the quality of daycare. It was found that children with poorer executive functioning had higher levels of salivary cortisol, and their parents reported higher parenting stress. However, parent coping style and quality of daycare did not modulate these relationships. Identifying ways to promote child executive functioning is an important direction for improving school readiness.

Curved singular beams for three-dimensional particle manipulation.

PubMed

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.

Research on propagation properties of controllable hollow flat-topped beams in turbulent atmosphere based on ABCD matrix

NASA Astrophysics Data System (ADS)

Liu, Huilong; Lü, Yanfei; Zhang, Jing; Xia, Jing; Pu, Xiaoyun; Dong, Yuan; Li, Shutao; Fu, Xihong; Zhang, Angfeng; Wang, Changjia; Tan, Yong; Zhang, Xihe

2015-01-01

This paper studies the propagation properties of controllable hollow flat-topped beams (CHFBs) in turbulent atmosphere based on ABCD matrix, sets up a propagation model and obtains an analytical expression for the propagation. With the help of numerical simulation, the propagation properties of CHFBs in different parameters are studied. Results indicate that in turbulent atmosphere, with the increase of propagation distance, the darkness of CHFBs gradually annihilate, and eventually evolve into Gaussian beams. Compared with the propagation properties in free space, the turbulent atmosphere enhances the diffraction effect of CHFBs and reduces the propagation distance for CHFBs to evolve into Gaussian beams. In strong turbulence atmospheric propagation, Airy disk phenomenon will disappear. The study on the propagation properties of CHFBs in turbulence atmosphere by using ABCD matrix is simple and convenient. This method can also be applied to study the propagation properties of other hollow laser beams in turbulent atmosphere.

Staircase-scene-based nonuniformity correction in aerial point target detection systems.

PubMed

Huo, Lijun; Zhou, Dabiao; Wang, Dejiang; Liu, Rang; He, Bin

2016-09-01

Focal-plane arrays (FPAs) are often interfered by heavy fixed-pattern noise, which severely degrades the detection rate and increases the false alarms in airborne point target detection systems. Thus, high-precision nonuniformity correction is an essential preprocessing step. In this paper, a new nonuniformity correction method is proposed based on a staircase scene. This correction method can compensate for the nonlinear response of the detector and calibrate the entire optical system with computational efficiency and implementation simplicity. Then, a proof-of-concept point target detection system is established with a long-wave Sofradir FPA. Finally, the local standard deviation of the corrected image and the signal-to-clutter ratio of the Airy disk of a Boeing B738 are measured to evaluate the performance of the proposed nonuniformity correction method. Our experimental results demonstrate that the proposed correction method achieves high-quality corrections.

Bouguer gravity anomaly and isostatic residual gravity maps of the Tonopah 1 degree by 2 degrees Quadrangle, central Nevada

USGS Publications Warehouse

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).

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.

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.

Quantum scattering beyond the plane-wave approximation

NASA Astrophysics Data System (ADS)

Karlovets, Dmitry

2017-12-01

While a plane-wave approximation in high-energy physics works well in a majority of practical cases, it becomes inapplicable for scattering of the vortex particles carrying orbital angular momentum, of Airy beams, of the so-called Schrödinger cat states, and their generalizations. Such quantum states of photons, electrons and neutrons have been generated experimentally in recent years, opening up new perspectives in quantum optics, electron microscopy, particle physics, and so forth. Here we discuss the non-plane-wave effects in scattering brought about by the novel quantum numbers of these wave packets. For the well-focused electrons of intermediate energies, already available at electron microscopes, the corresponding contribution can surpass that of the radiative corrections. Moreover, collisions of the cat-like superpositions of such focused beams with atoms allow one to probe effects of the quantum interference, which have never played any role in particle scattering.

Bending light via adiabatic optical transition in longitudinally modulated photonic lattices

PubMed Central

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

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.

Trapped waves on the mid-latitude β-plane

NASA Astrophysics Data System (ADS)

Paldor, Nathan; Sigalov, Andrey

2008-08-01

A new type of approximate solutions of the Linearized Shallow Water Equations (LSWE) on the mid-latitude β-plane, zonally propagating trapped waves with Airy-like latitude-dependent amplitude, is constructed in this work, for sufficiently small radius of deformation. In contrast to harmonic Poincare and Rossby waves, these newly found trapped waves vanish fast in the positive half-axis, and their zonal phase speed is larger than that of the corresponding harmonic waves for sufficiently large meridional domains. Our analysis implies that due to the smaller radius of deformation in the ocean compared with that in the atmosphere, the trapped waves are relevant to observations in the ocean whereas harmonic waves typify atmospheric observations. The increase in the zonal phase speed of trapped Rossby waves compared with that of harmonic ones is consistent with recent observations that showed that Sea Surface Height features propagated westwards faster than the phase speed of harmonic Rossby waves.

Automated generation of influence functions for planar crack problems

NASA Technical Reports Server (NTRS)

Sire, Robert A.; Harris, David O.; Eason, Ernest D.

1989-01-01

A numerical procedure for the generation of influence functions for Mode I planar problems is described. The resulting influence functions are in a form for convenient evaluation of stress-intensity factors for complex stress distributions. Crack surface displacements are obtained by a least-squares solution of the Williams eigenfunction expansion for displacements in a cracked body. Discrete values of the influence function, evaluated using the crack surface displacements, are curve fit using an assumed functional form. The assumed functional form includes appropriate limit-behavior terms for very deep and very shallow cracks. Continuous representation of the influence function provides a convenient means for evaluating stress-intensity factors for arbitrary stress distributions by numerical integration. The procedure is demonstrated for an edge-cracked strip and a radially cracked disk. Comparisons with available published results demonstrate the accuracy of the procedure.

Correlation range in a supercooled liquid via Green-Kubo expression for viscosity, local atomic stresses, and MD simulations

NASA Astrophysics Data System (ADS)

Levashov, Valentin A.; Egami, Takeshi; Morris, James R.

2009-03-01

We present a new approach to the issue of correlation range in supercooled liquids based on Green-Kubo expression for viscosity. The integrand of this expression is the average stress-stress autocorrelation function. This correlation function could be rewritten in terms of correlations among local atomic stresses at different times and distances. The features of the autocorrelation function decay with time depend on temperature and correlation range. Through this approach we can study the development of spatial correlation with time, thus directly addressing the question of dynamic heterogeneity. We performed MD simulations on a single component system of particles interacting through short range pair potential. Our results indicate that even above the crossover temperature correlations extend well beyond the nearest neighbors. Surprisingly we found that the system size effects exist even on relatively large systems. We also address the role of diffusion in decay of stress-stress correlation function.

TaUBA, a UBA domain-containing protein in wheat (Triticum aestivum L.), is a negative regulator of salt and drought stress response in transgenic Arabidopsis.

PubMed

Li, Xiao; Zhang, Shuang-shuang; Ma, Jun-xia; Guo, Guang-yan; Zhang, Xue-yong; Liu, Xu; Bi, Cai-li

2015-05-01

TaUBA functions as a negative regulator of salt and drought stress response in transgenic Arabidopsis, either the UBA domain or the zinc finger domain is crucial for TaUBA's function. TaUBA (DQ211935), which is a UBA domain-containing protein in wheat, was cloned and functionally characterized. Southern blot suggested that TaUBA is a low copy gene in common wheat. qRT-PCR assay showed that the expression of TaUBA was strongly induced by salt and drought stress. When suffering from drought and salt stresses, lower proline content and much higher MDA content in the TaUBA overexpressors were observed than those of the wild-type control, suggesting TaUBA may function as a negative regulator of salt and drought stress response in plants. To study whether the UBA domain or the zinc finger domain affects the function of TaUBA, TaUBAΔUBA (deletion of UBA domain) and TaUBA-M (Cys464Gly and Cys467Gly) overexpression vectors were constructed and transformed into Arabidopsis. Upon drought and salt stresses, the TaUBAΔUBA-and TaUBA-M-overexpressed plants accumulated much more proline and lower MDA than the wild-type control, the TaUBA-overexpressors lost water more quickly than TaUBAΔUBA-and TaUBA-M-overexpressed plants as well as the wild-type control, suggesting that overexpression of TaUBAΔUBA or TaUBA-M improved the drought and salt tolerance of transgenic Arabidopsis plants and the possibility of ubiquitination role in the regulation of osmolyte synthesis and oxidative stress responses in mediating stress tolerance. qRT-PCR assay of stress-related genes in transgenic plants upon drought and salt stresses suggested that TaUBA may function through down-regulating some stress related-transcription factors and by regulating P5CSs to cope with osmotic stress.

Anisotropy of stress correlation in two-dimensional liquids and a pseudospin model

DOE PAGES

Wu, Bin; Iwashita, Takuya; Egami, Takeshi

2015-11-04

Liquids are condensed matter in which atoms are strongly correlated in position and momentum. The atomic pair density function (PDF) is used often in describing such correlation. However, elucidation of many properties requires higher degrees of correlation than the pair correlation. For instance, viscosity depends upon the stress correlations in space and time. We examine the cross correlation between the stress correlation at the atomic level and the PDF for two-dimensional liquids. We introduce the concept of the stress-resolved pair distribution function (SRPDF) that uses the sign of atomic-level stress as a selection rule to include particles from density correlations.more » The connection between SRPDFs and stress correlation function is explained through an approximation in which the shear stress is replaced by a pseudospin. Lastly, we further assess the possibility of interpreting the long-range stress correlation as a consequence of short-range Ising-like pseudospin interactions.« less

Prenatal stress alters amygdala functional connectivity in preterm neonates.

PubMed

Scheinost, Dustin; Kwon, Soo Hyun; Lacadie, Cheryl; Sze, Gordon; Sinha, Rajita; Constable, R Todd; Ment, Laura R

2016-01-01

Exposure to prenatal and early-life stress results in alterations in neural connectivity and an increased risk for neuropsychiatric disorders. In particular, alterations in amygdala connectivity have emerged as a common effect across several recent studies. However, the impact of prenatal stress exposure on the functional organization of the amygdala has yet to be explored in the prematurely-born, a population at high risk for neuropsychiatric disorders. We test the hypothesis that preterm birth and prenatal exposure to maternal stress alter functional connectivity of the amygdala using two independent cohorts. The first cohort is used to establish the effects of preterm birth and consists of 12 very preterm neonates and 25 term controls, all without prenatal stress exposure. The second is analyzed to establish the effects of prenatal stress exposure and consists of 16 extremely preterm neonates with prenatal stress exposure and 10 extremely preterm neonates with no known prenatal stress exposure. Standard resting-state functional magnetic resonance imaging and seed connectivity methods are used. When compared to term controls, very preterm neonates show significantly reduced connectivity between the amygdala and the thalamus, the hypothalamus, the brainstem, and the insula (p < 0.05). Similarly, when compared to extremely preterm neonates without exposure to prenatal stress, extremely preterm neonates with exposure to prenatal stress show significantly less connectivity between the left amygdala and the thalamus, the hypothalamus, and the peristriate cortex (p < 0.05). Exploratory analysis of the combined cohorts suggests additive effects of prenatal stress on alterations in amygdala connectivity associated with preterm birth. Functional connectivity from the amygdala to other subcortical regions is decreased in preterm neonates compared to term controls. In addition, these data, for the first time, suggest that prenatal stress exposure amplifies these decreases.

Disruption of Fatty Acid Amide Hydrolase Activity Prevents the Effects of Chronic Stress on Anxiety and Amygdalar Microstructure

PubMed Central

Hill, Matthew N.; Kumar, Shobha Anil; Filipski, Sarah B.; Iverson, Moriah; Stuhr, Kara L.; Keith, John M.; Cravatt, Benjamin F.; Hillard, Cecilia J.; Chattarji, Sumantra; McEwen, Bruce S.

2014-01-01

Hyperactivation of the amygdala following chronic stress is believed to be one of the primary mechanisms underlying the increased propensity for anxiety-like behaviors and pathological states; however, the mechanisms by which chronic stress modulates amygdalar function are not well characterized. The aim of the current study was to determine the extent to which the endocannabinoid system, which is known to regulate emotional behavior and neuroplasticity, contributes to changes in amygdalar structure and function following chronic stress. To examine the hypothesis, we have exposed C57/Bl6 mice to chronic restraint stress which results in an increase in fatty acid amide hydrolase (FAAH) activity and a reduction in the concentration of the endocannabinoid N-arachidonylethanolamine (AEA) within the amygdala. Chronic restraint stress also increased dendritic arborization, complexity and spine density of pyramidal neurons in the basolateral nucleus of the amygdala (BLA) and increased anxiety-like behavior in wild-type mice. All of the stress-induced changes in amygdalar structure and function were absent in mice deficient in FAAH. Further, the anti-anxiety effect of FAAH deletion was recapitulated in rats treated orally with a novel pharmacological inhibitor of FAAH, JNJ5003 (50 mg/kg/day), during exposure to chronic stress. These studies suggest that FAAH is required for chronic stress to induce hyperactivity and structural remodeling of the amygdala. Collectively, these studies indicate that FAAH-mediated decreases in AEA occur following chronic stress and that this loss of AEA signaling is functionally relevant to the effects of chronic stress. These data support the hypothesis that inhibition of FAAH has therapeutic potential in the treatment of anxiety disorders, possibly by maintaining normal amygdalar function in the face of chronic stress. PMID:22776900

Effects of work stress and home stress on autonomic nervous function in Japanese male workers

PubMed Central

MAEDA, Eri; IWATA, Toyoto; MURATA, Katsuyuki

2014-01-01

Autonomic imbalance is one of the important pathways through which psychological stress contributes to cardiovascular diseases/sudden death. Although previous studies have focused mainly on stress at work (work stress), the association between autonomic function and stress at home (home stress) is still poorly understood. The purpose was to clarify the effect of work/home stress on autonomic function in 1,809 Japanese male workers. We measured corrected QT (QTc) interval and QT index on the electrocardiogram along with blood pressure and heart rate. Participants provided self-reported information about the presence/absence of work/home stress and the possible confounders affecting QT indicators. Home stress was related positively to QT index (p=0.040) after adjusting for the possible confounders, though work stress did not show a significant relation to QTc interval or QT index. The odds ratio of home stress to elevated QT index (≥105) was 2.677 (95% CI, 1.050 to 6.822). Work/home stress showed no significant relation to blood pressure or heart rate. These findings suggest that autonomic imbalance, readily assessed by QT indicators, can be induced by home stress in Japanese workers. Additional research is needed to identify different types of home stress that are strongly associated with autonomic imbalance. PMID:25382383

Effects of work stress and home stress on autonomic nervous function in Japanese male workers.

PubMed

Maeda, Eri; Iwata, Toyoto; Murata, Katsuyuki

2015-01-01

Autonomic imbalance is one of the important pathways through which psychological stress contributes to cardiovascular diseases/sudden death. Although previous studies have focused mainly on stress at work (work stress), the association between autonomic function and stress at home (home stress) is still poorly understood. The purpose was to clarify the effect of work/home stress on autonomic function in 1,809 Japanese male workers. We measured corrected QT (QTc) interval and QT index on the electrocardiogram along with blood pressure and heart rate. Participants provided self-reported information about the presence/absence of work/home stress and the possible confounders affecting QT indicators. Home stress was related positively to QT index (p=0.040) after adjusting for the possible confounders, though work stress did not show a significant relation to QTc interval or QT index. The odds ratio of home stress to elevated QT index (≥105) was 2.677 (95% CI, 1.050 to 6.822). Work/home stress showed no significant relation to blood pressure or heart rate. These findings suggest that autonomic imbalance, readily assessed by QT indicators, can be induced by home stress in Japanese workers. Additional research is needed to identify different types of home stress that are strongly associated with autonomic imbalance.

Chronic stress and neural function: accounting for sex and age.

PubMed

Luine, V N; Beck, K D; Bowman, R E; Frankfurt, M; Maclusky, N J

2007-10-01

Cognitive responses to stress follow the temporally dependent pattern originally established by Selye (1) wherein short-term stressors elicit adaptive responses whereas continued stress (chronic) results in maladaptive changes--deleterious effects on physiological systems and impaired cognition. However, this pattern for cognitive effects appears to apply to only half the population (males) and, more specifically, to young, adult males. Females show different cognitive responses to stress. In contrast to impaired cognition in males after chronic stress, female rodents show enhanced performance on the same memory tasks after the same stress. Not only cognition, but anxiety, shows sex-dependent changes following chronic stress--stress is anxiolytic in males and anxiogenic in females. Moreover, behavioral responses to chronic stress are different in developing as well as aging subjects (both sexes) as compared to adults. In aged rats, chronic stress enhances recognition memory in both sexes, does not alter spatial memory, and anxiety effects are opposite to young adults. When pregnant dams are exposed to chronic stress, at adulthood the offspring display yet different consequences of stress on anxiety and cognition, and, in contrast to adulthood when the behavioral effects of stress are reversible, prenatal stress effects appear enduring. Changing levels of estradiol in the sexes over the lifespan appear to contribute to the differences in response to stress. Thus, theories of stress dependent modulations in CNS function--developed solely in male models, focused on peripheral physiological processes and tested in adults--may require revision when applied to a more diverse population (age- and sex-wise) at least in relation to the neural functions of cognition and anxiety. Moreover, these results suggest that other stressors and neural functions should be investigated to determine whether age, sex and gonadal hormones also have an impact.

Longitudinal Effects of Latino Parent Cultural Stress, Depressive Symptoms, and Family Functioning on Youth Emotional Well-Being and Health Risk Behaviors.

PubMed

Lorenzo-Blanco, Elma I; Meca, Alan; Unger, Jennifer B; Romero, Andrea; Szapocznik, José; Piña-Watson, Brandy; Cano, Miguel Ángel; Zamboanga, Byron L; Baezconde-Garbanati, Lourdes; Des Rosiers, Sabrina E; Soto, Daniel W; Villamar, Juan A; Lizzi, Karina M; Pattarroyo, Monica; Schwartz, Seth J

2017-12-01

U.S. Latino parents can face cultural stressors in the form of acculturative stress, perceived discrimination, and a negative context of reception. It stands to reason that these cultural stressors may negatively impact Latino youth's emotional well-being and health risk behaviors by increasing parents' depressive symptoms and compromising the overall functioning of the family. To test this possibility, we analyzed data from a six-wave longitudinal study with 302 recently immigrated (<5 years in the United States) Latino parents (74% mothers, M age  = 41.09 years) and their adolescent children (47% female, M age  = 14.51 years). Results of a cross-lagged analysis indicated that parent cultural stress predicted greater parent depressive symptoms (and not vice versa). Both parent cultural stress and depressive symptoms, in turn, predicted lower parent-reported family functioning, which mediated the links from parent cultural stress and depressive symptoms to youth alcohol and cigarette use. Parent cultural stress also predicted lower youth-reported family functioning, which mediated the link from parent cultural stress to youth self-esteem. Finally, mediation analyses indicated that parent cultural stress predicted youth alcohol use by a way of parent depressive symptoms and parent-reported family functioning. Our findings point to parent depressive symptoms and family functioning as key mediators in the links from parent cultural stress to youth emotional well-being and health risk behaviors. We discuss implications for research and preventive interventions. © 2016 Family Process Institute.

A molecular web: endoplasmic reticulum stress, inflammation, and oxidative stress.

PubMed

Chaudhari, Namrata; Talwar, Priti; Parimisetty, Avinash; Lefebvre d'Hellencourt, Christian; Ravanan, Palaniyandi

2014-01-01

Execution of fundamental cellular functions demands regulated protein folding homeostasis. Endoplasmic reticulum (ER) is an active organelle existing to implement this function by folding and modifying secretory and membrane proteins. Loss of protein folding homeostasis is central to various diseases and budding evidences suggest ER stress as being a major contributor in the development or pathology of a diseased state besides other cellular stresses. The trigger for diseases may be diverse but, inflammation and/or ER stress may be basic mechanisms increasing the severity or complicating the condition of the disease. Chronic ER stress and activation of the unfolded-protein response (UPR) through endogenous or exogenous insults may result in impaired calcium and redox homeostasis, oxidative stress via protein overload thereby also influencing vital mitochondrial functions. Calcium released from the ER augments the production of mitochondrial Reactive Oxygen Species (ROS). Toxic accumulation of ROS within ER and mitochondria disturbs fundamental organelle functions. Sustained ER stress is known to potentially elicit inflammatory responses via UPR pathways. Additionally, ROS generated through inflammation or mitochondrial dysfunction could accelerate ER malfunction. Dysfunctional UPR pathways have been associated with a wide range of diseases including several neurodegenerative diseases, stroke, metabolic disorders, cancer, inflammatory disease, diabetes mellitus, cardiovascular disease, and others. In this review, we have discussed the UPR signaling pathways, and networking between ER stress-induced inflammatory pathways, oxidative stress, and mitochondrial signaling events, which further induce or exacerbate ER stress.

Stress responding in cannabis smokers as a function of trauma exposure, sex, and relapse in the human laboratory.

PubMed

Chao, Thomas; Radoncic, Vanya; Hien, Denise; Bedi, Gillinder; Haney, Margaret

2018-04-01

Stress responding is linked to drug use, but little is known about stress responses in cannabis smokers. We investigated acute stress responding in cannabis smokers as a function of trauma exposure and sex, and relationships between stress responses and cannabis relapse. 125 healthy, non-treatment-seeking daily cannabis smokers (23F, 102 M) completed the Trier Social Stress Task (TSST), a standardized laboratory stressor; subsets also completed a trauma questionnaire (n = 106) and a laboratory cannabis relapse measure (n = 54). Stress responding was assessed with heart rate (HR), salivary cortisol (CORT), and self-rated mood. Cannabis smokers reporting at least one trauma exposure had higher CORT and anxiety overall compared to those reporting no trauma. Stress responding did not differ as a function of binary trauma exposure, although total number of exposures correlated positively with CORT and anxiety during stress. Females reported increased nervousness after stress relative to males matched to the females for cannabis and cigarette use. An interactive effect of sex and trauma on HR suggested that females with trauma exposure have increased cardiovascular stress responding relative to those without such exposure, with no differential effect in males. Stress responding did not predict laboratory cannabis relapse. We report differences in acute stress responding as a function of trauma, sex, and their interaction in a large sample of relatively homogenous cannabis smokers. Further investigation of how trauma impacts stress responding in male and female cannabis smokers, and how this relates to different aspects of cannabis use, is warranted. Copyright © 2018 Elsevier B.V. All rights reserved.

Evaluation of a functional medicine approach to treating fatigue, stress, and digestive issues in women.

PubMed

Cutshall, Susanne M; Bergstrom, Larry R; Kalish, Daniel J

2016-05-01

Fatigue, stress, and digestive disorders are common among adults, especially women. We conducted a 28-week pilot study to assess the efficacy of a functional medicine approach to improving stress, energy, fatigue, digestive issues, and quality of life in middle-aged women. Findings showed significant improvements in many stress, fatigue, and quality-of-life measures. The treatment program increased mean salivary dehydroepiandrosterone levels and the cortisol-dehydroepiandrosterone ratio. Stool sample analyses suggested that these treatments reduced Helicobacter pylori infections. This study suggests that functional medicine may be an effective approach to managing stress and gastrointestinal symptoms. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Role of Family Functioning in the Stress Process of Dementia Caregivers: A Structural Family Framework

ERIC Educational Resources Information Center

Mitrani, Victoria B.; Lewis, John E.; Feaster, Daniel J.; Czaja, Sara J.; Eisdorfer, Carl; Schulz, Richard; Szapocznik, Jose

2006-01-01

Purpose: The purpose of the study was to evaluate the role of family functioning in the stress process in a sample of caregivers of dementia patients by using a structural family framework. The stress-process model of caregiver distress included family functioning as an intervening variable in the relationship between objective burden and…

Life stress vs. traumatic stress: The impact of life events on psychological functioning in children with and without serious illness

PubMed Central

Willard, Victoria W.; Long, Alanna; Phipps, Sean

2014-01-01

Objective To determine the differential impact of potentially traumatic events (PTEs) and other stressful life events on psychological functioning in two groups of children: those with cancer, and those without history of serious illness. Methods Children with cancer aged 8–17 (n=254) and age-, sex-, and race/ethnicity-matched controls (n=142) completed self-report measures of stressful life events, and psychological functioning. Stressful life events included those that may meet DSM-IV A1 criteria (PTEs; 9 events) and others that would likely not (other events; 21 events). Results Children with cancer endorsed significantly more PTEs than control children. There were no differences between groups in number of other events experienced. Hierarchical regression analyses revealed that number of other events accounted for significant variance in psychological functioning, above and beyond group status, demographic factors (age and SES) and number of PTEs. Discussion The number of cumulative other events experienced is a significant predictor of psychological functioning in both youth with serious illness and controls. In contrast, cumulative PTEs appear to have a minor (albeit significant) impact on children’s psychological functioning. Assessment of psychological functioning would benefit from a thorough history of stressful life events, regardless of their potential traumatic impact. PMID:26766295

NK cell recruitment and exercise: Potential immunotherapeutic role of shear stress and endothelial health.

PubMed

Evans, William

2017-11-01

Positive cancer patient outcomes, including increased time to recurrent events, have been associated with increased counts and function of natural killer (NK) cells. NK cell counts and function are elevated following acute exercise, and the generally accepted mechanism of increased recruitment suggests that binding of epinephrine releases NK cells from endothelial tissue via decreases in adhesion molecules following. I propose that blood flow-induced shear stress may also play a role in NK cell recruitment from the endothelium. Additionally, shear stress may play a role in improving NK cell function by decreasing oxidative stress. The relationship between shear stress and NK cell count and function can be tested by utilizing exercise and local heating with cuff inflation. If shear stress does play an important role, NK cell count and function will be improved in the non-cuffed exercise group, but not the cuffed limb. This paper will explore the mechanisms potentially explaining exercise-induced improvements in NK cell count and function, and propose a model for investigating these mechanisms. This mechanistic insight could aid in providing a novel, safe, relatively inexpensive, and non-invasive target for immunotherapy in cancer patients. Copyright © 2017. Published by Elsevier Ltd.

A degradation function consistent with Cocks–Ashby porosity kinetics

DOE PAGES

Moore, John A.

2017-10-14

Here, the load carrying capacity of ductile materials degrades as a function of porosity, stress state and strain-rate. The effect of these variables on porosity kinetics is captured by the Cocks–Ashby model; however, the Cocks–Ashby model does not account for material degradation directly. This work uses a yield criteria to form a degradation function that is consistent with Cocks–Ashby porosity kinetics and is a function of porosity, stress state and strain-rate dependence. Approximations of this degradation function for pure hydrostatic stress states are also explored.

A degradation function consistent with Cocks–Ashby porosity kinetics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, John A.

Here, the load carrying capacity of ductile materials degrades as a function of porosity, stress state and strain-rate. The effect of these variables on porosity kinetics is captured by the Cocks–Ashby model; however, the Cocks–Ashby model does not account for material degradation directly. This work uses a yield criteria to form a degradation function that is consistent with Cocks–Ashby porosity kinetics and is a function of porosity, stress state and strain-rate dependence. Approximations of this degradation function for pure hydrostatic stress states are also explored.

Function and Innervation of the Locus Ceruleus in a Macaque Model of Functional Hypothalamic Amenorrhea

PubMed Central

Bethea, Cynthia L; Kim, Aaron; Cameron, Judy L

2012-01-01

A body of knowledge implicates an increase in output from the locus ceruleus (LC) during stress. We questioned the innervation and function of the LC in our macaque model of Functional Hypothalamic Amenorrhea, also known as Stress-Induced Amenorrhea. Cohorts of macaques were initially characterized as highly stress resilient (HSR) or stress-sensitive (SS) based upon the presence or absence of ovulation during a protocol involving 2 menstrual cycles with psychosocial and metabolic stress. Afterwards, the animals were rested until normal menstrual cycles resumed and then euthanized on day 5 of a new menstrual cycle [a] in the absence of further stress; or [b] after 5 days of resumed psychosocial and metabolic stress. In this study, parameters of the LC were examined in HSR and SS animals in the presence and absence of stress (2 x 2 block design) using ICC and image analysis. Tyrosine hydroxylase (TH) is the rate-limiting enzyme for the synthesis of catecholamines; and the TH level was used to assess by inference, NE output. The pixel area of TH-positive dendrites extending outside the medial border of the LC was significantly increased by stress to a similar degree in both HSR and SS animals (p<0.0001). There is a significant CRF innervation of the LC. The positive pixel area of CRF boutons, lateral to the LC, was higher in SS than HSR animals in the absence of stress. Five days of moderate stress significantly increased the CRF-positive bouton pixel area in the HSR group (p<0.02), but not in the SS group. There is also a significant serotonin innervation of the LC. A marked increase in medial serotonin dendrite swelling and beading was observed in the SS + stress group, which may be a consequence of excitotoxicity. The dendrite beading interfered with analysis of axonal boutons. However, at one anatomical level, the serotonin-positive bouton area was obtained between the LC and the superior cerebellar peduncle. Serotonin-positive bouton pixel area was significantly higher in HSR than SS animals (p<0.04). There was no change in either group after 5 days of moderate stress. The ratio of serotonin/TH correlates with ovarian estrogen production with a sensitivity x stress interaction. Therefore, it appears that the serotonin system determines stress sensitivity and the NE system responds to stress. We hypothesize that elevated NE with low serotonin functionality ultimately leads to stress-induced infertililty. In contrast, high serotonin functionality maintains ovulation in the presence of stress even with elevated NE. PMID:23069677

Function and innervation of the locus ceruleus in a macaque model of Functional Hypothalamic Amenorrhea.

PubMed

Bethea, Cynthia L; Kim, Aaron; Cameron, Judy L

2013-02-01

A body of knowledge implicates an increase in output from the locus ceruleus (LC) during stress. We questioned the innervation and function of the LC in our macaque model of Functional Hypothalamic Amenorrhea, also known as Stress-Induced Amenorrhea. Cohorts of macaques were initially characterized as highly stress resilient (HSR) or stress-sensitive (SS) based upon the presence or absence of ovulation during a protocol involving 2 menstrual cycles with psychosocial and metabolic stress. Afterwards, the animals were rested until normal menstrual cycles resumed and then euthanized on day 5 of a new menstrual cycle [a] in the absence of further stress; or [b] after 5 days of resumed psychosocial and metabolic stress. In this study, parameters of the LC were examined in HSR and SS animals in the presence and absence of stress (2×2 block design) using ICC and image analysis. Tyrosine hydroxylase (TH) is the rate-limiting enzyme for the synthesis of catecholamines; and the TH level was used to assess by inference, NE output. The pixel area of TH-positive dendrites extending outside the medial border of the LC was significantly increased by stress to a similar degree in both HSR and SS animals (p<0.0001). There is a significant CRF innervation of the LC. The positive pixel area of CRF boutons, lateral to the LC, was higher in SS than HSR animals in the absence of stress. Five days of moderate stress significantly increased the CRF-positive bouton pixel area in the HSR group (p<0.02), but not in the SS group. There is also a significant serotonin innervation of the LC. A marked increase in medial serotonin dendrite swelling and beading was observed in the SS+stress group, which may be a consequence of excitotoxicity. The dendrite beading interfered with analysis of axonal boutons. However, at one anatomical level, the serotonin-positive bouton area was obtained between the LC and the superior cerebellar peduncle. Serotonin-positive bouton pixel area was significantly higher in HSR than SS animals (p<0.04). There was no change in either group after 5 days of moderate stress. The ratio of serotonin/TH correlates with ovarian estrogen production with a sensitivity×stress interaction. Therefore, it appears that the serotonin system determines stress sensitivity and the NE system responds to stress. We hypothesize that elevated NE with low serotonin functionality ultimately leads to stress-induced infertility. In contrast, high serotonin functionality maintains ovulation in the presence of stress even with elevated NE. Copyright © 2012 Elsevier Inc. All rights reserved.

[Impact of Socioeconomic Risk Exposure on Maternal Sensitivity, Stress and Family Functionality].

PubMed

Sidor, Anna; Köhler, Hubert; Cierpka, Manfred

2018-03-01

Impact of Socioeconomic Risk Exposure on Maternal Sensitivity, Stress and Family Functionality Parental stress exposure can influence the parent-child relationship, child development and child wellbeing in negative ways. The aim of this study was to investigate the impact of socio-economic risk exposure on the quality of the mother-child-interaction and family functionality. A sample of 294 mother-infant dyads at psychosocial risk was compared with a lower-risk, middle-class sample of 125 mother-infant-dyads in regard to maternal sensitivity/child's cooperation (CARE-Index), maternal stress (PSI-SF) and family functionality (FB-K). Lower levels of maternal sensitivity/child's cooperation and by trend also of the family functionality were found among the mothers from the at-risk sample in comparison to the low-risk sample. The level of maternal stress was similar in both samples. The results underpin the negative effects of a socio-economic risk exposure on the mother-child relationship. An early, sensitivity-focused family support could be encouraged to counteract the negative effects of early socioeconomic stress.

Psychological stress-induced cerebrovascular dysfunction: the role of metabolic syndrome and exercise.

PubMed

Brooks, Steven; Brnayan, Kayla W; DeVallance, Evan; Skinner, Roy; Lemaster, Kent; Sheets, J Whitney; Pitzer, Christopher R; Asano, Shinichi; Bryner, Randall W; Olfert, I Mark; Frisbee, Jefferson C; Chantler, Paul D

2018-05-01

What is the central question of this study? How does chronic stress impact cerebrovascular function and does metabolic syndrome accelerate the cerebrovascular adaptations to stress? What role does exercise training have in preventing cerebrovascular changes to stress and metabolic syndrome? What is the main finding and its importance? Stressful conditions lead to pathological adaptations of the cerebrovasculature via an oxidative nitric oxide pathway, and the presence of metabolic syndrome produces a greater susceptibility to stress-induced cerebrovascular dysfunction. The results also provide insight into the mechanisms that may contribute to the influence of stress and the role of exercise in preventing the negative actions of stress on cerebrovascular function and structure. Chronic unresolvable stress leads to the development of depression and cardiovascular disease. There is a high prevalence of depression with the metabolic syndrome (MetS), but to what extent the MetS concurrent with psychological stress affects cerebrovascular function is unknown. We investigated the differential effect of MetS on cerebrovascular structure/function in rats (16-17 weeks old) following 8 weeks of unpredictable chronic mild stress (UCMS) and whether exercise training could limit any cerebrovascular dysfunction. In healthy lean Zucker rats (LZR), UCMS decreased (28%, P < 0.05) ex vivo middle cerebral artery (MCA) endothelium-dependent dilatation (EDD), but changes in MCA remodelling and stiffness were not evident, though cerebral microvessel density (MVD) decreased (30%, P < 0.05). The presence of UCMS and MetS (obese Zucker rats; OZR) decreased MCA EDD (35%, P < 0.05) and dilatation to sodium nitroprusside (20%, P < 0.05), while MCA stiffness increased and cerebral MVD decreased (31%, P < 0.05), which were linked to reduced nitric oxide and increased oxidative levels. Aerobic exercise prevented UCMS impairments in MCA function and MVD in LZR, and partly restored MCA function, stiffness and MVD in OZR. Our data suggest that the benefits of exercise with UCMS were due to a reduction in oxidative stress and increased production of nitric oxide in the cerebral vessels. In conclusion, UCMS significantly impaired MCA structure and function, but the effects of UCMS were more substantial in OZR vs. LZR. Importantly, aerobic exercise when combined with UCMS prevented the MCA dysfunction through subtle shifts in nitric oxide and oxidative stress in the cerebral microvasculature. © 2018 The Authors. Experimental Physiology © 2018 The Physiological Society.

Post-disaster stressful life events and WTC-related posttraumatic stress, depressive symptoms, and overall functioning among responders to the World Trade Center disaster.

PubMed

Zvolensky, Michael J; Kotov, Roman; Schechter, Clyde B; Gonzalez, Adam; Vujanovic, Anka; Pietrzak, Robert H; Crane, Michael; Kaplan, Julia; Moline, Jacqueline; Southwick, Steven M; Feder, Adriana; Udasin, Iris; Reissman, Dori B; Luft, Benjamin J

2015-02-01

The current study examined contributions of post-disaster stressful life events in relation to the maintenance of WTC-related posttraumatic stress, depressive symptoms, and overall functioning among rescue, recovery, and clean-up workers who responded to the September 11, 2001 World Trade Center (WTC) terrorist attacks. Participants were 18,896 WTC responders, including 8466 police officers and 10,430 non-traditional responders (85.8% male; 86.4% Caucasian; M(age) = 39.5, SD = 8.8) participating in the WTC Health Program who completed an initial examination between July, 2002 and April, 2010 and who were reassessed, on average, 2.5 years later. Path analyses were conducted to evaluate contributions of life events to the maintenance of WTC-related posttraumatic stress, depressive symptoms, and overall functioning. These analyses were stratified by police and non-traditional responder groups and adjusted for age, sex, time from 9/11 to initial visit, WTC exposures (three WTC contextual exposures: co-worker, friend, or a relative died in the disaster; co-worker, friend, or a relative injured in the disaster; and responder was exposed to the dust cloud on 9/11), and interval from initial to first follow-up visit. In both groups, WTC-related posttraumatic stress, depressive symptoms, and overall functioning were stable over the follow-up period. WTC exposures were related to these three outcomes at the initial assessment. WTC-related posttraumatic stress, depressive symptoms, and overall functioning, at the initial assessment each predicted the occurrence of post-disaster stressful life events, as measured by Disaster Supplement of the Diagnostic Interview Schedule. Post-disaster stressful life events, in turn, were associated with subsequent mental health, indicating partial mediation of the stability of observed mental health. The present findings suggest a dynamic interplay between exposure, post-disaster stressful life events, and WTC-related posttraumatic stress, depressive symptoms, and overall functioning among WTC disaster responders. Published by Elsevier Ltd.

Moho Structure of the Central Sierra Nevada From an EarthScope Flex Array Deployment

NASA Astrophysics Data System (ADS)

Burdick, S.; Zandt, G.; Gilbert, H.; Jones, C.; Owens, T.

2005-12-01

Findings from the southern Sierra Nevada (south of 37 degrees north) show that the crustal thickness in the southern Sierra Nevada range does not obey an Airy isostasy model. Receiver function data show that the crustal thickness generally increases across the range from the high eastern peaks to the low western foothills, and the Moho discontinuity disappears beneath parts of the western foothills. This disappearance of the Moho has been attributed to the entrainment of the crust into the mantle by the convective removal of the southern batholithic root during the past 3-4 M yrs (Zandt et al., Nature, 2004). Other possible causes of Moho disappearance include a very gradational, or even inverted, impedance contrast due to lower crustal or upper mantle wavespeed anomalies. During the summer of 2005, the Sierra Nevada Earthscope Project (SNEP) has deployed an Earthscope flex array of over forty broadband seismometers with 25 km spacing, designed to constrain lithospheric structure of the central Sierra Nevada between the latitudes of approximately 37 to 38 degrees north. We will report on a receiver function study to better define the boundaries of the Moho "hole" to the north. Initial receiver functions from the first stations deployed mainly on the western and eastern flanks of the range show a northward continuation of both the "hole" under the western margin and a high amplitude Moho under the eastern flank of the range. This new observation suggests either the Moho disappearance is unrelated to the convective removal of the southern root or that root removal has affected the Sierra Nevada significantly farther north than suggested by presently available volcanic and xenolith evidence. Receiver functions collected from SNEP data will be processed into move-out corrected depth stacks in order to present a more complete map of Moho depth and amplitude beneath the region. To quantify the range of impedance contrasts capable of producing the observed variability in Moho amplitude, observed receiver function arrivals will be compared to synthetic examples calculated for a range of lower crustal and upper mantle wavespeeds. In conjunction with other studies these results should lead to a better understanding of the scale and processes associated with a young lithospheric foundering event.

Childhood Stress

MedlinePlus

... Safe Videos for Educators Search English Español Childhood Stress KidsHealth / For Parents / Childhood Stress What's in this ... and feel stress to some degree. Sources of Stress Stress is a function of the demands placed ...

The Batten disease gene CLN3 is required for the response to oxidative stress

PubMed Central

Tuxworth, Richard I.; Chen, Haiyang; Vivancos, Valerie; Carvajal, Nancy; Huang, Xun; Tear, Guy

2011-01-01

Mutations in the CLN3 gene cause juvenile neuronal ceroid lipofuscinosis (JNCL or Batten disease), an early onset neurodegenerative disorder. JNCL is the most common of the NCLs, a group of disorders with infant or childhood onset that are caused by single gene mutations. The NCLs, although relatively rare, share many pathological and clinical similarities with the more common late-onset neurodegenerative disorders, while their simple genetic basis makes them an excellent paradigm. The early onset and rapid disease progression in the NCLs suggests that one or more key cellular processes are severely compromised. To identify the functional pathways compromised in JNCL, we have performed a gain-of-function modifier screen in Drosophila. We find that CLN3 interacts genetically with the core stress signalling pathways and components of stress granules, suggesting a function in stress responses. In support of this, we find that Drosophila lacking CLN3 function are hypersensitive to oxidative stress yet they respond normally to other physiological stresses. Overexpression of CLN3 is sufficient to confer increased resistance to oxidative stress. We find that CLN3 mutant flies perceive conditions of increased oxidative stress correctly but are unable to detoxify reactive oxygen species, suggesting that their ability to respond is compromised. Together, our data suggest that the lack of CLN3 function leads to a failure to manage the response to oxidative stress and this may be the key deficit in JNCL that leads to neuronal degeneration. PMID:21372148

Australian Northwest Shelf: a Late Neogene Reversible Tectonic Event

NASA Astrophysics Data System (ADS)

Kominz, M. A.; Gurnis, M.; Gallagher, S. J.; Expedition 356 Scientists, I.

2017-12-01

The Northwest Shelf (NWS) of Australia is characterized by several offshore basins with active rifting in Permian and Jurassic time. Thus, by the Late Neogene this continental margin should be a very slowly subsiding passive margin. However, thick, poorly dated sediments have been noted in this region leading to speculation that this part of Australia has undergone down-warping in this time period. The International Ocean Discovery Program (IODP) Expedition 356 was designed, in part, to better constrain this even in both time and space. Post-cruise Airy-backstripping analyses of samples from four IODP 356 well sites, located as far south as the Perth Basin and as far North as the Carnarvon Basin, suggest that, in fact, this region has undergone a latest Miocene (≈ 8 to 6 Ma) subsidence event followed by a later (≈ 2 to 1 Ma) uplift event. Age constraints are from micropaleontology with some refinement using climate cycle-stratigraphy. Water depth constraints are from benthic foraminifera and from quantitative ratios of benthic foraminifera to planktonic foraminifera. These event cannot be explained as related to either the high-magnitude glacial eustatic changes nor can the uplift event be eliminated and ascribed to sediments filling the accommodation space generated in the earlier event. The magnitude and duration of the vertical movements are remarkably similar and suggests that the subsidence is reversible. Reversibility is a key aspect of a dynamic topography signal. However, it is difficult to produce a mantle anomaly that reproduces the subsidence and subsequent uplift with the requisite amplitude and rates as observed in the NWS of Australia. Additionally, the subduction of the Australian Plate into the Java Trench is too distant to affect this region of Australia. Modeling of a flexural warping due to in-plane stress related to collision of Timor with the Java trench is

Progress report of southeastern monazite exploration, 1952

USGS Publications Warehouse

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 contains only a small amount of monazite Pre-Wisconsin to early post-Wisconsin colluvial sediments locally contain 2 pounds of monazite to the cubic yard. Mode of presentation of reports covering field work during the seasons of 1951 - 52 is given. No further reconnaissance will be undertaken, in the western monazite belt.

Characterization of the Stabilized Test Bench of Nulling Interferometry PERSÉE

NASA Astrophysics Data System (ADS)

Lozi, Julien; Ollivier, M.; Cassaing, F.; Le Duigou, J.; CNES; Onera/Dota/HRA; IAS; LESIA; OCA; TAS

2013-01-01

There are two problems with the observation of exoplanets: the contrast between the planet and the star and their very low separation. One technique solving these problems is nulling interferometry: two pupils are recombined to make a destructive interference on the star, and their base is adjusted to create a constructive interference on the planet. However, to ensure a sufficient extinction of the star, the optical path difference between the beams must be around the nanometer, and the pointing must be better than one hundredth of Airy disk, despite the external disturbances.To validate the critical points of such a space mission, a laboratory demonstrator, PERSÉE, was defined by a consortium led by the french space agency CNES, including IAS, LESIA, ONERA, OCA and Thales Alenia Space and integrated in Paris Observatory. This bench simulates the entire space mission (interferometer and nanometric cophasing system). Its goal is to deliver and maintain an extinction of 10^-4 stable at better than 10^-5 over a few hours in the presence of typical injected disturbances.My thesis work consisted in integrating the bench in successive stages and to develop calibration procedures. This helped me to characterize the critical elements separately before grouping them. After having implemented the control loops of the cophasing system, their precise analysis helped me to reduce down to 0.3 nm rms the residual OPD, and 0.4 % of the Airy disk the residual tip/tilt, despite disturbances of tens of nanometers, consisting of several tens of vibrational frequencies between 1 and 100 Hz. This has been achieved by the implementation of a linear quadratic Gaussian controller, parameterized by the preliminary measurement of the disturbance to minimize. Thanks to these excellent results, I obtained on the band [1.65 - 2.45] µm a record null rate of 8.8x10^-6 stabilized at 9x10^-7 over a few hours, a decade better than the original specifications. An extrapolation of these results to the case of a space mission shows that the expected performance is achievable if the available flux is sufficiently important. With telescopes of 40 cm and a control frequency around 100 Hz, stars brighter than magnitude 9 should be observable.

Stress-induced changes in human decision-making are reversible.

PubMed

Soares, J M; Sampaio, A; Ferreira, L M; Santos, N C; Marques, F; Palha, J A; Cerqueira, J J; Sousa, N

2012-07-03

Appropriate decision-making relies on the ability to shift between different behavioral strategies according to the context in which decisions are made. A cohort of subjects exposed to prolonged stress, and respective gender- and age-matched controls, performed an instrumental behavioral task to assess their decision-making strategies. The stressed cohort was reevaluated after a 6-week stress-free period. The behavioral analysis was complemented by a functional magnetic resonance imaging (fMRI) study to detect the patterns of activation in corticostriatal networks ruling goal-directed and habitual actions. Using structural MRI, the volumes of the main cortical and subcortical regions implicated in instrumental behavior were determined. Here we show that chronic stress biases decision-making strategies in humans toward habits, as choices of stressed subjects become insensitive to changes in outcome value. Using functional imaging techniques, we demonstrate that prolonged exposure to stress in humans causes an imbalanced activation of the networks that govern decision processes, shifting activation from the associative to the sensorimotor circuits. These functional changes are paralleled by atrophy of the medial prefrontal cortex and the caudate, and by an increase in the volume of the putamina. Importantly, a longitudinal assessment of the stressed individuals showed that both the structural and functional changes triggered by stress are reversible and that decisions become again goal-directed.

Perception of Life as Stressful, not Biological Response to Stress, is Associated with Greater Social Disability in Adults with Autism Spectrum Disorder

PubMed Central

Bishop-Fitzpatrick, Lauren; Minshew, Nancy J.; Mazefsky, Carla A.; Eack, Shaun M.

2016-01-01

This study examined differences between adults with autism spectrum disorder (ASD; N=40) and typical community volunteers (N=25) on measures of stressful life events, perceived stress, and biological stress response (cardiovascular and cortisol reactivity) during a novel social stress task. Additional analyses examined the relationship between stress and social functioning as measured by the Social Adjustment Scale-II and the Waisman Activities of Daily Living scale. Results indicated that adults with ASD experienced significantly more stressful life events and perceived stress, and greater systolic blood pressure reactivity than typical community volunteers. Results also indicated that perceived stress and stressful life events were significantly associated with social disability. Interventions targeting stress management might improve social function in adults with ASD. PMID:27696184

Perception of Life as Stressful, Not Biological Response to Stress, is Associated with Greater Social Disability in Adults with Autism Spectrum Disorder.

PubMed

Bishop-Fitzpatrick, Lauren; Minshew, Nancy J; Mazefsky, Carla A; Eack, Shaun M

2017-01-01

This study examined differences between adults with autism spectrum disorder (ASD; N = 40) and typical community volunteers (N = 25) on measures of stressful life events, perceived stress, and biological stress response (cardiovascular and cortisol reactivity) during a novel social stress task. Additional analyses examined the relationship between stress and social functioning as measured by the Social Adjustment Scale-II and the Waisman Activities of Daily Living scale. Results indicated that adults with ASD experienced significantly more stressful life events and perceived stress, and greater systolic blood pressure reactivity than typical community volunteers. Results also indicated that perceived stress and stressful life events were significantly associated with social disability. Interventions targeting stress management might improve social function in adults with ASD.

[The severity of gestational diabetes mellitus affects microvascular dysfunction measured three years after pregnancy that may be related to increased oxidative stress].

PubMed

Horváth, Eszter Mária; Mágenheim, Rita; Domján, Beatrix Annamária; Ferencz, Viktória; Tänczer, Tímea; Szabó, Eszter; Benkő, Rita; Szabó, Csaba; Tabák, Ádám; Somogyi, Anikó

2015-11-22

Oxidative-nitrative stress and poly(ADP-ribose) polymerase activation observed in gestational diabetes may play role in the increased cardiovascular risk in later life. The present study aimed to examine the influence of the severity of previous gestational diabetes (insulin need) on vascular function three years after delivery. Furthermore, the authors investigated the relation of vascular function with oxidative-nitrative stress and poly(ADP-ribose) polymerase activation. Macrovascular function was measured by applanation tonometry; microvascular reactivity was assessed by provocation tests during Laser-Doppler flowmetry in 40 women who had gestational diabetes 3 years before the study. Oxidative-nitrative stress and poly(ADP-ribose) polymerase activity in blood components were determined by colorimetry and immunohistochemistry. Three years after insulin treated gestational diabetes impaired microvascular function and increased oxidative stress was observed compared to mild cases. The severity of previous gestational diabetes affects microvascular dysfunction that is accompanied by elevated oxidative stress. Nitrative stress and poly(ADP-ribose) polymerase activity correlates with certain vascular factors not related to the severity of the disease.

Clonidine Reduces Norepinephrine and Improves Bone Marrow Function in a Rodent Model of Lung Contusion, Hemorrhagic Shock and Chronic Stress

PubMed Central

Alamo, Ines G.; Kannan, Kolenkode B.; Ramos, Harry; Loftus, Tyler J.; Efron, Philip A.; Mohr, Alicia M.

2016-01-01

Background Propranolol has been shown previously to restore bone marrow function and improve anemia after lung contusion/hemorrhagic shock. We hypothesized that daily clonidine administration would inhibit central sympathetic outflow and restore bone marrow function in our rodent model of lung contusion/hemorrhagic shock with chronic stress. Methods Male Sprague-Dawley rats underwent six days of restraint stress after lung contusion/hemorrhagic shock during which the animals received clonidine (75μg/kg) after the restraint stress. On post-injury day seven, we assessed urine norepinephrine, blood hemoglobin, plasma granulocyte colony stimulating factor (G-CSF), and peripheral blood mobilization of hematopoietic progenitor cells (HPC), as well as bone marrow cellularity and erythroid progenitor cell growth. Results The addition of clonidine to lung contusion/hemorrhagic shock with chronic restraint stress, significantly decreased urine norepinephrine levels, improved bone marrow cellularity, restored erythroid progenitor colony growth, and improved hemoglobin (14.1±0.6 vs. 10.8±0.6 g/dL). The addition of clonidine to lung contusion/hemorrhagic shock with chronic restraint stress significantly decreased HPC mobilization and restored G-CSF levels. Conclusions After lung contusion/hemorrhagic shock with chronic restraint stress, daily administration of clonidine restored bone marrow function and improved anemia. Alleviating chronic stress and decreasing norepinephrine is a key therapeutic target to improve bone marrow function after severe injury. PMID:27742030

Effect of Mindfulness Meditation on Perceived Stress Scores and Autonomic Function Tests of Pregnant Indian Women.

PubMed

Muthukrishnan, Shobitha; Jain, Reena; Kohli, Sangeeta; Batra, Swaraj

2016-04-01

Various pregnancy complications like hypertension, preeclampsia have been strongly correlated with maternal stress. One of the connecting links between pregnancy complications and maternal stress is mind-body intervention which can be part of Complementary and Alternative Medicine (CAM). Biologic measures of stress during pregnancy may get reduced by such interventions. To evaluate the effect of Mindfulness meditation on perceived stress scores and autonomic function tests of pregnant Indian women. Pregnant Indian women of 12 weeks gestation were randomised to two treatment groups: Test group with Mindfulness meditation and control group with their usual obstetric care. The effect of Mindfulness meditation on perceived stress scores and cardiac sympathetic functions and parasympathetic functions (Heart rate variation with respiration, lying to standing ratio, standing to lying ratio and respiratory rate) were evaluated on pregnant Indian women. There was a significant decrease in perceived stress scores, a significant decrease of blood pressure response to cold pressor test and a significant increase in heart rate variability in the test group (p< 0.05, significant) which indicates that mindfulness meditation is a powerful modulator of the sympathetic nervous system and can thereby reduce the day-to-day perceived stress in pregnant women. The results of this study suggest that mindfulness meditation improves parasympathetic functions in pregnant women and is a powerful modulator of the sympathetic nervous system during pregnancy.

[Relationship between the frequency of work-related stress and prevalence of functional dyspepsia in Lima Geriatric Army Hospital].

PubMed

Valenzuela Narváez, Daniel Raúl; Gayoso Cervantes, Milagros

2017-01-01

To determine the relationship between the frequency of work-related stress and prevalence of functional dyspepsia in a sample of 218 military older 50 years in 2010 in Lima Military Hospital Geriatric. Descriptive and explanatory study and for the data collection on stress, were used the Vital Events Scale Holmes-Rahe and clinical records for clinical and upper endoscopy registration that comply the criteria of Rome III for functional dyspepsia. For processing and data analysis the statistical software package SPSS (Statistical Package for Social Sciences) was used. 100% of military showed some level of work stress during the study year; thus, 36.7% had a high level, 31.2% medium or moderate level, and 32.1% had low stress level; these percentages medium and high stress levels accounted for 67.9%. These results establish that job stress is a common discomfort in the study population (tabulated Chi2 = 3.841, chi2 observed = 27,908). Regarding functional dyspepsia prevalence of 37.2%, which indicates that it is a common condition in those military (tabular Z = 1.96, Z c = 9.163) it was determined. There is a significant relationship between the frequency of work-related stress and prevalence of functional dyspepsia in military activity in older than 50 years (tabulated Chi2 = 5.991, chi2 observed = 28,878, contingency coefficient = 0.342).

Stress and brain functional changes in patients with Crohn's disease: A functional magnetic resonance imaging study.

PubMed

Agostini, A; Ballotta, D; Righi, S; Moretti, M; Bertani, A; Scarcelli, A; Sartini, A; Ercolani, M; Nichelli, P; Campieri, M; Benuzzi, F

2017-10-01

In Crohn's disease (CD) patients, stress is believed to influence symptoms generation. Stress may act via central nervous system pathways to affect visceral sensitivity and motility thus exacerbating gastrointestinal symptoms. The neural substrate underpinning these mechanisms needs to be investigated in CD. We conducted an explorative functional magnetic resonance imaging (fMRI) study in order to investigate potential differences in the brain stress response in CD patients compared to controls. 17 CD patients and 17 healthy controls underwent a fMRI scan while performing a stressful task consisting in a Stroop color-word interference task designed to induce mental stress in the fMRI environment. Compared to controls, in CD patients the stress task elicited greater blood oxygen level dependent (BOLD) signals in the midcingulate cortex (MCC). The MCC integrate "high" emotional processes with afferent sensory information ascending from the gut. In light of these integrative functions, the stress-evoked MCC hyperactivity in CD patients might represent a plausible neural substrate for the association between stress and symptomatic disease. The MCC dysfunction might be involved in mechanisms of central disinhibition of nociceptive inputs leading to amplify the visceral sensitivity. Finally, the stress-evoked MCC hyperactivity might affect the regulation of intestinal motility resulting in exacerbation of disease symptoms and the autonomic and neuroendocrine regulation of inflammation resulting in enhanced inflammatory activity. © 2017 John Wiley & Sons Ltd.

Stress responses at the endometrial-placental interface regulate labyrinthine placental differentiation from trophoblast stem cells.

PubMed

Rappolee, D A; Zhou, S; Puscheck, E E; Xie, Y

2013-05-01

Development can happen in one of two ways. Cells performing a necessary function can differentiate from stem cells before the need for it arises and stress does not develop. Or need arises before function, stress develops and stress signals are part of the normal stimuli that regulate developmental mechanisms. These mechanisms adjust stem cell differentiation to produce function in a timely and proportional manner. In this review, we will interpret data from studies of null lethal mutants for placental stress genes that suggest the latter possibility. Acknowledged stress pathways participate in stress-induced and -regulated differentiation in two ways. These pathways manage the homeostatic response to maintain stem cells during the stress. Stress pathways also direct stem cell differentiation to increase the first essential lineage and suppress later lineages when stem cell accumulation is diminished. This stress-induced differentiation maintains the conceptus during stress. Pathogenic outcomes arise because population sizes of normal stem cells are first depleted by decreased accumulation. The fraction of stem cells is further decreased by differentiation that is induced to compensate for smaller stem cell populations. Analysis of placental lethal null mutant genes known to mediate stress responses suggests that the labyrinthine placenta develops during, and is regulated by, hypoxic stress.

Effects of Cable News Watching on Older Adults' Physiological and Self-Reported Stress and Cognitive Function.

PubMed

Deal, Caroline; Bogdan, Ryan; Miller, J Phil; Rodebaugh, Tom; Caburnay, Charlene; Yingling, Mike; Hershey, Tammy; Schweiger, Julia; Lenze, Eric J

2017-01-01

Older adults are the largest consumer of cable news, which includes negative and politicized content and may constitute a daily stressor. As older adults are also vulnerable to the negative consequences of stress, we hypothesized that cable news watching could induce a stress reaction and impair cognitive function. We tested exposures to cable news (i.e., Fox News and MSNBC) in a within-subject randomized controlled design in 34 healthy older adults. We also included negative (Public Broadcasting Station) and positive (trier social stress test) controls. Cable news watching had no effect on psychological stress, physiological stress, or cognitive function. This remained true even if the news exposures were discordant with participants' political affiliation. We conclude that brief cable news watching does not induce a physiological or subjective stress response or cognitive impairment among healthy older adults.

A Molecular Web: Endoplasmic Reticulum Stress, Inflammation, and Oxidative Stress

PubMed Central

Chaudhari, Namrata; Talwar, Priti; Parimisetty, Avinash; Lefebvre d’Hellencourt, Christian; Ravanan, Palaniyandi

2014-01-01

Execution of fundamental cellular functions demands regulated protein folding homeostasis. Endoplasmic reticulum (ER) is an active organelle existing to implement this function by folding and modifying secretory and membrane proteins. Loss of protein folding homeostasis is central to various diseases and budding evidences suggest ER stress as being a major contributor in the development or pathology of a diseased state besides other cellular stresses. The trigger for diseases may be diverse but, inflammation and/or ER stress may be basic mechanisms increasing the severity or complicating the condition of the disease. Chronic ER stress and activation of the unfolded-protein response (UPR) through endogenous or exogenous insults may result in impaired calcium and redox homeostasis, oxidative stress via protein overload thereby also influencing vital mitochondrial functions. Calcium released from the ER augments the production of mitochondrial Reactive Oxygen Species (ROS). Toxic accumulation of ROS within ER and mitochondria disturbs fundamental organelle functions. Sustained ER stress is known to potentially elicit inflammatory responses via UPR pathways. Additionally, ROS generated through inflammation or mitochondrial dysfunction could accelerate ER malfunction. Dysfunctional UPR pathways have been associated with a wide range of diseases including several neurodegenerative diseases, stroke, metabolic disorders, cancer, inflammatory disease, diabetes mellitus, cardiovascular disease, and others. In this review, we have discussed the UPR signaling pathways, and networking between ER stress-induced inflammatory pathways, oxidative stress, and mitochondrial signaling events, which further induce or exacerbate ER stress. PMID:25120434

Biological Mechanisms Underlying the Relationship between Stress and Smoking: State of the Science and Directions for Future Work

PubMed Central

Richards, Jessica; Stipelman, Brooke A.; Bornovalova, Marina A.; Daughters, Stacey; Sinha, Rajita; Lejuez, C.W.

2011-01-01

Theories of addiction implicate stress as a crucial mechanism underlying initiation, maintenance, and relapse to cigarette smoking. Examinations of the biological stress systems, including functioning of the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system (ANS), have provided additional insights into the relationship between stress and smoking. To date, convergent data suggests that chronic cigarette smoking is associated with alterations in HPA and ANS functioning; however, less is known about the role of HPA and ANS functioning in smoking initiation and relapse following cessation. In order to organize existing findings and stimulate future research, the current paper summarizes the available literature on the roles of HPA axis and ANS functioning in the relationship between stress and cigarette smoking, highlights limitations within the existing literature, and suggests directions for future research to address unanswered questions in the extant literature on the biological mechanisms underlying the relationship between stress and smoking. PMID:21741435

Blunted amygdala functional connectivity during a stress task in alcohol dependent individuals: A pilot study.

PubMed

Wade, Natasha E; Padula, Claudia B; Anthenelli, Robert M; Nelson, Erik; Eliassen, James; Lisdahl, Krista M

2017-12-01

Scant research has been conducted on neural mechanisms underlying stress processing in individuals with alcohol dependence (AD). We examined neural substrates of stress in AD individuals compared with controls using an fMRI task previously shown to induce stress, assessing amygdala functional connectivity to medial prefrontal cortex (mPFC). For this novel pilot study, 10 abstinent AD individuals and 11 controls completed a modified Trier stress task while undergoing fMRI acquisition. The amygdala was used as a seed region for whole-brain seed-based functional connectivity analysis. After controlling for family-wise error (p = 0.05), there was significantly decreased left and right amygdala connectivity with frontal (specifically mPFC), temporal, parietal, and cerebellar regions. Subjective stress, but not craving, increased from pre-to post-task. This study demonstrated decreased connectivity between the amygdala and regions important for stress and emotional processing in long-term abstinent individuals with AD. These results suggest aberrant stress processing in individuals with AD even after lengthy periods of abstinence.

Does social support from family and friends work as a buffer against reactions to stressful life events such as terminal cancer?

PubMed

Ringdal, Gerd Inger; Ringdal, Kristen; Jordhøy, Marit S; Kaasa, Stein

2007-03-01

To examine the relationship between social support and emotional functioning and stress reactions. Our hypothesis is that patients who reported a high degree of social support will experience better emotional functioning and less serious stress reactions than patients with a low degree of social support. The sample was comprised of 434 patients at the Palliative Medicine Unit (PMU), University Hospital of Trondheim in Norway. The patients completed a questionnaire monthly including questions about social support from the MacAdam's Scale, subjective stress measured by the Impact of Event Scale (IES), and emotional functioning measured by the subscale in the EORTC QLQ-30. Although our hypothesis was not supported at the baseline assessment, it was supported at the second assessment, 2 months later. Patients with high social support reported better emotional functioning and less serious stress reactions, in terms of lower scores on the IES avoidance subscale, than patients with a low degree of social support. SIGNIFICANCE OF THE RESULTS: The mixed findings may indicate that social support has only small effects on emotional functioning and stress reactions. Our results on the second assessment indicate, however, that social support might work as a buffer against reactions toward external stressful events such as terminal cancer.

The effects of stress hormones on immune function may be vital for the adaptive reconfiguration of the immune system during fight-or-flight behavior.

PubMed

Adamo, Shelley A

2014-09-01

Intense, short-term stress (i.e., robust activation of the fight-or-flight response) typically produces a transient decline in resistance to disease in animals across phyla. Chemical mediators of the stress response (e.g., stress hormones) help induce this decline, suggesting that this transient immunosuppression is an evolved response. However, determining the function of stress hormones on immune function is difficult because of their complexity. Nevertheless, evidence suggests that stress hormones help maintain maximal resistance to disease during the physiological changes needed to optimize the body for intense physical activity. Work on insects demonstrates that stress hormones both shunt resources away from the immune system during fight-or-flight responses as well as reconfigure the immune system. Reconfiguring the immune system minimizes the impact of the loss of these resources and reduces the increased costs of some immune functions due to the physiological changes demanded by the fight-or-flight response. For example, during the stress response of the cricket Gryllus texensis, some molecular resources are shunted away from the immune system and toward lipid transport, resulting in a reduction in resistance to disease. However, insects' immune cells (hemocytes) have receptors for octopamine (the insect stress neurohormone). Octopamine increases many hemocyte functions, such as phagocytosis, and these changes would tend to mitigate the decline in immunity due to the loss of molecular resources. Moreover, because the stress response generates oxidative stress, some immune responses are probably more costly when activated during a stress response (e.g., those that produce reactive molecules). Some of these immune responses are depressed during stress in crickets, while others, whose costs are probably not increased during a stress response, are enhanced. Some effects of stress hormones on immune systems may be better understood as examples of reconfiguration rather than as mediating a trade-off. © The Author 2014. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Posterior papillary muscle anchoring affects remote myofiber stress and pump function: finite element analysis.

PubMed

Pantoja, Joe Luis; Ge, Liang; Zhang, Zhihong; Morrel, William G; Guccione, Julius M; Grossi, Eugene A; Ratcliffe, Mark B

2014-10-01

The role of posterior papillary muscle anchoring (PPMA) in the management of chronic ischemic mitral regurgitation (CIMR) is controversial. We studied the effect of anchoring point direction and relocation displacement on left ventricular (LV) regional myofiber stress and pump function. Previously described finite element models of sheep 16 weeks after posterolateral myocardial infarction (MI) were used. True-sized mitral annuloplasty (MA) ring insertion plus different PPM anchoring techniques were simulated. Anchoring points tested included both commissures and the central anterior mitral annulus; relocation displacement varied from 10% to 40% of baseline diastolic distance from the PPM to the anchor points on the annulus. For each reconstruction scenario, myofiber stress in the MI, border zone, and remote myocardium as well as pump function were calculated. PPMA caused reductions in myofiber stress at end-diastole and end-systole in all regions of the left ventricle that were proportional to the relocation displacement. Although stress reduction was greatest in the MI region, it also occurred in the remote region. The maximum 40% displacement caused a slight reduction in LV pump function. However, with the correction of regurgitation by MA plus PPMA, there was an overall increase in forward stroke volume. Finally, anchoring point direction had no effect on myofiber stress or pump function. PPMA reduces remote myofiber stress, which is proportional to the absolute distance of relocation and independent of anchoring point. Aggressive use of PPMA techniques to reduce remote myofiber stress may accelerate reverse LV remodeling without impairing LV function. Copyright © 2014 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Endogenous extra-cellular heat shock protein 72: releasing signal(s) and function.

PubMed

Fleshner, M; Johnson, J D

2005-08-01

Exposure to acute physical and/or psychological stressors induces a cascade of physiological changes collectively termed the stress response. The stress response is demonstrable at the behavioural, neural, endocrine and cellular levels. Stimulation of the stress response functions to improve an organism's chance of survival during acute stressor challenge. The current review focuses on one ubiquitous cellular stress response, up-regulation of heat shock protein 72 (Hsp72). Although a great deal is known about the function of intra-cellular Hsp72 during exposure to acute stressors, little is understood about the potential function of endogenous extra-cellular Hsp72 (eHsp72). The current review will develop the hypothesis that eHsp72 release may be a previously unrecognized feature of the acute stress response and may function as an endogenous 'danger signal' for the immune system. Specifically, it is proposed that exposure to physical or psychological acute stressors stimulate the release of endogenous eHsp72 into the blood via an alpha1-adrenergic receptor-mediated mechanism and that elevated eHsp72 functions to facilitate innate immunity in the presence of bacterial challenge.

Elevated stress is associated with prefrontal cortex dysfunction during a verbal memory task in women with HIV

PubMed Central

Rubin, Leah H.; Wu, Minjie; Sundermann, Erin E.; Meyer, Vanessa J.; Smith, Rachael; Weber, Kathleen M.; Cohen, Mardge H.; Little, Deborah M.; Maki, Pauline M.

2016-01-01

HIV-infected women may be particularly vulnerable to verbal learning and memory deficits. One factor contributing to these deficits is high perceived stress, which is associated with prefrontal cortical (PFC) atrophy and memory outcomes sensitive to PFC function, including retrieval and semantic clustering. We examined the association between stress and PFC activation during a verbal memory task in 36 HIV-infected women from the Chicago Consortium of the Women’s Interagency HIV Study (WIHS) to better understand the role of the PFC in this stress-related impairment. Participants completed standardized measures of verbal learning and memory and stress (Perceived Stress Scale-10). We used functional magnetic resonance imaging to assess brain function while participants completed encoding and recognition phases of a verbal memory task. HIV-infected women with higher stress (scores in top tertile) performed worse on all verbal memory outcomes including strategic encoding (p’s<0.05) compared to HIV-infected women with lower stress (scores in lower two tertiles). Patterns of brain activation during recognition (but not encoding) differed between women with higher versus lower stress. During recognition, women with higher stress demonstrated greater deactivation in medial PFC and posterior cingulate cortex compared to women with lower stress (p’s<0.05). Greater deactivation in medial PFC marginally related to less efficient strategic retrieval (p=0.06). Similar results were found in analyses focusing on PTSD symptoms. Results suggest that stress might alter the function of the medial PFC in HIV-infected women resulting in less efficient strategic retrieval and deficits in verbal memory. PMID:27094924

Elevated stress is associated with prefrontal cortex dysfunction during a verbal memory task in women with HIV.

PubMed

Rubin, Leah H; Wu, Minjie; Sundermann, Erin E; Meyer, Vanessa J; Smith, Rachael; Weber, Kathleen M; Cohen, Mardge H; Little, Deborah M; Maki, Pauline M

2016-12-01

HIV-infected women may be particularly vulnerable to verbal learning and memory deficits. One factor contributing to these deficits is high perceived stress, which is associated with prefrontal cortical (PFC) atrophy and memory outcomes sensitive to PFC function, including retrieval and semantic clustering. We examined the association between stress and PFC activation during a verbal memory task in 36 HIV-infected women from the Chicago Consortium of the Women's Interagency HIV Study (WIHS) to better understand the role of the PFC in this stress-related impairment. Participants completed standardized measures of verbal learning and memory and stress (perceived stress scale-10). We used functional magnetic resonance imaging to assess brain function while participants completed encoding and recognition phases of a verbal memory task. HIV-infected women with higher stress (scores in top tertile) performed worse on all verbal memory outcomes including strategic encoding (p < 0.05) compared to HIV-infected women with lower stress (scores in lower two tertiles). Patterns of brain activation during recognition (but not encoding) differed between women with higher vs. lower stress. During recognition, women with higher stress demonstrated greater deactivation in medial PFC and posterior cingulate cortex compared to women with lower stress (p < 0.05). Greater deactivation in medial PFC marginally related to less efficient strategic retrieval (p = 0.06). Similar results were found in analyses focusing on PTSD symptoms. Results suggest that stress might alter the function of the medial PFC in HIV-infected women resulting in less efficient strategic retrieval and deficits in verbal memory.

Parental alcohol use disorders and child delinquency: the mediating effects of executive functioning and chronic family stress.

PubMed

Grekin, Emily R; Brennan, Patricia A; Hammen, Constance

2005-01-01

This study examines the relationship between parental alcohol use disorders (AUDs) and child violent and nonviolent delinquency. It also explores the mediating effects of executive functioning and chronic family stress on the parental AUD/child delinquency relationship. Participants were 816 families with children (414 boys and 402 girls) born between 1981 and 1984 at Mater Misericordiae Mother's Hospital in Brisbane, Australia. Parents and children completed semistructured interviews, questionnaires and neuropsychological tests that assessed parental alcohol use, family psychiatric history, chronic family stress, child delinquency and child executive functioning. Paternal (but not maternal) AUDs predicted child violent and nonviolent delinquency. Executive functioning mediated the relationship between paternal AUDs and violent delinquency, whereas family stress mediated the relationship between paternal AUDs and both violent and nonviolent delinquency. Results support a biosocial conceptualization of the paternal AUD/delinquency relationship. They suggest that paternal AUDs may be associated with child executive functioning and family stress, which may in turn lead to child delinquency.

Life stress versus traumatic stress: The impact of life events on psychological functioning in children with and without serious illness.

PubMed

Willard, Victoria W; Long, Alanna; Phipps, Sean

2016-01-01

To determine the differential impact of potentially traumatic events (PTEs) and other stressful life events on psychological functioning in 2 groups of children: those with cancer and those without history of serious illness. Children with cancer age 8-17 (n = 254) and age-, sex-, and race/ethnicity-matched controls (n = 142) completed self-report measures of stressful life events and psychological functioning. Stressful life events included those that may meet Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 2000) A1 criteria (PTEs; 9 events) and others that would likely not (other events; 21 events). Children with cancer endorsed significantly more PTEs than control children. There were no differences between groups in number of other events experienced. Hierarchical regression analyses revealed that number of other events accounted for significant variance in psychological functioning, above and beyond group status, demographic factors (age and socioeconomic status), and number of PTEs. The number of cumulative other events experienced is a significant predictor of psychological functioning in both youth with serious illness and controls. In contrast, cumulative PTEs appear to have a minor (albeit significant) impact on children's psychological functioning. Assessment of psychological functioning would benefit from a thorough history of stressful life events, regardless of their potential traumatic impact. (c) 2016 APA, all rights reserved).

Neuroendocrine circuits governing energy balance and stress regulation: functional overlap and therapeutic implications

PubMed Central

Ulrich-Lai, Yvonne M.; Ryan, Karen K.

2014-01-01

Significant co-morbidities between obesity-related metabolic disease and stress-related psychological disorders suggest important functional interactions between energy balance and brain stress integration. Largely overlapping neural circuits control these systems, and this anatomical arrangement optimizes opportunities for mutual influence. Here we first review the current literature identifying effects of metabolic neuroendocrine signals on stress regulation, and vice versa. Next, the contributions of reward driven food intake to these metabolic and stress interactions are discussed. Lastly, we consider the inter-relationships among metabolism, stress and reward in light of their important implications in the development of therapies for metabolism- or stress-related disease. PMID:24630812

An alternative approach for modeling strength differential effect in sheet metals with symmetric yield functions

NASA Astrophysics Data System (ADS)

Kurukuri, Srihari; Worswick, Michael J.

2013-12-01

An alternative approach is proposed to utilize symmetric yield functions for modeling the tension-compression asymmetry commonly observed in hcp materials. In this work, the strength differential (SD) effect is modeled by choosing separate symmetric plane stress yield functions (for example, Barlat Yld 2000-2d) for the tension i.e., in the first quadrant of principal stress space, and compression i.e., third quadrant of principal stress space. In the second and fourth quadrants, the yield locus is constructed by adopting interpolating functions between uniaxial tensile and compressive stress states. In this work, different interpolating functions are chosen and the predictive capability of each approach is discussed. The main advantage of this proposed approach is that the yield locus parameters are deterministic and relatively easy to identify when compared to the Cazacu family of yield functions commonly used for modeling SD effect observed in hcp materials.

Benefit of pelvic floor muscle therapy in improving sexual function in women with stress urinary incontinence: a pretest-posttest intervention study.

PubMed

Serati, Maurizio; Braga, Andrea; Di Dedda, Maria Carmela; Sorice, Paola; Peano, Elena; Biroli, Antonella; Torella, Marco; Cromi, Antonella; Uccella, Stefano; Salvatore, Stefano; Ghezzi, Fabio

2015-01-01

Very few data are available on the effect of pelvic floor muscle training on sexual function in incontinent women. The authors used the Female Sexual Function Index to assess the effect of pelvic floor muscle training on female sexual function. Participants included women with stress urinary incontinence, without overactive bladder symptoms, who completed a 3-month pelvic floor muscle training. All patients completed the Female Sexual Function Index and the International Consultation on Incontinence Questionnaire-Short Form at baseline and at the 3-month follow-up. Thirty-four patients completed all of the questionnaires; 64.7% patients were referred with stress urinary incontinence without sexual disorders, while 35.3% complained of stress urinary incontinence and sexual symptoms. The International Consultation on Incontinence Questionnaire-Short Form score significantly decreased after 3 months of pelvic floor muscle training (p =.01). The Female Sexual Function Index score significantly improved after pelvic floor muscle training even in women with sexual disorders (12.5 ± 9.5 vs. 29.7 ± 3.7; p <.001). This study showed that pelvic floor muscle training may improve female sexual function in women with pure stress urinary incontinence.

Chronic stress disrupts neural coherence between cortico-limbic structures.

PubMed

Oliveira, João Filipe; Dias, Nuno Sérgio; Correia, Mariana; Gama-Pereira, Filipa; Sardinha, Vanessa Morais; Lima, Ana; Oliveira, Ana Filipa; Jacinto, Luís Ricardo; Ferreira, Daniela Silva; Silva, Ana Maria; Reis, Joana Santos; Cerqueira, João José; Sousa, Nuno

2013-01-01

Chronic stress impairs cognitive function, namely on tasks that rely on the integrity of cortico-limbic networks. To unravel the functional impact of progressive stress in cortico-limbic networks we measured neural activity and spectral coherences between the ventral hippocampus (vHIP) and the medial prefrontal cortex (mPFC) in rats subjected to short term stress (STS) and chronic unpredictable stress (CUS). CUS exposure consistently disrupted the spectral coherence between both areas for a wide range of frequencies, whereas STS exposure failed to trigger such effect. The chronic stress-induced coherence decrease correlated inversely with the vHIP power spectrum, but not with the mPFC power spectrum, which supports the view that hippocampal dysfunction is the primary event after stress exposure. Importantly, we additionally show that the variations in vHIP-to-mPFC coherence and power spectrum in the vHIP correlated with stress-induced behavioral deficits in a spatial reference memory task. Altogether, these findings result in an innovative readout to measure, and follow, the functional events that underlie the stress-induced reference memory impairments.

Long-term effects of psychosocial work stress in midlife on health functioning after labor market exit--results from the GAZEL study.

PubMed

Wahrendorf, Morten; Sembajwe, Grace; Zins, Marie; Berkman, Lisa; Goldberg, Marcel; Siegrist, Johannes

2012-07-01

To study long-term effects of psychosocial work stress in mid-life on health functioning after labor market exit using two established work stress models. In the frame of the prospective French Gazel cohort study, data on psychosocial work stress were assessed using the full questionnaires measuring the demand-control-support model (in 1997 and 1999) and the effort-reward imbalance model (in 1998). In 2007, health functioning was assessed, using the Short Form 36 mental and physical component scores. Multivariate regressions were calculated to predict health functioning in 2007, controlling for age, gender, social position, and baseline self-perceived health. Consistent effects of both work stress models and their single components on mental and physical health functioning during retirement were observed. Effects remained significant after adjustment including baseline self-perceived health. Whereas the predictive power of both work stress models was similar in the case of the physical composite score, in the case of the mental health score, values of model fit were slightly higher for the effort-reward imbalance model (R(2): 0.13) compared with the demand-control model (R²: 0.11). Findings underline the importance of working conditions in midlife not only for health in midlife but also for health functioning after labor market exit.

Stressful Presentations: Mild Cold Stress in Laboratory Mice Influences Phenotype of Dendritic Cells in Naïve and Tumor-Bearing Mice

PubMed Central

Kokolus, Kathleen M.; Spangler, Haley M.; Povinelli, Benjamin J.; Farren, Matthew R.; Lee, Kelvin P.; Repasky, Elizabeth A.

2013-01-01

The ability of dendritic cells (DCs) to stimulate and regulate T cells is critical to effective anti-tumor immunity. Therefore, it is important to fully recognize any inherent factors which may influence DC function under experimental conditions, especially in laboratory mice since they are used so heavily to model immune responses. The goals of this report are to 1) briefly summarize previous work revealing how DCs respond to various forms of physiological stress and 2) to present new data highlighting the potential for chronic mild cold stress inherent to mice housed at the required standard ambient temperatures to influence baseline DCs properties in naïve and tumor-bearing mice. As recent data from our group shows that CD8+ T cell function is significantly altered by chronic mild cold stress and since DC function is crucial for CD8+ T cell activation, we wondered whether housing temperature may also be influencing DC function. Here we report that there are several significant phenotypical and functional differences among DC subsets in naïve and tumor-bearing mice housed at either standard housing temperature or at a thermoneutral ambient temperature, which significantly reduces the extent of cold stress. The new data presented here strongly suggests that, by itself, the housing temperature of mice can affect fundamental properties and functions of DCs. Therefore differences in basal levels of stress due to housing should be taken into consideration when interpreting experiments designed to evaluate the impact of additional variables, including other stressors on DC function. PMID:24575090

Stressful presentations: mild cold stress in laboratory mice influences phenotype of dendritic cells in naïve and tumor-bearing mice.

PubMed

Kokolus, Kathleen M; Spangler, Haley M; Povinelli, Benjamin J; Farren, Matthew R; Lee, Kelvin P; Repasky, Elizabeth A

2014-01-01

The ability of dendritic cells (DCs) to stimulate and regulate T cells is critical to effective anti-tumor immunity. Therefore, it is important to fully recognize any inherent factors which may influence DC function under experimental conditions, especially in laboratory mice since they are used so heavily to model immune responses. The goals of this report are to 1) briefly summarize previous work revealing how DCs respond to various forms of physiological stress and 2) to present new data highlighting the potential for chronic mild cold stress inherent to mice housed at the required standard ambient temperatures to influence baseline DCs properties in naïve and tumor-bearing mice. As recent data from our group shows that CD8(+) T cell function is significantly altered by chronic mild cold stress and since DC function is crucial for CD8(+) T cell activation, we wondered whether housing temperature may also be influencing DC function. Here we report that there are several significant phenotypical and functional differences among DC subsets in naïve and tumor-bearing mice housed at either standard housing temperature or at a thermoneutral ambient temperature, which significantly reduces the extent of cold stress. The new data presented here strongly suggests that, by itself, the housing temperature of mice can affect fundamental properties and functions of DCs. Therefore differences in basal levels of stress due to housing should be taken into consideration when interpreting experiments designed to evaluate the impact of additional variables, including other stressors on DC function.

Possible roles of vacuolar H+-ATPase and mitochondrial function in tolerance to air-drying stress revealed by genome-wide screening of Saccharomyces cerevisiae deletion strains.

PubMed

Shima, Jun; Ando, Akira; Takagi, Hiroshi

2008-03-01

Yeasts used in bread making are exposed to air-drying stress during dried yeast production processes. To clarify the genes required for air-drying tolerance, we performed genome-wide screening using the complete deletion strain collection of diploid Saccharomyces cerevisiae. The screening identified 278 gene deletions responsible for air-drying sensitivity. These genes were classified based on their cellular function and on the localization of their gene products. The results showed that the genes required for air-drying tolerance were frequently involved in mitochondrial functions and in connection with vacuolar H(+)-ATPase, which plays a role in vacuolar acidification. To determine the role of vacuolar acidification in air-drying stress tolerance, we monitored intracellular pH. The results showed that intracellular acidification was induced during air-drying and that this acidification was amplified in a deletion mutant of the VMA2 gene encoding a component of vacuolar H(+)-ATPase, suggesting that vacuolar H(+)-ATPase helps maintain intracellular pH homeostasis, which is affected by air-drying stress. To determine the effects of air-drying stress on mitochondria, we analysed the mitochondrial membrane potential under air-drying stress conditions using MitoTracker. The results showed that mitochondria were extremely sensitive to air-drying stress, suggesting that a mitochondrial function is required for tolerance to air-drying stress. We also analysed the correlation between oxidative-stress sensitivity and air-drying-stress sensitivity. The results suggested that oxidative stress is a critical determinant of sensitivity to air-drying stress, although ROS-scavenging systems are not necessary for air-drying stress tolerance. (c) 2008 John Wiley & Sons, Ltd.

Impact of a Stress Management Intervention Program on Sexual Functioning and Stress Reduction in Women with Breast Cancer

PubMed Central

Shayan, Arezoo; Jamshidi, Farkhondeh; Tahmasebiboldaji, Vahid; Khani, Somayeh; Babaei, Maryam; Havasian, Mohamad Reza; Masoumi, Seyedeh Zahra

2017-01-01

Breast cancer as the most common cancer among women endangers various aspects of their sexual lives and is a major culprit regarding health impairment and low life quality. The aim of this study was to examine the effect of a stress management intervention program on sexual functioning and stress reduction in women with breast cancer. This study employed a quasi-experimental pre-test, post-test design which included follow-up checks and a control group. To this end, 104 women with breast cancer referring to Hamadan’s Mahdiyeh MRI Center at the time of data collection were conventionally selected in 2015. Using permuted blocks, they were randomly divided into experimental and control groups (n= 52), only the former receiving stress management counseling for 18 hours. Data were collected through a demographic questionnaire, the Female Sexual Function Index (FSFI) questionnaire, and Harry’s stress questionnaire, filled out by patients before and after the intervention. To analyze the data, descriptive statistics and two-way ANOVA were used. The results showed that cognitive - behavioral stress management group therapy improved total sexual functioning and its subscales. After the treatment, there was a significant difference in mean scores between the groups (p=0.01). Moreover, significant differences were observed in the mean scores for stress with improvement in the experimental group in post-test results. Cognitive - behavioral group therapy for stress management was thuis found to improve total sexual functioning and its subscales and reduce the level of stress in the experimental group after the intervention and follow-up period with an interval of two weeks. Therefore, this method can be used as a complementary therapy along with medical treatment in oncology centers. PMID:29072415

Including Effects of Water Stress on Dead Organic Matter Decay to a Forest Carbon Model

NASA Astrophysics Data System (ADS)

Kim, H.; Lee, J.; Han, S. H.; Kim, S.; Son, Y.

2017-12-01

Decay of dead organic matter is a key process of carbon (C) cycling in forest ecosystems. The change in decay rate depends on temperature sensitivity and moisture conditions. The Forest Biomass and Dead organic matter Carbon (FBDC) model includes a decay sub-model considering temperature sensitivity, yet does not consider moisture conditions as drivers of the decay rate change. This study aimed to improve the FBDC model by including a water stress function to the decay sub-model. Also, soil C sequestration under climate change with the FBDC model including the water stress function was simulated. The water stress functions were determined with data from decomposition study on Quercus variabilis forests and Pinus densiflora forests of Korea, and adjustment parameters of the functions were determined for both species. The water stress functions were based on the ratio of precipitation to potential evapotranspiration. Including the water stress function increased the explained variances of the decay rate by 19% for the Q. variabilis forests and 7% for the P. densiflora forests, respectively. The increase of the explained variances resulted from large difference in temperature range and precipitation range across the decomposition study plots. During the period of experiment, the mean annual temperature range was less than 3°C, while the annual precipitation ranged from 720mm to 1466mm. Application of the water stress functions to the FBDC model constrained increasing trend of temperature sensitivity under climate change, and thus increased the model-estimated soil C sequestration (Mg C ha-1) by 6.6 for the Q. variabilis forests and by 3.1 for the P. densiflora forests, respectively. The addition of water stress functions increased reliability of the decay rate estimation and could contribute to reducing the bias in estimating soil C sequestration under varying moisture condition. Acknowledgement: This study was supported by Korea Forest Service (2017044B10-1719-BB01)

Effect of Pranayama on stress and cardiovascular autonomic function.

PubMed

Bhimani, N T; Kulkarni, N B; Kowale, A; Salvi, S

2011-01-01

The stress either physical or mental, leads to cardiovascular morbidity. Newly admitted medical students are likely to be exposed to various stresses like change of environment, demanding medical education and different teaching protocol in a medical college. Pranayama is known since ancient times to relieve stress and stabilize autonomic function of the body. Therefore it was decided to study effect of Pranayama on stress and cardiovascular autonomic function. The subjects were first M.B.B.S students and the sample size was 59 consisting of 27 males and 32 females. The group of students thus selected was briefed about the study. After the orientation session, informed written consent was taken, stress questionnaire was put and the autonomic function tests were done. This was followed by practice of Pranayama for 2 months, 1 hour/day for 5 days/week and again stress questionnaire was put and the autonomic function tests were performed on the study group. The above tests were done before and after the practice of Pranayama. The results obtained were analyzed using SPSS software. The stress level has reduced after 2 months of practicing various pranayama as evident by decrease in total stress score which is highly significant. VLF and LF in n.u have reduced significantly after practice of pranayama signifying reduction in sympathetic drive to heart. HF in n.u has increased significantly after practice of pranayama for 2 months showing the increase in parasympathetic output to the heart. LF/ HF ratio reduced significantly after 2 months of practice of pranayama indicating a better sympatho vagal balance with resting balance tilting toward better parasympathetic control.

Complex interplay between health and successful aging: Role of perceived stress, resilience, and social support

PubMed Central

Moore, Raeanne C.; Eyler, Lisa T.; Mausbach, Brent T.; Zlatar, Zvinka Z.; Thompson, Wesley K.; Peavy, Guerry; Fazeli, Pariya L.; Jeste, Dilip V.

2014-01-01

Psychological and psychosocial resources, including resilience and social support, have traditionally been studied in the context of the stress paradigm and, more recently, in the context of successful aging. This study used moderated mediation analyses to examine the role of perceived stress in the relationships between physical and mental health functioning and self-rated successful aging (SRSA), and whether differences between people in level of resilience and social support changes the role of perceived stress in these relationships. A cross-sectional study of 1,006 older adults (Mean=77 years) completed scales addressing SRSA, physical and mental health functioning, perceived stress, resilience, and social support. Results indicated that the strength of relationships between both physical and mental health functioning and SRSA were reduced after accounting for variation in level of perceived stress. The role of perceived stress in the association between mental health functioning and SRSA was found to be stronger among participants with the highest levels of resilience, and the influence of perceived stress on the degree of relationship between physical health functioning and SRSA was stronger among those with greatest social support. These findings suggest that interventions to reduce perceived stress may help break the link between disability and poor well-being in older adults. The findings further suggest that the impact of such interventions might differ depending on psychological resources (i.e., resilience) for mental health disabilities and external resources (i.e., social support) for those with physical health problems. The complex interplay of these factors should be taken into account in clinical settings. PMID:25217186

Analysis of corner cracks at hole by a 3-D weight function method with stresses from finite element method

NASA Technical Reports Server (NTRS)

Zhao, W.; Newman, J. C., Jr.; Sutton, M. A.; Wu, X. R.; Shivakumar, K. N.

1995-01-01

Stress intensity factors for quarter-elliptical corner cracks emanating from a circular hole are determined using a 3-D weight function method combined with a 3-D finite element method. The 3-D finite element method is used to analyze uncracked configuration and provide stress distribution in the region where crack is to occur. Using this stress distribution as input, the 3-D weight function method is used to determine stress intensity factors. Three different loading conditions, i.e. remote tension, remote bending and wedge loading, are considered for a wide range in geometrical parameters. The significance in using 3-D uncracked stress distribution and the difference between single and double corner cracks are studied. Typical crack opening displacements are also provided. Comparisons are made with solutions available in the literature.

Stressful life events predict delayed functional recovery following treatment for mania in bipolar disorder.

PubMed

Yan-Meier, Leslie; Eberhart, Nicole K; Hammen, Constance L; Gitlin, Michael; Sokolski, Kenneth; Altshuler, Lori

2011-04-30

Identifying predictors of functional recovery in bipolar disorder is critical to treatment efforts to help patients re-establish premorbid levels of role adjustment following an acute manic episode. The current study examined the role of stressful life events as potential obstacles to recovery of functioning in various roles. 65 patients with bipolar I disorder participated in a longitudinal study of functional recovery following clinical recovery from a manic episode. Stressful life events were assessed as predictors of concurrent vs. delayed recovery of role functioning in 4 domains (friends, family, home duties, work/school). Despite clinical recovery, a subset of patients experienced delayed functional recovery in various role domains. Moreover, delayed functional recovery was significantly associated with presence of one or more stressors in the prior 3 months, even after controlling for mood symptoms. Presence of a stressor predicted longer time to functional recovery in life domains, up to 112 days in work/school. Interventions that provide monitoring, support, and problem-solving may be needed to help prevent or mitigate the effects of stress on functional recovery. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Fatigue life prediction in bending from axial fatigue information

NASA Technical Reports Server (NTRS)

Manson, S. S.; Muralidharan, U.

1982-01-01

Bending fatigue in the low cyclic life range differs from axial fatigue due to the plastic flow which alters the linear stress-strain relation normally used to determine the nominal stresses. An approach is presented to take into account the plastic flow in calculating nominal bending stress (S sub bending) based on true surface stress. These functions are derived in closed form for rectangular and circular cross sections. The nominal bending stress and the axial fatigue stress are plotted as a function of life (N sub S) and these curves are shown for several materials of engineering interest.

Immediate and long-term effects of meditation on acute stress reactivity, cognitive functions, and intelligence.

PubMed

Singh, Yogesh; Sharma, Ratna; Talwar, Anjana

2012-01-01

With the current globalization of the world's economy and demands for enhanced performance, stress is present universally. Life's stressful events and daily stresses cause both deleterious and cumulative effects on the human body. The practice of meditation might offer a way to relieve that stress. The research team intended to study the effects of meditation on stress-induced changes in physiological parameters, cognitive functions, intelligence, and emotional quotients. The research team conducted the study in two phases, with a month between them. Each participant served as his own control, and the first phase served as the control for the second phase. In phase 1, the research team studied the effects of a stressor (10 minutes playing a computer game) on participants' stress levels. In phase 2, the research team examined the effects of meditation on stress levels. The research team conducted the study in a lab setting at the All India Institute of Medical Sciences (AIIMS), New Delhi, India. The participants were 34 healthy, male volunteers who were students. To study the effects of long-term meditation on stress levels, intelligence, emotional quotients, and cognitive functions participants meditated daily for 1 month, between phases 1 and 2. To study the immediate effects of meditation on stress levels, participants meditated for 15 minutes after playing a computer game to induce stress. The research team measured galvanic skin response (GSR), heart rate (HR), and salivary cortisol and administered tests for the intelligence and emotional quotients (IQ and EQ), acute and perceived stress (AS and PS), and cognitive functions (ie, the Sternberg memory test [short-term memory] and the Stroop test [cognitive flexibility]). Using a pre-post study design, the team performed this testing (1) prior to the start of the study (baseline); (2) in phase 1, after induced stress; (3) in part 1 of phase 2, after 1 month of daily meditation, and (4) in part 2 of phase 2, after induced stress, both before and after 15 minutes of meditation. Induced stress from the computer game resulted in a significant increase in physiological markers of stress such as GSR and HR. In the short term, meditation was associated with a physiological relaxation response (significant decrease in GSR) and an improvement in scores on the Stroop test of reaction times. In the long-term, meditation brought significant improvements in IQ and scores for cognitive functions, whereas participants' stress levels (GSR and AS) decreased. EQ, salivary cortisol, and HR showed no significant changes. The practice of meditation reduced psychological stress responses and improved cognitive functions, and the effects were pronounced with practice of meditation for a longer duration (1 month).

Life Stress and Dimensions of Functioning in Old Age.

ERIC Educational Resources Information Center

Leon, Gloria Rakita; And Others

1981-01-01

Most men had made a satisfactory social and emotional adjustment over time, but a significant number were troubled by chronic illness. The most common stress factor reported was death of a friend. Past personality patterns coupled with current life stress factors were not predictive of present personality functioning. (JAC)

A longitudinal investigation of parenting stress in caregivers of children with retinoblastoma.

PubMed

Willard, Victoria W; Qaddoumi, Ibrahim; Zhang, Hui; Huang, Lu; Russell, Kathryn M; Brennan, Rachel; Wilson, Matthew W; Rodriguez-Galindo, Carlos; Phipps, Sean

2017-04-01

Retinoblastoma is typically diagnosed in young children and may present unique parenting challenges. Qualitative research suggests that parents experience distress related to the initial diagnosis and treatment that subsequently resolves. The objectives were to systematically assess parenting stress over time in parents of young children with retinoblastoma and to examine associations between parenting stress and child outcomes. Parents of children with retinoblastoma completed the Parenting Stress Index (PSI) during serial psychological assessments scheduled based on the child's age (6 months to 5 years). Caregivers of 92 patients (85.9% mothers) completed the assessments. Child outcomes included developmental functioning and parent-reported adaptive functioning. At baseline and age 5, all subscales on the PSI were within normal limits, and most were significantly below normative means (i.e., demonstrating low levels of stress). All domains remained relatively stable over time. Associations between parenting stress and child outcomes were much stronger at age 5 than at baseline. Child-directed parenting stress was a small but significant contributor to declines in child functioning over time. Parents of children with retinoblastoma report normal levels of parenting stress while their children are young. However, baseline parenting stress appears to contribute to changes in child functioning over time. Future studies should assess illness-related aspects of adjustment to further understand the parenting experience of young children with cancer and/or having a visually impaired child. © 2016 Wiley Periodicals, Inc.

Early life stress determines the effects of glucocorticoids and stress on hippocampal function: Electrophysiological and behavioral evidence respectively.

PubMed

Pillai, Anup G; Arp, Marit; Velzing, Els; Lesuis, Sylvie L; Schmidt, Mathias V; Holsboer, Florian; Joëls, Marian; Krugers, Harm J

2018-05-01

Exposure to early-life adversity may program brain function to prepare individuals for adaptation to matching environmental contexts. In this study we tested this hypothesis in more detail by examining the effects of early-life stress - induced by raising offspring with limited nesting and bedding material from postnatal days 2-9 - in various behavioral tasks and on synaptic function in adult mice. Early-life stress impaired adult performance in the hippocampal dependent low-arousing object-in-context recognition memory task. This effect was absent when animals were exposed to a single stressor before training. Early-life stress did not alter high-arousing context and auditory fear conditioning. Early-life stress-induced behavioral modifications were not associated with alterations in the dendritic architecture of hippocampal CA1 pyramidal neurons or principal neurons of the basolateral amygdala. However, early-life stress reduced the ratio of NMDA to AMPA receptor-mediated excitatory postsynaptic currents and glutamate release probability specifically in hippocampal CA1 neurons, but not in the basolateral amygdala. These ex vivo effects in the hippocampus were abolished by acute glucocorticoid treatment. Our findings support that early-life stress can hamper object-in-context learning via pre- and postsynaptic mechanisms that affect hippocampal function but these effects are counteracted by acute stress or elevated glucocorticoid levels. Copyright © 2018. Published by Elsevier Ltd.

Clonidine reduces norepinephrine and improves bone marrow function in a rodent model of lung contusion, hemorrhagic shock, and chronic stress.

PubMed

Alamo, Ines G; Kannan, Kolenkode B; Ramos, Harry; Loftus, Tyler J; Efron, Philip A; Mohr, Alicia M

2017-03-01

Propranolol has been shown previously to restore bone marrow function and improve anemia after lung contusion/hemorrhagic shock. We hypothesized that daily clonidine administration would inhibit central sympathetic outflow and restore bone marrow function in our rodent model of lung contusion/hemorrhagic shock with chronic stress. Male Sprague-Dawley rats underwent 6 days of restraint stress after lung contusion/hemorrhagic shock during which the animals received clonidine (75 μg/kg) after the restraint stress. On postinjury day 7, we assessed urine norepinephrine, blood hemoglobin, plasma granulocyte colony stimulating factor, and peripheral blood mobilization of hematopoietic progenitor cells, as well as bone marrow cellularity and erythroid progenitor cell growth. The addition of clonidine to lung contusion/hemorrhagic shock with chronic restraint stress significantly decreased urine norepinephrine levels, improved bone marrow cellularity, restored erythroid progenitor colony growth, and improved hemoglobin (14.1 ± 0.6 vs 10.8 ± 0.6 g/dL). The addition of clonidine to lung contusion/hemorrhagic shock with chronic restraint stress significantly decreased hematopoietic progenitor cells mobilization and restored granulocyte colony stimulating factor levels. After lung contusion/hemorrhagic shock with chronic restraint stress, daily administration of clonidine restored bone marrow function and improved anemia. Alleviating chronic stress and decreasing norepinephrine is a key therapeutic target to improve bone marrow function after severe injury. Copyright © 2016 Elsevier Inc. All rights reserved.

Perceived stress and change in cognitive function among adults 65 years and older.

PubMed

Aggarwal, Neelum T; Wilson, Robert S; Beck, Todd L; Rajan, Kumar B; Mendes de Leon, Carlos F; Evans, Denis A; Everson-Rose, Susan A

2014-01-01

Exposure to acute and chronic stress can affect learning and memory, but most evidence comes from animal studies or clinical observations. Almost no population-based studies have investigated the relation of stress to cognition or changes in cognition over time. We examined whether higher levels of perceived stress were associated with accelerated decline in cognitive function in older blacks and whites from a community-based population sample. Participants included 6207 black and white adults (65.7% black, 63.3% women) from the Chicago Health and Aging Project. Two to five in-home assessments were completed over an average of 6.8 years of follow-up and included sociodemographics, health behaviors, psychosocial measures, cognitive function tests, and health history. Perceived stress was measured by a six-item scale, and a composite measure of four tests of cognition was used to determine cognitive function at each assessment. Mixed-effects regression models showed that increasing levels of perceived stress were related to lower initial cognitive scores (B = -0.0379, standard error = 0.0025, p < .001) and a faster rate of cognitive decline (stress × time interaction: B = -0.0015, standard error = 0.0004, p < .001). Results were similar after adjusting for demographic variables, smoking, systolic blood pressure, body mass index, chronic medical conditions, and psychosocial factors and did not vary by race, sex, age, or education. Increasing levels of stress are independently associated with accelerated declines in cognitive function in black and white adults 65 years and older.

A NAP-Family Histone Chaperone Functions in Abiotic Stress Response and Adaptation1[OPEN

PubMed Central

Pareek, Ashwani; Singla-Pareek, Sneh Lata

2016-01-01

Modulation of gene expression is one of the most significant molecular mechanisms of abiotic stress response in plants. Via altering DNA accessibility, histone chaperones affect the transcriptional competence of genomic loci. However, in contrast to other factors affecting chromatin dynamics, the role of plant histone chaperones in abiotic stress response and adaptation remains elusive. Here, we studied the physiological function of a stress-responsive putative rice (Oryza sativa) histone chaperone of the NAP superfamily: OsNAPL6. We show that OsNAPL6 is a nuclear-localized H3/H4 histone chaperone capable of assembling a nucleosome-like structure. Utilizing overexpression and knockdown approaches, we found a positive correlation between OsNAPL6 expression levels and adaptation to multiple abiotic stresses. Results of comparative transcriptome profiling and promoter-recruitment studies indicate that OsNAPL6 functions during stress response via modulation of expression of various genes involved in diverse functions. For instance, we show that OsNAPL6 is recruited to OsRad51 promoter, activating its expression and leading to more efficient DNA repair and abrogation of programmed cell death under salinity and genotoxic stress conditions. These results suggest that the histone chaperone OsNAPL6 may serve a regulatory role in abiotic stress physiology possibly via modulating nucleosome dynamics at various stress-associated genomic loci. Taken together, our findings establish a hitherto unknown link between histone chaperones and abiotic stress response in plants. PMID:27342307

Resting-state functional connectivity of the bed nucleus of the stria terminalis in post-traumatic stress disorder and its dissociative subtype.

PubMed

Rabellino, Daniela; Densmore, Maria; Harricharan, Sherain; Jean, Théberge; McKinnon, Margaret C; Lanius, Ruth A

2018-03-01

The bed nucleus of the stria terminals (BNST) is a subcortical structure involved in anticipatory and sustained reactivity to threat and is thus essential to the understanding of anxiety and stress responses. Although chronic stress and anxiety represent a hallmark of post-traumatic stress disorder (PTSD), to date, few studies have examined the functional connectivity of the BNST in PTSD. Here, we used resting state functional Magnetic Resonance Imaging (fMRI) to investigate the functional connectivity of the BNST in PTSD (n = 70), its dissociative subtype (PTSD + DS) (n = 41), and healthy controls (n = 50). In comparison to controls, PTSD showed increased functional connectivity of the BNST with regions of the reward system (ventral and dorsal striatum), possibly underlying stress-induced reward-seeking behaviors in PTSD. By contrast, comparing PTSD + DS to controls, we observed increased functional connectivity of the BNST with the claustrum, a brain region implicated in consciousness and a primary site of kappa-opioid receptors, which are critical to the dynorphin-mediated dysphoric stress response. Moreover, PTSD + DS showed increased functional connectivity of the BNST with brain regions involved in attention and salience detection (anterior insula and caudate nucleus) as compared to PTSD and controls. Finally, BNST functional connectivity positively correlated with default-mode network regions as a function of state identity dissociation, suggesting a role of BNST networks in the disruption of self-relevant processing characterizing the dissociative subtype. These findings represent an important first step in elucidating the role of the BNST in aberrant functional networks underlying PTSD and its dissociative subtype. © 2017 Wiley Periodicals, Inc.

Functional mechanisms of drought tolerance in subtropical maize (Zea mays L.) identified using genome-wide association mapping.

PubMed

Thirunavukkarasu, Nepolean; Hossain, Firoz; Arora, Kanika; Sharma, Rinku; Shiriga, Kaliyugam; Mittal, Swati; Mohan, Sweta; Namratha, Pottekatt Mohanlal; Dogga, Sreelatha; Rani, Tikka Shobha; Katragadda, Sumalini; Rathore, Abhishek; Shah, Trushar; Mohapatra, Trilochan; Gupta, Hari Shankar

2014-12-24

Earlier studies were focused on the genetics of temperate and tropical maize under drought. We identified genetic loci and their association with functional mechanisms in 240 accessions of subtropical maize using a high-density marker set under water stress. Out of 61 significant SNPs (11 were false-discovery-rate-corrected associations), identified across agronomic traits, models, and locations by subjecting the accessions to water stress at flowering stage, 48% were associated with drought-tolerant genes. Maize gene models revealed that SNPs mapped for agronomic traits were in fact associated with number of functional traits as follows: stomatal closure, 28; flowering, 15; root development, 5; detoxification, 4; and reduced water potential, 2. Interactions of these SNPS through the functional traits could lead to drought tolerance. The SNPs associated with ABA-dependent signalling pathways played a major role in the plant's response to stress by regulating a series of functions including flowering, root development, auxin metabolism, guard cell functions, and scavenging reactive oxygen species (ROS). ABA signalling genes regulate flowering through epigenetic changes in stress-responsive genes. ROS generated by ABA signalling are reduced by the interplay between ethylene, ABA, and detoxification signalling transductions. Integration of ABA-signalling genes with auxin-inducible genes regulates root development which in turn, maintains the water balance by regulating electrochemical gradient in plant. Several genes are directly or indirectly involved in the functioning of agronomic traits related to water stress. Genes involved in these crucial biological functions interacted significantly in order to maintain the primary as well as exclusive functions related to coping with water stress. SNPs associated with drought-tolerant genes involved in strategic biological functions will be useful to understand the mechanisms of drought tolerance in subtropical maize.

Salubrious effects of oxytocin on social stress-induced deficits

PubMed Central

Smith, Adam S.; Wang, Zuoxin

2012-01-01

Social relationships are a fundamental aspect of life, affecting social, psychological, physiological, and behavioral functions. While social interactions can attenuate stress and promote health, disruption, confrontations, isolation, or neglect in the social environment can each be major stressors. Social stress can impair the basal function and stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis, impairing function of multiple biological systems and posing a risk to mental and physical health. In contrast, social support can ameliorate stress-induced physiological and immunological deficits, reducing the risk of subsequent psychological distress and improving an individual's overall well-being. For better clinical treatment of these physiological and mental pathologies, it is necessary to understand the regulatory mechanisms of stress-induced pathologies as well as determine the underlying biological mechanisms that regulate social buffering of the stress system. A number of ethologically relevant animal models of social stress and species that form strong adult social bonds have been utilized to study the etiology, treatment, and prevention of stress-related disorders. While undoubtedly a number of biological pathways contribute to the social buffering of the stress response, the convergence of evidence denotes the regulatory effects of oxytocin in facilitating social bond-promoting behaviors and their effect on the stress response. Thus, oxytocin may be perceived as a common regulatory element of the social environment, stress response, and stress-induced risks on mental and physical health. PMID:22178036

Quantum electronic stress: density-functional-theory formulation and physical manifestation.

PubMed

Hu, Hao; Liu, Miao; Wang, Z F; Zhu, Junyi; Wu, Dangxin; Ding, Hepeng; Liu, Zheng; Liu, Feng

2012-08-03

The concept of quantum electronic stress (QES) is introduced and formulated within density functional theory to elucidate extrinsic electronic effects on the stress state of solids and thin films in the absence of lattice strain. A formal expression of QES (σ(QE)) is derived in relation to deformation potential of electronic states (Ξ) and variation of electron density (Δn), σ(QE) = ΞΔn as a quantum analog of classical Hooke's law. Two distinct QES manifestations are demonstrated quantitatively by density functional theory calculations: (1) in the form of bulk stress induced by charge carriers and (2) in the form of surface stress induced by quantum confinement. Implications of QES in some physical phenomena are discussed to underlie its importance.

The calculation of the viscosity from the autocorrelation function using molecular and atomic stress tensors

NASA Astrophysics Data System (ADS)

Cui, S. T.

The stress-stress correlation function and the viscosity of a united-atom model of liquid decane are studied by equilibrium molecular dynamics simulation using two different formalisms for the stress tensor: the atomic and the molecular formalisms. The atomic and molecular correlation functions show dramatic difference in short-time behaviour. The integrals of the two correlation functions, however, become identical after a short transient period whichis significantly shorter than the rotational relaxation time of the molecule. Both reach the same plateau value in a time period corresponding to this relaxation time. These results provide a convenient guide for the choice of the upper integral time limit in calculating the viscosity by the Green-Kubo formula.

Prenatal stress-induced increases in hippocampal von Willebrand factor expression are prevented by concurrent prenatal escitalopram

PubMed Central

Neigh, Gretchen N.; Nemeth, Christina L; Kelly, Sean D.; Hardy, Emily E.; Bourke, Chase; Stowe, Zachary N.; Owens, Michael J.

2016-01-01

Prenatal stress has been linked to deficits in neurological function including deficient social behavior, alterations in learning and memory, impaired stress regulation, and susceptibility to adult disease. In addition, prenatal environment is known to alter cardiovascular health; however, limited information is available regarding the cerebrovascular consequences of prenatal stress exposure. Vascular disturbances late in life may lead to cerebral hypoperfusion which is linked to a variety of neurodegenerative and psychiatric diseases. The known impact of cerebrovascular compromise on neuronal function and behavior highlights the importance of characterizing the impact of stress on not just neurons and glia, but also cerebrovasculature. Von Willebrand factor has previously been shown to be impacted by prenatal stress and is predictive of cerebrovascular health. Here we assess the impact of prenatal stress on von Willebrand factor and related angiogenic factors. Furthermore, we assess the potential protective effects of concurrent anti-depressant treatment during in utero stress exposure on the assessed cerebrovascular endpoints. Prenatal stress augmented expression of von Willebrand factor which was prevented by concurrent in utero escitalopram treatment. The functional implications of this increase in von Willebrand factor remain elusive, but the presented data demonstrate that although prenatal stress did not independently impact total vascularization, exposure to chronic stress in adulthood decreased blood vessel length. In addition, the current study demonstrates that production of reactive oxygen species in the hippocampus is decreased by prenatal exposure to escitalopram. Collectively, these findings demonstrate that the prenatal experience can cause complex changes in adult cerebral vascular structure and function. PMID:27422674

Design of a k-space spectrometer for ultra-broad waveband spectral domain optical coherence tomography.

PubMed

Lan, Gongpu; Li, Guoqiang

2017-03-07

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).

Design of a k-space spectrometer for ultra-broad waveband spectral domain optical coherence tomography

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).

Analysis of spatial correlations in a model two-dimensional liquid through eigenvalues and eigenvectors of atomic-level stress matrices.

PubMed

Levashov, V A; Stepanov, M G

2016-01-01

Considerations of local atomic-level stresses associated with each atom represent a particular approach to address structures of disordered materials at the atomic level. We studied structural correlations in a two-dimensional model liquid using molecular dynamics simulations in the following way. We diagonalized the atomic-level stress tensor of every atom and investigated correlations between the eigenvalues and orientations of the eigenvectors of different atoms as a function of distance between them. It is demonstrated that the suggested approach can be used to characterize structural correlations in disordered materials. In particular, we found that changes in the stress correlation functions on decrease of temperature are the most pronounced for the pairs of atoms with separation distance that corresponds to the first minimum in the pair density function. We also show that the angular dependencies of the stress correlation functions previously reported by Wu et al. [Phys. Rev. E 91, 032301 (2015)10.1103/PhysRevE.91.032301] do not represent the anisotropic Eshelby's stress fields, as it is suggested, but originate in the rotational properties of the stress tensors.

Personal and couple level risk factors: Maternal and paternal parent-child aggression risk.

PubMed

Tucker, Meagan C; Rodriguez, Christina M; Baker, Levi R

2017-07-01

Previous literature examining parent-child aggression (PCA) risk has relied heavily upon mothers, limiting our understanding of paternal risk factors. Moreover, the extent to which factors in the couple relationship work in tandem with personal vulnerabilities to impact PCA risk is unclear. The current study examined whether personal stress and distress predicted PCA risk (child abuse potential, over-reactive discipline style, harsh discipline practices) for fathers as well as mothers and whether couple functioning mediated versus moderated the relation between personal stress and PCA risk in a sample of 81 couples. Additionally, the potential for risk factors in one partner to cross over and affect their partner's PCA risk was considered. Findings indicated higher personal stress predicted elevated maternal and paternal PCA risk. Better couple functioning did not moderate this relationship but partially mediated stress and PCA risk for both mothers and fathers. In addition, maternal stress evidenced a cross-over effect, wherein mothers' personal stress linked to fathers' couple functioning. Findings support the role of stress and couple functioning in maternal and paternal PCA risk, including potential cross-over effects that warrant further inquiry. Copyright © 2017 Elsevier Ltd. All rights reserved.

Developmental inter-relations between early maternal depression, contextual risks, and interpersonal stress, and their effect on later child cognitive functioning.

PubMed

Jensen, Sarah K G; Dumontheil, Iroise; Barker, Edward D

2014-07-01

Maternal depression and contextual risks (e.g. poverty) are known to impact children's cognitive and social functioning. However, few published studies have examined how stress in the social environment (i.e. interpersonal stress) might developmentally inter-relate with maternal depression and contextual risks to negatively affect a child in these domains. This was the purpose of the current study. Mother-child pairs (n = 6979) from the Avon Longitudinal Study of Parents were the study participants. Mothers reported on depression, contextual risks, and interpersonal stress between pregnancy and 33 months child age. At age 8, the children underwent cognitive assessments and the mothers reported on the children's social cognitive skills. Maternal depression, contextual risks, and interpersonal stress showed strong continuity and developmental inter-relatedness. Maternal depression and contextual risks directly predicted a range of child outcomes, including executive functions and social cognitive skills. Interpersonal stress worked indirectly via maternal depression and contextual risks to negatively affect child outcomes. Maternal depression and contextual risks each increased interpersonal stress in the household, which, in turn, contributed to reduced child cognitive and social functioning. © 2013 Wiley Periodicals, Inc.

Effects of stress on immune function: the good, the bad, and the beautiful.

PubMed

Dhabhar, Firdaus S

2014-05-01

Although the concept of stress has earned a bad reputation, it is important to recognize that the adaptive purpose of a physiological stress response is to promote survival during fight or flight. While long-term stress is generally harmful, short-term stress can be protective as it prepares the organism to deal with challenges. This review discusses the immune effects of biological stress responses that can be induced by psychological, physiological, or physical (including exercise) stressors. We have proposed that short-term stress is one of the nature's fundamental but under-appreciated survival mechanisms that could be clinically harnessed to enhance immunoprotection. Short-term (i.e., lasting for minutes to hours) stress experienced during immune activation enhances innate/primary and adaptive/secondary immune responses. Mechanisms of immuno-enhancement include changes in dendritic cell, neutrophil, macrophage, and lymphocyte trafficking, maturation, and function as well as local and systemic production of cytokines. In contrast, long-term stress suppresses or dysregulates innate and adaptive immune responses by altering the Type 1-Type 2 cytokine balance, inducing low-grade chronic inflammation, and suppressing numbers, trafficking, and function of immunoprotective cells. Chronic stress may also increase susceptibility to some types of cancer by suppressing Type 1 cytokines and protective T cells and increasing regulatory/suppressor T cell function. Here, we classify immune responses as being protective, pathological, or regulatory, and discuss "good" versus "bad" effects of stress on health. Thus, short-term stress can enhance the acquisition and/or expression of immunoprotective (wound healing, vaccination, anti-infectious agent, anti-tumor) or immuno-pathological (pro-inflammatory, autoimmune) responses. In contrast, chronic stress can suppress protective immune responses and/or exacerbate pathological immune responses. Studies such as the ones discussed here could provide mechanistic targets and conceptual frameworks for pharmacological and/or biobehavioral interventions designed to enhance the effects of "good" stress, minimize the effects of "bad" stress, and maximally promote health and healing.

Identification and classification of genes required for tolerance to freeze-thaw stress revealed by genome-wide screening of Saccharomyces cerevisiae deletion strains.

PubMed

Ando, Akira; Nakamura, Toshihide; Murata, Yoshinori; Takagi, Hiroshi; Shima, Jun

2007-03-01

Yeasts used in bread making are exposed to freeze-thaw stress during frozen-dough baking. To clarify the genes required for freeze-thaw tolerance, genome-wide screening was performed using the complete deletion strain collection of diploid Saccharomyces cerevisiae. The screening identified 58 gene deletions that conferred freeze-thaw sensitivity. These genes were then classified based on their cellular function and on the localization of their products. The results showed that the genes required for freeze-thaw tolerance were frequently involved in vacuole functions and cell wall biogenesis. The highest numbers of gene products were components of vacuolar H(+)-ATPase. Next, the cross-sensitivity of the freeze-thaw-sensitive mutants to oxidative stress and to cell wall stress was studied; both of these are environmental stresses closely related to freeze-thaw stress. The results showed that defects in the functions of vacuolar H(+)-ATPase conferred sensitivity to oxidative stress and to cell wall stress. In contrast, defects in gene products involved in cell wall assembly conferred sensitivity to cell wall stress but not to oxidative stress. Our results suggest the presence of at least two different mechanisms of freeze-thaw injury: oxidative stress generated during the freeze-thaw process, and defects in cell wall assembly.

Psychological stress-relieving effects of chewing - Relationship between masticatory function-related factors and stress-relieving effects.

PubMed

Tasaka, Akinori; Kikuchi, Manaki; Nakanishi, Kousuke; Ueda, Takayuki; Yamashita, Shuichiro; Sakurai, Kaoru

2018-01-01

The objective of the present study was to investigate the relationship between masticatory function-related factors (masticatory performance, occlusal contact area, maximum bite force, number of chewing strokes, and muscle activity) and the stress-relieving effects of chewing. A total of 28 healthy male subjects were instructed to rest or chew for 10min after 30min of stress loading with arithmetic calculations. Their stress state was assessed by measuring salivary cortisol levels. Saliva was collected at three time points: before stress loading, immediately after stress loading, and 10min after stress loading. Compared to resting, chewing produced a significantly greater reduction in the rate of change in salivary cortisol levels 10min after stress loading. A negative correlation was observed between the rate of decrease in salivary cortisol levels and the number of chewing strokes. No significant correlation was observed between the rate of decrease in salivary cortisol levels and other measurement items. In healthy dentulous people, the number of chewing strokes has been shown to be a masticatory function-related factor that affects stress relief from chewing, suggesting the possibility that more appropriate chewing would produce a greater effect psychological stress relief. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Mitochondrial functions modulate neuroendocrine, metabolic, inflammatory, and transcriptional responses to acute psychological stress

PubMed Central

Picard, Martin; McManus, Meagan J.; Gray, Jason D.; Nasca, Carla; Moffat, Cynthia; Kopinski, Piotr K.; Seifert, Erin L.; McEwen, Bruce S.; Wallace, Douglas C.

2015-01-01

The experience of psychological stress triggers neuroendocrine, inflammatory, metabolic, and transcriptional perturbations that ultimately predispose to disease. However, the subcellular determinants of this integrated, multisystemic stress response have not been defined. Central to stress adaptation is cellular energetics, involving mitochondrial energy production and oxidative stress. We therefore hypothesized that abnormal mitochondrial functions would differentially modulate the organism’s multisystemic response to psychological stress. By mutating or deleting mitochondrial genes encoded in the mtDNA [NADH dehydrogenase 6 (ND6) and cytochrome c oxidase subunit I (COI)] or nuclear DNA [adenine nucleotide translocator 1 (ANT1) and nicotinamide nucleotide transhydrogenase (NNT)], we selectively impaired mitochondrial respiratory chain function, energy exchange, and mitochondrial redox balance in mice. The resulting impact on physiological reactivity and recovery from restraint stress were then characterized. We show that mitochondrial dysfunctions altered the hypothalamic–pituitary–adrenal axis, sympathetic adrenal–medullary activation and catecholamine levels, the inflammatory cytokine IL-6, circulating metabolites, and hippocampal gene expression responses to stress. Each mitochondrial defect generated a distinct whole-body stress-response signature. These results demonstrate the role of mitochondrial energetics and redox balance as modulators of key pathophysiological perturbations previously linked to disease. This work establishes mitochondria as stress-response modulators, with implications for understanding the mechanisms of stress pathophysiology and mitochondrial diseases. PMID:26627253

Neuro-Epigenetic Indications of Acute Stress Response in Humans: The Case of MicroRNA-29c

PubMed Central

Farberov, Luba; Lin, Tamar; Sharon, Haggai; Gilam, Avital; Volk, Naama; Admon, Roee; Edry, Liat; Fruchter, Eyal; Wald, Ilan; Bar-Haim, Yair; Tarrasch, Ricardo; Chen, Alon; Shomron, Noam; Hendler, Talma

2016-01-01

Stress research has progressively become more integrative in nature, seeking to unfold crucial relations between the different phenotypic levels of stress manifestations. This study sought to unravel stress-induced variations in expression of human microRNAs sampled in peripheral blood mononuclear cells and further assess their relationship with neuronal and psychological indices. We obtained blood samples from 49 healthy male participants before and three hours after performing a social stress task, while undergoing functional magnetic resonance imaging (fMRI). A seed-based functional connectivity (FC) analysis was conducted for the ventro-medial prefrontal cortex (vmPFC), a key area of stress regulation. Out of hundreds of microRNAs, a specific increase was identified in microRNA-29c (miR-29c) expression, corresponding with both the experience of sustained stress via self-reports, and alterations in vmPFC functional connectivity. Explicitly, miR-29c expression levels corresponded with both increased connectivity of the vmPFC with the anterior insula (aIns), and decreased connectivity of the vmPFC with the left dorso-lateral prefrontal cortex (dlPFC). Our findings further revealed that miR-29c mediates an indirect path linking enhanced vmPFC-aIns connectivity during stress with subsequent experiences of sustained stress. The correlative patterns of miR-29c expression and vmPFC FC, along with the mediating effects on subjective stress sustainment and the presumed localization of miR-29c in astrocytes, together point to an intriguing assumption; miR-29c may serve as a biomarker in the blood for stress-induced functional neural alterations reflecting regulatory processes. Such a multi-level model may hold the key for future personalized intervention in stress psychopathology. PMID:26730965

Stress and reward processing in bipolar disorder: a functional magnetic resonance imaging study.

PubMed

Berghorst, Lisa H; Kumar, Poornima; Greve, Doug N; Deckersbach, Thilo; Ongur, Dost; Dutra, Sunny J; Pizzagalli, Diego A

2016-11-01

A link between negative life stress and the onset of mood episodes in bipolar disorder (BD) has been established, but processes underlying such a link remain unclear. Growing evidence suggests that stress can negatively affect reward processing and related neurobiological substrates, indicating that a dysregulated reward system may provide a partial explanation. The aim of this study was to test the impact of stress on reward-related neural functioning in BD. Thirteen euthymic or mildly depressed individuals with BD and 15 controls performed a Monetary Incentive Delay (MID) task while undergoing functional magnetic resonance imaging during no-stress and stress (negative psychosocial stressor involving poor performance feedback and threat of monetary deductions) conditions. In hypothesis-driven region-of-interest analyses, a significant group-by-condition interaction emerged in the amygdala during reward anticipation. Relative to controls, while anticipating a potential reward, subjects with BD were characterized by amygdalar hyperactivation in the no-stress condition but hypoactivation during stress. Moreover, relative to controls, subjects with BD had significantly larger amygdala volumes. After controlling for structural differences, the effects of stress on amygdalar function remained, whereas groups no longer differed during the no-stress condition. During reward consumption, a group-by-condition interaction emerged in the putamen due to increased putamen activation in response to rewards in participants with BD during stress, but an opposite pattern in controls. Overall, findings highlight possible impairments in using reward-predicting cues to adaptively engage in goal-directed actions in BD, combined with stress-induced hypersensitivity to reward consumption. Potential clinical implications are discussed. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Revisiting the Role of Plant Transcription Factors in the Battle against Abiotic Stress.

PubMed

Khan, Sardar-Ali; Li, Meng-Zhan; Wang, Suo-Min; Yin, Hong-Ju

2018-05-31

Owing to diverse abiotic stresses and global climate deterioration, the agricultural production worldwide is suffering serious losses. Breeding stress-resilient crops with higher quality and yield against multiple environmental stresses via application of transgenic technologies is currently the most promising approach. Deciphering molecular principles and mining stress-associate genes that govern plant responses against abiotic stresses is one of the prerequisites to develop stress-resistant crop varieties. As molecular switches in controlling stress-responsive genes expression, transcription factors (TFs) play crucial roles in regulating various abiotic stress responses. Hence, functional analysis of TFs and their interaction partners during abiotic stresses is crucial to perceive their role in diverse signaling cascades that many researchers have continued to undertake. Here, we review current developments in understanding TFs, with particular emphasis on their functions in orchestrating plant abiotic stress responses. Further, we discuss novel molecular mechanisms of their action under abiotic stress conditions. This will provide valuable information for understanding regulatory mechanisms to engineer stress-tolerant crops.

Fibroblast Growth Factor 8 Deficiency Compromises the Functional Response of the Serotonergic System to Stress

PubMed Central

Brooks, Leah R.; Pals, Heide L.; Enix, Courtney L.; Woolaver, Rachel A.; Paul, Evan D.; Lowry, Christopher A.; Tsai, Pei-San

2014-01-01

Functionally heterogeneous populations of serotonergic neurons, located within the dorsal raphe nucleus (DR), play a role in stress-related behaviors and neuropsychiatric illnesses such as anxiety and depression. Abnormal development of these neurons may permanently alter their structure and connections, making the organism more susceptible to anxiety-related disorders. A factor that critically regulates the development of serotonergic neurons is fibroblast growth factor 8 (Fgf8). In this study, we used acute restraint stress followed by behavioral testing to examine whether Fgf8 signaling during development is important for establishing functional stress- and anxiety-related DR neurocircuits in adulthood. Wild-type and heterozygous male mice globally hypomorphic for Fgf8 were exposed to acute restraint stress and then tested for anxiety-like behavior on the elevated plus-maze. Further, we measured c-Fos immunostaining as a marker of serotonergic neuronal activation and tissue 5-hydroxyindoleacetic acid concentrations as a marker of serotonin functional output. Results showed that Fgf8 hypomorphs exhibited 1) an exaggerated response of DR anxiety-promoting circuits and 2) a blunted response of a DR panic-inhibiting circuit to stress, effects that together were associated with increased baseline anxiety-like behavior. Overall, our results provide a neural substrate upon which Fgf8 deficiency could affect stress response and support the hypothesis that developmental disruptions of serotonergic neurons affect their postnatal functional integrity. PMID:24992493

Fibroblast growth factor 8 deficiency compromises the functional response of the serotonergic system to stress.

PubMed

Brooks, Leah R; Pals, Heide L; Enix, Courtney L; Woolaver, Rachel A; Paul, Evan D; Lowry, Christopher A; Tsai, Pei-San

2014-01-01

Functionally heterogeneous populations of serotonergic neurons, located within the dorsal raphe nucleus (DR), play a role in stress-related behaviors and neuropsychiatric illnesses such as anxiety and depression. Abnormal development of these neurons may permanently alter their structure and connections, making the organism more susceptible to anxiety-related disorders. A factor that critically regulates the development of serotonergic neurons is fibroblast growth factor 8 (Fgf8). In this study, we used acute restraint stress followed by behavioral testing to examine whether Fgf8 signaling during development is important for establishing functional stress- and anxiety-related DR neurocircuits in adulthood. Wild-type and heterozygous male mice globally hypomorphic for Fgf8 were exposed to acute restraint stress and then tested for anxiety-like behavior on the elevated plus-maze. Further, we measured c-Fos immunostaining as a marker of serotonergic neuronal activation and tissue 5-hydroxyindoleacetic acid concentrations as a marker of serotonin functional output. Results showed that Fgf8 hypomorphs exhibited 1) an exaggerated response of DR anxiety-promoting circuits and 2) a blunted response of a DR panic-inhibiting circuit to stress, effects that together were associated with increased baseline anxiety-like behavior. Overall, our results provide a neural substrate upon which Fgf8 deficiency could affect stress response and support the hypothesis that developmental disruptions of serotonergic neurons affect their postnatal functional integrity.

Stress and Depression in Relation to Functional Health Behaviors in African American Patients with Systemic Lupus Erythematosus.

PubMed

Williams, Edith M; Bruner, Larisa; Penfield, Megan; Kamen, Diane; Oates, James C

While increased psychological distress in SLE has been clinically and empirically reported, the relationship between emotional distress, treatment adherence, and disease activity are complex and even more unclear in African American lupus patients. In an effort to elucidate this phenomenon in these patients, this exploratory study aimed to investigate relationships between stress, depression, and various health behaviors in this group. Thirty patients invited to participate in this study were African American systemic lupus erythematosus (SLE) patients attending rheumatology clinics at the Medical University of South Carolina (MUSC). This study was part of a larger interventional pilot study, the Balancing Lupus Experiences with Stress Strategies (BLESS) study, that included a comprehensive battery of psychosocial, quality of life, and behavior change measures. When looking at the association between anxiety/stress and functionality, levels of reported stress had strong effects upon functionality, especially between health distress and functionality. When looking at the association between depressive symptoms and functionality, depressive symptoms had moderate effects upon social/role limitations and nights spent in the hospital. Not only did the larger pilot project demonstrate significant reductions in stress and depression as a result of workshop participation; this nested study also showed that those improvements were positively associated with improved health behaviors. These results could have implications for developing interventions to improve disease experience and quality of life in SLE patients with stress and depression.

Ethylene Response Factor TERF1, Regulated by ETHYLENE-INSENSITIVE3-like Factors, Functions in Reactive Oxygen Species (ROS) Scavenging in Tobacco (Nicotiana tabacum L.).

PubMed

Zhang, Hongbo; Li, Ang; Zhang, Zhijin; Huang, Zejun; Lu, Pingli; Zhang, Dingyu; Liu, Xinmin; Zhang, Zhong-Feng; Huang, Rongfeng

2016-07-20

The phytohormone ethylene plays a crucial role in the production and accumulation of reactive oxygen species (ROS) in plants under stress conditions. Ethylene response factors (ERFs) are important ethylene-signaling regulators functioning in plant defense responses against biotic and abiotic stresses. However, the roles of ERFs during plant adapting to ROS stress have not yet been well documented. Our studies previously reported that a tomato ERF transcription factor TERF1 functions in the regulation of plant ethylene responses and stress tolerance. Here, we report our findings regarding the roles of TERF1 in ROS scavenging. In this study, we revealed that the transcription of TERF1 is regulated by upstream EIN3-like (EIN3, ethylene-insensitive 3) regulators LeEIL3 and LeEIL4 in tomato (Solanum lycopersicum), and is also inducible by exogenous applied ROS-generating reagents. Ectopic expression of TERF1 in tobacco promoted the expression of genes involved in oxidative stress responses, including carbonic anhydrase functioning in hypersensitive defense, catalase and glutathione peroxidase catalyzing oxidative reactions, and GDP-D-mannose pyrophosphorylase functioning in ascorbic acid biosynthesis, reduced the ROS content induced by ethylene treatment, and enhanced stress tolerance of tobacco seedlings to hydrogen peroxide (H2O2). Cumulatively, these findings suggest that TERF1 is an ethylene inducible factor regulating ROS scavenging during stress responses.

Evaluation of stress changes in the mandible with a fixed functional appliance: a finite element study.

PubMed

Chaudhry, Anshul; Sidhu, Maninder S; Chaudhary, Girish; Grover, Seema; Chaudhry, Nimisha; Kaushik, Ashutosh

2015-02-01

The aim of this study was to evaluate the effects of a fixed functional appliance (Forsus Fatigue Resistant Device; 3M Unitek, Monrovia, Calif) on the mandible with 3-dimensional finite element stress analysis. A 3-dimensional finite element model of the mandible was constructed from the images generated by cone-beam computed tomography of a patient undergoing fixed orthodontic treatment. The changes were studied with the finite element method, in the form of highest von Mises stress and maximum principal stress regions. More areas of stress were seen in the model of the mandible with the Forsus compared with the model of the mandible in the resting stage. This fixed functional appliance studied by finite element model analysis caused increases in the maximum principal stress and the von Mises stress in both the cortical bone and the condylar region of the mandible by more than 2 times. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Photonic homeostatics

NASA Astrophysics Data System (ADS)

Liu, Timon C.; Li, Fan-Hui

2010-11-01

Photonic homeostatics is a discipline to study the establishment, maintenance, decay, upgrading and representation of function-specific homoestasis (FSH) by using photonics. FSH is a negative-feedback response of a biosystem to maintain the function-specific fluctuations inside the biosystem so that the function is perfectly performed. A stress may increase sirtuin 1 (SIRT1) activities above FSH-specific SIRT1 activity to induce a function far from its FSH. On the one hand, low level laser irradiation or monochromatic light (LLL) can not modulate a function in its FSH or a stress in its stress-specific homeostasis (StSH), but modulate a function far from its FSH or a stress far from its StSH. On the other hand, the biophotons from a biosystem with its function in its FSH should be less than the one from the biosystem with its function far from its FSH. The non-resonant interaction of low intensity laser irradiation or monochromatic light (LIL) and a kind of membrane protein can be amplified by all the membrane proteins if the function is far from its FSH. This amplification might hold for biophoton emission of the membrane protein so that the photonic spectroscopy can be used to represent the function far from its FSH, which is called photonomics.

Interactive Contributions of Cumulative Peer Stress and Executive Function Deficits to Depression in Early Adolescence.

PubMed

Agoston, Anna M; Rudolph, Karen D

2016-01-01

Exposure to peer stress contributes to adolescent depression, yet not all youth experience these effects. Thus, it is important to identify individual differences that shape the consequences of peer stress. This research investigated the interactive contribution of cumulative peer stress during childhood (second-fifth grades) and executive function (EF) deficits to depression during early adolescence (sixth grade). Youth (267 girls, 227 boys; X̄ age at Wave 1 = 7.95, SD = .37) completed questionnaires and semi-structured interviews to assess peer stress and depression, respectively; teachers completed the Behavior Rating Scale of Executive Function to assess everyday performance in several EF domains. As anticipated, exposure to peer stress in childhood predicted heightened sixth-grade depression in girls but not boys with higher levels of EF deficits. This study extends theory and research on individual differences in vulnerability to adolescent depression, in turn elucidating potential intervention targets.

Acute stress affects prospective memory functions via associative memory processes.

PubMed

Szőllősi, Ágnes; Pajkossy, Péter; Demeter, Gyula; Kéri, Szabolcs; Racsmány, Mihály

2018-01-01

Recent findings suggest that acute stress can improve the execution of delayed intentions (prospective memory, PM). However, it is unclear whether this improvement can be explained by altered executive control processes or by altered associative memory functioning. To investigate this issue, we used physical-psychosocial stressors to induce acute stress in laboratory settings. Then participants completed event- and time-based PM tasks requiring the different contribution of control processes and a control task (letter fluency) frequently used to measure executive functions. According to our results, acute stress had no impact on ongoing task performance, time-based PM, and verbal fluency, whereas it enhanced event-based PM as measured by response speed for the prospective cues. Our findings indicate that, here, acute stress did not affect executive control processes. We suggest that stress affected event-based PM via associative memory processes. Copyright © 2017 Elsevier B.V. All rights reserved.

Interactive Contributions of Cumulative Peer Stress and Executive Function Deficits to Depression in Early Adolescence

PubMed Central

Agoston, Anna M.; Rudolph, Karen D.

2017-01-01

Exposure to peer stress contributes to adolescent depression, yet not all youth experience these effects. Thus, it is important to identify individual differences that shape the consequences of peer stress. This research investigated the interactive contribution of cumulative peer stress during childhood (second-fifth grades) and executive function (EF) deficits to depression during early adolescence (sixth grade). Youth (267 girls, 227 boys; X̄age at Wave 1 = 7.95, SD = .37) completed questionnaires and semi-structured interviews to assess peer stress and depression, respectively; teachers completed the Behavior Rating Scale of Executive Function to assess everyday performance in several EF domains. As anticipated, exposure to peer stress in childhood predicted heightened sixth-grade depression in girls but not boys with higher levels of EF deficits. This study extends theory and research on individual differences in vulnerability to adolescent depression, in turn elucidating potential intervention targets. PMID:28936024

Computational gene expression profiling under salt stress reveals patterns of co-expression

PubMed Central

Sanchita; Sharma, Ashok

2016-01-01

Plants respond differently to environmental conditions. Among various abiotic stresses, salt stress is a condition where excess salt in soil causes inhibition of plant growth. To understand the response of plants to the stress conditions, identification of the responsible genes is required. Clustering is a data mining technique used to group the genes with similar expression. The genes of a cluster show similar expression and function. We applied clustering algorithms on gene expression data of Solanum tuberosum showing differential expression in Capsicum annuum under salt stress. The clusters, which were common in multiple algorithms were taken further for analysis. Principal component analysis (PCA) further validated the findings of other cluster algorithms by visualizing their clusters in three-dimensional space. Functional annotation results revealed that most of the genes were involved in stress related responses. Our findings suggest that these algorithms may be helpful in the prediction of the function of co-expressed genes. PMID:26981411

Lexical Stress Assignment in Italian Developmental Dyslexia

ERIC Educational Resources Information Center

Paizi, Despina; Zoccolotti, Pierluigi; Burani, Cristina

2011-01-01

Stress assignment to Italian polysyllabic words is unpredictable, because stress is neither marked nor predicted by rule. Stress assignment, especially to low frequency words, has been reported to be a function of stress dominance and stress neighbourhood. Two experiments investigate stress assignment in sixth-grade, skilled and dyslexic, readers.…

Chronic Gestational Stress Leads to Depressive-Like Behavior and Compromises Medial Prefrontal Cortex Structure and Function during the Postpartum Period

PubMed Central

Leuner, Benedetta; Fredericks, Peter J.; Nealer, Connor; Albin-Brooks, Christopher

2014-01-01

Postpartum depression, which affects approximately 15% of new mothers, is associated with impaired mother-infant interactions and deficits in cognitive function. Exposure to stress during pregnancy is a major risk factor for postpartum depression. However, little is known about the neural consequences of gestational stress. The medial prefrontal cortex (mPFC) is a brain region that has been linked to stress, cognition, maternal care, and mood disorders including postpartum depression. Here we examined the effects of chronic gestational stress on mPFC function and whether these effects might be linked to structural modifications in the mPFC. We found that in postpartum rats, chronic gestational stress resulted in maternal care deficits, increased depressive-like behavior, and impaired performance on an attentional set shifting task that relies on the mPFC. Furthermore, exposure to chronic stress during pregnancy reduced dendritic spine density on mPFC pyramidal neurons and altered spine morphology. Taken together, these findings suggest that pregnancy stress may contribute to postpartum mental illness and its associated symptoms by compromising structural plasticity in the mPFC. PMID:24594708

Stress Intensity Factors for Cracking Metal Structures under Rapid Thermal Loading. Volume 2. Theoretical Background

DTIC Science & Technology

1989-08-01

thermal pulse loadings. The work couples a Green’s function integration technique for transient thermal stresses with the well-known influence ... function approach for calculating stress intensity factors. A total of seven most commonly used crack models were investigated in this study. A computer

Posttraumatic stress and functional impairment in Kenyan children following the 1998 American Embassy bombing.

PubMed

Pfefferbaum, Betty; North, Carol S; Doughty, Debby E; Gurwitch, Robin H; Fullerton, Carol S; Kyula, Jane

2003-04-01

This study examined a convenience sample of 562 Nairobi school children exposed to the 1998 bombing of the American Embassy in Nairobi, Kenya. Posttraumatic stress reactions to the bombing were related to posttraumatic stress reactions to other trauma and to peritraumatic reaction. Self-reported functional impairment was minimal.

Stress and Social Support in Parents of Hyperactive Children.

ERIC Educational Resources Information Center

Miner, Joanne

The role of social support in moderating stress was examined in 65 parents of hyperactive children. The sample included 29 couples and 7 single mothers. The theoretical framework guiding the research was Lazarus' general model of stress. Each parent's psychological functioning was hypothesized to be a function of the severity of the child's…

Teacher Stress Predicts Child Executive Function: Moderation by School Poverty

ERIC Educational Resources Information Center

Neuenschwander, Regula; Friedman-Krauss, Allison; Raver, Cybele; Blair, Clancy

2017-01-01

Research Findings: Recent research has explored relations between classroom quality and child executive function (EF), but little is known about how teachers' well-being, including stress, relates to child EF--a crucial component of self-regulation. We hypothesized that teacher stress is negatively or curvilinearly related to child EF and…

Relationship of Stress, Leukocyte Functions and Acute Ulcerative Gingivitis.

DTIC Science & Technology

1982-10-22

IONAL 1jjl (I Y AN[)AAU> I,)(, 4 •. . . . .i -AD (Report Number 3 , Lf) RELATIONSHIP OF STRESS, LEUKOCYTE FUNCTION AND ACUTE ULCERATIVE GINGIVITIS...AIk £It. KEY WORDS (C~mntm. a reers old. A *1acoa and Identit by block number) Acute Necrotic Ulcerative Gingivitis (ANUG)), Stress 4 Leukocyte

Transactional relations between caregiving stress, executive functioning, and problem behavior from early childhood to early adolescence

PubMed Central

LaGasse, Linda L.; Conradt, Elisabeth; Karalunas, Sarah L.; Dansereau, Lynne M.; Butner, Jonathan E.; Shankaran, Seetha; Bada, Henrietta; Bauer, Charles R.; Whitaker, Toni M.; Lester, Barry M.

2016-01-01

Developmental psychopathologists face the difficult task of identifying the environmental conditions that may contribute to early childhood behavior problems. Highly stressed caregivers can exacerbate behavior problems, while children with behavior problems may make parenting more difficult and increase caregiver stress. Unknown is: (1) how these transactions originate, (2) whether they persist over time to contribute to the development of problem behavior and (3) what role resilience factors, such as child executive functioning, may play in mitigating the development of problem behavior. In the present study, transactional relations between caregiving stress, executive functioning, and behavior problems were examined in a sample of 1,388 children with prenatal drug exposures at three developmental time points: early childhood (birth-age 5), middle childhood (ages 6 to 9), and early adolescence (ages 10 to 13). Transactional relations differed between caregiving stress and internalizing versus externalizing behavior. Targeting executive functioning in evidence-based interventions for children with prenatal substance exposure who present with internalizing problems and treating caregiving psychopathology, depression, and parenting stress in early childhood may be particularly important for children presenting with internalizing behavior. PMID:27427803

Relations between cognitive functioning and alcohol use, craving, and posttraumatic stress: An examination among trauma exposed military Veterans with alcohol use disorder

PubMed Central

Heinz, Adrienne J.; Pennington, David L.; Cohen, Nicole; Schmeling, Brandi; Lasher, Brooke A.; Schrodek, Emily; Batki, Steven L.

2015-01-01

Cognitive dysfunction is commonly observed among individuals with Alcohol Use Disorder (AUD) and trauma exposure and is, in turn, associated with worse clinical outcomes. Accordingly, disruptions in cognitive functioning may be conceptualized as a trans-disease phenomenon representing a potential high-yield target for intervention. Less is known though about how different cognitive functions co-vary with alcohol use, craving, and posttraumatic stress symptom severity among trauma exposed individuals with AUD. Sixty-eight male and female trauma exposed military Veterans with AUD, entering treatment trials to reduce alcohol use, completed measures assessing alcohol use and craving, posttraumatic stress symptom severity, and cognitive functioning. In multivariate models, after controlling for posttraumatic stress symptom severity, poorer learning and memory was associated with higher alcohol consumption and higher risk-taking/impulsivity was associated with stronger pre-occupations with alcohol and compulsions to drink. Alcohol consumption and craving, but not performance on cognitive tests, were positively associated with posttraumatic stress symptom severity. Findings suggest that interventions to strengthen cognitive functioning might be used as a preparatory step to augment treatments for AUD. Clinicians are encouraged to consider a standard assessment of cognitive functioning, in addition to posttraumatic stress symptom severity, in treatment planning and delivery for this vulnerable and high-risk population. PMID:27391620

Glucocorticoids, stress, and fertility.

PubMed

Whirledge, S; Cidlowski, J A

2010-06-01

Modifications of the hypothalamo-pituitary-adrenal axis and associated changes in circulating levels of glucocorticoids form a key component of the response of an organism to stressful challenges. Increased levels of glucocorticoids promote gluconeogenesis, mobilization of amino acids, and stimulation of fat breakdown to maintain circulating levels of glucose necessary to mount a stress response. In addition to profound changes in the physiology and function of multiple tissues, stress and elevated glucocorticoids can also inhibit reproduction, a logical effect for the survival of self. Precise levels of glucocorticoids are required for proper gonadal function; where the balance is disrupted, so is fertility. Glucocorticoids affect gonadal function at multiple levels in hypothalamo-pituitary-gonadal axis: 1) the hypothalamus (to decrease the synthesis and release of gonadotropin-releasing hormone [GnRH]); 2) the pituitary gland (to inhibit the synthesis and release of luteinizing hormone [LH] and follicle stimulating hormone [FSH]); 3) the testis/ovary (to modulate steroidogenesis and/or gametogenesis directly). Furthermore, maternal exposure to prenatal stress or exogenous glucocorticoids can lead to permanent modification of hypothalamo-pituitary-adrenal function and stress-related behaviors in offspring. Glucocorticoids are vital to many aspects of normal brain development, but fetal exposure to superabundant glucocorticoids can result in life-long effects on neuroendocrine function. This review focuses on the molecular mechanisms believed to mediate glucocorticoid inhibition of reproductive functions and the anatomical sites at which these effects take place.

Long-term Effects of Psychosocial Work Stress in Midlife on Health Functioning After Labor Market Exit—Results From the GAZEL Study

PubMed Central

Sembajwe, Grace; Zins, Marie; Berkman, Lisa; Goldberg, Marcel; Siegrist, Johannes

2012-01-01

Objectives. To study long-term effects of psychosocial work stress in mid-life on health functioning after labor market exit using two established work stress models. Methods. In the frame of the prospective French Gazel cohort study, data on psychosocial work stress were assessed using the full questionnaires measuring the demand-control-support model (in 1997 and 1999) and the effort–reward imbalance model (in 1998). In 2007, health functioning was assessed, using the Short Form 36 mental and physical component scores. Multivariate regressions were calculated to predict health functioning in 2007, controlling for age, gender, social position, and baseline self-perceived health. Results. Consistent effects of both work stress models and their single components on mental and physical health functioning during retirement were observed. Effects remained significant after adjustment including baseline self-perceived health. Whereas the predictive power of both work stress models was similar in the case of the physical composite score, in the case of the mental health score, values of model fit were slightly higher for the effort–reward imbalance model (R²: 0.13) compared with the demand-control model (R²: 0.11). Conclusions. Findings underline the importance of working conditions in midlife not only for health in midlife but also for health functioning after labor market exit. PMID:22546992

Stress perception and depressive symptoms: functionality and impact on the quality of life of women with fibromyalgia.

PubMed

Homann, Diogo; Stefanello, Joice Mara Facco; Góes, Suelen Meira; Breda, Chris Andreissy; Paiva, Eduardo dos Santos; Leite, Neiva

2012-01-01

Depression is one of the most frequent psychiatric comorbidities in patients with fibromyalgia (FM), and chronic stress might be one of the triggering events of the characteristic FM symptoms. To compare depressive symptoms and stress perception between women with and without FM, in addition to investigate the relationship between those characteristics and the functionality and the impact on the quality of life of those patients. The study included 20 women with FM (FM group) and 20 healthy women (control group). The following instruments were used: Beck Depression Inventory, Perceived Stress Scale-10, Health Assessment Questionnaire, Fibromyalgia Impact Questionnaire, and Visual Analogue Scale for pain (0-10 cm). The FM group showed higher severity of the depressive symptoms (24.10 ± 11.68) and greater perception of stress (25.10 ± 4.82) as compared with those of the control group (10.20 ± 12.78, P < 0.01;and 15.45 ± 7.29, P < 0.01;respectively). A higher incidence of depressive symptoms was observed in the FM group (75%) than in the control group (25%) (χ² = 10.00, P < 0.01). In the FM group, a positive correlation was observed between the depressive symptoms and perceived stress (r = 0.54, P < 0.05), pain (r = 0.58, P < 0.01), impaired functionality (r = 0.56, P < 0.01), and impact on the quality of life (r = 0.46, P < 0.05). In this group there was also correlation between perceived stress and impaired functionality (r = 0.50;P < 0.05). Pain showed no relationship with perceived stress. The relationship between stress, depression and functionality seems to be part of a complex mechanism, which might affect the quality of life of patients with FM.

Complex interplay between health and successful aging: role of perceived stress, resilience, and social support.

PubMed

Moore, Raeanne C; Eyler, Lisa T; Mausbach, Brent T; Zlatar, Zvinka Z; Thompson, Wesley K; Peavy, Guerry; Fazeli, Pariya L; Jeste, Dilip V

2015-06-01

Psychological and psychosocial resources, including resilience and social support, have traditionally been studied in the context of the stress paradigm and, more recently, in the context of successful aging. This study used moderated mediation analyses to examine the role of perceived stress in the relationships between physical and mental health functioning and self-rated successful aging (SRSA) and whether differences between people in level of resilience and social support changes the role of perceived stress in these relationships. A cross-sectional study of 1,006 older adults (mean age: 77 years) completed scales addressing SRSA, physical and mental health functioning, perceived stress, resilience, and social support. Results indicated that the strength of relationships between both physical and mental health functioning and SRSA were reduced after accounting for variation in level of perceived stress. The role of perceived stress in the association between mental health functioning and SRSA was found to be stronger among participants with the highest levels of resilience, and the influence of perceived stress on the degree of relationship between physical health functioning and SRSA was stronger among those with greatest social support. These findings suggest that interventions to reduce perceived stress may help break the link between disability and poor well-being in older adults. The findings further suggest that the impact of such interventions might differ depending on psychological resources (i.e., resilience) for mental health disabilities and external resources (i.e., social support) for those with physical health problems. The complex interplay of these factors should be taken into account in clinical settings. Copyright © 2015 American Association for Geriatric Psychiatry. All rights reserved.

Prevention of psychological stress-induced immune suppression by aged garlic extract.

PubMed

Kyo, E; Uda, N; Ushijima, M; Kasuga, S; Itakura, Y

1999-11-01

We determined the effect of Aged Garlic Extract (AGE) on damage caused to immune function by a psychological stress using a communication box. After four days of a psychological stress, a decrease in spleen weight and spleen cells was observed in the psychological stress-exposed mice as compared normal mice (non-stress). AGE significantly prevented the decreases in spleen weight and cells. Additionally, AGE significantly prevented the reduction of hemolytic plaque-forming-cells in spleen cells and anti-SRBC antibody titer in serum caused by this psychological stress. Moreover, a reduction in NK activities was observed in the psychological stress-exposed mice as compared with normal mice (non-stress), whereas NK activities in the AGE administered mice were almost the same as normal mice (non-stress). These results indicate that psychological stress qualitatively and quantitatively impairs immune function, and that AGE is extremely useful for preventing psychologically-induced damage.

Behavioral stress alters corticolimbic microglia in a sex- and brain region-specific manner.

PubMed

Bollinger, Justin L; Collins, Kaitlyn E; Patel, Rushi; Wellman, Cara L

2017-01-01

Women are more susceptible to numerous stress-linked psychological disorders (e.g., depression) characterized by dysfunction of corticolimbic brain regions critical for emotion regulation and cognitive function. Although sparsely investigated, a number of studies indicate sex differences in stress effects on neuronal structure, function, and behaviors associated with these regions. We recently demonstrated a basal sex difference in- and differential effects of stress on- microglial activation in medial prefrontal cortex (mPFC). The resident immune cells of the brain, microglia are implicated in synaptic and dendritic plasticity, and cognitive-behavioral function. Here, we examined the effects of acute (3h/day, 1 day) and chronic (3h/day, 10 days) restraint stress on microglial density and morphology, as well as immune factor expression in orbitofrontal cortex (OFC), basolateral amygdala (BLA), and dorsal hippocampus (DHC) in male and female rats. Microglia were visualized, classified based on their morphology, and stereologically counted. Microglia-associated transcripts (CD40, iNOS, Arg1, CX3CL1, CX3CR1, CD200, and CD200R) were assessed in brain punches from each region. Expression of genes linked with cellular stress, neuroimmune state, and neuron-microglia communication varied between unstressed male and female rats in a region-specific manner. In OFC, chronic stress upregulated a wider variety of immune factors in females than in males. Acute stress increased microglia-associated transcripts in BLA in males, whereas chronic stress altered immune factor expression in BLA more broadly in females. In DHC, chronic stress increased immune factor expression in males but not females. Moreover, acute and chronic stress differentially affected microglial morphological activation state in male and female rats across all brain regions investigated. In males, chronic stress altered microglial activation in a pattern consistent with microglial involvement in stress-induced dendritic remodeling across OFC, BLA, and DHC. Together, these data suggest the potential for microglia-mediated sex differences in stress effects on neural structure, function, and behavior.

Behavioral stress alters corticolimbic microglia in a sex- and brain region-specific manner

PubMed Central

Bollinger, Justin L.; Collins, Kaitlyn E.; Patel, Rushi

2017-01-01

Women are more susceptible to numerous stress-linked psychological disorders (e.g., depression) characterized by dysfunction of corticolimbic brain regions critical for emotion regulation and cognitive function. Although sparsely investigated, a number of studies indicate sex differences in stress effects on neuronal structure, function, and behaviors associated with these regions. We recently demonstrated a basal sex difference in- and differential effects of stress on- microglial activation in medial prefrontal cortex (mPFC). The resident immune cells of the brain, microglia are implicated in synaptic and dendritic plasticity, and cognitive-behavioral function. Here, we examined the effects of acute (3h/day, 1 day) and chronic (3h/day, 10 days) restraint stress on microglial density and morphology, as well as immune factor expression in orbitofrontal cortex (OFC), basolateral amygdala (BLA), and dorsal hippocampus (DHC) in male and female rats. Microglia were visualized, classified based on their morphology, and stereologically counted. Microglia-associated transcripts (CD40, iNOS, Arg1, CX3CL1, CX3CR1, CD200, and CD200R) were assessed in brain punches from each region. Expression of genes linked with cellular stress, neuroimmune state, and neuron-microglia communication varied between unstressed male and female rats in a region-specific manner. In OFC, chronic stress upregulated a wider variety of immune factors in females than in males. Acute stress increased microglia-associated transcripts in BLA in males, whereas chronic stress altered immune factor expression in BLA more broadly in females. In DHC, chronic stress increased immune factor expression in males but not females. Moreover, acute and chronic stress differentially affected microglial morphological activation state in male and female rats across all brain regions investigated. In males, chronic stress altered microglial activation in a pattern consistent with microglial involvement in stress-induced dendritic remodeling across OFC, BLA, and DHC. Together, these data suggest the potential for microglia-mediated sex differences in stress effects on neural structure, function, and behavior. PMID:29194444

Effect of acute acoustic stress on anorectal function sensation in healthy human.

PubMed

Gonlachanvit, S; Rhee, J; Sun, W M; Chey, W D

2005-04-01

Little is known about the effects of acute acoustic stress on anorectal function. To determine the effects of acute acoustic stress on anorectal function and sensation in healthy volunteers. Ten healthy volunteers (7 M, 3 F, mean age 34 +/- 3 years) underwent anorectal manometry, testing of rectal compliance and sensation using a barostat with and without acute noise stress on separate days. Rectal perception was assessed using an ascending method of limits protocol and a 5-point Likert scale. Arousal and anxiety status were evaluated using a visual analogue scale. Acoustic stress significantly increased anxiety score (P < 0.05). Rectal compliance was significantly decreased with acoustic stress compared with control P (P < 0.000001). In addition, less intraballoon volume was needed to induce the sensation of severe urgency with acoustic stress (P < 0.05). Acoustic stress had no effect on hemodynamic parameters, anal sphincter pressure, threshold for first sensation, sensation of stool, or pain. Acute acoustic stimulation increased anxiety scores, decreased rectal compliance, and enhanced perception of severe urgency to balloon distention but did not affect anal sphincter pressure in healthy volunteers. These results may offer insight into the pathogenesis of stress-in-induced diarrhoea and faecal urgency.

Mindfulness meditation training alters stress-related amygdala resting state functional connectivity: a randomized controlled trial

PubMed Central

Taren, Adrienne A.; Gianaros, Peter J.; Greco, Carol M.; Lindsay, Emily K.; Fairgrieve, April; Brown, Kirk Warren; Rosen, Rhonda K.; Ferris, Jennifer L.; Julson, Erica; Marsland, Anna L.; Bursley, James K.; Ramsburg, Jared

2015-01-01

Recent studies indicate that mindfulness meditation training interventions reduce stress and improve stress-related health outcomes, but the neural pathways for these effects are unknown. The present research evaluates whether mindfulness meditation training alters resting state functional connectivity (rsFC) of the amygdala, a region known to coordinate stress processing and physiological stress responses. We show in an initial discovery study that higher perceived stress over the past month is associated with greater bilateral amygdala-subgenual anterior cingulate cortex (sgACC) rsFC in a sample of community adults (n = 130). A follow-up, single-blind randomized controlled trial shows that a 3-day intensive mindfulness meditation training intervention (relative to a well-matched 3-day relaxation training intervention without a mindfulness component) reduced right amygdala-sgACC rsFC in a sample of stressed unemployed community adults (n = 35). Although stress may increase amygdala-sgACC rsFC, brief training in mindfulness meditation could reverse these effects. This work provides an initial indication that mindfulness meditation training promotes functional neuroplastic changes, suggesting an amygdala-sgACC pathway for stress reduction effects. PMID:26048176

Predictable chronic mild stress improves mood, hippocampal neurogenesis and memory.

PubMed

Parihar, V K; Hattiangady, B; Kuruba, R; Shuai, B; Shetty, A K

2011-02-01

Maintenance of neurogenesis in adult hippocampus is important for functions such as mood and memory. As exposure to unpredictable chronic stress (UCS) results in decreased hippocampal neurogenesis, enhanced depressive- and anxiety-like behaviors, and memory dysfunction, it is believed that declined hippocampal neurogenesis mainly underlies the behavioral and cognitive abnormalities after UCS. However, the effects of predictable chronic mild stress (PCMS) such as the routine stress experienced in day-to-day life on functions such as mood, memory and hippocampal neurogenesis are unknown. Using FST and EPM tests on a prototype of adult rats, we demonstrate that PCMS (comprising 5 min of daily restraint stress for 28 days) decreases depressive- and anxiety-like behaviors for prolonged periods. Moreover, we illustrate that decreased depression and anxiety scores after PCMS are associated with ~1.8-fold increase in the production and growth of new neurons in the hippocampus. Additionally, we found that PCMS leads to enhanced memory function in WMT as well as NORT. Collectively, these findings reveal that PCMS is beneficial to adult brain function, which is exemplified by increased hippocampal neurogenesis and improved mood and cognitive function.

Functional Connectivity During Exposure to Favorite-Food, Stress, and Neutral-Relaxing Imagery Differs Between Smokers and Nonsmokers.

PubMed

Garrison, Kathleen A; Sinha, Rajita; Lacadie, Cheryl M; Scheinost, Dustin; Jastreboff, Ania M; Constable, R Todd; Potenza, Marc N

2016-09-01

Tobacco-use disorder is a complex condition involving multiple brain networks and presenting with multiple behavioral correlates including changes in diet and stress. In a previous functional magnetic resonance imaging (fMRI) study of neural responses to favorite-food, stress, and neutral-relaxing imagery, smokers versus nonsmokers demonstrated blunted corticostriatal-limbic responses to favorite-food cues. Based on other recent reports of alterations in functional brain networks in smokers, the current study examined functional connectivity during exposure to favorite-food, stress, and neutral-relaxing imagery in smokers and nonsmokers, using the same dataset. The intrinsic connectivity distribution was measured to identify brain regions that differed in degree of functional connectivity between groups during each imagery condition. Resulting clusters were evaluated for seed-to-voxel connectivity to identify the specific connections that differed between groups during each imagery condition. During exposure to favorite-food imagery, smokers versus nonsmokers showed lower connectivity in the supramarginal gyrus, and differences in connectivity between the supramarginal gyrus and the corticostriatal-limbic system. During exposure to neutral-relaxing imagery, smokers versus nonsmokers showed greater connectivity in the precuneus, and greater connectivity between the precuneus and the posterior insula and rolandic operculum. During exposure to stress imagery, smokers versus nonsmokers showed lower connectivity in the cerebellum. These findings provide data-driven insights into smoking-related alterations in brain functional connectivity patterns related to appetitive, relaxing, and stressful states. This study uses a data-driven approach to demonstrate that smokers and nonsmokers show differential patterns of functional connectivity during guided imagery related to personalized favorite-food, stress, and neutral-relaxing cues, in brain regions implicated in attention, reward-related, emotional, and motivational processes. For smokers, these differences in connectivity may impact appetite, stress, and relaxation, and may interfere with smoking cessation. © The Author 2016. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Functional Connectivity During Exposure to Favorite-Food, Stress, and Neutral-Relaxing Imagery Differs Between Smokers and Nonsmokers

PubMed Central

Sinha, Rajita; Lacadie, Cheryl M.; Scheinost, Dustin; Jastreboff, Ania M.; Constable, R. Todd; Potenza, Marc N.

2016-01-01

Introduction: Tobacco-use disorder is a complex condition involving multiple brain networks and presenting with multiple behavioral correlates including changes in diet and stress. In a previous functional magnetic resonance imaging (fMRI) study of neural responses to favorite-food, stress, and neutral-relaxing imagery, smokers versus nonsmokers demonstrated blunted corticostriatal-limbic responses to favorite-food cues. Based on other recent reports of alterations in functional brain networks in smokers, the current study examined functional connectivity during exposure to favorite-food, stress, and neutral-relaxing imagery in smokers and nonsmokers, using the same dataset. Methods: The intrinsic connectivity distribution was measured to identify brain regions that differed in degree of functional connectivity between groups during each imagery condition. Resulting clusters were evaluated for seed-to-voxel connectivity to identify the specific connections that differed between groups during each imagery condition. Results: During exposure to favorite-food imagery, smokers versus nonsmokers showed lower connectivity in the supramarginal gyrus, and differences in connectivity between the supramarginal gyrus and the corticostriatal-limbic system. During exposure to neutral-relaxing imagery, smokers versus nonsmokers showed greater connectivity in the precuneus, and greater connectivity between the precuneus and the posterior insula and rolandic operculum. During exposure to stress imagery, smokers versus nonsmokers showed lower connectivity in the cerebellum. Conclusions: These findings provide data-driven insights into smoking-related alterations in brain functional connectivity patterns related to appetitive, relaxing, and stressful states. Implications: This study uses a data-driven approach to demonstrate that smokers and nonsmokers show differential patterns of functional connectivity during guided imagery related to personalized favorite-food, stress, and neutral-relaxing cues, in brain regions implicated in attention, reward-related, emotional, and motivational processes. For smokers, these differences in connectivity may impact appetite, stress, and relaxation, and may interfere with smoking cessation. PMID:26995796

Assessing the Functional Role of Leptin in Energy Homeostasis and the Stress Response in Vertebrates

PubMed Central

Deck, Courtney A.; Honeycutt, Jamie L.; Cheung, Eugene; Reynolds, Hannah M.; Borski, Russell J.

2017-01-01

Leptin is a pleiotropic hormone that plays a critical role in regulating appetite, energy metabolism, growth, stress, and immune function across vertebrate groups. In mammals, it has been classically described as an adipostat, relaying information regarding energy status to the brain. While retaining poor sequence conservation with mammalian leptins, teleostean leptins elicit a number of similar regulatory properties, although current evidence suggests that it does not function as an adipostat in this group of vertebrates. Teleostean leptin also exhibits functionally divergent properties, however, possibly playing a role in glucoregulation similar to what is observed in lizards. Further, leptin has been recently implicated as a mediator of immune function and the endocrine stress response in teleosts. Here, we provide a review of leptin physiology in vertebrates, with a particular focus on its actions and regulatory properties in the context of stress and the regulation of energy homeostasis. PMID:28439255

Effect of yeast (Xanthophyllomyces dendrorhous) and plant (Saint John's wort, lemon balm, and rosemary) extract based functional diets on antioxidant and immune status of Atlantic salmon (Salmo salar) subjected to crowding stress.

PubMed

Reyes-Cerpa, Sebastián; Vallejos-Vidal, Eva; Gonzalez-Bown, María José; Morales-Reyes, Jonathan; Pérez-Stuardo, Diego; Vargas, Deborah; Imarai, Mónica; Cifuentes, Víctor; Spencer, Eugenio; Sandino, Ana María; Reyes-López, Felipe E

2018-03-01

Salmon farming may face stress due to the intensive culture conditions with negative impacts on overall performance. In this aspect, functional feed improves not only the basic nutritional requirements but also the health status and fish growth. However, to date no studies have been carried out to evaluate the effect of functional diets in salmon subjected to crowding stress. Thus, the aim of this study was to evaluate the effect of yeast extract (Xanthophyllomyces dendrorhous; diet A) and the combination of plant extracts (common Saint John's wort, lemon balm, and rosemary; diet B) on the antioxidant and immune status of Atlantic salmon grown under normal cultured conditions and then subjected to crowding stress. Fish were fed with functional diets during 30 days (12 kg/m 3 ) and then subjected to crowding stress (20 kg/m 3 ) for 10 days. The lipid peroxidation in gut showed that both diets induced a marked decrease on oxidative damage when fish were subjected to crowding stress. The protein carbonylation in muscle displayed at day 30 a marked decrease in both functional diets that was more marked on the stress condition. The expression of immune markers (IFNγ, CD4, IL-10, TGF-β, IgM mb , IgM sec , T-Bet, and GATA-3) indicated the upregulation of those associated to humoral-like response (CD4, IL-10, GATA-3) when fish were subjected to crowding stress. These results were confirmed with the expression of secreted IgM. Altogether, these functional diets improved the antioxidant status and increased the expression of genes related to Th2-like response suggesting a protective role on fish subjected to crowding stress. Copyright © 2017. Published by Elsevier Ltd.

Are there gender differences in cognitive function, chronic stress, and neurobehavioral symptoms after mild-to-moderate traumatic brain injury?

PubMed

Covassin, Tracey; Bay, Esther

2012-06-01

Research is inconclusive on whether gender differences exist in cognitive function in persons who sustain a mild-to-moderate traumatic brain injury (TBI). Furthermore, it is also unclear whether there is a relationship between chronic stress and cognitive function in these persons. The purpose of this integrative review is to determine whether gender differences exist in cognitive function, neurobehavioral symptoms, and chronic stress levels after a mild-to-moderate TBI. Participants (n = 72) were recruited from eight outpatient rehabilitation centers. Participants completed the demographic questions, the Immediate Postconcussion Assessment Cognitive Testing neurocognitive test battery, the Perceived Stress Scale-14, and the Neurobehavioral Functioning Inventory (NFI). Gender differences were present on verbal memory composite scores (p = .033), with women performing worse than men. There were no other between-gender differences on cognitive tasks, neurobehavioral symptoms, or chronic stress. Higher chronic stress levels result in a decrease in verbal memory (p = .015) and motor processing speed (p = .006) and slower reaction time (p = .007) for women. As male NFI cognition scores increased, motor processing speed scores decreased (p = .012) and reaction time got slower (p = .019), whereas women exhibited decreased verbal memory (p = .017) and slower reaction time (p = .034). As NFI motor symptoms increased, men exhibited decreased verbal memory (p = .005), visual memory (p = .002), and motor processing speed (p = .002) and slower reaction time (p = .002). Overall, this study only found gender differences on verbal memory composite scores, whereas the remaining cognitive tasks, neurobehavioral symptoms, and chronic stress did not indicate gender differences. Correlations between chronic stress, neurobehavioral symptoms, and cognitive function differed in both men and women with TBI. Persons in the chronic phase of recovery from a TBI may benefit from training in compensatory strategies for verbal memory deficits and stress management.

Stress and adolescent hippocampal neurogenesis: diet and exercise as cognitive modulators

PubMed Central

Hueston, C M; Cryan, J F; Nolan, Y M

2017-01-01

Adolescence is a critical period for brain maturation. Deciphering how disturbances to the central nervous system at this time affect structure, function and behavioural outputs is important to better understand any long-lasting effects. Hippocampal neurogenesis occurs during development and continues throughout life. In adulthood, integration of these new cells into the hippocampus is important for emotional behaviour, cognitive function and neural plasticity. During the adolescent period, maturation of the hippocampus and heightened levels of hippocampal neurogenesis are observed, making alterations to neurogenesis at this time particularly consequential. As stress negatively affects hippocampal neurogenesis, and adolescence is a particularly stressful time of life, it is important to investigate the impact of stressor exposure at this time on hippocampal neurogenesis and cognitive function. Adolescence may represent not only a time for which stress can have long-lasting effects, but is also a critical period during which interventions, such as exercise and diet, could ameliorate stress-induced changes to hippocampal function. In addition, intervention at this time may also promote life-long behavioural changes that would aid in fostering increased hippocampal neurogenesis and cognitive function. This review addresses both the acute and long-term stress-induced alterations to hippocampal neurogenesis and cognition during the adolescent period, as well as changes to the stress response and pubertal hormones at this time which may result in differential effects than are observed in adulthood. We hypothesise that adolescence may represent an optimal time for healthy lifestyle changes to have a positive and long-lasting impact on hippocampal neurogenesis, and to protect against stress-induced deficits. We conclude that future research into the mechanisms underlying the susceptibility of the adolescent hippocampus to stress, exercise and diet and the consequent effect on cognition may provide insight into why adolescence may be a vital period for correct conditioning of future hippocampal function. PMID:28375209

Stress and adolescent hippocampal neurogenesis: diet and exercise as cognitive modulators.

PubMed

Hueston, C M; Cryan, J F; Nolan, Y M

2017-04-04

Adolescence is a critical period for brain maturation. Deciphering how disturbances to the central nervous system at this time affect structure, function and behavioural outputs is important to better understand any long-lasting effects. Hippocampal neurogenesis occurs during development and continues throughout life. In adulthood, integration of these new cells into the hippocampus is important for emotional behaviour, cognitive function and neural plasticity. During the adolescent period, maturation of the hippocampus and heightened levels of hippocampal neurogenesis are observed, making alterations to neurogenesis at this time particularly consequential. As stress negatively affects hippocampal neurogenesis, and adolescence is a particularly stressful time of life, it is important to investigate the impact of stressor exposure at this time on hippocampal neurogenesis and cognitive function. Adolescence may represent not only a time for which stress can have long-lasting effects, but is also a critical period during which interventions, such as exercise and diet, could ameliorate stress-induced changes to hippocampal function. In addition, intervention at this time may also promote life-long behavioural changes that would aid in fostering increased hippocampal neurogenesis and cognitive function. This review addresses both the acute and long-term stress-induced alterations to hippocampal neurogenesis and cognition during the adolescent period, as well as changes to the stress response and pubertal hormones at this time which may result in differential effects than are observed in adulthood. We hypothesise that adolescence may represent an optimal time for healthy lifestyle changes to have a positive and long-lasting impact on hippocampal neurogenesis, and to protect against stress-induced deficits. We conclude that future research into the mechanisms underlying the susceptibility of the adolescent hippocampus to stress, exercise and diet and the consequent effect on cognition may provide insight into why adolescence may be a vital period for correct conditioning of future hippocampal function.

The Dichotomous Effect of Chronic Stress on Obesity.

PubMed

Razzoli, Maria; Bartolomucci, Alessandro

2016-07-01

Obesity and metabolic diseases are linked to chronic stress and low socioeconomic status. The mechanistic link between stress and obesity has not been clarified, partly due to the inherent complexity exemplified by the bidirectional effect of stress on eating and body weight. Recent studies focusing on adaptive thermogenesis and brown adipose tissue (BAT) function support a dichotomous relation to explain the impact of stress on obesity: stress promotes obesity in the presence of hyperphagia and unchanged BAT function; stress results in weight loss and/or obesity resistance in the presence of hypophagia, or when hyperphagia is associated with BAT recruitment and enhanced thermogenesis. Mechanistically dissecting the bidirectional effects of stress on metabolic outcomes might open new avenues for innovative pharmacotherapies for the treatment of obesity-associated diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.

The dichotomous effect of chronic stress on obesity

PubMed Central

Razzoli, Maria; Bartolomucci, Alessandro

2016-01-01

Obesity and metabolic diseases are linked to chronic stress and low socio-economic status. The mechanistic link between stress and obesity has not been clarified, partly due to the inherent complexity exemplified by the bidirectional effect of stress on eating and body weight. Recent studies focusing on adaptive-thermogenesis and brown adipose tissue (BAT) function support a dichotomous relationship to explain the impact of stress on obesity: stress promotes obesity in the presence of hyperphagia and unchanged BAT function; stress results in weight-loss/obesity-resistance in the presence of hypophagia, or when hyperphagia is associated with BAT recruitment and enhanced thermogenesis. Mechanistically dissecting the bidirectional effects of stress on metabolic outcomes might open new avenues for innovative pharmacotherapies for the treatment of obesity-associated diseases. PMID:27162125

Production of functional proteins: balance of shear stress and gravity

NASA Technical Reports Server (NTRS)

Kaysen, James Howard (Inventor); Hammond, Timothy Grant (Inventor); Goodwin, Thomas John (Inventor)

2011-01-01

A method for the production of functional proteins including hormones by renal cells in a three dimensional culturing process responsive to shear stress uses a rotating wall vessel. Natural mixture of renal cells expresses the enzyme 1-.alpha.-hydroxylase which can be used to generate the active form of vitamin D: 1,25-diOH vitamin D.sub.3. The fibroblast cultures and co-culture of renal cortical cells express the gene for erythropoietin and secrete erythropoietin into the culture supernatant. Other shear stress response genes are also modulated by shear stress, such as toxin receptors megalin and cubulin (gp280). Also provided is a method of treating an in-need individual with the functional proteins produced in a three dimensional co-culture process responsive to shear stress using a rotating wall vessel.

4-Phenylbutyrate Benefits Traumatic Hemorrhagic Shock in Rats by Attenuating Oxidative Stress, Not by Attenuating Endoplasmic Reticulum Stress.

PubMed

Yang, Guangming; Peng, Xiaoyong; Hu, Yi; Lan, Dan; Wu, Yue; Li, Tao; Liu, Liangming

2016-07-01

Vascular dysfunction such as vascular hyporeactivity following severe trauma and shock is a major cause of death in injured patients. Oxidative stress and endoplasmic reticulum stress play an important role in vascular dysfunction. The objective of the present study was to determine whether or not 4-phenylbutyrate can improve vascular dysfunction and elicit antishock effects by inhibiting oxidative and endoplasmic reticulum stress. Prospective, randomized, controlled laboratory experiment. State key laboratory of trauma, burns, and combined injury. Five hundred and fifty-two Sprague-Dawley rats. Rats were anesthetized, and a model of traumatic hemorrhagic shock was established by left femur fracture and hemorrhage. The effects of 4-phenylbutyrate (5, 20, 50, 100, 200, and 300 mg/kg) on vascular reactivity, animal survival, hemodynamics, and vital organ function in traumatic hemorrhagic shock rats and cultured vascular smooth muscle cells, and the relationship to oxidative stress and endoplasmic reticulum stress was observed. Lower doses of 4-phenylbutyrate significantly improved the vascular function, stabilized the hemodynamics, and increased the tissue blood flow and vital organ function in traumatic hemorrhagic shock rats, and markedly improved the survival outcomes. Among all dosages observed in the present study, 20 mg/kg of 4-phenylbutyrate had the best effect. Further results indicated that 4-phenylbutyrate significantly inhibited the oxidative stress, decreased shock-induced oxidative stress index such as the production of reactive oxygen species, increased the antioxidant enzyme levels such as superoxide dismutase, catalase, and glutathione, and improved the mitochondrial function by inhibiting the opening of the mitochondrial permeability transition pore in rat artery and vascular smooth muscle cells. In contrast, 4-phenylbutyrate did not affect the changes of endoplasmic reticulum stress markers following traumatic hemorrhagic shock. Furthermore, 4-phenylbutyrate increased the nuclear levels of nuclear factor-E2-related factor 2, and decreased the nuclear levels of nuclear factor κB in hypoxic vascular smooth muscle cells. 4-phenylbutyrate has beneficial effects for traumatic hemorrhagic shock including improving animal survival and protecting organ function. These beneficial effects of 4-phenylbutyrate in traumatic hemorrhagic shock result from its vascular function protection via attenuation of the oxidative stress and mitochondrial permeability transition pore opening. Nuclear factor-E2-related factor 2 and nuclear factor-κB may be involved in 4-phenylbutyrate-mediated inhibition of oxidative stress.

Stress as a one-armed bandit: Differential effects of stress paradigms on the morphology, neurochemistry and behavior in the rodent amygdala

PubMed Central

Wilson, Marlene A.; Grillo, Claudia A.; Fadel, Jim R.; Reagan, Lawrence P.

2015-01-01

Neuroplasticity may be defined as the ability of the central nervous system (CNS) to respond to changes in the internal and external environment and it is well established that some stimuli have the ability to facilitate or impair neuroplasticity depending on the pre-existing milieu. A classic example of a stimulus that can both facilitate and impair neuroplasticity is stress. Indeed, the ability of CNS to respond to acute stress is often dependent upon the prior stress history of the individual. While responses to acute stress are often viewed as adaptive in nature, stress reactivity in subjects with prior chronic stress experiences are often linked to neuropsychiatric disorders, including major depressive disorder, post-traumatic stress disorder (PTSD) and anxiety. In rodent studies, chronic stress exposure produces structural and functional alterations in the hippocampus and medial prefrontal cortex that are consistent across different types of stress paradigms. Conversely, the amygdala appears to exhibit differential structural and functional responses to stress that are dependent on a variety of factors, including the type of stressor performed and the duration of the stress paradigm. This is most evident in output measures including morphological analysis of amygdala neurons, measurement of glutamatergic tone in amygdalar subdivisions and the analysis of amygdala-centric behaviors. Accordingly, this review will provide an overview of the effects of stress on the structural and functional plasticity of the rodent amygdala, especially in relation to the differential effects of repeated or chronic stress paradigms on dendritic architecture, neurochemistry of the glutamatergic system and behavior. PMID:26844236

Financial stress response profiles and psychosocial functioning in low-income parents.

PubMed

Perzow, Sarah E D; Bray, Bethany C; Wadsworth, Martha E

2018-06-01

Parenting in the context of poverty is accompanied by heightened stress and heightened stakes. How parents respond to poverty-related stress has important implications for family functioning, but research investigating individual differences in low-income mothers' and fathers' responses to financial stress and their associations with parents' concurrent psychosocial adaptation is lacking. A better understanding of differences in stress responses among low-income parents is required to develop and tailor prevention programs that meet these families' needs. This study applies latent profile analysis (LPA) to identify and describe profiles of financial stress responses (problem solving, emotion regulation, emotion expression, cognitive restructuring, positive thinking, acceptance, distraction, denial, avoidance, wishful thinking, rumination, intrusive thoughts, emotional arousal, physiologic arousal, impulsive action, emotional numbing, cognitive interference, escape, and inaction) and examines associations between profile membership and psychosocial functioning in low-income parents. Five profiles were identified that were distinguished by self-reported voluntary and involuntary financial stress responses: active (32% of sample), low (11%), high (11%), negative cognitive (NC; 17%), and average (29%) responders. Notable differences emerged on measures of life stress, economic hardship, psychopathology, and social support, with individuals in the NC responders profile reporting the most difficulty and members of the active responders profile reporting the greatest adaptation. These findings offer a more nuanced understanding of how mothers and fathers respond to chronic poverty-related stress and have valuable implications for intervention efforts to promote adaptive stress responses and psychosocial functioning in low-income families. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Saccharomyces cerevisiae Hsp30 is necessary for homeostasis of a set of thermal stress response functions.

PubMed

Thakur, Suresh; Chakrabarti, Amitabha

2010-02-01

Saccharomyces cerevisiae Hsp30 is a plasma membrane heat shock protein which is induced by various environmental stress conditions. However functional role of Hsp30 during diverse environmental stressors is not presently known. To gain insight into its function during thermal stress, we have constructed and characterized a hsp30 strain during heat stress. BY4741Deltahsp30 cells were found to be more sensitive compared to BY4741 cells when exposed to a lethal heat stress at 50 degrees Celsius. When budding yeast is exposed to either heat shock or weak organic acid, it inhibits Pma1p activity. In this study we measured the levels of Pma1p in mutant and Wt cells both during optimal temperature and heat shock temperature. We observed that BY4741Deltahsp30 cells showed constitutive reduction of Pma1p. To gain further insights into the role of Hsp30 during heat stress, we compared total protein profile by 2D gel electrophoresis followed by identification of differentially expressed spots by LC-MS. We observed that contrary to that expected from thermal stress induced changes in gene expression, the Deltahsp30mutant maintained elevated levels of Pdc1p, Trx1p and Nbp35p and reduced levels of Atp2p and Sod1p during heat shock. In conclusion, Hsp30 is necessary during lethal heat stress, for the maintenance of Pma1p and a set of thermal stress response functions.

Sex differences in brain activation during stress imagery in abstinent cocaine users: a functional magnetic resonance imaging study.

PubMed

Li, Chiang-Shan Ray; Kosten, Thomas R; Sinha, Rajita

2005-03-01

Because stress mediates drug seeking and relapse, and sex differences have been observed in stress and in the development of cocaine addiction, in this study we used functional neuroimaging to examine the effect of sex on stress responses in abstinent cocaine users. In a functional magnetic resonance imaging session, 17 male and 10 female cocaine-dependent subjects participated in script-guided imagery of neutral or stress situations. Subjects rated imagery vividness, anxiety, and cocaine craving for each trial. Brain activation during the stress and neutral imagery periods relative to their own baseline was examined in individual subjects. Sex contrast was obtained in second-level group analysis. Female subjects demonstrated more activation, compared with male subjects, in left middle frontal, anterior cingulate, and inferior frontal cortices and insula, and right cingulate cortex during stress imagery. Region of interest analysis showed that the change of activity in left anterior cingulate and right posterior cingulate cortices both correlated inversely with the change of craving rating during stress imagery. The greater left frontolimbic activity in women suggests that women might use more verbal coping strategies than do men while experiencing stress. The results also suggest a distinct role of the cingulate cortices in modulating stress-induced cocaine craving.

Parenting stress and child behaviour problems among parents with intellectual disabilities: the buffering role of resources.

PubMed

Meppelder, M; Hodes, M; Kef, S; Schuengel, C

2015-07-01

Parents with intellectual disabilities (ID) are at risk for high levels of parenting stress. The present study evaluated resources, including parental adaptive functioning, financial resources and access to a support network, as moderators of the association between child behaviour problems and parenting stress. A total of 134 parents with ID and their children (ages 1-7 years) were recruited from 10 Dutch care organisations. Questionnaires were administered to the parents to obtain information on parenting stress in the parent and child domain, financial resources and their support network. Teachers and care workers reported on child behaviour problems and parental adaptive functioning, respectively. Parents experienced more stress with regard to their children than towards their own functioning and situation. Parenting stress was less in parents who were not experiencing financial hardship. Child behaviour problems were associated with high child-related parenting stress, not parent-related parenting stress. Large support networks decreased the association between child behaviour problems and child-related parenting stress. Financial resources did not significantly moderate the association. Parenting stress among parents with ID is focused on problems with the child, especially when little social support is available. © 2014 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

Exogenous γ-Aminobutyric Acid Improves the Structure and Function of Photosystem II in Muskmelon Seedlings Exposed to Salinity-Alkalinity Stress

PubMed Central

Xu, Weinan; Zhen, Ai; Zhang, Liang; Hu, Xiaohui

2016-01-01

Gamma-aminobutyric acid (GABA) is important in plant responses to environmental stresses. We wished to clarify the role of GABA in maintenance of photosynthesis in muskmelon seedlings (Cucumis melo L., cv. Yipintianxia) during saline-alkaline stress. To this end, we assessed the effect of GABA on the structure and function of the photosynthetic apparatus in muskmelon seedlings grown under saline-alkaline stress. These stresses in combination reduced net photosynthetic rate, gas-exchange, and inhibited photosystem II (PSII) electron transport as measured by the JIP-test. They also reduced the activity of chloroplast ATPases and disrupted the internal lamellar system of the thylakoids. Exogenous GABA alleviated the stress-induced reduction of net photosynthesis, the activity of chloroplast ATPases, and overcame some of the damaging effects of stress on the chloroplast structure. Based on interpretation of the JIP-test, we conclude that exogenous GABA alleviated stress-related damage on the acceptor side of PSII. It also restored energy distribution, the reaction center status, and enhanced the ability of PSII to repair reaction centers in stressed seedlings. GABA may play a crucial role in protecting the chloroplast structure and function of PSII against the deleterious effects of salinity-alkalinity stress. PMID:27764179

Protective effect of exercise and sildenafil on acute stress and cognitive function.

PubMed

Ozbeyli, Dilek; Gokalp, Ayse Gizem; Koral, Tolga; Ocal, Onur Yuksel; Dogan, Berkay; Akakin, Dilek; Yuksel, Meral; Kasimay, Ozgur

2015-11-01

There are contradictory results about the effects of exercise and sildenafil on cognitive functions. To investigate the effects of sildenafil pretreatment and chronic exercise on anxiety and cognitive functions. Wistar rats (n=42) were divided as sedentary and exercise groups. A moderate-intensity swimming exercise was performed for 6 weeks, 5 days/week, 1h/day. Some of the rats were administered orogastrically with sildenafil (25mg/kg/day) either acutely or chronically. Exposure to cat odor was used for induction of stress. The level of anxiety was evaluated by elevated plus maze test, while object recognition test was used to determine cognitive functions. Brain tissues were removed for the measurement of myeloperoxidase (MPO), malondialdehyde (MDA), nitric oxide levels, lucigenin-enhanced chemiluminescence, and for histological analysis. Increased MPO and MDA levels in sedentary-stressed rats were decreased with sildenafil applications. Chronic exercise inhibited the increase in MPO levels. Increased nitric oxide and lucigenin chemiluminescence levels in sedentary-stressed rats, were diminished with chronic sildenafil pretreatment. The time spent in the open arms of the plus maze was declined in sedentary-stressed rats, while chronic sildenafil pretreatment increased the time back to that in non-stressed rats. Acute sildenafil application to exercised rats prolonged the time spent in open arms as compared to non-treated exercise group. The time spent with the novel object, which was decreased in sedentary-stressed rats, was increased with sildenafil pretreatment. Our results suggest that sildenafil pretreatment or exercise exerts a protective effect against acute stress and improves cognitive functions by decreasing oxidative damage. Copyright © 2015 Elsevier Inc. All rights reserved.

Aroma Effects on Physiologic and Cognitive Function Following Acute Stress: A Mechanism Investigation

PubMed Central

Oken, Barry S.

2016-01-01

Abstract Objective: Aromas may improve physiologic and cognitive function after stress, but associated mechanisms remain unknown. This study evaluated the effects of lavender aroma, which is commonly used for stress reduction, on physiologic and cognitive functions. The contribution of pharmacologic, hedonic, and expectancy-related mechanisms of the aromatherapy effects was evaluated. Methods: Ninety-two healthy adults (mean age, 58.0 years; 79.3% women) were randomly assigned to three aroma groups (lavender, perceptible placebo [coconut], and nonperceptible placebo [water] and to two prime subgroups (primed, with a suggestion of inhaling a powerful stress-reducing aroma, or no prime). Participants' performance on a battery of cognitive tests, physiologic responses, and subjective stress were evaluated at baseline and after exposure to a stress battery during which aromatherapy was present. Participants also rated the intensity and pleasantness of their assigned aroma. Results: Pharmacologic effects of lavender but not placebo aromas significantly benefited post-stress performance on the working memory task (F(2, 86) = 5.41; p = 0.006). Increased expectancy due to positive prime, regardless of aroma type, facilitated post-stress performance on the processing speed task (F(1, 87) = 8.31; p = 0.005). Aroma hedonics (pleasantness and intensity) played a role in the beneficial lavender effect on working memory and physiologic function. Conclusions: The observable aroma effects were produced by a combination of mechanisms involving aroma-specific pharmacologic properties, aroma hedonic properties, and participant expectations. In the future, each of these mechanisms could be manipulated to produce optimal functioning. PMID:27355279

Emerging trends in the functional genomics of the abiotic stress response in crop plants.

PubMed

Vij, Shubha; Tyagi, Akhilesh K

2007-05-01

Plants are exposed to different abiotic stresses, such as water deficit, high temperature, salinity, cold, heavy metals and mechanical wounding, under field conditions. It is estimated that such stress conditions can potentially reduce the yield of crop plants by more than 50%. Investigations of the physiological, biochemical and molecular aspects of stress tolerance have been conducted to unravel the intrinsic mechanisms developed during evolution to mitigate against stress by plants. Before the advent of the genomics era, researchers primarily used a gene-by-gene approach to decipher the function of the genes involved in the abiotic stress response. However, abiotic stress tolerance is a complex trait and, although large numbers of genes have been identified to be involved in the abiotic stress response, there remain large gaps in our understanding of the trait. The availability of the genome sequences of certain important plant species has enabled the use of strategies, such as genome-wide expression profiling, to identify the genes associated with the stress response, followed by the verification of gene function by the analysis of mutants and transgenics. Certain components of both abscisic acid-dependent and -independent cascades involved in the stress response have already been identified. Information originating from the genome-wide analysis of abiotic stress tolerance will help to provide an insight into the stress-responsive network(s), and may allow the modification of this network to reduce the loss caused by stress and to increase agricultural productivity.

Rheological approaches of arteries.

PubMed

Bauer, R D

1984-01-01

A fundamental problem of haemodynamics lies in the description of the rheological properties of arteries. The time and history dependency of stress and strain, the nonlinearity of the stress-radius relationship, and the activity of vascular smooth muscle complicate or even prevent a complete mathematical characterization of the arterial wall mechanics. Due to this nonlinearity, dynamic investigations were hitherto performed in excised arteries in vitro by means of small sinusoidal changes of stress and radius at different stress levels in a wide frequency range. To allow an analysis of the dynamic rheological properties of arteries in vivo, we have developed a procedure which permits the separate determination of the elastic, the viscous, and the inertial forces acting on the arterial wall. The stress can be subdivided into an elastic stress which is a function of radius (r), a viscous stress which is a function of dr/dt, and an inertial stress which is a function of d2r/dt2. These stresses are formulated as polynomials. Under cyclic loading and unloading, hysteresis loops appear in the stress-radius diagrams of arteries. Since the elastic stress-radius diagram must be free from any loop, the coefficients of the viscous and the inertial stress can be found by a fitting procedure, using the criterion of loop elimination. Investigations were performed on exposed canine arteries in vivo. The main result was that the elastic stress-radius curve was markedly nonlinear at greater pulse pressures. The viscous wall behaviour, too, was nonlinear and depended mainly on the square of the vessel radius.

Genome-wide analysis of Glycine soja ubiquitin (UBQ) genes and functional analysis of GsUBQ10 in response to alkaline stress.

PubMed

Chen, Chao; Chen, Ranran; Wu, Shengyang; Zhu, Dan; Sun, Xiaoli; Liu, Beidong; Li, Qiang; Zhu, Yanming

2018-03-26

Ubiquitin is a highly conserved protein with multiple essential regulation functions through the ubiquitin-proteasome system. Even though its functions in the ubiquitin-mediated protein degradation pathway were very well characterized. The functions of ubiquitin genes in regulating alkaline stress response are not fully established. In this study, we identified 12 potential UBQ genes in Glycine soja genome, and analyzed their evolutionary relationship, conserved domains and promoter cis-elements. We also explored the expression profiles of G. soja UBQ genes under alkaline stress, based on the transcriptome sequencing. We found that the expression of GsUBQ10 was significantly induced by alkaline stress, and function of GsUBQ10 was characterized using overexpression transgenic alfalfa (Medicago sativa). Our results suggested that GsUBQ10 transgenic lines significantly improved the alkaline tolerance in alfalfa. The GsUBQ10 transgenic lines showed lower relative membrane permeability, lower malon dialdehyde content and higher catalase activity than in the wild-type plants. This indicates that GsUBQ10 is involved in regulating the reactive oxygen species accumulation under alkaline stress. Taken together, we identified an ubiquitin gene GsUBQ10 from G. soja, which plays a positive role in responses to alkaline stress in alfalfa. This article is protected by copyright. All rights reserved.

Lateralized kappa opioid receptor signaling from the amygdala central nucleus promotes stress-induced functional pain.

PubMed

Nation, Kelsey M; De Felice, Milena; Hernandez, Pablo I; Dodick, David W; Neugebauer, Volker; Navratilova, Edita; Porreca, Frank

2018-05-01

The response of diffuse noxious inhibitory controls (DNIC) is often decreased, or lost, in stress-related functional pain syndromes. Because the dynorphin/kappa opioid receptor (KOR) pathway is activated by stress, we determined its role in DNIC using a model of stress-induced functional pain. Male, Sprague-Dawley rats were primed for 7 days with systemic morphine resulting in opioid-induced hyperalgesia. Fourteen days after priming, when hyperalgesia was resolved, rats were exposed to environmental stress and DNIC was evaluated by measuring hind paw response threshold to noxious pressure (test stimulus) after capsaicin injection in the forepaw (conditioning stimulus). Morphine priming without stress did not alter DNIC. However, stress produced a loss of DNIC in morphine-primed rats in both hind paws that was abolished by systemic administration of the KOR antagonist, nor-binaltorphimine (nor-BNI). Microinjection of nor-BNI into the right, but not left, central nucleus of the amygdala (CeA) prevented the loss of DNIC in morphine-primed rats. Diffuse noxious inhibitory controls were not modulated by bilateral nor-BNI in the rostral ventromedial medulla. Stress increased dynorphin content in both the left and right CeA of primed rats, reaching significance only in the right CeA; no change was observed in the rostral ventromedial medulla or hypothalamus. Although morphine priming alone is not sufficient to influence DNIC, it establishes a state of latent sensitization that amplifies the consequences of stress. After priming, stress-induced dynorphin/KOR signaling from the right CeA inhibits DNIC in both hind paws, likely reflecting enhanced descending facilitation that masks descending inhibition. Kappa opioid receptor antagonists may provide a new therapeutic strategy for stress-related functional pain disorders.

The dependence of permeability on effective stress from flow tests at hot dry rock reservoirs at Rosemanowes (Cornwall) and Fenton Hill (New Mexico)

USGS Publications Warehouse

Nathenson, M.

1999-01-01

Effective stress is the primary control on permeability and thus on flow and water loss for two-well hot dry rock systems involving injection and production that have been tested to date. Theoretical relations are derived for the flow between an injector and producer, including the dependence of permeability on effective stress. Four relations for permeability as a function of effective stress are used to match field data for the hot dry rock systems at Rosemanowes, Cornwall, and Fenton Hill, New Mexico. The flow and water loss behavior of these systems are well explained by the influence of effective stress on permeability. All four relations for permeability as a function of effective stress are successful in matching the field data, but some have difficulty in determining unique values for elastic and hydrologic parameters.Effective stress is the primary control on permeability and thus on flow and water loss for two-well hot dry rock systems involving injection and production that have been tested to date. Theoretical relations are derived for the flow between an injector and producer, including the dependence of permeability on effective stress. Four relations for permeability as a function of effective stress are used to match field data for the hot dry rock systems at Rosemanowes, Cornwall, and Fenton Hill, New Mexico. The flow and water loss behavior of these systems are well explained by the influence of effective stress on permeability. All four relations for permeability as a function of effective stress are successful in matching the field data, but some have difficulty in determining unique values for elastic and hydrologic parameters.

Modeling the Collisional-Plastic Stress Transition for Bin Discharge of Granular Material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pannala, Sreekanth; Daw, C Stuart; FINNEY, Charles E A

2009-01-01

We propose a heuristic model for the transition between collisional and frictional/plastic stresses in the flow of granular material. Our approach is based on a physically motivated, nonlinear blending function that produces a weighted average of the limiting stresses, depending on the local void fraction in the flow field. Previously published stress models are utilized to describe the behavior in the collisional (Lun et al., 1984) and quasi-static limits (Schaeffer, 1987 and Syamlal et al., 1993). Sigmoidal and hyperbolic tangent functions are used to mimic the observed smooth yet rapid transition between the collisional and plastic stress zones. We implementmore » our stress transition model in an opensource multiphase flow solver, MFIX (Multiphase Flow with Interphase eXchanges, www.mfix.org) and demonstrate its application to a standard bin discharge problem. The model s effectiveness is illustrated by comparing computational predictions to the experimentally derived Beverloo correlation. With the correct choice of function parameters, the model predicts bin discharge rates within the error margins of the Beverloo correlation and is more accurate than one of the alternative granular stress models proposed in the literature. Although a second granular stress model in the literature is also reasonably consistent with the Beverloo correlation, we propose that our alternative blending function is likely to be more adaptable to situations with more complex solids properties (e.g., sticky solids).« less

On the influence of dynamic stress variations on strain accumulation in fault zones

NASA Astrophysics Data System (ADS)

Grigoriev, A. S.; Shilko, E. V.; Astafurov, S. V.; Dimaki, A. V.; Vysotsky, E. M.; Psakhie, S. G.

2015-10-01

In this paper, a numerical study of the influence of the stress state of interface of the block medium structural elements on the deformation response of interface to the dynamic impacts. It is shown that the basic characteristics of the stress state determining the deformation response of the interface are the values of shear stress and mean stress. It is found that the dependence of the irreversible displacement at the interface zone initiated by dynamic impact on the reduced shear stress is described by the logistic function. Herewith, the influence of the mean stress and dynamic impact energy on the value of displacement initiated by dynamic impact can be taken into account by dependence of the logistic function numerator on these parameters.

Traumatic stress: effects on the brain

PubMed Central

Bremner, J. Douglas

2006-01-01

Brain areas implicated in the stress response include the amygdala, hippocampus, and prefrontal cortex. Traumatic stress can be associated with lasting changes in these brain areas. Traumatic stress is associated with increased cortisol and norepinephrine responses to subsequent stressors. Antidepressants have effets on the hippocampus that counteract the effects of stress. Findings from animal studies have been extended to patients with post-traumatic stress disorder (PTSD) showing smaller hippocampal and anterior cingulate volumes, increased amygdala function, and decreased medial prefrontal/anterior cingulate function. In addition, patients with PTSD show increased cortisol and norepinephrine responses to stress. Treatments that are efficacious for PTSD show a promotion of neurogenesis in animal studies, as well as promotion of memory and increased hippocampal volume in PTSD. PMID:17290802

The Relationship between Sources and Functions of Social Support and Dimensions of Child- and Parent-Related Stress

ERIC Educational Resources Information Center

Guralnick, M. J.; Hammond, M. A.; Neville, B.; Connor, R. T.

2008-01-01

Background: In this longitudinal study, we examined the relationship between the sources and functions of social support and dimensions of child- and parent-related stress for mothers of young children with mild developmental delays. Methods: Sixty-three mothers completed assessments of stress and support at two time points. Results: Multiple…

Parental Family Stress during Pregnancy and Cognitive Functioning in Early Childhood: The Generation R Study

ERIC Educational Resources Information Center

Henrichs, Jens; Schenk, Jacqueline J.; Kok, Rianne; Ftitache, Bouchra; Schmidt, Henk G.; Hofman, Albert; Jaddoe, Vincent W. V.; Verhulst, Frank C.; Tiemeier, Henning

2011-01-01

We investigated whether parental family stress during pregnancy is associated with cognitive functioning in early childhood in a population-based cohort (n = 3139). Family stress was assessed using the Family Assessment Device at the 20th week of pregnancy and was reported by mothers and fathers. Mothers completed the MacArthur Communicative…

[Use of terahertz electromagnetic radiation at nitric oxide frequencies for the correction of thyroid functional state during stress].

PubMed

Kirichuk, V F; Tsymbal, A A

2010-01-01

The influence of terahertz electromagnetic radiation at nitric oxide frequencies (150.176-150.664 Ghz) on the functional activity of rat thyroid gland subjected to acute immobilization stress has been studied. It is shown that terahertz radiation totally normalizes thyroid activity in stressed animals within 30 min after application.

Endogenously Released Neuropeptide Y Suppresses Hippocampal Short-Term Facilitation and Is Impaired by Stress-Induced Anxiety

PubMed Central

Li, Qin; Bartley, Aundrea F.

2017-01-01

Neuropeptide Y (NPY) has robust anxiolytic properties and is reduced in patients with anxiety disorders. However, the mechanisms by which NPY modulates circuit function to reduce anxiety behavior are not known. Anxiolytic effects of NPY are mediated in the CA1 region of hippocampus, and NPY injection into hippocampus alleviates anxiety symptoms in the predator scent stress model of stress-induced anxiety. The mechanisms that regulate NPY release, and its effects on CA1 synaptic function, are not fully understood. Here we show in acute hippocampal slices from mice that endogenous NPY, released in response to optogenetic stimulation or synaptically evoked spiking of NPY+ cells, suppresses both of the feedforward pathways to CA1. Stimulation of temporoammonic synapses with a physiologically derived spike train causes NPY release that reduces short-term facilitation, whereas the release of NPY that modulates Schaffer collateral synapses requires integration of both the Schaffer collateral and temporoammonic pathways. Pathway specificity of NPY release is conferred by three functionally distinct NPY+ cell types, with differences in intrinsic excitability and short-term plasticity of their inputs. Predator scent stress abolishes the release of endogenous NPY onto temporoammonic synapses, a stress-sensitive pathway, thereby causing enhanced short-term facilitation. Our results demonstrate how stress alters CA1 circuit function through the impairment of endogenous NPY release, potentially contributing to heightened anxiety. SIGNIFICANCE STATEMENT Neuropeptide Y (NPY) has robust anxiolytic properties, and its levels are reduced in patients with post-traumatic stress disorder. The effects of endogenously released NPY during physiologically relevant stimulation, and the impact of stress-induced reductions in NPY on circuit function, are unknown. By demonstrating that NPY release modulates hippocampal synaptic plasticity and is impaired by predator scent stress, our results provide a novel mechanism by which stress-induced anxiety alters circuit function. These studies fill an important gap in knowledge between the molecular and behavioral effects of NPY. This article also advances the understanding of NPY+ cells and the factors that regulate their spiking, which could pave the way for new therapeutic targets to increase endogenous NPY release in patients in a spatially and temporally appropriate manner. PMID:28053027