WorldWideScience

Sample records for rapidly responding kerr

  1. Policy options to respond to rapid climate change

    NARCIS (Netherlands)

    Swart, R.J.; Marinova, N.A.; Bakker, S.; Tilburg, van X.

    2009-01-01

    Ongoing research on climate change indicates that we cannot rule out the possibility of extreme climatic changes, beyond current IPCC scenarios. The thinking about policy responses to address these risks is still in its infancy. This study explores the possibilities for responding to extreme

  2. Researchers rapidly respond to submarine activity at Loihi Volcano, Hawaii

    Science.gov (United States)

    The 1996 Loihi Science Team

    The largest swarm of earthquakes ever observed at a Hawaiian volcano occurred at Loihi Seamount during July and early August 1996. The earthquake activity formed a large summit pit crater similar to those observed at Kilauea, and hydrothermal activity led to the formation of intense hydrothermal plumes in the ocean surrounding the summit. To investigate this event, the Rapid Response Cruise (RRC) was dispatched to Loihi in early August and two previously planned LONO cruises (named for a Hawaiian warrior god) sailed in September and October on the R/V Kaimikai-O-Kanaloa. Calm weather and a newly refurbished ship provided excellent opportunities for documenting the volcanic, hydrothermal plume, vent, and biological activities associated with the earthquake swarm.

  3. Marine assemblages respond rapidly to winter climate variability.

    Science.gov (United States)

    Morley, James W; Batt, Ryan D; Pinsky, Malin L

    2017-07-01

    Even species within the same assemblage have varied responses to climate change, and there is a poor understanding for why some taxa are more sensitive to climate than others. In addition, multiple mechanisms can drive species' responses, and responses may be specific to certain life stages or times of year. To test how marine species respond to climate variability, we analyzed 73 diverse taxa off the southeast US coast in 26 years of scientific trawl survey data and determined how changes in distribution and biomass relate to temperature. We found that winter temperatures were particularly useful for explaining interannual variation in species' distribution and biomass, although the direction and magnitude of the response varied among species from strongly negative, to little response, to strongly positive. Across species, the response to winter temperature varied greatly, with much of this variation being explained by thermal preference. A separate analysis of annual commercial fishery landings revealed that winter temperatures may also impact several important fisheries in the southeast United States. Based on the life stages of the species surveyed, winter temperature appears to act through overwinter mortality of juveniles or as a cue for migration timing. We predict that this assemblage will be responsive to projected increases in temperature and that winter temperature may be broadly important for species relationships with climate on a global scale. © The Authors Global Change Biology Published by John Wiley & Sons Ltd.

  4. Fast plunges into Kerr black holes

    Energy Technology Data Exchange (ETDEWEB)

    Hadar, Shahar [Racah Institute of Physics, Hebrew University,Jerusalem 91904 (Israel); Porfyriadis, Achilleas P.; Strominger, Andrew [Center for the Fundamental Laws of Nature, Harvard University,Cambridge, MA 02138 (United States)

    2015-07-15

    Most extreme-mass-ratio-inspirals of small compact objects into supermassive black holes end with a fast plunge from an eccentric last stable orbit. For rapidly rotating black holes such fast plunges may be studied in the context of the Kerr/CFT correspondence because they occur in the near-horizon region where dynamics are governed by the infinite dimensional conformal symmetry. In this paper we use conformal transformations to analytically solve for the radiation emitted from fast plunges into near-extreme Kerr black holes. We find perfect agreement between the gravity and CFT computations.

  5. Innate immunity and testosterone rapidly respond to acute stress, but is corticosterone at the helm?

    Science.gov (United States)

    Davies, S; Noor, S; Carpentier, E; Deviche, P

    2016-10-01

    When faced with a stressor, vertebrates can rapidly increase the secretion of glucocorticoids, which is thought to improve the chances of survival. Concurrent changes in other physiological systems, such as the reproductive endocrine or innate immune systems, have received less attention, particularly in wild vertebrates. It is often thought that glucocorticoids directly modulate immune performance during a stress response, but, in many species, androgens also rapidly respond to stress. However, to our knowledge, no study has simultaneously examined the interactions between the glucocorticoid, androgen, and innate immune responses to stress in a wild vertebrate. To address this issue, we tested the hypothesis that the change in plasma corticosterone (CORT) in response to the acute stress of capture and restraint is correlated with the concurrent changes in plasma testosterone (T) and innate immune performance (estimated by the capacity of plasma to agglutinate and lyse foreign cells) in the Abert's Towhee (Melozone aberti). Furthermore, to broaden the generality of the findings, we compared male and female towhees, as well as males from urban and non-urban populations. Acute stress increased plasma CORT, decreased plasma T in males, and decreased innate immune performance, but the increase in CORT during stress was not correlated with the corresponding decreases in either plasma T or innate immunity. By contrast, the plasma T stress response was positively correlated with the innate immune stress response. Collectively, our results challenge the proposition that the glucocorticoid stress response is correlated with the concurrent changes in plasma T, a key reproductive hormone, and innate immunity, as estimated by agglutination and lysis.

  6. Barley (Hordeum vulgare) circadian clock genes can respond rapidly to temperature in an EARLY FLOWERING 3-dependent manner.

    Science.gov (United States)

    Ford, Brett; Deng, Weiwei; Clausen, Jenni; Oliver, Sandra; Boden, Scott; Hemming, Megan; Trevaskis, Ben

    2016-10-01

    An increase in global temperatures will impact future crop yields. In the cereal crops wheat and barley, high temperatures accelerate reproductive development, reducing the number of grains per plant and final grain yield. Despite this relationship between temperature and cereal yield, it is not clear what genes and molecular pathways mediate the developmental response to increased temperatures. The plant circadian clock can respond to changes in temperature and is important for photoperiod-dependent flowering, and so is a potential mechanism controlling temperature responses in cereal crops. This study examines the relationship between temperature, the circadian clock, and the expression of flowering-time genes in barley (Hordeum vulgare), a crop model for temperate cereals. Transcript levels of barley core circadian clock genes were assayed over a range of temperatures. Transcript levels of core clock genes CCA1, GI, PRR59, PRR73, PRR95, and LUX are increased at higher temperatures. CCA1 and PRR73 respond rapidly to a decrease in temperature whereas GI and PRR59 respond rapidly to an increase in temperature. The response of GI and the PRR genes to changes in temperature is lost in the elf3 mutant indicating that their response to temperature may be dependent on a functional ELF3 gene. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  7. Quasilocal Energy in Kerr Spacetime

    CERN Document Server

    Liu, Jian-Liang

    2016-01-01

    In this work we study the quasilocal energy as in [11] for a constant radius surface in Kerr spacetime in Boyer-Lindquist coordinates. We show that under suitable conditions for isometric embedding, for a stationary observer the quasilocal energy defined in [11] for constant radius in a Kerr like spacetime is exactly equal to the Brown-York quasilocal energy [2]. By some careful estimations, we show that for a constant radius surface in the Kerr spacetime which is outside the ergosphere the embedding conditions for the previous result are satisfied. Finally we discuss extremal solutions as described in [14] and show that near the horizon of the Kerr spacetime for the small rotation case the extremal solutions are trivial.

  8. More on Kerr geodesics

    Energy Technology Data Exchange (ETDEWEB)

    Fayos, F; Teijon, Ch [Departament de Fisica Aplicada, Universitat Politecnica de Catalunya, Barcelona (Spain)

    2007-05-15

    The equations of motion of a Kerr Black Hole are deeply analyzed in order to find out and classify the different kinds of orbits; i.e. bounded geodesics with null or non null eccentricity. Using Boyer-Lindquist coordinates; this classification is made in terms of the constants of motion: mass (m), energy (E) angular momentum (L) and Carter's constant (L). Constraints on the allowed values are found: constants of motion cannot take any value, and the allowed range of values depends on the values of the other parameters. Finally, a 'three dimensional space of parameters' is build, using the constants of motion at the axes: z = m{sup 2}/E{sup 2}, {xi} = L/E and {mu} L/E{sup 2} . In this representation, every point represents a geodesic and regions of different kind of orbits are delimited, becoming a powerful tool to visualize the position and relationship between them, and to see how one particle is able to go from one kind of geodesic to another by a slow change of its constants of motion. This slow change is predicted in the adiabatic limit hypothesis of gravitational radiationl [N Sago et al 2006 Progress of Theoretical Physics 115 873].

  9. New entropy formula for Kerr black holes

    OpenAIRE

    Gonzalez, Hernan; Grumiller, Daniel; Merbis, Wout; Wutte, Raphaela

    2017-01-01

    We introduce a new entropy formula for Kerr black holes inspired by recent results for 3-dimensional black holes and cosmologies with soft Heisenberg hair. We show that also Kerr-Taub-NUT black holes obey the same formula.

  10. Somatically Hypermutated Plasmodium-Specific IgM(+) Memory B Cells Are Rapid, Plastic, Early Responders upon Malaria Rechallenge.

    Science.gov (United States)

    Krishnamurty, Akshay T; Thouvenel, Christopher D; Portugal, Silvia; Keitany, Gladys J; Kim, Karen S; Holder, Anthony; Crompton, Peter D; Rawlings, David J; Pepper, Marion

    2016-08-16

    Humoral immunity consists of pre-existing antibodies expressed by long-lived plasma cells and rapidly reactive memory B cells (MBC). Recent studies of MBC development and function after protein immunization have uncovered significant MBC heterogeneity. To clarify functional roles for distinct MBC subsets during malaria infection, we generated tetramers that identify Plasmodium-specific MBCs in both humans and mice. Long-lived murine Plasmodium-specific MBCs consisted of three populations: somatically hypermutated immunoglobulin M(+) (IgM(+)) and IgG(+) MBC subsets and an unmutated IgD(+) MBC population. Rechallenge experiments revealed that high affinity, somatically hypermutated Plasmodium-specific IgM(+) MBCs proliferated and gave rise to antibody-secreting cells that dominated the early secondary response to parasite rechallenge. IgM(+) MBCs also gave rise to T cell-dependent IgM(+) and IgG(+)B220(+)CD138(+) plasmablasts or T cell-independent B220(-)CD138(+) IgM(+) plasma cells. Thus, even in competition with IgG(+) MBCs, IgM(+) MBCs are rapid, plastic, early responders to a secondary Plasmodium rechallenge and should be targeted by vaccine strategies. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Selective sensitivity in Kerr microscopy

    Science.gov (United States)

    Soldatov, I. V.; Schäfer, R.

    2017-07-01

    A new technique for contrast separation in wide-field magneto-optical Kerr microscopy is introduced. Utilizing the light from eight light emitting diodes, guided to the microscope by glass fibers and being switched synchronously with the camera exposure, domain images with orthogonal in-plane sensitivity can be displayed simultaneously at real-time, and images with pure in-plane or polar contrast can be obtained. The benefit of this new method of contrast separation is demonstrated for Permalloy films, a NdFeB sinter magnet, and a cobalt crystal. Moreover, the new technique is shown to strongly enhance the sensitivity of Kerr microscopy by eliminating parasitic contrast contributions occurring in conventional setups. A doubling of the in-plane domain contrast and a sensitivity to Kerr rotations as low as 0.6 mdeg is demonstrated.

  12. 75 FR 57920 - Kerr-Philpott System

    Science.gov (United States)

    2010-09-23

    ... Southeastern Power Administration Kerr-Philpott System AGENCY: Southeastern Power Administration, (Southeastern... Administration, Kerr-Philpott System Power Rates; Rate Order No. SEPA-52 Order Confirming and Approving Power... Notice and Comment Notice of a proposed rate adjustment for the Kerr-Philpott System was published in the...

  13. Race for the Kerr field

    CERN Document Server

    Dautcourt, G

    2008-01-01

    Roy P. Kerr has discovered his celebrated metric 45 years ago, yet the problem to find a generalization of the Schwarzschild metric for a rotating mass was faced much earlier. Lense and Thirring, Bach, Andress, Akeley, Lewis, van Stockum and others have tried to solve it or to find an approximative solution at least. In particular Achilles Papapetrou, from 1952 to 1961 in Berlin, was interested in an exact solution. He directed the author in the late autumn of 1959 to work on the problem. Why did these pre-Kerr attempts fail? Comments based on personal reminiscences and old notes.

  14. Unstable Fields in Kerr Spacetimes

    CERN Document Server

    Dotti, Gustavo; Ranea-Sandoval, Ignacio F

    2011-01-01

    We present a generalization of previous results regarding the stability under gravitational perturbations of nakedly singular super extreme Kerr spacetime and Kerr black hole interior beyond the Cauchy horizon. To do so we study solutions to the radial and angular Teukolsky's equations with different spin weights, particulary $s=\\pm 1$ representing electromagnetic perturbations, $s=\\pm 1/2$ representing a perturbation by a Dirac field and $s=0$ representing perturbations by a scalar field. By analizing the properties of radial and angular eigenvalues we prove the existence of an infinite family of unstable modes.

  15. On Didelphis caudivolvula Kerr and Didelphis vulpecula Kerr

    NARCIS (Netherlands)

    Jentink, F.A.

    1885-01-01

    Some months ago I was happy enough to procure for our library the rare Animal Kingdom written by Kerr. This autuhor described clearly two Phalangers under the names New-Holland descriptions have Opossum and Vulpine Opossum: these been overlooked by all the naturalist Who have studied the

  16. Femtosecond Kerr-lens autocorrelation.

    Science.gov (United States)

    Sheik-Bahae, M

    1997-03-15

    An autocorrelation measurement of femtosecond laser pulse duration using the Kerr-lens mechanism is demonstrated. This technique can also be used as a sensitive and absolutely calibratable method for measuring ultrafast optical nonlinearities. A method that uses an electronic spectral-filtering scheme is proposed for determining the frequency chirp of pulses by interferometric autocorrelation.

  17. MOKE: Magneto Optical Kerr Effect

    Science.gov (United States)

    Wildforster, Erik; Buchanan, Kristen

    2011-10-01

    The magneto-optical Kerr effect (MOKE) is a powerful tool for studying the magnetization reversal process of ferromagnetic materials. It works by measuring changes in the polarization of reflected light that are proportional to the magnetization of the sample, an effect discovered in the 1800's. This effect, known as the magneto-optical Kerr effect, provides a non-destructive means to measure the magnetization of thin film or patterned ferromagnetic materials. Furthermore, the light can be focused down to a diffraction-limited spot, allowing one to measure much smaller samples than conventional magnetometers. This poster will give an overview of the MOKE technique and we will show a comparison of magnetic hysteresis loops of ferromagnetic thin film samples measured using the longitudinal MOKE effect and with a conventional vibrating sample magnetometer. We acknowledge support from NIST award number 60NANB10D011 and the NSF, award 0907706.

  18. Enhancement of Kerr nonlinearity completely without absorption

    Science.gov (United States)

    Liang, Hong; Niu, Yueping; Deng, Li; Gong, Shangqing

    2017-12-01

    We investigate the enhancement of the Kerr nonlinearity in a four-level tripod-type atomic system completely without absorption. We study the effect of the incoherent pumping on the nonlinear susceptibility of the probe field and show that compared with that without the incoherent pumping, the Kerr nonlinearity can be enhanced with completely suppressed absorption at two different probe frequencies. Thus, we can get a symmetrical enhanced Kerr nonlinearity. Particularly, all of our results are in the case of Doppler broadening.

  19. Spectral Hole Burning via Kerr Nonlinearity

    Science.gov (United States)

    Khan, Anwar Ali; Abdul Jabar, M. S.; Jalaluddin, M.; Bacha, Bakht Amin; Iftikhar, Ahmad

    2015-10-01

    Spectral hole burning is investigated in an optical medium in the presence of Doppler broadening and Kerr nonlinearity. The Kerr nonlinearity generates coherent hole burning in the absorption spectrum. The higher order Kerr nonlinearity enhances the typical lamb dip of the hole. Normal dispersion in the hole burning region while Steep anomalous dispersion between the two hole burning regions also enhances with higher order Kerr effect. A large phase shift creates large delay or advancement in the pulse propagation while no distortion is observed in the pulse. These results provide significant steps to improve optical memory, telecom devices, preservation of information and image quality. Supported by Higher Education Commission (HEC) of Pakistan

  20. Perceptions of interactions between staff members calling, and those responding to, rapid response team activations for patient deterioration.

    Science.gov (United States)

    Chalwin, Richard; Flabouris, Arthas; Kapitola, Karoline; Dewick, Leonie

    2016-09-01

    Objectives The aim of the present study was to investigate experiences of staff interactions and non-technical skills (NTS) at rapid response team (RRT) calls, and their association with repeat RRT calls. Methods Mixed-methods surveys were conducted of RRT members and staff who activate the RRT (RRT users) for their perceptions and attitudes regarding the use of NTS during RRT calls. Responses within the survey were recorded as Likert items, ranked data and free comments. The latter were coded into nodes relating to one of four NTS domains: leadership, communication, cooperation and planning. Results Two hundred and ninety-seven (32%) RRT users and 79 (73.8%) RRT members provided responses. Of the RRT user respondents, 76.5% had activated the RRT at some point. Deficits in NTS at RRT calls were revealed, with 36.9% of users not feeling involved during RRT calls and 24.7% of members perceiving that users were disinterested. Unresolved user clinical concerns, or persistence of RRT calling criteria, were reasons cited by 37.6% and 23%, respectively, of RRT users for reactivating an RRT to the same patient. Despite recollections of conflict at previous RRT calls, 92% of users would still reactivate the RRT. The most common theme in the free comments related to deficiencies in cooperation (52.9%), communication (28.6%) and leadership (14.3%). Conclusions This survey of RRT users and members revealed problems with RRT users' and members' interactions at the time of an RRT call. Both users and members considered NTS to be important, but lacking. These findings support NTS training for RRT members and users. What is known about the topic? Previous surveying has related experiences of criticism and conflict between clinical staff at RRT activations. This leads to reluctance to call the RRT when indicated, with risks to patient safety, especially if subsequent RRT activation is necessary. Training in NTS has improved clinician interactions in simulated emergencies, but the

  1. Spatial Solitons and Induced Kerr Effects in Quasi-Phase-Matched Quadratic Media

    DEFF Research Database (Denmark)

    Clausen, Carl A. Balslev; Bang, Ole; Kivshar, Yu.S.

    1997-01-01

    We show that the evolution of the average intensity of cw beams in a quasi-phase-matched quadratic (or chi((2))) medium is strongly influenced by induced Kerr effects, such as self- and cross-phase modulation. We prove the existence of rapidly oscillating solitary waves (a spatial analog of the g......We show that the evolution of the average intensity of cw beams in a quasi-phase-matched quadratic (or chi((2))) medium is strongly influenced by induced Kerr effects, such as self- and cross-phase modulation. We prove the existence of rapidly oscillating solitary waves (a spatial analog...

  2. Rapid Evidence Assessment: What can be learnt from other jurisdictions about preventing and responding to child sexual abuse

    OpenAIRE

    Radford, Lorraine; Richardson-foster, Helen; Barter, Christine Anne; Stanley, Nicky

    2017-01-01

    This Rapid Evidence Assessment was commissioned by the Independent Inquiry into Child Sexual Abuse in England and Wales which is investigating whether public bodies and other non-state institutions have taken seriously their duties to care for and protect children and young people from child sexual abuse and exploitation. The question for the review was: What can be learnt from jurisdictions, outside of England and Wales, about the role of institutions, including accountable state and non-sta...

  3. Ligand Replacement Approach to Raman-Responded Molecularly Imprinted Monolayer for Rapid Determination of Penicilloic Acid in Penicillin.

    Science.gov (United States)

    Zhang, Liying; Jin, Yang; Huang, Xiaoyan; Zhou, Yujie; Du, Shuhu; Zhang, Zhongping

    2015-12-01

    Penicilloic acid (PA) is a degraded byproduct of penicillin and often causes fatal allergies to humans, but its rapid detection in penicillin drugs remains a challenge due to its similarity to the mother structure of penicillin. Here, we reported a ligand-replaced molecularly imprinted monolayer strategy on a surface-enhanced Raman scattering (SERS) substrate for the specific recognition and rapid detection of Raman-inactive PA in penicillin. The bis(phenylenediamine)-Cu(2+)-PA complex was first synthesized and stabilized onto the surface of silver nanoparticle film that was fabricated by a bromide ion-added silver mirror reaction. A molecularly imprinted monolayer was formed by the further modification of alkanethiol around the stabilized complex on the Ag film substrate, and the imprinted recognition site was then created by the replacement of the complex template with Raman-active probe molecule p-aminothiophenol. When PA rebound into the imprinted site in the alkanethiol monolayer, the SERS signal of p-aminothiophenol exhibited remarkable enhancement with a detection limit of 0.10 nM. The imprinted monolayer can efficiently exclude the interference of penicillin and thus provides a selective determination of 0.10‰ (w/w) PA in penicillin, which is about 1 order of magnitude lower than the prescribed residual amount of 1.0‰. The strategy reported here is simple, rapid and inexpensive compared to the traditional chromatography-based methods.

  4. Non-responsiveness to intervention: children with autism spectrum disorders who do not rapidly respond to communication interventions.

    Science.gov (United States)

    Ganz, Jennifer B; Lashley, Erin; Rispoli, Mandy Jenkins

    2010-01-01

    Providing a detailed description of two participants who failed to acquire functional communication skills following a verbal modelling intervention and Picture Exchange Communication System (PECS) training. Single-case research; Independent verbal requests, imitated verbal requests, word approximations and independent picture requests were assessed in a toddler and a pre-schooler with autism before and during two interventions. Although both participants used some vocalizations over the course of the study, experimental control was not demonstrated and the participants did not acquire a functional communication system prior to the cessation of intervention. Future research should include additional, detailed reports that provide insight to why some children with autism do not respond to particular communication interventions and should investigate the pairing of particular child characteristics with targeted interventions.

  5. Kerr geometry in f(T) gravity

    Energy Technology Data Exchange (ETDEWEB)

    Bejarano, Cecilia; Guzman, Maria Jose [Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), Buenos Aires (Argentina); Ferraro, Rafael [Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), Buenos Aires (Argentina); Universidad de Buenos Aires, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)

    2015-02-01

    Null tetrads are shown to be a valuable tool in teleparallel theories of modified gravity. We use them to prove that Kerr geometry remains a solution for a wide family of f(T) theories of gravity. (orig.)

  6. The polar Kerr effect in superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Robbins, Joshua; Annett, James F.; Gradhand, Martin [University of Bristol (United Kingdom)

    2016-07-01

    The polar Kerr effect is an optical phenomenon which arises in states with broken time-reversal symmetry. This effect has recently been observed in a series of unconventional superconductors, including the layered perovskite compound Sr{sub 2}RuO{sub 4}. Confirmation of a Kerr signal below T{sub c} supports the hypothesis of chiral p-wave superconductivity in this material. However, the nature of the unconventional superconducting state remains a source of controversy. Here, we present calculations for the chiral superconducting state including spin-orbit coupling (SOC) by extending the three dimensional, multiband model considered previously. SOC was found to induce strong mixing of the orbital characters within the bandstructure. This mixing is essential for the existence of the polar Kerr effect and the large increase due to SOC has a significant influence on the frequency dependence of the predicted Kerr signal. We will extend and apply the model to other unconventional superconductors which have displayed the Kerr effect in recent years. This will allow a detailed study of the symmetry properties of these systems and will provide valuable insight into the pairing mechanism of superconductors.

  7. Efeito Kerr eletro-optico em liquidos

    OpenAIRE

    Jose Montanha Neto

    1991-01-01

    Resumo: Foi construído um sistema para o estudo do efeito Kerr eletro-óptico em líquidos, para o qual desenvolvemos um gerador de pulsos retangulares de alta tensão e curta duração, além de uma célula de Kerr com baixa birrefringência residual. Uma técnica de sinal nulo foi empregada na medida da birrefringência induzida. As constantes de Kerr de sete líquidos puros; água, acetona, clorofórmio, nitrometano, quinolina, ácido acético e isopropil benzeno (cumeno) foram medidas. Para os quatro úl...

  8. HIGH SPEED KERR CELL FRAMING CAMERA

    Science.gov (United States)

    Goss, W.C.; Gilley, L.F.

    1964-01-01

    The present invention relates to a high speed camera utilizing a Kerr cell shutter and a novel optical delay system having no moving parts. The camera can selectively photograph at least 6 frames within 9 x 10/sup -8/ seconds during any such time interval of an occurring event. The invention utilizes particularly an optical system which views and transmits 6 images of an event to a multi-channeled optical delay relay system. The delay relay system has optical paths of successively increased length in whole multiples of the first channel optical path length, into which optical paths the 6 images are transmitted. The successively delayed images are accepted from the exit of the delay relay system by an optical image focusing means, which in turn directs the images into a Kerr cell shutter disposed to intercept the image paths. A camera is disposed to simultaneously view and record the 6 images during a single exposure of the Kerr cell shutter. (AEC)

  9. Finite escape fraction for ultrahigh energy collisions around Kerr ...

    Indian Academy of Sciences (India)

    We investigate the issue of observability of high-energy collisions around Kerr naked singularity and show that results are in contrast with the Kerr black hole case. We had shown that it would be possible to have ultrahigh energy collisions between the particles close to the location = M around the Kerr naked singularity if ...

  10. Finite escape fraction for ultrahigh energy collisions around Kerr ...

    Indian Academy of Sciences (India)

    Abstract. We investigate the issue of observability of high-energy collisions around Kerr naked singularity and show that results are in contrast with the Kerr black hole case. We had shown that it would be possible to have ultrahigh energy collisions between the particles close to the location r = M around the Kerr naked ...

  11. Ergoregion in metamaterials mimicking a Kerr spacetime

    Science.gov (United States)

    Pires, D. G.; Rocha, J. C. A.; Brandão, P. A.

    2018-02-01

    We propose a simple singularity-free coordinate transformation that could be implemented in Maxwell’s equations in order to simulate one aspect of a Kerr black hole. Kerr black holes are known to force light to rotate in a predetermined direction inside the ergoregion. By making use of cosmological analogies and the theoretical framework of transformation optics, we have designed a metamaterial that can make light behave as if it is propagating around a rotating cosmological massive body. We present numerical simulations involving incident Gaussian beams interacting with the materials to verify our predictions. The ergoregion is defined through the dispersion curve of the off-axis permittivities components.

  12. Innermost stable circular orbit of Kerr-MOG black hole

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun-Chul; Han, Yong-Jin [Soonchunhyang University, Department of Physics, Asan (Korea, Republic of)

    2017-10-15

    We study the innermost stable circular orbit (ISCO) of the metric of the Kerr black hole in modified gravity (Kerr-MOG black hole), which is one of the exact solutions of the field equation of modified gravity in the strong gravity regime. The Kerr-MOG metric is constructed; it is the commonly known Kerr metric in Boyer-Lindquist coordinates by adding a repulsive term like the Yukawa force, which is explained in quantum gravity. In this paper, we numerically calculate the circular orbit of a photon and the ISCO of a test particle of Kerr-MOG black holes. (orig.)

  13. Innermost stable circular orbit of Kerr-MOG black hole

    Science.gov (United States)

    Lee, Hyun-Chul; Han, Yong-Jin

    2017-10-01

    We study the innermost stable circular orbit (ISCO) of the metric of the Kerr black hole in modified gravity (Kerr-MOG black hole), which is one of the exact solutions of the field equation of modified gravity in the strong gravity regime. The Kerr-MOG metric is constructed; it is the commonly known Kerr metric in Boyer-Lindquist coordinates by adding a repulsive term like the Yukawa force, which is explained in quantum gravity. In this paper, we numerically calculate the circular orbit of a photon and the ISCO of a test particle of Kerr-MOG black holes.

  14. Kerr black holes with scalar hair.

    Science.gov (United States)

    Herdeiro, Carlos A R; Radu, Eugen

    2014-06-06

    We present a family of solutions of Einstein's gravity minimally coupled to a complex, massive scalar field, describing asymptotically flat, spinning black holes with scalar hair and a regular horizon. These hairy black holes (HBHs) are supported by rotation and have no static limit. Besides mass M and angular momentum J, they carry a conserved, continuous Noether charge Q measuring the scalar hair. HBHs branch off from the Kerr metric at the threshold of the superradiant instability and reduce to spinning boson stars in the limit of vanishing horizon area. They overlap with Kerr black holes for a set of (M, J) values. A single Killing vector field preserves the solutions, tangent to the null geodesic generators of the event horizon. HBHs can exhibit sharp physical differences when compared to the Kerr solution, such as J/M^{2}>1, a quadrupole moment larger than J^{2}/M, and a larger orbital angular velocity at the innermost stable circular orbit. Families of HBHs connected to the Kerr geometry should exist in scalar (and other) models with more general self-interactions.

  15. Complex Structure of the Four-Dimensional Kerr Geometry: Stringy System, Kerr Theorem, and Calabi-Yau Twofold

    Directory of Open Access Journals (Sweden)

    Alexander Burinskii

    2013-01-01

    Full Text Available The 4D Kerr geometry displays many wonderful relations with quantum world and, in particular, with superstring theory. The lightlike structure of fields near the Kerr singular ring is similar to the structure of Sen solution for a closed heterotic string. Another string, open and complex, appears in the complex representation of the Kerr geometry initiated by Newman. Combination of these strings forms a membrane source of the Kerr geometry which is parallel to the structure of M-theory. In this paper we give one more evidence of this relationship, emergence of the Calabi-Yau twofold (K3 surface in twistorial structure of the Kerr geometry as a consequence of the Kerr theorem. Finally, we indicate that the Kerr stringy system may correspond to a complex embedding of the critical N = 2 superstring.

  16. Academics respond

    DEFF Research Database (Denmark)

    Hazel, Spencer

    2015-01-01

    Contribution to the article "Academics respond: Brexit would weaken UK university research and funding", Guardian Witness, The Guardian, UK......Contribution to the article "Academics respond: Brexit would weaken UK university research and funding", Guardian Witness, The Guardian, UK...

  17. The Kerr-Newman metric: A Review

    CERN Document Server

    Adamo, Tim

    2014-01-01

    The Kerr-Newman metric describes a very special rotating, charged mass and is the most general of the asymptotically flat stationary 'black hole' solutions to the Einstein-Maxwell equations of general relativity. We review the derivation of this metric from the Reissner-Nordstrom solution by means of a complex transformation algorithm and provide a brief overview of its basic geometric properties. We also include some discussion of interpretive issues, related metrics, and higher-dimensional analogues.

  18. Time-resolved photoinduced Kerr rotation in semiconductor microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Mitsumori, Y.; Kosaka, H. [Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Katahira, Aoba-ku, Sendai (Japan); CREST-JST (Japan); Kato, N.; Edamatsu, K. [Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Katahira, Aoba-ku, Sendai (Japan); Yamamoto, N.; Akahane, K. [National Institute of Information and Communications Technology, Nukuikita, Koganei-shi, Tokyo (Japan)

    2009-01-15

    We studied photoinduced Kerr effect in cavity polaritons in a semiconductor microcavity by carefully measuring the time-resolved Kerr rotation and ellipticity spectra. The Kerr rotation angle of the microcavity polaritons is a hundred times larger than a conventional single quantum well. A spectral shape analysis of the observed spectra suggests that the photoindeced Kerr effect mainly results from a line broadening of the polarions due to spin-polarized polariton-polariton scattering. Enhancement in oscillator strength also contributes to the large rotation angle. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. The geometry of Kerr black holes

    CERN Document Server

    O'Neill, Barrett

    2014-01-01

    This unique monograph by a noted UCLA professor examines in detail the mathematics of Kerr black holes, which possess the properties of mass and angular momentum but carry no electrical charge. Suitable for advanced undergraduates and graduate students of mathematics, physics, and astronomy as well as professional physicists, the self-contained treatment constitutes an introduction to modern techniques in differential geometry. The text begins with a substantial chapter offering background on the mathematics needed for the rest of the book. Subsequent chapters emphasize physical interpretation

  20. Entropy in Kerr-Newman-Kasuya spacetime

    CERN Document Server

    Gao Chang Jun

    2002-01-01

    The entropy of a rotating Kerr-Newman-Kasuya black hole due to massive charged fields (bosons and fermions) is calculated using an improved brick-wall model. The result shows that the entropy depends not on the mass and charge but the spin of the fields. Considering statistical physics, we do not propose to consider the superradiant modes for bosons (fermion fields do not display superradiance). In fact, the non-superradiant mode contributes exactly the area entropy for both bosons and fermions.

  1. Cross-Kerr Nonlinearity for Phonon Counting

    Science.gov (United States)

    Ding, Shiqian; Maslennikov, Gleb; Hablützel, Roland; Matsukevich, Dzmitry

    2017-11-01

    State measurement of a quantum harmonic oscillator is essential in quantum optics and quantum information processing. In a system of trapped ions, we experimentally demonstrate the projective measurement of the state of the ions' motional mode via an effective cross-Kerr coupling to another motional mode. This coupling is induced by the intrinsic nonlinearity of the Coulomb interaction between the ions. We spectroscopically resolve the frequency shift of the motional sideband of the first mode due to the presence of single phonons in the second mode and use it to reconstruct the phonon number distribution of the second mode.

  2. Innovations in energy: the story of Kerr-McaGee

    Energy Technology Data Exchange (ETDEWEB)

    Ezell, J.S.

    1979-01-01

    The history of the Kerr-McGee Corporation is a saga of American enterprise that began in Ada, Oklahoma, in 1929, when future Senator Robert S. Kerr and his brother-in-law, James L. Anderson, became partners in the Anderson and Kerr Drilling Company. Fifty years later Kerr-McGee's diversified, international operations truly justify Kerr-McGee President, Dean A. McGee's epithet, ''a natural resource company.'' Able to find other gifted people to work for him, Robert Kerr's company has been dominated by a series of extraordinary oil-industry personalities who made extraordinary and essential contributions - from roughnecks and drillers to lawyers and financiers. Much of his history, based on first-person accounts, emphasizes human element in the exploitation of energy resources, describes the company's pioneering achievements in the inland and offshore oil industry (including the drilling of the first offshore well), the expansion into refining, manufacturing, and retailing and into the development of other natural resources (including uranium, coal, helium, boron, and potash), the corporate structure that sustained exploration and expansion, the financing of multimillion-dollar operations, the lawsuits (including the case of Karen Silkwood) in which the company has been involved from its earliest days, the relations between business and government exacerbated by Robert S. Kerr and the technological innovations that have been characteristic of Kerr-McGee. 90 references, 22 figures, 83 tables.

  3. Terahertz-induced Kerr effect in amorphous chalcogenide glasses

    DEFF Research Database (Denmark)

    Zalkovskij, Maksim; Strikwerda, Andrew; Iwaszczuk, Krzysztof

    2013-01-01

    We have investigated the terahertz-induced third-order (Kerr) nonlinear optical properties of the amorphous chalcogenide glasses As2S3 and As2Se3. Chalcogenide glasses are known for their high optical Kerr nonlinearities which can be several hundred times greater than those of fused silica. We use...

  4. Enhanced Kerr nonlinearity via quantum interference from spontaneous emission

    Science.gov (United States)

    Asadpour, S. H.; Sahrai, M.; Soltani, A.; Hamedi, H. R.

    2012-01-01

    A novel atom configuration is proposed for a giant Kerr nonlinearity in zero linear and nonlinear probe absorption. It is shown that without coherent control field and just by quantum interference of spontaneous emission, a giant Kerr nonlinearity can be obtained.

  5. Enhanced Kerr nonlinearity via quantum interference from spontaneous emission

    Energy Technology Data Exchange (ETDEWEB)

    Asadpour, S.H., E-mail: S.Hosein.Asadpour@gmail.com [Young Researchers Club, Bandar Anzali Branch, Islamic Azad University, Bandar Anzali (Iran, Islamic Republic of); Sahrai, M. [Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of); Soltani, A. [School of Engineering and Emerging Technologies, University of Tabriz, Tabriz (Iran, Islamic Republic of); Hamedi, H.R. [Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2012-01-02

    A novel atom configuration is proposed for a giant Kerr nonlinearity in zero linear and nonlinear probe absorption. It is shown that without coherent control field and just by quantum interference of spontaneous emission, a giant Kerr nonlinearity can be obtained. -- Highlights: ► The quantum interference from spontaneous emission is considered in a four-level medium. ► The giant Kerr nonlinearity in the zero linear and nonlinear absorption is obtained. ► The quantum interference effect on group velocity is then investigated.

  6. Multispectral Kerr frequency comb initiated by Faraday ripples

    CERN Document Server

    Huang, Shu-Wei

    2016-01-01

    In a uniform microresonator, the generation of a broadband Kerr frequency comb is triggered by Turing patterns. Here, we study a distinctly different route to initiate the Kerr frequency comb by Faraday ripples. Momentum conservation is ensured by azimuthal modulation of the cavity dispersion. With a good agreement with the theoretical analysis, we demonstrate a multispectral Kerr frequency comb covering telecommunication O, C, L, and 2 {\\mu}m bands. Comb coherence and absence of a subcomb offset are confirmed by cw heterodyne beat note and amplitude noise spectra measurements. The device can be used for achieving broadband optical frequency synthesizer and high-capacity coherent telecommunication.

  7. Horizon dynamics in perturbed Kerr spacetimes

    CERN Document Server

    Chu, Tony; Cohen, Michael I

    2010-01-01

    We present numerical simulations of a Kerr black hole perturbed by a pulse of ingoing gravitational radiation. For strong perturbations we find up to five concentric marginally outer trapped surfaces. These trapped surfaces appear and disappear in pairs, so that the total number of such surfaces at any given time is odd. The world tubes traced out by the marginally outer trapped surfaces are found to be spacelike during the highly dynamical regime, approaching a null hypersurface at early and late times. We analyze the structure of these marginally trapped tubes in the context of the dynamical horizon formalism, computing the expansion of outgoing and incoming null geodesics, as well as evaluating the dynamical horizon flux law and the angular momentum flux law. Finally, we compute the event horizon. The event horizon is well-behaved and approaches the apparent horizon before and after the highly dynamical regime. No new generators enter the event horizon during the simulation.

  8. Echoes of Kerr-like wormholes

    Science.gov (United States)

    Bueno, Pablo; Cano, Pablo A.; Goelen, Frederik; Hertog, Thomas; Vercnocke, Bert

    2018-01-01

    Structure at the horizon scale of black holes would give rise to echoes of the gravitational wave signal associated with the postmerger ringdown phase in binary coalescences. We study the waveform of echoes in static and stationary, traversable wormholes in which perturbations are governed by a symmetric effective potential. We argue that echoes are dominated by the wormhole quasinormal frequency nearest to the fundamental black hole frequency that controls the primary signal. We put forward an accurate method to construct the echoes' waveform(s) from the primary signal and the quasinormal frequencies of the wormhole, which we characterize. We illustrate this in the static Damour-Solodukhin wormhole and in a new, rotating generalization that approximates a Kerr black hole outside the throat. Rotation gives rise to a potential with an intermediate plateau region that breaks the degeneracy of the quasinormal frequencies. Rotation also leads to late-time instabilities that, however, fade away for small angular momentum.

  9. The zero mass limit of Kerr and Kerr-(anti-)de-Sitter space-times: exact solutions and wormholes

    Science.gov (United States)

    Birkandan, T.; Hortaçsu, M.

    2018-03-01

    Heun-type exact solutions emerge for both the radial and the angular equations for the case of a scalar particle coupled to the zero mass limit of both the Kerr and Kerr-(anti)de-Sitter spacetime. Since any type D metric has Heun-type solutions, it is interesting that this property is retained in the zero mass case. This work further refutes the claims that M going to zero limit of the Kerr metric is both locally and globally the same as the Minkowski metric.

  10. Timescale for trans-Plankian collisions in Kerr spacetime

    CERN Document Server

    Patil, Mandar; Nakao, Ken-ichi; Kimura, Masashi; Harada, Tomohiro

    2015-01-01

    We make a critical comparison between ultra-high energy particle collisions around an extremal Kerr black hole and that around an over-spinning Kerr singularity, mainly focusing on the issue of the timescale of collisions. We show that the time required for two massive particles with the proton mass or two massless particles of GeV energies to collide around the Kerr black hole with Planck energy is several orders of magnitude longer than the age of the Universe for astro-physically relevant masses of black holes, whereas time required in the over-spinning case is of order ten million years which is much shorter than the age of the Universe. Thus from the point of view of observation of Planck scale collisions, the over-spinning Kerr geometry, subject to their occurrence, have distinct advantage over their black hole counterparts.

  11. Tradition and its transformation: Joan Kerr, Housewife to historian

    Directory of Open Access Journals (Sweden)

    Susan Steggall

    2011-06-01

    Full Text Available Australian art and architectural historian Joan Kerr (1938-2004 championed many little-known artists in her democratic approach to Australian art history. As an architectural historian she held strong views on how heritage restoration should be conducted. Joan Kerr in context: a biography, from which this essay is taken, is a biography of Joan Kerr, arranged in chapters that deal with particular aspects of her career while also moving forward in time along her life’s journey. Tradition and its transformation: Joan Kerr, housewife to historian focuses on her coming of age as a scholar: her postgraduate studies and subsequent research in architectural history, in particular her impressive body of work on Australian nineteenth-century architecture.

  12. A Zeroth Law Compatible Model to Kerr Black Hole Thermodynamics

    OpenAIRE

    Viktor G. Czinner; Hideo Iguchi

    2017-01-01

    We consider the thermodynamic and stability problem of Kerr black holes arising from the nonextensive/nonadditive nature of the Bekenstein–Hawking entropy formula. Nonadditive thermodynamics is often criticized by asserting that the zeroth law cannot be compatible with nonadditive composition rules, so in this work we follow the so-called formal logarithm method to derive an additive entropy function for Kerr black holes also satisfying the zeroth law’s requirement. Starting from the most gen...

  13. The matter-antimatter interpretation of Kerr spacetime

    OpenAIRE

    Villata, M.

    2014-01-01

    Repulsive gravity is not very popular in physics. However, one comes across it in at least two main occurrences in general relativity: in the negative-$r$ region of Kerr spacetime, and as the result of the gravitational interaction between matter and antimatter, when the latter is assumed to be CPT-transformed matter. Here we show how these two independent developments of general relativity are perfectly consistent in predicting gravitational repulsion and how the above Kerr negative-$r$ regi...

  14. Time-Periodic Einstein-Klein-Gordon Bifurcations of Kerr

    Science.gov (United States)

    Chodosh, Otis; Shlapentokh-Rothman, Yakov

    2017-12-01

    We construct one-parameter families of solutions to the Einstein-Klein-Gordon equations bifurcating off the Kerr solution such that the underlying family of spacetimes are each an asymptotically flat, stationary, axisymmetric, black hole spacetime, and such that the corresponding scalar fields are non-zero and time-periodic. An immediate corollary is that for these Klein-Gordon masses, the Kerr family is not asymptotically stable as a solution to the Einstein-Klein-Gordon equations.

  15. How quickly do High Arctic coastal environments respond to rapid deglaciation and the paraglacial transformation of proglacial areas? - Answers from Spitsbergen, Svalbard Archipelago

    Science.gov (United States)

    Strzelecki, Matt; Long, Antony; Lloyd, Jerry; Zagórski, Piotr

    2014-05-01

    The coastal zone is one of the most important storage systems for sediments that are eroded and transported by rivers, wind and slope processes from deglacierised valleys and proglacial areas before reaching their final sediment sink (fjords or the open sea. The Svalbard archipelago provides an excellent location to quantify how High Arctic coasts are responding to climate warming and the associated paraglacial landscape transformations. In this paper we summarize the results of several coastal surveys carried out by our research teams along the paraglacial coasts of Spitsbergen during the last decade. We reconstruct the post-Little Ice Age development of selected coastlines in Spitsbergen to illustrate the variable coastal response to paraglacial and periglacial processes activated following the recent retreat of glaciers. Our surveys use aerial photogrammetric and GIS analyses, sedimentological classification of coastal deposits and field-based geomorphological mapping in Kongsfjorden, Billefjorden, Bellsund, Hornsund and Sørkappland. Our results document dramatic changes in sediment flux and coastal response under intervals characterized by a warming climate, retreating local ice masses, a shortened winter sea-ice season and thawing permafrost. The study highlights the need for a greater understanding of the controls on High Arctic coastal geomorphology, especially given the potential for future accelerated warming and sea-level rise.

  16. Kerr-Newman black holes with scalar hair

    Science.gov (United States)

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

    2016-10-01

    We construct electrically charged Kerr black holes (BHs) with scalar hair. Firstly, we take an uncharged scalar field, interacting with the electromagnetic field only indirectly, via the background metric. The corresponding family of solutions, dubbed Kerr-Newman BHs with ungauged scalar hair, reduces to (a sub-family of) Kerr-Newman BHs in the limit of vanishing scalar hair and to uncharged rotating boson stars in the limit of vanishing horizon. It adds one extra parameter to the uncharged solutions: the total electric charge. This leading electromagnetic multipole moment is unaffected by the scalar hair and can be computed by using Gauss's law on any closed 2-surface surrounding (a spatial section of) the event horizon. By contrast, the first sub-leading electromagnetic multipole - the magnetic dipole moment -, gets suppressed by the scalar hair, such that the gyromagnetic ratio is always smaller than the Kerr-Newman value (g = 2). Secondly, we consider a gauged scalar field and obtain a family of Kerr-Newman BHs with gauged scalar hair. The electrically charged scalar field now stores a part of the total electric charge, which can only be computed by applying Gauss' law at spatial infinity and introduces a new solitonic limit - electrically charged rotating boson stars. In both cases, we analyze some physical properties of the solutions.

  17. Shadows of Kerr black holes with scalar hair

    CERN Document Server

    Cunha, Pedro V P; Radu, Eugen; Runarsson, Helgi F

    2015-01-01

    Using backwards ray tracing, we study the shadows of Kerr black holes with scalar hair (KBHsSH). KBHsSH interpolate continuously between Kerr BHs and boson stars (BSs), so we start by investigating the lensing of light due to BSs. Moving from the weak to the strong gravity region, BSs - which by themselves have no shadows - are classified, according to the lensing produced, as: $(i)$ non-compact, which yield no multiple images; $(ii)$ compact, which produce an increasing number of Einstein rings and multiple images of the whole celestial sphere; $(iii)$ ultra-compact, which possess light rings, yielding an infinite number of images with (we conjecture) a self-similar structure. The shadows of KBHsSH, for Kerr-like horizons and non-compact BS-like hair, are analogous to, but distinguishable from, those of comparable Kerr BHs. But for non-Kerr-like horizons and ultra-compact BS-like hair, the shadows of KBHsSH are drastically different: novel shapes arise, sizes are considerably smaller and multiple shadows of ...

  18. Electrically charged Kerr black holes with scalar hair

    CERN Document Server

    Delgado, Jorge F M; Radu, Eugen; Runarsson, Helgi

    2016-01-01

    We construct electrically charged Kerr black holes (BHs) with scalar hair. Firstly, we take an uncharged scalar field, interacting with the electromagnetic field only indirectly, via the background metric. The corresponding family of solutions, dubbed Kerr-Newman BHs with ungauged scalar hair, reduces to (a sub-family of) Kerr-Newman BHs in the limit of vanishing scalar hair and to uncharged rotating boson stars in the limit of vanishing horizon. It adds one extra parameter to the uncharged solutions: the total electric charge. This leading electromagnetic multipole moment is unaffected by the scalar hair and can be computed by using Gauss's law on any closed 2-surface surrounding (a spatial section of) the event horizon. By contrast, the first sub-leading electromagnetic multipole -- the magnetic dipole moment --, gets suppressed by the scalar hair, such that the gyromagnetic ratio is always smaller than the Kerr-Newman value ($g=2$). Secondly, we consider a gauged scalar field and obtain a family of Kerr-Ne...

  19. Shadows of Kerr Black Holes with Scalar Hair.

    Science.gov (United States)

    Cunha, Pedro V P; Herdeiro, Carlos A R; Radu, Eugen; Rúnarsson, Helgi F

    2015-11-20

    Using backwards ray tracing, we study the shadows of Kerr black holes with scalar hair (KBHSH). KBHSH interpolate continuously between Kerr BHs and boson stars (BSs), so we start by investigating the lensing of light due to BSs. Moving from the weak to the strong gravity region, BSs-which by themselves have no shadows-are classified, according to the lensing produced, as (i) noncompact, which yield not multiple images, (ii) compact, which produce an increasing number of Einstein rings and multiple images of the whole celestial sphere, and (iii) ultracompact, which possess light rings, yielding an infinite number of images with (we conjecture) a self-similar structure. The shadows of KBHSH, for Kerr-like horizons and noncompact BS-like hair, are analogous to, but distinguishable from, those of comparable Kerr BHs. But for non-Kerr-like horizons and ultracompact BS-like hair, the shadows of KBHSH are drastically different: novel shapes arise, sizes are considerably smaller, and multiple shadows of a single BH become possible. Thus, KBHSH provide quantitatively and qualitatively new templates for ongoing (and future) very large baseline interferometry observations of BH shadows, such as those of the Event Horizon Telescope.

  20. Gravitational collapse to a Kerr-Newman black hole

    Science.gov (United States)

    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.

  1. Zero mass limit of Kerr spacetime is a wormhole

    Science.gov (United States)

    Gibbons, Gary W.; Volkov, Mikhail S.

    2017-07-01

    We show that, contrary to what is usually claimed in the literature, the zero mass limit of Kerr spacetime is not flat Minkowski space but a spacetime whose geometry is only locally flat. This limiting spacetime, as the Kerr spacetime itself, contains two asymptotic regions and hence cannot be topologically trivial. It also contains a curvature singularity, because the power-law singularity of the Weyl tensor vanishes in the limit but there remains a distributional contribution of the Ricci tensor. This spacetime can be interpreted as a wormhole sourced by a negative tension ring. We also extend the discussion to similarly interpret the zero mass limit of the Kerr-(anti-)de Sitter spacetime.

  2. Advanced MOKE magnetometry in wide-field Kerr-microscopy

    Science.gov (United States)

    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.

  3. Large Kerr nonlinearity in a crystal of molecular magnets system

    Science.gov (United States)

    Feili, Sahar; Hamedi, Hamid Reza

    2014-03-01

    A novel scheme is proposed to investigate the possible giant Kerr nonlinearity in a crystal of molecular magnets. The crystal is subjected to one dc magnetic field and two probe and coupling ac magnetic fields. By studying the steady-state behavior of the medium, we show that an enhanced Kerr nonlinearity with negligible absorption can be achieved under condition of slow light levels, just by properly adjusting the coupling field. Also, the transient evolution of nonlinear dispersion is proposed. It is found that the frequency detunings of probe and coupling fields, as well as the intensity of coupling field, lead to the large Kerr nonlinearity. Our results can be used as a guideline for optimizing and controlling the switching process in the crystal of molecular magnets, which is much more practical than that in the atomic system because of its flexible design and the long relaxation times.

  4. Kerr nonlinearity and EIT in a double Lambda type atomic system

    Science.gov (United States)

    Hamedi, Hamid Reza; Khaledi-Nasab, Ali; Raheli, Ali

    2013-10-01

    The giant Kerr nonlinearity in a four-level double Lambda type atomic system is theoretically predicted. We find that an enhanced Kerr nonlinearity can be achieved just by the intensity of coupling filed that lies within the transparency window. It is also shown that the giant Kerr nonlinearity with reduced absorption can be achieved by the quantum interference mechanisms.

  5. Entropy of Kerr-de Sitter black hole

    Science.gov (United States)

    Li, Huai-Fan; Ma, Meng-Sen; Zhang, Li-Chun; Zhao, Ren

    2017-07-01

    Based on the consideration that the black hole horizon and the cosmological horizon of Kerr-de Sitter black hole are not independent of each other, we conjecture the total entropy of the system should have an extra term contributed from the correlations between the two horizons, except for the sum of the two horizon entropies. By employing globally effective first law and effective thermodynamic quantities, we obtain the corrected total entropy and find that the region of stable state for Kerr-de Sitter is related to the angular velocity parameter a, i.e., the region of stable state becomes bigger as the rotating parameters a is increases.

  6. Polarizability of Fluid Droplets and the Kerr Effect on Microemulsions

    CERN Document Server

    Lisy, V

    2001-01-01

    Spheroidal fluid droplets immersed in another fluid and thermally fluctuating in the shape are considered. The polarizability of the droplet is evaluated up to the second order in the fluctuation amplitudes. The correlation functions of the polarizability tensor components are found and used to describe the polarized and depolarized scattering of light, and the Kerr effect on microemulsions. By comparison of the theoretical results with the Kerr constant measurements from the literature, we estimate the bending rigidity of the surfactant monolayer that separates the oil and water phases in droplet microemulsions.

  7. Cosmic Censorship Conjecture in Kerr-Sen Black Hole

    CERN Document Server

    Gwak, Bogeun

    2016-01-01

    The validity of 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, its charges are changed due 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 extremal Kerr-Sen black hole to more than its charges, so the black hole cannot be overcharged. Therefore, cosmic censorship conjecture is valid.

  8. Onset of superradiant instabilities in the composed Kerr-black-hole–mirror bomb

    Directory of Open Access Journals (Sweden)

    Shahar Hod

    2014-09-01

    Full Text Available It was first pointed out by Press and Teukolsky that a system composed of a spinning Kerr black hole surrounded by a reflecting mirror may develop instabilities. The physical mechanism responsible for the development of these exponentially growing instabilities is the superradiant amplification of bosonic fields confined between the black hole and the mirror. A remarkable feature of this composed black-hole–mirror-field system is the existence of a critical mirror radius, rmstat, which supports stationary (marginally-stable field configurations. This critical (‘stationary’ mirror radius marks the boundary between stable and unstable black-hole–mirror-field configurations: composed systems whose confining mirror is situated in the region rmrmstat are unstable (that is, there are confined field modes which grow exponentially over time. In the present paper we explore this critical (marginally-stable boundary between stable and explosive black-hole–mirror-field configurations. It is shown that the innermost (smallest radius of the confining mirror which allows the extraction of rotational energy from a spinning Kerr black hole approaches the black-hole horizon radius in the extremal limit of rapidly-rotating black holes. We find, in particular, that this critical mirror radius (which marks the onset of superradiant instabilities in the composed system scales linearly with the black-hole temperature.

  9. Resonance spectrum of near-extremal Kerr black holes in the eikonal limit

    Energy Technology Data Exchange (ETDEWEB)

    Hod, Shahar, E-mail: shaharhod@gmail.com [Ruppin Academic Center, Emeq Hefer 40250 (Israel); Hadassah Institute, Jerusalem 91010 (Israel)

    2012-09-10

    The fundamental resonances of rapidly rotating Kerr black holes in the eikonal limit are derived analytically. We show that there exists a critical value, {mu}{sub c}={radical}((15-{radical}(193))/2 ), for the dimensionless ratio {mu}{identical_to}m/l between the azimuthal harmonic index m and the spheroidal harmonic index l of the perturbation mode, above which the perturbations become long lived. In particular, it is proved that above {mu}{sub c} the imaginary parts of the quasinormal frequencies scale like the black-hole temperature: {omega}{sub I}(n;{mu}>{mu}{sub c})=2{pi}T{sub BH}(n+1/2 ). This implies that for perturbations modes in the interval {mu}{sub c}<{mu}{>=}1, the relaxation period {tau}{approx}1/{omega}{sub I} of the black hole becomes extremely long as the extremal limit T{sub BH}{yields}0 is approached. A generalization of the results to the case of scalar quasinormal resonances of near-extremal Kerr-Newman black holes is also provided. In particular, we prove that only black holes that rotate fast enough (with M{Omega}{>=}2/5 , where M and {Omega} are the black-hole mass and angular velocity, respectively) possess this family of remarkably long-lived perturbation modes.

  10. Non-linear Q-clouds around Kerr black holes

    Directory of Open Access Journals (Sweden)

    Carlos Herdeiro

    2014-12-01

    Full Text Available Q-balls are regular extended ‘objects’ that exist for some non-gravitating, self-interacting, scalar field theories with a global, continuous, internal symmetry, on Minkowski spacetime. Here, analogous objects are also shown to exist around rotating (Kerr black holes, as non-linear bound states of a test scalar field. We dub such configurations Q-clouds. We focus on a complex massive scalar field with quartic plus hexic self-interactions. Without the self-interactions, linear clouds have been shown to exist, in synchronous rotation with the black hole horizon, along 1-dimensional subspaces – existence lines – of the Kerr 2-dimensional parameter space. They are zero modes of the superradiant instability. Non-linear Q-clouds, on the other hand, are also in synchronous rotation with the black hole horizon; but they exist on a 2-dimensional subspace, delimited by a minimal horizon angular velocity and by an appropriate existence line, wherein the non-linear terms become irrelevant and the Q-cloud reduces to a linear cloud. Thus, Q-clouds provide an example of scalar bound states around Kerr black holes which, generically, are not zero modes of the superradiant instability. We describe some physical properties of Q-clouds, whose backreaction leads to a new family of hairy black holes, continuously connected to the Kerr family.

  11. Non-linear Q-clouds around Kerr black holes

    Energy Technology Data Exchange (ETDEWEB)

    Herdeiro, Carlos; Radu, Eugen; Rúnarsson, Helgi, E-mail: helgi.runarsson@gmail.com

    2014-12-12

    Q-balls are regular extended ‘objects’ that exist for some non-gravitating, self-interacting, scalar field theories with a global, continuous, internal symmetry, on Minkowski spacetime. Here, analogous objects are also shown to exist around rotating (Kerr) black holes, as non-linear bound states of a test scalar field. We dub such configurations Q-clouds. We focus on a complex massive scalar field with quartic plus hexic self-interactions. Without the self-interactions, linear clouds have been shown to exist, in synchronous rotation with the black hole horizon, along 1-dimensional subspaces – existence lines – of the Kerr 2-dimensional parameter space. They are zero modes of the superradiant instability. Non-linear Q-clouds, on the other hand, are also in synchronous rotation with the black hole horizon; but they exist on a 2-dimensional subspace, delimited by a minimal horizon angular velocity and by an appropriate existence line, wherein the non-linear terms become irrelevant and the Q-cloud reduces to a linear cloud. Thus, Q-clouds provide an example of scalar bound states around Kerr black holes which, generically, are not zero modes of the superradiant instability. We describe some physical properties of Q-clouds, whose backreaction leads to a new family of hairy black holes, continuously connected to the Kerr family.

  12. Kerr black holes in horizon-generating form.

    Science.gov (United States)

    Hayward, Sean A

    2004-05-14

    New coordinates are given which describe nondegenerate Kerr black holes in dual-null foliations based on the outer (or inner) horizons, generalizing the Kruskal form for Schwarzschild black holes. The construction involves an area radius for the transverse surfaces and a generalization of the Regge-Wheeler radial function, both functions of the original radial coordinate only.

  13. Compact singularity-free Kerr-Newman-de Sitter instantons

    Science.gov (United States)

    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.

  14. Benchtop time-resolved magneto-optical Kerr magnetometer.

    Science.gov (United States)

    Barman, Anjan; Kimura, T; Otani, Y; Fukuma, Y; Akahane, K; Meguro, S

    2008-12-01

    We present here the construction and application of a compact benchtop time-resolved Kerr magnetometer to measure the magnetization precession in magnetic thin films and lithographically patterned elements. As opposed to very expensive femtosecond lasers this system is built upon a picosecond pulsed injection diode laser and electronic pulse and delay generators. The precession is triggered by the electronic pulses of controlled duration and shape, which is launched onto the sample by a microstrip line. We used polarized optical pulses synchronous to the electronic pulses to measure the magneto-optical Kerr rotation. The system is integrated in a conventional upright microscope configuration with separate illumination, imaging, and magneto-optical probe paths. The system offers high stability, relative ease of alignment, sample changing, and a long range of time delay. We demonstrate the measurements of time-resolved dynamics of a Permalloy microwire and microdot using this system, which showed dynamics at two different time scales.

  15. The matter-antimatter interpretation of Kerr spacetime

    Science.gov (United States)

    Villata, Massimo

    2015-08-01

    Repulsive gravity is not very popular in physics. However, one comes across it in at least two main occurrences in general relativity: in the negative-$r$ region of Kerr spacetime, and as the result of the gravitational interaction between matter and antimatter, when the latter is assumed to be CPT-transformed matter. Here we show how these two independent developments of general relativity are perfectly consistent in predicting gravitational repulsion and how the above Kerr negative-$r$ region can be interpreted as the habitat of antimatter. As a consequence, matter particles traveling along vortical geodesics can pass through the throat of a rotating black hole and emerge as antimatter particles (and vice versa). An experimental definitive answer on the gravitational behavior of antimatter is awaited in the next few years.

  16. The matter-antimatter interpretation of Kerr spacetime

    CERN Document Server

    Villata, M

    2014-01-01

    Repulsive gravity is not very popular in physics. However, one comes across it in at least two main occurrences in general relativity: in the negative-$r$ region of Kerr spacetime, and as the result of the gravitational interaction between matter and antimatter, when the latter is assumed to be CPT-transformed matter. Here we show how these two independent developments of general relativity are perfectly consistent in predicting gravitational repulsion and how the above Kerr negative-$r$ region can be interpreted as the habitat of antimatter. As a consequence, matter particles traveling along vortical geodesics can pass through the throat of a rotating black hole and emerge as antimatter particles (and vice versa). An experimental definitive answer on the gravitational behavior of antimatter is awaited in the next few years.

  17. The Quantization of a Kerr-AdS Black Hole

    Directory of Open Access Journals (Sweden)

    Claus Gerhardt

    2018-01-01

    Full Text Available We apply our model of quantum gravity to a Kerr-AdS space-time of dimension 2m+1, m≥2, where all rotational parameters are equal, resulting in a wave equation in a quantum space-time which has a sequence of solutions that can be expressed as a product of stationary and temporal eigenfunctions. The stationary eigenfunctions can be interpreted as radiation and the temporal ones as gravitational waves. The event horizon corresponds in the quantum model to a Cauchy hypersurface that can be crossed by causal curves in both directions such that the information paradox does not occur. We also prove that the Kerr-AdS space-time can be maximally extended by replacing in a generalized Boyer-Lindquist coordinate system the r variable by ρ=r2 such that the extended space-time has a timelike curvature singularity in ρ=-a2.

  18. Higher-order Kerr effect and harmonic cascading in gases

    OpenAIRE

    Bache, Morten; Eilenberger, Falk; Minardi, Stefano

    2012-01-01

    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 sat...

  19. Absorption of electromagnetic and gravitational waves by Kerr black holes

    Science.gov (United States)

    Leite, Luiz C. S.; Dolan, Sam R.; Crispino, Luís C. B.

    2017-11-01

    We calculate the absorption cross section for planar waves incident upon Kerr black holes, and present a unified picture for scalar, electromagnetic and gravitational waves. We highlight the spin-helicity effect that arises from a coupling between the rotation of the black hole and the helicity of a circularly-polarized wave. For the case of on-axis incidence, we introduce an extended 'sinc approximation' to quantify the spin-helicity effect in the strong-field regime.

  20. Photon emission of extremal Kerr-Newman black holes

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Shao-Wen; Gu, Bao-Min; Wang, Yong-Qiang; Liu, Yu-Xiao [Lanzhou University, Institute of Theoretical Physics, Lanzhou (China)

    2017-02-15

    In this paper, we deal with the null geodesics extending from the near-horizon region out to a distant observatory in an extremal Kerr-Newman black hole background. In particular, using the matched asymptotic expansion method, we analytically solve the null geodesics near the superradiant bound in the form of algebraic equations. For the case that the photon trajectories are limited in the equatorial plane, the shifts in the azimuthal angle and time are obtained. (orig.)

  1. Valley-selective optical Stark effect probed by Kerr rotation

    Science.gov (United States)

    LaMountain, Trevor; Bergeron, Hadallia; Balla, Itamar; Stanev, Teodor K.; Hersam, Mark C.; Stern, Nathaniel P.

    2018-01-01

    The ability to monitor and control distinct states is at the heart of emerging quantum technologies. The valley pseudospin in transition metal dichalcogenide (TMDC) monolayers is a promising degree of freedom for such control, with the optical Stark effect allowing for valley-selective manipulation of energy levels in WS2 and WSe2 using ultrafast optical pulses. Despite these advances, understanding of valley-sensitive optical Stark shifts in TMDCs has been limited by reflectance-based detection methods where the signal is small and prone to background effects. More sensitive polarization-based spectroscopy is required to better probe ultrafast Stark shifts for all-optical manipulation of valley energy levels. Here, we show time-resolved Kerr rotation to be a more sensitive probe of the valley-selective optical Stark effect in monolayer TMDCs. Compared to the established time-resolved reflectance methods, Kerr rotation is less sensitive to background effects. Kerr rotation provides a fivefold improvement in the signal-to-noise ratio of the Stark effect optical signal and a more precise estimate of the energy shift. This increased sensitivity allows for observation of an optical Stark shift in monolayer MoS2 that exhibits both valley and energy selectivity, demonstrating the promise of this method for investigating this effect in other layered materials and heterostructures.

  2. Gravitational redshift in Kerr-Newman geometry using gravity's rainbow

    Science.gov (United States)

    Dubey, Anuj Kumar; Sen, A. K.; Mazumdar, Bijoy

    2017-11-01

    Gravitational redshift is generally reported by most of the authors without considering the influence of the energy of the test particle using various spacetime geometries such as Schwarzschild, Reissner-Nordstrom, Kerr and Kerr-Newman geometries for static, charged static, rotating and charged rotating objects respectively. In the present work, the general expression for the energy dependent gravitational redshift is derived for charged rotating body using the Kerr-Newman geometry along with the energy dependent gravity's rainbow function. It is found that the gravitational redshift is influenced by the energy of the photon. One may obtain greater correction in the value of gravitational redshift, using the high energy photons. Knowing the value of gravitational redshift from a high energy sources such as Gamma-ray Bursters (GRB), one may obtain the idea of upper bounds on the dimensionless rainbow function parameter (ξ). Also there may be a possibility to introduce a new physical scale of the order of ξ/E_{Pl}.

  3. High contrast ballistic imaging using femtosecond optical Kerr gate of tellurite glass.

    Science.gov (United States)

    Tan, Wenjiang; Zhou, Zhiguang; Lin, Aoxiang; Si, Jinhai; Zhan, Pingping; Wu, Bin; Hou, Xun

    2013-03-25

    We investigated the ballistic imaging technique using femtosecond optical Kerr gate of a tellurite glass. High contrast images of an object hidden behind turbid media were obtained. Compared to the conventional femtosecond optical Kerr gate using fused quartz, the optical Kerr gate using tellurite glass has more capacity to acquire high quality images of the object hidden behind a high optical density turbid medium. The experimental results indicated that the tellurite glass is a good candidate as the optical Kerr material for the ballistic imaging technique due to its large optical nonlinearity.

  4. Higher-order Kerr effect and harmonic cascading in gases

    DEFF Research Database (Denmark)

    Bache, Morten; Eilenberger, Falk; Minardi, Stefano

    2012-01-01

    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....

  5. Higher-order Kerr effect and harmonic cascading in gases.

    Science.gov (United States)

    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.

  6. Dark matter spikes in the vicinity of Kerr black holes

    Science.gov (United States)

    Ferrer, Francesc; Medeiros da Rosa, Augusto; Will, Clifford M.

    2017-10-01

    The growth of a massive black hole will steepen the cold dark matter density at the center of a galaxy into a dense spike, enhancing the prospects for indirect detection. We study the impact of black hole spin on the density profile using the exact Kerr geometry of the black whole in a fully relativistic adiabatic growth framework. We find that, despite the transfer of angular momentum from the hole to the halo, rotation increases significantly the dark matter density close to the black hole. The gravitational effects are still dominated by the black hole within its influence radius, but the larger dark matter annihilation fluxes might be relevant for indirect detection estimates.

  7. Absorption of electromagnetic and gravitational waves by Kerr black holes

    Directory of Open Access Journals (Sweden)

    Luiz C.S. Leite

    2017-11-01

    Full Text Available We calculate the absorption cross section for planar waves incident upon Kerr black holes, and present a unified picture for scalar, electromagnetic and gravitational waves. We highlight the spin-helicity effect that arises from a coupling between the rotation of the black hole and the helicity of a circularly-polarized wave. For the case of on-axis incidence, we introduce an extended ‘sinc approximation’ to quantify the spin-helicity effect in the strong-field regime.

  8. Analogue Kerr-like geometries in a MHD inflow

    CERN Document Server

    Noda, Sousuke; Takahashi, Masaaki

    2016-01-01

    We present a model of the analogue black hole in magnetohydrodynamic (MHD) flow. For a two dimensional axisymmetric stationary trans-magnetosonic inflow with a sink, using the dispersion relation of the MHD waves, we introduce the effective geometries for magnetoacoustic waves propagating in the MHD flow. Investigating the properties of the effective potentials for magnetoacoustic rays, we find that the effective geometries can be classified into five types which include analogue spacetimes of the Kerr black hole, ultra spinning stars with ergoregions and spinning stars without ergoregions. We address the effects of the magnetic pressure and the magnetic tension on each magnetoacoustic geometries.

  9. Oscillatory dynamics in nanocavities with noninstantaneous Kerr response

    Energy Technology Data Exchange (ETDEWEB)

    Armaroli, Andrea; Malaguti, Stefania; Bellanca, Gaetano; Trillo, Stefano; Rossi, Alfredo de; Combrie, Sylvain [Department of Engineering, University of Ferrara, Via Saragat 1, IT 44122 Ferrara (Italy); Thales Research and Technology, Palaiseau Cedex FR 91767 (France)

    2011-11-15

    We investigate the impact of a finite response time of Kerr nonlinearities over the onset of spontaneous oscillations (self-pulsing) occurring in a nanocavity. The complete characterization of the underlying Hopf bifurcation in the full parameter space allows us to show the existence of a critical value of the response time and to envisage different regimes of competition with bistability. The transition from a stable oscillatory state to chaos is found to occur only in cavities which are detuned far off-resonance, which turns out to be mutually exclusive with the region where the cavity can operate as a bistable switch.

  10. Noise conversion in Kerr comb RF photonic oscillators

    CERN Document Server

    Matsko, Andrey B

    2014-01-01

    Transfer of amplitude and phase noise from a continuous wave optical pump to the repetition rate of a Kerr frequency comb is studied theoretically, with focus on generation of spectrally pure radio frequency (RF) signals via demodulation of the frequency comb on a fast photodiode. It is shown that both the high order chromatic dispersion of the resonator spectrum and frequency-dependent quality factor of the resonator modes facilitate the optical-to-RF noise conversion that limits spectral purity of the RF signal.

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

    Science.gov (United States)

    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.

  12. Effects of resonator input power on Kerr lens mode-locked lasers

    Indian Academy of Sciences (India)

    Using the ABCD matrix method, the common stability region between the sagittal and tangential planes of a four-mirror Kerr lens mode-locked (KLM) laser cavity is obtained for different ranges of input power. In addition, the effect of the input power on the Kerr lens sensitivity is investigated. Optimal input power and position ...

  13. Managing the research university : Clark Kerr and the University of California

    NARCIS (Netherlands)

    Soo, M; Carson, C

    In the 1950s and 1960s, Clark Kerr led the University of California's Berkeley campus, and then the University of California as a whole. Throughout these years, he developed a system of managerial strategies. This paper shows how Kerr's administrative views drew upon his background in industrial

  14. Enhanced Kerr nonlinearity in a tunnel-coupled double quantum wells

    Science.gov (United States)

    Asadpour, S. H.; Hamedi, Hamid Reza; Eslami-Majd, A.; Sahrai, Mostafa

    2011-11-01

    The giant Kerr nonlinearity in an asymmetric coupled quantum well (CQW) driven by probe and control laser fields based on intersubband transitions is investigated. The effect of controlling parameters such as intensity of coupling field and electron tunneling on nonlinear behavior of the system is then discussed. It is shown that the enhanced Kerr nonlinearity with reduced linear and nonlinear absorption can be achieved.

  15. Elkind's Theory of Adolescent Egocentrism as Expressed in Selected Characters of M. E. Kerr.

    Science.gov (United States)

    Matter, Roxana Marie

    1982-01-01

    Studied the extent to which the unique and typical behaviors of adolescent egocentrism are manifested by the adolescent characters in Kerr's novels. Analysis shows at least one of the egocentrism characteristics is present in each character. Because Kerr's characters are realistic they provide helpful models for adolescents and adults. (JAC)

  16. Color and Kerr rotation in a dielectric/ferromagnetic double layers structure

    Science.gov (United States)

    Zhang, Jing; Wang, Hai; Qu, Xin; Zhou, Yunsong

    2017-02-01

    By the multiple reflections and transmissions in a dielectric on a ferromagnetic metal, color and Kerr rotation correlate with each other. It is revealed that the real refractive index of dielectric plays a major role on the variations of color and Kerr signal, while the absorbing term adjusts the intensive color exhibition and Kerr enhancement at much thinner dielectric thickness. The intensive Kerr signal variation is always accompanied by the color transition with the dielectric thickness changing. Experimental results observed in silicon(or silica)/iron samples are well consistent with calculations. Nanometer dielectric optical coating can not only enhance Kerr effect but also endow magnetic surface with chromatics, which has promising potential applications in anti-fake brands, colorful decorations, camouflages, and even bionics.

  17. Plasmon-enhanced Kerr nonlinearity via subwavelength-confined anisotropic Purcell factors

    Science.gov (United States)

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

    2016-10-01

    We theoretically investigate the enhancement of Kerr nonlinearity through anisotropic Purcell factors provided by plasmon nanostructures. In a three-level atomic system with crossing damping, larger anisotropism of Purcell factors leads to more enhanced Kerr nonlinearity in electromagnetically induced transparency windows. While for fixed anisotropic Purcell factors, Kerr nonlinearity with orthogonal dipole moments increases with the decrease of its crossing damping, and Kerr nonlinearity with nonorthogonal dipole moments is very sensitive to both the value of crossing damping and the orientation of the dipole moments. We design the non-resonant gold nanorods array, which only provides subwavelength-confined anisotropic Purcell factors, and demonstrate that the Kerr nonlinearity of cesium atoms close to the nanorods array can be modulated at the nanoscale. These findings should have potential application in ultracompact quantum logic devices.

  18. Proposal for electro-optic multiplier based on dual transverse electro-optic Kerr effect.

    Science.gov (United States)

    Li, Changsheng

    2008-10-20

    A novel electro-optic multiplier is proposed, which can perform voltage multiplication operation by use of the Kerr medium exhibiting dual transverse electro-optic Kerr effect. In this kind of Kerr medium, electro-optic phase retardation is proportional to the square of its applied electric field, and orientations of the field-induced birefringent axes are only related to the direction of the field. Based on this effect, we can design an electro-optic multiplier by selecting the crystals of 6/mmm, 432, and m3m classes and isotropic Kerr media such as glass. Simple calculation demonstrates that a kind of glass-ceramic material with a large Kerr constant can be used for the design of the proposed electro-optic multiplier.

  19. Note on the Cardoso-Pani-Rico parametrization to test the Kerr black hole hypothesis

    Science.gov (United States)

    Bambi, Cosimo

    2014-08-01

    The construction of a generic parametrization to describe the spacetime geometry around astrophysical black hole candidates is an important step to test the Kerr black hole hypothesis. In the last few years, the Johannsen-Psaltis metric has been the most common framework to study possible deviations from the Kerr solution with present and near-future observations. Recently, Cardoso, Pani, and Rico have proposed a more general parametrization. The aim of the present paper is to study this new metric in a specific context, namely, the thermal spectrum of geometrically thin and optically thick accretion disks. The most relevant finding is that the spacetime geometry around objects that look like very-fast-rotating Kerr black holes may still have large deviations from the Kerr solution. This is not the case with the Johannsen-Psaltis metric, which means the latter is missing an important class of non-Kerr spacetimes.

  20. Origins of Kerr phase and orientational phase in polymer-dispersed liquid crystal

    Science.gov (United States)

    Chang, Chia-Ming; Lin, Yi-Hsin; Reshetnyak, Victor; Park, Chui Ho; Manda, Ramesh; Lee, Seung Hee

    2017-08-01

    The anisotropic properties of nematic liquid crystals result in polarization dependency which leads to requirement of at least a polarizer in liquid crystal photonic devices. To develop polarizer free phase modulation, Kerr effect is one of the path. The phase modulation in polymer dispersed liquid crystals (PDLCs) is shown to have two parts: Kerr phase, which is the optical phase modulation linearly proportional to a square of electric field, and orientational phase. However, many puzzles are still under investigation: the origins of Kerr phase, the relation between Kerr phase and orientational phase, and how two-steps of electro-optical (EO) response relates to Kerr phase and orientational phase. We investigated the origins of Kerr phase and orientational phase in PDLC and their connection to two-step EO response. In our study, the Kerr phase is a result of LC orientation in the center of LC droplets. The orientational phase attribute to orientation of LC molecules near LC-polymer interfaces. The two phase in PDLC samples are adjustable depending on droplet size. We also found that two-steps EO response existing in small droplet (<33 nm) is related to Kerr phase and orientational phase. A modified PDLC model related to the Kerr phase and orientational phase is also proposed. Besides the conventional features of PDLC, such as polarization independent optical phase shift and response time independent of cell gap, we believe the Kerr phase and orientational phase with different response times ( msec) in PDLC pave a way for designing versatile photonic devices with pure optical phase modulation.

  1. Cosmic censorship conjecture in Kerr-Sen black hole

    Science.gov (United States)

    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.

  2. The Kerr black hole as a quantum rotator

    CERN Document Server

    Gour, G

    2003-01-01

    It has been proposed by Bekenstein and others that the horizon area of a black hole conforms, upon quantization, to a discrete and uniformly spaced spectrum. In this paper, we consider the area spectrum for the highly non-trivial case of a rotating (Kerr) black-hole solution. Following a prior work by Barvinsky, Das and Kunstatter, we are able to express the area spectrum in terms of an integer-valued quantum number and an angular-momentum operator. (The procedure employs a periodicity condition that can be viewed as a conjectural, although well-motivated input.) Moreover, by using an analogy between the Kerr black hole and a quantum rotator, we are able to quantize the angular-momentum sector. We find the area spectrum to be A sub n sub , sub J sub sub c sub sub l = 8 pi h-bar (n + J sub c sub l + 1/2), where n and J sub c sub l are both integers. The quantum number J sub c sub l is related to but distinct from the eigenvalue j of the angular momentum of the black hole. Actually, it represents the 'classical...

  3. A Zeroth Law Compatible Model to Kerr Black Hole Thermodynamics

    Directory of Open Access Journals (Sweden)

    Viktor G. Czinner

    2017-02-01

    Full Text Available We consider the thermodynamic and stability problem of Kerr black holes arising from the nonextensive/nonadditive nature of the Bekenstein–Hawking entropy formula. Nonadditive thermodynamics is often criticized by asserting that the zeroth law cannot be compatible with nonadditive composition rules, so in this work we follow the so-called formal logarithm method to derive an additive entropy function for Kerr black holes also satisfying the zeroth law’s requirement. Starting from the most general, equilibrium compatible, nonadditive entropy composition rule of Abe, we consider the simplest non-parametric approach that is generated by the explicit nonadditive form of the Bekenstein–Hawking formula. This analysis extends our previous results on the Schwarzschild case, and shows that the zeroth law-compatible temperature function in the model is independent of the mass–energy parameter of the black hole. By applying the Poincaré turning point method, we also study the thermodynamic stability problem in the system.

  4. The Kerr-Schild double copy in curved spacetime

    Science.gov (United States)

    Bahjat-Abbas, Nadia; Luna, Andrés; White, Chris D.

    2017-12-01

    The double copy is a much-studied relationship between scattering amplitudes in gauge and gravity theories, that has subsequently been extended to classical field solutions. In nearly all previous examples, the graviton field is defined around Minkowski space. Recently, it has been suggested that one may set up a double copy for gravitons defined around a non-trivial background. We investigate this idea from the point of view of the classical double copy. First, we use Kerr-Schild spacetimes to construct graviton solutions in curved space, as double copies of gauge fields on non-zero gauge backgrounds. Next, we find that we can reinterpret such cases in terms of a graviton on a non-Minkowski background, whose single copy is a gauge field in the same background spacetime. The latter type of double copy persists even when the background is not of Kerr-Schild form, and we provide examples involving conformally flat metrics. Our results will be useful in extending the remit of the double copy, including to possible cosmological applications.

  5. Kerr comb generation from the perspective of spatial dissipative structures

    Science.gov (United States)

    Coillet, Aurélien; Balakireva, Irina; Saleh, Khaldoun; Henriet, Rémi; Larger, Laurent; Chembo, Yanne K.

    2014-03-01

    The theoretical understanding of Kerr combs has been the object of extensive efforts worldwide in the last ten years. Several insights have been provided since then into this problem and have enabled significant progress for the optimization and tailoring of these combs. Here, we investigate the formation of dissipative structures in crystalline whispering-gallery mode disk resonators that are pumped in different dispersion regimes. In the Fourier domain, these dissipative structures correspond to specific types of mode-locked Kerr optical frequency combs. Depending on the sign of the second-order chromatic dispersion and on the pumping conditions, we show that either bright or dark cavity solitons can emerge, and we show these two regimes are associated with characteristic spectral signatures that can be discriminated experimentally. We use the Lugiato-Lefever spatiotemporal formalism to investigate the temporal dynamics leading to the formation of these azimuthal solitons, as well as the emergence of Turing patterns. The theoretical results are in excellent agreement with experimental measurements that are obtained using calcium and magnesium fluoride disk resonators pumped near 1550 nm.

  6. The Kerr/CFT Correspondence and its Extensions

    Directory of Open Access Journals (Sweden)

    Geoffrey Compère

    2012-10-01

    Full Text Available We present a first-principles derivation of the main results of the Kerr/CFT correspondence and its extensions using only tools from gravity and quantum field theory, filling a few gaps in the literature when necessary. Firstly, we review properties of extremal black holes that imply, according to semi-classical quantization rules, that their near-horizon quantum states form a centrally-extended representation of the one-dimensional conformal group. This motivates the conjecture that the extremal Kerr and Reissner–Nordström black holes are dual to the chiral limit of a two-dimensional CFT. We also motivate the existence of an SL (2,ℤ family of two-dimensional CFTs, which describe in their chiral limit the extremal Kerr–Newman black hole. We present generalizations in anti-de Sitter spacetime and discuss other matter-coupling and higher-derivative corrections. Secondly, we show how a near-chiral limit of these CFTs reproduces the dynamics of near-superradiant probes around near-extremal black holes in the semi-classical limit. Thirdly, we review how the hidden conformal symmetries of asymptotically-flat black holes away from extremality, combined with their properties at extremality, allow for a microscopic accounting of the entropy of non-extremal asymptotically-flat rotating or charged black holes. We conclude with a list of open problems.

  7. Collision of an object in the transition from adiabatic inspiral to plunge around a Kerr black hole

    CERN Document Server

    Harada, Tomohiro

    2011-01-01

    An inspiralling object of mass $\\mu$ around a Kerr black hole of mass $M (\\gg \\mu)$ experiences a continuous transition near the innermost stable circular orbit from adiabatic inspiral to plunge into the horizon as gravitational radiation extracts its energy and angular momentum. We investigate the collision of such an object with a generic counterpart around a Kerr black hole. We find that the angular momentum of the object is fine-tuned through gravitational radiation and that the high-velocity collision of the object with a generic counterpart naturally occurs around a nearly maximally rotating black hole. We also find that the centre-of-mass energy can be far beyond the Planck energy for dark matter particles colliding around a stellar mass black hole and as high as $10^{58}$ erg for stellar mass compact objects colliding around a supermassive black hole, where the present transition formalism is well justified. Therefore, rapidly rotating black holes can accelerate objects inspiralling around them to ene...

  8. Advanced magneto-optical Kerr effect measurements of superconductors at low temperatures

    Science.gov (United States)

    Stahl, Claudia; Gräfe, Joachim; Ruoß, Stephen; Zahn, Patrick; Bayer, Jonas; Simmendinger, Julian; Schütz, Gisela; Albrecht, Joachim

    2017-10-01

    Magneto-optical Kerr-effect (MOKE) measurements of superconducting films with soft-magnetic coatings are performed at low temperatures using a laser-based MOKE set-up. An elaborate measurement scheme with internal reference allows the quantitative comparison of the temperature dependent Kerr-amplitude with the magnetic field generated by supercurrents. For this purpose, an amorphous CoFeB thin film exhibiting a large Kerr-signal is deposited directly on top of the YBCO superconductor acting as field sensing layer. It is shown that the resulting magnetic hysteresis loops of the soft-magnetic film can be used to reconstruct the electric properties of the superconductor.

  9. Stabilization of vortex beams in Kerr media by nonlinear absorption

    Science.gov (United States)

    Porras, Miguel A.; Carvalho, Márcio; Leblond, Hervé; Malomed, Boris A.

    2016-11-01

    We elaborate a solution for the problem of stable propagation of transversely localized vortex beams in homogeneous optical media with self-focusing Kerr nonlinearity. Stationary nonlinear Bessel-vortex states are stabilized against azimuthal breakup and collapse by multiphoton absorption, while the respective power loss is offset by the radial influx of the power from an intrinsic reservoir. A linear stability analysis and direct numerical simulations reveal a region of stability of these vortices. Beams with multiple vorticities have their stability regions too. These beams can then form robust tubular filaments in transparent dielectrics as common as air, water, and optical glasses at sufficiently high intensities. We also show that the tubular, rotating, and specklelike filamentation regimes, previously observed in experiments with axicon-generated Bessel beams, can be explained as manifestations of the stability or instability of a specific nonlinear Bessel-vortex state, which is fully identified.

  10. Relativistic tidal effects in non standard Kerr space-time

    CERN Document Server

    Maselli, Andrea; Laguna, Pablo

    2016-01-01

    Astrophysical phenomena involving massive black holes (BHs) in close binaries are expected to leave detectable signatures in the electromagnetic and gravitational-wave spectrum. Such imprints may provide precious information to probe the space-time around rotating BHs, and to reveal new insights on the nature of gravity in the strong-field regime. To support this observational window it is crucial to develop suitable tests to verify the predictions of General Relativity (GR). In this framework, the metric recently proposed by Johannsen and Psaltis parametrises strong field deviations from a Kerr space-time in a theory-independent way. In the following, we make use of this approach to describe the tidal field produced by spinning BHs. We compute the gravito-magnetic and gravito-electric tidal tensors for particles moving on equatorial circular geodesics, comparing our results with those obtained in the standard GR scenario. Our calculations show significant differences even for distances far form the last stab...

  11. Is the Kerr black hole a super accelerator?

    Science.gov (United States)

    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.

  12. Particle dynamics near Kerr-MOG black hole

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, M.; Shahzadi, Misbah [University of the Punjab, Department of Mathematics, Lahore (Pakistan)

    2017-06-15

    This paper explores the dynamics of both neutral and charged particles orbiting near a rotating black hole in scalar-tensor-vector gravity. We study the conditions for the particle to escape at the innermost stable circular orbit. We investigate the stability of orbits through the effective potential and Lyapunov exponent in the presence of a magnetic field. The effective force acting on particle is also discussed. We also study the center of mass energy of particle collision near the horizon of this black hole. Finally, we compare our results with the particle motion around Schwarzschild, Kerr and Schwarzschild-MOG black holes. It is concluded that the external magnetic field, spin parameter and dimensionless parameter of the theory have strong effects on the particle dynamics in modified gravity. (orig.)

  13. Particle dynamics near Kerr-MOG black hole

    Science.gov (United States)

    Sharif, M.; Shahzadi, Misbah

    2017-06-01

    This paper explores the dynamics of both neutral and charged particles orbiting near a rotating black hole in scalar-tensor-vector gravity. We study the conditions for the particle to escape at the innermost stable circular orbit. We investigate the stability of orbits through the effective potential and Lyapunov exponent in the presence of a magnetic field. The effective force acting on particle is also discussed. We also study the center of mass energy of particle collision near the horizon of this black hole. Finally, we compare our results with the particle motion around Schwarzschild, Kerr and Schwarzschild-MOG black holes. It is concluded that the external magnetic field, spin parameter and dimensionless parameter of the theory have strong effects on the particle dynamics in modified gravity.

  14. High spectral purity Kerr frequency comb radio frequency photonic oscillator.

    Science.gov (United States)

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

    2015-08-11

    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.

  15. Higher-order geodesic deviations applied to the Kerr metric

    CERN Document Server

    Colistete, R J; Kerner, R

    2002-01-01

    Starting with an exact and simple geodesic, we generate approximate geodesics by summing up higher-order geodesic deviations within a general relativistic setting, without using Newtonian and post-Newtonian approximations. We apply this method to the problem of closed orbital motion of test particles in the Kerr metric spacetime. With a simple circular orbit in the equatorial plane taken as the initial geodesic, we obtain finite eccentricity orbits in the form of Taylor series with the eccentricity playing the role of a small parameter. The explicit expressions of these higher-order geodesic deviations are derived using successive systems of linear equations with constant coefficients, whose solutions are of harmonic oscillator type. This scheme gives best results when applied to orbits with low eccentricities, but with arbitrary possible values of (GM/Rc sup 2).

  16. How to observe a non-Kerr spacetime using gravitational waves.

    Science.gov (United States)

    Apostolatos, Theocharis A; Lukes-Gerakopoulos, Georgios; Contopoulos, George

    2009-09-11

    We present a generic criterion which can be used in gravitational-wave data analysis to distinguish an extreme-mass-ratio inspiral into a Kerr background spacetime from one into a non-Kerr spacetime. We exploit the fact that when an integrable system, such as the system that describes geodesic orbits in a Kerr spacetime, is perturbed, the tori in phase space which initially corresponded to resonances disintegrate so as to form Birkhoff chains on a surface of section. The KAM curves of the islands in such a chain share the same ratio of frequencies, even though the frequencies themselves vary from one KAM curve to another inside an island. However the KAM curves, which do not lie in a Birkhoff chain, do not share this characteristic property. Such a temporal constancy of the ratio of frequencies during the evolution of the gravitational-wave signal will signal a non-Kerr spacetime.

  17. Soft x-ray magneto-optic Kerr rotation and element-specific hysteresis measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kortright, J.B.; Rice, M.

    1996-03-01

    Soft x-ray magneto-optic Kerr rotation has been measured using a continuously tunable multilayer linear polarizer in the beam reflected form samples in applied magnetic fields. Like magnetic circular dichroism, Kerr rotation in the soft x-ray can be element - specific and much larger than in the visible spectral range when the photon energy is tuned near atomic core resonances. Thus sensitive element-specific hysteresis measurements are possible with this technique. Examples showing large Kerr rotation from an Fe film and element-specific hysteresis loops of the Fe and Cr in an Fe/Cr multilayer demonstrate these new capabilities. Some consequences of the strong anomalous dispersion near the FeL{sub 2,3} edges to the Kerr rotation are discussed.

  18. The Euclidean quantisation of Kerr-Newman-de Sitter black holes

    Energy Technology Data Exchange (ETDEWEB)

    Chruściel, Piotr T.; Hörzinger, Michael [Erwin Schrödinger Institute and Faculty of Physics, University of Vienna,Vienna (Austria)

    2016-04-04

    We study the family of Einstein-Maxwell instantons associated with the Kerr-Newman metrics with a positive cosmological constant. This leads to a quantisation condition on the masses, charges, and angular momentum parameters of the resulting Euclidean solutions.

  19. Universality of the quasinormal spectrum of near-extremal Kerr-Newman black holes

    Energy Technology Data Exchange (ETDEWEB)

    Hod, Shahar [The Ruppin Academic Center, Emeq Hefer (Israel); The Hadassah Institute, Jerusalem (Israel)

    2015-06-15

    Our current knowledge about the quasinormal resonance spectrum of charged and rotating Kerr-Newman black holes is quite poor. This unsatisfactory situation is a direct consequence of the fact that all attempts to decouple the gravitational and electromagnetic perturbations of generic Kerr-Newman black holes have failed thus far. Recently, Zilhao et al. (Phys Rev D 90:12, 124088, 2014. arXiv:1410.0694) have studied the nonlinear stability of Kerr-Newman black holes. We show here that their numerical results for the time evolutions of the spacetime deformations of near-extremal Kerr-Newman black holes are described extremely well by a simple and universal analytical formula for the quasinormal resonances of the black holes. This formula is expressed in terms of the black-hole physical parameters: the horizon angular velocity Ω{sub H} and the Bekenstein-Hawking temperature T{sub BH}. (orig.)

  20. A platform for time-resolved scanning Kerr microscopy in the near-field.

    Science.gov (United States)

    Keatley, Paul S; Loughran, Thomas H J; Hendry, Euan; Barnes, William L; Hicken, Robert J; Childress, Jeffrey R; Katine, Jordan A

    2017-12-01

    Time-resolved scanning Kerr microscopy (TRSKM) is a powerful technique for the investigation of picosecond magnetization dynamics at sub-micron length scales by means of the magneto-optical Kerr effect (MOKE). The spatial resolution of conventional (focused) Kerr microscopy using a microscope objective lens is determined by the optical diffraction limit so that the nanoscale character of the magnetization dynamics is lost. Here we present a platform to overcome this limitation by means of a near-field TRSKM that incorporates an atomic force microscope (AFM) with optical access to a metallic AFM probe with a nanoscale aperture at its tip. We demonstrate the near-field capability of the instrument through the comparison of time-resolved polar Kerr images of magnetization dynamics within a microscale NiFe rectangle acquired using both near-field and focused TRSKM techniques at a wavelength of 800 nm. The flux-closure domain state of the in-plane equilibrium magnetization provided the maximum possible dynamic polar Kerr contrast across the central domain wall and enabled an assessment of the magneto-optical spatial resolution of each technique. Line profiles extracted from the Kerr images demonstrate that the near-field spatial resolution was enhanced with respect to that of the focused Kerr images. Furthermore, the near-field polar Kerr signal (∼1 mdeg) was more than half that of the focused Kerr signal, despite the potential loss of probe light due to internal reflections within the AFM tip. We have confirmed the near-field operation by exploring the influence of the tip-sample separation and have determined the spatial resolution to be ∼550 nm for an aperture with a sub-wavelength diameter of 400 nm. The spatial resolution of the near-field TRSKM was in good agreement with finite element modeling of the aperture. Large amplitude electric field along regions of the modeled aperture that lie perpendicular to the incident polarization indicate that the aperture can

  1. A platform for time-resolved scanning Kerr microscopy in the near-field

    Science.gov (United States)

    Keatley, Paul S.; Loughran, Thomas H. J.; Hendry, Euan; Barnes, William L.; Hicken, Robert J.; Childress, Jeffrey R.; Katine, Jordan A.

    2017-12-01

    Time-resolved scanning Kerr microscopy (TRSKM) is a powerful technique for the investigation of picosecond magnetization dynamics at sub-micron length scales by means of the magneto-optical Kerr effect (MOKE). The spatial resolution of conventional (focused) Kerr microscopy using a microscope objective lens is determined by the optical diffraction limit so that the nanoscale character of the magnetization dynamics is lost. Here we present a platform to overcome this limitation by means of a near-field TRSKM that incorporates an atomic force microscope (AFM) with optical access to a metallic AFM probe with a nanoscale aperture at its tip. We demonstrate the near-field capability of the instrument through the comparison of time-resolved polar Kerr images of magnetization dynamics within a microscale NiFe rectangle acquired using both near-field and focused TRSKM techniques at a wavelength of 800 nm. The flux-closure domain state of the in-plane equilibrium magnetization provided the maximum possible dynamic polar Kerr contrast across the central domain wall and enabled an assessment of the magneto-optical spatial resolution of each technique. Line profiles extracted from the Kerr images demonstrate that the near-field spatial resolution was enhanced with respect to that of the focused Kerr images. Furthermore, the near-field polar Kerr signal (˜1 mdeg) was more than half that of the focused Kerr signal, despite the potential loss of probe light due to internal reflections within the AFM tip. We have confirmed the near-field operation by exploring the influence of the tip-sample separation and have determined the spatial resolution to be ˜550 nm for an aperture with a sub-wavelength diameter of 400 nm. The spatial resolution of the near-field TRSKM was in good agreement with finite element modeling of the aperture. Large amplitude electric field along regions of the modeled aperture that lie perpendicular to the incident polarization indicate that the aperture can

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

    Science.gov (United States)

    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.

  3. Modeling of octave-spanning Kerr frequency combs using a generalized mean-field Lugiato-Lefever model.

    Science.gov (United States)

    Coen, Stéphane; Randle, Hamish G; Sylvestre, Thibaut; Erkintalo, Miro

    2013-01-01

    A generalized Lugiato-Lefever equation is numerically solved with a Newton-Raphson method to model Kerr frequency combs. We obtain excellent agreement with past experiments, even for an octave-spanning comb. Simulations are much faster than with any other technique despite including more modes than ever before. Our study reveals that Kerr combs are associated with temporal cavity solitons and dispersive waves, and opens up new avenues for the understanding of Kerr-comb formation.

  4. Magneto-Optic Kerr Effect in a Magnetized Electron Gun

    Science.gov (United States)

    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.

  5. What is the longitudinal magneto-optical Kerr effect?

    Science.gov (United States)

    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.

  6. The Gesell Institute Responds.

    Science.gov (United States)

    Young Children, 1987

    1987-01-01

    Responding to Dr. Meisels' article concerning the uses and abuses of the Gesell readiness tests, the Gesell Institute of Child development maintains that the Gesell series of assessments are used by schools to gain a fuller developmental understanding of the child and have been predictive of school success. (BB)

  7. Responding to Tragedy

    Science.gov (United States)

    Coopman, J. T.

    2009-01-01

    In this article, the author, a superintendent of Clark-Pleasant School Corporation in Whiteland, Indiana, relates how she and the school community responded to a car accident that killed two students. The author stresses the need to develop a comprehensive crisis plan. It is also important to be sensitive to the needs of family members who are…

  8. Efficiency estimates and practical aspects of an optical Kerr gate for time-resolved luminescence spectroscopy

    Science.gov (United States)

    Dmitruk, I.; Shynkarenko, Ye; Dmytruk, A.; Aleksiuk, D.; Kadan, V.; Korenyuk, P.; Zubrilin, N.; Blonskiy, I.

    2016-12-01

    We report experience of assembling an optical Kerr gate setup at the Femtosecond Laser Center for collective use at the Institute of Physics of the National Academy of Sciences of Ukraine. This offers an inexpensive solution to the problem of time-resolved luminescence spectroscopy. Practical aspects of its design and alignment are discussed and its main characteristics are evaluated. Theoretical analysis and numerical estimates are performed to evaluate the efficiency and the response time of an optical Kerr gate setup for fluorescence spectroscopy with subpicosecond time resolution. The theoretically calculated efficiency is compared with the experimentally measured one of ~12% for Crown 5 glass and ~2% for fused silica. Other characteristics of the Kerr gate are analyzed and ways to improve them are discussed. A method of compensation for the refractive index dispersion in a Kerr gate medium is suggested. Examples of the application of the optical Kerr gate setup for measurements of the time-resolved luminescence of Astra Phloxine and Coumarin 30 dyes and both linear and nonlinear chirp parameters of a supercontinuum are presented.

  9. Negative Kerr nonlinearity of graphene as seen via chirped-pulse-pumped self-phase modulation

    CERN Document Server

    Vermeulen, Nathalie; Cheng, JinLuo; Pasternak, Iwona; Krajewska, Aleksandra; Ciuk, Tymoteusz; Strupinski, Wlodek; Thienpont, Hugo; Van Erps, Jurgen

    2016-01-01

    We experimentally demonstrate a negative Kerr nonlinearity for quasi-undoped graphene. Hereto, we introduce the method of chirped-pulse-pumped self-phase modulation and apply it to graphene-covered silicon waveguides at telecom wavelengths. The extracted Kerr-nonlinear index for graphene equals n2,gr = -10^(-13) m^2/W. Whereas the sign of n2,gr turns out to be negative in contrast to what has been assumed so far, its magnitude is in correspondence with that observed in earlier experiments. Graphene's negative Kerr nonlinearity strongly impacts how graphene should be exploited for enhancing the nonlinear response of photonic (integrated) devices exhibiting a positive nonlinearity. It also opens up the possibility of using graphene to annihilate unwanted nonlinear effects in such devices, to develop unexplored approaches for establishing Kerr processes, and to extend the scope of the "periodic poling" method often used for second-order nonlinearities towards third-order Kerr processes. Because of the generic na...

  10. Stray-field-induced Faraday contributions in wide-field Kerr microscopy and -magnetometry

    Energy Technology Data Exchange (ETDEWEB)

    Markó, D.; Soldatov, I. [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Institute for Metallic Materials, PO 270116, D-01171 Dresden (Germany); Dresden University of Technology, Institute for Materials Science, D-01062 Dresden (Germany); Tekielak, M. [Institute of Experimental Physics, University of Bialystok, Lipowa 41, Bialystok 15-424 Poland (Poland); Schäfer, R., E-mail: r.schaefer@ifw-dresden.de [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Institute for Metallic Materials, PO 270116, D-01171 Dresden (Germany); Dresden University of Technology, Institute for Materials Science, D-01062 Dresden (Germany)

    2015-12-15

    The magnetic domain contrast in wide-field Kerr microscopy on bulk specimens can be substantially distorted by non-linear, field-dependent Faraday rotations in the objective lens that are caused by stray-field components emerging from the specimen. These Faraday contributions, which were detected by Kerr-magnetometry on grain-oriented iron–silicon steel samples, are thoroughly elaborated and characterized. They express themselves as a field-dependent gray-scale offset to the domain contrast and in highly distorted surface magnetization curves if optically measured in a wide field Kerr microscope. An experimental method to avoid such distortions is suggested. In the course of these studies, a low-permeability part in the surface magnetization loop of slightly misoriented (110)-surfaces in iron–silicon sheets was discovered that is attributed to demagnetization effects in direction perpendicular to the sheet surface. - Highlights: • Magnetizing a finite sample in a Kerr microscope leads to sample-generated stray-fields. • They cause non-linear, field- and position-dependent Faraday rotations in the objective. • This leads to a modulation of the Kerr contrast and to distorted MOKE loops. • A method to compensate these Faraday rotations is presented.

  11. Phase-sensitive Kerr nonlinearity for closed-loop quantum systems

    Science.gov (United States)

    Hamedi, H. R.; Juzeliūnas, G.

    2015-05-01

    The third-order susceptibility is investigated in a five-level atomic system in which the laser beams couple the ground state to a four-level closed-loop system. It is found that under the condition of the multiphoton resonance, one can enhance the Kerr nonlinearity of such a medium by properly adjusting the amplitudes and phases of the applied fields. In this case, the linear and nonlinear absorption reduce considerably in a region with a positive group velocity. It is demonstrated that the third-order susceptibility is very sensitive to the relative phase of the applied fields. An analytical model is presented to elucidate such phase control of the Kerr nonlinearity. A comparison is also made between the Kerr-nonlinear indices for the five-, four-, and three-level systems. It is realized that the magnitude of the Kerr nonlinearity for the five-level system is larger than that of the three- and four-level counterparts. Finally, it is shown that effect of Doppler broadening can lead to an enhanced Kerr nonlinearity while maintaining linear and nonlinear absorption.

  12. Responding to Mechanical Antigravity

    Science.gov (United States)

    Millis, Marc G.; Thomas, Nicholas E.

    2006-01-01

    Based on the experiences of the NASA Breakthrough Propulsion Physics Project, suggestions are offered for constructively responding to proposals that purport breakthrough propulsion using mechanical devices. Because of the relatively large number of unsolicited submissions received (about 1 per workday) and because many of these involve similar concepts, this report is offered to help the would-be submitters make genuine progress as well as to help reviewers respond to such submissions. Devices that use oscillating masses or gyroscope falsely appear to create net thrust through differential friction or by misinterpreting torques as linear forces. To cover both the possibility of an errant claim and a genuine discovery, reviews should require that submitters meet minimal thresholds of proof before engaging in further correspondence; such as achieving sustained deflection of a level-platform pendulum in the case of mechanical thrusters.

  13. On the branching of the quasinormal resonances of near-extremal Kerr black holes

    Energy Technology Data Exchange (ETDEWEB)

    Hod, Shahar [The Ruppin Academic Center, Emeq Hefer (Israel); The Hadassah Institute, Jerusalem (Israel)

    2015-11-15

    It has recently been shown by Yang et al. (Phys Rev D 87:041502(R), 2013a; Phys Rev D 88:044047, 2013b) that rotating Kerr black holes are characterized by two distinct sets of quasinormal resonances. These two families of quasinormal resonances display qualitatively different asymptotic behaviors in the extremal (a/M → 1) black-hole limit: the zero-damping modes are characterized by relaxation times which tend to infinity in the extremal black-hole limit (Iω → 0 as a/M @→ 1), whereas the damped modes (DMs) are characterized by non-zero damping rates (Iω @→ finite-values as a/M @→ 1). In this paper we refute the claim made by Yang et al. that co-rotating DMs of near-extremal black holes are restricted to the limited range 0 ≤ μ μ{sub c} regime, the regime which was claimed by Yang et al. not to contain DMs. We show that these co-rotating DMs (in the regime μ > μ{sub c}) are expected to characterize the resonance spectra of rapidly rotating (near-extremal) black holes with a/M >or similar 1 - 10{sup -9}. (orig.)

  14. On the branching of the quasinormal resonances of near-extremal Kerr black holes

    Energy Technology Data Exchange (ETDEWEB)

    Hod, Shahar, E-mail: shaharhod@gmail.com [The Ruppin Academic Center, 40250, Emeq Hefer (Israel); The Hadassah Institute, 91010, Jerusalem (Israel)

    2015-11-02

    It has recently been shown by Yang et al. (Phys Rev D 87:041502(R), 2013a; Phys Rev D 88:044047, 2013b) that rotating Kerr black holes are characterized by two distinct sets of quasinormal resonances. These two families of quasinormal resonances display qualitatively different asymptotic behaviors in the extremal (a/M→1) black-hole limit: the zero-damping modes are characterized by relaxation times which tend to infinity in the extremal black-hole limit (Iω→0 as a/M→1), whereas the damped modes (DMs) are characterized by non-zero damping rates (Iω→ finite-values as a/M→1). In this paper we refute the claim made by Yang et al. that co-rotating DMs of near-extremal black holes are restricted to the limited range 0≤μ≲μ{sub c}≈0.74, where μ≡m/l is the dimensionless ratio between the azimuthal harmonic index m and the spheroidal harmonic index l of the perturbation mode. In particular, we use an analytical formula originally derived by Detweiler in order to prove the existence of DMs (damped quasinormal resonances which are characterized by finiteIω values in the a/M→1 limit) of near-extremal black holes in the μ>μ{sub c} regime, the regime which was claimed by Yang et al. not to contain DMs. We show that these co-rotating DMs (in the regime μ>μ{sub c}) are expected to characterize the resonance spectra of rapidly rotating (near-extremal) black holes with a/M≳1-10{sup -9}.

  15. Severe symptomatic acute hyponatremia in traumatic brain injury responded very rapidly to a single 15 mg dose of oral tolvaptan; a Mayo Clinic Health System hospital experience - need for caution with tolvaptan in younger patients with preserved renal function.

    Science.gov (United States)

    Onuigbo, Macaulay Amechi Chukwukadibia; Agbasi, Nneoma

    2017-01-01

    Tolvaptan is now well established as a potent pharmaceutical agent for symptomatic hyponatremia from syndrome of inappropriate antidiuretic hormone secretion (SIADH), congestive heart failure and liver cirrhosis. Previous studies had recruited older (63-65 years) patients with mild renal impairment (serum creatinine, 1.3-1.4 mg/dl). A 2012 report in the Journal of Neurology, Neurosurgery & Psychiatry described tolvaptan as a "lifesaving drug". A major outcome concern in the treatment of chronic hyponatremia is potentially fatal pontine demyelination from over-rapid correction of serum sodium >0.5 mEq/dL/h. The maximum reported correction of serum sodium within 24 hours was 13 mEq/L in a case of SIADH. We recently experienced the dramatic correction of hyponatremia at 1 mEq/dL/h over 18 hours, following 15 mg of oral tolvaptan in a 32-year old male patient with normal kidney function (serum creatinine 0.76 mg/dL), following traumatic brain injury (TBI). Tolvaptan is indeed an effective and life-saving drug for post-TBI hyponatremia. However, we strongly recommend the use of lower doses of tolvaptan (≤15 mg/d) in younger patients with more preserved renal function to avoid the development of life-threatening pontine demyelination.

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

    Science.gov (United States)

    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.

  17. Chromatic-dispersion measurement by modulation phase-shift method using a Kerr phase-interrogator.

    Science.gov (United States)

    Baker, Chams; Lu, Yang; Bao, Xiaoyi

    2014-09-22

    We present a novel approach for the measurement of chromatic-dispersion in long optical fibers using a modulation phase-shift method based on a Kerr phase-interrogator. This approach utilizes a Kerr phase-interrogator to measure the phase variation of a sinusoidal optical signal induced by traveling in a fiber under test as the laser carrier wavelength and the sinusoidal signal frequency are varied. Chromatic-dispersion measurement for several fibers including a standard single-mode silica fiber and a dispersion-shifted fiber is experimentally demonstrated. The ultrafast response of the Kerr phase-interrogator opens the way for real-time monitoring of chromatic-dispersion in kilometers-long optical fibers.

  18. Flat-space holography and stress tensor of Kerr black hole

    Energy Technology Data Exchange (ETDEWEB)

    Baghchesaraei, Omid, E-mail: omidbaghchesaraei@gmail.com [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Fareghbal, Reza, E-mail: r_fareghbal@sbu.ac.ir [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Izadi, Yousef, E-mail: yizadi2015@fau.edu [Department of Physics, Florida Atlantic University, Boca Raton, FL 33431 (United States)

    2016-09-10

    We propose a stress tensor for the Kerr black hole written in the Boyer–Lindquist coordinate. To achieve this, we use the dictionary of the Flat/CCFT correspondence and take the flat-space limit from the quasi-local stress tensor of the four-dimensional Kerr–AdS black hole. The proposed stress tensor yields the correct values for the mass and angular momentum of the Kerr black hole at spatial infinity. We also calculate some components of the energy momentum tensor of the three dimensional CCFT and show that they are consistent with the holographic calculation of the Kerr black hole. The calculation we present in this paper is another confirmation for the Flat/CCFT proposal.

  19. The effect of Kerr nonlinearity and Doppler broadening on slow light propagation

    Science.gov (United States)

    Ali, Hazrat; Ziauddin; Ahmad, Iftikhar

    2014-02-01

    The influence of Kerr nonlinearity and Doppler broadening on the slow light propagation of a dispersive atomic medium is revisited using a four-level Λ-type (87Rb) atomic system under the condition of electromagnetically induced transparency (EIT). The medium exhibits an EIT process which is accompanied by normal dispersion, i.e., sub-luminal (slow light) pulse propagation. In the presence of Kerr nonlinearity and the Doppler broadening effect the dispersion property of the proposed atomic medium is modified, which leads to enhancement of the positive group index of the medium. The combined effect of Kerr nonlinearity and Doppler broadening on slow light propagation inside the medium is the major motivation for this work.

  20. Imaging spin dynamics in monolayer WS2 by time-resolved Kerr rotation microscopy

    Science.gov (United States)

    McCormick, Elizabeth J.; Newburger, Michael J.; Luo, Yunqiu Kelly; McCreary, Kathleen M.; Singh, Simranjeet; Martin, Iwan B.; Cichewicz, Edward J., Jr.; Jonker, Berend T.; Kawakami, Roland K.

    2018-01-01

    Monolayer transition metal dichalcogenides (TMD) have immense potential for future spintronic and valleytronic applications due to their 2D nature and long spin/valley lifetimes. We investigate the origin of these long-lived states in n-type WS2 using time-resolved Kerr rotation microscopy and photoluminescence microscopy with ~1 µm spatial resolution. Comparing the spatial dependence of the Kerr rotation signal and the photoluminescence reveals a correlation with neutral exciton emission, which is likely due to the transfer of angular momentum to resident conduction electrons with long spin/valley lifetimes. In addition, we observe an unexpected anticorrelation between the Kerr rotation and trion emission, which provides evidence for the presence of long-lived spin/valley-polarized dark trions. We also find that the spin/valley polarization in WS2 is robust to magnetic fields up to 700 mT, indicative of spins and valleys that are stabilized with strong spin–orbit fields.

  1. Electric-Magneto-Optical Kerr Effect in a Hybrid Organic-Inorganic Perovskite.

    Science.gov (United States)

    Fan, Feng-Ren; Wu, Hua; Nabok, Dmitrii; Hu, Shunbo; Ren, Wei; Draxl, Claudia; Stroppa, Alessandro

    2017-09-20

    Hybrid organic-inorganic compounds attract a lot of interest for their flexible structures and multifunctional properties. For example, they can have coexisting magnetism and ferroelectricity whose possible coupling gives rise to magnetoelectricity. Here using first-principles computations, we show that, in a perovskite metal-organic framework (MOF), the magnetic and electric orders are further coupled to optical excitations, leading to an Electric tuning of the Magneto-Optical Kerr effect (EMOKE). Moreover, the Kerr angle can be switched by reversal of both ferroelectric and magnetic polarization only. The interplay between the Kerr angle and the organic-inorganic components of MOFs offers surprising unprecedented tools for engineering MOKE in complex compounds. Note that this work may be relevant to acentric magnetic systems in general, e.g., multiferroics.

  2. Advanced magneto-optical Kerr effect measurements of superconductors at low temperatures

    Directory of Open Access Journals (Sweden)

    Claudia Stahl

    2017-10-01

    Full Text Available Magneto-optical Kerr-effect (MOKE measurements of superconducting films with soft-magnetic coatings are performed at low temperatures using a laser-based MOKE set-up. An elaborate measurement scheme with internal reference allows the quantitative comparison of the temperature dependent Kerr-amplitude with the magnetic field generated by supercurrents. For this purpose, an amorphous CoFeB thin film exhibiting a large Kerr-signal is deposited directly on top of the YBCO superconductor acting as field sensing layer. It is shown that the resulting magnetic hysteresis loops of the soft-magnetic film can be used to reconstruct the electric properties of the superconductor.

  3. Gaussian Beam Propagation in a Kerr Type Metamaterial Medium Using ABCD Matrix Method

    Science.gov (United States)

    Keshavarz, A.; Naseri, M.

    2016-08-01

    In this paper, a split step ABCD matrix method is suggested to investigate Gaussian beam propagation in a Kerr type metamaterial medium. This method is based on dividing the medium interval into subsequent steps. Meanwhile, Gaussian beam profile in every step is obtained by finding the ABCD matrix of that particular step, and is used to find the ABCD matrix of the next step. Results of the suggested matrix method have been compared with the results of numerical split-step Fourier method for a Kerr medium, which indicates a good agreement. Then, we use the ABCD matrix to investigate Gaussian beams propagation in a Kerr type metamaterial, which is also in agreement with pervious results by other methods.

  4. Super-entropic black holes and the Kerr-CFT correspondence

    Energy Technology Data Exchange (ETDEWEB)

    Sinamuli, Musema [Department of Physics and Astronomy, University of Waterloo,200 University Ave., Waterloo, Ontario N2L 3G1 (Canada); Perimeter Institute for Theoretical Physics,31 Caroline St., Waterloo, Ontario, N2L 2Y5 (Canada); Mann, Robert B. [Department of Physics and Astronomy, University of Waterloo,200 University Ave., Waterloo, Ontario N2L 3G1 (Canada)

    2016-08-24

    We demonstrate that Kerr-CFT duality can be extended to super-entropic black holes, which have non-compact horizons with finite area. We demonstrate that this duality is robust insofar as the ultra-spinning limit of a Kerr-AdS black hole (which yields the super-entropic class) commutes with the near-horizon limit (which yields the Kerr-CFT duality). Consequently the Bekenstein-Hawking and the CFT entropies are equivalent. We show that the duality holds for both singly-spinning super-entropic black holes in 4 dimensions and for doubly-spinning super-entropic black holes of gauged supergravity in 5 dimensions. In both cases we obtain not only the expected left/right temperatures, but also temperatures associated with electric charge and with a new thermodynamic parameter specific to super-entropic black holes.

  5. Enhancement of Kerr nonlinearity at λ = 1550 nm in an Er3+-doped optical fiber

    Science.gov (United States)

    Ghaforyan, H.; Hamedi, H. R.; Khaledi-Nasab, A.; Jafarzadeh, H.; Asadpour, S. H.; Hoseini, Seyyed Mostafa; Sahrai, M.

    2013-05-01

    The Kerr nonlinearity behavior in an Er3+-doped ZrF4-BaF2-LaF3-AlF3-NaF optical fiber is investigated theoretically. It is found that by increasing the intensity of the coherent coupling field and in the presence of an incoherent pumping field, the enhanced Kerr nonlinearity with reduced absorption can be achieved at long wavelength, i.e. λ = 1550 nm, which is practical for communicational applications. In addition, it is found that the rate of incoherent pump field can significantly decrease the maximal Kerr nonlinearity of the medium. The impact of frequency detuning of the coherent field on linear and nonlinear susceptibilities is discussed.

  6. Pump polarization dependence of the optical Kerr gate with elliptically polarized probe light

    Science.gov (United States)

    Wang, Xiaofang; Yan, Lihe; Yue, Mengmeng; Dong, Qi

    2018-02-01

    Based on the light-induced polarization ellipse rotation effect, we propose an optical Kerr gate (OKG) in which elliptically polarized probe light is used by introducing a pair of crossed quarter-wave plates into the conventional OKG arrangement, placed just before and after the Kerr medium. Transient birefringence induced by the pump beam in the Kerr medium leads to a rotation of the polarization ellipse of the probe beam, hence part of the probe beam would pass through the OKG. Theoretical calculations and experimental results both indicate that the OKG signal intensity would reach the optimum value independent of the pump polarization direction when the probe beam is circularly polarized. This modified OKG measurement is suitable to detect the third-order nonlinearities induced in anisotropic materials.

  7. A re-examination of the life and work of A.F.G. Kerr and of his colleagues and friends

    DEFF Research Database (Denmark)

    Parnell, J. A. N.; Pilla, F.; Simpson, D. A.

    2015-01-01

    Arthur Francis George Kerr's life is reviewed and related to a previously published account. Kerr's collecting activity is analysed using an expanded version of the Thai Biogeography Group's database of collections. 8,666 of the total 48,970 collections are Kerr's and 3,178 are those of his...

  8. Impurity Induced Polar Kerr Effect in A Chiral p-wave Superconductor

    OpenAIRE

    Goryo, Jun

    2008-01-01

    We discuss the polar Kerr effect (PKE) in a chiral p-wave (p_x+i p_y-wave) superconductor. It is found that the off-diagonal component of a current-current correlation function is induced by impurity scattering in the chiral p-wave condensate, and a nonzero Hall conductivity is obtained using the Kubo formula. We estimate the Kerr rotation angle by using this impurity-induced Hall conductivity and compare it with experimental results [Jing Xia et al., Phys. Rev. Lett. 97, 167002 (2006)].

  9. Splitting and acquiring quantum information with perfect W states based on weak cross-Kerr nonlinearities

    Science.gov (United States)

    Xiu, Xiao-Ming; Cui, Cen; Lin, Yan-Fang; Dong, Li; Dong, Hai-Kuan; Gao, Ya-Jun

    2018-01-01

    With the assistance of weak cross-Kerr nonlinear interaction between photons and coherent states via Kerr media, we propose a scheme to split and acquire quantum information with three-photon perfect W states. By means of a fault-tolerant circuit, the perfect W states are distributed to the participants without being affected by the collective noise. And on this basis we present a scheme for splitting and acquiring a single-photon state with the shared perfect W states. Together with the mature techniques of classical feed-forward, simple and available linear optical elements are applied in the procedure, afford enhancing the feasibility of the theoretical scheme proposed here.

  10. Josephson Metamaterial with a Widely Tunable Positive or Negative Kerr Constant

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  12. Diode-pumped Kerr-lens mode-locked Yb: GSO laser generating 72 fs pulses

    Science.gov (United States)

    Tian, Wenlong; Wang, Zhaohua; Zhu, Jiangfeng; Zheng, Lihe; Xu, Xiaodong; Xu, Jun; Wei, Zhiyi

    2016-05-01

    The generation of 72 fs hyperbolic secant pulses centered at 1050 nm with 17.8 nm bandwidth from a diode pumped Kerr-lens mode-locked Yb: GSO laser is demonstrated. With the help of a semiconductor saturable absorber mirror, stable mode-locking with an average output power of 85 mW at a repetition rate of 113 MHz is realized. To the best of our knowledge, this is the first demonstration of Kerr-lens mode-locking in Yb: GSO laser.

  13. Interferometric method to determine the Kerr constant of perspex and ZnSe

    CSIR Research Space (South Africa)

    Govender, P

    2010-09-01

    Full Text Available comparison between results from earlier work [2]. 2. Experiment The Kerr constant is determined by the applied bias field, , as shown in the figure below, and the resulting birefringence, , using: 0E n∆ 2 0E n K λ... ∆ = , (1) where λ is the wavelength of the light source [1] . 3. Results With an applied voltage of 4.0kV across the perspex specimen, the Kerr constant for the sample was found to be . 2161066.7 −−× mV A comparison between the Michelson method...

  14. CFT description of three-dimensional Kerr-de Sitter spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Fjelstad, Jens E-mail: jens.fjelstad@kau.se; Hwang, Stephen E-mail: stephen.hwang@kau.se; Maansson, Teresia E-mail: teresia@physto.se

    2002-10-07

    We describe three-dimensional Kerr-de Sitter space using similar methods as recently applied to the BTZ black hole. A rigorous form of the classical connection between gravity in three dimensions and two-dimensional conformal field theory is employed, where the fundamental degrees of freedom are described in terms of two dependent SL(2,C) currents. In contrast to the BTZ case, however, quantization does not give the Bekenstein-Hawking entropy connected to the cosmological horizon of Kerr-de Sitter space.

  15. A Thought Experiment to Distinguish the Kerr Black Hole and Over-spinning Singularities

    CERN Document Server

    Chakraborty, Chandrachur; Joshi, Pankaj S

    2016-01-01

    We propose a thought experiment here to distinguish an over-spinning Kerr singularity from a Kerr black hole, using the gyroscopic precession due to the frame-dragging effect. We show that there is an important characteristic difference in behavior of the gyroscope precession frequency for these objects, which can be used to distinguish one from the other. Specifically, if we lower the gyroscope along the pole of the Kerr black hole, the precession frequency becomes arbitrarily high, blowing up as the event horizon is approached. However, in the case of an over-spinning Kerr singularity, this frequency always remains finite and is fully well-behaved. It turns out that this behavior is intimately related to and governed by the nature of ergoregions in each of these cases. Interestingly, it turns out that in the over-spinning singularity case, the precession frequency ($\\Omega_{LT}$) of the gyro decreases as ($\\Omega_{LT}\\propto r$) after reaching a maximum, in the limit of approach to the singularity. In princ...

  16. Shadows of CPR black holes and tests of the Kerr metric

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemi-Nodehi, M.; Li, Zilong; Bambi, Cosimo [Fudan University, Department of Physics, Center for Field Theory and Particle Physics, Shanghai (China)

    2015-07-15

    Ww study the shadow of the Cardoso-Pani-Rico black hole for different values of the black hole spin a{sub *}, the deformation parameters ε{sub 3}{sup t} and ε{sub 3}{sup r}, and the viewing angle i. We find that the main impact of the deformation parameter ε{sub 3}{sup t} is the change of the size of the shadow, while the deformation parameter ε{sub 3}{sup r} affects the shape of its boundary. In general, it is impossible to test the Kerr metric, because the shadow of a Kerr black hole can be reproduced quite well by a black hole with non-vanishing ε{sub 3}{sup t} or ε{sub 3}{sup r}. Deviations from the Kerr geometry could be constrained in the presence of high quality data and in the favorable case of a black hole with high values of a{sub *} and i. However, the shadows of some black holes with non-vanishing ε{sub 3}{sup r} present peculiar features and the possible detection of these shadows could unambiguously distinguish these objects from the standard Kerr black holes of general relativity. (orig.)

  17. A Simple, Approximate Method for Analysis of Kerr-Newman Black Hole Dynamics and Thermodynamics

    Directory of Open Access Journals (Sweden)

    Ciganović, S.

    2009-06-01

    Full Text Available In this work we present a simple approximate method for analysisof the basic dynamical and thermodynamical characteristics ofKerr-Newman black hole. Instead of the complete dynamics of theblack hole self-interaction, we consider only the stable(stationary dynamical situations determined by condition that theblack hole (outer horizon "circumference" holds the integernumber of the reduced Compton wave lengths corresponding to massspectrum of a small quantum system (representing the quantum of theblack hole self-interaction. Then, we show that Kerr-Newmanblack hole entropy represents simply the ratio of the sum ofstatic part and rotation part of the mass of black hole on onehand, and the ground mass of small quantum system on the other hand.Also we show that Kerr-Newman black hole temperature representsthe negative value of the classical potential energy ofgravitational interaction between a part of black hole withreduced mass and a small quantum system in the ground mass quantumstate. Finally, we suggest a bosonic great canonical distributionof the statistical ensemble of given small quantum systems in thethermodynamical equilibrium with (macroscopic black hole asthermal reservoir. We suggest that, practically, only the ground massquantum state is significantly degenerate while all the other, excitedmass quantum states, are non-degenerate. Kerr-Newman black holeentropy is practically equivalent to the ground mass quantum statedegeneration. Given statistical distribution admits a rough(qualitative but simple modeling of Hawking radiation of theblack hole too.

  18. On a zero-gravity limit of the Kerr-Newman spacetimes and their electromagnetic fields

    Science.gov (United States)

    Tahvildar-Zadeh, A. Shadi

    2015-04-01

    We discuss the limit of vanishing G (Newton's constant of universal gravitation) of the maximal analytically extended Kerr-Newman electrovacuum spacetimes represented in Boyer-Lindquist coordinates. We investigate the topologically nontrivial spacetime M 0 emerging in this limit and show that it consists of two copies of flat Minkowski spacetime cross-linked at a timelike solid cylinder (spacelike 2-disk × timelike ℝ). As G → 0, the electromagnetic fields of the Kerr-Newman spacetimes converge to nontrivial solutions of Maxwell's equations on this background spacetime M 0 . We show how to obtain these fields by solving Maxwell's equations with singular sources supported only on a circle in a spacelike slice of M 0 . These sources do not suffer from any of the pathologies that plague the alternate sources found in previous attempts to interpret the Kerr-Newman fields on the topologically simple Minkowski spacetime. We characterize the singular behavior of these sources and prove that the Kerr-Newman electrostatic potential and magnetic scalar potential are the unique solutions of the Maxwell equations among all functions that have the same blow-up behavior at the ring singularity.

  19. Effects of resonator input power on Kerr lens mode-locked lasers

    Indian Academy of Sciences (India)

    Department of Physics, Faculty of Sciences, Shiraz University of Technology, Shiraz, Iran ... In addition, the effect of the input power on the Kerr lens sensitivity ... So, to establish a KLM system, δ must be negative. Furthermore, it must be noted that the value of |δ| ≥ 0.5 is necessary for a. Pramana – J. Phys., Vol. 85, No.

  20. Control of Group Velocity via Spontaneous Generated Coherence and Kerr Nonlinearity

    Science.gov (United States)

    Hazrat, Ali; Iftikhar, Ahmad; Ziauddin

    2014-09-01

    A four-level N-type atomic medium is considered to study the effect of spontaneous generated coherence (SGC) and Kerr nonlinearity on light pulse propagation. A light pulse is propagating inside the medium where each atom follows four-level N-type atom-field configuration of rubidium (85Rb) atom. The atom-field interaction leads to electromagnetically induced transparency (EIT) process. The atom-field interaction is accompanied by normal dispersion and in the presence of SGC and Kerr nonlinearity the dispersion property of the proposed atomic medium is modified, which leads to enhancement of positive group index of the medium. The enhancement of positive group index then leads to slow group velocity inside the medium. A more slow group velocity is also investigated by incorporated the collective effect of SGC and Kerr nonlinearity. The control of group velocity inside a four-level N-type atomic medium via collective effect of SGC and Kerr nonlinearity is the major part of this work.

  1. Addendum: Hawking Radiation of Photons in a Variable-mass Kerr Black Hole

    OpenAIRE

    Wu, S. Q.; Cai, X.

    2001-01-01

    Hawking evaporation of photons in a variable-mass Kerr space-time is investigated by using a method of the generalized tortoise coordinate transformation. The blackbody radiant spectrum of photons displays a new spin-rotation coupling effect obviously dependent on different helicity states of photons.

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

    Science.gov (United States)

    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.

  3. Responding to Marginalization

    Directory of Open Access Journals (Sweden)

    Jie Y. Park

    2017-01-01

    Full Text Available This article offers an analysis of how refugee youths from Africa used and shifted languages and discourses in the United States. Drawing on sociocultural theories of language and utilizing ethnographic discourse and classroom observation data, the author illustrates the varied ways in which three high school–aged refugee youths used languages to make sense of who and where they are; respond to social, religious, and linguistic marginalization in the United States; and challenge narrow perceptions of African Muslims. This article brings to fore a group that, although facing a unique set of challenges in the United States, is rarely included in research on youth language practices and im/migration. Attention to their multilingual practices and the multilayered nature of their identity is central to understanding how refugee youths experience school in their new land, and how they see themselves and others. This understanding can guide school personnel, educational researchers, and community-based youth workers in their respective work with refugee students.

  4. Self-force correction to geodetic spin precession in Kerr spacetime

    Science.gov (United States)

    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.

  5. Kerr-effect analysis in a three-level negative index material under magneto cross-coupling

    Science.gov (United States)

    Boutabba, N.

    2018-02-01

    We discuss the feasibility of the Kerr effect in negative refractive index materials under magneto cross-coupling and reservoir interaction. The considered medium is a typical three-level atomic system where we derive both the refractive and the gain spectrum. The profiles are analyzed for a weak probe field, and for varying strengths of the strong control field. The considered scheme shows an enhancement of the Kerr nonlinearity which we attribute to the contribution of the electromagnetic components of the fields. For more realistic experimental conditions, we discuss the dependence of the Kerr effect on different thermal bath coupling constants.

  6. Hemicrania continua: who responds to indomethacin?

    Science.gov (United States)

    Marmura, M J; Silberstein, S D; Gupta, M

    2009-03-01

    Hemicrania continua (HC) is a primary headache disorder characterized by a continuous, moderate to severe, unilateral headache and defined by its absolute responsiveness to indomethacin. However, some patients with the clinical phenotype of HC do not respond to indomethacin. We reviewed the records of 192 patients with the putative diagnosis of HC and divided them into groups based on their headaches' response to indomethacin. They were compared for age, gender, presence or absence of specific autonomic symptoms, medication overuse, rapidity of headache onset, and whether or not the headaches met criteria for migraine when severe. Forty-three patients had an absolute response and 122 patients did not respond to adequate doses of indomethacin. The two groups did not differ significantly in terms of age, sex, presence of rapid-onset headache, or medication overuse. Autonomic symptoms, based on a questionnaire, did not predict response. Eighteen patients could not complete a trial of indomethacin due to adverse events. Nine patients could not be included in the HC group despite improvement with indomethacin: one patient probably had primary cough headache, another paroxysmal hemicrania; three patients improved but it was uncertain if they were absolutely pain free, and four patients dramatically improved but still had a baseline headache. We found no statistically significant differences between patients who did and did not respond to indomethacin. All patients with continuous, unilateral headache should receive an adequate trial of indomethacin. Most patients with unilateral headache suggestive of HC did not respond to indomethacin.

  7. Spinning test body orbiting around a Kerr black hole: Circular dynamics and gravitational-wave fluxes

    Science.gov (United States)

    Lukes-Gerakopoulos, Georgios; Harms, Enno; Bernuzzi, Sebastiano; Nagar, Alessandro

    2017-09-01

    In a recent work [Phys. Rev. D 94, 104010 (2016), 10.1103/PhysRevD.94.104010], hereafter Paper I, we numerically studied different prescriptions for the dynamics of a spinning body in circular motion around a Schwarzschild black hole. In the present work, we continue this line of investigation by studying the rotating Kerr black hole. We consider the Mathisson-Papapetrou formalism under three different spin-supplementary conditions (SSC), the Tulczyjew SSC, the Pirani SSC, and the Ohashi-Kyrian-Semerak SSC, and analyze the different circular dynamics in terms of the innermost stable circular orbit (ISCO) shifts and the frequency parameter x ≡(M Ω )2 /3 , where Ω is the orbital frequency and M is the Kerr black hole mass. Then, we solve numerically the inhomogeneous (2 +1 )D Teukolsky equation to contrast the asymptotic gravitational wave fluxes for the three cases. Our central observation made in Paper I for the Schwarzschild limit is found to hold true for the Kerr background; the three SSCs reduce to the same circular dynamics and the same radiation fluxes for small frequency parameters, but differences arise as x grows close to the ISCO. For a positive Kerr parameter a =0.9 , the energy fluxes mutually agree with each other within a 0.2% uncertainty up to x circular orbit parameters and the fluxes, especially for the a =-0.9 case. Instead, in the study of ISCO, the negative Kerr parameter a =-0.9 results in fewer discrepancies in comparison with the positive Kerr parameter a =0.9 . As a side result, we mention that, apart from the Tulczyew SSC, ISCOs could not be found over the full range of spins; for a =0.9 , for the Ohashi-Kyrian-Semerak SSC, ISCOs could be found only for σ <0.25 (σ denotes the test body's spin), while for the Pirani SSC, ISCOs could be found only for -0.68 <σ <0.64 . For a =-0.9 , for the Ohashi-Kyrian-Semerak SSC, ISCOs could be found for σ <0.721 .

  8. Switching feature of EIT-based slow light giant phase-sensitive Kerr nonlinearity in a semiconductor quantum well

    Science.gov (United States)

    Hamedi, H. R.; Mehmannavaz, Mohammad Reza

    2015-02-01

    A four level inverted Y-type quantum well semiconductor is proposed based on phase-sensitive Kerr nonlinearity with a closed-loop configuration. It is found that as the Rabi-frequency of coupling field increases, the maximal Kerr nonlinearity intensifies and at the same time the probe linear and nonlinear absorption decreases at Telecom wavelength λ = 1550 nm . The impact of an incoherent pumping field as well as the relative phase of the applied fields on nonlinear optical properties of the QW medium is then discussed. The temporal behavior of the Kerr nonlinearity and the required switching time for switching the nonlinear dispersion are also discussed. The results may be useful for understanding the switching feature of EIT-based slow light Kerr nonlinearity enhancement systems and have potential application in optical information processing and transmission.

  9. Kerr nonlinearity and optical multi-stability in a four-level Y-type atomic system

    Science.gov (United States)

    Sahrai, M.; Hamedi, H. R.; Memarzadeh, M.

    2012-06-01

    The nonlinear response to applied fields of a four-level Y-type atomic system is investigated. The effect of laser intensity and quantum interference induced by spontaneous emission on optical bistability, optical multi-stability and Kerr nonlinearity is then discussed. It is found that the threshold of the optical bistability can substantially be reduced by the quantum interference. So, an enhanced Kerr nonlinearity with reduced absorption can be achieved.

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

    Science.gov (United States)

    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.

  11. Critical phenomena in the extended phase space of Kerr-Newman-AdS black holes

    CERN Document Server

    Cheng, Peng; Liu, Yu-Xiao

    2016-01-01

    Treating the cosmological constant as a thermodynamic pressure, we investigate the critical behavior of a Kerr-Newman-AdS black hole system. The critical points for the van der Waals like phase transition are numerically solved. The highly accurate fitting formula for them is given and is found to be dependent of the charge $Q$ and angular momentum $J$. In the reduced parameter space, we find that the temperature, Gibbs free energy, and coexistence curve depend only on the dimensionless angular momentum-charge ratio $\\epsilon=J/Q^2$ rather than $Q$ and $J$. Moreover, when varying $\\epsilon$ from 0 to $\\infty$, the coexistence curve will continuously change from that of the Reissner-Nordstr\\"{o}m-AdS black hole to the Kerr-AdS black hole. These results may guide us to study the critical phenomena for other thermodynamic systems with two characteristic parameters.

  12. Bringing short-lived dissipative Kerr soliton states in microresonators into a steady state

    CERN Document Server

    Brasch, Victor; Pfeiffer, Martin H P; Kippenberg, Tobias J

    2016-01-01

    Dissipative Kerr solitons have recently been generated in optical microresonators, enabling ultrashort optical pulses at microwave repetition rates, that constitute coherent and numerically predictable Kerr frequency combs. However, the seeding and excitation of the temporal solitons is associated with changes in the intracavity power, that can lead to large thermal resonance shifts during the excitation process and render the soliton states in most commonly used resonator platforms short lived. Here we describe a "power kicking" method to overcome this instability by modulating the power of the pump laser. A fast modulation triggers the soliton formation, while a slow adjustment of the power compensates the thermal effect during the excitation laser scan. With this method also initially very short-lived (100ns) soliton states , as encountered in SiN integrated photonic microresonators, can be brought into a steady state in contrast to techniques reported earlier which relied on an adjustment of the laser sca...

  13. Dynamics of extended bodies with spin-induced quadrupole in Kerr spacetime: generic orbits

    CERN Document Server

    Han, Wen-Biao

    2016-01-01

    We discuss motions of extended bodies in Kerr spacetime by using Mathisson-Papapetrou-Dixon equations. We firstly solve the conditions for circular orbits, and calculate the orbital frequency shift due to the mass quadrupoles. The results show that we need not consider the spin-induced quadrupoles in extreme-mass-ratio inspirals for spatial gravitational wave detectors. We quantitatively investigate the temporal variation of rotational velocity of the extended body due to the coupling of quadrupole and background gravitational field. For generic orbits, we numerically integrate the Mathisson-Papapetrou-Dixon equations for evolving the motion of an extended body orbiting a Kerr black hole. By comparing with the monopole-dipole approximation, we reveal the influences of quadrupole moments of extended bodies on the orbital motion and chaotic dynamics of extreme-mass-ratio systems. We do not find any chaotic orbits for the extended bodies with physical spins and spin-induced quadrupoles. Possible implications for...

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

    Science.gov (United States)

    Wang, Mingzhi; Chen, Songbai; Jing, Jiliang

    2017-10-01

    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 ablack hole shadow possesses a cusp shape with small eye lashes in the cases with a>M, and the shadow becomes less 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.

  15. Kerr-Taub-NUT General Frame, Energy, and Momentum in Teleparallel Equivalent of General Relativity

    Directory of Open Access Journals (Sweden)

    Gamal G. L. Nashed

    2012-01-01

    Full Text Available A new exact solution describing a general stationary and axisymmetric object of the gravitational field in the framework of teleparallel equivalent of general relativity (TEGR is derived. The solution is characterized by three parameters “the gravitational mass M, the rotation a, and the NUT L.” The vierbein field is axially symmetric, and the associated metric gives the Kerr-Taub-NUT spacetime. Calculation of the total energy using two different methods, the gravitational energy momentum and the Riemannian connection 1-form Γα̃β, is carried out. It is shown that the two methods give the same results of energy and momentum. The value of energy is shown to depend on the mass M and the NUT parameter L. If L is vanishing, then the total energy reduced to the energy of Kerr black hole.

  16. Thermodynamics of a sufficient small singly spinning Kerr-AdS black hole

    Energy Technology Data Exchange (ETDEWEB)

    Pourhassan, Behnam, E-mail: b.pourhassan@du.ac.ir [School of Physics, Damghan University, Damghan (Iran, Islamic Republic of); Faizal, Mir, E-mail: mirfaizalmir@gmail.com [Irving K. Barber School of Arts and Sciences, University of British Columbia – Okanagan, Kelowna, BC V1V 1V7 (Canada); Department of Physics and Astronomy, University of Lethbridge, Lethbridge, AB T1K 3M4 (Canada)

    2016-12-15

    In this paper, we will analyze the thermodynamics of a small singly spinning Kerr-AdS black hole. As the black hole will be sufficient small, its temperature will be large and so we can not neglect the effects of thermal fluctuations. We will demonstrate that these thermal fluctuations correct the entropy of singly spinning Kerr-AdS black hole by a logarithmic correction term. We will analyze the implications of the logarithmic correction on other thermodynamic properties of this black hole, and analyze the stability of such a black hole. We will observe that this form of correction becomes important when the size of the black hole is sufficient small. We will also analyze the effect of these thermal fluctuations on the critical phenomena for such a black hole.

  17. Construction and physical properties of Kerr black holes with scalar hair

    CERN Document Server

    Herdeiro, Carlos

    2015-01-01

    Kerr black holes with scalar hair are solutions of the Einstein-Klein-Gordon field equations describing regular (on and outside an event horizon), asymptotically flat black holes with scalar hair (arXiv:1403.2757). These black holes interpolate continuously between the Kerr solution and rotating boson stars in D=4 spacetime dimensions. Here we provide details on their construction, discussing properties of the ansatz, the field equations, the boundary conditions and the numerical strategy. Then, we present an overview of the parameter space of the solutions, and describe in detail the space-time structure of the black holes exterior geometry and of the scalar field for a sample of reference solutions. Phenomenological properties of potential astrophysical interest are also discussed, and the stability properties and possible generalizations are commented on. As supplementary material to this paper we make available numerical data files for the sample of reference solutions discussed, for public use.

  18. Kerr effect at high electric field in the isotropic phase of mesogenic materials.

    Science.gov (United States)

    Li, Bing-Xiang; Borshch, Volodymyr; Shiyanovskii, Sergij V; Liu, Shao-Bin; Lavrentovich, Oleg D

    2015-11-01

    The well-known Kerr effect in isotropic fluids consists in the appearance of uniaxial orientational order and birefringence that grows as the square of the applied electric field. We predict and observe that at a high electric field, the Kerr effect displays features caused by the nonlinear dependence of dielectric permittivity on the field-induced orientational order parameter. Namely, the field-induced birefringence grows faster than the square of the electric field and the dynamics of birefringence growth slows down as the field increases. As a function of temperature, the field-induced birefringence is inversely proportional to the departure from an asymptotic critical temperature, but this temperature is no longer a constant (corresponding to the lower limit of the supercooled isotropic phase) and increases proportionally to the square of the electric field.

  19. Stable one-dimensional periodic waves in Kerr-type saturable and quadratic nonlinear media

    Energy Technology Data Exchange (ETDEWEB)

    Kartashov, Yaroslav V [ICFO-Institut de Ciencies Fotoniques, and Department of Signal Theory and Communications, Universitat Politecnica de Catalunya, E-08034 Barcelona (Spain); Egorov, Alexey A [Physics Department, M V Lomonosov Moscow State University, 119899, Moscow (Russian Federation); Vysloukh, Victor A [Departamento de Fisica y Matematicas, Universidad de las Americas-Puebla, Santa Catarina Martir, 72820, Puebla, Cholula (Mexico); Torner, Lluis [ICFO-Institut de Ciencies Fotoniques, and Department of Signal Theory and Communications, Universitat Politecnica de Catalunya, E-08034 Barcelona (Spain)

    2004-05-01

    We review the latest progress and properties of the families of bright and dark one-dimensional periodic waves propagating in saturable Kerr-type and quadratic nonlinear media. We show how saturation of the nonlinear response results in the appearance of stability (instability) bands in a focusing (defocusing) medium, which is in sharp contrast with the properties of periodic waves in Kerr media. One of the key results discovered is the stabilization of multicolour periodic waves in quadratic media. In particular, dark-type waves are shown to be metastable, while bright-type waves are completely stable in a broad range of energy flows and material parameters. This yields the first known example of completely stable periodic wave patterns propagating in conservative uniform media supporting bright solitons. Such results open the way to the experimental observation of the corresponding self-sustained periodic wave patterns.

  20. L -edge resonant magneto-optical Kerr effect of a buried Fe nanofilm

    Science.gov (United States)

    Kubota, Y.; Taguchi, M.; Akai, H.; Yamamoto, Sh.; Someya, T.; Hirata, Y.; Takubo, K.; Araki, M.; Fujisawa, M.; Yamamoto, K.; Yokoyama, Y.; Yamamoto, S.; Tsunoda, M.; Wadati, H.; Shin, S.; Matsuda, I.

    2017-10-01

    The Fe L -edge resonant magneto-optical Kerr effect of a buried Fe nanofilm was investigated by rotating-analyzer ellipsometry and the results were compared with those from three theoretical simulations. The reversal of the Kerr rotation angle θK between the L3 and L2 edges, observed in the experiment, was consistent with classical electromagnetic simulation using empirical optical constants. The spectral θK feature was reproduced by the first-principles calculation of the KKR-Green's function method on the itinerant electronic system. The demonstration indicates that spectra of the L -edge resonant MOKE can be understood in terms of both the macroscopic and microscopic pictures.

  1. A mirror based polar magneto-optical Kerr effect spectroscopy arrangement.

    Science.gov (United States)

    Arora, Ashish; Ghosh, Sandip; Sugunakar, Vasam

    2011-12-01

    An arrangement is described for performing magneto-optical Kerr effect (MOKE) spectroscopy in polar geometry with a conventional C-frame or H-frame type electromagnet. It uses an additional mirror which eliminates the need for an electromagnet pole piece with an axial hole and allows for easy switching between polar MOKE geometry and longitudinal or transverse MOKE geometries. A theoretical analysis of the photo-elastic modulation based detection scheme shows that the mirror causes a strong mixing of signals corresponding to Kerr rotation and ellipticity. The influence of the mirror is experimentally demonstrated and a procedure is given to correct for it. MOKE spectrum of nickel films obtained using this arrangement is shown to match with reports in the literature.

  2. Optimization of polarizer azimuth in improving domain image contrast in magneto-optical Kerr microscope

    Science.gov (United States)

    Wang, X.; Lian, J.; Li, P.; Li, X.; Li, M. M.; Wang, Y.; Liu, Y. X.

    2016-02-01

    The magneto-optical Kerr effect (MOKE) is a widely used technique in magnetic domain imaging for its high surface sensitivity and external magnetic compatibility. In this work, we use the generalized magneto-optical ellipsometry technique to study the influence of polarizer and analyzer azimuth on domain image contrast in the Kerr microscope. Results show that the image contrasts around the extinction place are larger than other area. When the polarizer and analyzer are set slightly deviated from the extinction condition (0.35°,89.7°), the maximum image contrast can be obtained. The color map of image contrast on polarizer and analyzer angle is given by measuring the MOKE response of 200 nm permalloy. Results verify the validity of the conclusion.

  3. A Note on Physical Mass and the Thermodynamics of AdS-Kerr Black Holes

    CERN Document Server

    McInnes, Brett

    2015-01-01

    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" mass $E=M/(1-a^2/L^2)^2$; 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: for example, in attempts to "over-spin" AdS-Kerr black holes.

  4. Kerr-lens mode-locked femtosecond Cr(2+):ZnSe laser at 2420 nm.

    Science.gov (United States)

    Cizmeciyan, M Natali; Cankaya, Huseyin; Kurt, Adnan; Sennaroglu, Alphan

    2009-10-15

    We describe a cw Kerr-lens mode-locked Cr(2+):ZnSe laser pumped by a 1800 nm thulium fiber laser. The astigmatically compensated asymmetric x cavity contained a 2.4-mm-long Cr(2+):ZnSe sample with a pump absorption coefficient of 11.6 cm(-1) and was operated with a 1% output coupler. The dispersion compensation was achieved by using a MgF(2) prism pair. During Kerr-lens mode-locked operation, we could generate 95 fs pulses at a pulse repetition rate of 94.3 MHz and with 40 mW of output power. The center wavelength of the pulses was 2420 nm. The pulses had a spectral width of 69 nm and a time-bandwidth product of 0.335, which is close to the transform limit for hyperbolic secant pulses.

  5. Comparative Study of FDTD-Adopted Numerical Algorithms for Kerr Nonlinearities

    DEFF Research Database (Denmark)

    Maksymov, Ivan S.; Sukhorukov, Andrey A.; Lavrinenko, Andrei

    2011-01-01

    Accurate finite-difference time-domain (FDTD) modeling of optical pulse propagation in nonlinear media usually implies the use of auxiliary differential equation (ADE) techniques. The updating of electric field in full-vectorial 3-D ADE FDTD modeling of the optical Kerr effect and two-photon abso...... approaches. Such schemes can significantly reduce the CPU time for nonlinear computations, especially in 3-D models.......Accurate finite-difference time-domain (FDTD) modeling of optical pulse propagation in nonlinear media usually implies the use of auxiliary differential equation (ADE) techniques. The updating of electric field in full-vectorial 3-D ADE FDTD modeling of the optical Kerr effect and two...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2016-07-01

    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.

  8. On the effect of random inhomogeneities in Kerr media modelled by a nonlinear Schroedinger equation

    Energy Technology Data Exchange (ETDEWEB)

    Villarroel, Javier [Facultad de Ciencias, Universidad de Salamanca, Plaza Merced s/n, E-37008 Salamanca (Spain); Montero, Miquel, E-mail: javier@usal.e, E-mail: miquel.montero@ub.ed [Departament de FIsica Fonamental, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona (Spain)

    2010-07-14

    We consider the propagation of optical beams under the interplay of dispersion and Kerr nonlinearity in optical fibres with impurities distributed at random uniformly on the fibre. By using a model based on the nonlinear Schroedinger equation we clarify how such inhomogeneities affect different aspects such as the number of solitons present and the intensity of the signal. We also obtain the mean distance for the signal to dissipate to a given level.

  9. Calculation and experimental verification of a collimator with a Kerr lens for fibre laser mode locking

    Science.gov (United States)

    Zakharov, Ia. V.; Kuznetsov, A. G.; Podivilov, E. V.; Babin, S. A.

    2017-11-01

    We present the calculation and experimental verification of the operation of a collimator coupling a light beam into an optical fibre with an As2S3 nonlinear plate. It is shown that a Kerr lens formed in the plate with an increase in the peak pulse power leads to an increase in the output coupling ratio by about 15%, which can be used for the passive mode locking of a fibre laser.

  10. A simple, approximate method for analysis of Kerr-Newman black hole dynamics and thermodynamics

    Directory of Open Access Journals (Sweden)

    Panković V.

    2009-01-01

    Full Text Available In this work we present a simple approximate method for analysis of the basic dynamical and thermodynamical characteristics of Kerr-Newman black hole. Instead of the complete dynamics of the black hole self-interaction, we consider only the stable (stationary dynamical situations determined by condition that the black hole (outer horizon 'circumference' holds the integer number of the reduced Compton wave lengths corresponding to mass spectrum of a small quantum system (representing the quantum of the black hole self-interaction. Then, we show that Kerr-Newman black hole entropy represents simply the ratio of the sum of static part and rotation part of the mass of black hole on one hand, and the ground mass of small quantum system on the other hand. Also we show that Kerr-Newman black hole temperature represents the negative value of the classical potential energy of gravitational interaction between a part of black hole with reduced mass and a small quantum system in the ground mass quantum state. Finally, we suggest a bosonic great canonical distribution of the statistical ensemble of given small quantum systems in the thermodynamical equilibrium with (macroscopic black hole as thermal reservoir. We suggest that, practically, only the ground mass quantum state is significantly degenerate while all the other, excited mass quantum states, are non-degenerate. Kerr-Newman black hole entropy is practically equivalent to the ground mass quantum state degeneration. Given statistical distribution admits a rough (qualitative but simple modeling of Hawking radiation of the black hole too.

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

    Science.gov (United States)

    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.

  12. A Review of Cavity Design for Kerr Lens Mode-Locked Solid-State Lasers

    Directory of Open Access Journals (Sweden)

    Shai Yefet

    2013-12-01

    Full Text Available We provide a critical review of the fundamental concepts of Kerr lens mode-locking (KLM, along with a detailed description of the experimental considerations involved in the realization of a mode-locked oscillator. In addition, we review recent developments that overcome inherent limitations and disadvantages in standard KLM lasers. Our review is aimed mainly at readers who wish to realize/maintain such an oscillator or for those who wish to better understand this major experimental tool.

  13. Femtosecond Raman-induced Kerr effect study of polar solvent dynamics: Amides

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yong Joon; Castner, E.W. Jr.

    1993-07-01

    We have measured the ultrafast pure solvent dynamics of highly power liquids, formamide (FA), N-methylformamide (NMF), N-methylacetamide (NMA), N-methylpropioamide (NMP) and N,N{prime}-dimethylformamide (DMF) using femtosecond optical-heterodyne-detected Raman-induced Kerr effect spectroscopy (OHD-RIKES). The effects of deuteration and temperature-dependence were studied to characterize in detail both the inertial (or non-diffusive) and diffusive intermolecular motions in these liquids.

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

    Science.gov (United States)

    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 \

  15. Cascaded Kerr photon-blockade soruces and applications in quantum key distribution.

    Science.gov (United States)

    Li, Ao; Zhou, Yiheng; Wang, Xiang-Bin

    2017-08-04

    To raise the repetition rate, a single-photon source based on Kerr quantum blockade in a cascaded quantum system is studied. Using the quantum trajectory method, we calculate and simulate the photon number distributions out of a two-cavity system. A high quality single-photon source can be achieved through optimizing parameters. The designed photon source is further applied to the decoy state quantum key distribution (QKD). With and without statistical fluctuation, the key rate can be both raised drastically.

  16. Temperature Dependence Characterization of Layered Materials via the Magneto-Optical Kerr Effect

    Science.gov (United States)

    Zhang, Haoxiang; Stevens, Christopher; Paul, Jagannath; Karaiskaj, Denis; Miller, Casey

    The Curie temperature of PyCu alloy films can be controlled by Cu content. The additional thickness in layered materials changes the Cure temperature and hence the magnetic coupling between permalloy and Cu layers. The decoupling is investigated by the Magneto-Optical Kerr Effect (MOKE) as a function of temperature around the Curie temperature. The measurements reveal the coupling dynamics between permalloy and Co in novel magnetic heterostructures. This research at USF is supported by the National Science Foundation.

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

    Science.gov (United States)

    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.

  18. Gyroscope precession along unbound equatorial plane orbits around a Kerr black hole

    CERN Document Server

    Bini, Donato; Jantzen, Robert T

    2016-01-01

    The precession of a test gyroscope along unbound equatorial plane geodesic orbits around a Kerr black hole is analyzed with respect to a static reference frame whose axes point towards the "fixed stars." The accumulated precession angle after a complete scattering process is evaluated and compared with the corresponding change in the orbital angle. Limiting results for the non-rotating Schwarzschild black hole case are also discussed.

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

    CERN Document Server

    Bini, Donato; Jantzen, Robert T

    2016-01-01

    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 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.

  20. Anomalous Lense-Thirring precession in Kerr-Taub-NUT spacetimes

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Chandrachur [Saha Institute of Nuclear Physics, Kolkata (India)

    2015-12-15

    Exact Lense-Thirring (LT) precession in Kerr-Taub-NUT spacetime is reviewed. It is shown that the LT precession does not obey the general inverse cube law of distance at strong gravity regime in Kerr-Taub-NUT spacetime. Rather, it becomes maximum just near the horizon, falls sharply and becomes zero near the horizon. The precession rate increases again and after that it falls obeying the general inverse cube law of distance. This anomaly is maximum at the polar region of this spacetime and it vanishes after crossing a certain 'critical' angle towards the equator from the pole. We highlight that this particular 'anomaly' also arises in the LT effect at the interior spacetime of the pulsars and such a signature could be used to identify a role of Taub-NUT solutions in the astrophysical observations or equivalently, a signature of the existence of a NUT charge in the pulsars. In addition, we show that if the Kerr-Taub-NUT spacetime rotates with the angular momentum J = Mn (mass x dual mass), the inner horizon goes to r = 0 and only the event horizon exists at the distance r = 2M. (orig.)

  1. Optimization of polarizer azimuth in improving domain image contrast in magneto-optical Kerr microscope

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X. [School of Physics and Technology, University of Ji Nan, Jinan 250022 (China); Lian, J., E-mail: sps_wangx@ujn.edu.cn [Department of Optical Engineering, Scholl of Science and Engineering, Shan Dong University, Jinan 250100 (China); Li, P.; Li, X [School of Physics and Technology, University of Ji Nan, Jinan 250022 (China); Li, M.M.; Wang, Y.; Liu, Y.X. [Department of Optical Engineering, Scholl of Science and Engineering, Shan Dong University, Jinan 250100 (China)

    2016-02-01

    The magneto-optical Kerr effect (MOKE) is a widely used technique in magnetic domain imaging for its high surface sensitivity and external magnetic compatibility. In this work, we use the generalized magneto-optical ellipsometry technique to study the influence of polarizer and analyzer azimuth on domain image contrast in the Kerr microscope. Results show that the image contrasts around the extinction place are larger than other area. When the polarizer and analyzer are set slightly deviated from the extinction condition (0.35°,89.7°), the maximum image contrast can be obtained. The color map of image contrast on polarizer and analyzer angle is given by measuring the MOKE response of 200 nm permalloy. Results verify the validity of the conclusion. - Highlights: • In this text, we expand the application of generalized magneto-optical ellipsometry (GME) to domain observing area. We study the domain image contrast with different polarizer and analyzer combination with GME. • 1. In this text, we provide a new method to improve the domain image contrast by optimizing the polarizer and analyzer azimuth combinations in magneto-optical Kerr microscopy.

  2. Uniqueness of Smooth Stationary Black Holes in Vacuum: Small Perturbations of the Kerr Spaces

    Science.gov (United States)

    Alexakis, S.; Ionescu, A. D.; Klainerman, S.

    2010-10-01

    The goal of the paper is to prove a perturbative result, concerning the uniqueness of Kerr solutions, a result which we believe will be useful in the proof of their nonlinear stability. Following the program started in Ionescu and Klainerman (Invent. Math. 175:35-102, 2009), we attempt to remove the analyticity assumption in the the well known Hawking-Carter-Robinson uniqueness result for regular stationary vacuum black holes. Unlike (Ionescu and Klainerman in Invent. Math. 175:35-102, 2009), which was based on a tensorial characterization of the Kerr solutions, due to Mars (Class. Quant. Grav. 16:2507-2523, 1999), we rely here on Hawking’s original strategy, which is to reduce the case of general stationary space-times to that of stationary and axi-symmetric spacetimes for which the Carter-Robinson uniqueness result holds. In this reduction Hawking had to appeal to analyticity. Using a variant of the geometric Carleman estimates developed in Ionescu and Klainerman (Invent. Math. 175:35-102, 2009), in this paper we show how to bypass analyticity in the case when the stationary vacuum space-time is a small perturbation of a given Kerr solution. Our perturbation assumption is expressed as a uniform smallness condition on the Mars-Simon tensor. The starting point of our proof is the new local rigidity theorem established in Alexakis et al. (Hawking’s local rigidity theorem without analyticity. http://arxiv.org/abs/0902.1173v1[gr-qc] , 2009).

  3. Photoconductivity, photoluminescence and optical Kerr nonlinear effects in zinc oxide films containing chromium nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Torres, C., E-mail: crstorres@yahoo.com.mx [Seccion de Estudios de Posgrado e Investigacion, ESIME-Z, Instituto Politecnico Nacional, Mexico, DF 07738 (Mexico); Garcia-Cruz, M.L. [Centro de Investigacion en Dispositivos Semiconductores, Benemerita Universidad Autonoma de Puebla, A. P. J-48, Puebla 72570, Mexico (Mexico); Castaneda, L., E-mail: luisca@sirio.ifuap.buap.mx [Instituto de Fisica, Benemerita Universidad Autonoma de Puebla, A. P. J-48, Puebla 72570, Mexico (Mexico); Rangel Rojo, R. [CICESE/Depto. de Optica, A. P. 360, Ensenada, BC 22860 (Mexico); Tamayo-Rivera, L. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Mexico, DF 01000 (Mexico); Maldonado, A. [Depto. de Ing. Electrica, CINVESTAV IPN-SEES, A. P. 14740, Mexico DF 07000 (Mexico); Avendano-Alejo, M., E-mail: imax_aa@yahoo.com.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, A. P. 70-186, 04510, DF (Mexico); and others

    2012-04-15

    Chromium doped zinc oxide thin solid films were deposited on soda-lime glass substrates. The photoconductivity of the material and its influence on the optical behavior was evaluated. A non-alkoxide sol-gel synthesis approach was used for the preparation of the samples. An enhancement of the photoluminescence response exhibited by the resulting photoconductive films with embedded chromium nanoclusters is presented. The modification in the photoconduction induced by a 445 nm wavelength was measured and then associated with the participation of the optical absorptive response. In order to investigate the third order optical nonlinearities of the samples, a standard time-resolved Optical Kerr Gate configuration with 80 fs pulses at 830 nm was used and a quasi-instantaneous pure electronic nonlinearity without the contribution of nonlinear optical absorption was observed. We estimate that from the inclusion of Cr nanoclusters into the sample results a strong optical Kerr effect originated by quantum confinement. The large photoluminescence response and the important refractive nonlinearity of the photoconductive samples seem to promise potential applications for the development of multifunctional all-optical nanodevices. - Highlights: Black-Right-Pointing-Pointer Enhancement in photoluminescence for chromium doped zinc oxide films is presented. Black-Right-Pointing-Pointer A strong and ultrafast optical Kerr effect seems to result from quantum confinement. Black-Right-Pointing-Pointer Photoconductive properties for optical and optoelectronic functions were observed.

  4. First Responders and Criticality Accidents

    Energy Technology Data Exchange (ETDEWEB)

    Valerie L. Putman; Douglas M. Minnema

    2005-11-01

    Nuclear criticality accident descriptions typically include, but do not focus on, information useful to first responders. We studied these accidents, noting characteristics to help (1) first responders prepare for such an event and (2) emergency drill planners develop appropriate simulations for training. We also provide recommendations to help people prepare for such events in the future.

  5. Responding to the Housing and Financial Crises

    DEFF Research Database (Denmark)

    Scanlon, Kathleen; Lunde, Jens; Whitehead, Christine

    2011-01-01

    The long period of house price growth in markets across the world ended with the US and global financial crisis of 2007/08. The crisis and the consequent recession had profound effects on mortgage market actors – including households, institutions and governments – in most advanced economies......, whether or not they participated in this rapid house price growth. Many of the trends observed during the boom, especially the innovations in financial instruments, were reversed. This paper presents evidence on how mortgage markets and stakeholders responded in the initial period after the crash....... In particular it reports on a 2009 survey of housing experts from 16 industrialised countries, which concentrated on how each country's mortgage system responded to the crisis and how governments addressed the problems of borrowers....

  6. Rapid Response in Psychological Treatments for Binge-Eating Disorder

    Science.gov (United States)

    Hilbert, Anja; Hildebrandt, Thomas; Agras, W. Stewart; Wilfley, Denise E.; Wilson, G. Terence

    2015-01-01

    Objective Analysis of short- and long-term effects of rapid response across three different treatments for binge-eating disorder (BED). Method In a randomized clinical study comparing interpersonal psychotherapy (IPT), cognitive-behavioral guided self-help (CBTgsh), and behavioral weight loss (BWL) treatment in 205 adults meeting DSM-IV criteria for BED, the predictive value of rapid response, defined as ≥ 70% reduction in binge-eating by week four, was determined for remission from binge-eating and global eating disorder psychopathology at posttreatment, 6-, 12-, 18-, and 24-month follow-up. Results Rapid responders in CBTgsh, but not in IPT or BWL, showed significantly greater rates of remission from binge-eating than non-rapid responders, which was sustained over the long term. Rapid and non-rapid responders in IPT and rapid responders in CBTgsh showed a greater remission from binge-eating than non-rapid responders in CBTgsh and BWL. Rapid responders in CBTgsh showed greater remission from binge-eating than rapid responders in BWL. Although rapid responders in all treatments had lower global eating disorder psychopathology than non-rapid responders in the short term, rapid responders in CBTgsh and IPT were more improved than those in BWL and non-rapid responders in each treatment. Rapid responders in BWL did not differ from non-rapid responders in CBTgsh and IPT. Conclusions Rapid response is a treatment-specific positive prognostic indicator of sustained remission from binge-eating in CBTgsh. Regarding an evidence-based stepped care model, IPT, equally efficacious for rapid and non-rapid responders, could be investigated as a second-line treatment in case of non-rapid response to first-line CBTgsh. PMID:25867446

  7. Responder Technology Alert (February 2015)

    Energy Technology Data Exchange (ETDEWEB)

    Upton, Jaki F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Stein, Steven L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-04-10

    As part of technology foraging for the Responder Technology Alliance, established by the Department of Homeland Science and Technologies First Responders Group, this report summarizes technologies that are relevant in the area of “wearables,” with the potential for use by first responders. The content was collected over the previous month(s) and reproduced from a general Internet search using the term wearables. Additional information is available at the websites provided. This report is not meant to be an exhaustive list nor an endorsement of any technology described herein. Rather, it is meant to provide useful information about current developments in the areas wearable technology.

  8. Bound states of the Dirac equation on Kerr spacetime

    CERN Document Server

    Dolan, Sam R

    2015-01-01

    We formulate the Dirac equation for a massive neutral spin-half particle on a rotating black hole spacetime, and we consider its (quasi)bound states: gravitationally-trapped modes which are regular across the future event horizon. These bound states decay with time, due to the absence of superradiance in the (single-particle) Dirac field. We introduce a practical method for computing the spectrum of energy levels and decay rates, and we compare our numerical results with known asymptotic results in the small-$M \\mu$ and large-$M \\mu$ regimes. By applying perturbation theory in a horizon-penetrating coordinate system, we compute the `fine structure' of the energy spectrum, and show good agreement with numerical results. We obtain data for a hyperfine splitting due to black hole rotation. We evolve generic initial data in the time domain, and show how Dirac bound states appear as spectral lines in the power spectra. In the rapidly-rotating regime, we find that the decay of low-frequency co-rotating modes is sup...

  9. Spatiotemporal complex geometrical optics for wavepacket evolution in inhomogeneous and nonlinear media of Kerr type

    Science.gov (United States)

    Berczynski, Pawel

    2013-12-01

    In this paper complex geometrical optics (CGO) is applied to spatiotemporal evolution of 2D Gaussian wavepackets in nonlinear media of Kerr type. Instead of solving the commonly accepted nonlinear Schrödinger equation (NLS), we propose equations of geometrical optics: a complex eikonal equation and a complex transport equation. The eikonal equation lets us derive immediately the ordinary differential equations for spatial and temporal widths, omitting in this way the complicated variational process used in nonlinear optics. Moreover, the obtained CGO equations for actual spatial and temporal widths happen to be identical to those obtained by the variational method approach. From the transport equation we obtain the first order ordinary differential equation for complex amplitude evolution and the conservation principle for energy flux in the packet cross-section. For the combined effect of diffraction, anomalous dispersion and nonlinear refraction, we observe three types of solution for temporal and spatial widths of the packet propagating in a nonlinear medium of Kerr type: the diffraction/dispersion widening, the stationary solution and the solution under the effect of the spatiotemporal collapse. Moreover, we discuss the evolution of the 2D Gaussian wavepacket in a nonlinear inhomogeneous waveguide and we present conditions for stable propagation without the collapse effect. Under these conditions the wavepacket asymptotically approaches stationary solutions when the parameters of the waveguide change over the propagation distance. The paper also discusses the influence of initial spatial and temporal chirps on Gaussian wavepacket evolution in nonlinear media of Kerr type and in nonlinear inhomogeneous waveguides. Moreover, we notice that the equations for temporal and spatial widths of the 2D wavepacket have the same structure as the equations for the evolution of the elliptical Gaussian beam. Thus, the description of the 2D spatiotemporal wavepacket can be

  10. Optimization of polarizer azimuth in improving signal-to-noise ratio in Kerr microscopy.

    Science.gov (United States)

    Wang, X; Lian, J; Xu, X J; Li, X; Li, P; Li, M M; Wang, Y; Liu, Y X

    2016-03-01

    The magneto optical Kerr effect (MOKE) is a widely used technique in magnetic domain imaging for its high surface sensitivity and external magnetic compatibility. Optimization of Kerr microscopy will improve the detecting sensitivity and provide high-quality domain images. In this work, we provide a method to optimize the polarizer azimuth in improving the signal-to-noise ratio (S/N) in longitudinal Kerr microscopy with the generalized magneto optical ellipsometry. Detailed analysis of the MOKE signal and the noise components are provided to study the optimum polarizer and analyzer azimuth combinations. Results show that, for a fixed polarizer angle 1°, the laser intensity noise and the shot noise, which vary with the input laser power, have a similar amplitude and decline with the analyzer azimuth increasing. When the analyzer is set at the extinction place, the Johnson noise plays a dominate role in the total noise. Then, the S/N values are calculated to find the optimum polarizer and analyzer azimuth. Results show that the optimum polarizer and analyzer azimuth combination for Permalloy is (18.35°, 68.35°) under an incident angle of 45°. After that, the S/N of 200 nm Permalloy at different analyzer angles with the polarizer azimuth set at 18.35° is measured to verify the validity of the simulation results. At last, the S/N at different incident angles is calculated. Results show that the optimum incident angle of 200 nm Permalloy film to improve the S/N is 70.35° under the polarizer and analyzer angles set at the optimal combinations (18.35°, 68.35°).

  11. Post-closure permit application for the Kerr Hollow Quarry at the Y-12 plant

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-06-01

    The Kerr Hollow Quarry (KHQ) is located on U.S. Department of Energy (DOE) property at the Y-12 Plant, Oak Ridge, Tennessee. The Oak Ridge Y-12 Plant was built by the U.S. Army Corps of Engineers in 1943 as part of the Manhattan Project. Until 1992, the primary mission of the Y-12 Plant was the production and fabrication of nuclear weapons components. Activities associated with these functions included production of lithium compounds, recovery of enriched uranium from scrap material, and fabrication of uranium and other materials into finished parts for assemblies. The Kerr Hollow Quarry was used for waste disposal of a variety of materials including water-reactive and shock-sensitive chemicals and compressed gas cylinders. These materials were packaged in various containers and sank under the water in the quarry due to their great weight. Disposal activities were terminated in November, 1988 due to a determination by the Tennessee Department of Environment and Conservation that the quarry was subject to regulations under the Resource Conservation and Recovery Act of 1993. Methods of closure for the quarry were reviewed, and actions were initiated to close the quarry in accordance with closure requirements for interim status surface impoundments specified in Tennessee Rules 1200-1-11-.05(7) and 1200-1-11-.05(11). As part of these actions, efforts were made to characterize the physical and chemical nature of wastes that had been disposed of in the quarry, and to remove any containers or debris that were put into the quarry during waste disposal activities. Closure certification reports (Fraser et al. 1993 and Dames and Moore 1993) document closure activities in detail. This report contains the post-closure permit application for the Kerr Hollow Quarry site.

  12. Understanding the contribution of mode area and slow light to the effective Kerr nonlinearity of waveguides.

    Science.gov (United States)

    Afshar V, Shahraam; Monro, T M; de Sterke, C Martijn

    2013-07-29

    We resolve the ambiguity in existing definitions of the effective area of a waveguide mode that have been reported in the literature by examining which definition leads to an accurate evaluation of the effective Kerr nonlinearity. We show that the effective nonlinear coefficient of a waveguide mode can be written as the product of a suitable average of the nonlinear coefficients of the waveguide's constituent materials, the mode's group velocity and a new suitably defined effective mode area. None of these parameters on their own completely describe the strength of the nonlinear effects of a waveguide.

  13. Entanglement of a nonlinear two two-level atoms interacting with deformed fields in Kerr medium

    Science.gov (United States)

    Abdel-Khalek, S.; El-Saman, Y. S.; Abdel-Aty, M.

    2018-01-01

    In this paper we investigate the entanglement dynamics between two two-level atoms interacting with two coherent fields in two spatially separated cavities which are filled with a Kerr-like medium. We examine the effect of nonlinear medium on the dynamical properties of entanglement and atomic occupation probabilities in the case of even and odd deformed coherent states. The results show that the deformed fields play important roles in the evolution of entanglement. Also, the results demonstrate that entanglement sudden death, sudden birth and long-distance can be controlled by the deformation and nonlinear parameters.

  14. Kerr-Anti-De-Sitter/De-Sitter Black Hole In Dark Matter Background

    OpenAIRE

    Xu, Zhaoyi; Wang, Jiancheng; Hou, Xian

    2017-01-01

    In this work, we obtain the Kerr-anti-de-sitter/de-sitter black hole solutions of the Einstein field equation in the quintessence-like dark matter or phantom-like dark matter using Newman-Janis method and Mathematica package. From the horizon equation $g_{rr}=0$, we get the expression between the dark matter parameter $\\alpha$ and the cosmological constant when one cosmological horizon $r_{\\Lambda}$ exists. For $\\Lambda=0$, we find that $\\alpha$ is in the range of $0

  15. Terahertz Kerr nonlinearity analysis of a microribbon graphene array using the harmonic balance method

    Science.gov (United States)

    Taghvaee, H. R.; Zarrinkhat, F.; Abrishamian, M. S.

    2017-06-01

    Transmission spectra of microribbon graphene arrays are investigated with a circuit model based on the transmission line method. The accuracy of the proposed method is comparable with full-wave electromagnetic simulation results versus chemical potential, incident angle, dimensions of microribbons and the permittivity of the substrate. This rigorous method takes less than a second to perform, therefore it can be employed to optimize other similar devices instead of numerical methods that involve heavy calculations. Furthermore, we depicted the Kerr effect with the harmonic balance method through calculating the parameters in steady state. The results of this novel approach exhibited an excellent agreement with full-wave simulation results.

  16. Flag-dipole and flagpole spinor fluid flows in Kerr spacetimes

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, Roldão da, E-mail: roldao.rocha@ufabc.edu.br [Universidade Federal do ABC, CMCC (Brazil); Cavalcanti, R. T., E-mail: rogerio.cavalcanti@ufabc.edu.br [Universidade Federal do ABC, CCNH (Brazil)

    2017-03-15

    Flagpole and flag-dipole spinors are particular classes of spinor fields that has been recently used in different branches of theoretical physics. In this paper, we study the possibility and consequences of these spinor fields to induce an underlying fluid flow structure in the background of Kerr spacetimes. We show that flag-dipole spinor fields are solutions of the equations of motion in this context. To our knowledge, this is the second time that this class of spinor field appears as a physical solution, the first one occurring as a solution of the Dirac equation in ESK gravities.

  17. Tunable nonreciprocal transmission system based on MIM waveguide with Kerr nonlinear material

    Science.gov (United States)

    Xiao, Wenfeng; Luo, Xin; Zhai, Xiang; Wang, Lingling

    2017-11-01

    A novel nonreciprocal MIM waveguide with Kerr nonlinear material in near-infrared region is proposed and the corresponding transmission characteristics are investigated. In the proposed MIM waveguide, a transmission contrast ratio up to 49.2 dB can be achieved between forward and backward transmission by using the finite-difference time-domain (FDTD) method, revealing an excellent nonreciprocal effect. Moreover, the proposed nonreciprocal MIM waveguide can also be flexibly controlled as forward transmission or backward transmission at different wavelengths. Therefore, our results can offer a new possibility and important application in highly integrated optical circuits.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  20. Geometric Thermodynamics of Kerr-AdS black hole with a Cosmological Constant as State Variable

    CERN Document Server

    Larranaga, Alexis

    2012-01-01

    The thermodynamics of the Kerr-AdS black hole is reformulated within the context of the formalism of geometrothermodynamics (GTD) and the cosmological constant is considered as a new thermodynamical parameter. We conclude that the mass of the black hole corresponds to the total enthalpy of this system. Choosing appropriately the metric in the equilibrium states manifold, we study the phase transitions as a divergence of the thermodynamical curvature scalar. This approach reproduces the Hawking-Page transition and shows that considering the cosmological constant as a thermodynamical parameter does not contribute with new phase transitions.

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

    Science.gov (United States)

    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.

  2. Dynamics of spin valves investigated using Magneto-Optical Kerr Effect Spectroscopy

    Science.gov (United States)

    Stevens, Christopher; Paul, Jagannath; Dey, Prasenjit; Miller, Casey; McGill, Stephen; Karaiskaj, Denis

    Through an all-optical approach, we are investigating the spin dynamics in different spin torque based structures. Using pump-probe Time-Resolved Magneto-Optical Kerr Effect (TR-MOKE) spectroscopy, we are able to monitor the ultrafast magnon propagation on a sub-picosecond timescale as well as the longer lived oscillations and demagnetization. This represents a recent efforts to realize magnon induced spin torque using an all optical method. This research at USF is supported by the National Science Foundation, Division of Electrical, Communications and Cyber Systems under Grant Number: 1231929. The work was done in part at the NHMFL, Tallahassee, FSU under Grants: DMR-1229217, DMR-1157490.

  3. Magneto-optical Kerr Effect Spectroscopy Study of Ferromagnetic Metal/Organic Heterostructures

    OpenAIRE

    Li, Wen

    2011-01-01

    Diese Dissertation stellt die erste Anwendung des magneto-optischen Kerr Effektes (MOKE) auf ferromagnetische Metall/Organische Heterostrukturen zur Aufklärung der optischen und chemischen Eigenschaften dar. Die MOKE-Untersuchungen wurden spektroskopisch in einem Energiebereich von 1.7 eV bis 5.5 eV durchgeführt. Heterostrukturen, wie sie hier untersucht werden, sind relevant für Anwendungen in der organischen Spintronik. Die Auswertung der Experimentellen Daten wird unterstützt durch numeris...

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

    Science.gov (United States)

    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.

  5. Exact solutions to sourceless charged massive scalar field equation on Kerr-Newman background

    Science.gov (United States)

    Wu, S. Q.; Cai, X.

    1999-09-01

    The covariant Klein-Gordon equation in the Kerr-Newman black hole geometry is separated into a radial part and an angular part. It is discovered that in the nonextreme case, these two equations belong to a generalized spin-weighted spheroidal wave equation. Then general exact solutions in integral forms and several special solutions with physical interest are given. While in the extreme case, the radial equation can be transformed into a generalized Whittaker-Hill equation. In both cases, five-term recurrence relations between coefficients in power series expansion of general solutions are presented. Finally, the connection between the radial equations in both cases is discussed.

  6. Hawking radiation screening and Penrose process shielding in the Kerr black hole

    Energy Technology Data Exchange (ETDEWEB)

    Mc Caughey, Eamon [Dublin Institute of Technology, School of Mathematical Sciences, Dublin 8 (Ireland)

    2016-04-15

    The radial motion of massive particles in the equatorial plane of a Kerr black hole is considered. Screening of the Hawking radiation and shielding of the Penrose process are examined (both inside and outside the ergosphere) and their effect on the evaporation of the black hole is studied. In particular, the locus and width of a classically forbidden region and their dependence on the particle's angular momentum and energy is analysed. Tunneling of particles between the boundaries of this region is considered and the transmission coefficient determined. (orig.)

  7. Hidden Symmetries of Euclideanised Kerr-NUT-(AdS Metrics in Certain Scaling Limits

    Directory of Open Access Journals (Sweden)

    Mihai Visinescu

    2012-08-01

    Full Text Available The hidden symmetries of higher dimensional Kerr-NUT-(AdS 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.

  8. Filamentation patterns in Kerr media vs. beam shape robustness, nonlinear saturation and polarization states

    DEFF Research Database (Denmark)

    Bergé, L.; Gouédard, C.; Schjødt-Eriksen, Jens

    2003-01-01

    The filamentation of optical beams in focusing Kerr media is investigated. First, the creation of filamentary structures is shown to strongly depend on the radial distribution of the incident beam in the diffraction plane. With a cubic nonlinearity, broadening an input beam from Gaussian to super...... on the filamentation instability is investigated. Rigorous conditions for the SF of beams with different polarizations are derived, which prove that the power threshold for collapse noticeably increases for circularly-polarized beams. The growth rate for modulational instability decreases accordingly and the minimal...

  9. Gyroscope precession along general timelike geodesics in a Kerr black hole spacetime

    Science.gov (United States)

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

    2017-06-01

    The precession angular velocity of a gyroscope moving along a general geodesic in the Kerr spacetime is analyzed using the geometric properties of the spacetime. Natural frames along the gyroscope world line are explicitly constructed by boosting frames adapted to fundamental observers. A novel geometrical description is given to Marck's construction of a parallel propagated orthonormal frame along a general geodesic, identifying and clarifying the special role played by the Carter family of observers in this general context, thus extending previous discussion for the equatorial plane case.

  10. High-power 200 fs Kerr-lens mode-locked Yb:YAG thin-disk oscillator.

    Science.gov (United States)

    Pronin, O; Brons, J; Grasse, C; Pervak, V; Boehm, G; Amann, M-C; Kalashnikov, V L; Apolonski, A; Krausz, F

    2011-12-15

    We demonstrate a power-scalable Kerr-lens mode-locked Yb:YAG thin-disk oscillator. It delivers 200 fs pulses at an average power of 17 W and a repetition rate of 40 MHz. At an increased (180 W) pump power level, the laser produces 270 fs 1.1 μJ pulses at an average power of 45 W (optical-to-optical efficiency of 25%). Semiconductor-saturable-absorber-mirror-assisted Kerr-lens mode locking (KLM) and pure KLM with a hard aperture show similar performance. To our knowledge, these are the shortest pulses achieved from a mode-locked Yb:YAG disk oscillator and this is the first demonstration of a Kerr-lens mode-locked thin-disk laser.

  11. Gain assisted multiple surperluminal regions via a Kerr nonlinearity in a double lambda-type atomic configuration

    Science.gov (United States)

    Amin Bacha, Bakht; Ghafoor, Fazal; Ahmad, Iftikhar; Rahman, A.

    2014-04-01

    A four level double lambda-type atomic configuration is extended to polychromatic pump fields driven from the ground to the same excited hyperfine sublevel. Multiple superluminal regions are observed in the gain peak regions and between the two pairs of gain peak regions. Furthermore, the effect of cross Kerr nonlinearity is introduced in the system by applying an additional driving field. Large enhancement in the superluminality is observed as compared to the previously observed superluminality without the Kerr nonlinearity. The results clearly show a small negative group velocity of - 0.72 m s-1 with a negative time delay of -42.2 ms in the presence of the Kerr field. In this connection, useful theoretical techniques are presented for the enhancement of slow and fast light propagation. This generalized model is adjustable with the current applied technologies of cloaking devices and spacial mode images.

  12. Phase control of Kerr nonlinearity due to quantum interference in a four-level N-type atomic system

    Energy Technology Data Exchange (ETDEWEB)

    Asadpour, Seyyed Hossein, E-mail: S.hosein.asadpour@gmail.com [Young Researchers Club, Bandar Anzali Branch, Islamic Azad University, Bandar Anzali (Iran, Islamic Republic of); Reza Hamedi, Hamid; Sahrai, Mostafa [Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2012-08-15

    Linear and nonlinear response of a four-level N-type atomic system for a weak probe field is investigated. It is demonstrated that the giant Kerr nonlinearity with reduced absorption can be achieved by the spontaneously generated coherence. In addition, the effect of a relative phase between coupling fields on linear and nonlinear absorption as well as Kerr nonlinearity is then discussed. - Highlights: Black-Right-Pointing-Pointer The quantum interference due to spontaneous emission is considered in a four level medium. Black-Right-Pointing-Pointer The giant Kerr nonlinearity in the reduced linear absorption is obtained. Black-Right-Pointing-Pointer The phase control of driving fields on linear and nonlinear susceptibility is investigated.

  13. Numerical evidence for universality in the relaxation dynamics of near-extremal Kerr-Newman black holes

    Energy Technology Data Exchange (ETDEWEB)

    Hod, Shahar [The Ruppin Academic Center, Emeq Hefer (Israel); The Hadassah Institute, Jerusalem (Israel)

    2015-12-15

    The coupled gravitational-electromagnetic quasinormal resonances of charged rotating Kerr-Newman black holes are explored. In particular, using the recently published numerical data of Dias et al. (Phys Rev Lett 114:151101, 2015), we show that the characteristic relaxation times τ ≡ 1/Iω{sub 0} of near-extremal Kerr-Newman black holes in the regime Q/r{sub +} ≤ 0.9 are described, to a very good degree of accuracy, by the simple universal relation τ x T{sub BH} = π{sup -1} (here Q/r{sub +}, and T{sub BH} are respectively the electric charge, horizon radius, and temperature of the Kerr-Newman black hole, and ω{sub 0} is the fundamental quasinormal resonance of the perturbed black-hole spacetime). (orig.)

  14. Beam steering using optical parametric amplification in Kerr medium: a space-time analogy of parametric slow-light.

    Science.gov (United States)

    Fanjoux, Gil; Lantz, Eric; Michaud, Jérémy; Sylvestre, Thibaut

    2012-11-19

    In a way analogous to a light pulse that can be optically delayed via slow light propagation in Kerr-type nonlinear media, we theoretically demonstrate that beam steering and spatial walk-off compensation can be achieved in noncollinear optical parametric amplification. We identify this effect as a result of the quadratic phase shift induced by parametric amplification that leads to the cancellation of the spatial walk-off and collinear propagation of all beams though they have different wavevectors. Experimental evidence is reported of a soliton array steering in a Kerr slab waveguide.

  15. Photon Number-Phase Uncertainty Relation in the Evolution of the Field in a Kerr-Like Medium

    Science.gov (United States)

    Fan, An-Fu; Sun, Nian-Chun

    1996-01-01

    A model of a single-mode field, initially prepared in a coherent state, coupled to a two-level atom surrounded by a nonlinear Kerr-like medium contained inside a very good quality cavity is considered. We derive the photon number-phase uncertainty relation in the evolution of the field for a weak and strong nonlinear coupling respectively, within the Hermitian phase operator formalism of Pegg and Barnett, and discuss the effects of nonlinear coupling of the Kerr-like medium on photon number-phase uncertainty relation of the field.

  16. Generation of a coherent near-infrared Kerr frequency comb in a monolithic microresonator with normal GVD

    CERN Document Server

    Liang, Wei; Ilchenko, Vladimir S; Eliyahu, Danny; Seidel, David; Matsko, Andrey B; Maleki, Lute

    2014-01-01

    We demonstrate experimentally, and explain theoretically, generation of a wide, fundamentally phase locked Kerr frequency comb in a nonlinear resonator with a normal group velocity dispersion. A magnesium fluoride whispering gallery resonator characterized with 10 GHz free spectral range and pumped either at 780 nm or 795 nm is used in the experiment. The envelope of the observed frequency comb differs significantly from the Kerr frequency comb spectra reported previously. We show via numerical simulation that, while the frequency comb does not correspond to generation of short optical pulses, the relative phases of the generated harmonics are fixed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Schemm, E.R., E-mail: eschemm@alumni.stanford.edu [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305 (United States); Levenson-Falk, E.M. [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305 (United States); Department of Physics, Stanford University, Stanford, CA 94305 (United States); Kapitulnik, A. [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305 (United States); Department of Physics, Stanford University, Stanford, CA 94305 (United States); Department of Applied Physics, Stanford University, Stanford, CA 94305 (United States); Stanford Institute of Energy and Materials Science, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

    2017-04-15

    Highlights: • Polar Kerr effect (PKE) probes broken time-reversal symmetry (TRS) in superconductors. • Absence of PKE below Tc in CeCoIn{sub 5} is consistent with dx2-y2 order parameter symmetry. • PKE in the B phase of the multiphase superconductor UPt3 agrees with an E2u model. • Data on URu2Si2 show broken TRS and additional structure in the superconducting state. - Abstract: 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. With the notable exception of {sup 3}He-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. Here 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.

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

    CERN Document Server

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

    2016-01-01

    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 $z\\sim 3$. 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 nat...

  19. Enhanced magneto-optical Kerr effect at Fe/insulator interfaces

    Science.gov (United States)

    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.

  20. Hamiltonian formulation of the conservative self-force dynamics in the Kerr geometry

    Science.gov (United States)

    Fujita, Ryuichi; Isoyama, Soichiro; Le Tiec, Alexandre; Nakano, Hiroyuki; Sago, Norichika; Tanaka, Takahiro

    2017-07-01

    We formulate a Hamiltonian description of the orbital motion of a point particle in Kerr spacetime for generic (eccentric, inclined) orbits, which accounts for the effects of the conservative part of the gravitational self-force. This formulation relies on a description of the particle’s motion as geodesic in a certain smooth effective spacetime, in terms of (generalized) action-angle variables. Clarifying the role played by the gauge freedom in the Hamiltonian dynamics, we extract the gauge-invariant information contained in the conservative self-force. We also propose a possible gauge choice for which the orbital dynamics can be described by an effective Hamiltonian, written solely in terms of the action variables. As an application of our Hamiltonian formulation in this gauge, we derive the conservative self-force correction to the orbital frequencies of Kerr innermost stable spherical (inclined or circular) orbits. This gauge choice also allows us to establish a ‘first law of mechanics’ for black-hole-particle binary systems, at leading order beyond the test-mass approximation.

  1. Time-Resolved Magneto-Optical Kerr Effect of Magnetic Thin Films for Ultrafast Thermal Characterization.

    Science.gov (United States)

    Chen, Jun-Yang; Zhu, Jie; Zhang, Delin; Lattery, Dustin M; Li, Mo; Wang, Jian-Ping; Wang, Xiaojia

    2016-07-07

    Thermomagnetic and magneto-optical effects are two fundamental but unique phenomena existing in magnetic materials. In this work, we demonstrate ultrafast time-resolved magneto-optical Kerr effect (TR-MOKE) as an advanced thermal characterization technique by studying the original factors of the MOKE signal from four magnetic transducers, including TbFe, GdFeCo, Co/Pd, and CoFe/Pt. A figure of merit is proposed to evaluate the performance of the transducer layers, corresponding to the degree of the signal-to-noise ratio in TR-MOKE measurements. We observe improved figure of merit for rare-earth transition-metal-based TbFe and GdFeCo transducers and attribute this improvement to their relatively larger temperature-dependent magnetization and the Kerr rotation angle at the saturated magnetization state. Furthermore, an optimal thickness of TbFe is found to be ∼18.5 nm to give the best performance. Our findings will facilitate the nanoscale thermal characterization and the device design where the thermo-magneto-optical coupling plays an important role.

  2. Circuit QED: cross-Kerr effect induced by a superconducting qutrit without classical pulses

    Science.gov (United States)

    Liu, Tong; Zhang, Yang; Guo, Bao-Qing; Yu, Chang-Shui; Zhang, Wei-Ning

    2017-09-01

    The realization of cross-Kerr nonlinearity is an important task for many applications in quantum information processing. In this work, we propose a method for realizing cross-Kerr nonlinearity interaction between two superconducting coplanar waveguide resonators coupled by a three-level superconducting flux qutrit (coupler). Because the resonator photons are virtually excited and the coupler is unexcited for the entire process, the effect of resonator decay and the coupler decoherence are greatly minimized. More importantly, compared with the previous proposals, our proposal does not require classical pulses. Furthermore, due to use of only a three-level qutrit, the experimental setup is much simplified when compared with previous proposals requiring a four-level artificial atomic systems. In addition, we implement a two-resonator qubits controlled-phase gate and generate a two-resonator entangled coherent state. Numerical simulation shows that the high-fidelity implementation of the phase gate and creation of the entangled coherent state are feasible with current circuit QED technology.

  3. Revised upper limit to energy extraction from a Kerr black hole.

    Science.gov (United States)

    Schnittman, Jeremy D

    2014-12-31

    We present a new upper limit on the energy that may be extracted from a Kerr black hole by means of particle collisions in the ergosphere (i.e., the "collisional Penrose process"). Earlier work on this subject has focused largely on particles with critical values of angular momentum falling into an extremal Kerr black hole from infinity and colliding just outside the horizon. While these collisions are able to reach arbitrarily high center-of-mass energies, it is very difficult for the reaction products to escape back to infinity, effectively limiting the peak efficiency of such a process to roughly 130%. When we allow one of the initial particles to have impact parameter b>2M, and thus not get captured by the horizon, it is able to collide along outgoing trajectories, greatly increasing the chance that the products can escape. For equal-mass particles annihilating to photons, we find a greatly increased peak energy of Eout≈6×Ein. For Compton scattering, the efficiency can go even higher, with Eout≈14×Ein, and for repeated scattering events, photons can both be produced and escape to infinity with Planck-scale energies.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Wei-Ping, E-mail: zhongwp6@126.com [Department of Electronic and Information Engineering, Shunde Polytechnic, Guangdong Province, Shunde 528300 (China); Texas A and M University at Qatar, P.O. Box 23874 Doha (Qatar); Belić, Milivoj [Texas A and M University at Qatar, P.O. Box 23874 Doha (Qatar); Institute of Physics, University of Belgrade, P.O. Box 57, 11001 Belgrade (Serbia)

    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, 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.

  5. Decontamination and decommissioning of the Kerr-McGee Cimarron Plutonium Fuel Plant

    Energy Technology Data Exchange (ETDEWEB)

    1994-05-01

    This final report is a summary of the events that completes the decontamination and decommissioning of the Cimarron Corporation`s Mixed Oxides Fuel Plant (formally Sequoyah Fuels Corporation and formerly Kerr-McGee Nuclear Corporation - all three wholly owned subsidiaries of the Kerr-McGee Corporation). Included are details dealing with tooling and procedures for performing the unique tasks of disassembly decontamination and/or disposal. That material which could not be economically decontaminated was volume reduced by disassembly and/or compacted for disposal. The contaminated waste cleaning solutions were processed through filtration and ion exchange for release or solidified with cement for L.S.A. waste disposal. The L.S.A. waste was compacted, and stabilized as required in drums for burial in an approved burial facility. T.R.U. waste packaging and shipping was completed by the end of July 1987. This material was shipped to the Hanford, Washington site for disposal. The personnel protection and monitoring measures and procedures are discussed along with the results of exposure data of operating personnel. The shipping containers for both T.R.U. and L.S.A. waste are described. The results of the decommissioning operations are reported in six reports. The personnel protection and monitoring measures and procedures are contained and discussed along with the results of exposure data of operating personnel in this final report.

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

    Science.gov (United States)

    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.

  7. Responding to the Invisible Student.

    Science.gov (United States)

    Callahan, Susan

    2000-01-01

    Investigates what constitutes good reflection. Describes how one instructor used the Myers-Briggs type indicator (MBTI) to explore her responses to the reflective writing produced by preservice English teachers. Concludes that the MBTI can provide insight into and improve how instructors assign, respond to, and evaluate student reflection.…

  8. CORRUPTION: HOW SHOULD CHRISTIANS RESPOND?

    African Journals Online (AJOL)

    CHRISTIANS RESPOND? ABSTRACT. The results of the 2010 Corruption Perceptions Index of Transparency International indicate the seriousness of the worldwide corruption problem. Although recent decades have witnessed a global public awareness and an increase in attempts to eradicate corruption, it is an ongoing ...

  9. Sixty years of lithium responders.

    Science.gov (United States)

    Grof, Paul

    2010-01-01

    It has been 60 years since Cade first described patients who responded to antimanic lithium treatment. Two decades later, responders to lithium stabilization emerged in larger numbers. The responses of many severely ill bipolar patients to lithium were striking and called for an explanation. Remarkable reactions to a simple ion generated hope for an uncomplicated laboratory test of response and an extensive search for suitable biological markers ensued. But despite promising reports, particularly from molecular genetics, we are still waiting for a biological elucidation of the stabilizing effects of lithium. The most useful predictor of lithium stabilization has to date been the patient's clinical profile, based on a comprehensive clinical assessment: complete remissions and other characteristics of episodic clinical course, bipolar family history, low psychiatric comorbidity and a characteristic presenting psychopathology. In brief, the responders approximate the classical Kraepelinian description of a manic-depressive patient. But the most intriguing findings have recently emerged from prospective observations of the next generation: the children of lithium responders, their counterparts coming from parents who did not respond to lithium and controls. Overall, they indicate that parents and offspring suffer from a comparable brain dysfunction that manifests clinically in distinct stages. If the child's predicament starts early in childhood, it presents with varied, nonaffective or subclinical manifestations that are usually nonresponsive to standard treatments prescribed according to the symptoms. The next stage then unfolds in adolescence, first with depressive and later with activated episodes. The observations have a potential to markedly enrich the prevailing understanding and management of mood disorders. Copyright 2010 S. Karger AG, Basel.

  10. Squeezing and higher-order squeezing of photon-added coherent states propagating in a Kerr-like medium

    Science.gov (United States)

    Sudheesh, C.; Lakshmibala, S.; Balakrishnan, V.

    2005-12-01

    We investigate the squeezing and higher-order squeezing properties of photon-added coherent states propagating through a Kerr-like medium, particularly close to instants of revivals and fractional revivals of the state. The Wigner functions at these instants are obtained, and the extent of non-classicality quantified.

  11. Coherent control of polarization state rotation via Doppler broadening and Kerr nonlinearity in a spinning fast light medium

    Science.gov (United States)

    Rahman, Habibur; Hizbullah; Jabar, M. S. Abdul; Khan, Anwar Ali; Ahmad, Iftikhar; Amin Bacha, Bakht

    2014-11-01

    We propose a four-level experimental N-type atomic configuration to observe the propagation of a light pulse in a spinning dispersive medium. In this model a fast propagating light pulse is observed in which the polarization states of the light and their transmitted images are rotated in the opposite direction to the spinning medium. We investigate the effects of Doppler broadening and Kerr nonlinearity on fast light propagation in a spinning medium. Doppler broadening and Kerr nonlinearity strongly influence the rotation of the polarization states of the light and images of fast light in a spinning medium. A pulse of group velocity -c/2000.5 ms-1 is enhanced to -c/80000 ms-1 due to the the Kerr effect and a significant increase is observed in the rotation of the polarization states of the light and images. At a specific parameter, a 25% fraction change is observed due to the Kerr effect. These results provide different rotation states for image coding.

  12. Time-Translation Invariance of Scattering Maps and Blue-Shift Instabilities on Kerr Black Hole Spacetimes

    Science.gov (United States)

    Dafermos, Mihalis; Shlapentokh-Rothman, Yakov

    2017-03-01

    In this paper, we provide an elementary, unified treatment of two distinct blue-shift instabilities for the scalar wave equation on a fixed Kerr black hole background: the celebrated blue-shift at the Cauchy horizon (familiar from the strong cosmic censorship conjecture) and the time-reversed red-shift at the event horizon (relevant in classical scattering theory). Our first theorem concerns the latter and constructs solutions to the wave equation on Kerr spacetimes such that the radiation field along the future event horizon vanishes and the radiation field along future null infinity decays at an arbitrarily fast polynomial rate, yet, the local energy of the solution is infinite near any point on the future event horizon. Our second theorem constructs solutions to the wave equation on rotating Kerr spacetimes such that the radiation field along the past event horizon (extended into the black hole) vanishes and the radiation field along past null infinity decays at an arbitrarily fast polynomial rate, yet, the local energy of the solution is infinite near any point on the Cauchy horizon. The results make essential use of the scattering theory developed in Dafermos, Rodnianski and Shlapentokh-Rothman ( A scattering theory for the wave equation on Kerr black hole exteriors (2014). arXiv:1412.8379) and exploit directly the time-translation invariance of the scattering map and the non-triviality of the transmission map.

  13. Saddleworth, Responding to a Landscape

    OpenAIRE

    Murray, Matthew

    2017-01-01

    Matthew Murray's Landscape publication Saddleworth, Responding To A Landscape. Forward by Martin Barnes Senior Curator of Photographs at The Victoria and Albert Museum, London, Artist Richard Billingham and Maartje van den Heuvel Curator Photography and Media Culture -Leiden Institute. \\ud \\ud ‘Every trip I have taken to Saddleworth Moor over four years has encapsulated each season, weather and cloud pattern, rain, sunshine, snow, early morning clear skies and the sense of the bitter cold of ...

  14. An integrated command control and communications center for first responders

    Science.gov (United States)

    Messner, Richard A.; Hludik, Frank; Vidacic, Dragan; Melnyk, Pavlo

    2005-05-01

    First responders to a major incident include many different agencies. These may include law enforcement officers, multiple fire departments, paramedics, HAZMAT response teams, and possibly even federal personnel such as FBI and FEMA. Often times multiple jurisdictions respond to the incident which causes interoperability issues with respect to communication and dissemination of time critical information. Accurate information from all responding sources needs to be rapidly collected and made available to the current on site responders as well as the follow-on responders who may just be arriving on scene. The creation of a common central database with a simple easy to use interface that is dynamically updated in real time would allow prompt and efficient information distribution between different jurisdictions. Such a system is paramount to the success of any response to a major incident. First responders typically arrive in mobile vehicles that are equipped with communications equipment. Although the first responders may make reports back to their specific home based command centers, the details of those reports are not typically available to other first responders who are not a part of that agencies infrastructure. Furthermore, the collection of information often occurs outside of the first responder vehicle and the details of the scene are normally either radioed from the field or written down and then disseminated after significant delay. Since first responders are not usually on the same communications channels, and the fact that there is normally a considerable amount of confusion during the first few hours on scene, it would be beneficial if there were a centralized location for the repository of time critical information which could be accessed by all the first responders in a common fashion without having to redesign or add significantly to each first responders hardware/software systems. Each first responder would then be able to provide information

  15. Order Responding to Petitioner's Request that the Administrator Object to Issuance of a State Operating Permit to Kerr-McGee Chemicals, LLC in Theodore, AL

    Science.gov (United States)

    This document may be of assistance in applying the Title V air operating permit regulations. This document is part of the Title V Petition Database available at www2.epa.gov/title-v-operating-permits/title-v-petition-database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

  16. Biodetection Technologies for First Responders

    Energy Technology Data Exchange (ETDEWEB)

    Baird, Cheryl L.; Seiner, Derrick R.; Ozanich, Richard M.; Bartholomew, Rachel A.; Colburn, Heather A.; Straub, Tim M.; Bruckner-Lea, Cindy J.

    2012-10-24

    In a white powder scenario, there are a large number of field-deployable assays that can be used to determine if the suspicious substance contains biological material and warrants further investigation. This report summarizes commercially available technologies that are considered hand portable and can be used by first responders in the field. This is not meant to be an exhaustive list, nor do the authors endorse any of the technologies described herein. Rather, it is meant to provide useful information about available technologies to help end-users make informed decisions about biodetection technology procurement and use.

  17. Dishonest responding or true virtue?

    DEFF Research Database (Denmark)

    Zettler, Ingo; Hilbig, Benjamin E.; Moshagen, Morten

    2015-01-01

    management scores indeed reflect true virtues rather than dishonesty under such conditions. We found support for this idea by replicating previous correlations between impression management scores and virtue-related basic personality traits (including honesty-humility), and additionally provided conclusive...... behavioral evidence: We linked scores on an impression management scale administered under typical low demand condition to behavior in an incentivized, anonymous cheating task. The results clearly indicate that low scores in impression management are associated with more cheating. That is, high—and not low......—scores on the Impression Management scale of the Balanced Inventory of Desirable Responding are aligned with more virtuous, honest behavior....

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

    Science.gov (United States)

    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.

  19. Testing the Kerr black hole hypothesis: Comparison between the gravitational wave and the iron line approaches

    Energy Technology Data Exchange (ETDEWEB)

    Cárdenas-Avendaño, Alejandro [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China); Programa de Matemática, Fundación Universitaria Konrad Lorenz, 110231 Bogotá (Colombia); Jiang, Jiachen [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China); Bambi, Cosimo, E-mail: bambi@fudan.edu.cn [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China); Theoretical Astrophysics, Eberhard-Karls Universität Tübingen, 72076 Tübingen (Germany)

    2016-09-10

    The recent announcement of the detection of gravitational waves by the LIGO/Virgo Collaboration has opened a new window to test the nature of astrophysical black holes. Konoplya & Zhidenko have shown how the LIGO data of GW 150914 can constrain possible deviations from the Kerr metric. In this letter, we compare their constraints with those that can be obtained from accreting black holes by fitting their X-ray reflection spectrum, the so-called iron line method. We simulate observations with eXTP, a next generation X-ray mission, finding constraints much stronger than those obtained by Konoplya & Zhidenko. Our results can at least show that, contrary to what is quite commonly believed, it is not obvious that gravitational waves are the most powerful approach to test strong gravity. In the presence of high quality data and with the systematics under control, the iron line method may provide competitive constraints.

  20. Polar Kerr Effect as Probe for Time-Reversal Symmetry Breaking in Unconventional Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kapitulnik, A.

    2010-05-26

    The search for broken time reversal symmetry (TRSB) in unconventional superconductors intensified in the past year as more systems have been predicted to possess such a state. Following our pioneering study of TRSB states in Sr{sub 2}RuO{sub 4} using magneto-optic probes, we embarked on a systematic study of several other of these candidate systems. The primary instrument for our studies is the Sagnac magneto-optic interferometer, which we recently developed. This instrument can measure magneto-optic Faraday or Kerr effects with an unprecedented sensitivity of 10 nanoradians at temperatures as low as 100 mK. In this paper we review our recent studies of TRSB in several systems, emphasizing the study of the pseudogap state of high temperature superconductors and the inverse proximity effect in superconductor/ferromagnet proximity structures.

  1. Vortex magnetic structure in circularly magnetized microwires as deduced from magneto-optical Kerr measurements

    KAUST Repository

    Ivanov, Yurii P.

    2014-02-14

    The magneto-optic Kerr effect has been employed to determine the magnetization process and estimate the domain structure of microwires with circular magnetic anisotropy. The diameter of microwires was 8 μm, and pieces 2 cm long were selected for measurements. The analysis of the local surface longitudinal and transverse hysteresis loops has allowed us to deduce a vortex magnetic structure with axial core and circular external shell. Moreover, a bamboo-like surface domain structure is confirmed with wave length of around 10 to 15 μm and alternating chirality in adjacent circular domains. The width of the domain wall is estimated to be less than 3 μm. Finally, closure domain structures with significant helical magnetization component are observed extending up to around 1000 μm from the end of the microwire.

  2. A scattering theory for the wave equation on Kerr black hole exteriors

    CERN Document Server

    Dafermos, Mihalis; Shlapentokh-Rothman, Yakov

    2014-01-01

    We develop a definitive physical-space scattering theory for the scalar wave equation on Kerr exterior backgrounds in the general subextremal case |a|

  3. Spin Interaction under the Collision of Two Kerr-(Anti-de Sitter Black Holes

    Directory of Open Access Journals (Sweden)

    Bogeun Gwak

    2017-12-01

    Full Text Available We investigate herein the spin interaction during collisions between Kerr-(anti-de Sitter black holes. The spin interaction potential depends on the relative rotation directions of the black holes, and this potential can be released as gravitational radiation upon collision. The energy of the radiation depends on the cosmological constant and corresponds to the spin interaction potential in the limit that one of the black holes has negligibly small mass and angular momentum. We then determine the approximate overall behaviors of the upper bounds on the radiation using thermodynamics. The results indicate that the spin interaction can consistently contribute to the radiation. In addition, the radiation depends on the stability of the black hole produced by the collision.

  4. Gap soliton transparency switching in one-dimensional Kerr-metamaterial superlattices

    Science.gov (United States)

    Lobo, T. P.; Oliveira, L. E.; Cavalcanti, S. B.

    2017-12-01

    Plasmon-polariton gap soliton formation and transparency switching in one-dimensional nonlinear layered systems composed of alternate layers of a Kerr material and a dispersive linear metamaterial are theoretically studied. The behavior of the electric field profile inside the layered system is shown for different values of nonlinear power, linking the localized modes of the electric field with complete transparency states of the system. A detailed investigation on the influence of a defocusing nonlinearity on the transmission switching phenomenon, in the frequency range where the linear dispersion predicts the photon-plasmon coupling, is made, revealing different effects in the top and bottom edges of the plasmon-polariton gap. Specifically, we found a broadening of the plasmon-polariton gap when increasing the nonlinear power. In addition, a switching from very low to high transmission states is obtained and localized plasmon-polariton gap solitons of various orders are found for various values of frequencies and nonlinear strength.

  5. Radiative evolution of the Carter constant for generic orbits around a Kerr black hole

    Science.gov (United States)

    Ori, Amos

    1997-03-01

    Recently, we proposed a new approach for the radiative evolution of generic orbits around a Kerr black hole. This involves the calculation of the evolution rate of all three constants of motion: The energy E, the azimuthal angular momentum Lz, and the Carter constant Q. In a previous paper we presented the general approach, and outlined its application to a scalar-field radiation reaction. In the present paper, we give the full details of the scalar-field calculations: We first derive the explicit expressions for Edo;, Ldotz, and Qdot. Then, we compare our results for Edot and Ldotz to those obtained from the standard method, and show that they are in full agreement. In addition, we outline the application of our method to the electromagnetic and gravitational radiation-reaction problem.

  6. Optomechanics with a position-modulated Kerr-type nonlinear coupling

    Science.gov (United States)

    Mikkelsen, M.; Fogarty, T.; Twamley, J.; Busch, Th.

    2017-10-01

    Cavity optomechanics has proven to be a field of research rich with possibilities for studying motional cooling, squeezing, quantum entanglement, and metrology in solid-state systems. While to date most studies have focused on the modulation of the cavity frequency by the moving element, the emergence of new materials will soon allow us to explore the influences of nonlinear optical effects. We therefore study in this work the effects due to a nonlinear position-modulated self-Kerr interaction and find that this leads to an effective coupling that scales with the square of the photon number, meaning that significant effects appear even for very small nonlinearities. This strong effective coupling can lead to lower powers required for motional cooling and the appearance of multistability in certain regimes.

  7. Korteweg-de Vries description of Helmholtz-Kerr dark solitons

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J M [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom) ; McDonald, G S [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom) ; Chamorro-Posada, P [Departmento de TeorIa de la Senal y Comunicaciones e IngenierIa Telematica, Universidad de Valladolid, ETSI Telecomunicacion, Campus Miguel Delibes s/n, 47011 Valladolid (Spain)

    2006-12-15

    A wide variety of different physical systems can be described by a relatively small set of universal equations. For example, small-amplitude nonlinear Schroedinger dark solitons can be described by a Korteweg-de Vries (KdV) equation. Reductive perturbation theory, based on linear boosts and Gallilean transformations, is often employed to establish connections to and between such universal equations. Here, a novel analytical approach reveals that the evolution of small-amplitude Helmholtz-Kerr dark solitons is also governed by a KdV equation. This broadens the class of nonlinear systems that are known to possess KdV soliton solutions, and provides a framework for perturbative analyses when propagation angles are not negligibly small. The derivation of this KdV equation involves an element that appears new to weakly nonlinear analyses, since transformations are required to preserve the rotational symmetry inherent to Helmholtz-type equations.

  8. Quantum radiation of Maxwell’s electromagnetic field in nonstationary Kerr-de Sitter black hole

    Science.gov (United States)

    Ibungochouba Singh, T.; Ablu Meitei, I.; Yugindro Singh, K.

    2016-03-01

    Quantum radiation properties of nonstationary Kerr-de Sitter (KdS) black hole is investigated using the method of generalized tortoise coordinate transformation. The locations of horizons and the temperature of the thermal radiation as well as the maximum energy of the nonthermal radiation are derived. It is found that the surface gravity and the Hawking temperature depend on both time and different angles. An extra coupling effect is obtained in the thermal radiation spectrum of Maxwell’s electromagnetic field equations which is absent in the thermal radiation spectrum of scalar particles. Further, the chemical potential derived from the thermal radiation spectrum of scalar particle has been found to be equal to the highest energy of the negative energy state of the scalar particle in the nonthermal radiation for KdS black hole. It is also shown that the generalized tortoise coordinate transformation produces a constant term in the expression of the surface gravity and Hawking temperature.

  9. Measuring the Nonlinear Refractive Index of Graphene using the Optical Kerr Effect Method

    CERN Document Server

    Dremetsika, Evdokia; Gorza, Simon-Pierre; Ciret, Charles; Martin, Marie-Blandine; Hofmann, Stephan; Seneor, Pierre; Dolfi, Daniel; Massar, Serge; Emplit, Philippe; Kockaert, Pascal

    2016-01-01

    By means of the ultrafast optical Kerr effect method coupled to optical heterodyne detection (OHD-OKE), we characterize the third order nonlinear response of graphene at telecom wavelength, and compare it to experimental values obtained by the Z-scan method on the same samples. From these measurements, we estimate a negative nonlinear refractive index for monolayer graphene, $n_2 = - 1.1\\times 10^{-13} m^2/W$. This is in contradiction to previously reported values, which leads us to compare our experimental measurements obtained by the OHD-OKE and the Z-scan method with theoretical and experimental values found in the literature, and to discuss the discrepancies, taking into account parameters such as doping.

  10. Magneto-optic Kerr effect CCD imaging with polarization modulation technique

    Directory of Open Access Journals (Sweden)

    Satoru Nakayama

    2017-05-01

    Full Text Available We have developed a magneto-optic Kerr effect (MOKE imaging system with a charge-coupled-device (CCD camera by using the rotating compensator technique. We chose optimal conditions of the rotation frequency of the compensator with stable rotation along with a CCD camera frame rate that allowed precise control of the exposure timing in order to link with the angle of the compensator. Precise timing management of the CCD exposure enables us to carry out repeated experiments, which greatly improves the signal-to-noise ratio of the longitudinal MOKE signal. We applied the technique to the material characterization of the Ni81 Fe19 thin film and its microstructure, and succeeded in evaluating the spatial variation of the complex magneto-optic constant Q of the sample. Because of its attractive advantages such as high-speed and compactness, the present method provides a novel platform for investigating the domain structures in various magnetic materials.

  11. Gate-controllable magneto-optic Kerr effect in layered collinear antiferromagnets

    Science.gov (United States)

    Sivadas, Nikhil; Okamoto, Satoshi; Xiao, Di

    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 magneto-optic Kerr effect (MOKE) in bilayer MnPSe3 using first-principles calculations. 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. This work is supported by AFOSR No. FA9550-12-1-0479 and FA9550-14-1-0277 and NSP No. EFRI-1433496.

  12. Absence of detectable current-induced magneto-optical Kerr effects in Pt, Ta, and W

    Science.gov (United States)

    Riego, Patricia; Vélez, Saül; Gomez-Perez, Juan M.; Arregi, Jon Ander; Hueso, Luis E.; Casanova, Fèlix; Berger, Andreas

    2016-10-01

    We explore the possibility to detect spin accumulation due to the spin Hall effect (SHE) by means of the magneto-optical Kerr effect (MOKE). For this purpose, we utilize the generalized magneto-optical ellipsometry (GME), which enables the disentanglement of different magnetization components contributing to the resulting MOKE signal, and perform measurements for three different materials: Pt, W, and Ta. Although we observe a current-induced effect in the light intensity in our polarization sensitive GME setup, it does not arise from a SHE-induced light polarization signal in any of the materials, but from a change in reflectivity due to heating effects. Based on the sensitivity achieved in our experiments, we conclude that state-of-the-art magneto-optical methods utilizing linear optics are not sufficiently sensitive to detect SHE-induced spin accumulation in these metals.

  13. Magneto-optic Kerr effect CCD imaging with polarization modulation technique

    Science.gov (United States)

    Nakayama, Satoru; Okano, Makoto; Nozaki, Yukio; Watanabe, Shinichi

    2017-05-01

    We have developed a magneto-optic Kerr effect (MOKE) imaging system with a charge-coupled-device (CCD) camera by using the rotating compensator technique. We chose optimal conditions of the rotation frequency of the compensator with stable rotation along with a CCD camera frame rate that allowed precise control of the exposure timing in order to link with the angle of the compensator. Precise timing management of the CCD exposure enables us to carry out repeated experiments, which greatly improves the signal-to-noise ratio of the longitudinal MOKE signal. We applied the technique to the material characterization of the Ni81 Fe19 thin film and its microstructure, and succeeded in evaluating the spatial variation of the complex magneto-optic constant Q of the sample. Because of its attractive advantages such as high-speed and compactness, the present method provides a novel platform for investigating the domain structures in various magnetic materials.

  14. Simple quadratic magneto-optic Kerr effect measurement system using permanent magnets

    Science.gov (United States)

    Pradeep, A. V.; Ghosh, Sayak; Anil Kumar, P. S.

    2017-01-01

    In recent times, quadratic magneto-optic Kerr effect (QMOKE) is emerging as an important experimental tool to investigate higher-order spin-orbit interactions in magnetic thin films and heterostructures. We have designed and constructed a simple, cost-effective QMOKE measurement system using permanent magnets. The permanent magnets are mounted on the inner surface of a cylindrical ferromagnetic yoke which can be rotated about its axis. Our system is sensitive to both the quadratic and linear MOKE signals. We use rotating field method to extract the QMOKE components in saturation. This system is capable of extracting the QMOKE signal from single crystals and thin film samples. Here we present the construction and working of the QMOKE measurement system using permanent magnets and report, for the first time, the QMOKE signal from Fe3O4 single crystal.

  15. Note: Probing quadratic magneto-optical Kerr effects with a dual-beam system.

    Science.gov (United States)

    Trudel, Simon; Wolf, Georg; Schultheiss, Helmut; Hamrle, Jaroslav; Hillebrands, Burkard; Kubota, Takahide; Ando, Yasuo

    2010-02-01

    In this Note, we present a dual-beam magneto-optical Kerr effect (MOKE) magnetometer for the study of quadratic MOKE in magnetic thin films. The two beams simultaneously probe the sample, located in the middle of a quadrupole magnet, at two angles of incidence (0 degrees and 45 degrees). This combination of two systems allows one to automatically and routinely perform measurements that are sensitive to the combined longitudinal and quadratic MOKE signals (45 degrees), or the quadratic effect alone (0 degrees). Orientation-dependent and automated quantitative analyses of the quadratic effect's amplitude are also implemented. We present representative measurements on Heusler compound thin films to illustrate the newly combined capabilities of this instrument.

  16. Versatile, high sensitivity, and automatized angular dependent vectorial Kerr magnetometer for the analysis of nanostructured materials.

    Science.gov (United States)

    Teixeira, J M; Lusche, R; Ventura, J; Fermento, R; Carpinteiro, F; Araujo, J P; Sousa, J B; Cardoso, S; Freitas, P P

    2011-04-01

    Magneto-optical Kerr effect (MOKE) magnetometry is an indispensable, reliable, and one of the most widely used techniques for the characterization of nanostructured magnetic materials. Information, such as the magnitude of coercive fields or anisotropy strengths, can be readily obtained from MOKE measurements. We present a description of our state-of-the-art vectorial MOKE magnetometer, being an extremely versatile, accurate, and sensitivity unit with a low cost and comparatively simple setup. The unit includes focusing lenses and an automatized stepper motor stage for angular dependent measurements. The performance of the magnetometer is demonstrated by hysteresis loops of Co thin films displaying uniaxial anisotropy induced on growth, MnIr/CoFe structures exhibiting the so called exchange bias effect, spin valves, and microfabricated flux guides produced by optical lithography. © 2011 American Institute of Physics

  17. Mössbauer and Kerr microscopy investigation of crystallization in FeCoB ribbons

    Science.gov (United States)

    Reddy, V. Raghavendra; Hussain, Zaineb; Babu, Hari; Shrivastava, Namrata; Gupta, Ajay

    2016-05-01

    The present work reports the crystallization study of amorphous FeCoB ribbons using x-ray diffraction, 57Fe 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, (Fe0.5Co0.5)2B and Fe2B 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 of the presence of internal stresses and their annealing with thermal heat treatment.

  18. Vectorial Kerr magnetometer for simultaneous and quantitative measurements of the in-plane magnetization components.

    Science.gov (United States)

    Jiménez, E; Mikuszeit, N; Cuñado, J L F; Perna, P; Pedrosa, J; Maccariello, D; Rodrigo, C; Niño, M A; Bollero, A; Camarero, J; Miranda, R

    2014-05-01

    A vectorial magneto-optic Kerr effect (v-MOKE) setup with simultaneous and quantitative determination of the two in-plane magnetization components is described. The setup provides both polarization rotations and reflectivity changes at the same time for a given sample orientation with respect to a variable external magnetic field, as well as allowing full angular studies. A classical description based on the Jones formalism is used to calculate the setup's properties. The use of different incoming light polarizations and/or MOKE geometries, as well as the errors due to misalignment and solutions are discussed. To illustrate the capabilities of the setup a detailed study of a model four-fold anisotropy system is presented. Among others, the setup allows to study the angular dependence of the hysteresis phenomena, remanences, critical fields, and magnetization reversal processes, as well as the accurate determination of the easy and hard magnetization directions, domain wall orientations, and magnetic anisotropies.

  19. Quantum gravity of Kerr-Schild spacetimes and the logarithmic correction to Schwarzschild black hole entropy

    Energy Technology Data Exchange (ETDEWEB)

    El-Menoufi, Basem Kamal [Department of Physics, University of Massachusetts,Amherst, MA 01003 (United States)

    2016-05-05

    In the context of effective field theory, we consider quantum gravity with minimally coupled massless particles. Fixing the background geometry to be of the Kerr-Schild type, we fully determine the one-loop effective action of the theory whose finite non-local part is induced by the long-distance portion of quantum loops. This is accomplished using the non-local expansion of the heat kernel in addition to a non-linear completion technique through which the effective action is expanded in gravitational curvatures. Via Euclidean methods, we identify a logarithmic correction to the Bekenstein-Hawking entropy of Schwarzschild black hole. Using dimensional transmutation the result is shown to exhibit an interesting interplay between the UV and IR properties of quantum gravity.

  20. Exploiting Kerr Cross Non-linearity in Circuit Quantum Electrodynamics for Non-demolition Measurements

    Science.gov (United States)

    Kumar, Shwetank; Divincenzo, David

    2010-03-01

    High quality factor microwave resonators are versatile devices which find many applications in circuits for scalable quantum computing architectures. We will present a novel circuit for dispersive readout of energy stored in one mode of a nonlinear superconducting ring resonator by detecting frequency shift of a second mode coupled to the first via Kerr nonlinearity. Symmetry is used to enhance the circuit responsivity by minimizing the nonlinear terms that do not contribute to the detector response. Assessment of the signal to noise ratio indicates that the scheme will function at the single photon level, allowing quantum non-demolition measurement of the photon number state of one resonator mode. Experimental data from a simplified version of the device demonstrating the principle of operation will be presented. Extensions of this work to implement on-chip superconducting beam splitters with applications towards linear optics qubit schemes will be discussed.

  1. Strong gravitational lensing for the photons coupled to Weyl tensor in a Kerr black hole spacetime

    CERN Document Server

    Chen, Songbai; Huang, Yang; Jing, Jiliang; Wang, Shiliang

    2016-01-01

    We present firstly equation of motion for the photon coupled to Weyl tensor in a Kerr black hole spacetime and then study further the corresponding strong gravitational lensing. We find that black hole rotation makes propagation of the coupled photons more complicated, which brings some new features for physical quantities including the marginally circular photon orbit, the deflection angle, the observational gravitational lensing variables and the time delay between two relativistic images. There is a critical value of the coupling parameter for existence of the marginally circular photon orbit outside the event horizon, which depends on the rotation parameter of black hole and the polarization direction of photons. As the value of coupling parameter is near the critical value, we find that the marginally circular photon orbit for the retrograde photon increases with the rotation parameter, which modifies a common feature of the marginally circular photon orbit in a rotating black hole spacetime since it alw...

  2. Mössbauer and Kerr microscopy investigation of crystallization in FeCoB ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, V. Raghavendra, E-mail: varimalla@yahoo.com, E-mail: vrreddy@csr.res.in; Hussain, Zaineb; Babu, Hari [UGC DAE Consortium for Scientific Research, University Campus, Kandhwa Road, Indore-452001 India (India); Shrivastava, Namrata [School of Physics, DAVV, Khandwa Road, Indore – 452001 India (India); Gupta, Ajay [Amity Centre for Spintronic Materials, Amity University, Noida 201303.India (India)

    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 of the presence of internal stresses and their annealing with thermal heat treatment.

  3. Optical Kerr phase shift in a nanostructured nickel-doped zinc oxide thin solid film.

    Science.gov (United States)

    Torres-Torres, C; Can-Uc, B A; Rangel-Rojo, R; Castañeda, L; Torres-Martínez, R; García-Gil, C I; Khomenko, A V

    2013-09-09

    The optical Kerr effect exhibited by a nickel doped zinc oxide thin solid film was explored with femto- and pico-second pulses using the z-scan method. The samples were prepared by the ultrasonic spray pyrolysis technique. Opposite signs for the value of the nonlinear refractive index were observed in the two experiments. Self-defocusing together with a two-photon absorption process was observed with 120 ps pulses at 1064 nm, while a dominantly self-focusing effect accompanied by saturated absorption was found for 80 fs pulses at 825 nm. Regarding the nanostructured morphology of the resulting film, we attribute the difference in the two ultrafast optical responses to the different physical mechanism responsible of energy transfer generated by multiphoton processes under electronic and thermal effects.

  4. Shadow of a Kerr-Sen dilaton-axion Black Hole

    CERN Document Server

    Dastan, Sara; Soroushfar, Saheb

    2016-01-01

    We analyze the shadow of charged stationary axially symmetric space-time (Kerr-Sen dilaton-axion black hole). This black hole is defined by a mass $M$, a spin $a$ and $r_{\\alpha}=Q^{2}/M$, where $Q$ is the electric charge. Shadows are investigated in two conditions, i) for an observer at infinity in vacuum and ii) for an observer at infinity in the presence of plasma with radial power-low density. In vacuum, the shadow of this black hole depends on charge and spin parameter. We can see that, increasing electric charge, $Q$ decreases the size of shadow. Also, increasing spin parameter $a$ decreases the size of shadow. However, in existence of plasma, parameter of plasma like refraction index, $n$, playing an important role on shadows. In fact, decreasing refraction index decreases the size of shadow.

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

    Science.gov (United States)

    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.

  6. Laboratory upwelled radiance and reflectance spectra of Kerr reservoir sediment waters

    Science.gov (United States)

    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.

  7. Gravitational perturbation induced by a rotating ring around a Kerr black hole

    CERN Document Server

    Sano, Yasumichi

    2014-01-01

    The linear perturbation of a Kerr black hole induced by a rotating massive circular ring is discussed by using the formalism by Teukolsky, Chrzanowski, Cohen and Kegeles. In these formalism, the perturbed Weyl scalars, $\\psi_0$ and $\\psi_4$, are first obtained from the Teukolsky equation. The perturbed metric is obtained in a radiation gauge via the Hertz potential. The computation can be done in the same way as in our previous paper, in which we considered the perturbation of a Schwarzschild black hole induced by a rotating ring. By adding lower multipole modes such as mass and angular momentum perturbation which are not computed by the Teukolsky equation, and by appropriately setting the parameters which are related to the gauge freedom, we obtain the perturbed gravitational field which is smooth except on the equatorial plane outside the ring.

  8. Quasinormal ringing of Kerr black holes. II. Excitation by particles falling radially with arbitrary energy

    CERN Document Server

    Zhang, Zhongyang; Cardoso, Vitor

    2013-01-01

    The analytical understanding of quasinormal mode ringing requires an accurate knowledge of the Green's function describing the response of the black hole to external perturbations. We carry out a comprehensive study of quasinormal mode excitation for Kerr black holes. Relying on the formalism developed by Mano, Suzuki and Takasugi, we improve and extend previous calculations of the quasinormal mode residues in the complex frequency plane ("excitation factors" B_q). Using these results we compute the "excitation coefficients" C_q (essentially the mode amplitudes) in the special case where the source of the perturbations is a particle falling into the black hole along the symmetry axis. We compare this calculation with numerical integrations of the perturbation equations, and we show quantitatively how the addition of higher overtones improves the agreement with the numerical waveforms. Our results should find applications in models of the ringdown stage and in the construction of semianalytical template banks ...

  9. Magneto-optical Kerr-effect at low temperatures. Investigation of superconductor/ferromagnet heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zahn, Patrick; Bayer, Jonas [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Institute for Innovative Surfaces FINO, Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany); Stahl, Claudia; Ruoss, Stephen; Graefe, Joachim; Schuetz, Gisela [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Albrecht, Joachim [Institute for Innovative Surfaces FINO, Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany)

    2016-07-01

    With XMCD microscopy it is possible to visualize the critical current density of the superconductor YBCO with high spatial resolution. Therefore, soft magnetic CoFeB is introduced as sensor layer. The magnetic stray fields of the supercurrents lead to a local reorientation of the magnetic moments in the ferromagnet, which are then imaged via X-ray microscopy. These experiments have to be carried out at the scanning X-ray microscope MAXYMUS at the synchrotron Bessy II in Berlin. For that purpose pre-characterization of the sensor is highly desirable: Magnetic interactions between the superconductor and the ferromagnetic sensor layer have been investigated at low temperatures using Kerr-effect measurements. Therefore hysteresis loops are obtained by a sophisticated magnet and field ramping setup within the NanoMOKE3 system. The results are used to optimize the ferromagnetic sensor layer for XMCD microscopy of superconductors.

  10. Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator.

    Science.gov (United States)

    Wu, Liang; Salehi, M; Koirala, N; Moon, J; Oh, S; Armitage, N P

    2016-12-02

    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. Copyright © 2016, American Association for the Advancement of Science.

  11. MO Kerr and Faraday studies of Au/Co ultrathin film structures

    Science.gov (United States)

    Ferré, J.; Nývlt, M.; Pénissard, G.; Prosser, V.; Renard, D.; Višňovský, Šf.

    1995-07-01

    Magneto-optical (MO) polar Kerr and Faraday effect spectra in Au(5 nm) /Co/Au(25 nm) structures deposited by thermal evaporation in an ultrahigh-vacuum chamber on float glass substrates are reported. The Co layer thickness was varied only between 0.4 and 2 nm to preserve a perpendicular spin alignment under a moderate field. The experimental results are well explained with an electromagnetic wave model employing bulk optical constants of Co and Au and MO data of Co. Approximate formulae for a trilayer demonstrate the effects of ultrathin Co, Au buffer and overlayer thicknesses. Trends in the spectra when t Co varies from zero to 50 nm are illustrated.

  12. Coexistence of Multiple Nonlinear States in a Tristable Passive Kerr Resonator

    Science.gov (United States)

    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.

  13. Testosterone for Poor Ovarian Responders

    DEFF Research Database (Denmark)

    Polyzos, Nikolaos P; Davis, Susan R; Drakopoulos, Panagiotis

    2016-01-01

    Testosterone, an androgen that directly binds to the androgen receptor, has been shown in previous small randomized controlled trials to increase the reproductive outcomes of poor ovarian responders. In most of these studies, transdermal testosterone in relatively high doses was administered before...... ovarian stimulation with a duration varying from 5 to 21 days. Nevertheless, the key question to be asked is whether, based on ovarian physiology and testosterone pharmacokinetics, a short course of testosterone administration of more than 10 mg could be expected to have any beneficial effect...... on reproductive outcome. The rationale for asking this question lies in the existing scientific evidence derived from basic research and animal studies regarding the action of androgens during folliculogenesis, showing that their main effect in follicular development is defined during the earlier developmental...

  14. Building a rapid response team.

    Science.gov (United States)

    Halvorsen, Lisa; Garolis, Salomeja; Wallace-Scroggs, Allyson; Stenstrom, Judy; Maunder, Richard

    2007-01-01

    The use of rapid response teams is a relatively new approach for decreasing or eliminating codes in acute care hospitals. Based on the principles of a code team for cardiac and/or respiratory arrest in non-critical care units, the rapid response teams have specially trained nursing, respiratory, and medical personnel to respond to calls from general care units to assess and manage decompensating or rapidly changing patients before their conditions escalate to a full code situation. This article describes the processes used to develop a rapid response team, clinical indicators for triggering a rapid response team call, topics addressed in an educational program for the rapid response team members, and methods for evaluating effectiveness of the rapid response team.

  15. Linear and quadratic magneto-optical Kerr effect investigation of Co2Mn1.30Si0.84 epitaxially grown on MgO

    Science.gov (United States)

    Liu, Jihong; Qiao, Shuang; Wang, Shufang; Fu, Guangsheng

    2017-01-01

    We investigated the magneto-optical properties of a L21 ordered nonstoichiometric Co2Mn1.30Si0.84 film epitaxially grown on a MgO-buffered MgO (001) single-crystal substrate. Longitudinal magneto-optical Kerr effects (LMOKE) and rotating magneto-optical Kerr effect (ROT-MOKE) measurements suggest that the film exhibits a cubic magnetic anisotropy with the extracted cubic anisotropy constant of KC = 6.7 ×104 erg / cm3 . Orientation-dependent ROT-MOKE suggest that the quadratic magneto-optical Kerr effects (QMOKE) components also show fourfold symmetry with a modest amplitude of 3 mdeg, which is in accordance with complex Kerr angle expression for cubic symmetry systems. Our results suggest that ROT-MOKE is not only an efficient method to determine magnetic anisotropy parameters but also a good method to extract QMOKE components.

  16. Rapid response in psychological treatments for binge eating disorder.

    Science.gov (United States)

    Hilbert, Anja; Hildebrandt, Thomas; Agras, W Stewart; Wilfley, Denise E; Wilson, G Terence

    2015-06-01

    Analysis of short- and long-term effects of rapid response across 3 different treatments for binge eating disorder (BED). In a randomized clinical study comparing interpersonal psychotherapy (IPT), cognitive-behavioral therapy guided self-help (CBTgsh), and behavioral weight loss (BWL) treatment in 205 adults meeting Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; APA, 1994) criteria for BED, the predictive value of rapid response, defined as ≥70% reduction in binge eating by Week 4, was determined for remission from binge eating and global eating disorder psychopathology at posttreatment, 6-, 12-, 18-, and 24-month follow-ups. Rapid responders in CBTgsh, but not in IPT or BWL, showed significantly greater rates of remission from binge eating than nonrapid responders, which was sustained over the long term. Rapid and nonrapid responders in IPT and rapid responders in CBTgsh showed a greater remission from binge eating than nonrapid responders in CBTgsh and BWL. Rapid responders in CBTgsh showed greater remission from binge eating than rapid responders in BWL. Although rapid responders in all treatments had lower global eating disorder psychopathology than nonrapid responders in the short term, rapid responders in CBTgsh and IPT were more improved than those in BWL and nonrapid responders in each treatment. Rapid responders in BWL did not differ from nonrapid responders in CBTgsh and IPT. Rapid response is a treatment-specific positive prognostic indicator of sustained remission from binge eating in CBTgsh. Regarding an evidence-based, stepped-care model, IPT, equally efficacious for rapid and nonrapid responders, could be investigated as a second-line treatment in case of nonrapid response to first-line CBTgsh. (c) 2015 APA, all rights reserved).

  17. Giant Kerr nonlinearity and weak-light superluminal optical solitons in a four-state atomic system with gain doublet.

    Science.gov (United States)

    Hang, Chao; Huang, Guoxiang

    2010-02-01

    We consider an active-Raman-gain scheme for realizing giant Kerr nonlinearity and superluminal optical solitons in a four-state atomic system with a gain doublet. We show that this scheme, which is fundamentally different from those based on electromagnetically induced transparency (EIT), is capable of working at room temperature and eliminating nearly all attenuation and distortion.We demonstrate that, due to the appearance of a gain spectrum hole induced by the quantum interference effect induced by a signal field, a significant enhancement of Kerr nonlinearity of probe field can be realized effectively, which can be more than ten times larger than that arrived by the EIT-based scheme with the same energy-level configuration. Based on these important features, we obtain a giant cross-phase modulation effect and hence a stable long-distance propagation of optical solitons, which have superluminal propagating velocity and very low generating power.

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

    CERN Document Server

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

    2015-01-01

    We have switched GaAs/AlAs and AlGaAs/AlAs planar microcavities operating in the "original" telecom band by exploiting the instantaneous electronic Kerr effect. We demonstrate that resonance frequency reversibly shifts within a picosecond and the magnitude of the shift is affected by the backbone of the $\\lambda-$layer. We investigate experimentally and theoretically the role of the quality factor in terms of its effect on resonance frequency shift. Our model shows that the magnitude of the resonance frequency shift depends on the pump pulse duration and is maximized when the cavity cavity storage time is matched. Our experiments and our calculations indicate that the resonance frequency shift induced via the electronic Kerr effect can be maximized by judicious tuning of the pump frequency, pump power and pump pulse duration relative to the storage time of the cavity.

  19. Enormous enhancements of the Kerr nonlinearity at C-band telecommunication wavelength in an Er3+-doped YAG crystal

    Science.gov (United States)

    Hamedi, Hamid Reza

    2014-06-01

    A novel solid configuration is proposed to achieve a giant Kerr nonlinearity with reduced absorption under conditions of slow light levels. It is shown that an enhanced Kerr nonlinearity accompanied with negligible absorption can be obtained just through the proper tuning of intensity of coherent driving field at C-band telecommunication wavelength which is practical for communication applications. Moreover, the impact of incoherent pump field as well as frequency detuning of coherent field on manipulating the linear and nonlinear optical properties of the yttrium-aluminum-garnet (YAG) crystal medium is discussed. The presented results may be of interest to researchers in the field of all-optical signal processing and solid-state quantum information science.

  20. Generation of an arbitrary four-photon polarization-entangled decoherence-free state with cross-Kerr nonlinearity

    Science.gov (United States)

    Wang, Meiyu; Yan, Fengli; Gao, Ting

    2017-08-01

    We present a new scheme to provide an arbitrary four-photon polarization-entangled state, which enables the encoding of single logical qubit information into a four-qubit decoherence-free subspace robustly against collective decoherence. With the assistance of the cross-Kerr nonlinearities, a spatial entanglement gate and a polarization entanglement gate are inserted into the circuit, where the X-quadrature homodyne measurement is properly performed. According to the outcomes of homodyne measurement in the spatial entanglement process, some swap gates are inserted into the corresponding paths of the photons to swap their spatial modes. Apart from Kerr media, some basic linear optical elements are necessary, which make it feasible with current experimental techniques.

  1. Imaging the ultrafast Kerr effect, free carrier generation, relaxation and ablation dynamics of Lithium Niobate irradiated with femtosecond laser pulses

    Science.gov (United States)

    Garcia-Lechuga, Mario; Siegel, Jan; Hernandez-Rueda, Javier; Solis, Javier

    2014-09-01

    The interaction of high-power single 130 femtosecond (fs) laser pulses with the surface of Lithium Niobate is experimentally investigated in this work. The use of fs-resolution time-resolved microscopy allows us to separately observe the instantaneous optical Kerr effect induced by the pulse and the generation of a free electron plasma. The maximum electron density is reached 550 fs after the peak of the Kerr effect, confirming the presence of a delayed carrier generation mechanism. We have also observed the appearance of transient Newton rings during the ablation process, related to optical interference of the probe beam reflected at the front and back surface of the ablating layer. Finally, we have analyzed the dynamics of the photorefractive effect on a much longer time scale by measuring the evolution of the transmittance of the irradiated area for different fluences below the ablation threshold.

  2. Spin relaxation and dephasing mechanism in (Ga,Mn)As studied by time-resolved Kerr rotation

    Science.gov (United States)

    Zhu, Yonggang; Zhang, Xinhui; Li, Tao; Chen, Lin; Lu, Jun; Zhao, Jianhua

    2009-04-01

    Spin dynamics in (Ga,Mn)As films grown on GaAs(001) was investigated by Time-resolved magneto-optical Kerr effect. The Kerr signal decay time of (Ga,Mn)As without external magnetic field applied was found to be several hundreds picoseconds, which suggested that photogenerated polarized holes and magnetic ions are coupled as a ferromagnetic system. Nonmonotonic temperature dependence of relaxation and dephasing (R&D) time and Larmor frequency manifests that Bir-Aronov-Pikus mechanism dominates the spin R&D time at low temperature, while D'yakonov-Perel mechanism dominates the spin R&D time at high temperature, and the crossover between the two regimes is Curie temperature.

  3. Brillouin/Raman compensation of the Kerr-effect-induced bias in a nonlinear ring laser gyroscope.

    Science.gov (United States)

    Luo, Zhang; Yuan, Xiaodong; Zhu, Zhihong; Liu, Ken; Ye, Weimin; Zeng, Chun; Ji, Jiarong

    2013-04-01

    In this Letter, the beat frequency at rest of a ring laser gyroscope with nonlinear effects is discussed in detail. Even without an additional intensity-stabilizing system, the random nullshift bias induced by the Kerr effect is compensated by the phase shift associated with the stimulated Brillouin/Raman scattering. And the nonlinear stimulated scattering also serves as the gain mechanism of the gyroscope. And thus the influence of the fluctuation of the injected pump intensity on the beat frequency is eliminated.

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

    Science.gov (United States)

    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.

  5. Soliton breathing induced by stimulated Raman scattering and self-steepening in octave-spanning Kerr frequency comb generation.

    Science.gov (United States)

    Bao, Chengying; Zhang, Lin; Kimerling, Lionel C; Michel, Jurgen; Yang, Changxi

    2015-07-13

    We investigate the impact of stimulated Raman scattering (SRS) and self-steepening (SS) on breather soliton dynamics in octave-spanning Kerr frequency comb generation. SRS and SS can transform chaotic fluctuations in cavity solitons into periodic breathing. Furthermore, with SRS and SS considered, bandwidth of the soliton breathes more than two times stronger. The simultaneous presence of SRS and SS also make the soliton breathe slower and degrades the coherence of the soliton.

  6. Aging of rubrene layers in Ni/rubrene heterostructures studied by magneto-optical Kerr effect spectroscopy.

    Science.gov (United States)

    Li, Wen; Fronk, Michael; Kupfer, Hartmut; Schulze, Steffen; Hietschold, Michael; Zahn, Dietrich R T; Salvan, Georgeta

    2010-04-28

    Magneto-optical Kerr effect (MOKE) spectroscopy was applied to probe the aging of Ni/rubrene bilayers under ambient atmosphere. A comparison between the simulated MOKE spectra of the heterostructure and the experimental MOKE spectra recorded at several time intervals after the samples were exposed to the ambient atmosphere demonstrates that the organic layer undergoes slow oxidation. The Ni top layer was found to exhibit capping properties, reducing the rate of oxidation of the organic underlayer in comparison with single organic layers.

  7. Magneto-optical Kerr spectra and magnetic properties of Co-substituted M-type strontium ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xiansong, E-mail: xiansongliu@ahu.edu.cn [Engineering Technology Research Center of Magnetic Materials, Anhui Province, School of Physics and Materials Science, Anhui University, Hefei 230039 (China); Fernandez-Garcia, Lucia [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo UO - Principado de Asturias, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain); Hu Feng; Zhu Deru [Engineering Technology Research Center of Magnetic Materials, Anhui Province, School of Physics and Materials Science, Anhui University, Hefei 230039 (China); Suarez, Marta; Menendez, Jose Luis [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo UO - Principado de Asturias, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Prepare single phase ferrites by substituted with Co{sup 2+}. Black-Right-Pointing-Pointer The magnetic properties were remarkably modified. Black-Right-Pointing-Pointer A very noticeable Kerr activity was obtained for the Co-substituted ferrites. - Abstract: M-type strontium ferrites SrFe{sub 12-x}Co{sub x}O{sub 19} (x = 0, 0.05, 0.10, 0.15, 0.20) were prepared by the conventional ceramic technology. The structure, magnetic properties and magneto-optical Kerr activity of the samples were investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and magneto-optical ellipsometry, respectively. X-ray diffraction showed that all the samples were single phase ferrites. The magnetic properties, especially the coercive field, were remarkably modified due to the substitution of cobalt. Most importantly, a noticeable Kerr activity was demonstrated in the Co-substituted M-type strontium ferrites with x = 0.20.

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

    Science.gov (United States)

    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.

  9. On the Unique Identification of the Polar Optical Kerr Effect with Microscopic Time-Reversal Symmetry Breaking

    Science.gov (United States)

    Fried, Alexander

    2014-03-01

    Over the past few decades, there has been an ongoing discussion regarding the choice of electromagnetic constitutive relations which correctly model linear media that exhibit natural optical activity, with most recent debate involving applications to optical phenomena in chiral superconductors and other gyrotropic media. In particular, is the controversy as to whether light incident upon naturally active materials will exhibit non-reciprocal polarization rotation in reflection, also known as the magneto-optical Kerr effect. A variety of constitutive relations have been postulated which describe the Electrodynamics within such materials, but only some of them predict this phenomena, while experimental investigations have similarly yielded mixed results. One such experiment uses a modified Sagnac Interferometer for high resolution and unique measurements of the Kerr effect and also has the property that it inherently tests for ``reciprocity,'' a metrological symmetry wherein the results of a measurement are the same as when an optical source and an optical detector are interchanged. We demonstrate theoretically and experimentally that the Sagnac Interferometer only measures time-reversal symemtry breaking and that gyrotropic materials can not give rise to a Kerr Effect.

  10. AFM study of combinatorial Ga sup + implanted Co sub 7 Ag sub 9 sub 3 film and its Kerr effect

    CERN Document Server

    Cai Ying Wen; Wei Lun; Li Jian Guo; Li Ai Guo; Ni Xin Bo; Zhang Gui Lin; Wang Song You; Shen Zuo Cheng; Li Jin; Chen Liang Yao

    2002-01-01

    A magneto-optic chip was prepared on Si wafer by combinatorial Ga sup + implantation into ion sputtered Co sub 7 Ag sub 9 sub 3 film. The surface morphology of each unit of the chip was detected by AFM, while their Kerr effect was measured by MOKE equipment. It is observed that the maximum Kerr rotation (MKR) occurs when the incident photon energy is around 3.8-3.9 eV. Summarisation of MKR versus implanted Ga sup + dose shows that the MKR enhancement by Ga sup + implantation can be characterized as incubation, enhancement and saturation regions. Considering the mutual solubility and surface morphology transition after annealing, it is suggested that Ga sup + tends to form CoGa and/or CoGa sub 3 intermetallic compounds. Before the formation of CoGa sub 3 compounds, no apparent MKR enhancement could be observed. While when the surface is half occupied by forest-like CoGa sub 3 compounds, MKR enhancement will be saturated. By comparison of the maximum Kerr rotation with the cone areal density, it can be induced ...

  11. SOLUCIÓN DE LA ECUACIÓN NO LINEAL DE SCHRODINGER (1+1 EN UN MEDIO KERR

    Directory of Open Access Journals (Sweden)

    Francis Armando Segovia

    2015-12-01

    Full Text Available Se presenta un marco teórico y se muestra una simulación numérica de la propagación de solitones. Con especial atención a los solitones ópticos espaciales, se calcula analíticamente el perfil de solitón correspondiente a la ecuación Schrodinger no-lineal para un medio Kerr. Los resultados muestran que los solitones ópticos son pulsos estables cuya forma y espectro son preservados en grandes distancias.Solution of the nonlinear Schrodinger equation (1+1 in a Kerr mediumABSTRACTThis document presents a theoretical framework and shows a numerical simulation for the propagation of solitons. With special attention to the spatial optical solitons, we calculates analytically the profile of solitón corresponding to the non-linear Schrodinger equation for a Kerr medium. The results show that the optical solitons are stable pulses whose shape and spectrum are preserved at great distances.Keywords: nonlinear optics, nonlinear Schrodinger equation, solitons.

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

    Science.gov (United States)

    Polewko-Klim, A; Uba, S; Uba, L

    2014-07-01

    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 modulation 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.

  13. The Hawking evaporation process of rapidly-rotating black holes: an almost continuous cascade of gravitons

    Energy Technology Data Exchange (ETDEWEB)

    Hod, Shahar [The Ruppin Academic Center, Emek Hefer (Israel); The Hadassah Institute, Jerusalem (Israel)

    2015-07-15

    It is shown that rapidly-rotating Kerr black holes are characterized by the dimensionless ratio τ{sub gap}/τ{sub emission} = O(1), where τ{sub gap} is the average time gap between the emissions of successive Hawking quanta and τ{sub emission} is the characteristic timescale required for an individual Hawking quantum to be emitted from the black hole. This relation implies that the Hawking cascade from rapidly-rotating black holes has an almost continuous character. Our results correct some inaccurate claims that recently appeared in the literature regarding the nature of the Hawking black-hole evaporation process. (orig.)

  14. Drug use among complete responders, partial responders and non-responders in a longitudinal survey of nonagenarians

    DEFF Research Database (Denmark)

    Wastesson, Jonas W; Rasmussen, Lotte; Oksuzyan, Anna

    2017-01-01

    PURPOSE: In observational studies, non-response can limit representativity and introduce bias. We aimed to investigate the longitudinal changes in the number of used drugs among complete responders, partial responders, and non-responders in a whole birth cohort of Danish nonagenarians participati...

  15. Como responder ao momento presente?

    Directory of Open Access Journals (Sweden)

    Maria Filomena Molder

    2013-12-01

    Full Text Available http://dx.doi.org/10.5007/1984-784X.2013v13n19p13 Foi com esta pergunta — já um efeito de um primeiro encontro entre Irene Pimentel e eu própria — que decidimos desafiar colegas, estudantes e funci­onários da nossa Faculdade, FCSH (Faculdade de Ciências Sociais e Huma­nas, de outras Faculdades da Universidade Nova de Lisboa, de outras Uni­versidades e todos os interessados em con­siderar e discutir em comum aquilo que se passava em Portugal e que no anúncio da Jornada de 6 de De­zembro de 2012 se descrevia como um “processo de desmantela­mento social, económico e cultural sem precedentes — pese embora tantas compara­ções, baseadas na premissa da ‘eterna repetição’ — e cujas consequências não param de exceder as previsões dos responsáveis por esse desmantelamento”. Acedendo com todo o empenho e gratidão ao convite que me foi dirigido por Humberto Brito para fazer uma resenha da Jornada a publicar no primeiro número de Forma de Vida (saúdo a revista e o título, decidi-me, no entanto, a pôr de lado a resenha, que sob a forma de “Editorial” será em breve publi­cada no blogue Responder ao Momento Presente, entre­tanto criado, conjuntamente com os textos escritos pelos nossos convidados, com as parti­cipações de pessoas que corresponderam ao nosso apelo e ainda com contri­bui­ções que se alargaram para lá da Jornada; a que se juntará uma gravação em video, também disponível no Youtube.   Texto publicado originalmente em Forma de Vida, Lisboa, n.1, fev. 2013. Agrade­cemos à autora por permitir a republicação neste número do Boletim. [N.E.

  16. Como responder ao momento presente?

    Directory of Open Access Journals (Sweden)

    Maria Filomena Molder

    2013-06-01

    Full Text Available Foi com esta pergunta — já um efeito de um primeiro encontro entre Irene Pimentel e eu própria — que decidimos desafiar colegas, estudantes e funci­onários da nossa Faculdade, FCSH (Faculdade de Ciências Sociais e Huma­nas, de outras Faculdades da Universidade Nova de Lisboa, de outras Uni­versidades e todos os interessados em con­siderar e discutir em comum aquilo que se passava em Portugal e que no anúncio da Jornada de 6 de De­zembro de 2012 se descrevia como um “processo de desmantela­mento social, económico e cultural sem precedentes — pese embora tantas compara­ções, baseadas na premissa da ‘eterna repetição’ — e cujas consequências não param de exceder as previsões dos responsáveis por esse desmantelamento”. Acedendo com todo o empenho e gratidão ao convite que me foi dirigido por Humberto Brito para fazer uma resenha da Jornada a publicar no primeiro número de Forma de Vida (saúdo a revista e o título, decidi-me, no entanto, a pôr de lado a resenha, que sob a forma de “Editorial” será em breve publi­cada no blogue Responder ao Momento Presente, entre­tanto criado, conjuntamente com os textos escritos pelos nossos convidados, com as parti­cipações de pessoas que corresponderam ao nosso apelo e ainda com contri­bui­ções que se alargaram para lá da Jornada; a que se juntará uma gravação em video, também disponível no Youtube. Texto publicado originalmente em Forma de Vida, Lisboa, n.1, fev. 2013. Agrade­cemos à autora por permitir a republicação neste número do Boletim. [N.E.

  17. Ultrafast Charge Transfer in Nickel Phthalocyanine Probed by Femtosecond Raman-Induced Kerr Effect Spectroscopy

    Science.gov (United States)

    2015-01-01

    The recently developed technique of femtosecond stimulated Raman spectroscopy, and its variant, femtosecond Raman-induced Kerr effect spectroscopy (FRIKES), offer access to ultrafast excited-state dynamics via structurally specific vibrational spectra. We have used FRIKES to study the photoexcitation dynamics of nickel(II) phthalocyanine with eight butoxy substituents, NiPc(OBu)8. NiPc(OBu)8 is reported to have a relatively long-lived ligand-to-metal charge-transfer (LMCT) state, an essential characteristic for efficient electron transfer in photocatalysis. Following photoexcitation, vibrational transitions in the FRIKES spectra, assignable to phthalocyanine ring modes, evolve on the femtosecond to picosecond time scales. Correlation of ring core size with the frequency of the ν10 (asymmetric C–N stretching) mode confirms the identity of the LMCT state, which has a ∼500 ps lifetime, as well as that of a precursor d-d excited state. An even earlier (∼0.2 ps) transient is observed and tentatively assigned to a higher-lying Jahn–Teller-active LMCT state. This study illustrates the power of FRIKES spectroscopy in elucidating ultrafast molecular dynamics. PMID:24841906

  18. Synchronous frequencies of extremal Kerr black holes: Resonances, scattering, and stability

    Science.gov (United States)

    Richartz, Maurício; Herdeiro, Carlos A. R.; Berti, Emanuele

    2017-08-01

    The characteristic damping times of the natural oscillations of a Kerr black hole become arbitrarily large as the extremal limit is approached. This behavior is associated with the so-called zero damped modes (ZDMs), and suggests that extremal black holes are characterized by quasinormal modes whose frequencies are purely real. Since these frequencies correspond to oscillations whose angular phase velocity matches the horizon angular velocity of the black hole, they are sometimes called "synchronous frequencies." Several authors have studied the ZDMs for near-extremal black holes. Recently, their correspondence to branch points of the Green's function of the wave equation was linked to the Aretakis instability of extremal black holes. Here we investigate the existence of ZDMs for extremal black holes, showing that these real-axis resonances of the field are unphysical as natural black hole oscillations: the corresponding frequency is always associated with a scattering mode. By analyzing the behavior of these modes near the event horizon we obtain new insight into the transition to extremality, including a simple way to understand the Aretakis instability.

  19. Kerr black holes with self-interacting scalar hair: hairier but not heavier

    CERN Document Server

    Herdeiro, Carlos A R; Rúnarsson, Helgi

    2015-01-01

    The maximal ADM mass for (mini-)boson stars (BSs) -- gravitating solitons of Einstein's gravity minimally coupled to a free, complex, mass $\\mu$, Klein-Gordon field -- is $M_{\\rm ADM}^{\\rm max}\\sim M_{Pl}^2/\\mu$. Adding quartic self-interactions to the scalar field theory, described by the Lagrangian $\\mathcal{L}_I=\\lambda |\\Psi|^4$, the maximal ADM mass becomes $M_{\\rm ADM}^{\\rm max}\\sim \\sqrt{\\lambda}M_{Pl}^3/\\mu^2$. Thus, for mini-BSs, astrophysically interesting masses require ultra-light scalar fields, whereas self-interacting BSs can reach such values for bosonic particles with Standard Model range masses. We investigate how these same self-interactions affect Kerr black holes with scalar hair (KBHsSH) [1], which can be regarded as (spinning) BSs in stationary equilibrium with a central horizon. Remarkably, whereas the ADM mass scales in the same way as for BSs, the \\textit{horizon mass} $M_H$ does not increases with the coupling $\\lambda$, and, for fixed $\\mu$, it is maximized at the "Hod point", corre...

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

    CERN Document Server

    Thornburg, Jonathan

    2016-01-01

    If a small "particle" of mass $\\mu M$ (with $\\mu \\ll 1$) orbits a black hole of mass $M$, the leading-order radiation-reaction effect is an $\\mathcal{O}(\\mu^2)$ "self-force" acting on the particle, with a corresponding $\\mathcal{O}(\\mu)$ "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 $e^{im\\phi}$ ("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 world...

  1. Linear mode stability of the Kerr-Newman black hole and its quasinormal modes.

    Science.gov (United States)

    Dias, Óscar J C; Godazgar, Mahdi; Santos, Jorge E

    2015-04-17

    We provide strong evidence that, up to 99.999% of extremality, Kerr-Newman black holes (KNBHs) are linear mode stable within Einstein-Maxwell theory. We derive and solve, numerically, a coupled system of two partial differential equations for two gauge invariant fields that describe the most general linear perturbations of a KNBH. We determine the quasinormal mode (QNM) spectrum of the KNBH as a function of its three parameters and find no unstable modes. In addition, we find that the lowest radial overtone QNMs that are connected continuously to the gravitational ℓ=m=2 Schwarzschild QNM dominate the spectrum for all values of the parameter space (m is the azimuthal number of the wave function and ℓ measures the number of nodes along the polar direction). Furthermore, the (lowest radial overtone) QNMs with ℓ=m approach Reω=mΩH(ext) and Imω=0 at extremality; this is a universal property for any field of arbitrary spin |s|≤2 propagating on a KNBH background (ω is the wave frequency and ΩH(ext) the black hole angular velocity at extremality). We compare our results with available perturbative results in the small charge or small rotation regimes and find good agreement.

  2. Modeling a circular equatorial test-particle in a Kerr spacetime

    CERN Document Server

    Carré, Jérôme

    2012-01-01

    Extreme Mass Ratio Inspirals (EMRIs) are one of the main gravitational wave (GW) sources for a future space detector, such as eLISA/NGO, and third generation ground-based detectors, like the Einstein Telescope. These systems present an interest both in astrophysics and fundamental physics. In order to make a high precision determination of their physical parameters, we need very accurate theoretical waveform models or templates. In the case of a circular equatorial orbit, the key stumbling block to the creation of these templates is the flux function of the GW. This function can be modeled either via very expensive numerical simulations, which then make the templates unusable for GW astronomy, or via some analytic approximation method such as a post-Newtonian approximation. This approximation is known to be asymptotically divergent and is only known up to 5.5PN order for the Schwarzschild case and to 4PN order for the Kerr case. A way to improve the convergence of the flux is to use re-summation methods. In t...

  3. Propagation of light in stratified media with optical Kerr nonlinearity under external electric fields

    Science.gov (United States)

    Kim, Sangbum; Kim, Kihong

    2011-10-01

    We analyze the controlled behavior of light propagation in a stratified Kerr-nonlinear medium with its photonic band structure tuned by applying an external electric field. The transmittance T of light is significantly influenced by nonlinear effects induced by both the external field and the incident light. Transmission resonance (T = 1) is induced by two mechanisms, band-edge resonance and gap soliton resonance. The T-Eex graph has two turning points and consists of three solution branches. One unstable branch is located between the turning points, and connected with a stable solution branch at each turning point. As Eex increases and then decreases through the region of the turning points, the transition between the stable states on different branches produces optical bistability and hysteresis. As input light intensity grows, the upper stable solution branch separates itself from the unstable branch at the turning point, and both branches extend down to the ordinate axis at Eex = 0. We have greatly enhanced single-envelope solitons on the upper stable branch from the separation point to the line of zero external field.

  4. Alternating stacking of ferromagnetic nanosheet and nanoparticle films: heteroassembly and magneto-optical Kerr effect

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Baoping, E-mail: baoping.jia@cczu.edu.cn [Changzhou University, School of Materials Science and Engineering (China); Zhang, Wei, E-mail: wei.zhang@unisa.edu.au [University of Tokyo, Department of Urban Engineering (Japan); Liu, Hui [Central South University, School of Metallurgy and Environment, National Engineering Research Center for Control & Treatment of Heavy Metal Pollution (China); Lin, Bencai; Ding, Jianning [Changzhou University, School of Materials Science and Engineering (China)

    2016-09-15

    Heterostructured multilayer films of two different nanocrystals have been successfully fabricated by layer-by-layer stacking of Ti{sub 0.8}Co{sub 0.2}O{sub 2} nanosheet and Fe{sub 3}O{sub 4} nanoparticle films. UV–Vis spectroscopy and AFM observation confirmed the successful alternating deposition in the multilayer buildup process. The average thickness of both Ti{sub 0.8}Co{sub 0.2}O{sub 2} nanosheet and Fe{sub 3}O{sub 4} nanoparticle layers was determined to be about 1.4–1.7 and 5 nm, which was in good agreement with TEM results. Magneto-optical Kerr effect measurements demonstrated that the heteroassemblies exhibit gigantic magnetic circular dichroism (MCD) (2 × 10{sup 4} deg/cm) at 320–360 nm, deriving from strong interlayer [Co{sup 2+}]t{sub 2g}–[Fe{sup 3+}]e{sub g} d–d charge transfer which was further confirmed by X-ray photoelectron spectroscopy. Their structure-dependent MCD showed high potential in rational design and construction of high-efficiency magneto-optical devices.

  5. Toward in Situ Measurement of the Density of Liquid Benzene Using Optical Kerr Effect Spectroscopy.

    Science.gov (United States)

    Bender, John S; Cohen, Samuel R; He, Xiaoxiao; Fourkas, John T; Coasne, Benoit

    2016-09-01

    The high-frequency portion of the optical Kerr effect (OKE) spectrum of benzene shifts to higher frequency with decreasing temperature at constant pressure. This behavior has been interpreted previously in terms of an increase in librational frequencies due to the decrease in free volume with liquid densification. However, decreasing temperature also provides less access to the more repulsive portion of the intermolecular potential, which would cause the blue edge of the spectrum to red-shift. To explore the relative importance of these phenomena, molecular dynamics simulations of benzene are used to isolate the effects of temperature and density on the spectrum. The simulations show that, at constant density, the high-frequency portion of the spectrum shifts to lower frequency with decreasing temperature. In contrast, at constant temperature, the high-frequency portion of the spectrum shifts to higher frequency with increasing density. These results indicate that density plays a greater role in determining the position of the blue edge of the low-frequency Raman spectrum of benzene than does temperature. Empirical fits show that the effects of changing density or temperature are similar in experimental and simulated OKE spectra. Furthermore, line-shape analysis of simulated spectra under isochoric and isothermal conditions shows that the effects of density and temperature are separable, suggesting that OKE spectroscopy is a viable technique for in situ measurement of the density of van der Waals liquids.

  6. Electromagnetic absorption and Kerr effect in quantum Hall ferromagnetic states of bilayer graphene

    Science.gov (United States)

    Côté, R.; Barrette, Manuel; Bouffard, Élie

    2015-09-01

    In a quantizing magnetic field, the chiral two-dimensional electron gas in Landau level N =0 of bilayer graphene goes through a series of phase transitions at integer filling factors ν ∈[-3 ,3 ] when the strength of an electric field applied perpendicularly to the layers is increased. At filling factor ν =3 , the electron gas can be described by a simple two-level system where layer and spin degrees of freedom are frozen. The gas then behaves as an orbital quantum Hall ferromagnet. A Coulomb-induced Dzyaloshinskii-Moriya term in the orbital pseudospin Hamiltonian is responsible for a series of transitions first to a Wigner crystal state and then to a spiral state as the electric field is increased. Both states have a nontrivial orbital pseudospin texture. In this work, we study how the phase diagram at ν =3 is modified by an electric field applied in the plane of the layers and then derive several experimental signatures of the uniform and nonuniform states in the phase diagram. In addition to the transport gap, we study the electromagnetic absorption and the Kerr rotation due to the excitations of the orbital pseudospin-wave modes in the broken-symmetry states.

  7. Magneto-optical Kerr effect studies of copper oxide and cobalt thin films

    Energy Technology Data Exchange (ETDEWEB)

    Fronk, Michael; Zahn, Dietrich R.T.; Salvan, Georgeta [Chemnitz University of Technology, Chemnitz (Germany); Mueller, Steve; Waechtler, Thomas; Schulz, Stefan E. [Fraunhofer Research Institution for Electronic Nano Systems ENAS, Chemnitz (Germany)

    2011-07-01

    Copper oxide is supposed to be a model material for tunnel-magneto-resistance (TMR) structures together with cobalt as ferromagnetic electrode. Therefore the magnetic properties of copper oxide itself are of interest and under investigation by various techniques. This contribution presents spectroscopic magneto-optical Kerr effect (MOKE) studies of thin films of this material. The films are produced by atomic layer deposition based on a Cu(I) {beta}-diketonate precursor at a process temperature of 120 C. The copper oxide films turned out to be magneto-optically active both in the spectral range around 2 eV and above 4 eV. Besides the experimental MOKE data the material-intrinsic magneto-optical Voigt constant extracted from optical model calculations are presented. Cobalt, the ferromagnetic counterpart in the TMR structures, was prepared by magnetron sputtering as thin films with different thicknesses. The Voigt constant of Co can be deduced from measurements on thick films (120 nm). It is investigated whether these data can be used to predict the magneto-optical response of thinner Co layers (10 nm).

  8. Polar magneto-optical Kerr effect instrument for 1-dimensional magnetic nanostructures

    Science.gov (United States)

    Pathak, Sachin; Sharma, Manish

    2014-01-01

    The magneto-optical Kerr effect (MOKE) is a powerful technique to investigate the magnetization behaviour in magnetic nanostructures. We describe the design of a polar MOKE instrument for investigating the magnetization variation in MOKE signal observed in the exciting regime where the size of the magnetic nanostructures is around 20-350 nm. In particular, when the magnetization of the sample is perpendicular to its plane (i.e., along the axis of a cylindrical nanowire) we use polar MOKE configuration. The sign and magnitude of the small rotation measured in the signal is found proportional to the magnetization and its direction. The MOKE measurements indicate that the hysteresis depends on the shape as well as the density of nanostructures formed. The instrument is sensitive enough to clearly indicate the effect of magneto-static interaction on shape of M-H loop. We have observed the coercive field of ˜269 G for cylindrical nanowire grown in anodic aluminium oxide template and ˜135 G for "pin" shaped nanowire grown in polycarbonate track etched template. The magnetization reversal measurements are intricate in the case of "pin" or "X" shaped nanostructures as seen from the loop. These typical MOKE measurements on the 1-dimensional (1-D) nanostructures explore the effect of magneto-static interaction between the nanostructures.

  9. Interactions of Airy beams, nonlinear accelerating beams, and induced solitons in Kerr and saturable nonlinear media.

    Science.gov (United States)

    Zhang, Yiqi; Belić, Milivoj R; Zheng, Huaibin; Chen, Haixia; Li, Changbiao; Li, Yuanyuan; Zhang, Yanpeng

    2014-03-24

    We investigate numerically interactions between two in-phase or out-of-phase Airy beams and nonlinear accelerating beams in Kerr and saturable nonlinear media in one transverse dimension. We discuss different cases in which the beams with different intensities are launched into the medium, but accelerate in opposite directions. Since both the Airy beams and nonlinear accelerating beams possess infinite oscillating tails, we discuss interactions between truncated beams, with finite energies. During interactions we see solitons and soliton pairs generated that are not accelerating. In general, the higher the intensities of interacting beams, the easier to form solitons; when the intensities are small enough, no solitons are generated. Upon adjusting the interval between the launched beams, their interaction exhibits different properties. If the interval is large relative to the width of the first lobes, the generated soliton pairs just propagate individually and do not interact much. However, if the interval is comparable to the widths of the maximum lobes, the pairs strongly interact and display varied behavior.

  10. Soft-x-ray magneto-optical Kerr effect and element-specific hysteresis measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kortright, J.B.; Rice, M. [Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    Interest in the utilization of x-ray magneto-optical properties to provide element-specific magnetic information, combined with recent development of tunable linear polarizers for spectroscopic polarization measurement, have led the authors to the study of magneto-optical rotation (MOR) near core levels of magnetic atoms in magnetic multilayer and alloy films. Their initial observation of Faraday rotation (in transmission) demonstrated that for Fe MOR is easily measured and is larger at its L{sub 3} resonance than in the near-visible spectral regions. This work also demonstrated that the spectroscopic behavior of the MOR signal in transmission, resulting from the differential reaction of left- and right-circular components of a linearly polarized beam, is related to the magnetic circular dichroism (MCD), or differential absorption, as expected by a Kramers-Kronig transformation. Thus MCD measurements using circular polarization and MOR measurements using linear polarization can provide complementary, and in some cases equivalent, information. On beamline 6.3.2 the authors have begun to investigate soft x-ray MOR in the reflection geometry, the x-ray magneto-optic Kerr effect (XMOKE). Early measurements have demonstrated the ability to measure element-specific hysteresis loops and large rotations compared to analogous near-visible measurements. The authors are investigating the spectral dependence of the XMOKE signal, and have initiated systematic materials studies of sputter-deposited films of Fe, Fe{sub x}Cr{sub 1{minus}x} alloys, and Fe/Cr multilayers.

  11. Geodesic synchrotron radiation in the Kerr geometry by the method of asymptotically factorized Green's functions

    Science.gov (United States)

    Chrzanowski, P. L.; Misner, C. W.

    1974-01-01

    The scalar, electromagnetic, and gravitational geodesic-synchrotron-radiation (GSR) spectra are determined for the case of a test particle moving on a highly relativistic circular orbit about a rotating (Kerr) black hole. It is found that the spectral shape depends only weakly on the value of the angular-momentum parameter (a/M) of the black hole, but the total radiated power drops unexpectedly for a value of at least 0.95 and vanishes as the value approaches unity. A spin-dependent factor (involving the inner product of the polarization of a radiated quantum with the source) is isolated to explain the dependence of the spectral shape on the spin of the radiated field. Although the scalar wave equation is solved by separation of variables, this procedure is avoided for the vector and tensor cases by postulating a sum-over-states expansion for the Green's function similar to that found to hold in the scalar case. The terms in this sum, significant for GSR, can then be evaluated in the geometric-optics approximation without requiring the use of vector or tensor spherical harmonics.

  12. Ultrasensitive transverse magneto-optical Kerr effect measurements by means of effective polarization change detection

    Science.gov (United States)

    Oblak, E.; Riego, P.; Fallarino, L.; Martínez-de-Guerenu, A.; Arizti, F.; Berger, A.

    2017-06-01

    We perform a detailed comparative study of conventional transverse magneto-optical Kerr effect (T-MOKE) measurements and a methodology that utilizes an effective polarization detection scheme for mixed s- and p-polarized incoming light. To test the ultimate sensitivity of both methods, we also design a series of specialized samples in which the T-MOKE signal of a Co-film is artificially reduced by means of a Ag overcoat of varying thickness. We find that the effective polarization detection scheme leads to a more than 30-fold increase of the T-MOKE signal and signal-to-noise ratio, even under general operation conditions which were not individually optimized. This allowed for the observation of T-MOKE hysteresis loops of Co-films that were buried under 80 nm of Ag, for which the MOKE signal was only 1/600 of that for an uncoated Co-film. In comparison, conventional T-MOKE measurements did not succeed for Ag overcoats thicker than 40 nm.

  13. Application of magneto-optical Kerr effect to first-order reversal curve measurements.

    Science.gov (United States)

    Gräfe, Joachim; Schmidt, Mathias; Audehm, Patrick; Schütz, Gisela; Goering, Eberhard

    2014-02-01

    First-order reversal curves (FORC) are a powerful method for magnetic sample characterization, separating all magnetic states of an investigated system according to their coercivity and internal magnetic interactions. A major drawback of using measurement techniques like VSM or SQUID, typically applied for FORC acquisition, is the long measurement time, limiting the resolution and the number of measurements due to time constraints. Faster techniques like MOKE result in problems regarding measurement stability over the curse of the acquisition of many minor loops, due to drift and non-absolute magnetization values. Here, we present an approach using a specialized field shape providing two anchor points for each minor loop for applying the magneto-optical Kerr effect (MOKE) technique to FORC measurements. This results in a high field resolution while keeping the total acquisition time to only a few minutes. MOKE FORC measurements are exemplarily applied to a simple permalloy film, an exchange-bias system, and a Gd/Fe multilayer system with perpendicular magnetic anisotropy, showcasing the versatility of the method.

  14. Magneto optical Kerr effect study of close packed arrays of cobalt nanostructure

    Science.gov (United States)

    Gu, Jiyeong; Ngo, Kevin

    Nanopatterned cobalt thin films were fabricated on silicon substrate using nanosphere lithography. Nanospheres of different diameters, 200 nm, 600 nm, and 900 nm, were used to pattern the surface of the cobalt thin films. The surface morphology of thin films were characterized using high powered optical microscope, scanning electron microscope and the atomic force microscope. The nanopatterned thin film is highly uniform at macroscopic scale while several distinct nanostructure morphologies are observed at microscopic scale. Magnetic switching behavior was investigated by the magneto optical Kerr effect (MOKE) measurement. Modification to the surface of cobalt thin film was found to extensively change its magnetization behavior due to influence of the shape anisotropy and magnetic domain wall. Coercivity increased in nanopatterned cobalt thin film as compared to the continuous thin film. Nanostructure sample using nanospheres template less than 600 nm was additionally found to show a various features in the MOKE hysteresis loops including the multi-steps, multi-loops and shearing features. The multi-steps and multi-loops behaviors are more prominent as the size of nanosphere is reduced.

  15. Magnetization switching behavior of exchange-coupled bilayer nanodots characterized by magneto-optical Kerr effect

    Science.gov (United States)

    Zhou, W.; Seki, T.; Takanashi, K.

    2017-09-01

    We investigated the magnetization switching behavior of exchange-coupled bilayer nanodots consisting of a soft magnetic Ni81Fe19 (permalloy; Py) layer and a perpendicularly magnetized L10-FePt layer by measuring the polar magneto-optical Kerr effect (MOKE). A MOKE system having a 2-μm-diameter laser spot was used, which detected the signal from around 20 nanodots of 200 nm in diameter. The measured polar MOKE loops exhibited a two-step behavior attributable to each magnetization reversal process of the Py and L10-FePt layers, allowing us to evaluate the switching field ( Hsw ) of L10-FePt from the MOKE loop. Under the application of both a static magnetic field and an rf magnetic field ( hrf ), the nanodots showed a clear Hsw reduction with characteristic hrf frequency dependence. This Hsw reduction is well interpreted as a behavior of spin wave-assisted magnetization switching. We also discuss the influence of the Py layer thickness on spin wave-assisted Hsw reduction.

  16. Note: A time-resolved Kerr rotation system with a rotatable in-plane magnetic field.

    Science.gov (United States)

    Qian, Xuan; Gu, Xiaofang; Ji, Yang

    2010-10-01

    A time-resolved Kerr rotation system with a rotatable in-plane magnetic field has been constructed to study anisotropic spin relaxation of electrons in semiconductors. A permanent magnet magic ring is placed on top of a motor-driven rotation stage (RS) to create the rotatable in-plane magnetic field. The RS is placed on a second translation stage to vary the local magnetic field around a sample. The in-plane magnetic field in such a system varies from 0.05 to 0.95 T, with full-round 360° rotatablity, thus offering a convenient and low-cost way to study the anisotropy of spin dynamics in semiconductors. Its performance was demonstrated via measurement of the anisotropy of the spin dephasing time (SDT) of electrons in a two-dimensional electron system embedded in a GaAs/Al(0.35)Ga(0.65)As heterostructure. The SDT with B∥[110] was observed to be 10% larger than that with B∥[110], consistent with the results of others, which was measured via rotating sample.

  17. Electrooptic Kerr effect of porphyrin H-aggregates in polymer films: Polymer specific spectral blue shift

    Science.gov (United States)

    Suzuki, Masaya; Nakata, Kazuaki; Kuroda, Reiko; Kobayashi, Takayoshi; Tokunaga, Eiji

    2016-05-01

    J- and H-aggregates of porphyrin molecules (TPPS4) in spin-coated polymer films have been studied by electroabsorption and circular dichroism (CD) spectroscopy. A spectral blue shift of the H-band due to the electrooptic Kerr effect was observed for the first time. This occurs only for a polyvinylpyrrolidone (PVP) film, with negligibly small spectral shift observed in polyvinyl alcohol (PVA), polyvinyl sulfate (PVS), and polyacrylic acid (PAA) films, in contrast to the red shift of the J-band which is commonly observed for any host polymers. Accordingly, the CD activity in both of J- and H-bands is more enhanced in PVP films than in PVA films. The mechanism of the blue and red shifts of the respective H- and J-bands is discussed by invoking a helical structure in micro-aggregates, which is compatible with the CD spectra, based on the molecular rearrangement model. It is proved that blue- and red-shifts occur evenly to cancel each other in the H-band if a simple helical structure is assumed, in good agreement with no spectral shifts in the H-band in PVA, PVS, and PAA films.

  18. Quantum Process Tomography of an Optically-Controlled Kerr Non-linearity

    Science.gov (United States)

    Kupchak, Connor; Rind, Samuel; Jordaan, Bertus; Figueroa, Eden

    2015-11-01

    Any optical quantum information processing machine would be comprised of fully-characterized constituent devices for both single state manipulations and tasks involving the interaction between multiple quantum optical states. Ideally for the latter, would be an apparatus capable of deterministic optical phase shifts that operate on input quantum states with the action mediated solely by auxiliary signal fields. Here we present the complete experimental characterization of a system designed for optically controlled phase shifts acting on single-photon level probe coherent states. Our setup is based on a warm vapor of rubidium atoms under the conditions of electromagnetically induced transparency with its dispersion properties modified through the use of an optically triggered N-type Kerr non-linearity. We fully characterize the performance of our device by sending in a set of input probe states and measuring the corresponding output via time-domain homodyne tomography and subsequently performing the technique of coherent state quantum process tomography. This method provides us with the precise knowledge of how our optical phase shift will modify any arbitrary input quantum state engineered in the mode of the reconstruction.

  19. Chirped soliton solutions for the generalized nonlinear Schrödinger equation with polynomial nonlinearity and non-Kerr terms of arbitrary order

    Science.gov (United States)

    Triki, Houria; Porsezian, K.; Grelu, Philippe

    2016-07-01

    A generalized nonlinear Schrödinger equation with polynomial Kerr nonlinearity and non-Kerr terms of an arbitrarily higher order is investigated. This model can be applied to the femtosecond pulse propagation in highly-nonlinear optical media. We introduce a new chirping ansatz given as an expansion in powers of intensity of the light pulse and obtain both linear and nonlinear chirp contributions associated with propagating optical pulses. By taking the cubic-quintic-septic-nonic nonlinear Schrödinger (NLS) equation with seventh-order non-Kerr terms as an example for the generalized equation with Kerr and non-Kerr nonlinearity of arbitrary order, we derive families of chirped soliton solutions under certain parametric conditions. The solutions comprise bright, kink, anti-kink, and fractional-transform soliton solutions. In addition, we found the exact soliton solution for the model under consideration using a new ansatz. The parametric conditions for the existence of chirped solitons are also reported.

  20. Differences in change in coping styles between good responders, moderate responders and non-responders to pulmonary rehabilitation.

    Science.gov (United States)

    Stoilkova-Hartmann, Ana; Janssen, Daisy J A; Franssen, Frits M E; Wouters, Emiel F M

    2015-12-01

    Pulmonary rehabilitation (PR) improves exercise tolerance and health status in patients with chronic obstructive pulmonary disease (COPD). Data on the effects of PR on coping styles are limited. Aim of the present study was to compare changes in coping styles between patients who had a good, moderate and no improvement in either exercise tolerance or health status after PR. Coping styles of 439 COPD patients undergoing PR were assessed by the Utrecht Coping List (UCL) at baseline and after PR. Patients' pulmonary function, six-minute walking distance (6MWD), St. George's Respiratory Questionnaire (SGRQ) and Hospital Anxiety and Depression Scale (HADS-A and HADS-D) were recorded. Good, moderate and non-responders were defined on the basis of minimally clinically important difference (MCID) for SGRQ total score and/or 6MWD. Overall, 54.0% of the patients fulfilled the criteria for good responders, while 22.1% were moderate responders. Change in passive reaction pattern coping style differed significantly between good responders and non-responders following PR (p coping styles after PR occurred among the good responders, whereas the majority of moderate responders' and non-responders' coping styles were not significantly influenced by PR. Good responders decreased their passive reaction pattern coping style in contrast to non-responders after PR. In general, PR did not change the coping among moderate and non-responders. Further research is warranted to determine whether including interventions targeting coping styles may modify coping behaviour of COPD patients, as well as improvement in exercise tolerance or health status after PR. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Algorithms and Programs for Strong Gravitational Lensing In Kerr Space-time Including Polarization

    Science.gov (United States)

    Chen, Bin; Kantowski, Ronald; Dai, Xinyu; Baron, Eddie; Maddumage, Prasad

    2015-05-01

    Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python.

  2. ALGORITHMS AND PROGRAMS FOR STRONG GRAVITATIONAL LENSING IN KERR SPACE-TIME INCLUDING POLARIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Bin; Maddumage, Prasad [Research Computing Center, Department of Scientific Computing, Florida State University, Tallahassee, FL 32306 (United States); Kantowski, Ronald; Dai, Xinyu; Baron, Eddie, E-mail: bchen3@fsu.edu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)

    2015-05-15

    Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python.

  3. Simulation of ultrashort pulse induced plasma generation and interaction within the bulk of transparent Kerr media

    Science.gov (United States)

    Arnold, C. L.; Ertmer, W.; Lubatschowski, H.

    2006-02-01

    Recently ultrashort laser pulses became most important for micro structuring and biomedical applications such as refractive surgery. Ultrashort laser pulses tightly focused to a small spot easily provide intensity sufficient to induce nonlinear ionization. A plasma is generated and heated in the focus resulting in optical breakdown. The energy deposited in the plasma and the mechanical effects subsequent to optical breakdown are utilized by modern applications of ultrashort laser pulses to induce controlled highly reproducible material alteration. A model including both nonlinear pulse propagation and plasma generation is introduced to numerically investigate the interaction of ultrashort laser pulses with the self-induced plasma in the vicinity of the focus. The numerical code is based on a (3+1)-dimensional nonlinear Schroedinger equation describing the pulse propagation. A multi rate equation model recently published by B. Rethfeld is used to simultaneously calculate the generation of free electrons. It is the first numerically simple approach to describe nonlinear ionization that allows a non static energy distribution of free electrons in the conduction band. The code is applicable to any transparent Kerr medium, whose linear and nonlinear optical parameters are known. Numerical calculations based on this model are used to understand the dependence between the size, the geometry and the free electron density of ultrashort laser pulse induced optical breakdown plasmas in various focusing geometries. The code enables to use arbitrary initial conditions for the laser field in the focus. More realistic focusing scenarios than the simple assumption of focused gaussian beams can be taken into account. Nonlinear side effects, such as streak formation occurring in addition to optical breakdown during ultrashort pulse refractive eye surgeries can be numerically investigated.

  4. Off-diagonal deformations of Kerr metrics and black ellipsoids in heterotic supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Vacaru, Sergiu I. [Quantum Gravity Research, Topanga, CA (United States); University ' ' Al. I. Cuza' ' , Project IDEI, Iasi (Romania); Irwin, Klee [Quantum Gravity Research, Topanga, CA (United States)

    2017-01-15

    Geometric methods for constructing exact solutions of equations of motion with first order α{sup '} corrections to the heterotic supergravity action implying a nontrivial Yang-Mills sector and six-dimensional, 6-d, almost-Kaehler internal spaces are studied. In 10-d spacetimes, general parametrizations for generic off-diagonal metrics, nonlinear and linear connections, and matter sources, when the equations of motion decouple in very general forms are considered. This allows us to construct a variety of exact solutions when the coefficients of fundamental geometric/physical objects depend on all higher-dimensional spacetime coordinates via corresponding classes of generating and integration functions, generalized effective sources and integration constants. Such generalized solutions are determined by generic off-diagonal metrics and nonlinear and/or linear connections; in particular, as configurations which are warped/compactified to lower dimensions and for Levi-Civita connections. The corresponding metrics can have (non-) Killing and/or Lie algebra symmetries and/or describe (1+2)-d and/or (1+3)-d domain wall configurations, with possible warping nearly almost-Kaehler manifolds, with gravitational and gauge instantons for nonlinear vacuum configurations and effective polarizations of cosmological and interaction constants encoding string gravity effects. A series of examples of exact solutions describing generic off-diagonal supergravity modifications to black hole/ellipsoid and solitonic configurations are provided and analyzed. We prove that it is possible to reproduce the Kerr and other type black solutions in general relativity (with certain types of string corrections) in the 4-d case and to generalize the solutions to non-vacuum configurations in (super-) gravity/string theories. (orig.)

  5. 24 CFR 103.202 - Notification of respondent; joinder of additional or substitute respondents.

    Science.gov (United States)

    2010-04-01

    ... of additional or substitute respondents. 103.202 Section 103.202 Housing and Urban Development... Procedures § 103.202 Notification of respondent; joinder of additional or substitute respondents. (a) Within... may be joined as an additional or substitute respondent by service of a notice on the person under...

  6. Synthesis of amino acid block-copolymer imprinted chiral mesoporous silica and its acoustically-induced optical Kerr effects

    Energy Technology Data Exchange (ETDEWEB)

    Paik, Pradip, E-mail: pradip.paik@gmail.com [Department of Materials Engineering and Nanoscience and Technology, School of Engineering Sciences and Technology, University of Hyderabad, Central University P.O., Gachibowli, Hyderabad 500046, AP (India); Institute for Nanotechnology and Advanced Materials, Department of Chemistry, Bar-Ilan University, 52900 (Israel); Mastai, Yitzhak, E-mail: mastai@mail.biu.ac.il [Institute for Nanotechnology and Advanced Materials, Department of Chemistry, Bar-Ilan University, 52900 (Israel); Kityk, Iwan; Rakus, Piort [Electrical Engineering Department, Czestochowa University Technology, Armii Krajowej 17, Czestochowa (Poland); Gedanken, Aharon, E-mail: gedanken@mail.biu.ac.il [Institute for Nanotechnology and Advanced Materials, Department of Chemistry, Bar-Ilan University, 52900 (Israel)

    2012-08-15

    Chiral mesoporous SiO{sub 2} (CMS) have been synthesized and studied the Acoustically-Induced Optical Kerr Effects (AIOKE) and the results have been compared with non-chiral mesoporous silica. The CMS with controllable pore sizes (of {approx}3 nm) and high surface areas of ca. 650 m{sup 2}g{sup -1} was synthesized by mimicking the intrinsic chirality of the amino acid block copolymers. The chiral mesoporous materials were characterized through HRTEM, BET, small-angle XRD, {sup 29}Si-NMR and circular dichroism. AIOKE measurements have been performed using an Er:glass 20 ns laser with a 10 Hz frequency repetition. The optimal AIOKE results of the CMS were achieved for 9.7% of the chromophore in the matrices. We found that the AIOKE for the CMS mimicked with chiral block copolymers is quite high compared to the non-chiral SiO{sub 2}. A difference in AIOKE for these two compounds is observed, enabling CMS that can be used for the design of the acoustically-operated quantum electronic devices. - Graphical abstract: Novel chiral mesoporous SiO{sub 2} (CMS) is showing Acoustically-Induced Optical Kerr Effects (AIOKE). Different in AIOKE of two mesoporous materials is observed, enabling CMS can be used for the design of the acoustically-operated quantum electronic devices.Highlights: Black-Right-Pointing-Pointer Chiral mesoporous SiO{sub 2} (CMS) synthesized with amino acid block copolymers. Black-Right-Pointing-Pointer The Acoustically-induced Optical Kerr Effects (AIOKE) of chiral mesoporous SiO{sub 2} studied. Black-Right-Pointing-Pointer AIOKE very high for CMS compared to non chiral SiO{sub 2}. Black-Right-Pointing-Pointer CMS can be used in acoustically-operated quantum electronic devices.

  7. Diode-pumped Kerr-lens mode-locked Yb:LYSO laser with 61fs pulse duration.

    Science.gov (United States)

    Tian, Wenlong; Wang, Zhaohua; Wei, Long; Peng, Yingnan; Zhang, Jinwei; Zhu, Zheng; Zhu, Jiangfeng; Han, Hainian; Jia, Yulei; Zheng, Lihe; Xu, Jun; Wei, Zhiyi

    2014-08-11

    A stable diode pumped Kerr-lens mode-locked (KLM) Yb:LuYSiO5 (Yb:LYSO) laser of generating 61 fs pulses at a central wavelength of 1055.4 nm is experimentally demonstrated. This is, to the best of our knowledge, the first demonstration of femtosecond KLM operation in Yb:LYSO laser, and it is believed that 61 fs is the shortest pulse duration ever produced from an Yb-doped orthosilicate laser. The average output power of the mode-locked laser is 40 mW and the repetition rate is 113 MHz.

  8. Kerr-Lens Mode-Locked Femtosecond Yb:GdYSiO5 Laser Directly Pumped by a Laser Diode

    Directory of Open Access Journals (Sweden)

    Jiangfeng Zhu

    2015-10-01

    Full Text Available We demonstrate the first Kerr-lens mode-locked operation in a diode-pumped Yb:GdYSiO5 oscillator. Under a diode pump power of 5 W, 141 fs pulses with an average power of 237 mW were obtained at a repetition rate of 118 MHz. The central wavelength was at 1094 nm with a bandwidth of 10.1 nm. Shorter pulses were obtained by adjusting the cavity to operate at a shorter wavelength, resulting in 55 fs pulse duration at the central wavelength of 1054 nm with a bandwidth of 23.5 nm.

  9. Deterministic distribution of four-photon Dicke state over an arbitrary collective-noise channel with cross-Kerr nonlinearity.

    Science.gov (United States)

    Wang, Mei-Yu; Yan, Feng-Li; Gao, Ting

    2016-07-14

    We present two deterministic quantum entanglement distribution protocols for a four-photon Dicke polarization entangled state resorting to the frequency and spatial degrees of freedom, which are immune to an arbitrary collective-noise channel. Both of the protocols adopt the X homodyne measurement based on the cross-Kerr nonlinearity to complete the task of the single-photon detection with nearly unit probability in principle. After the four receivers share the photons, they add some local unitary operations to obtain a standard four-photon Dicke polarization entangled state.

  10. Theoretical Investigation of Light Transmission in a Slab Cavity via Kerr Nonlinearity of Carbon Nanotube Quantum Dot Nanostructure

    Science.gov (United States)

    Solookinejad, Gh.; Jabbari, M.; Sangachin, E. Ahmadi; Asadpour, S. H.

    2018-01-01

    In this paper, we discuss the transmission properties of weak probe laser field propagate through slab cavity with defect layer of carbon-nanotube quantum dot (CNT-QD) nanostructure. We show that due to spin-orbit coupling, the double electromagnetically induced transparency (EIT) windows appear and the giant Kerr nonlinearity of the intracavity medium can lead to manipulating of transmission coefficient of weak probe light. The thickness effect of defect layer medium has also been analyzed on transmission properties of probe laser field. Our proposed model may be useful for integrated photonics devices based on CNT-QD for applications in all-optical systems which require multiple EIT effect.

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

    Science.gov (United States)

    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

  12. Oscillatory spin polarization and magneto-optical Kerr effect in Fe₃O₄ thin films on GaAs(001).

    Science.gov (United States)

    Li, Yan; Han, Wei; Swartz, A G; Pi, K; Wong, J J I; Mack, S; Awschalom, D D; Kawakami, R K

    2010-10-15

    The spin dependent properties of epitaxial Fe₃O₄ thin films on GaAs(001) are studied by the ferromagnetic proximity polarization (FPP) effect and magneto-optical Kerr effect (MOKE). Both FPP and MOKE show oscillations with respect to Fe₃O₄ film thickness, and the oscillations are large enough to induce repeated sign reversals. We attribute the oscillatory behavior to spin-polarized quantum well states forming in the Fe₃O₄ film. Quantum confinement of the t(2g) states near the Fermi level provides an explanation for the similar thickness dependences of the FPP and MOKE oscillations.

  13. Theoretical Investigation of Light Transmission in a Slab Cavity via Kerr Nonlinearity of Carbon Nanotube Quantum Dot Nanostructure

    Science.gov (United States)

    Solookinejad, Gh.; Jabbari, M.; Sangachin, E. Ahmadi; Asadpour, S. H.

    2017-09-01

    In this paper, we discuss the transmission properties of weak probe laser field propagate through slab cavity with defect layer of carbon-nanotube quantum dot (CNT-QD) nanostructure. We show that due to spin-orbit coupling, the double electromagnetically induced transparency (EIT) windows appear and the giant Kerr nonlinearity of the intracavity medium can lead to manipulating of transmission coefficient of weak probe light. The thickness effect of defect layer medium has also been analyzed on transmission properties of probe laser field. Our proposed model may be useful for integrated photonics devices based on CNT-QD for applications in all-optical systems which require multiple EIT effect.

  14. 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

    Science.gov (United States)

    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

  15. Rapid Prototyping

    Science.gov (United States)

    1999-01-01

    Javelin, a Lone Peak Engineering Inc. Company has introduced the SteamRoller(TM) System as a commercial product. The system was designed by Javelin during a Phase II NASA funded small commercial product. The purpose of the invention was to allow automated-feed of flexible ceramic tapes to the Laminated Object Manufacturing rapid prototyping equipment. The ceramic material that Javelin was working with during the Phase II project is silicon nitride. This engineered ceramic material is of interest for space-based component.

  16. Socio Economic Assessment of Urban Forestry Respondents ...

    African Journals Online (AJOL)

    The paper investigates the socio economic assessment of urban forestry respondents' income in Okitipupa, Nigeria. Data were collected using structured questionnaires and these were administered to 200 urban forestry respondents. Data were collected on socioeconomic characteristics viz: age, gender, marital status, ...

  17. Empathy-related responding and prosocial behaviour.

    Science.gov (United States)

    Eisenberg, Nancy

    2007-01-01

    In this paper I differentiate among empathy, sympathy and personal distress and discuss the central role of empathy-related responding in positive (including moral) development. Empathy-related responding, especially sympathy, is likely an important source of prosocial, other-oriented motivation. In fact, empathy-related responding, especially sympathy, has been associated with prosocial behaviour (voluntary behaviour intended to benefit another, e.g. helping, sharing); this relation has been obtained for both specific instances of empathy-related responding and for dispositional sympathy. In addition, sympathy (or sometimes empathy) has been linked to relatively high levels of moral reasoning and social competence, and to low levels of aggression and antisocial behaviour. In my talk, I will review research on the relation of empathy-related responding to prosocial behaviour, the consistency of costly prosocial behaviour over time and the possible role of sympathy in its consistency, and the relation of empathy-related responding to moral reasoning, antisocial behaviour and social competence. Examples of research, including longitudinal research in our laboratory, are provided to illustrate these relations. Because of its close relations to social and prosocial responding, an understanding of empathy-related responding contributes to efforts to promote children's moral development.

  18. Kerr nonlinearity compensation in a 5×28-GBd PDM 16-QAM WDM system using fiber-based optical phase conjugation

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Sackey, I.; Elschner, R.

    2014-01-01

    Effective Kerr nonlinearity mitigation is experimentally demonstrated using optical phase conjugation in the middle of an 800-km dispersion-compensated link for a 5-channel WDM 28-GBd PDM 16-QAM signal. A Q-factor improvement of 0.9 dB over no mitigation allows a BER......Effective Kerr nonlinearity mitigation is experimentally demonstrated using optical phase conjugation in the middle of an 800-km dispersion-compensated link for a 5-channel WDM 28-GBd PDM 16-QAM signal. A Q-factor improvement of 0.9 dB over no mitigation allows a BER...

  19. Kerr/CFT correspondence in a 4D extremal rotating regular black hole with a non-linear magnetic monopole

    Science.gov (United States)

    Takeuchi, Shingo

    2017-08-01

    We carry out the Kerr/CFT correspondence in a four-dimensional extremal rotating regular black hole with a non-linear magnetic monopole (NLMM). One problem in this study would be whether our geometry can be a solution or not. We search for the way making our rotating geometry into a solution based on the fact that the Schwarzschild regular geometry can be a solution. However, in the attempt to extend the Schwarzschild case that we can naturally consider, it turns out that it is impossible to construct a model in which our geometry can be a exact solution. We manage this problem by making use of the fact that our geometry can be a solution approximately in the whole space-time except for the black hole's core region. As a next problem, it turns out that the equation to obtain the horizon radii is given by a fifth-order equation due to the regularization effect. We overcome this problem by treating the regularization effect perturbatively. As a result, we can obtain the near-horizon extremal Kerr (NHEK) geometry with the correction of the regularization effect. Once obtaining the NHEK geometry, we can obtain the central charge and the Frolov-Thorne temperature in the dual CFT. Using these, we compute its entropy through the Cardy formula, which agrees with the one computed from the Bekenstein-Hawking entropy.

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

    Science.gov (United States)

    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.

  1. Testing the Kerr nature of black hole candidates using iron line reverberation mapping in the Cardoso-Pani-Rico framework

    Science.gov (United States)

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

    2016-06-01

    The iron K α line commonly observed in the x-ray spectrum of black hole candidates is produced by x-ray fluorescence of the inner accretion disk. This line can potentially be quite a powerful tool to probe the spacetime geometry around these objects and test the Kerr black hole hypothesis. In a previous paper, we studied the ability to constrain possible deviations from the Kerr solution from the standard time-integrated iron line spectrum within the Cardoso-Pani-Rico framework. In the present work, we expand on that study and consider iron line reverberation mapping in the Cardoso-Pani-Rico framework. That is, we consider the time evolution of the iron line profile in response to fluctuations in the x-ray primary source. Our simulations clearly show that the time information in reverberation mapping can better constrain the background metric than the time-integrated approach, and this is true, notably, for the deformation parameter ɛ3r, which is only weakly informed by a time-integrated observation.

  2. High resolution in situ magneto-optic Kerr effect and scanning tunneling microscopy setup with all optical components in UHV.

    Science.gov (United States)

    Lehnert, A; Buluschek, P; Weiss, N; Giesecke, J; Treier, M; Rusponi, S; Brune, H

    2009-02-01

    A surface magneto-optic Kerr effect (MOKE) setup fully integrated in an ultrahigh vacuum chamber is presented. The system has been designed to combine in situ MOKE and scanning tunneling microscopy. Magnetic fields up to 0.3 T can be applied at any angle in the transverse plane allowing the study of in-plane and out-of-plane magnetization. The setup performance is demonstrated for a continuous film of 0.9 monolayers (ML) Co/Rh(111) with in-plane easy axis and for a superlattice of nanometric double layer Co islands on Au(11,12,12) with out-of-plane easy axis. For Co/Au(11,12,12) we demonstrate that the magnetic anisotropy energies deduced from thermally induced magnetization reversal and from applying a torque onto the magnetization by turning the field are the same. For the presented setup we establish a coverage detection limit of 0.5 ML for transverse and 0.1 ML for polar MOKE. For island superlattices with the density of Co/Au(11,12,12), the latter limit corresponds to islands composed of about 50 atoms. The detection limit can be further reduced when optimizing the MOKE setup for either one of the two Kerr configurations.

  3. Criticality Safety Basics for INL Emergency Responders

    Energy Technology Data Exchange (ETDEWEB)

    Valerie L. Putman

    2012-08-01

    This document is a modular self-study guide about criticality safety principles for Idaho National Laboratory emergency responders. This guide provides basic criticality safety information for people who, in response to an emergency, might enter an area that contains much fissionable (or fissile) material. The information should help responders understand unique factors that might be important in responding to a criticality accident or in preventing a criticality accident while responding to a different emergency.

    This study guide specifically supplements web-based training for firefighters (0INL1226) and includes information for other Idaho National Laboratory first responders. However, the guide audience also includes other first responders such as radiological control personnel.

    For interested readers, this guide includes clearly marked additional information that will not be included on tests. The additional information includes historical examples (Been there. Done that.), as well as facts and more in-depth information (Did you know …).

    INL criticality safety personnel revise this guide as needed to reflect program changes, user requests, and better information. Revision 0, issued May 2007, established the basic text. Revision 1 incorporates operation, program, and training changes implemented since 2007. Revision 1 increases focus on first responders because later responders are more likely to have more assistance and guidance from facility personnel and subject matter experts. Revision 1 also completely reorganized the training to better emphasize physical concepts behind the criticality controls that help keep emergency responders safe. The changes are based on and consistent with changes made to course 0INL1226.

  4. Responder Technology Alert Monthly (January 2015)

    Energy Technology Data Exchange (ETDEWEB)

    Upton, Jaki F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Stein, Steven L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-02-01

    As part of technology foraging for the Responder Technology Alliance, established by the Department of Homeland Science and Technologies First Responders Group, this report summarizes technologies that are relevant in the area of “wearables,” with the potential for use by first responders. The content was collected over the previous month(s) and reproduced from a general Internet search using the term wearables. Additional information is available at the websites provided. This report is not meant to be an exhaustive list nor an endorsement of any technology described herein. Rather, it is meant to provide useful information about current developments in the areas wearable technology.

  5. Responder Technology Alert Monthly (December 2014)

    Energy Technology Data Exchange (ETDEWEB)

    Upton, Jaki F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Stein, Steven L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-02-13

    As part of technology foraging for the Responder Technology Alliance, established by the Department of Homeland Science and Technologies First Responders Group, this report summarizes technologies that are relevant in the area of “wearables,” with the potential for use by first responders. The content was collected over the previous month(s) and reproduced from a general Internet search using the term wearables. Additional information is available at the websites provided. This report is not meant to be an exhaustive list nor an endorsement of any technology described herein. Rather, it is meant to provide useful information about current developments in the areas wearable technology.

  6. Responding to the refusal of care in the emergency department.

    Science.gov (United States)

    Nelson, Jennifer; Venkat, Arvind; Davenport, Moira

    2014-01-01

    The emergency department (ED) serves as the primary gateway for acute care and the source of health care of last resort. Emergency physicians are commonly expected to rapidly assess and treat patients with a variety of life-threatening conditions. However, patients do refuse recommended therapy, even when the consequences are significant morbidity and even mortality. This raises the ethical dilemma of how emergency physicians and ED staff can rapidly determine whether patient refusal of treatment recommendations is based on intact decision-making capacity and how to respond in an appropriate manner when the declining of necessary care by the patient is lacking a basis in informed judgment. This article presents a case that illustrates the ethical tensions raised by the refusal of life-sustaining care in the ED and how such situations can be approached in an ethically appropriate manner.

  7. Challenges to Leadership: Responding to Biological Threats

    Science.gov (United States)

    2011-10-01

    Challenges to Leadership : Responding to Biological Threats Paul Rosenzweig Center for Technology and National Security Policy...Challenges to Leadership : Responding to Biological Threats 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT... theory , two other components to any program to reduce the threat of a biological attack: limiting access to source materials and technology and

  8. Preschool Needle Pain Responding: Establishing 'Normal'.

    Science.gov (United States)

    Waxman, Jordana A; DiLorenzo, Miranda G; Pillai Riddell, Rebecca R; Flora, David B; Greenberg, Saul; Garfield, Hartley

    2017-06-01

    The current study sets forth to provide descriptive data for preschool vaccination pain responding as well as examine longitudinal relationships over early childhood. Growth mixture modeling was first used to describe stable subgroups of preschoolers on the basis of their pain response patterns over 2-minutes post-needle. Secondly, a parallel-process growth curve model was used to assess the stability of acute pain responding from 12 months of age to preschool age. Specifically, we examined whether preschool pain-related distress or regulation could be predicted from 12-month acute pain responding. Preschool participants were part of a Canadian longitudinal cohort (The Opportunities to Understand Childhood Hurt [OUCH] cohort; N = 302). Growth mixture modeling analyses discerned 3 distinct groups of preschoolers, with an important minority not regulating to low-no pain by 2 minutes post-needle. There were no significant associations between 12-month and preschool pain responding. These results highlight the steep trajectory of development between these different stages of early childhood and the variability of pain responding at the preschool vaccination. This study provides descriptive data for preschool vaccination pain responding as well as examines longitudinal relationships over early childhood. Demonstrating significantly different pain patterns from infancy, 25% of preschoolers are displaying suboptimal regulation trajectories. This considerable minority poses a significant concern because of the established trajectory of phobia onset in middle childhood. Copyright © 2017 American Pain Society. Published by Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    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.

  10. Kerr and free carrier ultrafast all-optical switching of GaAs/As nanostructures near the three photon edge of GaAs

    NARCIS (Netherlands)

    Hartsuiker, A.; Harding, P.J.; Nowicki-Bringuier, Yoanna-Reine; Gérard, Jean-Michel; Vos, Willem L.

    2008-01-01

    We performed nondegenerate pump-probe experiments on a GaAs/AlAs photonic cavity structure. We switched the photonic properties using the optical Kerr effect and free carriers excited by three photon absorption. The structure was probed at 1150–1640 nm, in the telecom spectral range below the stop

  11. LEBANON AFTER THE CEDAR REVOLUTION/ARE KNUDSEN AND MICHAEL KERR (eds; LEBANON: A HISTORY, 600--2011/by WILLIAM HARRIS

    Directory of Open Access Journals (Sweden)

    Franck Salameh

    2013-05-01

    Full Text Available LEBANON AFTER THE CEDAR REVOLUTION, ARE KNUDSEN AND MICHAEL KERR (eds; London: C. Hurst & Company, 2012. 323 pp. $29.95. LEBANON: A HISTORY, 600--2011, WILLIAM HARRIS; Oxford, New York: Oxford University Press, 2012. 360 pp. $34.95.

  12. A QM/MM and QM/QM/MM study of Kerr, Cotton-Mouton and Jones linear birefringences in liquid acetonitrile

    DEFF Research Database (Denmark)

    Fahleson, Tobias; Olsen, Jógvan Magnus Haugaard; Norman, Patrick

    2018-01-01

    QM/MM and QM/QM/MM protocols are applied to the ab initio study of the three linear birefringences Kerr, Cotton-Mouton, and Jones, as shown by acetonitrile in the gas and pure liquid phases. The relevant first-order properties as well as linear, quadratic, and cubic frequency-dependent response...

  13. The anisotropic Kerr nonlinear refractive index of the beta-barium borate (β-BaB2O4) nonlinear crystal

    DEFF Research Database (Denmark)

    Bache, Morten; Guo, Hairun; Zhou, Binbin

    2013-01-01

    We study the anisotropic nature of the Kerr nonlinear response in a beta-barium borate (β-BaB2O4, BBO) nonlinear crystal. The focus is on determining the relevant χ(3) cubic tensor components that affect interaction of type I cascaded second-harmonic generation. Various experiments in the literat...

  14. Transcriptional changes induced by bevacizumab combination therapy in responding and non-responding recurrent glioblastoma patients

    DEFF Research Database (Denmark)

    Urup, Thomas; Staunstrup, Line Maersk; Michaelsen, Signe Regner

    2017-01-01

    expression profiling of formalin-fixed paraffin-embedded tumor tissue was performed using RNA-sequencing.Results: By comparing pretreatment samples of responders with those of non-responders no significant difference was observed. In a paired comparison analysis of pre- and posttreatment samples of non...... distinct gene expression changes while responding tumors adaptively respond or progress by means of the same transcriptional changes. In conclusion, we hypothesize that the identified gene expression changes of responding tumors are associated to bevacizumab response or resistance mechanisms....

  15. Rapid response manufacturing (RRM)

    Energy Technology Data Exchange (ETDEWEB)

    Cain, W.D. [Lockheed Martin Energy Systems, Inc., Oak Ridge, TN (United States); Waddell, W.L. [National Centers for Manufacturing Sciences, Ann Arbor, MI (United States)

    1997-02-18

    US industry is fighting to maintain its competitive edge in the global market place. Today markets fluctuate rapidly. Companies, to survive, have to be able to respond with quick-to-market, improved, high quality, cost efficient products. The way products are developed and brought to market can be improved and made more efficient through the proper incorporation of emerging technologies. The RRM project was established to leverage the expertise and resources of US private industries and federal agencies to develop, integrate, and deploy new technologies that meet critical needs for effective product realization. The RRM program addressed a needed change in the US Manufacturing infrastructure that will ensure US competitiveness in world market typified by mass customization. This project provided the effort needed to define, develop and establish a customizable infrastructure for rapid response product development design and manufacturing. A major project achievement was the development of a broad-based framework for automating and integrating the product and process design and manufacturing activities involved with machined parts. This was accomplished by coordinating and extending the application of feature-based product modeling, knowledge-based systems, integrated data management, and direct manufacturing technologies in a cooperative integrated computing environment. Key technological advancements include a product model that integrates product and process data in a consistent, minimally redundant manner, an advanced computer-aided engineering environment, knowledge-based software aids for design and process planning, and new production technologies to make products directly from design application software.

  16. Dependent Interviewing and Sub-Optimal Responding

    Directory of Open Access Journals (Sweden)

    Johannes Eggs

    2015-02-01

    Full Text Available With proactive dependent interviewing (PDI respondents are reminded of the answer they gave in the previous interview, before being asked about their current status. PDI is used in panel surveys to assist respondent recall and reduce spurious changes in responses over time. PDI may however provide scope for new errors if respondents falsely accept the previous information as still being an accurate description of their current situation. In this paper we use data from the German Labour Market and Social Security panel study, in which an error was made with the preload data for a PDI question about receipt of welfare benefit. The survey data were linked to individual administrative records on receipt of welfare benefit. A large proportion of respondents accepted the false preload. This behaviour seems mainly driven by the difficulty of the response task: respondents with a more complex history of receipt according to the records were more likely to confirm the false preload. Personality also seemed related to the probability of confirming. Predictors of satisficing, indicators of satisficing on other items in the survey, and characteristics of the survey and interviewer were not predictive of confirming the false preload.

  17. Mischievous responding in Internet Gaming Disorder research.

    Science.gov (United States)

    Przybylski, Andrew K

    2016-01-01

    The most recent update to the American Psychiatric Association's (APA) Diagnostic and Statistical Manual of Mental Disorders (DSM-5) included Internet Gaming Disorder as a new potential psychiatric condition that merited further scientific study. The present research was conducted in response to the APA Substance-Related Disorders Working Group's research call to estimate the extent to which mischievous responding-a known problematic pattern of participant self-report responding in questionnaires-is relevant to Internet Gaming Disorder research. In line with a registered sampling and analysis plan, findings from two studies (n tot = 11,908) provide clear evidence that mischievous responding is positively associated with the number of Internet Gaming Disorder indicators participants report. Results are discussed in the context of ongoing problem gaming research and the discussion provides recommendations for improving the quality of scientific practice in this area.

  18. Half-metallicity and giant magneto-optical Kerr effect in N-doped NaTaO3

    KAUST Repository

    Saeed, Yasir

    2012-09-01

    We use density functional theory and the modified Becke-Johnson (mBJ) approach to analyze the electronic and magneto-optical properties of N-doped NaTaO 3. The mBJ results show a half-metallic nature of NaTaO 2N, in contrast to the generalized gradient approximation. We find a giant polar Kerr rotation of 2.16°at 725 nm wave length (visible region), much higher than in other half-metallic perovskites and the prototypical half-metal PtMnSb. We explain the physical origin of this unexpected property. © 2012 Elsevier B.V. All rights reserved.

  19. Domain wall velocity measurement in permalloy nanowires with X-ray magnetic circular dichroism imaging and single shot Kerr microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Moore, T.A., E-mail: t.a.moore@physics.or [Fachbereich Physik, Universitaet Konstanz, Universitaetsstrasse 10, 78457 Konstanz (Germany); Klaeui, M.; Heyne, L.; Moehrke, P. [Fachbereich Physik, Universitaet Konstanz, Universitaetsstrasse 10, 78457 Konstanz (Germany); Backes, D.; Rhensius, J. [Fachbereich Physik, Universitaet Konstanz, Universitaetsstrasse 10, 78457 Konstanz (Germany); Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Ruediger, U. [Fachbereich Physik, Universitaet Konstanz, Universitaetsstrasse 10, 78457 Konstanz (Germany); Heyderman, L.J. [Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Mentes, T.O.; Nino, M.A.; Locatelli, A. [Sincrotrone Trieste, 34012 Basovizza-Trieste (Italy); Potenza, A.; Marchetto, H.; Cavill, S.; Dhesi, S.S. [Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE (United Kingdom)

    2010-05-15

    Domain walls (DWs) propagated along nanoscale magnetic wires by current or field pulses could potentially be used for data storage or logic applications, but the understanding of the DW dynamics, particularly under the influence of spin-polarized current, is incomplete. Measuring the velocity can give insights into the physics of the DW motion. Here we demonstrate DW velocity measurements in permalloy (Ni{sub 80}Fe{sub 20}) nanowires (1500 nm width and 20 nm thickness) using the techniques of X-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) to image the magnetic contrast in the nanowires, and single shot Kerr microscopy, which allows for dynamic measurements. The magnetic imaging yields the average velocity as well as information on the DW spin structure, whereas the single shot method highlights the stochastic nature of the DW motion.

  20. Domain wall velocity measurement in permalloy nanowires with X-ray magnetic circular dichroism imaging and single shot Kerr microscopy

    Science.gov (United States)

    Moore, T. A.; Kläui, M.; Heyne, L.; Möhrke, P.; Backes, D.; Rhensius, J.; Rüdiger, U.; Heyderman, L. J.; Mentes, T. O.; Niño, M. Á.; Locatelli, A.; Potenza, A.; Marchetto, H.; Cavill, S.; Dhesi, S. S.

    2010-05-01

    Domain walls (DWs) propagated along nanoscale magnetic wires by current or field pulses could potentially be used for data storage or logic applications, but the understanding of the DW dynamics, particularly under the influence of spin-polarized current, is incomplete. Measuring the velocity can give insights into the physics of the DW motion. Here we demonstrate DW velocity measurements in permalloy ( Ni80Fe20) nanowires (1500 nm width and 20 nm thickness) using the techniques of X-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) to image the magnetic contrast in the nanowires, and single shot Kerr microscopy, which allows for dynamic measurements. The magnetic imaging yields the average velocity as well as information on the DW spin structure, whereas the single shot method highlights the stochastic nature of the DW motion.

  1. Operation of femtosecond Kerr-lens mode-locked Cr:ZnSe lasers with different dispersion compensation methods

    Science.gov (United States)

    Cizmeciyan, M. N.; Cankaya, H.; Kurt, A.; Sennaroglu, A.

    2012-03-01

    We employed various low-cost dispersion compensation methods to generate femtosecond pulses from a Kerr-lens mode-locked (KLM) Cr:ZnSe laser operating near 2400 nm. Prism pairs made of CaF2 and MgF2 and slabs of BK7 and YAG were tested. Pulses as short as 92 fs were obtained when a CaF2 prism pair was used in the resonator with a 1% output coupler. With a 6% output coupler and CaF2 prism pair, pulse energies as high as 1.8 nJ were obtained. The KLM operating point was further analyzed for different dispersion compensation scenarios by using the soliton area theorem to determine the nonlinear refractive index ( n 2) of Cr:ZnSe. Results gave an n 2 value of (1.2±0.2)×10-18 m2/W in agreement with previous reports.

  2. Giant Kerr nonlinearity and superluminal and subluminal polaritonic solitons in a Bose-Einstein condensate via superradiant scattering

    Science.gov (United States)

    Hang, Chao; Gabadadze, Gregory; Huang, Guoxiang

    2015-09-01

    We propose a setup to generate giant Kerr nonlinearity and polaritonic solitons via matter-wave superradiant scattering. The system we consider is a long cigar-shaped Bose-Einstein condensate (BEC), pumped by a red-detuned laser field with a space-dependent intensity distribution in transverse directions. The pump and the scattered fields propagate along the longitudinal direction. We show that by means of the atom-photon and atom-atom interactions in the system it is possible to produce a giant nonlinear optical effect. We further show that a backward scattering of the laser field from the BEC is favorable for the formation and stable propagation of polaritonic solitons, which are collective nonlinear excitations of the BEC coupled with the scattered laser field. In the case of backward Stokes (anti-Stokes) scattering the system may support robust bright (dark) polaritonic solitons propagating with superluminal (subluminal) velocity.

  3. Gravitational self-force correction to the innermost stable circular equatorial orbit of a Kerr black hole.

    Science.gov (United States)

    Isoyama, Soichiro; Barack, Leor; Dolan, Sam R; Le Tiec, Alexandre; Nakano, Hiroyuki; Shah, Abhay G; Tanaka, Takahiro; Warburton, Niels

    2014-10-17

    For a self-gravitating particle of mass μ in orbit around a Kerr black hole of mass M ≫ μ, we compute the O(μ/M) shift in the frequency of the innermost stable circular equatorial orbit due to the conservative piece of the gravitational self-force acting on the particle. Our treatment is based on a Hamiltonian formulation of the dynamics in terms of geodesic motion in a certain locally defined effective smooth spacetime. We recover the same result using the so-called first law of binary black-hole mechanics. We give numerical results for the innermost stable circular equatorial orbit frequency shift as a function of the black hole's spin amplitude, and compare with predictions based on the post-Newtonian approximation and the effective one-body model. Our results provide an accurate strong-field benchmark for spin effects in the general-relativistic two-body problem.

  4. Analysis of the time-resolved magneto-optical Kerr effect for ultrafast magnetization dynamics in ferromagnetic thin films

    Science.gov (United States)

    Razdolski, I.; Alekhin, A.; Martens, U.; Bürstel, D.; Diesing, D.; Münzenberg, M.; Bovensiepen, U.; Melnikov, A.

    2017-05-01

    We discuss fundamental aspects of laser-induced ultrafast demagnetization probed by the time-resolved magneto-optical Kerr effect (MOKE). Studying thin Fe films on MgO substrate in the absence of electronic transport, we demonstrate how to disentangle pump-induced variations of magnetization and magneto-optical coefficients. We provide a mathematical formalism for retrieving genuine laser-induced magnetization dynamics and discuss its applicability in real experimental situations. We further stress the importance of temporal resolution achieved in the experiments and argue that measurements of both time-resolved MOKE rotation and ellipticity are needed for the correct assessment of magnetization dynamics on sub-picosecond timescales. The framework developed here sheds light onto the details of the time-resolved MOKE technique and contributes to the understanding of the interplay between ultrafast laser-induced optical and magnetic effects.

  5. Incidence angle dependence of Magneto Optical Kerr Effect in magnetic(Py or Co)/nonmagnetic(Nb) multilayers

    Science.gov (United States)

    Kuljis, Daniel

    The Magneto Optical Kerr Effect (MOKE) has garnered much attention for being a low cost and extremely sensitive magnetometer capable of local magnetic measurements with a shallow penetration depth. While this quality has been readily exploited, little attention has been devoted to the variation in angle of incidence and its effect on the penetration depth or any capabilities it has in measuring the depth sensitivity function. A Py/Nb/Co system was optimized for two-step switching within a range of a penetration depth of 270 A by changing the thickness of the individual layers. MOKE measurement setup was modified by changing the angle of incidence from 20° to 52°. Increasing angle of incidence correlated with an increasing ratio of magnetization after first switching to the saturation magnetization. Distinct two-step hysteresis measurements change to a one-step hysteresis measurement with increasing angle of incidence, observing the laser penetration depth moving over a domain wall.

  6. High-power diode-pumped Kerr-lens mode-locked bulk Yb:KGW laser.

    Science.gov (United States)

    Akbari, Reza; Major, Arkady

    2017-11-01

    A high-power (>1  W) pure Kerr-lens mode-locked bulk Yb:KGW laser with multimode fiber-coupled diode pumping was demonstrated. The laser delivered 240 fs pulses with 2.3 W of average output power at 86.8 MHz, corresponding to 97 kW of peak power and 26 nJ of pulse energy. The shortest generated pulse duration was 120 fs with 1.2 W of output power. The self-starting regime was also observed with a background continuous-wave component. The laser exhibited more than an order of magnitude higher output power when compared to the previously reported bulk Yb-ion-doped lasers with multimode laser diode pumping systems.

  7. Temperature dependence of Kerr coefficient and quadratic polarized optical coefficient of a paraelectric Mn:Fe:KTN crystal

    Directory of Open Access Journals (Sweden)

    Qieni Lu

    2015-08-01

    Full Text Available We measure temperature dependence on Kerr coefficient and quadratic polarized optical coefficient of a paraelectric Mn:Fe:KTN crystal simultaneously in this work, based on digital holographic interferometry (DHI. And the spatial distribution of the field-induced refractive index change can also be visualized and estimated by numerically retrieving sequential phase maps of Mn:Fe:KTN crystal from recording digital holograms in different states. The refractive indices decrease with increasing temperature and quadratic polarized optical coefficient is insensitive to temperature. The experimental results suggest that the DHI method presented here is highly applicable in both visualizing the temporal and spatial behavior of the internal electric field and accurately measuring electro-optic coefficient for electrooptical media.

  8. Off-Diagonal Deformations of Kerr Black Holes in Einstein and Modified Massive Gravity and Higher Dimensions

    CERN Document Server

    Gheorghiu, Tamara; Vacaru, Sergiu I

    2014-01-01

    We find general parameterizations for generic off-diagonal spacetime metrics and matter sources in general relativity, GR, and modified gravity theories when the field equations decouple with respect to certain types of nonholonomic frames of reference. This allows us to construct various classes of exact solutions when the coefficients of fundamental geometric/ physical objects depend on all spacetime coordinates via corresponding classes of generating and integration functions and/or constants. Such (modified) spacetimes can be with Killing and non-Killing symmetries, describe nonlinear vacuum configurations and effective polarizations of cosmological and interaction constants. Our method can be extended to higher dimensions which simplifies some proofs for imbedded and nonholonomically constrained four dimensional configurations. We reproduce the Kerr solution and show how to deform it nonholonomically into new classes of generic off-diagonal solutions depending on 3-8 spacetime coordinates. There are anal...

  9. Determination of the spin-flip time in ferromagnetic SrRuO3 from time-resolved Kerr measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kantner, C.L.S.; Langner, M.C.; Siemons, W.; Blok, J.L.; Koster, G.; Rijnders, A.J.H.M.; Ramesh, R.; Orenstein, J.

    2010-07-30

    We report time-resolved Kerr effect measurements of magnetization dynamics in ferromagnetic SrRuO{sub 3}. We observe that the demagnetization time slows substantially at temperatures within 15K of the Curie temperature, which is {approx} 150K. We analyze the data with a phenomenological model that relates the demagnetization time to the spin flip time. In agreement with our observations the model yields a demagnetization time that is inversely proportional to T-T{sub c}. We also make a direct comparison of the spin flip rate and the Gilbert damping coefficient showing that their ratio very close to k{sub B}T{sub c}, indicating a common origin for these phenomena.

  10. Transcriptional changes induced by bevacizumab combination therapy in responding and non-responding recurrent glioblastoma patients

    DEFF Research Database (Denmark)

    Urup, Thomas; Staunstrup, Line Maersk; Michaelsen, Signe Regner

    2017-01-01

    and resistance to bevacizumab combination therapy.Methods: Recurrent glioblastoma patients who had biomarker-accessible tumor tissue surgically removed both before bevacizumab treatment and at time of progression were included. Patients were grouped into responders (n = 7) and non-responders (n = 14). Gene...... expression profiling of formalin-fixed paraffin-embedded tumor tissue was performed using RNA-sequencing.Results: By comparing pretreatment samples of responders with those of non-responders no significant difference was observed. In a paired comparison analysis of pre- and posttreatment samples of non...

  11. Responding to Loneliness: Counseling the Elderly.

    Science.gov (United States)

    France, M. Honore

    1984-01-01

    Describes the development and implementation of a group on "Responding to Loneliness" for the elderly. Focuses on building positive self-esteem; learning social and personal skills; managing stress and anxiety; developing problem-solving strategies; and building a social network. (Author/JAC)

  12. Responding to Misinformation about Climate Change

    Science.gov (United States)

    Lawrence, Eva K.; Estow, Sarah

    2017-01-01

    This study examined responses to climate change misinformation and messages designed to counter misinformation. Participants (N = 406) first responded to a social media post denying the existence of global warming and then were randomly assigned to read one of three responses to the original post (correction, collaboration, control). Participants…

  13. Porphyria cutanea tarda responding to spirulina

    Directory of Open Access Journals (Sweden)

    Pavithran K

    1992-01-01

    Full Text Available A male patient of porphyria cutanea tarda responded to oral spirulina - an alga rich in beta - carotene. The beta - carotene in the spirulina quenches the singlet oxygen which is responsible for the tissue damage in porphyria-associated photosensitivity.

  14. What is wrong with non-respondents?

    DEFF Research Database (Denmark)

    Christensen, Anne Illemann; Ekholm, Ola; Gray, Linsay

    2015-01-01

    AIM: Response rates in health surveys have diminished over the last two decades, making it difficult to obtain reliable information on health and health-related risk factors in different population groups. This study compared cause-specific mortality and morbidity among survey respondents and dif...

  15. Responding to organised environmental crimes: Collaborative ...

    African Journals Online (AJOL)

    Responding to organised environmental crimes: Collaborative approaches and capacity building. ... helpful Frequently Asked Questions about PDFs. Alternatively, you can download the PDF file directly to your computer, from where it can be opened using a PDF reader. To download the PDF, click the Download link above.

  16. Learning Games for Active Student Responding.

    Science.gov (United States)

    Wesson, Caren; And Others

    1988-01-01

    Instructional games can be used effectively when they require active student participation and high rates of student responding. The article describes principles of such games and suggests ways to turn typical games (such as "Bingo,""War,""Scrabble,""Boggle," paper/pencil games, and question/answer games) into active, high-response games. (JDD)

  17. School Principals and Racism: Responding to Aveling

    Science.gov (United States)

    Charles, Claire; Mahoney, Caroline; Fox, Brandi; Halse, Christine

    2016-01-01

    This study responds to Nado Aveling's call in "Anti-racism in Schools: A question of leadership?" ("Discourse: Studies in the Cultural Politics of Education," 2007, 28(1), 69-85) for further investigation into racism in Australian schools. Aveling's interview study concluded that an overwhelming number of school principals…

  18. The superluminous transient ASASSN-15lh as a tidal disruption event from a Kerr black hole

    Science.gov (United States)

    Leloudas, G.; Fraser, M.; Stone, N. C.; van Velzen, S.; Jonker, P. G.; Arcavi, I.; Fremling, C.; Maund, J. R.; Smartt, S. J.; Krìhler, T.; Miller-Jones, J. C. A.; Vreeswijk, P. M.; Gal-Yam, A.; Mazzali, P. A.; De Cia, A.; Howell, D. A.; Inserra, C.; Patat, F.; de Ugarte Postigo, A.; Yaron, O.; Ashall, C.; Bar, I.; Campbell, H.; Chen, T.-W.; Childress, M.; Elias-Rosa, N.; Harmanen, J.; Hosseinzadeh, G.; Johansson, J.; Kangas, T.; Kankare, E.; Kim, S.; Kuncarayakti, H.; Lyman, J.; Magee, M. R.; Maguire, K.; Malesani, D.; Mattila, S.; McCully, C. V.; Nicholl, M.; Prentice, S.; Romero-Cañizales, C.; Schulze, S.; Smith, K. W.; Sollerman, J.; Sullivan, M.; Tucker, B. E.; Valenti, S.; Wheeler, J. C.; Young, D. R.

    2016-12-01

    When a star passes within the tidal radius of a supermassive black hole, it will be torn apart1. For a star with the mass of the Sun (M ⊙) and a non-spinning black hole with a mass 108 M ⊙ 12,13, a star with the same mass as the Sun could be disrupted outside the event horizon if the black hole were spinning rapidly14. The rapid spin and high black hole mass can explain the high luminosity of this event.

  19. Role of top and bottom interfaces of a Pt/Co/AlOx system in Dzyaloshinskii-Moriya interaction, interface perpendicular magnetic anisotropy, and magneto-optical Kerr effect

    Science.gov (United States)

    Kim, Nam-Hui; Cho, Jaehun; Jung, Jinyong; Han, Dong-Soo; Yin, Yuxiang; Kim, June-Seo; Swagten, Henk J. M.; Lee, Kyujoon; Jung, Myung-Hwa; You, Chun-Yeol

    2017-03-01

    We investigate the role of top and bottom interfaces in inversion symmetry-breaking Pt/Co/AlOx systems by inserting ultra-thin Cu layers. Wedge-type ultrathin Cu layers (0-0.5 nm) are introduced between Pt/Co or Co/AlOx interfaces. Interface sensitive physical quantities such as the interfacial Dzyaloshinskii-Moriya interaction (iDMI) energy density, the interfacial perpendicular magnetic anisotropy (iPMA), and the magneto-optical Kerr effects (MOKE) are systematically measured as a function of Cu-insertion layer thickness. We find that the Cu-insertion layer in the bottom interface (Pt/Co) plays a more important role in iDMI, PMA, and MOKE. In contrast, the top interface (Co/AlOx) noticeably contributes to only PMA, while its contributions to iDMI and MOKE enhancement are less significant. Although the PMA mainly comes from the bottom interface (Pt/Co), the Cu-insertion layers of all interfaces (Pt/Co, Co/AlOx) influence PMA. For iDMI, only the Cu-insertion layer in the bottom interface exerts SOC suppression which leads iDMI energy to decrease rapidly.

  20. Role of top and bottom interfaces of a Pt/Co/AlOx system in Dzyaloshinskii-Moriya interaction, interface perpendicular magnetic anisotropy, and magneto-optical Kerr effect

    Directory of Open Access Journals (Sweden)

    Nam-Hui Kim

    2017-03-01

    Full Text Available We investigate the role of top and bottom interfaces in inversion symmetry-breaking Pt/Co/AlOx systems by inserting ultra-thin Cu layers. Wedge-type ultrathin Cu layers (0-0.5 nm are introduced between Pt/Co or Co/AlOx interfaces. Interface sensitive physical quantities such as the interfacial Dzyaloshinskii-Moriya interaction (iDMI energy density, the interfacial perpendicular magnetic anisotropy (iPMA, and the magneto-optical Kerr effects (MOKE are systematically measured as a function of Cu-insertion layer thickness. We find that the Cu-insertion layer in the bottom interface (Pt/Co plays a more important role in iDMI, PMA, and MOKE. In contrast, the top interface (Co/AlOx noticeably contributes to only PMA, while its contributions to iDMI and MOKE enhancement are less significant. Although the PMA mainly comes from the bottom interface (Pt/Co, the Cu-insertion layers of all interfaces (Pt/Co, Co/AlOx influence PMA. For iDMI, only the Cu-insertion layer in the bottom interface exerts SOC suppression which leads iDMI energy to decrease rapidly.

  1. RESPONDING PROFESSIONALLY TO REQUESTS FOR CESAREAN DELIVERY.

    Science.gov (United States)

    Chervenak, F; McCullough, L

    2017-01-01

    Patients' requests for non-indicated cesarean delivery challenge the professionalism of obstetricians. This is because physicians should not provide clinical management in the absence of an evidence-based indication for it. The ethics of responding professionally to requests for non-indicated cesarean delivery would appear to be simple: just say "No." This paper presents an ethically and clinically more nuanced approach, on the basis of the professional responsibility model of obstetric ethics, emphasizinga preventive ethics approach. Preventive ethics deploys the informed consent process to minimize ethical conflict in clinical practice. This process should focus on when to recommend against cesarean delivery - rather than simply saying no. There is no evidence of net clinical benefit for pregnant, fetal, and neonatal patients from non-indicated cesarean delivery. Obstetricians should therefore respond to such requests by recommending against cesarean delivery, recommending vaginal delivery, and explaining the evidence base for these recommendations.

  2. Mischievous responding in Internet Gaming Disorder research

    Directory of Open Access Journals (Sweden)

    Andrew K. Przybylski

    2016-09-01

    Full Text Available The most recent update to the American Psychiatric Association’s (APA Diagnostic and Statistical Manual of Mental Disorders (DSM-5 included Internet Gaming Disorder as a new potential psychiatric condition that merited further scientific study. The present research was conducted in response to the APA Substance-Related Disorders Working Group’s research call to estimate the extent to which mischievous responding—a known problematic pattern of participant self-report responding in questionnaires—is relevant to Internet Gaming Disorder research. In line with a registered sampling and analysis plan, findings from two studies (ntot = 11,908 provide clear evidence that mischievous responding is positively associated with the number of Internet Gaming Disorder indicators participants report. Results are discussed in the context of ongoing problem gaming research and the discussion provides recommendations for improving the quality of scientific practice in this area.

  3. Dendritic cells from the human female reproductive tract rapidly capture and respond to HIV.

    Science.gov (United States)

    Rodriguez-Garcia, M; Shen, Z; Barr, F D; Boesch, A W; Ackerman, M E; Kappes, J C; Ochsenbauer, C; Wira, C R

    2017-03-01

    Dendritic cells (DCs) throughout the female reproductive tract (FRT) were examined for phenotype, HIV capture ability and innate anti-HIV responses. Two main CD11c + DC subsets were identified: CD11b + and CD11b low DCs. CD11b + CD14 + DCs were the most abundant throughout the tract. A majority of CD11c + CD14 + cells corresponded to CD1c + myeloid DCs, whereas the rest lacked CD1c and CD163 expression (macrophage marker) and may represent monocyte-derived cells. In addition, we identified CD103 + DCs, located exclusively in the endometrium, whereas DC-SIGN + DCs were broadly distributed throughout the FRT. Following exposure to GFP-labeled HIV particles, CD14 + DC-SIGN + as well as CD14 + DC-SIGN - cells captured virus, with ∼30% of these cells representing CD1c + myeloid DCs. CD103 + DCs lacked HIV capture ability. Exposure of FRT DCs to HIV induced secretion of CCL2, CCR5 ligands, interleukin (IL)-8, elafin, and secretory leukocyte peptidase inhibitor (SLPI) within 3 h of exposure, whereas classical pro-inflammatory molecules did not change and interferon-α2 and IL-10 were undetectable. Furthermore, elafin and SLPI upregulation, but not CCL5, were suppressed by estradiol pre-treatment. Our results suggest that specific DC subsets in the FRT have the potential for capture and dissemination of HIV, exert antiviral responses and likely contribute to the recruitment of HIV-target cells through the secretion of innate immune molecules.

  4. Protecting Respondent Confidentiality in Qualitative Research

    Science.gov (United States)

    Kaiser, Karen

    2009-01-01

    For qualitative researchers, maintaining respondent confidentiality while presenting rich, detailed accounts of social life presents unique challenges. These challenges are not adequately addressed in the literature on research ethics and research methods. Using an example from a study of breast cancer survivors, I argue that by carefully considering the audience for one’s research and by re-envisioning the informed consent process, qualitative researchers can avoid confidentiality dilemmas that might otherwise lead them not to report rich, detailed data. PMID:19843971

  5. Nuclear Fallout Decision Tool for First Responders

    Energy Technology Data Exchange (ETDEWEB)

    Archibald, E. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Buddemeier, B. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2010-08-11

    If terrorists detonated an improvised nuclear device (IND) in an urban area, thousands of people would die from the blast, and many more would become sick or die from exposure to fallout radiation. Proper sheltering and evacuation can protect people from fallout and save lives. This project provides guidance to first responders as to when to evacuate and what route to take to protect themselves against fallout radiation.

  6. Preventing and responding to medical identity theft.

    Science.gov (United States)

    Amori, Geraldine

    2008-01-01

    Medical identity theft is a crime with two victims: patients and providers. It is easy to commit and lucrative because healthcare record keeping and business interactions are complex and mainly electronic. Patients whose identity has been stolen are vulnerable to both medical error and financial loss. Providers may suffer both reputation loss and financial loss. There are steps to help prevent and to respond appropriately to medical identity theft.

  7. Amitriptyline Intoxication Responded to Cardiopulmonary Resuscitation

    Directory of Open Access Journals (Sweden)

    Güldem Turan

    2012-04-01

    Full Text Available The most severe effects in amitriptiline intoxications are related with central nervous system and cardiovascular system. Amitriptiline intoxication especially with high doses has severe cardiac effects and can result in cardiac arrest. Most favorable responses can be achieved with efficient and prolonged cardiopulmonary resuscitation. We wanted to present a case ingested high dose of amitriptiline for attempt to suicide and responded to prolonged cardiopulmonary resuscitation.

  8. 77 GHz radar for first responders

    Science.gov (United States)

    Kosowsky, L. H.; Aronoff, A. D.; Ferraro, R.; Alland, S.; Fleischman, E.

    2017-02-01

    First responders have the dangerous task of responding to emergency situations in firefighting scenarios involving homes and offices. The importance of this radar is its ability to see through walls and into adjacent areas to provide the first responder with information to assess the status of a building fire, its occupants, and to supplement his thermal camera which is obstructed by the wall. For the firefighter looking into an adjacent room containing unknown objects including humans, the challenge is to recognize what is in that room, the configuration of the room, and potential escape routes. We have just concluded a series of experiments to illustrate the performance of 77GHz radar in buildings. The experiments utilized the Delphi Automotive radar as the mm wave sensor and included display software developed by L. H. Kosowsky and Associates. The system has demonstrated the capability of seeing through walls consisting of sheetrock separated by two by four pieces of wood. It has demonstrated the ability to see into the adjacent room and to display the existence of persons and furniture Based on published data, the radar will perform well in a smoke, haze, and/or fog environment.

  9. Niacin-respondent subset of schizophrenia – a therapeutic review.

    Science.gov (United States)

    Xu, X J; Jiang, G S

    2015-01-01

    It is well known that niacin deficiency manifests with several psychiatric manifestations. Also historically evidence has accumulated that niacin augmentation can be used for treatment of schizophrenia. However, the etiopathological associations between niacin deficiency and schizophrenia as well as the mechanism of action of niacin in its treatment. More importantly, the subgroups of schizophrenia which will respond to niacin augmentation has never been highlighted in the literature. In this article, we review three of the mechanisms in which niacin deficiency could lead to schizophrenic symptoms: (1) Niacin deficiency neurodegeneration (2) Membrane phospholipid deficiency hypothesis and (3) Adrenochrome hypothesis. We will further move towards the clinical as well as treatment related associations as reviewed from the literature. Here, we propose a model that a subset of schizophrenia can respond to niacin augmentation therapy better than other subsets because these patients have contributions in their psychotic manifestations from the neural degeneration resulting from niacin deficiency. We present a short description of our case report which showed rapid improvement in schizophrenic psychotic symptoms subsequent to administration of niacin as an augmentation therapy. We, thus, propose that niacin deficiency is a contributory factor in schizophrenia development in some patients and symptom alleviation in these patients will benefit from niacin augmentation, especially in some particular psychotic features.

  10. First aid skill retention of first responders within the workplace

    Directory of Open Access Journals (Sweden)

    Masse Jeff

    2011-02-01

    Full Text Available Abstract Background Recent literature states that many necessary skills of CPR and first aid are forgotten shortly after certification. The purpose of this study was to determine the skill and knowledge decay in first aid in those who are paid to respond to emergency situations within a workplace. Methods Using a choking victim scenario, the sequence and accuracy of events were observed and recorded in 257 participants paid to act as first responders in large industrial or service industry settings. A multiple choice exam was also written to determine knowledge retention. Results First aid knowledge was higher in those who were trained at a higher level, and did not significantly decline over time. Those who had renewed their certificate one or more times performed better than those who had learned the information only once. During the choking scenario many skills were performed poorly, regardless of days since last training, such as hand placement and abdominal thrusts. Compressions following the victim becoming unconscious also showed classic signs of skill deterioration after 30 days. Conclusions As many skills deteriorate rapidly over the course of the first 90 days, changing frequency of certification is not necessarily the most obvious choice to increase retention of skill and knowledge. Alternatively, methods of regularly "refreshing" a skill should be explored that could be delivered at a high frequency - such as every 90 days.

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

    CERN Document Server

    Lin, Guoping

    2015-01-01

    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 $10^9$. 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 pus...

  12. Enormous enhancements of the Kerr nonlinearity at C-band telecommunication wavelength in an Er{sup 3+}-doped YAG crystal

    Energy Technology Data Exchange (ETDEWEB)

    Hamedi, Hamid Reza, E-mail: hamid.r.hamedi@gmail.com

    2014-06-01

    A novel solid configuration is proposed to achieve a giant Kerr nonlinearity with reduced absorption under conditions of slow light levels. It is shown that an enhanced Kerr nonlinearity accompanied with negligible absorption can be obtained just through the proper tuning of intensity of coherent driving field at C-band telecommunication wavelength which is practical for communication applications. Moreover, the impact of incoherent pump field as well as frequency detuning of coherent field on manipulating the linear and nonlinear optical properties of the yttrium–aluminum-garnet (YAG) crystal medium is discussed. The presented results may be of interest to researchers in the field of all-optical signal processing and solid-state quantum information science.

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

    Science.gov (United States)

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

    2018-01-01

    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.

  14. Culture-Free Leadership Effectiveness Versus Moderators of Leadership Behavior: An Extension and Test of Kerr and Jermier's “Substitutes for Leadership” Model in Taiwan

    OpenAIRE

    Jiing-Lih Farh; Podsakoff, Philip M; Bor-Shiuan Cheng

    1987-01-01

    This study was designed to examine whether several situation variables serve as moderators of the effects of leader reward and punishment behaviors for Taiwanese workers. Contrary to what would be expected from Kerr and Jermier's (1978) substitutes for leadership model, none of the situational variables was found to reverse (1) the positive relationship between leader contingent reward behavior and subordinate performance or satisfaction, or (2) the generally negative relationship between lea...

  15. Modeling of all-optical 3x8 line decoder using optical Kerr effect in plasmonic metal-insulator-metal waveguides

    Science.gov (United States)

    Singh, Lokendra; Bedi, Amna; Kumar, Santosh

    2017-02-01

    MIM plasmonic waveguides are considered in proposed work, due to their ability of confining the surface plasmons to deep subwavelength scale or beyond diffraction limit. By cascading various MIM waveguides Mach-Zehnder interferometer (MZI) is designed which has been used to design all-optical 3 × 8 line decoder. To attain the nonlinearity Kerr material has been used. The proposed device is studied and analyzed using finite-difference-time-domain (FDTD) method and MATLAB simulations.

  16. Nonlinear magneto-optical Kerr effect in hyper-Rayleigh scattering from layer-by-layer assembled films of yttrium iron garnet nanoparticles

    Science.gov (United States)

    Murzina, T. V.; Nikulin, A. A.; Aktsipetrov, O. A.; Ostrander, J. W.; Mamedov, A. A.; Kotov, N. A.; Devillers, M. A. C.; Roark, J.

    2001-08-01

    Magnetization-induced second-harmonic generation (SHG) in layer-by-layer assembled films containing yttrium iron garnet nanoparticles is observed. The SHG intensity, including its magnetoinduced component, linearly increases with the number of self-assembling layers, which indicates along with diffuseness of the SHG radiation that SHG occurs in its incoherent form: hyper-Rayleigh scattering (HRS). The nonlinear magneto-optical Kerr effect in HRS has a noticeable magnetic contrast brought about by the internal homodyne mechanism.

  17. Rapid response systems in The Netherlands

    NARCIS (Netherlands)

    Ludikhuize, Jeroen; Hamming, Annette; de Jonge, Evert; Fikkers, Bernard G.

    2011-01-01

    Sixty-three (approximately 80%) of the 81 hospitals that responded to a survey sent to all hospitals in The Netherlands with nonpediatric intensive care units had a rapid response system (RRS) in place or were in the final process of starting one. Among many other findings regarding RRS

  18. Infinite efficiency of collisional Penrose process: Can over-spinning Kerr geometry be the source of ultra-high-energy cosmic rays and neutrinos ?

    CERN Document Server

    Patil, Mandar

    2015-01-01

    The origin of the ultra-high-energy particles we receive on the Earth from the 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 ultra-high-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 $a=M(1+\\epsilon)$, where we take the limit $\\epsilon \\rightarrow 0^+$. 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 ultra-high energies exploiting the collisional Penrose p...

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

    Science.gov (United States)

    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.

  20. Enhancement of the optical Kerr effect exhibited by an integrated configuration of silicon quantum dots and silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Suarez, A; Benami, A; Tamayo-Rivera L; Reyes-Esqueda, J A; Cheang-Wong, J C; Rodriguez-Fernandez, L; Crespo-Sosa, A; Oliver, A [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, D. F. 04510 (Mexico); R Rangel-Rojo [Departamento de Optica, Centro de Investigacion CientIfica y de Educacion Superior de Ensenada, Apartado Postal 2732, Ensenada, BC 22860 (Mexico); Torres-Torres, C, E-mail: rrangel@cicese.mx [Seccion de Estudios de Posgrado e Investigacion, ESIME-Z, Instituto Politecnico Nacional, D.F. 07738 (Mexico)

    2011-01-01

    We present nonlinear refractive results for three different systems produced by ion implantation: high purity silica substrates with silicon quantum dots (Si-QDs), silver nanoparticles (Ag-NPs), and one sample containing both. We used a femtosecond optical Kerr gate (OKG) with 80 fs pulses at 830 nm to investigate the magnitude and response time of their nonlinear response. The Ag-NPs samples were prepared implanting 2 MeV Ag{sup 2+} ions at different fluencies. A sample with 1x10{sup 17} ions/cm{sup 2} showed no discernible Kerr signal, while for one with 2.4x10{sup 17} ions/cm{sup 2} we measured |{chi}{sup (3)}|{sub 1111} = 5.1x10{sup -11} esu. The Si-QDs sample required irradiation with 1.5 MeV Si{sup 2+} ions, at a 2.5x10{sup 17} ions/cm{sup 2} fluence in order that the OKG results for this sample yielded a similar |{chi}{sup (3)}|{sub 1111} value. The sample containing the Si-QDs was then irradiated by 1 MeV Ag2+ ions at a 4.44 x 10{sup 16} ions/cm{sup 2} fluence and thermally treated, for which afterward we measured |{chi}{sup (3)}|{sub 1111} 1.7x10{sup -10} esu. In all cases the response time was quasi-instantaneous. These results imply that the inclusion of Ag-NPs at low fluence, enhances the nonlinearity of the composite by a factor of around three, and that this is purely electronic in nature. Pump-probe results show that there is not any nonlinear absorption present. We estimate that the confinement effect of the Si-QDs in the sample plays an important role for the excitation of the Surface Plasmon Resonance (SPR) related to the Ag-NPs. A theoretical model that describes the modification of the third order nonlinearity is also presented.

  1. Alopecia mucinosa responding to antileprosy treatment: Are we missing something?

    Directory of Open Access Journals (Sweden)

    Rajiv Joshi

    2013-01-01

    Full Text Available Three cases with single lesion of Alopecia mucinosa (follicular mucinosis were treated with antileprosy treatment and showed rapid and complete resolution of the lesions with no recurrence on extended follow-up. Two children, a boy aged 14 years and a girl aged 12 years presented themselves, each, with a single hypopigmented, hypoesthetic patch on the face. Clinically leprosy was suspected, however, skin biopsy from both patients revealed follicular mucinosis as the only pathological finding, without any granulomas. Based on clinical suspicion both were started on multi drug therapy (MDT for leprosy with complete resolution of the lesions. The third case, male, aged 22 years presented with a single erythematous, hypoesthetic plaque on the forehead.This lesion had been diagnosed as follicular mucinosis with folliculo-tropic mycosis fungoides, in the USA. He too responded completely within 3 months with rifampicin, ofloxacin, minocycline (ROM treatment, which was given once monthly for a total of 6 months and remains free of disease since the past 1 year. Follicular mucinosis as the only pathology may be seen in facial lesions of clinically suspected leprosy in children and young adults. Based on histological findings these cannot be diagnosed as leprosy and will be considered as Alopecia mucinosa. These lesions, however, are always single and show rapid and complete response to antileprosy treatment. The authors suggest that in regions endemic for leprosy, such as India, single lesion Alopecia mucinosa on the face in children and young adults should be given antileprosy treatment.

  2. Infant differential behavioral responding to discrete emotions.

    Science.gov (United States)

    Walle, Eric A; Reschke, Peter J; Camras, Linda A; Campos, Joseph J

    2017-10-01

    Emotional communication regulates the behaviors of social partners. Research on individuals' responding to others' emotions typically compares responses to a single negative emotion compared with responses to a neutral or positive emotion. Furthermore, coding of such responses routinely measure surface level features of the behavior (e.g., approach vs. avoidance) rather than its underlying function (e.g., the goal of the approach or avoidant behavior). This investigation examined infants' responding to others' emotional displays across 5 discrete emotions: joy, sadness, fear, anger, and disgust. Specifically, 16-, 19-, and 24-month-old infants observed an adult communicate a discrete emotion toward a stimulus during a naturalistic interaction. Infants' responses were coded to capture the function of their behaviors (e.g., exploration, prosocial behavior, and security seeking). The results revealed a number of instances indicating that infants use different functional behaviors in response to discrete emotions. Differences in behaviors across emotions were clearest in the 24-month-old infants, though younger infants also demonstrated some differential use of behaviors in response to discrete emotions. This is the first comprehensive study to identify differences in how infants respond with goal-directed behaviors to discrete emotions. Additionally, the inclusion of a function-based coding scheme and interpersonal paradigms may be informative for future emotion research with children and adults. Possible developmental accounts for the observed behaviors and the benefits of coding techniques emphasizing the function of social behavior over their form are discussed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  3. "Responding to Climate Change" Course: Research Integration

    Science.gov (United States)

    Pfirman, S. L.; Bowman, J. S.

    2015-12-01

    The "Responding to Climate Change" Barnard/Columbia course integrates current research as well as hands-on research-based activities modified for a classroom environment. The course covers the major response themes of adaptation, mitigation and communication. In the spring of 2015 the course was oriented around Arctic and Antarctic case studies. Each week a different theme is addressed, such as the physical setting, changing ecosystems, governance issues, perspectives of residents and indigenous peoples, geoengineering, commercial interests, security, and health and developmental issues. Frequent guest lectures from thematic experts keep the course grounded in realities and present the students with cutting edge issues. Activities match the weekly theme, for example during the week on Arctic development, students engage with the marine spatial planning simulation Arctic SMARTIC (Strategic Management of Resources in Times of Change) based on research on Arctic sea ice trends and projections coupled with current and projected developmental interests of stakeholders. Created under the Polar Learning and Responding: PoLAR Climate Change Education Partnership (thepolarhub.org), a complete set of SMARTIC resources is available on line for use by others (http://www.camelclimatechange.org/view/article/175297/). The Responding to Climate Change course is designed to be current and respond to events. For the Arctic case study, students developed proposals for the US State Department as the upcoming Chair of the Arctic Council. Student evaluations indicated that they appreciated the opportunity to connect science with policy and presentation of preliminary proposals in a workshop format was valued as a way to develop and hone their ideas. An additional finding was that students were surprisingly tolerant of technical issues when guest lecturers were linked in via Skype, allowing interaction with thematic experts across the US. Students commented positively on this exposure to

  4. Safety Risk Management for Homeland Defense and Security Responders

    National Research Council Canada - National Science Library

    Meyers, Tommey H

    2005-01-01

    ...) report on responder safety, this thesis explores the issues associated with creating a safety risk management capability that will enable HLDS responders to better protect themselves from harm...

  5. Brain Changes in Responders versus Non-Responders in Chronic Migraine: Markers of Disease Reversal

    Directory of Open Access Journals (Sweden)

    Catherine S Hubbard

    2016-10-01

    Full Text Available The aim of this study was to identify structural and functional brain changes that accompanied the transition from chronic (CM; ≥ 15 headache days/month to episodic (EM; < 15 headache days/month migraine following prophylactic treatment with onabotulinumtoxinA. Specifically, we examined whether CM patients responsive to prophylaxis (responders; n = 11, as evidenced by a reversal in disease status (defined by at least a 50% reduction in migraine frequency and < 15 headache days/month, compared to CM patients whose migraine frequency remained unchanged (non-responders; n = 12, showed differences in cortical thickness using surface-based morphometry. We also investigated whether areas showing group differences in cortical thickness displayed altered resting-state functional connectivity (RS-FC using seed-to-voxel analyses. Migraine characteristics measured across groups included disease duration, pain intensity and headache frequency. Patient reports’ of headache frequency over the four weeks prior to (pre-treatment and following (post-treatment prophylaxis were compared (post minus pre and this measure served as the clinical endpoint that determined group assignment. All patients were scanned within two weeks of the post-treatment visit. Results revealed that responders showed significant cortical thickening in the right primary somatosensory cortex (SI and anterior insula, and left superior temporal gyrus and pars opercularis compared to non-responders. In addition, disease duration was negatively correlated with cortical thickness in fronto-parietal and temporo-occipital regions in responders but not non-responders, with the exception of the primary motor cortex (MI that showed the opposite pattern; disease duration was positively associated with MI cortical thickness in responders versus non-responders. Our seed-based RS-FC analyses revealed anti-correlations between the SI seed and lateral occipital (LOC and dorsomedial prefrontal cortices

  6. How tree roots respond to drought

    Directory of Open Access Journals (Sweden)

    Ivano eBrunner

    2015-07-01

    Full Text Available The ongoing climate change is characterised by increased temperatures and altered precipitation patterns. In addition, there has been an increase in both the frequency and intensity of extreme climatic events such as drought. Episodes of drought induce a series of interconnected effects, all of which have the potential to alter the carbon balance of forest ecosystems profoundly at different scales of plant organisation and ecosystem functioning. During recent years, considerable progress has been made in the understanding of how aboveground parts of trees respond to drought and how these responses affect carbon assimilation. In contrast, processes of belowground parts are relatively underrepresented in research on climate change. In this review, we describe current knowledge about responses of tree roots to drought. Tree roots are capable of responding to drought through a variety of strategies that enable them to avoid and tolerate stress. Responses include root biomass adjustments, anatomical alterations, and physiological acclimations. The molecular mechanisms underlying these responses are characterized to some extent, and involve stress signalling and the induction of numerous genes, leading to the activation of tolerance pathways. In addition, mycorrhizas seem to play important protective roles. The current knowledge compiled in this review supports the view that tree roots are well equipped to withstand drought situations and maintain morphological and physiological functions as long as possible. Further, the reviewed literature demonstrates the important role of tree roots in the functioning of forest ecosystems and highlights the need for more research in this emerging field.

  7. Kerr black hole parameters in terms of red/blue shifts of photons emitted by geodesic particles

    CERN Document Server

    Herrera-Aguilar, Alfredo

    2015-01-01

    We are motivated by the recently reported dynamical evidence of stars with short orbital periods moving around the center of the Milky Way and the corresponding hypothesis about the existence of a supermassive black hole hosted at its center. In this paper we show how the mass and rotation parameters of a Kerr black hole (assuming that the putative supermassive black hole is of this type), as well as the distance that separates the black hole from the Earth, can be estimated in a relativistic way in terms of i) the red and blue shifts of photons that are emitted by geodesic massive particles (stars and galactic gas) and travel along null geodesics towards a distant observer, and ii) the radius of these star/gas orbits. As a concrete example and as a first step towards a full relativistic analysis of the above mentioned star orbits around the center of our galaxy, we consider stable equatorial circular orbits of stars and express their corresponding red/blue shifts in terms of the metric parameters (mass and a...

  8. Sensory and Textural Characteristics of Noodle Made of Ganyong Flour (Canna edulis Kerr.) and Arenga Starch (Arenga pinnata Merr.)

    Science.gov (United States)

    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.

  9. Direct and inverse scattering at fixed energy for massless charged Dirac fields by Kerr-Newman-de Sitter black holes

    CERN Document Server

    Daudé, Thierry

    2017-01-01

    In this paper, the authors study the direct and inverse scattering theory at fixed energy for massless charged Dirac fields evolving in the exterior region of a Kerr-Newman-de Sitter black hole. In the first part, they establish the existence and asymptotic completeness of time-dependent wave operators associated to our Dirac fields. This leads to the definition of the time-dependent scattering operator that encodes the far-field behavior (with respect to a stationary observer) in the asymptotic regions of the black hole: the event and cosmological horizons. The authors also use the miraculous property (quoting Chandrasekhar)-that the Dirac equation can be separated into radial and angular ordinary differential equations-to make the link between the time-dependent scattering operator and its stationary counterpart. This leads to a nice expression of the scattering matrix at fixed energy in terms of stationary solutions of the system of separated equations. In a second part, the authors use this expression of ...

  10. Light-switching-light optical transistor based on metallic nanoparticle cross-chains geometry incorporating Kerr nonlinearity

    Energy Technology Data Exchange (ETDEWEB)

    AbdelMalek, Fathi; Aroua, Walid [National Institute of Applied Science and Technology, University of Carthage, Tunis (Tunisia); Haxha, Shyqyri [Computer Science and Technology Department, Bedfordshire University, Luton (United Kingdom); Flint, Ian [Selex ES Ltd, Luton, Bedfordshire (United Kingdom)

    2016-08-15

    In this research work, we propose all-optical transistor based on metallic nanoparticle cross-chains geometry. The geometry of the proposed device consists of two silver nanoparticle chains arranged along the x- and z-axis. The x-chain contains a Kerr nonlinearity, the source beam is set at the left side of the later, while the control beam is located at the top side of the z-chain. The control beam can turn ON and OFF the light transmission of an incoming light. We report a theoretical model of a very small all-optical transistor proof-of-concept made of optical 'light switching light' concept. We show that the transmission efficiency strongly depends on the control beam and polarization of the incoming light. We investigate the influence of a perfect reflector and reflecting substrate on the transmission of the optical signal when the control beam is turned ON and OFF. These new findings make our unique design a potential candidate for future highly-integrated optical information processing chips. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Exploring ultrafast negative Kerr Effect for self-mode-locking vertical external-cavity surface-emitting lasers

    Science.gov (United States)

    Albrecht, Alexander R.; Seletskiy, Denis V.; Wang, Yi; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor

    2014-03-01

    Quasi-stable self-mode-locking of an InGaAs vertical external-cavity surface-emitting laser (VECSEL) emitting around 1020 nm has been observed, resulting in 500 fs pulses at a repetition rate of 1 GHz. The mechanism is attributed to negative ultrafast Kerr lensing in the semiconductor gain structure. Our calculations show that a mode narrowing on the order of 0.5% can be obtained at the concave cavity end-mirror or at the gain medium. This is consistent with experimental observations, as mode-locking can be achieved by placing a (hard) aperture before the concave cavity end mirror inside the VECSEL cavity, or by the soft aperture created by changing the pump spot size in relation to the lasing mode on the gain chip. The pulse train generated by the VECSEL has been analyzed by a fast InGaAs photo diode and oscilloscope, RF spectrum analyzer, and second harmonic intensity autocorrelation. The effect of dispersion on pulse width has been studied, hinting at soliton-like pulse formation.

  12. X-ray magnetic circular dichroism and reflection anisotropy spectroscopy Kerr effect studies of capped magnetic nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Cunniffe, J. P.; McNally, D.E.; Liberati, M.; Arenholz, E.; McGuinness, C.; McGilp, J. F.

    2010-03-02

    Aligned Co wires grown on Pt(997) under ultra-high vacuum conditions have been capped successfully by the epitaxial growth of Au monolayers (ML) at room temperature. The samples were kept under vacuum except when transferring between apparatus or when making some of the measurements. No degradation of the Co wires was detected during the measurements. The magneto-optic response of the system was measured using X-ray magnetic circular dichroism (XMCD) at the Co L{sub 2,3} edge and reflection anisotropy spectroscopy (RAS) at near normal incidence, which is sensitive to the normal component of the out-of-plane magnetization via the Kerr effect (MOKE). Capping the wires significantly impacts their magnetic properties. Comparison of the magneto-optic response of the system at X-ray and optical energies reveals small differences that are attributed to the induced moment in the Pt substrate and Au capping layer not picked up by the element specific XMCD measurements. The sensitivity of RAS-MOKE is sufficient to allow the determination of the easy axis direction of the capped wires to within a few degrees. The results for a 6-atom-wide Co wire sample, capped with 6 ML of Au, are consistent with the capped wires possessing perpendicular magnetization.

  13. Gyroscopic behavior exhibited by the optical Kerr effect in bimetallic Au–Pt nanoparticles suspended in ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Fernández-Valdés, D.; Torres-Torres, C., E-mail: ctorrest@ipn.mx, E-mail: crstorres@yahoo.com.mx; Martínez-González, C. L. [Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Ingeniería Mecánica y Eléctrica Unidad Zacatenco (Mexico); Trejo-Valdez, M. [Instituto Politécnico Nacional, Escuela Superior de Ingeniería Química e Industrias Extractivas (Mexico); Hernández-Gómez, L. H. [Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Ingeniería Mecánica y Eléctrica Unidad Zacatenco (Mexico); Torres-Martínez, R. [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada Unidad Querétaro (Mexico)

    2016-07-15

    The modification in the third-order nonlinear optical response exhibited by rotating bimetallic Au–Pt nanoparticles in an ethanol solution was analyzed. The samples were prepared by a sol–gel processing route. The anisotropy associated to the elemental composition of the nanoparticles was confirmed by high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy measurements. The size of the nanoparticles varies in the range from 9 to 13 nm, with an average size of 11 nm. Changes in the spatial orientation of the nanomaterials automatically generated a variation in their plasmonic response evaluated by UV–Vis spectroscopy. A two-wave mixing experiment was conducted to explore an induced birefringence at 532 nm wavelength with nanosecond pulses interacting with the samples. A strong optical Kerr effect was identified to be the main responsible effect for the third-order nonlinear optical phenomenon exhibited by the nanoparticles. It was estimated that the rotation of inhomogeneous nanostructures can provide a remarkable change in the participation of different surface plasmon resonances, if they correspond to multimetallic nanoparticles. Potential applications for developing low-dimensional gyroscopic systems can be contemplated.

  14. Magneto-optical Kerr effect spectroscopy--a sensitive tool for investigating the molecular orientation in organic semiconductor films.

    Science.gov (United States)

    Bräuer, Björn; Fronk, Michael; Lehmann, Daniel; Zahn, Dietrich R T; Salvan, Georgeta

    2009-11-12

    The detection and control of the molecular growth mode is a key prerequisite for fabricating opto-electronic devices. In this work we present the magneto-optical Kerr effect (MOKE) spectroscopy to be a highly sensitive method for the detection of the molecular orientation. On the example of metal free phthalocyanine (H(2)Pc) in thin films, it will be shown that also for diamagnetic molecules a strong magneto-optical response can be expected. The growth mode and thus the intensity of the MOKE signal of H2Pc is strongly influenced by a templating effect using ultrathin layers of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA). From the MOKE spectra in the energy range from 1.5 to 5.0 eV and the optical constants, the Voigt constant of thin organic films was determined. From the strong in-plane/out-of-plane anisotropy of the optical constants and the value of the Voigt constant the average molecular tilt angle of H2Pc molecules with respect to the substrate plane can be obtained.

  15. Distinguishing Kerr naked singularities and black holes using the spin precession of a test gyro in strong gravitational fields

    CERN Document Server

    Chakraborty, Chandrachur; Kocherlakota, Prashant; Bhattacharyya, Sudip; Joshi, Pankaj S; Królak, Andrzej

    2016-01-01

    We consider here the precession of a test gyroscope in Kerr spacetimes to distinguish a naked singularity (NS) from black hole (BH). It is known that when the angular velocity of the gyro vanishes the spin precession frequency diverged at the ergo-surface. We show that it is possible to overcome this divergence by moving the gyro to the ergoregion with a non-zero angular velocity ($\\Omega_e$) in a definite range. Then the frequency is finite and regular on the boundary of the ergoregion and inside, for both the BH and NS. Specifically, if we move the gyro with a non-zero $\\Omega_e$ to an unknown astrophysical object, its precession diverges on the event horizon for a black hole, but finite and regular for NS. Therefore a genuine detection for the existence or otherwise of the event horizon becomes possible. We also show that for a near-extremal ($1 1.089$. For $1

  16. Nonclassicality and decoherence of photon-added squeezed coherent Schrödinger kitten states in a Kerr medium

    Science.gov (United States)

    Chakrabarti, R.; Yogesh, V.

    2018-01-01

    We study the nonclassicality of the evolution of a superposition of an arbitrary number of photon-added squeezed coherent Schrödinger cat states in a nonlinear Kerr medium. The nonlinearity of the medium gives rise to the periodicities of the quantities such as the Wehrl entropy SQ and the negativity δW of the W-distribution, and a series of local minima of these quantities arise at the rational submultiples of the said period. At these local minima the evolving state coincides with the transient Yurke-Stoler type of photon-added squeezed kitten states, which, for the choice of the phase space variables reflecting their macroscopic nature, show extremely short-lived behavior. Proceeding further we provide the closed form tomograms, which furnish the alternate description of these short-lived states. The increasing complexity in the kitten formations induces more number of interference terms that trigger more quantumness of the corresponding states. The nonclassical depth of the photon-added squeezed kitten states are observed to be of maximum possible value. Employing the Lindblad master equation approach we study the amplitude and the phase damping models for the initial state considered here. In the phase damping model the nonclassicality is not completely erased even in the long time limit when the dynamical quantities, such as the negativity δW and the tomogram, assume nontrivial asymptotic values.

  17. Biodetection Technologies for First Responders: 2014 Edition

    Energy Technology Data Exchange (ETDEWEB)

    Ozanich, Richard M.; Baird, Cheryl L.; Bartholomew, Rachel A.; Colburn, Heather A.; Straub, Tim M.; Bruckner-Lea, Cindy J.

    2014-03-28

    This report summarizes commercially-available, hand-portable technologies that can be used by first responders in the field. This is not meant to be an exhaustive list, nor an endorsement of any technology described herein. Rather, this report is meant to provide useful information about available technologies to help end-users make informed decisions about biodetection technology procurement and use. Information listed in this report is primarily vendor-provided; however, where possible it has been supplemented with additional information obtained from publications, reports, and websites. Manufacturers were given the chance to review summaries of their technologies from August through November 2013 to verify the accuracy of technical specifications, available references, and pricing.

  18. Responding to Indigenous Australian Sexual Assault

    Directory of Open Access Journals (Sweden)

    Janya McCalman

    2014-01-01

    Full Text Available Indigenous Australians experience a high prevalence of sexual assault, yet a regional sexual assault service found few Indigenous Australians accessed their services. This prompted exploration of how its services might be improved. A resultant systematic search of the literature is reported in this article. Seven electronic databases and seven websites were systematically searched for peer reviewed and gray literature documenting responses to the sexual assault of Indigenous Australians. These publications were then classified by response type and study type. Twenty-three publications met the inclusion criteria. They included studies of legal justice, media, and community-based and mainstream service responses for Indigenous survivors and perpetrators. We located program descriptions, measurement, and descriptive research, but no intervention studies. There is currently insufficient evidence to confidently prescribe what works to effectively respond to Indigenous Australian sexual assault. The study revealed an urgent need for researchers, Indigenous communities, and services to work together to develop the evidence base.

  19. Metastatic urachal cancer responding to FOLFOX chemotherapy.

    Science.gov (United States)

    Tran, Ben; McKendrick, Joe

    2010-04-01

    Metastatic urachal cancer is a rare disease and subsequently, does not have a defined systemic treatment. Although urachal cancer is most commonly adenocarcinoma and histologically similar to colon cancer, treatment selection is usually based upon location (the proximity of the urachus to the bladder) with bladder cancer regimens the most commonly prescribed. We report a case of metastatic urachal cancer where the immunohistochemical profile's similarities to colon cancer led to treatment with colon cancer specific chemotherapy. Our case is the first to report urachal cancer treated with and responding to modified FOLFOX6. In the age of targeted therapy, where molecular biology drives treatment selection, our case highlights that in rare tumors, when evidence is often lacking, a common sense approach can often prevail.

  20. Responding to the Challenge of True Uncertainty

    DEFF Research Database (Denmark)

    Hallin, Carina Antonia; Andersen, Torben Juul

    We construe a conceptual framework for responding effectively to true uncertainty in the business environment. We drill down to the essential micro-foundational capabilities - sensing and seizing of dynamic capabilities - and link them to classical strategic issue management theory with suggestions...... on how to operationalize these essential capabilities. By definition true uncertainty represents environmental conditions that are hard to foresee, which can catch the unprepared by surprise while presenting opportunities to the conscious organization. We demonstrate that organizations relying...... on aggregation of stakeholder sensing and predictions of emergent strategic issues can positively influence the two capabilities and help the firm adapt in the face of uncertainty and unpredictability. Robust measures predicating performance based on information from key stakeholders involved in the firm’s core...

  1. Methods of responding to healthcare security incidents.

    Science.gov (United States)

    Furnell, S; Gritzalis, D; Katsikas, S; Mavroudakis, K; Sanders, P; Warren, M

    1998-01-01

    This paper considers the increasing requirement for security in healthcare IT systems and, in particular, identifies the need for appropriate means by which healthcare establishments (HCEs) may respond to incidents. The main discussion focuses upon two significant initiatives that have been established in order to improve understanding and awareness of healthcare security issues. The first is the establishment of a dedicated Incident Reporting Scheme (IRS) for HCEs, enabling the level and types of security incidents faced within the healthcare community to be monitored and advice appropriately targeted. The second aspect presents a description of healthcare security World Wide Web service, which provides a comprehensive source of advice and guidance for establishments when trying to address and prevent IT security breaches. The discussion is based upon work that is currently being undertaken with the ISHTAR (Implementing Secure Healthcare Telematics Applications in Europe) project, as part of the Telematics Applications for Health programme of the European Commission.

  2. How to define responders in osteoarthritis

    Science.gov (United States)

    Cooper, Cyrus; Adachi, Jonathan D.; Bardin, Thomas; Berenbaum, Francis; Flamion, Bruno; Jonsson, Helgi; Kanis, John A.; Pelousse, Franz; Lems, Willem F.; Pelletier, Jean-Pierre; Martel-Pelletier, Johanne; Reiter, Susanne; Reginster, Jean-Yves; Rizzoli, René; Bruyère, Olivier

    2013-01-01

    Background Osteoarthritis is a clinical syndrome of failure of the joint accompanied by varying degrees of joint pain, functional limitation, and reduced quality of life due to deterioration of articular cartilage and involvement of other joint structures. Scope Regulatory agencies require relevant clinical benefit on symptoms and structure modification for registration of a new therapy as a disease-modifying osteoarthritis drug (DMOAD). An international Working Group of the European Society on Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) and International Osteoporosis Foundation was convened to explore the current burden of osteoarthritis, review current regulatory guidelines for the conduct of clinical trials, and examine the concept of responder analyses for improving drug evaluation in osteoarthritis. Findings The ESCEO considers that the major challenges in DMOAD development are the absence of a precise definition of the disease, particularly in the early stages, and the lack of consensus on how to detect structural changes and link them to clinically meaningful endpoints. Responder criteria should help identify progression of disease and be clinically meaningful. The ideal criterion should be sensitive to change over time and should predict disease progression and outcomes such as joint replacement. Conclusion The ESCEO considers that, for knee osteoarthritis, clinical trial data indicate that radiographic joint space narrowing >0.5 mm over 2 or 3 years might be a reliable surrogate measure for total joint replacement. On-going research using techniques such as magnetic resonance imaging and biochemical markers may allow the identification of these patients earlier in the disease process. PMID:23557069

  3. Cognitive Attributes of Adequate and Inadequate Responders to Reading Intervention in Middle School

    Science.gov (United States)

    Miciak, Jeremy; Stuebing, Karla K.; Vaughn, Sharon; Roberts, Greg; Barth, Amy Elizabeth; Fletcher, Jack M.

    2016-01-01

    No studies have investigated the cognitive attributes of middle school students who are adequate and inadequate responders to Tier 2 reading intervention. We compared students in Grades 6 and 7 representing groups of adequate responders (n = 77) and inadequate responders who fell below criteria in (a) comprehension (n = 54); (b) fluency (n = 45); and (c) decoding, fluency, and comprehension (DFC; n = 45). These students received measures of phonological awareness, listening comprehension, rapid naming, processing speed, verbal knowledge, and nonverbal reasoning. Multivariate comparisons showed a significant Group-by-Task interaction: the comprehension-impaired group demonstrated primary difficulties with verbal knowledge and listening comprehension, the DFC group with phonological awareness, and the fluency-impaired group with phonological awareness and rapid naming. A series of regression models investigating whether responder status explained unique variation in cognitive skills yielded largely null results consistent with a continuum of severity associated with level of reading impairment, with no evidence for qualitative differences in the cognitive attributes of adequate and inadequate responders. PMID:28579668

  4. Resurgence of responding after the cessation of response-independent reinforcement.

    Science.gov (United States)

    Epstein, R; Skinner, B F

    1980-10-01

    In an autoshaping experiment, food-deprived pigeons pecked rapidly at a moving dot that preceded the delivery of food. When the moving dot and food were no longer correlated, the rate of pecking dropped nearly to zero. When, subsequently, no food was given, pecking reappeared at a high rate (nearly 200 pecks per min for each subject), the rate dropping again in subsequent sessions. In two other experiments, designed to clarify relevant variables, the effect was replicated. The data suggest that although response-independent reinforcement produces a decrement in responding, it does not reduce a tendency to respond under other conditions.

  5. Primate dental ecology: How teeth respond to the environment.

    Science.gov (United States)

    Cuozzo, Frank P; Ungar, Peter S; Sauther, Michelle L

    2012-06-01

    Teeth are central for the study of ecology, as teeth are at the direct interface between an organism and its environment. Recent years have witnessed a rapid growth in the use of teeth to understand a broad range of topics in living and fossil primate biology. This in part reflects new techniques for assessing ways in which teeth respond to, and interact with, an organism's environment. Long-term studies of wild primate populations that integrate dental analyses have also provided a new context for understanding primate interactions with their environments. These new techniques and long-term field studies have allowed the development of a new perspective-dental ecology. We define dental ecology as the broad study of how teeth respond to, or interact with, the environment. This includes identifying patterns of dental pathology and tooth use-wear, as they reflect feeding ecology, behavior, and habitat variation, including areas impacted by anthropogenic disturbance, and how dental development can reflect environmental change and/or stress. The dental ecology approach, built on collaboration between dental experts and ecologists, holds the potential to provide an important theoretical and practical framework for inferring ecology and behavior of fossil forms, for assessing environmental change in living populations, and for understanding ways in which habitat impacts primate growth and development. This symposium issue brings together experts on dental morphology, growth and development, tooth wear and health, primate ecology, and paleontology, to explore the broad application of dental ecology to questions of how living and fossil primates interact with their environments. Copyright © 2012 Wiley Periodicals, Inc.

  6. Responder safety and health: preparing for future disasters.

    Science.gov (United States)

    Reissman, Dori B; Howard, John

    2008-01-01

    This article reviews lessons learned about managing the safety and health of workers who were involved in disaster response, recovery, and cleanup after the 2001 World Trade Center (WTC) disaster. The first two sections review ongoing responder health burdens and the tragic toll of this disaster from a worker safety and health perspective. The remaining sections address changes in federal infrastructure, response planning, and resources for protection of response and recovery personnel. Proper preparation includes pre-event and "just-in-time" disaster-worker training on likely hazards, organizational assets for hazard monitoring, and hands-on instruction in the use of assigned protective equipment. Good planning includes predeployment medical review to ensure "fitness for duty" and considers the following: (1) personal risk factors, (2) hazards likely to be associated with particular field locations, and (3) risks involved with assigned tasks (eg, workload and pace, work/rest cycles, available resources, and team/supervisory dynamics). Planning also should address worker health surveillance, medical monitoring, and availability of medical care (including mental health services). Disaster safety managers should anticipate likely hazards within planning scenarios and prepare asset inventories to facilitate making timely safety decisions. Disaster safety management begins immediately and provides ongoing real-time guidance to incident leadership at all levels of government. Robust standards must be met to reliably protect workers/responders. An integrated and measurable multiagency safety management function must be built into the incident command system before an incident occurs. This function delineates roles and responsibilities for rapid exposure assessments, ensuring cross-agency consistency in data interpretation, and timely, effective communication of information and control strategies. The ability to perform this safety management function should be tested and

  7. Chromatin proteins: key responders to stress.

    Directory of Open Access Journals (Sweden)

    Karen T Smith

    Full Text Available Environments can be ever-changing and stresses are commonplace. In order for organisms to survive, they need to be able to respond to change and adapt to new conditions. Fortunately, many organisms have systems in place that enable dynamic adaptation to immediate stresses and changes within the environment. Much of this cellular response is coordinated by modulating the structure and accessibility of the genome. In eukaryotic cells, the genome is packaged and rolled up by histone proteins to create a series of DNA/histone core structures known as nucleosomes; these are further condensed into chromatin. The degree and nature of the condensation can in turn determine which genes are transcribed. Histones can be modified chemically by a large number of proteins that are thereby responsible for dynamic changes in gene expression. In this Primer we discuss findings from a study published in this issue of PLoS Biology by Weiner et al. that highlight how chromatin structure and chromatin binding proteins alter transcription in response to environmental changes and stresses. Their study reveals the importance of chromatin in mediating the speed and amplitude of stress responses in cells and suggests that chromatin is a critically important component of the cellular response to stress.

  8. UK medicines regulation: responding to current challenges.

    Science.gov (United States)

    Richards, Natalie; Hudson, Ian

    2016-12-01

    The medicines regulatory environment is evolving rapidly in response to the changing environment. Advances in science and technology have led to a vast field of increasingly complicated pharmaceutical and medical device products; increasing globalization of the pharmaceutical industry, advances in digital technology and the internet, changing patient populations, and shifts in society also affect the regulatory environment. In the UK, the Medicines and Healthcare products Regulatory Agency (MHRA) regulates medicines, medical devices and blood products to protect and improve public health, and supports innovation through scientific research and development. It works closely with other bodies in a single medicines network across Europe and takes forward UK health priorities. This paper discusses the range of initiatives in the UK and across Europe to support innovation in medicines regulation. The MHRA leads a number of initiatives, such as the Innovation Office, which helps innovators to navigate the regulatory processes to progress their products or technologies; and simplification of the Clinical Trials Regulations and the Early Access to Medicines Scheme, to bring innovative medicines to patients faster. The Accelerated Access Review will identify reforms to accelerate access for National Health Service patients to innovative medicines and medical technologies. PRIME and Adaptive Pathways initiatives are joint endeavours within the European regulatory community. The MHRA runs spontaneous reporting schemes and works with INTERPOL to tackle counterfeiting and substandard products sold via the internet. The role of the regulator is changing rapidly, with new risk-proportionate, flexible approaches being introduced. International collaboration is a key element of the work of regulators, and is set to expand. © 2016 The British Pharmacological Society.

  9. Surface microstructure and magnetic behavior in FeSiB amorphous ribbons from magneto-optical Kerr effect

    Energy Technology Data Exchange (ETDEWEB)

    Zivotsky, O., E-mail: ondrej.zivotsky@post.cz [Department of Physics, Technical University of Ostrava, 17.listopadu 15, 708 33 Ostrava-Poruba (Czech Republic); Hendrych, A.; Klimsa, L. [Department of Physics, Technical University of Ostrava, 17.listopadu 15, 708 33 Ostrava-Poruba (Czech Republic); Jiraskova, Y.; Bursik, J. [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, 616 62 Brno (Czech Republic); Gomez, J.A.M. [Department of Physics and Astronomy, Division of Nuclear Material Physics, Ghent University, Proeftuinstraat 86, 9000 Ghent (Belgium); Janickovic, D. [Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava (Slovakia)

    2012-02-15

    The magneto-optical Kerr effect (MOKE) completed by other surface sensitive methods as integral low-energy and conversion electron Moessbauer spectroscopy, scanning and transmission electron microscopy and by X-ray diffraction have been used with the aim to trace the surface microstructure and magnetic properties of FeSiB amorphous ribbons prepared by planar flow casting. The general composition of studied samples is Fe{sub 80}Si{sub x}B{sub 20-x}, where x=4, 6, 8, 10 at.%. It is shown that MOKE used for magnetization, hysteresis loop, and domain structure determination is highly beneficial in a detection of both surface crystallization and local ordering of atoms into magnetically different clusters of amorphous structure. Moreover, a combination of blue and red laser with different penetration depths yields unique results concerning the surface anisotropy and depth sensitivity. In the case of samples with 4, 6, and 8 at.% Si MOKE detects two magnetically different phases diverging in coercivity values H{sub c}, however, not varying with the sample composition. These phases have been identified by Moessbauer measurements as FeSi and FeB clusters. Their relationship changes with Si concentration. On the other hand, a strong increase in the surface H{sub c} found for the sample with 10 at.% Si has indicated a nanocrystallization. It was confirmed by electron microscopy, Moessbauer and X-ray diffraction results. The size of nanocrystals has varied between 200 nm and 500 nm. - Highlights: > Amorphous FeSiB samples exhibit an existence of short-ordered FeSi and FeB clusters. > Cluster sizes are lower than 2 nm. > For higher Si concentrations clusters are transformed into the nanocrystals.

  10. Smart radio: spectrum access for first responders

    Science.gov (United States)

    Silvius, Mark D.; Ge, Feng; Young, Alex; MacKenzie, Allen B.; Bostian, Charles W.

    2008-04-01

    This paper details the Wireless at Virginia Tech Center for Wireless Telecommunications' (CWT) design and implementation of its Smart Radio (SR) communication platform. The CWT SR can identify available spectrum within a pre-defined band, rendezvous with an intended receiver, and transmit voice and data using a selected quality of service (QoS). This system builds upon previous cognitive technologies developed by CWT for the public safety community, with the goal of providing a prototype mobile communications package for military and public safety First Responders. A master control (MC) enables spectrum awareness by characterizing the radio environment with a power spectrum sensor and an innovative signal detection and classification module. The MC also enables spectrum and signal memory by storing sensor results in a knowledge database. By utilizing a family radio service (FRS) waveform database, the CWT SR can create a new communication link on any designated FRS channel frequency using FM, BPSK, QPSK, or 8PSK modulations. With FM, it supports analog voice communications with legacy hand-held FRS radios. With digital modulations, it supports IP data services, including a CWT developed CVSD-based VoIP protocol. The CWT SR coordinates spectrum sharing between analog primary users and digital secondary users by applying a simple but effective channel-change protocol. It also demonstrates a novel rendezvous protocol to facilitate the detection and initialization of communications links with neighboring SR nodes through the transmission of frequency-hopped rendezvous beacons. By leveraging the GNU Radio toolkit, writing key modules entirely in Python, and utilizing the USRP hardware front-end, the CWT SR provides a dynamic spectrum test bed for future smart and cognitive radio research.

  11. Femtosecond Raman-Induced Kerr Effect Study of Temperature-Dependent Intermolecular Dynamics in Imidazolium-Based Ionic Liquids: Effects of Anion Species and Cation Alkyl Groups.

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Avazpour, L.; Toroghinejad, M.R. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Shokrollahi, H., E-mail: Shokrollahi@sutech.ac.ir [Electroceramics Group, Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz 13876-71557 (Iran, Islamic Republic of)

    2016-11-30

    Highlights: • The nanostructured rare earth doped Co-ferrite thin film was synthesized by the sol–gel method. • The coercivity of as high as 1.8 kOe is achieved for 20% substituted cobalt ferrite. • The average particle diameter of particulate film is decreasing by increasing substitute content. • Kerr spectra of films shifted to higher energies. • Kerr rotation angle increased to 1.65° for 0.1 Eu doped thin film. - Abstract: A series of rare-earth (RE)-doped nanocrystalline Co{sub x} RE{sub (1−x)} Fe{sub 2}O{sub 4} (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 RE{sup 3+} 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 Co{sub x} RE{sub (1−x)} Fe{sub 2}O{sub 4} 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

  13. Nonlinear Dynamics and Exact Traveling Wave Solutions of the Higher-Order Nonlinear Schrödinger Equation with Derivative Non-Kerr Nonlinear Terms

    Directory of Open Access Journals (Sweden)

    Heng Wang

    2016-01-01

    Full Text Available By using the method of dynamical system, the exact travelling wave solutions of the higher-order nonlinear Schrödinger equation with derivative non-Kerr nonlinear terms are studied. Based on this method, all phase portraits of the system in the parametric space are given with the aid of the Maple software. All possible bounded travelling wave solutions, such as solitary wave solutions, kink and anti-kink wave solutions, and periodic travelling wave solutions, are obtained, respectively. The results presented in this paper improve the related previous conclusions.

  14. Giant enhancement of the transverse magneto-optical Kerr effect through the coupling of ɛ -near-zero and surface plasmon polariton modes

    Science.gov (United States)

    Girón-Sedas, J. A.; Reyes Gómez, F.; Albella, Pablo; Mejía-Salazar, J. R.; Oliveira, Osvaldo N.

    2017-08-01

    We demonstrate a concept for the giant enhancement of the transverse magneto-optical Kerr effect (TMOKE), with amplitudes reaching the maximum theoretical values of ±1 . The concept exploits the strong electromagnetic field localization in ɛ -near-zero metamaterials to excite surface plasmon resonances with no need of a prism or grating coupler, thus opening routes for magneto-optical devices amenable to miniaturization. A demonstration of the capability of the enhancement mechanism is presented in which giant TMOKE values can be used for sensing and biosensing.

  15. Total Conserved Charges of Kerr-Newman Spacetimes in Gravity Theory Using a Poincaré Gauge Version of the Teleparallel Equivalent of General Relativity

    Directory of Open Access Journals (Sweden)

    Gamal G. L. Nashed

    2013-01-01

    Full Text Available The total conserved charges of several tetrad spacetimes, generating the Kerr-Newman (KN metric, are calculated using the approach of invariant conserved currents generated by an arbitrary vector field that reproduces a diffeomorphism on the spacetime. The accompanying charges of some tetrads give the known value of energy and angular momentum, while those of other tetrads give, in addition to the unknown format charges, a divergent entity. Therefore, regularized expressions are considered also to get the commonly known form of conserved charges of KN.

  16. Data for First Responder Use of Photoionization Detectors for Vapor Chemical Constituents

    Energy Technology Data Exchange (ETDEWEB)

    Keith A. Daum; Matthew G. Watrous; M. Dean Neptune; Daniel I. Michael; Kevin J. Hull; Joseph D. Evans

    2006-11-01

    First responders need appropriate measurement technologies for evaluating incident scenes. This report provides information about photoionization detectors (PIDs), obtained from manufacturers and independent laboratory tests, and the use of PIDs by first responders, obtained from incident commanders in the United States and Canada. PIDs are valued for their relatively low cost, light weight, rapid detection response, and ease of use. However, it is clear that further efforts are needed to provide suitable instruments and decision tools to incident commanders and first responders for assessing potential hazardous chemical releases. Information provided in this report indicates that PIDs should always be part of a decision-making context in which other qualitative and more definitive tests and instruments are used to confirm a finding. Possible amelioratory actions ranging from quick and relatively easy fixes to those requiring significant additional effort are outlined in the report.

  17. Community first responders and responder schemes in the United Kingdom: systematic scoping review.

    Science.gov (United States)

    Phung, Viet-Hai; Trueman, Ian; Togher, Fiona; Orner, Roderick; Siriwardena, A Niroshan

    2017-06-19

    Community First Responder (CFR) schemes support lay people to respond to medical emergencies, working closely with ambulance services. They operate widely in the UK. There has been no previous review of UK literature on these schemes. This is the first systematic scoping review of UK literature on CFR schemes, which identifies the reasons for becoming a CFR, requirements for training and feedback and confusion between the CFR role and that of ambulance service staff. This study also reveals gaps in the evidence base for CFR schemes. We conducted a systematic scoping review of the published literature, in the English language from 2000 onwards using specific search terms in six databases. Narrative synthesis was used to analyse article content. Nine articles remained from the initial search of 15,969 articles after removing duplicates, title and abstract and then full text review. People were motivated to become CFRs through an altruistic desire to help others. They generally felt rewarded by their work but recognised that the help they provided was limited by their training compared with ambulance staff. There were concerns about the possible emotional impact on CFRs responding to incidents. CFRs felt that better feedback would enhance their learning. Ongoing training and support were viewed as essential to enable CFRs to progress. They perceived that public recognition of the CFR role was low, patients sometimes confusing them with ambulance staff. Relationships with the ambulance service were sometimes ambivalent due to confusion over roles. There was support for local autonomy of CFR schemes but with greater sharing of best practice. Most studies dated from 2005 and were descriptive rather than analytical. In the UK and Australia CFRs are usually lay volunteers equipped with basic skills for responding to medical emergencies, whereas in the US they include other emergency staff as well as lay people. Opportunities for future research include exploring

  18. Support Framework for First Responder Family Members: A Proposed Model for Increasing Responder Effectiveness

    Science.gov (United States)

    2009-12-01

    always been consistent regarding disaster preparedness. The International Pentecostal Holiness Church article titled Family Preparedness for Disaster...prepared by developing a family disaster plan and when a disaster occurs, work the prearranged plan (International Pentecostal Holiness Church, n.d...would fall under the auspices of “first responder.” It was also noted that there is movement with a blue card certification process for first

  19. Network Analysis of Toxic Chemicals and Symptoms: Implications for Designing First-Responder Systems

    OpenAIRE

    Bhavnani, Suresh K; Abraham, Annie; Demeniuk, Christopher; Gebrekristos, Messeret; Gong, Abe; Nainwal, Satyendra; Vallabha, Gautam K.; Richardson, Rudy J.

    2007-01-01

    The rapid and accurate identification of toxic chemicals is critical for saving lives in emergency situations. However, first-responder systems such as WISER typically require a large number of inputs before a chemical can be identified. To address this problem, we used networks to visualize and analyze the complex relationship between toxic chemicals and their symptoms. The results explain why current approaches require a large number of inputs and help to identify regularities related to th...

  20. Improving Situational Awareness for First Responders via Mobile Computing

    Science.gov (United States)

    Betts, Bradley J.; Mah, Robert W.; Papasin, Richard; Del Mundo, Rommel; McIntosh, Dawn M.; Jorgensen, Charles

    2006-01-01

    This project looks to improve first responder incident command, and an appropriately managed flow of situational awareness using mobile computing techniques. The prototype system combines wireless communication, real-time location determination, digital imaging, and three-dimensional graphics. Responder locations are tracked in an outdoor environment via GPS and uploaded to a central server via GPRS or an 802. II network. Responders can also wireless share digital images and text reports, both with other responders and with the incident commander. A pre-built three dimensional graphics model of the emergency scene is used to visualize responder and report locations. Responders have a choice of information end points, ranging from programmable cellular phones to tablet computers. The system also employs location-aware computing to make responders aware of particular hazards as they approach them. The prototype was developed in conjunction with the NASA Ames Disaster Assistance and Rescue Team and has undergone field testing during responder exercises at NASA Ames.

  1. 16 CFR 5.62 - Hearing rights of respondent.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Hearing rights of respondent. 5.62 Section 5.62 Commercial Practices FEDERAL TRADE COMMISSION ORGANIZATION, PROCEDURES AND RULES OF PRACTICE... rights of respondent. In any hearing under this subpart, the respondent shall have the right: (a) To be...

  2. CIRUN: Climate Information Responding to User Needs

    Science.gov (United States)

    Busalacchi, A. J.

    2009-12-01

    The Earth System will experience real climate change over the next 50 years, exceeding the scope of natural climate variability. A paramount question facing society is how to adapt to this certainty of climate variability and change. In response, OSTP and NOAA are considering how comprehensive climate services would best inform decisions about adaptation. Similarly, NASA is considering the optimal configuration of the next generation of Earth, environmental, and climate observations to be deployed over the coming 10-20 years. Moreover, much of the added-value information for specific climate-related decisions will be provided by private, academic and non-governmental organizations. In this context, over the past several years the University of Maryland has established the CIRUN (Climate Information: Responding to User Needs) initiative to identify the nature of national needs for climate information and services from a decision support perspective. To date, CIRUN has brought together decisionmakers in a number of sectors to help understand their perspectives on climate with the goal of improving the usefulness of climate information, observations and prediction products to specific user communities. CIRUN began with a major workshop in October 2007 that convened 430 participants in agriculture, parks and recreation, terrestrial ecosystems, insurance/investment, energy, national security, state/local/municipal, water, human health, commerce and manufacturing, transportation, and coastal/marine sectors. Plenary speakers such as Norman Augustine, R. James Woolsey, James Mahoney, and former Senator Joseph Tydings, breakout panel sessions, and participants provided input based on the following: - How would you characterize the exposure or vulnerability to climate variability or change impacting your organization? - Does climate variability and/or change currently factor into your organization's objectives or operations? - Are any of your existing plans being affected by

  3. A new method for rapid Canine retraction

    Directory of Open Access Journals (Sweden)

    "Khavari A

    2001-06-01

    Full Text Available Distraction osteogenesis method (Do in bone lengthening and rapid midpalatal expansion have shown the great ability of osteognic tissues for rapid bone formation under distraction force and special protocol with optimum rate of one millimeter per day. Periodontal membrane of teeth (PDM is the extension of periostium in the alveolar socked. Orthodontic force distracts PDM fibers in the tension side and then bone formation will begin.Objects: Rapid retraction of canine tooth into extraction space of first premolar by DO protocol in order to show the ability of the PDM in rapid bone formation. The other objective was reducing total orthodontic treatment time of extraction cases.Patients and Methods: Tweleve maxillary canines in six patients were retracted rapidly in three weeks by a custom-made tooth-born appliance. Radiographic records were taken to evaluate the effects of heavy applied force on canine and anchorage teeth.Results: Average retraction was 7.05 mm in three weeks (2.35 mm/week. Canines rotated distal- in by mean 3.5 degrees.Anchorage loss was from 0 to 0.8 mm with average of 0.3 mm.Root resorption of canines was negligible, and was not significant clinically. Periodontium was normal after rapid retraction. No hazard for pulp vitality was observed.Discussion: PDM responded well to heavy distraction force by Do protocol. Rapid canine retraction seems to be a safe method and can considerabely reduce orthodontic time.

  4. The Auditory P3 in Antidepressant Pharmacotherapy Treatment Responders, Non-Responders and Controls

    Science.gov (United States)

    Jaworska, Natalia; De Somma, Elisea; Blondeau, Claude; Tessier, Pierre; Norris, Sandhaya; Fusee, Wendy; Smith, Dylan; Blier, Pierre; Knott, Verner

    2013-01-01

    Event-related potentials (ERPs), derived from electroencephalographic (EEG) recordings, can index electrocortical activity related to cognitive operations. The fronto-central P3a ERP is involved in involuntary processing of novel auditory information, whereas the parietal P3b indexes controlled attention processing. The amplitude of the auditory P3b has been found to be decreased in major depressive disorder (MDD). However, few studies have examined the relationship between the P3b, the related P3a, and antidepressant treatment response. We tested 53 unmedicated individuals (25 females) with MDD as well as 43 non-depressed controls (23 females) on the novelty oddball task, wherein infrequent deviant (target) and frequent standard (non-target) tones were presented, along with infrequent novel (non-target/distractor) sounds. The P3a and P3b ERPs were assessed to the novel and target sounds, respectively, as were accompanying behavioural performance measures. Depression ratings and antidepressant response status were assessed following 12 weeks of pharmacotherapy with three different regimens. Antidepressant treatment non-responders had smaller baseline P3a/b amplitudes than responders and healthy controls. Baseline P3b amplitude also weakly predicted the extent of depression rating changes by week 12. Females exhibited larger P3a/b amplitudes than males. With respect to task performance, controls had more target hits than treatment non-responders. ERP measures correlated with clinical changes in males and with behavioural measures in females. These results suggest that greater (or control-like) baseline P3a/b amplitudes are associated with a positive antidepressant response, and that gender differences characterize the P3 and, hence, basic attentive processes. PMID:23664712

  5. Auditory P3 in antidepressant pharmacotherapy treatment responders, non-responders and controls.

    Science.gov (United States)

    Jaworska, Natalia; De Somma, Elisea; Blondeau, Claude; Tessier, Pierre; Norris, Sandhaya; Fusee, Wendy; Smith, Dylan; Blier, Pierre; Knott, Verner

    2013-11-01

    Event-related potentials (ERPs), derived from electroencephalographic (EEG) recordings, can index electrocortical activity related to cognitive operations. The fronto-central P3a ERP is involved in involuntary processing of novel auditory information, whereas the parietal P3b indexes controlled attention processing. The amplitude of the auditory P3b has been found to be decreased in major depressive disorder (MDD). However, few studies have examined the relations between the P3b, the related P3a, and antidepressant treatment response. We tested 53 unmedicated individuals (25 females) with MDD, as well as 43 non-depressed controls (23 females) on the novelty oddball task, wherein infrequent deviant (target) and frequent standard (non-target) tones were presented, along with infrequent novel (non-target/distractor) sounds. The P3a and P3b ERPs were assessed to novel and target sounds, respectively, as were their accompanying behavioral performance measures. Depression ratings and the antidepressant response status were assessed following 12 weeks of pharmacotherapy with three different regimens. Antidepressant treatment non-responders had smaller baseline P3a/b amplitudes than responders and healthy controls. Baseline P3b amplitude also weakly predicted the extent of depression rating changes by week 12. Females exhibited larger P3a/b amplitudes than males. With respect to task performance, controls had more target hits than treatment non-responders. ERP measures correlated with clinical changes in males and with behavioral measures in females. These results suggest that greater (or control-like) baseline P3a/b amplitudes are associated with a positive antidepressant response, and that gender differences characterize the P3 and, by extension, basic attentive processes. Copyright © 2013 Elsevier B.V. and ECNP. All rights reserved.

  6. Impact of loss on the light propagation in 1D optical waveguide array in the presence of Kerr-type nonlinearity

    Science.gov (United States)

    Khazaei Nezhad, M.; Golshani, M.; Mirshamsi, D.

    2017-12-01

    The interplay between radiation loss (diagonal and off-diagonal) and Kerr-type nonlinearity on the light propagation in 1D array of nonlinear dissipative optical waveguides are investigated numerically. Our results show that, at low nonlinear parameters, the diagonal loss only reduces the light intensity in the guides and does not affect the ballistic regime of light spreading. However, for nonlinear parameters above a critical value, the transition from the localized to the ballistic regime can be observed, after certain propagation distance. The study of the interplay between off-diagonal loss term and Kerr type nonlinearity, demonstrates that the results depend mainly to the nonlinear parameter strength. In this case, and for low strength of nonlinearity, the transition from ballistic to diffusive regime is observed after a critical propagation distance, while, spreading from localized to diffusive regime occurs at high nonlinear parameters (above the critical one). In addition, we have examined the impact of the both diagonal and off-diagonal losses in highly nonlinear optical lattices. In this case, by increasing the propagation distance, three different regimes of light spreading (from localized to the ballistic, and then, from ballistic to the diffusive) can be observed. Both critical propagation distances in which these transitions occur increase by the magnitude of the nonlinear parameter, while, decrease by the enhancement of the loss coefficients.

  7. Rapid Prototyping Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The ARDEC Rapid Prototyping (RP) Laboratory was established in December 1992 to provide low cost RP capabilities to the ARDEC engineering community. The Stratasys,...

  8. Rapid Hepatitis B Vaccination in Adults

    Directory of Open Access Journals (Sweden)

    Mansur Özcan

    2004-01-01

    Full Text Available Vaccination is a very important method in prevention of HBV.Especially rapid immunization takes an important place in subjects at highrisk. We have injected HBV vaccine to health workers who are attending inour hospital by rapid immunisation programme (at 0, 1 and 2 months andaimed to identify it’s efficiacy. Eighty seven subjects (69% male, 31%female were included to our study. Median age was 34 for male and 32 forwomen. We obtained 90% achievement of immunity rate after theprogramme finished. There were no significant difference between maleend female groups, and age groups. The non-responder rate was 11.6% inmale, and 7.4% in female. This rate was 6% in under 40 years old group,and 22.7% in 40 or older group. This difference was significant in twogroups statistically (p=0.02. The rapid immunization programme, weperformed has nearly the same success results as in standard programme.

  9. PAPIO URSINUS KERR, 1792

    African Journals Online (AJOL)

    calls were typical and differed from the alert warning call. Field example: 16.1.68 - 0500 h: 0500. A female of W troop sat alone with her dead infant at the main sleeping place. She groomed the baby intensively. 0516. The female looked around continually uttering communication calls. 0518. Carrying the dead infant, the ...

  10. POLITENESS STRATEGIES IN RESPONDING TO COMPLIMENTS IN JAVANESE

    OpenAIRE

    Sukarno Sukarno

    2015-01-01

    Abstract:  Javanese has been studied from many different perspectives. However, no one discusses how Javanese respond to compliments politely. The aim of this study is to investigate the politeness strategies as applied to respond to compliments by the Javanese people in Jember, East Java. The notion of politeness plays crucial role in the realization of speech acts (utterances and verbal communication) in Javanese, such as responding to compliements. As utterances and verbal communications s...

  11. Connecting, Protecting, and Informing the Next Generation of First Responders

    Science.gov (United States)

    2015-12-10

    Department of Homeland Security Science and Technology Directorate (S&T) First Responder Group‘s (FRG) cutting-edge Next Generation First Responder...smartphones, responders have access to a powerful computer that has potential far beyond smartphones’ conventional uses. Michael Flood, a developer...for flight on an indoor-capable drone required a collaboration of aero, electrical, controls, and mechanical engineers and physicists .” Complementing

  12. No impact of repeated extinction exposures on operant responding maintained by different reinforcer rates.

    Science.gov (United States)

    Bai, John Y H; Podlesnik, Christopher A

    2017-05-01

    Greater rates of intermittent reinforcement in the presence of discriminative stimuli generally produce greater resistance to extinction, consistent with predictions of behavioral momentum theory. Other studies reveal more rapid extinction with higher rates of reinforcers - the partial reinforcement extinction effect. Further, repeated extinction often produces more rapid decreases in operant responding due to learning a discrimination between training and extinction contingencies. The present study examined extinction repeatedly with training with different rates of intermittent reinforcement in a multiple schedule. We assessed whether repeated extinction would reverse the pattern of greater resistance to extinction with greater reinforcer rates. Counter to this prediction, resistance to extinction was consistently greater across twelve assessments of training followed by six successive sessions of extinction. Moreover, patterns of responding during extinction resembled those observed during satiation tests, which should not alter discrimination processes with repeated testing. These findings join others suggesting operant responding in extinction can be durable across repeated tests. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Rapid Airplane Parametric Input Design (RAPID)

    Science.gov (United States)

    Smith, Robert E.

    1995-01-01

    RAPID is a methodology and software system to define a class of airplane configurations and directly evaluate surface grids, volume grids, and grid sensitivity on and about the configurations. A distinguishing characteristic which separates RAPID from other airplane surface modellers is that the output grids and grid sensitivity are directly applicable in CFD analysis. A small set of design parameters and grid control parameters govern the process which is incorporated into interactive software for 'real time' visual analysis and into batch software for the application of optimization technology. The computed surface grids and volume grids are suitable for a wide range of Computational Fluid Dynamics (CFD) simulation. The general airplane configuration has wing, fuselage, horizontal tail, and vertical tail components. The double-delta wing and tail components are manifested by solving a fourth order partial differential equation (PDE) subject to Dirichlet and Neumann boundary conditions. The design parameters are incorporated into the boundary conditions and therefore govern the shapes of the surfaces. The PDE solution yields a smooth transition between boundaries. Surface grids suitable for CFD calculation are created by establishing an H-type topology about the configuration and incorporating grid spacing functions in the PDE equation for the lifting components and the fuselage definition equations. User specified grid parameters govern the location and degree of grid concentration. A two-block volume grid about a configuration is calculated using the Control Point Form (CPF) technique. The interactive software, which runs on Silicon Graphics IRIS workstations, allows design parameters to be continuously varied and the resulting surface grid to be observed in real time. The batch software computes both the surface and volume grids and also computes the sensitivity of the output grid with respect to the input design parameters by applying the precompiler tool

  14. Increasing Poverty: How Do Leaders in One Suburban District Respond?

    Science.gov (United States)

    Spencer, Jennifer Dawn

    2014-01-01

    This dissertation addresses the question of how suburban school district leaders in one large Midwestern school district respond to increasing student poverty. The purpose of this study was to determine how suburban school district leaders respond to increasing student poverty in their decision making and actions. Data for this study came from one…

  15. 76 FR 68828 - Pipeline Safety: Emergency Responder Forum

    Science.gov (United States)

    2011-11-07

    ... Administration [Docket ID PHMSA-2011-0295] Pipeline Safety: Emergency Responder Forum AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA), DOT. ACTION: Notice of Forum. SUMMARY: PHMSA is co-sponsoring a one-day Emergency Responder Forum with the National Association of Pipeline Safety...

  16. Training Law Enforcement Officials on Responding to Equine Calls

    Science.gov (United States)

    Anderson, Kathleen P.; Stauffer, Gary; Stauffer, Monte; Anderson, Doug; Biodrowski, Kristie

    2016-01-01

    The occurrence of equine abuse/neglect cases is an ongoing issue. However, officials responding to equine cases are rarely experienced in handling horses. Therefore, workshops teaching basic horse husbandry were offered to better equip and prepare officials to respond to equine cases. Trainings consisted of both classroom and hands-on sessions.…

  17. 45 CFR 612.4 - Responding to requests.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Responding to requests. 612.4 Section 612.4 Public... RECORDS AND INFORMATION § 612.4 Responding to requests. (a) Monitoring of requests. The NSF Office of the... General, that Office will control incoming requests made directly or referred to it, dispatch response...

  18. Transforming Higher Education in the Information Age: Presidents Respond.

    Science.gov (United States)

    Breslin, Richard D.; And Others

    1991-01-01

    College presidents respond to an article by Richard Nolan challenging college and university presidents and chancellors to transform their campuses for survival and competitive advantage in the information age. Respondents include Richard D. Breslin, David M. Clarke, Joseph Cronin, Thomas Ehrlich, Donald N. Langenberg, Harold McAninch, and Donald…

  19. Collaboration and interaction of first responders with the general public

    NARCIS (Netherlands)

    Emmerik, M. van; Dinesen, C.; Rijk, R. van; Bird, M.; Wester, M.; Hansen, L.J.; Vinther-Larsen, L.; Padron, C.; Boswinkel, R.; Ven, J. van de

    2016-01-01

    There is an increased focus on the need for collaboration between first responders and the general public. This type of collaboration requires soft skills that are not necessarily included in more traditional command and control trainings for first responders. Learning to collaborate with the

  20. Responding to the double implication of telemarketers' opinion queries

    NARCIS (Netherlands)

    Mazeland, H

    During a call, telemarketers sometimes solicit respondent's opinions about a product or service. This turns out to be a query with multiple implications, and respondents are alive to them. On the one hand, the recipient orients to a local preference to evaluate the telemarketer's product positively.

  1. Understanding and Responding to Adolescent Girls' Online Cruelty

    Science.gov (United States)

    Sokal, Laura

    2012-01-01

    Many school counsellors have identified "cyber-bullying" among adolescent girls as a growing concern. In order to respond to this issue, this article begins with a new model of cyber-communications from the unique perspective of adolescent girls. Next, it explores the limitations of responding to this model, based on current understandings of…

  2. Responding electronically to student drafts on campus: Dis ...

    African Journals Online (AJOL)

    This article reports on an investigation into whether writing centre (WC) respondents at an institution of Higher Education (HE) encourage or discourage draft dialogue (a conversation in writing) with students submitting drafts electronically to the WC for feedback. The writing respondents insert local feedback responses or ...

  3. Dissociating indifferent, directional, and extreme responding in personality data

    DEFF Research Database (Denmark)

    Zettler, Ingo; Lang, Jonas W B; Hülsheger, Ute R

    2015-01-01

    supporting the hypothesis that Honesty-Humility is negatively linked to extreme responding. CONCLUSION: In Likert-based personality data, applying the three-process model can unveil individual differences in the response process. This article is protected by copyright. All rights reserved.......- and observer reports of personality traits. The three-process model captures indifferent, directional, and extreme responding. Substantively, we hypothesize that, and test whether, trait Honesty-Humility is negatively linked to extreme responding. METHOD: We applied the three-process model to personality data...... of N = 577 dyads (self- and observer reports of the HEXACO Personality Inventory-Revised) of Dutch and German respondents. RESULTS: First, we provide evidence that indifferent, directional, and extreme responding can be separated from each other in personality data through the use of the three...

  4. Agreement among response to intervention criteria for identifying responder status.

    Science.gov (United States)

    Barth, Amy E; Stuebing, Karla K; Anthony, Jason L; Denton, Carolyn A; Mathes, Patricia G; Fletcher, Jack M; Francis, David J

    2008-09-01

    In order to better understand the extent to which operationalizations of response to intervention (RTI) overlap and agree in identifying adequate and inadequate responders, an existing database of 399 first grade students was evaluated in relation to cut-points, measures, and methods frequently cited for the identification of inadequate responders to instruction. A series of 543 2x2 measures of association (808 total comparisons) were computed to address the agreement of different operationalizations of RTI. The results indicate that agreement is generally poor and that different methods tend to identify different students as inadequate responders, although agreement for identifying adequate responders is higher. Approaches to the assessment of responder status must use multiple criteria and avoid formulaic decision making.

  5. High-power Kerr-lens mode-locked Yb:YAG thin-disk oscillator in the positive dispersion regime.

    Science.gov (United States)

    Pronin, O; Brons, J; Grasse, C; Pervak, V; Boehm, G; Amann, M-C; Apolonski, A; Kalashnikov, V L; Krausz, F

    2012-09-01

    We demonstrate a self-starting Kerr-lens mode-locked (KLM) Yb:YAG thin-disk oscillator operating in the regime of positive intracavity group-delay dispersion (GDD). It delivers 1.7 ps pulses at an average power of 17 W and a repetition rate of 40 MHz. Dispersive mirrors compress the pulses to a duration of 190 fs (assuming sech2 shape; Fourier limit: 150 fs) at an average power level of 11 W. To our knowledge, this is the first KLM thin-disk oscillator with positive GDD. Output powers of up to 30 W were achieved with an increased output coupler transmission and intracavity GDD. We demonstrate increase of the pulse energy with increasing positive intracavity GDD, limited by difficulties in initiating mode-locking.

  6. Kerr nonlinearity mitigation in 5 × 28-GBd PDM 16-QAM signal transmission over a dispersion-uncompensated link with backward-pumped distributed Raman amplification.

    Science.gov (United States)

    Sackey, Isaac; Da Ros, Francesco; Jazayerifar, Mahmoud; Richter, Thomas; Meuer, Christian; Nölle, Markus; Molle, Lutz; Peucheret, Christophe; Petermann, Klaus; Schubert, Colja

    2014-11-03

    We present experimental and numerical investigations of Kerr nonlinearity compensation in a 400-km standard single-mode fiber link with distributed Raman amplification with backward pumping. A dual-pump polarization-independent fiber-based optical parametric amplifier is used for mid-link spectral inversion of 5 × 28-GBd polarization-multiplexed 16-QAM signals. Signal quality factor (Q-factor) improvements of 1.1 dB and 0.8 dB were obtained in the cases of a single-channel and a five-channel wavelength-division multiplexing (WDM) system, respectively. The experimental results are compared to numerical simulations with good agreement. It is also shown with simulations that a maximum transmission reach of 2400 km enabled by the optical phase conjugator is possible for the WDM signal.

  7. Compensation of Incomplete Round Trip in an Herriott Multipass-Based Kerr-Lens Mode-Locked Ti:Sapphire Oscillator via an Output Coupler Position

    Science.gov (United States)

    Song, Dong Hoon; In Hwang, Sung; Ko, Do-Kyeong

    2011-03-01

    We examined the soft-aperture Kerr-lens mode-locked femtosecond Ti:sapphire oscillator derived from an Herriott multi-pass cavity (HMPC). Additionally, a novel and simple configuration was provided to extend the cavity length, the HMPC consisting of notched, flat and curved (R = 4 m) mirrors by which beams were injected and extracted. To compensate for beams which failed to complete round trips, the configuration was designed and analyzed as a function of the output coupler position. Such an oscillator generated 21.5 nJ, 34 fs pulses at a repetition rate of approximately 13.5 MHz; the spectral bandwidth represented 20 nm, corresponding to a time-bandwidth product of 0.33, assuming a sech2 fit.

  8. Existence and switching behavior of bright and dark Kerr solitons in whispering-gallery mode resonators with zero group-velocity dispersion

    Science.gov (United States)

    Talla Mbé, Jimmi H.; Milián, Carles; Chembo, Yanne K.

    2017-07-01

    We use the generalized Lugiato-Lefever model to investigate the phenomenon of Kerr optical frequency comb generation when group-velocity dispersion is null. In that case, the first dispersion term that plays a leading role is third-order dispersion. We show that this term is sufficient to allow for the existence of both bright and dark solitons. We identify the areas in the parameter space where both kind of solitons can be excited inside the resonator. We also unveil a phenomenon of hysteretic switching between these two types of solitons when the power of the pump laser is cyclically varied. Contribution to the Topical Issue "Theory and Applications of the Lugiato-Lefever Equation", edited by Yanne K. Chembo, Damia Gomila, Mustapha Tlidi, Curtis R. Menyuk.

  9. Solutions to the Helmholtz equation for TE-guided waves in a three-layer structure with Kerr-type nonlinearity

    CERN Document Server

    Schuermann, H W; Shestopalov, Y V

    2002-01-01

    We study certain solutions (TE-polarized electromagnetic waves) of the Helmholtz equation on the line describing waves propagating in a nonlinear three-layer structure consisting of a film surrounded by semi-infinite media. All three media are assumed to be lossless, nonmagnetic, isotropic and exhibiting a local Kerr-type dielectric nonlinearity. The linear component of the permittivity is modelled by a continuous real-valued function of the transverse coordinate. We show that the solution of the Helmholtz equation in the form of a TE-polarized electromagnetic wave exists and can be obtained by iterating the equivalent Volterra equation. The associated dispersion equation has a simple root (if the semi-infinite media are linear and if the nonlinearity parameter of the film is sufficiently small) that uniquely determines this solution.

  10. Spectral dynamics of THz pulses generated by two-color laser filaments in air: The role of Kerr nonlinearities and pump wavelength

    CERN Document Server

    Nguyen, A; Dechard, J; Thiele, I; Babushkin, I; Skupin, S; Berge, L

    2016-01-01

    We theoretically and numerically study the influence of both instantaneous and Raman-delayed Kerr nonlinearities as well as a long-wavelength pump in the terahertz (THz) emissions produced by two-color femtosecond filaments in air. Although the Raman-delayed nonlinearity induced by air molecules weakens THz generation, four-wave mixing is found to impact the THz spectra accumulated upon propagation via self-, cross-phase modulations and self-steepening. Besides, using the local current theory, we show that the scaling of laser-to-THz conversion efficiency with the fundamental laser wavelength strongly depends on the relative phase between the two colors, the pulse duration and shape, rendering a universal scaling law impossible. Scaling laws in powers of the pump wavelength may only provide a rough estimate of the increase in the THz yield. We confront these results with comprehensive numerical simulations of strongly focused pulses and of filaments propagating over meter-range distances.

  11. Pulse splitting in light propagation through N -type atomic media due to an interplay of Kerr nonlinearity and group-velocity dispersion

    Science.gov (United States)

    Rajitha K., V.; Dey, Tarak N.; Evers, Jörg; Kiffner, Martin

    2015-08-01

    We investigate the spatiotemporal evolution of a Gaussian probe pulse propagating through a four-level N -type atomic medium. At two-photon resonance of probe and control fields, weaker probe pulses may propagate through the medium with low absorption and pulse shape distortion. In contrast, we find that increasing the probe pulse intensity leads to a splitting of the initially Gaussian pulse into a sequence of subpulses in the time domain. The number of subpulses arising throughout the propagation can be controlled via a suitable choice of the probe and control field parameters. Employing a simple theoretical model for the nonlinear pulse propagation, we conclude that the splitting occurs due to an interplay of Kerr nonlinearity and group-velocity dispersion.

  12. Kerr Nonlinearity Mitigation: Mid-Link Spectral Inversion Versus Digital Backpropagation in 5×28-GBd PDM 16-QAM Signal Transmission

    DEFF Research Database (Denmark)

    Sackey, Isaac; Da Ros, Francesco; Karl Fischer, Johannes

    2015-01-01

    a dual-pump polarization-independent fiber-optic parametric amplifier and compared to digital backpropagation (DBP) compensation over up to 800-km in a dispersion-managed link. In the single-channel case, the use of the DBP algorithm outperformed the OPC with a Q-factor improvement of 0.9 dB after 800-km......We experimentally investigate Kerr nonlinearity mitigation of a 28-GBd polarization-multiplexed 16-QAM signal in a five-channel 50-GHz spaced wavelength-division multiplexing (WDM) system. Optical phase conjugation (OPC) employing the mid-link spectral inversion technique is implemented by using...... transmission. However, signal transmission was not possible with DBP in the WDM scenario over the same link length while it was enabled by the OPC with a maximum Q-factor of 8.6 dB....

  13. Semiconductor saturable-absorber mirror assisted Kerr-lens mode-locked Ti:sapphire laser producing pulses in the two-cycle regime.

    Science.gov (United States)

    Sutter, D H; Steinmeyer, G; Gallmann, L; Matuschek, N; Morier-Genoud, F; Keller, U; Scheuer, V; Angelow, G; Tschudi, T

    1999-05-01

    Pulses of sub-6-fs duration have been obtained from a Kerr-lens mode-locked Ti:sapphire laser at a repetition rate of 100 MHz and an average power of 300 mW. Fitting an ideal sech(2) to the autocorrelation data yields a 4.8-fs pulse duration, whereas reconstruction of the pulse amplitude profile gives 5.8 fs. The pulse spectrum covers wavelengths from above 950 nm to below 630 nm, extending into the yellow beyond the gain bandwidth of Ti:sapphire. This improvement in bandwidth has been made possible by three key ingredients: carefully designed spectral shaping of the output coupling, better suppression of the dispersion oscillation of the double-chirped mirrors, and a novel broadband semiconductor saturable-absorber mirror.

  14. Distribution of hybrid entanglement and hyperentanglement with time-bin for secure quantum channel under noise via weak cross-Kerr nonlinearity.

    Science.gov (United States)

    Heo, Jino; Kang, Min-Sung; Hong, Chang-Ho; Yang, Hyung-Jin; Choi, Seong-Gon; Hong, Jong-Phil

    2017-08-31

    We design schemes to generate and distribute hybrid entanglement and hyperentanglement correlated with degrees of freedom (polarization and time-bin) via weak cross-Kerr nonlinearities (XKNLs) and linear optical devices (including time-bin encoders). In our scheme, the multi-photon gates (which consist of XKNLs, quantum bus [qubus] beams, and photon-number-resolving [PNR] measurement) with time-bin encoders can generate hyperentanglement or hybrid entanglement. And we can also purify the entangled state (polarization) of two photons using only linear optical devices and time-bin encoders under a noisy (bit-flip) channel. Subsequently, through local operations (using a multi-photon gate via XKNLs) and classical communications, it is possible to generate a four-qubit hybrid entangled state (polarization and time-bin). Finally, we discuss how the multi-photon gate using XKNLs, qubus beams, and PNR measurement can be reliably performed under the decoherence effect.

  15. Note: Vectorial-magneto optical Kerr effect technique combined with variable temperature and full angular range all in a single setup

    Science.gov (United States)

    Cuñado, Jose Luis F.; Pedrosa, Javier; Ajejas, Fernando; Bollero, Alberto; Perna, Paolo; Teran, Francisco J.; Miranda, Rodolfo; Camarero, Julio

    2015-04-01

    Here, we report on a versatile full angular resolved/broad temperature range/vectorial magneto optical Kerr effect (MOKE) magnetometer, named TRISTAN. Its versatility relies on its capacity to probe temperature and angular dependencies of magnetization reversal processes without the need to do any intervention on the apparatus during measurements. The setup is a combination of a vectorial MOKE bench and a cryostat with optical access. The cryostat has a motorized rotatable sample holder with azimuthal correction. It allows for simultaneous and quantitative acquisition of the two in-plane magnetization components during the hysteresis loop at different temperatures from 4 K up to 500 K and in the whole angular range, without neither changing magnet orientation nor opening the cryostat. Measurements performed in a model system with competing collinear biaxial and uniaxial contributions are presented to illustrate its capabilities.

  16. Kerr nonlinearity mitigation in 5 × 28-GBd PDM16-QAM signal transmission over a dispersion-uncompensated link with backward-pumpeddistributed Raman amplification

    DEFF Research Database (Denmark)

    Sackey, I.; Da Ros, Francesco; Jazayerifar, M.

    2014-01-01

    We present experimental and numerical investigations of Kerr nonlinearity compensation in a 400-km standard single-mode fiber link with distributed Raman amplification with backward pumping. A dual-pump polarization-independent fiber-based optical parametric amplifier is used for mid-link spectral...... inversion of 5 × 28-GBd polarization-multiplexed 16- QAM signals. Signal quality factor (Q-factor) improvements of 1.1 dB and 0.8 dB were obtained in the cases of a single-channel and a five-channel wavelength-division multiplexing (WDM) system, respectively. The experimental results are compared...... to numerical simulations with good agreement. It is also shown with simulations that a maximum transmission reach of 2400 km enabled by the optical phase conjugator is possible for the WDM signal...

  17. A setup combining magneto-optical Kerr effect and conversion electron Mössbauer spectrometry for analysis of the near-surface magnetic properties of thin films.

    Science.gov (United States)

    Juraszek, J; Zivotsky, O; Chiron, H; Vaudolon, C; Teillet, J

    2009-04-01

    We propose a system allowing the characterization of thin magnetic multilayer structures that combine conversion electron Mossbauer spectrometry (CEMS) under applied magnetic field with the magneto-optical Kerr effect (MOKE) technique. Measured hysteresis loops obtained from the MOKE part are used for investigation of sample surface magnetic properties. The CEMS part of such a system is suitable for studying the spatial spin distribution during magnetization reversal under applied magnetic field, whose values are established from the measured MOKE loop. The combined technique is demonstrated on the results obtained at 300 K on an exchange-coupled ferrimagnetic amorphous GdFe/TbFe bilayer, where the center of the GdFe layer is enriched in (57)Fe. Both techniques confirm in-plane uniaxial anisotropy. The spin structure at the position of the probe layer is analyzed for several values of the external magnetic field applied in the hard magnetization axis direction.

  18. Field-dependent magneto-optical Kerr effect spectroscopy applied to the magnetic component diagnosis of a rubrene/Ni system.

    Science.gov (United States)

    Li, Wen; Fronk, Michael; Albrecht, Manfred; Franke, Mechthild; Zahn, Dietrich R T; Salvan, Georgeta

    2014-07-28

    Polar magneto-optical Kerr effect (MOKE) spectroscopy in the energy range from 1.75 eV to 5 eV at different magnetic field strength was applied to study Ni nanostructures formed on rubrene nanoislands. The magnetic hysteresis curves measured by MOKE change the shape depending on the photon energy and therefore deviate from those measured by superconducting quantum interference device (SQUID) magnetometry. Similar optical effects were previously observed in inorganic heterostructures. Our observations show that it correlates to the change in lineshape of the MOKE rotation and ellipticity spectra as a function of magnetic field strength. We show that this spectral dependence on magnetic field can be exploited to separate the contributions of two magnetic components to the magneto-optical spectra and hysteresis. The proposed model does not require the a priori knowledge of the (magneto-)optical constants of the heterostructure and its components.

  19. Note: Vectorial-magneto optical Kerr effect technique combined with variable temperature and full angular range all in a single setup.

    Science.gov (United States)

    Cuñado, Jose Luis F; Pedrosa, Javier; Ajejas, Fernando; Bollero, Alberto; Perna, Paolo; Teran, Francisco J; Miranda, Rodolfo; Camarero, Julio

    2015-04-01

    Here, we report on a versatile full angular resolved/broad temperature range/vectorial magneto optical Kerr effect (MOKE) magnetometer, named TRISTAN. Its versatility relies on its capacity to probe temperature and angular dependencies of magnetization reversal processes without the need to do any intervention on the apparatus during measurements. The setup is a combination of a vectorial MOKE bench and a cryostat with optical access. The cryostat has a motorized rotatable sample holder with azimuthal correction. It allows for simultaneous and quantitative acquisition of the two in-plane magnetization components during the hysteresis loop at different temperatures from 4 K up to 500 K and in the whole angular range, without neither changing magnet orientation nor opening the cryostat. Measurements performed in a model system with competing collinear biaxial and uniaxial contributions are presented to illustrate its capabilities.

  20. Rapid shallow breathing

    Science.gov (United States)

    ... the smallest air passages of the lungs in children ( bronchiolitis ) Pneumonia or other lung infection Transient tachypnea of the newborn Anxiety and panic Other serious lung disease Home Care Rapid, shallow breathing should not be treated at home. It is ...