Advanced MOKE magnetometry in wide-field Kerr-microscopy

NASA Astrophysics Data System (ADS)

Soldatov, I. V.; Schäfer, R.

2017-10-01

The measurement of MOKE (Magneto-Optical Kerr Effect) magnetization loops in a wide-field Kerr microscope offers the advantage that the relevant domain images along the loop can be readily recorded. As the microscope's objective lens is exposed to the magnetic field, the loops are usually strongly distorted by non-linear Faraday rotations of the polarized light that occur in the objective lens and that are superimposed to the MOKE signal. In this paper, an experimental method, based on a motorized analyzer, is introduced which allows to compensate the Faraday contributions, thus leading to pure MOKE loops. A wide field Kerr microscope, equipped with this technology, works well as a laser-based MOKE magnetometer, additionally offering domain images and thus providing the basis for loop interpretation.

Metric of two balancing Kerr particles in physical parametrization

NASA Astrophysics Data System (ADS)

Manko, V. S.; Ruiz, E.

2015-11-01

The present paper aims at elaborating a completely physical representation for the general 4-parameter family of the extended double-Kerr spacetimes describing two spinning sources in gravitational equilibrium. This involved problem is solved in a concise analytical form by using the individual Komar masses and angular momenta as arbitrary parameters, and the simplest equatorially symmetric specialization of the general expressions obtained by us yields the physical representation for the well-known Dietz-Hoenselaers superextreme case of two balancing identical Kerr constituents. The existence of the physically meaningful "black-hole-superextreme-object" equilibrium configurations permitted by the general solution may be considered as a clear indication that the spin-spin repulsion force might actually be by far stronger than expected earlier, when only the balance between two superextreme Kerr sources was thought possible. We also present the explicit analytical formulas relating the equilibrium states in the double-Kerr and double-Reissner-Nordström configurations.

Mechanical Kerr nonlinearities due to bipolar optical forces between deformable silicon waveguides.

PubMed

Ma, Jing; Povinelli, Michelle L

2011-05-23

We use an analytical method based on the perturbation of effective index at fixed frequency to calculate optical forces between silicon waveguides. We use the method to investigate the mechanical Kerr effect in a coupled-waveguide system with bipolar forces. We find that a positive mechanical Kerr coefficient results from either an attractive or repulsive force. An enhanced mechanical Kerr coefficient several orders of magnitude larger than the intrinsic Kerr coefficient is obtained in waveguides for which the optical mode approaches the air light line, given appropriate design of the waveguide dimensions.

Kerr optical frequency combs: theory, applications and perspectives

NASA Astrophysics Data System (ADS)

Chembo, Yanne K.

2016-06-01

The optical frequency comb technology is one of the most important breakthrough in photonics in recent years. This concept has revolutionized the science of ultra-stable lightwave and microwave signal generation. These combs were originally generated using ultrafast mode-locked lasers, but in the past decade, a simple and elegant alternativewas proposed,which consisted in pumping an ultra-high-Q optical resonator with Kerr nonlinearity using a continuous-wave laser. When optimal conditions are met, the intracavity pump photons are redistributed via four-wave mixing to the neighboring cavity modes, thereby creating the so-called Kerr optical frequency comb. Beyond being energy-efficient, conceptually simple, and structurally robust, Kerr comb generators are very compact devices (millimetric down to micrometric size) which can be integrated on a chip. They are, therefore, considered as very promising candidates to replace femtosecond mode-locked lasers for the generation of broadband and coherent optical frequency combs in the spectral domain, or equivalently, narrow optical pulses in the temporal domain. These combs are, moreover, expected to provide breakthroughs in many technological areas, such as integrated photonics, metrology, optical telecommunications, and aerospace engineering. The purpose of this review article is to present a comprehensive survey of the topic of Kerr optical frequency combs.We provide an overview of the main theoretical and experimental results that have been obtained so far. We also highlight the potential of Kerr combs for current or prospective applications, and discuss as well some of the open challenges that are to be met at the fundamental and applied level.

Nanoscale Kerr Nonlinearity Enhancement Using Spontaneously Generated Coherence in Plasmonic Nanocavity

PubMed Central

Chen, Hongyi; Ren, Juanjuan; Gu, Ying; Zhao, Dongxing; Zhang, Junxiang; Gong, Qihuang

2015-01-01

The enhancement of the optical nonlinear effects at nanoscale is important in the on-chip optical information processing. We theoretically propose the mechanism of the great Kerr nonlinearity enhancement by using anisotropic Purcell factors in a double-Λ type four-level system, i.e., if the bisector of the two vertical dipole moments lies in the small/large Purcell factor axis in the space, the Kerr nonlinearity will be enhanced/decreased due to the spontaneously generated coherence accordingly. Besides, when the two dipole moments are parallel, the extremely large Kerr nonlinearity increase appears, which comes from the double population trapping. Using the custom-designed resonant plasmonic nanostructure which gives an anisotropic Purcell factor environment, we demonstrate the effective nanoscale control of the Kerr nonlinearity. Such controllable Kerr nonlinearity may be realized by the state-of-the-art nanotechnics and it may have potential applications in on-chip photonic nonlinear devices. PMID:26670939

Kerr effect from diffractive skew scattering in chiral px +/- ipy superconductors

NASA Astrophysics Data System (ADS)

König, Elio; Levchenko, Alex

We calculate the temperature dependent anomalous ac Hall conductance σH (Ω , T) for a two-dimensional chiral p-wave superconductor. This quantity determines the polar Kerr effect, as it was observed in Sr2RuO4. We concentrate on a single band model with arbitrary isotropic dispersion relation subjected to rare, weak impurities treated in the Born approximation. As we explicitly show by detailed computation, previously omitted contributions to extrinsic part of an anomalous Hall response, physically originating from diffractive skew scattering on quantum impurity complexes, appear to the leading order in impurity concentration. By direct comparison with published results from the literature we demonstrate the relevance of our findings for the interpretation of the Kerr effect measurements in superconductors. This work was financially supported in part by NSF Grants No. DMR-1606517 and ECCS-1560732 and at U of Wisconsin by the Office of the Vice Chancellor for Research and Graduate Education with funding from the Wisconsin Alumni Research Foundation.

Perturbations of the Kerr spacetime in horizon-penetrating coordinates

NASA Astrophysics Data System (ADS)

Campanelli, Manuela; Khanna, Gaurav; Laguna, Pablo; Pullin, Jorge; Ryan, Michael P.

2001-04-01

We derive the Teukolsky equation for perturbations of a Kerr spacetime when the spacetime metric is written in either ingoing or outgoing Kerr-Schild form. We also write explicit formulae for setting up the initial data for the Teukolsky equation in the time domain in terms of a 3-metric and an extrinsic curvature. The motivation of this work is to have in place a formalism to study the evolution in the `close limit' of two recently proposed solutions to the initial-value problem in general relativity that are based on Kerr-Schild slicings. A perturbative formalism in horizon-penetrating coordinates is also very desirable in connection with numerical relativity simulations using black hole `excision'.

Greybody factors and charges in Kerr/CFT

DOE PAGES

Cvetič, Mirjam; Larsen, Finn

2009-09-01

We compute greybody factors for near extreme Kerr black holes in D = 4 and D = 5. In D = 4 we include four charges so that our solutions can be continuously deformed to the BPS limit. In D = 5 we include two independent angular momenta so Left-Right symmetry is incorporated. We discuss the CFT interpretation of our emission amplitudes, including the overall frequency dependence and the dependence on all black hole parameters. We find that all additional parameters can be incorporated Kerr/CFT, with central charge independent of U(1) charges.

Diode-pumped Kerr-lens mode-locked femtosecond Yb:YAG ceramic laser

NASA Astrophysics Data System (ADS)

Zi-Ye, Gao; Jiang-Feng, Zhu; Ke, Wang; Jun-Li, Wang; Zhao-Hua, Wang; Zhi-Yi, Wei

2016-02-01

We experimentally demonstrated a diode-pumped Kerr-lens mode-locked femtosecond laser based on an Yb:YAG ceramic. Stable laser pulses with 97-fs duration, 2.8-nJ pulse energy, and 320-mW average power were obtained. The femtosecond oscillator operated at a central wavelength of 1049 nm and a repetition rate of 115 MHz. To the best of our knowledge, this is the first demonstration of a Kerr-lens mode-locked operation in a diode-pumped Yb:YAG ceramic laser with sub-100 fs pulse duration. Project supported by the National Major Scientific Instrument Development Project of China (Grant No. 2012YQ120047), the National Natural Science Foundation of China (Grant No. 61205130), and the Fundamental Research Funds for the Central Universities, China (Grant No. JB140502).

Iron K α line of Kerr black holes with Proca hair

NASA Astrophysics Data System (ADS)

Zhou, Menglei; Bambi, Cosimo; Herdeiro, Carlos A. R.; Radu, Eugen

2017-05-01

We continue our study on the capabilities of present and future x-ray missions to test the nature of astrophysical black hole candidates via x-ray reflection spectroscopy and distinguish Kerr black holes from other solutions of 4-dimensional Einstein's gravity in the presence of a matter field. Here we investigate the case of Kerr black holes with Proca hair [1]. The analysis of a sample of these configurations suggests that even extremely hairy black holes can mimic the iron line profile of the standard Kerr black holes, and, at least for the configurations of our study, we find that current x-ray missions cannot distinguish these objects from Kerr black holes. This contrasts with our previous findings for the case of Kerr black holes with scalar (rather than Proca) hair [2], even though such comparison may be biased by the limited sample. Future x-ray missions can detect the presence of Proca hair, but a theoretical knowledge of the expected intensity profile (currently missing) can be crucial to obtain strong constraints.

Large Electro-Optic Kerr Effect in Ionic Liquid Crystals: Connecting Features of Liquid Crystals and Polyelectrolytes.

PubMed

Schlick, M Christian; Kapernaum, Nadia; Neidhardt, Manuel M; Wöhrle, Tobias; Stöckl, Yannick; Laschat, Sabine; Giesselmann, Frank

2018-06-06

The electro-optic Kerr effect in simple dipolar fluids such as nitrobenzene has been widely applied in electro-optical phase modulators and light shutters. In 2005, the discovery of the large Kerr effect in liquid-crystalline blue phases (Y. Hisakado et al., Adv. Mater. 2005, 17, 96-98.) gave new directions to the search for advanced Kerr effect materials. Even though the Kerr effect is present in all transparent and optically isotropic media, it is well known that the effect can be anomalously large in complex fluids, namely in the isotropic phase of liquid crystals or in polyelectrolyte solutions. Herein, it is shown that the Kerr effect in the isotropic phase of ionic liquid crystals combines the effective counterion polarization mechanism found in polyelectrolytes and the unique pretransitional growth of the Kerr constant found in the isotropic phase of nematic liquid crystals. Maximum Kerr constants in the order of several 10 -11  m V -2 (ten times higher than the Kerr constant of the toxic nitrobenzene and less temperature sensitive than Kerr constants of nematic liquid crystals) make ionic liquid crystals attractive as new class of functional materials in low-speed Kerr effect applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comprehensive analysis of the optical Kerr coefficient of graphene

DOE PAGES

Soh, Daniel B. S.; Hamerly, Ryan; Mabuchi, Hideo

2016-08-25

We present a comprehensive analysis of the nonlinear optical Kerr effect in graphene. We directly solve the S-matrix element to calculate the absorption rate, utilizing the Volkov-Keldysh-type crystal wave functions. We then convert to the nonlinear refractive index coefficients through the Kramers-Kronig relation. In this formalism, the source of Kerr nonlinearity is the interplay of optical fields that cooperatively drive the transition from valence to conduction band. This formalism makes it possible to identify and compute the rates of distinct nonlinear processes that contribute to the Kerr nonlinear refractive index coefficient. The four identified mechanisms are two-photon absorption, Raman transition,more » self-coupling, and quadratic ac Stark effect. As a result, we present a comparison of our theory with recent experimental and theoretical results.« less

Gravitational collapse to a Kerr-Newman black hole

NASA Astrophysics Data System (ADS)

Nathanail, Antonios; Most, Elias R.; Rezzolla, Luciano

2017-07-01

We present the first systematic study of the gravitational collapse of rotating and magnetized neutron stars to charged and rotating (Kerr-Newman) black holes. In particular, we consider the collapse of magnetized and rotating neutron stars assuming that no pair-creation takes place and that the charge density in the magnetosphere is so low that the stellar exterior can be described as an electrovacuum. Under these assumptions, which are rather reasonable for a pulsar that has crossed the 'death line', we show that when the star is rotating, it acquires a net initial electrical charge, which is then trapped inside the apparent horizon of the newly formed back hole. We analyse a number of different quantities to validate that the black hole produced is indeed a Kerr-Newman one and show that, in the absence of rotation or magnetic field, the end result of the collapse is a Schwarzschild or Kerr black hole, respectively.

Optical coatings for improved contrast in longitudinal magneto-optic Kerr effect measurements

NASA Astrophysics Data System (ADS)

Cantwell, P. R.; Gibson, U. J.; Allwood, D. A.; Macleod, H. A. M.

2006-11-01

We have studied the increases in the longitudinal magneto-optic Kerr effect signal contrast that can be achieved by the application of optical overlayers on magnetic films. For simple coatings, a factor of ˜3 improvement in signal contrast is possible. Matching the optical impedance of the magnetic material improves the raw Kerr signal and also reduces the sample reflectivity, yielding a large Kerr angle. The contrast can be optimized by increasing the rotated Kerr reflectivity component while maintaining enough of the base reflectivity Fresnel component to produce a strong signal. Calculations and experimental results are presented for single layer ZrO2 dielectric coatings on Ni along with calculations for a three-layer Au -ZrO2-Ni structure. Incidence angle effects are also presented.

A geometric description of Maxwell field in a Kerr spacetime

NASA Astrophysics Data System (ADS)

Jezierski, Jacek; Smołka, Tomasz

2016-06-01

We consider the Maxwell field in the exterior of a Kerr black hole. For this system, we propose a geometric construction of generalized Klein-Gordon equation called Fackerell-Ipser equation. Our model is based on conformal Yano-Killing tensor (CYK tensor). We present non-standard properties of CYK tensors in the Kerr spacetime which are useful in electrodynamics.

Horizon geometry for Kerr black holes with synchronized hair

NASA Astrophysics Data System (ADS)

Delgado, Jorge F. M.; Herdeiro, Carlos A. R.; Radu, Eugen

2018-06-01

We study the horizon geometry of Kerr black holes (BHs) with scalar synchronized hair [1], a family of solutions of the Einstein-Klein-Gordon system that continuously connects to vacuum Kerr BHs. We identify the region in parameter space wherein a global isometric embedding in Euclidean 3-space, E3, is possible for the horizon geometry of the hairy BHs. For the Kerr case, such embedding is possible iff the horizon dimensionless spin jH (which equals the total dimensionless spin, j ), the sphericity s and the horizon linear velocity vH are smaller than critical values, j(S ),s(S ),vH(S ), respectively. For the hairy BHs, we find that jHKerr BHs) differs from jH—is larger than unity.

Effective stability against superradiance of Kerr black holes with synchronised hair

NASA Astrophysics Data System (ADS)

Degollado, Juan Carlos; Herdeiro, Carlos A. R.; Radu, Eugen

2018-06-01

Kerr black holes with synchronised hair [1,2] are a counter example to the no hair conjecture, in General Relativity minimally coupled to simple matter fields (with mass μ) obeying all energy conditions. Since these solutions have, like Kerr, an ergoregion it has been a lingering possibility that they are afflicted by the superradiant instability, the same process that leads to their dynamical formation from Kerr. A recent breakthrough [3] confirmed this instability and computed the corresponding timescales for a sample of solutions. We discuss how these results and other observations support two conclusions: 1) starting from the Kerr limit, the increase of hair for fixed coupling μM (where M is the BH mass) increases the timescale of the instability; 2) there are hairy solutions for which this timescale, for astrophysical black hole masses, is larger than the age of the Universe. The latter conclusion introduces the limited, but physically relevant concept of effective stability. The former conclusion, allows us to identify an astrophysically viable domain of such effectively stable hairy black holes, occurring, conservatively, for Mμ ≲ 0.25. These are hairy BHs that form dynamically, from the superradiant instability of Kerr, within an astrophysical timescale, but whose own superradiant instability occurs only in a cosmological timescale.

Scattering of Dirac waves off Kerr black holes

NASA Astrophysics Data System (ADS)

Chakrabarti, Sandip K.; Mukhopadhyay, Banibrata

2000-10-01

Chandrasekhar separated the Dirac equation for spinning and massive particles in Kerr geometry into radial and angular parts. Here we solve the complete wave equation and find out how the Dirac wave scatters off Kerr black holes. The eigenfunctions, eigenvalues and reflection and transmission co-efficients are computed. We compare the solutions with several parameters to show how a spinning black hole recognizes the mass and energy of incoming waves. Very close to the horizon the solutions become independent of the particle parameters, indicating the universality of the behaviour.

Schwarzschild and Kerr solutions of Einstein's field equation: An Introduction

NASA Astrophysics Data System (ADS)

Heinicke, Christian; Hehl, Friedrich W.

2015-12-01

Starting from Newton's gravitational theory, we give a general introduction into the spherically symmetric solution of Einstein's vacuum field equation, the Schwarzschild(-Droste) solution, and into one specific stationary axially symmetric solution, the Kerr solution. The Schwarzschild solution is unique and its metric can be interpreted as the exterior gravitational field of a spherically symmetric mass. The Kerr solution is only unique if the multipole moments of its mass and its angular momentum take on prescribed values. Its metric can be interpreted as the exterior gravitational field of a suitably rotating mass distribution. Both solutions describe objects exhibiting an event horizon, a frontier of no return. The corresponding notion of a black hole is explained to some extent. Eventually, we present some generalizations of the Kerr solution.

Closed-form solutions and scaling laws for Kerr frequency combs

PubMed Central

Renninger, William H.; Rakich, Peter T.

2016-01-01

A single closed-form analytical solution of the driven nonlinear Schrödinger equation is developed, reproducing a large class of the behaviors in Kerr-comb systems, including bright-solitons, dark-solitons, and a large class of periodic wavetrains. From this analytical framework, a Kerr-comb area theorem and a pump-detuning relation are developed, providing new insights into soliton- and wavetrain-based combs along with concrete design guidelines for both. This new area theorem reveals significant deviation from the conventional soliton area theorem, which is crucial to understanding cavity solitons in certain limits. Moreover, these closed-form solutions represent the first step towards an analytical framework for wavetrain formation, and reveal new parameter regimes for enhanced Kerr-comb performance. PMID:27108810

The superradiant instability regime of the spinning Kerr black hole

NASA Astrophysics Data System (ADS)

Hod, Shahar

2016-07-01

Spinning Kerr black holes are known to be superradiantly unstable to massive scalar perturbations. We here prove that the instability regime of the composed Kerr-black-hole-massive-scalar-field system is bounded from above by the dimensionless inequality Mμ < m ṡ√{2(1 + γ) (1 -√ 1 -γ2) / -γ2 4γ2, where { μ , m } are respectively the proper mass and azimuthal harmonic index of the scalar field and γ ≡r- /r+ is the dimensionless ratio between the horizon radii of the black hole. It is further shown that this analytically derived upper bound on the superradiant instability regime of the spinning Kerr black hole agrees with recent numerical computations of the instability resonance spectrum.

Constraints on two accretion disks centered on the equatorial plane of a Kerr SMBH

NASA Astrophysics Data System (ADS)

Pugliese, Daniela; Stuchlík, Zdeněk

2017-12-01

The possibility that two toroidal accretion configurations may be orbiting around a super–massive Kerr black hole has been addressed. Such tori may be formed during different stages of the Kerr attractor accretion history. We consider the relative rotation of the tori and the corotation or counterrotation of a single torus with respect to the Kerr attractor. We give classification of the couples of accreting and non–accreting tori in dependence on the Kerr black hole dimensionless spin. We demonstrate that only in few cases a double accretion tori system may be formed under specific conditions.

Strong gravitational lensing by a Konoplya-Zhidenko rotating non-Kerr compact object

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

Wang, Shangyun; Chen, Songbai; Jing, Jiliang, E-mail: shangyun_wang@163.com, E-mail: csb3752@hunnu.edu.cn, E-mail: jljing@hunnu.edu.cn

Konoplya and Zhidenko have proposed recently a rotating non-Kerr black hole metric beyond General Relativity and make an estimate for the possible deviations from the Kerr solution with the data of GW 150914. We here study the strong gravitational lensing in such a rotating non-Kerr spacetime with an extra deformation parameter. We find that the condition of existence of horizons is not inconsistent with that of the marginally circular photon orbit. Moreover, the deflection angle of the light ray near the weakly naked singularity covered by the marginally circular orbit diverges logarithmically in the strong-field limit. In the case ofmore » the completely naked singularity, the deflection angle near the singularity tends to a certain finite value, whose sign depends on the rotation parameter and the deformation parameter. These properties of strong gravitational lensing are different from those in the Johannsen-Psaltis rotating non-Kerr spacetime and in the Janis-Newman-Winicour spacetime. Modeling the supermassive central object of the Milk Way Galaxy as a Konoplya-Zhidenko rotating non-Kerr compact object, we estimated the numerical values of observables for the strong gravitational lensing including the time delay between two relativistic images.« less

Black and gray Helmholtz-Kerr soliton refraction

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

Sanchez-Curto, Julio; Chamorro-Posada, Pedro; McDonald, Graham S.

Refraction of black and gray solitons at boundaries separating different defocusing Kerr media is analyzed within a Helmholtz framework. A universal nonlinear Snell's law is derived that describes gray soliton refraction, in addition to capturing the behavior of bright and black Kerr solitons at interfaces. Key regimes, defined by beam and interface characteristics, are identified, and predictions are verified by full numerical simulations. The existence of a unique total nonrefraction angle for gray solitons is reported; both internal and external refraction at a single interface is shown possible (dependent only on incidence angle). This, in turn, leads to the proposalmore » of positive or negative lensing operations on soliton arrays at planar boundaries.« less

Self-force correction to geodetic spin precession in Kerr spacetime

NASA Astrophysics Data System (ADS)

Akcay, Sarp

2017-08-01

We present an expression for the gravitational self-force correction to the geodetic spin precession of a spinning compact object with small, but non-negligible mass in a bound, equatorial orbit around a Kerr black hole. We consider only conservative backreaction effects due to the mass of the compact object (m1), thus neglecting the effects of its spin s1 on its motion; i.e., we impose s1≪G m12/c and m1≪m2, where m2 is the mass parameter of the background Kerr spacetime. We encapsulate the correction to the spin precession in ψ , the ratio of the accumulated spin-precession angle to the total azimuthal angle over one radial orbit in the equatorial plane. Our formulation considers the gauge-invariant O (m1) part of the correction to ψ , denoted by Δ ψ , and is a generalization of the results of Akcay et al. [Classical Quantum Gravity 34, 084001 (2017), 10.1088/1361-6382/aa61d6] to Kerr spacetime. Additionally, we compute the zero-eccentricity limit of Δ ψ and show that this quantity differs from the circular orbit Δ ψcirc by a gauge-invariant quantity containing the gravitational self-force correction to general relativistic periapsis advance in Kerr spacetime. Our result for Δ ψ is expressed in a manner that readily accommodates numerical/analytical self-force computations, e.g., in the radiation gauge, and paves the way for the computation of a new eccentric-orbit Kerr gauge invariant beyond the generalized redshift.

A tunable optical Kerr switch based on a nanomechanical resonator coupled to a quantum dot.

PubMed

Li, Jin-Jin; Zhu, Ka-Di

2010-05-21

We have theoretically demonstrated the large enhancement of the optical Kerr effect in a scheme of a nanomechanical resonator coupled to a quantum dot and shown that this phenomenon can be used to realize a fast optical Kerr switch by turning the control field on or off. Due to the vibration of the nanoresonator, as we pump on the strong control beam, the optical spectrum shows that the magnitude of this optical Kerr effect is proportional to the intensity of the control field. In this case, a fast and tunable optical Kerr switch can be implemented easily by an intensity-adjustable laser. Based on this tunable optical Kerr switch, we also provide a detection method to measure the frequency of the nanomechanical resonator in this coupled system.

Logarithmic corrections to black hole entropy from Kerr/CFT

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

Pathak, Abhishek; Porfyriadis, Achilleas P.; Strominger, Andrew

It has been shown by A. Sen that logarithmic corrections to the black hole area-entropy law are entirely determined macroscopically from the massless particle spectrum. They therefore serve as powerful consistency checks on any proposed enumeration of quantum black hole microstates. Furthermore, Sen’s results include a macroscopic computation of the logarithmic corrections for a five-dimensional near extremal Kerr-Newman black hole. We compute these corrections microscopically using a stringy embedding of the Kerr/CFT correspondence and find perfect agreement.

Logarithmic corrections to black hole entropy from Kerr/CFT

DOE PAGES

Pathak, Abhishek; Porfyriadis, Achilleas P.; Strominger, Andrew; ...

2017-04-14

It has been shown by A. Sen that logarithmic corrections to the black hole area-entropy law are entirely determined macroscopically from the massless particle spectrum. They therefore serve as powerful consistency checks on any proposed enumeration of quantum black hole microstates. Furthermore, Sen’s results include a macroscopic computation of the logarithmic corrections for a five-dimensional near extremal Kerr-Newman black hole. We compute these corrections microscopically using a stringy embedding of the Kerr/CFT correspondence and find perfect agreement.

Repulsive Effect for Unbound High Energy Particles Along Rotation Axis in Kerr-Taub-NUT Spacetime

NASA Astrophysics Data System (ADS)

Zhang, Lu; Chen, Song-Bai

2018-04-01

We have investigated the acceleration of the unbound high energy particles moving along the rotation axis in the Kerr-Taub-NUT spacetime, and then study the dependence of the repulsive effects on the NUT charge for the particles in the spacetime. Whether the repulsive effects with the NUT charge become stronger depends on the Carter constant, the position and velocity of the particles themselves. We also present numerically the changes of the observable velocity and acceleration with the NUT charge for the unbound particles in the Kerr-Taub-NUT spacetime. Supported by the Scientific Research Fund of Hunan Provincial Education Department under Grant No. 17A124, and the Construct Program of Key Disciplines in Hunan Province

Quasilocal energy and surface geometry of Kerr spacetime

NASA Astrophysics Data System (ADS)

Yu, Chengjie; Liu, Jian-Liang

2017-04-01

We study the quasilocal energy (QLE) and the surface geometry for Kerr spacetime in the Boyer-Lindquist coordinates without taking the slow rotation approximation. We also consider in the region r ≤2 m , which is inside the ergosphere. For a certain region, r >rk(a ) , the Gaussian curvature of the surface with constant t , r is positive, and for r >√{3 }a the critical value of the QLE is positive. We found that the three curves: the outer horizon r =r+(a ), r =rk(a ) and r =√{3 }a intersect at the point a =√{3 }m /2 , which is the limit for the horizon to be isometrically embedded into R3. The numerical result indicates that the Kerr QLE is monotonically decreasing to the ADM m from the region inside the ergosphere to large r . Based on the second law of black hole dynamics, the QLE is increasing with respect to the irreducible mass Mir. From the results of Chen-Wang-Yau, we conclude that in a certain region, r >rh(a ), the critical value of the Kerr QLE is a global minimum.

Ergosurfaces for Kerr black holes with scalar hair

NASA Astrophysics Data System (ADS)

Herdeiro, Carlos; Radu, Eugen

2014-06-01

We have recently reported the existence of Kerr black holes with scalar hair in General Relativity minimally coupled to a massive, complex scalar field [C. Herdeiro and E. Radu, Phys. Rev. Lett. 112, 221101 (2014)]. These solutions interpolate between boson stars and Kerr black holes. The latter have a well-known topologically S2 ergosurface (ergosphere) whereas the former develop a S1×S1 ergosurface (ergotorus) in a region of parameter space. We show that hairy black holes always have an ergoregion, and that this region is delimited by either an ergosphere or an ergo-Saturn—i.e. a S2⊕(S1×S1) ergosurface. In the phase space of solutions, the ergotorus can either appear disconnected from the ergosphere or pinch off from it. We provide a heuristic argument, based on a measure of the size of the ergoregion, that superradiant instabilities—which are likely to be present—are weaker for hairy black holes than for Kerr black holes with the same global charges. We observe that Saturn-like, and even more remarkable, ergosurfaces should also arise for other rotating "hairy" black holes.

Magneto-optical Kerr rotation and color in ultrathin lossy dielectric

NASA Astrophysics Data System (ADS)

Zhang, Jing; Wang, Hai; Qu, Xin; Zhou, Yun song; Li, Li na

2017-05-01

Ultra-thin optical coating comprising nanometer-thick silicon absorbing films on iron substrates can display strong optical interference effects. A resonance peak of ∼1.6^\\circ longitudinal Kerr rotation with the silicon thickness of ∼47 \\text{nm} was found at the wavelength of 660 nm. The optical properties of silicon thin films were well controlled by the sputtering power. Non-iridescence color exhibition and Kerr rotation enhancement can be manipulated and encoded individually.

Analytical study of a Kerr-Sen black hole and a charged massive scalar field

NASA Astrophysics Data System (ADS)

Bernard, Canisius

2017-11-01

It is reported that Kerr-Newman and Kerr-Sen black holes are unstable to perturbations of charged massive scalar field. In this paper, we study analytically the complex frequencies which characterize charged massive scalar fields in a near-extremal Kerr-Sen black hole. For near-extremal Kerr-Sen black holes and for charged massive scalar fields in the eikonal large-mass M ≫μ regime, where M is the mass of the black hole, and μ is the mass of the charged scalar field, we have obtained a simple expression for the dimensionless ratio ωI/(ωR-ωc) , where ωI and ωR are, respectively, the imaginary and real parts of the frequency of the modes, and ωc is the critical frequency for the onset of super-radiance. We have also found our expression is consistent with the result of Hod [Phys. Rev. D 94, 044036 (2016), 10.1103/PhysRevD.94.044036] for the case of a near-extremal Kerr-Newman black hole and the result of Zouros and Eardly [Ann. Phys. (N.Y.) 118, 139 (1979), 10.1016/0003-4916(79)90237-9] for the case of neutral scalar fields in the background of a near-extremal Kerr black hole.

Routes to spatiotemporal chaos in Kerr optical frequency combs.

PubMed

Coillet, Aurélien; Chembo, Yanne K

2014-03-01

We investigate the various routes to spatiotemporal chaos in Kerr optical frequency combs, obtained through pumping an ultra-high Q-factor whispering-gallery mode resonator with a continuous-wave laser. The Lugiato-Lefever model is used to build bifurcation diagrams with regards to the parameters that are externally controllable, namely, the frequency and the power of the pumping laser. We show that the spatiotemporal chaos emerging from Turing patterns and solitons display distinctive dynamical features. Experimental spectra of chaotic Kerr combs are also presented for both cases, in excellent agreement with theoretical spectra.

Anadarko's Proposed Acquisition of Kerr-McGee and Western Gas Resources

EIA Publications

2006-01-01

Presentation of company-level, non-proprietary data and relevant aggregate data for worldwide oil and natural gas reserves and production of Anadarko, Kerr-McGee, and Western Gas Resources to inform discussions of Anadarko Petroleum Corp.'s proposed acquisition of both Kerr-McGee Corp. and Western Gas Resources Inc. for a total of $23.3 billion, which was announced June 23, 2006.

Designing Kerr interactions using multiple superconducting qubit types in a single circuit

NASA Astrophysics Data System (ADS)

Elliott, Matthew; Joo, Jaewoo; Ginossar, Eran

2018-02-01

The engineering of Kerr interactions is of great interest for processing quantum information in multipartite quantum systems and for investigating many-body physics in a complex cavity-qubit network. We study how coupling multiple different types of superconducting qubits to the same cavity modes can be used to modify the self- and cross-Kerr effects acting on the cavities and demonstrate that this type of architecture could be of significant benefit for quantum technologies. Using both analytical perturbation theory results and numerical simulations, we first show that coupling two superconducting qubits with opposite anharmonicities to a single cavity enables the effective self-Kerr interaction to be diminished, while retaining the number splitting effect that enables control and measurement of the cavity field. We demonstrate that this reduction of the self-Kerr effect can maintain the fidelity of coherent states and generalised Schrödinger cat states for much longer than typical coherence times in realistic devices. Next, we find that the cross-Kerr interaction between two cavities can be modified by coupling them both to the same pair of qubit devices. When one of the qubits is tunable in frequency, the strength of entangling interactions between the cavities can be varied on demand, forming the basis for logic operations on the two modes. Finally, we discuss the feasibility of producing an array of cavities and qubits where intermediary and on-site qubits can tune the strength of self- and cross-Kerr interactions across the whole system. This architecture could provide a way to engineer interesting many-body Hamiltonians and be a useful platform for quantum simulation in circuit quantum electrodynamics.

Enhancement of optical Kerr effect in quantum-cascade lasers with multiple resonance levels.

PubMed

Bai, Jing; Citrin, D S

2008-08-18

In this paper, we investigated the optical Kerr lensing effect in quantum-cascade lasers with multiple resonance levels. The Kerr refractive index n2 is obtained through the third-order susceptibility at the fundamental frequency chi(3)( omega; omega, omega,-omega). Resonant two-photon processes are found to have almost equal contributions to chi(3)( omega; omega, omega,-omega) as the single-photon processes, which result in the predicted enhancement of the positive nonlinear (Kerr) refractive index, and thus may enhance mode-locking of quantum-cascade lasers. Moreover, we also demonstrate an isospectral optimization strategy for further improving n2 through the band-structure design, in order to boost the multimode performance of quantum-cascade lasers. Simulation results show that the optimized stepwise multiple-quantum-well structure has n2 approximately 10-8 cm2/W, a twofold enhancement over the original flat quantum-well structure. This leads to a refractive-index change (delta)n of about 0.01, which is at the upper bound of those reported for typical Kerr medium. This stronger Kerr refractive index may be important for quantum-cascade lasers ultimately to demonstrate self-mode-locking.

Scalar Dyon Production In Near Extremal Kerr-Newman Black Holes

NASA Astrophysics Data System (ADS)

Chen, Chiang-Mei; Kim, Sang Pyo; Sun, Jia-Rui; Tang, Fu-Yi

2018-01-01

The pair production of charged scalar dyons is analytically studied in near-extremal Kerr-Newman (KN) dyonic black holes. The pair production rate and its thermal interpretation are given. Moreover, the absorption cross section ratio has been compared with the two-point function of the conformal field theories (CFTs) holographically dual to the near horizon geometry, namely warped AdS3, of the near extremal Kerr-Newman black holes to verify the threefold dyonic KN/CFTs correspondence.

Eruptive Massive Vector Particles of 5-Dimensional Kerr-Gödel Spacetime

NASA Astrophysics Data System (ADS)

Övgün, A.; Sakalli, I.

2018-02-01

In this paper, we investigate Hawking radiation of massive spin-1 particles from 5-dimensional Kerr-Gödel spacetime. By applying the WKB approximation and the Hamilton-Jacobi ansatz to the relativistic Proca equation, we obtain the quantum tunneling rate of the massive vector particles. Using the obtained tunneling rate, we show how one impeccably computes the Hawking temperature of the 5-dimensional Kerr-Gödel spacetime.

Theory of Kerr and Faraday rotations and linear dichroism in Topological Weyl Semimetals.

PubMed

Kargarian, Mehdi; Randeria, Mohit; Trivedi, Nandini

2015-08-03

We consider the electromagnetic response of a topological Weyl semimetal (TWS) with a pair of Weyl nodes in the bulk and corresponding Fermi arcs in the surface Brillouin zone. We compute the frequency-dependent complex conductivities σαβ(ω) and also take into account the modification of Maxwell equations by the topological θ-term to obtain the Kerr and Faraday rotations in a variety of geometries. For TWS films thinner than the wavelength, the Kerr and Faraday rotations, determined by the separation between Weyl nodes, are significantly larger than in topological insulators. In thicker films, the Kerr and Faraday angles can be enhanced by choice of film thickness and substrate refractive index. We show that, for radiation incident on a surface with Fermi arcs, there is no Kerr or Faraday rotation but the electric field develops a longitudinal component inside the TWS, and there is linear dichroism signal. Our results have implications for probing the TWS phase in various experimental systems.

Direct diode-pumped Kerr-lens mode-locked Ti:sapphire laser

PubMed Central

Durfee, Charles G.; Storz, Tristan; Garlick, Jonathan; Hill, Steven; Squier, Jeff A.; Kirchner, Matthew; Taft, Greg; Shea, Kevin; Kapteyn, Henry; Murnane, Margaret; Backus, Sterling

2012-01-01

We describe a Ti:sapphire laser pumped directly with a pair of 1.2W 445nm laser diodes. With over 30mW average power at 800 nm and a measured pulsewidth of 15fs, Kerr-lens-modelocked pulses are available with dramatically decreased pump cost. We propose a simple model to explain the observed highly stable Kerr-lens modelocking in spite of the fact that both the mode-locked and continuous-wave modes are smaller than the pump mode in the crystal. PMID:22714433

Enhanced Kerr nonlinearity in a quantized four-level graphene nanostructure

NASA Astrophysics Data System (ADS)

Ghahraman, Solookinejad; M, Panahi; E, Ahmadi; Seyyed, Hossein Asadpour

2016-07-01

In this paper, a new model is proposed for manipulating the Kerr nonlinearity of right-hand circular probe light in a monolayer of graphene nanostructure. By using the density matrix equations and quantum optical approach, the third-order susceptibility of probe light is explored numerically. It is realized that the enhanced Kerr nonlinearity with zero linear absorption can be provided by selecting the appropriate quantities of controllable parameters, such as Rabi frequency and elliptical parameter of elliptical polarized coupling field. Our results may be useful applications in future all-optical system devices in nanostructures.

Source of the Kerr-Newman solution as a gravitating bag model: 50 years of the problem of the source of the Kerr solution

NASA Astrophysics Data System (ADS)

Burinskii, Alexander

2016-01-01

It is known that gravitational and electromagnetic fields of an electron are described by the ultra-extreme Kerr-Newman (KN) black hole solution with extremely high spin/mass ratio. This solution is singular and has a topological defect, the Kerr singular ring, which may be regularized by introducing the solitonic source based on the Higgs mechanism of symmetry breaking. The source represents a domain wall bubble interpolating between the flat region inside the bubble and external KN solution. It was shown recently that the source represents a supersymmetric bag model, and its structure is unambiguously determined by Bogomolnyi equations. The Dirac equation is embedded inside the bag consistently with twistor structure of the Kerr geometry, and acquires the mass from the Yukawa coupling with Higgs field. The KN bag turns out to be flexible, and for parameters of an electron, it takes the form of very thin disk with a circular string placed along sharp boundary of the disk. Excitation of this string by a traveling wave creates a circulating singular pole, indicating that the bag-like source of KN solution unifies the dressed and point-like electron in a single bag-string-quark system.

Spinning BTZ black hole versus Kerr black hole: A closer look

NASA Astrophysics Data System (ADS)

Kim, Hongsu

1999-03-01

By applying Newman's algorithm, the AdS3 rotating black hole solution is ``derived'' from the nonrotating black hole solution of Bañados, Teitelboim, and Zanelli (BTZ). The rotating BTZ solution derived in this fashion is given in ``Boyer-Lindquist-type'' coordinates whereas the form of the solution originally given by BTZ is given in kind of ``unfamiliar'' coordinates which are related to each other by a transformation of time coordinate alone. The relative physical meaning between these two time coordinates is carefully studied. Since the Kerr-type and Boyer-Lindquist-type coordinates for rotating BTZ solution are newly found via Newman's algorithm, the transformation to Kerr-Schild-type coordinates is looked for. Indeed, such a transformation is found to exist. In these Kerr-Schild-type coordinates, a truly maximal extension of its global structure by analytically continuing to an ``antigravity universe'' region is carried out.

Dynamical Formation of Kerr Black Holes with Synchronized Hair: An Analytic Model

NASA Astrophysics Data System (ADS)

Herdeiro, Carlos A. R.; Radu, Eugen

2017-12-01

East and Pretorius have successfully evolved, using fully nonlinear numerical simulations, the superradiant instability of the Kerr black hole (BH) triggered by a massive, complex vector field. Evolutions terminate in stationary states of a vector field condensate synchronized with a rotating BH horizon. We show that these end points are fundamental states of Kerr BHs with synchronized Proca hair. Motivated by the "experimental data" from these simulations, we suggest a universal (i.e., field-spin independent), analytic model for the subset of BHs with synchronized hair that possess a quasi-Kerr horizon, applicable in the weak hair regime. Comparing this model with fully nonlinear numerical solutions of BHs with a synchronized scalar or Proca hair, we show that the model is accurate for hairy BHs that may emerge dynamically from superradiance, whose domain we identify.

Dynamical Formation of Kerr Black Holes with Synchronized Hair: An Analytic Model.

PubMed

Herdeiro, Carlos A R; Radu, Eugen

2017-12-29

East and Pretorius have successfully evolved, using fully nonlinear numerical simulations, the superradiant instability of the Kerr black hole (BH) triggered by a massive, complex vector field. Evolutions terminate in stationary states of a vector field condensate synchronized with a rotating BH horizon. We show that these end points are fundamental states of Kerr BHs with synchronized Proca hair. Motivated by the "experimental data" from these simulations, we suggest a universal (i.e., field-spin independent), analytic model for the subset of BHs with synchronized hair that possess a quasi-Kerr horizon, applicable in the weak hair regime. Comparing this model with fully nonlinear numerical solutions of BHs with a synchronized scalar or Proca hair, we show that the model is accurate for hairy BHs that may emerge dynamically from superradiance, whose domain we identify.

Kerr-like behaviour of second harmonic generation in the far-off resonant regime

NASA Astrophysics Data System (ADS)

Peřinová, Vlasta; Lukš, Antonín; Křepelka, Jaromír; Leoński, Wiesław; Peřina, Jan

2018-05-01

We separate the Kerr-like behaviour of the second-harmonic generation in the far-off resonant regime from the oscillations caused by the time-dependence of the interaction energy. To this purpose, we consider the approximation obtained from the exact dynamics by the method of small rotations. The Floquet-type decomposition of the approximate dynamics comprises the Kerr-like dynamics and oscillations of the same order of magnitude as those assumed for the exact dynamics of the second-harmonic generation. We have found that a superposition of two states of concentrated quantum phase arises in the fundamental mode in the second-harmonic generation in the far-off resonant limit at a later time than a superposition of two coherent states in the corresponding Kerr medium and the difference is larger for higher initial coherent amplitudes. The quantum phase fluctuation is higher for the same initial coherent amplitudes in the fundamental mode in the second-harmonic generation in the far-off resonant limit than in the corresponding Kerr medium and the difference is larger for higher initial coherent amplitudes.

Closed Conformal Killing-Yano Tensor and Uniqueness of Generalized Kerr-NUT-de Sitter Spacetime

NASA Astrophysics Data System (ADS)

Houri, Tsuyoshi

We classify all spacetimes with a rank-2 closed conformal Killing-Yano tensor. They give a generalization of Kerr-NUT-de Sitter spacetime. The Einstein condition is explicitly solved. The Kerr-NUT-de Sitter spacetime is obtained as a spacetime with a non-degenerate CKY tensor.

Physical Properties of the Double Kerr Solution

NASA Astrophysics Data System (ADS)

Herdeiro, Carlos A. R.; Rebelo, Carmen

We consider two special cases, dubbed counter-rotating and co-rotating of the double-Kerr solution, in four spacetime dimensions. We discuss how various physical properties of the black holes vary as the distance between them varies, namely: the horizon angular velocity and extremality condition, the horizon and ergo-surface geometry.

Nearly deterministic quantum Fredkin gate based on weak cross-Kerr nonlinearity

NASA Astrophysics Data System (ADS)

Wu, Yun-xiang; Zhu, Chang-hua; Pei, Chang-xing

2016-09-01

A scheme of an optical quantum Fredkin gate is presented based on weak cross-Kerr nonlinearity. By an auxiliary coherent state with the cross-Kerr nonlinearity effect, photons can interact with each other indirectly, and a non-demolition measurement for photons can be implemented. Combined with the homodyne detection, classical feedforward, polarization beam splitters and Pauli-X operations, a controlled-path gate is constructed. Furthermore, a quantum Fredkin gate is built based on the controlled-path gate. The proposed Fredkin gate is simple in structure and feasible by current experimental technology.

Combined three-axis surface magneto-optical Kerr effects in the study of surface and ultrathin-film magnetism

NASA Astrophysics Data System (ADS)

Yang, Z. J.; Scheinfein, M. R.

1993-12-01

Surface and ultrathin-film magnetocrystalline anisotropy in epitaxial fcc Fe thin films grown on room-temperature Cu(100) single crystals has been investigated, in situ, by the combined surface magneto-optical Kerr effects (SMOKE). In polar, longitudinal, and transverse Kerr effects, the direction of the applied magnetic field must be distinguished from the direction of magnetization during the switching process. For arbitrary orientations of the magnetization and field axis relative to the optical scattering plane, any of the three Kerr effects may contribute to the detected signal. A general expression for the normalized light intensity sensed by a photodiode detector, involving all three combined Kerr effects, is obtained both in the ultrathin-film limit and for bulk, at general oblique incidence angles and with different orientations of the polarizer, modulator, and analyzer. This expression is used to interpret the results of fcc Fe/Cu(100) SMOKE measurements. For films grown at room temperature, polar and longitudinal Kerr-effect magnetization loops show that the easy axis of magnetization rotates from the (canted) out-of-plane direction to the in-plane direction at a thickness of about 4.7 monolayers. Transverse Kerr-effect measurements indicate that the in-plane easy axes are biaxial.

Using iron line reverberation and spectroscopy to distinguish Kerr and non-Kerr black holes

NASA Astrophysics Data System (ADS)

Jiang, Jiachen; Bambi, Cosimo; Steiner, James F.

2015-05-01

The iron Kα line commonly observed in the X-ray spectrum of both stellar-mass and supermassive black hole candidates is produced by the illumination of a cold accretion disk by a hot corona. In this framework, the activation of a new flaring region in the hot corona imprints a time variation on the iron line spectrum. Future X-ray facilities with high time resolution and large effective areas may be able to measure the so-called 2-dimensional transfer function; that is, the iron line profile detected by a distant observer as a function of time in response to an instantaneous flare from the X-ray primary source. This work is a preliminary study to determine if and how such a technique can provide more information about the spacetime geometry around the compact object than the already possible measurements of the time-integrated iron line profile. Within our simplified model, we find that a measurement of iron line reverberation can improve constraints appreciably given a sufficiently strong signal, though that most of the information is present in the time-integrated spectrum. Our aim is to test the Kerr metric. We find that current X-ray facilities and data are unable to provide strong tests of the Kerr nature of supermassive black hole candidates. We consider an optimistic case of 105 iron line photons from a next-generation data set. With such data, the reverberation model improves upon the spectral constraint by an order of magnitude.

Kerr-McGee and the NRC: from Indian country to Silkwood to Gore.

PubMed

Baer, H

1990-01-01

By focusing upon the Nuclear Regulatory Commission's appraisal of the Kerr-McGee Corporation's safety record in the Four Corners area and at two facilities in Oklahoma, this article examines the political economy of nuclear regulation in American society. Particular attention is given to the agency's response to intervenor groups which protested various operations at Kerr-McGee facility in Gore, Oklahoma, both prior to and following the accidental rupture of a cylinder containing uranium hexafluoride. Despite a consistent record of violations and nuclear mishaps by Kerr-McGee, the Nuclear Regulatory Commission permitted the company to essentially monitor its own activities. Rather than protecting workers and the public from the hazards of the nuclear industry, state regulation attempts to legitimize and defuse public opposition to its endeavors.

Testing the Kerr metric with the iron line and the KRZ parametrization

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

Ni, Yueying; Jiang, Jiachen; Bambi, Cosimo, E-mail: yyni13@fudan.edu.cn, E-mail: jcjiang12@fudan.edu.cn, E-mail: bambi@fudan.edu.cn

The spacetime geometry around astrophysical black holes is supposed to be well approximated by the Kerr metric, but deviations from the Kerr solution are predicted in a number of scenarios involving new physics. Broad iron Kα lines are commonly observed in the X-ray spectrum of black holes and originate by X-ray fluorescence of the inner accretion disk. The profile of the iron line is sensitively affected by the spacetime geometry in the strong gravity region and can be used to test the Kerr black hole hypothesis. In this paper, we extend previous work in the literature. In particular: i )more » as test-metric, we employ the parametrization recently proposed by Konoplya, Rezzolla, and Zhidenko, which has a number of subtle advantages with respect to the existing approaches; ii ) we perform simulations with specific X-ray missions, and we consider NuSTAR as a prototype of current observational facilities and eXTP as an example of the next generation of X-ray observatories. We find a significant difference between the constraining power of NuSTAR and eXTP. With NuSTAR, it is difficult or impossible to constrain deviations from the Kerr metric. With eXTP, in most cases we can obtain quite stringent constraints (modulo we have the correct astrophysical model).« less

Compact singularity-free Kerr-Newman-de Sitter instantons

NASA Astrophysics Data System (ADS)

Chruściel, Piotr T.; Hörzinger, Michael

2017-04-01

Generalizing the results in Chruściel and Hörzinger [J. High Energy Phys. 16 (2016) 1, 10.1007/JHEP04(2016)012], we construct further families of compact Einstein-Maxwell instantons associated with the Kerr-Newman metrics with a positive cosmological constant.

Properties of the distorted Kerr black hole

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

Abdolrahimi, Shohreh; Tzounis, Christos; Kunz, Jutta

We investigate the properties of the ergoregion and the location of the curvature singularities for the Kerr black hole distorted by the gravitational field of external sources. The particular cases of quadrupole and octupole distortion are studied in detail. We also investigate the scalar curvature invariants of the horizon and compare their behaviour with the case of the isolated Kerr black hole. In a certain region of the parameter space the ergoregion consists of a compact region encompassing the horizon and a disconnected part extending to infinity. The curvature singularities in the domain of outer communication, when they exist, aremore » always located on the boundary of the ergoregion. We present arguments that they do not lie on the compact ergosurface. For quadrupole distortion the compact ergoregion size is negatively correlated with the horizon angular momentum when the external sources are varied. For octupole distortion infinitely many ergoregion configurations can exist for a certain horizon angular momentum. For some special cases we can have J{sup 2}/M{sup 4} > 1 and yet avoid a naked singularity.« less

Effective Hamiltonian approach to the Kerr nonlinearity in an optomechanical system

NASA Astrophysics Data System (ADS)

Gong, Z. R.; Ian, H.; Liu, Yu-Xi; Sun, C. P.; Nori, Franco

2009-12-01

Using the Born-Oppenheimer approximation, we derive an effective Hamiltonian for an optomechanical system that leads to a nonlinear Kerr effect in the system’s vacuum. The oscillating mirror at one edge of the optomechanical system induces a squeezing effect in the intensity spectrum of the cavity field. A near-resonant laser field is applied at the other edge to drive the cavity field in order to enhance the Kerr effect. We also propose a quantum-nondemolition-measurement setup to monitor a system with two cavities separated by a common oscillating mirror based on our effective Hamiltonian approach.

Kerr Reservoir LANDSAT experiment analysis for March 1981

NASA Technical Reports Server (NTRS)

Lecroy, S. R. (Principal Investigator)

1982-01-01

LANDSAT radiance data were used in an experiment conducted on the waters of Kerr Reservoir to determine if reliable algorithms could be developed that relate water quality parameters to remotely sensed data. A mix of different types of algorithms using the LANDSAT bands was generated to provide a thorough understanding of the relationships among the data involved. Except for secchi depth, the study demonstrated that for the ranges measured, the algorithms that satisfactorily represented the data encompass a mix of linear and nonlinear forms using only one LANDSAT band. Ratioing techniques did not improve the results since the initial design of the experiment minimized the errors against which this procedure is effective. Good correlations were found for total suspended solids, iron, turbidity, and secchi depth. Marginal correlations were discovered for nitrate and tannin + lignin. Quantification maps of Kerr Reservoir are presented for many of the water quality parameters using the developed algorithms.

Trumpet slices in Kerr spacetimes.

PubMed

Dennison, Kenneth A; Baumgarte, Thomas W; Montero, Pedro J

2014-12-31

We introduce a new time-independent family of analytical coordinate systems for the Kerr spacetime representing rotating black holes. We also propose a (2+1)+1 formalism for the characterization of trumpet geometries. Applying this formalism to our new family of coordinate systems we identify, for the first time, analytical and stationary trumpet slices for general rotating black holes, even for charged black holes in the presence of a cosmological constant. We present results for metric functions in this slicing and analyze the geometry of the rotating trumpet surface.

Magnetic Field-Dependent Magneto-Optical Kerr Effect in [(GeTe)2(Sb2Te3)1]8 Topological Superlattice

NASA Astrophysics Data System (ADS)

Bang, Do; Awano, Hiroyuki; Saito, Yuta; Tominaga, Junji

2016-05-01

We studied the magnetic field dependence of magneto-optical Kerr rotation of the [(GeTe)2/(Sb2Te3)1]8 topological superlattice at different temperatures (from 300 K to 440 K). At low temperatures (less than 360 K), the Kerr signal was within noise level. However, large Kerr rotation peaks with a mirror symmetric loop were at high temperatures (higher than 360 K). The temperature dependence of the observed Kerr signal can be attributed to the breaking of spatial inversion symmetry, which induces a narrow gap in surface state bands due to the Ge atomic layer movement-induced phase transition in the superlattice. We found that the resonant field of each Kerr peak gradually decreases with increasing temperature. On the other hand, the phase transition from a high temperature phase to a low temperature one could be controlled by external magnetic fields.

Magneto-optical fingerprints of distinct graphene multilayers using the giant infrared Kerr effect

NASA Astrophysics Data System (ADS)

Ellis, Chase T.; Stier, Andreas V.; Kim, Myoung-Hwan; Tischler, Joseph G.; Glaser, Evan R.; Myers-Ward, Rachael L.; Tedesco, Joseph L.; Eddy, Charles R.; Gaskill, D. Kurt; Cerne, John

2013-11-01

The remarkable electronic properties of graphene strongly depend on the thickness and geometry of graphene stacks. This wide range of electronic tunability is of fundamental interest and has many applications in newly proposed devices. Using the mid-infrared, magneto-optical Kerr effect, we detect and identify over 18 interband cyclotron resonances (CR) that are associated with ABA and ABC stacked multilayers as well as monolayers that coexist in graphene that is epitaxially grown on 4H-SiC. Moreover, the magnetic field and photon energy dependence of these features enable us to explore the band structure, electron-hole band asymmetries, and mechanisms that activate a CR response in the Kerr effect for various multilayers that coexist in a single sample. Surprisingly, we find that the magnitude of monolayer Kerr effect CRs is not temperature dependent. This unexpected result reveals new questions about the underlying physics that makes such an effect possible.

Testing the Kerr Black Hole Hypothesis Using X-Ray Reflection Spectroscopy

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

Bambi, Cosimo; Nampalliwar, Sourabh; Cárdenas-Avendaño, Alejandro

We present the first X-ray reflection model for testing the assumption that the metric of astrophysical black holes is described by the Kerr solution. We employ the formalism of the transfer function proposed by Cunningham. The calculations of the reflection spectrum of a thin accretion disk are split into two parts: the calculation of the transfer function and the calculation of the local spectrum at any emission point in the disk. The transfer function only depends on the background metric and takes into account all the relativistic effects (gravitational redshift, Doppler boosting, and light bending). Our code computes the transfermore » function for a spacetime described by the Johannsen metric and can easily be extended to any stationary, axisymmetric, and asymptotically flat spacetime. Transfer functions and single line shapes in the Kerr metric are compared to those calculated from existing codes to check that we reach the necessary accuracy. We also simulate some observations with NuSTAR and LAD/eXTP and fit the data with our new model to show the potential capabilities of current and future observations to constrain possible deviations from the Kerr metric.« less

Josephson Metamaterial with a Widely Tunable Positive or Negative Kerr Constant

NASA Astrophysics Data System (ADS)

Zhang, Wenyuan; Huang, W.; Gershenson, M. E.; Bell, M. T.

2017-11-01

We report on the microwave characterization of a novel one-dimensional Josephson metamaterial composed of a chain of asymmetric superconducting quantum interference devices with nearest-neighbor coupling through common Josephson junctions. This metamaterial demonstrates a strong Kerr nonlinearity, with a Kerr constant tunable over a wide range, from positive to negative values, by a magnetic flux threading the superconducting quantum interference devices. The experimental results are in good agreement with the theory of nonlinear effects in Josephson chains. The metamaterial is very promising as an active medium for Josephson traveling-wave parametric amplifiers; its use facilitates phase matching in a four-wave-mixing process for efficient parametric gain.

Dark-bright quadratic solitons with a focusing effective Kerr nonlinearity

NASA Astrophysics Data System (ADS)

Chen, Manna; Ping, Xiaorou; Liang, Guo; Guo, Qi; Lu, Daquan; Hu, Wei

2018-01-01

Dark solitons are traditionally considered to exist in defocusing Kerr nonlinearity media. We investigate dark quadratic solitons with a focusing effective Kerr nonlinearity and a sine-oscillatory nonlocal response. A nonlinear refractive index with a focusing sine-oscillatory response leads to a defocusing effect with a strong degree of nonlocality, which causes the formation of dark solitons. By analyzing the modulational instability, we determine the parameter domain for dark quadratic solitons with a stable background and numerically obtain dark-bright soliton solutions in the form of pairs, which avoid radiative phenomena. Based on a numerical simulation, we find that all dark-bright soliton pairs are unstable after a relatively long propagation distance, and their stabilities are affected by the soliton interval and the degree of nonlocality.

Propagation of a Pearcey-Gaussian-vortex beam in free space and Kerr media

NASA Astrophysics Data System (ADS)

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

2016-12-01

The propagation of a Pearcey-Gaussian-vortex beam (PGVB) has been investigated numerically in free space and Kerr media. In addition, we have done a numerical experiment for the beam in free space. A PGVB maintains the characteristics of auto-focusing, self-healing and form-invariance which are possessed by a Pearcey beam and a Pearcey-Gaussian beam. Due to the influence of the optical vortex, a bright speck occurs in front of the main lobe. Compared with a Pearcey beam and a Pearcey-Gaussian beam, a PGVB has the most remarkable intensity singularity and the phase singularity. It is worth noting that the impact of the vortex at the coordinate origins means that a PGVB in the vicinity carries no angular momentum or transverse energy flow. We have investigated and numerically simulated the transverse intensity of a PGVB in Kerr media. We find that the auto-focusing of a PGVB in a Kerr medium becomes stronger with increasing power.

Algorithmic characterization results for the Kerr-NUT-(A)dS space-time. II. KIDs for the Kerr-(A)(de Sitter) family

NASA Astrophysics Data System (ADS)

Paetz, Tim-Torben

2017-04-01

We characterize Cauchy data sets leading to vacuum space-times with vanishing Mars-Simon tensor. This approach provides an algorithmic procedure to check whether a given initial data set (Σ ,hi j,Ki j) evolves into a space-time which is locally isometric to a member of the Kerr-(A)(dS) family.

Critical exponents of extremal Kerr perturbations

NASA Astrophysics Data System (ADS)

Gralla, Samuel E.; Zimmerman, Peter

2018-05-01

We show that scalar, electromagnetic, and gravitational perturbations of extremal Kerr black holes are asymptotically self-similar under the near-horizon, late-time scaling symmetry of the background metric. This accounts for the Aretakis instability (growth of transverse derivatives) as a critical phenomenon associated with the emergent symmetry. We compute the critical exponent of each mode, which is equivalent to its decay rate. It follows from symmetry arguments that, despite the growth of transverse derivatives, all generally covariant scalar quantities decay to zero.

Diode-pumped Kerr-lens mode-locked Yb:CaGdAlO4 laser with tunable wavelength

NASA Astrophysics Data System (ADS)

Gao, Ziye; Zhu, Jiangfeng; Wang, Junli; Wang, Zhaohua; Wei, Zhiyi; Xu, Xiaodong; Zheng, Lihe; Su, Liangbi; Xu, Jun

2016-01-01

We experimentally demonstrated a wavelength tunable Kerr-lens mode-locked femtosecond laser based on an Yb:CaGdAlO4 (Yb:CGA) crystal. The Kerr-lens mode-locked wavelength tuning range was from 1043.5 to 1076 nm, as broad as 32.5 nm, by slightly tilting the end mirror. Pulses as short as 60 fs were generated at the central wavelength of 1043.8 nm with an average output power of 66 mW. By using an output coupler with 1.5% transmittance, the Kerr-lens mode-locked average output power reached 127 mW with a pulse duration of 81 fs at a central wavelength of 1049.5 nm.

Solitary waves of surface plasmon polariton via phase shifts under Doppler broadening and Kerr nonlinearity

NASA Astrophysics Data System (ADS)

Ahmad, S.; Ahmad, A.; Bacha, B. A.; Khan, A. A.; Abdul Jabar, M. S.

2017-12-01

Surface Plasmon Polaritons (SPPs) are theoretically investigated at the interface of a dielectric metal and gold. The output pulse from the dielectric is used as the input pulse for the generation of SPPs. The SPPs show soliton-like behavior at the interface. The solitary form of a SPP is maintained under the effects of Kerr nonlinearity, Doppler broadening and Fresnel dragging whereas its phase shift is significantly modified. A 0.3radian phase shift is calculated in the presence of both Kerr nonlinearity and Fresnel dragging in the absence of plasma motion. The phase shift is enhanced to 60radian due to the combined effect of Doppler broadening, Kerr nonlinearity and Fresnel dragging. The results may have significant applications in nano-photonics, optical tweezers, photovoltaic devices, plasmonster and sensing technology.

Enhanced magneto-optical Kerr effect at Fe/insulator interfaces

NASA Astrophysics Data System (ADS)

Gu, Bo; Takahashi, Saburo; Maekawa, Sadamichi

2017-12-01

Using density functional theory calculations, we have found an enhanced magneto-optical Kerr effect in Fe/insulator interfaces. The results of our study indicate that interfacial Fe atoms in the Fe films have a low-dimensional nature, which causes the following two effects: (i) The diagonal component σx x of the optical conductivity decreases dramatically because the hopping integral for electrons between Fe atoms is suppressed by the low dimensionality. (ii) The off-diagonal component σx y of the optical conductivity does not change at low photon energies, but it is enhanced at photon energies around 2 eV, where we obtain enhanced orbital magnetic moments and spin-orbit correlations for the interfacial Fe atoms. A large Kerr angle develops in proportion to the ratio σx y/σx x . Our findings indicate an efficient way to enhance the effect of spin-orbit coupling at metal/insulator interfaces without using heavy elements.

Giant ultrafast Kerr effect in superconductors

NASA Astrophysics Data System (ADS)

Robson, Charles W.; Fraser, Kieran A.; Biancalana, Fabio

2017-06-01

We study the ultrafast Kerr effect and high-harmonic generation in superconductors by formulating a model for a time-varying electromagnetic pulse normally incident on a thin-film superconductor. It is found that superconductors exhibit exceptionally large χ(3 ) due to the progressive destruction of Cooper pairs, and display high-harmonic generation at low incident intensities, and the highest nonlinear susceptibility of all known materials in the THz regime. Our theory opens up avenues for accessible analytical and numerical studies of the ultrafast dynamics of superconductors.

Integrated Kerr comb-based reconfigurable transversal differentiator for microwave photonic signal processing

NASA Astrophysics Data System (ADS)

Xu, Xingyuan; Wu, Jiayang; Shoeiby, Mehrdad; Nguyen, Thach G.; Chu, Sai T.; Little, Brent E.; Morandotti, Roberto; Mitchell, Arnan; Moss, David J.

2018-01-01

An arbitrary-order intensity differentiator for high-order microwave signal differentiation is proposed and experimentally demonstrated on a versatile transversal microwave photonic signal processing platform based on integrated Kerr combs. With a CMOS-compatible nonlinear micro-ring resonator, high quality Kerr combs with broad bandwidth and large frequency spacings are generated, enabling a larger number of taps and an increased Nyquist zone. By programming and shaping individual comb lines' power, calculated tap weights are realized, thus achieving a versatile microwave photonic signal processing platform. Arbitrary-order intensity differentiation is demonstrated on the platform. The RF responses are experimentally characterized, and systems demonstrations for Gaussian input signals are also performed.

Magnification effect of Kerr metric by configurations of collisionless particles in non-isotropic kinetic equilibria

NASA Astrophysics Data System (ADS)

Cremaschini, Claudio; Stuchlík, Zdeněk

2018-05-01

A test fluid composed of relativistic collisionless neutral particles in the background of Kerr metric is expected to generate non-isotropic equilibrium configurations in which the corresponding stress-energy tensor exhibits pressure and temperature anisotropies. This arises as a consequence of the constraints placed on single-particle dynamics by Killing tensor symmetries, leading to a peculiar non-Maxwellian functional form of the kinetic distribution function describing the continuum system. Based on this outcome, in this paper the generation of Kerr-like metric by collisionless N -body systems of neutral matter orbiting in the field of a rotating black hole is reported. The result is obtained in the framework of covariant kinetic theory by solving the Einstein equations in terms of an analytical perturbative treatment whereby the gravitational field is decomposed as a prescribed background metric tensor described by the Kerr solution plus a self-field correction. The latter one is generated by the uncharged fluid at equilibrium and satisfies the linearized Einstein equations having the non-isotropic stress-energy tensor as source term. It is shown that the resulting self-metric is again of Kerr type, providing a mechanism of magnification of the background metric tensor and its qualitative features.

Kerr-Newman black holes with string corrections

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

Charles, Anthony M.; Larsen, Finn

We study N = 2 supergravity with higher-derivative corrections that preserve the N = 2 supersymmetry and show that Kerr-Newman black holes are solutions to these theories. Modifications of the black hole entropy due to the higher derivatives are universal and apply even in the BPS and Schwarzschild limits. Our solutions and their entropy are greatly simplified by supersymmetry of the theory even though the black holes generally do not preserve any of the supersymmetry.

Kerr-Newman black holes with string corrections

DOE PAGES

Charles, Anthony M.; Larsen, Finn

2016-10-26

We study N = 2 supergravity with higher-derivative corrections that preserve the N = 2 supersymmetry and show that Kerr-Newman black holes are solutions to these theories. Modifications of the black hole entropy due to the higher derivatives are universal and apply even in the BPS and Schwarzschild limits. Our solutions and their entropy are greatly simplified by supersymmetry of the theory even though the black holes generally do not preserve any of the supersymmetry.

Tori sequences as remnants of multiple accreting periods of Kerr SMBHs

NASA Astrophysics Data System (ADS)

Pugliese, D.; Stuchlík, Z.

2018-03-01

Super-massive black holes (SMBHs) hosted in active galactic nuclei (AGNs) can be characterized by multi-accreting periods as the attractors interact with the environment during their life-time. These multi-accretion episodes should leave traces in the matter orbiting the attractor. Counterrotating and even misaligned structures orbiting around the SMBHs would be consequences of these episodes. Our task in this work is to consider situations where such accretions occur and to trace their remnants represented by several toroidal accreting fluids, corotating or counterrotating relative to the central Kerr attractor, and created in various regimes during the evolution of matter configurations around SMBHs. We focus particularly on the emergence of matter instabilities, i.e., tori collisions, accretion onto the central Kerr black hole, or creation of jet-like structures (proto-jets). Each orbiting configuration is governed by the general relativistic hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluid. We prove that sequences of configurations and hot points, where an instability occurs, characterize the Kerr SMBHs, depending mainly on their spin-mass ratios. The occurrence of tori accretion or collision are strongly constrained by the fluid rotation with respect to the central black hole and the relative rotation with respect to each other. Our investigation provides characteristic of attractors where traces of multi-accreting episodes can be found and observed.

Cosmic censorship conjecture in Kerr-Sen black hole

NASA Astrophysics Data System (ADS)

Gwak, Bogeun

2017-06-01

The validity of the cosmic censorship conjecture for the Kerr-Sen black hole, which is a solution to the low-energy effective field theory for four-dimensional heterotic string theory, is investigated using charged particle absorption. When the black hole absorbs the particle, the charge on it changes owing to the conserved quantities of the particle. Changes in the black hole are constrained to the equation for the motion of the particle and are consistent with the laws of thermodynamics. Particle absorption increases the mass of the Kerr-Sen black hole to more than that of the absorbed charges such as angular momentum and electric charge; hence, the black hole cannot be overcharged. In the near-extremal black hole, we observe a violation of the cosmic censorship conjecture for the angular momentum in the first order of expansion and the electric charge in the second order. However, considering an adiabatic process carrying the conserved quantities as those of the black hole, we prove the stability of the black hole horizon. Thus, we resolve the violation. This is consistent with the third law of thermodynamics.

Multiplicity of transmission coefficients in photonic crystal and split ring resonator waveguides with Kerr nonlinear impurities

NASA Astrophysics Data System (ADS)

Rai, Buddhi; McGurn, Arthur R.

2015-02-01

Photonic crystal and split ring resonator (SRR) metamaterial waveguides with Kerr nonlinear dielectric impurities are studied. The transmission coefficients for two guided modes of different frequencies scattering from the Kerr impurities are computed. The systems are shown to exhibit multiple transmission coefficient solutions arising from the Kerr nonlinearity. Multiple transmission coefficients occur when different input intensities into a waveguide result in the same transmitted output intensities past its nonlinear impurities. (In the case of a single incident guided mode the multiplicity of transmission coefficients is known as optical bistability.) The analytical conditions under which the transmission coefficients are single and multiple valued are determined, and specific examples of both single and multiple valued transmission coefficient scattering are presented. Both photonic crystal and split ring resonator systems are studied as the Kerr nonlinearity enters the photonic crystal and SRR systems in different ways. This allows for an interesting comparison of the differences in behaviors of these two types of system which are described by distinctly different mathematical structures. Both the photonic crystal and SRR models used in the calculations are based on a difference equation approach to the system dynamics. The difference equation approach has been extensively employed in previous papers to model the basic properties of these systems. The paper is a continuation of work on the optical bistability of single guided modes interacting with Kerr impurities in photonic crystals originally considered by McGurn [Chaos 13, 754 (2003), 10.1063/1.1568691] and work on the resonant scattering from Kerr impurities in photonic crystal waveguides considered by McGurn [J. Phys.: Condens. Matter 16, S5243 (2004), 10.1088/0953-8984/16/44/021]. It generalizes this work making the extension to the more complex interaction of two guided modes at different frequencies

The Mixed Legacy of Clark Kerr: A Personal View

ERIC Educational Resources Information Center

Lustig, Jeff

2004-01-01

The death of famed educator Clark Kerr last December evoked tributes and testimonials everywhere from the "New York Times" to local faculty bulletins. Architect of California's famous Master Plan of 1960, skilled labor mediator, first president of the University of California system, bete noir of the early student movement, and chair of…

Principal Killing strings in higher-dimensional Kerr-NUT-(A)dS spacetimes

NASA Astrophysics Data System (ADS)

Boos, Jens; Frolov, Valeri P.

2018-04-01

We construct special solutions of the Nambu-Goto equations for stationary strings in a general Kerr-NUT-(A)dS spacetime in any number of dimensions. This construction is based on the existence of explicit and hidden symmetries generated by the principal tensor which exists for these metrics. The characteristic property of these string configurations, which we call "principal Killing strings," is that they are stretched out from "infinity" to the horizon of the Kerr-NUT-(A)dS black hole and remain regular at the latter. We also demonstrate that principal Killing strings extract angular momentum from higher-dimensional rotating black holes and interpret this as the action of an asymptotic torque.

Ultralow-threshold Kerr-lens mode-locked Ti:Al(2)O(3) laser.

PubMed

Kowalevicz, A M; Schibli, T R; Kärtner, F X; Fujimoto, J G

2002-11-15

An ultralow-threshold Kerr-lens mode-locked Ti:Al(2)O(3) laser achieved by use of an extended cavity design is demonstrated. Mode-locking thresholds as low as 156 mW are achieved. Pulses with durations as short as 14 fs and bandwidths of >100 nm with output powers of ~15 mW at 50-MHz repetition rates are generated by only 200 mW of pump power. Reducing the pump power requirements to a factor of 10x less than required by most conventional Kerr-lens mode-locked lasers permits inexpensive, low-power pump lasers to be used. This will facilitate the development of low-cost, high-performance femtosecond Ti:Al(2)O(3) laser technology.

Transfer matrix approach for the Kerr and Faraday rotation in layered nanostructures.

PubMed

Széchenyi, Gábor; Vigh, Máté; Kormányos, Andor; Cserti, József

2016-09-21

To study the optical rotation of the polarization of light incident on multilayer systems consisting of atomically thin conductors and dielectric multilayers we present a general method based on transfer matrices. The transfer matrix of the atomically thin conducting layer is obtained using the Maxwell equations. We derive expressions for the Kerr (Faraday) rotation angle and for the ellipticity of the reflected (transmitted) light as a function of the incident angle and polarization of the light. The method is demonstrated by calculating the Kerr (Faraday) angle for bilayer graphene in the quantum anomalous Hall state placed on the top of dielectric multilayers. The optical conductivity of the bilayer graphene is calculated in the framework of a four-band model.

Photon blockade in optomechanical systems with a position-modulated Kerr-type nonlinear coupling

NASA Astrophysics Data System (ADS)

Zhang, X. Y.; Zhou, Y. H.; Guo, Y. Q.; Yi, X. X.

2018-03-01

We explore the photon blockade in optomechanical systems with a position-modulated Kerr-type nonlinear coupling, i.e. H_int˜\\hat{a}\\dagger2\\hat{a}^2(\\hat{b}_1^\\dagger+\\hat{b}_1) . We find that the Kerr-type nonlinear coupling can enhance the photon blockade greatly. We evaluate the equal-time second-order correlation function of the cavity photons and find that the optimal photon blockade does not happen at the single photon resonance. By working within the few-photon subspace, we get an approximate analytical expression for the correlation function and the condition for the optimal photon blockade. We also find that the photon blockade effect is not always enhanced as the Kerr-type nonlinear coupling strength g 2 increases. At some values of g 2, the photon blockade is even weakened. For the system we considered here, the second-order correlation function can be smaller than 1 even in the unresolved sideband regime. By numerically simulating the master equation of the system, we also find that the thermal noise of the mechanical environment can enhance the photon blockade. We give out an explanation for this counter-intuitive phenomenon qualitatively.

On hidden symmetries of extremal Kerr-NUT-AdS-dS black holes

NASA Astrophysics Data System (ADS)

Rasmussen, Jørgen

2011-05-01

It is well known that the Kerr-NUT-AdS-dS black hole admits two linearly independent Killing vectors and possesses a hidden symmetry generated by a rank-2 Killing tensor. The near-horizon geometry of an extremal Kerr-NUT-AdS-dS black hole admits four linearly independent Killing vectors, and we show how the hidden symmetry of the black hole itself is carried over by means of a modified Killing-Yano potential which is given explicitly. We demonstrate that the corresponding Killing tensor of the near-horizon geometry is reducible as it can be expressed in terms of the Casimir operators formed by the four Killing vectors.

Rotating Black Holes and the Kerr Metric

NASA Astrophysics Data System (ADS)

Kerr, Roy Patrick

2008-10-01

Since it was first discovered in 1963 the Kerr metric has been used by relativists as a test-bed for conjectures on worm-holes, time travel, closed time-like loops, and the existence or otherwise of global Cauchy surfaces. More importantly, it has also used by astrophysicists to investigate the effects of collapsed objects on their local environments. These two groups of applications should not be confused. Astrophysical Black Holes are not the same as the Kruskal solution and its generalisations.

Investigation of giant Kerr nonlinearity in quantum cascade lasers using mid-infrared femtosecond pulses

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

Cai, Hong; Liu, Sheng; Department of Physics, University of Maryland, Baltimore County

2015-02-02

We study the Kerr nonlinearity of quantum cascade lasers (QCLs) by coupling resonant and off-resonant mid-infrared (mid-IR) femtosecond (fs) pulses into an active QCL waveguide. We observe an increase in the spectral width of the transmitted fs pulses as the coupled mid-infrared (mid-IR) pulse power increases. This is explained by the self-phase modulation effect due to the large Kerr nonlinearity of QCL waveguides. We further confirm this effect by observing the intensity dependent far-field profile of the transmitted mid-IR pulses, showing the pulses undergo self-focusing as they propagate through the active QCL due to the intensity dependent refractive index. Wemore » experimentally estimate the nonlinear refractive index n{sub 2} of a QCL to be ∼8 × 10{sup −9 }cm{sup 2}/W using the far-field beam profile of the transmitted pulses. The finite-difference time-domain simulations of QCL waveguides with Kerr nonlinearity incorporated show similar behavior to the experimental results.« less

Neutron tori around Kerr black holes

NASA Technical Reports Server (NTRS)

Witt, H. J.; Jaroszynski, M.; Haensel, P.; Paczynski, B.; Wambsganss, J.

1994-01-01

Models of stationary, axisymmetric, non-self-gravitating tori around stellar mass Kerr black holes are calculated. Such objects may form as a result of a merger between two neutron stars, a neutron star and a stellar mass black hole, or a 'failed supernova' collapse of a single rapidly rotating star. We explore a large range of parameters: the black hole mass and angular momentum, the torus mass, angular momentum and entropy. Physical conditions within the tori are similar to those in young and hot neutron stars, but their topology is different, and the range of masses and energies is much larger.

Optical activity via Kerr nonlinearity in a spinning chiral medium

NASA Astrophysics Data System (ADS)

Khan, Anwar Ali; Bacha, Bakht Amin; Khan, Rahmat Ali

2016-11-01

Optical activity is investigated in a chiral medium by employing the four level cascade atomic model, in which the optical responses of the atomic medium are studied with Kerr nonlinearity. Light entering into a chiral medium splits into circular birefringent beams. The angle of divergence between the circular birefringent beams and the polarization states of the two light beams is manipulated with Kerr nonlinearity. In the stationary chiral medium the angle of divergence between the circular birefringent beams is calculated to be 1.3 radian. Furthermore, circular birefringence is optically controlled in a spinning chiral medium, where the maximum rotary photon drag angle for left (right) circularly polarized beam is ±1.1 (±1.5) microradian. The change in the angle of divergence between circular birefringent beams by rotary photon drag is calculated to be 0.4 microradian. The numerical results may help to understand image designing, image coding, discovery of photonic crystals and optical sensing technology.

Kerr-de Sitter spacetime, Penrose process, and the generalized area theorem

NASA Astrophysics Data System (ADS)

Bhattacharya, Sourav

2018-04-01

We investigate various aspects of energy extraction via the Penrose process in the Kerr-de Sitter spacetime. We show that the increase in the value of a positive cosmological constant, Λ , always reduces the efficiency of this process. The Kerr-de Sitter spacetime has two ergospheres associated with the black hole and the cosmological event horizons. We prove by analyzing turning points of the trajectory that the Penrose process in the cosmological ergoregion is never possible. We next show that in this process both the black hole and cosmological event horizons' areas increase, and the latter becomes possible when the particle coming from the black hole ergoregion escapes through the cosmological event horizon. We identify a new, local mass function instead of the mass parameter, to prove this generalized area theorem. This mass function takes care of the local spacetime energy due to the cosmological constant as well, including that which arises due to the frame-dragging effect due to spacetime rotation. While the current observed value of Λ is quite small, its effect in this process could be considerable in the early Universe scenario where its value is much larger, where the two horizons could have comparable sizes. In particular, the various results we obtain here are also evaluated in a triply degenerate limit of the Kerr-de Sitter spacetime we find, in which radial values of the inner, the black hole and the cosmological event horizons are nearly coincident.

Effect of the Kerr Metric on Photosperic Radius Expansion in X Ray Burst

NASA Astrophysics Data System (ADS)

Kalita, S.; Barman, A.

2017-12-01

The main objective of this paper is to study general relativistic effects on the photospheric radius expansion during an X-ray burst. We examine how the Kerr metric causes a shift in the effective temperature and radiation flux with respect to the Schwarzschild values during mass accretion onto a neutron star or a black hole resulting in the X-ray burst. The spin of the compact object is used up to the maximal Kerr limit χ = 0.99 with different latitudes of accretion emission. The amplitude of temperature shift relative to the Schwarzschild case is found to be δ T/ T ≈ - (10-3 - 10-4) for the range χ = 0.1 - 0.99 at latitudes θ = 0o , 30o, 45o and 88o. The ratio of emission flux in the Kerr metric to that in the Schwarzschild metric, F(K)/F(S), is found to be less than unity. It goes up to a maximum of 0.9 for the lowest nonzero value of the spin parameter (i.e., 0.1). For the maximal Kerr limit, χ = 0.99 , it saturates near 0.8. This effect is more prominent towards the pole. This reduction in temperature and flux is found to be consistent with the absence of photospheric radius expansion in the X Ray burst LMXB 4U 1608-52, observed by NuSTAR. Although this is not uniquely ascribed to the metric, it is believed that the spacetime metric effect in the burst phenomena can be used as a probe for testing general relativity. Also, the shift in temperature or the radiation flux might have an observable signature in the element synthesis processes in such environments.

Magneto-optical Kerr spectroscopy of noble metals

NASA Astrophysics Data System (ADS)

Uba, L.; Uba, S.; Antonov, V. N.

2017-12-01

Magneto-optical (MO) response of the noble metals Cu, Ag, and Au in the joint experimental and ab initio theoretical study is reported. The magneto-optical polar Kerr effect (MOKE) spectra of the noble-metal films were measured with the high sensitivity in the applied magnetic field of 1.5 T over the photon energy range 0.74-5.8 eV. Complete set of the optical conductivity tensor elements was determined precisely from the MOKE and the optical spectra measured at the same energy points. The importance of the off-diagonal intraband Drude-type transitions is demonstrated explicitly for each noble metal and found to be a substantial contribution to the observed spectra. It is shown that the first-principles calculations using the spin-polarized fully relativistic Dirac linear-muffin-tin-orbital method with the inclusion of correlation effects by GGA+U approach reproduce well the experimental spectra and allow to explain the microscopic origin of the noble metals' magneto-optical response in terms of interband transitions. Although the energy band structures of Cu, Ag, and Au are very similar, there are some distinctive differences in bandwidths and the energy positions of the bands (especially in X and L symmetry points), mainly due to different spin-orbit splitting and differences in the spatial extent of 3 d , 4 d , and 5 d valence wave functions of noble metals. It was found that the small differences in the band positions lead to significant differences in the MO properties of three noble metals. Although the spin-orbit interaction in Au is about six times larger than in Cu, and approximately two times larger than in Ag, the absolute value of Kerr rotation in Au is of the same magnitude as in Cu and one order of magnitude smaller as compared to Ag. The sharp Kerr effect spectral peak in Ag is not due to the electronic interband transitions, but rather to the plasma-edge splitting. The band-by-band decomposition of the Cu, Ag, and Au MO spectra is presented and the

Sensing Environmental Education Research

ERIC Educational Resources Information Center

Reid, Alan

2003-01-01

The field of environmental education research has been moving away from scientistic and positivistic discourses for some time now ("Environmental Education Research," 2000; Hart & Nolan, 1999). However, it has been noted that the meta-discourse about this research continues to draw on their framings, registers, and lexicons (Hart, 2000;…

Perturbations of the Kerr black hole and the boundness of linear waves

NASA Astrophysics Data System (ADS)

Eskin, G.

2010-11-01

Artificial black holes (also called acoustic or optical black holes) are the black holes for the linear wave equation describing the wave propagation in a moving medium. They attracted a considerable interest of physicists who study them to better understand the black holes in general relativity. We consider the case of stationary axisymmetric metrics and we show that the Kerr black hole is not stable under perturbations in the class of all axisymmetric metrics. We describe families of axisymmetric metrics having black holes that are the perturbations of the Kerr black hole. We also show that the ergosphere can be determined by boundary measurements. Finally, we prove the uniform boundness of the solution in the exterior of the black hole when the event horizon coincides with the ergosphere.

Shadow casted by a Konoplya-Zhidenko rotating non-Kerr black hole

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

Wang, Mingzhi; Chen, Songbai; Jing, Jiliang, E-mail: wmz9085@126.com, E-mail: csb3752@hunnu.edu.cn, E-mail: jljing@hunnu.edu.cn

We have investigated the shadow of a Konoplya-Zhidenko rotating non-Kerr black hole with an extra deformation parameter. The spacetime structure arising from the deformed parameter affects sharply the black hole shadow. With the increase of the deformation parameter, the size of the shadow of black hole increase and its shape becomes more rounded for arbitrary rotation parameter. The D-shape shadow of black hole emerges only in the case a <2√3/3\\, M with the proper deformation parameter. Especially, the black hole shadow possesses a cusp shape with small eye lashes in the cases with a >M, and the shadow becomes lessmore » cuspidal with the increase of the deformation parameter. Our result show that the presence of the deformation parameter yields a series of significant patterns for the shadow casted by a Konoplya-Zhidenko rotating non-Kerr black hole.« less

ODYSSEY: A PUBLIC GPU-BASED CODE FOR GENERAL RELATIVISTIC RADIATIVE TRANSFER IN KERR SPACETIME

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

Pu, Hung-Yi; Yun, Kiyun; Yoon, Suk-Jin

General relativistic radiative transfer calculations coupled with the calculation of geodesics in the Kerr spacetime are an essential tool for determining the images, spectra, and light curves from matter in the vicinity of black holes. Such studies are especially important for ongoing and upcoming millimeter/submillimeter very long baseline interferometry observations of the supermassive black holes at the centers of Sgr A* and M87. To this end we introduce Odyssey, a graphics processing unit (GPU) based code for ray tracing and radiative transfer in the Kerr spacetime. On a single GPU, the performance of Odyssey can exceed 1 ns per photon, per Runge–Kutta integrationmore » step. Odyssey is publicly available, fast, accurate, and flexible enough to be modified to suit the specific needs of new users. Along with a Graphical User Interface powered by a video-accelerated display architecture, we also present an educational software tool, Odyssey-Edu, for showing in real time how null geodesics around a Kerr black hole vary as a function of black hole spin and angle of incidence onto the black hole.« less

Polar Kerr effect studies of time reversal symmetry breaking states in heavy fermion superconductors

DOE PAGES

Schemm, E. R.; Levenson-Falk, E. M.; Kapitulnik, A.

2016-11-30

The connection between chiral superconductivity and topological order has emerged as an active direction in research as more instances of both have been identified in condensed matter systems. Moreover, with the notable exception of 3He-B, all of the known or suspected chiral – that is to say time-reversal symmetry-breaking (TRSB) – superfluids arise in heavy fermion superconductors, although the vast majority of heavy fermion superconductors preserve time-reversal symmetry. We review recent experimental efforts to identify TRSB states in heavy fermion systems via measurement of polar Kerr effect, which is a direct consequence of TRSB.

Polar Kerr Effect from Time-Reversal Symmetry Breaking in the Heavy-Fermion Superconductor PrOs 4 Sb 12

DOE PAGES

Levenson-Falk, Eli M.; Schemm, E. R.; Aoki, Y.; ...

2018-05-04

Here, we present polar Kerr effect measurements of the filled skutterudite superconductor PrOs 4Sb 12. Simultaneous ac susceptibility measurements allow us to observe the superconducting transition under the influence of heating from the optical beam. A nonzero Kerr angle θ K develops below the superconducting transition, saturating at ~300 nrad at low temperatures. This result is repeated across several measurements of multiple samples. By extrapolating the measured θ K(T) to zero optical power, we are able to show that the Kerr angle onset temperature in one set of measurements is consistent with the transition to the B phase at Tmore » C2. We discuss the possible explanations for this result and its impact on the understanding of multiphase and inhomogeneous superconductivity in PrOs 4Sb 12.« less

Polar Kerr Effect from Time-Reversal Symmetry Breaking in the Heavy-Fermion Superconductor PrOs 4 Sb 12

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

Levenson-Falk, Eli M.; Schemm, E. R.; Aoki, Y.

Here, we present polar Kerr effect measurements of the filled skutterudite superconductor PrOs 4Sb 12. Simultaneous ac susceptibility measurements allow us to observe the superconducting transition under the influence of heating from the optical beam. A nonzero Kerr angle θ K develops below the superconducting transition, saturating at ~300 nrad at low temperatures. This result is repeated across several measurements of multiple samples. By extrapolating the measured θ K(T) to zero optical power, we are able to show that the Kerr angle onset temperature in one set of measurements is consistent with the transition to the B phase at Tmore » C2. We discuss the possible explanations for this result and its impact on the understanding of multiphase and inhomogeneous superconductivity in PrOs 4Sb 12.« less

Polar Kerr Effect from Time-Reversal Symmetry Breaking in the Heavy-Fermion Superconductor PrOs4Sb12

NASA Astrophysics Data System (ADS)

Levenson-Falk, E. M.; Schemm, E. R.; Aoki, Y.; Maple, M. B.; Kapitulnik, A.

2018-05-01

We present polar Kerr effect measurements of the filled skutterudite superconductor PrOs4 Sb12 . Simultaneous ac susceptibility measurements allow us to observe the superconducting transition under the influence of heating from the optical beam. A nonzero Kerr angle θK develops below the superconducting transition, saturating at ˜300 nrad at low temperatures. This result is repeated across several measurements of multiple samples. By extrapolating the measured θK(T ) to zero optical power, we are able to show that the Kerr angle onset temperature in one set of measurements is consistent with the transition to the B phase at TC 2. We discuss the possible explanations for this result and its impact on the understanding of multiphase and inhomogeneous superconductivity in PrOs4 Sb12 .

Terahertz spectroscopy on Faraday and Kerr rotations in a quantum anomalous Hall state.

PubMed

Okada, Ken N; Takahashi, Youtarou; Mogi, Masataka; Yoshimi, Ryutaro; Tsukazaki, Atsushi; Takahashi, Kei S; Ogawa, Naoki; Kawasaki, Masashi; Tokura, Yoshinori

2016-07-20

Electrodynamic responses from three-dimensional topological insulators are characterized by the universal magnetoelectric term constituent of the Lagrangian formalism. The quantized magnetoelectric coupling, which is generally referred to as topological magnetoelectric effect, has been predicted to induce exotic phenomena including the universal low-energy magneto-optical effects. Here we report the experimental indication of the topological magnetoelectric effect, which is exemplified by magneto-optical Faraday and Kerr rotations in the quantum anomalous Hall states of magnetic topological insulator surfaces by terahertz magneto-optics. The universal relation composed of the observed Faraday and Kerr rotation angles but not of any material parameters (for example, dielectric constant and magnetic susceptibility) well exhibits the trajectory towards the fine structure constant in the quantized limit.

Terahertz spectroscopy on Faraday and Kerr rotations in a quantum anomalous Hall state

PubMed Central

Okada, Ken N.; Takahashi, Youtarou; Mogi, Masataka; Yoshimi, Ryutaro; Tsukazaki, Atsushi; Takahashi, Kei S.; Ogawa, Naoki; Kawasaki, Masashi; Tokura, Yoshinori

2016-01-01

Electrodynamic responses from three-dimensional topological insulators are characterized by the universal magnetoelectric term constituent of the Lagrangian formalism. The quantized magnetoelectric coupling, which is generally referred to as topological magnetoelectric effect, has been predicted to induce exotic phenomena including the universal low-energy magneto-optical effects. Here we report the experimental indication of the topological magnetoelectric effect, which is exemplified by magneto-optical Faraday and Kerr rotations in the quantum anomalous Hall states of magnetic topological insulator surfaces by terahertz magneto-optics. The universal relation composed of the observed Faraday and Kerr rotation angles but not of any material parameters (for example, dielectric constant and magnetic susceptibility) well exhibits the trajectory towards the fine structure constant in the quantized limit. PMID:27436710

Spectroscopy of Kerr Black Holes with Earth- and Space-Based Interferometers.

PubMed

Berti, Emanuele; Sesana, Alberto; Barausse, Enrico; Cardoso, Vitor; Belczynski, Krzysztof

2016-09-02

We estimate the potential of present and future interferometric gravitational-wave detectors to test the Kerr nature of black holes through "gravitational spectroscopy," i.e., the measurement of multiple quasinormal mode frequencies from the remnant of a black hole merger. Using population synthesis models of the formation and evolution of stellar-mass black hole binaries, we find that Voyager-class interferometers will be necessary to perform these tests. Gravitational spectroscopy in the local Universe may become routine with the Einstein Telescope, but a 40-km facility like Cosmic Explorer is necessary to go beyond z∼3. In contrast, detectors like eLISA (evolved Laser Interferometer Space Antenna) should carry out a few-or even hundreds-of these tests every year, depending on uncertainties in massive black hole formation models. Many space-based spectroscopical measurements will occur at high redshift, testing the strong gravity dynamics of Kerr black holes in domains where cosmological corrections to general relativity (if they occur in nature) must be significant.

Direct diode-pumped Kerr Lens 13 fs Ti:sapphire ultrafast oscillator using a single blue laser diode

DOE PAGES

Backus, Sterling; Colorado State Univ., Fort Collins, CO; Kirchner, Matt; ...

2017-05-18

We demonstrate a direct diode-pumped Kerr Lens Modelocked Ti:sapphire laser producing 13 fs pulses with 1.85 nJ energy at 78 MHz (145 mW) using a single laser diode pump. We also present a similar laser using three spectrally combined diodes, generating >300 mW output power with >50 nm bandwidth. We discuss the use of far-from TEM 00 pump laser sources, and their effect on the Kerr lens modelocking process.

Direct diode-pumped Kerr Lens 13 fs Ti:sapphire ultrafast oscillator using a single blue laser diode

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

Backus, Sterling; Colorado State Univ., Fort Collins, CO; Kirchner, Matt

We demonstrate a direct diode-pumped Kerr Lens Modelocked Ti:sapphire laser producing 13 fs pulses with 1.85 nJ energy at 78 MHz (145 mW) using a single laser diode pump. We also present a similar laser using three spectrally combined diodes, generating >300 mW output power with >50 nm bandwidth. We discuss the use of far-from TEM 00 pump laser sources, and their effect on the Kerr lens modelocking process.

Enhancement of the transverse magneto-optical Kerr effect via resonant tunneling in trilayers containing magneto-optical metals

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

Girón-Sedas, J. A.; Centro de Investigación e Innovación en Bioinformática y Fotónica - CIBioFI, AA 25360 Cali; Mejía-Salazar, J. R., E-mail: jrmejia3146@gmail.com

We propose a way to enhance the transverse magneto-optical Kerr effect, by the excitation of resonant tunneling modes, in subwavelength trilayer structures featuring a dielectric slab sandwiched between two magneto-optical metallic layers. Depending on the magneto-optical layer widths, the proposed system may exhibit an extraordinary transverse magneto-optical Kerr effect, which makes it very attractive for the design and engineering of thin-film magneto-optical-based devices for future photonic circuits or fiber optical-communication systems.

Optical Kerr spatiotemporal dark extreme waves

NASA Astrophysics Data System (ADS)

Wabnitz, Stefan; Kodama, Yuji; Baronio, Fabio

2018-02-01

We study the existence and propagation of multidimensional dark non-diffractive and non-dispersive spatiotemporal optical wave-packets in nonlinear Kerr media. We report analytically and confirm numerically the properties of spatiotemporal dark lines, X solitary waves and lump solutions of the (2 + 1)D nonlinear Schr odinger equation (NLSE). Dark lines, X waves and lumps represent holes of light on a continuous wave background. These solitary waves are derived by exploiting the connection between the (2 + 1)D NLSE and a well-known equation of hydrodynamics, namely the (2+1)D Kadomtsev-Petviashvili (KP) equation. This finding opens a novel path for the excitation and control of spatiotemporal optical solitary and rogue waves, of hydrodynamic nature.

Self-force via m-mode regularization and 2+1D evolution. II. Scalar-field implementation on Kerr spacetime

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

Dolan, Sam R.; Barack, Leor; Wardell, Barry

2011-10-15

This is the second in a series of papers aimed at developing a practical time-domain method for self-force calculations in Kerr spacetime. The key elements of the method are (i) removal of a singular part of the perturbation field with a suitable analytic 'puncture' based on the Detweiler-Whiting decomposition, (ii) decomposition of the perturbation equations in azimuthal (m-)modes, taking advantage of the axial symmetry of the Kerr background, (iii) numerical evolution of the individual m-modes in 2+1 dimensions with a finite-difference scheme, and (iv) reconstruction of the physical self-force from the mode sum. Here we report an implementation of themore » method to compute the scalar-field self-force along circular equatorial geodesic orbits around a Kerr black hole. This constitutes a first time-domain computation of the self-force in Kerr geometry. Our time-domain code reproduces the results of a recent frequency-domain calculation by Warburton and Barack, but has the added advantage of being readily adaptable to include the backreaction from the self-force in a self-consistent manner. In a forthcoming paper--the third in the series--we apply our method to the gravitational self-force (in the Lorenz gauge).« less

Feasibility Study of Economics and Performance of Solar Photovoltaics at the Kerr McGee Site in Columbus, Mississippi. A Study Prepared in Partnership with the Environmental Protection Agency for the RE-Powering America's Land Initiative: Siting Renewable Energy on Potentially Contaminated Land and Mine Sites

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

Simon, J.; Mosey, G.

2013-01-01

The U.S. Environmental Protection Agency (EPA), in accordance with the RE-Powering America's Land initiative, selected the Kerr McGee site in Columbus, Mississippi, for a feasibility study of renewable energy production. The National Renewable Energy Laboratory (NREL) provided technical assistance for this project. The purpose of this report is to assess the site for a possible photovoltaic (PV) system installation and estimate the cost, performance, and site impacts of different PV options. In addition, the report recommends financing options that could assist in the implementation of a PV system at the site.

Nonlinear Kerr enhancement of the Sagnac effect in a coherently coupled array of optical microresonators

NASA Astrophysics Data System (ADS)

Wang, Chao; Search, Christopher

2013-03-01

Optical gyroscopes based on the Sagnac effect are of great interest both theoretically and practically. Previously it has been suggested a nonlinear Kerr medium inserted into a ring resonator gyroscope can largely increase the rotation sensitivity due to an instability caused by the non-reciprocal self-phase and cross-phase modulations. Recently, coupled microresonator arrays such as Side-Coupled Integrated Spaced Sequence of Resonators (SCISSOR) and Coupled Resonator Optical Waveguides (CROW) have drawn interest as potential integrated gyroscopes due to the sensitivity enhancement resulting from distributed interference between resonators. Here we analyze a SCISSOR system, which consists of an array of microresonators evanescently coupled to two parallel bus waveguides in the presence of a strong intra-resonator Kerr nonlinearity. We show that the distributed interference in the waveguides combined with the nonlinearly enhanced Sagnac effect in the resonators can further improve the sensitivity compared with either a single resonator of equal footprint or SCISSOR without a Kerr nonlinearity. Numerical simulation shows that bistability in the SCISSOR occurs and the rotation sensitivity dIoutput/dω can go to infinity near the boundaries of the bistable region.

A study for testing the Kerr metric with AGN iron line eclipses

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

Cárdenas-Avendaño, Alejandro; Jiang, Jiachen; Bambi, Cosimo, E-mail: alejandro.cardenasa@konradlorenz.edu.co, E-mail: jcjiang12@fudan.edu.cn, E-mail: bambi@fudan.edu.cn

2016-04-01

Recently, two of us have studied iron line reverberation mapping to test black hole candidates, showing that the time information in reverberation mapping can better constrain the Kerr metric than the time-integrated approach. Motivated by this finding, here we explore the constraining power of another time-dependent measurement: an AGN iron line eclipse. An obscuring cloud passes between the AGN and the distant observer, covering different parts of the accretion disk at different times. Similar to the reverberation measurement, an eclipse might help to better identify the relativistic effects affecting the X-ray photons. However, this is not what we find. Inmore » our study, we employ the Johannsen-Psaltis parametrisation, but we argue that our conclusions hold in a large class of non-Kerr metrics. We explain our results pointing out an important difference between reverberation and eclipse measurements.« less

Domain walls of linear polarization in isotropic Kerr media

NASA Astrophysics Data System (ADS)

Louis, Y.; Sheppard, A. P.; Haelterman, M.

1997-09-01

We present a new type of domain-wall vector solitary waves in isotropic self-defocusing Kerr media. These domain walls consist of localized structures separating uniform field domains of orthogonal linear polarizations. They result from the interplay between diffraction, self-phase modulation and cross-phase modulation in cases where the nonlinear birefringence coefficient B = {χxyyx(3)}/{χxxxx(3)} is negative. Numerical simulations show that these new vector solitary waves are stable.

Community Involvement Plan for Northeast Church Rock and Kerr-McGee Quivira Mine Sites

EPA Pesticide Factsheets

This Community Involvement Plan outlines opportunities for individual participation and meaningful information sharing regarding EPA’s activities in communities near Northeast Churchrock and Kerr-McGee Quivira Mine Sites.

Regional economic impact study for the McClellan Kerr Arkansas River Navigation System.

DOT National Transportation Integrated Search

2015-10-01

The McClellan-Kerr Arkansas River Navigation System (MKARNS), located in Oklahoma and : Arkansas, contains 440 miles of waterway and is a crucial part of the United States : transportation system. The MKARNS strategically connects the heartland of...

The spinning Kerr-black-hole-mirror bomb: A lower bound on the radius of the reflecting mirror

NASA Astrophysics Data System (ADS)

Hod, Shahar

2016-10-01

The intriguing superradiant amplification phenomenon allows an orbiting scalar field to extract rotational energy from a spinning Kerr black hole. Interestingly, the energy extraction rate can grow exponentially in time if the black-hole-field system is placed inside a reflecting mirror which prevents the field from radiating its energy to infinity. This composed Kerr-black-hole-scalar-field-mirror system, first designed by Press and Teukolsky, has attracted the attention of physicists over the last four decades. Previous numerical studies of this spinning black-hole bomb have revealed the interesting fact that the superradiant instability shuts down if the reflecting mirror is placed too close to the black-hole horizon. In the present study we use analytical techniques to explore the superradiant instability regime of this composed Kerr-black-hole-linearized-scalar-field-mirror system. In particular, it is proved that the lower bound rm/r+ >1/2 (√{ 1 +8M/r- } - 1) provides a necessary condition for the development of the exponentially growing superradiant instabilities in this composed physical system, where rm is the radius of the confining mirror and r± are the horizon radii of the spinning Kerr black hole. We further show that, in the linearized regime, this analytically derived lower bound on the radius of the confining mirror agrees with direct numerical computations of the superradiant instability spectrum which characterizes the spinning black-hole-mirror bomb.

Life as the Middle Child: A Conversation With Mary Margaret Kerr

ERIC Educational Resources Information Center

Teagarden, James M.; Zabel, Robert H.; Kaff, Marilyn S.

2015-01-01

As part of an ongoing oral history project, a conversation was held with Dr. Mary Margaret Kerr on the past, present, and possible future of the field of providing services to children with emotional-behavioral disorders. Dr. Wood stresses the increasing importance of providing an interdisciplinary approach to meet the needs for children or, as…

Environmental Economics Research Strategy (2005)

EPA Pesticide Factsheets

This 2005 Environmental Economics Research Strategy outlines EPA’s research effort to provide the necessary behavioral science foundation for making decisions and designing environmental policies at the least cost to American businesses and consumers.

Spectroscopy of Kerr black holes with Earth- and space-based interferometers

NASA Astrophysics Data System (ADS)

Berti, Emanuele; Sesana, Alberto; Barausse, Enrico; Cardoso, Vitor; Belczynski, Krzysztof

2017-01-01

We estimate the potential of present and future interferometric gravitational-wave detectors to test the Kerr nature of black holes through ``gravitational spectroscopy,'' i.e. the measurement of multiple quasinormal mode frequencies from the remnant of a black hole merger. Using population synthesis models of the formation and evolution of stellar-mass black hole binaries, we find that Voyager-class interferometers will be necessary to perform these tests. Gravitational spectroscopy in the local Universe may become routine with the Einstein Telescope, but a 40-km facility like Cosmic Explorer is necessary to go beyond z 3 . In contrast, eLISA-like detectors should carry out a few - or even hundreds - of these tests every year, depending on uncertainties in massive black hole formation models. Many space-based spectroscopical measurements will occur at high redshift, testing the strong gravity dynamics of Kerr black holes in domains where cosmological corrections to general relativity (if they occur in nature) must be significant. NSF CAREER Grant No. PHY-1055103, NSF Grant No. PHY-1607130, FCT contract IF/00797/2014/CP1214/CT0012.

Optical Kerr effect in graphene: Theoretical analysis of the optical heterodyne detection technique

NASA Astrophysics Data System (ADS)

Savostianova, N. A.; Mikhailov, S. A.

2018-04-01

Graphene is an atomically thin two-dimensional material demonstrating strong optical nonlinearities, including harmonics generation, four-wave mixing, Kerr, and other nonlinear effects. In this paper we theoretically analyze the optical heterodyne detection (OHD) technique of measuring the optical Kerr effect (OKE) in two-dimensional crystals and show how to relate the quantities measured in such experiments with components of the third-order conductivity tensor σαβ γ δ (3 )(ω1,ω2,ω3) of the two-dimensional crystal. Using results of a recently developed quantum theory of the third-order nonlinear electrodynamic response of graphene, we analyze the frequency, charge carrier density, temperature, and other dependencies of the OHD-OKE response of this material. We compare our results with a recent OHD-OKE experiment in graphene and find good agreement between the theory and experiment.

The effect of damping on a quantum system containing a Kerr-like medium

NASA Astrophysics Data System (ADS)

Mohamed, A.-B. A.; Sebawe Abdalla, M.; Obada, A.-S. F.

2018-05-01

An analytical description is given for a model which represents the interaction between Su(1,1) and Su(2) quantum systems taking into account Su(1,1)-cavity damping and Kerr medium properties. The analytic solution for the master equation of the density matrix is obtained. The examination of the effects of the damping parameter as well as the Kerr-like medium features is performed. The atomic inversion is discussed where the revivals and collapses phenomenon is realized at the considered period of time. Our study is extended to include the degree of entanglement where the system shows partial entanglement in all cases, however, disentanglement is also observed. The death and rebirth is seen in the system provided one selects the suitable values of the parameters. The correlation function of the system shows non-classical as well as classical behavior.

Weakly charged generalized Kerr-NUT-(A)dS spacetimes

NASA Astrophysics Data System (ADS)

Frolov, Valeri P.; Krtouš, Pavel; Kubizňák, David

2017-08-01

We find an explicit solution of the source free Maxwell equations in a generalized Kerr-NUT-(A)dS spacetime in all dimensions. This solution is obtained as a linear combination of the closed conformal Killing-Yano tensor hab, which is present in such a spacetime, and a derivative of the primary Killing vector, associated with hab. For the vanishing cosmological constant the obtained solution reduces to the Wald's electromagnetic field generated from the primary Killing vector.

Kerr microscopy study of exchange-coupled FePt/Fe exchange spring magnets

NASA Astrophysics Data System (ADS)

Hussain, Zaineb; Kumar, Dileep; Reddy, V. Raghavendra; Gupta, Ajay

2017-05-01

Magnetization reversal and magnetic microstructure of top soft magnetic layer (Fe) in exchange spring coupled L10 FePt/Fe is studied using high resolution Kerr microscopy. With remnant state of the hard magnetic layer (L10 FePt) as initial condition, magnetization loops along with magnetic domains are recorded for the top soft magnetic layer (Fe) using Kerr microscopy. Considerable shifting of Fe layer hysteresis loop from center which is similar to exchange bias phenomena is observed. It is also observed that one can tune the magnitude of hysteresis shift by reaching the remanent state from different saturating fields (HSAT) and also by varying the angle between measuring field and HSAT. The hysteresis loops and magnetic domains of top soft Fe layer demonstrate unambiguously that soft magnetic layer at remanent state in such exchange coupled system is having unidirectional anisotropy. An analogy is drawn and the observations are explained in terms of established model of exchange bias phenomena framed for field-cooled ferromagnetic - antiferromagnetic bilayer systems.

Kerr nonlinearity and nonlinear absorption coefficient in a four-level M-model cylindrical quantum dot under the phenomenon of electromagnetically induced transparency

NASA Astrophysics Data System (ADS)

Behroozian, B.; Askari, H. R.

2018-07-01

The Kerr nonlinearity and the nonlinear absorption coefficient in a four-level M-model of a GaAs cylindrical quantum dot (QD) with parabolic potential under electromagnetically induced transparency are investigated. By solving the density matrix equations in the steady-state, the third order susceptibility is obtained. Then, by using the real and imaginary parts of third order susceptibility, the Kerr nonlinearity and the nonlinear absorption coefficient, respectively, for this system are computed. The effects of the radius and height of the cylindrical QD are then investigated. In addition, the effects of the control laser fields on the Kerr nonlinearity and the nonlinear absorption coefficient are investigated.

Determination of circulation and turbidity patterns in Kerr Lake from LANDSAT MSS imagery. [Kerr Lake, Virginia, North Carolina

NASA Technical Reports Server (NTRS)

Lecroy, S. R. (Principal Investigator)

1981-01-01

The LANDSAT imagery was historically analyzed to determine the circulation and turbidity patterns of Kerr Lake, located on the Virginia-North Carolina border. By examining the seasonal and regional turbidity and circulation patterns, a record of sediment transport and possible disposition can be obtained. Sketches were generated, displaying different intensities of brightness observed in bands 5 and 7 of LANDSAT's multispectral scanner data. Differences in and between bands 5 and 7 indicate variances in the levels of surface sediment concentrations. High sediment loads are revealed when distinct patterns appear in the band 7 imagery. The upwelled signal is exponential in nature and saturates in band 5 at low wavelengths for large concentrations of suspended solids.

Dissipative entanglement swapping in the presence of detuning and Kerr medium: Bell state measurement method

NASA Astrophysics Data System (ADS)

Ghasemi, M.; Tavassoly, M. K.; Nourmandipour, A.

2017-12-01

In this paper, we investigate the possibility of entanglement swapping between two independent nonperfect cavities consisting of an atom with finite lifetime of atomic levels (as two independent sources of dissipation), which interacts with a quantized electromagnetic field in the presence of detuning and Kerr medium. In fact, there is no direct interaction between the two atoms, therefore, no entanglement exists between them. We use the Bell state measurement performed on the photons leaving the cavities to swap the entanglement stored between the atom-fields in each cavity into atom-atom. Our motivation comes from the fact that two-qubit entangled states are of great interest for quantum information science and technologies. We discuss the effect of the initial state of the system, the detuning parameter, the Kerr medium and the two dissipation sources on the swapped entanglement to atom-atom. We interestingly find that when the atomic decay rates and photonic leakages from the cavities are equal, our system behaves as an ideal system with no dissipation. Our results show that it is possible to create a long-living atom-atom maximally entangled state in the presence of Kerr effect and dissipation; we determine these conditions in detail and also establish the final atom-atom Bell state.

Gravitoelectromagnetic perturbations of Kerr-Newman black holes: stability and isospectrality in the slow-rotation limit.

PubMed

Pani, Paolo; Berti, Emanuele; Gualtieri, Leonardo

2013-06-14

The most general stationary black-hole solution of Einstein-Maxwell theory in vacuum is the Kerr-Newman metric, specified by three parameters: mass M, spin J, and charge Q. Within classical general relativity, one of the most important and challenging open problems in black-hole perturbation theory is the study of gravitational and electromagnetic fields in the Kerr-Newman geometry, because of the indissoluble coupling of the perturbation functions. Here we circumvent this long-standing problem by working in the slow-rotation limit. We compute the quasinormal modes up to linear order in J for any value of Q and provide the first, fully consistent stability analysis of the Kerr-Newman metric. For scalar perturbations the quasinormal modes can be computed exactly, and we demonstrate that the method is accurate within 3% for spins J/J(max) ≲ 0.5, where J(max) is the maximum allowed spin for any value of Q. Quite remarkably, we find numerical evidence that the axial and polar sectors of the gravitoelectromagnetic perturbations are isospectral to linear order in the spin. The extension of our results to nonasymptotically flat space-times could be useful in the context of gauge-gravity dualities and string theory.

Nonlinear evolution equations for surface plasmons for nano-focusing at a Kerr/metallic interface and tapered waveguide

NASA Astrophysics Data System (ADS)

Crutcher, Sihon H.; Osei, Albert; Biswas, Anjan

2012-06-01

Maxwell's equations for a metallic and nonlinear Kerr interface waveguide at the nanoscale can be approximated to a (1+1) D Nonlinear Schrodinger type model equation (NLSE) with appropriate assumptions and approximations. Theoretically, without losses or perturbations spatial plasmon solitons profiles are easily produced. However, with losses, the amplitude or beam profile is no longer stationary and adiabatic parameters have to be considered to understand propagation. For this model, adiabatic parameters are calculated considering losses resulting in linear differential coupled integral equations with constant definite integral coefficients not dependent on the transverse and longitudinal coordinates. Furthermore, by considering another configuration, a waveguide that is an M-NL-M (metal-nonlinear Kerr-metal) that tapers, the tapering can balance the loss experienced at a non-tapered metal/nonlinear Kerr interface causing attenuation of the beam profile, so these spatial plasmon solitons can be produced. In this paper taking into consideration the (1+1)D NLSE model for a tapered waveguide, we derive a one soliton solution based on He's Semi-Inverse Variational Principle (HPV).

Si-rich SiNx based Kerr switch enables optical data conversion up to 12 Gbit/s

PubMed Central

Lin, Gong-Ru; Su, Sheng-Pin; Wu, Chung-Lun; Lin, Yung-Hsiang; Huang, Bo-Ji; Wang, Huai-Yung; Tsai, Cheng-Ting; Wu, Chih-I; Chi, Yu-Chieh

2015-01-01

Silicon photonic interconnection on chip is the emerging issue for next-generation integrated circuits. With the Si-rich SiNx micro-ring based optical Kerr switch, we demonstrate for the first time the wavelength and format conversion of optical on-off-keying data with a bit-rate of 12 Gbit/s. The field-resonant nonlinear Kerr effect enhances the transient refractive index change when coupling the optical data-stream into the micro-ring through the bus waveguide. This effectively red-shifts the notched dip wavelength to cause the format preserved or inversed conversion of data carried by the on-resonant or off-resonant probe, respectively. The Si quantum dots doped Si-rich SiNx strengthens its nonlinear Kerr coefficient by two-orders of magnitude higher than that of bulk Si or Si3N4. The wavelength-converted and cross-amplitude-modulated probe data-stream at up to 12-Gbit/s through the Si-rich SiNx micro-ring with penalty of −7 dB on transmission has shown very promising applicability to all-optical communication networks. PMID:25923653

Si-rich SiNx based Kerr switch enables optical data conversion up to 12 Gbit/s.

PubMed

Lin, Gong-Ru; Su, Sheng-Pin; Wu, Chung-Lun; Lin, Yung-Hsiang; Huang, Bo-Ji; Wang, Huai-Yung; Tsai, Cheng-Ting; Wu, Chih-I; Chi, Yu-Chieh

2015-04-29

Silicon photonic interconnection on chip is the emerging issue for next-generation integrated circuits. With the Si-rich SiNx micro-ring based optical Kerr switch, we demonstrate for the first time the wavelength and format conversion of optical on-off-keying data with a bit-rate of 12 Gbit/s. The field-resonant nonlinear Kerr effect enhances the transient refractive index change when coupling the optical data-stream into the micro-ring through the bus waveguide. This effectively red-shifts the notched dip wavelength to cause the format preserved or inversed conversion of data carried by the on-resonant or off-resonant probe, respectively. The Si quantum dots doped Si-rich SiNx strengthens its nonlinear Kerr coefficient by two-orders of magnitude higher than that of bulk Si or Si3N4. The wavelength-converted and cross-amplitude-modulated probe data-stream at up to 12-Gbit/s through the Si-rich SiNx micro-ring with penalty of -7 dB on transmission has shown very promising applicability to all-optical communication networks.

A method for eliminating Faraday rotation in cryostat windows in longitudinal magneto-optical Kerr effect measurements

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

Polewko-Klim, A., E-mail: anetapol@uwb.edu.pl; Uba, S.; Uba, L.

2014-07-15

A solution to the problem of disturbing effect of the background Faraday rotation in the cryostat windows on longitudinal magneto-optical Kerr effect (LMOKE) measured under vacuum conditions and/or at low temperatures is proposed. The method for eliminating the influence of Faraday rotation in cryostat windows is based on special arrangement of additional mirrors placed on sample holder. In this arrangement, the orientation of the cryostat window is perpendicular to the light beam direction and parallel to an external magnetic field generated by the H-frame electromagnet. The operation of the LMOKE magnetometer with the special sample holder based on polarization modulationmore » technique with a photo-elastic modulator is theoretically analyzed with the use of Jones matrices, and formulas for evaluating of the actual Kerr rotation and ellipticity of the sample are derived. The feasibility of the method and good performance of the magnetometer is experimentally demonstrated for the LMOKE effect measured in Fe/Au multilayer structures. The influence of imperfect alignment of the magnetometer setup on the Kerr angles, as derived theoretically through the analytic model and verified experimentally, is examined and discussed.« less

Designing environmental research for impact.

PubMed

Campbell, C A; Lefroy, E C; Caddy-Retalic, S; Bax, N; Doherty, P J; Douglas, M M; Johnson, D; Possingham, H P; Specht, A; Tarte, D; West, J

2015-11-15

Transdisciplinary research, involving close collaboration between researchers and the users of research, has been a feature of environmental problem solving for several decades, often spurred by the need to find negotiated outcomes to intractable problems. In 2005, the Australian government allocated funding to its environment portfolio for public good research, which resulted in consecutive four-year programmes (Commonwealth Environmental Research Facilities, National Environmental Research Program). In April 2014, representatives of the funders, researchers and research users associated with these programmes met to reflect on eight years of experience with these collaborative research models. This structured reflection concluded that successful multi-institutional transdisciplinary research is necessarily a joint enterprise between funding agencies, researchers and the end users of research. The design and governance of research programmes need to explicitly recognise shared accountabilities among the participants, while respecting the different perspectives of each group. Experience shows that traditional incentive systems for academic researchers, current trends in public sector management, and loose organisation of many end users, work against sustained transdisciplinary research on intractable problems, which require continuity and adaptive learning by all three parties. The likelihood of research influencing and improving environmental policy and management is maximised when researchers, funders and research users have shared goals; there is sufficient continuity of personnel to build trust and sustain dialogue throughout the research process from issue scoping to application of findings; and there is sufficient flexibility in the funding, structure and operation of transdisciplinary research initiatives to enable the enterprise to assimilate and respond to new knowledge and situations. Copyright © 2014 Elsevier B.V. All rights reserved.

Summer Undergraduate Research Program: Environmental studies

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

McMillan, J.

1994-12-31

The purpose of the summer undergraduate internship program for research in environmental studies is to provide an opportunity for well-qualified students to undertake an original research project as an apprentice to an active research scientist in basic environmental research. The students are offered research topics at the Medical University in the scientific areas of pharmacology and toxicology, epidemiology and risk assessment, environmental microbiology, and marine sciences. Students are also afforded the opportunity to work with faculty at the University of Charleston, SC, on projects with an environmental theme. Ten well-qualified students from colleges and universities throughout the eastern United Statesmore » were accepted into the program.« less

Children's Environmental Health Research

EPA Pesticide Factsheets

Conducted in-house, with our federal partners like NIH’s National Institute of Environmental Health Services (NIEHS), and by external researchers through a research grants program administered through the agency’s Office of Research & Development.

The quantum emission spectra of rapidly-rotating Kerr black holes: Discrete or continuous?

NASA Astrophysics Data System (ADS)

Hod, Shahar

2015-10-01

Bekenstein and Mukhanov (BM) have suggested that, in a quantum theory of gravity, black holes may have discrete emission spectra. Using the time-energy uncertainty principle they have also shown that, for a (non-rotating) Schwarzschild black hole, the natural broadening δω of the black-hole emission lines is expected to be small on the scale set by the characteristic frequency spacing Δω of the spectral lines: ζSch ≡ δω / Δω ≪ 1. BM have therefore concluded that the expected discrete emission lines of the quantized Schwarzschild black hole are unlikely to overlap. In this paper we calculate the characteristic dimensionless ratio ζ (a bar) ≡ δω / Δω for the predicted BM emission spectra of rapidly-rotating Kerr black holes (here a bar ≡ J /M2 is the dimensionless angular momentum of the black hole). It is shown that ζ (a bar) is an increasing function of the black-hole angular momentum. In particular, we find that the quantum emission lines of Kerr black holes in the regime a bar ≳ 0.9 are characterized by the dimensionless ratio ζ (a bar) ≳ 1 and are therefore effectively blended together. Our results thus suggest that, even if the underlying mass (energy) spectrum of these rapidly-rotating Kerr black holes is fundamentally discrete as suggested by Bekenstein and Mukhanov, the natural broadening phenomenon (associated with the time-energy uncertainty principle) is expected to smear the black-hole radiation spectrum into a continuum.

Phase space information in a non-linear quantum system containing a Kerr-like medium through Su(1, 1)-algebraic treatment

NASA Astrophysics Data System (ADS)

Mohamed, Abdel-Baset A.

2018-05-01

Analytical description for a Su(2)-quantum system interacting with a damped Su(1, 1)-cavity, which is filled with a non-linear Kerr medium, is presented. The dynamics of non-classicality of Su(1, 1)-state is investigated via the negative part of the Wigner function. We show that the negative part depends on the unitary interaction and the Kerr-like medium and it can be disappeared by increasing the dissipation rate and the detuning parameter. The phase space information of the Husimi function and its Wehrl density is very sensitive not only to the coupling to the environment and the unitary interaction but also to the detuning as well as to the Kerr-like medium. The phase space information may be completely erased by increasing the coupling to the environment. The coherence loss of the Su(2)-state is investigated via the Husimi Wehrl entropy. If the effects of the detuning parameter or/and of the Kerr-like medium are combined with the damping effect, the damping effect of the coupling to the environment may be weaken, and the Wehrl entropy is delayed to reach its steady-state value. At the steady-state value, the phase space information and the coherence are quickly lost.

Environmental futures research at the U.S. Environmental Protection Agency

Treesearch

Robert L. Olson

2012-01-01

Relatively little research on environmental futures has been carried out in the United States. An exception is the long-running futures research that the U.S. Environmental Protection Agency (EPA) has been conducting since the 1970s. This paper reviews past and current efforts toward developing a capacity for environmental foresight within the EPA, and discusses some...

The characteristics of Kerr-lens mode-locked self-Raman Nd:YVO4 1176 nm laser

NASA Astrophysics Data System (ADS)

Li, Zuohan; Peng, Jiying; Yao, Jianquan; Han, Ming

2017-03-01

In this paper we report on a compact and feasible dual-concave cavity CW Kerr-lens mode-locked self-Raman Nd:YVO4 laser. A self-starting diode-pumped picosecond Nd:YVO4 1176 nm laser is demonstrated without any additional components, where the stimulated Stokes Raman scattering and Kerr-lens-induced mode locking are operated in the same crystal. With an incident pump power of 12 W, the average output power at 1176 nm is up to 643 mW. Meanwhile, the repetition rate and the pulse width of the fundamental laser are measured to be 1.53 GHz and 8.6 ps, respectively. In addition, the yellow laser output at 588 nm is realized by frequency doubling with a LiB3O5 crystal.

Higher-order Kerr effect and harmonic cascading in gases.

PubMed

Bache, Morten; Eilenberger, Falk; Minardi, Stefano

2012-11-15

The higher-order Kerr effect (HOKE) has recently been advocated to explain measurements of the saturation of the nonlinear refractive index in gases. Here we show that cascaded third-harmonic generation results in an effective fifth-order nonlinearity that is negative and significant. Higher-order harmonic cascading will also occur from the HOKE, and the cascading contributions may significantly modify the observed nonlinear index change. At lower wavelengths, cascading increases the HOKE saturation intensity, while for longer wavelengths cascading will decrease the HOKE saturation intensity.

Hawking radiation by Kerr black holes and conformal symmetry.

PubMed

Agullo, Ivan; Navarro-Salas, José; Olmo, Gonzalo J; Parker, Leonard

2010-11-19

The exponential blueshift associated with the event horizon of a black hole makes conformal symmetry play a fundamental role in accounting for its thermal properties. Using a derivation based on two-point functions, we show that the full spectrum of thermal radiation of scalar particles by Kerr black holes can be explicitly derived on the basis of a conformal symmetry arising in the wave equation near the horizon. The simplicity of our approach emphasizes the depth of the connection between conformal symmetry and black hole radiance.

Near horizon symmetry and entropy formula for Kerr-Newman (A)dS black holes

NASA Astrophysics Data System (ADS)

Setare, Mohammad Reza; Adami, Hamed

2018-04-01

In this paper we provide the first non-trivial evidence for universality of the entropy formula 4 πJ 0 + J 0 - beyond pure Einstein gravity in 4-dimensions. We consider the Einstein-Maxwell theory in the presence of cosmological constant, then write near horizon metric of the Kerr-Newman (A)dS black hole in the Gaussian null coordinate system. We consider near horizon fall-off conditions for metric and U(1) gauge field. We find asymptotic combined symmetry generator, consists of diffeomorphism and U(1) gauge transformation, so that it preserves fall-off conditions. Consequently, we find supertranslation, supperrotation and multiple-charge modes and then we show that the entropy formula is held for the Kerr-Newman (A)dS black hole. Supperrotation modes suffer from a problem. By introducing new combined symmetry generator, we cure that problem.

Computing the Entropy of Kerr-Newman Black Hole Without Brick Walls Method

NASA Astrophysics Data System (ADS)

Zhang, Li-Chun; Wu, Yue-Qin; Li, Huai-Fan; Ren, Zhao

By using the entanglement entropy method, the statistical entropy of the Bose and Fermi fields in a thin film is calculated and the Bekenstein-Hawking entropy of Kerr-Newman black hole is obtained. Here, the Bose and Fermi fields are entangled with the quantum states in Kerr-Newman black hole and are outside of the horizon. The divergence of brick-wall model is avoided without any cutoff by the new equation of state density obtained with the generalized uncertainty principle. The calculation implies that the high density quantum states near the event horizon are strongly correlated with the quantum states in black hole. The black hole entropy is a quantum effect. It is an intrinsic characteristic of space-time. The ultraviolet cutoff in the brick-wall model is unreasonable. The generalized uncertainty principle should be considered in the high energy quantum field near the event horizon. From the calculation, the constant λ introduced in the generalized uncertainty principle is related to polar angle θ in an axisymmetric space-time.

The modified Misgav-Ladach versus the Pfannenstiel-Kerr technique for cesarean section: a randomized trial.

PubMed

Xavier, Pedro; Ayres-De-Campos, Diogo; Reynolds, Ana; Guimarães, Mariana; Costa-Santos, Cristina; Patrício, Belmiro

2005-09-01

Modifications to the classic cesarean section technique described by Pfannenstiel and Kerr have been proposed in the last few years. The objective of this trial was to compare intraoperative and short-term postoperative outcomes between the Pfannenstiel-Kerr and the modified Misgav-Ladach (MML) techniques for cesarean section. This prospective randomized trial involved 162 patients undergoing transverse lower uterine segment cesarean section. Patients were allocated to one of the two arms: 88 to the MML technique and 74 to the Pfannenstiel-Kerr technique. Main outcome measures were defined as the duration of surgery, analgesic requirements, and bowel restitution by the second postoperative day. Additional outcomes evaluated were febrile morbidity, postoperative antibiotic use, postpartum endometritis, and wound complications. Student's t, Mann-Whitney, and Chi-square tests were used for statistical analysis of the results, and a p < 0.05 was considered as the probability level reflecting significant differences. No differences between groups were noted in the incidence of analgesic requirements, bowel restitution by the second postoperative day, febrile morbidity, antibiotic requirements, endometritis, or wound complications. The MML technique took on average 12 min less to complete (p = 0.001). The MML technique is faster to perform and similar in terms of febrile morbidity, time to bowel restitution, or need for postoperative medications. It is likely to be more cost-effective.

Three-configurational surface magneto-optical Kerr effect measurement system for an ultrahigh vacuum in situ study of ultrathin magnetic films

NASA Astrophysics Data System (ADS)

Lee, J.-W.; Jeong, J.-R.; Kim, D.-H.; Ahn, J. S.; Kim, J.; Shin, S.-C.

2000-10-01

We have constructed a three-configurational surface magneto-optical Kerr effect system, which provides the simultaneous measurements of the "polar," "longitudinal," and "transverse" Kerr hysteresis loops at the position where deposition is carried out in an ultrahigh vacuum growth chamber. The present system enables in situ three-dimensional vectorial studies of ultrathin film magnetism with a submonolayer sensitivity. We present three-configurational hysteresis loops measured during the growth of Co films on Pd(111), glass, and Pd/glass substrates.

Effects of external magnetic field and out-of-plane strain on magneto-optical Kerr spectra in CrI3 monolayer.

PubMed

Guo, Guanxing; Bi, Gang; Cai, Chunfeng; Wu, Huizhen

2018-07-18

Magnetic semiconductors based on two-dimensional (2D) crystals have attracted attention owing to their intrinsic ferromagnetism and have potential for spintronic devices. Here, full-potential linearized augmented plane wave plus local orbitals method is used to explore the structural, electronic, magnetic, and magneto-optical properties of CrI 3 monolayer. Our first-principles calculations show that CrI 3 monolayer is a ferromagnetic indirect semiconductor with spin-up and spin-down band gaps of 1.23 and 1.90 eV, respectively, and a magnetic moment of 2.93 [Formula: see text] per Cr atom. Based on the macroscopic linear response theory, we systematically study the influences of external magnetic field and out-of-plane strain on the magneto-optical Kerr effect spectra in CrI 3 monolayer. The Kerr rotation of CrI 3 monolayer at 1.96 eV photon energy is [Formula: see text], which is consistent with the recent experiments. We find that the Kerr rotation reaches its maximum when the external magnetic field is perpendicular to CrI 3 plane, while it is almost zero on turning the magnetic field in the plane. This result as well as the sizable magnetocrystalline anisotropy energy (MAE) of 0.79 meV verifies that CrI 3 monolayer has a strong magnetic anisotropy with an out-of-plane easy axis. Further, applying out-of-plane compressive and tensile strain upon CrI 3 monolayer, we observe a redshift of the Kerr rotation spectra with the increase of the strain and the peak values of the Kerr rotation increase correspondingly. The rich electronic and magnetic properties, especially the magneto-optical spectra, render CrI 3 monolayer a promising 2D magnetic material for applications from sensing to data storage.

A PREP Panel, Practice-Based, Evaluation of the Handling of the Kerr Demi-Ultra Light Curing Unit.

PubMed

Burke, F J Trevor; Crisp, Russell J

2015-09-01

This paper describes the handling evaluation (by a group of practice-based researchers, the PREP Panel) of a recently introduced Light Curing Unit (LCU), the Kerr Demi-Ultra, which possesses a number of novel features such as its ultracapacitor power source, and the Light Emitting Diodes (LEDs) which provide the light output being placed close to the tip of the light guide. CPD/CLINICAL RELEVANCE: Testing of new devices and materials with respect to their handling is of importance, given that an easy to handle device should produce better clinical results than one which is difficult to use.

Magneto-Optic Kerr Effect in a Magnetized Electron Gun

NASA Astrophysics Data System (ADS)

Hardy, Benjamin; Grames, Joseph; CenterInjectors; Sources Team

2016-09-01

Magnetized electron sources have the potential to improve ion beam cooling efficiency. At the Gun Test Stand at Jefferson Lab, a solenoid magnet will be installed adjacent to the photogun to magnetize the electron beam. Due to the photocathode operating in a vacuum chamber, measuring and monitoring the magnetic field at the beam source location with conventional probes is impractical. The Magneto-Optical Kerr Effect (MOKE) describes the change on polarized light by reflection from a magnetized surface. The reflection from the surface may alter the polarization direction, ellipticity, or intensity, and depends linearly upon the surface magnetization of the sample. By replacing the photocathode with a magnetized sample and reflecting polarized light from the sample surface, the magnetic field at the beam source is inferred. A controlled MOKE system has been assembled to test the magnetic field. Calibration of the solenoid magnet is performed by comparing the MOKE signal with magnetic field measurements. The apparatus will provide a description of the field at electron beam source. The report summarizes the method and results of controlled tests and calibration of the MOKE sample with the solenoid magnet field measurements. This work is supported by the National Science Foundation, Research Experience for Undergraduates Award 1359026 and the Department of Energy, Laboratory Directed Research and Development Contract DE-AC05-06OR23177.

BOOK REVIEW Cracking the Einstein Code: Relativity and the Birth of Black Hole Physics With an Afterword by Roy Kerr Cracking the Einstein Code: Relativity and the Birth of Black Hole Physics With an Afterword by Roy Kerr

NASA Astrophysics Data System (ADS)

Carr, Bernard

2011-02-01

General relativity is arguably the most beautiful scientific theory ever conceived but its status within mainstream physics has vacillated since it was proposed in 1915. It began auspiciously with the successful explanation of the precession of Mercury and the dramatic confirmation of light-bending in the 1919 solar eclipse expedition, which turned Einstein into an overnight celebrity. Though little noticed at the time, there was also Karl Schwarzschild's discovery of the spherically symmetric solution in 1916 (later used to predict the existence of black holes) and Alexander Friedmann's discovery of the cosmological solution in 1922 (later confirmed by the discovery of the cosmic expansion). Then for 40 years the theory was more or less forgotten, partly because most physicists were turning their attention to the even more radical developments of quantum theory but also because the equations were too complicated to solve except in situations involving special symmetries or very weak gravitational fields (where general relativity is very similar to Newtonian theory). Furthermore, it was not clear that strong gravitational fields would ever arise in the real universe and, even if they did, it seemed unlikely that Einstein's equations could then be solved. So research in relativity became a quiet backwater as mainstream physics swept forward in other directions. Even Einstein lost interest, turning his attention to the search for a unified field theory. This book tells the remarkable story of how the tide changed in 1963, when the 28-year-old New Zealand mathematician Roy Kerr discovered an exact solution of Einstein's equations which represents a rotating black hole, thereby cracking the code of the title. The paper was just a few pages long, it being left for others to fill in the extensive beautiful mathematics which underlay the result, but it ushered in a golden age of relativity and is now one of the most cited works in physics. Coincidentally, Kerr

An Environmental Ethical Conceptual Framework for Research on Sustainability and Environmental Education

ERIC Educational Resources Information Center

Kronlid, David O.; Ohman, Johan

2013-01-01

This article suggests that environmental ethics can have great relevance for environmental ethical content analyses in environmental education and education for sustainable development research. It is based on a critique that existing educational research does not reflect the variety of environmental ethical theories. Accordingly, we suggest an…

Gravitational radiation from extreme Kerr black hole

NASA Technical Reports Server (NTRS)

Sasaki, Misao; Nakamura, Takashi

1989-01-01

Gravitational radiation induced by a test particle falling into an extreme Kerr black hole was investigated analytically. Assuming the radiation is dominated by the infinite sequence of quasi-normal modes which has the limiting frequency m/(2M), where m is an azimuthal eigenvalue and M is the mass of the black hole, it was found that the radiated energy diverges logarithmically in time. Then the back reaction to the black hole was evaluated by appealing to the energy and angular momentum conservation laws. It was found that the radiation has a tendency to increase the ratio of the angular momentum to mass of the black hole, which is completely different from non-extreme case, while the contribution of the test particle is to decrease it.

Unstable Mode Solutions to the Klein-Gordon Equation in Kerr-anti-de Sitter Spacetimes

NASA Astrophysics Data System (ADS)

Dold, Dominic

2017-03-01

For any cosmological constant {Λ = -3/ℓ2 < 0} and any {α < 9/4}, we find a Kerr-AdS spacetime {({M}, g_{KAdS})}, in which the Klein-Gordon equation {Box_{g_{KAdS}}ψ + α/ℓ2ψ = 0} has an exponentially growing mode solution satisfying a Dirichlet boundary condition at infinity. The spacetime violates the Hawking-Reall bound {r+2 > |a|ℓ}. We obtain an analogous result for Neumann boundary conditions if {5/4 < α < 9/4}. Moreover, in the Dirichlet case, one can prove that, for any Kerr-AdS spacetime violating the Hawking-Reall bound, there exists an open family of masses {α} such that the corresponding Klein-Gordon equation permits exponentially growing mode solutions. Our result adopts methods of Shlapentokh-Rothman developed in (Commun. Math. Phys. 329:859-891, 2014) and provides the first rigorous construction of a superradiant instability for negative cosmological constant.

Number-phase minimum-uncertainty state with reduced number uncertainty in a Kerr nonlinear interferometer

NASA Astrophysics Data System (ADS)

Kitagawa, M.; Yamamoto, Y.

1987-11-01

An alternative scheme for generating amplitude-squeezed states of photons based on unitary evolution which can properly be described by quantum mechanics is presented. This scheme is a nonlinear Mach-Zehnder interferometer containing an optical Kerr medium. The quasi-probability density (QPD) and photon-number distribution of the output field are calculated, and it is demonstrated that the reduced photon-number uncertainty and enhanced phase uncertainty maintain the minimum-uncertainty product. A self-phase-modulation of the single-mode quantized field in the Kerr medium is described based on localized operators. The spatial evolution of the state is demonstrated by QPD in the Schroedinger picture. It is shown that photon-number variance can be reduced to a level far below the limit for an ordinary squeezed state, and that the state prepared using this scheme remains a number-phase minimum-uncertainty state until the maximum reduction of number fluctuations is surpassed.

Research priorities in environmental education

Treesearch

George H. Moeller

1977-01-01

Although natural processes operate in urban areas, they are difficult to observe. Much discussion during the symposium-fair was devoted to finding ways to improve urban children's environmental understanding through environmental education programs. But before effective environmental education programs can be developed, research is needed to: test the...

Hidden symmetries of the Kerr metric and Goldstone’s theorem

NASA Astrophysics Data System (ADS)

Penna, Robert F.

2011-12-01

Perturbations of the Kerr metric admit a spectrum of massless excitations, which we interpret as Goldstone modes coming from the metric’s broken spherical symmetry. The zero-frequency mode is related to the conformal Yano-Killing tensor which encodes Carter’s constant and the Killing vectors of the spacetime. The modes are described by a conformal field theory, which becomes two-dimensional Liouville theory in the near-horizon limit. Directly counting the quantum microstates of this theory reproduces the Bekenstein-Hawking area law.

Qualitative methods in environmental health research.

PubMed Central

Brown, Phil

2003-01-01

Public health researchers increasingly turn to qualitative methods either on their own or in combination with quantitative methods. Qualitative methods are especially important to community environmental health research, as they provide a way to produce community narratives that give voice to individuals and characterize the community in a full and complex fashion. This article first traces the legacy of qualitative research in environmental health, then uses a case study of the author's experiences studying the Woburn, Massachusetts, childhood leukemia cluster to provide personal and scholarly insights on qualitative approaches. That material then informs a discussion of important components of qualitative methods in environmental health research, including flexible study design, access, trust, empathy, and personal shifts in the researcher's worldview, bias, and the nature of the researcher's roles. A concluding discussion addresses issues in funding policy and research practices. PMID:14594634

X-ray magneto-optic KERR effect studies of spring magnet heterostructures.

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

Kortright, J. B.; Kim, S.-K.; Fullerton, E. E.

2000-11-01

The complex 3-dimensional magnetization reversal behavior of Sin-Co/Fe exchange spring films is used to test the sensitivity of different resonant soft x-ray magneto-optical Kerr effect (MOKE) measurements to changes in longitudinal and transverse moments within the SOIIFe layer and to changes in these moments in depth within the Fe layer. As in the visible MOKE, changes in longitudinal and net transverse moments are resolved by measuring both Kerr rotation and intensity loops in the near the Fe 2p core resonance. These x-ray MOKE signals measured using linear incident polarization are more directly interpreted in terms of longitudinal and transverse momentsmore » than are the same signals measured using elliptical polarization. Varying photon energy near the Fe L3line is shown to be an effective means of resolving distinctly different reversal behavior at the top and bottom of the 20 nm thick Fe layer resulting from the strong exchange coupling at the Sin-Co/Fe interface. Measured x-ray MOKE spectra and signals are in qualitative agreement with those calculated using standard magneto-optical formalisms incorporating interference between different layers and measured helicity-dependent magneto-optical constants for Fe.« less

Measurement of ultrafast optical Kerr effect of Ge-Sb-Se chalcogenide slab waveguides by the beam self-trapping technique

NASA Astrophysics Data System (ADS)

Kuriakose, Tintu; Baudet, Emeline; Halenkovič, Tomáš; Elsawy, Mahmoud M. R.; Němec, Petr; Nazabal, Virginie; Renversez, Gilles; Chauvet, Mathieu

2017-11-01

We present a reliable and original experimental technique based on the analysis of beam self-trapping to measure ultrafast optical nonlinearities in planar waveguides. The technique is applied to the characterization of Ge-Sb-Se chalcogenide films that allow Kerr induced self-focusing and soliton formation. Linear and nonlinear optical constants of three different chalcogenide waveguides are studied at 1200 and 1550 nm in femtosecond regime. Waveguide propagation loss and two photon absorption coefficients are determined by transmission analysis. Beam broadening and narrowing results are compared with simulations of the nonlinear Schrödinger equation solved by BPM method to deduce the Kerr n2 coefficients. Kerr optical nonlinearities obtained by our original technique compare favorably with the values obtained by Z-scan technique. Nonlinear refractive index as high as (69 ± 11) × 10-18m2 / W is measured in Ge12.5Sb25Se62.5 at 1200 nm with low nonlinear absorption and low propagation losses which reveals the great characteristics of our waveguides for ultrafast all optical switching and integrated photonic devices.

Quantum Statistical Properties of the Codirectional Kerr Nonlinear Coupler in Terms of su (2 ) Lie Group in Interaction with a Two-level Atom

NASA Astrophysics Data System (ADS)

Abdalla, M. Sebawe; Khalil, E. M.; Obada, A. S.-F.

2017-08-01

The problem of the codirectional Kerr coupler has been considered several times from different point of view. In the present paper we introduce the interaction between a two-level atom and the codirectional Kerr nonlinear coupler in terms of su (2 ) Lie algebra. Under certain conditions we have adjusted the Kerr coupler and consequently we have managed to handle the problem. The wave function is obtained by using the evolution operator where the Heisnberg equation of motion is invoked to get the constants of the motion. We note that the Kerr parameter χ as well as the quantum number j plays the role of controlling the atomic inversion behavior. Also the maximum entanglement occurs after a short period of time when χ = 0. On the other hand for the entropy and the variance squeezing we observe that there is exchange between the quadrature variances. Furthermore, the variation in the quantum number j as well as in the parameter χ leads to increase or decrease in the number of fluctuations. Finally we examined the second order correlation function where classical and nonclassical phenomena are observed.

A note on physical mass and the thermodynamics of AdS-Kerr black holes

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

McInnes, Brett; Ong, Yen Chin, E-mail: matmcinn@nus.edu.sg, E-mail: yenchin.ong@nordita.org

As with any black hole, asymptotically anti-de Sitter Kerr black holes are described by a small number of parameters, including a ''mass parameter'' M that reduces to the AdS-Schwarzschild mass in the limit of vanishing angular momentum. In sharp contrast to the asymptotically flat case, the horizon area of such a black hole increases with the angular momentum parameter a if one fixes M; this appears to mean that the Penrose process in this case would violate the Second Law of black hole thermodynamics. We show that the correct procedure is to fix not M but rather the ''physical'' massmore » E=M/(1−a{sup 2}/L{sup 2}){sup 2}; this is motivated by the First Law. For then the horizon area decreases with a. We recommend that E always be used as the mass in physical processes: for example, in attempts to ''over-spin'' AdS-Kerr black holes.« less

Two-component vector solitons in defocusing Kerr-type media with spatially modulated nonlinearity

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

Zhong, Wei-Ping, E-mail: zhongwp6@126.com; Texas A and M University at Qatar, P.O. Box 23874 Doha; Belić, Milivoj

2014-12-15

We present a class of exact solutions to the coupled (2+1)-dimensional nonlinear Schrödinger equation with spatially modulated nonlinearity and a special external potential, which describe the evolution of two-component vector solitons in defocusing Kerr-type media. We find a robust soliton solution, constructed with the help of Whittaker functions. For specific choices of the topological charge, the radial mode number and the modulation depth, the solitons may exist in various forms, such as the half-moon, necklace-ring, and sawtooth vortex-ring patterns. Our results show that the profile of such solitons can be effectively controlled by the topological charge, the radial mode number,more » and the modulation depth. - Highlights: • Two-component vector soliton clusters in defocusing Kerr-type media are reported. • These soliton clusters are constructed with the help of Whittaker functions. • The half-moon, necklace-ring and vortex-ring patterns are found. • The profile of these solitons can be effectively controlled by three soliton parameters.« less

On the Kerr-AdS/CFT correspondence

NASA Astrophysics Data System (ADS)

Amado, Julián Barragán; da Cunha, Bruno Carneiro; Pallante, Elisabetta

2017-08-01

We review the relation between four-dimensional global conformal blocks and field propagation in AdS5. Following the standard argument that marginal perturbations should backreact in the geometry, we turn to the study of scalar fields in the generic Kerr-AdS5 geometry. On one hand, the result for scattering coefficients can be obtained exactly using the isomonodromy technique, giving exact expressions in terms of c = 1 chiral conformal blocks. On the other hand, one can use the analogy between the scalar field equations to the Level 2 null field Ward identity in two dimensional Liouville field theory to write approximate expressions for the same coefficients in terms of semi-classical chiral Liouville conformal blocks. Surprisingly, the conformal block thus constructed has a well-behaved interpretation in terms of Liouville vertex operators.

Numerical implementation of equations for photon motion in Kerr spacetime

NASA Astrophysics Data System (ADS)

Bursa, Michal

2017-12-01

Raytracing is one of the essential tools for accurate modeling of spectra and variability of various astrophysical objects. It has a major importance in relativistic environments, where light endures to a number of relativistic effects. Because the trajectories of light rays in curved spacetimes, and in Kerr spacetime in particular, are highly non-trivial, we summarize the equations governing the motion of photon (or any other zero rest mass particle) and give analytic solution of the equations that can be further used in practical computer implementations.

Fast-switching optically isotropic liquid crystal nano-droplets with improved depolarization and Kerr effect by doping high k nanoparticles.

PubMed

Kim, Byeonggon; Kim, Hyun Gyu; Shim, Gyu-Yeop; Park, Ji-Sub; Joo, Kyung-Il; Lee, Dong-Jin; Lee, Joun-Ho; Baek, Ji-Ho; Kim, Byeong Koo; Choi, Yoonseuk; Kim, Hak-Rin

2018-01-10

We proposed and analyzed an optically isotropic nano-droplet liquid crystal (LC) doped with high k nanoparticles (NPs), exhibiting enhanced Kerr effects, which could be operated with reduced driving voltages. For enhancing the contrast ratio together with the light efficiencies, the LC droplet sizes were adjusted to be shorter than the wavelength of visible light to reduce depolarization effects by optical scattering of the LC droplets. Based on the optical analysis of the depolarization effects, the influence of the relationship between the LC droplet size and the NP doping ratio on the Kerr effect change was investigated.

Modified Hawking Radiation from a Kerr-Newman Black Hole due to Back-Reaction

NASA Astrophysics Data System (ADS)

Liu, Bo; Wang, Gang; Liu, Wenbiao

Hawking radiation from a general Kerr-Newman black hole is investigated using Damour-Ruffini's method. Considering the back-reaction of particle's energy, charge and angular momentum to the spacetime, we obtain a modified nonthermal spectrum. Maybe the information loss paradox can be explained, furthermore, the result is also consistent with the result obtained using Parikh and Wilczek's method.

Iron Kα line of Kerr black holes with scalar hair

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

Ni, Yueying; Zhou, Menglei; Bambi, Cosimo

Recently, a family of hairy black holes in 4-dimensional Einstein gravity minimally coupled to a complex, massive scalar field was discovered [1]. Besides the mass M and spin angular momentum J , these objects are characterized by a Noether charge Q , measuring the amount of scalar hair, which is not associated to a Gauss law and cannot be measured at spatial infinity. Introducing a dimensionless scalar hair parameter q , ranging from 0 to 1, we recover (a subset of) Kerr black holes for q = 0 and a family of rotating boson stars for q = 1. Inmore » the present paper, we explore the possibility of measuring q for astrophysical black holes with current and future X-ray missions. We study the iron Kα line expected in the reflection spectrum of such hairy black holes and we simulate observations with Suzaku and eXTP. As a proof of concept, we point out, by analyzing a sample of hairy black holes, that current observations can already constrain the scalar hair parameter q , because black holes with q close to 1 would have iron lines definitively different from those we observe in the available data. We conclude that a detailed scanning of the full space of solutions, together with data from the future X-ray missions, like eXTP, will be able to put relevant constraints on the astrophysical realization of Kerr black holes with scalar hair.« less

Environmental Education Research: To What Ends?

ERIC Educational Resources Information Center

Jickling, Bob

2009-01-01

This paper engages questions about ends in environmental education research. In doing so, I argue that such questions are essentially normative, and that normative questions are underrepresented in this field. After cautioning about perils of prescribing research agendas, I gently suggest that in environmental education key normative questions…

Engineering the quantum states of light in a Kerr-nonlinear resonator by two-photon driving

NASA Astrophysics Data System (ADS)

Puri, Shruti; Boutin, Samuel; Blais, Alexandre

2017-04-01

Photonic cat states stored in high-Q resonators show great promise for hardware efficient universal quantum computing. We propose an approach to efficiently prepare such cat states in a Kerr-nonlinear resonator by the use of a two-photon drive. Significantly, we show that this preparation is robust against single-photon loss. An outcome of this observation is that a two-photon drive can eliminate undesirable phase evolution induced by a Kerr nonlinearity. By exploiting the concept of transitionless quantum driving, we moreover demonstrate how non-adiabatic initialization of cat states is possible. Finally, we present a universal set of quantum logical gates that can be performed on the engineered eigenspace of such a two-photon driven resonator and discuss a possible realization using superconducting circuits. The robustness of the engineered subspace to higher-order circuit nonlinearities makes this implementation favorable for scalable quantum computation.

Fast, optically controlled Kerr phase shifter for digital signal processing.

PubMed

Li, R B; Deng, L; Hagley, E W; Payne, M G; Bienfang, J C; Levine, Z H

2013-05-01

We demonstrate an optically controlled Kerr phase shifter using a room-temperature 85Rb vapor operating in a Raman gain scheme. Phase shifts from zero to π relative to an unshifted reference wave are observed, and gated operations are demonstrated. We further demonstrate the versatile digital manipulation of encoded signal light with an encoded phase-control light field using an unbalanced Mach-Zehnder interferometer. Generalizations of this scheme should be capable of full manipulation of a digitized signal field at high speed, opening the door to future applications.

Archeological/Environmental Research

NASA Technical Reports Server (NTRS)

1991-01-01

Landsat/Seasat remote sensing was used by Ames Research Center to evaluate environmental influence on ancient Mayan civilization. Over 35 archeological sites were imaged and valuable information concerning Maya settlement patterns, environment, and resource usage resulted. The imagery was also used by Mexican authorities to develop coastal management plans, establish Biosphere Reserves and assess damage from the 1988 Hurricane Gilbert. Imagery showed evidence of ancient coastlines, changes in sea level, an ancient river plain and Mayan canal systems. Previously unknown Mayan reservoirs were discovered. The project is considered a pioneering effort combining remote sensing, environmental studies and archeology.

In situ Kerr and harmonic measurement in determining current-induced effective fields in MgO/CoFeB/Ta

NASA Astrophysics Data System (ADS)

Wong, Q. Y.; Gan, W. L.; Luo, F. L.; Lim, G. J.; Ang, C. C. I.; Tan, F. N.; Law, W. C.; Lew, W. S.

2018-03-01

A combination of the harmonic measurement and in situ Kerr imaging was used to experimentally determine the spin-orbit (SO) effective fields in a MgO/CoFeB/Ta structure. Here, we evaluate the SO effective fields through an analytical energy approach by transforming the anomalous Hall effect and planar Hall effect (PHE) voltage into a field dependency while imaging the magnetisation behaviour by differential Kerr microscopy. The analytical fitting to the measurement data indicates the significant coexistence of both a transverse field, {{H}T} , and longitudinal field, {{H}L} , in the longitudinal (H L  =  -12 Oe, H T  =  8 Oe per 106 A cm-2) and transverse (H L  =  -12 Oe, H T  =  -17 Oe per 106 A cm-2) measurement schemes, respectively, due to the PHE. Additionally, dendritic-like domains, indicating the influence of the interfacial Dzyaloshinskii-Moriya interaction (DMI) at the CoFeB/Ta interface, were observed by in situ Kerr imaging. Micromagnetic simulations confirm the dendritic domain formation and edge tilting of the magnetisation, as being due to the DMI.

40 CFR 18.3 - Purpose of Environmental Protection Research Fellowships.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Research Fellowships. 18.3 Section 18.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GENERAL ENVIRONMENTAL PROTECTION RESEARCH FELLOWSHIPS AND SPECIAL RESEARCH CONSULTANTS FOR ENVIRONMENTAL PROTECTION § 18.3 Purpose of Environmental Protection Research Fellowships. Environmental Protection Research...

Environmental practices for biomedical research facilities.

PubMed Central

Medlin, E L; Grupenhoff, J T

2000-01-01

As a result of the Leadership Conference on Biomedical Research and the Environment, the Facilities Committee focused its work on the development of best environmental practices at biomedical research facilities at the university and independent research facility level as well as consideration of potential involvement of for-profit companies and government agencies. The designation "facilities" includes all related buildings and grounds, "green auditing" of buildings and programs, purchasing of furnishings and sources, energy efficiency, and engineering services (lighting, heating, air conditioning), among other activities. The committee made a number of recommendations, including development of a national council for environmental stewardship in biomedical research, development of a system of green auditing of such research facilities, and creation of programs for sustainable building and use. In addition, the committee recommended extension of education and training programs for environmental stewardship, in cooperation with facilities managers, for all research administrators and researchers. These programs would focus especially on graduate fellows and other students, as well as on science labs at levels K--12. PMID:11121360

On the competition of forces in the Kerr field

NASA Astrophysics Data System (ADS)

Semerak, O.

1994-11-01

'Rotosphere', where the component of 4-acceleration, radial relative to the symmetry axis, of the stationary observer depends on his angular velocity in a way going against our intuition, is demarcated in the Kerr spacetime. Stationary observers with extremal value of this acceleration ('extremelly accelerated observers') are introduced and their privileged relation to circular geodesics in the equatorial plane is found. Possible translation of the results into 'force' language is based on the definition of the 'centrifugal force' with respect to the zero-angular-momentum observers. It yields, in particular, a simple interpretation of the behavior of acceleration of the stationary observer in terms of gravitational, Coriolis and centrifugal forces.

78 FR 6087 - Biological and Environmental Research Advisory Committee

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-29

... Biological and Environmental Research News from the Biological Systems Science and Climate and Environmental... DEPARTMENT OF ENERGY Biological and Environmental Research Advisory Committee AGENCY: Office of... the Biological and Environmental Research Advisory Committee (BERAC). The Federal Advisory Committee...

Radiation transport around Kerr black holes

NASA Astrophysics Data System (ADS)

Schnittman, Jeremy David

This Thesis describes the basic framework of a relativistic ray-tracing code for analyzing accretion processes around Kerr black holes. We begin in Chapter 1 with a brief historical summary of the major advances in black hole astrophysics over the past few decades. In Chapter 2 we present a detailed description of the ray-tracing code, which can be used to calculate the transfer function between the plane of the accretion disk and the detector plane, an important tool for modeling relativistically broadened emission lines. Observations from the Rossi X-Ray Timing Explorer have shown the existence of high frequency quasi-periodic oscillations (HFQPOs) in a number of black hole binary systems. In Chapter 3, we employ a simple "hot spot" model to explain the position and amplitude of these HFQPO peaks. The power spectrum of the periodic X-ray light curve consists of multiple peaks located at integral combinations of the black hole coordinate frequencies, with the relative amplitude of each peak determined by the orbital inclination, eccentricity, and hot spot arc length. In Chapter 4, we introduce additional features to the model to explain the broadening of the QPO peaks as well as the damping of higher frequency harmonics in the power spectrum. The complete model is used to fit the power spectra observed in XTE J1550-564, giving confidence limits on each of the model parameters. In Chapter 5 we present a description of the structure of a relativistic alpha- disk around a Kerr black hole. Given the surface temperature of the disk, the observed spectrum is calculated using the transfer function mentioned above. The features of this modified thermal spectrum may be used to infer the physical properties of the accretion disk and the central black hole. In Chapter 6 we develop a Monte Carlo code to calculate the detailed propagation of photons from a hot spot emitter scattering through a corona surrounding the black hole. The coronal scattering has two major observable

Optimal all-optical switching of a microcavity resonance in the telecom range using the electronic Kerr effect.

PubMed

Yüce, Emre; Ctistis, Georgios; Claudon, Julien; Gérard, Jean-Michel; Vos, Willem L

2016-01-11

We have switched GaAs/AlAs and AlGaAs/AlAs planar microcavities that operate in the "Original" (O) telecom band by exploiting the instantaneous electronic Kerr effect. We observe that the resonance frequency reversibly shifts within one picosecond when the nanostructure is pumped with low-energy photons. We investigate experimentally and theoretically the role of several parameters: the material backbone and its electronic bandgap, the quality factor, and the duration of the switch pulse. The magnitude of the frequency shift is reduced when the backbone of the central λ-layer has a greater electronic bandgap compared to the cavity resonance frequency and the frequency of the pump. This observation is caused by the fact that pumping with photon energies near the bandgap resonantly enhances the switched magnitude. We thus find that cavities operating in the telecom O-band are more amenable to ultrafast Kerr switching than those operating at lower frequencies, such as the C-band. Our results indicate that the large bandgap of AlGaAs/AlAs cavity allows to tune both the pump and the probe to the telecom range to perform Kerr switching without detrimental two-photon absorption. We observe that the magnitude of the resonance frequency shift decreases with increasing quality factor of the cavity. Our model shows that the magnitude of the resonance frequency shift depends on the pump pulse duration and is maximized when the duration matches the cavity storage time to within a factor two. In our experiments, we obtain a maximum shift of the cavity resonance relative to the cavity linewidth of 20%. We project that the shift of the cavity resonance can be increased twofold with a pump pulse duration that better matches the cavity storage time. We provide the essential parameter settings for different materials so that the frequency shift of the cavity resonance can be maximized using the electronic Kerr effect.

Webinar Presentation: Children’s Environmental Health Research

EPA Pesticide Factsheets

This presentation, Children’s Environmental Health Research, was given at the NIEHS/EPA Children's Centers 2015 Webinar Series: The Significance of Children’s Environmental Health Research Through Collaboration held on July 8, 2015.

Sagnac delay in the Kerr-dS spacetime: Implications for Mach's principle

NASA Astrophysics Data System (ADS)

Karimov, R. Kh.; Izmailov, R. N.; Garipova, G. M.; Nandi, K. K.

2018-02-01

Relativistic twin paradox can have important implications for Mach's principle. It has been recently argued that the behavior of the time asynchrony (different aging of twins) between two flying clocks along closed loops can be attributed to the existence of an absolute spacetime, which makes Mach's principle unfeasible. In this paper, we shall revisit, and support, this argument from a different viewpoint using the Sagnac delay. This is possible since the above time asynchrony is known to be exactly the same as the Sagnac delay between two circumnavigating light rays re-uniting at the orbiting source/receiver. We shall calculate the effect of mass M and cosmological constant Λ on the delay in the general case of Kerr-de Sitter spacetime. It follows that, in the independent limits M→ 0, spin a→ 0 and Λ → 0, while the Kerr-dS metric reduces to Minkowski metric, the clocks need not tick in consonance since there will still appear a non-zero observable Sagnac delay. While we do not measure spacetime itself, we do measure the Sagnac effect, which signifies an absolute substantive Minkowski spacetime instead of a void. We shall demonstrate a completely different limiting behavior of Sagnac delay, heretofore unknown, between the case of non-geodesic and geodesic source/observer motion.

HUMAN HEALTH RESEARCH IMPLEMENTATION PLAN, NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LABORATORY

EPA Science Inventory

The National Health and Environmental Effects Research Laboratory (NHEERL), as part of the Environmental Protection Agency's (EPA's) Office of Research and Development (ORD), is responsible for conducting research to improve the risk assessment of chemicals for potential effects ...

Two-dimensional Kerr-Fourier imaging of translucent phantoms in thick turbid media

NASA Astrophysics Data System (ADS)

Liang, X.; Wang, L.; Ho, P. P.; Alfano, R. R.

1995-06-01

Translucent scattering phantoms hidden inside a 5.5-cm-thick Intralipid solution were imaged as a function of phantom scattering coefficients by the use of a picosecond time-and space-gated Kerr-Fourier imaging system. A 2-mm-thick translucent phantom with a 0.1% concentration (scattering coefficient) difference from the 55-mm-thick surrounding scattering host can be distinguished at a signal level of approximately 10-10 of the incidence illumination intensity.

A Monte Carlo Code for Relativistic Radiation Transport Around Kerr Black Holes

NASA Technical Reports Server (NTRS)

Schnittman, Jeremy David; Krolik, Julian H.

2013-01-01

We present a new code for radiation transport around Kerr black holes, including arbitrary emission and absorption mechanisms, as well as electron scattering and polarization. The code is particularly useful for analyzing accretion flows made up of optically thick disks and optically thin coronae. We give a detailed description of the methods employed in the code and also present results from a number of numerical tests to assess its accuracy and convergence.

Depth-resolved ballistic imaging in a low-depth-of-field optical Kerr gated imaging system

NASA Astrophysics Data System (ADS)

Zheng, Yipeng; Tan, Wenjiang; Si, Jinhai; Ren, YuHu; Xu, Shichao; Tong, Junyi; Hou, Xun

2016-09-01

We demonstrate depth-resolved imaging in a ballistic imaging system, in which a heterodyned femtosecond optical Kerr gate is introduced to extract useful imaging photons for detecting an object hidden in turbid media and a compound lens is proposed to ensure both the depth-resolved imaging capability and the long working distance. Two objects of about 15-μm widths hidden in a polystyrene-sphere suspension have been successfully imaged with approximately 600-μm depth resolution. Modulation-transfer-function curves with the object in and away from the object plane have also been measured to confirm the depth-resolved imaging capability of the low-depth-of-field (low-DOF) ballistic imaging system. This imaging approach shows potential for application in research of the internal structure of highly scattering fuel spray.

Animals in Environmental Education Research

ERIC Educational Resources Information Center

Spannring, Reingard

2017-01-01

Over the past few decades, the increase in public and scholarly attention to human-animal relations has inspired an animal turn in a number of academic disciplines including environmental education research. This paper reviews the literature on animals in environmental education with respect to its theoretical foundations in critical pedagogy,…

Verification of antiferromagnetic exchange coupling at room temperature using polar magneto-optic Kerr effect in thin EuS/Co multilayers with perpendicular magnetic anisotropy

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

Goschew, A., E-mail: alexander.goschew@fu-berlin.de; Scott, M.; Fumagalli, P.

2016-08-08

We report on magneto-optic Kerr measurements in polar geometry carried out on a series of thin Co/EuS multilayers on suitable Co/Pd-multilayer substrates. Thin Co/EuS multilayers of a few nanometers individual layer thickness usually have their magnetization in plane. Co/Pd multilayers introduce a perpendicular magnetic anisotropy in the Co/EuS layers deposited on top, thus making it possible to measure magneto-optic signals in the polar geometry in remanence in order to study exchange coupling. Magneto-optic Kerr-effect spectra and hysteresis loops were recorded in the visible and ultraviolet photon-energy range at room temperature. The EuS contribution to the magneto-optic signal is extracted atmore » 4.1 eV by combining hysteresis loops measured at different photon energies with polar magneto-optic Kerr-effect spectra recorded in remanence and in an applied magnetic field of 2.2 T. The extracted EuS signal shows clear signs of antiferromagnetic coupling of the Eu magnetic moments to the Co layers. This implies that the ordering temperature of at least a fraction of the EuS layers is above room temperature proving that magneto-optic Kerr-effect spectroscopy can be used here as a quasi-element-specific method.« less

Gate-Controllable Magneto-optic Kerr Effect in Layered Collinear Antiferromagnets

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

Sivadas, Nikhil; Okamoto, Satoshi; Xiao, Di

2016-12-23

In this paper, using symmetry arguments and a tight-binding model, we show that for layered collinear antiferromagnets, magneto-optic effects can be generated and manipulated by controlling crystal symmetries through a gate voltage. This provides a promising route for electric field manipulation of the magneto-optic effects without modifying the underlying magnetic structure. We further demonstrate the gate control of the magneto-optic Kerr effect (MOKE) in bilayer MnPSe 3 using first-principles calculations. Finally, the field-induced inversion symmetry breaking effect leads to gate-controllable MOKE, whose direction of rotation can be switched by the reversal of the gate voltage.

Pair production of scalar dyons in Kerr-Newman black holes

NASA Astrophysics Data System (ADS)

Chen, Chiang-Mei; Kim, Sang Pyo; Sun, Jia-Rui; Tang, Fu-Yi

2018-06-01

We study the spontaneous pair production of scalar dyons in the near extremal dyonic Kerr-Newman (KN) black hole, which contains a warped AdS3 structure in the near horizon region. The leading term contribution of the pair production rate and the absorption cross section ratio are also calculated using the Hamilton-Jacobi approach and the thermal interpretation is given. In addition, the holographic dual conformal field theories (CFTs) descriptions of the pair production rate and absorption cross section ratios are analyzed both in the J-, Q- and P-pictures respectively based on the threefold dyonic KN/CFTs dualities.

Direct investigation of collective phenomena in patterned Ising-like arrays using high-resolution Kerr microscopy

NASA Astrophysics Data System (ADS)

Fraleigh, Robert Douglas

Magnetic systems with interacting ferromagnetic single-domain elements are a useful landscape to explore a wide range of fundamental and technological phenomena. In this dissertation, we consider a system of interacting ferromagnetic islands with perpendicular anisotropy. Islands are lithographically-defined to be single-domain and are arranged into large arrays with geometries that are geometrically frustrated and unfrustrated. We explore field-driven local and global magnetic switching behavior using a home-built diffraction-limited magneto-optical Kerr microscope wherein individual islands in each array are isolated, indexed, and tracked in the presence of an applied external field. Global and local switching behavior is directly accessed through analysis island switching fields in the presence of magnetic hysteresis loops. We first explore the considerations regarding lithographic definition of disconnected islands and deposition of Co/Pt multilayers with strong perpendicular anisotropy. The thickness and number of stacked Co/Pt bilayers as well as deposition method significantly affect the strength of perpendicular anisotropy. We find sputter deposition of a 8-stack bilayer of Co0.3 nm=Pt 1 nm optimizes strong perpendicular anisotropy with square hysteresis loops. Our experimental sample contains several sets of ordered arrays with varying geometry and inter-island spacing. Each island is single-domain with length scales amenable to Kerr imaging such that magnetic degrees of freedom are optically accessible. We next discuss the development, calibration, and operation of a home-built magneto-optical Kerr microscope. The Kerr microscope uses a xenon stabilized white light source, Glan-Thompson polarizers, and a 100x oil objective lens to illuminate a sample with linear polarized light. A cooled CCD camera receives the re ected light and transmits it to the computer in a sequence timed with the application of an external magnetic field. We use LabVIEW software to

Overview of the National Risk Management Research Laboratory: The Environmental Research Institute of the States Environmental Council of the States 2007

EPA Science Inventory

An overview of the EPA Science and Research Organization, The National Risk Management Research Lab, the current research being conducted, priority Environmental Technology Research Issues, and new approaches to environmental management and sustainability taking place at the Nati...

Environmental Justice Research: Contemporary Issues and Emerging Topics

PubMed Central

Chakraborty, Jayajit; Collins, Timothy W.; Grineski, Sara E.

2016-01-01

Environmental justice (EJ) research seeks to document and redress the disproportionate environmental burdens and benefits associated with social inequalities. Although its initial focus was on disparities in exposure to anthropogenic pollution, the scope of EJ research has expanded. In the context of intensifying social inequalities and environmental problems, there is a need to further strengthen the EJ research framework and diversify its application. This Special Issue of the International Journal of Environmental Research and Public Health (IJERPH) incorporates 19 articles that broaden EJ research by considering emerging topics such as energy, food, drinking water, flooding, sustainability, and gender dynamics, including issues in Canada, the UK, and Eastern Europe. Additionally, the articles contribute to three research themes: (1) documenting connections between unjust environmental exposures and health impacts by examining unsafe infrastructure, substance use, and children’s obesity and academic performance; (2) promoting and achieving EJ by implementing interventions to improve environmental knowledge and health, identifying avenues for sustainable community change, and incorporating EJ metrics in government programs; and (3) clarifying stakeholder perceptions of EJ issues to extend research beyond the documentation of unjust conditions and processes. Collectively, the articles highlight potentially compounding injustices and an array of approaches being employed to achieve EJ. PMID:27809294

Environmental Justice Research: Contemporary Issues and Emerging Topics.

PubMed

Chakraborty, Jayajit; Collins, Timothy W; Grineski, Sara E

2016-11-01

Environmental justice (EJ) research seeks to document and redress the disproportionate environmental burdens and benefits associated with social inequalities. Although its initial focus was on disparities in exposure to anthropogenic pollution, the scope of EJ research has expanded. In the context of intensifying social inequalities and environmental problems, there is a need to further strengthen the EJ research framework and diversify its application. This Special Issue of the International Journal of Environmental Research and Public Health (IJERPH) incorporates 19 articles that broaden EJ research by considering emerging topics such as energy, food, drinking water, flooding, sustainability, and gender dynamics, including issues in Canada, the UK, and Eastern Europe. Additionally, the articles contribute to three research themes: (1) documenting connections between unjust environmental exposures and health impacts by examining unsafe infrastructure, substance use, and children's obesity and academic performance; (2) promoting and achieving EJ by implementing interventions to improve environmental knowledge and health, identifying avenues for sustainable community change, and incorporating EJ metrics in government programs; and (3) clarifying stakeholder perceptions of EJ issues to extend research beyond the documentation of unjust conditions and processes. Collectively, the articles highlight potentially compounding injustices and an array of approaches being employed to achieve EJ.

Optical Kerr Spatiotemporal Dark-Lump Dynamics of Hydrodynamic Origin

NASA Astrophysics Data System (ADS)

Baronio, Fabio; Wabnitz, Stefan; Kodama, Yuji

2016-04-01

There is considerable fundamental and applicative interest in obtaining nondiffractive and nondispersive spatiotemporal localized wave packets propagating in optical cubic nonlinear or Kerr media. Here, we analytically predict the existence of a novel family of spatiotemporal dark lump solitary wave solutions of the (2 +1 )D nonlinear Schrödinger equation. Dark lumps represent multidimensional holes of light on a continuous wave background. We analytically derive the dark lumps from the hydrodynamic exact soliton solutions of the (2 +1 )D shallow water Kadomtsev-Petviashvili model, inheriting their complex interaction properties. This finding opens a novel path for the excitation and control of optical spatiotemporal waveforms of hydrodynamic footprint and multidimensional optical extreme wave phenomena.

Optical Kerr Spatiotemporal Dark-Lump Dynamics of Hydrodynamic Origin.

PubMed

Baronio, Fabio; Wabnitz, Stefan; Kodama, Yuji

2016-04-29

There is considerable fundamental and applicative interest in obtaining nondiffractive and nondispersive spatiotemporal localized wave packets propagating in optical cubic nonlinear or Kerr media. Here, we analytically predict the existence of a novel family of spatiotemporal dark lump solitary wave solutions of the (2+1)D nonlinear Schrödinger equation. Dark lumps represent multidimensional holes of light on a continuous wave background. We analytically derive the dark lumps from the hydrodynamic exact soliton solutions of the (2+1)D shallow water Kadomtsev-Petviashvili model, inheriting their complex interaction properties. This finding opens a novel path for the excitation and control of optical spatiotemporal waveforms of hydrodynamic footprint and multidimensional optical extreme wave phenomena.

76 FR 57028 - Biological and Environmental Research Advisory Committee

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Translational Environmental Research: Improving the Usefulness and Usability of Research Results

NASA Astrophysics Data System (ADS)

Garfin, G.

2008-12-01

In recent years, requests for proposals more frequently emphasize outreach to stakeholder communities, decision support, and science that serves societal needs. Reports from the National Academy of Sciences and Western States Water Council emphasize the need for science translation and outreach, in order to address societal concerns with climate extremes, such as drought, the use of climate predictions, and the growing challenges of climate change. In the 1990s, the NOAA Climate Program Office developed its Regional Integrated Sciences and Asssessments program to help bridge the gap between climate science (notably, seasonal predictions) and society, to improve the flow of information to stakeholders, and to increase the relevance of climate science to inform decisions. During the same time period, the National Science Foundation initiated multi-year Science and Technology Centers and Decision Making Under Uncertainty Centers, with similar goals, but different metrics of success. Moreover, the combination of population growth, climate change, and environmental degradation has prompted numerous research initiatives on linking knowledge and action for sustainable development. This presentation reviews various models and methodologies for translating science results from field, lab, or modeling work to use by society. Lessons and approaches from cooperative extension, boundary organizations, co-production of science and policy, and medical translational research are examined. In particular, multi-step translation as practiced within the health care community is examined. For example, so- called "T1" (translation 1) research moves insights from basic science to clinical research; T2 research evaluates the effectiveness of clinical practice, who benefits from promising care regimens, and develops tools for clinicians, patients, and policy makers. T3 activities test the implementation, delivery, and spread of research results and clinical practices in order to foster

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Decay of Solutions of the Wave Equation in the Kerr Geometry

NASA Astrophysics Data System (ADS)

Finster, F.; Kamran, N.; Smoller, J.; Yau, S.-T.

2006-06-01

We consider the Cauchy problem for the massless scalar wave equation in the Kerr geometry for smooth initial data compactly supported outside the event horizon. We prove that the solutions decay in time in L ∞ loc. The proof is based on a representation of the solution as an infinite sum over the angular momentum modes, each of which is an integral of the energy variable ω on the real line. This integral representation involves solutions of the radial and angular ODEs which arise in the separation of variables.

Magnetoelastic Properties of Magnetic Thin Films Using the Magnetooptic Kerr Effect

NASA Astrophysics Data System (ADS)

Mayo, Elizabeth; Lederman, David

1998-03-01

The magnetoelastic properties of Co and Fe thin films were measured using the magnetooptic Kerr effect (MOKE). Films were grown via magnetron sputtering on thin mica substrates. Magnetization loops were measured using MOKE with the magnetic field along different in-plane directions. Subsequently, the samples were mounted on a cylindrical sample holder, which imposed a well-defined strain to the film. This caused the magnetization loops to change dramatically due to the magnetoelastic coefficient of the thin film materials. The effects of the surface roughness and film thickness will also be discussed.

76 FR 8357 - Biological and Environmental Research Advisory Committee

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The Carnegie Commission and Council on Higher Education: A Retrospective. Research & Occasional Paper Series. CSHE.14.05

ERIC Educational Resources Information Center

Douglass, John Aubrey

2005-01-01

It has been nearly forty years since Clark Kerr was asked to create and lead the Carnegie Commission on Higher Education under the auspices of the Carnegie Corporation. The Commission was to be a national effort, unprecedented both in scope and in the freedom of its director, Kerr, to guide its research and productivity. Carnegie President Alan…

Superradiant instabilities in the Kerr-mirror and Kerr-AdS black holes with Robin boundary conditions

NASA Astrophysics Data System (ADS)

Ferreira, Hugo R. C.; Herdeiro, Carlos A. R.

2018-04-01

It has been recently observed that a scalar field with Robin boundary conditions (RBCs) can trigger both a superradiant and a bulk instability for a Bañados-Teitelboim-Zanelli (BTZ) black hole (BH) [1]. To understand the generality and scrutinize the origin of this behavior, we consider here the superradiant instability of a Kerr BH confined either in a mirrorlike cavity or in anti-de Sitter (AdS) space, triggered also by a scalar field with RBCs. These boundary conditions are the most general ones that ensure the cavity/AdS space is an isolated system and include, as a particular case, the commonly considered Dirichlet boundary conditions (DBCs). Whereas the superradiant modes for some RBCs differ only mildly from the ones with DBCs, in both cases, we find that as we vary the RBCs the imaginary part of the frequency may attain arbitrarily large positive values. We interpret this growth as being sourced by a bulk instability of both confined geometries when certain RBCs are imposed to either the mirrorlike cavity or the AdS boundary, rather than by energy extraction from the BH, in analogy with the BTZ behavior.

Axisymmetric plasma equilibria in a Kerr metric

NASA Astrophysics Data System (ADS)

Elsässer, Klaus

2001-10-01

Plasma equilibria near a rotating black hole are considered within the multifluid description. An isothermal two-component plasma with electrons and positrons or ions is determined by four structure functions and the boundary conditions. These structure functions are the Bernoulli function and the toroidal canonical momentum per mass for each species. The quasi-neutrality assumption (no charge density, no toroidal current) allows to solve Maxwell's equations analytically for any axisymmetric stationary metric, and to reduce the fluid equations to one single scalar equation for the stream function \\chi of the positrons or ions, respectively. The basic smallness parameter is the ratio of the skin depth of electrons to the scale length of the metric and fluid quantities, and, in the case of an electron-ion plasma, the mass ratio m_e/m_i. The \\chi-equation can be solved by standard methods, and simple solutions for a Kerr geometry are available; they show characteristic flow patterns, depending on the structure functions and the boundary conditions.

Depth-resolved ballistic imaging in a low-depth-of-field optical Kerr gated imaging system

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

Zheng, Yipeng; Tan, Wenjiang, E-mail: tanwenjiang@mail.xjtu.edu.cn; Si, Jinhai

2016-09-07

We demonstrate depth-resolved imaging in a ballistic imaging system, in which a heterodyned femtosecond optical Kerr gate is introduced to extract useful imaging photons for detecting an object hidden in turbid media and a compound lens is proposed to ensure both the depth-resolved imaging capability and the long working distance. Two objects of about 15-μm widths hidden in a polystyrene-sphere suspension have been successfully imaged with approximately 600-μm depth resolution. Modulation-transfer-function curves with the object in and away from the object plane have also been measured to confirm the depth-resolved imaging capability of the low-depth-of-field (low-DOF) ballistic imaging system. Thismore » imaging approach shows potential for application in research of the internal structure of highly scattering fuel spray.« less

Gyroscope precession along bound equatorial plane orbits around a Kerr black hole

NASA Astrophysics Data System (ADS)

Bini, Donato; Geralico, Andrea; Jantzen, Robert T.

2016-09-01

The precession of a test gyroscope along stable bound equatorial plane orbits around a Kerr black hole is analyzed, and the precession angular velocity of the gyro's parallel transported spin vector and the increment in the precession angle after one orbital period is evaluated. The parallel transported Marck frame which enters this discussion is shown to have an elegant geometrical explanation in terms of the electric and magnetic parts of the Killing-Yano 2-form and a Wigner rotation effect.

On the dispersion management of fluorite whispering-gallery mode resonators for Kerr optical frequency comb generation in the telecom and mid-infrared range.

PubMed

Lin, Guoping; Chembo, Yanne K

2015-01-26

Optical whispering gallery mode (WGM) resonators have been very attracting platforms for versatile Kerr frequency comb generations. We report a systematic study on the material dispersion of various optical materials that are capable of supporting quality factors above 10⁹. Using an analytical approximation of WGM resonant frequencies in disk resonators, we investigate the effect of the geometry and transverse mode order on the total group-velocity dispersion (GVD). We demonstrate that the major radii and the radial mode indices play an important role in tailoring the GVD of WGM resonators. In particular, our study shows that in WGM disk-resonators, the polar families of modes have very similar GVD, while the radial families of modes feature dispersion values that can differ by up to several orders of magnitude. The effect of these giant dispersion shifts are experimentally evidenced in Kerr comb generation with magnesium fluoride. From a more general perspective, this critical feature enables to push the zero-dispersion wavelength of fluorite crystals towards the mid-infrared (mid-IR) range, thereby allowing for efficient Kerr comb generation in that spectral range. We show that barium fluoride is the most interesting crystal in this regard, due to its zero dispersion wavelength (ZDW) at 1.93 μm and an optimal dispersion profile in the mid-IR regime. We expect our results to facilitate the design of different platforms for Kerr frequency comb generations in both telecommunication and mid-IR spectral ranges.

Collisions near Kerr black holes: lower limit of energy between orbiting and incoming particles

NASA Astrophysics Data System (ADS)

Rutkowski, Mieszko

2017-01-01

In our paper we investigate the lower limit of collisional energy of test particles near the Kerr black hole. In particular we examine the minimal Lorentz factor between the freely falling particles and the particles orbiting around a black hole. We consider collisions on the innermost stable circular orbit and examine near-extreme case, where collisions take place near an event horizon. By fine-tuning the particles' angular momentum, the Lorentz factor of the collision can always be minimized to a value dependent on the black hole's spin. We identified that this minimal value is always less than 2√{2}-1/√{3} and more than √{12}-1/√{6} (the limits are the values for an extreme Kerr and Schwarzschild, respectively). It implies that this kind of collisions of compact objects are expected to be highly energetic near supermassive black holes. In addition, we show that an interaction between black hole's and particle's spins has an influence on minimal Lorentz factor. This contribution is nonnegligible for near-extreme black holes. We also discuss the relation between our results and sci-fi movie Interstellar.

Hopfield-Kerr model and analogue black hole radiation in dielectrics

NASA Astrophysics Data System (ADS)

Belgiorno, F.; Cacciatori, S. L.; Dalla Piazza, F.; Doronzo, M.

2017-11-01

In the context of the interaction between the electromagnetic field and a dielectric dispersive lossless medium, we present a nonlinear version of the relativistically covariant Hopfield model, which is suitable for the description of a dielectric Kerr perturbation propagating in a dielectric medium. The nonlinearity is introduced in the Lagrangian through a self-interacting term proportional to the fourth power of the polarization field. We find an exact solution for the nonlinear equations describing a propagating perturbation in the dielectric medium. Furthermore, the presence of an analogue Hawking effect, as well as the thermal properties of the model, are discussed, confirming and improving the results achieved in the scalar case.

40 CFR 18.5 - Qualifications for Environmental Protection Research Fellowships.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Qualifications for Environmental Protection Research Fellowships. 18.5 Section 18.5 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GENERAL ENVIRONMENTAL PROTECTION RESEARCH FELLOWSHIPS AND SPECIAL RESEARCH CONSULTANTS FOR ENVIRONMENTAL...

Local nondestructive data reading in three-dimensional memory systems based on the optical Kerr effect

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

Zheltikov, Aleksei M; Koroteev, Nikolai I; Naumov, A N

1998-11-30

An investigation was made of the characteristics of the optical Kerr effect in a spiropyran solution. It was found that this effect makes it possible to distinguish the coloured and uncoloured forms of spiropyran and that it represents a promising method for nondestructive data reading in three-dimensional optical memory systems based on photochromic materials. (letters to the editor)

Intrinsic and Extrinsic Origins of the Polar Kerr Effect in a Chiral p-WAVE Superconductor

NASA Astrophysics Data System (ADS)

Goryo, Jun

Recently, the measurement of the polar Kerr effect (PKE) in the quasi two-dimensional superconductor Sr2RuO4, which is motivated to observe the chirality of px + ipy-wave pairing, has been reported. We clarify that the PKE has intrinsic and extrinsic (disorder-induced) origins. The extrinsic contribution would be dominant in the PKE experiment.

The Carnegie Commission and Council on Higher Education: A Retrospective. Research and Occasional Paper Series: CSHE.14.05

ERIC Educational Resources Information Center

Douglass, John Aubrey

2005-01-01

It has been nearly forty years since Clark Kerr was asked to create and lead the Carnegie Commission on Higher Education under the auspices of the Carnegie Corporation. The Commission was to be a national effort, unprecedented both in scope and in the freedom of its director, Kerr, to guide its research and productivity. Carnegie President Alan…

Coexistence of Multiple Nonlinear States in a Tristable Passive Kerr Resonator

NASA Astrophysics Data System (ADS)

Anderson, Miles; Wang, Yadong; Leo, François; Coen, Stéphane; Erkintalo, Miro; Murdoch, Stuart G.

2017-07-01

Passive Kerr cavities driven by coherent laser fields display a rich landscape of nonlinear physics, including bistability, pattern formation, and localized dissipative structures (solitons). Their conceptual simplicity has for several decades offered an unprecedented window into nonlinear cavity dynamics, providing insights into numerous systems and applications ranging from all-optical memory devices to microresonator frequency combs. Yet despite the decades of study, a recent theoretical work has surprisingly alluded to an entirely new and unexplored paradigm in the regime where nonlinearly tilted cavity resonances overlap with one another [T. Hansson and S. Wabnitz, J. Opt. Soc. Am. B 32, 1259 (2015), 10.1364/JOSAB.32.001259]. We use synchronously driven fiber ring resonators to experimentally access this regime and observe the rise of new nonlinear dissipative states. Specifically, we observe, for the first time to the best of our knowledge, the stable coexistence of temporal Kerr cavity solitons and extended modulation instability (Turing) patterns, and perform real-time measurements that unveil the dynamics of the ensuing nonlinear structure. When operating in the regime of continuous wave tristability, we further observe the coexistence of two distinct cavity soliton states, one of which can be identified as a "super" cavity soliton, as predicted by Hansson and Wabnitz. Our experimental findings are in excellent agreement with theoretical analyses and numerical simulations of the infinite-dimensional Ikeda map that governs the cavity dynamics. The results from our work reveal that experimental systems can support complex combinations of distinct nonlinear states, and they could have practical implications to future microresonator-based frequency comb sources.

75 FR 41514 - Notice of Availability of a Draft Environmental Impact Statement for the Greater Natural Buttes...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-16

.... Based on the foregoing documents and a review of information from Utah Division of Oil Gas and Mining... cumulative environmental impacts of a proposal to develop natural gas in Uintah County, Utah. This notice... by Kerr-McGee Oil & Gas Onshore LP (KMG), a wholly- owned subsidiary of Anadarko Petroleum...

40 CFR 18.3 - Purpose of Environmental Protection Research Fellowships.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Fellowships in the Agency are for the purpose of encouraging and promoting research, studies, and... Research Fellowships. 18.3 Section 18.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GENERAL ENVIRONMENTAL PROTECTION RESEARCH FELLOWSHIPS AND SPECIAL RESEARCH CONSULTANTS FOR ENVIRONMENTAL PROTECTION § 18...

Water and Environmental Research Institute of the Western Pacific

Science.gov Websites

UOG Pre-engineering Program © 2018 University of Guam, Water and Environmental Research Institute of Water and Environmental Research Institute of the Western Pacific - University of Guam Skip to main entered the website of the Water and Environmental Research Institute of the Western Pacific (WERI) at the

Hysteresis and memory factor of the Kerr effect in blue phases

NASA Astrophysics Data System (ADS)

Nordendorf, Gaby; Lorenz, Alexander; Hoischen, Andreas; Schmidtke, Jürgen; Kitzerow, Heinz; Wilkes, David; Wittek, Michael

2013-11-01

The performance of a polymer-stabilized blue phase system based on a nematic host with large dielectric anisotropy and a chiral dopant with high helical twisting power is investigated and the influence of the reactive monomer composition on the electro-optic characteristics is studied. Field-induced birefringence with a Kerr coefficient greater than 1 nm V-2 can be achieved in a large temperature range from well below 20 °C to above 55 °C. The disturbing influences of electro-optic hysteresis and memory effects can be reduced by diligent choice of the composition and appropriate electric addressing.

Hidden instabilities in the Ti:sapphire Kerr lens mode-locked laser.

PubMed

Kovalsky, M G; Hnilo, A A; González Inchauspe, C M

1999-11-15

It is experimentally shown that pulse-to-pulse instabilities in the output of Kerr lens mode-locked Ti:sapphire lasers are usual and that they can affect some of the pulse variables (e.g., the spot size) and not others (e.g., pulse duration and energy). These instabilities are not detectable in the averaged signals (such as the autocorrelation of the pulse) that are customarily used for controlling the laser. But, if they are present but are disregarded, these instabilities have undesirable consequences in almost any application. A simple way to detect and eliminate the instabilities is described.

77 FR 55200 - Biological and Environmental Research Advisory Committee

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-07

... News from the Biological Systems Science and Climate and Environmental Sciences Divisions Discussion of... DEPARTMENT OF ENERGY Biological and Environmental Research Advisory Committee AGENCY: Office of... the Biological and Environmental Research Advisory Committee (BERAC). The Federal Advisory Committee...

78 FR 77111 - Biological and Environmental Research Advisory Committee

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-20

..., General Services Administration, notice is hereby given that the Biological and Environmental Research... DEPARTMENT OF ENERGY Biological and Environmental Research Advisory Committee AGENCY: Office of... provides advice and recommendations to the Director, Office of Science on the biological and environmental...

ACQUISITION OF REPRESENTATIVE GROUND WATER QUALITY SAMPLES FOR METALS

EPA Science Inventory

R.S. Kerr Environmental Research Laboratory (RSKERL) personnel have evaluated sampling procedures for the collection of representative, accurate, and reproducible ground water quality samples for metals for the past four years. Intensive sampling research at three different field...

Native Americans: Where in Environmental Justice Research?

PubMed Central

Vickery, Jamie; Hunter, Lori M.

2016-01-01

While the last two decades have seen important theoretical, empirical, and policy advancements in environmental justice generally, much remains to be done regarding Native Americans. Unique political and cultural dynamics shape the study and pursuit of environmental justice (EJ) in Native American communities. This review summarizes Native American EJ issues based on a cross-disciplinary search of over 60 publications. In so doing, we discuss the unique nature of Native American EJ in terms of conducting research and working toward reducing the continuation of historical trauma associated with environmental ills, the types of strategies used in Native American EJ research, and issues of Native American climate justice. We conclude with discussion of remaining knowledge gaps and future research needs. PMID:27103758

An Integral Spectral Representation of the Propagator for the Wave Equation in the Kerr Geometry

NASA Astrophysics Data System (ADS)

Finster, F.; Kamran, N.; Smoller, J.; Yau, S.-T.

2005-12-01

We consider the scalar wave equation in the Kerr geometry for Cauchy data which is smooth and compactly supported outside the event horizon. We derive an integral representation which expresses the solution as a superposition of solutions of the radial and angular ODEs which arise in the separation of variables. In particular, we prove completeness of the solutions of the separated ODEs.

(2 + 1)-dimensional bright optical solitons in metamaterials with Kerr, power and parabolic law nonlinearities

NASA Astrophysics Data System (ADS)

Boubir, Badreddine

2018-06-01

In this paper, we investigate the dynamics of bright optical solitons in nonlinear metamaterials governed by a (2 + 1)-dimensional nonlinear Schrödinger equation. Three types of nonlinearities have been considered, Kerr law, power law and parabolic law. We based on the solitary wave ansatz method to find these optical soliton solutions. All necessary parametric conditions for their existence are driven.

Magneto-optical Kerr effect of a Ni2.00Mn1.16Ga0.84 single crystal across austenite and intermartensite transitions

NASA Astrophysics Data System (ADS)

Fikáček, Jan; Heczko, Oleg; Kopecký, Vít; Kaštil, Jiří; Honolka, Jan

2018-04-01

We carried out magneto-optical Kerr effect (MOKE) and magnetization measurements on a single crystal of Ni2.00Mn1.16Ga0.84, which is a magnetic shape memory material with application potential for actuator devices or for energy recuperation. Up to the time of our study, there had been reports of MOKE measurements in polar geometry. Against earlier predictions, we show that surface magnetic states of the martensite and the austenite can be also probed efficiently via longitudinal MOKE. A single-variant magnetic state prepared at room temperature is characterized by square-shaped ferromagnetic hysteresis loops yielding coercive fields, which are key material properties for future applications. Temperature dependencies of Kerr rotation were found to be linearly proportional to magnetization for martensitic phases. After passing through an inter-martensitic structural transition below room temperature in zero magnetic field, the coercive fields are more than doubled in comparison with the room temperature values. Above room temperature where an austenite structure is formed, MOKE signals are dominated by quadratic contributions and the magnitude of Kerr rotation drops due to changes in the electronic and magnetic domains structure.

Applying environmental product design to biomedical products research.

PubMed Central

Messelbeck, J; Sutherland, L

2000-01-01

The principal themes for the Biomedical Research and the Environment Conference Committee on Environmental Economics in Biomedical Research include the following: healthcare delivery companies and biomedical research organizations, both nonprofit and for-profit, need to improve their environmental performance; suppliers of healthcare products will be called upon to support this need; and improving the environmental profile of healthcare products begins in research and development (R&D). The committee report begins with requirements from regulatory authorities (e.g., U.S. Environmental Protection Agency [EPA], the U.S. Food and Drug Administration), and the healthcare delivery sector). The 1998 American Hospital Association and EPA Memorandum of Understanding to reduce solid waste and mercury from healthcare facilities is emblematic of these requirements. The dominant message from the requirements discussion is to ensure that R&D organizations do not ignore customer, environmental, and regulatory requirements in the early stages of product development. Several representatives from healthcare products manufacturers presented their companies' approaches to meeting these requirements. They reported on efforts to ensure that their R&D processes are sensitive to the environmental consequences from manufacturing, distributing, using, and disposing of healthcare products. These reports describe representatives' awareness of requirements and the unique approaches their R&D organizations have taken to meet these requirements. All representatives reported that their R&D organizations have embraced environmental product design because it avoids the potential of returning products to R&D to improve the environmental profile. Additionally, several reports detailed cost savings, sustainability benefits, and improvements in environmental manufacturing or redesign, and increased customer satisfaction. Many companies in healthcare delivery are working to improve environmental

Applying environmental product design to biomedical products research.

PubMed

Messelbeck, J; Sutherland, L

2000-12-01

The principal themes for the Biomedical Research and the Environment Conference Committee on Environmental Economics in Biomedical Research include the following: healthcare delivery companies and biomedical research organizations, both nonprofit and for-profit, need to improve their environmental performance; suppliers of healthcare products will be called upon to support this need; and improving the environmental profile of healthcare products begins in research and development (R&D). The committee report begins with requirements from regulatory authorities (e.g., U.S. Environmental Protection Agency [EPA], the U.S. Food and Drug Administration), and the healthcare delivery sector). The 1998 American Hospital Association and EPA Memorandum of Understanding to reduce solid waste and mercury from healthcare facilities is emblematic of these requirements. The dominant message from the requirements discussion is to ensure that R&D organizations do not ignore customer, environmental, and regulatory requirements in the early stages of product development. Several representatives from healthcare products manufacturers presented their companies' approaches to meeting these requirements. They reported on efforts to ensure that their R&D processes are sensitive to the environmental consequences from manufacturing, distributing, using, and disposing of healthcare products. These reports describe representatives' awareness of requirements and the unique approaches their R&D organizations have taken to meet these requirements. All representatives reported that their R&D organizations have embraced environmental product design because it avoids the potential of returning products to R&D to improve the environmental profile. Additionally, several reports detailed cost savings, sustainability benefits, and improvements in environmental manufacturing or redesign, and increased customer satisfaction. Many companies in healthcare delivery are working to improve environmental

The Dynamics of a Five-level (Double Λ)-type Atom Interacting with Two-mode Field in a Cross Kerr-like Medium

NASA Astrophysics Data System (ADS)

Obada, A.-S. F.; Ahmed, M. M. A.; Farouk, Ahmed M.

2018-04-01

In this paper, we propose a new transition scheme (Double Λ) for the interaction between a five-level atom and an electromagnetic field and study its dynamics in the presence of a cross Kerr-like medium in the exact-resonance case. The wave function is derived when the atom is initially prepared in its upper most state, and the field is initially prepared in the coherent state. We studied the atomic population inversion, the coherence degree by studying the second-order correlation function, Cauchy-Schwartz inequality (CSI) and the relation with P-function. Finally, we investigate the effect of Kerr-like medium on the evolution of Husimi Q-function of the considered system.

Improvement of on/off ratio in single-shot multichannel demultiplexing by using an optical Kerr gate of a squarylium dye J aggregate film

NASA Astrophysics Data System (ADS)

Sato, Yasuhiro; Furuki, Makoto; Tian, Minquan; Iwasa, Izumi; Pu, Lyong Sun; Tatsuura, Satoshi

2002-04-01

We demonstrated ultrafast single-shot multichannel demultiplexing by using a squarylium dye J aggregate film as an optical Kerr medium. High efficiency and fast recovery of the optical Kerr responses were achieved when a signal-pulse wavelength was close to the absorption peak of the J aggregate film with off-resonant excitation. The on/off ratio in demultiplexing of 1 Tb/s signals was improved to be approximately 5. By introducing time delay to both horizontal and vertical directions, we succeeded in directly observing the conversion of 1 Tb/s serial signals into two-dimensionally arranged parallel signals.

Is the Kerr black hole a super accelerator?

NASA Astrophysics Data System (ADS)

Krasnikov, S.; Skvortsova, M. V.

2018-02-01

A number of long-standing puzzles, such as the origin of extreme-energy cosmic rays, could perhaps be solved if we found a mechanism for effectively transferring energy from black holes to particles and, correspondingly, accelerating the latter to (unboundedly, as long as we neglect the back reaction) large velocities. As of today the only such candidate mechanism in the case of the nonextreme Kerr black hole is colliding a particle that freely falls from infinity with a particle whose trajectory is subject to some special requirements to fulfil which it has to be suitably corrected by auxiliary collisions. In the present paper we prove that—at least when the relevant particles move in the equatorial plane and experience a single correcting collision—this mechanism does not work too. The energy of the final collision becomes unboundedly high only when the energies of the incoming particles do.

Femtosecond Kerr index of cyclic olefin co/polymers for THz nonlinear optics

NASA Astrophysics Data System (ADS)

Noskovicova, E.; Lorenc, D.; Slusna, L.; Velic, D.

2016-10-01

The second-order nonlinear refractive index n2 (Kerr index) of cyclic olefin copolymer (TOPAS) and cyclic olefin polymers (ZEONEX, ZEONOR) was determined at the wavelength of 800 nm within this work. Bulk samples of ZEONEX, ZEONOR and TOPAS were measured using the single-beam Z-scan technique and the values of their nonlinear refractive index were determined to be approximately 2 × 10-20 m2W-1 for all cases. The obtained values of n2 play a vital role for ultrafast pulse evolution and corresponding phenomena such as nonlinear spectral transformation.

Nanostructural organization in carbon disulfide/ionic liquid mixtures: Molecular dynamics simulations and optical Kerr effect spectroscopy

NASA Astrophysics Data System (ADS)

Yang, Peng; Voth, Gregory A.; Xiao, Dong; Hines, Larry G.; Bartsch, Richard A.; Quitevis, Edward L.

2011-07-01

In this paper, the nanostructural organization and subpicosecond intermolecular dynamics in the mixtures of CS2 and the room temperature ionic liquid (IL) 1-pentyl-3-methylimidazolium bis{(trifluoromethane)sulfonyl}amide ([C5mim][NTf2]) were studied as a function of concentration using molecular dynamics (MD) simulations and optical heterodyne-detected Raman-induced Kerr effect spectroscopy. At low CS2 concentrations (<10 mol.% CS2/IL), the MD simulations indicate that the CS2 molecules are localized in the nonpolar domains. In contrast, at higher concentrations (≥10 mol.% CS2/IL), the MD simulations show aggregation of the CS2 molecules. The optical Kerr effect (OKE) spectra of the mixtures are interpreted in terms of an additivity model with the components arising from the subpicosecond dynamics of CS2 and the IL. Comparison of the CS2-component with the OKE spectra of CS2 in alkane solvents is consistent with CS2 mainly being localized in the nonpolar domains, even at high CS2 concentrations, and the local CS2 concentration being higher than the bulk CS2 concentration.

Final Environmental Impact Statement, Brooks City Base Project, Brooks Air Force Base, Texas

DTIC Science & Technology

2001-03-01

Wilson GuadalupeBexar Cornal Kendall Gillespie Kerr Bandera Medina Frio Uvalde Atascosa Karnes NOT TO SCALE Index Map TEXAS San Antonio Brooks AFB 3-60...1987, Anthropology, California State University, San Bernardino Years of Experience: 15 Ray Ramos , P.E., Environmental Professional, Earth Tech M.S...The Honorable Frank Madla, District 29 House of Representatives The Honorable Carlos Uresti, District 118 Elected Officials - Local The Honorable

Magneto-optical Kerr effect in L1{sub 0} FePdPt ternary alloys: Experiments and first-principles calculations

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

Ma, L.; Shi, Z.; Zhou, S. M., E-mail: wur@uci.edu, E-mail: shiming@tongji.edu.cn

2014-05-14

We have studied the magneto-optical Kerr effect (MOKE) of L1{sub 0} Fe{sub 0.5}(Pd{sub 1−x}Pt{sub x}){sub 0.5} alloy films with both experiments and first-principles calculations. In the visible region, negative Kerr rotation and ellipticity peaks are, respectively, observed in the regions of 1.5–2.0 eV and 1.7–2.6 eV. These peaks are shifted towards higher energies, and their magnitudes are enhanced for larger x. The MOKE evolution is mainly ascribed to the anomalous Hall conductivity contributed by the spin-down d{sub ↓,x{sup 2}−y{sup 2}} bands from Pd and Pt. We established a close correlation among the MOKE spectra, the spin orbit coupling strength, andmore » the band feature for this prototypical system.« less

Silicon-nanocrystal Optoelectronic Kerr Effect for Complementary Metal-oxide Semiconductor (CMOS) Compatible Optical Switching

DTIC Science & Technology

2011-04-01

changes the material’s index of refraction via dispersion . This absorption requires carrier transport and, in present implementations, suffers from slow...designed to take advantage of the large Kerr effect that has been reported in Si-nanocrystals imbedded in oxide (Si-nc). The expected refractive index ...estimate of the expected refractive index change versus applied voltage. An index change of ~2 x 10–4 is enough to modulate the light, corresponding to a

COOPEUS - connecting research infrastructures in environmental sciences

NASA Astrophysics Data System (ADS)

Koop-Jakobsen, Ketil; Waldmann, Christoph; Huber, Robert

2015-04-01

The COOPEUS project was initiated in 2012 bringing together 10 research infrastructures (RIs) in environmental sciences from the EU and US in order to improve the discovery, access, and use of environmental information and data across scientific disciplines and across geographical borders. The COOPEUS mission is to facilitate readily accessible research infrastructure data to advance our understanding of Earth systems through an international community-driven effort, by: Bringing together both user communities and top-down directives to address evolving societal and scientific needs; Removing technical, scientific, cultural and geopolitical barriers for data use; and Coordinating the flow, integrity and preservation of information. A survey of data availability was conducted among the COOPEUS research infrastructures for the purpose of discovering impediments for open international and cross-disciplinary sharing of environmental data. The survey showed that the majority of data offered by the COOPEUS research infrastructures is available via the internet (>90%), but the accessibility to these data differ significantly among research infrastructures; only 45% offer open access on their data, whereas the remaining infrastructures offer restricted access e.g. do not release raw data or sensible data, demand user registration or require permission prior to release of data. These rules and regulations are often installed as a form of standard practice, whereas formal data policies are lacking in 40% of the infrastructures, primarily in the EU. In order to improve this situation COOPEUS has installed a common data-sharing policy, which is agreed upon by all the COOPEUS research infrastructures. To investigate the existing opportunities for improving interoperability among environmental research infrastructures, COOPEUS explored the opportunities with the GEOSS common infrastructure (GCI) by holding a hands-on workshop. Through exercises directly registering resources

FAST TRACK COMMUNICATION: Regularized Kerr-Newman solution as a gravitating soliton

NASA Astrophysics Data System (ADS)

Burinskii, Alexander

2010-10-01

The charged, spinning and gravitating soliton is realized as a regular solution of the Kerr-Newman (KN) field coupled with a chiral Higgs model. A regular core of the solution is formed by a domain wall bubble interpolating between the external KN solution and a flat superconducting interior. An internal electromagnetic (em) field is expelled to the boundary of the bubble by the Higgs field. The solution reveals two new peculiarities: (i) the Higgs field is oscillating, similar to the known oscillon models; (ii) the em field forms on the edge of the bubble a Wilson loop, resulting in quantization of the total angular momentum.

Health and Environmental Research. Summary of Accomplishments

DOE R&D Accomplishments Database

1984-04-01

This is a short account of a 40-year-old health and environmental research program performed in national laboratories, universities, and research institutes. Under the sponsorship of the federal agencies that were consecutively responsible for the national energy mission, this research program has contributed to the understanding of the human health and environmental effects of emergining energy technologies. In so doing, it has also evolved several nuclear techniques for the diagnosis and treatment of human ills. The form of this presentation is through examples of significant, tangible accomplishments in each of these areas at certain times to illustrate the role and impact of the research program. The narrative of this research program concludes with a perspective of its past and a prospectus on its future.

Environmental Behavior and Gender: An Emerging Area of Concern for Environmental Education Research

ERIC Educational Resources Information Center

Sakellari, Maria; Skanavis, Constantina

2013-01-01

Ecofeminism suggests that women are more active than men regarding environmental issues for a variety of social, cultural, and biological reasons. In support to these arguments, women predominate within the overall grassroots of the Environmental Justice movement. However, claims have been made that environmental education theory and research are…

Nonradial and nonpolytropic astrophysical outflows. X. Relativistic MHD rotating spine jets in Kerr metric

NASA Astrophysics Data System (ADS)

Chantry, L.; Cayatte, V.; Sauty, C.; Vlahakis, N.; Tsinganos, K.

2018-04-01

Context. High-resolution radio imaging of active galactic nuclei (AGN) has revealed that the jets of some sources present superluminal knots and transverse stratification. Recent observational projects, such as ALMA and γ-ray telescopes, such as HESS and HESS2 have provided new observational constraints on the central regions of rotating black holes in AGN, suggesting that there is an inner- or spine-jet surrounded by a disk wind. This relativistic spine-jet is likely to be composed of electron-positron pairs extracting energy from the black hole and will be explored by the future γ-ray telescope CTA. Aims: In this article we present an extension to and generalization of relativistic jets in Kerr metric of the Newtonian meridional self-similar mechanism. We aim at modeling the inner spine-jet of AGN as a relativistic light outflow emerging from a spherical corona surrounding a Kerr black hole and its inner accretion disk. Methods: The model is built by expanding the metric and the forces with colatitude to first order in the magnetic flux function. As a result of the expansion, all colatitudinal variations of the physical quantities are quantified by a unique parameter. Unlike previous models, effects of the light cylinder are not neglected. Results: Solutions with high Lorentz factors are obtained and provide spine-jet models up to the polar axis. As in previous publications, we calculate the magnetic collimation efficiency parameter, which measures the variation of the available energy across the field lines. This collimation efficiency is an integral part of the model, generalizing the classical magnetic rotator efficiency criterion to Kerr metric. We study the variation of the magnetic efficiency and acceleration with the spin of the black hole and show their high sensitivity to this integral. Conclusions: These new solutions model collimated or radial, relativistic or ultra-relativistic outflows in AGN or γ-ray bursts. In particular, we discuss the

Groundwater Technical Support Center (GWTSC) Annual Report Fiscal Year 2016 (FY16)

EPA Science Inventory

The Groundwater Technical Support Center (GWTSC) is part of the Groundwater, Watershed, and Ecosystem Restoration Division (GWERD), which is based in the Robert S. Kerr Environmental Research Center in Ada, Oklahoma. The GWERD is a research division of EPA’s National Risk M...

Widely tunable optical parametric oscillation in a Kerr microresonator.

PubMed

Sayson, Noel Lito B; Webb, Karen E; Coen, Stéphane; Erkintalo, Miro; Murdoch, Stuart G

2017-12-15

We report on the first experimental demonstration of widely tunable parametric sideband generation in a Kerr microresonator. Specifically, by pumping a silica microsphere in the normal dispersion regime, we achieve the generation of phase-matched four-wave mixing sidebands at large frequency detunings from the pump. Thanks to the role of higher-order dispersion in enabling phase matching, small variations of the pump wavelength translate into very large and controllable changes in the wavelengths of the generated sidebands: we experimentally demonstrate over 720 nm of tunability using a low-power continuous-wave pump laser in the C-band. We also derive simple theoretical predictions for the phase-matched sideband frequencies and discuss the predictions in light of the discrete cavity resonance frequencies. Our experimentally measured sideband wavelengths are in very good agreement with theoretical predictions obtained from our simple phase-matching analysis.

Hawking radiation of charged Dirac particles from a Kerr-Newman black hole

NASA Astrophysics Data System (ADS)

Zhou, Shiwei; Liu, Wenbiao

2008-05-01

Charged Dirac particles’ Hawking radiation from a Kerr-Newman black hole is calculated using Damour-Ruffini’s method. When energy conservation and the backreaction of particles to the space-time are considered, the emission spectrum is not purely thermal anymore. The leading term is exactly the Boltzman factor, and the deviation from the purely thermal spectrum can bring some information out, which can be treated as an explanation to the information loss paradox. The result can also be treated as a quantum-corrected radiation temperature, which is dependent on the black hole background and the radiation particle’s energy, angular momentum, and charge.

ASSESSMENT OF COLD-CLIMATE ENVIRONMENTAL RESEARCH PRIORITIES

EPA Science Inventory

Since its inception, the U.S. Environmental Protection Agency has maintained a research program in Alaska to address environmental problems unique to cold climates. The wide range of natural resource developments now being considered pose an equally wide range of possible environ...

Focus on environmental justice: new directions in international research

NASA Astrophysics Data System (ADS)

Chakraborty, Jayajit

2017-03-01

More than three decades since the emergence of the environmental justice (EJ) movement in the U.S., environmental injustices continue to unfold across the world to include new narratives of air and water pollution, as well as new forms of injustices associated with climate change, energy use, natural disasters, urban greenspaces, and public policies that adversely affect socially disadvantaged communities and future generations. This focus issue of Environmental Research Letters provides an interdisciplinary forum for conceptual, methodological, and empirical scholarship on EJ activism, research, and policy that highlights the continuing salience of an EJ perspective to understanding nature-society linkages. The 16 letters published in this focus issue address a variety of environmental issues and social injustices in multiple countries across the world, and advance EJ research by: (1) demonstrating how environmental injustice emerges through particular policies and political processes; (2) exploring environmental injustices associated with industrialization and industrial pollution; and (3) documenting unjust exposure to various environmental hazards in specific urban landscapes. As the discourse of EJ continues to evolve both topically and geographically, we hope that this focus issue will help establish research agendas for the next generation of EJ scholarship on distributive, procedural, participatory, and other forms of injustices, as well as their interrelationships.

40 CFR 18.10 - Appointment of Special Research Consultants for Environmental Protection.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Consultants for Environmental Protection. 18.10 Section 18.10 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GENERAL ENVIRONMENTAL PROTECTION RESEARCH FELLOWSHIPS AND SPECIAL RESEARCH CONSULTANTS FOR ENVIRONMENTAL PROTECTION § 18.10 Appointment of Special Research Consultants for Environmental Protection. (a...

Polarization entanglement purification of nonlocal microwave photons based on the cross-Kerr effect in circuit QED

NASA Astrophysics Data System (ADS)

Zhang, Hao; Liu, Qian; Xu, Xu-Sheng; Xiong, Jun; Alsaedi, Ahmed; Hayat, Tasawar; Deng, Fu-Guo

2017-11-01

Microwave photons have become very important qubits in quantum communication, as the first quantum satellite has been launched successfully. Therefore, it is a necessary and meaningful task for ensuring the high security and efficiency of microwave-based quantum communication in practice. Here, we present an original polarization entanglement purification protocol for nonlocal microwave photons based on the cross-Kerr effect in circuit quantum electrodynamics (QED). Our protocol can solve the problem that the purity of maximally entangled states used for constructing quantum channels will decrease due to decoherence from environment noise. This task is accomplished by means of the polarization parity-check quantum nondemolition (QND) detector, the bit-flipping operation, and the linear microwave elements. The QND detector is composed of several cross-Kerr effect systems which can be realized by coupling two superconducting transmission line resonators to a superconducting molecule with the N -type level structure. We give the applicable experimental parameters of QND measurement system in circuit QED and analyze the fidelities. Our protocol has good applications in long-distance quantum communication assisted by microwave photons in the future, such as satellite quantum communication.

Overspinning a Kerr black hole: The effect of the self-force

NASA Astrophysics Data System (ADS)

Colleoni, Marta; Barack, Leor

2015-05-01

We study the scenario in which a massive particle is thrown into a rapidly rotating Kerr black hole in an attempt to spin it up beyond its extremal limit, challenging weak cosmic censorship. We work in black-hole perturbation theory, and focus on nonspinning, uncharged particles sent in on equatorial orbits. We first identify the complete parameter-space region in which overspinning occurs when backreaction effects from the particle's self-gravity are ignored. We find, in particular, that overspinning can be achieved only with particles sent in from infinity. Gravitational self-force effects may prevent overspinning by radiating away a sufficient amount of the particle's angular momentum ("dissipative effect"), and/or by increasing the effective centrifugal repulsion, so that particles with suitable parameters never get captured ("conservative effect"). We analyze the full effect of the self-force, thereby completing previous studies by Jacobson and Sotiriou (who neglected the self-force) and by Barausse, Cardoso and Khanna (who considered the dissipative effect on a subset of orbits). Our main result is an inequality, involving certain self-force quantities, which describes a necessary and sufficient condition for the overspinning scenario to be overruled. This "censorship" condition is formulated on a certain one-parameter family of geodesics in the limit of an extremal Kerr geometry. We find that the censorship condition is insensitive to the dissipative effect (within the first-order self-force approximation used here), except for a subset of perfectly fine-tuned orbits, for which a separate censorship condition is derived. We do not obtain here the self-force input needed to evaluate either of our two conditions, but discuss the prospects for producing the necessary data using state-of-the-art numerical codes.

Enhancement of the transversal magnetic optic Kerr effect: Lock-in vs. hysteresis method.

PubMed

Hayek, Jorge Nicolás; Herreño-Fierro, César A; Patiño, Edgar J

2016-10-01

The lock-in amplifier is often used to study the enhancement of the magneto-optical Kerr effect (MOKE) in the presence of plasmon resonances. In the present work we show that it is possible to investigate such effect replacing the lock-in amplifier by a compensator, filter, and differential amplifier. This allows us to extract the full hysteresis loop in and out of the resonance without the need of a lock-in amplifier. Our results demonstrate these two setups are equivalent to study the enhancement of the transversal MOKE (T-MOKE) in magnetoplasmonic systems.

All-optical analog-to-digital converter based on Kerr effect in photonic crystal

NASA Astrophysics Data System (ADS)

Jafari, Dariush; Nurmohammadi, Tofiq; Asadi, Mohammad Javad; Abbasian, Karim

2018-05-01

In this paper, a novel all-optical analog-to-digital converter (AOADC) is proposed and simulated for proof of principle. This AOADC is designed to operate in the range of telecom wavelength (1550 nm). A cavity made of nonlinear Kerr material in photonic crystal (PhC), is designed to achieve an optical analog-to-digital conversion with 1 Tera sample per second (TS/s) and the total footprint of 42 μm2 . The simulation is done using finite-difference time domain (FDTD) method.

Environmental Sciences Division: Summaries of research in FY 1996

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

NONE

This document describes the Fiscal Year 1996 activities and products of the Environmental Sciences Division, Office of Biological and Environmental Research, Office of Energy Research. The report is organized into four main sections. The introduction identifies the basic program structure, describes the programs of the Environmental Sciences Division, and provides the level of effort for each program area. The research areas and project descriptions section gives program contact information, and provides descriptions of individual research projects including: three-year funding history, research objective and approach used in each project, and results to date. Appendixes provide postal and e-mail addresses for principalmore » investigators and define acronyms used in the text. The indexes provide indexes of principal investigators, research institutions, and keywords for easy reference. Research projects are related to climatic change and remedial action.« less

Ground Water Technical Support Center (GWTSC) Annual Report Fiscal Year 2014 (FY14)

EPA Science Inventory

The Ground Water Technical Support Center (GWTSC) is part of the Ground Water and Ecosystems Restoration Division (GWERD), which is based in the Robert S. Kerr Environmental Research Center in Ada, Oklahoma. The GWERD is a research division of U.S. EPA's National Risk Management...

Ground Water Technical Support Center (GWTSC) Annual Report FY 2012: October 2011 – September 2012

EPA Science Inventory

The Ground Water Technical Support Center (GWTSC) is part of the Ground Water and Ecosystems Restoration Division (GWERD), which is based in the Robert S. Kerr Environmental Research Center in Ada, Oklahoma. The GWERD is a research division of U.S. EPA's National Risk Management...

Research on third-order susceptibility tensor of silicon at telecom wavelength

NASA Astrophysics Data System (ADS)

Zhang, Yu-Hong; Liu, Hang; Chen, Zhan-Guo; Jia, Gang; Ren, Ce

2010-10-01

In this paper, the electro-induced birefringence based on Kerr effect and Franz-Keldysh effect in bulk silicon crystal at 1.3μm wavelengths has been measured. By using Kerr effect, the third-order susceptibility tensor of bulk crystalline silicon has been calculated.The two independent tensor of silicon X (3) susceptibility can be obtained by calculation (3) 6.22 (1 2.2%) 10 -20 m2 V2 and Xxyxy(3) = and xxxx(3) 9.13 (1 +/-2.2%) 10-20 m2 V 2 = m2/V2. The research can drive the silicon utility in the photo-electricity field.

Expanded solutions of force-free electrodynamics on general Kerr black holes

NASA Astrophysics Data System (ADS)

Li, Huiquan; Wang, Jiancheng

2017-07-01

In this work, expanded solutions of force-free magnetospheres on general Kerr black holes are derived through a radial distance expansion method. From the regular conditions both at the horizon and at spatial infinity, two previously known asymptotical solutions (one of them is actually an exact solution) are identified as the only solutions that satisfy the same conditions at the two boundaries. Taking them as initial conditions at the boundaries, expanded solutions up to the first few orders are derived by solving the stream equation order by order. It is shown that our extension of the exact solution can (partially) cure the problems of the solution: it leads to magnetic domination and a mostly timelike current for restricted parameters.

Empirical research on international environmental migration: a systematic review.

PubMed

Obokata, Reiko; Veronis, Luisa; McLeman, Robert

2014-01-01

This paper presents the findings of a systematic review of scholarly publications that report empirical findings from studies of environmentally-related international migration. There exists a small, but growing accumulation of empirical studies that consider environmentally-linked migration that spans international borders. These studies provide useful evidence for scholars and policymakers in understanding how environmental factors interact with political, economic and social factors to influence migration behavior and outcomes that are specific to international movements of people, in highlighting promising future research directions, and in raising important considerations for international policymaking. Our review identifies countries of migrant origin and destination that have so far been the subject of empirical research, the environmental factors believed to have influenced these migrations, the interactions of environmental and non-environmental factors as well as the role of context in influencing migration behavior, and the types of methods used by researchers. In reporting our findings, we identify the strengths and challenges associated with the main empirical approaches, highlight significant gaps and future opportunities for empirical work, and contribute to advancing understanding of environmental influences on international migration more generally. Specifically, we propose an exploratory framework to take into account the role of context in shaping environmental migration across borders, including the dynamic and complex interactions between environmental and non-environmental factors at a range of scales.

Skills and Knowledge for Data-Intensive Environmental Research

PubMed Central

Hampton, Stephanie E.; Jones, Matthew B.; Wasser, Leah A.; Schildhauer, Mark P.; Supp, Sarah R.; Brun, Julien; Hernandez, Rebecca R.; Boettiger, Carl; Collins, Scott L.; Gross, Louis J.; Fernández, Denny S.; Budden, Amber; White, Ethan P.; Teal, Tracy K.; Aukema, Juliann E.

2017-01-01

Abstract The scale and magnitude of complex and pressing environmental issues lend urgency to the need for integrative and reproducible analysis and synthesis, facilitated by data-intensive research approaches. However, the recent pace of technological change has been such that appropriate skills to accomplish data-intensive research are lacking among environmental scientists, who more than ever need greater access to training and mentorship in computational skills. Here, we provide a roadmap for raising data competencies of current and next-generation environmental researchers by describing the concepts and skills needed for effectively engaging with the heterogeneous, distributed, and rapidly growing volumes of available data. We articulate five key skills: (1) data management and processing, (2) analysis, (3) software skills for science, (4) visualization, and (5) communication methods for collaboration and dissemination. We provide an overview of the current suite of training initiatives available to environmental scientists and models for closing the skill-transfer gap. PMID:28584342

Skills and Knowledge for Data-Intensive Environmental Research.

PubMed

Hampton, Stephanie E; Jones, Matthew B; Wasser, Leah A; Schildhauer, Mark P; Supp, Sarah R; Brun, Julien; Hernandez, Rebecca R; Boettiger, Carl; Collins, Scott L; Gross, Louis J; Fernández, Denny S; Budden, Amber; White, Ethan P; Teal, Tracy K; Labou, Stephanie G; Aukema, Juliann E

2017-06-01

The scale and magnitude of complex and pressing environmental issues lend urgency to the need for integrative and reproducible analysis and synthesis, facilitated by data-intensive research approaches. However, the recent pace of technological change has been such that appropriate skills to accomplish data-intensive research are lacking among environmental scientists, who more than ever need greater access to training and mentorship in computational skills. Here, we provide a roadmap for raising data competencies of current and next-generation environmental researchers by describing the concepts and skills needed for effectively engaging with the heterogeneous, distributed, and rapidly growing volumes of available data. We articulate five key skills: (1) data management and processing, (2) analysis, (3) software skills for science, (4) visualization, and (5) communication methods for collaboration and dissemination. We provide an overview of the current suite of training initiatives available to environmental scientists and models for closing the skill-transfer gap.

Enhanced photon-phonon cross-Kerr nonlinearity with two-photon driving.

PubMed

Yin, Tai-Shuang; Lü, Xin-You; Wan, Liang-Liang; Bin, Shang-Wu; Wu, Ying

2018-05-01

We propose a scheme to significantly enhance the cross-Kerr (CK) nonlinearity between photons and phonons in a quadratically coupled optomechanical system (OMS) with two-photon driving. This CK nonlinear enhancement originates from the parametric-driving-induced squeezing and the underlying nonlinear optomechanical interaction. Moreover, the noise of the squeezed mode can be suppressed completely by introducing a squeezed vacuum reservoir. As a result of this dramatic nonlinear enhancement and the suppressed noise, we demonstrate the feasibility of the quantum nondemolition measurement of the phonon number in an originally weak coupled OMS. In addition, the photon-phonon blockade phenomenon is also investigated in this regime, which allows for performing manipulations between photons and phonons. This Letter offers a promising route towards the potential application for the OMS in quantum information processing and quantum networks.

On the Future of American Higher Education: A Bibliography of Clark Kerr. Public Administration Series: Bibliography P-1033.

ERIC Educational Resources Information Center

Quay, Richard H.

A bibliography of publications authored, coauthored, or edited by Clark Kerr on the future of American higher education is presented. The specific topics of the publications, which cover 1939-1981, include the following: the failure of academic reform in the United States and Western Europe, changes and challenges ahead for community colleges,…

Cohort profile: the maternal-infant research on environmental chemicals research platform.

PubMed

Arbuckle, Tye E; Fraser, William D; Fisher, Mandy; Davis, Karelyn; Liang, Chun Lei; Lupien, Nicole; Bastien, Stéphanie; Velez, Maria P; von Dadelszen, Peter; Hemmings, Denise G; Wang, Jingwei; Helewa, Michael; Taback, Shayne; Sermer, Mathew; Foster, Warren; Ross, Greg; Fredette, Paul; Smith, Graeme; Walker, Mark; Shear, Roberta; Dodds, Linda; Ettinger, Adrienne S; Weber, Jean-Philippe; D'Amour, Monique; Legrand, Melissa; Kumarathasan, Premkumari; Vincent, Renaud; Luo, Zhong-Cheng; Platt, Robert W; Mitchell, Grant; Hidiroglou, Nick; Cockell, Kevin; Villeneuve, Maya; Rawn, Dorothea F K; Dabeka, Robert; Cao, Xu-Liang; Becalski, Adam; Ratnayake, Nimal; Bondy, Genevieve; Jin, Xiaolei; Wang, Zhongwen; Tittlemier, Sheryl; Julien, Pierre; Avard, Denise; Weiler, Hope; Leblanc, Alain; Muckle, Gina; Boivin, Michel; Dionne, Ginette; Ayotte, Pierre; Lanphear, Bruce; Séguin, Jean R; Saint-Amour, Dave; Dewailly, Eric; Monnier, Patricia; Koren, Gideon; Ouellet, Emmanuel

2013-07-01

The Maternal-Infant Research on Environmental Chemicals (MIREC) Study was established to obtain Canadian biomonitoring data for pregnant women and their infants, and to examine potential adverse health effects of prenatal exposure to priority environmental chemicals on pregnancy and infant health. Women were recruited during the first trimester from 10 sites across Canada and were followed through delivery. Questionnaires were administered during pregnancy and post-delivery to collect information on demographics, occupation, life style, medical history, environmental exposures and diet. Information on the pregnancy and the infant was abstracted from medical charts. Maternal blood, urine, hair and breast milk, as well as cord blood and infant meconium, were collected and analysed for an extensive list of environmental biomarkers and nutrients. Additional biospecimens were stored in the study's Biobank. The MIREC Research Platform encompasses the main cohort study, the Biobank and follow-up studies. Of the 8716 women approached at early prenatal clinics, 5108 were eligible and 2001 agreed to participate (39%). MIREC participants tended to smoke less (5.9% vs. 10.5%), be older (mean 32.2 vs. 29.4 years) and have a higher education (62.3% vs. 35.1% with a university degree) than women giving birth in Canada. The MIREC Study, while smaller in number of participants than several of the international cohort studies, has one of the most comprehensive datasets on prenatal exposure to multiple environmental chemicals. The biomonitoring data and biological specimen bank will make this research platform a significant resource for examining potential adverse health effects of prenatal exposure to environmental chemicals. © 2013 John Wiley & Sons Ltd and Her Majesty the Queen in Right of Canada. Reproduced with the permission of the Minister of Health.

Creating Meaningful Partnerships Between Communities and Environmental Health Researchers

PubMed Central

De Souza, Rachael; Aguilar, Genevieve C.; de Castro, A. B.

2014-01-01

Community engagement is a necessary, although challenging, element of environmental health research in communities. To facilitate the engagement process, direct action community organizing agencies can be useful in bringing together communities and researchers. This article describes the preliminary activities that one direct action community organizing agency used in partnership with researchers to improve community engagement in the first 6 months of an environmental health study conducted in a major U.S. city. Activities included developing communication strategies, creating opportunities for researcher–community interaction, and sustaining project momentum. To conduct environmental research that is both scientifically rigorous and relevant to communities, collaborating partners had to develop professional skills and strategies outside of their areas of expertise. PMID:23875568

Entanglement analysis of a two-atom nonlinear Jaynes-Cummings model with nondegenerate two-photon transition, Kerr nonlinearity, and two-mode Stark shift

NASA Astrophysics Data System (ADS)

Baghshahi, H. R.; Tavassoly, M. K.; Faghihi, M. J.

2014-12-01

An entangled state, as an essential tool in quantum information processing, may be generated through the interaction between light and matter in cavity quantum electrodynamics. In this paper, we study the interaction between two two-level atoms and a two-mode field in an optical cavity enclosed by a medium with Kerr nonlinearity in the presence of a detuning parameter and Stark effect. It is assumed that the atom-field coupling and third-order susceptibility of the Kerr medium depend on the intensity of the light. In order to investigate the dynamics of the introduced system, we obtain the exact analytical form of the state vector of the considered atom-field system under initial conditions which may be prepared for the atoms (in a coherent superposition of their ground and upper states) and the fields (in a standard coherent state). Then, in order to evaluate the degree of entanglement between the subsystems, we investigate the dynamics of the entanglement by employing the entanglement of formation. Finally, we analyze in detail the influences of the Stark shift, the deformed Kerr medium, the intensity-dependent coupling, and also the detuning parameter on the behavior of this measure for different subsystems. The numerical results show that the amount of entanglement between the different subsystems can be controlled by choosing the evolved parameters appropriately.

Ground Water Technical Support Center (GWTSC) Annual Report Fiscal Year 2015

EPA Science Inventory

The Ground Water Technical Support Center (GWTSC) is part of the Ground Water and Ecosystems Restoration Division (GWERD), which is based in the Robert S. Kerr Environmental Research Center in Ada, Oklahoma. The GWERD is a research division of U.S. EPA’s National Risk Management ...

Numerically solving the relativistic Grad-Shafranov equation in Kerr spacetimes: numerical techniques

NASA Astrophysics Data System (ADS)

Mahlmann, J. F.; Cerdá-Durán, P.; Aloy, M. A.

2018-07-01

The study of the electrodynamics of static, axisymmetric, and force-free Kerr magnetospheres relies vastly on solutions of the so-called relativistic Grad-Shafranov equation (GSE). Different numerical approaches to the solution of the GSE have been introduced in the literature, but none of them has been fully assessed from the numerical point of view in terms of efficiency and quality of the solutions found. We present a generalization of these algorithms and give a detailed background on the algorithmic implementation. We assess the numerical stability of the implemented algorithms and quantify the convergence of the presented methodology for the most established set-ups (split-monopole, paraboloidal, BH disc, uniform).

Control of Wave Propagation and Effect of Kerr Nonlinearity on Group Index

NASA Astrophysics Data System (ADS)

Hazrat, Ali; Ziauddin; Iftikhar, Ahmed

2013-07-01

We use four-level atomic system and control the wave propagation via forbidden decay rate. The Raman gain process becomes dominant on electromagnetically induced transparency (EIT) medium by increasing the forbidden decay rate via increasing the number of atoms [G.S. Agarwal and T.N. Dey, Phys. Rev. A 74 (2006) 043805 and K. Harada, T. Kanbashi, and M. Mitsunaga, Phys. Rev. A 73 (2006) 013803]. The behavior of wave propagation is dramatically changed from normal (subluminal) to anomalous (superluminal) dispersion by increasing the forbidden decay rate. The system can also give a control over the group velocity of the light propagating through the medium via Kerr field.

Numerically solving the relativistic Grad-Shafranov equation in Kerr spacetimes: Numerical techniques

NASA Astrophysics Data System (ADS)

Mahlmann, J. F.; Cerdá-Durán, P.; Aloy, M. A.

2018-04-01

The study of the electrodynamics of static, axisymmetric and force-free Kerr magnetospheres relies vastly on solutions of the so called relativistic Grad-Shafranov equation (GSE). Different numerical approaches to the solution of the GSE have been introduced in the literature, but none of them has been fully assessed from the numerical point of view in terms of efficiency and quality of the solutions found. We present a generalization of these algorithms and give detailed background on the algorithmic implementation. We assess the numerical stability of the implemented algorithms and quantify the convergence of the presented methodology for the most established setups (split-monopole, paraboloidal, BH-disk, uniform).

Phase Properties of Photon-Added Coherent States for Nonharmonic Oscillators in a Nonlinear Kerr Medium

NASA Astrophysics Data System (ADS)

Jahanbakhsh, F.; Honarasa, G.

2018-04-01

The potential of nonharmonic systems has several applications in the field of quantum physics. The photon-added coherent states for annharmonic oscillators in a nonlinear Kerr medium can be used to describe some quantum systems. In this paper, the phase properties of these states including number-phase Wigner distribution function, Pegg-Barnett phase distribution function, number-phase squeezing and number-phase entropic uncertainty relations are investigated. It is found that these states can be considered as the nonclassical states.

Realization of all-optical switch and diode via Raman gain process using a Kerr field

NASA Astrophysics Data System (ADS)

Abbas, Muqaddar; Qamar, Sajid; Qamar, Shahid

2016-08-01

The idea of optical photonic crystal, which is generated using two counter-propagating fields, is revisited to study gain-assisted all-optical switch and diode using Kerr field. Two counter-propagating fields with relative detuning Δ ν generate standing-wave field pattern which interacts with a four-level atomic system. The standing-wave field pattern acts like a static photonic crystal for Δ ν =0 , however, it behaves as a moving photonic crystal for Δ ν \

Kerr Reservoir LANDSAT experiment analysis for November 1980

NASA Technical Reports Server (NTRS)

Lecroy, S. R.

1982-01-01

An experiment was conducted on the waters of Kerr Reservoir to determine if reliable algorithms could be developed that relate water quality parameters to remotely sensed data. LANDSAT radiance data was used in the analysis since it is readily available and covers the area of interest on a regular basis. By properly designing the experiment, many of the unwanted variations due to atmosphere, solar, and hydraulic changes were minimized. The algorithms developed were constrained to satisfy rigorous statistical criteria before they could be considered dependable in predicting water quality parameters. A complete mix of different types of algorithms using the LANDSAT bands was generated to provide a thorough understanding of the relationships among the data involved. The study demonstrated that for the ranges measured, the algorithms that satisfactorily represented the data are mostly linear and only require a maximum of one or two LANDSAT bands. Rationing techniques did not improve the results since the initial design of the experiment minimized the errors that this procedure is effective against. Good correlations were established for inorganic suspended solids, iron, turbidity, and secchi depth.

Lessons learned from the Children's Environmental Exposure Research Study.

PubMed

Resnik, David B; Wing, Steven

2007-03-01

We examined 5 different ethical concerns about the Children's Environmental Exposure Research Study and make some recommendations for future studies of exposure to hazardous environmental agents in the home. Researchers should seek community consultation and participation; make participants aware of all the risks associated with the research, including hazards discovered in the home and uncertainties about the risks of agents under investigation; and take steps to ensure that their studies will not have unfair representation of the poor or people of color. Researchers should also avoid even the appearance of a financial conflict of interest in studies that are likely to be controversial and make it clear to all parties that studies will not intentionally expose subjects to hazardous environmental agents.

USEPA RESEARCH ACTIVITIES TO CHARACTERIZE CHILDREN'S ENVIRONMENTAL EXPOSURES

EPA Science Inventory

Given the vulnerability of children to effects from environmental exposures, understanding links between children's health and environmental exposures is critical. In recent years, significant research has been initiated at USEPA to characterize children's exposures.

NEESPI focus issues in Environmental Research Letters

NASA Astrophysics Data System (ADS)

Norman, Julian; Groisman, Pavel; Soja, Amber J.

2010-05-01

In 2007 and 2009 Environmental Research Letters published focus issues (edited by Pavel Groisman and Amber J Soja) made up of work carried out by NEESPI participants. Here, we present the content of those focus issues as an invaluable resource for researchers working in the NEESPI study area. The first of the two issues, published in 2007 with title 'Northern Hemisphere High Latitude Climate and Environmental Change', presents a diverse collection of articles that are assembled into five groups devoted to studies of climate and hydrology, land cover and land use, the biogeochemical cycle and its feedbacks, the cryosphere, and human dimensions. The second issue, published in 2009, with title 'Climatic and Environmental Change in Northern Eurasia' presents diverse, assorted studies of different aspects of contemporary change, representing the diversity of climates and ecosystems across Northern Eurasia.

40 CFR 18.10 - Appointment of Special Research Consultants for Environmental Protection.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 1 2011-07-01 2011-07-01 false Appointment of Special Research... PROTECTION AGENCY GENERAL ENVIRONMENTAL PROTECTION RESEARCH FELLOWSHIPS AND SPECIAL RESEARCH CONSULTANTS FOR ENVIRONMENTAL PROTECTION § 18.10 Appointment of Special Research Consultants for Environmental Protection. (a...

Grant-Funded Research in Environmental Economics

EPA Pesticide Factsheets

This database contains summaries of these awards, as well as project reports and publications, developed under environmental economics-related grants made by EPA's Office of Research and Development, NCEE and their partners since 1990.

Dynamics of oscillating relativistic tori around Kerr black holes

NASA Astrophysics Data System (ADS)

Zanotti, Olindo; Font, José A.; Rezzolla, Luciano; Montero, Pedro J.

2005-02-01

We present a comprehensive numerical study of the dynamics of relativistic axisymmetric accretion tori with a power-law distribution of specific angular momentum orbiting in the background space-time of a Kerr black hole. By combining general relativistic hydrodynamics simulations with a linear perturbative approach we investigate the main dynamical properties of these objects over a large parameter space. The astrophysical implications of our results extend and improve two interesting results that have been recently reported in the literature. First, the induced quasi-periodic variation of the mass quadrupole moment makes relativistic tori of nuclear matter densities, as those formed during the last stages of binary neutron star mergers, promising sources of gravitational radiation, potentially detectable by interferometric instruments. Secondly, p-mode oscillations in relativistic tori of low rest-mass densities could be used to explain high-frequency quasi-periodic oscillations observed in X-ray binaries containing a black hole candidate under conditions more generic than those considered so far.

Tilted Thick-Disk Accretion onto a Kerr Black Hole

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

Fragile, P C; Anninos, P

2003-12-12

We present the first results from fully general relativistic numerical studies of thick-disk accretion onto a rapidly-rotating (Kerr) black hole with a spin axis that is tilted (not aligned) with the angular momentum vector of the disk. We initialize the problem with the solution for an aligned, constant angular momentum, accreting thick disk around a black hole with spin a/M = J/M{sup 2} = +0.9 (prograde disk). The black hole is then instantaneously tilted, through a change in the metric, by an angle {beta}{sub 0}. In this Letter we report results with {beta}{sub 0} = 0, 15, and 30{sup o}.more » The disk is allowed to respond to the Lense-Thirring precession of the tilted black hole. We find that the disk settles into a quasi-static, twisted, warped configuration with Lense-Thirring precession dominating out to a radius analogous to the Bardeen-Petterson transition in tilted Keplerian disks.« less

Partnership of Environmental Education and Research-A compilation of student research, 1999-2008

USGS Publications Warehouse

Bradley, Michael W.; Armstrong, Patrice; Byl, Thomas D.

2011-01-01

The U.S. Geological Survey (USGS) Tennessee Water Science Center and the College of Engineering and Technology at Tennessee State University developed a Partnership in Environmental Education and Research (PEER) to support environmental research at TSU and to expand the environmental research capabilities of the USGS in Tennessee. The PEER program is driven by the research needs to better define the occurrence, fate, and transport of contaminants in groundwater and surface water. Research in the PEER program has primarily focused on the transport and remediation of organic contamination in karst settings. Research conducted through the program has also expanded to a variety of media and settings. Research areas include contaminant occurrence and transport, natural and enhanced bioremediation, geochemical conditions in karst aquifers, mathematical modeling for contaminant transport and degradation, new methods to evaluate groundwater contamination, the resuspension of bacteria from sediment in streams, the use of bioluminescence and chemiluminescence to identify the presence of contaminants, and contaminant remediation in wetlands. The PEER program has increased research and education opportunities for students in the College of Engineering, Technology, and Computer Science and has provided students with experience in presenting the results of their research. Students in the program have participated in state, regional, national and international conferences with more than 140 presentations since 1998 and more than 40 student awards. The PEER program also supports TSU outreach activities and efforts to increase minority participation in environmental and earth science programs at the undergraduate and graduate levels. TSU students and USGS staff participate in the TSU summer programs for elementary and high school students to promote earth sciences. The 2007 summer camps included more than 130 students from 20 different States and Washington DC.

LABORATORY SCALE STEAM INJECTION TREATABILITY STUDIES

EPA Science Inventory

Laboratory scale steam injection treatability studies were first developed at The University of California-Berkeley. A comparable testing facility has been developed at USEPA's Robert S. Kerr Environmental Research Center. Experience has already shown that many volatile organic...

Quantum dynamics of Kerr optical frequency combs below and above threshold: Spontaneous four-wave mixing, entanglement, and squeezed states of light

NASA Astrophysics Data System (ADS)

Chembo, Yanne K.

2016-03-01

The dynamical behavior of Kerr optical frequency combs is very well understood today from the perspective of the semiclassical approximation. These combs are obtained by pumping an ultrahigh-Q whispering-gallery mode resonator with a continuous-wave laser. The long-lifetime photons are trapped within the toruslike eigenmodes of the resonator, where they interact nonlinearly via the Kerr effect. In this article, we use quantum Langevin equations to provide a theoretical understanding of the nonclassical behavior of these combs when pumped below and above threshold. In the configuration where the system is under threshold, the pump field is the unique oscillating mode inside the resonator, and it triggers the phenomenon of spontaneous four-wave mixing, where two photons from the pump are symmetrically up- and down-converted in the Fourier domain. This phenomenon, also referred to as parametric fluorescence, can only be understood and analyzed from a fully quantum perspective as a consequence of the coupling between the field of the central (pumped) mode and the vacuum fluctuations of the various side modes. We analytically calculate the power spectra of the spontaneous emission noise, and we show that these spectra can be either single- or double-peaked depending on the value of the laser frequency, chromatic dispersion, pump power, and spectral distance between the central mode and the side mode of interest. We also calculate as well the overall spontaneous noise power per side mode and propose simplified analytical expressions for some particular cases. In the configuration where the system is pumped above threshold, we investigate the phenomena of quantum correlations and multimode squeezed states of light that can occur in the Kerr frequency combs originating from stimulated four-wave mixing. We show that for all stationary spatiotemporal patterns, the side modes that are symmetrical relative to the pumped mode in the frequency domain display quantum correlations

Hidden Symmetries of Euclideanised Kerr-NUT-(A)dS Metrics in Certain Scaling Limits

NASA Astrophysics Data System (ADS)

Visinescu, Mihai; Vîlcu, Eduard

2012-08-01

The hidden symmetries of higher dimensional Kerr-NUT-(A)dS metrics are investigated. In certain scaling limits these metrics are related to the Einstein-Sasaki ones. The complete set of Killing-Yano tensors of the Einstein-Sasaki spaces are presented. For this purpose the Killing forms of the Calabi-Yau cone over the Einstein-Sasaki manifold are constructed. Two new Killing forms on Einstein-Sasaki manifolds are identified associated with the complex volume form of the cone manifolds. Finally the Killing forms on mixed 3-Sasaki manifolds are briefly described.

Environmental futures research: experiences, approaches, and opportunities

Treesearch

David N., comp Bengston

2012-01-01

These papers, presented in a special session at the International Symposium on Society and Resource Management in June 2011, explore the transdisciplinary field of futures research and its application to long-range environmental analysis, planning, and policy. Futures research began in the post-World War II era and has emerged as a mature research field. Although the...

Environmental Science and Research Foundation annual technical report: Calendar year 1996

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

Morris, R.C.; Blew, R.D.

1997-07-01

This Annual Technical Report describes work conducted for the Department of Energy, Idaho Operations Office (DOE-ID), by the Environmental Science and Research Foundation (Foundation). The Foundation`s mission to DOE-ID provides support in several key areas. The authors conduct an environmental monitoring and surveillance program over an area covering much of the upper Snake River Plain, and provide environmental education and support services related to Idaho National Engineering and Environmental Laboratory (INEEL) natural resource issues. Also, the Foundation, with its University Affiliates, conducts ecological and radioecological research in the Idaho National Environmental Research Park. This research benefits major DOE-ID programs includingmore » Waste Management, Environmental Restoration, Spent Nuclear Fuels, and Land Management Issues. The major accomplishments of the Foundation and its University Affiliates during the calendar year 1996 are discussed.« less

Kerr electro-optic field mapping study of the effect of charge injection on the impulse breakdown strength of transformer oil

NASA Astrophysics Data System (ADS)

Zhang, X.; Zahn, M.

2013-10-01

The smart use of charge injection to improve breakdown strength in transformer oil is demonstrated in this paper. Hypothetically, bipolar homo-charge injection with reduced electric field at both electrodes may allow higher voltage operation without insulation failure, since electrical breakdown usually initiates at the electrode-dielectric interfaces. To find experimental evidence, the applicability and limitation of the hypothesis is first analyzed. Impulse breakdown tests and Kerr electro-optic field mapping measurements are then conducted with different combinations of parallel-plate aluminum and brass electrodes stressed by millisecond duration impulse. It is found that the breakdown voltage of brass anode and aluminum cathode is ˜50% higher than that of aluminum anode and brass cathode. This can be explained by charge injection patterns from Kerr measurements under a lower voltage, where aluminum and brass electrodes inject negative and positive charges, respectively. This work provides a feasible approach to investigating the effect of electrode material on breakdown strength.

NASA Integrated Systems Research with an Environmental Focus

NASA Technical Reports Server (NTRS)

Wolfe, Jean; Collier, Fay

2010-01-01

This slide presentation reviews the Integrated Systems Research Program (ISRP) with a focus on the work being done on reduction of environmental impact from aeronautics. The focus of the ISRP is to Conduct research at an integrated system-level on promising concepts and technologies and explore, assess, or demonstrate the benefits in a relevant environment. The presentation reviews the criteria for an ISRP project, and discusses the Environmentally Responsible Aviation (ERA) project, and the technical challenges.

Investigations of black-hole spectra: Purely-imaginary modes and Kerr ringdown radiation

NASA Astrophysics Data System (ADS)

Zalutskiy, Maxim P.

When black holes are perturbed they give rise to characteristic waves that propagate outwards carrying information about the black hole. In the linear regime these waves are described in terms of quasinormal modes (QNM). Studying QNM is an important topic which may provide a connection to the quantum theory of gravity in addition to their astrophysical applications. Quasinormal modes correspond to complex frequencies where the real part represents oscillation and the imaginary part represents damping. We have developed a new code for calculating QNM with high precision and accuracy, which we applied to the Schwarzschild and Kerr geometries. The high accuracy of our calculations was a significant improvement over prior work, allowing us to compute QNM much closer to the negative imaginary axis (NIA) than it was possible before. The existence of QNM on the NIA has remained poorly understood, but our high accuracy studies have highlighted the importance of understanding their nature. In this work we show how the purely-imaginary modes can be calculated with the help of the theory of confluent Heun polynomials with the conclusion that all modes on the NIA correspond to polynomial solutions. We also show that certain types of these modes correspond to Kerr QNM. Finally, using our highly accurate QNM data we model the ringdown, a remnant black hole's decaying radiation. Ringdown occurs in the final stages of such violent astrophysical events as supernovae and black hole collisions. We use our model to analyse the ringdown waveforms from the publicly available binary black hole coalescence catalog maintained by the SXS collaboration. In our analysis we use a number of methods: Fourier transform, multi-mode nonlinear fitting and waveform overlap. Both our fitting and overlap approach allow inclusion of many modes in the ringdown model with the goal being to extract information about the nature of the astrophysical source of the ringdown signal.

Twelfth International Symposium on Recent Advances in Environmental Health Research.

PubMed

Tchounwou, Paul B

2016-05-04

During the past century, environmental hazards have become a major concern, not only to public health professionals, but also to the society at large because of their tremendous health, socio-cultural and economic impacts. Various anthropogenic or natural factors have been implicated in the alteration of ecosystem integrity, as well as in the development of a wide variety of acute and/or chronic diseases in humans. It has also been demonstrated that many environmental agents, acting either independently or in combination with other toxins, may induce a wide range of adverse health outcomes. Understanding the role played by the environment in the etiology of human diseases is critical to designing cost-effective control/prevention measures. This special issue of International Journal of Environmental Research and Public Health includes the proceedings of the Twelfth International Symposium on Recent Advances in Environmental Health Research. The Symposium provided an excellent opportunity to discuss the scientific advances in biomedical, environmental, and public health research that addresses global environmental health issues.

UMBC CENTER FOR URBAN ENVIRONMENTAL RESEARCH AND EDUCATION

EPA Science Inventory

This was a multi-year project to establish the Center for Urban Environmental Research and Education (CUERE) at UMBC. The Center was founded to advance understanding of the environmental, social and economic consequences of changes to the urban and suburban landscape.

Environmental Education Policy Research--Challenges and Ways Research Might Cope with Them

ERIC Educational Resources Information Center

Laessoe, Jeppe; Feinstein, Noah Weeth; Blum, Nicole

2013-01-01

This essay examines the relationship between research and policy and, more specifically, how researchers might relate to policy work. Given the current international policy focus on climate change, green growth and sustainability in general, it argues for strengthening and widening policy research in the areas of Environmental Education (EE),…

Environmental research program. 1995 Annual report

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

Brown, N.J.

1996-06-01

The objective of the Environmental Research Program is to enhance the understanding of, and mitigate the effects of pollutants on health, ecological systems, global and regional climate, and air quality. The program is multidisciplinary and includes fundamental research and development in efficient and environmentally benign combustion, pollutant abatement and destruction, and novel methods of detection and analysis of criteria and noncriteria pollutants. This diverse group conducts investigations in combustion, atmospheric and marine processes, flue-gas chemistry, and ecological systems. Combustion chemistry research emphasizes modeling at microscopic and macroscopic scales. At the microscopic scale, functional sensitivity analysis is used to explore themore » nature of the potential-to-dynamics relationships for reacting systems. Rate coefficients are estimated using quantum dynamics and path integral approaches. At the macroscopic level, combustion processes are modelled using chemical mechanisms at the appropriate level of detail dictated by the requirements of predicting particular aspects of combustion behavior. Parallel computing has facilitated the efforts to use detailed chemistry in models of turbulent reacting flow to predict minor species concentrations.« less

Toward sustainable environmental quality: Identifying priority research questions for Latin America.

PubMed

Furley, Tatiana Heid; Brodeur, Julie; Silva de Assis, Helena C; Carriquiriborde, Pedro; Chagas, Katia R; Corrales, Jone; Denadai, Marina; Fuchs, Julio; Mascarenhas, Renata; Miglioranza, Karina Sb; Miguez Caramés, Diana Margarita; Navas, José Maria; Nugegoda, Dayanthi; Planes, Estela; Rodriguez-Jorquera, Ignacio Alejandro; Orozco-Medina, Martha; Boxall, Alistair Ba; Rudd, Murray A; Brooks, Bryan W

2018-05-01

The Global Horizon Scanning Project (GHSP) is an innovative initiative that aims to identify important global environmental quality research needs. Here we report 20 key research questions from Latin America (LA). Members of the Society of Environmental Toxicology and Chemistry (SETAC) LA and other scientists from LA were asked to submit research questions that would represent priority needs to address in the region. One hundred questions were received, then partitioned among categories, examined, and some rearranged during a workshop in Buenos Aires, Argentina. Twenty priority research questions were subsequently identified. These research questions included developing, improving, and harmonizing across LA countries methods for 1) identifying contaminants and degradation products in complex matrices (including biota); 2) advancing prediction of contaminant risks and effects in ecosystems, addressing lab-to-field extrapolation challenges, and understanding complexities of multiple stressors (including chemicals and climate change); and 3) improving management and regulatory tools toward achieving sustainable development. Whereas environmental contaminants frequently identified in these key questions were pesticides, pharmaceuticals, endocrine disruptors or modulators, plastics, and nanomaterials, commonly identified environmental challenges were related to agriculture, urban effluents, solid wastes, pulp and paper mills, and natural extraction activities. Several interesting research topics included assessing and preventing pollution impacts on conservation protected areas, integrating environment and health assessments, and developing strategies for identification, substitution, and design of less hazardous chemicals (e.g., green chemistry). Finally, a recurrent research need included developing an understanding of differential sensitivity of regional species and ecosystems to environmental contaminants and other stressors. Addressing these critical questions will

Environmental Science and Research Foundation, Inc. annual technical report: Calendar year 1997

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

Reynolds, R.D.; Warren, R.W.

This Annual Technical Report describes work conducted for the Department of Energy, Idaho Operations Office (DOE-ID), by the Environmental Science and Research Foundation (Foundation). The Foundation`s mission to DOE-ID provides support in several key areas. The Foundation conducts an environmental monitoring and surveillance program over an area covering much of the upper Snake River Plain, and provides environmental education and support services related to Idaho National Engineering and Environmental Laboratory (INEEL) natural resource issues. Also, the Foundation, with its University Affiliates, conducts ecological and radioecological research on the Idaho National Environmental Research Park. This research benefits major DOE-ID programs includingmore » Waste Management, Environmental Restoration, Spent Nuclear Fuels, and Land Management Issues. Summaries are included of the individual research projects.« less

NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LABORATORY - ACCOMPLISHMENTS FOR FY 2001

EPA Science Inventory

This Annual Report showcases some of the scientific activities of the National Health and Environmental Effects Research Laboratory (NHEERL) in various health and environmental effects research areas. Where appropriate, the contributions of other collaborating research organizat...

Scalar self-force for highly eccentric equatorial orbits in Kerr spacetime

NASA Astrophysics Data System (ADS)

Thornburg, Jonathan; Wardell, Barry

2017-04-01

If a small "particle" of mass μ M (with μ ≪1 ) orbits a black hole of mass M , the leading-order radiation-reaction effect is an O (μ2) "self-force" acting on the particle, with a corresponding O (μ ) "self-acceleration" of the particle away from a geodesic. Such "extreme-mass-ratio inspiral" systems are likely to be important gravitational-wave sources for future space-based gravitational-wave detectors. Here we consider the "toy model" problem of computing the self-force for a scalar-field particle on a bound eccentric orbit in Kerr spacetime. We use the Barack-Golbourn-Vega-Detweiler effective-source regularization with a 4th-order puncture field, followed by an ei m ϕ ("m -mode") Fourier decomposition and a separate time-domain numerical evolution in 2 +1 dimensions for each m . We introduce a finite worldtube that surrounds the particle worldline and define our evolution equations in a piecewise manner so that the effective source is only used within the worldtube. Viewed as a spatial region, the worldtube moves to follow the particle's orbital motion. We use slices of constant Boyer-Lindquist time in the region of the particle's motion, deformed to be asymptotically hyperboloidal and compactified near the horizon and J+ . Our numerical evolution uses Berger-Oliger mesh refinement with 4th-order finite differencing in space and time. Our computational scheme allows computation for highly eccentric orbits and should be generalizable to orbital evolution in the future. Our present implementation is restricted to equatorial geodesic orbits, but this restriction is not fundamental. We present numerical results for a number of test cases with orbital eccentricities as high as 0.98. In some cases we find large oscillations ("wiggles") in the self-force on the outgoing leg of the orbit shortly after periastron passage; these appear to be caused by the passage of the orbit through the strong-field region close to the background Kerr black hole.

40 CFR 18.10 - Appointment of Special Research Consultants for Environmental Protection.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) Purpose. When the EPA requires the services of consultants with expertise in environmental sciences or... Consultants for Environmental Protection. 18.10 Section 18.10 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GENERAL ENVIRONMENTAL PROTECTION RESEARCH FELLOWSHIPS AND SPECIAL RESEARCH CONSULTANTS FOR...

40 CFR 18.10 - Appointment of Special Research Consultants for Environmental Protection.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) Purpose. When the EPA requires the services of consultants with expertise in environmental sciences or... Consultants for Environmental Protection. 18.10 Section 18.10 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GENERAL ENVIRONMENTAL PROTECTION RESEARCH FELLOWSHIPS AND SPECIAL RESEARCH CONSULTANTS FOR...

40 CFR 18.10 - Appointment of Special Research Consultants for Environmental Protection.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) Purpose. When the EPA requires the services of consultants with expertise in environmental sciences or... Consultants for Environmental Protection. 18.10 Section 18.10 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GENERAL ENVIRONMENTAL PROTECTION RESEARCH FELLOWSHIPS AND SPECIAL RESEARCH CONSULTANTS FOR...

Enhanced magneto-optical Kerr effect in rare earth substituted nanostructured cobalt ferrite thin film prepared by sol-gel method

NASA Astrophysics Data System (ADS)

Avazpour, L.; Toroghinejad, M. R.; Shokrollahi, H.

2016-11-01

A series of rare-earth (RE)-doped nanocrystalline Cox RE(1-x) Fe2O4 (x = 0, 0.1, 0.2 and RE: Nd, Eu) thin films were prepared on silicon substrates by a sol-gel process, and the influences of different RE3+ ions on the microstructure, magnetism and polar magneto-optical Kerr effect of the deposited films were investigated. Also this research presents the optimization process of cobalt ferrite thin films deposited via spin coating, by studying their structural and morphological properties at different thicknesses (200, 350 nm) and various heat treatment temperatures 300-850 °C. Nanoparticulate polycrystalline thin film were formed with heat treatment above 400 °C but proper magnetic properties due to well crystallization of the film were achieved at about 650 °C. AFM results indicated that the deposited thin films were crack-free exhibiting a dense nanogranular structure. The root-mean square (RMS) roughness of the thin films was in the range of 0.2-3.2 nm. The results revealed that both of the magnetism and magneto optical Kerr (MOKE) spectra of Cox RE(1-x) Fe2O4 films could be mediated by doping with various RE ions. The Curie temperature of substituted samples was lower than pristine cobalt ferrite thin films. In MOKE spectra both dominant peaks were blue shifted with addition of RE ions. For low concentration dopant the inter-valence charge transfer related rotation was enhanced and for higher concentration dopant the crystal field rotation peak was enhanced. The MOKE enhancement for Eu3+ substituted samples was more than Nd3+ doped cobalt ferrite films. The enhanced MOKEs in nanocrystalline thin films might promise their applications for magneto-optical sensors in adopted wavelengths.

RESEARCH PROGRAMS AT THE ECOSYSTEMS RESEARCH DIVISION, U.S. ENVIRONMENTAL PROTECTION AGENCY

EPA Science Inventory

This presentation presents information on the research programs at the Ecosystems Research Division (ERD) of the U.S. Environmental Protection Agency located in Athens, Georgia. The presentation gives an overview of the Agency, laws and regulations that the Agency operates under,...

Environmental Pollution, A Guide to Current Research.

ERIC Educational Resources Information Center

Smithsonian Institution, Washington, DC. Science Information Exchange.

Compiled from data gathered in fiscal years 1969 and 1970 by the Science Information Exchange, Smithsonian Institution, this inventory of more than 4200 federally and non-federally supported environmental research projects represents an attempt to provide a meaningful look at the shape, complexity, and direction of current and recent research.…

High spectral purity Kerr frequency comb radio frequency photonic oscillator

PubMed Central

Liang, W.; Eliyahu, D.; Ilchenko, V. S.; Savchenkov, A. A.; Matsko, A. B.; Seidel, D.; Maleki, L.

2015-01-01

Femtosecond laser-based generation of radio frequency signals has produced astonishing improvements in achievable spectral purity, one of the basic features characterizing the performance of an radio frequency oscillator. Kerr frequency combs hold promise for transforming these lab-scale oscillators to chip-scale level. In this work we demonstrate a miniature 10 GHz radio frequency photonic oscillator characterized with phase noise better than −60 dBc Hz−1 at 10 Hz, −90 dBc Hz−1 at 100 Hz and −170 dBc Hz−1 at 10 MHz. The frequency stability of this device, as represented by Allan deviation measurements, is at the level of 10−10 at 1–100 s integration time—orders of magnitude better than existing radio frequency photonic devices of similar size, weight and power consumption. PMID:26260955

Observing the contour profile of a Kerr-Sen black hole

NASA Astrophysics Data System (ADS)

Lan, X. G.; Pu, J.

2018-06-01

In this paper, the shadow and the corresponding naked singularity cast by a Kerr-Sen black hole are studied. It is found that the shadow of a rotating black hole would be a dark zone surrounded by a deformed circle, and the shadow is distorted more away from a circle when the black hole approaches the extremal case. Besides, it is shown that the mean radius of the shadow decreases and distortion parameter increases with the increasing of charge, respectively. However, the mean radius and the distortion parameter vary complicatedly with the change of spin parameter. In the beginning, both observables decrease rapidly with the increasing of specific angular momentum, nevertheless, they increase slightly in the latter part. These results show that there would be a significant effect of the spin on the shadows, which would be of great importance for probing the nature of the black hole.

Research on environmental impact of water-based fire extinguishing agents

NASA Astrophysics Data System (ADS)

Wang, Shuai

2018-02-01

This paper offers current status of application of water-based fire extinguishing agents, the environmental and research considerations of the need for the study of toxicity research. This paper also offers systematic review of test methods of toxicity and environmental impact of water-based fire extinguishing agents currently available, illustrate the main requirements and relevant test methods, and offer some research findings for future research considerations. The paper also offers limitations of current study.

The not-for-profit form and translational research: Kerr revisited?

PubMed Central

Joiner, Keith A

2005-01-01

Translational research conducted in academic health centers is confounded by the organizational structure in which the work is performed. Investigators must obtain research funding and appropriate recognition as a part of a research team in a not-for-profit environment which has more readily rewarded basic work, and individual accomplishments. What results is a unique form of conflict of interest, best understood by relating the basic principles underlying the not-for-profit form to the conduct of translational research in the AHC setting. PMID:15862130

What is the longitudinal magneto-optical Kerr effect?

NASA Astrophysics Data System (ADS)

Ander Arregi, Jon; Riego, Patricia; Berger, Andreas

2017-01-01

We explore the commonly used classification scheme for the magneto-optical Kerr effect (MOKE), which essentially utilizes a dual definition based simultaneously on the Cartesian coordinate components of the magnetization vector with respect to the plane of incidence reference frame and specific elements of the reflection matrix, which describes light reflection from a ferromagnetic surface. We find that an unambiguous correspondence in between reflection matrix elements and magnetization components is valid only in special cases, while in more general cases, it leads to inconsistencies due to an intermixing of the presumed separate effects of longitudinal, transverse and polar MOKE. As an example, we investigate in this work both theoretically and experimentally a material that possesses anisotropic magneto-optical properties in accordance with its crystal symmetry. The derived equations, which specifically predict a so-far unknown polarization effect for the transverse magnetization component, are confirmed by detailed experiments on epitaxial hcp Co films. The results indicate that magneto-optical anisotropy causes significant deviations from the commonly employed MOKE data interpretation. Our work addresses the associated anomalies, provides a suitable analysis route for reliable MOKE magnetometry procedures, and proposes a revised MOKE terminology scheme.

Infinite efficiency of the collisional Penrose process: Can a overspinning Kerr geometry be the source of ultrahigh-energy cosmic rays and neutrinos?

NASA Astrophysics Data System (ADS)

Patil, Mandar; Harada, Tomohiro; Nakao, Ken-ichi; Joshi, Pankaj S.; Kimura, Masashi

2016-05-01

The origin of the ultrahigh-energy particles we receive on Earth from outer space such as EeV cosmic rays and PeV neutrinos remains an enigma. All mechanisms known to us currently make use of electromagnetic interaction to accelerate charged particles. In this paper, we propose a mechanism exclusively based on gravity rather than electromagnetic interaction. We show that it is possible to generate ultrahigh-energy particles starting from particles with moderate energies using the collisional Penrose process in an overspinning Kerr spacetime transcending the Kerr bound only by an infinitesimal amount, i.e., with the Kerr parameter a =M (1 +ɛ ) , where we take the limit ɛ →0+. We consider two massive particles starting from rest at infinity that collide at r =M with divergent center-of-mass energy and produce two massless particles. We show that massless particles produced in the collision can escape to infinity with the ultrahigh energies exploiting the collisional Penrose process with the divergent efficiency η ˜1 /√{ɛ }→∞ . Assuming the isotropic emission of massless particles in the center-of-mass frame of the colliding particles, we show that half of the particles created in the collisions escape to infinity with the divergent energies, while the proportion of particles that reach infinity with finite energy is minuscule. To a distant observer, ultrahigh-energy particles appear to originate from a bright spot which is at the angular location ξ ˜2 M /robs with respect to the singularity on the side which is rotating toward the observer. We compute the spectrum of the high-energy massless particles and show that anisotropy in the emission in the center-of-mass frame leaves a distinct signature on its shape. Since the anisotropy is dictated by the differential cross section of the underlying particle physics process, the observation of the spectrum can constrain the particle physics model and serve as a unique probe into fundamental physics at

Reintroducing Environmental Change Drivers in Biodiversity-Ecosystem Functioning Research.

PubMed

De Laender, Frederik; Rohr, Jason R; Ashauer, Roman; Baird, Donald J; Berger, Uta; Eisenhauer, Nico; Grimm, Volker; Hommen, Udo; Maltby, Lorraine; Meliàn, Carlos J; Pomati, Francesco; Roessink, Ivo; Radchuk, Viktoriia; Van den Brink, Paul J

2016-12-01

For the past 20 years, research on biodiversity and ecosystem functioning (B-EF) has only implicitly considered the underlying role of environmental change. We illustrate that explicitly reintroducing environmental change drivers in B-EF research is needed to predict the functioning of ecosystems facing changes in biodiversity. Next we show how this reintroduction improves experimental control over community composition and structure, which helps to provide mechanistic insight on how multiple aspects of biodiversity relate to function and how biodiversity and function relate in food webs. We also highlight challenges for the proposed reintroduction and suggest analyses and experiments to better understand how random biodiversity changes, as studied by classic approaches in B-EF research, contribute to the shifts in function that follow environmental change. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Jupiter Environmental Research & Field Studies Academy.

ERIC Educational Resources Information Center

Huttemeyer, Bob

1996-01-01

Describes the development and workings of the Jupiter Environmental Research and Field Studies Academy that focuses on enabling both teachers and students to participate in real-life learning experiences. Discusses qualifications for admittance, curriculum, location, ongoing projects, students, academics, preparation for life, problem solving, and…

Towards a joint approach for access to environmental research infrastructures

NASA Astrophysics Data System (ADS)

Mann, Ingrid; Tjulin, Anders; Pappalardo, Gelsomina; Gagliardi, Simone; Philippin, Sabine; Sellegri, Karine; Chabbi, Abad

2016-04-01

Geoscience is a multi-disciplinary field and in many cases its research benefits from considering different kinds of observational results. Geoscience observations are in some cases of direct interest also to the public. For these reasons effective knowledge transfer and access also across disciplines are especially important for research infrastructures (RIs) in the environmental domain. More generally, the ultimate success of a RI is measured by its scientific outcome and this is best achieved based on efficient access for a broad scientific community. In this presentation the authors report activities to develop governance tools so that the access to environmental RIs and to the data that they provide is common, fair and based on scientific rationale, regarding at the same time economically and technically reasonable use of limited resources. Implementing such governance tools will indeed foster and widen the access to RIs across environmental science domains while addressing societal challenges. The strategies also need to be flexible and sustainable over the expected lifetimes of the RIs. The reported activities involve researchers from different projects and environmental subdomains that come together in the project ENVRI_plus. ENVRI_plus is a Cluster project of RIs that brings together the current ESFRI roadmap RIs in the environmental domain and other relevant existing and developing RIs and projects. ENVRI_plus also offers opportunities for free-of-charge transnational access to four multi-disciplinary research platforms. These calls for access target research groups and companies wishing to conduct research or to test instruments for cross-disciplinary topics within the environmental domains atmosphere, biosphere, marine, and solid earth. They are initiated specifically to gain experience with access across different disciplines (further information is given at www.envriplus.eu). ENVRI_plus receives funding from the European Union's Horizon 2020 research

Lessons Learned From the Children’s Environmental Exposure Research Study

PubMed Central

Resnik, David B.; Wing, Steven

2007-01-01

We examined 5 different ethical concerns about the Children’s Environmental Exposure Research Study and make some recommendations for future studies of exposure to hazardous environmental agents in the home. Researchers should seek community consultation and participation; make participants aware of all the risks associated with the research, including hazards discovered in the home and uncertainties about the risks of agents under investigation; and take steps to ensure that their studies will not have unfair representation of the poor or people of color. Researchers should also avoid even the appearance of a financial conflict of interest in studies that are likely to be controversial and make it clear to all parties that studies will not intentionally expose subjects to hazardous environmental agents. PMID:17267718

Health and Environmental Research: Summary of Accomplishments. Volume 2

DOE R&D Accomplishments Database

1986-08-01

This is an account of some of the accomplishments of the health and environmental research program performed in national laboratories, universities, and research institutes. Both direct and indirect societal benefits emerged from the new knowledge provided by the health and environmental research program. In many cases, the private sector took this knowledge and applied it well beyond the mission of supporting the defense and energy needs of the Nation. Industrial and medical applications, for example, have in several instances provided annual savings to society of $100 million or more. The form of this presentation is, in fact, through "snapshots" - examples of significant, tangible accomplishments in each of the areas at certain times to illustrate the role and impact of the research program. The program's worth is not necessarily confined to such accomplishments; it extends, rather, to its ability to identify and help solve potential health and environmental problems before they become critical. This anticipatory mission has been pursued with an approach that combines applied problem solving with a commitment to fundamental research that is long-term and high-risk. The narrative of this research program concludes with a perspective of its past and a prospectus on its future.

Tales from Camp Wilde: Queer(y)ing Environmental Education Research

ERIC Educational Resources Information Center

Gough, Noel; Gough, Annette

2003-01-01

This paper questions the relative silence of queer theory and theorizing in environmental education research. We explore some possibilities for queering environmental education research by fabricating (and inviting colleagues to fabricate) stories of Camp Wilde, a fictional location that helps us to expose the facticity of the field's…

Femtosecond pulse self-shortening in Kerr media: role of modulational instability in the spectrum formation

NASA Astrophysics Data System (ADS)

Grudtsyn, Ya. V.; Koribut, A. V.; Mikheev, L. D.; Trofimov, V. A.

2018-04-01

The mechanism of femtosecond pulse self-shortening in thin optical materials with Kerr nonlinearity is investigated. The experimentally observed spectral-angular distribution of the radiation intensity on the exit surface of a 1-mm-thick fused silica sample is compared with the results of numerical simulation based on solving the nonlinear Schrödinger equation for an electromagnetic wave with a transverse perturbation on the axis. Qualitative agreement between the calculated and experimental results confirms the hypothesis about the transient regime of multiple filamentation as a mechanism of femtosecond pulse self-shortening.

Spinning boson stars and Kerr black holes with scalar hair: The effect of self-interactions

NASA Astrophysics Data System (ADS)

Herdeiro, Carlos A. R.; Radu, Eugen; Rúnarsson, Helgi F.

2016-05-01

Self-interacting boson stars (BSs) have been shown to alleviate the astrophysically low maximal mass of their nonself-interacting counterparts. We report some physical features of spinning self-interacting BSs, namely their compactness, the occurrence of ergo-regions and the scalar field profiles, for a sample of values of the coupling parameter. The results agree with the general picture that these BSs are comparatively less compact than the nonself-interacting ones. We also briefly discuss the effect of scalar self-interactions on the properties of Kerr black holes with scalar hair.

Assessing the benefits of OHER (Office of Health and Environmental Research) research: Three case studies

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

Nesse, R.J.; Callaway, J.M.; Englin, J.E.

1987-09-01

This research was undertaken to estimate the societal benefits and costs of selected past research performed for the Office of Health and Environmental Research (OHER) of the US Department of Energy (DOE). Three case studies of representative OHER and DOE research were performed. One of these, the acid rain case study, includes research conducted elsewhere in DOE. The other two cases were the OHER marine research program and the development of high-purity germanium that is used in radiation detectors. The acid rain case study looked at the research benefits and costs of furnace sorbent injection and duct injection, technologies thatmore » might reduce acid deposition precursors. Both appear to show benefits in excess of costs. We examined in detail one of the OHER marine research program's accomplishments - the increase in environmental information used by the Outer Continental Shelf leasing program to manage bidding for off-shore oil drilling. The results of an econometric model show that environmental information of the type supported by OHER is unequivocally linked to government and industry leasing decisions. The germanium case study indicated that the benefits of germanium radiation detectors were significant.« less

Environmental Research Guidance Committee annual report

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

Not Available

1982-01-01

Section 3-303 of the Natural Resources Article of the Annotated Code of Maryland (1973 Volume) provides for a Power Plant Environmental Research Program to be administered by the Secretary of Natural Resources in cooperation with the Secretaries of Health and Mental Hygiene, Agriculture, State Planning, Economic and Community Development, and Electric Company representatives. In order to carry out this provision of the law, the Power Plant Siting Program requested the Scientific Council of the Maryland Academy of Sciences to establish an Environmental Research Guidance Committee (ERGC) in June, 1973. The ERGC is divided into 4 subcommittees designated Biological Effects (impactmore » of power plants on aquatic and terrestrial ecosystems), Aquatic and Terrestrial (transport and chemical interactions of materials discharged into aquatic and terrestrial environments), Atmospheric (transport and chemical interactions of atmospheric emissions and their impacts on the environment), and Socioeconomic (effects of power plants on the social and economic structure of the State).« less

Environmental health capacity-building: Examples from EPA’s National Center for Environmental Research Grants Program

EPA Science Inventory

NCER’s environmental health research funding to academic institutions and non-profit entities have supported EPA’s mission to protect human health and the environment, while also supporting capacity-building in communities in understanding and mitigating environmental...

Toward sustainable environmental quality: Identifying priority research questions for Latin America

PubMed Central

Furley, Tatiana Heid; Brodeur, Julie; Silva de Assis, Helena C; Carriquiriborde, Pedro; Chagas, Katia R; Corrales, Jone; Denadai, Marina; Fuchs, Julio; Mascarenhas, Renata; Miglioranza, Karina SB; Miguez Caramés, Diana Margarita; Navas, José Maria; Nugegoda, Dayanthi; Planes, Estela; Rodriguez‐Jorquera, Ignacio Alejandro; Orozco‐Medina, Martha; Boxall, Alistair BA; Rudd, Murray A

2018-01-01

ABSTRACT The Global Horizon Scanning Project (GHSP) is an innovative initiative that aims to identify important global environmental quality research needs. Here we report 20 key research questions from Latin America (LA). Members of the Society of Environmental Toxicology and Chemistry (SETAC) LA and other scientists from LA were asked to submit research questions that would represent priority needs to address in the region. One hundred questions were received, then partitioned among categories, examined, and some rearranged during a workshop in Buenos Aires, Argentina. Twenty priority research questions were subsequently identified. These research questions included developing, improving, and harmonizing across LA countries methods for 1) identifying contaminants and degradation products in complex matrices (including biota); 2) advancing prediction of contaminant risks and effects in ecosystems, addressing lab‐to‐field extrapolation challenges, and understanding complexities of multiple stressors (including chemicals and climate change); and 3) improving management and regulatory tools toward achieving sustainable development. Whereas environmental contaminants frequently identified in these key questions were pesticides, pharmaceuticals, endocrine disruptors or modulators, plastics, and nanomaterials, commonly identified environmental challenges were related to agriculture, urban effluents, solid wastes, pulp and paper mills, and natural extraction activities. Several interesting research topics included assessing and preventing pollution impacts on conservation protected areas, integrating environment and health assessments, and developing strategies for identification, substitution, and design of less hazardous chemicals (e.g., green chemistry). Finally, a recurrent research need included developing an understanding of differential sensitivity of regional species and ecosystems to environmental contaminants and other stressors. Addressing these critical

Resonant magneto-optic Kerr effect in the magnetic topological insulator Cr:(Sb x,Bi 1–x) 2Te 3

DOE PAGES

Patankar, Shreyas; Hinton, J. P.; Griesmar, Joel; ...

2015-12-31

Here, we report measurements of the polar Kerr effect, proportional to the out-of-plane component of the magnetization, in thin films of the magnetically doped topological insulator (Cr 0.12Bi 0.26Sb 0.62) 2Te 3. Measurements of the complex Kerr angle ΘK were performed as a function of photon energy in the range 0.8eV < ℏω < 3.0eV. We observed a peak in the real part of Θ K(ω) and zero crossing in the imaginary part that we attribute to a resonant interaction with a spin-orbit avoided crossing located ≈ 1.6 eV above the Fermi energy. The resonant enhancement allows measurement of themore » temperature and magnetic field dependence of Θ K in the ultrathin film limit, d ≥ 2 quintuple layers (QL). We find a sharp transition to zero remanent magnetization at 6 K for d < 8 QL, consistent with theories of the dependence of impurity spin interactions on film thickness and their location relative to topological insulator surfaces.« less

Mach-Zehnder interferometer implementation for thermo-optical and Kerr effect study

NASA Astrophysics Data System (ADS)

Bundulis, Arturs; Nitiss, Edgars; Busenbergs, Janis; Rutkis, Martins

2018-04-01

In this paper, we propose the Mach-Zehnder interferometric method for third-order nonlinear optical and thermo-optical studies. Both effects manifest themselves as refractive index dependence on the incident light intensity and are widely employed for multiple opto-optical and thermo-optical applications. With the implemented method, we have measured the Kerr and thermo-optical coefficients of chloroform under CW, ns and ps laser irradiance. The application of lasers with different light wavelengths, pulse duration and energy allowed us to distinguish the processes responsible for refractive index changes in the investigated solution. Presented setup was also used for demonstration of opto-optical switching. Results from Mach-Zehnder experiment were compared to Z-scan data obtained in our previous studies. Based on this, a quality comparison of both methods was assessed and advantages and disadvantages of each method were analyzed.

APPLIED OPTICS. Overcoming Kerr-induced capacity limit in optical fiber transmission.

PubMed

Temprana, E; Myslivets, E; Kuo, B P-P; Liu, L; Ataie, V; Alic, N; Radic, S

2015-06-26

Nonlinear optical response of silica imposes a fundamental limit on the information transfer capacity in optical fibers. Communication beyond this limit requires higher signal power and suppression of nonlinear distortions to prevent irreversible information loss. The nonlinear interaction in silica is a deterministic phenomenon that can, in principle, be completely reversed. However, attempts to remove the effects of nonlinear propagation have led to only modest improvements, and the precise physical mechanism preventing nonlinear cancellation remains unknown. We demonstrate that optical carrier stability plays a critical role in canceling Kerr-induced distortions and that nonlinear wave interaction in silica can be substantially reverted if optical carriers possess a sufficient degree of mutual coherence. These measurements indicate that fiber information capacity can be notably increased over previous estimates. Copyright © 2015, American Association for the Advancement of Science.

Characterization of (asymptotically) Kerr-de Sitter-like spacetimes at null infinity

NASA Astrophysics Data System (ADS)

Mars, Marc; Paetz, Tim-Torben; Senovilla, José M. M.; Simon, Walter

2016-08-01

We investigate solutions ({M},g) to Einstein's vacuum field equations with positive cosmological constant Λ which admit a smooth past null infinity {{I}}- à la Penrose and a Killing vector field whose associated Mars-Simon tensor (MST) vanishes. The main purpose of this work is to provide a characterization of these spacetimes in terms of their Cauchy data on {{I}}-. Along the way, we also study spacetimes for which the MST does not vanish. In that case there is an ambiguity in its definition which is captured by a scalar function Q. We analyze properties of the MST for different choices of Q. In doing so, we are led to a definition of ‘asymptotically Kerr-de Sitter-like spacetimes’, which we also characterize in terms of their asymptotic data on {{I}}-. Preprint UWThPh-2016-5.

Multi-Contextual Segregation and Environmental Justice Research: Toward Fine-Scale Spatiotemporal Approaches

PubMed Central

Park, Yoo Min; Kwan, Mei-Po

2017-01-01

Many environmental justice studies have sought to examine the effect of residential segregation on unequal exposure to environmental factors among different social groups, but little is known about how segregation in non-residential contexts affects such disparity. Based on a review of the relevant literature, this paper discusses the limitations of traditional residence-based approaches in examining the association between socioeconomic or racial/ethnic segregation and unequal environmental exposure in environmental justice research. It emphasizes that future research needs to go beyond residential segregation by considering the full spectrum of segregation experienced by people in various geographic and temporal contexts of everyday life. Along with this comprehensive understanding of segregation, the paper also highlights the importance of assessing environmental exposure at a high spatiotemporal resolution in environmental justice research. The successful integration of a comprehensive concept of segregation, high-resolution data and fine-grained spatiotemporal approaches to assessing segregation and environmental exposure would provide more nuanced and robust findings on the associations between segregation and disparities in environmental exposure and their health impacts. Moreover, it would also contribute to significantly expanding the scope of environmental justice research. PMID:28994744

Multi-Contextual Segregation and Environmental Justice Research: Toward Fine-Scale Spatiotemporal Approaches.

PubMed

Park, Yoo Min; Kwan, Mei-Po

2017-10-10

Many environmental justice studies have sought to examine the effect of residential segregation on unequal exposure to environmental factors among different social groups, but little is known about how segregation in non-residential contexts affects such disparity. Based on a review of the relevant literature, this paper discusses the limitations of traditional residence-based approaches in examining the association between socioeconomic or racial/ethnic segregation and unequal environmental exposure in environmental justice research. It emphasizes that future research needs to go beyond residential segregation by considering the full spectrum of segregation experienced by people in various geographic and temporal contexts of everyday life. Along with this comprehensive understanding of segregation, the paper also highlights the importance of assessing environmental exposure at a high spatiotemporal resolution in environmental justice research. The successful integration of a comprehensive concept of segregation, high-resolution data and fine-grained spatiotemporal approaches to assessing segregation and environmental exposure would provide more nuanced and robust findings on the associations between segregation and disparities in environmental exposure and their health impacts. Moreover, it would also contribute to significantly expanding the scope of environmental justice research.

From Measure Zero to Measure Hero: Periodic Kerr Orbits and Gravitational Wave Physics

NASA Astrophysics Data System (ADS)

Perez-Giz, Gabriel

2011-12-01

A direct observational detection of gravitational waves -- perhaps the most fundamental prediction of a theory of curved spacetime -- looms close at hand. Stellar mass compact objects spiraling into supermassive black holes have received particular attention as sources of gravitational waves detectable by space-based gravitational wave observatories. A well-established approach models such an extreme mass ratio inspirals (EMRI) as an adiabatic progression through a series of Kerr geodesics. Thus, the direct detection of gravitational radiation from EMRIs and the extraction of astrophysical information from those waveforms require a thorough knowledge of the underlying geodesic dynamics. This dissertation adopts a dynamical systems approach to the study of Kerr orbits, beginning with equatorial orbits. We deduce a topological taxonomy of orbits that hinges on a correspondence between periodic orbits and rational numbers. The taxonomy defines the entire dynamics, including aperiodic motion, since every orbit is in or near the periodic set. A remarkable implication of this periodic orbit taxonomy is that the simple precessing ellipse familiar from planetary orbits is not allowed in the strong-field regime. Instead, eccentric orbits trace out precessions of multi-leaf clovers in the final stages of inspiral. Furthermore, for any black hole, there is some orbital angular momentum value in the strong-field regime below which zoom-whirl behavior becomes unavoidable. We then generalize the taxonomy to help identify nonequatorial orbits whose radial and polar frequencies are rationally related, or in resonance. The thesis culminates by describing how those resonant orbits can be leveraged for an order of magnitude or more reduction in the computational cost of adiabatic order EMRI trajectories, which are so prohibitively expensive that no such relativistically correct inspirals have been generated to date.

Collision of an innermost stable circular orbit particle around a Kerr black hole

NASA Astrophysics Data System (ADS)

Harada, Tomohiro; Kimura, Masashi

2011-01-01

We derive a general formula for the center-of-mass (CM) energy for the near-horizon collision of two particles of the same rest mass on the equatorial plane around a Kerr black hole. We then apply this formula to a particle which plunges from the innermost stable circular orbit (ISCO) and collides with another particle near the horizon. It is found that the maximum value of the CM energy Ecm is given by Ecm/(2m0)≃1.40/1-a*24 for a nearly maximally rotating black hole, where m0 is the rest mass of each particle and a* is the nondimensional Kerr parameter. This coincides with the known upper bound for a particle which begins at rest at infinity within a factor of 2. Moreover, we also consider the collision of a particle orbiting the ISCO with another particle on the ISCO and find that the maximum CM energy is then given by Ecm/(2m0)≃1.77/1-a*26. In view of the astrophysical significance of the ISCO, this result implies that particles can collide around a rotating black hole with an arbitrarily high CM energy without any artificial fine-tuning in an astrophysical context if we can take the maximal limit of the black hole spin or a*→1. On the other hand, even if we take Thorne’s bound on the spin parameter into account, highly or moderately relativistic collisions are expected to occur quite naturally, for Ecm/(2m0) takes 6.95 (maximum) and 3.86 (generic) near the horizon and 4.11 (maximum) and 2.43 (generic) on the ISCO for a*=0.998. This implies that high-velocity collisions of compact objects are naturally expected around a rapidly rotating supermassive black hole. Implications to accretion flows onto a rapidly rotating black hole are also discussed.

Completing the Circle: A Model for Effective Community Review of Environmental Health Research

PubMed Central

Shepard, Peggy Morrow; Corbin-Mark, Cecil D.

2009-01-01

While it is well understood that multiple and cumulative environmental stressors negatively impact health at the community level, existing ethical research review procedures are designed to protect individual research participants but not communities. Increasing concerns regarding the ethical conduct of research in general and environmental and genetic research in particular underscore the need to expand the scope of current human participant research regulations and ethical guidelines to include protections for communities. In an effort to address this issue, West Harlem Environmental Action (WE ACT), a nonprofit, community-based environmental justice organization in New York City that has been involved in community–academic partnerships for the past decade, used qualitative interview data to develop a pilot model for community review of environmental health science research. PMID:19890159

Qualitative environmental health research: an analysis of the literature, 1991-2008.

PubMed

Scammell, Madeleine Kangsen

2011-10-01

Qualitative research uses nonnumeric data to understand people's opinions, motives, understanding, and beliefs about events or phenomena. In this analysis, I report the use of qualitative methods and data in the study of the relationship between environmental exposures and human health. A primary search for peer-reviewed journal articles dated from 1991 through 2008 included the following three terms: qualitative, environ*, and health. Searches resulted in 3,155 records. Data were extracted and findings of articles analyzed to determine where and by whom qualitative environmental health research is conducted and published, the types of methods and analyses used in qualitative studies of environmental health, and the types of information qualitative data contribute to environmental health. The results highlight a diversity of disciplines and techniques among researchers who used qualitative methods to study environmental health. Nearly all of the studies identified increased scientific understanding of lay perceptions of environmental health exposures. This analysis demonstrates the potential of qualitative data to improve understanding of complex exposure pathways, including the influence of social factors on environmental health, and health outcomes.

SUMMARY PAPER: IN SITU BIOREMEDIATION OF CONTAMINATED VADOSE ZONE SOIL

EPA Science Inventory

The Robert S. Kerr Environmental Research Laboratory (RSKERL) has developed a number of Issue Papers and Briefing Documents which are designed to exchange up-to-date information related to the remediation of contaminated soil and ground water at hazardous waste sites. In an attem...

FIELD SAMPLING PROTOCOLS AND ANALYSIS

EPA Science Inventory

I have been asked to speak again to the environmental science class regarding actual research scenarios related to my work at Kerr Lab. I plan to discuss sampling protocols along with various field analyses performed during sampling activities. Many of the students have never see...

Hidden symmetries on Kerr-NUT-(A)dS metrics of Einstein-Sasaki type

NASA Astrophysics Data System (ADS)

Visinescu, Mihai

2013-01-01

The hidden symmetries of higher dimensional Euclideanised Kerr-NUT-(A)dS metrics are investigated. In certain scaling limits these metrics are related to the Einstein-Sasaki ones. The complete set of Killing-Yano tensors of the Einstein-Sasaki spaces are presented. For this purpose the Killing forms of the Calabi-Yau cone over the Einstein-Sasaki manifold are constructed. Two new Killing forms on Einstein-Sasaki manifolds are identified associated with the complex volume form of the cone manifolds. As a concrete example we present the complete set of Killing-Yano tensors on the five-dimensional Einstein-Sasaki Y(p, q) spaces. The corresponding hidden symmetries are not anomalous and the geodesic equations are superintegrable.

FRESHWATER FINDINGS, 1979-1982: RESEARCH PUBLICATIONS OF THE ENVIRONMENTAL RESEARCH LABORATORY, DULUTH, MINNESOTA

EPA Science Inventory

This report contains citations of publications for the years 1979-1982 on research conducted or supported by the Environmental Research Laboratory-Duluth. All published material has been organized into two major categories: (1) Journal Articles, Book Chapters, Proceedings, etc., ...

USE OF FOCUS GROUPS FOR THE ENVIRONMENTAL HEALTH RESEARCHER

EPA Science Inventory

Qualitative research techniques are often under-utilized by the environmental health researcher. Focus groups, one such qualitative method, can provide rich data sets for study planning and implementation, risk perception, program and policy research, and exploration into future...

Research Experience for Undergraduates Program in Multidisciplinary Environmental Science

NASA Astrophysics Data System (ADS)

Wu, M. S.

2012-12-01

During summers 2011 and 12 Montclair State University hosted a Research Experience for Undergraduates Program (REU) in transdisciplinary, hands-on, field-oriented research in environmental sciences. Participants were housed at the Montclair State University's field station situated in the middle of 30,000 acres of mature forest, mountain ridges and freshwater streams and lakes within the Kittatinny Mountains of Northwest New Jersey, Program emphases were placed on development of project planning skills, analytical skills, creativity, critical thinking and scientific report preparation. Ten students were recruited in spring with special focus on recruiting students from underrepresented groups and community colleges. Students were matched with their individual research interests including hydrology, erosion and sedimentation, environmental chemistry, and ecology. In addition to research activities, lectures, educational and recreational field trips, and discussion on environmental ethics and social justice played an important part of the program. The ultimate goal of the program is to facilitate participants' professional growth and to stimulate the participants' interests in pursuing Earth Science as the future career of the participants.

Adverse effects of methylmercury: environmental health research implications.

PubMed

Grandjean, Philippe; Satoh, Hiroshi; Murata, Katsuyuki; Eto, Komyo

2010-08-01

The scientific discoveries of health risks resulting from methylmercury exposure began in 1865 describing ataxia, dysarthria, constriction of visual fields, impaired hearing, and sensory disturbance as symptoms of fatal methylmercury poisoning. Our aim was to examine how knowledge and consensus on methylmercury toxicity have developed in order to identify problems of wider concern in research. We tracked key publications that reflected new insights into human methylmercury toxicity. From this evidence, we identified possible caveats of potential significance for environmental health research in general. At first, methylmercury research was impaired by inappropriate attention to narrow case definitions and uncertain chemical speciation. It also ignored the link between ecotoxicity and human toxicity. As a result, serious delays affected the recognition of methylmercury as a cause of serious human poisonings in Minamata, Japan. Developmental neurotoxicity was first reported in 1952, but despite accumulating evidence, the vulnerability of the developing nervous system was not taken into account in risk assessment internationally until approximately 50 years later. Imprecision in exposure assessment and other forms of uncertainty tended to cause an underestimation of methylmercury toxicity and repeatedly led to calls for more research rather than prevention. Coupled with legal and political rigidity that demanded convincing documentation before considering prevention and compensation, types of uncertainty that are common in environmental research delayed the scientific consensus and were used as an excuse for deferring corrective action. Symptoms of methylmercury toxicity, such as tunnel vision, forgetfulness, and lack of coordination, also seemed to affect environmental health research and its interpretation.

Adverse Effects of Methylmercury: Environmental Health Research Implications

PubMed Central

Grandjean, Philippe; Satoh, Hiroshi; Murata, Katsuyuki; Eto, Komyo

2010-01-01

Background The scientific discoveries of health risks resulting from methylmercury exposure began in 1865 describing ataxia, dysarthria, constriction of visual fields, impaired hearing, and sensory disturbance as symptoms of fatal methylmercury poisoning. Objective Our aim was to examine how knowledge and consensus on methylmercury toxicity have developed in order to identify problems of wider concern in research. Data sources and extraction We tracked key publications that reflected new insights into human methylmercury toxicity. From this evidence, we identified possible caveats of potential significance for environmental health research in general. Synthesis At first, methylmercury research was impaired by inappropriate attention to narrow case definitions and uncertain chemical speciation. It also ignored the link between ecotoxicity and human toxicity. As a result, serious delays affected the recognition of methylmercury as a cause of serious human poisonings in Minamata, Japan. Developmental neurotoxicity was first reported in 1952, but despite accumulating evidence, the vulnerability of the developing nervous system was not taken into account in risk assessment internationally until approximately 50 years later. Imprecision in exposure assessment and other forms of uncertainty tended to cause an underestimation of methylmercury toxicity and repeatedly led to calls for more research rather than prevention. Conclusions Coupled with legal and political rigidity that demanded convincing documentation before considering prevention and compensation, types of uncertainty that are common in environmental research delayed the scientific consensus and were used as an excuse for deferring corrective action. Symptoms of methylmercury toxicity, such as tunnel vision, forgetfulness, and lack of coordination, also seemed to affect environmental health research and its interpretation. PMID:20529764

Algebraically special resonances of the Kerr-black-hole-mirror bomb

NASA Astrophysics Data System (ADS)

Hod, Shahar

2013-12-01

A corotating bosonic field interacting with a spinning Kerr black hole can extract rotational energy and angular momentum from the hole. This intriguing phenomenon is known as superradiant scattering. As pointed out by Press and Teukolsky, the black-hole-field system can be made unstable (explosive) by placing a reflecting mirror around the black hole, which prevents the extracted energy from escaping to infinity. This composed black-hole-mirror-field bomb has been studied extensively by many researchers. It is worth noting, however, that most former studies of the black-hole bomb phenomenon have focused on the specific case of confined scalar (spin-0) fields. In the present study we explore the physical properties of the higher-spin (electromagnetic and gravitational) black-hole bombs. It is shown that this composed system is amenable to an analytic treatment in the physically interesting regime of rapidly rotating black holes. In particular, we prove that the composed black-hole-mirror-field bomb is characterized by the unstable resonance frequency ω=mΩH+is·2πTBH (here s and m are, respectively, the spin parameter and the azimuthal harmonic index of the field, and ΩH and TBH are, respectively, the angular-velocity and the temperature of the rapidly spinning black hole). Our results provide evidence that the higher-spin (electromagnetic and gravitational) black-hole-mirror bombs are much more explosive than the extensively studied scalar black-hole-mirror bomb. In particular, it is shown here that the instability growth rates that characterize the higher-spin black-hole bombs are 2 orders of magnitude larger than the instability growth rate of the scalar black-hole bomb.

International Research: Its Role in Environmental Biology

ERIC Educational Resources Information Center

Higginson, John

1970-01-01

Proposes an international research laboratory to investigate environmental factors in human health. By international cooperation unnecessary duplication and waste of resources can be avoided and long-term studies can examine various world-wide environments. (JM)

Low-frequency collective dynamics in deep eutectic solvents of acetamide and electrolytes: a femtosecond Raman-induced Kerr effect spectroscopic study.

PubMed

Biswas, Ranjit; Das, Anuradha; Shirota, Hideaki

2014-10-07

In this study, we have investigated the ion concentration dependent collective dynamics in two series of deep eutectic solvent (DES) systems by femtosecond Raman-induced Kerr effect spectroscopy, as well as some physical properties, e.g., shear viscosity (η), density (ρ), and surface tension (γ). The DES systems studied here are [0.75CH3CONH2 + 0.25{f KSCN + (1 - f )NaSCN}] and [0.78CH3CONH2 + 0.22{f LiBr + (1 - f )LiNO3}] with f = 0, 0.2, 0.4, 0.6, 0.8, and 1.0. γ of these DES systems shows near insensitivity to f, while ρ shows a moderate dependence on f. Interestingly, η exhibits a strong dependence on f. In the low-frequency Kerr spectra, obtained via the Fourier transform of the collected Kerr transients, a characteristic band at ∼70 cm(-1) is clear in [0.78CH3CONH2 + 0.22{f LiBr + (1 - f )LiNO3}] DES especially at the larger f. The band is attributed to the intermolecular hydrogen bond of acetamide. Because of less depolarized Raman activities of intermolecular/interionic vibrational motions, which are mostly translational (collision-induced or interaction-induced) motions, of spherical ions, the intermolecular hydrogen-bonding band is clearly observed. In contrast, the intermolecular hydrogen-bonding band is buried in the other intermolecular/interionic vibrational motions, which includes translational and reorientational (librational) motions and their cross-terms, in [0.75CH3CONH2 + 0.25{f KSCN + (1 - f )NaSCN}] system. The first moment (M1) of the intermolecular/interionic vibrational band in these DES systems is much higher than that in typical neutral molecular liquids and shows a weak but contrasting dependence on the bulk parameter √γ/ρ. The time constants for picosecond overdamped Kerr transients in both the DES systems, which are obtained on the basis of the analysis fitted by a triexponential function, are rather insensitive to f for both the DES systems, but all the three time constants (fast: ∼1-3 ps; intermediate: �

ENVIRONMENTAL MONITORING AND ASSESSMENT PROGRAM RESEARCH STRATEGY, JULY 2002

EPA Science Inventory

The U.S. Environmental Protection Agency's (EPA) Environmental Monitoring and Assessment Program (EMAP) is a long-term research effort to enable status and trends assessments of aquatic ecosystems across the U.S. with known statistical confidence. Initiated in the late 1980's wi...

Proceedings of Workshop on Priority Great Lakes Environmental Research Initiatives (Great Lakes Environmental Research Laboratory, Ann Arbor, Michigan, October 10-11, 1974).

ERIC Educational Resources Information Center

Pinsak, Arthur P., Ed.

This publication contains the proceedings of a workshop held in Ann Arbor, Michigan to identify the priority Great Lakes environmental research initiatives. The five major objectives of the workshop include the determination of research initiatives, opportunities for university research communities to discuss and recommend future research…

Environmental assessment of the Carlsbad Environmental Monitoring and Research Center Facility

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

NONE

1995-10-01

This Environmental Assessment has been prepared to determine if the Carlsbad Environmental Monitoring and Research Center (the Center), or its alternatives would have significant environmental impacts that must be analyzed in an Environmental Impact Statement. DOE`s proposed action is to continue funding the Center. While DOE is not funding construction of the planned Center facility, operation of that facility is dependent upon continued funding. To implement the proposed action, the Center would initially construct a facility of approximately 2,300 square meters (25,000 square feet). The Phase 1 laboratory facilities and parking lot will occupy approximately 1.2 hectares (3 acres) ofmore » approximately 8.9 hectares (22 acres) of land which were donated to New Mexico State University (NMSU) for this purpose. The facility would contain laboratories to analyze chemical and radioactive materials typical of potential contaminants that could occur in the environment in the vicinity of the DOE Waste Isolation Pilot Plant (WIPP) site or other locations. The facility also would have bioassay facilities to measure radionuclide levels in the general population and in employees of the WIPP. Operation of the Center would meet the DOE requirement for independent monitoring and assessment of environmental impacts associated with the planned disposal of transuranic waste at the WIPP.« less

High Performance Simulations of Accretion Disk Dynamics and Jet Formations Around Kerr Black Holes

NASA Technical Reports Server (NTRS)

Nishikawa, Ken-Ichi; Mizuno, Yosuke; Watson, Michael

2007-01-01

We investigate jet formation in black-hole systems using 3-D General Relativistic Particle-In-Cell (GRPIC) and 3-D GRMHD simulations. GRPIC simulations, which allow charge separations in a collisionless plasma, do not need to invoke the frozen condition as in GRMHD simulations. 3-D GRPIC simulations show that jets are launched from Kerr black holes as in 3-D GRMHD simulations, but jet formation in the two cases may not be identical. Comparative study of black hole systems with GRPIC and GRMHD simulations with the inclusion of radiate transfer will further clarify the mechanisms that drive the evolution of disk-jet systems.

Nonlinear optical waves with the second Painleve transcendent shape of envelope in Kerr media

NASA Astrophysics Data System (ADS)

Shcherbakov, Alexandre S.; Tepichin Rodriguez, Eduardo; Sanchez Sanchez, Mauro

2004-05-01

Nonlinear optical wave packets with the second Painleve transcendent shape of envelope are revealed in Kerr media, manifesting weakly focusing cubic nonlinearity, square-law dispersion, and linear losses. When the state of nonlinear optical transmission is realized, two possible types of boundary conditions turn out to be satisfied for these wave packets. The propagation of initially unchirped optical wave packets under consideration could be supported by lossless medium in both normal and anomalous dispersion regimes. At the same time initially chirped optical waves with the second Painleve transcendent shape in low-loss medium and need matching the magnitude of optical losses by the dispersion and nonlinear properties of that medium.

Decay Rates and Probability Estimatesfor Massive Dirac Particlesin the Kerr-Newman Black Hole Geometry

NASA Astrophysics Data System (ADS)

Finster, F.; Kamran, N.; Smoller, J.; Yau, S.-T.

The Cauchy problem is considered for the massive Dirac equation in the non-extreme Kerr-Newman geometry, for smooth initial data with compact support outside the event horizon and bounded angular momentum. We prove that the Dirac wave function decays in L∞ {loc} at least at the rate t-5/6. For generic initial data, this rate of decay is sharp. We derive a formula for the probability p that the Dirac particle escapes to infinity. For various conditions on the initial data, we show that p = 0, 1 or 0 < p < 1. The proofs are based on a refined analysis of the Dirac propagator constructed in [4].

Effects of Kerr space-time on spectral features from X-ray illuminated accretion discs

NASA Astrophysics Data System (ADS)

Martocchia, A.; Karas, V.; Matt, G.

2000-03-01

We performed detailed calculations of the relativistic effects acting on both the reflection continuum and the iron line from accretion discs around rotating black holes. Fully relativistic transfer of both illuminating and reprocessed photons has been considered in Kerr space-time. We calculated overall spectra, line profiles and integral quantities, and present their dependences on the black hole angular momentum. We show that the observed EW of the lines is substantially enlarged when the black hole rotates rapidly and/or the source of illumination is near above the hole. Therefore, such calculations provide a way to distinguish between different models of the central source.

Research in nonlinear optics

NASA Technical Reports Server (NTRS)

Yariv, A.

1972-01-01

A theoretical investigation revealed that a steady state mode-locked solution appropriate to ultrashort pulses is induced by Kerr liquids. An experimental investigation using a Q-switched ruby laser passively mode-locked by the insertion of a Kerr liquid verified the theory. Pulses of about 10 to the -11th power sec were generated when the relaxation time of the liquid was temperature tuned to approximately 10 to the -11th power sec.

Advancing the quality of environmental microplastic research.

PubMed

Connors, Kristin A; Dyer, Scott D; Belanger, Scott E

2017-07-01

Investigations into the environmental fate and effects of microplastics have been gaining momentum. Small, insoluble polymeric particles are implicated by scientists in a wide variety of studies that are used to suggest a potential for widespread impacts in freshwater and marine pelagic and sediment environments. An exponential growth in scientific publications and an increase in regulatory attention have occurred. However, despite these efforts, the environmental hazard of these particles is still unknown. To evaluate the hazard of microplastics within a risk assessment context, we need a way to evaluate the quality of experimental studies. We performed a thorough review of the quality and focus of environmental microplastic research, to understand the methodologies employed and how this may assist or distract from the ability of environmental risk assessors to evaluate microplastics. We provide guidance to improve the reliability and relevance of ecotoxicological studies for regulatory and broader environmental assessments. Nine areas of needed improvement are identified and discussed. Important data gaps and experimental limitations are highlighted. Environ Toxicol Chem 2017;36:1697-1703. © 2017 SETAC. © 2017 SETAC.

European environmental research infrastructures are going for common 30 years strategy

NASA Astrophysics Data System (ADS)

Asmi, Ari; Konjin, Jacco; Pursula, Antti

2014-05-01

Environmental Research infrastructures are facilities, resources, systems and related services that are used by research communities to conduct top-level research. Environmental research is addressing processes at very different time scales, and supporting research infrastructures must be designed as long-term facilities in order to meet the requirements of continuous environmental observation, measurement and analysis. This longevity makes the environmental research infrastructures ideal structures to support the long-term development in environmental sciences. ENVRI project is a collaborative action of the major European (ESFRI) Environmental Research Infrastructures working towards increased co-operation and interoperability between the infrastructures. One of the key products of the ENVRI project is to combine the long-term plans of the individual infrastructures towards a common strategy, describing the vision and planned actions. The envisaged vision for environmental research infrastructures toward 2030 is to support the holistic understanding of our planet and it's behavior. The development of a 'Standard Model of the Planet' is a common ambition, a challenge to define an environmental standard model; a framework of all interactions within the Earth System, from solid earth to near space. Indeed scientists feel challenged to contribute to a 'Standard Model of the Planet' with data, models, algorithms and discoveries. Understanding the Earth System as an interlinked system requires a systems approach. The Environmental Sciences are rapidly moving to become a one system-level science. Mainly since modern science, engineering and society are increasingly facing complex problems that can only be understood in the context of the full overall system. The strategy of the supporting collaborating research infrastructures is based on developing three key factors for the Environmental Sciences: the technological, the cultural and the human capital. The technological

EDITORIAL: The need and challenge for Environmental Research Letters

NASA Astrophysics Data System (ADS)

Kammen, Daniel M.

2006-11-01

Why another journal? This is the inevitable question that every effort to launch a new journal must, and should, address. A common statistic in the business world is that nine out of ten new restaurants fail. In the academic world something similar, but less definitive, can happen: a potentially interesting, but practically flawed, effort can be launched, never truly build an intellectual community, but then continue as a sub-critical, little-known journal for far too long. The challenge any new publication, academic or professional, faces is thus extreme. A new journal must find a way to usefully compete, and bring new value, in the face of multiple existing outlets for significant results, tremendous barriers to establishing a 'track record' or 'name recognition' against existing publications, and a print and a cyberspace increasingly desperate in the search for 'content', scientific or otherwise. In the case of Environmental Research Letters (ERL), however, these questions answered themselves and, as a result, I cannot imagine a more critically needed new publication. Indeed, the goal of ERL is to be more than simply one more good new journal. It is to be a place—both physical and online—that those engaged in environmental issues—from researchers within the physical and natural sciences, to those concerned with applied systems studies, modeling and simulation techniques, practical engagement in environmental activism, and developing, conducting or critiquing policy, legal, or business efforts—will all want to go to read, and to engage with colleagues. The environmental field has witnessed an incredible intellectual and professional proliferation. The areas of ecological resilience, global change science, policy, law and economics, industrial ecology, green buildings, environmental genomics, environmental archaeology, and the sociology of environmental movements have become increasingly regarded and, to varying degrees, recognized themselves as major

Ongoing research in occupational health and environmental epidemiology in developing countries

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

Levy, B.S.; Kjellstrom, T.; Forget, G.

Research in occupational health and environmental epidemiology can play an important role in furthering our understanding of occupational and environmental health problems. Research guides us in the recognition, management, and prevention of health problems. However, in developing countries, where rates of occupational and environmental illnesses and injuries are higher and where these problems are often more severe than in developed countries, research capabilities are less developed. In mid-1990, a project was undertaken to (a) document ongoing research in occupational health and environmental epidemiology in developing countries, (b) facilitate the exchange of information among researchers in this field, (c) stimulate research,more » and (d) avoid unnecessary duplication among researchers in this field. A questionnaire was mailed, the purpose of which was to learn the current status of research in developing countries and to develop a directory of such ongoing research. The questionnaire was sent to 1,528 individuals. Of the 500 research projects identified, 77% were investigating chemical hazards; 26%, physical hazards; 10%, biological hazards; 10%, psychosocial hazards (some projects addressed multiple hazards). The chemical hazards studied most frequently were dusts, pesticides, and lead. The greatest number of research projects were identified in China, India, Brazil, Korea, and Thailand. Most projects were descriptive or cross-sectional epidemiologic studies or industrial hygiene or exposure-assessment studies. The World Health Organization has published a directory of the specific research projects that were identified in this survey.« less

REU Site: Yosemite Research Training in Environmental Science

NASA Astrophysics Data System (ADS)

Conklin, M. H.; Dayrat, B.

2009-12-01

The Yosemite Research Training in Environmental Science offers undergraduate students a unique opportunity to actively experience field research in Environmental Science in a premier National Park, over a nine-week period in the summer. The Yosemite REU is a collaboration between three institutions: the University of California at Merced, Yosemite National Park, and the USGS Western Ecological Research Center. Student activities mainly consist of individual research projects, spanning a broad range of disciplines such as Ecology, Geosciences, Biodiversity, Conservation, Restoration, and Hydrology. All projects include a strong field component. Students are exposed to the benefits of multi-disciplinary research in weekly meetings in which all students talk about their most recent work. Students present their research in Yosemite Valley at the end of the program before a public audience (including visitors). Research training is provided by mentors from UC Merced (Schools of Natural Sciences, Engineering, and Social Sciences) and the USGS Western Ecological Research Center. In addition to their interactions with their mentors and other faculty, students have opportunities to meet with NPS professionals engaged in park-related activities, to learn more about the integration of science with resources management and about potential careers in research and science outside academia. Students also participate in field trips led by UCM, USGS, and NPS scientists, focusing on Yosemite and the Sierra Nevada. Students attend a weekly seminar in Environmental Science with a broad diversity of speakers, including researchers as well as other science-related professionals, such as freelance science writers and illustrators, as well as NPS scientists and staff. Finally, student participants engage in several other activities, including outreach (e.g., a day-long meeting with high-school Central Valley students from underrepresented minorities). The Yosemite REU has already run for

Freshwater findings, 1979-1982: research publications of the Environmental Research Laboratory, Duluth, Minnesota

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

Highland, T.; Curtis, C.

1983-10-01

This report contains citations of publications for the years 1979-1982 on research conducted or supported by the Environmental Research Laboratory-Duluth. All published material has been organized into two major categories: (1) Journal Articles, Book Chapters, Proceedings, etc., and (2) EPA Research Reports. The report is organized by year with all journal articles, book chapters, proceedings, etc., for a given year appearing before the EPA research reports for the same year; within each category publications are listed alphabetically by author. Authors of the publications listed include ERL-Duluth laboratory staff members and scientists at universities, in industry, and at other facilities whomore » received research funding under the auspices of the Environmental Research Laboratory-Duluth. Limited quantities of reprints are available for those articles identified by ERL-Duluth reprint number in parentheses following the citation. These can be obtained by writing to: Librarian, ERL-Duluth, U.S. EPA, 6201 Congdon Boulevard, Duluth, MN 55804. EPA research reports can be obtained by writing to: National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22151. All other articles are not available from ERL-Duluth or NTIS, but can be found in most major libraries.« less

Comparison between modified Misgav-Ladach and Pfannenstiel-Kerr techniques for Cesarean section: review of literature

PubMed Central

Vitale, Salvatore Giovanni; Marilli, Ilaria; Cignini, Pietro; Padula, Francesco; D’Emidio, Laura; Mangiafico, Lucia; Rapisarda, Agnese Maria Chiara; Gulino, Ferdinando Antonio; Cianci, Stefano; Biondi, Antonio; Giorlandino, Claudio

2014-01-01

In the last decades cesarean section rates increased in many countries becoming the most performed intraperitoneal surgical procedure. Despite its worldwide spread, a general consensus on the most appropriate technique to use has not yet been reached. The operative technique performed is made chiefly on the basis of the individual experience and preference of operators, the characteristics of patients, timing and urgency of intervention. We compared the two most known and used techniques, modified Misgav-Ladach and traditional Pfannenstiel-Kerr, and analyzed their impact on primary, short- and long-term outcomes and outcome related to health service use. PMID:26265999

Comparison between modified Misgav-Ladach and Pfannenstiel-Kerr techniques for Cesarean section: review of literature.

PubMed

Vitale, Salvatore Giovanni; Marilli, Ilaria; Cignini, Pietro; Padula, Francesco; D'Emidio, Laura; Mangiafico, Lucia; Rapisarda, Agnese Maria Chiara; Gulino, Ferdinando Antonio; Cianci, Stefano; Biondi, Antonio; Giorlandino, Claudio

2014-01-01

In the last decades cesarean section rates increased in many countries becoming the most performed intraperitoneal surgical procedure. Despite its worldwide spread, a general consensus on the most appropriate technique to use has not yet been reached. The operative technique performed is made chiefly on the basis of the individual experience and preference of operators, the characteristics of patients, timing and urgency of intervention. We compared the two most known and used techniques, modified Misgav-Ladach and traditional Pfannenstiel-Kerr, and analyzed their impact on primary, short- and long-term outcomes and outcome related to health service use.

[Integration of sex/gender into environmental health research. Results of the interdisciplinary research network Sex/Gender-Environment-Health (GeUmGe-NET)].

PubMed

Bolte, Gabriele; David, Madlen; Dębiak, Małgorzata; Fiedel, Lotta; Hornberg, Claudia; Kolossa-Gehring, Marike; Kraus, Ute; Lätzsch, Rebecca; Paeck, Tatjana; Palm, Kerstin; Schneider, Alexandra

2018-06-01

The comprehensive consideration of sex/gender in health research is essential to increase relevance and validity of research results. Contrary to other areas of health research, there is no systematic summary of the current state of research on the significance of sex/gender in environmental health. Within the interdisciplinary research network Sex/Gender-Environment-Health (GeUmGe-NET) the current state of integration of sex/gender aspects or, respectively, gender theoretical concepts into research was systematically assessed within selected topics of the research areas environmental toxicology, environmental medicine, environmental epidemiology and public health research on environment and health. Knowledge gaps and research needs were identified in all research areas. Furthermore, the potential for methodological advancements by using gender theoretical concepts was depicted. A dialogue between biomedical research, public health research, and gender studies was started with the research network GeUmGe-NET. This dialogue has to be continued particularly regarding a common testing of methodological innovations in data collection and data analysis. Insights of this interdisciplinary research are relevant for practice areas such as environmental health protection, health promotion, environmental justice, and environmental health monitoring.

Giant Kerr response of ultrathin gold films from quantum size effect.

PubMed

Qian, Haoliang; Xiao, Yuzhe; Liu, Zhaowei

2016-10-10

With the size of plasmonic devices entering into the nanoscale region, the impact of quantum physics needs to be considered. In the past, the quantum size effect on linear material properties has been studied extensively. However, the nonlinear aspects have not been explored much so far. On the other hand, much effort has been put into the field of integrated nonlinear optics and a medium with large nonlinearity is desirable. Here we study the optical nonlinear properties of a nanometre scale gold quantum well by using the z-scan method and nonlinear spectrum broadening technique. The quantum size effect results in a giant optical Kerr susceptibility, which is four orders of magnitude higher than the intrinsic value of bulk gold and several orders larger than traditional nonlinear media. Such high nonlinearity enables efficient nonlinear interaction within a microscopic footprint, making quantum metallic films a promising candidate for integrated nonlinear optical applications.

Mobile Sensing in Environmental Health and Neighborhood Research.

PubMed

Chaix, Basile

2018-04-01

Public health research has witnessed a rapid development in the use of location, environmental, behavioral, and biophysical sensors that provide high-resolution objective time-stamped data. This burgeoning field is stimulated by the development of novel multisensor devices that collect data for an increasing number of channels and algorithms that predict relevant dimensions from one or several data channels. Global positioning system (GPS) tracking, which enables geographic momentary assessment, permits researchers to assess multiplace personal exposure areas and the algorithm-based identification of trips and places visited, eventually validated and complemented using a GPS-based mobility survey. These methods open a new space-time perspective that considers the full dynamic of residential and nonresidential momentary exposures; spatially and temporally disaggregates the behavioral and health outcomes, thus replacing them in their immediate environmental context; investigates complex time sequences; explores the interplay among individual, environmental, and situational predictors; performs life-segment analyses considering infraindividual statistical units using case-crossover models; and derives recommendations for just-in-time interventions.

Qualitative environmental health research: an analysis of the literature, 1991-2008.

PubMed

Scammell, Madeleine Kangsen

2010-08-01

Recent articles have advocated for the use of qualitative methods in environmental health research. Qualitative research uses nonnumeric data to understand people's opinions, motives, understanding, and beliefs about events or phenomena. In this analysis of the literature, I report the use of qualitative methods and data in the study of the relationship between environmental exposures and human health. A primary search on ISI Web of Knowledge/Web of Science for peer-reviewed journal articles dated from 1991 through 2008 included the following three terms: qualitative, environ*, and health. Inclusion and exclusion criteria are described. Searches resulted in 3,155 records. Data were extracted and findings of articles analyzed to determine where and by whom qualitative environmental health research is conducted and published, the types of methods and analyses used in qualitative studies of environmental health, and the types of information qualitative data contribute to environmental health. Ninety-one articles met inclusion criteria. These articles were published in 58 different journals, with a maximum of eight for a single journal. The results highlight a diversity of disciplines and techniques among researchers who used qualitative methods to study environmental health, with most studies relying on one-on-one interviews. Details of the analyses were absent from a large number of studies. Nearly all of the studies identified increased scientific understanding of lay perceptions of environmental health exposures. Qualitative data are published in traditionally quantitative environmental health studies to a limited extent. However, this analysis demonstrates the potential of qualitative data to improve understanding of complex exposure pathways, including the influence of social factors on environmental health, and health outcomes.

SUstaiNability: a science communication website on environmental research

NASA Astrophysics Data System (ADS)

Gravina, Teresita; Rutigliano, Flora Angela

2015-04-01

Environmental news mainly reach not specialist people by mass media, which generally focuses on fascinating or catastrophic events without reporting scientific data. Otherwise, scientific data on environment are published in peer-reviewed journals with specific language, so they could be not understandable to common people. In the last decade, Internet spread made easier to divulge environmental information. This allows everyone (scientist or not) to publish information without revision. In fact, World Wide Web includes many scientific sites with different levels of confidence. Within Italian scientific websites, there are those of University and Research Centre, but they mainly contain didactic and bureaucratic information, generally lacking in research news, or reporting them in peer-reviewed format. University and Research Centre should have an important role to divulge certified information, but news should be adapted to a general audience without scientific skills, in order to help population to gain knowledge on environmental issues and to develop responsible behavior. Therefore, an attractive website (www.sunability.unina2.it) has been created in order to divulge research products of Environmental, Biological and Pharmaceutical Sciences and Technologies Department (DiSTABiF) of Second University of Naples-SUN (Campania, Southern Italy). This website contains divulgation articles derived from peer-reviewed publications of DiSTABiF researchers and concerning studies on environmental, nutrition, and health issues, closely related topics. Environmental studies mainly referred to Caserta district (Southern Italy), where DiSTABiF is located. Divulgation articles have been shared by main social networks (Facebook: sunability, Twitter: @SUNability) and accesses have been monitored for 28 days in order to obtain demographic and geographic information about users and visualization number of both DiSTABiF website and social network pages. Demographic and geographic

[Environmental Hazards Assessment Program annual report, June 1992--June 1993]. Summer undergraduate research program: Environmental studies

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

McMillan, J.

1993-12-01

The purpose of the summer undergraduate internship program for research in environmental studies is to provide an opportunity for well-qualified students to undertake an original research project as an apprentice to an active research scientist in basic environmental research. Ten students from throughout the midwestern and eastern areas of the country were accepted into the program. These students selected projects in the areas of marine sciences, biostatistics and epidemiology, and toxicology. The research experience for all these students and their mentors was very positive. The seminars were well attended and the students showed their interest in the presentations and environmentalmore » sciences as a whole by presenting the speakers with thoughtful and intuitive questions. This report contains the research project written presentations prepared by the student interns.« less

Environmental sustainability in hospitals - a systematic review and research agenda.

PubMed

McGain, Forbes; Naylor, Chris

2014-10-01

Hospitals are significant contributors to natural resource depletion and environmental change. Our objective was to establish the extent to which hospital environmental sustainability has been studied and the key issues that emerge for policy, practice and research. The PubMed, Engineering Village, Cochrane and King's Fund databases were searched for articles relating to hospital environmental sustainability published in English between 1 January 1990 and 1 October 2013. Further studies were found by review of reference lists. One hundred ninety-three relevant articles were found and 76 were selected for inclusion in the review. Common research themes were identified: hospital design, direct energy consumption, water, procurement, waste, travel and psychology and behaviour. Some countries (particularly the United Kingdom) have begun to invest systematically in understanding the environmental effects of hospitals. We found large variability in the extent of the evidence base according to topic. Research regarding the architectural fabric of hospital buildings is at a relatively mature stage. Similarly, there is a developed research base regarding devices and technologies used within hospitals to reduce the environmental effects of direct hospital energy and water use. Less is known about the clinical, psychological and social factors that influence how health care professionals use resources, travel to/from hospital, and interact with the buildings and technologies available. A significant part of the environmental footprint of hospitals relates to clinical practice, e.g. decisions regarding the use of pharmaceuticals and medical devices. Medical 'cradle to grave' life cycle assessment studies have been published to understand the full financial and environmental costs of hospital activities. The effects of preventive or demand management measures which avoid unnecessary hospital procedures are likely to be much greater than incremental changes to how hospital

Re-introducing environmental change drivers in biodiversity-ecosystem functioning research

PubMed Central

De Laender, Frederik; Rohr, Jason R.; Ashauer, Roman; Baird, Donald J.; Berger, Uta; Eisenhauer, Nico; Grimm, Volker; Hommen, Udo; Maltby, Lorraine; Meliàn, Carlos J.; Pomati, Francesco; Roessink, Ivo; Radchuk, Viktoriia; Van den Brink, Paul J.

2016-01-01

For the past 20 years, research on biodiversity and ecosystem functioning (B-EF) has only implicitly considered the underlying role of environmental change. We illustrate that explicitly re-introducing environmental change drivers in B-EF research is needed to predict the functioning of ecosystems facing changes in biodiversity. Next, we show how this reintroduction improves experimental control over community composition and structure, which helps to obtain mechanistic insight about how multiple aspects of biodiversity relate to function, and how biodiversity and function relate in food-webs. We also highlight challenges for the proposed re-introduction, and suggest analyses and experiments to better understand how random biodiversity changes, as studied by classic approaches in B-EF research, contribute to the shifts in function that follow environmental change. PMID:27742415

Participatory Action Research and Environmental Learning: Implications for Resilient Forests and Communities

ERIC Educational Resources Information Center

Ballard, Heidi L.; Belsky, Jill M.

2010-01-01

How can a participatory approach to research promote environmental learning and enhance social-ecological systems resilience? Participatory action research (PAR) is an approach to research that its' supporters claim can foster new knowledge, learning, and action to support positive social and environmental change through reorienting the standard…

[Research in space environmental medicine: review and future].

PubMed

Yu, Xue-jun; Qi, Zhang-nian; Chang, Shao-yong; Liang, Hong; Liu, Hong-tao

2003-01-01

The investigation progress of space environmental medicine in China is summarized. Then, the application of space environmental medicine to formulating medical requirements for the crew module design, and performing medical evaluation for Shenzhou spaceship are addressed. Additionally, the medical and engineering means for the protection from harmful agents during spaceflight is illustrated. Finally, the objective and challenge of space environment medicine faced in the future research in China are presented.

RESEARCH ON ENVIRONMENTAL HEALTH INTERVENTIONS: ETHICAL PROBLEMS AND SOLUTIONS

PubMed Central

RESNIK, DAVID B.; ZELDIN, DARRYL C.; SHARP, RICHARD R.

2014-01-01

This article reviews a variety of ethical issues one must consider when conducting research on environmental health interventions on human subjects. The paper uses the Kennedy Krieger Institute lead abatement study as well as a hypothetical asthma study to discuss questions concerning benefits and risks, risk minimization, safety monitoring, the duty to warn, the duty to report, the use of control groups, informed consent, equitable subject selection, privacy, conflicts of interest, and community consultation. Research on environmental health interventions can make an important contribution to our understanding of human health and disease prevention, provided it is conducted in a manner that meets prevailing scientific, ethical, and legal standards for research on human subjects. PMID:16220621

78 FR 51713 - Strategic Environmental Research and Development Program, Scientific Advisory Board; Notice of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-21

... DEPARTMENT OF DEFENSE Office of the Secretary Strategic Environmental Research and Development... Environmental Research and Development Program, Scientific Advisory Board (SAB). This notice is published in... meeting is to review new start research and development projects requesting Strategic Environmental...

Masses, Dimensionless Kerr Parameters, and Emission Regions in GeV Gamma-Ray-loud Blazars

NASA Astrophysics Data System (ADS)

Xie, G.-Z.; Ma, L.; Liang, E.-W.; Zhou, S.-B.; Xie, Z.-H.

2003-11-01

We have compiled sample of 17 GeV γ-ray-loud blazars, for which rapid optical variability and γ-ray fluxes are well observed, from the literature. We derive estimates of the masses, the minimum Kerr parameters amin, and the size of the emission regions of the supermassive black holes (SMBHs) for the blazars in the sample from their minimum optical variability timescales and γ-ray fluxes. The results show that (1) the masses derived from the optical variability timescale (MH) are significantly correlated with the masses from the γ-ray luminosity (MKNH); (2) the values of amin of the SMBHs with masses MH>=108.3 Msolar (three out of 17 objects) range from ~0.5 to ~1.0, suggesting that these SMBHs are likely to be Kerr black holes. For the SMBHs with MH<108.3 Msolar, however, amin=0, suggesting that a nonrotating black hole model cannot be ruled out for these objects. In addition, the values of the size of the emission region, r*, for the two kinds of SMBHs are significantly different. For the SMBHs with amin>0, the sizes of the emission regions are almost within the horizon (2rG) and marginally bound orbit (4rG), while for those with amin=0 they are in the range (4.3-66.4)rG, extending beyond the marginally stable orbit (6rG). These results may imply that (1) the rotational state, the radiating regions, and the physical processes in the inner regions for the two kinds of SMBH are significantly different and (2) the emission mechanisms of GeV γ-ray blazars are related to the SMBHs in their centers but are not related to the two different kinds of SMBH.

Direct observation of magnetic domains by Kerr microscopy in a Ni-Mn-Ga magnetic shape-memory alloy

NASA Astrophysics Data System (ADS)

Perevertov, O.; Heczko, O.; Schäfer, R.

2017-04-01

The magnetic domains in a magnetic shape-memory Ni-Mn-Ga alloy were observed by magneto-optical Kerr microscopy using monochromatic blue LED light. The domains were observed for both single- and multivariant ferroelastic states of modulated martensite. The multivariant state with very fine twins was spontaneously formed after transformation from high-temperature austenite. For both cases, bar domains separated by 180∘ domain walls were found and their dynamics was studied. A quasidomain model was applied to explain the domains in the multivariant state.

Coming to Terms with Environmental Justice in Outdoor Recreation: A Conceptual Discussion with Research Implications

Treesearch

Myron F Floyd; Cassandra Y. Johnson

2002-01-01

Much of the research on environmental justice centers on environmental hazards. This article offers an overview of the emergence of environmental justice issues in outdoor recreation management and research. The authors argue that a major challenge to future research on environmental justice in outdoor recreation is clarifying definitions of environmental justice and...

Long-Term Environmental Research Programs - Evolving Capacity for Discovery

NASA Astrophysics Data System (ADS)

Swanson, F. J.

2008-12-01

Long-term forestry, watershed, and ecological research sites have become critical, productive nodes for environmental science research and in some cases for work in the social sciences and humanities. The Forest Service's century-old Experimental Forests and Ranges and the National Science Foundation's 28- year-old Long-Term Ecological Research program have been remarkably productive in both basic and applied sciences, including characterization of acid rain and old-growth ecosystems and development of forest, watershed, and range management systems for commercial and other land use objectives. A review of recent developments suggests steps to enhance the function of collections of long-term research sites as interactive science networks. The programs at these sites have evolved greatly, especially over the past few decades, as the questions addressed, disciplines engaged, and degree of science integration have grown. This is well displayed by small, experimental watershed studies, which first were used for applied hydrology studies then more fundamental biogeochemical studies and now examination of complex ecosystem processes; all capitalizing on the legacy of intensive studies and environmental monitoring spanning decades. In very modest ways these collections of initially independent sites have functioned increasingly as integrated research networks addressing inter-site questions by using common experimental designs, being part of a single experiment, and examining long-term data in a common analytical framework. The network aspects include data sharing via publicly-accessible data-harvester systems for climate and streamflow data. The layering of one research or environmental monitoring network upon another facilitates synergies. Changing climate and atmospheric chemistry highlight a need to use these networks as continental-scale observatory systems for assessing the impacts of environmental change on ecological services. To better capitalize on long

The Roots and Routes of Environmental and Sustainability Education Policy Research

ERIC Educational Resources Information Center

Van Poeck, Katrien; Lysgaard, Jonas A.

2016-01-01

"Environmental Education Research" has developed a Virtual Special Issue (VSI) (http://explore.tandfonline.com/content/ed/ceer-vsi) focusing on studies of environmental and sustainability education (ESE) policy. The VSI draws on key examples of research on this topic published in the Journal from the past two decades, for three reasons.…

Gravitational self-force on generic bound geodesics in Kerr spacetime

NASA Astrophysics Data System (ADS)

van de Meent, Maarten

2018-05-01

In this work we present the first calculation of the gravitational self-force on generic bound geodesics in Kerr spacetime to first order in the mass ratio. That is, the local correction to equations of motion for a compact object orbiting a larger rotating black hole due to its own impact on the gravitational field. This includes both dissipative and conservative effects. Our method builds on and extends earlier methods for calculating the gravitational self-force on equatorial orbits. In particular we reconstruct the local metric perturbation in the outgoing radiation gauge from the Weyl scalar ψ4 , which in turn is obtained by solving the Teukolsky equation using semianalytical frequency domain methods. The gravitational self-force is subsequently obtained using (spherical) l -mode regularization. We test our implementation by comparing the large l -behavior against the analytically known regularization parameters. In addition we validate our results by comparing the long-term average changes to the energy, angular momentum, and Carter constant to changes to these constants of motion inferred from the gravitational wave flux to infinity and down the horizon.

Laboratory upwelled radiance and reflectance spectra of Kerr reservoir sediment waters

NASA Technical Reports Server (NTRS)

Witte, W. G.; Whitlock, C. H.; Morris, W. D.; Gurganus, E. A.

1982-01-01

Reflectance, chromaticity, and several other physical and chemical properties were measured for various water mixtures of bottom sediments taken from two sites at Kerr Reservoir, Virginia. Mixture concentrations ranged from 5 to 1000 ppm by weight of total suspended solids (TSS) in filtered deionized tap water. The two sets of radiance and reflectance spectra obtained were similar in shape and magnitude for comparable values of TSS. Upwelled reflectance was observed to be a nonlinear function of TSS with the degree of curvature a function of wavelength. Sediment from the downstream site contained a greater amount of particulate organic carbon than from the upstream site. No strong conclusions can be made regarding the effects of this difference on the radiance and reflectance spectra. Near-infrared wavelengths appear useful for measuring highly turbid water with concentrations up to 1000 ppm or more. Chromaticity characteristics do not appear useful for monitoring sediment loads above 150 ppm.

Rigidly rotating zero-angular-momentum observer surfaces in the Kerr spacetime

NASA Astrophysics Data System (ADS)

Frolov, Andrei V.; Frolov, Valeri P.

2014-12-01

A stationary observer in the Kerr spacetime has zero angular momentum if their angular velocity ω has a particular value, which depends on the position of the observer. Worldlines of such zero-angular-momentum observers (ZAMOs) with the same value of the angular velocity ω form a three-dimensional surface, which has the property that the Killing vectors generating time translation and rotation are tangent to it. We call such a surface a rigidly rotating ZAMO surface. This definition allows for a natural generalization to the surfaces inside the black hole, where ZAMO trajectories formally become spacelike. A general property of such a surface is that there exist linear combinations of the Killing vectors with constant coefficients which make them orthogonal on it. In this paper we discuss properties of the rigidly rotating ZAMO surfaces both outside and inside the black hole and the relevance of these objects to a couple of interesting physical problems.

Spin-dependent post-Newtonian parameters from EMRI computation in Kerr background

NASA Astrophysics Data System (ADS)

Friedman, John; Le Tiec, Alexandre; Shah, Abhay

2013-04-01

Because the extreme mass-ratio inspiral (EMRI) approximation is accurate to all orders in v/c, it can be used to find high order post-Newtonian parameters that are not yet analytically accessible. We report here on progress in computing spin-dependent, conservative, post-Newtonian parameters from a radiation-gauge computation for a particle in circular orbit in a family of Kerr geometries. For a particle with 4-velocity u^α= U k^α, with k^α the helical Killing vector of the perturbed spacetime, the renormalized perturbation δU, when written as a function of the particle's angular velocity, is invariant under gauge transformations generated by helically symmetric vectors. The EMRI computations are done in a modified radiation gauge. Extracted parameters are compared to previously known and newly computed spin-dependent post-Newtonian terms. This work is modeled on earlier computations by Blanchet, Detweiler, Le Tiec and Whiting of spin-independent terms for a particle in circular orbit in a Schwarzschild geometry.

Thermal radiation from optically driven Kerr (χ{sup (3)}) photonic cavities

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

Khandekar, Chinmay; Rodriguez, Alejandro W.; Lin, Zin

2015-04-13

We describe thermal radiation from nonlinear (χ{sup (3)}) photonic cavities coupled to external channels and subject to incident monochromatic light. Our work extends related work on nonlinear mechanical oscillators to the problem of thermal radiation, demonstrating that bistability can enhance thermal radiation by orders of magnitude and result in strong lineshape alternations, including “super-narrow spectral peaks” occurring at the onset of kinetic phase transitions. We show that when the cavities are designed to exhibit perfect linear emissivity (rate matching), such thermally activated transitions can be exploited to dramatically tune the output power and radiative properties of the cavity, leading tomore » a kind of Kerr-mediated thermo-optic effect. Finally, we demonstrate that in certain parameter regimes, the output radiation exhibits Stokes and anti-Stokes side peaks whose relative magnitudes can be altered by tuning the internal temperature of the cavity relative to its surroundings, a consequence of strong correlations and interference between the emitted and reflected radiation.« less

International Research Workshop on Integrating GIS and Environmental Modeling: Problems, Prospects, and Research Needs

NASA Technical Reports Server (NTRS)

Parks, Bradley; Meeson, Blanche W. (Technical Monitor)

2001-01-01

The 4th International Conference on Integrating GIS and Environmental Modeling (GIS/EM4) was convened in Banff, Canada, September 2-8, 2000 at The Banff Centre for Conferences. The meeting's purpose, like it's predecessors was to reformulate, each three to four years, the collaborative research agenda for integrating spatio-temporal analysis with environmental simulation modeling.

Environmental monitoring and research at the John F. Kennedy Space Center

NASA Technical Reports Server (NTRS)

Hall, C. R.; Hinkle, C. R.; Knott, W. M.; Summerfield, B. R.

1992-01-01

The Biomedical Operations and Research Office at the NASA John F. Kennedy Space Center has been supporting environmental monitoring and research since the mid-1970s. Program elements include monitoring of baseline conditions to document natural variability in the ecosystem, assessments of operations and construction of new facilities, and ecological research focusing on wildlife habitat associations. Information management is centered around development of a computerized geographic information system that incorporates remote sensing and digital image processing technologies along with traditional relational data base management capabilities. The proactive program is one in which the initiative is to anticipate potential environmental concerns before they occur and, by utilizing in-house expertise, develop impact minimization or mitigation strategies to reduce environmental risk.

Community Engagement and Data Disclosure in Environmental Health Research

PubMed Central

Haynes, Erin N.; Elam, Sarah; Burns, Roxanne; Spencer, Alonzo; Yancey, Elissa; Kuhnell, Pierce; Alden, Jody; Walton, Mike; Reynolds, Virgil; Newman, Nicholas; Wright, Robert O.; Parsons, Patrick J.; Praamsma, Meredith L.; Palmer, Christopher D.; Dietrich, Kim N.

2016-01-01

Summary: Federal funding agencies increasingly support stakeholder participation in environmental health studies, and yet there is very little published research on engagement of community members in the development of data disclosure (DD) strategies. The Ohio Environmental Protection Agency reported airborne manganese (Mn) concentrations in East Liverpool, Ohio, 30 times higher than the reference concentration, which led to an academic–community research partnership to address community concern about Mn exposure, particularly among children. Children and their families were recruited to participate in a pilot study. Samples of blood and hair were collected from the children and analyzed for metals. DD mechanisms were developed using an iterative approach between community and academic partners. Individual DD letters were mailed to each participating family, and a community meeting was held. A post-meeting survey was administered to gauge community perception of the DD strategies. The purpose of this article is to demonstrate the effectiveness of engaging community partners in the conduct of environmental health research and in the development of DD strategies for individuals and the community at large. Scientists should include community partners in the development of DD strategies to enhance translation of the research findings and support the right of study participants to know their individual results. PMID:26829152

Research characteristics and status on Environmental Psychology: a bibliometric and knowledge mapping analysis

NASA Astrophysics Data System (ADS)

Xu, Jun Hua; Zhu, Lei Ye; Wang, Hai Bin

2018-06-01

Environmental psychology is an interdisciplinary field that focuses on the interplay between individuals and their built and natural environments. Great progress has been made in the areas of environmental psychology by researchers form many countries. However, a thorough quantitative analysis to the emergent research trends and topics has not been found. To reveal the research characteristics and status on Environmental Psychology, 853 related papers from Web of Science core collection were analysed by CiteSpace II. The results show that: (1) the domain of Environmental Psychology was started in 1960s and showed a low growth over the past half century, which reaches a historical peak in 2017. Gifford, USA and the Journal of Environmental Psychology top the list of contributing authors, country and publication respectively. (2) "Environmental Psychology" is the most frequently keywords and has the longest span of the bursts. "ambient scent", "recycling", "children as outsiders" and "ambient temperature" are the top four largest clusters, which are the popular research topics in the domain of environmental psychology.

Scientific integrity: critical issues in environmental health research

PubMed Central

Merlo, Domenico Franco; Vahakangas, Kirsi; Knudsen, Lisbeth E

2008-01-01

Environmental health research is a relatively new scientific area with much interdisciplinary collaboration. Regardless of which human population is included in field studies (e.g., general population, working population, children, elderly, vulnerable sub-groups, etc.) their conduct must guarantee well acknowledged ethical principles. These principles, along with codes of conduct, are aimed at protecting study participants from research-related undesired effects and guarantee research integrity. A central role is attributed to the need for informing potential participants (i.e., recruited subjects who may be enrolled in a study), obtaining their written informed consent to participate, and making them aware of their right to refuse to participate at any time and for any reason. Data protection is also required and communication of study findings must respect participant's willingness to know or not know. This is specifically relevant for studies including biological markers and/or storing biological samples that might be analysed years later to tackle research objectives that were specified and communicated to participants at the time of recruitment or that may be formulated after consent was obtained. Integrity is central to environmental health research searching for causal relations. It requires open communication and trust and any violation (i.e., research misconduct, including fabrication or falsification of data, plagiarism, conflicting interests, etc.) may endanger the societal trust in the research community as well as jeopardize participation rates in field projects. PMID:18541075

Giant magneto-optical Kerr rotation, quality factor and figure of merit in cobalt-ferrite magnetic nanoparticles doped in silica matrix as the only defect layer embedded in magnetophotonic crystals

NASA Astrophysics Data System (ADS)

Zamani, Mehdi; Hocini, Abdesselam

2018-03-01

In this work, we report on the theoretical study of one-dimensional magnetophotonic crystals (MPC) comprising of periodic dielectric structure Si/SiO and of silica matrix doped with cobalt-ferrite (CoFe2O4) magnetic nanoparticles as the only magnetic defect layer. Such structure can be prepared by sol-gel dip coating method that controls the thickness of each layer with nanometer level, hence, can overcome the problem of integration of the magneto-optical (MO) devices. We have studied the influence of the volume fraction (concentration of magnetic nanoparticles VF%) on the optical (reflectance, transmittance and absorption) and MO (Kerr rotation) responses in reflection-type one-dimensional MPCs. During investigation of the influence of magnetic nanoparticle's concentration, we found that giant Kerr rotations (even ≈135° for VF = 39%) can be obtained accompanied by large reflectance and low amounts for transmittance and absorption. We report on the demonstration of large MO quality factor and figure of merit in cobalt-ferrite magnetic nanoparticles in the infrared regime. Given the large Kerr rotation, high reflectance accompanied by low absorption and nearly zero transmittance of the 1D MPC containing cobalt-ferrite magnetic nanoparticles, large MO Q factor and figure of merit are obtained.

Adaptation to the edge of chaos in a self-starting Kerr-lens mode-locked laser

NASA Astrophysics Data System (ADS)

Hsu, C. C.; Lin, J. H.; Hsieh, W. F.

2009-08-01

We experimentally and numerically demonstrated that self-focusing acts as a slow-varying control parameter that suppresses the transient chaos to reach a stable mode-locking (ML) state in a self-starting Kerr-lens mode-locked Ti:sapphire laser without external modulation and feedback control. Based on Fox-Li’s approach, including the self-focusing effect, the theoretical simulation reveals that the self-focusing effect is responsible for the self-adaptation. The self-adaptation occurs at the boundary between the chaotic and continuous output regions in which the laser system begins with a transient chaotic state with fractal correlation dimension, and then evolves with reducing dimension into the stable ML state.

Engaging Children: Research Issues around Participation and Environmental Learning

ERIC Educational Resources Information Center

Hacking, Elisabeth Barratt; Barratt, Robert; Scott, William

2007-01-01

In this article we explore a number of issues arising from the papers in this special issue of "Environmental Education Research." The papers focus on current examples of childhood environment research in the UK together with research reviews from the UK, the US and Australia. In order to provide a framework for considering and…

78 FR 48200 - Advisory Committee for Environmental Research and Education; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-07

... NATIONAL SCIENCE FOUNDATION Advisory Committee for Environmental Research and Education; Notice of... Research and Education, 9487. Dates: September 11, 2013, 9:00 a.m.-5:00 p.m., and September 12, 2013, 9:00... research and education. Agenda September 11, 2013 Update on NSF environmental research and education...

Generation of Kerr combs centered at 4.5 μm in crystalline microresonators pumped with quantum-cascade lasers.

PubMed

Savchenkov, Anatoliy A; Ilchenko, Vladimir S; Di Teodoro, Fabio; Belden, Paul M; Lotshaw, William T; Matsko, Andrey B; Maleki, Lute

2015-08-01

We report on the generation of mid-infrared Kerr frequency combs in high-finesse CaF2 and MgF2 whispering-gallery-mode resonators pumped with continuous-wave room-temperature quantum cascade lasers. The combs were centered at 4.5 μm, the longest wavelength to date. A frequency comb wider than one half of an octave was demonstrated when approximately 20 mW of pump power was coupled to an MgF2 resonator characterized with quality factor exceeding 10(8).

Privacy and ethics in pediatric environmental health research-part II: protecting families and communities.

PubMed

Fisher, Celia B

2006-10-01

In pediatric environmental health research, information about family members is often directly sought or indirectly obtained in the process of identifying child risk factors and helping to tease apart and identify interactions between genetic and environmental factors. However, federal regulations governing human subjects research do not directly address ethical issues associated with protections for family members who are not identified as the primary "research participant." Ethical concerns related to family consent and privacy become paramount as pediatric environmental health research increasingly turns to questions of gene-environment interactions. In this article I identify issues arising from and potential solutions for the privacy and informed consent challenges of pediatric environmental health research intended to adequately protect the rights and welfare of children, family members, and communities. I first discuss family members as secondary research participants and then the specific ethical challenges of longitudinal research on late-onset environmental effects and gene-environment interactions. I conclude with a discussion of the confidentiality and social risks of recruitment and data collection of research conducted within small or unique communities, ethnic minority populations, and low-income families. The responsible conduct of pediatric environmental health research must be conceptualized as a goodness of fit between the specific research context and the unique characteristics of subjects and other family stakeholders.

Phase-transition Theory of Kerr Black Holes in the Electromagnetic Field

NASA Astrophysics Data System (ADS)

Liao, Yi; Gong, Xiao-Bo; Wu, Jian-Sheng

2017-02-01

For a Kerr black hole (KBH) with spin J and mass M in a steady electromagnetic field, a special Wald vacuum solution (WVS) has been found in the case of the no-source uniform field. For WVS, the Meissner effect (ME) occurs only in the the extreme KBH, where M2/J = 1, in this case, the magnetic field is totally excluded from the event horizon (EH) of KBH. However, WVS does not consider the Hawking radiation (HR) but treats KBH as an absolutely black body. If HR is added , researchers believe that the condition is not so restricted and it is possible for ME to occur in the less-extreme case. How less is the “less-extreme case”? This paper tries to answer this question. Since the Hawking temperature TH of KBH defined by HR is proportional to the surface gravity κ at the EH, this question is actually about the so-called existence/non-existence of ME (ME/NME) or superconducting phase transition. In this paper, we study the connection between the superconductivity of KBH-EH and the existence of Weyl fermion. Using thermodynamic formulas and the KBH state equation, we prove that the inherent-parameter condition for ME to occur is {M}2/J≤slant {ɛ }c=1.5 in force-free fields whether it be in the simple axisymmetric vacuum zero source case or in the non-zero source case, which can be described by the nonlinear Grad-Shafranov equation. We suggest that this is a second-order phase transition and calculate the critical exponents δ = 1 and η = 1/2 for the specific heat diverging at constant J.

GeoEnvironmental Education Through Multidisciplinary Research

NASA Astrophysics Data System (ADS)

Padilla, I. Y.; Hwang, S.

2007-12-01

The growing need to understand environmental and geological processes, their impacts, and solutions in a dynamic world requires a diverse, multidiscipline, and multicultural approach in science and engineering. In the last few years, faculty at the University of Puerto Rico, Mayagüez have engaged in education and training activities aimed at developing a critical mass of students that can address a wide range of geoenvironmental problems through multidisciplinary research. Students of diverse age, gender, culture, and academic disciplines addressing different research questions work together in a common space. Hierarchy assignments use senior students as primary mentors, but foster work at parallel levels that require sharing and developing knowledge and research resources. The activities have resulted in a significant increase in the number of diverse students in science and engineering areas related to the environment.

Improved longitudinal magneto-optic Kerr effect signal contrast from nanomagnets with dielectric coatings

NASA Astrophysics Data System (ADS)

Holiday, L. F.; Gibson, U. J.

2006-12-01

We report on the use of dielectric coatings to improve the contrast of longitudinal magneto-optic Kerr effect signals from submicron magnetic structures. Electron-beam lithography was used to define disks in 22 nm thick Ni films deposited on Si substrates. The structures were measured in four configurations: as-deposited, through a fused silica prism using index-matching fluid, coated with ZnS, and using a prism on top of the ZnS layer. The modified samples show up to 20 times improvement in the MOKE contrast due to admittance matching to the magnetic material and suppression of the substrate reflectance. The behavior is successfully predicted by a model that includes the magneto-optic response of the nickel layer and accounts for the fraction of the beam intercepted by the magnetic structure.

Mössbauer and Kerr microscopy investigation of crystallization in FeCoB ribbons

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

Reddy, V. Raghavendra, E-mail: varimalla@yahoo.com, E-mail: vrreddy@csr.res.in; Hussain, Zaineb; Babu, Hari

2016-05-23

The present work reports the crystallization study of amorphous FeCoB ribbons using x-ray diffraction, {sup 57}Fe Mössbauer spectroscopy in transmission mode and magneto-optical Kerr (MOKE) microscopy. Annealing at 673 K is found to result in crystallization. From the Mossbauer measurements it is observed that the Fe magnetic moments are in the plane of sample for as-cast ribbon; α-FeCo, (Fe{sub 0.5}Co{sub 0.5}){sub 2}B and Fe{sub 2}B phases are formed after crystallization. MOKE microscopy revealed that wide 180° domain walls & narrow fingerprint domains are observed before crystallization and fine domains are observed after crystallization. The results are explained in terms ofmore » the presence of internal stresses and their annealing with thermal heat treatment.« less

Investigating the Benefits of Participatory Action Research for Environmental Education

ERIC Educational Resources Information Center

Bywater, Krista

2014-01-01

Environmental education (EE) continues to focus on enhancing people's ecological knowledge to encourage sustainable actions. This deficit approach presumes that once informed about environmental harms, people will work towards sustainable solutions for healthy societies. Yet research overwhelmingly demonstrates that knowledge of environmental…

Protecting Privacy and Confidentiality in Environmental Health Research.

PubMed

Resnik, David B

2010-01-01

Environmental health researchers often need to make difficult decisions on how to protect privacy and confidentiality when they conduct research in the home or workplace. These dilemmas are different from those normally encountered in clinical research. Although protecting privacy and confidentiality is one of the most important principles of research involving human subjects, it can be overridden to prevent imminent harm to individuals or if required by law. Investigators should carefully consider the facts and circumstances and use good judgment when deciding whether to breach privacy or confidentiality.

Report to Congress on the U.S. Department of Energy`s Environmental Management Science Program: Research funded and its linkages to environmental cleanup problems, and Environmental Management Science Program research award abstracts. Volume 2 of 3 -- Appendix B

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

NONE

The Department of Energy`s Environmental Management Science Program (EMSP) serves as a catalyst for the application of scientific discoveries to the development and deployment of technologies that will lead to reduction of the costs and risks associated with cleaning up the nation`s nuclear complex. Appendix B provides details about each of the 202 research awards funded by the EMSP. This information may prove useful to researchers who are attempting to address the Department`s environmental management challenges in their work, program managers who are planning, integrating, and prioritizing Environmental Management projects, and stakeholders and regulators who are interested in the Department`smore » environmental challenges. The research award information is organized by the state and institution in which the lead principal investigator is located. In many cases, the lead principal investigator is one of several investigators at a number of different institutions. In these cases, the lead investigator (major collaborator) at each of the additional institutions is listed. Each research award abstract is followed by a list of high cost projects that can potentially be impacted by the research results. High cost projects are Environmental Management projects that have total costs greater than $50 million from the year 2007 and beyond, based on the March 1998 Accelerating Cleanup: Paths to Closure Draft data, and have costs or quantities of material associated with an Environmental Management problem area. High cost projects which must remain active in the year 2007 and beyond to manage high risk are also identified. Descriptions of these potentially related high cost Environmental Management projects can be found in Appendix C. Additional projects in the same problem area as a research award can be located using the Index of High Cost Environmental Management Projects by Problem Area, at the end of Appendices B and C.« less

Privacy and ethics in pediatric environmental health research-part I: genetic and prenatal testing.

PubMed

Fisher, Celia B

2006-10-01

The pressing need for empirically informed public policies aimed at understanding and promoting children's health has challenged environmental scientists to modify traditional research paradigms and reevaluate their roles and obligations toward research participants. Methodologic approaches to children's environmental health research raise ethical challenges for which federal regulations may provide insufficient guidance. In this article I begin with a general discussion of privacy concerns and informed consent within pediatric environmental health research contexts. I then turn to specific ethical challenges associated with research on genetic determinants of environmental risk, prenatal studies and maternal privacy, and data causing inflicted insight or affecting the informational rights of third parties.

Femtosecond Raman-Induced Kerr Effect Study of Temperature-Dependent Intermolecular Dynamics in Imidazolium-Based Ionic Liquids: Effects of Anion Species and Cation Alkyl Groups.

PubMed

Kakinuma, Shohei; Ishida, Tateki; Shirota, Hideaki

2017-01-12

The temperature dependence of the intermolecular vibrational dynamics in imidazolium-based ionic liquids (ILs) with 10 different anions was studied by femtosecond Raman-induced Kerr effect spectroscopy. For all ILs investigated in this study, the intensity in the low-frequency region below 50 cm -1 increases, and the spectral density in the high-frequency region above 80 cm -1 decreases (and shows a redshift) with increasing temperature. The first phenomenon would be attributed to the activation of the translational vibrational motions, whereas the second one is ascribed to the slowing librational motion of the imidazolium ring with increasing temperature. Calculated spectra of the density of states for the intermolecular vibrations of 1-butyl-3-methylimidazolium hexafluorophosphate, which is one of the experiment samples studied here, obtained by molecular dynamics simulation agreed well with the experimental results and confirmed the spectral assignments. When we compared the difference spectra between spectra measured at various temperatures and the spectrum measured at 293 K, a clear difference was found in the ∼50 cm -1 region of the Kerr spectra of 1-butyl-3-methylimidazolium thiocyanate and 1-butyl-3-methylimidazolium dicyanamide from those of the other ILs. The difference might have originated from the librational motions of the corresponding anions. We also compared the temperature-dependent Kerr spectra of hexafluorophosphate salts of 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, and 1-heptyl-3-methylimidazolium cations. These ILs showed a similar temperature dependence, which was not affected by the alkyl group length. The temperature-dependent viscosities and glass transition temperatures of the ILs were also estimated to determine their fragilities.

ROLE OF VIBRATIONAL SPECTROSCOPY AT THE U.S. ENVIRONMENTAL PROTECTION AGENCY'S ENVIRONMENTAL RESEARCH LABORATORY IN ATHENS, GEORGIA

EPA Science Inventory

The Environmental Research Laboratory, U.S. Environmental Protection Agency, Athens GA, is best known by vibrational spectroscopists as the laboratory where much of the pioneering work on the development of a sensitive, real-time gas chromatograph/Fourier transform infrared syste...

About the Director of EPA's National Health and Environmental Effects Research Laboratory (NHEERL)

EPA Pesticide Factsheets

Dr. Wayne Cascio serves as Acting Director for the National Health and Environmental Effects Research Laboratory (NHEERL) within the U.S. Environmental Protection Agency's Office of Research and Development (ORD).

An Integrated Cyberenvironment for Event-Driven Environmental Observatory Research and Education

NASA Astrophysics Data System (ADS)

Myers, J.; Minsker, B.; Butler, R.

2006-12-01

National environmental observatories will soon provide large-scale data from diverse sensor networks and community models. While much attention is focused on piping data from sensors to archives and users, truly integrating these resources into the everyday research activities of scientists and engineers across the community, and enabling their results and innovations to be brought back into the observatory, also critical to long-term success of the observatories, is often neglected. This talk will give an overview of the Environmental Cyberinfrastructure Demonstrator (ECID) Cyberenvironment for observatory-centric environmental research and education, under development at the National Center for Supercomputing Applications (NCSA), which is designed to address these issues. Cyberenvironments incorporate collaboratory and grid technologies, web services, and other cyberinfrastructure into an overall framework that balances needs for efficient coordination and the ability to innovate. They are designed to support the full scientific lifecycle both in terms of individual experiments moving from data to workflows to publication and at the macro level where new discoveries lead to additional data, models, tools, and conceptual frameworks that augment and evolve community-scale systems such as observatories. The ECID cyberenvironment currently integrates five major components a collaborative portal, workflow engine, event manager, metadata repository, and social network personalization capabilities - that have novel features inspired by the Cyberenvironment concept and enabling powerful environmental research scenarios. A summary of these components and the overall cyberenvironment will be given in this talk, while other posters will give details on several of the components. The summary will be presented within the context of environmental use case scenarios created in collaboration with researchers from the WATERS (WATer and Environmental Research Systems) Network, a

Time-resolved scanning Kerr microscopy of flux beam formation in hard disk write heads

NASA Astrophysics Data System (ADS)

Valkass, Robert A. J.; Spicer, Timothy M.; Burgos Parra, Erick; Hicken, Robert J.; Bashir, Muhammad A.; Gubbins, Mark A.; Czoschke, Peter J.; Lopusnik, Radek

2016-06-01

To meet growing data storage needs, the density of data stored on hard disk drives must increase. In pursuit of this aim, the magnetodynamics of the hard disk write head must be characterized and understood, particularly the process of "flux beaming." In this study, seven different configurations of perpendicular magnetic recording (PMR) write heads were imaged using time-resolved scanning Kerr microscopy, revealing their detailed dynamic magnetic state during the write process. It was found that the precise position and number of driving coils can significantly alter the formation of flux beams during the write process. These results are applicable to the design and understanding of current PMR and next-generation heat-assisted magnetic recording devices, as well as being relevant to other magnetic devices.

Environmental reporting and accounting in Australia: progress, prospects and research priorities.

PubMed

van Dijk, Albert; Mount, Richard; Gibbons, Philip; Vardon, Michael; Canadell, Pep

2014-03-01

Despite strong demand for information to support the sustainable use of Australia's natural resources and conserve environmental values and despite considerable effort and investment, nation-wide environmental data collection and analysis remains a substantially unmet challenge. We review progress in producing national environmental reports and accounts, identify challenges and opportunities, and analyse the potential role of research in addressing these. Australia's low and concentrated population density and the short history since European settlement contribute to the lack of environmental data. There are additional factors: highly diverse data requirements and standards, disagreement on information priorities, poorly measurable management objectives, lack of coordination, over-reliance on researchers and businesses for data collection, lack of business engagement, and short-term, project-based activities. New opportunities have arisen to overcome some of these challenges: enhanced monitoring networks, standardisation, data management and modelling, greater commitment to share and integrate data, community monitoring, increasing acceptance of environmental and sustainability indicators, and progress in environmental accounting practices. Successes in generating climate, water and greenhouse gas information appear to be attributable to an unambiguous data requirement, considerable investment, and legislative instruments that enhance data sharing and create a clearly defined role for operational agencies. Based on the analysis presented, we suggest six priorities for research: (1) common definitions and standards for information that address management objectives, (2) ecological measures that are scalable from local to national level, (3) promotion of long-term data collection and reporting by researchers, (4) efficient satellite and sensor network technologies and data analysis methods, (5) environmental modelling approaches that can reconcile multiple data

Conducting environmental health research in the Arabian Middle East: lessons learned and opportunities.

PubMed

Yeatts, Karin B; El-Sadig, Mohamed; Ali, Habiba I; Al-Maskari, Fatma; Campbell, Alan; Ng, Shu Wen; Reeves, Lisa; Chan, Ronna L; Davidson, Christopher A; Funk, William E; Boundy, Maryanne G; Leith, David; Popkin, Barry; Gibson, Jacqueline Macdonald; Rusyn, Ivan; Olshan, Andrew F

2012-05-01

The Arabian Gulf nations are undergoing rapid economic development, leading to major shifts in both the traditional lifestyle and the environment. Although the pace of change is brisk, there is a dearth of environmental health research in this region. We describe challenges and successes of conducting an environmental epidemiologic study in the United Arab Emirates (UAE), a Gulf nation in the Middle East, with an inter-disciplinary team that includes in-country academic and government collaborators as well as U.S. academic collaborators. We present several issues, including study and data collection design, exposure assessment, scheduling and time coordination, quality assurance and quality control, and institutional review board protocols. These topics are considered in a cultural context. Benefits of this research included building linkages among multinational, interdisciplinary team members, generating data for local environmental decision making, and developing local epidemiologic research capacity. The Middle Eastern culture of hospitality greatly benefited the project team. Cultural differences impact multiple aspects of epidemiologic research and should be respectfully addressed. Conducting international population-based environmental research poses many challenges; these challenges can be met successfully with careful planning, cultural knowledge, and flexibility. Lessons learned are applicable to interdisciplinary research all over the world. The research conducted will benefit the environmental and public health agencies of the UAE and provide the nation's leadership with country-specific environmental health data that can be used to protect the public's health in a rapidly changing environment.

Conducting Environmental Health Research in the Arabian Middle East: Lessons Learned and Opportunities

PubMed Central

El-Sadig, Mohamed; Ali, Habiba I.; Al-Maskari, Fatma; Campbell, Alan; Ng, Shu Wen; Reeves, Lisa; Chan, Ronna L.; Davidson, Christopher A.; Funk, William E.; Boundy, Maryanne G.; Leith, David; Popkin, Barry; Gibson, Jacqueline MacDonald; Rusyn, Ivan; Olshan, Andrew F.

2012-01-01

Background: The Arabian Gulf nations are undergoing rapid economic development, leading to major shifts in both the traditional lifestyle and the environment. Although the pace of change is brisk, there is a dearth of environmental health research in this region. Objective: We describe challenges and successes of conducting an environmental epidemiologic study in the United Arab Emirates (UAE), a Gulf nation in the Middle East, with an inter-disciplinary team that includes in-country academic and government collaborators as well as U.S. academic collaborators. Discussion: We present several issues, including study and data collection design, exposure assessment, scheduling and time coordination, quality assurance and quality control, and institutional review board protocols. These topics are considered in a cultural context. Benefits of this research included building linkages among multinational, interdisciplinary team members, generating data for local environmental decision making, and developing local epidemiologic research capacity. The Middle Eastern culture of hospitality greatly benefited the project team. Conclusion: Cultural differences impact multiple aspects of epidemiologic research and should be respectfully addressed. Conducting international population-based environmental research poses many challenges; these challenges can be met successfully with careful planning, cultural knowledge, and flexibility. Lessons learned are applicable to interdisciplinary research all over the world. The research conducted will benefit the environmental and public health agencies of the UAE and provide the nation’s leadership with country-specific environmental health data that can be used to protect the public’s health in a rapidly changing environment. PMID:22356946

Environmental Quality Research and Development. A Review and Analysis of Federal Programs.

ERIC Educational Resources Information Center

Executive Office of the President, Washington, DC.

This is the first interagency report on Federal environmental quality research and development programs that presents program descriptions, levels of funding, and analyses. Undertaken at the request of the Federal Council for Science and Technology, the study may be useful in identifying environmental quality research and development programs in…

Measuring Values in Environmental Research: A Test of an Environmental Portrait Value Questionnaire

PubMed Central

Bouman, Thijs; Steg, Linda; Kiers, Henk A. L.

2018-01-01

Four human values are considered to underlie individuals’ environmental beliefs and behaviors: biospheric (i.e., concern for environment), altruistic (i.e., concern for others), egoistic (i.e., concern for personal resources) and hedonic values (i.e., concern for pleasure and comfort). These values are typically measured with an adapted and shortened version of the Schwartz Value Survey (SVS), to which we refer as the Environmental-SVS (E-SVS). Despite being well-validated, recent research has indicated some concerns about the SVS methodology (e.g., comprehensibility, self-presentation biases) and suggested an alternative method of measuring human values: The Portrait Value Questionnaire (PVQ). However, the PVQ has not yet been adapted and applied to measure values most relevant to understand environmental beliefs and behaviors. Therefore, we tested the Environmental-PVQ (E-PVQ) – a PVQ variant of E-SVS –and compared it with the E-SVS in two studies. Our findings provide strong support for the validity and reliability of both the E-SVS and E-PVQ. In addition, we find that respondents slightly preferred the E-PVQ over the E-SVS (Study 1). In general, both scales correlate similarly to environmental self-identity (Study 1), energy behaviors (Studies 1 and 2), pro-environmental personal norms, climate change beliefs and policy support (Study 2). Accordingly, both methodologies show highly similar results and seem well-suited for measuring human values underlying environmental behaviors and beliefs. PMID:29743874

A Vision for the Future of Environmental Research: Creating Environmental Intelligence Centers

NASA Astrophysics Data System (ADS)

Barron, E. J.

2002-12-01

The nature of the environmental issues facing our nation demands a capability that allows us to enhance economic vitality, maintain environmental quality, and limit threats to life and property through more fundamental understanding of the Earth. It is "advanced" knowledge of how the system may respond that gives environmental information most of its power and utility. This fact is evident in the demand for new forecasting products, involving air quality, energy demand, water quality and quantity, ultraviolet radiation, and human health indexes. As we demonstrate feasibility and benefit, society is likely to demand a growing number of new operational forecast products on prediction time scales of days to decades into the future. The driving forces that govern our environment are widely recognized, involving primarily weather and climate, patterns of land use and land cover, and resource use with its associated waste products. The importance of these driving forces has been demonstrated by a decade of research on greenhouse gas emissions, ozone depletion and deforestation, and through the birth of Earth System Science. But, there are also major challenges. We find the strongest intersection between human activity, environmental stresses, system interactions and human decision-making in regional analysis coupled to larger spatial scales. In addition, most regions are influenced by multiple-stresses. Multiple, cumulative, and interactive stresses are clearly the most difficult to understand and hence the most difficult to assess and to manage. Currently, we are incapable of addressing these issues in a truly integrated fashion at global scales. The lack of an ability to combine global and regional forcing and to assess the response of the system to multiple stresses at the spatial and temporal scales of interest to humans limits our ability to assess the impacts of specific human perturbations, to assess advantages and risks, and to enhance economic and societal well

Environmental Science and Research Foundation annual technical report to DOE-ID, January , 1995--December 31, 1995

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

NONE

1996-06-01

The foundation conducts an environmental monitoring and surveillance program over an area covering much of the upper Snake River Plain and provide environmental education and support services related to INEL natural resource issues. Also, the foundation, with its university affiliates, conducts ecological and radioecological research on the Idaho National Environmental Research Park. This research benefits major DOE-ID programs including waste management, environmental restoration, spent nuclear fuels, and land management issues. Major accomplishments during CY1995 can be divided into five categories: environmental surveillance program, environmental education, environmental services and support, ecological risk assessment, and research benefitting the DOE-ID mission.

Qualitative Environmental Health Research: An Analysis of the Literature, 1991–2008

PubMed Central

Scammell, Madeleine Kangsen

2010-01-01

Background Recent articles have advocated for the use of qualitative methods in environmental health research. Qualitative research uses nonnumeric data to understand people’s opinions, motives, understanding, and beliefs about events or phenomena. Objective In this analysis of the literature, I report the use of qualitative methods and data in the study of the relationship between environmental exposures and human health. Data sources A primary search on ISI Web of Knowledge/Web of Science for peer-reviewed journal articles dated from 1991 through 2008 included the following three terms: qualitative, environ*, and health. Inclusion and exclusion criteria are described. Data extraction Searches resulted in 3,155 records. Data were extracted and findings of articles analyzed to determine where and by whom qualitative environmental health research is conducted and published, the types of methods and analyses used in qualitative studies of environmental health, and the types of information qualitative data contribute to environmental health. Data synthesis Ninety-one articles met inclusion criteria. These articles were published in 58 different journals, with a maximum of eight for a single journal. The results highlight a diversity of disciplines and techniques among researchers who used qualitative methods to study environmental health, with most studies relying on one-on-one interviews. Details of the analyses were absent from a large number of studies. Nearly all of the studies identified increased scientific understanding of lay perceptions of environmental health exposures. Discussion and conclusions Qualitative data are published in traditionally quantitative environmental health studies to a limited extent. However, this analysis demonstrates the potential of qualitative data to improve understanding of complex exposure pathways, including the influence of social factors on environmental health, and health outcomes. PMID:20421191

The Delaware River Basin Collaborative Environmental Monitoring and Research Initiative: Foundation Document

Treesearch

Peter S. Murdoch; Jennifer C. Jenkins; Richard A. Birdsey

2008-01-01

The U.S. Forest Service, the U.S. Geological Survey, and the National Park Service formed the Collaborative Environmental Monitoring and Research Initiative (CEMRI) to test strategies for integrated environmental monitoring among the agencies. The initiative combined monitoring and research efforts of the participating Federal programs to evaluate health and...

The concept of externality: Implications for TVA Environmental Research Center

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

Foster, T.H.

1994-06-01

Pollution of the environment is a result of the economic activities of production and consumption. And although the market system is touted as the superior method of organizing and operating an economic system, society frequently is dissatisfied with some of the side effects. In these cases of market failure, a cry for intervention often is raised to obtain more socially-desirable solutions. Environmental pollution is one symptom of market failure. If the TVA Environmental Research Center is to focus on defining solutions to environmental problems and designing policy options for implementing such solutions, its efforts should benefit from an understanding ofmore » why the market fails and how it may be adjusted to produce more socially-desirable results. The purposes of this report are to: (1) promote an appreciation for and understanding of the concept of externality; (2) demonstrate the utility of the concept in the design and packaging of policy and technology for improved environmental performance; (3) provide a brief summary of the externality valuation issue currently being debated by the electric power industry; and (4) identify environmental research and development agenda opportunities or strategic considerations suggested for the Center by this review.« less

Environmental Education Research in Southern Africa: Dilemmas of Interpretation

ERIC Educational Resources Information Center

Gough, Annette; Gough, Noel

2004-01-01

These multiple framings of our reflections on environmental education research in southern Africa are written as dilemmas of interpretation that aim to disrupt any temptation to generalise or essentialise its qualities and characteristics. Recognising that research is a textual practice, we use J. M. Coetzee's portrayal of the dilemmas faced by…

Reflexive Research Ethics for Environmental Health and Justice: Academics and Movement-Building

PubMed Central

Cordner, Alissa; Ciplet, David; Brown, Phil; Morello-Frosch, Rachel

2012-01-01

Community-engaged research on environmental problems has reshaped researcher-participant relationships, academic-community interaction, and the role of community partners in human subjects protection and ethical oversight. We draw on our own and others’ research collaborations with environmental health and justice social movement organizations to discuss the ethical concerns that emerge in community-engaged research. In this paper we introduce the concept of reflexive research ethics: ethical guidelines and decision-making principles that depend on continual reflexivity concerning the relationships between researchers and participants. Seeing ethics in this way can help scientists conduct research that simultaneously achieves a high level of professional conduct and protects the rights, well-being, and autonomy of both researchers and the multiple publics affected by research. We highlight our research with community-based organizations in Massachusetts, California, and Alaska, and discuss the potential impacts of the community or social movement on the research process and the potential impacts of research on community or social movement goals. We conclude by discussing ways in which the ethical concerns that surface in community-engaged research have led to advances in ethical research practices. This type of work raises ethical questions whose answers are broadly relevant for social movement, environmental, and public health scholars. PMID:22690133

The age of citizen science: Stimulating future environmental research

NASA Astrophysics Data System (ADS)

Burgess, S. N.

2010-12-01

Public awareness of the state of the ocean is growing with issues such as climate change, over-harvesting, marine pollution, coral bleaching, ocean acidification and sea level rise appearing regularly in popular media outlets. Society is also placing greater value on the range of ecosystem services the ocean provides. This increased consciousness of environmental change due to a combination of anthropogenic activities and impacts from climate change offers scientists the opportunity of engaging citizens in environmental research. The term citizen science refers to scientific research carried out by citizens and led by professionals, which involves large scale data collection whilst simultaneously engaging and educating those who participate. Most projects that engage citizen scientists have been specifically designed to provide an educational benefit to the volunteer and benefit the scientific inquiry by collecting extensive data sets over large geographical areas. Engaging the public in environmental science is not a new concept and successful projects (such as the Audobon Christmas Bird Count and Earthwatch) have been running for several decades resulting in hundreds of thousands of people conducting long-term field research in partnership with scientists based at universities worldwide. The realm of citizen science projects is continually expanding, with public engagement options ranging from science online; to backyard afternoon studies; to fully immersive experiential learning projects running for weeks at a time. Some organisations, such as Earthwatch also work in partnership with private industry; giving scientists access to more funding opportunities than those avenues traditionally available. These scientist -industry partnerships provide mutual benefits as the results of research projects in environments such as coastal ecosystems feed directly back into business risk strategies; for example mitigating shoreline erosion, storm surges, over fishing and

Bidirectional quantum teleportation of unknown photons using path-polarization intra-particle hybrid entanglement and controlled-unitary gates via cross-Kerr nonlinearity

NASA Astrophysics Data System (ADS)

Heo, Jino; Hong, Chang-Ho; Lim, Jong-In; Yang, Hyung-Jin

2015-05-01

We propose an arbitrary controlled-unitary (CU) gate and a bidirectional quantum teleportation (BQTP) scheme. The proposed CU gate utilizes photonic qubits (photons) with cross-Kerr nonlinearities (XKNLs), X-homodyne detectors, and linear optical elements, and consists of the consecutive operation of a controlled-path (C-path) gate and a gathering-path (G-path) gate. It is almost deterministic and feasible with current technology when a strong coherent state and weak XKNLs are employed. Based on the CU gate, we present a BQTP scheme that simultaneously teleports two unknown photons between distant users by transmitting only one photon in a path-polarization intra-particle hybrid entangled state. Consequently, it is possible to experimentally implement BQTP with a certain success probability using the proposed CU gate. Project supported by the Ministry of Science, ICT&Future Planning, Korea, under the C-ITRC (Convergence Information Technology Research Center) Support program (NIPA-2013-H0301-13-3007) supervised by the National IT Industry Promotion Agency.

TOWARD GREATER IMPLEMENTATION OF THE EXPOSOME RESEARCH PARADIGM WITHIN ENVIRONMENTAL EPIDEMIOLOGY

PubMed Central

Stingone, Jeanette A.; Buck Louis, Germaine M.; Nakayama, Shoji F.; Vermeulen, Roel C. H.; Kwok, Richard K.; Cui, Yuxia; Balshaw, David M.; Teitelbaum, Susan L.

2017-01-01

Investigating a single environmental exposure in isolation does not reflect the actual human exposure circumstance nor does it capture the multifactorial etiology of health and disease. The exposome, defined as the totality of environmental exposures from conception onward, may advance our understanding of environmental contributors to disease by more fully assessing the multitude of human exposures across the life course. Implementation into studies of human health has been limited, in part owing to theoretical and practical challenges including a lack of infrastructure to support comprehensive exposure assessment, difficulty in differentiating physiologic variation from environmentally induced changes, and the need for study designs and analytic methods that accommodate specific aspects of the exposome, such as high-dimensional exposure data and multiple windows of susceptibility. Recommendations for greater data sharing and coordination, methods development, and acknowledgment and minimization of multiple types of measurement error are offered to encourage researchers to embark on exposome research to promote the environmental health and well-being of all populations. PMID:28125387

Material research for environmental sustainability in Thailand: current trends

PubMed Central

Niranatlumpong, Panadda; Ramangul, Nudjarin; Dulyaprapan, Pongsak; Nivitchanyong, Siriluck; Udomkitdecha, Werasak

2015-01-01

This article covers recent developments of material research in Thailand with a focus on environmental sustainability. Data on Thailand’s consumption and economic growth are briefly discussed to present a relevant snapshot of its economy. A selection of research work is classified into three topics, namely, (a) resource utilization, (b) material engineering and manufacturing, and (c) life cycle efficiency. Material technologies have been developed and implemented to reduce the consumption of materials, energy, and other valuable resources, thus reducing the burden we place on our ecological system. At the same time, product life cycle study allows us to understand the extent of the environmental impact we impart to our planet. PMID:27877788

Optical proposals for controlled delayed-choice experiment based on weak cross-Kerr nonlinearities

NASA Astrophysics Data System (ADS)

Dong, Li; Lin, Yan-Fang; Li, Qing-Yang; Xiu, Xiao-Ming; Dong, Hai-Kuan; Gao, Ya-Jun

2017-05-01

Employing polarization modes of a photon, we propose two theoretical proposals to exhibit the wave-particle duality of the photon with the assistance of weak cross-Kerr nonlinearities. The first proposal is a classical controlled delayed-choice experiment (that is, Wheeler's delayed-choice experiment), where we can observe selectively wave property or particle property of the photon relying on the experimenter's selection, whereas the second proposal is a quantum controlled delayed-choice experiment, by which the mixture phenomenon of a wave and a particle will be exhibited. Both of them can be realized with near-unity probability and embody the charming characteristics of quantum mechanics. The employment of the mature techniques and simple operations (e.g., Homodyne measurement, classical feed forward, and single-photon transformations) provides the feasibility of the delayed-choice experiment proposals presented here.

Environmental and occupational health research and training needs in Colombia: A Delphi study

PubMed Central

Rodríguez-Villamizar, Laura A.; González, Beatriz Elena; Vera, Lina María; Patz, Jonathan; Bautista, Leonelo E.

2015-01-01

Introduction Environmental factors contribute with 16% of the burden of disease in Colombia. A main obstacle in implementing national and regional environmental and occupational health policies is the limited knowledge on the local ability to study and control the impact of harmful exposures on health. Objective To identify needs for research and training in environmental and occupational health in Colombia. Materials and methods We conducted a three-round hybrid Delphi study. A group of environmental and occupational health Colombian experts (n=16) from government agencies, universities, and research centers was recruited to participate in the study. Expert’s opinions on research and training needs were gathered through online questionnaires, followed by an in-person meeting. The percentage of agreement and the coefficient of variation were used to measure consensus. Results Air pollution and chemical products were considered the most important environmental and occupational exposures, due to their significant impact on chronic non-communicable diseases, such as respiratory diseases, cardiovascular diseases, and cancer. Research on the effects of outdoor air pollution on cardiovascular and respiratory diseases was considered of the greatest importance. Priority training areas included environmental and occupational health risk assessment, exposure modeling, advanced statistical methods, urban planning, occupational safety and hygiene, and epidemiology and toxicology. Conclusions These findings provide a valuable input for the definition and implementation of national environmental and occupational health policies and for the development of a regional hub aimed at strengthening the capacity for research and training in Colombia. PMID:26535742

Environmental and occupational health research and training needs in Colombia: A Delphi study.

PubMed

Rodríguez-Villamizar, Laura A; González, Beatriz Elena; Vera, Lina María; Patz, Jonathan; Bautista, Leonelo E

2015-08-01

Environmental factors contribute with 16% of the burden of disease in Colombia. A main obstacle in implementing national and regional environmental and occupational health policies is the limited knowledge on the local ability to study and control the impact of harmful exposures on health. To identify needs for research and training in environmental and occupational health in Colombia. We conducted a three-round hybrid Delphi study. A group of environmental and occupational health Colombian experts (n=16) from government agencies, universities, and research centers was recruited to participate in the study. Expert´s opinions on research and training needs were gathered through online questionnaires, followed by an in-person meeting. The percentage of agreement and the coefficient of variation were used to measure consensus. Air pollution and chemical products were considered the most important environmental and occupational exposures, due to their significant impact on chronic non-communicable diseases, such as respiratory diseases, cardiovascular diseases, and cancer. Research on the effects of outdoor air pollution on cardiovascular and respiratory diseases was considered of the greatest importance. Priority training areas included environmental and occupational health risk assessment, exposure modeling, advanced statistical methods, urban planning, occupational safety and hygiene, and epidemiology and toxicology. These findings provide a valuable input for the definition and implementation of national environmental and occupational health policies and for the development of a regional hub aimed at strengthening the capacity for research and training in Colombia.

Using local research sites to engage undergraduates in environmental science research

NASA Astrophysics Data System (ADS)

Varner, R. K.

2016-12-01

For the first time in their undergraduate experience, students in the University of New Hampshire's Techniques in Environmental Science course are immersed in learning approaches to scientific investigation that they can implement as part of their senior capstone research experience or other REU type programs. The course begins with an understanding of the value of note taking in the field and working collaboratively in groups. The students then embark upon a series of field experiences that include using both simple and complex tools for mapping elevation, species composition and above ground biomass estimates in a forest and wetland, carbon cycling through measurement of greenhouse gas exchange at both a wetland and at an organic dairy farm, assessing hydrology and water quality through both ground and surface water measurements at locations on campus, and finally analysis of atmospheric chemistry data collected locally. Over the course of a semester the students learn how to describe their methodology and the importance of their work concisely. Eventually the students are given instrumentation and a field site and learn to ask their own research question and develop their approach to answering it. This course model provides a foundation for students to pursue their capstone research experiences but also for understanding complex environmental questions such as the impact of land use change on water and air quality and carbon cycling and its role in our climate system. Students are provided a unique opportunity to address questions at field sites that are local and are part of larger research programs which allows for a larger context to place their work. This course has also been a framework for the NSF funded REU program- Northern Ecosystems Research for Undergraduates (EAR#1063037). Sallie's Fen, a wetland research site, is used as an initial field setting for students to learn techniques, build their ability to ask research questions and to plan research

Linking research and policy to ensure children's environmental health.

PubMed Central

Goldman, L R

1998-01-01

The U.S. Environmental Protection Agency (U.S. EPA) has made protecting children's environmental health its highest priority. Data on how and when children may be at risk are vital for accomplishing this goal. Recent examples of the link between research and policy include U.S. EPA actions to carry out the recommendations of the National Academy of Sciences on pesticides in children's food, reduce and prevent childhood lead poisoning, and revise national ambient air quality standards for ozone and particulate matter. Today, the Food Quality Protection Act (FQPA), which makes protecting children from pesticide residues in food a national priority, is contributing to the growing need for data for decision making. Further impetus comes from provisions in the FQPA and 1996 Safe Drinking Water Act Amendments for establishing a screening and testing program for potential risks from endocrine disruptors. Another factor is the analysis that will be required under President William J. Clinton's executive order directing all federal agencies, for the first time, to reduce environmental health and safety risks to children. Success of the U.S. international commitment to protect children is directly tied to the strength and availability of environmental data. To meet such challenges, the U.S. EPA is revising key science policies, expanding research opportunities, and adding to the public's right-to-know tools. In this dynamic climate, there are growing opportunities for the research community to play a greater role in helping ensure the well-being of children living today and in generations to come. PMID:9646049

Dispersive optical solitons and modulation instability analysis of Schrödinger-Hirota equation with spatio-temporal dispersion and Kerr law nonlinearity

NASA Astrophysics Data System (ADS)

Inc, Mustafa; Aliyu, Aliyu Isa; Yusuf, Abdullahi; Baleanu, Dumitru

2018-01-01

This paper obtains the dark, bright, dark-bright or combined optical and singular solitons to the perturbed nonlinear Schrödinger-Hirota equation (SHE) with spatio-temporal dispersion (STD) and Kerr law nonlinearity in optical fibers. The integration algorithm is the Sine-Gordon equation method (SGEM). Furthermore, the modulation instability analysis (MI) of the equation is studied based on the standard linear-stability analysis and the MI gain spectrum is got.

Conservative corrections to the innermost stable circular orbit (ISCO) of a Kerr black hole: A new gauge-invariant post-Newtonian ISCO condition, and the ISCO shift due to test-particle spin and the gravitational self-force

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

Favata, Marc

2011-01-15

The innermost stable circular orbit (ISCO) delimits the transition from circular orbits to those that plunge into a black hole. In the test-mass limit, well-defined ISCO conditions exist for the Kerr and Schwarzschild spacetimes. In the finite-mass case, there are a large variety of ways to define an ISCO in a post-Newtonian (PN) context. Here I generalize the gauge-invariant ISCO condition of Blanchet and Iyer [Classical Quantum Gravity 20, 755 (2003)] to the case of spinning (nonprecessing) binaries. The Blanchet-Iyer ISCO condition has two desirable and unexpected properties: (1) it exactly reproduces the Schwarzschild ISCO in the test-mass limit, andmore » (2) it accurately approximates the recently calculated shift in the Schwarzschild ISCO frequency due to the conservative-piece of the gravitational self-force [L. Barack and N. Sago, Phys. Rev. Lett. 102, 191101 (2009)]. The generalization of this ISCO condition to spinning binaries has the property that it also exactly reproduces the Kerr ISCO in the test-mass limit (up to the order at which PN spin corrections are currently known). The shift in the ISCO due to the spin of the test-particle is also calculated. Remarkably, the gauge-invariant PN ISCO condition exactly reproduces the ISCO shift predicted by the Papapetrou equations for a fully relativistic spinning particle. It is surprising that an analysis of the stability of the standard PN equations of motion is able (without any form of 'resummation') to accurately describe strong-field effects of the Kerr spacetime. The ISCO frequency shift due to the conservative self-force in Kerr is also calculated from this new ISCO condition, as well as from the effective-one-body Hamiltonian of Barausse and Buonanno [Phys. Rev. D 81, 084024 (2010)]. These results serve as a useful point of comparison for future gravitational self-force calculations in the Kerr spacetime.« less

PLD growth of CoPd thin films and characterization of their magnetic properties by magneto optical Kerr effect

NASA Astrophysics Data System (ADS)

Sedrpooshan, Mehran; Ahmadvand, Hossein; Ranjbar, Mehdi; Salamati, Hadi

2018-06-01

CoPd alloy thin films with different thicknesses and Co/Pd ratios have been deposited on Si (100) substrate by pulsed laser deposition (PLD). The magnetic properties were investigated by using the magneto-optical Kerr effect (MOKE) in both longitudinal and polar geometries. The results show that the films with thickness in the range of 6-24 nm, deposited at a low substrate temperature of 200 °C, are mostly magnetized in the plane of film. Higher deposition temperature forces the magnetic easy axis to orient in the perpendicular direction of the films.

Kerr microscopy studies of the effects of bending stress on galfenola)

NASA Astrophysics Data System (ADS)

Raghunath, Ganesh; Marana, Michael; Na, Suok-Min; Flatau, Alison

2014-05-01

This work deals with using a magneto-optic Kerr effect (MOKE) microscope to optically analyze the evolution of magnetic domains in a rolled and Goss textured galfenol (Fe81Ga19 + 1.0% NbC) sample when subjected to a bending stress. The initial magnetization state of the cantilevered sample was fixed along its length by a 0.3 T permanent magnet. The magnetic state was monitored with the MOKE microscope as a tip load was applied to bend the sample. The magnetic state of galfenol depends on its magneto-elastic properties. A finite element model that incorporates an energy based formulation of magnetostriction [W. D. Armstrong, J. Magn. Magn. Mater. 263(1-2), 208-218 (2003)] was used to investigate the stresses in the sample and the corresponding change in the magnetic induction as bending occurred. A qualitative comparison with the domain pictures is presented, and the experimental micromagnetic behavior results are shown to correlate well to the macro scale bending stress and magnetization results obtained in the FEM simulations.

Properties of the instantaneous ergo surface of a Kerr black hole

NASA Astrophysics Data System (ADS)

Pelavas, Nicos; Neary, Nicholas; Lake, Kayll

2001-04-01

{This paper explores properties of the instantaneous ergo surface of a Kerr black hole. The surface area is evaluated in closed form. In terms of the mass (m) and angular velocity (a), to second order in a, the area of the ergo surface is given by 16πm2 + 4πa2 (compared to the familiar 16πm2-4πa2 for the event horizon). Whereas the total curvature of the instantaneous event horizon is 4π, on the ergo surface it ranges from 4π (for a = 0) to 0 (for a = m) due to conical singularities on the axis (θ = 0,π) of deficit angle 2π(1-(1-(a/m)2)1/2). A careful application of the Gauss-Bonnet theorem shows that the ergo surface remains topologically spherical. Isometric embeddings of the ergo surface in Euclidean 3-space are defined for 0≤a/m≤1 (compared to 0≤a/m≤(3)1/2/2 for the horizon).

Environmental justice and regional inequality in southern California: implications for future research.

PubMed Central

Morello-Frosch, Rachel; Pastor, Manuel; Porras, Carlos; Sadd, James

2002-01-01

Environmental justice offers researchers new insights into the juncture of social inequality and public health and provides a framework for policy discussions on the impact of discrimination on the environmental health of diverse communities in the United States. Yet, causally linking the presence of potentially hazardous facilities or environmental pollution with adverse health effects is difficult, particularly in situations in which diverse populations are exposed to complex chemical mixtures. A community-academic research collaborative in southern California sought to address some of these methodological challenges by conducting environmental justice research that makes use of recent advances in air emissions inventories and air exposure modeling data. Results from several of our studies indicate that communities of color bear a disproportionate burden in the location of treatment, storage, and disposal facilities and Toxic Release Inventory facilities. Longitudinal analysis further suggests that facility siting in communities of color, not market-based "minority move-in," accounts for these disparities. The collaborative also investigated the health risk implications of outdoor air toxics exposures from mobile and stationary sources and found that race plays an explanatory role in predicting cancer risk distributions among populations in the region, even after controlling for other socioeconomic and demographic indicators. Although it is unclear whether study results from southern California can be meaningfully generalized to other regions in the United States, they do have implications for approaching future research in the realm of environmental justice. The authors propose a political economy and social inequality framework to guide future research that could better elucidate the origins of environmental inequality and reasons for its persistence. PMID:11929723

Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator

NASA Astrophysics Data System (ADS)

Wu, Liang; Salehi, M.; Koirala, N.; Moon, J.; Oh, S.; Armitage, N. P.

2016-12-01

Topological insulators have been proposed to be best characterized as bulk magnetoelectric materials that show response functions quantized in terms of fundamental physical constants. Here, we lower the chemical potential of three-dimensional (3D) Bi2Se3 films to ~30 meV above the Dirac point and probe their low-energy electrodynamic response in the presence of magnetic fields with high-precision time-domain terahertz polarimetry. For fields higher than 5 tesla, we observed quantized Faraday and Kerr rotations, whereas the dc transport is still semiclassical. A nontrivial Berry’s phase offset to these values gives evidence for axion electrodynamics and the topological magnetoelectric effect. The time structure used in these measurements allows a direct measure of the fine-structure constant based on a topological invariant of a solid-state system.

Time-resolved scanning Kerr microscopy of flux beam formation in hard disk write heads

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

Valkass, Robert A. J., E-mail: rajv202@ex.ac.uk; Spicer, Timothy M.; Burgos Parra, Erick

To meet growing data storage needs, the density of data stored on hard disk drives must increase. In pursuit of this aim, the magnetodynamics of the hard disk write head must be characterized and understood, particularly the process of “flux beaming.” In this study, seven different configurations of perpendicular magnetic recording (PMR) write heads were imaged using time-resolved scanning Kerr microscopy, revealing their detailed dynamic magnetic state during the write process. It was found that the precise position and number of driving coils can significantly alter the formation of flux beams during the write process. These results are applicable tomore » the design and understanding of current PMR and next-generation heat-assisted magnetic recording devices, as well as being relevant to other magnetic devices.« less

Synergetic Use of Crowdsourcing for Environmental Science Research, Applications and Education

NASA Astrophysics Data System (ADS)

Nair, U. S.; Thau, D.

2015-12-01

Environmental science research and applications often utilize information that is not readily available or routinely collected by government agencies. Whereas, the quality and quantity of environmental monitoring data is continually improving (e. g., spectral and spatial resolution of satellite imagery) contextual information needed to effectively utilize the data is sparse. Examples of such contextual information include ground truth data for land cover classification, presence/absence of species, prevalence of mosquito breeding sites and characteristics of urban land cover. Often, there are no agencies tasked with routine collection of such contextual information, which could be effectively collected through crowdsourcing. Crowdsourcing of such information, that is useful for environmental science research and applications, also provide opportunities for experiential learning at all levels of education. Appropriately designed crowdsourcing activity can be transform students from passive recipients of information to generators of knowledge. Multiple examples of synergistic use of crowdsourcing, developed by the Public Environmental Education and Research Apps (PEERA) group, at the University of Alabama in Huntsville will be presented. One example is crowdsourcing of land use and land cover (LULC) data using Open Data Kit (ODK) and associated analysis of satellite imagery using Google Earth Engine (GEE). Implementation of this activity as inquiry based learning exercise, for both middle school and for pre-service teachers will be discussed. Another example will detail the synergy between crowdsourcing for biodiversity mapping in southern India and environmental education. Other crowdsourcing activities that offer potential for synergy between research and public education will also be discussed.

Risky Substance Use Environments and Addiction: A New Frontier for Environmental Justice Research.

PubMed

Mennis, Jeremy; Stahler, Gerald J; Mason, Michael J

2016-06-18

Substance use disorders are widely recognized as one of the most pressing global public health problems, and recent research indicates that environmental factors, including access and exposure to substances of abuse, neighborhood disadvantage and disorder, and environmental barriers to treatment, influence substance use behaviors. Racial and socioeconomic inequities in the factors that create risky substance use environments may engender disparities in rates of substance use disorders and treatment outcomes. Environmental justice researchers, with substantial experience in addressing racial and ethnic inequities in environmental risk from technological and other hazards, should consider similar inequities in risky substance use environments as an environmental justice issue. Research should aim at illustrating where, why, and how such inequities in risky substance use environments occur, the implications of such inequities for disparities in substance use disorders and treatment outcomes, and the implications for tobacco, alcohol, and drug policies and prevention and treatment programs.

Risky Substance Use Environments and Addiction: A New Frontier for Environmental Justice Research

PubMed Central

Mennis, Jeremy; Stahler, Gerald J.; Mason, Michael J.

2016-01-01

Substance use disorders are widely recognized as one of the most pressing global public health problems, and recent research indicates that environmental factors, including access and exposure to substances of abuse, neighborhood disadvantage and disorder, and environmental barriers to treatment, influence substance use behaviors. Racial and socioeconomic inequities in the factors that create risky substance use environments may engender disparities in rates of substance use disorders and treatment outcomes. Environmental justice researchers, with substantial experience in addressing racial and ethnic inequities in environmental risk from technological and other hazards, should consider similar inequities in risky substance use environments as an environmental justice issue. Research should aim at illustrating where, why, and how such inequities in risky substance use environments occur, the implications of such inequities for disparities in substance use disorders and treatment outcomes, and the implications for tobacco, alcohol, and drug policies and prevention and treatment programs. PMID:27322303

Bridging Research and Environmental Regulatory Processes: The Role of Knowledge Brokers

PubMed Central

Pennell, Kelly G.; Thompson, Marcella; Rice, James W.; Senier, Laura; Brown, Phil; Suuberg, Eric

2013-01-01

Federal funding agencies increasingly require research investigators to ensure that federally-sponsored research demonstrates broader societal impact. Specifically, the National Institutes of Environmental Health Sciences (NIEHS) Superfund Research Program (SRP) requires research centers to include research translation and community engagement cores to achieve broader impacts, with special emphasis on improving environmental health policies through better scientific understanding. This paper draws on theoretical insights from the social sciences to show how incorporating knowledge brokers in research centers can facilitate translation of scientific expertise to influence regulatory processes and thus promote public health. Knowledge brokers connect academic researchers with decision-makers, to facilitate the translation of research findings into policies and programs. In this article, we describe the stages of the regulatory process and highlight the role of the knowledge broker and scientific expert at each stage. We illustrate the cooperation of knowledge brokers, scientific experts and policymakers using a case from the Brown University (Brown) SRP. We show how the Brown SRP incorporated knowledge brokers to engage scientific experts with regulatory officials around the emerging public health problem of vapor intrusion. In the Brown SRP, the knowledge broker brought regulatory officials into the research process, to help scientific experts understand the critical nature of this emerging public health threat, and helped scientific experts develop a research agenda that would inform the development of timely measures to protect public health. Our experience shows that knowledge brokers can enhance the impact of environmental research on public health by connecting policy decision-makers with scientific experts at critical points throughout the regulatory process. PMID:24083557

A perspective of Genes and Environment for the development of environmental mutagen research in Asia.

PubMed

Yagi, Takashi

2017-01-01

Two years have passed since the Japanese Environmental Society (JEMS) made the official journal Genes and Environment (G&E) open access. Current subjects on environmental mutagen research to further advance this field are described herein, and the roles of JEMS and G&E are discussed. Various important subjects are being investigated in current research fields such as severe environmental pollution in Asian countries; the identification of new hazardous substances and elucidation of mutation mechanisms using newly developed techniques; the development of new genotoxicity assays including in silico predictions using information technology and artificial intelligence as well as bioassays. International exchange by scientists is important for advancing these research fields through international conferences such as the 12th International Conference and 5th Asian Congress on Environmental Mutagens and the 7th International Workshop on Genotoxicity Testing that will be held in 2017. G&E provides a common platform for high quality environmental mutagen research, contributes to the dissemination of Asian environmental mutagen research, and potentiates the level of research being conducted.

[Advance research on association between environmental compound and parkinson's disease].

PubMed

Li, X T; Cai, D F

2016-10-06

Parkinson's disease(PD)was the second most common neurodegenerative disorder after Alzheimer's disease. Incidence of PD was ascending year by year. The etiology of PD is poorly understood, involving aging, genetic and environmental factors. Recently, environmental compound had attracted more and more research interest. Studies and extrapolation from epidemiology, animal experiments and cell culture suggested that environmental compound had involved in the molecular mechanisms including mitochondrial dysfunction, oxidative stress, microglia activation, abnormal aggregation of α-synuclein and autophagy damage ,which seemed to increase PD risk.

Program director`s overview report for the Office of Health & Environmental Research

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

Gilbert, D.

1994-02-01

LBL performs basic and applied research and develops technologies in support of the Office of Health and Environmental Research`s mission to explore and mitigate the long-term health and environmental consequences of energy use and to advance solutions to major medical challenges. The ability of the Laboratory to engage in this mission depends upon the strength of its core competencies. In addition, there are several key capabilities that are cross-cutting, or underlie, many of the core competencies. Attention is focused on the following: Facilities and resources; research management practices; research in progress; program accomplishments and research highlights; program orientation; work formore » non-OHER organizations DOE; critical issues; and resource orientation.« less

Description of the terrestrial ecology of the Oak Ridge Environmental Research Park

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

Kitchings, T.; Mann, L.K.

1976-10-01

The Environmental Sciences Division at Oak Ridge National Laboratory has begun to develop research and administrative foundations necessary to establish and operate an Environmental Research Park (ERP) on the Energy Research and Development Administration Reservation at Oak Ridge, Tennessee. Important in developing a functional research area is a description and inventory of the species and ecosystems which comprise the Research Park. This report describes some of the floral and faunal components of the Oak Ridge Reservation. Emphasis is placed on the relationship of faunal communities to the vegetation type in which they occur. Unique vegetational areas and rare and endangeredmore » species are also discussed.« less

Ecological research and environmental management: We need different interfaces based on different knowledge types.

PubMed

Gosselin, Frédéric; Cordonnier, Thomas; Bilger, Isabelle; Jappiot, Marielle; Chauvin, Christophe; Gosselin, Marion

2018-04-25

The role of ecological science in environmental management has been discussed by many authors who recognize that there is a persistent gap between ecological science and environmental management. Here we develop theory through different perspectives based on knowledge types, research categories and research-management interface types, which we combine into a common framework. To draw out insights for bridging this gap, we build our case by:We point out the complementarities as well as the specificities and limitations of the different types of ecological research, ecological knowledge and research-management interfaces, which is of major importance for environmental management and research policies. Copyright © 2018 Elsevier Ltd. All rights reserved.

76 FR 47611 - Advisory Committee for Environmental Research And Education; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-05

... NATIONAL SCIENCE FOUNDATION Advisory Committee for Environmental Research And Education; Notice of Meeting In accordance with the Federal Advisory Committee Act (Pub. L. 92- 463, as amended), the National Science Foundation announces the following meeting: Name: Advisory Committee for Environmental Research and Education (9487). Dates:September ...

75 FR 50009 - Advisory Committee for Environmental Research and Education; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-16

... NATIONAL SCIENCE FOUNDATION Advisory Committee for Environmental Research and Education; Notice of... and Education (9487). Dates: September 8, 2010-September 9, 2010, 8:30 a.m.-1 p.m. Place: Stafford I... support for environmental research and education. Agenda September 8, 2010 Update on recent NSF...

Early Environmental Field Research Career Exploration: An Analysis of Impacts on Precollege Apprentices

PubMed Central

Flowers, Susan K.; Beyer, Katherine M.; Pérez, Maria; Jeffe, Donna B.

2016-01-01

Research apprenticeships offer opportunities for deep understanding of scientific practice, transparency about research careers, and possible transformational effects on precollege youth. We examined two consecutive field-based environmental biology apprenticeship programs designed to deliver realistic career exploration and connections to research scientists. The Shaw Institute for Field Training (SIFT) program combines introductory field-skills training with research assistance opportunities, and the subsequent Tyson Environmental Research Fellowships (TERF) program provides immersive internships on university field station–based research teams. In a longitudinal mixed-methods study grounded in social cognitive career theory, changes in youth perspectives were measured during program progression from 10th grade through college, evaluating the efficacy of encouraging career path entry. Results indicate SIFT provided self-knowledge and career perspectives more aligned with reality. During SIFT, differences were found between SIFT-only participants compared with those who progressed to TERF. Transition from educational activities to fieldwork with scientists was a pivotal moment at which data showed decreased or increased interest and confidence. Continuation to TERF provided deeper relationships with role models who gave essential early-career support. Our study indicates the two-stage apprenticeship structure influenced persistence in pursuit of an environmental research career pathway. Recommendations for other precollege environmental career–exploration programs are presented. PMID:27909017

Study of the Induced Anisotropy in Field Annealed Hitperm Alloys by Mössbauer Spectroscopy and Kerr Microscopy

NASA Astrophysics Data System (ADS)

Blázquez, J. S.; Marcin, J.; Andrejka, F.; Franco, V.; Conde, A.; Skorvanek, I.

2016-08-01

Samples of Fe39Co39Nb6B15Cu1 alloy were nanocrystallized under zero field annealing (ZF) and transverse field annealing (TF) conditions. A reduction in coercivity for TF samples with respect to ZF sample (16 and 45 A/m, respectively) is observed. Kerr microscopy images show a well-defined parallel domain structure, transversally oriented to the ribbon axis for the TF sample unlike for the ZF sample, for which a complex pattern is observed with large and small domains at the surface of the ribbon. Although Mössbauer spectra are clearly different for the two studied samples, Mössbauer studies confirm that there is no significant difference between the hyperfine field distributions of TF and ZF samples but only the relative intensity of the 2nd and 3rd lines A 23 (related to the angle between the gamma radiation and the magnetic moments, α). However, for TF annealed samples α = 90 deg ( A 23 = 4), indicating that the magnetic moments lay on the plane of the ribbon in agreement with the well-defined domain structure observed by Kerr microscopy, ZF annealed samples show A 23 = 1.8. This value is close to that of a random orientation ( A 23 = 2) but smaller, indicating a slight preference for out of plane orientations. Moreover, it is clearly smaller than that of the as-cast amorphous samples A 23 = 2.8, with a preference to in-plane orientations. The application of the law of approach to saturation yields a larger effect of the inhomogeneities in ZF sample with respect to TF one.

The sign of the polarizability anisotropy of polar molecules is obtained from the terahertz Kerr effect

NASA Astrophysics Data System (ADS)

Kampfrath, Tobias; Wolf, Martin; Sajadi, Mohsen

2018-01-01

The terahertz Kerr effect (TKE) of polar molecular vapors is reported. The birefringence signal of fluoroform appears with opposite polarity compared to acetonitrile and water. This behavior is a hallmark of the opposite sign of a new molecular polarizability anisotropy ΔαTKE =αzz - (αxx +αyy) / 2 , with αzz being the polarizability along the permanent dipole moment. As the excitation of the rotational states orients the permanent dipoles along the terahertz electric field, the orientation is translated into an optical birefringence proportional to ΔαTKE . Thus, the sign of ΔαTKE is imprinted onto the TKE signal, providing novel insights into the polarizability tensor of water.

An asymptotically consistent approximant for the equatorial bending angle of light due to Kerr black holes

NASA Astrophysics Data System (ADS)

Barlow, Nathaniel S.; Weinstein, Steven J.; Faber, Joshua A.

2017-07-01

An accurate closed-form expression is provided to predict the bending angle of light as a function of impact parameter for equatorial orbits around Kerr black holes of arbitrary spin. This expression is constructed by assuring that the weak- and strong-deflection limits are explicitly satisfied while maintaining accuracy at intermediate values of impact parameter via the method of asymptotic approximants (Barlow et al 2017 Q. J. Mech. Appl. Math. 70 21-48). To this end, the strong deflection limit for a prograde orbit around an extremal black hole is examined, and the full non-vanishing asymptotic behavior is determined. The derived approximant may be an attractive alternative to computationally expensive elliptical integrals used in black hole simulations.

Performance Evaluation Tests for Environmental Research (PETER): evaluation of 114 measures

NASA Technical Reports Server (NTRS)

Bittner, A. C. Jr; Carter, R. C.; Kennedy, R. S.; Harbeson, M. M.; Krause, M.

1986-01-01

The goal of the Performance Evaluation Tests for Environmental Research (PETER) Program was to identify a set of measures of human capabilities for use in the study of environmental and other time-course effects. 114 measures studied in the PETER Program were evaluated and categorized into four groups based upon task stability and task definition. The Recommended category contained 30 measures that clearly obtained total stabilization and had an acceptable level of reliability efficiency. The Acceptable-But-Redundant category contained 15 measures. The 37 measures in the Marginal category, which included an inordinate number of slope and other derived measures, usually had desirable features which were outweighed by faults. The 32 measures in the Unacceptable category had either differential instability or weak reliability efficiency. It is our opinion that the 30 measures in the Recommended category should be given first consideration for environmental research applications. Further, it is recommended that information pertaining to preexperimental practice requirements and stabilized reliabilities should be utilized in repeated-measures environmental studies.

THE CENTER FOR URBAN ENVIRONMENTAL RESEARCH AND EDUCATION - UMBC

EPA Science Inventory

EPA GRANT NUMBER: R831058
Title: The Center for Urban Environmental Research and Education - UMBC
Investigator: Claire Welty
Institution: University of Maryland - Baltimore County
EPA Project Officer: Brandon Jones
Project...

Public, environmental, and occupational health research activity in Arab countries: bibliometric, citation, and collaboration analysis.

PubMed

Sweileh, Waleed M; Zyoud, Sa'ed H; Al-Jabi, Samah W; Sawalha, Ansam F

2015-01-01

The objective of this study was to analyze quantity, assess quality, and investigate international collaboration in research from Arab countries in the field of public, environmental and occupational health. Original scientific articles and reviews published from the 22 Arab countries in the category "public, environmental & occupational health" during the study period (1900 - 2012) were screened using the ISI Web of Science database. The total number of original and review research articles published in the category of "public, environmental & occupational health" from Arab countries was 4673. Main area of research was tropical medicine (1862; 39.85%). Egypt with 1200 documents (25.86%) ranked first in quantity and ranked first in quality of publications (h-index = 51). The study identified 2036 (43.57%) documents with international collaboration. Arab countries actively collaborated with authors in Western Europe (22.91%) and North America (21.04%). Most of the documents (79.9%) were published in public health related journals while 21% of the documents were published in journals pertaining to prevention medicine, environmental, occupational health and epidemiology. Research in public, environmental and occupational health in Arab countries is in the rise. Public health research was dominant while environmental and occupation health research was relatively low. International collaboration was a good tool for increasing research quantity and quality.

Kerr-gated picosecond Raman spectroscopy and Raman photon migration of equine bone tissue with 400-nm excitation

NASA Astrophysics Data System (ADS)

Morris, Michael D.; Goodship, Allen E.; Draper, Edward R. C.; Matousek, Pavel; Towrie, Michael; Parker, Anthony W.

2004-07-01

We show that Raman spectroscopy with visible lasers, even in the deep blue is possible with time-gated Raman spectroscopy. A 4 picosec time gate allows efficient fluorescence rejection, up to 1000X, and provides almost background-free Raman spectra with low incident laser power. The technology enables spectroscopy with better than 10X higher scattering efficiency than is possible with the NIR (785 nm and 830 nm) lasers that are conventionally used. Raman photon migration is shown to allow depth penetration. We show for the first time that Kerr-gated Raman spectra of bone tissue with blue laser excitation enables both fluorescence rejection and depth penetration.

Sensory and Textural Characteristics of Noodle Made of Ganyong Flour (Canna edulis Kerr.) and Arenga Starch (Arenga pinnata Merr.)

NASA Astrophysics Data System (ADS)

Herawati, ERN; Ariani, D.; Miftakhussolikhah; Yosieto, E.; Angwar, M.; Pranoto, Y.

2017-12-01

Ganyong (Canna edulis Kerr) is a local tuber which highest amount of starch content, but has not been fully utilized well at present. One way to improve the usefulness of canna is to process it into noodle, but it needs arenga starch which has high amylose content. The aim of this research was to study the sensory and textural properties of noodle made from canna flour and arenga starch. Research methodologies consist of: (i) characterization of canna flour and arenga starch, (ii) noodle production, and (iii) characterization sensory and textural properties of the noodle. Noodle was made with five ratio variations of canna flour and arenga starch, i.e. 100:0; 75:25; 50:50; 25:75; and 0:100. Sensory analysis was done by hedonic scoring method with attributes : color, stickiness, elasticity, firmness, surface smoothness and overall liking. Textural properties analyses consist of tensile strength, elongation, and stickiness measurements. The results showed that canna flour and arenga starch can be used in noodle making process. Noodle with 25% of canna flour was the most favored product and has the best textural properties. Factors which affect textural properties of product are the amylose and amylopectin amount in each starch. Tensile strength, elongation, and stickiness measurements of noodle with 25% of canna flour were 0,13 N; 41,61%; and 0,0115N respectively.

Research on System Coherence Evolution of Different Environmental Models

NASA Astrophysics Data System (ADS)

Zhang, Si-Qi; Lu, Jing-Bin; Li, Hong; Liu, Ji-Ping; Zhang, Xiao-Ru; Liu, Han; Liang, Yu; Ma, Ji; Liu, Xiao-Jing; Wu, Xiang-Yao

2018-04-01

In this paper, we have studied the evolution curve of two-level atomic system that the initial state is excited state. At the different of environmental reservoir models, which include the single Lorentzian, ideal photon band-gap, double Lorentzian and square Lorentzian reservoir, we researched the influence of these environmental reservoir models on the evolution of energy level population. At static no modulation, comparing the four environmental models, the atomic energy level population oscillation of square Lorentzian reservoir model is fastest, and the atomic system decoherence is slowest. Under dynamic modulation, comparing the photon band-gap model with the single Lorentzian reservoir model, no matter what form of dynamic modulation, the time of atoms decay to the ground state is longer for the photonic band-gap model. These conclusions make the idea of using the environmental change to modulate the coherent evolution of atomic system become true.

Measurement of nonlinear optical refraction of composite material based on sapphire with silver by Kerr-lens autocorrelation method.

PubMed

Yu, Xiang-xiang; Wang, Yu-hua

2014-01-13

Silver nanoparticles synthesized in a synthetic sapphire matrix were fabricated by ion implantation using the metal vapor vacuum arc ion source. The optical absorption spectrum of the Ag: Al2O3 composite material has been measured. The analysis of the supercontinuum spectrum displayed the nonlinear refractive property of this kind of sample. Nonlinear optical refraction index was identified at 800 nm excitation using the Kerr-lens autocorrelation (KLAC) technique. The spectrum showed that the material possessed self-defocusing property (n(2) = -1.1 × 10(-15) cm(2)W). The mechanism of nonlinear refraction has been discussed.

Philosophical Hermeneutics and Critical Pedagogy in Environmental Education Research and Practice

ERIC Educational Resources Information Center

Iared, Valéria Ghisloti; Di Tullio, Ariane; Payne, Phillip G.; Torres de Oliveira, Haydée

2015-01-01

The contributions and challenges of Gadamer's philosophical hermeneutics and Freire's critical pedagogy to research and practice in environmental education are considered. We present the authors' main concepts and relate them to the principles of critical environmental education that have guided our work in Brazil. Although a raft of current…

Far-infrared Kerr rotation spectroscopy of graphite and multilayer graphene

NASA Astrophysics Data System (ADS)

Levallois, Julien; Tran, Michaël; Kuzmenko, Alexey

2012-02-01

Graphite attracts much attention nowadays as a reference 3D material for graphene. Since the early measurements of the cyclotron effect in graphite over fifty years ago [1], a satisfactory quantitative description of this spectacular phenomenon is missing. The analysis of magneto-optical data was hindered either by a limited set of the used photon energies or by the lack of the optical selectivity between electrons and holes. We overcome this issue by measuring the far-infrared magneto-optical Kerr rotation spectra [2] and achieve a highly accurate unified microscopic description of all spectra in a broad range of magnetic fields (0.5 -- 7 T) by taking rigorously the c-axis band dispersion and the trigonal warping into account. We find that the second- and the forth-order cyclotron harmonics are optically almost as strong as the fundamental cyclotron resonance even at high fields. The same effects are expected to strongly influence the magneto-optical spectra of Bernal stacked multilayer graphene and therefore play a major role in the respective applications. [4pt] [1] J. K. Galt, W.A. Yager and H.W. Dail Jr., Phys. Rev. 103, 1586 (1956) [2] J. Levallois, M.K. Tran and A. B. Kuzmenko, arXiv:1110.2754v2; submitted.

Hidden symmetries for ellipsoid-solitonic deformations of Kerr-Sen black holes and quantum anomalies

NASA Astrophysics Data System (ADS)

Vacaru, Sergiu I.

2013-02-01

We prove the existence of hidden symmetries in the general relativity theory defined by exact solutions with generic off-diagonal metrics, nonholonomic (non-integrable) constraints, and deformations of the frame and linear connection structure. A special role in characterization of such spacetimes is played by the corresponding nonholonomic generalizations of Stackel-Killing and Killing-Yano tensors. There are constructed new classes of black hole solutions and we study hidden symmetries for ellipsoidal and/or solitonic deformations of "prime" Kerr-Sen black holes into "target" off-diagonal metrics. In general, the classical conserved quantities (integrable and not-integrable) do not transfer to the quantized systems and produce quantum gravitational anomalies. We prove that such anomalies can be eliminated via corresponding nonholonomic deformations of fundamental geometric objects (connections and corresponding Riemannian and Ricci tensors) and by frame transforms.

The Nature of the Dielectric Response of Methanol Revealed by the Terahertz Kerr Effect.

PubMed

Kampfrath, Tobias; Campen, R Kramer; Wolf, Martin; Sajadi, Mohsen

2018-03-15

The dielectric response of liquids in the terahertz (THz) and sub-THz frequency range arises from low-energy collective molecular motions, which are often strongly influenced by intermolecular interactions. To shed light on the microscopic origin of the THz dielectric response of the simplest alcohol, methanol, we resonantly excite this liquid with an intense THz electric-field pulse and monitor the relaxation of the induced optical birefringence. We find a unipolar THz-Kerr-effect signal which, in contrast to aprotic polar liquids, shows a weak coupling between the THz electric field and the permanent molecular dipole moment of the liquid. We assign this weak coupling to the restricted translational rather than rotational nature of the excited mode. Our approach opens a new avenue to the assignment of the dielectric spectrum of liquids to a microscopic origin.

Animal Encounters in Environmental Education Research: Responding to the "Question of the Animal"

ERIC Educational Resources Information Center

Oakley, Jan; Watson, Gavan P. L.; Russell, Constance L.; Cutter-Mackenzie, Amy; Fawcett, Leesa; Kuhl, Gail; Russell, Joshua; van der Waal, Marlon; Warkentin, Traci