WorldWideScience

Sample records for changing polarization structures

  1. Characterizing the micro structure and kinetics of fast changing samples by simultaneous polarization measurements

    Science.gov (United States)

    Liao, Ran; He, Honghui; Zeng, Nan; Ma, Hui

    2015-03-01

    Taking accurate measurements of the state of polarization (SOP) is the key for the success of polarization sensitive techniques which can provide rich information on the microstructure of complex scattering media, such as biological tissues. For static or slow varying samples, SOP measurements can be achieved by time-sequential recoding of different polarization components controlled by rotating polarizers and wave plates or temporal modulation devices such as photoelastic modulators or liquid crystal variable retarders. When the sample is moving or changing its status quickly, polarization components recoded at different time may correspond to different SOPs, which can lead to significant errors in the final results. Simultaneous polarization measurements are necessary for probing such dynamic samples. In this paper, using the simultaneously recorded polarization components, we are able to mimic time sequential polarization schemes and evaluate the errors. The results show that the kinetics of the sample will affect the systematic error and an increase in the statistical errors of the measured degree of polarization (DOP). We change the kinetics of samples with different stirring speed, which is indicated by the characteristic time of the auto-correlation function. It is also demonstrated that the simultaneously recorded polarization components reveals additional information on the orientation of fibrous scatterers as well as their translation and rotation kinetics.

  2. Polarized light scattering as a probe for changes in chromosome structure

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, D.B.

    1993-10-01

    Measurements and calculations of polarized light scattering are applied to chromosomes. Calculations of the Mueller matrix, which completely describes how the polarization state of light is altered upon scattering, are developed for helical structures related to that of chromosomes. Measurements of the Mueller matrix are presented for octopus sperm heads, and dinoflagellates. Comparisons of theory and experiment are made. A working theory of polarized light scattering from helices is developed. The use of the first Born approximation vs the coupled dipole approximation are investigated. A comparison of continuous, calculated in this work, and discrete models is also discussed. By comparing light scattering measurements with theoretical predictions the average orientation of DNA in an octopus sperm head is determined. Calculations are made for the Mueller matrix of DNA plectonemic helices at UV, visible and X-ray wavelengths. Finally evidence is presented that the chromosomes of dinoflagellates are responsible for observed differential scattering of circularly-polarized light. This differential scattering is found to vary in a manner that is possibly correlated to the cell cycle of the dinoflagellates. It is concluded that by properly choosing the wavelength probe polarized light scattering can provide a useful tool to study chromosome structure.

  3. Polarized Raman spectroscopy unravels the biomolecular structural changes in cervical cancer

    Science.gov (United States)

    Daniel, Amuthachelvi; Prakasarao, Aruna; Dornadula, Koteeswaran; Ganesan, Singaravelu

    2016-01-01

    Polarized Raman spectroscopy has emerged as a promising technique giving a wealth of information about the orientation and symmetry of bond vibrations in addition to the general chemical information from the conventional Raman spectroscopy. In this regard, polarized Raman Spectroscopic technique was employed to study the changes in the orientation of biomolecules in normal and cancerous conditions. This technique was compared to the conventional Raman spectroscopic technique and was found to yield additional information about the orientation of tyrosine, collagen and DNA. The statistically analyzed depolarization ratios by Linear Discriminant Analysis yielded better accuracy than the statistical results of conventional Raman spectroscopy. Thus, this study reveals that polarized Raman spectroscopy has better diagnostic potential than the conventional Raman spectroscopic technique.

  4. Dynamical changes of the polar cap potential structure: an information theory approach

    Directory of Open Access Journals (Sweden)

    I. Coco

    2011-10-01

    Full Text Available Some features, such as vortex structures often observed through a wide spread of spatial scales, suggest that ionospheric convection is turbulent and complex in nature. Here, applying concepts from information theory and complex system physics, we firstly evaluate a pseudo Shannon entropy, H, associated with the polar cap potential obtained from the Super Dual Auroral Radar Network (SuperDARN and, then, estimate the degree of disorder and the degree of complexity of ionospheric convection under different Interplanetary Magnetic Field (IMF conditions. The aforementioned quantities are computed starting from time series of the coefficients of the 4th order spherical harmonics expansion of the polar cap potential for three periods, characterised by: (i steady IMF Bz > 0, (ii steady IMF Bz < 0 and (iii a double rotation from negative to positive and then positive to negative Bz. A neat dynamical topological transition is observed when the IMF Bz turns from negative to positive and vice versa, pointing toward the possible occurrence of an order/disorder phase transition, which is the counterpart of the large scale convection rearrangement and of the increase of the global coherence. This result has been confirmed by applying the same analysis to a larger data base of about twenty days of SuperDARN data, allowing to investigate the role of IMF By too.

  5. The Changing Polar Moon

    Science.gov (United States)

    Lucey, P. G.; Hurley, D.

    2015-12-01

    The Lunar Reconnaissance Orbiter (LRO) and LCROSS have provided an avalanche of new data regarding the lunar poles: LCROSS directly detected water vapor and other volatiles in its impact plume; LRO LAMP has detected surface frost using UV ratios; LEND has refined understanding of the distribution of hydrogen; LOLA and LAMP have showed that the spectral properties of permanently shadowed regions (PSR) are anomalous and may be due to unusual surface texture or altered space weathering; Diviner shows both where the coldest portions of the poles exist, and its quantitative results show where temperatures are low enough to preserve water ice at depth, well outside the PSRs. Yet while we are data rich, our understanding of the lunar poles is maddeningly poor. Our poverty of understanding is made even more baffling by the MESSENGER results from Mercury. At Mercury's poles the distribution of volatiles is dictated by temperature: where subsurface temperatures inferred from topography are consistent with long term preservation of water ice, radar anomalies indicating thick ice are present; where surface temperatures are consistent with preservation of surface frost, high reflectance anomalies indicating surface frost are revealed by laser reflectance. The distribution of water ice on Mercury is well understood. In contrast, temperature is only a weak indicator of the presence of volatiles at the lunar poles; there is little ability to predict the location and abundance of hydrogen or water. The difference may in the age of the volatile deposits on the two planets. Turn the clock forward a few billion years on Mercury and the deposits may appear more lunar. Surface lag deposits may have long ago succumbed to impact gardening, as has much of the shallow buried ice. Ice retained could be patchy, and confined to the coldest places that may tend to preserve it more effectively, even when finely comminuted. Lunar polar volatiles, a possible relic of an ancient, Mercury

  6. Flare processes evolution and polarization changes of fine structures of solar radio emission in the April 11, 2013 event

    CERN Document Server

    Chernov, Gennady; Tan, Baolin; Yan, Yihua; Tan, Chengming; Fu, Qijun; Karlicky, Marian; Fomichev, Valery

    2015-01-01

    The measurement of positions and sizes of radio sources in the observations of solar radio spectral fine structures in an M6.5 flare on April 11, 2013 were observed simultaneously by several radio instruments at four different observatories: Chinese Solar Broadband Radio Spectrometers at Huairou (SBRS/Huairou), Ondrejov Radio spectrograph in the Czech Republic (ORSC/Ondrejov), Badary Broadband Microwave spectropolarimeter (BMS/Irkutsk), and spectrograph/IZMIRAN (Moscow, Troitsk). The fine structures include microwave zebra patterns (ZP), fast pulsations, and fibers. They were observed during the flare brightening located at the tops of a loop arcade. The dynamics of the polarization was associated with the motion of the flare exciter, which was observed in EUV images at 171A and 131A (SDO/AIA). Combining magnetograms observed by the SDO Helioseismic and Magnetic Imager (HMI) with the homologous assumption of EUV flare brightening and ZP bursts, we deduced that the observed ZPs correspond to the ordinary radio...

  7. Long Term Changes in the Polar Vortices

    Science.gov (United States)

    Braathen, Geir O.

    2016-04-01

    As the amount of halogens in the stratosphere is slowly declining and the ozone layer slowly recovers it is of interest to see how the meteorological conditions in the vortex develop over the long term since such changes might alter the foreseen ozone recovery. In conjunction with the publication of the WMO Antarctic and Arctic Ozone Bulletins, WMO has acquired the ERA Interim global reanalysis data set for several meteorological parameters. This data set goes from 1979 - present. These long time series of data can be used for several useful studies of the long term development of the polar vortices. Several "environmental indicators" for vortex change have been calculated, and a climatology, as well as trends, for these parameters will be presented. These indicators can act as yardsticks and will be useful for understanding past and future changes in the polar vortices and how these changes affect polar ozone depletion. Examples of indicators are: vortex mean temperature, vortex minimum temperature, vortex mean PV, vortex "importance" (PV*area), vortex break-up time, mean and maximum wind speed. Data for both the north and south polar vortices have been analysed at several isentropic levels from 350 to 850 K. A possible link between changes in PV and sudden stratospheric warmings will be investigated, and the results presented. The unusual meteorological conditions of the 2015 south polar vortex and the 2010/11 and 2015/16 north polar vortices will be compared to other recent years.

  8. Polar ices: rapid climatic changes

    International Nuclear Information System (INIS)

    The recent successes of the European GRIP (GReenland Ice core Project) and American GISP 2 (Greenland Ice Sheet Project) drillings which have reached in 1992 and 1993 the basement rocks of central Greenland (SUMMIT site, 3250 m of altitude) have allow to reconstruct the climate evolution for the last 100,000 years or more. A comparison of climatic informations deduced from these two drillings with records from Vostok (Antarctica) is given in this paper. The δD and δ18O isotopic approach have been used for the reconstruction of climatic series and paleotemperatures in polar regions. Empirical relationships explained by Rayleigh's isotopic models are used as a base for paleotemperature reconstructions from isotopic analyses of ice. A one degree Celsius cooling corresponds to an oxygen 18 decay of 0.67 per thousand and to a 6 per thousand deuterium decay. The GRIP and GISP 2 drillings have demonstrated the exceptional stability of Greenland climate during the last 10.000 years in comparison with strong instabilities encountered during the last 100.000 years and also recorded in North Atlantic marine sediments. The time scales associated with these instabilities are of the order of a few decades for the warming phase. Thanks to Vostok ice-trapped air bubbles analyses, it is now well demonstrated that the strongest instabilities (cooling during the last deglaciation and major glaciation inter stages) are also recorded but less pronounced in Antarctica. GRIP data for the last interglacial stage have been interpreted in terms of climate instabilities but neither GISP 2 results nor Vostok results allow to confirm this interpretation. (J.S.). 29 refs, 3 figs

  9. Dynamics of Subauroral Polarization Stream (SAPS) Structures

    Science.gov (United States)

    Sazykin, S. Y.; Coster, A. J.; Huba, J.; Ridley, A. J.; Erickson, P. J.; Foster, J. C.; Baker, J. B. H.; Wolf, R.

    2015-12-01

    The Subauroral Polarization Stream (SAPS) flow structures are narrow ionospheric channels of fast (in excess of 100 m/s) westward drift just outside the equatorward edge of the diffuse aurora in the dusk-to-midnight local time sector. Other terms for this phenomenon include subauroral Ion Drift (SAID) events and Polarization Jets. SAPS structures represent a striking departure from the commonly-used two-cell convection pattern. They are thought to arise from the displacement of the downward region-2 Birkeland currents on the dusk side equatorward of the low-latitude boundary of the auroral oval during times of changing high-latitude convection. In this paper, we will use several event simulations with the SAMI3-RCM numerical model (a self-consistent ionosphere-inner magnetosphere model) and RCM-GITM (a self-consistent model of the ionosphere-thermosphere-inner magnetosphere) to analyze the relative roles of changes in the IMF Bz component, ionospheric electron density depletions, and thermospheric modifications in controlling the dynamics of SAPS. Simulation results will be compared to multi-instrument ionospheric observations.

  10. Long term changes in the polar vortices

    Science.gov (United States)

    Braathen, Geir O.

    2015-04-01

    As the amount of halogens in the stratosphere is slowly declining and the ozone layer slowly recovers it is of interest to see how the meteorological conditions in the vortex develop over the long term since such changes might alter the foreseen ozone recovery. In conjunction with the publication of the WMO Antarctic and Arctic Ozone Bulletins, WMO has acquired the ERA Interim global reanalysis data set for several meteorological parameters. This data set goes from 1979 - present. These long time series of data can be used for several useful studies of the long term development of the polar vortices. Several "environmental indicators" for vortex change have been calculated, and a climatology, as well as trends, for these parameters will be presented. These indicators can act as yardsticks and will be useful for understanding past and future changes in the polar vortices and how these changes affect polar ozone depletion. Examples of indicators are: vortex mean temperature, vortex minimum temperature, vortex mean PV, vortex "importance" (PV*area), vortex break-up time, mean and maximum wind speed. Data for both the north and south polar vortices have been analysed at several isentropic levels from 350 to 850 K. A possible link between changes in PV and sudden stratospheric warmings will be investigated, and the results presented.

  11. Spin structure of constituent quark and polarized structure of hadrons

    International Nuclear Information System (INIS)

    Polarized parton distribution inside a constituent quark is calculated. This structure is universal for all hadrons and the polarized structure of any hadron is a convolution of polarized constituent quark distribution in the hadron with the polarized structure function of the constituent quark. This approach gives very good agreement with the experimental data on polarized proton, neutron, and deuteron. However, in order to assemble the components to build the spin the constituent quark we are forced to include a sizeable orbital angular momentum. (author)

  12. Classifying spaces of degenerating polarized Hodge structures

    CERN Document Server

    Kato, Kazuya

    2009-01-01

    In 1970, Phillip Griffiths envisioned that points at infinity could be added to the classifying space D of polarized Hodge structures. In this book, Kazuya Kato and Sampei Usui realize this dream by creating a logarithmic Hodge theory. They use the logarithmic structures begun by Fontaine-Illusie to revive nilpotent orbits as a logarithmic Hodge structure. The book focuses on two principal topics. First, Kato and Usui construct the fine moduli space of polarized logarithmic Hodge structures with additional structures. Even for a Hermitian symmetric domain D, the present theory is a refinem

  13. The Large Scale Structure: Polarization Aspects

    Indian Academy of Sciences (India)

    R. F. Pizzo

    2011-12-01

    Polarized radio emission is detected at various scales in the Universe. In this document, I will briefly review our knowledge on polarized radio sources in galaxy clusters and at their outskirts, emphasizing the crucial information provided by the polarized signal on the origin and evolution of such sources. Successively, I will focus on Abell 2255, which is known in the literature as the first cluster for which filamentary polarized emission associated with the radio halo has been detected. By using RM synthesis on our multi-wavelength WSRT observations, we studied the 3-dimensional geometry of the cluster, unveiling the nature of the polarized filaments at the borders of the central radio halo. Our analysis points out that these structures are relics lying at large distance from the cluster center.

  14. Quantitative Assessment of Birefringent Skin Structures in Scattered Light Confocal Imaging Using Radially Polarized Light

    Directory of Open Access Journals (Sweden)

    Natallia Eduarda Uzunbajakava

    2013-09-01

    Full Text Available The polarization characteristics of birefringent tissues could be only partially obtained using linearly polarized light in polarization sensitive optical imaging. Here we analyze the change in polarization of backscattered light from birefringent structures versus the orientations of the incident polarizations using linearly, circularly and radially polarized light in a cross-polarized confocal microscope. A spatially variable retardation plate composed of eight sectors of λ/2 wave plates was used to transform linearly polarized light into a radially polarized light. Based on the experimental data obtained from ex-vivo measurements on human scalp hairs and in-vivo measurements on hair and skin, we exemplify that the underestimation of the birefringence content resulting from the orientation related effects associated with the use of linearly polarized light for imaging tissues containing wavy birefringent structures could be minimized by using radially polarized light.

  15. Growth and characterization of periodically polarity-inverted ZnO structures on sapphire substrates

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jinsub, E-mail: jinsubpark@hanyang.ac.kr [Department of Electronic Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Yao, Takafumi [Center for Interdisciplinary Research, Tohoku University, Sendai 980-855 (Japan)

    2012-10-15

    We report on the fabrication and characterization of periodically polarity inverted (PPI) ZnO heterostructures on (0 0 0 1) Al{sub 2}O{sub 3} substrates. For the periodically inverted array of ZnO polarity, CrN and Cr{sub 2}O{sub 3} polarity selection buffer layers are used for the Zn- and O-polar ZnO films, respectively. The change of polarity and period in fabricated ZnO structures is evaluated by diffraction patterns and polarity sensitive piezo-response microscopy. Finally, PPI ZnO structures with subnanometer scale period are demonstrated by using holographic lithography and regrowth techniques.

  16. Polarization selective phase-change nanomodulator

    Science.gov (United States)

    Appavoo, Kannatassen; Haglund, Richard F., Jr.

    2014-10-01

    Manipulating optical signals below the diffraction limit is crucial for next-generation data-storage and telecommunication technologies. Although controlling the flow of light around nanoscale waveguides was achieved over a decade ago, modulating optical signals at terahertz frequencies within nanoscale volumes remains a challenge. Since the physics underlying any modulator relies on changes in dielectric properties, the incorporation of strongly electron-correlated materials (SECMs) has been proposed because they can exhibit orders of magnitude changes in electrical and optical properties with modest thermal, electrical or optical trigger signals. Here we demonstrate a hybrid nanomodulator of deep sub-wavelength dimensions with an active volume of only 0.002 µm3 by spatially confining light on the nanometre length scale using a plasmonic nanostructure while simultaneously controlling the reactive near-field environment at its optical focus with a single, precisely positioned SECM nanostructure. Since the nanomodulator functionality hinges on this near-field electromagnetic interaction, the modulation is also selectively responsive to polarization. This architecture suggests one path for designing reconfigurable optoelectronic building blocks with responses that can be tailored with exquisite precision by varying size, geometry, and the intrinsic materials properties of the hybrid elements.

  17. Polarization sensitive anisotropic structuring of silicon by ultrashort light pulses

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jingyu; Drevinskas, Rokas, E-mail: rd1c12@orc.soton.ac.uk; Beresna, Martynas; Kazansky, Peter G. [Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ (United Kingdom)

    2015-07-27

    Imprinting of anisotropic structures on the silicon surface by double pulse femtosecond laser irradiation is demonstrated. The origin of the polarization-induced anisotropy is explained in terms of interaction of linearly polarized second pulse with the wavelength-sized symmetric crater-shaped structure generated by the linearly polarized first pulse. A wavefront sensor is fabricated by imprinting an array of micro-craters. Polarization controlled anisotropy of the structures can be also explored for data storage applications.

  18. Polar ionospheric responses to solar wind IMF changes

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    Full Text Available Auroral and airglow emissions over Eureka (89° CGM during the 1997-98 winter show striking variations in relation to solar wind IMF changes. The period January 19 to 22, 1998, was chosen for detailed study, as the IMF was particularly strong and variable. During most of the period, Bz was northward and polar arcs were observed. Several overpasses by DMSP satellites during the four day period provided a clear picture of the particle precipitation producing the polar arcs. The spectral character of these events indicated excitation by electrons of average energy 300 to 500 eV. Only occasionally were electrons of average energy up to ~1 keV observed and these appeared transitory from the ground optical data. It is noted that polar arcs appear after sudden changes in IMF By, suggesting IMF control over arc initiation. When By is positive there is arc motion from dawn to dusk, while By is negative the motion is consistently dusk to dawn. F-region (anti-sunward convections were monitored through the period from 630.0 nm emissions. The convection speed was low (100-150 m/s when Bz was northward but increased to 500 m/s after Bz turned southward on January 20.

    Key words: Atmospheric composition and structure (airglow and aurora - Ionosphere (particle precipitation - Magnetospheric Physics (polar cap phenomena

  19. Polarization changing technique in macrocosm and it's application to radar

    Institute of Scientific and Technical Information of China (English)

    潘健; 毛二可

    2004-01-01

    A new model of air-surveillance radar (named polarization changing in macrocosm radar: PCM radar), which makes use of the polarization changing technique in macrocosm, is presented in this paper. On basis of careful selection of representative 98 states of polarization in macrocosm, PCM radar can not only perform transmitting and receiving polarization matching for various targets, consequently make full use of transmitting and receiving signals of radar, but also improve the capability against active interference and jamming. Experimental test in air defense early-warning radar system demonstrates that it can effectively enhance radar performance.

  20. Bringing Society to a Changing Polar Ocean: Polar Interdisciplinary Coordinated Education (ICE)

    Science.gov (United States)

    Schofield, O.

    2015-12-01

    Environmental changes in the Arctic and Antarctic appear to be accelerating and scientists are trying to understand both the patterns and the impacts of change. These changes will have profound impact on humanity and create a need for public education about these critical habitats. We have focused on a two-pronged strategy to increase public awareness as well as enable educators to discuss comfortably the implications of climate change. Our first focus is on entraining public support through the development of science documentaries about the science and people who conduct it. Antarctic Edge is a feature length award-winning documentary about climate change that has been released in May 2015 and has garnered interest in movie theatres and on social media stores (NetFlix, ITunes). This broad outreach is coupled with our group's interest assisting educators formally. The majority of current polar education is focused on direct educator engagement through personal research experiences that have impact on the participating educators' classrooms. Polar Interdisciplinary Coordinated Education (ICE) proposes to improve educator and student engagement in polar sciences through exposure to scientists and polar data. Through professional development and the creation of data tools, Polar ICE will reduce the logistical costs of bringing polar science to students in grades 6-16. We will provide opportunities to: 1) build capacity of polar scientists in communicating and engaging with diverse audiences; 2) create scalable, in-person and virtual opportunities for educators and students to engage with polar scientists and their research through data visualizations, data activities, educator workshops, webinars, and student research symposia; and 3) evaluate the outcomes of Polar ICE and contribute to our understanding of science education practices. We will use a blended learning approach to promote partnerships and cross-disciplinary sharing. This combined multi-pronged approach

  1. The hybrid outcome of urban change: global city, polarized city?

    Directory of Open Access Journals (Sweden)

    Ayat Ismail

    2013-12-01

    Full Text Available A wide range of studies supports the assumption that levels of socio-spatial polarization, segregation, and exclusion are rising in global cities over the past decades as a direct outcome of certain global processes, such as the deindustrialization process, its associated changes in division of labor, and declined redistributive power of the welfare state. However, that assumption – known as the polarization thesis – is criticized based on several contentions, including the oversimplification of the global/local interplay by overlooking the role of local contingent factors that may modify, intensify, or reverse the expected socio-spatial outcome in individual cities. This study aims to capture the hybrid nature of the socio-spatial outcomes of global cities by proving that the complex process of restructuring of cities is a form of structural and chronological hybridity. Through providing a solid empirical ground for investigating the general applicability of the socio-spatial polarization thesis, as well as evaluating the influence of local contexts of cities on the outcomes of urban change. The research offers a theoretical review of the multifaceted restructuring of global cities. Then, the macro trends of global economy are linked to their micro outcomes (segregation patterns within cities, through understanding the implications of cities’ economic functions on local urban policies and housing markets. Finally, the changes in socioeconomic segregation over the past decades are calculated for a large dataset of 66 global cities. The collective result of the analysis shows the downfalls of the generalized hypothesis. While the discussion of individual cities highlights certain contextual particularities, that are contributing to the production of unique socio-spatial configurations in different global cities.

  2. Study of hadron structure in a deep-inelastic scattering of polarized leptons on polarized nucleons

    International Nuclear Information System (INIS)

    The problem is discussed of nucleon structure research in deep inelastic scattering processes of polarized leptons on polarized nucleons. Using a modified Kuti-Weisskopf model theoretical relations are derived for structure functions involved in the deep inelastic differential cross section of leptons on nucleons. (Z.J.)

  3. Alignment of quasar polarizations with large-scale structures

    CERN Document Server

    Hutsemékers, Damien; Pelgrims, Vincent; Sluse, Dominique

    2014-01-01

    We have measured the optical linear polarization of quasars belonging to Gpc-scale quasar groups at redshift z ~ 1.3. Out of 93 quasars observed, 19 are significantly polarized. We found that quasar polarization vectors are either parallel or perpendicular to the directions of the large-scale structures to which they belong. Statistical tests indicate that the probability that this effect can be attributed to randomly oriented polarization vectors is of the order of 1%. We also found that quasars with polarization perpendicular to the host structure preferentially have large emission line widths while objects with polarization parallel to the host structure preferentially have small emission line widths. Considering that quasar polarization is usually either parallel or perpendicular to the accretion disk axis depending on the inclination with respect to the line of sight, and that broader emission lines originate from quasars seen at higher inclinations, we conclude that quasar spin axes are likely parallel ...

  4. Coherence and Polarization of Polarization Speckle Generated by Depolarizers and Their Changes through Complex ABCD Matrix

    DEFF Research Database (Denmark)

    Ma, Ning; Hanson, Steen Grüner; Lee, Tim K.;

    2015-01-01

    Recent research work on speckle patterns indicates a variation of the polarization state during propagation and its nonuniformly spatial distribution. The preliminary step for the investigation of this polarization speckle is the generation of the corresponding field. In this paper, a kind...... of special depolarizer: the random roughness birefringent screen (RRBS) is introduced to meet this requirement. The statistical properties of the field generated by the depolarizer is investigated and illustrated in terms of the 2x2 beam coherence and polarization matrix (BCPM) with the corresponding degree...... of coherence (DoC). and degree of polarization (DoP) P. The changes of the coherence and polarization when the speckle field propagates through any optical system are analysed within the framework of the complex ABCD-matrix theory....

  5. Organisational Structure & Change

    Science.gov (United States)

    National Centre for Vocational Education Research (NCVER), 2006

    2006-01-01

    Structural change is seen as a way to meet the challenges of the future that face many organisations. While some writers agree that broad-ranging structural change may not always transform an organisation or enhance its performance, others claim that innovation will be a major source of competitive advantage to organisations, particularly when…

  6. Polarization converters on double hetero structures containing strained quantum wells

    Science.gov (United States)

    Khalique, U.; van der Tol, J. J. G. M.; Nötzel, R.; Smit, M. K.

    2009-02-01

    The importance of polarization manipulation is increased as optical fiber systems evolve to higher data rates. Photonic integrated circuits should be insensitive to the state of polarization of the light emanating from fibers if they are to be used as detectors, add-drop mutiplexers or cross connects. Either all the integrated components have to be polarization independent or only one polarization direction should be used. For either method, a compact polarization converter is useful. A model is developed for the mode propagation in the waveguide of the slanted side polarization converter based on double hetero structures. The model is extended to include polarization dependent absorption and mismatch. Polarization converters on different double heterostructures (with and without quantum wells) have been designed and are realized by contact optical lithography. The performance of the realized converters is well described with the model.

  7. High Performance Circularly Polarized Antenna Based on Fractal EBG Structure

    OpenAIRE

    Bao, Xiulong; Ammann, Max; Ruvio, Giuseppe; John, Matthias

    2006-01-01

    Circularly polarized patch antennas have been widely applied in wireless communication system, global positioning system, etc., because of their low-profile, lightweight, ease of fabrication and low lost [1,2]. To achieve high performance for circularly polarized patch antennas, some new structures were reported in the literature, such as antennas array, stack layer antennas, using periodic structures [3-7], etc. In this paper, a high performance circularly polarized low frequency patch anten...

  8. Fine structure and optical properties of biological polarizers in crustaceans and cephalopods

    Science.gov (United States)

    Chiou, Tsyr-Huei; Caldwell, Roy L.; Hanlon, Roger T.; Cronin, Thomas W.

    2008-04-01

    The lighting of the underwater environment is constantly changing due to attenuation by water, scattering by suspended particles, as well as the refraction and reflection caused by the surface waves. These factors pose a great challenge for marine animals which communicate through visual signals, especially those based on color. To escape this problem, certain cephalopod mollusks and stomatopod crustaceans utilize the polarization properties of light. While the mechanisms behind the polarization vision of these two animal groups are similar, several distinctive types of polarizers (i.e. the structure producing the signal) have been found in these animals. To gain a better knowledge of how these polarizers function, we studied the relationships between fine structures and optical properties of four types of polarizers found in cephalopods and stomatopods. Although all the polarizers share a somewhat similar spectral range, around 450- 550 nm, the reflectance properties of the signals and the mechanisms used to produce them have dramatic differences. In cephalopods, stack-plates polarizers produce the polarization patterns found on the arms and around their eyes. In stomatopods, we have found one type of beam-splitting polarizer based on photonic structures and two absorptive polarizer types based on dichroic molecules. These stomatopod polarizers may be found on various appendages, and on the cuticle covering dorsal or lateral sides of the animal. Since the efficiencies of all these polarizer types are somewhat sensitive to the change of illumination and viewing angle, how these animals compensate with different behaviors or fine structural features of the polarizer also varies.

  9. Polarization beam splitter based on dielectric periodic structure with different EFCs for two polarizations

    Institute of Scientific and Technical Information of China (English)

    Yuan Zhang; Yurong Jiang; Xia Li; Wei Xue

    2008-01-01

    @@ A dielectric multi-layered structure is studied in this letter. It is found that at some frequency ranges, the equal-frequency contours (EFCs) are almost flat for one polarization but still curve for the other. Based on this property, we propose a novel polarization beam splitter.

  10. Characterization of PEM fuel cell degradation by polarization change curves

    Science.gov (United States)

    Bezmalinovic, Dario; Simic, Boris; Barbir, Frano

    2015-10-01

    Polarization change curves, defined as a difference between the polarization curve at the beginning of life and the actual polarization curve after the cell has been operational for some time, were used to analyze degradation of a PEM fuel cell exposed to voltage cycling as an accelerated stress test for electrocatalyst degradation. Degradation, i.e., loss of voltage was due to increase of activation losses and increase of resistance in the catalyst layer, both most likely due to the loss of catalyst electrochemically active area. The results of the polarization change curves analysis correspond to the findings of the periodic individual tests performed during the accelerated stress test, such as electrochemical impedance spectroscopy, cyclic voltammetry and linear sweep voltammetry. Therefore, this method has potential to be used as a relatively quick and simple, yet effective, degradation diagnostic tool.

  11. Change in Business Structure

    Data.gov (United States)

    Department of Veterans Affairs — Provides information on whether a company’s change in business structure affects its Data Universal Numbering System (DUNS) Number and its Vendor Information Pages...

  12. Holographic liquid crystal polarization grating with Fabry-Perot structure.

    Science.gov (United States)

    Sakamoto, Moritsugu; Yamaguchi, Haruki; Noda, Kohei; Sasaki, Tomoyuki; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2016-03-15

    A holographic liquid crystal polarization grating with a Fabry-Perot structure was developed. Because of its resonant structure, the device offers high levels of control of the diffraction properties of incident-polarized light beams, depending on the resonance conditions. The diffracted light beams are emitted in both the reflection and transmission directions, and the device thus works as a multibranch polarization grating with double optical paths, unlike a conventional polarization grating. These device features were experimentally demonstrated and were also explained theoretically.

  13. The hybrid outcome of urban change: global city, polarized city?

    OpenAIRE

    Ayat Ismail

    2013-01-01

    A wide range of studies supports the assumption that levels of socio-spatial polarization, segregation, and exclusion are rising in global cities over the past decades as a direct outcome of certain global processes, such as the deindustrialization process, its associated changes in division of labor, and declined redistributive power of the welfare state. However, that assumption – known as the polarization thesis – is criticized based on several contentions, including the oversimplification...

  14. Uranus’ Hemispheric Asymmetries in Polar Cloud and Circulation Structures

    Science.gov (United States)

    Hammel, Heidi B.; Sromovsky, Lawrence; Fry, Pat; de Pater, Imke

    2015-11-01

    We report on the north polar region of Uranus in the post-equinoctial era. Near-IR imaging with Keck 2 using NIRC2 in 2012-2014 revealed numerous small bright features, as well as small dark features, between 50 degrees N and the north pole. Tracking of these features yielded circulation patterns, with the remarkable result that the region from 60 degrees to at least 83 degrees rotates about the northern pole as a solid body, with a drift rate of 4.1 degrees/hour westward relative to the interior (Sromovsky et al. 2015, Icarus 258, 192-223). For the south pole, the same latitude region had dramatically different characteristics, as judged by 1986 Voyager and 2003 Keck observations. The southern region showed no discrete near-IR features; detailed circulation measurements in that region were based solely on low-contrast features in re-analyzed Voyager images (Karkoschka, 2015, Icarus 250, 294-307). They revealed a large gradient in drift rates, with values reaching twice that seen in the corresponding northern region.The north-south asymmetry in circulation and cloud structure/morphology is surprising because the distribution of upper tropospheric methane is relatively symmetric: roughly constant over a region from 30 S to 30 N, and then declining at higher latitudes in both hemispheres. The methane distribution suggests symmetric down-welling motion in both polar regions, which would inhibit formation of condensation clouds there, in contrast to the observed dichotomy. Some asymmetry may be an effect of seasonal forcing, since the north versus south polar measurements were made during different seasons. If so, then major changes can be expected in the north polar region as Uranus proceeds toward its 2030 northern summer solstice. Hubble STIS observations expected in October of 2015 will further examine the vertical distribution and stability of the polar methane abundances. Future high-resolution imaging with Earth-based facilities will be able to track circulation

  15. Corporate funding and ideological polarization about climate change.

    Science.gov (United States)

    Farrell, Justin

    2016-01-01

    Drawing on large-scale computational data and methods, this research demonstrates how polarization efforts are influenced by a patterned network of political and financial actors. These dynamics, which have been notoriously difficult to quantify, are illustrated here with a computational analysis of climate change politics in the United States. The comprehensive data include all individual and organizational actors in the climate change countermovement (164 organizations), as well as all written and verbal texts produced by this network between 1993-2013 (40,785 texts, more than 39 million words). Two main findings emerge. First, that organizations with corporate funding were more likely to have written and disseminated texts meant to polarize the climate change issue. Second, and more importantly, that corporate funding influences the actual thematic content of these polarization efforts, and the discursive prevalence of that thematic content over time. These findings provide new, and comprehensive, confirmation of dynamics long thought to be at the root of climate change politics and discourse. Beyond the specifics of climate change, this paper has important implications for understanding ideological polarization more generally, and the increasing role of private funding in determining why certain polarizing themes are created and amplified. Lastly, the paper suggests that future studies build on the novel approach taken here that integrates large-scale textual analysis with social networks.

  16. Differential extinction and the contrasting structure of polar marine faunas.

    Directory of Open Access Journals (Sweden)

    Andrew Z Krug

    Full Text Available BACKGROUND: The low taxonomic diversity of polar marine faunas today reflects both the failure of clades to colonize or diversify in high latitudes and regional extinctions of once-present clades. However, simple models of polar evolution are made difficult by the strikingly different faunal compositions and community structures of the two poles. METHODOLOGY/PRINCIPAL FINDINGS: A comparison of early Cenozoic Arctic and Antarctic bivalve faunas with modern ones, within the framework of a molecular phylogeny, shows that while Arctic losses were randomly distributed across the tree, Antarctic losses were significantly concentrated in more derived families, resulting in communities dominated by basal lineages. Potential mechanisms for the phylogenetic structure to Antarctic extinctions include continental isolation, changes in primary productivity leading to turnover of both predators and prey, and the effect of glaciation on shelf habitats. CONCLUSIONS/SIGNIFICANCE: These results show that phylogenetic consequences of past extinctions can vary substantially among regions and thus shape regional faunal structures, even when due to similar drivers, here global cooling, and provide the first phylogenetic support for the "retrograde" hypothesis of Antarctic faunal evolution.

  17. Resilience in polar ecosystems: From drivers to impacts and changes

    Science.gov (United States)

    Bölter, Manfred; Müller, Felix

    2016-03-01

    The theory of resilience is increasing in applied ecosystem research and has become a valuable concept for analyzing relationships between natural environments and various stressors, e.g., global warming or direct human impacts. This concept offers opportunities to apply management strategies to different system levels and can provide insights into future ecosystem change. Polar systems are known to be ecologically sensitive to global and local impacts. Records of changes in polar environments, used as alarm signals by governmental and non-governmental institutions, are well documented in various reports. However, it remains difficult to define specific disturbance thresholds, only few methods allow an evaluation of the actual natural state of polar systems, its degree of modification they can accommodate before trophic systems change with severe damages. Some of the main drivers of system changes have been analyzed with respect to possible effects on system changes over different time scales. This paper reviews studies of polar ecosystems and their ability to cope with changes by assessing their resilience in response to human disturbances. Furthermore, we suggest that a customized framework (drivers, pressures, states, impacts, and responses (DPSIR)) should be applied to obtain an improved understanding of the interactions between the state of, and changes in, natural systems.

  18. Monocyte polarization: the relationship of genome-wide changes in H4 acetylation with polarization.

    Science.gov (United States)

    Zhang, Z; Song, L; Maurer, K; Bagashev, A; Sullivan, K E

    2011-09-01

    The character of monocytes is both molded by and contributes to ongoing immune responses. We hypothesized that monocyte polarization could have durable qualities and these would be mediated partly by changes in the chromatin. We defined genome-wide expression and histone H4 acetylation (H4ac) changes after γ-interferon (IFN), α-IFN and interleukin-4 treatment. To identify genes with altered potential for expression, we stimulated polarized monocytes and identified genes up- or downregulated after polarization and stimulation but not either treatment alone. We also defined durability after an 18-h or 3-day washout. Genes uniquely regulated after the combination of polarization and stimulus were durably altered, with 51% of the effects being durable. This gene set was highly enriched for cytokine-induced alterations in H4ac, with P-values ranging from 10(-24) to 10(-37). Certain regulons defined by patterns of expression were also associated with altered H4ac, with P-values ranging from 10(-4) to 10(-29). Networking software revealed a high density of mitogen-activated protein (MAP) kinase nodes in these clusters. Therefore, some changes in monocyte gene expression were sustained over a 3-day period. These durably altered gene sets were enriched for changes in H4ac and were associated with potential MAP kinase effects. PMID:21451557

  19. A Novel Nano-Grating Structure of Polarizing Beam Splitters

    Institute of Scientific and Technical Information of China (English)

    ZHANG Liang; LI Jing; LI Cheng-Fang; ZHANG Fei; SHI Li-Na

    2006-01-01

    @@ A metal wire nanograting is fabricated and used as a polarizing beam splitter that reflects TE polarization and transmits TM polarization. The metal wire nanograting is based on a fully optimized design structure that consists of not only the core nanowire metal grid but also the substrate nanograting. The substrate nanograting is designed to provide better performance for both TM and TE polarizations. We fabricate metal-stripe gratings on a glass substrate using nanoimprint lithography and reactive ion etching process. A detailed investigation of the polarization effect at 1550 nm wavelength is carried out with the theoretical analysis and experimental results.The polarizing beam splitter has uniform performance with wide variations in the incident angle (±25) and has high efficiency for both the reflected and the transmitted beams.

  20. Alignment of quasar polarizations with large-scale structures

    Science.gov (United States)

    Hutsemékers, D.; Braibant, L.; Pelgrims, V.; Sluse, D.

    2014-12-01

    We have measured the optical linear polarization of quasars belonging to Gpc scale quasar groups at redshift z ~ 1.3. Out of 93 quasars observed, 19 are significantly polarized. We found that quasar polarization vectors are either parallel or perpendicular to the directions of the large-scale structures to which they belong. Statistical tests indicate that the probability that this effect can be attributed to randomly oriented polarization vectors is on the order of 1%. We also found that quasars with polarization perpendicular to the host structure preferentially have large emission line widths while objects with polarization parallel to the host structure preferentially have small emission line widths. Considering that quasar polarization is usually either parallel or perpendicular to the accretion disk axis depending on the inclination with respect to the line of sight, and that broader emission lines originate from quasars seen at higher inclinations, we conclude that quasar spin axes are likely parallel to their host large-scale structures. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program ID 092.A-0221.Table 1 is available in electronic form at http://www.aanda.org

  1. Polarity inverted intracloud discharges and electric charge structure of thunderstorm

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The three-dimensional spatial and temporal development of impulsive VHF radiation events during lightning discharges has been analyzed based on the data measured by the lightning mapping array (LMA) system with high space and time resolution. The results indicate that intracloud discharges in the thunderstorm with anormal tripole charge structure occur not only between the upper positive and middle main negative charge region, but also with inverted polarity between the lower positive and middle main negative charge region. The polarity-inverted discharge originates from the middle negative charge and propagates downward to the lower positive region, where then the discharge develops horizontally. The characteristics of the discharge are similar to that of normal intracloud discharge except the polarity opposite. The results further confirmed the existence of the lower positive charge region involved in the lightning discharge. It was also found that the inverted charge structure opposite to the normal polarity ap pears in some storms or at a certain stage of the storm development. In the stor m with a polarity inverted charge structure, a main positive charge region is lo cated at the middle part and a negative charge at the upper part of the storm. T he intracloud discharges occurred between them are of inverted polarity, showing the existence of a polarity inverted charging mechanism in storms and the compl exity of storm charge structure.

  2. Enhanced polarization of (11–22) semi-polar InGaN nanorod array structure

    Energy Technology Data Exchange (ETDEWEB)

    Athanasiou, M.; Smith, R. M.; Hou, Y.; Zhang, Y.; Gong, Y.; Wang, T., E-mail: t.wang@sheffield.ac.uk [Department of Electronic and Electrical Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2015-10-05

    By means of a cost effective nanosphere lithography technique, an InGaN/GaN multiple quantum well structure grown on (11–22) semipolar GaN has been fabricated into two dimensional nanorod arrays which form a photonic crystal (PhC) structure. Such a PhC structure demonstrates not only significantly increased emission intensity, but also an enhanced polarization ratio of the emission. This is due to an effective inhibition of the emission in slab modes and then redistribution to the vertical direction, thus minimizing the light scattering processes that lead to randomizing of the optical polarization. The PhC structure is designed based on a standard finite-difference-time-domain simulation, and then optically confirmed by detailed time-resolved photoluminescence measurements. The results presented pave the way for the fabrication of semipolar InGaN/GaN based emitters with both high efficiency and highly polarized emission.

  3. Polarized and Unpolarized Structure Functions in the Valon Model

    Science.gov (United States)

    Arash, Firooz

    2006-02-01

    Hadrons are considered as the bound states of their structureful constituents, the Valons. The valon structure is calculated perturbatively in QCD; which is universal and independent of the hosting hadron. This structure is used to calculate Proton and pion structure functions. For the case of polarized structure function, the valon representation, not only gives all the available data on gp,n,d1, but also requires a sizable orbital angular momentum associated with the partonic structure of the valon.

  4. Polar marine ecosystems: major threats and future change

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, A. [British Antarctic Survey, Cambridge (United Kingdom); Harris, C.M. [Environmental Research and Assessment, Grantchester (United Kingdom)

    2003-07-01

    This review of polar marine ecosystems covers both the Arctic and Antarctic, identifying the major threats and, where possible, predicting their possible state(s) in 2025. Although the two polar regions are similar in their extreme photoperiod, low temperatures, and in being heavily influenced by snow and ice, in almost all other respects they are very different. The Arctic Ocean is a basin surrounded by continental landmasses close to, and influenced by, large populations and industrial activities. In contrast, the Southern Ocean is contiguous with all the other great oceans and surrounds a single land mass; Antarctica is remote from major centres of population and sources of pollution. Marine environments in both Polar Regions have been highly disturbed by fishing activity, but, in terms of pollution, some areas remain among the most pristine in the world. There are, however, both local and global pressures. Over the 2025 time horizon, the greatest concern for the Arctic is probably the ecological implications of climate change, particularly insofar as sea ice extent and duration are likely to be affected. Such changes are not expected to be as pronounced in the Southern Ocean over this time period, and concerns are related more to direct threats from harvesting of marine living resources, and the ability to manage these fisheries sustainably. In both Polar Regions, the capacity of marine ecosystems to withstand the cumulative impact of a number of pressures, including climate change, pollution and overexploitation, acting synergistically is of greatest concern. (author)

  5. Milliarcsecond polarization structure of the superluminal quasar 3C 273

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, D.H.; Kollgaard, R.I.; Brown, L.F.; Gabuzda, D.C.; Wardle, J.F. C. (Brandeis Univ., Waltham, MA (USA))

    1990-09-01

    A 2 x 10 marcsec-resolution determination is presented for the total intensity and linear polarization structures of the superluminal quasar 3C 273 at 5 GHz. Substantial polarized flux was detected from several superluminal components of the jet, whose fractional polarization increased symmetrically with distance from the core; the most distant component is highly polarized and exhibits a highly ordered magnetic field. Within a few marcsec of the core, the inferred magnetic field orientation varies rapidly with position along the jet. The primarily longitudinal magnetic field orientation is concluded to become established within 20 marcsec of the core. A highly disorganized magnetic field is the most plausible explanation for the low degree of polarization in the innermost regions of the jet. 48 refs.

  6. Milliarcsecond polarization structure of the superluminal quasar 3C 273

    International Nuclear Information System (INIS)

    A 2 x 10 marcsec-resolution determination is presented for the total intensity and linear polarization structures of the superluminal quasar 3C 273 at 5 GHz. Substantial polarized flux was detected from several superluminal components of the jet, whose fractional polarization increased symmetrically with distance from the core; the most distant component is highly polarized and exhibits a highly ordered magnetic field. Within a few marcsec of the core, the inferred magnetic field orientation varies rapidly with position along the jet. The primarily longitudinal magnetic field orientation is concluded to become established within 20 marcsec of the core. A highly disorganized magnetic field is the most plausible explanation for the low degree of polarization in the innermost regions of the jet. 48 refs

  7. Radio polarization and magnetic field structure in M 101

    CERN Document Server

    Berkhuijsen, E M; Beck, R; Han, J L

    2016-01-01

    We observed total and polarized radio continuum emission from the spiral galaxy M 101 at 6.2 cm and 11.1 cm wavelengths with the Effelsberg telescope. We use these data to study various emission components in M 101 and properties of the magnetic field. Separation of thermal and non-thermal emission shows that the thermal emission is closely correlated with the spiral arms, while the non-thermal emission is more smoothly distributed indicating diffusion of cosmic ray electrons away from their places of origin. The radial distribution of both emissions has a break near R=16 kpc, where it steepens to an exponential scale length of about 5 kpc, which is about 2.5 times smaller than at R<16 kpc. The distribution of the polarized emission has a broad maximum near R=12 kpc and beyond R=16 kpc also decreases with about 5 kpc scalelength. It seems that near R=16 kpc a major change in the structure of M 101 takes place, which also affects the distributions of the strength of the random and ordered magnetic field. Be...

  8. Monitoring Polar Environmental Change Using FORMOSAT-2 Satellite

    Science.gov (United States)

    Huang, C.; Liu, C.; Chang, L.; Wang, S.; Yan, K.; Wu, F.; Wu, A.

    2007-12-01

    Polar ice loss to the sea currently account for virtually all of the sea-level rise that is not attributable to ocean warming. Huge section of the Ayles Ice Shelf broke off into the Arctic Ocean. Permafrost soil is losing its permanence across the Northern Hemisphere, altering ecosystems and damaging roads and buildings across Alaska, Canada, and Russia. Global warming change the polar environment significantly, especially in recent year. The National Space Organization (NSPO) of Taiwan successfully launched FORMOSAT-2 on 20 May 2004. The orbit is designed to be high-altitude,. Sun-synchronous, and daily-revisit. With high agility in attitude control, FORMOSAT-2 can cover the polar areas up to +/- 90 deg latitude. More than 72 Area of interests in Alaska, Canada, Greenland area and Ice land have imaged periodically in 2006 and 2007. The images have 2m resolution in panchromatic band and 8m in multispectral bands, with size of about 24 x 100 km or large. The ability of FORMOSAT-2 daily revisit has been extended to monitor the change of topography for the glacier and ice shelf daily, weekly and monthly. By using the FORMOSAT-2 stereo pair, we can determine the elevation profile (DEM) across the glacier surface. In this paper, we will present the mapping and topography of Greenland glaciers and ice land including Kangerdlugssuaq Glacier, Greenland, Belcher Glacier, Canada and Ayles ice island. We will demonstrate the DEM extract ability from FORMOSAT-2 polar stereo images( up to 82 deg latitude), and compared with the DEM of the popular SRTM, ASTER which can be acquired to 79 deg latitude. It is expected that FORMOSAT-2 polar images will be continuously collected for years and contribute to the research of global environmental change.

  9. Polarized neutron scattering on geometrically frustrated magnets with Swedenborgite structure

    Energy Technology Data Exchange (ETDEWEB)

    Valldor, Martin [II. Physikalisches Institut, Universitaet Koeln (Germany); Sanders, Yvonne; Schweika, Werner [Institut fuer Festkoerperforschung, Forschungszentrum Juelich (Germany)

    2009-07-01

    Diffuse scattering of polarized neutrons on cobaltate polycrystalline samples with Swedenborgite structure, ABaCo{sub 3}BO{sub 7} (A=Y Ca, and B=Co Fe,Al,Zn) was used to study the change in magnetic order depending on chemical composition. The atomic structure contains alternate stacking of kagome and triangular layers of metal ions, all in tetrahedral oxygen coordination. Geometrical frustration of antiferromagnetically coupled spins should suppress long-range order even at low temperatures despite strong spin-spin coupling in the Swedenborgites. The diffuse magnetic scattering in Y{sub 0.5}Ca{sub 0.5}BaCo{sub 4}O {sub 7} reveals two dimensional (2D) spin correlations on the Kagome sublattices towards the entropically favoured V3*V3 structure and suggests a decoupling of layers on triangular sites. Co-substitution by Al and Zn yields similar diffuse magnetic scattering, however, spin dilution results in even more disordered spin liquid or spin glass states. With B=Fe or Co, differences in the magnetic scattering evolve, indicating the onset of spin correlations perpendicular to the Kagome layers.

  10. Aggregation of Dodecyl 1-Pyrenylmethyl Ether and Its Application in Structure-Polarity Relations of Aggregates

    Institute of Scientific and Technical Information of China (English)

    SANG,Da-Yong; TIAN,Juan; JI,Guo-Zhen

    2006-01-01

    The aggregation behavior of dodecyl 1-pyrenylmethyl ether was studied in dioxane-water mixture solvents by fluorescence techniques. The labeled pyrenyl group was effective in monitoring the polarity change of its environment during aggregation processes. Based on the structural effects such as chain-length effect, self-coiling effect,and branch-group effect on the polarity of the probe environment, the structure features of aggregates were discussed and have been used to interpret the effect of the structural features on the aggregates formed by three cholesteryl esters and three long chain alkanes.

  11. Polarity Analysis of Texts using Discourse Structure

    NARCIS (Netherlands)

    Heerschop, Bas; Goosen, Frank; Hogenboom, Alexander; Frasincar, Flavius; Kaymak, Uzay; Jong, de Franciska

    2011-01-01

    Sentiment analysis has applications in many areas and the exploration of its potential has only just begun. We propose Pathos, a framework which performs document sentiment analysis (partly) based on a document’s discourse structure. We hypothesize that by splitting a text into important and less im

  12. Linearly Polarized IR Spectroscopy Theory and Applications for Structural Analysis

    CERN Document Server

    Kolev, Tsonko

    2011-01-01

    A technique that is useful in the study of pharmaceutical products and biological molecules, polarization IR spectroscopy has undergone continuous development since it first emerged almost 100 years ago. Capturing the state of the science as it exists today, "Linearly Polarized IR Spectroscopy: Theory and Applications for Structural Analysis" demonstrates how the technique can be properly utilized to obtain important information about the structure and spectral properties of oriented compounds. The book starts with the theoretical basis of linear-dichroic infrared (IR-LD) spectroscop

  13. The milliarcsecond polarization structure of six BL Lacertae objects

    International Nuclear Information System (INIS)

    Milliarcsecond resolution total intensity and linear polarization maps at GHz are presented for the BL Lacertae objects 0235 + 164, 0454 + 844, 1749 + 096, 1823 + 568, and 2200 + 420 (BL Lac). Maps of 1807 + 698 (3C 371), which has in the past been classified either as a BL Lacertae object or an N galaxy, are also presented. Appreciable polarization structure is found in 0454 + 844, 1823 + 568, and BL Lac; in each the polarization position angle in the knots lies within about 10 deg of the structural direction of the VLBI jet, suggesting that plane perpendicular shock waves may be common in these objects. The polarization of 3C 371 is weak, and is quite atypical of BL Lacertae objects. Superluminal motion in 1823 + 568 is suggested. Similar comparison for 0454 + 844 over four epochs confirms proper motion at mu about 0.14 mas/yr. Systematic differences in the VLBI polarization structures of BL Lacertae objects and quasars rule out the possibility that a significant fraction of BL Lacertae objects are gravitationally microlensed quasars. 87 refs

  14. Polarization Control by Using Anisotropic 3D Chiral Structures

    CERN Document Server

    Chen, Menglin L N; Sha, Wei E I; Choy, Wallace C H; Itoh, Tatsuo

    2016-01-01

    Due to the mirror symmetry breaking, chiral structures show fantastic electromagnetic (EM) properties involving negative refraction, giant optical activity, and asymmetric transmission. Aligned electric and magnetic dipoles excited in chiral structures contribute to extraordinary properties. However, the chiral structures that exhibit n-fold rotational symmetry show limited tuning capability. In this paper, we proposed a compact, light, and highly tunable anisotropic chiral structure to overcome this limitation and realize a linear-to-circular polarization conversion. The anisotropy is due to simultaneous excitations of two different pairs of aligned electric and magnetic dipoles. The 3D omega-like structure, etched on two sides of one PCB board and connected by metallic vias, achieves 60% of linearto- circular conversion (transmission) efficiency at the operating frequency of 9.2 GHz. The desired 90-degree phase shift between the two orthogonal linear polarization components is not only from the finite-thick...

  15. Dual polarized receiving steering antenna array for measurement of ultrawideband pulse polarization structure.

    Science.gov (United States)

    Balzovsky, E V; Buyanov, Yu I; Koshelev, V I; Nekrasov, E S

    2016-03-01

    To measure simultaneously two orthogonal components of the electromagnetic field of nano- and subnano-second duration, an antenna array has been developed. The antenna elements of the array are the crossed dipoles of dimension 5 × 5 cm. The arms of the dipoles are connected to the active four-pole devices to compensate the frequency response variations of a short dipole in the frequency band ranging from 0.4 to 4 GHz. The dipoles have superimposed phase centers allowing measuring the polarization structure of the field in different directions. The developed antenna array is the linear one containing four elements. The pattern maximum position is controlled by means of the switched ultrawideband true time delay lines. Discrete steering in seven directions in the range from -40° to +40° has been realized. The error at setting the pattern maximum position is less than 4°. The isolation of the polarization exceeds 29 dB in the direction orthogonal to the array axis and in the whole steering range it exceeds 23 dB. Measurement results of the polarization structure of radiated and scattered pulses with different polarization are presented as well. PMID:27036799

  16. Chemical changes in the Arctic troposphere at polar sunrise

    International Nuclear Information System (INIS)

    At polar sunrise, the Arctic troposphere (0 to ∼8 km) is a unique chemical reactor influenced by human activity and the Arctic Ocean. It is surrounded by industrialized continents that in winter contribute gaseous and particulate pollution (Arctic haze). It is underlain by the flat Arctic Ocean from which it is separated by a crack-ridden ice membrane 3 to 4 m thick. Ocean to atmosphere exchange of heat, water vapor and marine biogenic gases influence the composition of the reactor. From 21 September to 21 December to 21 March, the region north of the Arctic circle goes from a completely sunlit situation to a completely dark one and then back to light. At the same time the lower troposphere is stably stratified. This hinders vertical mixing. In this environment, chemical reactions involving sunlight are much slower than further south. Thus, it would not be surprising to find a high abundance of photochemically reactive compounds in the atmosphere at polar sunrise. Between complete dark in February and complete light in April, a number of chemical changes in the lower troposphere are observed. Perhaps the most sensational is the destruction of lower tropospheric ozone accompanied by production of filterable bromine and iodine. The latter are likely of marine origin, although their production may involve anthropogenic compounds. Another change is the shift in the fraction of total sulfur in its end oxidation state (VI) from 50% to 90%. Several gaseous hydrocarbons disappear from the atmosphere at this time. Preliminary observations also indicate a maximum in total non-black carbon on particulate matter. This is consistent with the formation of non-volatile organics from photochemically induced reactions of gas phase organics. Results of the Canadian Polar Sunrise Experiment 1988 are presented

  17. Thermospheric Neutral Density Responses to Changes in IMF Sector Polarity

    Science.gov (United States)

    Kwak, Y.; Kim, K.; Forbes, J.; Lee, S.

    2008-12-01

    The thermospheric density is important not only for satellite orbital tracking, but also in understanding the thermosphere-ionosphere coupling process as well. Thermospheric density variations are controlled by various sources such as Joule/particle heating, Lorentz force, thermal expansion, upwelling and horizontal wind circulation. These sources are directly or indirectly associated with the direction and/or strength of the interplanetary magnetic field (IMF). That is, there is an intimate relationship between IMF variation and thermospheric density variation. In order to examine how thermospheric density variations are influenced on the orientation and/or strength of the IMF, we used total mass density around 400 km, derived from the high- accuracy accelerometer on board the Challenging Minisatellite Payload (CHAMP) spacecraft, in 2003 when the IMF exhibited a well-defined sector polarity change with a ~27-day periodicity; directed toward the Sun (i.e., +Bx and -By) and away the Sun (-Bx and +By). It has been known that the IMF By in GSE coordinates makes a positive or negative IMF Bz offset in GSM coordinate. We discuss whether the thermospheric total mass density from CHAMP changes with the IMF sector polarity.

  18. Local magnetic structure determination using polarized neutron holography

    Energy Technology Data Exchange (ETDEWEB)

    Szakál, Alex, E-mail: szakal.alex@wigner.mta.hu; Markó, Márton, E-mail: marko.marton@wigner.mta.hu; Cser, László, E-mail: cser.laszlo@wigner.mta.hu [Wigner Research Centre for Physics, Konkoly Thege M. út 29-33, H-1121 Budapest (Hungary)

    2015-05-07

    A unique and important property of the neutron is that it possesses magnetic moment. This property is widely used for determination of magnetic structure of crystalline samples observing the magnetic components of the diffraction peaks. Investigations of diffraction patterns give information only about the averaged structure of a crystal but for discovering of local spin arrangement around a specific (e.g., impurity) nucleus remains still a challenging problem. Neutron holography is a useful tool to investigate the local structure around a specific nucleus embedded in a crystal lattice. The method has been successfully applied experimentally in several cases using non-magnetic short range interaction of the neutron and the nucleus. A mathematical model of the hologram using interaction between magnetic moment of the atom and the neutron spin for polarized neutron holography is provided. Validity of a polarized neutron holographic experiment is demonstrated by applying the proposed method on model systems.

  19. Climate change threatens polar bear populations: A stochastic demographic analysis

    Science.gov (United States)

    Hunter, C.M.; Caswell, H.; Runge, M.C.; Regehr, E.V.; Amstrup, Steven C.; Stirling, I.

    2010-01-01

    The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with forecasts of future sea ice conditions from IPCC general circulation models (GCMs). The matrix population models classified individuals by age and breeding status; mothers and dependent cubs were treated as units. Parameter estimates were obtained from a capture-recapture study conducted from 2001 to 2006. Candidate statistical models allowed vital rates to vary with time and as functions of a sea ice covariate. Model averaging was used to produce the vital rate estimates, and a parametric bootstrap procedure was used to quantify model selection and parameter estimation uncertainty. Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in ?? in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log ??s, as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log ??s ' - 0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with "business as usual" (A1B) greenhouse gas emissions. The resulting stochastic population projections showed drastic

  20. Low temperature polarized target for spin structure studies of nucleons at COMPASS

    CERN Document Server

    Pesek, Michael

    In presented thesis we describe concept of Deep Inelastic Scattering of leptons on nucleons in context of nucleon spin structure studies. Both polarized and unpolarized cases are discussed and concept of Transverse Momentum Dependent Parton Distribution Functions (TMD PDF) is introduced. The possibility of TMDs measurement using Semi-inclusive DIS (SIDIS) is described along with related results from COMPASS experiment. The future Drell-Yan programme at COMPASS is briefly mentioned and its importance is presented on the universality test i.e. change of sign of T-odd TMDs when measured in Drell-Yan and SIDIS. The importance of Polarized Target (PT) for spin structure studies is highlighted and principles of Dynamic Nuclear Polarization (DNP) are given using both Solid effect and spin temperature concept. COMPASS experiment is described in many details with accent given to PT. Finally the thermal equilibrium (TE) calibration procedure is described and carried out for 2010 and 2011 physics runs at COMPASS. The av...

  1. Chiral Huygens metasurfaces for nonlinear structuring of linearly polarized light

    CERN Document Server

    Lesina, A Calà; Ramunno, L

    2016-01-01

    We report on a chiral nanostructure, which we term a "butterfly nanoantenna," that, when used in a metasurface, allows the direct conversion of a linearly polarized beam into a nonlinear optical far-field of arbitrary complexity. The butterfly nanoantenna exhibits field enhancement in its gap for every incident linear polarization, which can be exploited to drive nonlinear optical emitters within the gap, for the structuring of light within a frequency range not accessible by linear plasmonics. As the polarization, phase and amplitude of the field in the gap are highly controlled, nonlinear emitters within the gap behave as an idealized Huygens source. A general framework is thereby proposed wherein the butterfly nanoantennas can be arranged on a surface to produce a highly structured far-field nonlinear optical beam with high purity. A third harmonic Laguerre-Gauss beam carrying an optical orbital angular momentum of 41 is demonstrated as an example, through large-scale simulations on a high-performance comp...

  2. Polarized sphingolipid transport from the subapical compartment changes during cell polarity development

    NARCIS (Netherlands)

    van Ijzendoorn, SCD; Hoekstra, D

    2000-01-01

    The subapical compartment (SAC) plays an important role in the polarized transport of proteins and lipids. In hepatoma-derived HepG2 cells, fluorescent analogues of sphingomyelin and glucosylceramide are sorted in the SAG. Here, evidence is provided that shows that polarity development is regulated

  3. Effects of climatic changes on anisakid nematodes in polar regions

    Science.gov (United States)

    Rokicki, Jerzy

    2009-11-01

    Anisakid nematodes are common in Antarctic, sub-Antarctic, and Arctic areas. Current distributional knowledge of anisakids in the polar regions is reviewed. Climatic variables influence the occurrence and abundance of anisakids, directly influencing their free-living larval stages and also indirectly influencing their predominantly invertebrate (but also vertebrate) hosts. As these parasites can also be pathogenic for humans, the paucity of information available is a source of additional hazard. As fish are a major human dietary component in Arctic and Antarctic areas, and are often eaten without heat processing, a high risk of infection by anisakid larvae might be expected. The present level of knowledge, particularly relating to anisakid larval stages present in fishes, is far from satisfactory. Preliminary molecular studies have revealed the presence of species complexes. Contemporary climate warming is modifying the marine environment and may result in an extension of time during which anisakid eggs can persist and hatch, and of the time period during which newly hatched larvae remain viable. As a result there may be an increase in the extent of anisakid distribution. Continued warming will modify the composition of the parasitic nematode fauna of marine animals, due to changes in feeding habits, as the warming of the sea and any localised reduction in salinity (from freshwater runoff) can be expected to bring about changes in the species composition of pelagic and benthic invertebrates.

  4. CHANG-ES VIII: Uncovering Hidden AGN Activity in Radio Polarization

    CERN Document Server

    Irwin, Judith A; Damas-Segovia, A; Beck, Rainer; English, Jayanne; Heald, George; Henriksen, Richard N; Krause, Marita; Li, Jiang-Tao; Rand, Richard J; Wang, Q Daniel; Wiegert, Theresa; Kamieneski, Patrick; Paré, Dylan; Sullivan, Kendall

    2016-01-01

    We report on C-band (5 - 7 GHz) observations of the galaxy, NGC~2992, from the CHANG-ES sample. This galaxy displays an embedded nuclear double-lobed radio morphology within its spiral disk, as revealed in linearly polarized emission but {\\it not} in total intensity emission. The radio lobes are kpc-sized, similar to what has been observed in the past for other Seyfert galaxies, and show ordered magnetic fields. NGC~2992 has shown previous evidence for AGN-related activity, but not the linearly polarized radio features that we present here. We draw attention to this galaxy as the first clear example (and prototype) of bipolar radio outflow that is revealed in linearly polarized emission only. Such polarization observations, which are unobscured by dust, provide a new tool for uncovering hidden weak AGN activity which may otherwise be masked by brighter unpolarized emission within which it is embedded. The radio lobes observed in NGC~2992 are interacting with the surrounding interstellar medium and offer new o...

  5. Seasonal and Annual Change in the Martian Polar Regions

    Science.gov (United States)

    Calvin, W. M.; James, P. B.

    2011-12-01

    The polar caps have a long established dichotomy in visual appearance, relative elevations, and surface composition. Observations using the Mars Reconnaissance Orbiter (MRO) instruments MARCI, CTX and CRISM have shown unique styles of seasonal frost retreat as well as fine scale variations in the composition of various units. With MRO we have observations for three Martian Years (MY) 28, 29 and 30 from November of 2006 to the present. We have observed the seasonal cap recessions in both the north and south using MARCI daily global images and have examined the composition of selected units of the polar layered deposits exposed in summer. Observation over multiple Mars years allows us to compare changes between years as well as longer term evolution of the high albedo deposits at the poles. North Cap Recession and Change: The northern seasonal cap recession was observed in both MY 29 and 30. Past work had noted large scale loss of bright deposits up to Ls 95 and the rugged terrain of the Gemini Scopuli darkens up to ~Ls 100 and then subsequently brightens. The patterns observed in MY 29 and 30 are similar. Significant variability in the early season is noted in both years and the retreating seasonal cap edge is extremely dynamic. Additional retreat of high albedo deposits are noted in MY 30. A new high albedo deposit appears off a reentrant in Olympia Planum in MY 29 and later disappears. In MY30, portions of Olympia Planitia have larger areas of high albedo. In both years sustained bright patches appear along the cap margins and while some are persistent between years, they are also variable over the northern summer. It is still uncertain if these albedo changes represent volatile "refrosting" or the removal of low albedo material to expose higher albedo material underneath and whether or not longer term loss of volatiles is implied. South Cap Recession and Change: The southern seasonal cap recession is fundamentally different than the north, and persistence of

  6. PoLAR Voices: Informing Adult Learners about the Science and Story of Climate Change in the Polar Regions Through Audio Podcast

    Science.gov (United States)

    Quinney, A.; Murray, M. S.; Gobroski, K. A.; Topp, R. M.; Pfirman, S. L.

    2015-12-01

    The resurgence of audio programming with the advent of podcasting in the early 2000s spawned a new medium for communicating advances in science, research, and technology. To capitalize on this informal educational outlet, the Arctic Institute of North America partnered with the International Arctic Research Center, the University of Alaska Fairbanks, and the UA Museum of the North to develop a podcast series called PoLAR Voices for the Polar Learning and Responding (PoLAR) Climate Change Education Partnership. PoLAR Voices is a public education initiative that uses creative storytelling and novel narrative structures to immerse the listener in an auditory depiction of climate change. The programs will feature the science and story of climate change, approaching topics from both the points of view of researchers and Arctic indigenous peoples. This approach will engage the listener in the holistic story of climate change, addressing both scientific and personal perspectives, resulting in a program that is at once educational, entertaining and accessible. Feedback is being collected at each stage of development to ensure the content and format of the program satisfies listener interests and preferences. Once complete, the series will be released on thepolarhub.org and on iTunes. Additionally, blanket distribution of the programs will be accomplished via radio broadcast in urban, rural and remote areas, and in multiple languages to increase distribution and enhance accessibility.

  7. On arc-polarized structures in the solar wind

    Directory of Open Access Journals (Sweden)

    B. U. Ö. Sonnerup

    2010-06-01

    Full Text Available A theoretical model is proposed to account for some of the behavior of arc-polarized magnetic structures seen in the solar wind. To this end, an exact analytical solution is developed that describes infinite plane wave trains of arbitrary amplitude in a plasma governed by ideal Hall MHD. The main focus is on intermediate-mode wave trains, which display double-branched magnetic hodogram signatures similar to those seen in the solar wind. The theoretically derived hodograms have field rotation in the ion-polarized sense at a slightly depressed field magnitude on one branch and an electron-polarized rotation at a slightly enhanced field magnitude on the other branch. The two branches are joined at the two "turning points", at which the normal flow is exactly Alfvénic. The behavior is accounted for in terms of the opposite dispersive properties of ion and electron whistlers. The hodograms derived from the theory are shown to compare favorably with those of one event, observed by the Cluster spacecraft near the ecliptic plane, and one event at high heliographic latitude observed by the Ulysses spacecraft. However, these two observed structures comprise only a single full wave period, approximately from one turning point to the other and then back again. The theory can be used to predict propagation direction (away from, or towards, the sun from magnetic data alone, provided the sign of the magnetic field component along the wave normal can be reliably determined. Under the same condition, it also predicts whether the ion-polarized branch should precede or follow the electron-polarized branch. Both behaviors are seen in the solar wind. The major shortcoming of the theory is that it fails to reproduce the observed saw-tooth like time series for the magnetic field, in which the field rotation is rapid in the ion sense and slow in the electron sense. Instead, the theory gives about the same rotation rates. Possible explanations for this discrepancy are

  8. Polar semiconductor heterojunction structure energy band diagram considerations

    Science.gov (United States)

    Lin, Shuxun; Wen, Cheng P.; Wang, Maojun; Hao, Yilong

    2016-03-01

    The unique nature of built-in electric field induced positive/negative charge pairs of polar semiconductor heterojunction structure has led to a more realistic device model for hexagonal III-nitride HEMT. In this modeling approach, the distribution of charge carriers is dictated by the electrostatic potential profile instead of Femi statistics. The proposed device model is found suitable to explain peculiar properties of GaN HEMT structures, including: (1) Discrepancy in measured conventional linear transmission line model (LTLM) sheet resistance and contactless sheet resistance of GaN HEMT with thin barrier layer. (2) Below bandgap radiation from forward biased Nickel Schottky barrier diode on GaN HEMT structure. (3) GaN HEMT barrier layer doping has negligible effect on transistor channel sheet charge density.

  9. Modulated nematic structures induced by chirality and steric polarization

    Science.gov (United States)

    Longa, Lech; PajÄ k, Grzegorz

    2016-04-01

    What kind of one-dimensional modulated nematic structures (ODMNS) can form nonchiral and chiral bent-core and dimeric materials? Here, using the Landau-de Gennes theory of nematics, extended to account for molecular steric polarization, we study a possibility of formation of ODMNS, both in nonchiral and intrinsically chiral liquid crystalline materials. Besides nematic and cholesteric phases, we find four bulk ODMNS for nonchiral materials, two of which, to the best of our knowledge, have not been reported so far. These two structures are longitudinal (NLP) and transverse (NTP) periodic waves where the polarization field being periodic in one dimension stays parallel and perpendicular, respectively, to the wave vector. The other two phases are the twist-bend nematic phase (NTB) and the splay-bend nematic phase (NSB), but their fine structure appears more complex than that considered so far. The presence of molecular chirality converts nonchiral NTP and NSB into new NTB phases. Surprisingly, the nonchiral NLP phase can stay stable even in the presence of intrinsic chirality.

  10. Polarized Structure Function of Nucleon and Orbital Angular Momentum

    Science.gov (United States)

    Arash, Firooz; Taghavi-Shahri, Fatemeh

    2007-06-01

    We have utilized the concept of valon model to calculate the spin structure function of a constituent quark. This structure is universal and arises from perturbative dressing of a valence quark in QCD. With a convolution method the polarized structure functions of proton, neutron, and deuteron are obtained. Our results agree rather well with all available experimental data. It suggests that the sea quark contribution to the spin of nucleon is consistent with zero, in agreement with HERMES data. It also reveals that while the total quark contribution to the spin of a constituent quark, or valon, is almost constant and equal to one, the gluon contribution grows with the increase of Q2, and hence, requiring a sizable negative angular momentum contribution. This component, as well as singlet and non-singlet parts are calculated in the Next-to-Leading order in QCD. We speculate that the gluon contribution to the spin of proton is in the order of 50%. Furthermore, we have determined the polarized valon distribution in a nucleon.

  11. Large amplitude nonlinear structures in the nighttime polar mesosphere

    Science.gov (United States)

    Maharaj, Shimul K.; Bharuthram, Ramashwar; Singh Lakhina, Gurbax; Muralikrishna, Polinaya; Singh, Satyavir

    2016-07-01

    The existence of large amplitude potential structures will be investigated for a plasma composed of negative ions, positive ions, electrons and an additional fourth component of charged (usually positive) nano-sized ions in an attempt to model the plasma composition in the nighttime polar mesosphere (˜80 - 90 km altitude) [1]. The fourth ionic component becomes positively charged if there is a high enough concentration of negative ions which are sufficiently heavy. The positive charge on the fourth component can be explained by the capture of currents, and is not a result of photo-emission and secondary electron emission processes. Consequently, if the negative ions are much lighter, then the fourth ion component will become negatively charged. The charged ion species will be treated as inertial species which are cold or adiabatic, whilst the electrons will be considered to be Boltzmann-distributed (isothermal). Taking into consideration not only the dynamics of the heaviest species (dust-acoustic) but also the lighter ions (ion-acoustic), the theoretical study will use the Sagdeev pseudo-potential formalism to explore the existence of arbitrary amplitude solitons and double layer potential structures. [1] Observations of positively charged nanoparticles in the nighttime polar mesosphere, M. Rapp, J. Hedin, I. Strelnikova, M. Friederich, J. Gumbel, and F.˜J. Lübken, Geophys. Res. Letters. 32, L23821, doi:10.1029/2005GL024676 (2005).

  12. Characterizing microstructural changes of skeletal muscle tissues using spectral transformed Mueller matrix polarization parameters

    Science.gov (United States)

    He, Chao; He, Honghui; Chang, Jintao; Ma, Hui

    2016-03-01

    Polarization imaging techniques are recognized as potentially powerful tools to detect the structural changes of biological tissues. Meanwhile, spectral features of the scattered light can also provide abundant microstructural information, therefore can be applied in biomedical studies. In this paper, we adopt the polarization reflectance spectral imaging to analyze the microstructural changes of hydrolyzing skeletal muscle tissues. We measure the Mueller matrix, which is a comprehensive description of the polarization properties, of the bovine skeletal muscle samples in different periods of time, and analyze its behavior using the multispectral Mueller matrix transformation (MMT) technique. The experimental results show that for bovine skeletal muscle tissues, the backscattered spectral MMT parameters have different values and variation features at different stages. We can also find the experimental results indicate that the stages of hydrolysis for bovine skeletal muscle samples can be judged by the spectral MMT parameters. The results presented in this work show that combining with the spectral technique, the MMT parameters have the potential to be used as tools for meat quality detection and monitoring.

  13. Circumpolar Genetic Structure and Recent Gene Flow of Polar Bears: A Reanalysis.

    Directory of Open Access Journals (Sweden)

    René M Malenfant

    Full Text Available Recently, an extensive study of 2,748 polar bears (Ursus maritimus from across their circumpolar range was published in PLOS ONE, which used microsatellites and mitochondrial haplotypes to apparently show altered population structure and a dramatic change in directional gene flow towards the Canadian Archipelago-an area believed to be a future refugium for polar bears as their southernmost habitats decline under climate change. Although this study represents a major international collaborative effort and promised to be a baseline for future genetics work, methodological shortcomings and errors of interpretation undermine some of the study's main conclusions. Here, we present a reanalysis of this data in which we address some of these issues, including: (1 highly unbalanced sample sizes and large amounts of systematically missing data; (2 incorrect calculation of FST and of significance levels; (3 misleading estimates of recent gene flow resulting from non-convergence of the program BayesAss. In contrast to the original findings, in our reanalysis we find six genetic clusters of polar bears worldwide: the Hudson Bay Complex, the Western and Eastern Canadian Arctic Archipelago, the Western and Eastern Polar Basin, and-importantly-we reconfirm the presence of a unique and possibly endangered cluster of bears in Norwegian Bay near Canada's expected last sea-ice refugium. Although polar bears' abundance, distribution, and population structure will certainly be negatively affected by ongoing-and increasingly rapid-loss of Arctic sea ice, these genetic data provide no evidence of strong directional gene flow in response to recent climate change.

  14. Circumpolar Genetic Structure and Recent Gene Flow of Polar Bears: A Reanalysis.

    Science.gov (United States)

    Malenfant, René M; Davis, Corey S; Cullingham, Catherine I; Coltman, David W

    2016-01-01

    Recently, an extensive study of 2,748 polar bears (Ursus maritimus) from across their circumpolar range was published in PLOS ONE, which used microsatellites and mitochondrial haplotypes to apparently show altered population structure and a dramatic change in directional gene flow towards the Canadian Archipelago-an area believed to be a future refugium for polar bears as their southernmost habitats decline under climate change. Although this study represents a major international collaborative effort and promised to be a baseline for future genetics work, methodological shortcomings and errors of interpretation undermine some of the study's main conclusions. Here, we present a reanalysis of this data in which we address some of these issues, including: (1) highly unbalanced sample sizes and large amounts of systematically missing data; (2) incorrect calculation of FST and of significance levels; (3) misleading estimates of recent gene flow resulting from non-convergence of the program BayesAss. In contrast to the original findings, in our reanalysis we find six genetic clusters of polar bears worldwide: the Hudson Bay Complex, the Western and Eastern Canadian Arctic Archipelago, the Western and Eastern Polar Basin, and-importantly-we reconfirm the presence of a unique and possibly endangered cluster of bears in Norwegian Bay near Canada's expected last sea-ice refugium. Although polar bears' abundance, distribution, and population structure will certainly be negatively affected by ongoing-and increasingly rapid-loss of Arctic sea ice, these genetic data provide no evidence of strong directional gene flow in response to recent climate change. PMID:26974333

  15. Refinement of circular-polarization based on multilayer film structure

    Institute of Scientific and Technical Information of China (English)

    LI Bin; LEE Kuei-jen; CHOU His-tseng; HUANG Shan-guo; GU Wan-yi

    2009-01-01

    Circular-polarization discrimination appears in many antennas' applications. A compensation approach based on multilayer film structure is proposed to improve the axial ratio of the magnitude of the two perpendicular modes of the lump ports. The goal is to widen the beamwidth of radiation that has an axial ratio less than 3 dB and thus reducing the complexity at the receiver. A transfer matrix method was developed to represent the multilayer film and characterize its performance. Simulation using high frequency structure simulator shows that a crossed dipole, as an example, can achieve a beamwidth of more than at the frequency of 12.45 GHz after compensation. Finally, conclusions and future work about this compensation method are presented.

  16. More about arc-polarized structures in the solar wind

    International Nuclear Information System (INIS)

    We report results from a Cluster-based study of the properties of 28 arc-polarized magnetic structures (also called rotational discontinuities) in the solar wind. These Alfv'enic events were selected from the database created and analyzed by Knetter (2005) by use of criteria chosen to eliminate ambiguous cases. His studies showed that standard, four-spacecraft timing analysis in most cases lacks sufficient accuracy to identify the small normal magnetic field components expected to accompany such structures, leaving unanswered the question of their existence. Our study aims to break this impasse. By careful application of minimum variance analysis of the magnetic field (MVAB) from each individual spacecraft, we show that, in most cases, a small but significantly non-zero magnetic field component was present in the direction perpendicular to the discontinuity. In the very few cases where this component was found to be large, examination revealed that MVAB had produced an unusual and unexplained orientation of the normal vector. On the whole, MVAB shows that many verifiable rotational discontinuities (Bn ≠ 0) exist in the solar wind and that their eigenvalue ratio (EVR = intermediate/minimum variance) can be extremely large (up to EVR = 400). Each of our events comprises four individual spacecraft crossings. The events include 17 ionpolarized cases and 11 electron-polarized ones. Fifteen of the ion events have widths ranging from 9 to 21 ion inertial lengths, with two outliers at 46 and 54. The electronpolarized events are generally thicker: nine cases fall in the range 20-71 ion inertial lengths, with two outliers at 9 and 13. In agreement with theoretical predictions from a onedimensional, ideal, Hall-MHD description (Sonnerup et al., 2010), the ion-polarized events show a small depression in field magnitude, while the electron-polarized ones tend to show a small enhancement. This effect was also predicted by Wu and Lee (2000). Judging only from the sense of the

  17. Light switching at low light level based on changes in light polarization

    International Nuclear Information System (INIS)

    We studied the polarization spectroscopy of a linearly-polarized optical (probe) field in a multi-Zeeman-sublevel atomic system of the 87Rb D1 line. The polarization spectroscopy signals of the probe light result from the changes in its polarization, which are caused by a left-circularly polarized pumping beam. A theoretical analysis involving multiple Zeeman sublevels is presented and the results are in qualitative agreement with the experimental observations. Based on this phenomenon, we demonstrated a light switch at low light level (∼68 photons per λ2/2π) with a switching efficiency of ∼3%

  18. Light switching at low light level based on changes in light polarization

    Energy Technology Data Exchange (ETDEWEB)

    Yang Xudong; Li Shujing; Cao Xuemin; Wang Hai [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China)], E-mail: wanghai@sxu.edu.cn

    2008-04-28

    We studied the polarization spectroscopy of a linearly-polarized optical (probe) field in a multi-Zeeman-sublevel atomic system of the {sup 87}Rb D1 line. The polarization spectroscopy signals of the probe light result from the changes in its polarization, which are caused by a left-circularly polarized pumping beam. A theoretical analysis involving multiple Zeeman sublevels is presented and the results are in qualitative agreement with the experimental observations. Based on this phenomenon, we demonstrated a light switch at low light level ({approx}68 photons per {lambda}{sup 2}/2{pi}) with a switching efficiency of {approx}3%.

  19. Radiation-induced structural changes. 4

    International Nuclear Information System (INIS)

    This seminar was held for discussion on recent progress in experimental investigation of positron and its application to material science. Fundamental characteristics of positronium, measuring method, molecular structure of positronium, and its annihilation and reaction, in liquid phase positronium chemistry are reported. The nonthermal positrons (0.25-2.5 keV) are occurred in KURRI-LINAC, slow positrons are found out by moderating with solid xenon film. Positronium formation in insulating materials are reported. Positron lifetime and insulating rupture strength are measured with epoxy resin and fluororesin changing bridging density, experimental materials temperature, gamma ray dose Free-volume studies on polymer in multiphase systems are evaluated using the method of spin labeling, the molecular dynamics of polymer chains are discussed. The anisotropy diffusion process on structural relaxation of linear polymers are described, introducing the molecular dynamics simulation of polarization and stress relaxation of ferroelectric polymers. (J.P.N.)

  20. Implications of the circumpolar genetic structure of polar bears for their conservation in a rapidly warming Arctic.

    Science.gov (United States)

    Peacock, Elizabeth; Sonsthagen, Sarah A; Obbard, Martyn E; Boltunov, Andrei; Regehr, Eric V; Ovsyanikov, Nikita; Aars, Jon; Atkinson, Stephen N; Sage, George K; Hope, Andrew G; Zeyl, Eve; Bachmann, Lutz; Ehrich, Dorothee; Scribner, Kim T; Amstrup, Steven C; Belikov, Stanislav; Born, Erik W; Derocher, Andrew E; Stirling, Ian; Taylor, Mitchell K; Wiig, Øystein; Paetkau, David; Talbot, Sandra L

    2015-01-01

    We provide an expansive analysis of polar bear (Ursus maritimus) circumpolar genetic variation during the last two decades of decline in their sea-ice habitat. We sought to evaluate whether their genetic diversity and structure have changed over this period of habitat decline, how their current genetic patterns compare with past patterns, and how genetic demography changed with ancient fluctuations in climate. Characterizing their circumpolar genetic structure using microsatellite data, we defined four clusters that largely correspond to current ecological and oceanographic factors: Eastern Polar Basin, Western Polar Basin, Canadian Archipelago and Southern Canada. We document evidence for recent (ca. last 1-3 generations) directional gene flow from Southern Canada and the Eastern Polar Basin towards the Canadian Archipelago, an area hypothesized to be a future refugium for polar bears as climate-induced habitat decline continues. Our data provide empirical evidence in support of this hypothesis. The direction of current gene flow differs from earlier patterns of gene flow in the Holocene. From analyses of mitochondrial DNA, the Canadian Archipelago cluster and the Barents Sea subpopulation within the Eastern Polar Basin cluster did not show signals of population expansion, suggesting these areas may have served also as past interglacial refugia. Mismatch analyses of mitochondrial DNA data from polar and the paraphyletic brown bear (U. arctos) uncovered offset signals in timing of population expansion between the two species, that are attributed to differential demographic responses to past climate cycling. Mitogenomic structure of polar bears was shallow and developed recently, in contrast to the multiple clades of brown bears. We found no genetic signatures of recent hybridization between the species in our large, circumpolar sample, suggesting that recently observed hybrids represent localized events. Documenting changes in subpopulation connectivity will allow

  1. Implications of the circumpolar genetic structure of polar bears for their conservation in a rapidly warming Arctic.

    Directory of Open Access Journals (Sweden)

    Elizabeth Peacock

    Full Text Available We provide an expansive analysis of polar bear (Ursus maritimus circumpolar genetic variation during the last two decades of decline in their sea-ice habitat. We sought to evaluate whether their genetic diversity and structure have changed over this period of habitat decline, how their current genetic patterns compare with past patterns, and how genetic demography changed with ancient fluctuations in climate. Characterizing their circumpolar genetic structure using microsatellite data, we defined four clusters that largely correspond to current ecological and oceanographic factors: Eastern Polar Basin, Western Polar Basin, Canadian Archipelago and Southern Canada. We document evidence for recent (ca. last 1-3 generations directional gene flow from Southern Canada and the Eastern Polar Basin towards the Canadian Archipelago, an area hypothesized to be a future refugium for polar bears as climate-induced habitat decline continues. Our data provide empirical evidence in support of this hypothesis. The direction of current gene flow differs from earlier patterns of gene flow in the Holocene. From analyses of mitochondrial DNA, the Canadian Archipelago cluster and the Barents Sea subpopulation within the Eastern Polar Basin cluster did not show signals of population expansion, suggesting these areas may have served also as past interglacial refugia. Mismatch analyses of mitochondrial DNA data from polar and the paraphyletic brown bear (U. arctos uncovered offset signals in timing of population expansion between the two species, that are attributed to differential demographic responses to past climate cycling. Mitogenomic structure of polar bears was shallow and developed recently, in contrast to the multiple clades of brown bears. We found no genetic signatures of recent hybridization between the species in our large, circumpolar sample, suggesting that recently observed hybrids represent localized events. Documenting changes in subpopulation

  2. Polarization-dependent diffraction in all-dielectric, twisted-band structures

    Science.gov (United States)

    Kardaś, Tomasz M.; Jagodnicka, Anna; Wasylczyk, Piotr

    2015-11-01

    We propose a concept for light polarization management: polarization-dependent diffraction in all-dielectric microstructures. Numerical simulations of light propagation show that with an appropriately configured array of twisted bands, such structures may exhibit zero birefringence and at the same time diffract two circular polarizations with different efficiencies. Non-birefringent structures as thin as 3 μm have a significant difference in diffraction efficiency for left- and right-hand circular polarizations. We identify the structural parameters of such twisted-band matrices for optimum performance as circular polarizers.

  3. Polarization-dependent diffraction in all-dielectric, twisted-band structures

    Energy Technology Data Exchange (ETDEWEB)

    Kardaś, Tomasz M.; Jagodnicka, Anna; Wasylczyk, Piotr, E-mail: pwasylcz@fuw.edu.pl [Photonic Nanostructure Facility, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa (Poland)

    2015-11-23

    We propose a concept for light polarization management: polarization-dependent diffraction in all-dielectric microstructures. Numerical simulations of light propagation show that with an appropriately configured array of twisted bands, such structures may exhibit zero birefringence and at the same time diffract two circular polarizations with different efficiencies. Non-birefringent structures as thin as 3 μm have a significant difference in diffraction efficiency for left- and right-hand circular polarizations. We identify the structural parameters of such twisted-band matrices for optimum performance as circular polarizers.

  4. Clarification on Polarity of Bipolar Electric Field Solitary Structures in Space Plasmas with Satellite Observation

    Institute of Scientific and Technical Information of China (English)

    M. N. S.Qureshi; SHI Jian-Kui; LIU Zhen-Xing; Klaus Torkar

    2011-01-01

    The bipolar electric field solitary (EFS) structures observed frequently in space plasmas by satellites have two different polarities, first positive electric field peak then negative (i.e., positive/negative) and first negative then positive peak (i.e., negative/positive). We provide the physical explanation on the polarity of observed bipolar EFS structures with an electrostatic ion fluid model. The results show that ii initial electric field E0 > 0, the polarity of the bipolar EFS structure will be positive/negative; and if E0 < 0, the polarity of the bipolar EFS structure will be negative/positive. However, for a fixed polarity of the EFS, either positive/negative or negative/positive, if the satellite is located at the positive side of the EFS, the observed polarity should be positive/negative, if the satellite is located at the negative side of the EFS, the observed polarity should be negative/positive. Therefore, we provide a method to clarify the natural polarity of the EFS with observed polarity by satellites. Our results are significant to understand the physical process in space plasma with the satellite observation.%@@ The bipolar electric field solitary (EFS) structures observed frequently in space plasmas by satellites have two different polarities, first positive electric Held peak then negative (i.e., positive/negative) and first negative then positive peak (i.e., negative/positive).We provide the physical explanation on the polarity of observed bipolar EFS structures with an electrostatic ion fluid model.

  5. Polar POLICRYPS Diffractive Structures Generate Cylindrical Vector Beams

    CERN Document Server

    Alj, Domenico; Volpe, Giovanni; Caputo, Roberto; Umeton, Cesare

    2015-01-01

    Local shaping of the polarization state of a light beam is appealing for a number of applications. This can be achieved by employing devices containing birefringent materials. In this article, we present one such device that permits one to convert a uniformly circularly polarized beam into a cylindrical vector beam (CVB). This device has been fabricated by exploiting the POLICRYPS photocuring technique. It is a liquid-crystal-based optical diffraction grating featuring polar symmetry of the director alignment. We have characterized the resulting CVB profile and polarization for the cases of left and right circularly polarized incoming beams.

  6. Polar POLICRYPS diffractive structures generate cylindrical vector beams

    Energy Technology Data Exchange (ETDEWEB)

    Alj, Domenico; Caputo, Roberto, E-mail: roberto.caputo@fis.unical.it; Umeton, Cesare [Department of Physics and CNR-NANOTEC University of Calabria, I-87036 Rende (CS) (Italy); Paladugu, Sathyanarayana [Soft Matter Lab, Department of Physics, Bilkent University, Ankara 06800 (Turkey); Volpe, Giovanni [Soft Matter Lab, Department of Physics, Bilkent University, Ankara 06800 (Turkey); UNAM-National Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey)

    2015-11-16

    Local shaping of the polarization state of a light beam is appealing for a number of applications. This can be achieved by employing devices containing birefringent materials. In this article, we present one such enables converting a uniformly circularly polarized beam into a cylindrical vector beam (CVB). This device has been fabricated by exploiting the POLICRYPS (POlymer-LIquid CRYstals-Polymer-Slices) photocuring technique. It is a liquid-crystal-based optical diffraction grating featuring polar symmetry of the director alignment. We have characterized the resulting CVB profile and polarization for the cases of left and right circularly polarized incoming beams.

  7. Fermionic out-of-plane structure of polarization singularities

    CERN Document Server

    Dennis, Mark R

    2011-01-01

    A new classification of circular polarization C points in three-dimensional polarization ellipse fields is proposed. The classification type depends on the out-of-plane variation of the polarization ellipse axis, in particular, whether the ellipse axes are in the plane of circular polarization one or three times. A minimal set of parameters for this classification are derived, and discussed in the context of the familiar in-plane C point classification into lemon, star, and monstar types. This new geometric classification is related to the M\\"obius index of polarization singularities recently introduced by Freund.

  8. Terahertz wave polarization beam splitter using a cascaded multimode interference structure.

    Science.gov (United States)

    Li, Jiu-sheng; Liu, Han; Zhang, Le

    2014-08-01

    A terahertz wave polarization beam splitter, based on two cascaded multimode interference structures with different widths, is designed and numerically demonstrated. The numerical calculation results show that the designed polarization beam splitter can split transverse-electric (TE) and transverse-magnetic (TM)-polarized terahertz waves into different propagation directions with high efficiency over a frequency range from 6.40 to 6.50 THz. This polarization beam splitter shows more than a 22.06 dB extinction ratio for TE-polarization and a 31.65 dB extinction ratio for TM-polarization. Using such a polarization beam splitter, the whole length of the polarization beam splitter is reduced to about 1/12 that of a conventional design. This enables the polarization beam splitter to be used in terahertz wave integrated circuit fields.

  9. Polarized Neutron in Structural Biology Present and Future Outlook

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jinkui [ORNL; Robertson, Lee [ORNL; Herwig, Kenneth W [ORNL; Crabb, Don [University of Virginia

    2013-01-01

    Hydrogen has a strong polarization-dependent neutron scattering cross section. This property has been exploited in the study of soft matters, especially biological macromolecules. When a polarized neutron beam is scattered off a polarized hydrogenous sample, the otherwise large hydrogen incoherent cross section is drastically reduced while the coherent signal is significantly increased. Past experiments have demonstrated the potentials and benefits of polarized neutron scattering from soft materials. The main technical challenge of polarized neutron scattering from biological matters lies at sample polarization. Dynamic nuclear polarization is a proven yet rather sophisticated technique. Its complexity is one of the main reasons for the technique's slow adoption. The future of polarized neutron scattering in biology may rest largely in neutron protein crystallography. Polarization of protein crystals is much easier to accomplish, since protein crystals are typically rather small (<<1 mm) and only require small and easy- to-operate polarization apparatuses. In addition, the high resolution nature of neutron protein crystallography means that we will be able to study individual atoms using the polarized neutron scattering technique.

  10. Does subduction polarity changes below the Alps? Inferences from analogue modelling

    NARCIS (Netherlands)

    Luth, S.; Willingshofer, E.; Sokoutis, D.; Cloetingh, S.

    2013-01-01

    The surface expression of a lateral polarity change of continental mantle lithosphere subduction has been studied by using lithosphere-scale physical models. Key parameters investigated were: the degree of lateral coupling between adjacent domains of opposing subduction polarity, the width of the zo

  11. Polarized structure of nucleon in the valon representation

    Science.gov (United States)

    Arash, Firooz; Taghavi-Shahri, Fatemeh

    2007-07-01

    We have utilized the concept of valon model to calculate the spin structure functions of proton, neutron, and deuteron. The valon structure itself is universal and arises from the perturbative dressing of the valence quark in QCD. Our results agree rather well with all of the relevant experimental data on g1p,n,d and gA/gV, and suggests that the sea quark contribution to the spin of proton is consistent with zero. It also reveals that while the total quark contribution to the spin of a valon, ΔΣvalon, is almost constant at Q2 >= 1 the gluon contribution grows with the increase of Q2 and hence requiring a sizable negative orbital angular momentum component Lz. This component along with the singlet and non-singlet parts are calculated in the Next-to-Leading order in QCD . We speculate that gluon contribution to the spin content of the proton is about 60% for all Q2 values. Finally, we show that the size of gluon polarization and hence, Lz, is sensitive to the initial scale Q02.

  12. Polarized structure of nucleon in the valon representation

    International Nuclear Information System (INIS)

    We have utilized the concept of valon model to calculate the spin structure functions of proton, neutron, and deuteron. The valon structure itself is universal and arises from the perturbative dressing of the valence quark in QCD. Our results agree rather well with all of the relevant experimental data on g1p,n,d and gA/gV, and suggests that the sea quark contribution to the spin of proton is consistent with zero. It also reveals that while the total quark contribution to the spin of a valon, ΔΣvalon, is almost constant at Q2 ≥ 1 the gluon contribution grows with the increase of Q2 and hence requiring a sizable negative orbital angular momentum component Lz. This component along with the singlet and non-singlet parts are calculated in the Next-to-Leading order in QCD . We speculate that gluon contribution to the spin content of the proton is about 60% for all Q2 values. Finally, we show that the size of gluon polarization and hence, Lz, is sensitive to the initial scale Q02

  13. The Polarized Structure Function $g_{2} A Lattice Study Revisited

    CERN Document Server

    Göckeler, M; Kürzinger, W; Oelrich, H; Rakow, P; Schierholz, G

    1999-01-01

    A recent lattice calculation of the spin-dependent structure function g_2 is revisited. It has been recognized that the twist-three operator, which gives rise to d_2, mixes non-perturbatively with operators of lower dimensions under renormalization. This changes the results substantially.

  14. Tensor-polarized structure functions: Tensor structure of deuteron in 2020's

    Science.gov (United States)

    Kumano, S.

    2014-10-01

    We explain spin structure for a spin-one hadron, in which there are new structure functions, in addition to the ones (F1, F2, g1, g2) which exist for the spin-1/2 nucleon, associated with its tensor structure. The new structure functions are b1, b2, b3, and b4 in deep inelastic scattering of a charged-lepton from a spin-one hadron such as the deuteron. Among them, twist- two functions are related by the Callan-Gross type relation b2 = 2xb1 in the Bjorken scaling limit. First, these new structure functions are introduced, and useful formulae are derived for projection operators of b1-4 from a hadron tensor Wμν. Second, a sum rule is explained for b1, and possible tensor-polarized distributions are discussed by using HERMES data in order to propose future experimental measurements and to compare them with theoretical models. A proposal was approved to measure b1 at the Thomas Jefferson National Accelerator Facility (JLab), so that much progress is expected for b1 in the near future. Third, formalisms of polarized proton-deuteron Drell-Yan processes are explained for probing especially tensor- polarized antiquark distributions, which were suggested by the HERMES data. The studies of the tensor-polarized structure functions will open a new era in 2020's for tensor-structure studies in terms of quark and gluon degrees of freedom, which are very different from ordinary descriptions in terms of nucleons and mesons.

  15. Changes of the ash structure

    Science.gov (United States)

    Peer, Václav; Friedel, Pavel; Janša, Jan

    2016-06-01

    The aim of the article is to appraisal of the changes in the structure of the ash due to the addition of compounds capable of the eutectics composition change. For the transformation were used limestone and dolomite dosed in amounts of 2, 5 and 10 wt.% with pellets of spruce wood, willow wood and refused derived fuel. Combustion temperatures of the mixtures were adjusted according to the temperatures reached during the using of fuels in power plants, i.e. 900, 1000, 1100 and 1200 °C.

  16. Growth, Employment and Structural Change

    DEFF Research Database (Denmark)

    Aggarwal, Aradhna

    2016-01-01

    This paper studies the decomposition of GSDP growth per capita in Punjab via-a-vis 15 other states in India during 1993–94 and 2011–12 in terms of employment and productivity growth. Specifically, it focuses on the role of employment growth and structural change in employment on economic growth....... It reviews the theoretical rationale, presents the growth patterns in GSDP and employment, and estimates the employment-productivity components of GSDP growth per capita using the Shapley decomposition analysis. The results show that Punjab has slipped in terms of GSDP per capita over this period...... to be positive. Finally, while the state was outpaced by other states in terms of growth rate in GSDP per capita and even employment, structural change in the economy has been a positive feature of growth in the state....

  17. Two-Element PIFA Array Structure for Polarization Diversity in UMTS Mobile Phones

    Directory of Open Access Journals (Sweden)

    P. Hamouz

    2009-12-01

    Full Text Available In this paper, we demonstrate the possibility to strongly modify the radiated fields of a UMTS handset by using a phased two-element PIFA array. The structure is composed of a 100x40 mm2 metallic ground plane acting as the Printed Circuit Board (PCB of the mobile phone. Two UMTS PIFAs are located at the top edge of this PCB. They are fed by a double Quasi-Lumped Coupler able to provide a 360 phase difference between its two outputs. By properly choosing the DC bias of the double QuasiLumped Coupler, we can set a specific phase difference between the two PIFAs. In this way the two-element array is able to radiate different electromagnetic fields. Simulated and measured radiation patterns in the two main planes of the chassis are presented for different phase differences. It is especially revealed that the novel twoantenna structure is able to radiate vertically-polarized electric fields in the azimuthal plane of the phone and horizontally-polarized electric fields in the same plane when changing the phase shift between the antennas from 0 to 180. Potential applications are polarization-diversity techniques and Specific Absorption Rate reduction for handsets.

  18. Spin polarization of two-dimensional electronic gas decoupled from structural asymmetry environment

    Science.gov (United States)

    Pieczyrak, B.; Szary, M.; Jurczyszyn, L.; Radny, M. W.

    2016-05-01

    It is shown, using density functional theory, that a 2D electron gas induced in a monolayer of Pb or Tl adatoms on the Si (111 )-1 ×1 surface is insensitive to the structural asymmetry of the system and its spin polarization is governed by the interaction between the adlayer and the substrate. It is demonstrated that this interaction changes the in-plane inversion symmetry of the charge distribution within the monolayer and can either suppress [Pb/Si(111)] or enhance [Tl/Si(111)] the adatom intra-atomic spin-orbit effect on a Rashba-Bychkov-type spin splitting.

  19. Intensity-dependent change in polarization state of light in normal incidence on an isotropic nonlinear Kerr medium

    Indian Academy of Sciences (India)

    Hari Prakash; Devendra K Singh

    2010-03-01

    It is shown that all optical polarization states of light except plane and circular polarization states undergo an intensity-dependent change in normal incidence of light in an isotropic nonlinear Kerr medium. This effect should be detectable and we propose an experiment for detecting nonlinear susceptibility involved in that part of nonlinear polarization, which depends on the polarization state of light also.

  20. Atomic and electronic structure of polar Fe2O3(0001)/MgO(111) interfaces

    Science.gov (United States)

    Pande, K.; Gajdardziska-Josifovska, M.; Weinert, M.

    2012-07-01

    We present a first-principles investigation of the structural, electronic, and magnetic properties of ultrathin Fe2O3(0001) films on a polar MgO(111) substrate. The results imply that the heterointerface is atomically abrupt with oxidelike stacking for film thicknesses between ˜1.5 and 8.5 Å. The Fe-Fe bilayer (nominal separation of 0.59 Å in Fe2O3) at the interface collapses into an “Fe2” monolayer. Both electronic polarization and structural relaxations effectively screen the dipole field of the polar interface system. The structural relaxations—consisting of interpenetration, separation, and merger of Fe and oxygen planes—are particularly drastic in the three- and four-bilayers-thick films, giving rise to barrierless movement of oxygen towards the surface and the formation of an “Fe2|FeO3” layer structure not seen in hematite. Comparisons to calculations of unsupported polar Fe2O3(0001) slabs demonstrate that these unusual changes in stacking sequence and electronic structure are associated with the polar nature of this oxide heterointerface.

  1. Grain size disposed structural, optical and polarization tuning in ZnO

    Science.gov (United States)

    Para, Touseef Ahmad; Reshi, Hilal Ahmad; Pillai, Shreeja; Shelke, Vilas

    2016-08-01

    Structural, optical and polarization properties were investigated in different batches of ZnO synthesized by sol-gel method at varying sintering temperature. The structural visualization and charge scattering density analysis on the basis of X-ray diffraction data indicate polarized nature of sample. The structure- and polarization-related parameters were determined from Raman and Fourier transformed infrared spectroscopy data. Urbach energies and band gap were calculated using UV-visible spectroscopy. We observed increase in polarization, decrease in optical activity and band gap with increasing grain size without any increase in defects. Distortion in ZnO tetrahedra resulted in nonlinear optical behaviour above band edges. The results show direct correlation between grain size, band gap, optical behaviour and polarization. Low band gap and high polarization in ZnO can be employed for the production of opto-electronic devices.

  2. Empiricism, Structuralism and Scientific Change

    Directory of Open Access Journals (Sweden)

    Susana Lucero

    2008-06-01

    Full Text Available In the last decades there was a structural turn in the classic debate between scientific realists and antirealists with empiricist orientation. Two main arguments support the realist conception: the ‘No Miracle Argument’ and the thesis of continuity. The thesis of continuity states that some parts of a theory are retained when a scientific change takes place. In a current famous article, J. Worrall (1989 defends the continuity argument by stating that what is preserved in the succession of two empirically successful theories are the relations among the postulated entities and not the nature of the relata (structural or syntactical realism. Based on this perspective, van Fraassen introduces his position named Empiricist Structuralism, which claims that only the structures of phenomena are retained. This conception tries to explain the success of science and at the same time defend the continuity of structures. I will demonstrate in this paper that the accomplishment of the two mentioned requirements imply a capitulation in favor of realistic intuitions.

  3. Finite element analysis of the dynamic behavior of radially polarized Functionally Graded Piezoelectric (FGP) structures

    Science.gov (United States)

    Kandasamy, Ramkumar; Cui, Fangsen

    2016-04-01

    In the traditional layered piezoelectric structures, high stress concentrations could cause the structural failure in interlayer surfaces due to repeated strain reversals. To overcome the performance limitations of these structures, the concept of Functionally Graded Materials (FGMs) has been introduced to improve the lifetime, integrity, and reliability of these structures. In this paper, the free and forced vibration of radially polarized Functionally Graded Piezoelectric (FGP) cylinders under different sets of loading are studied. Material properties such as piezoelectric, elastic and permittivity are assumed to change along its thickness, based on a specific gradation function. Four-parameter power law distribution is used to grade the volume fraction of the constituents comprising of PZT-5A and PZT-5H. Material property is assumed to be temperature dependent for a few numerical studies. The present modeling approach is validated by comparing the free and forced vibration of radially polarized Functionally Graded Piezoelectric (FGP) cylinders with those reported in the literature. The effects of material composition, loading and boundary conditions on the dynamic behavior of FGP cylinder are described. Since the modeling of functionally graded piezoelectric systems is challenging, the present study can help in the design and analysis of FGP cylinders.

  4. CARS polarized microscopy of three-dimensional director structures in liquid crystals

    CERN Document Server

    Kachynski, A V; Prasad, P N; Smalyukh, I I

    2007-01-01

    We demonstrate three-dimensional vibrational imaging of director structures in liquid crystals using coherent anti-Stokes Raman scattering (CARS) polarized microscopy. Spatial mapping of the structures is based on sensitivity of a polarized CARS signal to orientation of anisotropic molecules in liquid crystals. As an example, we study structures in a smectic material and demonstrate that single-scan CARS and two-photon fluorescence images of molecular orientation patterns are consistent with each other and with the structure model.

  5. NHS System Reform: Structural Changes

    Directory of Open Access Journals (Sweden)

    H Ravaghi

    2005-10-01

    Full Text Available The National Health Service (NHS was established in 1948 to provide equitable healthcare for all citizens. Over the years the NHS has gone under different reforms and changes. In 2002 the NHS launched one of its biggest changes in structure since its commencement in 1948. The scale of these changes are greater than those established following the white paper “Working for Patients” in 1989 (Conservative Government that indicated the introduction of the internal market (focus on efficiency. This review therefore proposes to give a brief summarize of the structural changes and current structure of the NHS in the England. The NHS plan was published in July 2000 (Labour Government and outlined a 10 year plan of investment in the NHS. This delineates a vision for a service planned around the patients and more responsive to patients’ needs. The Government emphasizes on the empowering of staff at all levels as a way to achieve this vision. "Shifting the Balance of Power" is part of the Government’s plans for implementation of the NHS Plan and has directed to the establishment of new structures. The main feature of change has been giving locally based Primary Care Trusts the role of running the NHS and, with the local authorities, improving health in their areas. The PCTs are receiving 75% of the NHS budget to act as primary services provider, commissioner (service purchaser, network developer and controller. In addition, all former Health Authorities have been abolished and new Strategic Health Authorities (SHA have been created to serve larger areas and with a more strategic role. The SHAs are responsible for developing strategic frameworks for the local health service; performance of the local health service; and building capacity in the local health service. The Department of Health is also refocusing to reflect these changes, including the abolition of its Regional Offices and relegating some of its operational responsibilities to SHAs and

  6. Structural study of magnesium phtalocyanin and tetraphenylporphyrin - polar molecule complexes

    International Nuclear Information System (INIS)

    As part of the structural study of biological magnesium compounds we examined the interaction of magnesium tetraphenyl porphyrin and phtalocyanin (TPPMg and PcMg) with nitrogenated polar molecules (pyridine and quinoline) as follows: - the infrared spectra of TPPMg and PcMg without external ligands were interpreted in the 4000 to 150 cm-1 region. By comparison with the IR spectra of TPPH2, PcH2, PcZn and PcFe II, and especially using the isotopic substitution 24Mg/26Mg; the absorption bands corresponding to the intramolecular magnesium-nitrogen vibrations were revealed. - the IR spectra of TPPMg, PcMg, PcFeII and PcZn complexes with pyridine and quinoline were interpreted next. The absorption bands of the intermolecular metal-nitrogen vibrations were identified. - these complexes were then studied quantitatively in the solid state by thermogravimetry: TPPMg pyridine was examined in benzene solution by absorption spectrometry in the visible and in carbon sulphide solution by infrared spectrometry. The equilibrium constants were determined for these systems at various temperatures and their thermodynamic constants (ΔH0 and ΔS0) of formation evaluated. From studies it was concluded that the stoichiometry of the complexes with pyridine (or quinoline) is 1:1 or 1:2 (one tetrapyrolic magnesium molecule for 1 or 2 pyridines); in the 1:1 complex the pyridine nitrogen interacts strongly and directly with the porphyrin magnesium (electron donor-acceptor system); the same applies to the second by weak interactions between the π systems of pyridine and of the tetrapyrolic ring, the tetrapyrolic molecule and pyridine planes probably being parallel. The model accounts for the fact that in these systems there is only one isosbestic point, whereas two are expected and observed for a 1:2 complex of the iron porphyrin-pyridine type. (author)

  7. The Polar Stratosphere in a Changing Climate (POLSTRACC)

    Science.gov (United States)

    Oelhaf, Hermann; Sinnhuber, Björn-Martin; Woiwode, Wolfgang; Rapp, Markus; Dörnbrack, Andreas; Engel, Andreas; Boenisch, Harald

    2015-04-01

    The POLSTRACC mission aims at providing new scientific knowledge on the Arctic lowermost stratosphere (LMS) and upper troposphere under the present load of halogens and state of climate variables. POLSTRACC is the only HALO (High Altitude and LOng Range Research Aircraft, German Research Community) mission dedicated to study the UTLS at high latitudes several years after the last intensive Arctic campaigns. The scientific scope of POLSTRACC will be broadened by its combination with the SALSA (Seasonality of Air mass transport and origin in the Lowermost Stratosphere using the HALO Aircraft) and GW-LCYCLE (Gravity Wave Life Cycle Experiment, a BMBF/ROMIC project) missions, which address complementary scientific goals sharing the same HALO payload. POLSTRACC, SALSA and GW-LCYCLE will offer the unique opportunity to study the bottom of the polar vortex and the high-latitude UTLS along with their impact on lower latitudes throughout an entire winter/spring cycle. The POLSTRACC consortium includes national (KIT, Forschungszentrum Jülich, DLR, Max Planck Institute for Chemistry, Universities of Frankfurt, Heidelberg, Mainz and Wuppertal) and international partners (e.g. NASA). The payload for the combined POLSTRACC, SALSA and GW-LCYCLE campaigns comprises an innovative combination of remote sensing techniques providing 2- and 3-D distributions of temperature and a large number of substances, and precise in-situ instruments measuring T, O3, H2O, tracers of different lifetimes and chemically active species at the aircraft level with high time-resolution. Drop sondes will add information about temperature, humidity and wind in the atmosphere underneath the aircraft. The field campaign will be divided into three phases for addressing (i) the early polar vortex and its wide-scale vicinity in December 2015 (from Oberpfaffenhofen, Germany), (ii) the mid-winter vortex from January to March 2016 (from Kiruna, Sweden), and (iii) the late dissipating vortex and its wide

  8. Time for a Change; Spirit's View on Sol 1843 (Polar)

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Spirit used its navigation camera to take the images that have been combined into this full-circle view of the rover's surroundings during the 1,843rd Martian day, or sol, of Spirit's surface mission (March 10, 2009). South is in the middle. North is at both ends. This view is presented as a polar projection with geometric seam correction. North is at the top. The rover had driven 36 centimeters downhill earlier on Sol 1854, but had not been able to get free of ruts in soft material that had become an obstacle to getting around the northeastern corner of the low plateau called 'Home Plate.' The Sol 1854 drive, following two others in the preceding four sols that also achieved little progress in the soft ground, prompted the rover team to switch to a plan of getting around Home Plate counterclockwise, instead of clockwise. The drive direction in subsequent sols was westward past the northern edge of Home Plate.

  9. Probing Membrane Protein Structure Using Water Polarization Transfer Solid-State NMR

    OpenAIRE

    Williams, Jonathan K.; Hong, Mei

    2014-01-01

    Water plays an essential role in the structure and function of proteins, lipid membranes and other biological macromolecules. Solid-state NMR heteronuclear-detected 1H polarization transfer from water to biomolecules is a versatile approach for studying water-protein, water-membrane, and water-carbohydrate interactions in biology. We review radiofrequency pulse sequences for measuring water polarization transfer to biomolecules, the mechanisms of polarization transfer, and the application of ...

  10. Phase space structures and ionization dynamics of hydrogen atom in elliptically polarized microwaves

    OpenAIRE

    Shchekinova, Elena; Chandre, Cristel; Uzer, Turgay

    2006-01-01

    International audience The multiphoton ionization of hydrogen atoms in a strong elliptically polarized microwave field exhibits complex features that are not observed for ionization in circular and linear polarized fields. Experimental data reveal high sensitivity of ionization dynamics to the small changes of the field polarization. The multidimensional nature of the problem makes widely used diagnostics of dynamics, such as Poincaré surfaces of section, impractical. We analyze the phase ...

  11. International conference on the role of the polar regions in global change: Proceedings. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Weller, G.; Wilson, C.L.; Severin, B.A.B. [eds.

    1991-12-01

    The International Conference on the Role of the Polar Regions in Global Change took place on the campus of the University of Alaska Fairbanks on June 11--15, 1990. The goal of the conference was to define and summarize the state of knowledge on the role of the polar regions in global change, and to identify gaps in knowledge. To this purpose experts in a wide variety of relevant disciplines were invited to present papers and hold panel discussions. While there are numerous conferences on global change, this conference dealt specifically with the polar regions which occupy key positions in the global system. These two volumes of conference proceedings include papers on (1) detection and monitoring of change; (2) climate variability and climate forcing; (3) ocean, sea ice, and atmosphere interactions and processes; and (4) effects on biota and biological feedbacks; (5) ice sheet, glacier and permafrost responses and feedbacks, (6) paleoenvironmental studies; and, (7) aerosol and trace gases.

  12. International conference on the role of the polar regions in global change: Proceedings

    International Nuclear Information System (INIS)

    The International Conference on the Role of the Polar Regions in Global Change took place on the campus of the University of Alaska Fairbanks on June 11--15, 1990. The goal of the conference was to define and summarize the state of knowledge on the role of the polar regions in global change, and to identify gaps in knowledge. To this purpose experts in a wide variety of relevant disciplines were invited to present papers and hold panel discussions. While there are numerous conferences on global change, this conference dealt specifically with polar regions which occupy key positions in the global system. These two volumes of conference proceedings include papers on (1) detection and monitoring of change; (2) climate variability and climate forcing; (3) ocean, sea ice, and atmosphere interactions and processes; (4) effects on biota and biological feedbacks; (5) ice sheet, glacier and permafrost responses and feedbacks; (6) paleoenvironmental studies; and, (7) aerosols and trace gases

  13. International conference on the role of the polar regions in global change: Proceedings. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Weller, G.; Wilson, C.L.; Severin, B.A.B. [eds.

    1991-12-01

    The International Conference on the Role of the Polar Regions in Global Change took place on the campus of the University of Alaska Fairbanks on June 11--15, 1990. The goal of the conference was to define and summarize the state of knowledge on the role of the polar regions in global change, and to identify gaps in knowledge. To this purpose experts in a wide variety of relevant disciplines were invited to present papers and hold panel discussions. While there are numerous conferences on global change, this conference dealt specifically with polar regions which occupy key positions in the global system. These two volumes of conference proceedings include papers on (1) detection and monitoring of change; (2) climate variability and climate forcing; (3) ocean, sea ice, and atmosphere interactions and processes; (4) effects on biota and biological feedbacks; (5) ice sheet, glacier and permafrost responses and feedbacks; (6) paleoenvironmental studies; and, (7) aerosols and trace gases.

  14. International conference on the role of the polar regions in global change: Proceedings

    International Nuclear Information System (INIS)

    The International Conference on the Role of the Polar Regions in Global Change took place on the campus of the University of Alaska Fairbanks on June 11--15, 1990. The goal of the conference was to define and summarize the state of knowledge on the role of the polar regions in global change, and to identify gaps in knowledge. To this purpose experts in a wide variety of relevant disciplines were invited to present papers and hold panel discussions. While there are numerous conferences on global change, this conference dealt specifically with the polar regions which occupy key positions in the global system. These two volumes of conference proceedings include papers on (1) detection and monitoring of change; (2) climate variability and climate forcing; (3) ocean, sea ice, and atmosphere interactions and processes; and (4) effects on biota and biological feedbacks; (5) ice sheet, glacier and permafrost responses and feedbacks, (6) paleoenvironmental studies; and, (7) aerosol and trace gases

  15. Novel polar dielectrics with the tetragonal tungsten bronze structure

    OpenAIRE

    Andrei ROTARU

    2013-01-01

    There is great interest in the development of new polar dielectric ceramics and multiferroic materials with new and improved properties. A family of tetragonal tungsten bronze (TTB) relaxors of composition Ba₆M³⁺Nb₉O₃₀ (M³⁺ = Ga³⁺, Sc³⁺ and In³⁺, and also their solid solutions) were studied in an attempt to understand their dielectric properties to enable design of novel polar TTB materials. A combination of electrical measurements (dielectric and impedance spectroscopy) and powder diffr...

  16. Spatial-frequency structure and polarization phasometry of coherent images of biological polycrystalline networks

    Science.gov (United States)

    Angelsky, Pavlo O.; Trifonyuk, L.

    2013-06-01

    Our research is aimed at designing an experimental method of Fourier laser polarization phasometry of the layers of human effusion for an express determining the potentialities of diagnostics of pathological changes in mammary gland basing on polarization analysis of laser images of the biopsy of the uterine wall tissue in order to differentiate benign (fibromioma) and malignant (adenocarcinoma).

  17. Generation of arbitrary radially polarized array beams by modulating the correlation structure

    CERN Document Server

    Zhu, Shijun; Li, Zhenhua

    2016-01-01

    We demonstrate a convenient approach for simultaneously manipulating the amplitude and polarization of light beams by means of the modulation of the correlation structure. As an illustration, we constructed a periodic correlation structure that can generate an arbitrary radially polarized array (RPA) beam of a radial or rectangular symmetry array in the focal plane from a radially polarized (RP) beam. The physical realizability conditions for such source and the far-field beam condition are derived. It is illustrated that the beamlet shape and the state of polarization (SOP) can be effectively controlled by the initial correlation structure and the coherence width. Furthermore, by designing the source correlation structure, a tunable OK-shaped RPA beam and an optical cage are demonstrated, which can find widespread applications in non-destructive manipulation of particles and living biological cells. The arbitrariness in the design of correlation structure prompted us to find more convenient approaches for co...

  18. Surface chemistry and electronic structure of nonpolar and polar GaN films

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Monu; Krishna, T.C. Shibin; Aggarwal, Neha; Gupta, Govind, E-mail: govind@nplindia.org

    2015-08-01

    Highlights: • Surface chemistry and electronic structure of polar and nonpolar GaN is reported. • Influence of polarization on electron affinity of p & np GaN films is investigated. • Correlation between surface morphology and polarity has been deduced. - Abstract: Photoemission and microscopic analysis of nonpolar (a-GaN/r-Sapphire) and polar (c-GaN/c-Sapphire) epitaxial gallium nitride (GaN) films grown via RF-Molecular Beam Epitaxy is reported. The effect of polarization on surface properties like surface states, electronic structure, chemical bonding and morphology has been investigated and correlated. It was observed that polarization lead to shifts in core level (CL) as well as valence band (VB) spectra. Angle dependent X-ray Photoelectron Spectroscopic analysis revealed higher surface oxide in polar GaN film compared to nonpolar GaN film. On varying the take off angle (TOA) from 0° to 60°, the Ga−O/Ga−N ratio varied from 0.11–0.23 for nonpolar and 0.17–0.36 for polar GaN film. The nonpolar film exhibited N-face polarity while Ga-face polarity was perceived in polar GaN film due to the inherent polarization effect. Polarization charge compensated surface states were observed on the polar GaN film and resulted in downward band bending. Ultraviolet photoelectron spectroscopic measurements revealed electron affinity and ionization energy of 3.4 ± 0.1 eV and 6.8 ± 0.1 eV for nonpolar GaN film and 3.8 ± 0.1 eV and 7.2 ± 0.1 eV for polar GaN film respectively. Field Emission Scanning Electron Microscopy measurements divulged smooth morphology with pits on polar GaN film. The nonpolar film on the other hand showed pyramidal structures having facets all over the surface.

  19. Multiple scattering of polarized light in disordered media exhibiting short-range structural correlations

    CERN Document Server

    Vynck, Kevin; Carminati, Rémi

    2016-01-01

    We develop a model based on a multiple scattering theory to describe the diffusion of polarized light in disordered media exhibiting short-range structural correlations. Starting from exact expressions of the average field and the field spatial correlation function, we derive a radiative transfer equation for the polarization-resolved specific intensity that is valid for weak disorder and we solve it analytically in the diffusion limit. A decomposition of the specific intensity in terms of polarization eigenmodes reveals how structural correlations, represented via the standard anisotropic scattering parameter $g$, affect the diffusion of polarized light. More specifically, we find that propagation through each polarization eigenchannel is described by its own transport mean free path that depends on $g$ in a specific and non-trivial way.

  20. MARKET INTEGRATION: CASE STUDIES OF STRUCTURAL CHANGE

    OpenAIRE

    Franken, Jason R.V.; Parcell, Joseph L.

    2003-01-01

    The grain/oilseed industry is undergoing considerable structural change in the form of mergers and the addition of new processing facilities to add value beyond commodity grade. The rapid structural changes in this industry call into question the relevance of previous research conducted in these areas. Focusing on two structural change events in northeast Missouri as case studies provides an incisive glimpse at the larger impact of structural change on the grain/oilseed industry. This study a...

  1. Climate change and the increasing impact of polar bears on bird populations

    Directory of Open Access Journals (Sweden)

    Jouke eProp

    2015-03-01

    Full Text Available The Arctic is becoming warmer at a high rate, and contractions in the extent of sea ice are currently changing the habitats of marine top-predators dependent on ice. Polar bears (Ursus maritimus depend on sea ice for hunting seals. For these top-predators, longer ice-free seasons are hypothesized to force the bears to hunt for alternative terrestrial food, such as eggs from colonial breeding birds. We analyzed time-series of polar bear observations at four locations on Spitsbergen (Svalbard and one in east Greenland. Summer occurrence of polar bears, measured as the probability of encountering bears and the number of days with bear presence, has increased significantly from the 1970/80s to the present. The shifts in polar bear occurrence coincided with trends for shorter sea ice seasons and less sea ice during the spring in the study area. This resulted in a strong inverse relationship between the probability of bear encounters on land and the length of the sea ice season. Within ten years after their first appearance on land, polar bears had advanced their arrival dates by almost 30 days. Direct observations of nest predation showed that polar bears may severely affect reproductive success of the barnacle goose (Branta leucopsis, common eider (Somateria mollissima and glaucous gull (Larus hyperboreus. Nest predation was strongest in years when the polar bears arrived well before hatch, with more than 90% of all nests being predated. The results are similar to findings from Canada, and large-scale processes, such as climate and subsequent habitat changes, are pinpointed as the most likely drivers in various parts of the Arctic. We suggest that the increasing, earlier appearance of bears on land in summer reflects behavioral adaptations by a small segment of the population to cope with a reduced hunting range on sea ice. This exemplifies how behavioral adaptations may contribute to the cascading effects of climate change.

  2. Changes in aerobic performance, body composition, and physical activity in polar explorers during a year-long stay at the polar station in the Arctic

    Science.gov (United States)

    Maciejczyk, Marcin; Araźny, Andrzej; Opyrchał, Marta

    2016-09-01

    The aim of this study was to evaluate changes in physical activity, aerobic performance, and body composition in polar explorers during a 1-year stay at the polar station. The study group consisted of 10 people, including 8 men and 2 women. Aerobic performance (maximal oxygen uptake), physical activity, body mass, and composition were evaluated for the polar explores of the Polish Polar Station prior to departure, and then during their stay at the station for a period of 1 year. The measurements were performed every 3 months. Compared to the measurements taken before going to the polar station, aerobic performance significantly (p = 0.02) increased in the first 3 months of residing at the polar station and then remained relatively stable for the following duration of the stay. In the first 3 months of the stay, we also observed the highest level of physical activity in participants. In the polar explorers, no significant (p > 0.05) body fatness changes were noted. Nonetheless, lean body mass, body mass, and BMI significantly increased compared to the measurements taken before departure to the polar station. The greatest changes in aerobic performance, physical activity, and body composition were observed during the first 3 months after arrival to the Arctic and then, despite changing biometeorological conditions, they remained stable for the next months of the stay. We recommend the introduction of a physical preparation program before departing to the polar station to improve explorers' physical fitness, so that they can meet the physical challenges they are faced with immediately after arrival to the polar station.

  3. Landward and eastward shift of Alaskan polar bear denning associated with recent sea ice changes

    Science.gov (United States)

    Fischbach, A.S.; Amstrup, Steven C.; Douglas, D.C.

    2007-01-01

    Polar bears (Ursus maritimus) in the northern Alaska region den in coastal areas and on offshore drifting ice. We evaluated changes in the distribution of polar bear maternal dens between 1985 and 2005, using satellite telemetry. We determined the distribution of maternal dens occupied by 89 satellite collared female polar bears between 137°W and 167°W longitude. The proportion of dens on pack ice declined from 62% in 1985–1994 to 37% in 1998–2004 (P = 0.044) and among pack ice dens fewer occurred in the western Beaufort Sea after 1998. We evaluated whether hunting, attraction to bowhead whale remains, or changes in sea ice could explain changes in den distribution. We concluded that denning distribution changed in response to reductions in stable old ice, increases in unconsolidated ice, and lengthening of the melt season. In consort, these changes have likely reduced the availability and quality of pack ice denning habitat. Further declines in sea ice availability are predicted. Therefore, we expect the proportion of polar bears denning in coastal areas will continue to increase, until such time as the autumn ice retreats far enough from shore that it precludes offshore pregnant females from reaching the Alaska coast in advance of denning.

  4. Cassini Returns to Saturn's Poles: Seasonal Change in the Polar Vortices

    Science.gov (United States)

    Fletcher, Leigh N.; Orton, G. S.; Irwin, P. G. J.; Sinclair, J. A.; Hesman, B. E.; Hurley, J.; Bjoraker, G. L.; Simon-Miller, A. A.

    2013-01-01

    High inclination orbits during Cassini's solstice mission (2012) are providing us with our first observations of Saturn's high latitudes since the prime mission (2007). Since that time, the northern spring pole has emerged into sunlight and the southern autumn pole has disappeared into winter darkness, allowing us to study the seasonal changes occurring within the polar vortices in response to these dramatic insolation changes. Observations from the Cassini Composite Infrared Spectrometer] have revealed (i) the continued presence of small, cyclonic polar hotspots at both spring and autumn poles; and (ii) the emergence of an infrared-bright polar vortex at the north pole, consistent with the historical record of Saturn observations from the 1980s (previous northern spring).

  5. Chromospheric and Coronal Structure of Polar Plumes. 1; Magnetic Structure and Radiative Energy Balance

    Science.gov (United States)

    Allen, Maxwell J.; Oluseyi, Hakeem M.; Walker, Arthur B. C.; Hoover, Richard B.; Barbee, Troy W., Jr.

    1997-01-01

    The Multi-Spectral Solar Telescope Array (MSSTA), a rocket-borne solar observatory, was successfully launched from White Sands Missile Range, New Mexico, on May 13, 1991 at 19:05 UT. The telescope systems onboard the MSSTA obtained several full disk solar images in narrow bandpasses centered around strong soft X-ray, EUV, and FUV emission lines. Each telescope was designed to be sensitive to the coronal plasmas at a particular temperature, for seven temperatures ranging from 20,000 K to 4,000,000 K. We report here on the images obtained during the initial flight of the MSSTA, and on the chromospheric and coronal structure of polar plumes observed over both poles of the Sun. We have also co-aligned the MSSTA images with Kitt Peak magnetograms taken on the same day. We are able to positively identify the magnetic structures underlying the polar plumes we analyze as unipolar. We discuss the plume observations and present a radiative energy balance model derived from them.

  6. Anisotropic lattice response induced by a linearly-polarized femtosecond optical pulse excitation in interfacial phase change memory material

    OpenAIRE

    Kotaro Makino; Yuta Saito; Paul Fons; Kolobov, Alexander V.; Takashi Nakano; Junji Tominaga; Muneaki Hase

    2016-01-01

    Optical excitation of matter with linearly-polarized femtosecond pulses creates a transient non-equilibrium lattice displacement along a certain direction. Here, the pump and probe pulse polarization dependence of the photo-induced ultrafast lattice dynamics in (GeTe)2/(Sb2Te3)4 interfacial phase change memory material is investigated under obliquely incident conditions. Drastic pump polarization dependence of the coherent phonon amplitude is observed when the probe polarization angle is para...

  7. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions

    Science.gov (United States)

    Rode, Karyn D.; Wilson, Ryan R.; Regehr, Eric V.; St. Martin, Michelle; Douglas, David C.; Olson, Jay

    2015-01-01

    Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986–1995 and 2008–2013) when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia), highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions. PMID:26580809

  8. Increased land use by Chukchi Sea polar bears in relation to changing sea ice conditions

    Science.gov (United States)

    Rode, Karyn D.; Wilson, Ryan R.; Regehr, Eric V.; St. Martin, Michelle; Douglas, David; Olson, Jay

    2015-01-01

    Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986–1995 and 2008–2013) when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia), highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions.

  9. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions.

    Directory of Open Access Journals (Sweden)

    Karyn D Rode

    Full Text Available Recent observations suggest that polar bears (Ursus maritimus are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986-1995 and 2008-2013 when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia, highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions.

  10. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions.

    Science.gov (United States)

    Rode, Karyn D; Wilson, Ryan R; Regehr, Eric V; St Martin, Michelle; Douglas, David C; Olson, Jay

    2015-01-01

    Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986-1995 and 2008-2013) when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia), highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions. PMID:26580809

  11. Effects of Si-doping on structural, electrical, and optical properties of polar and non-polar AlGaN epi-layers

    Science.gov (United States)

    Yang, Hongquan; Zhang, Xiong; Wang, Shuchang; Wang, Yi; Luan, Huakai; Dai, Qian; Wu, Zili; Zhao, Jianguo; Cui, Yiping

    2016-08-01

    The polar (0001)-oriented c-plane and non-polar (11 2 bar 0) -oriented a-plane wurtzite AlGaN epi-layers were successfully grown on polar (0001)-oriented c-plane and semi-polar (1 1 bar 02) -oriented r-plane sapphire substrates, respectively with various Si-doping levels in a low pressure metal organic chemical vapor deposition (MOCVD) system. The morphological, structural, electrical, and optical properties of the polar and non-polar AlGaN epi-layers were studied with scanning electron microscopy (SEM), X-ray diffraction (XRD), Hall effect, and Raman spectroscopy. The characterization results show that Si dopants incorporated into the polar and non-polar AlGaN films induced a relaxation of compressive residual strain and a generation of biaxial tensile strain on the surface in consequence of the dislocation climbing. In particular, it was found that the Si-induced compressive strain relaxation in the non-polar AlGaN samples can be promoted by the structural anisotropy as compared with the polar counterparts. The gradually increased relaxation of compressive residual strain in both polar and non-polar AlGaN samples with increasing Si-doping level was attributed to the Si-induced enhancement in the opportunity for the dislocations to interact and annihilate. This implies that the crystal quality for both polar and non-polar AlGaN epi-layers can be remarkably improved by Si-doping.

  12. Variation of moduli spaces and Donaldson invariants under change of polarization

    CERN Document Server

    Ellingsrud, G; Ellingsrud, Geir; G\\"ottsche, Lothar

    1994-01-01

    The paper determines the change of moduli spaces of rank $2$ sheaves on surfaces with $p_g=0$ under change of polarization and the corresponding change of the Donaldson invariants. In this revised version we have made some minor stylistic changes in the previous text. In addition we have added a final chapter of about 20 pages (announced in the previous version), in which the six lowest order terms (three of them non-zero) of the change are computed explicitely using computations in the cohomology of Hilbert schemes of points.

  13. Unusual polar filament structure in two microsporidia from water reservoirs with radionuclide and organic pollution

    International Nuclear Information System (INIS)

    Two species of microsporidia with the unusual polar filament structure were found in Cricotopus silvestris and Microtendipes pedellus larvae which were collected near the zone of influence of the Chernobyl atomic power station (Ukraine) and from a high polluted pond in the Mazurian region of Poland. The first microsporidium had separate unikaryotic spores and was assigned to the family Unikaryonidae Sprague. The diameter of the middle coil of the triple-coiled polar filament of this microsporidium was larger than its two other coils. The observed polar filament was thus neither of isofilar nor of the classical anisofilar type. The second polysporoblastic microsporidium has unikaryotic spores and an uncoiled polar filament and was placed in the family Thelohaniidae Hazard and Oldacre. The rare single macrospores of this microsporidium have a double set of the polar filament complex. The relationship between ultrastructural features of microsporidian spores and water pollution is discussed. (author)

  14. Simulated In Situ Measurements and Structural Analysis of Reconnection-Driven Solar Polar Jets

    Science.gov (United States)

    Roberts, Merrill A.; Uritsky, Vadim M.; Karpen, Judith T.; DeVore, C. R.

    2015-04-01

    Solar polar jets are observed to originate in regions within the open field of solar coronal holes. These so called “anemone” regions are associated with an embedded dipole topology, consisting of a fan-separatrix and a spine line emanating from a null point occurring at the top of the dome shaped fan surface (Antiochos 1998). In this study, we analyze simulations using the Adaptively Refined MHD Solver (ARMS) that take into account gravity, solar wind, and spherical geometry to generate polar jets by reconnection between a twisted embedded bipole and the surrounding open field (Karpen et al. 2015). These new simulations confirm and extend previous Cartesian studies of polar jets based on this mechanism (Pariat et al. 2009, 2010, 2015). Focusing on the plasma density, velocity, and magnetic field, we interpolate the adaptively gridded simulation data onto a regular grid, and analyze the signatures that the jet produces as it propagates outward from the solar surface. The trans-Alfvénic nature of the jet front is confirmed by temporally differencing the plasma mass density and comparing the result with the local Alfvén speed. We perform a preliminary analysis of the magnetized plasma turbulence, and examine how the turbulence affects the overall structure of the jet. We also conduct simulated spacecraft fly-throughs of the jet, illustrating the signatures that spacecraft such as Solar Probe Plus may encounter in situ as the jet propagates into the heliosphere. These fly-throughs are performed in several different velocity regimes to better model the changing velocity of Solar Probe Plus relative to the Sun and its jets over the course of the mission.This research was supported by NASA grant NNG11PL10A 670.036 to CUA/IACS (M.A.R. and V.M.U.) and the Living With a Star Targeted Research and Technology (J.T.K. and C.R.D.) program.

  15. Solvent effects and polar interactions in the structural stability and dynamics of globular proteins

    Energy Technology Data Exchange (ETDEWEB)

    Finney, J.L.; Gellatly, B.J.; Golton, I.C.; Goodfellow, J.

    1980-10-01

    Using detailed hydrogen bonding, surface exposure, internal environment, and solvent interaction calculations on several proteins, in conjnction with data from quantum mechanical hydrogen-bonding studies, various contributions to the free energy of folding are estimated and their likely relative significance discussed. A picture emerges of globular proteins as extremely well-fitting jigsaw-puzzles, in which no single driving force dominates the marginal stability of the native conformation. Rather, the folded structure is seen as the result of a complex global maximization of several strongly-interacting driving forces. In particular, the necessity to maintain very efficient internal hydrogen-bonding, and the role of the solvent as a hydrogen-bond sink, are stressed as strong constraints on the (incomplete) maximization of hydrophobic effects. The possible significance of internal dipole-induced dipole interactions is discussed tentatively. Although quantitative estimates of the various contributions remain uncertain, consideration of effective force constants suggests that polar, including solvent, interactions may largely determine the overall curvatures of the native conformation's potential well, and be important in controlling the flexibility of local regions which are important for the exact positioning of groups during enzyme catalysis, as well as the molecule's overall dynamics. In contrast, hydrophobic interactions change less for small geometrical perturbations, and seem more relevant to directing the folding protein along a path to a region in configurational space where the polar interactions can switch on for the final docking.

  16. Climate change and the increasing impact of polar bears on bird populations

    OpenAIRE

    Prop, Jouke; Aars, Jon; Bårdsen, Bård-Jørgen; Hanssen, Sveinn A; Bech, Claus; Bourgeon, Sophie; de Fouw, Jimmy; Gabrielsen, Geir W; Lang, Johannes; Noreen, Elin; Oudman, Thomas; Sittler, Benoit; Stempniewicz, Lech; Tombre, Ingunn; Wolters, Eva

    2015-01-01

    The Arctic is becoming warmer at a high rate, and contractions in the extent of sea ice are currently changing the habitats of marine top-predators dependent on ice. Polar bears (Ursus maritimus) depend on sea ice for hunting seals. For these top-predators, longer ice-free seasons are hypothesized to force the bears to hunt for alternative terrestrial food, such as eggs from colonial breeding birds. We analyzed time-series of polar bear observations at four locations on Spitsbergen (Svalbard)...

  17. Vectorial Structure of Non-Paraxial Linearly Polarized Gaussian Beam in Far Field

    Institute of Scientific and Technical Information of China (English)

    ZHOU Guo-Quan; CHEN Liang; NI Yong-Zhou

    2006-01-01

    @@ According to the vectorial structure of non-paraxial electromagnetic beams and the method of stationary phase,the analytical TE and TM terms of non-paraxial linearly polarized Gaussian beam are presented in the far field.The influence of linearly polarized angle on the relative energy flux distributions of the whole beam and its TE and TM terms is studied. The beam spot of the TE term is perpendicular to the direction of linearly polarized angle, while that of the TM term coincides with the direction of linearly polarized angle. The whole beam spot is elliptical, and the long axis is located at the direction of linearly polarized angle. The relative energy flux distribution of the TE term is relatively centralized in the direction perpendicular to the linearly polarized angle.While that of the TM term is relatively centralized in the direction of linearly polarized angle. To obtain the isolated TM and TE terms, a polarizer should be put at the long and the short axis of the whole beam. spot,respectively.

  18. Changing governance structures in South African agribusiness

    NARCIS (Netherlands)

    Doyer, O.T.; Haese, D' M.F.C.; Rooyen, van C.J.; Kirsten, J.F.; Haese, D' L.

    2008-01-01

    This article examines the changing governance structures in the South African agri-food sector. Changing legislative and market conditions forced agribusiness managers to rethink their governance structures to ensure the competitiveness of the agri-food sector. They had to adapt to the new structure

  19. Neutral hydrogen structures trace dust polarization angle: Implications for the interstellar medium and CMB foregrounds

    CERN Document Server

    Clark, S E; Peek, J E G; Putman, M E; Babler, B L

    2015-01-01

    Using high-resolution data from the Galactic Arecibo L-Band Feed Array HI (GALFA-HI) survey, we show that linear structure in Galactic neutral hydrogen (HI) correlates with the magnetic field orientation implied by Planck 353 GHz polarized dust emission. The structure of the neutral interstellar medium is more tightly coupled to the magnetic field than previously known. At high Galactic latitudes, where the Planck data are noise-dominated, the HI data provide an independent constraint on the Galactic magnetic field orientation, and hence the local dust polarization angle. We detect strong cross-correlations between template maps constructed from estimates of dust intensity combined with either HI-derived angles, starlight polarization angles, or Planck 353 GHz angles. The HI data thus provide a new tool in the search for inflationary gravitational wave B-mode polarization in the cosmic microwave background, which is currently limited by dust foreground contamination.

  20. Probing space-time structure of new physics with polarized beams at the international linear collider

    Indian Academy of Sciences (India)

    B Ananthanarayan

    2007-11-01

    At the international linear collider large beam polarization of both the electron and positron beams will enhance the signature of physics due to interactions that are beyond the standard model. Here we review our recently obtained results on a general model-independent method of determining for an arbitary one-particle inclusive state the space-time structure of such new physics through the beam polarization dependence and angular distribution of the final state particle.

  1. Emergent Structures in an Active Polar Fluid : dynamics of shape, scattering and merger

    CERN Document Server

    Husain, Kabir

    2016-01-01

    Spatially localised defect structures emerge spontaneously in a hydrodynamic description of an active polar fluid comprising polar 'actin' filaments and 'myosin' motor proteins that (un)bind to filaments and exert active contractile stresses. These emergent defect structures are characterized by distinct textures and can be either static or mobile - we derive effective equations of motion for these 'extended particles' and analyse their shape, kinetics, interactions and scattering. Depending on the impact parameter and propulsion speed, these active defects undergo elastic scattering or merger. Our results are relevant for the dynamics of actomyosin-dense structures at the cell cortex, reconstituted actomyosin complexes and 2D active colloidal gels.

  2. Innovation, Productivity Growth, and Structural Change

    OpenAIRE

    Maier, H.

    1984-01-01

    This paper is concerned with three broad topics: first, changes in the conditions for productivity growth during the last decade; second, industrial innovation as a factor of productivity growth; and third, productivity as a factor of structural change.

  3. Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom Fragilariopsis cylindrus

    DEFF Research Database (Denmark)

    Pancic, Marina; Hansen, Per Juel; Tammilehto, Anna;

    2015-01-01

    Abstract. The effects of ocean acidification and increased temperature on physiology of six strains of the polar diatom Fragilariopsis cylindrus from Greenland were investigated. Experiments were performed under manipulated pH levels (8.0, 7.7, 7.4, and 7.1) and different temperatures (1, 5, and 8...... C) to simulate changes from present to plausible future levels. Each of the 12 scenarios was run for 7 days, and a significant interaction between temperature and pH on growth was detected. By combining increased temperature and acidification, the two factors counterbalanced each other...... the strains was larger than the variation observed due to the whole range of changes in either pH or temperature. Climate change may therefore not affect the species as such, but may lead to changes in the population structure of the species, with the strains exhibiting high phenotypic plasticity, in terms...

  4. Nuclear-polarization effect to the hyperfine structure in heavy multicharged ions

    OpenAIRE

    Nefiodov, A. V.; Plunien, G.; Soff, G.

    2002-01-01

    We have investigated the correction to the hyperfine structure of heavy multicharged ions, which is connected with the nuclear-polarization effect caused by the unpaired bound electron. Numerical calculations are performed for hydrogenlike ions taking into account the dominant collective nuclear excitations. The correction defines the ultimate limit of precision in accurate theoretical predictions of the hyperfine-structure splittings.

  5. The research of Polar sea ice and its role in climate change

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    As an important part of global climate system, the Polar sea ice is effecting on global climate changes through ocean surface radiation balance, mass balance, energy balance as well as the circulating of sea water temperature and salinity. Sea ice research has a centuries-old history. The many correlative sea ice projects were established through the extensive international cooperation during the period from the primary research of intensity and the bearing capacity of sea ice to the development of sea/ice/air coupled model. Based on these researches, the sea ice variety was combined with the global climate change. All research about sea ice includes: the physical properties and processes of sea ice and its snow cover, the ecosystem of sea ice regions, sea ice and upper snow albedo, mass balance of sea ice regions, sea ice and climate coupled model. The simulation suggests that the both of the area and volume of polar sea ice would be reduced in next century. With the developing of the sea ice research, more scientific issues are mentioned. Such as the interaction between sea ice and the other factors of global climate system, the seasonal and regional distribution of polar sea ice thickness, polar sea ice boundary and area variety trends, the growth and melt as well as their influencing factors, the role of the polynya and the sea/air interactions. We should give the best solutions to all of the issues in future sea ice studying.

  6. Identifying polar bear resource selection patterns to inform offshore development in a dynamic and changing Arctic

    Science.gov (United States)

    Wilson, Ryan R.; Horne, Jon S.; Rode, Karyn D.; Regehr, Eric V.; Durner, George M.

    2014-01-01

    Although sea ice loss is the primary threat to polar bears (Ursus maritimus), little can be done to mitigate its effects without global efforts to reduce greenhouse gas emissions. Other factors, however, could exacerbate the impacts of sea ice loss on polar bears, such as exposure to increased industrial activity. The Arctic Ocean has enormous oil and gas potential, and its development is expected to increase in the coming decades. Estimates of polar bear resource selection will inform managers how bears use areas slated for oil development and to help guide conservation planning. We estimated temporally-varying resource selection patterns for non-denning adult female polar bears in the Chukchi Sea population (2008–2012) at two scales (i.e., home range and weekly steps) to identify factors predictive of polar bear use throughout the year, before any offshore development. From the best models at each scale, we estimated scale-integrated resource selection functions to predict polar bear space use across the population's range and determined when bears were most likely to use the region where offshore oil and gas development in the United States is slated to occur. Polar bears exhibited significant intra-annual variation in selection patterns at both scales but the strength and annual patterns of selection differed between scales for most variables. Bears were most likely to use the offshore oil and gas planning area during ice retreat and growth with the highest predicted use occurring in the southern portion of the planning area. The average proportion of predicted high-value habitat in the planning area was >15% of the total high-value habitat for the population during sea ice retreat and growth and reached a high of 50% during November 2010. Our results provide a baseline on which to judge future changes to non-denning adult female polar bear resource selection in the Chukchi Sea and help guide offshore development in the region. Lastly, our study provides a

  7. Post-equinox dynamics and polar cloud structure on Uranus

    CERN Document Server

    Sromovsky, Lawrence; Hammel, Heidi; de Pater, Imke; Rages, Kathy

    2015-01-01

    Post equinox imaging of Uranus by HST, Keck, and Gemini telescopes has enabled new measurements of winds over previously sampled latitudes as well as measurements at high northern latitudes that have recently come into better view. These new observations also used techniques to greatly improve signal to noise ratios, making possible the detection and tracking of more subtle cloud features. The 250 m/s prograde jet peaking near 60 N was confirmed and more accurately characterized. Several long-lived cloud features have also been tracked. The winds pole-ward of 60 N are consistent with solid body rotation at a westward (prograde) rate of 4.3 deg/h with respect to Uranus' interior. When combined with 2007 and other recent measurements, it is clear that a small but well-resolved asymmetry exists in the zonal profile at middle latitudes, peaking at 35 deg, where southern winds are 20 m/s more westward than corresponding northern winds. High S/N Keck II imaging of the north polar region of Uranus reveals a transiti...

  8. Radio polarization and magnetic field structure in M 101

    Science.gov (United States)

    Berkhuijsen, E. M.; Urbanik, M.; Beck, R.; Han, J. L.

    2016-04-01

    We observed total and polarized radio continuum emission from the spiral galaxy M 101 at λλ 6.2 cm and 11.1 cm with the Effelsberg telescope. The angular resolutions are 2.´ 5 (=5.4 kpc) and 4.´ 4 (=9.5 kpc), respectively. We use these data to study various emission components in M 101 and properties of the magnetic field. Separation of thermal and non-thermal emission shows that the thermal emission is closely correlated with the spiral arms, while the non-thermal emission is more smoothly distributed indicating diffusion of cosmic ray electrons away from their places of origin. The radial distribution of both emissions has a break near R = 16 kpc (=7.´ 4), where it steepens to an exponential scale length of L ≃ 5 kpc, which is about 2.5 times smaller than at Rlaw exponent of b = 0.28 ± 0.02. The ordered magnetic field is generally aligned with the spiral arms with pitch angles that are about 8° larger than those of H i filaments. Based on observations with the 100 m telescope of the MPIfR at Effelsberg.FITS files of the images are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A114

  9. IDENTIFYING SURFACE CHANGES ON HRSC IMAGES OF THE MARS SOUTH POLAR RESIDUAL CAP (SPRC

    Directory of Open Access Journals (Sweden)

    A. R. D. Putri

    2016-06-01

    Full Text Available The surface of Mars has been an object of interest for planetary research since the launch of Mariner 4 in 1964. Since then different cameras such as the Viking Visual Imaging Subsystem (VIS, Mars Global Surveyor (MGS Mars Orbiter Camera (MOC, and Mars Reconnaissance Orbiter (MRO Context Camera (CTX and High Resolution Imaging Science Experiment (HiRISE have been imaging its surface at ever higher resolution. The High Resolution Stereo Camera (HRSC on board of the European Space Agency (ESA Mars Express, has been imaging the Martian surface, since 25th December 2003 until the present-day. HRSC has covered 100 % of the surface of Mars, about 70 % of the surface with panchromatic images at 10-20 m/pixel, and about 98 % at better than 100 m/pixel (Neukum et. al., 2004, including the polar regions of Mars. The Mars polar regions have been studied intensively recently by analysing images taken by the Mars Express and MRO missions (Plaut et al., 2007. The South Polar Residual Cap (SPRC does not change very much in volume overall but there are numerous examples of dynamic phenomena associated with seasonal changes in the atmosphere. In particular, we can examine the time variation of layers of solid carbon dioxide and water ice with dust deposition (Bibring, 2004, spider-like channels (Piqueux et al., 2003 and so-called Swiss Cheese Terrain (Titus et al., 2004. Because of seasonal changes each Martian year, due to the sublimation and deposition of water and CO2 ice on the Martian south polar region, clearly identifiable surface changes occur in otherwise permanently icy region. In this research, good quality HRSC images of the Mars South Polar region are processed based on previous identification as the optimal coverage of clear surfaces (Campbell et al., 2015. HRSC images of the Martian South Pole are categorized in terms of quality, time, and location to find overlapping areas, processed into high quality Digital Terrain Models (DTMs and

  10. Identifying Surface Changes on HRSC Images of the Mars South Polar Residual CAP (sprc)

    Science.gov (United States)

    Putri, Alfiah Rizky Diana; Sidiropoulos, Panagiotis; Muller, Jan-Peter

    2016-06-01

    The surface of Mars has been an object of interest for planetary research since the launch of Mariner 4 in 1964. Since then different cameras such as the Viking Visual Imaging Subsystem (VIS), Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), and Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) have been imaging its surface at ever higher resolution. The High Resolution Stereo Camera (HRSC) on board of the European Space Agency (ESA) Mars Express, has been imaging the Martian surface, since 25th December 2003 until the present-day. HRSC has covered 100 % of the surface of Mars, about 70 % of the surface with panchromatic images at 10-20 m/pixel, and about 98 % at better than 100 m/pixel (Neukum et. al., 2004), including the polar regions of Mars. The Mars polar regions have been studied intensively recently by analysing images taken by the Mars Express and MRO missions (Plaut et al., 2007). The South Polar Residual Cap (SPRC) does not change very much in volume overall but there are numerous examples of dynamic phenomena associated with seasonal changes in the atmosphere. In particular, we can examine the time variation of layers of solid carbon dioxide and water ice with dust deposition (Bibring, 2004), spider-like channels (Piqueux et al., 2003) and so-called Swiss Cheese Terrain (Titus et al., 2004). Because of seasonal changes each Martian year, due to the sublimation and deposition of water and CO2 ice on the Martian south polar region, clearly identifiable surface changes occur in otherwise permanently icy region. In this research, good quality HRSC images of the Mars South Polar region are processed based on previous identification as the optimal coverage of clear surfaces (Campbell et al., 2015). HRSC images of the Martian South Pole are categorized in terms of quality, time, and location to find overlapping areas, processed into high quality Digital Terrain Models (DTMs) and

  11. Plasmonic structure integrated single-photon detector configurations to improve absorptance and polarization contrast

    CERN Document Server

    Csete, Maria; Szenes, Andras; Szalai, Aniko; Szabo, Gabor

    2014-01-01

    Configurations capable of maximizing both absorptance and polarization contrast were determined for 1550 nm polarized light illumination of different plasmonic structure integrated superconducting nanowire single-photon detectors (SNSPDs) consisting of p=264 nm and P=792 nm periodic niobium-nitride (NbN) patterns on silica substrate. Global NbN absorptance maxima appear in case of p/s-polarized light illumination in S/P-orientation (gamma=90 azimuthal angle) and the highest polarization contrast is attained in S-orientation of all devices. Common nanophotonical origin of absorptance enhancement is collective resonance on nano-cavity-gratings with different profiles, which is promoted by coupling between localized modes in quarter wavelength MIM nano-cavities and laterally synchronized Brewster-Zenneck-type surface waves in integrated SNSPDs possessing a three-quarter-wavelength-scaled periodicity. The spectral sensitivity and dispersion characteristics reveal that device design specific optimal configurations...

  12. The optical polarization signatures of fragmented equatorial dusty structures in Active Galactic Nuclei

    CERN Document Server

    Marin, F

    2015-01-01

    If the existence of an obscuring circumnuclear region around the innermost regions of active galactic nuclei (AGN) has been observationally proven, its geometry remains highly uncertain. The morphology usually adopted for this region is a toroidal structure, but other alternatives, such as flared disks, can be a good representative of equatorial outflows. Those two geometries usually provide very similar spectroscopic signatures, even when they are modeled under the assumption of fragmentation. In this lecture note, we show that the resulting polarization signatures of the two models, either a torus or a flared disk, are quite different from each other. We use a radiative transfer code that computes the 2000 - 8000 angstrom polarization of the two morphologies in a clumpy environment, and show that varying the sizes of a toroidal region has deep impacts onto the resulting polarization, while the polarization of flared disks is independent of the outer radius. Clumpy flared disks also produce higher polarizati...

  13. Phase-space structures and ionization dynamics of the hydrogen atom in elliptically polarized microwaves

    Science.gov (United States)

    Shchekinova, E.; Chandre, C.; Uzer, T.

    2006-10-01

    The multiphoton ionization of hydrogen atoms in a strong elliptically polarized microwave field exhibits complex features that are not observed for ionization in circular and linear polarized fields. Experimental data reveal high sensitivity of ionization dynamics to the small changes of the field polarization. The multidimensional nature of the problem makes widely used diagnostics of dynamics, such as Poincaré surfaces of section, impractical. We analyze the phase-space dynamics using the finite time stability analysis rendered by the fast Lyapunov indicators technique. The concept of zero-velocity surface is used to initialize the calculations and visualize the dynamics. Our analysis provides stability maps calculated for the initial energy at the maximum and below the saddle of the zero-velocity surface. We estimate qualitatively the dependence of ionization thresholds on the parameters of the applied field, such as polarization and scaled amplitude.

  14. The change of GRB polarization angles in the magnetic-dominated jet model

    CERN Document Server

    Chang, Zhe

    2014-01-01

    The polarimetric measurement on the prompt phase of GRB 100826A shows that the polarization angle changes $\\sim 90^{\\circ}$ between two adjacent time intervals. This phenomenon can be naturally interpreted in the framework of the magnetic-dominated-jet (MDJ) model. The MDJ model suggests that the bulk Lorentz factor of outflow increases as $\\Gamma\\propto r^{1/3}$ until reaching a saturated value $\\Gamma_{\\rm sat}$. Electrons move in the magnetic field and produce synchrotron photons. A beam of synchrotron photons travel alone the jet direction and then collide with the cold electrons at the front of the jet. After the Compton scattering process, these photons are detected by the observer locating slightly off-axis. If photons are emitted before the bulk Lorentz factor saturates, the change of polarization angle is a natural result of the acceleration of outflow.

  15. Structural Change and Macrodynamic Capabilities

    OpenAIRE

    Araujo, Ricardo Azevedo; Teixeira, Joanilio Rodolpho

    2010-01-01

    In this paper we intend to study some mechanisms that block a rapid diffusion of technological progress from advanced to underdeveloped countries. In order to accomplish this task we focus on two approaches that challenge the view that technological gaps between rich and poor nations are diminishing. The first is the structural economic dynamic approach and the second is the evolutionary view. Both of them reveal that the elimination of the technological gaps between rich and poor nations is ...

  16. The structural properties of sustainable, continuous change

    DEFF Research Database (Denmark)

    Håkonsson, Dorthe Døjbak; Klaas, Johann Peter; Carroll, Timothy

    2013-01-01

    this relationship by exploring what structural properties enable continuous change in inertia-generating organizations and what their performance consequences are in dynamic environments. The article has three main findings: First, employing managers who anticipate change is not enough to generate continuous change......; it is also necessary to raise both the rate of responsiveness and desired performance. Second, continuous change increases average organizational performance and reduces its variation. Third, organizations’ capacity for continuous change is counterintuitively limited by the organizations’ capacity to build...

  17. Unsolved problems: Mesoscale polar cap flow channels' structure, propagation, and effects on space weather disturbances

    Science.gov (United States)

    Lyons, L. R.; Nishimura, Y.; Zou, Y.

    2016-04-01

    Recent evidence indicates that the magnetosphere-ionosphere system is frequently driven by dynamic mesoscale flow structures that are first seen near the dayside cusps, move across the open field line regions of the polar caps, and then enter the plasma sheet where they lead to a large variety of space weather disturbances. It will be important to uncover the features of these flow enhancements, including their structure, how they propagate across the polar cap, and what controls their dynamic effects after reaching the nightside plasma sheet.

  18. Low frequency observations of linearly polarized structures in the interstellar medium near the south Galactic pole

    CERN Document Server

    Lenc, Emil; Sun, X H; Sadler, E M; Willis, A G; Barry, N; Beardsley, A P; Bell, M E; Bernardi, G; Bowman, J D; Briggs, F; Callingham, J R; Cappallo, R J; Carroll, P; Corey, B E; de Oliveira-Costa, A; Deshpande, A A; Dillon, J S; Dwarkanath, K S; Emrich, D; Ewall-Wice, A; Feng, L; For, B -Q; Goeke, R; Greenhill, L J; Hancock, P; Hazelton, B J; Hewitt, J N; Hindson, L; Hurley-Walker, N; Johnston-Hollitt, M; Jacobs, D C; Kapinska, A D; Kaplan, D L; Kasper, J C; Kim, H -S; Kratzenberg, E; Line, J; Loeb, A; Lonsdale, C J; Lynch, M J; McKinley, B; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Morgan, J; Murphy, T; Neben, A R; Oberoi, D; Offringa, A R; Ord, S M; Paul, S; Pindor, B; Pober, J C; Prabu, T; Procopio, P; Riding, J; Rogers, A E E; Roshi, A; Shankar, N Udaya; Sethi, S K; Srivani, K S; Staveley-Smith, L; Subrahmanyan, R; Sullivan, I S; Tegmark, M; Thyagarajan, Nithyanandan; Tingay, S J; Trott, C; Waterson, M; Wayth, R B; Webster, R L; Whitney, A R; Williams, A; Williams, C L; Wu, C; Wyithe, J S B; Zheng, Q

    2016-01-01

    We present deep polarimetric observations at 154 MHz with the Murchison Widefield Array (MWA), covering 625 deg^2 centered on RA=0 h, Dec=-27 deg. The sensitivity available in our deep observations allows an in-band, frequency-dependent analysis of polarized structure for the first time at long wavelengths. Our analysis suggests that the polarized structures are dominated by intrinsic emission but may also have a foreground Faraday screen component. At these wavelengths, the compactness of the MWA baseline distribution provides excellent snapshot sensitivity to large-scale structure. The observations are sensitive to diffuse polarized emission at ~54' resolution with a sensitivity of 5.9 mJy beam^-1 and compact polarized sources at ~2.4' resolution with a sensitivity of 2.3 mJy beam^-1 for a subset (400 deg^2) of this field. The sensitivity allows the effect of ionospheric Faraday rotation to be spatially and temporally measured directly from the diffuse polarized background. Our observations reveal large-sca...

  19. Structural changes concurrent with ferromagnetic transition

    Institute of Scientific and Technical Information of China (English)

    Yang Sen; Bao Hui-Xin; Zhou Chao; Wang Yu; Ren Xiao-Bing; Song Xiao-Ping; Yoshitaka Matsushita

    2013-01-01

    Ferromagnetic transition has generally been considered to involve only an ordering of magnetic moment with no change in the host crystal structure or symmetry,as evidenced by a wealth of crystal structure data from conventional X-ray diffractometry (XRD).However,the existence of magnetostriction in all known ferromagnetic systems indicates that the magnetic moment is coupled to the crystal lattice; hence there is a possibility that magnetic ordering may cause a change in crystal structure.With the development of high-resolution synchrotron XRD,more and more magnetic transitions have been found to be accompanied by simultaneous structural changes.In this article,we review our recent progress in understanding the structural change at a ferromagnetic transition,including synchrotron XRD evidence of structural changes at the ferromagnetic transition,a phenomenological theory of crystal structure changes accompanying ferromagnetic transitions,new insight into magnetic morphotropic phase boundaries (MPB) and so on.Two intriguing implications of non-centric symmetry in the ferromagnetic phase and the first-order nature of ferromagnetic transition are also discussed here.In short,this review is intended to give a self-consistent and logical account of structural change occurring simultaneously with a ferromagnetic transition,which may provide new insight for developing highly magneto-responsive materials.

  20. Chiral Nematic Structure of Cellulose Nanocrystal Suspensions and Films; Polarized Light and Atomic Force Microscopy

    Directory of Open Access Journals (Sweden)

    Derek G. Gray

    2015-11-01

    Full Text Available Cellulosic liquid crystalline solutions and suspensions form chiral nematic phases that show a rich variety of optical textures in the liquid crystalline state. These ordered structures may be preserved in solid films prepared by evaporation of solvent or suspending medium. Film formation from aqueous suspensions of cellulose nanocrystals (CNC was investigated by polarized light microscopy, optical profilometry and atomic force microscopy (AFM. An attempt is made to interpret qualitatively the observed textures in terms of the orientation of the cellulose nanocrystals in the suspensions and films, and the changes in orientation caused by the evaporative process. Mass transfer within the evaporating droplet resulted in the formation of raised rings whose magnitude depended on the degree of pinning of the receding contact line. AFM of dry films at short length scales showed a radial orientation of the CNC at the free surface of the film, along with a radial height variation with a period of approximately P/2, ascribed to the anisotropic shrinkage of the chiral nematic structure.

  1. Tailoring the crystal structure of individual silicon nanowires by polarized laser annealing.

    Science.gov (United States)

    Chang, Chia-Chi; Chen, Haitian; Chen, Chun-Chung; Hung, Wei-Hsuan; Hsu, I-Kai; Theiss, Jesse; Zhou, Chongwu; Cronin, Stephen B

    2011-07-29

    We study the effect of polarized laser annealing on the crystalline structure of individual crystalline-amorphous core-shell silicon nanowires (NWs) using Raman spectroscopy. The crystalline fraction of the annealed spot increases dramatically from 0 to 0.93 with increasing incident laser power. We observe Raman lineshape narrowing and frequency hardening upon laser annealing due to the growth of the crystalline core, which is confirmed by high resolution transmission electron microscopy (HRTEM). The anti-Stokes:Stokes Raman intensity ratio is used to determine the local heating temperature caused by the intense focused laser, which exhibits a strong polarization dependence in Si NWs. The most efficient annealing occurs when the laser polarization is aligned along the axis of the NWs, which results in an amorphous-crystalline interface less than 0.5 µm in length. This paper demonstrates a new approach to control the crystal structure of NWs on the sub-micron length scale.

  2. Evaluation of Waveform Structure Features on Time Domain Target Recognition under Cross Polarization

    Science.gov (United States)

    Selver, M. A.; Seçmen, M.; Zoral, E. Y.

    2016-08-01

    Classification of aircraft targets from scattered electromagnetic waves is a challenging application, which suffers from aspect angle dependency. In order to eliminate the adverse effects of aspect angle, various strategies were developed including the techniques that rely on extraction of several features and design of suitable classification systems to process them. Recently, a hierarchical method, which uses features that take advantage of waveform structure of the scattered signals, is introduced and shown to have effective results. However, this approach has been applied to the special cases that consider only a single planar component of electric field that cause no-cross polarization at the observation point. In this study, two small scale aircraft models, Boeing-747 and DC-10, are selected as the targets and various polarizations are used to analyse the cross-polarization effects on system performance of the aforementioned method. The results reveal the advantages and the shortcomings of using waveform structures in time-domain target identification.

  3. Dielectric inspired scaling of polarization conversion subwavelength resonances in open ultrathin chiral structures

    Science.gov (United States)

    Serebryannikov, Andriy E.; Mutlu, Mehmet; Ozbay, E.

    2015-11-01

    It is shown that the scaling of subwavelength resonances in open ultrathin chiral structures can be obtained by varying only the permittivity of dielectric spacers, while multiband one-way polarization conversion and related asymmetric transmission remain possible. These features are quite general and obtainable in a wide range of parameter variation. Surprisingly, the difference in the power of ɛ for the classical ɛ-1/2 scaling rule and the empirical rules obtained in the present letter does not exceed 22%, giving an important entry point for future theoretical studies and design strategies. Both spectral scaling and conservation of the polarization characteristics can be achieved by using either tunneling or real-index impedance matching. The scaled structures with strong polarization and directional selectivity may have thickness of λ/100 and smaller.

  4. Long-living structures of photochromic salicylaldehyde azine: polarity and viscosity effects from nanoseconds to hours.

    Science.gov (United States)

    Ziółek, Marcin; Burdziński, Gotard; Douhal, Abderrazzak

    2012-08-01

    In this study, we report on the effects of solvent viscosity and polarity on the photochromic salicylaldehyde azine (SAA) molecule by examining the steady-state and UV-visible absorption results in the time scale from nanoseconds to hours, in solution and in a polymer film. For the neutral structure, the viscosity strongly affects the lifetime of the photochromic (trans-keto) tautomer by suppressing the second order quenching process, and thus increasing the photochrome lifetimes in highly viscous solvents to 500 μs in polar triacetine, and to 65 μs in non-polar squalane. Trapping SAA in a non-polar polymer film (polyethylene) results in further elongation of the photochromic lifetime (700 μs) by one order of magnitude (with respect to that in squalane), due to the retardation of the intramolecular back-isomerization. Another species, living significantly longer and absorbing more in the UV comparing to the photochrome, was identified as the syn-enol tautomer. The lifetime of this tautomer, created in a competitive mechanism to the photochrome creation, is much longer in non-polar solvents (hundreds of minutes) than in polar ones (tens of minutes), opposite to the trend observed for the photochrome. For the SAA anion, the transient living on the ns-μs time scale can be exclusively assigned to the triplet state, which is not observed for the neutral form at room temperature.

  5. Polarization switching and patterning in self-assembled peptide tubular structures

    Science.gov (United States)

    Bdikin, Igor; Bystrov, Vladimir; Delgadillo, Ivonne; Gracio, José; Kopyl, Svitlana; Wojtas, Maciej; Mishina, Elena; Sigov, Alexander; Kholkin, Andrei L.

    2012-04-01

    Self-assembled peptide nanotubes are unique nanoscale objects that have great potential for a multitude of applications, including biosensors, nanotemplates, tissue engineering, biosurfactants, etc. The discovery of strong piezoactivity and polar properties in aromatic dipeptides [A. Kholkin, N. Amdursky, I. Bdikin, E. Gazit, and G. Rosenman, ACS Nano 4, 610 (2010)] opened up a new perspective for their use as biocompatible nanoactuators, nanomotors, and molecular machines. Another, as yet unexplored functional property is the ability to switch polarization and create artificial polarization patterns useful in various electronic and optical applications. In this work, we demonstrate that diphenylalanine peptide nanotubes are indeed electrically switchable if annealed at a temperature of about 150 °C. The new orthorhombic antipolar structure that appears after annealing allows for the existence of a radial polarization component, which is directly probed by piezoresponse force microscopy (PFM) measurements. Observation of the relatively stable polarization patterns and hysteresis loops via PFM testifies to the local reorientation of molecular dipoles in the radial direction. The experimental results are complemented with rigorous molecular calculations and create a solid background of electric-field induced deformation of aromatic rings and corresponding polarization switching in this emergent material.

  6. Factor Endowment, Structural Change, and Economic Growth

    OpenAIRE

    Che, Natasha Xingyuan

    2010-01-01

    This paper aims (1) to test the endowment-based structural change theory proposed by recent studies such as Acemoglu & Guerrieri (2008) and Ju, Lin & Wang (2009); and (2) to explore the linkage between structural coherence and economic growth. By structural coherence, I refer to the degree that a country’s industrial structure optimally reflects its factor endowment fundamentals. Using data from 27 industries across 15 countries, I examine whether higher capital endowment is associated w...

  7. Structural Anisotropy in Polar Fluids Subjected to Periodic Boundary Conditions

    Science.gov (United States)

    2011-01-01

    A heuristic model based on dielectric continuum theory for the long-range solvation free energy of a dipolar system possessing periodic boundary conditions (PBCs) is presented. The predictions of the model are compared to simulation results for Stockmayer fluids simulated using three different cell geometries. The boundary effects induced by the PBCs are shown to lead to anisotropies in the apparent dielectric constant and the long-range solvation free energy of as much as 50%. However, the sum of all of the anisotropic energy contributions yields a value that is very close to the isotropic one derived from dielectric continuum theory, leading to a total system energy close to the dielectric value. It is finally shown that the leading-order contribution to the energetic and structural anisotropy is significantly smaller in the noncubic simulation cell geometries compared to when using a cubic simulation cell. PMID:22303290

  8. Structure-Dependent Spin Polarization in Polymorphic CdS:Y Semiconductor Nanocrystals.

    Science.gov (United States)

    Wang, Pan; Xiao, Bingxin; Zhao, Rui; Ma, Yanzhang; Zhang, Mingzhe

    2016-03-01

    Searching for the polymorphic semiconductor nanocrystals would provide precise and insightful structure-spin polarization correlations and meaningful guidance for designing and synthesizing high spin-polarized spintronic materials. Herein, the high spin polarization is achieved in polymorphic CdS:Y semiconductor nanocrystals. The high-pressure polymorph of rock-salt CdS:Y nanocrystals has been recovered at ambient conditions synthesized by the wurtzite CdS:Y nanocrystals as starting material under 5.2 GPa and 300 °C conditions. The rock-salt CdS:Y polymorph displays more robust room-temperature ferromagnetism than wurtzite sample, which can reach the ferromagnetic level of conventional semiconductors doped with magnetic transition-metal ions, mainly due to the significantly enhanced spin configuration and defect states. Therefore, crystal structure directly governs the spin configuration, which determines the degree of spin polarization. This work can provide experimental and theoretical methods for designing the high spin-polarized semiconductor nanocrystals, which is important for applications in semiconductor spintronics.

  9. Diapause is associated with a change in the polarity of secretion of insulin-like peptides.

    Science.gov (United States)

    Matsunaga, Yohei; Honda, Yoko; Honda, Shuji; Iwasaki, Takashi; Qadota, Hiroshi; Benian, Guy M; Kawano, Tsuyoshi

    2016-01-01

    The insulin/IGF-1 signalling (IIS) pathway plays an important role in the regulation of larval diapause, the long-lived growth arrest state called dauer arrest, in Caenorhabditis elegans. In this nematode, 40 insulin-like peptides (ILPs) have been identified as putative ligands of the IIS pathway; however, it remains unknown how ILPs modulate larval diapause. Here we show that the secretory polarity of INS-35 and INS-7, which suppress larval diapause, is changed in the intestinal epithelial cells at larval diapause. These ILPs are secreted from the intestine into the body cavity during larval stages. In contrast, they are secreted into the intestinal lumen and degraded during dauer arrest, only to be secreted into the body cavity again when the worms return to developmental growth. The process that determines the secretory polarity of INS-35 and INS-7, thus, has an important role in the modulation of larval diapause. PMID:26838180

  10. Macroscale modeling and mesoscale observations of plasma density structures in the polar cap

    Energy Technology Data Exchange (ETDEWEB)

    Basu, S.; Basu, S.; Sojka, J.J.; Schunk, R.W.; MacKenzie, E.

    1995-04-15

    The seasonal and UT variation of mesoscale structures (10 km - 100 m) in the central polar cap has been obtained from an analysis of 250-MHz intensity scintillation observations made at Thule, Greenland. It has been established earlier that mesoscale structures causing scintillations of satellite signals may develop at the edges of macroscale structures (several hundred km) such as discrete polar cap plasma density enhancements or patches through the gradient drift instability process. As such, the authrs examined the seasonal and UT variation of polar cap patches simulated by using the USU Time Dependent Ionospheric Model (TDIM) under conditions of southward B(sub z). A fairly remarkable similarity is found between the scintillation observations and the model predictions of patch occurrence. For instance, both the patch and scintillation occurrences are minimized during the winter solstice (northern hemisphere) between 0800-1200 UT while also having their largest seasonal intensity between 2000-2400 UT. Little UT dependence of patches and scintillations is seen at equinox with high intensity being observed throughout the day, while during local summer the intensity of macroscale patches and mesoscale irregularities are found to be a minimum at all UT. These results indicate that macroscale features in the polar cap are routinely associated with plasma instabilities giving rise to smaller scale structures and that the specific patch formation mechanism assumed in the simulation is consistent with the observations.

  11. The Structure & Linear Polarization of the Kiloparsec-Scale Jet of the Quasar 3C\\,345

    CERN Document Server

    Roberts, David H; Marchenko, Valerie V

    2012-01-01

    Deep Very Large Array imaging of the quasar 3C\\,345 at 4.86 and 8.44 GHz has been used to study the structure and linear polarization of its radio jet on scales ranging from 2 to 30 kpc. There is a 7--8 Jy unresolved core with spectral index $\\alpha \\simeq -0.24$ ($I_\

  12. Effect of the change in statocyte polarity on calcium distribution: results from PolCa space experiment

    Science.gov (United States)

    Legue, Valerie; Pereda, Veronica; Gerard, Joelle; Eche, Brigitte; Gasset, Gilbert; Chaput, Didier

    Plants are the ability to sense and to re-orient their growth in response to gravity. In roots, specialized sensory cells (called statocytes) perceive signal gravity and are the only cells that exhibit structural polarity with respect to gravity providing interactions with starch-containing plastids (amyloplasts) and the cortical endoplasmic reticulum (ER). Upon root reorientation, a displacement of amyloplasts is observed and is accompanied with a change in direct amyloplast-ER direct interaction in root cap cells. Even if amyloplasts are widely considered as gravity sensor, there is no clear evidence that a change in amyloplasts-ER interactions could lead to a transduction gravity signal. Previous space experiments clearly showed that amyloplasts inter-action with ER are not necessary to lead to a root re-orientation, suggesting that amyloplasts displacement mediate transduction events through cytoskeleton reorganisation and calcium-dependant pathways. The objective of the space experiment called PolCa is to dissect the effect of change in amyloplasts-ER interactions on calcium dependant pathways. Space conditions provide a unique opportunity to provide a change of structural polarity in statocytes without a gravistimulation. PolCa experiment has been conducted using Brassica napus seedlings, which submitted four different conditions: continuously on 1 g centrifuge or continuously in micrograv-ity conditions. Some seedlings germinated on centrifuge have been transferred during 10 min in microgravity conditions, leading to a loss of amyloplast-ER interactions through amyloplasts displacement. Others seedlings germinated in microgravity conditions have been transferred on centrifuge during 10 min. In this situation, we observed a return of amyloplasts-ER interactions. We analysed the localisation of free calcium after chemical fixation and calcium precipitation using potassium pyroantimonate in these four situations. The observation of calcium precipita-tions with

  13. Macroscale modeling and mesoscale observations of plasma density structures in the polar cap

    Energy Technology Data Exchange (ETDEWEB)

    Basu, S. [Phillips Lab., Hanscom Air Force Base, MA (United States); Basu, S. [National Science Foundation, Arlington, VA (United States); Sojka, J.J. [Utah State Univ., Logan, UT (United States)] [and others

    1995-04-15

    The seasonal and UT variation of mesoscale structures (10 km - 100 m) in the central polar cap has been obtained from an analysis of 250-MHz intensity scintillation observations made at Thule, Greenland. It has been established earlier that mesoscale structures causing scintillations of satellite signals may develop at the edges of macroscale structures (several hundred km) such as discrete polar cap plasma density enhancements or patches through the gradient drift instability process. As such, the authors examined the seasonal and UT variation of polar cap patches simulated by using the USU Time Dependent Ionospheric Model (TDIM) under conditions of southward B{sub z}. A fairly remarkable similarity is found between the scintillation observations and the model predictions of patch occurrence. For instance, both the patch and scintillation occurrences are minimized during the winter solstice (northern hemisphere) between 0800-1200 UT while also having their largest seasonal intensity between 2000-2400 UT. Little UT dependence of patches and scintillations is seen at equinox with high intensity being observed throughout the day, while during local summer the intensity of macroscale patches and mesoscale irregularities are found to be a minimum at all UT. These results indicate that macroscale features in the polar cap are routinely associated with plasma instabilities giving rise to smaller scale structures and that the specific patch formation mechanism assumed in the simulation is consistent with the observations. This ability to bridge between macroscale modeling and mesoscale observations provides a natural framework for the modeling of mesoscale structures themselves. This mesoscale modeling, in turn, can be utilized in a variety of radar and communication systems applications in the polar region. 25 refs., 3 figs.

  14. Probing the Inner Structure of Polar Broad Absorption-Line Quasars

    Science.gov (United States)

    Ghosh, Kajal

    2008-10-01

    We have discovered a sample of polar broad absorption-line quasars (BALQSOs). We know their inclination angles with reasonable certainty. Thus, these are the ideal objects to probe their inner structure through the X-ray studies. However, to date, we do not have a reasonably good signal-to-noise ratio X-ray spectrum of any of these objects. Here, we propose deep XMM-Newton observations of four polar BALQSOs to study the physical processes responsible for the X-ray emission, distribution of BAL clouds, wind driven mechanism, jet entrainment, etc. Finally, all these results will be used to constrain our time-dependent hydrodynamical simulations.

  15. Forward versus backward polarization-resolved SHG imaging of collagen structure in tissues

    Science.gov (United States)

    Teulon, Claire; Gusachenko, Ivan; Latour, Gaël.; Schanne-Klein, Marie-Claire

    2016-03-01

    Second harmonic generation (SHG) is a powerful technique to observe fibrillar collagen without any staining and with a good contrast. More information about the molecular structure of collagen fibrils in tissues and their 3D distribution can be gained with polarization-resolved SHG imaging. Nevertheless, strong focusing is required for effective imaging and light propagation in tissues is complex and not thoroughly understood yet, preventing accurate and reproducible measurements. Theoretical analysis, vectorial numerical simulations and experiments were implemented to understand how the SHG signal builds up and how geometrical parameters affect polarization-resolved measurements in homogeneous collagen-rich tissues.

  16. The polarized structure function of the nucleons with a non-extensive statistical quark model

    Science.gov (United States)

    Trevisan, Luis A.; Mirez, Carlos

    2013-05-01

    We studied an application of nonextensive thermodynamics to describe the polarized structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution, often used in the statistical models, were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and the chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon and by Δu and Δd of the polarized functions.

  17. Structural Changes in Chinese Food Preferences

    OpenAIRE

    Hovhannisyan, Vardges; Gould, Brian W.

    2012-01-01

    The article tests for structural food preference change in urban China using province-level panel data from 2002 to 2010. We employ the Generalized Quadratic Almost Ideal Demand System to represent consumer preferences and estimate demand for seven food groups in a dynamic setting. This relaxes many of the restrictions on the demand models used in the literature on structural preference change. Our findings suggest that Chinese food preferences are continuing to evolve.

  18. Structural Organization of Insulin Fibrils Based on Polarized Raman Spectroscopy: Evaluation of Existing Models.

    Science.gov (United States)

    Sereda, Valentin; Sawaya, Michael R; Lednev, Igor K

    2015-09-01

    Many different proteins undergo misfolding and self-assemble into amyloid fibrils, resulting in a range of neurodegenerative diseases. The limitations of conventional methods of structural biology for fibril characterization have led to the use of polarized Raman spectroscopy for obtaining quantitative structural information regarding the organization of amyloid fibrils. Herein, we report the orientation of selected chemical groups and secondary structure elements in aligned insulin fibrils, including β-sheets, which possess a high level of orientation in the cross-β core, and α-helices in the disordered portions of the fibrils. Strong orientation of disulfide bonds in amyloid fibrils was also revealed, indicating their association with the fibril core. The determined orientation of chemical groups provides strong constraints for modeling the overall structure of amyloid fibrils, including the core and disordered parts. The developed methodology allows for the validation of structural models proposed in the literature for amyloid fibrils. Specifically, the polarized Raman data obtained herein strongly agreed with two insulin fibril models (Jiménez et al., Proc. Natl. Acad. Sci. U. S. A. 2002, 99, 9196-9201 and Ivanova et al., Proc. Natl. Acad. Sci. U. S. A. 2009, 106, 18990-18995) yet revealed significant qualitative and quantitative differences. This work demonstrates the great potential of polarized Raman spectroscopy for structural characterization of anisotropic biological species.

  19. Polarizing properties and structure of the cuticle of scarab beetles from the Chrysina genus.

    Science.gov (United States)

    Fernández Del Río, Lía; Arwin, Hans; Järrendahl, Kenneth

    2016-07-01

    The optical properties of several scarab beetles have been previously studied but few attempts have been made to compare beetles in the same genus. To determine whether there is any relation between specimens of the same genus, we have studied and classified seven species from the Chrysina genus. The polarization properties were analyzed with Mueller-matrix spectroscopic ellipsometry and the structural characteristics with optical microscopy and scanning electron microscopy. Most of the Chrysina beetles are green colored or have a metallic look (gold or silver). The results show that the green-colored beetles polarize reflected light mainly at off-specular angles. The gold-colored beetles polarize light left-handed near circular at specular reflection. The structure of the exoskeleton is a stack of layers that form a cusplike structure in the green beetles whereas the layers are parallel to the surface in the case of the gold-colored beetles. The beetle C. gloriosa is green with gold-colored stripes along the elytras and exhibits both types of effects. The results indicate that Chrysina beetles can be classified according to these two major polarization properties. PMID:27575166

  20. Polarizing properties and structure of the cuticle of scarab beetles from the Chrysina genus

    Science.gov (United States)

    Fernández del Río, Lía; Arwin, Hans; Järrendahl, Kenneth

    2016-07-01

    The optical properties of several scarab beetles have been previously studied but few attempts have been made to compare beetles in the same genus. To determine whether there is any relation between specimens of the same genus, we have studied and classified seven species from the Chrysina genus. The polarization properties were analyzed with Mueller-matrix spectroscopic ellipsometry and the structural characteristics with optical microscopy and scanning electron microscopy. Most of the Chrysina beetles are green colored or have a metallic look (gold or silver). The results show that the green-colored beetles polarize reflected light mainly at off-specular angles. The gold-colored beetles polarize light left-handed near circular at specular reflection. The structure of the exoskeleton is a stack of layers that form a cusplike structure in the green beetles whereas the layers are parallel to the surface in the case of the gold-colored beetles. The beetle C. gloriosa is green with gold-colored stripes along the elytras and exhibits both types of effects. The results indicate that Chrysina beetles can be classified according to these two major polarization properties.

  1. Dynamic Changes of Microglia/Macrophage M1 and M2 Polarization in Theiler's Murine Encephalomyelitis.

    Science.gov (United States)

    Herder, Vanessa; Iskandar, Cut Dahlia; Kegler, Kristel; Hansmann, Florian; Elmarabet, Suliman Ahmed; Khan, Muhammad Akram; Kalkuhl, Arno; Deschl, Ulrich; Baumgärtner, Wolfgang; Ulrich, Reiner; Beineke, Andreas

    2015-11-01

    Microglia and macrophages play a central role for demyelination in Theiler's murine encephalomyelitis (TME) virus infection, a commonly used infectious model for chronic-progressive multiple sclerosis. In order to determine the dynamic changes of microglia/macrophage polarization in TME, the spinal cord of Swiss Jim Lambert (SJL) mice was investigated by gene expression profiling and immunofluorescence. Virus persistence and demyelinating leukomyelitis were confirmed by immunohistochemistry and histology. Electron microscopy revealed continuous myelin loss together with abortive myelin repair during the late chronic infection phase indicative of incomplete remyelination. A total of 59 genes out of 151 M1- and M2-related genes were differentially expressed in TME virus-infected mice over the study period. The onset of virus-induced demyelination was associated with a dominating M1 polarization, while mounting M2 polarization of macrophages/microglia together with sustained prominent M1-related gene expression was present during the chronic-progressive phase. Molecular results were confirmed by immunofluorescence, showing an increased spinal cord accumulation of CD16/32(+) M1-, arginase-1(+) M2- and Ym1(+) M2-type cells associated with progressive demyelination. The present study provides a comprehensive database of M1-/M2-related gene expression involved in the initiation and progression of demyelination supporting the hypothesis that perpetuating interaction between virus and macrophages/microglia induces a vicious circle with persistent inflammation and impaired myelin repair in TME.

  2. Periodic magnetic structures generated by spin–polarized currents in nanostripes

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, Oleksii M., E-mail: alexey@volkov.ca; Sheka, Denis D. [Taras Shevchenko National University of Kiev, 01601 Kiev (Ukraine); Kravchuk, Volodymyr P.; Gaididei, Yuri [Bogolyubov Institute for Theoretical Physics, 03680 Kiev (Ukraine); Mertens, Franz G. [Physics Institute, University of Bayreuth, 95440 Bayreuth (Germany)

    2013-11-25

    The influence of a transverse spin–polarized current on long ferromagnetic nanostripes is studied numerically. The magnetization behavior is analyzed for all range of the applied currents, up to the saturation. It is shown that the saturation current is a nonmonotonic function of the stripe width. A number of stable periodic magnetization structures are observed below the saturation. Type of the periodical structure depends on the stripe width. Besides the one–dimensional domain structure, typical for narrow wires, and the two–dimensional vortex–antivortex lattice, typical for wide films, a number of intermediate structures are observed, e.g., cross–tie and diamond state.

  3. Determination of mask induced polarization effects on AltPSM mask structures

    Science.gov (United States)

    Hollein, Ingo; Teuber, Silvio; Bubke, Karsten

    2005-06-01

    In the process of discussion of possible mask-types for the 5x nm node (half-pitch) and below, the alternating phase-shifting mask (AltPSM) is a potential candidate to be screened. The current scenario suggests using 193 nm immersion lithography with NA values of up to 1.2 and above. New optical effects from oblique incident angles, mask-induced polarization of the transmitted light and birefringence from the substrate need to be taken into account when the optical performance of a mask is evaluated. This paper addresses mask induced polarization effects from dense lines-and-space structures on a real mask. Measurements of the polarization dependent diffraction efficiencies have been performed on AltPSM masks. Experimental results show good agreement with simulations. A comparison with Binary Masks is made.

  4. Temperature dependences of the electric polarization and wave number of incommensurate structures in multiferroics

    Science.gov (United States)

    Pikin, S. A.

    2016-05-01

    It is shown that the electric polarization and wave number of incommensurate modulations, proportional to each other, increase according to the Landau law in spin multiferroic cycloids near the Néel temperature. In this case, the constant magnetization component (including the one for a conical spiral) is oriented perpendicular to the spin incommensurability wave vector. A similar temperature behavior should manifest itself for spin helicoids, the axes of which are oriented parallel to the polarization vector but their spin rotation planes are oriented perpendicular to the antiferromagnetic order plane. When the directions of axes of the magnetization helicoid and polarization vector coincide, the latter is quadratic with respect to magnetization and linearly depends on temperature, whereas the incommensurate-modulation wave number barely depends on temperature. Structural distortions of unit cells for multiferroics of different types determine their axial behavior.

  5. Tip-induced domain structures and polarization switching in ferroelectric amino acid glycine

    Science.gov (United States)

    Seyedhosseini, E.; Bdikin, I.; Ivanov, M.; Vasileva, D.; Kudryavtsev, A.; Rodriguez, B. J.; Kholkin, A. L.

    2015-08-01

    Bioorganic ferroelectrics and piezoelectrics are becoming increasingly important in view of their intrinsic compatibility with biological environment and biofunctionality combined with strong piezoelectric effect and a switchable polarization at room temperature. Here, we study tip-induced domain structures and polarization switching in the smallest amino acid β-glycine, representing a broad class of non-centrosymmetric amino acids. We show that β-glycine is indeed a room-temperature ferroelectric and polarization can be switched by applying a bias to non-polar cuts via a conducting tip of atomic force microscope (AFM). Dynamics of these in-plane domains is studied as a function of an applied voltage and pulse duration. The domain shape is dictated by polarization screening at the domain boundaries and mediated by growth defects. Thermodynamic theory is applied to explain the domain propagation induced by the AFM tip. Our findings suggest that the properties of β-glycine are controlled by the charged domain walls which in turn can be manipulated by an external bias.

  6. Tip-induced domain structures and polarization switching in ferroelectric amino acid glycine

    Energy Technology Data Exchange (ETDEWEB)

    Seyedhosseini, E., E-mail: Seyedhosseini@ua.pt; Ivanov, M. [CICECO-Aveiro Institute of Materials and Department of Physics, University of Aveiro, 3810-193 Aveiro (Portugal); Bdikin, I. [TEMA and Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro (Portugal); Vasileva, D. [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Kudryavtsev, A. [Moscow State Institute of Radioengineering, Electronics and Automation, 119454 Moscow (Russian Federation); Rodriguez, B. J. [Conway Institute of Biomolecular and Biomedical Research and School of Physics, University College Dublin, Dublin (Ireland); Kholkin, A. L. [CICECO-Aveiro Institute of Materials and Department of Physics, University of Aveiro, 3810-193 Aveiro (Portugal); Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation)

    2015-08-21

    Bioorganic ferroelectrics and piezoelectrics are becoming increasingly important in view of their intrinsic compatibility with biological environment and biofunctionality combined with strong piezoelectric effect and a switchable polarization at room temperature. Here, we study tip-induced domain structures and polarization switching in the smallest amino acid β-glycine, representing a broad class of non-centrosymmetric amino acids. We show that β-glycine is indeed a room-temperature ferroelectric and polarization can be switched by applying a bias to non-polar cuts via a conducting tip of atomic force microscope (AFM). Dynamics of these in-plane domains is studied as a function of an applied voltage and pulse duration. The domain shape is dictated by polarization screening at the domain boundaries and mediated by growth defects. Thermodynamic theory is applied to explain the domain propagation induced by the AFM tip. Our findings suggest that the properties of β-glycine are controlled by the charged domain walls which in turn can be manipulated by an external bias.

  7. Tip-induced domain structures and polarization switching in ferroelectric amino acid glycine

    International Nuclear Information System (INIS)

    Bioorganic ferroelectrics and piezoelectrics are becoming increasingly important in view of their intrinsic compatibility with biological environment and biofunctionality combined with strong piezoelectric effect and a switchable polarization at room temperature. Here, we study tip-induced domain structures and polarization switching in the smallest amino acid β-glycine, representing a broad class of non-centrosymmetric amino acids. We show that β-glycine is indeed a room-temperature ferroelectric and polarization can be switched by applying a bias to non-polar cuts via a conducting tip of atomic force microscope (AFM). Dynamics of these in-plane domains is studied as a function of an applied voltage and pulse duration. The domain shape is dictated by polarization screening at the domain boundaries and mediated by growth defects. Thermodynamic theory is applied to explain the domain propagation induced by the AFM tip. Our findings suggest that the properties of β-glycine are controlled by the charged domain walls which in turn can be manipulated by an external bias

  8. Neutron spin structure with polarized deuterons and spectator proton tagging at EIC

    CERN Document Server

    Cosyn, W; Higinbotham, D W; Hyde, C; Kuhn, S; Nadel-Turonski, P; Park, K; Sargsian, M; Strikman, M; Weiss, C

    2014-01-01

    The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x << 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < p_R < several 100 MeV in the nucleus rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We revie...

  9. Anisotropic lattice response induced by a linearly-polarized femtosecond optical pulse excitation in interfacial phase change memory material

    Science.gov (United States)

    Makino, Kotaro; Saito, Yuta; Fons, Paul; Kolobov, Alexander V.; Nakano, Takashi; Tominaga, Junji; Hase, Muneaki

    2016-01-01

    Optical excitation of matter with linearly-polarized femtosecond pulses creates a transient non-equilibrium lattice displacement along a certain direction. Here, the pump and probe pulse polarization dependence of the photo-induced ultrafast lattice dynamics in (GeTe)2/(Sb2Te3)4 interfacial phase change memory material is investigated under obliquely incident conditions. Drastic pump polarization dependence of the coherent phonon amplitude is observed when the probe polarization angle is parallel to the c-axis of the sample, while the pump polarization dependence is negligible when the probe polarization angle is perpendicular to the c-axis. The enhancement of phonon oscillation amplitude due to pump polarization rotation for a specific probe polarization angle is only found in the early time stage (≤2 ps). These results indicate that the origin of the pump and probe polarization dependence is dominantly attributable to the anisotropically-formed photo-excited carriers which cause the directional lattice dynamics.

  10. Polarization of modified titanium and titanium–zirconium creates nano-structures while hydride formation is modulated

    Energy Technology Data Exchange (ETDEWEB)

    Frank, Matthias J.; Walter, Martin S. [Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, PO Box 1109 Blindern, NO-0317 Oslo (Norway); Institute of Medical and Polymer Engineering, Chair of Medical Engineering, Technische Universität München, Boltzmannstrasse 15, D-85748 Garching (Germany); Bucko, Miroslaw M. [Department of Ceramics and Refractory Materials, Faculty of Materials Science and Ceramics, AGH University of Science and Technology, Al Mickiewicza 30, 30-059 Krakow (Poland); Pamula, Elzbieta [Department of Biomaterials, Faculty of Materials Science and Ceramics, AGH University of Science and Technology, Al Mickiewicza 30, 30-059 Krakow (Poland); Lyngstadaas, S. Petter [Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, PO Box 1109 Blindern, NO-0317 Oslo (Norway); Haugen, Håvard J., E-mail: h.j.haugen@odont.uio.no [Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, PO Box 1109 Blindern, NO-0317 Oslo (Norway)

    2013-10-01

    The majority of titanium based bone-level dental implants available on the market today feature a sand-blasted and acid-etched (SBAE) surface that contains comparably high hydrogen levels. Cathodic polarization of titanium in acidic solutions is known to further increase titanium hydride on the surface. The aim of this study was to explore the effect of cathodic reduction on titanium (Ti) and titanium–zirconium (TiZr) with a SBAE surface in order to investigate the potential of such a process for further improving surfaces for bone anchored dental implants. Samples of both materials were cathodically polarized in acidic solution at different current densities and for different process times. Chemical analysis of the hydrogen levels by SIMS showed that cathodic reduction re-arranged the hydride already present on the surfaces from the etching process but could not significantly increase hydride levels. The hydrogen layer created by the preceding hot acid etching appeared to modulate further hydride creation. Analysis of the surface topography by SEM showed changes to the nano-topography of both materials after polarization. TiZr showed homogeneously distributed nano-spheres as they were already observed for TiZr SBAE at increased size of 80–100 nm on the whole surface. By contrast, polarization of Ti created nano-nodules and nano-spheres of 150–200 nm on the surface. These spheres were interconnected to form flower-like structures along the ridges and peaks of the surface. Moreover the flanks were covered by a rippled structure of isotropically distributed small-diameter (10–20 nm) nano-nodules.

  11. Plasmonic structure integrated single-photon detectors optimized to maximize polarization contrast

    CERN Document Server

    Csete, M; Maraczi, D; Banhelyi, B; Csendes, T; Szabo, G

    2016-01-01

    Numerical optimization was performed via COMSOL Multiphysics to maximize the polarization contrast of superconducting nanowire single photon detectors (SNSPDs). SNSPDs were integrated with four different types of one-dimensional periodic plasmonic structures capable of mediating p-polarized photon selectivity to the niobium-nitride superconducting nanowire pattern. Optimization with two different criteria regarding the maximal tilting resulted in wavelength-scaled periodic integrated structures, which have different geometrical parameters, and exhibit different polar angle dependent optical response and dispersion characteristics, as well as accompanying near-field phenomena at the extrema. Polarization contrast of 6.37*10^2 and 3.28*10^2 - 6.86*10^11 and 1.42*10^11 - 1.81*10^13 and 7.87*10^12 - 1.90*10^3 and 1.15*10^5 can be achieved in nanocavity-, nanocavity-deflector-, nanocavity-double-deflector-, nanocavity-trench-array-integrated P-SNSPDs optimized with 85 degree and 80 degree criterion regarding the m...

  12. Structural analysis of polarizing indels: an emerging consensus on the root of the tree of life

    Directory of Open Access Journals (Sweden)

    Bourne Philip E

    2009-08-01

    Full Text Available Abstract Background The root of the tree of life has been a holy grail ever since Darwin first used the tree as a metaphor for evolution. New methods seek to narrow down the location of the root by excluding it from branches of the tree of life. This is done by finding traits that must be derived, and excluding the root from the taxa those traits cover. However the two most comprehensive attempts at this strategy, performed by Cavalier-Smith and Lake et al., have excluded each other's rootings. Results The indel polarizations of Lake et al. rely on high quality alignments between paralogs that diverged before the last universal common ancestor (LUCA. Therefore, sequence alignment artifacts may skew their conclusions. We have reviewed their data using protein structure information where available. Several of the conclusions are quite different when viewed in the light of structure which is conserved over longer evolutionary time scales than sequence. We argue there is no polarization that excludes the root from all Gram-negatives, and that polarizations robustly exclude the root from the Archaea. Conclusion We conclude that there is no contradiction between the polarization datasets. The combination of these datasets excludes the root from every possible position except near the Chloroflexi. Reviewers This article was reviewed by Greg Fournier (nominated by J. Peter Gogarten, Purificación López-García, and Eugene Koonin.

  13. Atomic structure of defects in GaN:Mg grown with Ga polarity

    International Nuclear Information System (INIS)

    Electron microscope phase images, produced by direct reconstruction of the scattered electron wave from a focal series of high-resolution images, were used to determine the nature of defects formed in GaN:Mg crystals. We studied bulk crystals grown from dilute solutions of atomic nitrogen in liquid gallium at high pressure and thin films grown by the MOCVD method. All the crystals were grown with Ga-polarity. In both types of samples the majority of defects were three dimensional Mg-rich hexagonal pyramids with bases on the (0001) plane and six walls on {11(und 2)3} planes seen in cross-section as triangulars. Some other defects appear in cross-section as trapezoidal (rectangular) defects as a result of presence of truncated pyramids. Both type of defects have hollow centers. They are decorated by Mg on all six side walls and a base. The GaN which grows inside on the defect walls shows polarity inversion. It is shown that change of polarity starts from the defect tip and propagates to the base, and that the stacking sequence changes from ab in the matrix to bc inside the defect. Exchange of the Ga sublattice with the N sublattice within the defect leads to 0.6 ± 0.2(angstrom) displacement between Ga sublattices outside and inside the defects. It is proposed that lateral overgrowth of the cavities formed within the defect takes place to restore matrix polarity on the defect base

  14. A Change in the Optical Polarization Associated with a Gamma-Ray Flare in the Blazar 3C 279

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, A.A.

    2011-08-19

    It is widely accepted that strong and variable radiation detected over all accessible energy bands in a number of active galaxies arises from a relativistic, Doppler-boosted jet pointing close to our line of sight. The size of the emitting zone and the location of this region relative to the central supermassive black hole are, however, poorly known, with estimates ranging from light-hours to a light-year or more. Here we report the coincidence of a gamma ({gamma})-ray flare with a dramatic change of optical polarization angle. This provides evidence for co-spatiality of optical and {gamma}-ray emission regions and indicates a highly ordered jet magnetic field. The results also require a non-axisymmetric structure of the emission zone, implying a curved trajectory for the emitting material within the jet, with the dissipation region located at a considerable distance from the black hole, at about 10{sup 5} gravitational radii.

  15. Tracking Changes in Cardiac Output: Statistical Considerations on the 4-Quadrant Plot and the Polar Plot Methodology.

    Science.gov (United States)

    Saugel, Bernd; Grothe, Oliver; Wagner, Julia Y

    2015-08-01

    When comparing 2 technologies for measuring hemodynamic parameters with regard to their ability to track changes, 2 graphical tools are omnipresent in the literature: the 4-quadrant plot and the polar plot recently proposed by Critchley et al. The polar plot is thought to be the more advanced statistical tool, but care should be taken when it comes to its interpretation. The polar plot excludes possibly important measurements from the data. The polar plot transforms the data nonlinearily, which may prevent it from being seen clearly. In this article, we compare the 4-quadrant and the polar plot in detail and thoroughly describe advantages and limitations of each. We also discuss pitfalls concerning the methods to prepare the researcher for the sound use of both methods. Finally, we briefly revisit the Bland-Altman plot for the use in this context.

  16. Single-molecule fluorescence polarization study of conformational change in archaeal group II chaperonin.

    Directory of Open Access Journals (Sweden)

    Ryo Iizuka

    Full Text Available Group II chaperonins found in archaea and in eukaryotic cytosol mediate protein folding without a GroES-like cofactor. The function of the cofactor is substituted by the helical protrusion at the tip of the apical domain, which forms a built-in lid on the central cavity. Although many studies on the change in lid conformation coupled to the binding and hydrolysis of nucleotides have been conducted, the molecular mechanism of lid closure remains poorly understood. Here, we performed a single-molecule polarization modulation to probe the rotation of the helical protrusion of a chaperonin from a hyperthermophilic archaeum, Thermococcus sp. strain KS-1. We detected approximately 35° rotation of the helical protrusion immediately after photorelease of ATP. The result suggests that the conformational change from the open lid to the closed lid state is responsible for the approximately 35° rotation of the helical protrusion.

  17. Structural Changes in Serbian Industry during Transition

    Directory of Open Access Journals (Sweden)

    Ivan Nikolić

    2013-07-01

    Full Text Available Transition is a complex process whereby a country in transition is stimulating structural changes wishing to achieve economic growth and improved social wellbeing. In this paper the authors aim to show that during transition in Serbia there such changes in the structure of manufacturing industry occurred, which resulted with only modest ​​growth that in fact was slower than in other transitional countries. By the means of theoretical and empirical approach – deductive methods, statistical and mathematical evaluation the authors have come to conclusion that structural changes did not improve industry branches like the hi-tech industry that contribute the most to PPP generation. At the same time, some low productive industries have gained on importance, therefore keeping the standard on the low levels without possibility to rapidly converge towards EU average, which was set as an ultimate goal of transition in Serbia.

  18. A Web-Based Polar Firn Model to Motivate Interest in Climate Change

    Science.gov (United States)

    Harris, P. D.; Lundin, J.; Stevens, C.; Leahy, W.; Waddington, E. D.

    2013-12-01

    How long would you have to dig straight down in Greenland before you reached solid ice? This is one of many questions that could be answered by a typical high school student using our online firn model. Firn is fallen snow that compacts under its own weight and eventually turns into glacial ice. The Herron and Langway (1980) firn model describes this process. An important component of predicting future climate change is researching past climate change. Some details of our past climate are discovered by analyzing polar ice and the firn process. Firn research can also be useful for understanding how changes in ice surface levels reflect changes in the ice mass. We have produced an online version of the Herron and Langway model that provides a simple way for students to learn how polar snow turns into ice. As a user, you can enter some climatic conditions (accumulation rate, temperature, and surface density) into our graphical user interface and press 'Submit'. We take the numbers you enter in your internet browser, send them to the model written in Python that is running on our server, and provide links to your results, all within seconds. The model produces firn depth, density, and age data. The results appear on the webpage in both text and graphical format. We have developed an example lesson plan appropriate for a high-school physics or environmental science class. The online model offers students an opportunity to apply their scientific knowledge in order to understand real-world physical processes. Additionally, students learn about scientific research and the tools scientists use to conduct it. The model can be used as a standalone lesson or as a part of a larger climate-science unit. The online model was created with funding from the Washington NASA Space Grant Consortium and the National Science Foundation's Partnerships for International Research and Education program.

  19. Security Authentication using Phase-Encoded Nanoparticle Structures and Polarized Light

    OpenAIRE

    Carnicer González, Arturo; Hassanfiroozi, Amir; Latorre-Carmona, Pedro; Huang, Yi-Pai; Javidi, Bahram

    2015-01-01

    Phase encoded nano structures such as Quick Response (QR) codes made of metallic nanoparticles are suggested to be used in security and authentication applications. We present a polarimetric optical method able to authenticate random phase encoded QR codes. The system is illuminated using polarized light and the QR code is encoded using a phase-only random mask. Using classification algorithms it is possible to validate the QR code from the examination of the polarimetric signature of the spe...

  20. Analysis of local structure of Arg10 domain in apo-α- lactalbumin with a polarity-sensitive arginine-specific fluorescent probe

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The polarity-sensitive fluorescent probe, 3-(4-chloro-6-p-glyoxalphenoxy-1,3,5-triazinylamino)-7- (dimethylamino)-2-methylphenazine, was used to analyze the local structure of apo-α-lactalbumin by detecting the polarity and conformational changes of the arginine residue (Arg10) domain. The polarity of the Arg10 domain in both native and heat-denatured apo-α-lactalbumin was determined, which corresponds to a dielectric constant of 16, and the hydrophobic core near the Arg10 was found to be conservative for heating. Meanwhile, the effect of Ca2+ binding on the conformational changes of the Arg10 domain was studied, revealing that the hydrophobic core near the Arg10 is insensitive to the binding of Ca2+.

  1. Structural change and industrial policy in Turkey

    OpenAIRE

    Atiyas, İzak; Atiyas, Izak; Bakış, Ozan; Bakis, Ozan

    2013-01-01

    This paper presents evidence on structural change in Turkey and provides an overview of the evolution of industrial policy in the last three decades. We show that Turkey has experienced substantial growth in labor productivity in the last decade and that this has been associated with substantial change in the composition of value added and employment both in the overall economy and within the manufacturing industry. Using sectoral national accounts data we decompose aggregate productivity g...

  2. Estimating Structural Change in Linear Simultaneous Equations

    OpenAIRE

    Huang Weihong; Zhang Yang

    2004-01-01

    Tests and estimation for changes in the coefficients of linear regression models, particularly the analysis of covariance and the Chow tests, are well known to econometricians and are widely used. This paper demonstrates that analogous estimation can also be constructed in simultaneous equation models when equations are estimated by common estimator like OLS, 2SLS and LIML. In the present paper, we discuss the problem of estimating structural changes in equations from a simultaneous structura...

  3. A structure for quasars under the scope of polarization - I. The UV/optical polarization dichotomy of type-1 and type-2 AGN

    Science.gov (United States)

    Marin, F.; Goosmann, R. W.

    2013-12-01

    We present ultraviolet/optical spectropolarimetric modelling of the phenomenologically based structure for quasars proposed by Elvis (2000). In this first paper of a series, we explore the continuum polarization emerging from radiatively accelerated and bent winds that were vertically launched from the accretion disc in an active galactic nucleus (AGN). We simulate the radiative transfer occurring in Thomson scattering and dust extinction media over a range of morphological parameters and optical depths of the wind. We demonstrate that the wind geometry proposed by Elvis with a phenomenologically derived bending angle of θ = 60° still underestimates the observed optical polarization percentage of type-1 and type-2 AGN and does not yet reproduce the expected dichotomy of the polarization position angle. To recover the observed polarization properties, a smaller bending angle and some amount of dust shielding in the equatorial region should be considered. A two-phase outflow is found to generate both the observed polarization dichotomy and acceptable levels of polarization degree if the wind has a bending angle θ = 45°, and the conical shells have a half-opening angle of 3° < δθ < 10°. The absorbing dust column at the wind base should be in the range 1 < τdust ≤ 4 (τ being integrated over 2000-8000 Å). Straightforward observational tests from spectropolarimetry and from determining the number density of different AGN types can be performed to further constrain the wind geometry.

  4. Plasmonic Structure Integrated Single-Photon Detector Configurations to Improve Absorptance and Polarization Contrast

    Directory of Open Access Journals (Sweden)

    Mária Csete

    2015-02-01

    Full Text Available Configurations capable of maximizing both the absorption component of system detection efficiency and the achievable polarization contrast were determined for 1550 nm polarized light illumination of different plasmonic structure integrated superconducting nanowire single-photon detectors (SNSPDs consisting of p = 264 nm and P = 792 nm periodic niobium nitride (NbN patterns on silica substrate. Global effective NbN absorptance maxima appear in case of p/s-polarized light illumination in S/P-orientation (γ = 90°/0° azimuthal angle and the highest polarization contrast is attained in S-orientation of all devices. Common nanophotonical origin of absorptance enhancement is collective resonance on nanocavity gratings with different profiles, which is promoted by coupling between localized modes in quarter-wavelength metal-insulator-metal nanocavities and laterally synchronized Brewster-Zenneck-type surface waves in integrated SNSPDs possessing a three-quarter-wavelength-scaled periodicity. The spectral sensitivity and dispersion characteristics reveal that device design specific optimal configurations exist.

  5. The Effects of Instrumental Elliptical Polarization on Stellar Point Spread Function Fine Structure

    Science.gov (United States)

    Carson, Joseph C.; Kern, Brian D.; Breckinridge, James B.; Trauger, John T.

    2005-01-01

    We present procedures and preliminary results from a study on the effects of instrumental polarization on the fine structure of the stellar point spread function (PSF). These effects are important to understand because the the aberration caused by instrumental polarization on an otherwise diffraction-limited will likely have have severe consequences for extreme high contrast imaging systems such as NASA's planned Terrestrial Planet Finder (TPF) mission and the proposed NASA Eclipse mission. The report here, describing our efforts to examine these effects, includes two parts: 1) a numerical analysis of the effect of metallic reflection, with some polarization-specific retardation, on a spherical wavefront; 2) an experimental approach for observing this effect, along with some preliminary laboratory results. While the experimental phase of this study requires more fine-tuning to produce meaningful results, the numerical analysis indicates that the inclusion of polarization-specific phase effects (retardation) results in a point spread function (PSF) aberration more severe than the amplitude (reflectivity) effects previously recorded in the literature.

  6. Structure and dynamics of a dizinc metalloprotein: effect of charge transfer and polarization.

    Science.gov (United States)

    Li, Yong L; Mei, Ye; Zhang, Da W; Xie, Dai Q; Zhang, John Z H

    2011-08-25

    Structures and dynamics of a recently designed dizinc metalloprotein (DFsc) (J. Mol. Biol. 2003, 334, 1101) are studied by molecular dynamics simulation using a dynamically adapted polarized force field derived from fragment quantum calculation for protein in solvent. To properly describe the effect of charge transfer and polarization in the present approach, quantum chemistry calculation of the zinc-binding group is periodically performed (on-the-fly) to update the atomic charges of the zinc-binding group during the MD simulation. Comparison of the present result with those obtained from simulations under standard AMBER force field reveals that charge transfer and polarization are critical to maintaining the correct asymmetric metal coordination in the DFsc. Detailed analysis of the result also shows that dynamic fluctuation of the zinc-binding group facilitates solvent interaction with the zinc ions. In particular, the dynamic fluctuation of the zinc-zinc distance is shown to be an important feature of the catalytic function of the di-ion zinc-binding group. Our study demonstrates that the dynamically adapted polarization approach is computationally practical and can be used to study other metalloprotein systems.

  7. Polar and brown bear genomes reveal ancient admixture and demographic footprints of past climate change

    Science.gov (United States)

    Miller, Webb; Schuster, Stephan C.; Welch, Andreanna J.; Ratan, Aakrosh; Bedoya-Reina, Oscar C.; Zhao, Fangqing; Kim, Hie Lim; Burhans, Richard C.; Drautz, Daniela I.; Wittekindt, Nicola E.; Tomsho, Lynn P.; Ibarra-Laclette, Enrique; Herrera-Estrella, Luis; Peacock, Elizabeth; Farley, Sean; Sage, George K.; Rode, Karyn; Obbard, Martyn E.; Montiel, Rafael; Bachmann, Lutz; Ingólfsson, Ólafur; Aars, Jon; Mailund, Thomas; Wiig, Øystein; Talbot, Sandra L.; Lindqvist, Charlotte

    2012-01-01

    Polar bears (PBs) are superbly adapted to the extreme Arctic environment and have become emblematic of the threat to biodiversity from global climate change. Their divergence from the lower-latitude brown bear provides a textbook example of rapid evolution of distinct phenotypes. However, limited mitochondrial and nuclear DNA evidence conflicts in the timing of PB origin as well as placement of the species within versus sister to the brown bear lineage. We gathered extensive genomic sequence data from contemporary polar, brown, and American black bear samples, in addition to a 130,000- to 110,000-y old PB, to examine this problem from a genome-wide perspective. Nuclear DNA markers reflect a species tree consistent with expectation, showing polar and brown bears to be sister species. However, for the enigmatic brown bears native to Alaska's Alexander Archipelago, we estimate that not only their mitochondrial genome, but also 5–10% of their nuclear genome, is most closely related to PBs, indicating ancient admixture between the two species. Explicit admixture analyses are consistent with ancient splits among PBs, brown bears and black bears that were later followed by occasional admixture. We also provide paleodemographic estimates that suggest bear evolution has tracked key climate events, and that PB in particular experienced a prolonged and dramatic decline in its effective population size during the last ca. 500,000 years. We demonstrate that brown bears and PBs have had sufficiently independent evolutionary histories over the last 4–5 million years to leave imprints in the PB nuclear genome that likely are associated with ecological adaptation to the Arctic environment.

  8. Neural coding of image structure and contrast polarity of Cartesian, hyperbolic, and polar gratings in the primary and secondary visual cortex of the tree shrew.

    Science.gov (United States)

    Poirot, Jordan; De Luna, Paolo; Rainer, Gregor

    2016-04-01

    We comprehensively characterize spiking and visual evoked potential (VEP) activity in tree shrew V1 and V2 using Cartesian, hyperbolic, and polar gratings. Neural selectivity to structure of Cartesian gratings was higher than other grating classes in both visual areas. From V1 to V2, structure selectivity of spiking activity increased, whereas corresponding VEP values tended to decrease, suggesting that single-neuron coding of Cartesian grating attributes improved while the cortical columnar organization of these neurons became less precise from V1 to V2. We observed that neurons in V2 generally exhibited similar selectivity for polar and Cartesian gratings, suggesting that structure of polar-like stimuli might be encoded as early as in V2. This hypothesis is supported by the preference shift from V1 to V2 toward polar gratings of higher spatial frequency, consistent with the notion that V2 neurons encode visual scene borders and contours. Neural sensitivity to modulations of polarity of hyperbolic gratings was highest among all grating classes and closely related to the visual receptive field (RF) organization of ON- and OFF-dominated subregions. We show that spatial RF reconstructions depend strongly on grating class, suggesting that intracortical contributions to RF structure are strongest for Cartesian and polar gratings. Hyperbolic gratings tend to recruit least cortical elaboration such that the RF maps are similar to those generated by sparse noise, which most closely approximate feedforward inputs. Our findings complement previous literature in primates, rodents, and carnivores and highlight novel aspects of shape representation and coding occurring in mammalian early visual cortex. PMID:26843607

  9. Fostering science communication and outreach through video production in Dartmouth's IGERT Polar Environmental Change graduate program

    Science.gov (United States)

    Hammond Wagner, C. R.; McDavid, L. A.; Virginia, R. A.

    2013-12-01

    Dartmouth's NSF-supported IGERT Polar Environmental Change graduate program has focused on using video media to foster interdisciplinary thinking and to improve student skills in science communication and public outreach. Researchers, educators, and funding organizations alike recognize the value of video media for making research results more accessible and relevant to diverse audiences and across cultures. We present an affordable equipment set and the basic video training needed as well as available Dartmouth institutional support systems for students to produce outreach videos on climate change and its associated impacts on people. We highlight and discuss the successes and challenges of producing three types of video products created by graduate and undergraduate students affiliated with the Dartmouth IGERT. The video projects created include 1) graduate student profile videos, 2) a series of short student-created educational videos for Greenlandic high school students, and 3) an outreach video about women in science based on the experiences of women students conducting research during the IGERT field seminar at Summit Station and Kangerlussuaq, Greenland. The 'Science in Greenland--It's a Girl Thing' video was featured on The New York Times Dot Earth blog and the Huffington Post Green blog among others and received international recognition. While producing these videos, students 1) identified an audience and created story lines, 2) worked in front of and behind the camera, 3) utilized low-cost digital editing applications, and 4) shared the videos on multiple platforms from social media to live presentations. The three video projects were designed to reach different audiences, and presented unique challenges for content presentation and dissemination. Based on student and faculty assessment, we conclude that the video projects improved student science communication skills and increased public knowledge of polar science and the effects of climate change.

  10. Entrepreneurship, structural change, and economic growth

    NARCIS (Netherlands)

    Noseleit, Florian

    2013-01-01

    The ability to adjust to structural change is vital to economic development, and entries can be active participants in this process. While the importance of factor reallocations for growth is widely discussed, the role of entrepreneurs in managing these reallocations is currently not well understood

  11. Migraine and structural changes in the brain

    DEFF Research Database (Denmark)

    Bashir, Asma; Lipton, Richard B; Ashina, Sait;

    2013-01-01

    To evaluate the association between migraine without aura (MO) and migraine with aura (MA) and 3 types of structural brain abnormalities detected by MRI: white matter abnormalities (WMAs), infarct-like lesions (ILLs), and volumetric changes in gray and white matter (GM, WM) regions....

  12. Polarity and structure peculiarities of trialkylphosphine oxides, sulfides, selenides and tellurides

    International Nuclear Information System (INIS)

    Using the quantum-chemical calculations structural characteristics of trialkylphosphine oxides, sulfates, selenides and tellurides (Alk3P=X; X O, S, Se, Te) are obtained, which are in good agreement with literature X-ray structural analysis and gas-phase electron diffraction data. The P=X bonds polarity is determined in the framework of vector-additive scheme on the base of experimental data on components dipole moments and using different base series of molecules geometry parameters. It is shown that increasing of bond moment P=X in the X = O, S, Se, Te series takes place through dipole length increasing

  13. Extensive photometry of the intermediate polar MU Cam: detection of a spin period change

    CERN Document Server

    Kozhevnikov, V P

    2016-01-01

    Intermediate polars with known rates of spin period changes are not numerous because such tasks require measurements performed for a long time. To measure a spin period change, MU Cam is a good candidate because it has a spin oscillation with a large amplitude enabling measurements with high precision. Fortunately, in the past the spin period of MU Cam was measured with high precision. To measure the spin period anew, in 2014-2015 we performed extensive photometric observations of MU Cam, spanning a total duration of 208 h within 46 nights. We found that the spin, sideband and orbital periods are equal to 1187.16245+/-0.00047 s, 1276.3424+/-0.0022 s and 4.71942+/-0.00016 h, respectively. Comparing the measured spin period with the spin period of MU Cam in the past, we detected the spin period change with dP/dt=-(2.17+/-0.10) X 10^(-10). This rate of the spin period change was not stable and varied in a time scale of years. During four nights in 2014 April-May MU Cam was fainter than usual by 0.8 mag, and the ...

  14. The electronic structure of spintronic materials as seen by spin-polarized angle-resolved photoemission

    Energy Technology Data Exchange (ETDEWEB)

    Plucinski, L., E-mail: l.plucinski@fz-juelich.de [Peter Grünberg Institute PGI-6, Forschungszentrum Jülich, D-52425 Jülich (Germany); Fakultät f. Physik, Universität Duisburg-Essen, D-47057 Duisburg (Germany); Schneider, C.M. [Peter Grünberg Institute PGI-6, Forschungszentrum Jülich, D-52425 Jülich (Germany); Fakultät f. Physik, Universität Duisburg-Essen, D-47057 Duisburg (Germany)

    2013-08-15

    Highlights: •Introduction of spin-dependent effects in modern angle-resolved photoemission from the point of view of potential applications in spintronics. •Review on modern spin-polarimeters, including the historical development of the field. •Several examples to illustrate the application of spin-polarized photoemission to ferromagnetic and non-ferromagnetic sample systems. -- Abstract: The key quantity in spintronic devices is the spin polarization of the current flowing through the various device components, which in turn is closely determined by the components’ electronic structure. Modern spin- and angle-resolved photoemission spectroscopy (spin-ARPES) can map the details of the spin-polarized electronic structure in many novel material systems – both magnetic and nonmagnetic. In order to separate close-lying electronic states, however, an improvement in energy and angular resolution as well as information depth is still mandatory. We review several types of modern photoemission spectrometers capable of spin analysis and discuss the application of the technique for several physical systems including ferromagnetic thin films and topological insulators.

  15. Far-field radially polarized focal spot from plasmonic spiral structure combined with central aperture antenna

    Science.gov (United States)

    Mao, Lei; Ren, Yuan; Lu, Yonghua; Lei, Xinrui; Jiang, Kang; Li, Kuanguo; Wang, Yong; Cui, Chenjing; Wen, Xiaolei; Wang, Pei

    2016-03-01

    Manipulation of a vector micro-beam with an optical antenna has significant potentials for nano-optical technology applications including bio-optics, optical fabrication, and quantum information processing. We have designed and demonstrated a central aperture antenna within an Archimedean spiral that extracts the bonding plasmonic field from a surface to produce a new vector focal spot in far-field. The properties of this vector focal field are revealed by confocal microscopy and theoretical simulations. The pattern, polarization and phase of the focal field are determined by the incident light and by the chirality of the Archimedean spiral. For incident light with right-handed circular polarization, the left-handed spiral (one-order chirality) outputs a micro-radially polarized focal field. Our results reveal the relationship between the near-field and far-field distributions of the plasmonic spiral structure, and the structure has the potential to lead to advances in diverse applications such as plasmonic lenses, near-field angular momentum detection, and optical tweezers.

  16. Linear polarization structures in LOFAR observations of the interstellar medium in the 3C196 field

    CERN Document Server

    Jelić, V; Pandey, V N; Mevius, M; Haverkorn, M; Brentjens, M A; Koopmans, L V E; Zaroubi, S; Abdalla, F B; Asad, K M B; Bus, S; Chapman, E; Ciardi, B; Fernandez, E R; Ghosh, A; Harker, G; Iliev, I T; Jensen, H; Kazemi, S; Mellema, G; Offringa, A R; Patil, A H; Vedantham, H K; Yatawatta, S

    2015-01-01

    This study aims to characterise linear polarization structures in LOFAR observations of the interstellar medium (ISM) in the 3C196 field, one of the primary fields of the LOFAR-Epoch of Reionization key science project. We have used the high band antennas (HBA) of LOFAR to image this region and RM-synthesis to unravel the distribution of polarized structures in Faraday depth. The brightness temperature of the detected Galactic emission is $5-15~{\\rm K}$ in polarized intensity and covers the range from -3 to +8 ${\\rm rad~m^{-2}}$ in Faraday depth. The most interesting morphological feature is a strikingly straight filament at a Faraday depth of $+0.5~{\\rm rad~m^{-2}}$ running from north to south, right through the centre of the field and parallel to the Galactic plane. There is also an interesting system of linear depolarization canals conspicuous in an image showing the peaks of Faraday spectra. We have used the Westerbork Synthesis Radio Telescope (WSRT) at 350 MHz to image the same region. For the first tim...

  17. Space and time aliasing structure is monthly mean polar-orbiting satellite data

    Science.gov (United States)

    Zeng, Lixin; Levy, Gad

    1995-01-01

    Monthly mean wind fields from the European Remote Sensing Satellite (ERS1) scatterometer are presented. A banded structure which resembles the satellite subtrack is clearly and consistently apparent in the isotachs as well as the u and v components of the routinely produced fields. The structure also appears in the means of data from other polar-orbiting satellites and instruments. An experiment is designed to trace the cause of the banded structure. The European Centre for Medium-Range Weather Forecast (ECMWF) gridded surface wind analyses are used as a control set. These analyses are also sampled with the ERS1 temporal-spatial samplig pattern to form a simulated scatterometer wind set. Both sets are used to create monthly averages. The banded structures appear in the monthly mean simulated data but do not appear in the control set. It is concluded that the source of the banded structure lies in the spatial and temporal sampling of the polar-orbiting satellite which results in undersampling. The problem involves multiple timescales and space scales, oversampling and under-sampling in space, aliasing in the time and space domains, and preferentially sampled variability. It is shown that commonly used spatial smoothers (or filters), while producing visually pleasing results, also significantly bias the true mean. A three-dimensional spatial-temporal interpolator is designed and used to determine the mean field. It is found to produce satisfactory monthly means from both simulated and real ERS1 data. The implications to climate studies involving polar-orbiting satellite data are discussed.

  18. Polarizing properties and structural characteristics of the cuticle of the scarab Beetle Chrysina gloriosa

    Energy Technology Data Exchange (ETDEWEB)

    Fernández del Río, Lía, E-mail: liafe@ifm.liu.se; Arwin, Hans; Järrendahl, Kenneth

    2014-11-28

    The scarab beetle Chrysina gloriosa is green with gold-colored stripes along its elytras. The properties of light reflected on these areas are investigated using Mueller-matrix spectroscopic ellipsometry. Both areas reflect light with high degree of left-handed polarization but this effect occurs for specular reflection for the gold-colored areas and for off-specular angles for the green areas. The colors and polarization phenomena originate from reflection of light in the cuticle and a structural analysis is presented to facilitate understanding of the different behaviors of these two areas. Scanning electron microscopy (SEM) images of the cross section of beetle cuticles show a multilayered structure. On the gold-colored areas the layers are parallel to the surface whereas on the green-colored areas they form cusp-like structures. Optical microscopy images show a rather flat surface in the gold-colored areas compared to the green-colored areas which display a net of polygonal cells with star-shaped cavities in the center. Each of the polygons corresponds to one of the cusps observed in the SEM images. Atomic force microscopy images of the star-shaped cavities are also provided. The roughness of the surface and the cusp-like structure of the green-colored areas are considered to cause scattering on this area. - Highlights: • Chrysina gloriosa reflects light with high degree of left-handed polarization. • Gold-colored areas are good specular reflectors whereas green-colored areas scatter light. • The cusp-like structure in the green areas is responsible for the scattering.

  19. Experimental results on polarized structure functions in deep inelastic lepton-nucleon scattering

    Energy Technology Data Exchange (ETDEWEB)

    Stuart, L.

    1994-08-01

    A summary is given of experimental results on spin structure functions of the proton g{sub 1}{sup p}(x,Q{sup 2}), deuteron g{sub 1}{sup d}(x,Q{sup 2}), and neutron g{sub 1}{sup n}(x,Q{sup 2}) as measured in deep inelastic scattering of polarized leptons from a polarized target. All results are consistent with the Bjorken sum rule predictions at the Q{sup 2} of each experiment. The data do not support the Ellis-Jaffe sum rule prediction for the proton which implies that the hencity carried by the strange quark may be nonzero and that the net quark helicity is smaller than expected from simple quark models.

  20. Structure-Function Study of Tertiary Amines as Switchable Polarity Solvents

    Energy Technology Data Exchange (ETDEWEB)

    Aaron D. Wilson; Frederick F. Stewart

    2014-02-01

    A series of tertiary amines have been screened for their function as switchable polarity solvents (SPS). The relative ratios of tertiary amine and carbonate species as well as maximum possible concentration were determined through quantitative 1H and 13C NMR spectroscopy. The viscosities of the polar SPS solutions were measured and ranged from near water in dilute systems through to gel formation at high concentrations. The van't Hoff indices for SPS solutions were measured through freezing point depression studies as a proxy for osmotic pressures. A new form of SPS with an amine : carbonate ratio significantly greater than unity has been identified. Tertiary amines that function as SPS at ambient pressures appear to be limited to molecules with fewer than 12 carbons. The N,N-dimethyl-n-alkylamine structure has been identified as important to the function of an SPS.

  1. Interdisciplinary Graduate Training in Polar Environmental Change: Field-based learning in Greenland

    Science.gov (United States)

    Virginia, R. A.; Holm, K.; Whitecloud, S.; Levy, L.; Kelly, M. A.; Feng, X.; Grenoble, L.

    2009-12-01

    The objective of the NSF-funded Integrative Graduate Education Research Traineeship (IGERT) program at Dartmouth College is to develop a new cohort of environmental scientists and engineers with an interdisciplinary understanding of polar regions and their importance to global environmental change. The Dartmouth IGERT challenges Ph.D. students to consider the broader dimensions of their research and to collaborate with scientists from other disciplines, educators, and policy makers. IGERT students will focus on research questions that are relevant to the needs of local people experiencing climate change and on understanding the ethical responsibilities and benefits of conducting research in partnership with northern residents and institutions. Seven Ph.D. students from the departments of Earth Sciences, Engineering, and Ecology and Evolutionary Biology at Dartmouth College make up the first IGERT cohort for the five-year program. The Dartmouth IGERT curriculum will focus on three main components of polar systems responding to recent climate change: the cryosphere, terrestrial ecosystems, and biogeochemical cycles. The integrating experience of the core curriculum is the Greenland Field Seminar that will take place in Kangerlussuaq (terrestrial and aquatic systems), Summit Camp (snow and ice) and Nuuk, Greenland (human dimensions of change). In Nuuk, IGERT students will share their science and develop partnerships with students, educators, and policy makers at the University of Greenland, the Inuit Circumpolar Council (ICC), and other Greenlandic institutions. In summer 2009 the authors conducted preliminary fieldwork near Kangerlussuaq, Greenland to develop aspects of the science curriculum for the 2010 Greenland Field Seminar and to explore research topics for IGERT Fellows (Levy and Whitecloud). Examples of results presented here are designed to develop field-based learning activities. These include soil and vegetation relationships as a function of aspect

  2. Reverse polarity magnetized melt rocks from the Chicxulub impact structure, Yucatan Peninsula, Mexico

    Science.gov (United States)

    Urrutia-Fucugauchi, Jaime; Marin, Luis E.; Sharpton, Virgil L.; Quezada, Juan Manuel

    1993-03-01

    Further paleomagnetic data for core samples of melt rock recovered in the Petroleos Mexicanos (PEMEX) exploratory wells within the Chicxulub structure, northern Yucatan peninsula, Mexico are reported. A previous report by Sharpton showed that the rocks studied contain high iridium levels and shocked breccia clasts, and an Ar-40/Ar-39 age of 65.2 plus or minus 0.4 Ma. The geomagnetic polarity determined for two samples is reverse (R) and was correlated with chron 29R that includes the K/T boundary. Our present analysis is based on two samples from each of three clasts of the melt rock from PEMEX well Y6-N17 (1295 to 1299 m b.s.l.). This study concentrates on the vectorial nature and stability of the remanence (NRM), the magnetic mineralogy and remanence carriers (i.e., the reliability and origin of the record), and on the implications (correlation with expected paleolatitude and polarity). The relative orientation of the drill core samples with respect to the horizontal is known. Samples were stable under alternating field (AF) and thermal treatments, and after removal of a small component they exhibited single-vectorial behavior. The characteristic remanence inclinations show small dispersion and a mean value (-43 deg) in close agreement with the expected inclination and paleolatitude (derived from the North American apparent polar wander path). Isothermal remenence (IRM) acquisition experiments, Lowrie-Fuller tests, coercivity and unblocking temperature spectra of NRM and saturation IRM, susceptibility and Q-coefficient analyses, and the single-component nature indicate a dominant mineralogy of iron-rich titanomagnetites with single or pseduo-single domain states. The stable characteristic magnetization may be interpreted as a result of shock heating of the rock at the time of formation of the inpact structure and its polarity, age, and paleolatitude are consistent with a time about the K/T boundary.

  3. Polarity correspondence in metaphor congruency effects: structural overlap predicts categorization times for bipolar concepts presented in vertical space.

    Science.gov (United States)

    Lakens, Daniël

    2012-05-01

    Previous research has shown that words presented on metaphor congruent locations (e.g., positive words UP on the screen and negative words DOWN on the screen) are categorized faster than words presented on metaphor incongruent locations (e.g., positive words DOWN and negative words UP). These findings have been explained in terms of an interference effect: The meaning associated with UP and DOWN vertical space can automatically interfere with the categorization of words with a metaphorically incongruent meaning. The current studies test an alternative explanation for the interaction between the vertical position of abstract concepts and the speed with which these stimuli are categorized. Research on polarity differences (basic asymmetries in the way dimensions are processed) predicts that +polar endpoints of dimensions (e.g., positive, moral, UP) are categorized faster than -polar endpoints of dimensions (e.g., negative, immoral, DOWN). Furthermore, the polarity correspondence principle predicts that stimuli where polarities correspond (e.g., positive words presented UP) provide an additional processing benefit compared to stimuli where polarities do not correspond (e.g., negative words presented UP). A meta-analysis (Study 1) shows that a polarity account provides a better explanation of reaction time patterns in previous studies than an interference explanation. An experiment (Study 2) reveals that controlling for the polarity benefit of +polar words compared to -polar words did not only remove the main effect of word polarity but also the interaction between word meaning and vertical position due to polarity correspondence. These results reveal that metaphor congruency effects should not be interpreted as automatic associations between vertical locations and word meaning but instead are more parsimoniously explained by their structural overlap in polarities.

  4. Changes to collagen structure during leather processing.

    Science.gov (United States)

    Sizeland, Katie H; Edmonds, Richard L; Basil-Jones, Melissa M; Kirby, Nigel; Hawley, Adrian; Mudie, Stephen; Haverkamp, Richard G

    2015-03-11

    As hides and skins are processed to produce leather, chemical and physical changes take place that affect the strength and other physical properties of the material. The structural basis of these changes at the level of the collagen fibrils is not fully understood and forms the basis of this investigation. Synchrotron-based small-angle X-ray scattering (SAXS) is used to quantify fibril orientation and D-spacing through eight stages of processing from fresh green ovine skins to staked dry crust leather. Both the D-spacing and fibril orientation change with processing. The changes in thickness of the leather during processing affect the fibril orientation index (OI) and account for much of the OI differences between process stages. After thickness is accounted for, the main difference in OI is due to the hydration state of the material, with dry materials being less oriented than wet. Similarly significant differences in D-spacing are found at different process stages. These are due also to the moisture content, with dry samples having a smaller D-spacing. This understanding is useful for relating structural changes that occur during different stages of processing to the development of the final physical characteristics of leather.

  5. Sensitivity of polar stratospheric cloud formation to changes in water vapour and temperature

    Science.gov (United States)

    Khosrawi, F.; Urban, J.; Lossow, S.; Stiller, G.; Weigel, K.; Braesicke, P.; Pitts, M. C.; Rozanov, A.; Burrows, J. P.; Murtagh, D.

    2016-01-01

    More than a decade ago it was suggested that a cooling of stratospheric temperatures by 1 K or an increase of 1 ppmv of stratospheric water vapour could promote denitrification, the permanent removal of nitrogen species from the stratosphere by solid polar stratospheric cloud (PSC) particles. In fact, during the two Arctic winters 2009/10 and 2010/11 the strongest denitrification in the recent decade was observed. Sensitivity studies along air parcel trajectories are performed to test how a future stratospheric water vapour (H2O) increase of 1 ppmv or a temperature decrease of 1 K would affect PSC formation. We perform our study based on measurements made during the Arctic winter 2010/11. Air parcel trajectories were calculated 6 days backward in time based on PSCs detected by CALIPSO (Cloud Aerosol Lidar and Infrared Pathfinder satellite observations). The sensitivity study was performed on single trajectories as well as on a trajectory ensemble. The sensitivity study shows a clear prolongation of the potential for PSC formation and PSC existence when the temperature in the stratosphere is decreased by 1 K and water vapour is increased by 1 ppmv. Based on 15 years of satellite measurements (2000-2014) from UARS/HALOE, Envisat/MIPAS, Odin/SMR, Aura/MLS, Envisat/SCIAMACHY and SCISAT/ACE-FTS it is further investigated if there is a decrease in temperature and/or increase of water vapour (H2O) observed in the polar regions similar to that observed at midlatitudes and in the tropics. Performing linear regression analyses we derive from the Envisat/MIPAS (2002-2012) and Aura/MLS (2004-2014) observations predominantly positive changes in the potential temperature range 350 to 1000 K. The linear changes in water vapour derived from Envisat/MIPAS observations are largely insignificant, while those from Aura/MLS are mostly significant. For the temperature neither of the two instruments indicate any significant changes. Given the strong inter-annual variation observed in

  6. Polarization-balanced design of heterostructures: Application to AlN/GaN double-barrier structures

    Science.gov (United States)

    Berland, Kristian; Andersson, Thorvald G.; Hyldgaard, Per

    2011-12-01

    Inversion and depletion regions generally form at the interfaces between doped leads (cladding layers) and the active region of polar heterostructures like AlN/GaN and other nitride compounds. The band bending in the depletion region sets up a barrier that may seriously impede perpendicular electronic transport. This may ruin the performance of devices such as quantum-cascade lasers and resonant-tunneling diodes. Here we introduce the concepts of polarization balance and polarization-balanced designs: A structure is polarization balanced when the applied bias match the voltage drop arising from spontaneous and piezeolectric fields. Devices designed to operate at this bias have polarization-balanced designs. These concepts offer a systematic approach to avoid the formation of depletion regions. As a test case, we consider the design of AlN/GaN double-barrier structures with Alx˜Ga1-x˜N leads. To guide our efforts, we derive a simple relation between the intrinsic voltage drop arising from polar effects, average alloy composition of the active region, and the alloy concentration of the leads. Polarization-balanced designs secure good filling of the ground state for unbiased structures, while for biased structures with efficient emptying of the active region they remove the depletion barriers.

  7. Inversion of single-station teleseismic P-wave polarization-data for the velocity structure of Beijing area

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Broadband three-component seismic data recorded by Beijingstation (BJI) of CDSN were used to calculate P-wave polarization of teleseismic events. These polarization data were then used in the inversion for the underground structure around the Beijing station, especially for the details of velocity discontinuities. The result shows that a conspicuous low velocity zone exists in the crust on the west of the station, which is in good agreement with previous studies. It proves the theory that polarization data could be applied to inversion for velocity structures, especially for boundaries with large velocity gradient. It also demonstrates the feasibility of velocity structure inversion with polarization data from high-quality broadband data recorded by a single station. Therefore, travel-times and polarization data can be jointly used to study velocity structure. Polarization data are more suitable for delineating the boundary of velocity anomalies. Moreover, if the polarization method is combined with receiver function method to fully exploit their complementarity, it is possible to obtain the lateral velocity variation around the station as well as the detailed vertical variation below the station.

  8. Structural Changes of Malt Proteins During Boiling

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available Changes in the physicochemical properties and structure of proteins derived from two malt varieties (Baudin and Guangmai during wort boiling were investigated by differential scanning calorimetry, SDS-PAGE, two-dimensional electrophoresis, gel filtration chromatography and circular dichroism spectroscopy. The results showed that both protein content and amino acid composition changed only slightly during boiling, and that boiling might cause a gradual unfolding of protein structures, as indicated by the decrease in surface hydrophobicity and free sulfhydryl content and enthalpy value, as well as reduced α-helix contents and markedly increased random coil contents. It was also found that major component of both worts was a boiling-resistant protein with a molecular mass of 40 kDa, and that according to the two-dimensional electrophoresis and SE-HPLC analyses, a small amount of soluble aggregates might be formed via hydrophobic interactions. It was thus concluded that changes of protein structure caused by boiling that might influence beer quality are largely independent of malt variety.

  9. Polarization Induced Changes in LSM Thin Film Electrode Composition Observed by In Operando Raman Spectroscopy and TOF-SIMS

    DEFF Research Database (Denmark)

    McIntyre, Melissa D.; Traulsen, Marie Lund; Norrman, Kion;

    2015-01-01

    Polarization induced changes in LSM electrode composition were investigated by utilizing in operando Raman spectroscopy and post mortem TOF-SIMS depth profiling. Experiments were conducted on cells with 160 nm thick (La0.85Sr0.15)0.9MnO3±δ thin film electrodes in 10% O2 at 700 °C under various......-surface region. Ex situ TOF-SIMS depth profiles were recorded through the LSM electrodes and revealed distinct compositional changes throughout the electrodes. The electrode elements and impurities separated into well-defined layers that were more stratified for stronger applied polarizations. The mechanism...

  10. PBX/extradenticle is required to re-establish axial structures and polarity during planarian regeneration.

    Science.gov (United States)

    Blassberg, Robert A; Felix, Daniel A; Tejada-Romero, Belen; Aboobaker, A Aziz

    2013-02-01

    Recent advances in a number of systems suggest many genes involved in orchestrating regeneration are redeployed from similar processes in development, with others being novel to the regeneration process in particular lineages. Of particular importance will be understanding the architecture of regenerative genetic regulatory networks and whether they are conserved across broad phylogenetic distances. Here, we describe the role of the conserved TALE class protein PBX/Extradenticle in planarians, a representative member of the Lophotrocozoa. PBX/Extradenticle proteins play central roles in both embryonic and post-embryonic developmental patterning in both vertebrates and insects, and we demonstrate a broad requirement during planarian regeneration. We observe that Smed-pbx has pleiotropic functions during regeneration, with a primary role in patterning the anterior-posterior (AP) axis and AP polarity. Smed-pbx is required for expression of polarity determinants notum and wnt1 and for correct patterning of the structures polarized along the AP axis, such as the brain, pharynx and gut. Overall, our data suggest that Smed-pbx functions as a central integrator of positional information to drive patterning of regeneration along the body axis. PMID:23318635

  11. The role of polar, lamdba (Λ)-shaped building units in noncentrosymmetric inorganic structures.

    Science.gov (United States)

    Donakowski, Martin D; Gautier, Romain; Yeon, Jeongho; Moore, Donald T; Nino, Juan C; Halasyamani, P Shiv; Poeppelmeier, Kenneth R

    2012-05-01

    A methodology for the design of polar, inorganic structures is demonstrated here with the packing of lambda (Λ)-shaped basic building units (BBUs). Noncentrosymmetric (NCS) solids with interesting physical properties can be created with BBUs that lack an inversion center and are likely to pack into a polar configuration; previous methods to construct these solids have used NCS octahedra as BBUs. Using this methodology to synthesize NCS solids, one must increase the coordination of the NCS octahedra with maintenance of the noncentrosymmetry of the bulk. The first step in this progression from an NCS octahedron to an inorganic NCS solid is the formation of a bimetallic BBU. This step is exemplified with the compound CuVOF(4)(H(2)O)(7): this compound, presented here, crystallizes in an NCS structure with ordered, isolated [Cu(H(2)O)(5)](2+) cations and [VOF(4)(H(2)O)](2-) anions into Λ-shaped, bimetallic BBUs to form CuVOF(4)(H(2)O)(6)·H(2)O, owing to the Jahn-Teller distortion of Cu(2+). Conversely, the centrosymmetric heterotypes with the same formula MVOF(4)(H(2)O)(7) (M(II) = Co, Ni, and Zn) exhibit ordered, isolated [VOF(4)(H(2)O)](2-) and [M(H(2)O)(6)](2+) ionic species in a hydrogen bond network. CuVOF(4)(H(2)O)(7) exhibits a net polar moment while the heterotypes do not; this demonstrates that Λ-shaped BBUs give a greater probability for and, in this case, lead to NCS structures. PMID:22335338

  12. The role of polar, lamdba (Λ)-shaped building units in noncentrosymmetric inorganic structures.

    Science.gov (United States)

    Donakowski, Martin D; Gautier, Romain; Yeon, Jeongho; Moore, Donald T; Nino, Juan C; Halasyamani, P Shiv; Poeppelmeier, Kenneth R

    2012-05-01

    A methodology for the design of polar, inorganic structures is demonstrated here with the packing of lambda (Λ)-shaped basic building units (BBUs). Noncentrosymmetric (NCS) solids with interesting physical properties can be created with BBUs that lack an inversion center and are likely to pack into a polar configuration; previous methods to construct these solids have used NCS octahedra as BBUs. Using this methodology to synthesize NCS solids, one must increase the coordination of the NCS octahedra with maintenance of the noncentrosymmetry of the bulk. The first step in this progression from an NCS octahedron to an inorganic NCS solid is the formation of a bimetallic BBU. This step is exemplified with the compound CuVOF(4)(H(2)O)(7): this compound, presented here, crystallizes in an NCS structure with ordered, isolated [Cu(H(2)O)(5)](2+) cations and [VOF(4)(H(2)O)](2-) anions into Λ-shaped, bimetallic BBUs to form CuVOF(4)(H(2)O)(6)·H(2)O, owing to the Jahn-Teller distortion of Cu(2+). Conversely, the centrosymmetric heterotypes with the same formula MVOF(4)(H(2)O)(7) (M(II) = Co, Ni, and Zn) exhibit ordered, isolated [VOF(4)(H(2)O)](2-) and [M(H(2)O)(6)](2+) ionic species in a hydrogen bond network. CuVOF(4)(H(2)O)(7) exhibits a net polar moment while the heterotypes do not; this demonstrates that Λ-shaped BBUs give a greater probability for and, in this case, lead to NCS structures.

  13. Three-dimensional thermal structure of the South Polar Vortex of Venus

    Science.gov (United States)

    Hueso, Ricardo; Garate-Lopez, Itziar; Garcia-Muñoz, Antonio; Sánchez-Lavega, Agustín

    2014-11-01

    We have analyzed thermal infrared images provided by the VIRTIS-M instrument aboard Venus Express (VEX) to obtain high resolution thermal maps of the Venus south polar region between 55 and 85 km altitudes. The maps investigate three different dynamical configurations of the polar vortex including its classical dipolar shape, a regularly oval shape and a transition shape between the different configurations of the vortex. We apply the atmospheric model described by García Muñoz et al. (2013) and a variant of the retrieval algorithm detailed in Grassi et al. (2008) to obtain maps of temperature over the Venus south polar region in the quoted altitude range. These maps are discussed in terms of cloud motions and relative vorticity distribution obtained previously (Garate-Lopez et al. 2013). Temperature maps retrieved at 55 - 63 km show the same structures that are observed in the ~5 µm radiance images. This altitude range coincides with the optimal expected values of the cloud top altitude at polar latitudes and magnitudes derived from the analysis of ~5 µm images are measured at this altitude range. We also study the imprint of the vortex on the thermal field above the cloud level which extends up to 80 km. From the temperature maps, we also study the vertical stability of different atmospheric layers. The cold collar is clearly the most statically stable structure at polar latitudes, while the vortex and subpolar latitudes show lower stability values. Furthermore, the hot filaments present within the vortex at 55-63 km exhibit lower values of static stability than their immediate surroundings.ReferencesGarate-Lopez et al. Nat. Geosci. 6, 254-257 (2013).García Muñoz et al. Planet. Space Sci. 81, 65-73 (2013).Grassi, D. et al. J. Geophys. Res. 113, 1-12 (2008).AcknowledgementsWe thank ESA for supporting Venus Express, ASI, CNES and the other national space agencies supporting VIRTIS on VEX and their principal investigators G. Piccioni and P. Drossart. This work

  14. A Compact Wideband Dual-Polarized Antenna with Harmonic Suppression Using Nonuniform Defected Ground Structure

    Directory of Open Access Journals (Sweden)

    Lana Damaj

    2015-01-01

    Full Text Available A wideband dual-polarized coplanar waveguide (CPW fed antenna integrating a wide stop-band filter is presented. The designed filter is based on a nonuniform defected ground structure (DGS in order to obtain a wide stop-band and a compact size. This filter is used to reject harmonics and spurious radiation arising from the RF front end. The complete structure (antenna and filter has been optimized to have a compact size of 0.6×0.6λ02 (λ0 being the free-space wavelength at the lowest operating frequency. The realized antenna operates in the frequency range between 2.7 GHz and 5.9 GHz (bandwidth of about 74%. The isolation between feeding ports is more than 18 dB. The complete structure has a wide stop-band characteristic (103% for harmonic rejection. The simulated numerical results have been confirmed with measurements.

  15. The Vast Polar Structure of the Milky Way and Filamentary Accretion of Sub-Halos

    CERN Document Server

    Pawlowski, Marcel S

    2012-01-01

    The Milky Way (MW) is surrounded by numerous satellite objects: dwarf galaxies, globular clusters and streams of disrupted systems. Together, these form a vast polar structure (VPOS), a thin plane spreading to Galactocentric distances as large as 250 kpc. The orbital directions of satellite galaxies and the preferred alignment of streams with the VPOS demonstrate that the objects orbit within the structure. This strong phase-space correlation is at odds with the expectations from simulations of structure formation based on the cold dark matter cosmology (LCDM). The accretion of sub-halos along filaments has been suggested as the origin of the anisotropic distribution. We have tested this scenario using the results of high-resolution cosmological simulations and found it unable to account for the large degree of correlation of the MW satellite orbits. It is therefore advisable to search for alternative explanations. The formation of tidal dwarf galaxies (TDGs) in the debris expelled from interacting galaxies i...

  16. Polarization memory effect in the photoluminescence of nc-Si-SiOx light-emitting structures

    Science.gov (United States)

    Michailovska, Katerina; Indutnyi, Ivan; Shepeliavyi, Petro; Sopinskyy, Mykola

    2016-06-01

    The polarization memory (PM) effect in the photoluminescence (PL) of the porous nc-Si-SiOx light-emitting structures, containing nanoparticles of silicon (nc-Si) in the oxide matrix and passivated in a solution of hydrofluoric acid (HF), has been investigated. The studied nc-Si-SiOx structures were produced by evaporation of Si monoxide (SiO) powder in vacuum and oblique deposition on Si wafer, and then the deposited silicon oxide (SiOx) films were annealed in the vacuum at 975 °C to grow nc-Si. It was found that the PM effect in the PL is observed only after passivation of nanostructures: during etching in HF solution, the initial symmetric nc-Si becomes asymmetric elongated. It was also found that in investigated nanostructures, there is a defined orientational dependence of the PL polarization degree ( ρ) in the sample plane which correlates with the orientation of SiOx nanocolumns, forming the structure of the porous layer. The increase of the ρ values in the long-wavelength spectral range with time of HF treatment can be associated with increasing of the anisotropy of large Si nanoparticles. The PM effect for this spectral interval can be described by the dielectric model. In the short-wavelength spectral range, the dependence of the ρ values agrees qualitatively with the quantum confinement effect.

  17. Polarization memory effect in the photoluminescence of nc-Si-SiOx light-emitting structures.

    Science.gov (United States)

    Michailovska, Katerina; Indutnyi, Ivan; Shepeliavyi, Petro; Sopinskyy, Mykola

    2016-12-01

    The polarization memory (PM) effect in the photoluminescence (PL) of the porous nc-Si-SiOx light-emitting structures, containing nanoparticles of silicon (nc-Si) in the oxide matrix and passivated in a solution of hydrofluoric acid (HF), has been investigated. The studied nc-Si-SiOx structures were produced by evaporation of Si monoxide (SiO) powder in vacuum and oblique deposition on Si wafer, and then the deposited silicon oxide (SiOx) films were annealed in the vacuum at 975 °C to grow nc-Si. It was found that the PM effect in the PL is observed only after passivation of nanostructures: during etching in HF solution, the initial symmetric nc-Si becomes asymmetric elongated. It was also found that in investigated nanostructures, there is a defined orientational dependence of the PL polarization degree (ρ) in the sample plane which correlates with the orientation of SiOx nanocolumns, forming the structure of the porous layer. The increase of the ρ values in the long-wavelength spectral range with time of HF treatment can be associated with increasing of the anisotropy of large Si nanoparticles. The PM effect for this spectral interval can be described by the dielectric model. In the short-wavelength spectral range, the dependence of the ρ values agrees qualitatively with the quantum confinement effect.

  18. Polarization memory effect in the photoluminescence of nc-Si-SiOx light-emitting structures.

    Science.gov (United States)

    Michailovska, Katerina; Indutnyi, Ivan; Shepeliavyi, Petro; Sopinskyy, Mykola

    2016-12-01

    The polarization memory (PM) effect in the photoluminescence (PL) of the porous nc-Si-SiOx light-emitting structures, containing nanoparticles of silicon (nc-Si) in the oxide matrix and passivated in a solution of hydrofluoric acid (HF), has been investigated. The studied nc-Si-SiOx structures were produced by evaporation of Si monoxide (SiO) powder in vacuum and oblique deposition on Si wafer, and then the deposited silicon oxide (SiOx) films were annealed in the vacuum at 975 °C to grow nc-Si. It was found that the PM effect in the PL is observed only after passivation of nanostructures: during etching in HF solution, the initial symmetric nc-Si becomes asymmetric elongated. It was also found that in investigated nanostructures, there is a defined orientational dependence of the PL polarization degree (ρ) in the sample plane which correlates with the orientation of SiOx nanocolumns, forming the structure of the porous layer. The increase of the ρ values in the long-wavelength spectral range with time of HF treatment can be associated with increasing of the anisotropy of large Si nanoparticles. The PM effect for this spectral interval can be described by the dielectric model. In the short-wavelength spectral range, the dependence of the ρ values agrees qualitatively with the quantum confinement effect. PMID:27255897

  19. Determination of the Structure of the Coronal Magnetic Field Using Microwave Polarization Measurements

    Science.gov (United States)

    Bogod, V. M.; Yasnov, L. V.

    2016-07-01

    An analysis of the oscillatory motions and wave processes in active regions requires knowledge of the structure of the magnetic fields in the chromosphere and corona. We study the magnetic field structure of active regions at coronal heights, as they are determined by means of multiwave observations of polarized radio emission of active regions in the microwave range. Two methods, a stereoscopic method and the analysis of the radio spectrum are used. The method of stereoscopy rotation allows estimating the height of radio sources in a stable active region relative to the photosphere, based on its apparent motion in the image plane recorded over several days of observation. At various times one-dimensional scans at multiple frequencies spanning the 5.98 - 15.95 GHz frequency range from the RATAN-600 instrument are used. The gyroresonance emission mechanism, which is sensitive to the coronal magnetic field strength, is applied to convert the radio source estimated heights at various frequencies, h(f), to information as regards magnetic field vs. height, B(h). Diagrams of longitude - height of some polarized radio sources revealed multiple reversals, suggestive of a spiral magnetic structure. In all cases, the magnetic field strength maintains high values (800 - 1000 G) at the highest altitudes analysed, which reflects a relatively weak divergence in the field of magnetic flux tubes (in the height range 8 - 14 Mm) responsible for the main part of the radio emission of active regions.

  20. Invited review: climate change impacts in polar regions: lessons from Antarctic moss bank archives.

    Science.gov (United States)

    Royles, Jessica; Griffiths, Howard

    2015-03-01

    Mosses are the dominant plants in polar and boreal regions, areas which are experiencing rapid impacts of regional warming. Long-term monitoring programmes provide some records of the rate of recent climate change, but moss peat banks contain an unrivalled temporal record of past climate change on terrestrial plant Antarctic systems. We summarise the current understanding of climatic proxies and determinants of moss growth for contrasting continental and maritime Antarctic regions, as informed by 13C and 18O signals in organic material. Rates of moss accumulation are more than three times higher in the maritime Antarctic than continental Antarctica with growing season length being a critical determinant of growth rate, and high carbon isotope discrimination values reflecting optimal hydration conditions. Correlation plots of 13C and 18O values show that species (Chorisodontium aciphyllum / Polytrichum strictum) and growth form (hummock / bank) are the major determinants of measured isotope ratios. The interplay between moss growth form, photosynthetic physiology, water status and isotope composition are compared with developments of secondary proxies, such as chlorophyll fluorescence. These approaches provide a framework to consider the potential impact of climate change on terrestrial Antarctic habitats as well as having implications for future studies of temperate, boreal and Arctic peatlands. There are many urgent ecological and environmental problems in the Arctic related to mosses in a changing climate, but the geographical ranges of species and life-forms are difficult to track individually. Our goal was to translate what we have learned from the more simple systems in Antarctica, for application to Arctic habitats.

  1. Impacts of Polar Changes on the UV-induced Mineralization of Terrigenous Dissolved Organic Matter.

    Science.gov (United States)

    Sulzberger, Barbara; Arey, J Samuel

    2016-07-01

    Local climates in the Northern and Southern Hemisphere are influenced by Arctic Amplification and by interactions of the Antarctic ozone hole with climate change, respectively. Polar changes may affect hydroclimatic conditions in temperate regions, for example, by increasing the length and intensity of precipitation events at Northern Hemisphere midlatitudes. Additionally, global warming has led to the thawing of ancient permafrost soils, particularly in Arctic regions, due to Arctic Amplification. Both heavy precipitation events and thawing of permafrost are increasing the net transfer of terrestrially derived dissolved organic matter (DOM) from land to surface waters. In aquatic ecosystems, UV-induced oxidation of terrigenous DOM (tDOM) produces atmospheric CO2 and this process is one of several mechanisms by which natural organic matter in aquatic and soil environments may play an important role in climate feedbacks. The Arctic is particularly affected by these processes: for example, melting of Arctic sea ice allows solar UV radiation to penetrate into the ice-free Arctic Ocean and to cause photochemical reactions that result in bleaching and mineralization of tDOM. Open questions, in addition to those shown in the Graphical Abstract, remain regarding the resulting contributions of tDOM photomineralization to CO2 production and global warming. PMID:27110903

  2. A novel microwave cancellation circuit for measuring nonlinear dielectric changes of polar solution under microwave fields

    Science.gov (United States)

    Sun, Hao-Ran; Huang, Ka-Ma

    2015-12-01

    In this paper, an experimental set-up based on a novel microstrip cancellation circuit is presented for investigating the effects of external microwave fields on the dielectric properties of polar solution. The circuit consists of a 3 dB Wilkinson power combiner, a conventional 20 dB backward coupler, and a specially designed 20 dB single-sectioned forward coupler. Besides, in order to realize a uniform electric field in the tested solution, a nicked microstrip ring is designed in the circuit. An improvement of measurement sensitivity in the proposed circuit was obtained when compared to the conventional transmission lines method. We exploit interference cancellation processes to suppress the probing signal at the output port under the principle that two identical amplitude signals with 180° phase difference will completely cancel each other. The measurements are carried out at the frequency of 2.45 GHz, and the temperature effects caused by microwave heating are excluded by the flowing fluid. Experimental results show that the dielectric properties of DMSO-methanol/ethanol mixtures change at the electric field intensity of 105 V m  -  1 and present a distinctly nonlinear dielectric change with the electric fields. The study of the microwave-material interaction has expanded our insights into the high-power microwave’s industry application.

  3. Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom Fragilariopsis cylindrus

    Directory of Open Access Journals (Sweden)

    M. Pančić

    2015-03-01

    Full Text Available The effects of ocean acidification and increased temperature on physiology of six strains of the polar diatom Fragilariopsis cylindrus from Greenland were investigated. Experiments were performed under manipulated pH levels (8.0, 7.7, 7.4, and 7.1 and different temperatures (1, 5 and 8 °C to simulate changes from present to plausible future levels. Each of the 12 scenarios was run for 7 days, and a significant interaction between temperature and pH on growth was detected. By combining increased temperature and acidification, the two factors counterbalanced each other, and therefore no effect on the growth rates was found. However, the growth rates increased with elevated temperatures by ∼20–50% depending on the strain. In addition, a general negative effect of increasing acidification on growth was observed. At pH 7.7 and 7.4, the growth response varied considerably among strains. However, a more uniform response was detected at pH 7.1 with most of the strains exhibiting reduced growth rates by 20–37% compared to pH 8.0. It should be emphasized that a significant interaction between temperature and pH was found, meaning that the combination of the two parameters affected growth differently than when considering one at a time. Based on these results, we anticipate that the polar diatom F. cylindrus will be unaffected by changes in temperature and pH within the range expected by the end of the century. In each simulated scenario, the variation in growth rates among the strains was larger than the variation observed due to the whole range of changes in either pH or temperature. Climate change may therefore not affect the species as such, but may lead to changes in the population structure of the species, with the strains exhibiting high phenotypic plasticity, in terms of temperature and pH tolerance towards future conditions, dominating the population.

  4. Outlook for activity and structural change

    International Nuclear Information System (INIS)

    The level of energy-using activities is continuing to increase throughout the world, but the rates of likely growth differ among regions. Over the next 20 years, manufacturing production is expected to grow at a rapid pace in parts of the developing world, and moderately in the OECD countries. In the Former East Bloc, it seems likely to stagnate or decline for much of the 1990s, but could then grow at a moderate pace if the transition to a market economy is successfully managed. Domestic passenger travel seems likely to increase everywhere, and growth in international travel will be especially strong. Freight transport activity is difficult to evaluate in the aggregate, since the composition of goods changes over time, but increase is expected in all regions, especially in the developing countries. Structural change within sectors will have significant impacts on energy use. In manufacturing, faster growth in light industry will lead to lower energy intensity in the OECD countries and especially in the Former East Bloc. The outlook in the LDCs suggests somewhat higher growth in energy-intensive industries, but this trend will vary among countries. In passenger travel, structural change is pointing toward higher energy intensity in most of the world as the role of automobiles and air travel continues to grow. Increase in the use of trucks is pushing in a similar direction in freight transport. In the residential sector, structural change will have only a moderate impact in the OECD countries, where per capita levels of home services are already high, but will push energy use significantly upward in the LDCs, and to a lesser extent, in the Former East Bloc. 17 refs., 4 figs., 1 tab

  5. Stability of the β-structure in prion protein: A molecular dynamics study based on polarized force field

    Science.gov (United States)

    Xu, Zhijun; Lazim, Raudah; Mei, Ye; Zhang, Dawei

    2012-06-01

    Conformational changes of the antiparallel β-sheet in normal cellular prion protein (PrPC) of rat, bovine, and human are investigated by molecular dynamics simulations in both neutral and acidic environment. Using a recently developed simulation method based on an on-the-fly polarized protein-specific charge (PPC) update scheme during the simulation process, we evaluate and compare the cross-species performances of the β-sheet during the early stage transition from the PrPC to its mutant configuration. Through this study, we observe the growth of the β-sheet structure in all species studied with the extent of elongation in β-sheet being different across the three species.

  6. Tensor-polarized structure functions: Tensor structure of deuteron in 2020's

    OpenAIRE

    Kumano, S

    2014-01-01

    We explain spin structure for a spin-one hadron, in which there are new structure functions, in addition to the ones ($F_1$, $F_2$, $g_1$, $g_2$) which exist for the spin-1/2 nucleon, associated with its tensor structure. The new structure functions are $b_1$, $b_2$, $b_3$, and $b_4$ in deep inelastic scattering of a charged-lepton from a spin-one hadron such as the deuteron. Among them, twist-two functions are related by the Callan-Gross type relation $b_2 = 2 x b_1$ in the Bjorken scaling l...

  7. Investigations of the supramolecular structure of individual diphenylalanine nano- and microtubes by polarized Raman microspectroscopy.

    Science.gov (United States)

    Lekprasert, Banyat; Korolkov, Vladimir; Falamas, Alexandra; Chis, Vasile; Roberts, Clive J; Tendler, Saul J B; Notingher, Ioan

    2012-07-01

    Polarized Raman microspectroscopy and atomic force microscopy were used to obtain quantitative information regarding the molecular structure of individual diphenylalanine (FF) nano- and microtubes. The frequencies of the Raman spectral bands corresponding to the amide I (1690 cm(-1)) and amide III (1249 cm(-1)) indicated that the FF-molecules interact by hydrogen bonding at the N-H and not at the C═O sites. The calculated mean orientation angles of the principal axes of the Raman tensors (PARTs) obtained from the polarized Raman spectral measurements were 41 ± 4° for the amide I and 59 ± 5° for amide III. On the basis of the orientation of the PART for the amide I mode, it was found that the C═O bond is oriented at an angle of 8 ± 4° to the tube axis. These values did not vary significantly with the diameter of the tubes (range 400-1700 nm) and were in agreement with the molecular structure proposed previously for larger crystalline specimens. PMID:22662867

  8. Structured caustic vector vortex optical field: manipulating optical angular momentum flux and polarization rotation.

    Science.gov (United States)

    Chen, Rui-Pin; Chen, Zhaozhong; Chew, Khian-Hooi; Li, Pei-Gang; Yu, Zhongliang; Ding, Jianping; He, Sailing

    2015-05-29

    A caustic vector vortex optical field is experimentally generated and demonstrated by a caustic-based approach. The desired caustic with arbitrary acceleration trajectories, as well as the structured states of polarization (SoP) and vortex orders located in different positions in the field cross-section, is generated by imposing the corresponding spatial phase function in a vector vortex optical field. Our study reveals that different spin and orbital angular momentum flux distributions (including opposite directions) in different positions in the cross-section of a caustic vector vortex optical field can be dynamically managed during propagation by intentionally choosing the initial polarization and vortex topological charges, as a result of the modulation of the caustic phase. We find that the SoP in the field cross-section rotates during propagation due to the existence of the vortex. The unique structured feature of the caustic vector vortex optical field opens the possibility of multi-manipulation of optical angular momentum fluxes and SoP, leading to more complex manipulation of the optical field scenarios. Thus this approach further expands the functionality of an optical system.

  9. Structures in the protoplanetary disk of HD142527 seen in polarized scattered light

    CERN Document Server

    Avenhaus, Henning; Schmid, Hans Martin; Meyer, Michael R; Garufi, Antonio; Wolf, Sebastian; Dominik, Carsten

    2013-01-01

    We present H- and Ks-band polarized differential images (PDI) of the Herbig Ae/Be star HD142527, revealing its optically thick outer disk and the nearly empty gap. The very small inner working angle (~0.1") and high resolution achievable with an 8m-class telescope, together with a careful polarimetric calibration strategy, allow us to achieve images that surpass the quality of previous scattered light images. Previously known substructures are resolved more clearly and new structures are seen. Specifically, we are able to resolve 1) half a dozen spiral structures in the disk, including previously known outer-disk spirals as well as new spiral arms and arcs close to the inner rim of the disk; 2) peculiar holes in the polarized surface brightness at position angles of ~0{\\deg} and ~160{\\deg}; 3) the inner rim on the eastern side of the disk; 4) the gap between the outer and inner disk, ranging from the inner working angle of 0.1" out to between 0.7 and 1.0", which is nearly devoid of dust. We then use a Markov-...

  10. Study on the layered dusty plasma structures in the summer polar mesopause

    Directory of Open Access Journals (Sweden)

    Bin Xu

    2010-09-01

    Full Text Available Traditional hydrodynamic equations are adopted to build a one-dimensional theoretical model to study the effect of gravity wave on layered dusty plasma structures formation and evolution near the polar summer mesospause region associated with polar mesosphere summer echoes (PMSE. The proposed mechanism gives consideration to the charged ice particle motion by the gravity wave modulation, making a significant contribution to the vertical transport of heavy ice particles and convergence into thin layers. And numerical results show that the pattern of the multi-layer structure depends on the ration of the initial ice particles density distribution to the vertical wavelength of the gravity waves, the ice particle size and the wind velocity caused by gravity wave. Also, the variation of ion density distribution under the influence of gravity wave has also been examined. Finally, the electron density depletions (bite-outs layers has been simulated according to the charge conservation laws, and the results are compared to the ECT02 rocket sounding data, which agree well with the measuring.

  11. The Fine-Structure of the Net-Circular Polarization in a Sunspot Penumbra

    CERN Document Server

    Tritschler, A; Schlichenmaier, R; Hagenaar, H J

    2007-01-01

    We present novel evidence for a fine structure observed in the net-circular polarization (NCP) of a sunspot penumbra based on spectropolarimetric measurements utilizing the Zeeman sensitive FeI 630.2 nm line. For the first time we detect a filamentary organized fine structure of the NCP on spatial scales that are similar to the inhomogeneities found in the penumbral flow field. We also observe an additional property of the visible NCP, a zero-crossing of the NCP in the outer parts of the center-side penumbra, which has not been recognized before. In order to interprete the observations we solve the radiative transfer equations for polarized light in a model penumbra with embedded magnetic flux tubes. We demonstrate that the observed zero-crossing of the NCP can be explained by an increased magnetic field strength inside magnetic flux tubes in the outer penumbra combined with a decreased magnetic field strength in the background field. Our results strongly support the concept of the uncombed penumbra.

  12. Tensor-polarized structure functions: Tensor structure of deuteron in 2020's

    CERN Document Server

    Kumano, S

    2014-01-01

    We explain spin structure for a spin-one hadron, in which there are new structure functions, in addition to the ones ($F_1$, $F_2$, $g_1$, $g_2$) which exist for the spin-1/2 nucleon, associated with its tensor structure. The new structure functions are $b_1$, $b_2$, $b_3$, and $b_4$ in deep inelastic scattering of a charged-lepton from a spin-one hadron such as the deuteron. Among them, twist-two functions are related by the Callan-Gross type relation $b_2 = 2 x b_1$ in the Bjorken scaling limit. First, these new structure functions are introduced, and useful formulae are derived for projection operators of $b_{1-4}$ from a hadron tensor $W_{\\mu\

  13. Special Features of Polarization-Induced Relaxation in Structurally Disordered Finely Dispersed Systems

    Science.gov (United States)

    Shcherbachenko, L. A.; Tanaev, A. B.; Bezrukova, Ya. V.; Ezhova, L. I.; Baryshnikov, D. S.; Marchuk, S. D.; Berezovskii, P. P.

    2015-04-01

    Dielectric characteristics of finely dispersed hydrated natural coal from the Krasnoyarsk Strip Mine are measured in wide ranges of external measuring electric field frequencies, environmental temperatures, and humidities. The frequency, temperature, and concentration dispersions of the dielectric permittivity are revealed for the examined structures. An analysis of the results obtained demonstrates that a cluster layer of the polar aqueous matrix characterized by rigid fixing of water molecules is formed at the interphase boundaries of the examined system. It is demonstrated that this layer plays the role of the potential barrier that complicates transitions for both free water molecules and surface active dispersed coals oriented by the electric field. This layer can increase the electric strength of the examined disordered finely dispersed structures.

  14. Three Dimensional Structure of the Mars North Polar Basal Unit from MARSIS data

    Science.gov (United States)

    Frigeri, A.; Orosei, R.; Cartacci, M.; Cicchetti, A.; Mitri, G.; Giuppi, S.; Noschese, R.; Picardi, G.; Plaut, J.

    2012-04-01

    Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) is an orbital subsurface sounder aboard ESA's Mars Express spacecraft . It transmits a low-frequency radar pulse that is capable of penetrating below the surface, and is reflected by subsurface dielectric discontinuities. MARSIS has been used to probe both the south and the north polar caps of Mars, revealing their thickness and structure. We report on the results of a campaign of observations of the north polar ice cap of Mars that took place between May and December 2011 in uniquely favorable conditions and produced data of unprecedented quality. The focus of this work is the so-called Basal Unit, a dark, ice-rich, complexely layered geologic unit lying stratigraphically between the polar layered deposits and the Vastitas Borealis Formation, and extending beneath most of Planum Boreum and Olympia Planitia. The objective of this work is the to study the full three dimensional structure of the Northern Polar Deposit and in particular of the Basal Unit (BU). It was recently found that the BU consists of two markedly different units, called the Rupes Tenuis unit and the Planum Boreum cavi unit. The Rupes Tenuis unit appears to be older, horizontally layered, and lacking erosional contacts. It has been thus interpreted as the result of precipitation and cold-trapping of dust-laden volatiles. The Planum Boreum cavi unit displays cross-bedding, indicating dune accumulation. Bright layers within it are interpreted as being made of ice-cemented dust, while dark layers should consist of weathered basalt fines. It seems likely that, in places, the Planum Boreum cavi unit rests directly on the Vastitas Borealis, without the Rupes Tenuis unit in between. Because the two units in the BU have formed much earlier than the north polar layered deposits, and at some interval from each other, they bear evidence of past climatic conditions that were very different from present, so that they "could potentially be a

  15. Optical and Micro-Structural Characterization of MBE Grown Indium Gallium Nitride Polar Quantum Dots

    KAUST Repository

    El Afandy, Rami

    2011-07-07

    Gallium nitride and related materials have ushered in scientific and technological breakthrough for lighting, mass data storage and high power electronic applications. These III-nitride materials have found their niche in blue light emitting diodes and blue laser diodes. Despite the current development, there are still technological problems that still impede the performance of such devices. Three-dimensional nanostructures are proposed to improve the electrical and thermal properties of III-nitride optical devices. This thesis consolidates the characterization results and unveils the unique physical properties of polar indium gallium nitride quantum dots grown by molecular beam epitaxy technique. In this thesis, a theoretical overview of the physical, structural and optical properties of polar III-nitrides quantum dots will be presented. Particular emphasis will be given to properties that distinguish truncated-pyramidal III-nitride quantum dots from other III-V semiconductor based quantum dots. The optical properties of indium gallium nitride quantum dots are mainly dominated by large polarization fields, as well as quantum confinement effects. Hence, the experimental investigations for such quantum dots require performing bandgap calculations taking into account the internal strain fields, polarization fields and confinement effects. The experiments conducted in this investigation involved the transmission electron microscopy and x-ray diffraction as well as photoluminescence spectroscopy. The analysis of the temperature dependence and excitation power dependence of the PL spectra sheds light on the carrier dynamics within the quantum dots, and its underlying wetting layer. A further analysis shows that indium gallium nitride quantum dots through three-dimensional confinements are able to prevent the electronic carriers from getting thermalized into defects which grants III-nitrides quantum dot based light emitting diodes superior thermally induced optical

  16. Structural changes in dairy business in Croatia

    Directory of Open Access Journals (Sweden)

    Teo Vujčić

    2005-01-01

    Full Text Available Croatia today is in the economy transition process that also includes agriculture aiming to increase production and achieving competitive standard with international and European markets. Currently, domestic cow milk production ensures 80% of annual milk and dairy products requirements with the 20% import. In the period from 1990-1992, during the patriot war, 103000 cows and heifers were destroyed. Since then, Croatia started the gradual process of reorganization of the agricultural private sector including dairy business in order to increase production insensitivity.The agricultural structure of dairy segment is unsatisfactory with only 23.39% of farms holding four or more heifers. Households with 3 cows per farm dominate with average real estate of 0.10-3.0 acres.Changes in milk production (1990-2003 are reflected in the decrease of the number of breeding cattle – index 56.13%, and decrease of milk market producers from 65 000 to 65 151. Never the less, positive trends towards stabilization in milk production (2003 – 642 mil litres and annual milk intake increased from 342 mil litres in 1990 to 472 mil litres in 2003 (index 138.08% can be noticed. Changes in the structure of milk producers show certain positive movements as 23.39% of producers have 53.40% cows and respectively participation in milk production and buy off. Until 2008, with determined development conditions, cow milk production can increase for 42% and from 2703 litres to average of 4000 litres per dairy cow.

  17. Linear polarization structures in LOFAR observations of the interstellar medium in the 3C 196 field

    Science.gov (United States)

    Jelić, V.; de Bruyn, A. G.; Pandey, V. N.; Mevius, M.; Haverkorn, M.; Brentjens, M. A.; Koopmans, L. V. E.; Zaroubi, S.; Abdalla, F. B.; Asad, K. M. B.; Bus, S.; Chapman, E.; Ciardi, B.; Fernandez, E. R.; Ghosh, A.; Harker, G.; Iliev, I. T.; Jensen, H.; Kazemi, S.; Mellema, G.; Offringa, A. R.; Patil, A. H.; Vedantham, H. K.; Yatawatta, S.

    2015-11-01

    Aims: This study aims to characterize linear polarization structures in LOFAR observations of the interstellar medium (ISM) in the 3C 196 field, one of the primary fields of the LOFAR-Epoch of Reionization key science project. Methods: We have used the high band antennas (HBA) of LOFAR to image this region and rotation measure (RM) synthesis to unravel the distribution of polarized structures in Faraday depth. Results: The brightness temperature of the detected Galactic emission is 5-15 K in polarized intensity and covers the range from -3 to +8 rad m-2 in Faraday depth. The most interesting morphological feature is a strikingly straight filament at a Faraday depth of +0.5 rad m-2 running from north to south, right through the centre of the field and parallel to the Galactic plane. There is also an interesting system of linear depolarization canals conspicuous in an image showing the peaks of Faraday spectra. We used the Westerbork Synthesis Radio Telescope (WSRT) at 350 MHz to image the same region. For the first time, we see some common morphology in the RM cubes made at 150 and 350 MHz. There is no indication of diffuse emission in total intensity in the interferometric data, in line with results at higher frequencies and previous LOFAR observations. Based on our results, we determined physical parameters of the ISM and proposed a simple model that may explain the observed distribution of the intervening magneto-ionic medium. Conclusions: The mean line-of-sight magnetic field component, B∥, is determined to be 0.3 ± 0.1 μG and its spatial variation across the 3C 196 field is 0.1 μG. The filamentary structure is probably an ionized filament in the ISM, located somewhere within the Local Bubble. This filamentary structure shows an excess in thermal electron density (neB∥> 6.2 cm-3μG) compared to its surroundings. The RM cubes (FITS files) are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  18. On Polarization and Mobility: A look at polarization in the wage-career profile in Italy

    OpenAIRE

    Ambra Poggi; Jacques Silber

    2008-01-01

    This paper attempts to combine the analysis of wage (income) polarization with that of wage (income) mobility. Using the polarization index PG recently proposed by Deutsch et al. (2007) it shows that, when taking the identity of the individuals into account (working with panel data), a distinction can be made between a change over time in polarization that is the consequence of "structural mobility" (change over time in the overall, between and within groups inequality) and a change in polari...

  19. Design of Compact EBG Structure and effect on Circularly Polarized Triangular Patch with Stub

    Directory of Open Access Journals (Sweden)

    Snehalata Chokat,

    2012-05-01

    Full Text Available This paper presents the study of electromagnetic band gap (EBG structure using slot ring and its effect oncircularly polarized triangular patch antenna performance. The EBG structure has been designed on dielectricsubstrate εr=4.3 and thickness h=1.53mm. The EBG structure acts as resonator which attenuates the surfacewave propagation in a specific frequency range. A new single slot ring EBG structure is proposed whichexhibits surface wave attenuation better than 20 dB in the frequency range from 2.75 GHz to 3.2 GHz. Anantenna with center frequency of 2.8 GHz is designed with and without EBG. The peak gain and radiation efficiency of this antenna are mproved significantly when antenna is above EBG in comparison to ntenna without EBG. The simulated adiation patterns of the antenna xhibit reduction in backward adiation when antenna above EBG plane n comparison to radiation pattern without EBG. Keywords- ctromagnetic band gap (EBG, periodic structures, fractal geometry, platting through hole (PTH, microstrip antenna, and surface wave suppression.

  20. Structural Integrity Analysis of CEA Change Platform

    International Nuclear Information System (INIS)

    The Control Element Assembly Change Platform (CEA CP) is similar to a gantry crane. The CEA CP for Shin-Kori units 3 and 4 (SKN 3 and 4) consists of a bridge, which spans the reactor cavity pool and a gantry superstructure mounted on the bridge. The structure is approximately 8.8 m wide, 4.9 m long and 10.6 m high. The gantry superstructure supports one ton capacity hoist trolley and the bridge supports the In Core Instrumentation (ICI) retrieval cart which moves along the bridge. This paper presents the dynamic and structural analysis of CEA CP which is greater than that of the previous nuclear power plants to verify the structural integrity under the application of the earthquake spectrum. The analysis have been performed using the three orthogonal SSE response spectrum for SKN 3 and 4 which shows much higher acceleration value than OPR- 1000 Plants. In addition, the analyses are performed by 3-dimensional finite element analysis using ANSYS software

  1. Changing Arctic Ecosystems: Updated forecast: Reducing carbon dioxide (CO2) emissions required to improve polar bear outlook

    Science.gov (United States)

    Oakley, Karen L.; Atwood, Todd C.; Mugel, Douglas N.; Rode, Karyn D.; Whalen, Mary E.

    2015-01-01

    The Arctic is warming faster than other regions of the world due to the loss of snow and ice, which increases the amount of solar energy absorbed by the region. The most visible consequence has been the rapid decline in sea ice over the last 3 decades-a decline projected to bring long ice-free summers if greenhouse gas (GHG) emissions are not significantly reduced. The polar bear (Ursus maritimus) depends on sea ice over the biologically productive continental shelves of the Arctic Ocean as a platform for hunting seals. In 2008, the U.S. Fish and Wildlife Service listed the polar bear as threatened under the Endangered Species Act (ESA) due to the threat posed by sea ice loss. The polar bear was the first species to be listed due to forecasted population declines from climate change.

  2. Quasistatic electric field structures and field-aligned currents in the polar cusp region

    Science.gov (United States)

    Jacobsen, K. S.; Moen, J. I.; Pedersen, A.

    2010-10-01

    Cluster data have been examined for quasi-stationary electric field structures and field-aligned currents (FACs) in the vicinity of the dayside cusp region. We have related the measurements to the Region 1/Region 2 (R1/R2) current system and the cusp current system. It has been theoretically proposed that the dayside R1 current may be located on open field lines, and experimental evidence has been shown for R1 currents partially on open field lines. We document that R1 currents may flow entirely on open field lines. The electric field structures are found to occur at plasma density gradients in the cusp. They are associated with strong FACs with current directions that are consistent with the cusp currents. This indicates that the electric field structures are closely coupled to the cusp current system. The electric equipotential structures linking the perpendicular electric fields seen at Cluster altitudes to field-aligned electric fields at lower altitudes fall into one of two categories: S shape or U shape. Both types are found at both the equatorward edge of the cusp ion dispersion and at the equatorward edge of injection events within the cusp. Previous studies in the nightside auroral region attributed the S-shaped potential structures to the boundary transition between the low-density polar cap and the high-density plasma sheet, concluding that the shape of the electric potential structure depends on whether the plasma populations on each side of the structure can support intense currents. This explanation is not applicable for the S-shaped structures observed in the dayside cusp region.

  3. The effect of chemical variations on the structural polarity of relaxor ferroelectrics studied by resonance Raman spectroscopy.

    Science.gov (United States)

    Rohrbeck, A; de la Flor, G; Aroyo, M I; Gospodinov, M; Bismayer, U; Mihailova, B

    2016-11-30

    Resonance Raman spectroscopy was applied to doped PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 relaxor ferroelectrics, to better understand the effect of composition disorder on the mesoscopic-scale polar order in complex perovskite-type (ABO3) ferroelectrics. The excitation photon energy used was 3.8 eV, which is slightly above the energy gap and corresponds to the maximum of the optical dielectric permittivity. Group-theory analysis reveals that the resonance Raman scattering (RRS) observed under these conditions is allowed only in polar crystal classes. Therefore, RRS is dominated by the atomic dynamics of nanoregions with coherent polar distortions, which considerably facilitates the comparison of polar order in various compounds. The results show that A-site doping (Ba(2+), Sr(2+), La(3+), Bi(3+)) has significantly stronger effect on the structural polarity than the introduction of a third element at the B site (Nb(5+) or Sn(4+) doped in PbSc0.5Ta0.5O3). The A-site substitution by cations that in contrast to Pb(2+) have isotropic outermost electron shells disturbs the system of lone-pair electrons, thus reducing the correlation length of coupled polar distortions and the strength of the electric field associated with the mean polarization of polar nanoregions. A-site doping with larger cations (Ba(2+)) augments the polar deformation of the individual BO6 octahedra due to local elastic fields. As a result, such A-site doping intensifies the initial structural polarity at high temperatures and prevails the enlargement of the polar fraction at low temperatures. A-site doping with smaller cations (Sr(2+), La(3+)), regardless if they are isovalent or aliovalent to Pb(2+), increases the correlation length of antiferrodistortive order (BO6 tilts), which in turn assists the development of double-perovskite structure with coherent local polar distortions. A-site doping with aliovalent cations (Bi(3+)) having the same outermost electron shell and ionic radius as the host A

  4. The effect of chemical variations on the structural polarity of relaxor ferroelectrics studied by resonance Raman spectroscopy

    Science.gov (United States)

    Rohrbeck, A.; de la Flor, G.; Aroyo, M. I.; Gospodinov, M.; Bismayer, U.; Mihailova, B.

    2016-11-01

    Resonance Raman spectroscopy was applied to doped PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 relaxor ferroelectrics, to better understand the effect of composition disorder on the mesoscopic-scale polar order in complex perovskite-type (ABO3) ferroelectrics. The excitation photon energy used was 3.8 eV, which is slightly above the energy gap and corresponds to the maximum of the optical dielectric permittivity. Group-theory analysis reveals that the resonance Raman scattering (RRS) observed under these conditions is allowed only in polar crystal classes. Therefore, RRS is dominated by the atomic dynamics of nanoregions with coherent polar distortions, which considerably facilitates the comparison of polar order in various compounds. The results show that A-site doping (Ba2+, Sr2+, La3+, Bi3+) has significantly stronger effect on the structural polarity than the introduction of a third element at the B site (Nb5+ or Sn4+ doped in PbSc0.5Ta0.5O3). The A-site substitution by cations that in contrast to Pb2+ have isotropic outermost electron shells disturbs the system of lone-pair electrons, thus reducing the correlation length of coupled polar distortions and the strength of the electric field associated with the mean polarization of polar nanoregions. A-site doping with larger cations (Ba2+) augments the polar deformation of the individual BO6 octahedra due to local elastic fields. As a result, such A-site doping intensifies the initial structural polarity at high temperatures and prevails the enlargement of the polar fraction at low temperatures. A-site doping with smaller cations (Sr2+, La3+), regardless if they are isovalent or aliovalent to Pb2+, increases the correlation length of antiferrodistortive order (BO6 tilts), which in turn assists the development of double-perovskite structure with coherent local polar distortions. A-site doping with aliovalent cations (Bi3+) having the same outermost electron shell and ionic radius as the host A-site Pb2+ cations leads to

  5. The effect of chemical variations on the structural polarity of relaxor ferroelectrics studied by resonance Raman spectroscopy.

    Science.gov (United States)

    Rohrbeck, A; de la Flor, G; Aroyo, M I; Gospodinov, M; Bismayer, U; Mihailova, B

    2016-11-30

    Resonance Raman spectroscopy was applied to doped PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 relaxor ferroelectrics, to better understand the effect of composition disorder on the mesoscopic-scale polar order in complex perovskite-type (ABO3) ferroelectrics. The excitation photon energy used was 3.8 eV, which is slightly above the energy gap and corresponds to the maximum of the optical dielectric permittivity. Group-theory analysis reveals that the resonance Raman scattering (RRS) observed under these conditions is allowed only in polar crystal classes. Therefore, RRS is dominated by the atomic dynamics of nanoregions with coherent polar distortions, which considerably facilitates the comparison of polar order in various compounds. The results show that A-site doping (Ba(2+), Sr(2+), La(3+), Bi(3+)) has significantly stronger effect on the structural polarity than the introduction of a third element at the B site (Nb(5+) or Sn(4+) doped in PbSc0.5Ta0.5O3). The A-site substitution by cations that in contrast to Pb(2+) have isotropic outermost electron shells disturbs the system of lone-pair electrons, thus reducing the correlation length of coupled polar distortions and the strength of the electric field associated with the mean polarization of polar nanoregions. A-site doping with larger cations (Ba(2+)) augments the polar deformation of the individual BO6 octahedra due to local elastic fields. As a result, such A-site doping intensifies the initial structural polarity at high temperatures and prevails the enlargement of the polar fraction at low temperatures. A-site doping with smaller cations (Sr(2+), La(3+)), regardless if they are isovalent or aliovalent to Pb(2+), increases the correlation length of antiferrodistortive order (BO6 tilts), which in turn assists the development of double-perovskite structure with coherent local polar distortions. A-site doping with aliovalent cations (Bi(3+)) having the same outermost electron shell and ionic radius as the host A

  6. Vectorial mapping of noncollinear antiferromagnetic structure of semiconducting FeSe surface with spin-polarized scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Antiferromagnetic semiconductors gain increasing interest due to their possible application in spintronics. Using spin polarized scanning tunneling microscopy operating in a vector field, we mapped the noncollinear antiferromagnetic spin structure of a semiconducting hexagonal FeSe surface on the atomic scale. The surface possesses an in-plane compensated Néel structure which is further confirmed by first-principles calculations

  7. Vectorial mapping of noncollinear antiferromagnetic structure of semiconducting FeSe surface with spin-polarized scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, K. F.; Yang, Fang; Song, Y. R. [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhang, Xiaole [Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240 (China); The State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Chen, Xianfeng [The State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Canhua; Qian, Dong; Gao, C. L., E-mail: clgao@sjtu.edu.cn; Jia, Jin-Feng [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing (China); Luo, Weidong, E-mail: wdluo@sjtu.edu.cn [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing (China)

    2016-02-08

    Antiferromagnetic semiconductors gain increasing interest due to their possible application in spintronics. Using spin polarized scanning tunneling microscopy operating in a vector field, we mapped the noncollinear antiferromagnetic spin structure of a semiconducting hexagonal FeSe surface on the atomic scale. The surface possesses an in-plane compensated Néel structure which is further confirmed by first-principles calculations.

  8. Transport of Spin-Polarized Electrons through an NEM-SET Structure with Ferromagnetic Electrodes

    Science.gov (United States)

    Wang, R.; Jiang, K.

    2009-10-01

    We have investigated the spin-polarized electron transport in a magnetic nanoelectromechanical single-electron-transistor (NEM-SET), with an oscillating quantum dot (QD) coupled to two ferromagnetic electrodes. The interplay between the electronic and mechanical degrees of freedom is considered by using the quantum master equation method within Wigner phase-space. We present a concrete picture for the transition of the QD oscillations from the tunneling state to the shuttling one by analysis of the electron occupation, the effective potential and amplitude probability distribution. It is found that the development of dynamic shuttle instability is dependent on the relative orientation of two leads' magnetizations, which arises a pronounced spin valve effect. For an asymmetric NEM-SET structure, besides the spin valve effect, we unexpectedly find that the shuttle instability is additionally dependent on the the bias-voltage polarities, exhibiting a sizable current rectifica tion. The coexistence of two effects makes it possible to control the spin valve effect electrically or control the rectification magnetically.

  9. Non-Gaussian Structure of B-mode Polarization after Delensing

    CERN Document Server

    Namikawa, Toshiya

    2015-01-01

    The B-mode polarization of the cosmic microwave background on large scales has been considered as a probe of gravitational waves from the cosmic inflation. Ongoing and future experiments will, however, suffer from contamination due to the B-modes of non-primordial origins, one of which is the lensing induced B-mode polarization. Subtraction of the lensing B-modes, usually referred to as delensing, will be required for further improvement of detection sensitivity of the gravitational waves. In such experiments, knowledge of statistical properties of the B-modes after delensing is indispensable to likelihood analysis particularly because the lensing B-modes are known to be non-Gaussian. In this paper, we study non-Gaussian structure of the delensed B-modes on large scales, comparing them with those of the lensing B-modes. In particular, we investigate the power spectrum correlation matrix and the probability distribution function (PDF) of the power spectrum amplitude. Assuming an experiment in which the quadrat...

  10. Spin structure of the proton from polarized inclusive deep-inelastic muon-proton scattering

    CERN Document Server

    Adams, D; Arik, E; Arvidson, A; Badelek, B; Ballintijn, M K; Bardin, G; Baum, G; Berglund, P; Betev, L; Bird, I G; Birsa, R; Björkholm, P; Bonner, B E; De Botton, N R; Boutemeur, M; Bradamante, Franco; Bravar, A; Bressan, A; Bültmann, S; Burtin, E; Cavata, C; Crabb, D; Cranshaw, J; Çuhadar-Dönszelmann, T; Dalla Torre, S; Van Dantzig, R; Derro, B R; Deshpande, A A; Dhawan, S K; Dulya, C M; Dyring, A; Eichblatt, S; Faivre, Jean-Claude; Fasching, D; Feinstein, F; Fernández, C; Frois, Bernard; Gallas, A; Garzón, J A; Gaussiran, T; Giorgi, M A; von Goeler, E; Gracia, G; De Groot, N; Grosse-Perdekamp, M; Gülmez, E; Von Harrach, D; Hasegawa, T; Hautle, P; Hayashi, N; Heusch, C A; Horikawa, N; Hughes, V W; Igo, G; Ishimoto, S; Iwata, T; Kabuss, E M; Karev, A G; Kessler, H J; Ketel, T; Kishi, A; Kiselev, Yu F; Klostermann, L; Krämer, Dietrich; Krivokhizhin, V G; Kröger, W; Kurek, K; Kyynäräinen, J; Lamanna, M; Landgraf, U; Layda, T; Le Goff, J M; Lehár, F; de Lesquen, A; Lichtenstadt, J; Lindqvist, T; Litmaath, M; Loewe, M; Magnon, A; Mallot, G K; Marie, F; Martin, A; Martino, J; Matsuda, T; Mayes, B W; McCarthy, J S; Medved, K S; Van Middelkoop, G; Miller, D; Mori, K; Moromisato, J H; Nagaitsev, A P; Nassalski, J P; Naumann, Lutz; Niinikoski, T O; Oberski, J; Ogawa, A; Ozben, C; Parks, D P; Penzo, Aldo L; Perrot-Kunne, F; Peshekhonov, V D; Piegaia, R; Pinsky, L; Platchkov, S K; Pló, M; Pose, D; Postma, H; Pretz, J; Pussieux, T; Pyrlik, J; Reyhancan, I; Rijllart, A; Roberts, J B; Rock, S E; Rodríguez, M; Rondio, Ewa; Rosado, A; Sabo, I; Saborido, J; Sandacz, A; Savin, I A; Schiavon, R P; Schüler, K P; Segel, R E; Seitz, R; Semertzidis, Y K; Sever, F; Shanahan, P; Sichtermann, E P; Simeoni, F; Smirnov, G I; Staude, A; Steinmetz, A; Stiegler, U; Stuhrmann, H B; Szleper, M; Teichert, K M; Tessarotto, F; Tlaczala, W; Trentalange, S; Ünel, G; Velasco, M; Vogt, J; Voss, Rüdiger; Weinstein, R; Whitten, C; Windmolders, R; Willumeit, R; Wislicki, W; Witzmann, A; Zanetti, A M; Zaremba, K; Zhao, J

    1997-01-01

    We have measured the spin-dependent structure function $g_1^{\\rm p}$ in inclusive deep-inelastic scattering of polarized muons off polarized protons, in the kinematic range $0.003 < x < 0.7$ and $1\\gevtwo < Q^2 < 60\\gevtwo$. A next-to-leading order QCD analysis is used to evolve the measured $\\gpone(x,Q^2)$ to a fixed $Q^2_0$. The first moment of $\\gpone$ at $Q^2_0 = 10\\gevtwo$ is $\\gammap = 0.136\\pm 0.013 \\,(\\mbox{stat.}) \\pm 0.009\\,(\\mbox{syst.})\\pm 0.005\\ (\\mbox{evol.})$. This result is below the prediction of the Ellis--Jaffe sum rule by more than two standard deviations. The singlet axial charge $\\dsigt$ is found to be $0.28 \\pm 0.16$. In the Adler--Bardeen factorization scheme, $\\Delta g \\simeq 2$ is required to bring $\\Delta \\Sigma$ in agreement with the Quark-Parton Model. A combined analysis of all available proton and deuteron data confirms the Bjorken sum rule.

  11. Phytoplankton abundance and community structure in the Antarctic polar frontal region during austral summer of 2009

    Institute of Scientific and Technical Information of China (English)

    SHRAMIK Patil; RAHUL Mohan; SUHAS Shetye; SAHINA Gazi

    2013-01-01

    The Antarctic polar front region in the Southern Ocean is known to be most productive.We studied the phytoplankton community structure in the Indian sector at this frontal location during late austral summer (February,2009) onboard R/V Akademic Boris Petrov.We used the phytoplankton and microheterotrophs abundance,as also the associated physico-chemical parameters to explain the low phytoplankton abundance in the study region.This study emphasizes the shift of phytoplankton,from large (>10 μm) to small (<10 μm) size.The phytoplankton abundance appears to be controlled by physical parameters and by nutrient concentrations and also by the microheterotrophs (ciliates and dinoflagellates) which exert a strong grazing pressure.This probably reduces small (<10 μm) and large (>10 μm)phytoplankton abundance during the late austral summer.This study highlights the highly productive polar front nevertheless becomes a region of low phytoplankton abundance,due to community shifts towards pico-phytoplankton (<10 μm) during late austral summer.

  12. Morphological, structural and electrical investigations on non-polar a-plane ZnO epilayers

    Science.gov (United States)

    Lautenschlaeger, Stefan; Eisermann, Sebastian; Hofmann, Michael N.; Roemer, Udo; Pinnisch, Melanie; Laufer, Andreas; Meyer, Bruno K.; von Wenckstern, Holger; Lajn, Alexander; Schmidt, Florian; Grundmann, Marius; Blaesing, Juergen; Krost, Alois

    2010-07-01

    We report on the growth of non-polar a-plane ZnO by CVD on r-plane-sapphire-wafers, a-plane GaN-templates and a-plane ZnO single-crystal substrates. Only the homoepitaxial growth approach leads to a Frank-van-der-Merwe growth mode, as shown by atomic force microscopy. The X-ray-diffraction spectra of the homoepitaxial thin films mirror the excellent crystalline quality of the ZnO substrate. The morphological and the structural quality of the homoepitaxial films is comparable to the best results for the growth on c-plane ZnO-substrates. The impurity incorporation, especially of group III elements, seems to be reduced when growing on the non-polar a-plane surface compared to the c-plane films as demonstrated by secondary ion mass spectrometry (SIMS). Optical properties have been investigated using low temperature photoluminescence measurements. We employed capacitance-voltage measurements ( C- V) to measure the background carrier density and its profile from substrate/film interface throughout the film to the surface. In thermal admittance spectroscopy (TAS) specific traps could be distinguished, and their thermal activation energies and capture cross sections could be determined.

  13. The effects of human umbilical cord perivascular cells on rat hepatocyte structure and functional polarity.

    Science.gov (United States)

    Gómez-Aristizábal, Alejandro; Davies, John Edward

    2013-06-01

    Hepatocyte culture is a useful tool for the study of their biology and the development of bioartificial livers. However, many challenges have to be overcome since hepatocytes rapidly lose their normal phenotype in vitro. We have recently demonstrated that human umbilical cord perivascular cells (HUCPVCs) are able to provide support to hepatocytes. In the present study we go further into exploring the effects that HUCPVCs have in the functional polarization, and both the internal and external organization, of hepatocytes. Also, we investigate HUCPVC-hepatocyte crosstalk by tracking both the effects of HUCPVCs on hepatocyte transcription factors and those of hepatocytes on the expression of hepatotrophic factors in HUCPVCs. Our results show that HUCPVCs maintain the functional polarity of hepatocytes ex vivo, as judged by the secretion of fluorescein into bile canaliculi, for at least 40 days. Transmission electron microscopy revealed that hepatocytes in coculture organize in an organoid-like structure embedded in extracellular matrix surrounded by HUCPVCs. In coculture, hepatocytes displayed a higher expression of C/EBPα, implicated in maintenance of the mature hepatocyte phenotype, and HUCPVCs upregulated hepatocyte growth factor and Jagged1 indicating that these genes may play important roles in HUCPVC-hepatocyte interactions.

  14. The local anesthetic tetracaine destabilizes membrane structure by interaction with polar headgroups of phospholipids.

    Science.gov (United States)

    Shimooka, T; Shibata, A; Terada, H

    1992-03-01

    The effect of the local anesthetic tetracaine at less than 10 mM on the water permeability of the phospholipid membrane was examined using liposomes composed of various molar ratios of negatively charged cardiolipin to electrically neutral phosphatidylcholine by monitoring their osmotic shrinkage in hypertonic glucose solution at 30 degrees C. The concentration of tetracaine causing the maximum velocity of shrinkage of liposomes increased with increase in the molar ratio of cardiolipin. Tetracaine increased the zeta-potential of the negatively charged liposomal membrane toward the positive side due to the binding of its cationic form to the negatively charged polar headgroups in the membrane. The maximum velocity of water permeation induced by osmotic shock was observed at essentially the same tetracaine concentration giving a zeta-potential of the liposomal membrane of 0 mV. These concentrations were not affected by change in the sort of acyl-chain of phospholipids in the liposomes when their negative charges were the same. These results suggests that the membrane integrity is governed mainly by the electrical charge of phospholipid polar headgroups when phospholipid bilayers are in the highly fluid state, and that positively charged tetracaine molecules neutralize the negative surface charge, lowering the barrier for water permeation through phospholipid bilayers. PMID:1547263

  15. Temporal changes in methane stable isotopes in polar ice cores: big picture and implications for ecosystem changes

    Science.gov (United States)

    Bock, Michael; Schmitt, Jochen; Seth, Barbara; Beck, Jonas; Fischer, Hubertus

    2014-05-01

    Methane (CH4) is the third most important greenhouse gas after water vapour and carbon dioxide (CO2). Since the industrial revolution the mixing ratio of CH4 in the atmosphere rose to ~1800 ppb, a value never reached within the last 800 000 years. Nowadays, CH4 contributes ~20% to the total radiative forcing from all of the long-lived greenhouse gases. This CH4 increase can only be assessed in relation to natural methane changes in the past. Firn air and air enclosures in polar ice cores represent the only direct paleoatmospheric archive. The latter show that atmospheric CH4 concentrations changed in concert with northern hemisphere temperature during both glacial/interglacial transitions as well as rapid climate changes (Dansgaard-Oeschger events), however, the sources of the methane concentration changes are still a matter of debate. Stable isotopes of methane (δ13CH4 and δD(CH4)) may help to distinguish differences in the magnitude of source type emissions (e.g. Bock et al. 2010). However, recently we could show that it is difficult to interpret the atmospheric loading of methane by relative source mix changes alone (Möller et al. 2013). In fact it appears, that the carbon isotopic signature (δ13CH4) of e.g. tropical wetlands undergoes drastic shifts connected to climate, CO2, sea level or potentially other unknown processes. Here we present the big picture derived from the EDML (European Project for Ice Coring in Antarctica, Dronning Maud Land) and Vostok ice cores (Möller et al. 2013) and additional new dual isotope data from 4 ice cores from both poles that cover three interglacials: the Holocene, MIS 5 and MIS 11. The contribution sheds light on our current understanding of methane biogeochemistry and discusses open questions. References: Bock, M., J. Schmitt, L. Möller, R. Spahni, T. Blunier, H. Fischer (2010). 'Hydrogen Isotopes Preclude Marine Hydrate CH4 Emissions at the Onset of Dansgaard-Oeschger Events', Science, 328, 1686-1689 Möller, L., T

  16. Structural polarization properties of vector Gaussian beam in the far field

    Institute of Scientific and Technical Information of China (English)

    Zhou Guo-Quan; Ni Yong-Zhou; Chu Xiu-Xiang

    2007-01-01

    Based on the vector angular spectrum representation of optical beam and the method of stationary phase, the analytical TE and TM terms of vector Gaussian beam have been presented in the far field. By using the local polarization matrix, the polarization properties of the TE and TM terms in the far field are investigated, and it is found that the degree of their polarization is only determined by the spatial location. When the source is completely polarized, the TE and TM terms are both completely polarized in the far field. When the source is completely unpolarized, the TE and TM terms in the far field are partially polarized. The whole beam is also partially polarized except on the propagating axis. Moreover, the degrees of polarization of TE and TM terms are both larger than that of the whole beam.

  17. Deuteron electromagnetic structure functions and polarization properties in soft-wall AdS/QCD

    CERN Document Server

    Gutsche, Thomas; Schmidt, Ivan

    2016-01-01

    We apply a soft-wall AdS/QCD approach to the description of deuteron structure functions and tensor polarized properties. Present work is a completion of our previous study on electromagnetic form factors. By the appropriate choice of two couplings in the effective action we are able to reproduce both the form factors and structure functions in full consistency with model-independent constraints set by perturbative QCD. Our framework is based on a five-dimensional action in AdS space formulated in terms of vector fields dual to the deuteron and the electromagnetic fields. The AdS fields depend on four Minkowski and one holographic coordinate $z$. The scale dependence of the form factors and structure functions is consistent with quark counting rules implying the $1/Q^{10}$ behavior of the charge form factor $G_C(Q^2)$, structure functions $A(Q^2)$ and $B(Q^2)$, and the $1/Q^{12}$ behavior of the magnetic $G_M(Q^2)$ and quadrupole $G_Q(Q^2)$ form factors.

  18. Magnetic Structure and Dynamics of the Erupting Solar Polar Crown Prominence on 2012 March 12

    CERN Document Server

    Su, Yingna; McCauley, Patrick I; Ji, Haisheng; Reeves, Katharine K; DeLuca, Edward E

    2015-01-01

    We present an investigation of the polar crown prominence that erupted on 2012 March 12. This prominence is observed at the southeast limb by SDO/AIA (end-on view) and displays a quasi vertical-thread structure. Bright U-shape/horn-like structure is observed surrounding the upper portion of the prominence at 171 angstrom before the eruption and becomes more prominent during the eruption. The disk view of STEREO-B shows that this long prominence is composed of a series of vertical threads and displays a half loop-like structure during the eruption. We focus on the magnetic support of the prominence vertical threads by studying the structure and dynamics of the prominence before and during the eruption using observations from SDO and STEREO-B. We also construct a series of magnetic field models (sheared arcade model, twisted flux rope model, and unstable model with hyperbolic flux tube (HFT)). Various observational characteristics appear to be in favor of the twisted flux rope model. We find that the flux rope ...

  19. Polarity determination of epitaxial structures of CdTe on GaAs by channeling techniques

    Energy Technology Data Exchange (ETDEWEB)

    Wielunski, L.S. (CSIRO Div. of Applied Physics, Lucas Heights Research Labs., Menai, NSW (Australia)); Kwietniak, M.S.; Pain, G.N. (Telecom Australia Research Labs., Clayton, Victoria (Australia)); Rossouw, C.J. (CSIRO Div. of Materials Science and Tech., Clayton, Victoria (Australia))

    1990-01-01

    RBS spectra analysis near the (111) planar channeling direction is used for polarity determination of MOCVD-grown epitaxial layers of (111) and (100) CdTe on sapphire and GaAs substrates. Extensive multiple twinning limits the application of RBS channeling analysis for polarity determination. Comparison is made with polarity determination by X-ray diffraction and two electron diffraction techniques. (orig.).

  20. Surface Binding of TOTAPOL Assists Structural Investigations of Amyloid Fibrils by Dynamic Nuclear Polarization NMR Spectroscopy.

    Science.gov (United States)

    Nagaraj, Madhu; Franks, Trent W; Saeidpour, Siavash; Schubeis, Tobias; Oschkinat, Hartmut; Ritter, Christiane; van Rossum, Barth-Jan

    2016-07-15

    Dynamic nuclear polarization (DNP) NMR can enhance sensitivity but often comes at the price of a substantial loss of resolution. Two major factors affect spectral quality: low-temperature heterogeneous line broadening and paramagnetic relaxation enhancement (PRE) effects. Investigations by NMR spectroscopy, isothermal titration calorimetry (ITC), and EPR revealed a new substantial affinity of TOTAPOL to amyloid surfaces, very similar to that shown by the fluorescent dye thioflavin-T (ThT). As a consequence, DNP spectra with remarkably good resolution and still reasonable enhancement could be obtained at very low TOTAPOL concentrations, typically 400 times lower than commonly employed. These spectra yielded several long-range constraints that were difficult to obtain without DNP. Our findings open up new strategies for structural studies with DNP NMR spectroscopy on amyloids that can bind the biradical with affinity similar to that shown towards ThT. PMID:27147408

  1. The Meso-Structured Magnetic Atmosphere -- A Stochastic Polarized Radiative Transfer Approach

    CERN Document Server

    Carroll, T A

    2007-01-01

    We present a general radiative transfer model appropriate to diagnose the small scale and mostly unresolved magnetic field of the solar photosphere. Present modeling techniques still rely to a large extend on a-priori assumptions about the geometry of the underlying magnetic field. In an effort to obtain a more flexible and unbiased approach we pursue a rigorous statistical description of the underlying atmosphere. Based on a Markov random field model the atmospheric structures are characterized in terms of probability densities and spatial correlations. This approach allows us to derive a stochastic transport equation for polarized light valid in a regime with an arbitrary fluctuating magnetic field on finite scales. One of the key ingredients of the derived stochastic transfer equation is the correlation length which provides an additional degree of freedom to the transport equation and can therefore be used as a diagnostic parameter to estimate the characteristic length scale of the underlying magnetic fie...

  2. CHANGES IN STRUCTURE OF ROMANIA'S INTERNATIONAL TRADE

    Directory of Open Access Journals (Sweden)

    CECILIA IRINA RABONTU

    2014-05-01

    Full Text Available Evolution of structural changes in Romanian trade is somewhat interesting if you look at it from the perspective of mutations that occurred in the categories of goods and services subject to international trade. After the Revolution of 1989, the Romanian economy has gone through dramatic changes that had determinate a total reconfiguration of foreign trade. At the same time, the economic instability has had further repercussions on the Romanian economy manifested through higher prices, reduced wages or earnings, reduced employment and rising unemployment, increasing interest rates on loans due to the devaluation of the national currency, increase value-added tax, consumption reduction etc. We proposed in this paper an analyze for a significant period of time evolution of international trade in goods and services of Romania in order to establish the main categories of goods traded but Romania's main trading partners, too. In order to achieve the central goal of this paper we will use statistical data found in the databases provided by the WTO, Eurostat and the National Statistical Institutes and statistical methods to support our initiative.

  3. Photoluminescence polarization anisotropy for studying long-range structural ordering within semiconductor multi-atomic alloys and organic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Prutskij, T.; Percino, J. [Instituto de Ciencias, BUAP, Privada 17 Norte, No 3417, col. San Miguel Huyeotlipan, 72050, Puebla, Pue. (Mexico); Orlova, T. [Department of Chemical and Biochemical Engineering, University of Notre Dame, Notre Dame, IN (United States); Vavilova, L. [Ioffe Physical-Technical Institute, 26 Polytekhnicheskaya, St Petersburg 194021, Russian Federation (Russian Federation)

    2013-12-04

    Long-range structural ordering within multi-component semiconductor alloys and organic crystals leads to significant optical anisotropy and, in particular, to anisotropy of the photoluminescence (PL) emission. The PL emission of ternary and quaternary semiconductor alloys is polarized if there is some amount of the atomic ordering within the crystal structure. We analyze the polarization of the PL emission from the quaternary GaInAsP semiconductor alloy grown by Liquid Phase Epitaxy (LPE) and conclude that it could be caused by low degree atomic ordering within the crystal structure together with the thermal biaxial strain due to difference between the thermal expansion coefficients of the layer and the substrate. We also study the state of polarization of the PL from organic crystals in order to identify different features of the crystal PL spectrum.

  4. Impact of changes in grain size and pore space on the hydraulic conductivity and spectral induced polarization response of sand

    Directory of Open Access Journals (Sweden)

    K. Koch

    2011-06-01

    Full Text Available Understanding the influence of pore space characteristics on the hydraulic conductivity and spectral induced polarization (SIP response is critical for establishing relationships between the electrical and hydrological properties of surficial unconsolidated sedimentary deposits, which host the bulk of the world's readily accessible groundwater resources. Here, we present the results of laboratory SIP measurements on industrial-grade, saturated quartz samples with granulometric characteristics ranging from fine sand to fine gravel. We altered the pore space characteristics by changing (i the grain size spectra, (ii the degree of compaction, and (iii the level of sorting. We then examined how these changes affect the SIP response, the hydraulic conductivity, and the specific surface area of the considered samples. In general, the results indicate a clear connection between the SIP response and the granulometric as well as pore space characteristics. In particular, we observe a systematic correlation between the hydraulic conductivity and the relaxation time of the Cole-Cole model describing the observed SIP effect for the entire range of considered grain sizes. The results do, however, also indicate that the detailed nature of these relations depends strongly on variations in the pore space characteristics, such as, for example, the degree of compaction. This underlines the complexity of the origin of the SIP signal as well as the difficulty to relate it to a single structural factor of a studied sample, and hence raises some fundamental questions with regard to the practical use of SIP measurements as site- and/or sample-independent predictors of the hydraulic conductivity.

  5. Interstellar Polarization in the Taurus Dark Clouds, Wavelength Dependent Position Angles and Cloud Structure Near TMC-1

    CERN Document Server

    Messinger, D W; Roberge, W G

    1997-01-01

    We use polarimetric observations of two stars (HD29647, HD283809) in the general direction of TMC-1 in the Taurus Dark Cloud to investigate grain properties and cloud structure in this region. We show the data to be consistent with a simple two-component model, in which general interstellar polarization in the Taurus Cloud is produced by a widely distributed cloud component with relatively uniform magnetic field orientation; the light from stars close to TMC-1 suffers additional polarization arising in one (or more) subcloud(s) with larger average grain size and different magnetic field directions compared with the general trend. Towards HD29647, in particular, we show that the unusually low degree of visual polarization relative to extinction is due to the presence of distinct cloud components in the line of sight with markedly different magnetic field orientations. Stokes parameter calculations allow us to separate out the polarization characteristics of the individual components. Results are fit with the S...

  6. Self-sustained spin-polarized current oscillations in multiquantum well structures

    Energy Technology Data Exchange (ETDEWEB)

    Escobedo, Ramon [Departamento de Matematica Aplicada y Ciencias de la Computacion, Universidad de Cantabria, 39005 Santander (Spain); Carretero, Manuel; Bonilla, Luis L [G. Millan Institute, Fluid Dynamics, Nanoscience and Industrial Mathematics, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Platero, Gloria [Instituto de Ciencia de Materiales, CSIC, 28049 Cantoblanco (Spain)], E-mail: escobedo@unican.es, E-mail: manuel.carretero@uc3m.es, E-mail: bonilla@ing.uc3m.es, E-mail: gplatero@icmm.csic.es

    2009-01-15

    Nonlinear transport through diluted magnetic semiconductor nanostructures is investigated. We have considered a II-VI multiquantum well nanostructure whose wells are selectively doped with Mn. The response to a dc voltage bias may be either a stationary or an oscillatory current. We have studied the transition from stationary to time-dependent current as a function of the doping density and the number of quantum wells. Analysis and numerical solution of a nonlinear spin transport model shows that the current in a structure without magnetic impurities is stationary, whereas current oscillations may appear if at least one well contains magnetic impurities. For long structures having two wells with magnetic impurities, a detailed analysis of nucleation of charge dipole domains shows that self-sustained current oscillations are caused by repeated triggering of dipole domains at the magnetic wells and motion towards the collector. Depending on the location of the magnetic wells and the voltage, dipole domains may be triggered at both wells or at only one. In the latter case, the well closer to the collector may inhibit domain motion between the first and the second well inside the structure. Our study could allow design of oscillatory spin-polarized current injectors.

  7. Structure, magnetic properties, polarized neutron diffraction, and theoretical study of a copper(II) cubane.

    Science.gov (United States)

    Aronica, Christophe; Chumakov, Yurii; Jeanneau, Erwann; Luneau, Dominique; Neugebauer, Petr; Barra, Anne-Laure; Gillon, Béatrice; Goujon, Antoine; Cousson, Alain; Tercero, Javier; Ruiz, Eliseo

    2008-01-01

    The paper reports the synthesis, X-ray and neutron diffraction crystal structures, magnetic properties, high field-high frequency EPR (HF-EPR), spin density and theoretical description of the tetranuclear CuII complex [Cu4L4] with cubane-like structure (LH2=1,1,1-trifluoro-7-hydroxy-4-methyl-5-aza-hept-3-en-2-one). The simulation of the magnetic behavior gives a predominant ferromagnetic interaction J1 (+30.5 cm(-1)) and a weak antiferromagnetic interaction J2 (-5.5 cm(-1)), which correspond to short and long Cu-Cu distances, respectively, as evidence from the crystal structure [see formulate in text]. It is in agreement with DFT calculations and with the saturation magnetization value of an S=2 ground spin state. HF-EPR measurements at low temperatures (5 to 30 K) provide evidence for a negative axial zero-field splitting parameter D (-0.25+/-0.01 cm(-1)) plus a small rhombic term E (0.025+/-0.001 cm(-1), E/D = 0.1). The experimental spin distribution from polarized neutron diffraction is mainly located in the basal plane of the CuII ion with a distortion of yz-type for one CuII ion. Delocalization on the ligand (L) is observed but to a smaller extent than expected from DFT calculations. PMID:18792037

  8. Polar cloud observatory at Ny-Ålesund in GRENE Arctic Climate Change Research Project

    Science.gov (United States)

    Yamanouchi, Takashi; Takano, Toshiaki; Shiobara, Masataka; Okamoto, Hajime; Koike, Makoto; Ukita, Jinro

    2016-04-01

    Cloud is one of the main processes in the climate system and especially a large feed back agent for Arctic warming amplification (Yoshimori et al., 2014). From this reason, observation of polar cloud has been emphasized and 95 GHz cloud profiling radar in high precision was established at Ny-Ålesund, Svalbard in 2013 as one of the basic infrastructure in the GRENE (Green Network of Excellence Program) Arctic Climate Change Research Project. The radar, "FALCON-A", is a FM-CW (frequency modulated continuous wave) Doppler radar, developed for Arctic use by Chiba University (PI: T. Takano) in 2012, following its prototype, "FALCON-1" which was developed in 2006 (Takano et al., 2010). The specifications of the radar are, central frequency: 94.84 GHz; antenna power: 1 W; observation height: up to 15 km; range resolution: 48 m; beam width: 0.2 degree (15 m at 5 km); Doppler width: 3.2 m/s; time interval: 10 sec, and capable of archiving high sensitivity and high spatial and time resolution. An FM-CW type radar realizes similar sensitivity with much smaller parabolic antennas separated 1.4 m from each other used for transmitting and receiving the wave. Polarized Micro-Pulse Lidar (PMPL, Sigma Space MPL-4B-IDS), which is capable to measure the backscatter and depolarization ratio, has also been deployed to Ny-Ålesund in March 2012, and now operated to perform collocated measurements with FALCON-A. Simultaneous measurement data from collocated PMPL and FALCON-A are available for synergetic analyses of cloud microphysics. Cloud mycrophysics, such as effective radius of ice particles and ice water content, are obtained from the analysis based on algorithm, which is modified for ground-based measurements from Okamoto's retrieval algorithm for satellite based cloud profiling radar and lidar (CloudSat and CALIPSO; Okamoto et al., 2010). Results of two years will be shown in the presentation. Calibration is a point to derive radar reflectivity (dBZ) from original intensity data

  9. SOCIAL POLARIZATION AND CONFLICT: A NETWORK APPROACH

    Directory of Open Access Journals (Sweden)

    Ernesto Cárdenas

    2013-12-01

    Full Text Available Theoretically, polarization is associated with a higher probability of social conflict. This paper, in a microeconomic model based on the theory of social networks, analyses how changes in the network's structure affect the level of some basic parameters associated with the concept of polarization. This study shows that under upward monotonic preferences, longer sets of affiliations for each individual reduce polarization, whereas under downward monotonic preferences, longer sets of the so-called bad affiliations increase polarization. Finally, in the case of a non-monotonic system of preferences, an expansion of the affiliations set will alter the resulting polarization order in different ways depending on the preferences themselves

  10. Influence of solvent polarity on the structure of drop-cast electroactive tetra(aniline)-surfactant thin films.

    Science.gov (United States)

    Dane, Thomas G; Bartenstein, Julia E; Sironi, Beatrice; Mills, Benjamin M; Alexander Bell, O; Emyr Macdonald, J; Arnold, Thomas; Faul, Charl F J; Briscoe, Wuge H

    2016-09-21

    The influence of processing conditions on the thin film microstructure is a fundamental question that must be understood to improve the performance of solution-processed organic electronic materials. Using grazing-incidence X-ray diffraction, we have studied the structure of thin films of a tetra(aniline)-surfactant complex prepared by drop-casting from five solvents (hexane, chloroform, tetrahydrofuran, dichloromethane and ethanol), selected to cover a range of polarities. We found that the structure, level of order and degree of orientation relative to the substrate were extremely sensitive to the solvent used. We have attempted to correlate such solvent sensitivity with a variety of solvent physical parameters. Of particular significance is the observation of a sharp structural transition in the thin films cast from more polar solvents; such films presented significantly greater crystallinity as measured by the coherence length and paracrystalline disorder parameter. We attribute this higher structural order to enhanced dissociation of the acid surfactant in the more polar solvents, which in turn promotes complex formation. Furthermore, the more polar solvents provide more effective screening of (i) the attractive ionic interaction between oppositely charged molecules, providing greater opportunity for dynamic reorganisation of the supramolecular aggregates into more perfect structures; and (ii) the repulsive interaction between the positively charged blocks permitting a solvophobic-driven aggregation of the aromatic surfaces during solvent evaporation.

  11. Influence of solvent polarity on the structure of drop-cast electroactive tetra(aniline)-surfactant thin films.

    Science.gov (United States)

    Dane, Thomas G; Bartenstein, Julia E; Sironi, Beatrice; Mills, Benjamin M; Alexander Bell, O; Emyr Macdonald, J; Arnold, Thomas; Faul, Charl F J; Briscoe, Wuge H

    2016-09-21

    The influence of processing conditions on the thin film microstructure is a fundamental question that must be understood to improve the performance of solution-processed organic electronic materials. Using grazing-incidence X-ray diffraction, we have studied the structure of thin films of a tetra(aniline)-surfactant complex prepared by drop-casting from five solvents (hexane, chloroform, tetrahydrofuran, dichloromethane and ethanol), selected to cover a range of polarities. We found that the structure, level of order and degree of orientation relative to the substrate were extremely sensitive to the solvent used. We have attempted to correlate such solvent sensitivity with a variety of solvent physical parameters. Of particular significance is the observation of a sharp structural transition in the thin films cast from more polar solvents; such films presented significantly greater crystallinity as measured by the coherence length and paracrystalline disorder parameter. We attribute this higher structural order to enhanced dissociation of the acid surfactant in the more polar solvents, which in turn promotes complex formation. Furthermore, the more polar solvents provide more effective screening of (i) the attractive ionic interaction between oppositely charged molecules, providing greater opportunity for dynamic reorganisation of the supramolecular aggregates into more perfect structures; and (ii) the repulsive interaction between the positively charged blocks permitting a solvophobic-driven aggregation of the aromatic surfaces during solvent evaporation. PMID:27539382

  12. Azimuthal Structure of the Sand Erg that Encircles the North Polar Water-Ice Cap

    Science.gov (United States)

    Teodoro, L. A.; Elphic, R. C.; Eke, V. R.; Feldman, W. C.; Maurice, S.; Pathare, A.

    2011-12-01

    The sand erg that completely encircles the perennial water-ice cap that covers the Martian north geographic pole displays considerable azimuthal structure as seen in visible and near-IR images. Much of this structure is associated with the terminations of the many steep troughs that cut spiral the approximately 3 km thick polar ice cap. Other contributions come from the katabatic winds that spill over steep-sided edges of the cap, such as what bounds the largest set of dunes that comprise Olympia Undae. During the spring and summer months when these winds initiate from the higher altitudes that contain sublimating CO2 ice, which is very cold and dry, heat adiabatically when they compress as they lose altitude. These winds should then remove H2O moisture from the uppermost layer of the sand dunes that are directly in their path. Two likely locations where this desiccation may occur preferentially is at the termination of Chasma Boreale and the ice cap at Olympia Undae. We will search for this effect by sharpening the spatial structure of the epithermal neutron counting rates measured at northern high latitudes using the Mars Odyssey Neutron Spectrometer (MONS). The epithermal range of neutron energies is nearly uniquely sensitive to the hydrogen content of surface soils, which should likely be in the form of H2O/OH molecules/radicals. We therefore convert epithermal counting rates in terms of Water-Equivalent-Hydrogen, WEH. However, MONS counting-rate data have a FWHM of ~550 km., which is sufficiently broad to prevent a close association of WEH variability with images of geological features. In this study, we reduce spurious features in the instrument smeared neutron counting rates through deconvolution. We choose the PIXON numerical deconvolution technique for this purpose. This technique uses a statistical approach (Pina 2001, Eke 2001), which is capable of removing spurious features in the data in the presence of noise. We have previously carried out a detailed

  13. Electronic structures and the spin polarization of Heusler alloy Co2FeAl surface

    Science.gov (United States)

    Xu, Xiaoguang; Wang, Yankai; Zhang, Delin; Jiang, Yong

    2011-01-01

    The electronic structures of the Heusler alloy Co2FeAl surface are studied theoretically via first-principles calculations. The space localization of the surface states is the key effect on the electronic structures of the Co2FeAl surface. At the surface, the lattice parameter shrinks to minimize the total energy, and the minority spin gap disappears and shows a metallic band gap character. However, with the depth increasing, the lattice parameter equals to that of bulk phase, and there shows an energy gap opening at the Fermi level in the minority spin states. As a result, the spin polarization at the surface is lower than that of the bulk Co2FeAl, while it is close to that of bulk phase beneath the surface. According to the calculations, it is clear that the half-metallic property fading of the Co2FeAl films is caused by the surface states. Therefore, it is important to minimize the lattice mismatch at the interface of Co2FeAl in order to obtain a high tunneling magnetoresistance.

  14. Joint effect of polarization and the propagation path of a light beam on its intrinsic structure

    CERN Document Server

    Abdulkareem, Sarkew

    2016-01-01

    The well-known effects of the spin-orbit interaction of light are manifestations of pair mutual influence of the three types of the angular momentum of light, namely, the spin angular momentum, the extrinsic orbital angular momentum and the intrinsic orbital angular momentum. Here we propose the convenient classification of the effects of the spin-orbit interaction of light and we observe one of the new effects in the frame of this classification, which is determined by the joint influence of two types of the angular momentum on the third type of the angular momentum, namely, the influence of the spin angular momentum and the extrinsic orbital angular momentum on the intrinsic orbital angular momentum. We experimentally studied the propagation of circularly polarized light through an optical fiber coiled into a helix. We have found that the spin angular momentum and the helix parameters affect the spatial structure of the radiation transmitted through the optical fiber. We found out that the structure of the ...

  15. Valley-dependent band structure and valley polarization in periodically modulated graphene

    Science.gov (United States)

    Lu, Wei-Tao

    2016-08-01

    The valley-dependent energy band and transport property of graphene under a periodic magnetic-strained field are studied, where the time-reversal symmetry is broken and the valley degeneracy is lifted. The considered superlattice is composed of two different barriers, providing more degrees of freedom for engineering the electronic structure. The electrons near the K and K' valleys are dominated by different effective superlattices. It is found that the energy bands for both valleys are symmetric with respect to ky=-(AM+ξ AS) /4 under the symmetric superlattices. More finite-energy Dirac points, more prominent collimation behavior, and new crossing points are found for K' valley. The degenerate miniband near the K valley splits into two subminibands and produces a new band gap under the asymmetric superlattices. The velocity for the K' valley is greatly renormalized compared with the K valley, and so we can achieve a finite velocity for the K valley while the velocity for the K' valley is zero. Especially, the miniband and band gap could be manipulated independently, leading to an increase of the conductance. The characteristics of the band structure are reflected in the transmission spectra. The Dirac points and the crossing points appear as pronounced peaks in transmission. A remarkable valley polarization is obtained which is robust to the disorder and can be controlled by the strain, the period, and the voltage.

  16. Ruthenium nanoparticles in ionic liquids: structural and stability effects of polar solutes.

    Science.gov (United States)

    Salas, Gorka; Podgoršek, Ajda; Campbell, Paul S; Santini, Catherine C; Pádua, Agílio A H; Costa Gomes, Margarida F; Philippot, Karine; Chaudret, Bruno; Turmine, Mireille

    2011-08-14

    Ionic liquids are a stabilizing medium for the in situ synthesis of ruthenium nanoparticles. Herein we show that the addition of molecular polar solutes to the ionic liquid, even in low concentrations, eliminates the role of the ionic liquid 3D structure in controlling the size of ruthenium nanoparticles, and can induce their aggregation. We have performed the synthesis of ruthenium nanoparticles by decomposition of [Ru(COD)(COT)] in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C(1)C(4)Im][NTf(2)], under H(2) in the presence of varying amounts of water or 1-octylamine. For water added during the synthesis of metallic nanoparticles, a decrease of the solubility in the ionic liquid was observed, showed by nanoparticles located at the interface between aqueous and ionic phases. When 1-octylamine is present during the synthesis, stable nanoparticles of a constant size are obtained. When 1-octylamine is added after the synthesis, aggregation of the ruthenium nanoparticles is observed. In order to explain these phenomena, we have explored the molecular interactions between the different species using (13)C-NMR and DOSY (Diffusional Order Spectroscopy) experiments, mixing calorimetry, surface tension measurements and molecular simulations. We conclude that the behaviour of the ruthenium nanoparticles in [C(1)C(4)Im][NTf(2)] in the presence of 1-octylamine depends on the interaction between the ligand and the nanoparticles in terms of the energetics but also of the structural arrangement of the amine at the nanoparticle's surface. PMID:21603700

  17. Inversion of single-station teleseismic P-wave polarization-data for the velocity structure of Beijing area

    Institute of Scientific and Technical Information of China (English)

    LIU; Futian; (

    2001-01-01

    [1]Pavlis, G. L., Booker, J. R., Progressive multiple event location (PMEL), Bull. Seismol. Soc. Am., 1983, 73: 1753.[2]Dziewonski, A. M., Anderson, D. L., Travel times and station corrections for P-waves at teleseismic distances, J. Geophys. Res., 1983, 88: 3295.[3]Hu Ge, Menke, W., Formal inversion of laterally heterogeneous velocity structure from P-wave polarization data, Geophys. J. Int., 1992. 110: 63.[4]Menke, W., Lerner-Lam, A., Transition from linear to complex polarization in short period compressional waves, Bull. Seismol. Soc. Am., 1991, 81: 611.[5]Hu Ge, Menke, W., Rognvaldsson, S., A demonstration of the joint use of p-wave polarization and travel-time data in tomographic inversion: crustal velocity structure near the south Iceland Lowland network, Geophys. Res. Letters, 1993, 20(13): 1407.[6]Teng, J., Yao, H., Chou, H., Crustal structure in the Beijing-Tianjin-Tangshan-Zhangjiakou region, Acta Geophysica Sinica(in Chinese), 1979, 22(3): 218.[7]Shao, X., Zhang, J., Chen, X. et al., The results of deep sounding by using converted waves of earthquakes in the Beijing-Tianjin-Tangshan region, Seismology and Geology(in Chinese), 1980: 2(2): 12.[8]Wei, M., Shi, Z., Yin, X. et al., The basic configuration of crustal structure in North China region and its relation to the earthquakes from gravimetric date, Seismology and Geology(in Chinese), 1980, 2(2): 55.[9]Jin Anshu, Liu Futian, Sun Yongzhi, Three-dimensional P velocity structure of the crust and upper Mantle under Beijing region, Acta Geophysica Sinica(in Chinese), 1980, 23(2): 172.[10]Vidale, J.E., Complex polarization analysis of particle motion, Bull. Seismol. Soc. Am., 1986, 76: 1393.[11]Jurkevics, A., Polarization analysis of three-component array data, Bull, Seismol. Soc. Am., 1988, 78: 1725.[12]Park, J., Vernon, F. L., Lindberg, C.R., Frequency dependent polarization analysis of high-frequency seismograms, J. Geophys. Res., 1987, 92: 12664.[13

  18. Electric-field-induced structural changes in water confined between two graphene layers

    Science.gov (United States)

    Sobrino Fernández, Mario; Peeters, F. M.; Neek-Amal, M.

    2016-07-01

    An external electric field changes the physical properties of polar liquids due to the reorientation of their permanent dipoles. Using molecular dynamics simulations, we predict that an in-plane electric field applied parallel to the channel polarizes water molecules which are confined between two graphene layers, resulting in distinct ferroelectricity and electrical hysteresis. We found that electric fields alter the in-plane order of the hydrogen bonds: Reversing the electric field does not restore the system to the nonpolar initial state, instead a residual dipole moment remains in the system. The square-rhombic structure of 2D ice is transformed into two rhombic-rhombic structures. Our study provides insights into the ferroelectric state of water when confined in nanochannels and shows how this can be tuned by an electric field.

  19. Images of Polar Bears and Penguins, Storms, Deforestation and More - Middle School Students Perceptions of Climate Change

    Science.gov (United States)

    Gopal, S.; Melaas, E. K.; Malmrose, M.; Mullokandov, A.

    2014-12-01

    Global change studies aim to foster a deeper understanding of the causes and consequences of global change on planet Earth. The study of global change presents a rich domain of inquiry, exploration, and discovery at all grade levels. The main objective of this exploratory study was to assess middle school students' perceptions of global change as part of their participation in the NSF GK12 program called GLACIER (Global Change Initiative - Education and Research) during the academic year 2012-13. The middle schools are located in the Metro Boston area. As part of the program, participating students were asked to draw pictures of their perceptions and ideas on global change. The drawings of 150 children, ages 11 to 13, were qualitatively analyzed. The analysis focused on (a) the type of concepts children chose to convey, (b) the specific context of the global change described (polar bears in floating glaciers), (c) students direct representation of anthropocentric impacts (such as pollution or deforestation), and (d) the match between students concepts and the recent IPCC reports. About 20% of the students focused on the iconic imagery of the melting glaciers and impact on animals such as penguins and polar bears, more than 25% focused on natural disasters (such as storms, sea level changes) while 30% focused on urban problems. These concepts are matched with the recent IPCC report. These results are notable and suggest students in middle schools understand the varied dimensions of global change and the role of human activities in bringing about change. Students' perspectives may help in developing a suitable curriculum using existing science standards to discuss this significant topic in middle school classrooms. In addition, students' drawings illustrate their perception of the coupled human and natural systems.

  20. Horizontal Structure of Dynamical Instability at Marine Stratocumulus Cloud Top Revealed in Polarized Light

    Science.gov (United States)

    Davis, A. B.; Diner, D. J.; Matheou, G.; Teixeira, J.; Qu, Z.; Emde, C.

    2014-12-01

    Marine stratocumulus (Sc) layers cover vast regions and, due to their high opacities, they play a major role in the Earth's solar radiation budget. They also have remarkably flat upper boundaries due to strong gradients in relative humidity at the top of the boundary layer (BL). However, those very gradients are unstable at scales as small as meters depending on fluctuations of temperature and liquid water content, hence radiative cooling in the thermal IR. The ensuing turbulent mixing of moist and dry air at cloud top due to such small-scale dynamical processes is not benign. It controls the structure of the entire marine BL, hence the Sc life-cycle, hence large-scale subsidence, hence global circulation and, ultimately, climate. This physical connection across many orders of magnitude in scale makes the prognosis and microphysical parameterization of marine Sc particularly challenging for climate modelers. It also makes these clouds high-value targets for remote sensing, both space-based and airborne. Airborne sensors can easily achieve the resolution required to image cloud-top instabilities but natural sunlight is so highly scattered that the finest spatial features are all but erased by the "radiative smoothing" process. However, we will show that JPL's Airborne Multi-angle Spectro-Polarimetric Imager (AirMSPI), which flies on NASA's ER-2 aircraft at 20 km altitude, reveals in near-backscattered polarized light the previously unseen horizontal structure of the marine Sc cloud top physics and dynamics at 10 m resolution across a 10 km swath. It appears as a complex network of meandering filaments. Large-Eddy Simulation modeling of these oceanic clouds with bin microphysics and state-of-the-art polarized 3D radiative transfer have been harnessed to model AirMSPI observations of the first three Stokes vector components in the relevant observational geometry for a 2.5x2.5 km^2 region. Synthetic imagery obtained at JPL's High-Performance Computing facility shows

  1. Fabrication of Proton-Exchange Waveguide Using Stoichiometric LiTaO3 for Guided Wave Electrooptic Modulators with Polarization-Reversed Structure

    Directory of Open Access Journals (Sweden)

    Hiroshi Murata

    2008-01-01

    Full Text Available Optical waveguides were fabricated on z-cut stoichiometric LiTaO3 (SLT by using the proton-exchange method. The surface index change for the extraordinary ray on the SLT substrate resulting from the proton exchange was 0.017, which coincided well with congruent LiTaO3 substrates. The proton exchange coefficient in the SLT was 0.25×10−12 cm2/s. The application of the SLT waveguide to a quasi-velocity-matched travelling-wave electrooptic modulator with periodically polarization-reversed structure is also reported.

  2. Changing Structures; Changing Rules: The Development of the "Internal Market."

    Science.gov (United States)

    Penney, D.; Evans, J.

    1995-01-01

    Explores the 1988 Education Reform Act's effects on providing physical education and sports in British schools, and specifically, implementation of the National Curriculum for Physical Education. The ERA and local school management have not only changed interschool and school-government agency relationships, but have fostered potentially damaging…

  3. Carrier-envelope-phase effects and V-like structure in nonsequential double ionization by elliptical polarization

    Science.gov (United States)

    Li, Yingbin; Yu, Benhai; Tang, Qingbin; Hua, Duanyang; Tong, Aihong; Jiang, Chenghuan; Shen, Naifeng; Li, Yongchao; Ge, Guixian; Wan, Jianguo

    2016-07-01

    The nonsequential double ionization (NSDI) of atom is revisited by elliptically polarized few-cycle laser pulse with the classical ensemble method. We focus on the events that both electrons emit into the same direction along the long and short axis of the laser polarization plane, and how do the correlated electron momentum spectra of these two events depends on the carrier-envelope-phase (CEP). We first exhibit that the double-ionization probability has a negligible dependence on CEP. Back analysis shows that the ionization dynamics of the second electron are strongly depend on the CEP, which is significantly responsible for the CEP-dependent correlated electron momentum spectra. Besides, the correlated electron momentum spectrum along the long axis of the laser polarization plane reproduces the so-called V-like structure (also called the figurelike structure) observed in experiments [A. Staudte, et al., Phys. Rev. Lett. 99, 263002 (2007); A. Rudenko, et al., Phys. Rev. Lett. 99, 263003 (2007)]. We sort the V-like shape into two regions and find that the different regions exhibit significantly different dynamics behaviors. Simultaneously, we demonstrate that the electron pairs emitted into the same direction along the short axis of the laser polarization plane is a result of the nuclear-electron attraction, and both the nuclear-electron attraction and e-e repulsion significantly contribute to the V-like structure.

  4. Geological connectivity drives microbial community structure and connectivity in polar, terrestrial ecosystems.

    Science.gov (United States)

    Ferrari, Belinda C; Bissett, Andrew; Snape, Ian; van Dorst, Josie; Palmer, Anne S; Ji, Mukan; Siciliano, Steven D; Stark, Jonathon S; Winsley, Tristrom; Brown, Mark V

    2016-06-01

    Landscape heterogeneity impacts community assembly in animals and plants, but it is not clear if this ecological concept extends to microbes. To examine this question, we chose to investigate polar soil environments from the Antarctic and Arctic, where microbes often form the major component of biomass. We examined soil environments that ranged in connectivity from relatively well-connected slopes to patchy, fragmented landforms that comprised isolated frost boils. We found landscape connectedness to have a significant correlation with microbial community structure and connectivity, as measured by co-occurrence networks. Soils from within fragmented landforms appeared to exhibit less local environmental heterogeneity, harboured more similar communities, but fewer biological associations than connected landforms. This effect was observed at both poles, despite the geographical distances and ecological differences between them. We suggest that microbial communities inhabiting well-connected landscape elements respond consistently to regional-scale gradients in biotic and edaphic factors. Conversely, the repeated freeze thaw cycles that characterize fragmented landscapes create barriers within the landscape and act to homogenize the soil environment within individual frost boils and consequently the microbial communities. We propose that lower microbial connectivity in the fragmented landforms is a function of smaller patch size and continual disturbances following soil mixing. PMID:26310523

  5. Polarization dependent soft x-ray spectro-microscopy of local spin structures

    Science.gov (United States)

    Robertson, Maccallum; Agostino, Christopher; Im, Mi-Young; Montoya, Sergio; Fullerton, Eric; Fischer, Peter

    Quantitative information about element-specific contributions to local magnetic spin and orbital moments is readily available by XMCD spectroscopy and images of magnetic domain patterns with a few tens of nanometer spatial resolution. We show that the x-ray spectroscopic analysis of x-ray microscopy images provides quantitative information about local spin structures. We have investigated two prototypical multilayered PMA film systems prepared by sputtering, specifically (Co 0.3 nm/Pt 0.5 nm)x30 and (Fe 0.7nm/Gd 0.4nm)x100 systems. A spectroscopic sequence of full-field magnetic transmission soft x-ray microscopy (MTXM) images covering about 8mm field-of-views with a spatial resolution of about 20nm were recorded across the Co and Fe L edges, resp. To modulate the magnetic contrast, two sets of images were obtained with left and right circular polarization. Standard XMCD spectroscopy analysis procedures were applied to retrieve the local spectroscopic behavior. We observe a decrease of the L3/L2 ratio when approaching the domain walls, indicating a non-uniform spin configuration along the vertical profile of a domain, which we will discuss in view of both systems' magnetic anisotropies. U.S. DOE under Contract No. DE-AC02-05-CH11231.

  6. Structures of chiral smectic-C mesophases revealed by polarization-analyzed resonant x-ray scattering

    International Nuclear Information System (INIS)

    We report polarization-analyzed, resonant x-ray diffraction at the sulfur K edge performed upon free-standing liquid-crystal films. Our studies of the thiobenzoate liquid-crystal enantiomer 10OTBBB1M7 yield the polarization states of resonant satellite peaks arising from characteristic superlattices in the chiral smectic-C (SmC*) variant phases, including the antiferroelectric SmCA*, ferrielectric SmCFI1* and SmCFI2*, as well as SmCα*. The observed polarizations agree with the clock model of chiral smectic-C variants, and rule out other proposals made to date for these structures. Data from the 10OTBBB1M7 racemate also support the clock model. Our resonant diffraction results from a thiophene liquid-crystal compound reveal the same superlattice periodicities seen in corresponding antiferroelectric and ferrielectric phases of 10OTBBB1M7. (c) 1999 The American Physical Society

  7. The vast polar structure of the Milky Way attains new members

    Energy Technology Data Exchange (ETDEWEB)

    Pawlowski, Marcel S. [Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106 (United States); Kroupa, Pavel, E-mail: marcel.pawlowski@case.edu [Helmholtz-Institut für Strahlen-und Kernphysik, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 14-16, D-53115 Bonn (Germany)

    2014-07-20

    The satellite galaxies of the Milky Way (MW) align with and preferentially orbit in a vast polar structure (VPOS), which also contains globular clusters (GCs) and stellar and gaseous streams. Similar alignments have been discovered around several other host galaxies. We test whether recently discovered objects in the MW halo, the satellite galaxy/GC transition object named PSO J174.0675-10.8774 or Crater and three stellar streams, are part of the VPOS. Crater is situated close to the VPOS. Incorporating the new object in the VPOS-plane fit slightly improves the alignment of the plane with other features such as the Magellanic stream and the average orbital plane of the satellites co-orbiting in the VPOS. We predict Crater's proper motion by assuming that it, too, orbits in the VPOS. One of the three streams aligns well with the VPOS. Surprisingly, it appears to lie in the exact same orbital plane as the Palomar 5 stream and shares its distance, suggesting a direct connection between the two. The stream also crosses close to the Fornax dwarf galaxy and is oriented approximately along the galaxy's direction of motion. The two other streams cannot align closely with the VPOS because they were discovered in the direction of M31/M33, which is outside of the satellite structure. The VPOS thus attains two new members. This further emphasizes that the highly anisotropic and correlated distribution of satellite objects requires an explanation beyond the suggestion that the MW satellite system is an extreme statistical outlier of a ΛCDM sub-halo system.

  8. Family Structure, Intergenerational Mobility, and the Reproduction of Poverty: Evidence for Increasing Polarization?

    OpenAIRE

    Musick, Kelly; Mare, Robert D.

    2003-01-01

    A substantial body of research demonstrates links between poverty and family structure from one generation to the next, but leaves open key questions about the implications of these associations for aggregate-level change. To what extent does intergenerational inheritance affect trends in poverty and single parenthood over time? This paper examines how patterns of intergenerational inheritance play out in the population over the long run, using data from the National Longitudinal Surveys and ...

  9. 偏光片知识讲座第四讲偏光片的结构和制造%A Course of Polarizer Knowledge Part Four The Structure and Manufacture of Polarizer

    Institute of Scientific and Technical Information of China (English)

    范志新

    2012-01-01

    This paper summarize the polarizer knowledge in detailed, include about of the invention and application of polarizer, the basic of polarization optics, the principle of polarizing devices, the structure and manufacture of polarizer, the properties and examination of polarizer, and the technology development and market state of polarizer. It have a common direct sense for new recruits in polarizer industry and a refer value for polarizer research workers.%全文详细综述偏光片的发明和应用、偏振光学基础、偏振元件原理、偏光片的结构、制造、性能、检测、实验、技术发展、产业现状、市场前景等系列知识,文章对于从事偏光片生产和应用工作的新成员具有入门指导意义,对于偏光片研究者也具有一定的参考价值。

  10. Polarized Raman study on the lattice structure of BiFeO3 films prepared by pulsed laser deposition

    KAUST Repository

    Yang, Yang

    2014-11-01

    Polarized Raman spectroscopy was used to study the lattice structure of BiFeO3 films on different substrates prepared by pulsed laser deposition. Interestingly, the Raman spectra of BiFeO3 films exhibit distinct polarization dependences. The symmetries of the fundamental Raman modes in 50-700 cm-1 were identified based on group theory. The symmetries of the high order Raman modes in 900-1500 cm-1 of BiFeO3 are determined for the first time, which can provide strong clarifications to the symmetry of the fundamental peaks in 400-700 cm-1 in return. Moreover, the lattice structures of BiFeO3 films are identified consequently on the basis of Raman spectroscopy. BiFeO3 films on SrRuO3 coated SrTiO3 (0 0 1) substrate, CaRuO3 coated SrTiO3 (0 0 1) substrate and tin-doped indium oxide substrate are found to be in the rhombohedral structure, while BiFeO3 film on SrRuO3 coated Nb: SrTiO3 (0 0 1) substrate is in the monoclinic structure. Our results suggest that polarized Raman spectroscopy would be a feasible tool to study the lattice structure of BiFeO3 films.

  11. Polarization structure of 12 gamma-ray quasars at 5 and 15 GHz

    Science.gov (United States)

    Vetukhnovskaya, Yu. N.; Gabuzda, D. C.

    2012-12-01

    The results of dual-frequency polarization observations of 12 gamma-ray quasars are presented (as a continuation of a study of six blazars carried out earlier). The observations were obtained with the American Very Long Baseline Array. The distributions of intensity and polarization were obtained at 5 and 15 GHz. The degrees of polarization in the cores and jets of the 18 gamma-ray quasars do not stand out from those of other quasars. The brightness temperatures of the core components do not strongly exceed 1012 K.

  12. Sensitivity of polar stratospheric cloud formation to changes in water vapour and temperature

    Directory of Open Access Journals (Sweden)

    F. Khosrawi

    2015-07-01

    Full Text Available More than a decade ago it was suggested that a cooling of stratospheric temperatures by 1 K or an increase of 1 ppmv of stratospheric water vapour could promote denitrification, the permanent removal of nitrogen species from the stratosphere by solid polar stratospheric cloud (PSC particles. In fact, during the two Arctic winters 2009/10 and 2010/11 the strongest denitrification in the recent decade was observed. Sensitivity studies along air parcel trajectories are performed to test how a future stratospheric water vapour (H2O increase of 1 ppmv or a temperature decrease of 1 K would affect PSC formation. We perform our study based on measurements made during the Arctic winter 2010/11. Air parcel trajectories were calculated 6 days backward in time based on PSCs detected by CALIPSO (Cloud Aerosol Lidar and Infrared Pathfinder satellite observations. The sensitivity study was performed on single trajectories as well as on a trajectory ensemble. The sensitivity study shows a clear prolongation of the potential for PSC formation and PSC existence when the temperature in the stratosphere is decreased by 1 K and water vapour is increased by 1 ppmv. Based on 15 years of satellite measurements (2000–2014 from UARS/HALOE, Envisat/MIPAS, Odin/SMR, Aura/MLS, Envisat/SCIAMACHY and SCISAT/ACE-FTS it is further investigated if there is a decrease in temperature and/or increase of water vapour (H2O observed in the polar regions similar to that observed at midlatitudes and in the tropics. Although in the polar regions no significant trend is found in the lower stratosphere, we found from the observations a correlation between cold winters and enhanced water vapour mixing ratios.

  13. The Effect of Changes in Polar Sea Ice on Emissions of Marine Aerosols

    Science.gov (United States)

    Matrai, P.; Gabric, A. J.

    2015-12-01

    Cloud radiative effects remain a major weakness in our understanding of the climate system and consequently in developing accurate climate projections. This is mainly true for Arctic low-level clouds in their key role of regulating surface energy fluxes which affect the freezing and melting of sea ice. The radiative properties of clouds are strongly dependent on the number concentration of airborne water-soluble particles, known as cloud condensation nuclei (CCN). In the Arctic, the aerosol-cloud-radiation relationship is more complex than elsewhere and the clouds constitute a warming factor for climate, rather than cooling, most of the year. This is due to the semi-permanent ice cover, which raises the albedo of the surface, and the clean Arctic air, which decreases the albedo of the clouds. There has been much discussion on the relative magnitude of the biogenic source of polar CCN: Primary organic marine aerosols and/or sulfate-containing aerosols, derived from marine emissions. Regional field measurements and pan- (Ant)Arctic model simulations don't necessarily agree. Arctic CCN are formed primarily by aggregates of marine organic material and may grow in mass by condensation. Southern Ocean aerosols may be dominated by sulfate particles and organic particles at lower and higher Antarctic latitudes, respectively. The interaction of polar marine microorganisms, seasonality, sea ice cover, presence or absence of sea spray, and atmospheric heterogeneous processes combine to control natural aerosol concentrations and mass, thus modulating the sensitivity of cloud properties, including their reflectivity and the resulting regional radiation budget. We discuss Arctic and Antarctic field and satellite observations and establish a strong and fundamental link between the biology at the ocean/sea ice interface, clouds and climate over polar regions.

  14. Relative Energy Dissipation: Sensitive to Structural Changes of Liquids

    Institute of Scientific and Technical Information of China (English)

    祖方遒; 郭丽君; 朱震刚; 凤仪

    2002-01-01

    Energy dissipation techniques, widely used in solid physics previously, are proven to be sensitive also to changes in liquid structure. It has been suggested from relative energy dissipation that changes in liquid structure can occur as a function of temperature in some ordinary binary systems such as Pb-Sn, In-Sn and In-Bi. This finding may be helpful to understand liquid structure changing patterns, therefore enriching the phenomenology of liquid state physics. This is significant for engineering practices.

  15. Generalized focusing of time-lapse changes with applications to direct current and time-domain induced polarization inversions

    Science.gov (United States)

    Fiandaca, Gianluca; Doetsch, Joseph; Vignoli, Giulio; Auken, Esben

    2015-11-01

    Often in geophysical monitoring experiments time-lapse inversion models vary too smoothly with time, owing to the strong imprint of regularization. Several methods have been proposed for focusing the spatiotemporal changes of the model parameters. In this study, we present two generalizations of the minimum support norm, which favour compact time-lapse changes and can be adapted to the specific problem requirements. Inversion results from synthetic direct current resistivity models that mimic developing plumes show that the focusing scheme significantly improves size, shape and magnitude estimates of the time-lapse changes. Inversions of the synthetic data also illustrate that the focused inversion gives robust results and that the focusing settings are easily chosen. Inversions of full-decay time-domain induced polarization (IP) field data from a CO2 monitoring injection experiment show that the focusing scheme performs well for field data and inversions for all four Cole-Cole polarization parameters. Our tests show that the generalized minimum support norms react in an intuitive and predictable way to the norm settings, implying that they can be used in time-lapse experiments for obtaining reliable and robust results.

  16. Towards a process-based understanding of Holocene polar climate change. Using glacier-fed lake sediments from Arctic Svalbard and Antarctic South Georgia

    OpenAIRE

    Bilt, Willem van der

    2016-01-01

    Earth`s polar regions are undergoing dramatic changes due to ongoing climate change as demonstrated by increasing temperatures, collapsing ice shelves, Arctic sea ice loss and rapid glacier retreat. Driving an accelerating rise in global sea level, this amplified regional response may have devastating global socio-economic consequences in the foreseeable future. Yet the causes and range of polar climate variability remain poorly understood as observational records are short and fragmentary, w...

  17. Hierarchical super-structure identified by polarized light microscopy, electron microscopy and nanoindentation: Implications for the limits of biological control over the growth mode of abalone sea shells

    Directory of Open Access Journals (Sweden)

    Schneider Andreas S

    2012-09-01

    Full Text Available Abstract Background Mollusc shells are commonly investigated using high-resolution imaging techniques based on cryo-fixation. Less detailed information is available regarding the light-optical properties. Sea shells of Haliotis pulcherina were embedded for polishing in defined orientations in order to investigate the interface between prismatic calcite and nacreous aragonite by standard materialographic methods. A polished thin section of the interface was prepared with a defined thickness of 60 μm for quantitative birefringence analysis using polarized light and LC-PolScope microscopy. Scanning electron microscopy images were obtained for comparison. In order to study structural-mechanical relationships, nanoindentation experiments were performed. Results Incident light microscopy revealed a super-structure in semi-transparent regions of the polished cross-section under a defined angle. This super-structure is not visible in transmitted birefringence analysis due to the blurred polarization of small nacre platelets and numerous organic interfaces. The relative orientation and homogeneity of calcite prisms was directly identified, some of them with their optical axes exactly normal to the imaging plane. Co-oriented "prism colonies" were identified by polarized light analyses. The nacreous super-structure was also visualized by secondary electron imaging under defined angles. The domains of the super-structure were interpreted to consist of crystallographically aligned platelet stacks. Nanoindentation experiments showed that mechanical properties changed with the same periodicity as the domain size. Conclusions In this study, we have demonstrated that insights into the growth mechanisms of nacre can be obtained by conventional light-optical methods. For example, we observed super-structures formed by co-oriented nacre platelets as previously identified using X-ray Photo-electron Emission Microscopy (X-PEEM [Gilbert et al., Journal of the

  18. Polarization structure of six gamma-ray quasars at 5 and 15 GHz

    Science.gov (United States)

    Vetukhnovskaya, Yu. N.; Gabuzda, D. C.; Yakimov, V. E.

    2011-05-01

    The results of 5 and 15 GHz polarization observations of the six blazars 1222+216, 1406-076, 1606+106, 1611+343, 17415-038, and 2022-077 obtained on the American Very Long Baseline Array are presented. The degrees of polarization in the cores and jets of these six gamma-ray quasars do not differ from those for other blazars.

  19. Upgrade and Design of Coastal Structures Exposed to Climate Changes

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Quvang Harck

    This thesis "Upgrade and Design of Coastal Structures Exposed to Climate Changes" evaluates the performance of existing types of structures when exposed to climate changes. This includes also the potential of using cost‐sharing multipurpose structures for protection against the effects of future...... climate changes. The thesis consists of three parts. The first part evaluates the performance of existing design formulae for estimation of wave actions on structures, especially in shallow water since these structures are most vulnerable to the rising sea water levels caused by climate changes. Existing...... of coastal protection structures, which are extended to a wider range of wave conditions, and which can be used to more accurately estimate the influence from climate changes. In the second part of the thesis, the extended and modified formulae are used in case studies to evaluate the influence from climate...

  20. The Evolving Risk of Climate Change and National Security: People not Polar Bears

    Science.gov (United States)

    Titley, D.

    2014-12-01

    This talk will provide a general overview of climate change and discuss why this is a national security issue. Climate change is about people, about water, and about change itself. Understanding the rate of climate change, relative to the abilities of both humans and ecosystems to adapt is critical. I will briefly describe the multiple, independent lines of evidence that the climate is changing, and that the primary cause of this change is a change in atmospheric composition caused by the burning of fossil fuels. I will cover the history of climate change as seen within the U.S. Department of Defense and U.S. Navy, how this challenge is being addressed from budgetary, policy, and political angles, and what are the greatest challenges to national security that arise from climate change and in particular, the associated changes in the Arctic. I will conclude with an assessment of future challenges and opportunities regarding climate change, from science, policy, and political perspectives, and why we know enough to take significant action now, even if we don't know every detail about the future. In addition, this talk will address how to effectively talk about climate change through the use of analogies, plain, non-jargon English, and even a little humor.

  1. Structural change in OECD comparative advantage

    NARCIS (Netherlands)

    Brakman, Steven; Inklaar, Robert; Van Marrewijk, Charles

    2013-01-01

    In the post-war period, the goods composition of trade in Organisation for Economic Cooperation and Development (OECD) countries has changed considerably. We analyze the evolution of comparative advantage using a detailed trade data set and a new analytical tool: the Harmonic Mass index (HM index),

  2. Particle dynamics and spatial $e^-e^+$ density structures at QED cascading in circularly polarized standing waves

    CERN Document Server

    Bashinov, A V; Kim, A V

    2016-01-01

    We present a comprehensive analysis of longitudinal particle drifting in a standing circularly polarized wave at extreme intensities when quantum radiation reaction (RR) effects should be accounted for. To get an insight into the physics of this phenomenon we made a comparative study considering the RR force in the Landau-Lifshitz or quantum-corrected form, including the case of photon emission stochasticity. It is shown that the cases of circular and linear polarization are qualitatively different. Moreover, specific features of particle dynamics have a strong impact on spatial structures of the electron-positron ($e^-e^+$) density created in vacuum through quantum electrodynamic (QED) cascades in counter-propagating laser pulses. 3D PIC modeling accounting for QED effects confirms realization of different pair plasma structures.

  3. Probing the magnetic field structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations

    CERN Document Server

    Gold, Roman; Johnson, Michael D; Doeleman, Sheperd S

    2016-01-01

    Magnetic fields are believed to drive accretion and relativistic jets in black hole accretion systems, but the magnetic-field structure that controls these phenomena remains uncertain. We perform general relativistic (GR) polarized radiative transfer of time-dependent three-dimensional GR magnetohydrodynamical (MHD) simulations to model thermal synchrotron emission from the Galactic Center source Sagittarius A$^\\ast$ (Sgr A*). We compare our results to new polarimetry measurements by the Event Horizon Telescope (EHT) and show how polarization in the visibility (Fourier) domain distinguishes and constrains accretion flow models with different magnetic field structures. These include models with small-scale fields in disks driven by the magnetorotational instability (MRI) as well as models with large-scale ordered fields in magnetically-arrested disks (MAD). We also consider different electron temperature and jet mass-loading prescriptions that control the brightness of the disk, funnel-wall jet, and Blandford-...

  4. Planck intermediate results XXXVIII. E- and B-modes of dust polarization from the magnetized filamentary structure of the interstellar medium

    DEFF Research Database (Denmark)

    Ade, P. A. R.; Aghanim, N.; Arnaud, M.;

    2016-01-01

    fraction of the filaments to be 11%. Furthermore, we show that the correlation between the filaments and the magnetic field orientations may account for the E and B asymmetry and the C-l(TE)/C-l(EE) ratio, reported in the power spectra analysis of the Planck 353 GHz polarization maps. Future models...... of the dust foreground for CMB polarization studies will need to take into account the observed correlation between the dust polarization and the structure of interstellar matter....

  5. Structural changes in bunched crystalline ion beams

    International Nuclear Information System (INIS)

    Measurements of the spatial distribution of bunched crystalline ion beams in the radio frequency quadrupole storage ring PALLAS are presented for different ratios of the longitudinal and the transverse confinement strengths. The length of highly elongated crystalline ion bunches and its dependence on the bunching voltage is compared to predictions for a one-dimensional ion string and three-dimensional space-charge-dominated beams. The length is found to be considerably shorter than that predicted by the models. Furthermore, the scaling of the length with the bunching voltage is shown to differ from the expected inverse cube root scaling. These differences can partially be attributed to the formation of a mixed crystalline structure. Additionally, a concise mapping of the structural transition from a string to a zig-zag configuration as a function of the ratio of the confinement strengths is presented, which in a similar way deviates from the predictions

  6. Structural changes in bunched crystalline ion beams

    CERN Document Server

    Bussmann, M; Schätz, T; Habs, D

    2003-01-01

    Measurements of the spatial distribution of bunched crystalline ion beams in the radio frequency quadrupole storage ring PALLAS are presented for different ratios of the longitudinal and the transverse confinement strengths. The length of highly elongated crystalline ion bunches and its dependence on the bunching voltage is compared to predictions for a one-dimensional ion string and three-dimensional space-charge-dominated beams. The length is found to be considerably shorter than that predicted by the models. Furthermore, the scaling of the length with the bunching voltage is shown to differ from the expected inverse cube root scaling. These differences can partially be attributed to the formation of a mixed crystalline structure. Additionally, a concise mapping of the structural transition from a string to a zig-zag configuration as a function of the ratio of the confinement strengths is presented, which in a similar way deviates from the predictions.

  7. Population and Employment Densities: Structure and Change

    OpenAIRE

    Small, Kenneth A.; Song, Shunfeng

    1994-01-01

    We examine spatial patterns and their changes during the 1970s for the Los Angeles region, by estimating monocentric and polycentric density functions for employment and population. Downtown Los Angeles is clearly identified as the statistical monocentric center of the region, and it is the most consistently strong center in the polycentric patterns. Polycentric models fit statistically better than monocentric models, and there was some shift in employment distribution toward a more polycentr...

  8. Leading Change: Faculty Development through Structured Collaboration

    Directory of Open Access Journals (Sweden)

    Suzanne Painter

    2015-06-01

    Full Text Available There are relentless calls for innovation in higher education programs in response to media and policy-makers attention to such concerns as instructional quality, relevance to employment, costs, and time-to-degree. At the same time, the individual course remains the primary unit of instruction and there is little evidence of faculty development strategies to assist with changing core instructional practices. We faced that dilemma when we led an innovative doctoral program in educational leadership. Soon after beginning, we implemented a regular meeting of all faculty members teaching and advising in the program to address upcoming events and review student progress. Our retrospective analysis indicates that these meetings evolved as a practical and sustainable framework for faculty development in support of deep change for instructional practices. Here we describe the challenge of faculty development for change and draw lessons learned from our four years of leadership centered on experiential learning and community sense-making. We hope that program leaders who aspire to promote faculty development in conjunction with graduate program implementation will find these lessons useful.

  9. Probing structural changes of self assembled i-motif DNA

    KAUST Repository

    Lee, Iljoon

    2015-01-01

    We report an i-motif structural probing system based on Thioflavin T (ThT) as a fluorescent sensor. This probe can discriminate the structural changes of RET and Rb i-motif sequences according to pH change. This journal is

  10. Political attitudes in adolescence and emerging adulthood: Developmental changes in mean level, polarization, rank-order stability, and correlates.

    Science.gov (United States)

    Rekker, Roderik; Keijsers, Loes; Branje, Susan; Meeus, Wim

    2015-06-01

    This three-wave cohort-sequential longitudinal study (N = 1302) examined the development of two core political attitudes, economic egalitarianism and ethnocentrism, among Dutch youths between age 12 and 31. Longitudinal regression analyses revealed a curvilinear mean level development for both attitudes, reflecting an increased disagreement with economic redistribution and multiculturalism around late adolescence. Furthermore, attitudes became decreasingly polarized (i.e., less extreme) and increasingly stable with age. Finally, several effects of attitudes' correlates gradually changed: The effect of educational level on ethnocentrism increased with age, whereas the effect of gender diminished. Regional effects on ethnocentrism developed as youths resided in a new area. No age-related change was found in the effect of parental SES. Overall, these findings support the idea that attitudes mature during the formative phase of adolescence and that this process slows down during emerging adulthood. Furthermore, these results support developmental explanations for the association between attitudes and their correlates. PMID:25880889

  11. Investigation of the electronic structure of CuPc on Cu(100) interfaces using ARUPS with polarized light

    Energy Technology Data Exchange (ETDEWEB)

    Wiessner, Michael; Haeming, Marc; Forster, Frank; Schoell, Achim [Universitaet Wuerzburg, Experimentelle Physik II, D-97074 Wuerzburg (Germany); Reinert, Friedrich [Universitaet Wuerzburg, Experimentelle Physik II, D-97074 Wuerzburg (Germany); Forschungszentrum Karlsruhe, Gemeinschaftslabor fuer Nanoanalytik, D-76021 Karlsruhe (Germany)

    2009-07-01

    The understanding of the electronic structure at metal-organic interfaces is crucial for electronic devices since it determines the charge transport through metal-organic contacts. Particularly if chemical interaction occurs, as it is the case between most aromatic organic molecules and metals, the hybridization of molecule and metal wave functions effects both the energy position and the symmetry of the involved orbitals. Consequently, the dipole matrix element, i.e. the intensity of a photoemission signal, will be influenced. This phenomenon can thus be utilized as a sensitive probe for the interfacial interaction and the character of the involved molecular and metal states. We report on an investigation of the adsorption of ultra-thin Cu-phthalocyanine films on Cu(100) surfaces by means of angular resolved photoemission spectroscopy (ARPES) with polarized light. By using a monochromatized HeI{sub {alpha}} source with a high degree of polarization and with variable polarization direction we observe polarization-dependent intensities for signals from the substrate, from the adsorbate molecules, and from interface states which are generated due to the chemisorption. The evaluation of these variations in intensity shows that the applied method is a usefull tool for understanding the interaction mechanisms.

  12. Local structure changes of Cu55 cluster during heating

    Institute of Scientific and Technical Information of China (English)

    Zhang Lin; Zhang Cai-Bei; Qi Yang

    2007-01-01

    The structural relaxation of a cluster containing 55 atoms at elevated temperatures is simulated by molecular dynamics. The interatomic interactions are given by using the embedded atom method (EAM) potential. By decomposing the peaks of the radial distribution functions (RDFs) according to the pair analysis technique, the local structural patterns are identified for this cluster. During increasing temperature, structural changes of different shells determined by atom density profiles result in an abrupt increase in internal energy. The simulations show how local structural changes can strongly cause internal energy to change accordingly.

  13. Resonance-inclined optical nuclear spin polarization of liquids in diamond structures

    CERN Document Server

    Chen, Qiong; Jelezko, Fedor; Retzker, Alex; Plenio, Martin B

    2015-01-01

    Dynamic nuclear polarization (DNP) of molecules in a solution at room temperature has potential to revolutionize nuclear magnetic resonance spectroscopy and imaging. The prevalent methods for achieving DNP in solutions are typically most effective in the regime of small interaction correlation times between the electron and nuclear spins, limiting the size of accessible molecules. To solve this limitation, we design a mechanism for DNP in the liquid phase that is applicable for large interaction correlation times. Importantly, while this mechanism makes use of a resonance condition similar to solid-state DNP, the polarization transfer is robust to a relatively large detuning from the resonance due to molecular motion. We combine this scheme with optically polarized nitrogen vacancy (NV) center spins in nanodiamonds to design a setup that employs optical pumping and is therefore not limited by room temperature electron thermal polarisation. We illustrate numerically the effectiveness of the model in a flow cel...

  14. Upgrade and Design of Coastal Structures Exposed to Climate Changes

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Quvang Harck

    This thesis “Upgrade and Design of Coastal Structures Exposed to Climate Changes” evaluates the performance of existing types of structures when exposed to climate changes. This includes also the potential of using cost‐sharing multipurpose structures for protection against the effects of future...... climate changes. The thesis consists of three parts. The first part evaluates the performance of existing design formulae for estimation of wave actions on structures, especially in shallow water since these structures are most vulnerable to the rising sea water levels caused by climate changes. Existing...... of coastal protection structures, which are extended to a wider range of wave conditions, and which can be used to more accurately estimate the influence from climate changes. In the second part of the thesis, the extended and modified formulae are used in case studies to evaluate the influence from climate...

  15. The Management of Resistance to Change and Polarity in Educational Organisations.

    Science.gov (United States)

    Theron, A. M. C.; Westhuizen, Philip C. van der

    Research has shown that organizations differ on the basis of their willingness to change and the strategies they use to manage change. For this paper, data were gathered through a review of the literature and through nonstandard interviews with persons in two identified organizations who handle grievance procedures. The analysis identifies the…

  16. Polar structure of disclination loops in nematic liquid crystals probed by second-harmonic-light scattering.

    Science.gov (United States)

    Pardaev, Shokir A; Williams, J C; Twieg, R J; Jakli, A; Gleeson, J T; Ellman, B; Sprunt, S

    2015-03-01

    Angle-resolved, second-harmonic-light scattering (SHLS) measurements are reported for three different classes of thermotropic nematic liquid crystals (NLCs): polar and nonpolar rodlike compounds and a bent-core compound. Results revealing well-defined scattering peaks are interpreted in terms of the electric polarization induced by distortions of the nematic orientational field ("flexopolarity") associated with inversion wall defects, nonsingular disclinations, analogous to Neel walls in ferromagnets, that often exhibit a closed loop morphology in NLCs. Analysis of the SHLS patterns based on this model provides a "proof-of-concept" for a potentially useful method to probe the flexopolar properties of NLCs.

  17. Changing the mindset[Lightweight composite structures

    Energy Technology Data Exchange (ETDEWEB)

    DeLuca, M.

    2002-12-01

    Advances in the use of composite technology are some of the more closely watched in the industry. In the industry all agree that to go deeper systems must get lighter, one way being examined is the replacement of heavy steel systems with lightweight composite structures.Composites offer high strength-to-weight ratio, fatigue, and corrosion-resistance, design flexibility, thermal insulation and stiffness over steel systems. Although generally more expensive on a direct component to component comparison, results in overall lower system cost, especially in the deepwater. Conoco-Phillips are one of the industry's leading advocates of composite technology advancement and this article reports on the discussions the author had with a senior research fellow of the company. Details of the research that has been carried out and how far these developments have reached are covered here.

  18. Structure Change of the Insulating Composite

    Directory of Open Access Journals (Sweden)

    Vaclav Mentlik

    2008-01-01

    Full Text Available Modern power electric drives brought advantages in induction motor control. In the same time appeared problems with high frequency square waveform voltage (pulse stress produced by the voltage converters. Voltage converters produce repetitive pulses with high level of voltage rise fronts (slew rates. Rise fronts attained values of up to tens kilovolts per microsecond and voltage pulse repetition frequency up to some tens of kilohertz. This technology is an advantage for a drive control. Significant is the impact of these voltage waveforms on the motor insulations. Degradation of the main wall insulation can reduce the reliability of the electric motor and whole drive. In this paper is discussed one possible solution. The promising modification in the insulation material structure is presented in the paper.

  19. A Structural Equation Model of Conceptual Change in Physics

    Science.gov (United States)

    Taasoobshirazi, Gita; Sinatra, Gale M.

    2011-01-01

    A model of conceptual change in physics was tested on introductory-level, college physics students. Structural equation modeling was used to test hypothesized relationships among variables linked to conceptual change in physics including an approach goal orientation, need for cognition, motivation, and course grade. Conceptual change in physics…

  20. Terazulene Isomers: Polarity Change of OFETs through Molecular Orbital Distribution Contrast.

    Science.gov (United States)

    Yamaguchi, Yuji; Takubo, Maki; Ogawa, Keisuke; Nakayama, Ken-Ichi; Koganezawa, Tomoyuki; Katagiri, Hiroshi

    2016-09-01

    Intermolecular orbital coupling is fundamentally important to organic semiconductor performance. Recently, we reported that 2,6':2',6″-terazulene (TAz1) exhibited excellent performance as an n-type organic field-effect transistor (OFET) via molecular orbital distribution control. To validate and develop this concept, here we present three other terazulene regioisomers, which have three azulene molecules connected at the 2- or 6-position along the long axis of the azulene, thus constructing a linear expanded π-conjugation system: 2,2':6',2″-terazulene (TAz2), 2,2':6',6″-terazulene (TAz3), and 6,2':6',6″-terazulene (TAz4). TAz2 and TAz3 exhibit ambipolar characteristics; TAz4 exhibits clear n-type transistor behavior as an OFET. The lowest unoccupied molecular orbitals (LUMOs) of all terazulenes are fully delocalized over the entire molecule. In contrast, the highest occupied molecular orbitals (HOMOs) of TAz2 and TAz3 are delocalized over the 2,2'-biazulene units; the HOMOs of TAz4 are localized at one end of the azulene unit. These findings confirm that terazulene isomers which are simple hydrocarbon compounds are versatile materials with a tunable-polarity FET characteristic that depends on the direction of the azulene unit and the related contrast of the molecular orbital distribution in the terazulene backbone. PMID:27511286

  1. Strong enhancement of nano-sized circularly polarized light using an aperture antenna with V-groove structures.

    Science.gov (United States)

    Cai, Yongfu; Ikeda, Soushi; Nakagawa, Katsuji; Kikuchi, Hiroshi; Shimidzu, Naoki; Ishibashi, Takayuki

    2015-04-01

    We present a new type of aperture antenna with V-groove structures that are made of Au to enhance strong circularly polarized light (CPL). Simulations using the finite element method revealed that strong CPL was enhanced within the aperture with a diameter of 10 nm. The intensity of the electric field was enhanced and was 22,700 times greater than that of the incident light. The channel plasmon polaritons generated in the V-groove structures were responsible for the strong enhancement. The influence of the angle and length of the V-groove on the enhancement of the CPL was investigated. PMID:25831317

  2. Spin-polarized structural, elastic, electronic and magnetic properties of half-metallic ferromagnetism in V-doped ZnSe

    Energy Technology Data Exchange (ETDEWEB)

    Monir, M. El Amine.; Baltache, H. [Laboratoire de Physique Quantique de la Matière et de la Modélisation Mathématique (LPQ3M), Faculté des Sciences, Université de Mascara, Mascara 29000 (Algeria); Murtaza, G., E-mail: murtaza@icp.edu.pk [Materials Modeling Lab, Department of Physics, Islamia College University, Peshawar (Pakistan); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique de la Matière et de la Modélisation Mathématique (LPQ3M), Faculté des Sciences, Université de Mascara, Mascara 29000 (Algeria); Ahmed, Waleed K. [ERU, Faculty of Engineering, United Arab Emirates University, Al Ain (United Arab Emirates); Bouhemadou, A. [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, University of Setif, 19000 Setif (Algeria); Omran, S. Bin [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Seddik, T. [Laboratoire de Physique Quantique de la Matière et de la Modélisation Mathématique (LPQ3M), Faculté des Sciences, Université de Mascara, Mascara 29000 (Algeria)

    2015-01-15

    Based on first principles spin-polarized density functional theory, the structural, elastic electronic and magnetic properties of Zn{sub 1−x}V{sub x}Se (for x=0.25, 0.50, 0.75) in zinc blende structure have been studied. The investigation was done using the full-potential augmented plane wave method as implemented in WIEN2k code. The exchange-correlation potential was treated with the generalized gradient approximation PBE-GGA for the structural and elastic properties. Moreover, the PBE-GGA+U approximation (where U is the Hubbard correlation terms) is employed to treat the “d” electrons properly. A comparative study between the band structures, electronic structures, total and partial densities of states and local moments calculated within both GGA and GGA+U schemes is presented. The analysis of spin-polarized band structure and density of states shows the half-metallic ferromagnetic character and are also used to determine s(p)-d exchange constants N{sub 0}α (conduction band ) and N{sub 0}β (valence band) due to Se(4p)–V(3d) hybridization. It has been clearly evidence that the magnetic moment of V is reduced from its free space change value of 3 µ{sub B} and the minor atomic magnetic moment on Zn and Se are generated. - Highlights: • Half metallicity origins by doping V in ZnSe. • PBE-GGA+U approximation is employed to treat the “d” electrons properly. • s(p)-d Exchange constants N{sub 0}α (conduction band ) and N{sub 0}β (valence band) are due to Se(4p)-V(3d) hybridization.

  3. The impact of volcanic aerosol on the Northern Hemisphere stratospheric polar vortex: mechanisms and sensitivity to forcing structure

    Directory of Open Access Journals (Sweden)

    M. Toohey

    2014-06-01

    imply that reproducing the polar vortex responses to past eruptions, or predicting the response to future eruptions, depends on accurate representation of the space-time structure of the volcanic aerosol forcing.

  4. Interrogation of orbital structure by elliptically polarized intense femtosecond laser pulses

    DEFF Research Database (Denmark)

    Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2011-01-01

    duration. We investigate the role of light ellipticity and the alignment angle of the major polarization axis of the external field relative to the probed orbital by studying radial and angular momentum distributions, the latter at a fixed narrow interval of final momenta close to the peak...

  5. The Structure and Linear Polarization of the Kiloparsec-scale Jet of the Quasar 3C 345

    Science.gov (United States)

    Roberts, David H.; Wardle, John F. C.; Marchenko, Valerie V.

    2013-02-01

    Deep Very Large Array imaging of the quasar 3C 345 at 4.86 and 8.44 GHz has been used to study the structure and linear polarization of its radio jet on scales ranging from 2 to 30 kpc. There is a 7-8 Jy unresolved core with spectral index α ~= -0.24 (I νvpropνα). The jet (typical intensity 15 mJy beam-1) consists of a 2.''5 straight section containing two knots, and two additional non-co-linear knots at the end. The jet's total projected length is about 27 kpc. The spectral index of the jet varies over -1.1 ~ 0.5. Despite the indication of jet precession in the total intensity structure, the polarization images suggest instead a jet re-directed at least twice by collisions with the external medium. Surprisingly, the electric vector position angles in the main body of the jet are neither longitudinal nor transverse, but make an angle of about 55° with the jet axis in the middle while along the edges the vectors are transverse, suggesting a helical magnetic field. There is no significant Faraday rotation in the source, so that is not the cause of the twist. The fractional polarization in the jet averages 25% and is higher at the edges. In a companion paper, Roberts & Wardle show that differential Doppler boosting in a diverging relativistic velocity field can explain the electric vector pattern in the jet.

  6. Ultra-broad band and dual-band highly efficient polarization conversion based on the three-layered chiral structure

    Science.gov (United States)

    Xu, Kai-kai; Xiao, Zhong-yin; Tang, Jing-yao; Liu, De-jun; Wang, Zi-hua

    2016-07-01

    In the paper, a novel three-layered chiral structure is proposed and investigated, which consists of a split-ring resonator sandwiched between two layers of sub-wavelength gratings. This designed structure can achieve simultaneously asymmetric transmission with an extremely broad bandwidth and high amplitude as well as multi-band 90° polarization rotator with very low dispersion. Numerical simulations adopted two kinds of softwares with different algorithms demonstrate that asymmetric parameter can reach a maximum of 0.99 and over than 0.8 from 4.6 to 16.8 GHz, which exhibit magnitude and bandwidth improvement over previous chiral metamaterials in microwave bands (S, C, X and Ku bands). Specifically, the reason of high amplitude is analyzed in detail based on the Fabry-perot like resonance. Subsequently, the highly efficient polarization conversion with very low dispersion between two orthogonal linearly polarized waves is also analyzed by the optical activity and ellipticity. Finally, the electric fields are also investigated and further demonstrate the correctness of the simulated and calculated results.

  7. Individual effects of seasonal changes, visitor density, and concurrent bear behavior on stereotypical behaviors in captive polar bears (Ursus maritimus).

    Science.gov (United States)

    Kelly, Krista R; Harrison, Michelle L; Size, Daniele D; MacDonald, Suzanne E

    2015-01-01

    Stereotypical behaviors in captive polar bears (Ursus maritimus) can be detrimental to their welfare. These behaviors can be reduced through enrichment programs but are often not completely eliminated, so identifying potential triggers is important. The present study investigated the influences of seasonal changes, visitor density, and concurrent bear activity on stereotypical behaviors exhibited by 3 captive polar bears at the Toronto Zoo. All bears exhibited these behaviors; however, individual differences were found in duration and form. The male exhibited less stereotypical behavior during spring, and the females exhibited less stereotypical behavior during winter. An increase in visitor density was associated with more stereotypical behavior in 1 female but less stereotypical behavior in the other 2 bears. All bears engaged in more stereotypical behaviors when the other bears were inactive, and 1 female engaged in more stereotypical behaviors when the other bears were out of sight. Further, when conspecifics were active, all bears engaged in less stereotypical behaviors. Given the variability among individual bears, future enrichment programs must be tailored to the needs of individuals to maximize efficacy. PMID:24933263

  8. Study on Land Use Structure Changes and Countermeasures

    Institute of Scientific and Technical Information of China (English)

    Zhiyou; LIU; Chunling; PU; Airong; ZHU; Zhiqiang; WANG

    2013-01-01

    Land structure change not only relates to the coordinated development of regional social economic,but also determines the ecological environment security in certain region. Ili river valley was chose as the study area. The scientific and quantitative assessment of land use struc- ture and spatial pattern is significant to the sustainable development of the Ili river valley area. Based on the detailed investigation date of land use from 2002 to 2008,and social and economic statistics of the Ili river valley in eight counties and one city in 2008,the study area’s land use structure changes were discussed in three aspects from the land use structure,the degree of land use,to the land use efficiency. The changes of land use structure were analyzed by the use of qualitative and quantitative methods. Factors that influence land use structure changes were analyzed. In the end,suggestions were put forward to optimize the management.

  9. The Polar Stratosphere in a Changing Climate (POLSTRACC): Mission overview and first results

    Science.gov (United States)

    Oelhaf, Hermann; Sinnhuber, Björn-Martin; Woiwode, Wolfgang; Rapp, Markus; Dörnbrack, Andreas; Engel, Andreas; Bönisch, Harald

    2016-04-01

    The POLSTRACC mission aims at providing new scientific knowledge on the Arctic lowermost stratosphere and upper troposphere under the present load of halogens and state of climate variables. POLSTRACC employs the German High Altitude and LOng Range Research Aircraft (HALO) and is the only HALO mission dedicated to study the UTLS at high latitudes several years after the last intensive Arctic campaigns. The scientific scope of POLSTRACC is broadened by its combination with the SALSA (Seasonality of Air mass transport and origin in the Lowermost Stratosphere using the HALO Aircraft) and GW-LCYCLE (Gravity Wave Life Cycle Experiment, a BMBF/ROMIC project) missions, which address complementary scientific goals sharing the same HALO payload. POLSTRACC, SALSA and GW-LCYCLE offer the unique opportunity to study the bottom of the polar vortex and the high-latitude UTLS along with their impact on lower latitudes throughout an entire winter/spring cycle. The payload for the combined POLSTRACC, SALSA and GW-LCYCLE campaigns comprises an innovative combination of remote sensing techniques providing 2- and 3-D distributions of temperature and a large number of substances, and precise in-situ instruments measuring T, O3, H2O, tracers of different lifetimes and chemically active species at the aircraft level with high time-resolution. Drop sondes will add information about temperature, humidity and wind in the atmosphere underneath the aircraft. The POLSTRACC consortium includes national (KIT, Forschungszentrum Jülich, DLR, Universities of Frankfurt, Heidelberg, Mainz and Wuppertal; PTB) and international partners (e.g. NASA). The field campaign is divided into three phases for addressing (i) the early polar vortex and its wide-scale vicinity in December 2015 (from Oberpfaffenhofen, Germany), (ii) the mid-winter vortex from January to March 2016 (from Kiruna, Sweden), and (iii) the late dissipating vortex and its wide-scale vicinity in March 2016 (from Kiruna and

  10. Electronic structure, spin polarization and high critical fields in Chevrel compounds

    Science.gov (United States)

    Jarlborg, T.; Freeman, A. J.

    1982-05-01

    Results are presented of an extensive theoretical study of the origin of high field superconductivity and/or magnetism in a number of Chevrel phase ternary compounds, MMo 6X 8 (with M=Sn, Eu, Gd and X=S and/or Se) based on self-consistent linear muffin-tin orbital (LMTO) energy band calculations using the local density approach (Hedin et al. exchange correlation) for the paramagnetic structures and local spin density formalism (Gunnarsson and Lundqvist) for the ferromagnetic structures. All electrons and all 15 atoms/cell are included with the core electrons (including the 4f's) recalculated in each iteration in a fully relativistic representation and the conduction electrons treated semirelativistically (all relativistic terms except spin-orbit). Superconductivity is found to be due to the high Mo d-band density of states (DOS) at E F resulting from the unusual large charge transfer of Mo electrons to the chalcogen sites. There is also a large charge transfer from the metal site to the cluster (≈2 electrons in Sn and Eu) giving essentially no occupied conduction bands, for example, at the Eu site and a divalent ion isomer shift in very good agreement with the experiments of Dunlap et al. The conduction-electron DOS at the Eu site is found to be reduced by an order of magnitude from its metallic state value - in close agreement with their spin - lattice relaxation rate measurements. This low conduction-electron DOS yields very weak coupling of the 4f electrons to the conduction electrons and only a very weak Ruderman-Kittel-Kasuya-Yosida magnetic interaction showing why all the Chevrel rare-earth compounds - except Ce and Eu - are superconducting despite their having large local magnetic moments. The unusually high upper critical fields, Hc 2, in these materials is found to be due to the unusully flat energy bands near F F. The ferromagnetic (spin polarized) results for the Eu- and Gd-compounds show a net small but positive magnetic moment on the metal site and a

  11. Excited-state proton coupled charge transfer modulated by molecular structure and media polarization.

    Science.gov (United States)

    Demchenko, Alexander P; Tang, Kuo-Chun; Chou, Pi-Tai

    2013-02-01

    Charge and proton transfer reactions in the excited states of organic dyes can be coupled in many different ways. Despite the complementarity of charges, they can occur on different time scales and in different directions of the molecular framework. In certain cases, excited-state equilibrium can be established between the charge-transfer and proton-transfer species. The interplay of these reactions can be modulated and even reversed by variations in dye molecular structures and changes of the surrounding media. With knowledge of the mechanisms of these processes, desired rates and directions can be achieved, and thus the multiple emission spectral features can be harnessed. These features have found versatile applications in a number of cutting-edge technological areas, particularly in fluorescence sensing and imaging.

  12. Multi-decadal changes in tundra environments and ecosystems: Synthesis of the International Polar Year-Back to the Future Project (IPY-BTF)

    DEFF Research Database (Denmark)

    Callaghan, Terry V.; Tweedie, Craig E.; Åkerman, Jonas;

    2011-01-01

    Understanding the responses of tundra systems to global change has global implications. Most tundra regions lack sustained environmental monitoring and one of the only ways to document multi-decadal change is to resample historic research sites. The International Polar Year (IPY) provided a uniqu...

  13. Structures and Correlations in Ideally Aligned Polar Gay-Berne Systems

    International Nuclear Information System (INIS)

    We study an ideally oriented system of Gay-Berne particles with embedded longitudinal dipole moments. While keeping the translational degrees of freedom of the molecules unrestricted we assume that their dipoles can be oriented either parallel or antiparallel to the positive z axis of the laboratory frame. At high temperatures, this frustrated Gay-Berne mesogen exhibits an ideally oriented nematic phase, which is the reference state of the system. In the limit of vanishing dipole moment nematic, smectic-A and smectic B phases are stable. Interestingly, by changing the magnitude and location of the molecular dipole in the nematic reference state we found dipole-induced smectic A, smectic B and tetragonal crystal phases, in addition to crystalline structures with smectic Ad and A2-like dipolar organization. Various singlet, pair and triplet distribution functions were evaluated to elucidate short and long range organization in these phases. In particular, the importance of triplet correlations for a proper understanding of the structures and their local, dipolar organization is demonstrated. (author)

  14. Characterization of process-induced damage in Cu/low-k interconnect structure by microscopic infrared spectroscopy with polarized infrared light

    Science.gov (United States)

    Seki, Hirofumi; Hashimoto, Hideki; Ozaki, Yukihiro

    2016-09-01

    Microscopic Fourier-transform infrared (FT-IR) spectra are measured for a Cu/low-k interconnect structure using polarized IR light for different widths of low-k spaces and Cu lines, and for different heights of Cu lines, on Si substrates. Although the widths of the Cu line and the low-k space are 70 nm each, considerably smaller than the wavelength of the IR light, the FT-IR spectra of the low-k film were obtained for the Cu/low-k interconnect structure. A suitable method was established for measuring the process-induced damage in a low-k film that was not detected by the TEM-EELS (Transmission Electron Microscope-Electron Energy-Loss Spectroscopy) using microscopic IR polarized light. Based on the IR results, it was presumed that the FT-IR spectra mainly reflect the structural changes in the sidewalls of the low-k films for Cu/low-k interconnect structures, and the mechanism of generating process-induced damage involves the generation of Si-OH groups in the low-k film when the Si-CH3 bonds break during the fabrication processes. The Si-OH groups attract moisture and the OH peak intensity increases. It was concluded that the increase in the OH groups in the low-k film is a sensitive indicator of low-k damage. We achieved the characterization of the process-induced damage that was not detected by the TEM-EELS and speculated that the proposed method is applicable to interconnects with line and space widths of 70 nm/70 nm and on shorter scales of leading edge devices. The location of process-induced damage and its mechanism for the Cu/low-k interconnect structure were revealed via the measurement method.

  15. Structural change in the brazilian economy in the 2000s

    Directory of Open Access Journals (Sweden)

    Alexandre Messa

    2013-12-01

    Full Text Available This paper investigates the sources of structural change in the Brazilian economy in the 2000s. On that purpose, it uses the input-output structural decomposition analysis and introduces a method to correct the influence of prices on the time behavior of the technical coefficients, making them actually represent changes in the production structure. Results show that most of the growth differential between services and industry in that period was induced by the production structure: more precisely, by a lower intermediate consumption of domestic industrial inputs by the production chain of all economic sectors, concomitant with a higher intermediate consumption of services.

  16. The intra-hour variable quasar J1819+3845: 13-year evolution, jet polarization structure, and interstellar scattering screen properties

    Science.gov (United States)

    de Bruyn, A. G.; Macquart, J.-P.

    2015-02-01

    We examine the long-term evolution of the intra-hour variable quasar, J1819+3845, whose variations have been attributed to interstellar scintillation by extremely local turbulent plasma, located only 1-3 pc from Earth. The variations in this source ceased some time in the period between June 2006 and February 2007. The evolution of the source spectrum and the long-term lightcurve, and the persistent compactness of the source VLBI structure indicate that the cessation of rapid variability was associated with the passage of the scattering material out of the line of sight to the quasar. We present an extensive analysis of the linear polarization variations and their relation to total intensity variations. The proper motion of polarized features in the quasar jet is found to be subluminal. Systematic time delays between Stokes I, Q, and U, in combination with the structure of the source obtained from 8.4 GHz VLBI data confirm the estimate of the screen distance: 1-2 pc, making the screen one of the nearest objects to the solar system. We determine the physical properties of this scattering material. The electron density in the scattering region is extremely high with respect to the warm ionized ISM, with an estimated density of ne ~ 97 l01/3 ΔL 100-1/2 cm -3, where l0 is the outer scale of the turbulence in AU and ΔL = 100 ΔL100 AU is the depth of the scattering region. If this plasma is in pressure balance with the local magnetic field, one expects a ~2 rad m-2 rotation measure (RM) change associated with the passage of this material past the quasar. To that end, we examine the RMs of sources and the diffuse polarized emission in the surrounding region. We place a limit of 10 rad m-2 on the RM change based upon 21 cm polarization observations. The variability of sources near J1819+3845 is examined to deduce limits on the transverse extent of the screen, and we find that no other sources exhibit variations on comparable timescales and that the screen must therefore

  17. Cosmic anisotropies from quasars: from polarization to structural-axis alignments

    CERN Document Server

    Pelgrims, Vincent

    2016-01-01

    The comparison of the orientations of the optical-polarization vectors of quasars that are separated by billions of light-years has led to the discovery that they are aligned instead of pointing in random directions as expected. This discovery has been confirmed and the significance of the correlations enhanced. We devoted this doctoral thesis to an in-depth analysis of these striking observations that imply Gpc-scale correlations. We developed a new and independent statistical method which is dedicated to the study and the characterization of the distribution of the orientations of vectorial quantities that are perpendicular to the lines of sight of a set of sources spread on the celestial sphere. This allowed us to confirm independently the large-scale polarization-vector alignments and to refine the limits of the alignment regions through an unbiased characterization of the signal. We also provided a detailed analysis of a large sample of polarization measurements made at radio wavelengths in which similar...

  18. A wind-driving disc model for the mm-wavelength polarization structure of HL Tau

    CERN Document Server

    Matsakos, Titos; Königl, Arieh

    2016-01-01

    The recent advent of spatially resolved mm- and cm-wavelength polarimetry in protostellar accretion discs could help clarify the role of magnetic fields in the angular momentum transport in these systems. The best case to date is that of HL~Tau, where the inability to produce a good fit to the 1.25-mm data with a combination of vertical and azimuthal magnetic field components was interpreted as implying that centrifugally driven winds (CDWs) are probably not a significant transport mechanism on the $\\sim 10^2\\,$au scale probed by the observations. Using synthetic polarization maps of heuristic single-field-component discs and of a post-processed simulation of a wind-driving disc, we demonstrate that a much better fit to the data can be obtained if the radial field component, a hallmark of the CDW mechanism, dominates in the polarized emission region. A similar inference was previously made in modelling the far-infrared polarization map of the pc-scale dust ring in the Galactic centre. To reconcile this interp...

  19. MAGNETIC FIELD STRUCTURE OF THE LARGE MAGELLANIC CLOUD FROM FARADAY ROTATION MEASURES OF DIFFUSE POLARIZED EMISSION

    International Nuclear Information System (INIS)

    We present a study of the magnetic field of the Large Magellanic Cloud (LMC), carried out using diffuse polarized synchrotron emission data at 1.4 GHz acquired at the Parkes Radio Telescope and the Australia Telescope Compact Array. The observed diffuse polarized emission is likely to originate above the LMC disk on the near side of the galaxy. Consistent negative rotation measures (RMs) derived from the diffuse emission indicate that the line-of-sight magnetic field in the LMC's near-side halo is directed coherently away from us. In combination with RMs of extragalactic sources that lie behind the galaxy, we show that the LMC's large-scale magnetic field is likely to be of quadrupolar geometry, consistent with the prediction of dynamo theory. On smaller scales, we identify two brightly polarized filaments southeast of the LMC, associated with neutral hydrogen arms. The filaments' magnetic field potentially aligns with the direction toward the Small Magellanic Cloud (SMC). We suggest that tidal interactions between the SMC and the LMC in the past 109 years are likely to have shaped the magnetic field in these filaments.

  20. Slim-structured electro-floating display system based on the polarization-controlled optical path.

    Science.gov (United States)

    Kim, Seung-Cheol; Park, Seong-Jin; Kim, Eun-Soo

    2016-04-18

    A new slim-type electro-floating display system based on the polarization-controlled optical path is proposed. In the proposed system, the optical path between the input plane and Fresnel lens can be made recursive by repetitive transmission and reflection of the input beam by employing a new polarization-based optical path controller (P-OPC), which is composed of two quaterwave plates, a half mirror and a reflective polarizer. Based on this P-OPC, the absolute optical path between the input plane and Fresnel lens, virtually representing the physical depth of the display system, can be reduced down to one third of its original path, which results in the same rate of decrease in the volume size of the display system. The operational principle of the proposed system is analyzed with the Jones matrix. In addition, to confirm the feasibility of the proposed system, experiments with test prototypes are carried out, and the results are comparatively discussed with those of the conventional system.

  1. Dynamic Changes in Sarcoplasmic Reticulum Structure in Ventricular Myocytes

    Directory of Open Access Journals (Sweden)

    Amanda L. Vega

    2011-01-01

    sarcoplasmic reticulum (SR and the sarcolemma where Ca2+ release is activated. Here, we tested the hypothesis that the SR is a structurally inert organelle in ventricular myocytes. Our data suggest that rather than being static, the SR undergoes frequent dynamic structural changes. SR boutons expressing functional ryanodine receptors moved throughout the cell, approaching or moving away from the sarcolemma of ventricular myocytes. These changes in SR structure occurred in the absence of changes in [Ca2+] during EC coupling. Microtubules and the molecular motors dynein and kinesin 1(Kif5b were important regulators of SR motility. These findings support a model in which the SR is a motile organelle capable of molecular motor protein-driven structural changes.

  2. Spin-polarized transport in manganite-based magnetic nano structures

    International Nuclear Information System (INIS)

    Giant magnetoresistance (G M R) and tunnel magnetoresistance are spin polarized transport phenomena which are observed in magnetic multilayers.They consist in a large variation of the electrical resistivity of the system depending on whether the magnetizations of the magnetic layers are aligned parallel or anti-parallel to each other. In order to be able to align the magnetic layers by means of an external magnetic field, they must not be strongly ferromagnetically coupled.The extrinsic magnetoresistance effects in magnetic multilayers, either G M R in the case of a metallic spacer, or T M R in the case of an insulating spacer, are observed at low magnetic fields, which makes these phenomena interesting for technological applications.We studied the possibility of using the ferromagnetic manganite La0,75Sr0,25MnO3 (L S M O) in magneto resistive devices, with different materials as a spacer layer.As the main result of this work, we report G M R and T M R measurements in L S M O/LaNiO3/L S M O and L S M O/CaMnO3/L S M O tri layers, respectively, observed for the first time in these systems.This work included the deposition of films and multilayers by sputtering, the structural characterization of the samples and the study of their magnetic and electric transport properties.Our main interest was the study of G M R in L S M O/LaNiO3/L S M O tri layers.It was necessary to firstly characterize the magnetic coupling of L S M O layers through the L N O spacer. After that, we performed electric transport measurements with the current in the plane of the samples.We measured a G M R contribution of ∼ 0,55 % at T = 83 K.We designed a procedure for patterning the samples by e-beam lithography for electric transport measurements with the current perpendicular to the plane. We also performed the study of L S M O/CaMnO3/L S M O tri layers with an insulating spacer.We studied the magnetic coupling, as in the previous case.Then we fabricated a tunnel junction for measuring electric

  3. Polar Climate Change from Recent Observations and in Global Climate Models

    Science.gov (United States)

    Weatherly, J. W.

    2002-12-01

    Recent papers on the thinning and shrinking sea ice cover of the Arctic Ocean have suggested that these changes can be explained by both natural climate oscillations and large-scale trends. The changes in patterns of ice motion are consistent with the dynamic response of sea ice to changing pressure patterns indicated by the Arctic Oscillation, which seem to transport thicker sea ice out of the Arctic Ocean. Anomalously warm air temperatures and ocean temperatures also appear to have contributed to less sea ice growth, resulting in thinner ice. Both warmer air and ocean temperatures are consistent with the warmer phase of the Arctic Oscillation. Global climate model simulations that include complex dynamic and thermodynamic ice models also show that anthropogenic global warming trends since the 1980's have also contributed to the present-day thinning and shrinking sea ice cover. However, the models also show the large natural variability in the ice cover that must be overcome before the anthropogenic trends can be reliably measured. Estimates of the number of additional ice observing stations that will be required to measure the secular trend will be presented.

  4. Polarized Sources, Targets and Polarimetry

    Science.gov (United States)

    Ciullo, Guiseppe; Contalbrigo, Marco; Lenisa, P.

    2011-01-01

    Remarks on the history of workshops on "spin tools" / E. Steffens -- Polarized proton beams in RHIC / A. Zelenski -- The COSY/Julich polarized H[symbol] and D[symbol] ion source / O. Felden -- The new source of polarized ions for the JINR accelerator complex / V. V. Fimushkin -- Resonance effects in nuclear dichroism - an inexpensive source of tensor-polarized deuterons / H. Seyfarth -- Polarized electrons and positrons at the MESA accelerator / K. Aulenbacher -- Status report of the Darmstadt polarized electron injector / Y. Poltoratska -- The Mott polarimeter at MAMI / V. Tioukine -- Proton polarimetry at the relativistic heavy ion collider / Y. Makdisi -- Polarisation and polarimetry at HERA / B. Sobloher -- Polarisation measurement at the ILC with a Compton polarimeter / C. Bartels -- Time evolution of ground motion-dependent depolarisation at linear colliders / A. Hartin -- Electron beam polarimetry at low energies and its applications / R. Barday -- Polarized solid targets: recent progress and future prospects / C. D. Keith -- HD gas distillation and analysis for HD frozen spin targets / A. D'Angelo -- Electron spin resonance study of hydrogen and alkyl free radicals trapped in solid hydrogen aimed for dynamic nuclear polarization of solid HD / T. Kumada -- Change of ultrafast nuclear-spin polarization upon photoionization by a short laser pulse / T. Nakajima -- Radiation damage and recovery in polarized [symbol]NH[symbol] ammonia targets at Jefferson lab / J. D. Maxwell.Polarized solid proton target in low magnetic field and at high temperature / T. Uesaka -- Pulse structure dependence of the proton spin polarization rate / T. Kawahara -- Proton NMR in the large COMPASS [symbol]NH[symbol] target / J. Koivuniemi -- DNP with TEMPO and trityl radicals in deuterated polystyrene / L. Wang -- The CLIC electron and positron polarized sources / L. Rinolfi -- Status of high intensity polarized electron gun at MIT-Bates / E. Tsentalovich -- Target section for spin

  5. Empirical analysis of structural change in Credit Default Swap volatility

    International Nuclear Information System (INIS)

    The purpose of this paper is to study the structural change in Credit Default Swap volatility. We use statistical properties and a network approach to better understand the behavior of CDS volatility. We hypothesize that structural change occurs in CDS index during a financial crisis and it requires subperiod analysis, rather than full period analysis, to investigate properly. Our results show that the probability of large volatility is related to the structure of volatility but it is more significantly related to the size of volatility. Both the memory property and the size of volatility are confirmed to have dependence on the structure of volatility. The linked degree of CDS volatilities is highly related to the probability of large volatility and its predictability, regardless of structural change in volatility. Another interesting result is that the CDS volatility of a country is more related to the behavior of other volatilities, not the geographical location

  6. Structural Changes and Global Trends in European Union Trade

    OpenAIRE

    Ishak Mesic

    2009-01-01

    The article aims at researching and presenting structural changes and global trends in distributive trade of European Union, resulted from liberalization of economic activities within the EU. During the last decades, EU trade went through deep transformation and structural changes. Traditional distributive trade has been replaced by organized and concentrated distribution. Even though, there are many developing trends which unify the EU trade, still there are some differences specific for par...

  7. Stress reduction correlates with structural changes in the amygdala

    OpenAIRE

    Hölzel, Britta K.; Carmody, James; Evans, Karleyton C.; Hoge, Elizabeth A.; Dusek, Jeffery A; Morgan, Lucas; Pitman, Roger K.; Lazar, Sara W.

    2009-01-01

    Stress has significant adverse effects on health and is a risk factor for many illnesses. Neurobiological studies have implicated the amygdala as a brain structure crucial in stress responses. Whereas hyperactive amygdala function is often observed during stress conditions, cross-sectional reports of differences in gray matter structure have been less consistent. We conducted a longitudinal MRI study to investigate the relationship between changes in perceived stress with changes in amygdala ...

  8. A Comparative Study of Molecular Structure, pKa, Lipophilicity, Solubility, Absorption and Polar Surface Area of Some Antiplatelet Drugs

    Directory of Open Access Journals (Sweden)

    Milan Remko

    2016-03-01

    Full Text Available Theoretical chemistry methods have been used to study the molecular properties of antiplatelet agents (ticlopidine, clopidogrel, prasugrel, elinogrel, ticagrelor and cangrelor and several thiol-containing active metabolites. The geometries and energies of most stable conformers of these drugs have been computed at the Becke3LYP/6-311++G(d,p level of density functional theory. Computed dissociation constants show that the active metabolites of prodrugs (ticlopidine, clopidogrel and prasugrel and drugs elinogrel and cangrelor are completely ionized at pH 7.4. Both ticagrelor and its active metabolite are present at pH = 7.4 in neutral undissociated form. The thienopyridine prodrugs ticlopidine, clopidogrel and prasugrel are lipophilic and insoluble in water. Their lipophilicity is very high (about 2.5–3.5 logP values. The polar surface area, with regard to the structurally-heterogeneous character of these antiplatelet drugs, is from very large interval of values of 3–255 Å2. Thienopyridine prodrugs, like ticlopidine, clopidogrel and prasugrel, with the lowest polar surface area (PSA values, exhibit the largest absorption. A high value of polar surface area (PSA of cangrelor (255 Å2 results in substantial worsening of the absorption in comparison with thienopyridine drugs.

  9. Structural changes of linear DNA molecules induced by cisplatin

    International Nuclear Information System (INIS)

    Interaction between long DNA molecules and activated cisplatin is believed to be crucial to anticancer activity. However, the exact structural changes of long DNA molecules induced by cisplatin are still not very clear. In this study, structural changes of long linear double-stranded DNA (dsDNA) and short single-stranded DNA (ssDNA) induced by activated cisplatin have been investigated by atomic force microscopy (AFM). The results indicated that long DNA molecules gradually formed network structures, beads-on-string structures and their large aggregates. Electrostatic and coordination interactions were considered as the main driving forces producing these novel structures. An interesting finding in this study is the beads-on-string structures. Moreover, it is worth noting that the beads-on-string structures were linked into the networks, which can be ascribed to the strong DNA–DNA interactions. This study expands our knowledge of the interactions between DNA molecules and cisplatin. - Highlights: • We investigate structural changes of dsDNA and ssDNA induced by cisplatin. • AFM results indicated long dsDNA formed network, beads-on-string and aggregates. • ssDNA can form very similar structures as those of long linear dsDNA. • A possible formation process of theses novel structure is proposed

  10. Structural changes of linear DNA molecules induced by cisplatin

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhiguo, E-mail: cn.zguoliu@yahoo.com [State Engineering Laboratory of Bio-Resource Eco-Utilization, Harbin 150040 (China); Engineering Research Center of Forest Bio-preparation, Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Key Laboratory of Forest Plant Ecology of Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Liu, Ruisi; Zhou, Zhen; Zu, Yuangang; Xu, Fengjie [State Engineering Laboratory of Bio-Resource Eco-Utilization, Harbin 150040 (China); Engineering Research Center of Forest Bio-preparation, Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Key Laboratory of Forest Plant Ecology of Ministry of Education, Northeast Forestry University, Harbin 150040 (China)

    2015-02-20

    Interaction between long DNA molecules and activated cisplatin is believed to be crucial to anticancer activity. However, the exact structural changes of long DNA molecules induced by cisplatin are still not very clear. In this study, structural changes of long linear double-stranded DNA (dsDNA) and short single-stranded DNA (ssDNA) induced by activated cisplatin have been investigated by atomic force microscopy (AFM). The results indicated that long DNA molecules gradually formed network structures, beads-on-string structures and their large aggregates. Electrostatic and coordination interactions were considered as the main driving forces producing these novel structures. An interesting finding in this study is the beads-on-string structures. Moreover, it is worth noting that the beads-on-string structures were linked into the networks, which can be ascribed to the strong DNA–DNA interactions. This study expands our knowledge of the interactions between DNA molecules and cisplatin. - Highlights: • We investigate structural changes of dsDNA and ssDNA induced by cisplatin. • AFM results indicated long dsDNA formed network, beads-on-string and aggregates. • ssDNA can form very similar structures as those of long linear dsDNA. • A possible formation process of theses novel structure is proposed.

  11. The measurement of g1n polarized structure of the neutron by the E154 experiment at SLAC

    International Nuclear Information System (INIS)

    This thesis presents the precision measurement of the neutron polarized structure g1n performed by the E154 collaboration at the Standford Linear Accelerator Center, USA, in autumn 1995, using a 48.3 GeV polarized electron beam scattered off a polarized Helium 3 target. The scattered electrons were detected using two spectrometer arms, covering the deep inelastic scattering range: 0.0134 2 2 2 at an average value of Q2 = 5 GeV2. Two electromagnetic calorimeters have been designed by the LPC in Clermont-Ferrand and the SphN-CEA in Saclay to measure the scattered electron energy and to eject the contaminating hadron background using, a cellular automaton and a neural network, widely described in this thesis. The analysis performed in Clermont-Ferrand and presented in this document led us to the integral on the measurement region of g1n equaling: - 0.34 ± 0.003STAT ± 0.004SYST ± 0.001EVOL at Q2 = 5 GeV2, where our data have been evolved to Q2 = 5 GeV2 using the next-to-leading order DGLAP evolution equations and a world parametrization of the polarized parton distributions. The Ellis and Jaffe sum rule is clearly violated. Using different low x extrapolations, our integral is compatible with the Bjorken sum rule. The quark contribution to the nucleon spin is ΔΣ = 29 ± 6 % in the M S-bar scheme and ΔΣ = 37 ± 7% in the AB scheme, at Q2 = 5 GeV2. The gluon contribution seems to be positive and within the range: 0 < ΔG < 2. (author)

  12. On the recovery of ISW fluctuations using large-scale structure tracers and CMB temperature and polarization anisotropies

    Science.gov (United States)

    Bonavera, L.; Barreiro, R. B.; Marcos-Caballero, A.; Vielva, P.

    2016-06-01

    In this work we present a method to extract the signal induced by the integrated Sachs-Wolfe (ISW) effect in the cosmic microwave background (CMB). It makes use of the Linear Covariance-Based filter introduced by Barreiro et al., and combines CMB data with any number of large-scale structure (LSS) surveys and lensing information. It also exploits CMB polarization to reduce cosmic variance. The performance of the method has been thoroughly tested with simulations taking into account the impact of non-ideal conditions such as incomplete sky coverage or the presence of noise. In particular, three galaxy surveys are simulated, whose redshift distributions peak at low (z ≃ 0.3), intermediate (z ≃ 0.6) and high redshift (z ≃ 0.9). The contribution of each of the considered data sets as well as the effect of a mask and noise in the reconstructed ISW map is studied in detail. When combining all the considered data sets (CMB temperature and polarization, the three galaxy surveys and the lensing map), the proposed filter successfully reconstructs a map of the weak ISW signal, finding a perfect correlation with the input signal for the ideal case and around 80 per cent, on average, in the presence of noise and incomplete sky coverage. We find that including CMB polarization improves the correlation between input and reconstruction although only at a small level. Nonetheless, given the weakness of the ISW signal, even modest improvements can be of importance. In particular, in realistic situations, in which less information is available from the LSS tracers, the effect of including polarization is larger. For instance, for the case in which the ISW signal is recovered from CMB plus only one survey, and taking into account the presence of noise and incomplete sky coverage, the improvement in the correlation coefficient can be as large as 10 per cent.

  13. Using elaborative interrogation to induce characteristics of polar and nonpolar solvents from animations of their molecular structures

    Science.gov (United States)

    Ems-Wilson, Janice

    This study concerned (a) how general chemistry students learn to classify solvent polarity from animated molecules, (b) whether peer interaction increases the number of correct classifications, and (c) whether language, academic ability, logical thinking ability, or prior knowledge interact with rate of learning or posttest performance. Two types of interaction were compared, group discussion and elaborative interrogation. The study rested on three assumptions: (a) animated molecules are appropriate for learning the concept of solvent polarity, (b) question stems and a guided interrogation enhance learning of a visual concept, (c) general chemistry students can induce the concept of solvent polarity from animated molecules when no guiding cues, either visual or verbal, are given. After a review of molecular geometry and bonding theories, students were presented with four trials of ten animated molecular structures. Ten three-to-five minute discussions were distributed among the four trials. Prior to the trials the experimental group received a 45-minute training session on elaborative interrogation; the topic was what happens on the molecular level when a carbonated beverage is opened. The control group received a 45-minute expository lecture on the same carbonated beverage topic. Participants were given a four-part posttest immediately following the trials. Results of the study suggest that most students tend to classify the solvent polarity of animated molecules based on certain structural features using a prototype or feature-frequency categorization strategy. Elaborative interrogation did not show a significant effect on the rate of learning or on the performance of learners on posttest measures of recall and comprehension. The experimental group noted a significantly greater number and range of types of features, and offered higher quality generalizations and explanations of their polarity classification procedure. Finally, the results implied that learning

  14. Does competitive entry structurally change key marketing metrics?

    NARCIS (Netherlands)

    Kornelis, M.; Dekimpe, de M.G.; Leeflang, P.S.H.

    2008-01-01

    To what extent does competitive entry create a structural change in keymarketingmetrics? New players may just be a temporal nuisance to incumbents, but could also fundamentally change the latter's performance evolution, or induce them to permanently alter their spending levels and/or pricing decisio

  15. Does competitive entry structurally change key marketing metrics?

    NARCIS (Netherlands)

    Kornelis, Marcel; Dekimpe, Marnik G.; Leeflang, Peter S. H.

    2008-01-01

    To what extent does competitive entry create a structural change in key marketing metrics? New players mayjust be a temporal nuisance to incumbents, but could also fundamentally change the latter's performance evolution, or induce them to permanently alter their spending levels and/or pricing decisi

  16. Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom Fragilariopsis cylindrus

    DEFF Research Database (Denmark)

    Pancic, Marina; Hansen, Per Juel; Tammilehto, Anna;

    2015-01-01

    Abstract. The effects of ocean acidification and increased temperature on physiology of six strains of the polar diatom Fragilariopsis cylindrus from Greenland were investigated. Experiments were performed under manipulated pH levels (8.0, 7.7, 7.4, and 7.1) and different temperatures (1, 5, and 8...... C) to simulate changes from present to plausible future levels. Each of the 12 scenarios was run for 7 days, and a significant interaction between temperature and pH on growth was detected. By combining increased temperature and acidification, the two factors counterbalanced each other......, and therefore no effect on the growth rates was found. However, the growth rates increased with elevated temperatures by 20–50% depending on the strain. In addition, a general negative effect of increasing acidification on growth was observed. At pH 7.7 and 7.4, the growth response varied considerably among...

  17. Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom Fragilariopsis cylindrus

    DEFF Research Database (Denmark)

    Pančić, M.; Hansen, Peter Juul; Tammilehto, A.;

    2015-01-01

    The effects of ocean acidification and increased temperature on physiology of six strains of the polar diatom Fragilariopsis cylindrus from Greenland were investigated. Experiments were performed under manipulated pH levels (8.0, 7.7, 7.4, and 7.1) and different temperatures (1, 5 and 8 °C......) to simulate changes from present to plausible future levels. Each of the 12 scenarios was run for 7 days, and a significant interaction between temperature and pH on growth was detected. By combining increased temperature and acidification, the two factors counterbalanced each other, and therefore no effect...... on the growth rates was found. However, the growth rates increased with elevated temperatures by ∼20–50% depending on the strain. In addition, a general negative effect of increasing acidification on growth was observed. At pH 7.7 and 7.4, the growth response varied considerably among strains. However, a more...

  18. $\\Lambda$ polarization in peripheral collisions at moderate relativistic energies

    CERN Document Server

    Xie, Y L; Stöcker, H; Wang, D J; Csernai, L P

    2016-01-01

    The polarization of $\\Lambda$ hyperons from relativistic flow vorticity is studied in peripheral heavy ion reactions at FAIR and NICA energies, just above the threshold of the transition to the Quark-Gluon Plasma. Previous calculations at higher energies with larger initial angular momentum, predicted significant $\\Lambda$ polarization based on the classical vorticity term in the polarization, while relativistic modifications decreased the polarization and changed its structure in the momentum space. At the lower energies studied here, we see the same effect namely that the relativistic modifications decrease the polarization arising from the initial shear flow vorticity.

  19. Polarized scattering of light for arbitrary magnetic fields with level-crossings from the combination of hyperfine and fine structure splittings

    CERN Document Server

    Sowmya, K; Sampoorna, M; Stenflo, J O

    2015-01-01

    Interference between magnetic substates of the hyperfine structure states belonging to different fine structure states of the same term influences the polarization for some of the diagnostically important lines of the Sun's spectrum, like the sodium and lithium doublets. The polarization signatures of this combined interference contain information on the properties of the solar magnetic fields. Motivated by this, in the present paper, we study the problem of polarized scattering on a two-term atom with hyperfine structure by accounting for the partial redistribution in the photon frequencies arising due to the Doppler motions of the atoms. We consider the scattering atoms to be under the influence of a magnetic field of arbitrary strength and develop a formalism based on the Kramers--Heisenberg approach to calculate the scattering cross section for this process. We explore the rich polarization effects that arise from various level-crossings in the Paschen--Back regime in a single scattering case using the li...

  20. Electronic structure, morphology and emission polarization of enhanced symmetry InAs quantum-dot-like structures grown on InP substrates by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Maryński, A.; Sĕk, G.; Musiał, A.; Andrzejewski, J.; Misiewicz, J. [Institute of Physics, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław (Poland); Gilfert, C.; Reithmaier, J. P. [Technische Physik, Institute of Nanostructure Technology and Analytics, CINSaT, University of Kassel, Heinrich Plett-Str. 40, D-34132 Kassel (Germany); Capua, A.; Karni, O.; Gready, D.; Eisenstein, G. [Department of Electrical Engineering, Technion, Haifa 32000 (Israel); Atiya, G.; Kaplan, W. D. [Department of Materials Science and Engineering, Technion, Haifa 32000 (Israel); Kölling, S. [Fraunhofer Institute for Photonic Microsystems, Center for Nanoelectronic Technologies, Königsbrücker Straße 180, D-01099 Dresden (Germany)

    2013-09-07

    The optical and structural properties of a new kind of InAs/InGaAlAs/InP quantum dot (QD)-like objects grown by molecular beam epitaxy have been investigated. These nanostructures were found to have significantly more symmetrical shapes compared to the commonly obtained dash-like geometries typical of this material system. The enhanced symmetry has been achieved due to the use of an As{sub 2} source and the consequent shorter migration length of the indium atoms. Structural studies based on a combination of scanning transmission electron microscopy (STEM) and atom probe tomography (APT) provided detailed information on both the structure and composition distribution within an individual nanostructure. However, it was not possible to determine the lateral aspect ratio from STEM or APT. To verify the in-plane geometry, electronic structure calculations, including the energy levels and transition oscillator strength for the QDs have been performed using an eight-band k·p model and realistic system parameters. The results of calculations were compared to measured polarization-resolved photoluminescence data. On the basis of measured degree of linear polarization of the surface emission, the in-plane shape of the QDs has been assessed proving a substantial increase in lateral symmetry. This results in quantum-dot rather than quantum-dash like properties, consistent with expectations based on the growth conditions and the structural data.

  1. Spin-polarized electronic structure of the Ni(001) surface and thin films

    DEFF Research Database (Denmark)

    Jepsen, O.; Madsen, J.; Andersen, O. K.

    1982-01-01

    of the five-layer film is used to calculate the electronic structure of a 13-layer film. The theoretical work function of 5.4 eV agrees well with the experimental value of 5.2 eV. The calculated spin moments are ordered ferromagnetically in all the films considered, and the moments of the atoms in the surface...... layer are 0.95, 0.69, and 0.65 Bohr magnetons for the one-, three-, and five-layer films, respectively. The moment of an atom in the central layer of the five-layer film is 0.61 Bohr magnetons as compared with the calculated (experimental) bulk value of 0.59±0.01 (0.56) Bohr magnetons. The increase...... of the magnetic moment at the surface is mainly of d(x2-y2) character. The calculated 4s contribution to the hyperfine field changes sign and becomes positive in the outermost layer. Near k=0, between the Fermi level and the d-band edge (which lies 0.3 eV below the Fermi level), we find no majority-spin surface...

  2. Structural Changes of Polyethylene Terephthalate Fibers Grafted by Acrylamide

    Institute of Scientific and Technical Information of China (English)

    施琴芬; 戴礼兴

    2003-01-01

    A group of grafted PET fibers with different graft yield are formed by grafiing acrylamide onto the PET main chains. The structure of grafted fibers are studied by scanning electronic microscope ( SEM ), infra-red spectrophotometer (IR), and differential scanning calorimetry( DSC ). At the same time, the moisture regain, dyeability, strength, and elongation at break of the samples are measured and their relations with structural changes are discussed. Compared with ungrafted fiber, shape of the fiber cross-section, IR characteristic absorption peaks, and melting behavior of the grafted fibers have been changed, causing the fiber dyeability and moisture regain to be increased, and mechanical properties to be changed.

  3. Extracellular Matrix components regulate cellular polarity and tissue structure in the developing and mature Retina

    Directory of Open Access Journals (Sweden)

    Shweta Varshney

    2015-01-01

    Full Text Available While genetic networks and other intrinsic mechanisms regulate much of retinal development, interactions with the extracellular environment shape these networks and modify their output. The present review has focused on the role of one family of extracellular matrix molecules and their signaling pathways in retinal development. In addition to their effects on the developing retina, laminins play a role in maintaining Müller cell polarity and compartmentalization, thereby contributing to retinal homeostasis. This article which is intended for the clinical audience, reviews the fundamentals of retinal development, extracellular matrix organization and the role of laminins in retinal development. The role of laminin in cortical development is also briefly discussed.

  4. Light-induced structural changes in a monomeric bacteriophytochrome

    Science.gov (United States)

    Takala, Heikki; Niebling, Stephan; Berntsson, Oskar; Björling, Alexander; Lehtivuori, Heli; Häkkänen, Heikki; Panman, Matthijs; Gustavsson, Emil; Hoernke, Maria; Newby, Gemma; Zontone, Federico; Wulff, Michael; Menzel, Andreas; Ihalainen, Janne A.; Westenhoff, Sebastian

    2016-01-01

    Phytochromes sense red light in plants and various microorganism. Light absorption causes structural changes within the protein, which alter its biochemical activity. Bacterial phytochromes are dimeric proteins, but the functional relevance of this arrangement remains unclear. Here, we use time-resolved X-ray scattering to reveal the solution structural change of a monomeric variant of the photosensory core module of the phytochrome from Deinococcus radiodurans. The data reveal two motions, a bend and a twist of the PHY domain with respect to the chromophore-binding domains. Infrared spectroscopy shows the refolding of the PHY tongue. We conclude that a monomer of the phytochrome photosensory core is sufficient to perform the light-induced structural changes. This implies that allosteric cooperation with the other monomer is not needed for structural activation. The dimeric arrangement may instead be intrinsic to the biochemical output domains of bacterial phytochromes. PMID:27679804

  5. In-depth imaging and quantification of degenerative changes associated with Achilles ruptured tendons by polarization-sensitive optical coherence tomography

    Science.gov (United States)

    Bagnaninchi, P. O.; Yang, Y.; Bonesi, M.; Maffulli, G.; Phelan, C.; Meglinski, I.; El Haj, A.; Maffulli, N.

    2010-07-01

    The objective of this study was to develop a method based on polarization-sensitive optical coherent tomography (PSOCT) for the imaging and quantification of degenerative changes associated with Achilles tendon rupture. Ex vivo PSOCT examinations were performed in 24 patients. The study involved samples from 14 ruptured Achilles tendons, 4 tendinopathic Achilles tendons and 6 patellar tendons (collected during total knee replacement) as non-ruptured controls. The samples were imaged in both intensity and phase retardation modes within 24 h after surgery, and birefringence was quantified. The samples were fixed and processed for histology immediately after imaging. Slides were assessed twice in a blind manner to provide a semi-quantitative histological score of degeneration. In-depth micro structural imaging was demonstrated. Collagen disorganization and high cellularity were observable by PSOCT as the main markers associated with pathological features. Quantitative assessment of birefringence and penetration depth found significant differences between non-ruptured and ruptured tendons. Microstructure abnormalities were observed in the microstructure of two out of four tendinopathic samples. PSOCT has the potential to explore in situ and in-depth pathological change associated with Achilles tendon rupture, and could help to delineate abnormalities in tendinopathic samples in vivo.

  6. In-depth imaging and quantification of degenerative changes associated with Achilles ruptured tendons by polarization-sensitive optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Bagnaninchi, P O; Yang, Y; Maffulli, G; El Haj, A; Maffulli, N [Institute for Science and Technology in Medicine, Keele University, Thornburrow Drive, Hartshill, Stoke-on-Trent ST4 7QB (United Kingdom); Bonesi, M; Meglinski, I [Cranfield Health, Cranfield University, Cranfield MK43 0AL (United Kingdom); Phelan, C, E-mail: pierre.bagnaninchi@ed.ac.u [Department of Pathology, University Hospital of North Staffordshire, Stoke-on-Trent ST4 7QB (United Kingdom)

    2010-07-07

    The objective of this study was to develop a method based on polarization-sensitive optical coherent tomography (PSOCT) for the imaging and quantification of degenerative changes associated with Achilles tendon rupture. Ex vivo PSOCT examinations were performed in 24 patients. The study involved samples from 14 ruptured Achilles tendons, 4 tendinopathic Achilles tendons and 6 patellar tendons (collected during total knee replacement) as non-ruptured controls. The samples were imaged in both intensity and phase retardation modes within 24 h after surgery, and birefringence was quantified. The samples were fixed and processed for histology immediately after imaging. Slides were assessed twice in a blind manner to provide a semi-quantitative histological score of degeneration. In-depth micro structural imaging was demonstrated. Collagen disorganization and high cellularity were observable by PSOCT as the main markers associated with pathological features. Quantitative assessment of birefringence and penetration depth found significant differences between non-ruptured and ruptured tendons. Microstructure abnormalities were observed in the microstructure of two out of four tendinopathic samples. PSOCT has the potential to explore in situ and in-depth pathological change associated with Achilles tendon rupture, and could help to delineate abnormalities in tendinopathic samples in vivo.

  7. In-depth imaging and quantification of degenerative changes associated with Achilles ruptured tendons by polarization-sensitive optical coherence tomography

    International Nuclear Information System (INIS)

    The objective of this study was to develop a method based on polarization-sensitive optical coherent tomography (PSOCT) for the imaging and quantification of degenerative changes associated with Achilles tendon rupture. Ex vivo PSOCT examinations were performed in 24 patients. The study involved samples from 14 ruptured Achilles tendons, 4 tendinopathic Achilles tendons and 6 patellar tendons (collected during total knee replacement) as non-ruptured controls. The samples were imaged in both intensity and phase retardation modes within 24 h after surgery, and birefringence was quantified. The samples were fixed and processed for histology immediately after imaging. Slides were assessed twice in a blind manner to provide a semi-quantitative histological score of degeneration. In-depth micro structural imaging was demonstrated. Collagen disorganization and high cellularity were observable by PSOCT as the main markers associated with pathological features. Quantitative assessment of birefringence and penetration depth found significant differences between non-ruptured and ruptured tendons. Microstructure abnormalities were observed in the microstructure of two out of four tendinopathic samples. PSOCT has the potential to explore in situ and in-depth pathological change associated with Achilles tendon rupture, and could help to delineate abnormalities in tendinopathic samples in vivo.

  8. Three-dimensionally modulated anisotropic structure for diffractive optical elements created by one-step three-beam polarization holographic photoalignment

    Science.gov (United States)

    Kawai, Kotaro; Sakamoto, Moritsugu; Noda, Kohei; Sasaki, Tomoyuki; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2016-03-01

    A diffractive optical element with a three-dimensional liquid crystal (LC) alignment structure for advanced control of polarized beams was fabricated by a highly efficient one-step photoalignment method. This study is of great significance because different two-dimensional continuous and complex alignment patterns can be produced on two alignment films by simultaneously irradiating an empty glass cell composed of two unaligned photocrosslinkable polymer LC films with three-beam polarized interference beam. The polarization azimuth, ellipticity, and rotation direction of the diffracted beams from the resultant LC grating widely varied depending on the two-dimensional diffracted position and the polarization states of the incident beams. These polarization diffraction properties are well explained by theoretical analysis based on Jones calculus.

  9. THE STRUCTURE AND LINEAR POLARIZATION OF THE KILOPARSEC-SCALE JET OF THE QUASAR 3C 345

    International Nuclear Information System (INIS)

    Deep Very Large Array imaging of the quasar 3C 345 at 4.86 and 8.44 GHz has been used to study the structure and linear polarization of its radio jet on scales ranging from 2 to 30 kpc. There is a 7-8 Jy unresolved core with spectral index α ≅ –0.24 (Iν∝να). The jet (typical intensity 15 mJy beam–1) consists of a 2.''5 straight section containing two knots, and two additional non-co-linear knots at the end. The jet's total projected length is about 27 kpc. The spectral index of the jet varies over –1.1 ∼ 0.5. Despite the indication of jet precession in the total intensity structure, the polarization images suggest instead a jet re-directed at least twice by collisions with the external medium. Surprisingly, the electric vector position angles in the main body of the jet are neither longitudinal nor transverse, but make an angle of about 55° with the jet axis in the middle while along the edges the vectors are transverse, suggesting a helical magnetic field. There is no significant Faraday rotation in the source, so that is not the cause of the twist. The fractional polarization in the jet averages 25% and is higher at the edges. In a companion paper, Roberts and Wardle show that differential Doppler boosting in a diverging relativistic velocity field can explain the electric vector pattern in the jet.

  10. CALCULATION OF THE FINE STRUCTURE OF OXYGEN-LIKE IONS USING THE POLARIZATION POTENTIAL FUNCTION

    Institute of Scientific and Technical Information of China (English)

    SHENG YONG; WANG RONG; JIANG GANG; ZHU ZHENG-HE

    2001-01-01

    We have calculated the forbidden transition energies and magnetic dipole transition probabilities of 2s22p4(3pl-3P2) and 2s22p4 (3p0-3p1) of oxygen-like isoelectronic sequences (Z=10-32) by a method of polarization potential correction. The transition energies show good agreement with experiment and are much better than the calculations in the literature. These results also illustrate that it is feasible to use the dipole expansion of the polarization potential to deal with some dynamic and non-dynamic effects in the central field approach. The relation of polarizability and cut-off radius with atomic number is discussed. We also give the fitted formula between the polarizability α1 and atomic number Z as c1 =0.73429-9.56644× 10-4Z+7.43016× 10-5Z2 -2.53298×10-6Z3+2.08306× 10-8Z4.

  11. North polar region of Mars: Advances in stratigraphy, structure, and erosional modification

    Science.gov (United States)

    Tanaka, Kenneth L.; Rodriguez, J. Alexis P.; Skinner, James A.; Bourke, Mary C.; Fortezzo, Corey M.; Herkenhoff, Kenneth E.; Kolb, Eric J.; Okubo, Chris H.

    2008-08-01

    We have remapped the geology of the north polar plateau on Mars, Planum Boreum, and the surrounding plains of Vastitas Borealis using altimetry and image data along with thematic maps resulting from observations made by the Mars Global Surveyor, Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter spacecraft. New and revised geographic and geologic terminologies assist with effectively discussing the various features of this region. We identify 7 geologic units making up Planum Boreum and at least 3 for the circumpolar plains, which collectively span the entire Amazonian Period. The Planum Boreum units resolve at least 6 distinct depositional and 5 erosional episodes. The first major stage of activity includes the Early Amazonian (˜3 to 1 Ga) deposition (and subsequent erosion) of the thick (locally exceeding 1000 m) and evenly-layered Rupes Tenuis unit (A Brt), which ultimately formed approximately half of the base of Planum Boreum. As previously suggested, this unit may be sourced by materials derived from the nearby Scandia region, and we interpret that it may correlate with the deposits that regionally underlie pedestal craters in the surrounding lowland plains. The second major episode of activity during the Middle to Late Amazonian ( ˜Olympia Planum underlying the dunes of Olympia Undae are interpreted to consist mostly of the Planum Boreum cavi unit (A Bb c). Planum Boreum materials were then deeply eroded to form spiral troughs, Chasma Boreale, and marginal scarps that define the major aspects of the polar plateau's current regional topography. Locally- to regionally-extensive (though vertically minor) episodes of deposition of evenly-bedded, light- and dark-toned layered materials and subsequent erosion of these materials persisted throughout the Late Amazonian. Sand saltation, including dune migration, is likely to account for much of the erosion of Planum Boreum, particularly at its margin, alluding to the lengthy sedimentological history of the

  12. Measurements of relativistic emission from runaway electrons in Alcator C-Mod: spectrum, polarization, and spatial structure

    Science.gov (United States)

    Granetz, Robert; Mumgaard, Robert

    2014-10-01

    At low densities, runaway electrons (RE's) can be generated during the flattop of Alcator C-Mod discharges with highly relativistic energies, γ >> 1 , allowing careful study under steady conditions. These RE's emit light in a narrow forward-peaked cone which is detected with a number of diagnostics, including spectrometers, a video imaging camera, and polarimetry (using the MSE system), in addition to the standard hard x-ray detectors. These measurements of the relativistic emission can provide information about the RE energy distribution, pitch angle distribution, and spatial distribution. Unlike most other tokamaks, C-Mod's high magnetic field shifts the peak of the continuum emission into the visible, due to the smaller gyroradius and higher gyro-frequency, allowing for excellent spectral coverage with standard spectrometers, and thus detailed comparison to theoretical predictions of synchrotron and bremsstrahlung spectra. Additionally, camera images occasionally show highly structured formations. Profiles of the polarization fraction and polarization angle show radial structure, including a jump of 90° outboard of the magnetic axis, in qualitative agreement with recent theoretical calculations for relativistic electrons in a tokamak field. This work is supported by the U.S. Department of Energy.

  13. Macro- and microscopic spectral-polarization characteristics of the structure of normal and abnormally located chordae tendianeae of left ventricular

    Science.gov (United States)

    Malyk, Yu. Yu.; Prydij, O. G.; Zymnyakov, D. A.; Alonova, M. V.; Ushakova, O. V.

    2013-12-01

    The morphological peculiarities of TS mitral valve of the heart of man in normal and abnormal spaced strings of the left ventricle and the study of their structural features depending on the location was studied. There are given the results of comparative statistics, correlation and fractal study population Mueller-matrix images (MMI) of healthy and abnormal (early forms that are not diagnosed by histological methods) BT normal and abnormally located tendon strings left ventricle of the human heart. Abnormalities in the structure of the wings, tendon strings (TS), mastoid muscle (MM) in inconsistencies elements and harmonized operation of all valve complex shown in the features of the polarization manifestations of it laser images.

  14. A polarization insensitive and broadband metamaterial absorber based on three-dimensional structure

    Science.gov (United States)

    Tang, Jingyao; Xiao, Zhongyin; Xu, Kaikai; Liu, Dejun

    2016-08-01

    In this paper, we propose a three-dimensional metamaterial absorber based on tailored resistive film patch array. The numerical results show that a broadband abs orption more than 90% can be achieved from 58.6 to 91.4 GHz for either transverse electric or magnetic polarization wave at normal incidence. And the E-field, surface current and power loss density distributions in the absorber are investigated to explain the physical mechanism of high absorption. In addition, the absorption efficiency of oblique incidence is also elucidated. According to the analysis of the E-field and power loss density distributions, we explain the absorption differences between TE and TM mode at oblique incidence. The proposed metamaterial absorber will pave the way for practical applications, such as sensing, imaging and stealth technology. Importantly, the design idea has the ability to be extended to terahertz, infrared and optical region.

  15. Polarization versus Temperature in Pyridinium Ionic Liquids

    DEFF Research Database (Denmark)

    Chaban, V. V.; Prezhdo, O. V.

    2014-01-01

    Electronic polarization and charge transfer effects play a crucial role in thermodynamic, structural, and transport properties of room-temperature ionic liquids (RTILs). These nonadditive interactions constitute a useful tool for tuning physical chemical behavior of RTILs. Polarization and charge...... interactions changes negligibly between 300 and 900 K, while the average dipole moment increases due to thermal fluctuations of geometries. Our results contribute to the fundamental understanding of electronic effects in the condensed phase of ionic systems and foster progress in physical chemistry...

  16. Family Structure Changes and Children's Health, Behavior, and Educational Outcomes

    DEFF Research Database (Denmark)

    Rasmussen, Astrid Würtz

    More and more children do not grow up in traditional nuclear families. Instead they grow up in single parent households or in families with a step-parent. Hence it is important to improve our understanding of the impact of "shocks" in family structure due to parental relationship dissolution...... on children. In this study I empirically test whether children are traumatized both in the short and the long run by shocks in the family structure during childhood. I focus on educational, behavioral, and health outcomes. A population sample of Danish children born in January to May 1983, 1984, and 1985...... is used for the analysis. The empirical cross-sectional analysis indicates a negative relation between the number of family structure changes and children.s educational outcomes. Children experiencing many family structure changes also seem to have worse health outcomes....

  17. Family Structure Changes and Children's Health, Behavior, and Educational Outcomes

    DEFF Research Database (Denmark)

    Rasmussen, Astrid Würtz

    More and more children do not grow up in traditional nuclear families. Instead they grow up in single parent households or in families with a step-parent. Hence it is important to improve our understanding of the impact of 'shocks' in family structure due to parental relationship dissolution...... on children. In this study I empirically test whether children are traumatized by shocks in the family structure during childhood. I focus on both educational, behavioral, and health outcomes. A population sample of Danish children born in January to May 1983, 1984, and 1985 is used for the analysis....... The empirical cross-sectional analysis indicates a negative relation between the number of family structure changes and children's educational outcomes. Children experiencing many family structure changes also seem to have worse health outcomes....

  18. Family Structure Changes and Children's Health, Behavior, and Educational Outcomes

    DEFF Research Database (Denmark)

    Rasmussen, Astrid Würtz

    relation between family structure changes and children's outcomes. Children who have experienced family structure changes during childhood seem to have worse educational outcomes and a higher propensity to being hospitalized and convicted of a crime. The children in the dataset experience up to 13 family...... decreased to 73% in 2005. Hence it is important to improve our understanding of the impact of "shocks" in family structure due to parental relationship dissolution on children. International studies mainly suggest a negative relationship between non-nuclear family structure and child outcomes. There are two...... childhood. I focus on educational, behavioral and health outcomes and investigate both the selection and causation explanations. For the estimations I use a Danish administrative register dataset with the full population of children born in January to May 1983, 1984, and 1985. I find a clear negative...

  19. The structural change of Cu-Sn melt

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With the high-temperature viscometer and magnetic susceptibility measurement device designed by our group,the viscosity and the magnetic susceptibility of the Cu65Sn35 melt were measured during the cooling process.An anomalous change can be found in the curves of viscosity and magnetic susceptibility at a certain temperature.The structure of the melt was studied by the high-temperature X-ray diffractometer.The anomalous change also can be found in the pair distribution function,correlation radius,and coordination number at the approximate tem-perature,which shows the microstructural change of the Cu65Sn35 melt.From the results,it was confirmed that the Cu6Sn5 compound occurs in the melt,which leads to the structural change of the melt.

  20. The structural change of Cu-Sn melt

    Institute of Scientific and Technical Information of China (English)

    HOU JiXin; SUN JianJun; ZHAN ChengWei; TIAN XueLei; CHEN XiChen

    2007-01-01

    With the high-temperature viscometer and magnetic susceptibility measurement device designed by our group, the viscosity and the magnetic susceptibility of the Cu65Sn35 melt were measured during the cooling process. An anomalous change can be found in the curves of viscosity and magnetic susceptibility at a certain temperature. The structure of the melt was studied by the high-temperature X-ray diffractometer. The anomalous change also can be found in the pair distribution function, correlation radius, and coordination number at the approximate temperature, which shows the microstructural change of the Cu65Sn35 melt. From the results, it was confirmed that the Cu6Sn5 compound occurs in the melt, which leads to the structural change of the melt.

  1. Reversible Magnetization of Ferrite-Garnet Film by Polarized Light

    OpenAIRE

    Sohatsky, V.; Kovalenko, V.

    1997-01-01

    The effect of low-powered polarized light on magnetic characteristics of ferrimagnetic garnet films has been studied at room temperatures by means of magneto-optical Faraday effect. A local magnetization of the film, occurred under the illumination, was carried out in the direction determined by orientation of polarization vector. The effect, accompanied by the domain structure reconstruction, caused also changes of the mechanical strain and dichroism. The spectral, polarization, amplitude an...

  2. Directed technical change and energy intensity dynamics: Structural change vs. energy efficiency

    OpenAIRE

    Haas, Christian; Kempa, Karol

    2016-01-01

    This paper uses a theoretical model with Directed Technical Change to analyse the observed heterogeneous energy intensity developments. Based on the empirical evidence on the underlying drivers of energy intensity developments, we decompose changes in aggregate energy intensity into structural changes in the economy (Sector Effect) and within-sector energy efficiency improvements (Efficiency Effect). We analyse how energy price growth and the relative productivity of both sectors affect the d...

  3. Structural Changes in Rice Bran Protein upon Different Extrusion Temperatures: A Raman Spectroscopy Study

    Directory of Open Access Journals (Sweden)

    Linyi Zhou

    2016-01-01

    Full Text Available Raman spectroscopy is critically evaluated to establish the limits to which it may be used to detect changes in protein conformation upon extrusion. Rice bran protein (RBP extruded with different temperatures (100, 120, 140, and 160°C, labeled as ERBP- was considered. DSC showed that extrusion at 100°C increased TD of RBP but decreased its ΔH, while, after extrusion treatment at 120°C, RBP completely denatured. A progressive increase in unordered structure and a general decrease in α-helix structure and β-sheet structure of extruded RBP were observed from Raman study. Meanwhile the content of unordered structure increased up to 140°C and then decreased at 160°C, while the trend of α-helix and β-sheet content was opposite, which was contributed to the composite effect of formation of some more protein aggregation and protein denaturation. Extrusion generally induced a significant decrease in Trp band near 760 cm−1 but an increase at 160°C. No significant difference was observed in Tyr doublet ratios between controlled RBP samples and extruded RBP below 160°C, whereas Tyr doublet ratios of extruded RBP decreased at 160°C. Intensity of the band assigned to CHn bending decreased progressively and then increased as extrusion temperature increased, indicating changes in microenvironment and polarity.

  4. Structural Change, Globalization and Economic Growth in China and India

    Directory of Open Access Journals (Sweden)

    Vittorio Valli

    2015-12-01

    Full Text Available In their period of rapid economic growth China and India have experienced profound structural transformations. The aim of the paper is to analyze the relation between structural change, the process of globalization and economic growth in the two great Asian countries, using a highly disaggregated dataset for the 1987-2009 period. While China had a longer and more intensive productivity growth than India, the latter had a somewhat more balanced growth. Both countries registered higher within-sectors gains in productivity than between-sectors ones. Our analysis also shows that there exist important feedbacks between structural change, globalization and economic growth over time. When the reallocation of labor is large, it may positively impact on the future rates of economic growth. At the same time, however, it seems that a too rapid economic growth may hinder a smooth reallocation of labor. In both countries, new policies should be designed to favor labor movement across sectors and areas, to reduce the wage-productivity differentials and to integrate the informal sector in formal markets in India, in order to foster structural changes and enhance economic growth. If a too unbalanced economic growth has somewhat limited the extent of structural change, globalization has on the contrary promoted it. High level of export, import and FDI not only has been related to higher rates of economic growth, but also to a deeper reallocation of resources across sectors, modifying the comparative advantage and reorganizing the production.

  5. Oil exports, structural change, and economic development in Iran

    Energy Technology Data Exchange (ETDEWEB)

    Emami-Khoi, A.

    1981-01-01

    Within the broad Chenery-Kuznets framework, using structural change as a major indicator of economic development, this study investigates the direction and magnitude and broad features of structural change in Iran, and the role of oil production and exports in that change. Although the study covers a larger horizon, the analysis is focused on the period 1955 through 1977. A similar but less-detailed investigation is conducted for Algeria, Indonesia, and Venezuela also, and a cross-country, comparative perspective is generated. The study shows that, in general, the structural changes in Iran have either been weak (for example, in production and employment), or they are contrary to what the model would predict (for instance in trade). The pattern of structural change observed in Iran, therefore, does not indicate any significant economic development even though per capita income increased five-fold over the period 1955 through 1977. In short, oil does not appear to have been an engine of economic development in Iran. The situation appears broadly similar for the other three countries. Based on these findings, the study offers some suggestions concerning the future economic strategies that should enhance very considerably the contribution that oil industry can make toward Iran's economic development, and should thus accelerate the pace of economic development. These suggestions may be useful to other oil-exporting countries as well.

  6. Employee experience of structural change in two Norwegian hospitals.

    Science.gov (United States)

    Roald, J; Edgren, L

    2001-01-01

    Advances in medical and technological procedures, together with changes in demography, demand structural changes in the Nordic health care systems. Few studies have focused on employee perceptions of these structural changes. This study aims to describe employee reactions following a merger between two Norwegian hospitals. A Grounded theory approach has been used in this study. The theoretical model is based on empirical data collected from employees directly affected by the structural change process. Employee resistance was found to be the core category. Three categories were found in relation to this core category; goal uncertainty, organizational culture and individual insecurity. Different perceptions and interpretations of vaguely formulated goals lead to employee resistance. The difference between the organizational cultures in the two hospitals impeded the merger according to the project plan, and very few positive results could be seen. Individual insecurity regarding the future was experienced in connection with the implementation of structural change. The authors propose a strategy to counteract resistance in similar mergers. PMID:11771150

  7. Analytical model and new structure of the enhancement-mode polarization-junction HEMT with vertical conduction channel

    Science.gov (United States)

    Yang, Chao; Xiong, Jiayun; Wei, Jie; Wu, Junfeng; Peng, Fu; Deng, Siyu; Zhang, Bo; Luo, Xiaorong

    2016-04-01

    A novel enhancement-mode (E-mode) polarization-junction HEMT with vertical conduction channel (PVC-HEMT) is proposed, and its analytical model for threshold voltage (Vth) is presented. It has two features: one is GaN/AlGaN/GaN double hetero-structure, the other is that source and drain locate at the same side of trench-type MOS gate (T-gate), and the source contacts with the T-gate, which forms vertical conduction channel (VC). The 2-D hole gas (2-DHG) and 2-D electron gas (2-DEG) are formed at the GaN-top/AlGaN and AlGaN/GaN-buffer interface, respectively, forming the polarization-junction. First, the E-mode operation is realized because 2-DHG under the source prevents the electrons injecting from source to 2-DEG, breaking through the conventional E-mode method by depleting 2-DEG under the gate. Second, a uniform electric field (E-field) distribution is achieved due to the assisted depletion effect by polarization-junction. Third, the source reduces the E-field peak at the T-gate side and modulates the E-field distribution. The breakdown voltage (BV) of PVC-HEMT is 705 V and specific ON-resistance (RON,sp) is 1.18 mΩ cm2. Compared with conventional HEMT (C-HEMT), PVC-HEMT has a smaller size due to the special location of the source and T-gate. An analytic threshold voltage model is presented and the analytical results agree well with the simulated results.

  8. Labor mobility, trade and structural change: the Philippine experience.

    Science.gov (United States)

    Abella, M I

    1993-01-01

    "This article addresses three questions: (1) Is the high rate of emigration of labor from the Philippines related to the country's trade policy? (2) Why have migration and accompanying remittances not made much of an impact on the growth and structure of the Philippine economy? (3) Would economic growth and structural change eventually curtail labor emigration? The Philippines' history of labor export and its economic development are contrasted with those of Asian NIEs [newly industrialized economies] which have adopted liberal trade regimes."

  9. Changes in corporate governance structures in Polish privatised companies

    OpenAIRE

    Kozarzewski, P.

    2002-01-01

    The paper presents early results of the survey of 84 Polish privatised industrial companies, sampled from a list of the 500 biggest firms. Three aspects of corporate governance were analysed: ownership structure, management of the companies, and supervision structures. An attempt was made to assess the influence of corporate governance characterisics on companies' performance. The main conclusion of the paper is that privatisation of the largest enterprises resulted in deep changes to their c...

  10. Does competitive entry structurally change key marketing metrics?

    OpenAIRE

    Kornelis, M.; Dekimpe, de, M.G.; Leeflang, P.S.H.

    2008-01-01

    To what extent does competitive entry create a structural change in keymarketingmetrics? New players may just be a temporal nuisance to incumbents, but could also fundamentally change the latter's performance evolution, or induce them to permanently alter their spending levels and/or pricing decisions. Similarly, the addition of a new marketing channel could permanently shift shopping preferences, or could just create a short-lived migration from existing channels. The steady-state impact of ...

  11. Technological and Structural Change in the European Banking Industry

    OpenAIRE

    Panapoulou, Maria

    2002-01-01

    The world banking industry is undergoing a large-scale transformation. Banking systems and financial markets, both domestic and international, have been undergoing a series of profound changes. One of the main driving forces of these worldwide changes is the introduction of innovations in new information technologies. Against these trends, industrial structure in the banking industry and banking regulation have sometimes encouraged these trends and sometimes adapted to them. The aim of this p...

  12. An analysis of structure change of food demand in China

    OpenAIRE

    Wang, Guanqing

    2014-01-01

    The estimation of consumer demand is playing an important role in applied econometrics. Chinese food demand has fundamentally changed as the result of growing income and urbanization ever since the economic reform in 1978. Although food demand of the western countries has been widely studied in the literature, the study of demand in the developing countries like China has been much ignored. In this study, we aim at analyzing structure changes of food demands in China. We intend to estimate Ch...

  13. Structural decomposition analysis on energy intensity changes at regional level

    OpenAIRE

    Hua Liao; Ce Wang; Zhi-Shuang Zhu; Xiao-Wei Ma

    2012-01-01

    As China's energy intensity fluctuated in recent years, it is necessary to examine whether this fluctuations happened at a regional level. This paper conducts a decomposition model by using the structural decomposition analysis (SDA) method at a regional level. Then this model is employed to empirically analyze the changes of Beijing's energy intensity. The conclusions are as follows: during 2002-2010, except petroleum, the energy intensity decreased and the changes were mostly attributed to ...

  14. Statistical methods in longitudinal research principles and structuring change

    CERN Document Server

    von Eye, Alexander

    1991-01-01

    These edited volumes present new statistical methods in a way that bridges the gap between theoretical and applied statistics. The volumes cover general problems and issues and more specific topics concerning the structuring of change, the analysis of time series, and the analysis of categorical longitudinal data. The book targets students of development and change in a variety of fields - psychology, sociology, anthropology, education, medicine, psychiatry, economics, behavioural sciences, developmental psychology, ecology, plant physiology, and biometry - with basic training in statistics an

  15. Structural change in developing countries: Has it decreased gender inequality?

    OpenAIRE

    Rendall, Michelle

    2012-01-01

    This paper examines the evolution of female labor market outcomes from 1987 to 2008 by assessing the role of changing labor demand requirements in four developing countries: Brazil, Mexico, India and Thailand. The results highlight the importance of structural change in reducing gender disparities by decreasing the labor demand for physical attributes. The results show that India, the country with the greatest physical labor requirements, exhibits the largest labor market gender inequality. I...

  16. Bias and population structure in the actuation of sound change

    CERN Document Server

    Kirby, James

    2015-01-01

    Why do human languages change at some times, and not others? We address this longstanding question from a computational perspective, focusing on the case of sound change. Sound change arises from the pronunciation variability ubiquitous in every speech community, but most such variability does not lead to change. Hence, an adequate model must allow for stability as well as change. Existing theories of sound change tend to emphasize factors at the level of individual learners promoting one outcome or the other, such as channel bias (which favors change) or inductive bias (which favors stability). Here, we consider how the interaction of these biases can lead to both stability and change in a population setting. We find that population structure itself can act as a source of stability, but that both stability and change are possible only when both types of bias are active, suggesting that it is possible to understand why sound change occurs at some times and not others as the population-level result of the inte...

  17. A stretch-tunable plasmonic structure with a polarization-dependent response

    DEFF Research Database (Denmark)

    Zhu, Xiaolong; Xiao, Sanshui; Shi, Lei;

    2012-01-01

    We experimentally demonstrate a stretchable plasmonic structure composed of a monolayer array of gold semishells with dielectric cores on an elastic PDMS substrate. The composite structure is fabricated using simple and inexpensive self-assembly and transfer-printing techniques, and it supports B...

  18. Asymmetric bistable reflection and polarization switching in a magnetic nonlinear multilayer structure

    DEFF Research Database (Denmark)

    Tuz, Vladimir R.; Novitsky, Denis V.; Prosvirnin, Sergey L.;

    2014-01-01

    Optical properties of one-dimensional photonic structures consisting of Kerr-type nonlinear and magnetic layers under the action of an external static magnetic field in the Faraday geometry are investigated. The structure is a periodic arrangement of alternating nonlinear and magnetic layers (a o...

  19. Radar altimetry measurements over antarctic ice sheet: A focus on antenna polarization and change in backscatter problems

    Science.gov (United States)

    Remy, F.; Flament, T.; Blarel, F.; Benveniste, J.

    2012-10-01

    In this paper, we investigate the impact of the error due to the penetration of the altimetric wave within the snowpack. The phenomenon has two different impacts. The first one, due to temporal change in snow characteristics, affects the ice sheet volume trend as derived from altimetric series. The second one, because of both the anisotropy of the ice sheet surface properties and of the linear antenna polarization, introduces a difference in measurements at crossover points. These two phenomena are the cause of what are probably the most critical limitations to the interpretation of long-term altimetric series in term of mass balance and to the comparison between or data fusion of different missions. Moreover, they will lead to the largest error when comparing data from EnviSat with data from CryoSat, because of the different orbits, or with data from AltiKa, because of the different radar frequencies. We show that waveform distortions due to snow characteristics fluctuation are complex. In the central part of the East Antarctica, the height and the leading edge width fluctuations vary together while elsewhere, height fluctuations may occur with no variations in the waveform shape, mostly during winter. As a consequence, these induced errors cannot be corrected with solely the help of the backscatter: waveform shape parameters are also needed. They are however not enough to fully correct these two errors. We propose an empirical correction for these effects. We show that crossover differences may be significantly reduced to up 22 cm. In terms of volume change, the estimation may vary up to 4 cm/yr at cross-overs depending on the correction used and is reduced in average to 2.3 cm/yr with our correction. The difference between the height trends estimated with both corrections is weak in average but may locally reach 5 cm/yr with a clear geographical pattern.

  20. Muscle structural changes in mitochondrial myopathy relate to genotype

    DEFF Research Database (Denmark)

    Olsen, David B.; Langkilde, Annika Reynberg; Ørngreen, Mette C.;

    2003-01-01

    typically not been associated with mitochondrial disease. We investigated gross and microscopic muscle morphology in thigh muscles by muscle biopsy and MRI in 16 patients with MM, and compared findings with those obtained in muscular dystrophy patients and healthy subjects. Changes of muscle architecture......It is well known that morphological changes at the cellular level occur in muscle of patients with mitochondrial myopathy (MM), but changes in muscle structure with fat infiltration and gross variation of muscle fiber size with giant fibers, normally encountered in the muscular dystrophies, have...

  1. Muscle structural changes in mitochondrial myopathy relate to genotype

    DEFF Research Database (Denmark)

    Olsen, David B.; Langkilde, Annika Reynberg; Ørngreen, Mette C.;

    2003-01-01

    It is well known that morphological changes at the cellular level occur in muscle of patients with mitochondrial myopathy (MM), but changes in muscle structure with fat infiltration and gross variation of muscle fiber size with giant fibers, normally encountered in the muscular dystrophies, have...... typically not been associated with mitochondrial disease. We investigated gross and microscopic muscle morphology in thigh muscles by muscle biopsy and MRI in 16 patients with MM, and compared findings with those obtained in muscular dystrophy patients and healthy subjects. Changes of muscle architecture...

  2. Polarization enhancement and ferroelectric switching enabled by interacting magnetic structures in DyMnO3 thin films

    KAUST Repository

    Lu, Chengliang

    2013-12-02

    The mutual controls of ferroelectricity and magnetism are stepping towards practical applications proposed for quite a few promising devices in which multiferroic thin films are involved. Although ferroelectricity stemming from specific spiral spin ordering has been reported in highly distorted bulk perovskite manganites, the existence of magnetically induced ferroelectricity in the corresponding thin films remains an unresolved issue, which unfortunately halts this step. In this work, we report magnetically induced electric polarization and its remarkable response to magnetic field (an enhancement of ?800% upon a field of 2 Tesla at 2 K) in DyMnO3 thin films grown on Nb-SrTiO3 substrates. Accompanying with the large polarization enhancement, the ferroelectric coercivity corresponding to the magnetic chirality switching field is significantly increased. A picture based on coupled multicomponent magnetic structures is proposed to understand these features. Moreover, different magnetic anisotropy related to strain-suppressed GdFeO 3-type distortion and Jahn-Teller effect is identified in the films.

  3. On the recovery of ISW fluctuations using large-scale structure tracers and CMB temperature and polarization anisotropies

    CERN Document Server

    Bonavera, L; Marcos-Caballero, A; Vielva, P

    2016-01-01

    In this work we present a method to extract the signal induced by the integrated Sachs-Wolfe (ISW) effect in the cosmic microwave background (CMB). It makes use of the Linear Covariance-Based filter introduced by Barreiro et al., and combines CMB data with any number of large-scale structure (LSS) surveys and lensing information. It also exploits CMB polarization to reduce cosmic variance. The performance of the method has been thoroughly tested with simulations taking into account the impact of non-ideal conditions such as incomplete sky coverage or the presence of noise. In particular, three galaxy surveys are simulated, whose redshift distributions peak at low ($z \\simeq 0.3$), intermediate ($z \\simeq 0.6$) and high redshift ($z \\simeq 0.9$). The contribution of each of the considered data sets as well as the effect of a mask and noise in the reconstructed ISW map is studied in detail. When combining all the considered data sets (CMB temperature and polarization, the three galaxy surveys and the lensing ma...

  4. Polarization response of nanowires à la carte.

    Science.gov (United States)

    Casadei, Alberto; Llado, Esther Alarcon; Amaduzzi, Francesca; Russo-Averchi, Eleonora; Rüffer, Daniel; Heiss, Martin; Dal Negro, Luca; Fontcuberta i Morral, Anna

    2015-01-01

    Thanks to their special interaction with light, semiconductor nanowires have opened new avenues in photonics, quantum optics and solar energy harvesting. One of the major challenges for their full technological deployment has been their strong polarization dependence in light absorption and emission. In the past, metal nanostructures have been shown to have the ability to modify and enhance the light response of nanoscale objects. Here we demonstrate that a hybrid structure formed by GaAs nanowires with a highly dense array of bow-tie antennas is able to modify the polarization response of a nanowire. As a result, the increase in light absorption for transverse polarized light changes the nanowire polarization response, including the polarization response inversion. This work will open a new path towards the widespread implementation of nanowires applications such as in photodetection, solar energy harvesting and light emission. PMID:25564366

  5. Internal structure changes of eyelash induced by eye makeup.

    Science.gov (United States)

    Fukami, Ken-Ichi; Inoue, Takafumi; Kawai, Tomomitsu; Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio

    2014-01-01

    To investigate how eye makeup affects eyelash structure, internal structure of eyelashes were observed with a scanning X-ray microscopic tomography system using synchrotron radiation light source. Eyelash samples were obtained from 36 Japanese women aged 20-70 years and whose use of eye makeup differed. Reconstructed cross-sectional images showed that the structure of the eyelash closely resembled that of scalp hair. The eyelash structure is changed by use of eye makeup. There was a positive correlation between the frequency of mascara use and the degree of cracking in cuticle. The positive correlation was also found between the frequency of mascara use and the porosity of the cortex. By contrast, the use of eyelash curler did not affect the eyelash structure with statistical significance.

  6. Atomistic mechanisms governing structural stability change of zinc antimony thermoelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaolong [Frontier Institute of Science and Technology, Xi' an Jiaotong University, Xi' an 710054 (China); Lin, Jianping, E-mail: jaredlin@163.com [School of Materials Science and Engineering, Xiamen University of Technology, Xiamen 361024 (China); Qiao, Guanjun [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, Zhao, E-mail: zwangzhao@gmail.com [Frontier Institute of Science and Technology, Xi' an Jiaotong University, Xi' an 710054 (China); State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

    2015-01-05

    The structural stability of thermoelectric materials is a subject of growing importance for their energy harvesting applications. Here, we study the microscopic mechanisms governing the structural stability change of zinc antimony at its working temperature, using molecular dynamics combined with experimental measurements of the electrical and thermal conductivity. Our results show that the temperature-dependence of the thermal and electrical transport coefficients is strongly correlated with a structural transition. This is found to be associated with a relaxation process, in which a group of Zn atoms migrates between interstitial sites. This atom migration gradually leads to a stabilizing structural transition of the entire crystal framework, and then results in a more stable crystal structure of β–Zn{sub 4}Sb{sub 3} at high temperature.

  7. Electric Field and Structural Phase Transition Induced Magnetization Effects in BaTiO3 -FeRh Heterostructures Probed using Polarized Neutron Reflectometry

    Science.gov (United States)

    Bennett, Steven; Ward, Thomas; Biegalski, Michael; Wong, Tony; Liu, Zhiqi; Ambaye, Haile; Glavic, Artur

    2015-03-01

    The ability to change the magnetic state of a material with an electric field opens up a plethora of possible devices in spintronics and memory applications. A strong candidate material for such a control is FeRh, whose magneto-structural phase transition from antiferromagnetic (AFM) to ferromagnetic (FM) at T ~350K, has shown to be controllably changed by an electric field when grown on ferroelectric BaTiO3 (BTO). It has been suggested that this shift is largely due to the -0.47% in plane compressive strain induced by the piezoelectric BTO. Here we show a sharp repeatable change in magnetization as the system is heated/cooled through the tetragonal to orthorhombic (280-290K) and orthorhombic to rhombohedral (180-205K) crystalline phase transitions of BTO. To further characterize the effect polarized neutron reflectometry (PNR) was used to evolve the depth profile of magnetization in FeRh within the temperature vicinity of these transitions with and without the application of electric field. This work was carried out at the Center for Nanophase Materials Sciences (CNMS) and the Spallation Neutron Source (SNS) supported by the Scientific User Facilities Divisions, Office of Basic Energy Sciences, DOE.

  8. Detailed structure of the outer disk around HD 169142 with polarized light in H-band

    CERN Document Server

    Momose, Munetake; Fukagawa, Misato; Muto, Takayuki; Takeuchi, Taku; Hashimoto, Jun; Honda, Mitsuhiko; Kudo, Tomoyuki; Okamoto, Yoshiko K; Kanagawa, Kazuhiro D; Tanaka, Hidekazu; Grady, Carol A; Sitko, Michael L; Akiyama, Eiji; Currie, Thayne; Follette, Katherine B; Mayama, Satoshi; Kusakabe, Nobuhiko; Abe, Lyu; Brandner, Wolfgang; Brandt, Timothy D; Carson, Joseph C; Egner, Sebastian; Feldt, Markus; Goto, Miwa; Guyon, Olivier; Hayano, Yutaka; Hayashi, Masahiko; Hayashi, Saeko S; Henning, Thomas; Hodapp, Klaus W; Ishii, Miki; Iye, Masanori; Janson, Markus; Kandori, Ryo; Knapp, Gillian R; Kuzuhara, Masayuki; Kwon, Jungmi; Matsuo, Taro; McElwain, Michael W; Miyama, Shoken; Morino, Jun-Ichi; Moro-Martin, Amaya; Nishimura, Tetsuo; Pyo, Tae-Soo; Serabyn, Eugene; Suenaga, Takuya; Suto, Hiroshi; Suzuki, Ryuji; Takahashi, Yasuhiro H; Takami, Michihiro; Takato, Naruhisa; Terada, Hiroshi; Thalmann, Christian; Tomono, Daigo; Turner, Edwin L; Watanabe, Makoto; Wisniewski, John; Yamada, Toru; Takami, Hideki; Usuda, Tomonori; Tamura, Motohide

    2015-01-01

    Coronagraphic imagery of the circumstellar disk around HD 169142 in H-band polarized intensity (PI) with Subaru/HiCIAO is presented. The emission scattered by dust particles at the disk surface in 0.2" <= r <= 1.2", or 29 <= r <= 174 AU, is successfully detected. The azimuthally-averaged radial profile of the PI shows a double power-law distribution, in which the PIs in r=29-52 AU and r=81.2-145 AU respectively show r^{-3}-dependence. These two power-law regions are connected smoothly with a transition zone (TZ), exhibiting an apparent gap in r=40-70 AU. The PI in the inner power-law region shows a deep minimum whose location seems to coincide with the point source at \\lambda = 7 mm. This can be regarded as another sign of a protoplanet in TZ. The observed radial profile of the PI is reproduced by a minimally flaring disk with an irregular surface density distribution or with an irregular temperature distribution or with the combination of both. The depletion factor of surface density in the inner...

  9. Structure and resistance of concentration polar layer on cation exchange membrane-solution interface

    Institute of Scientific and Technical Information of China (English)

    SANG Shang-bin; HUANG Ke-long; LI Xiao-gang; WANG Xian

    2006-01-01

    Membrane/solution interface consists of a neutral concentration polar layer(CPL) and a charge layer(CL) under external electrical field, and the neutral CPL can be neglected under high frequency AC electrical field. The relationship of CL thickness e with electrolyte concentration C and fixed ion exchange sites density σ in membrane surface layer can be expressed as e=σ/C.According to this model, the thickness of the CL on Nafion1135 membrane/solution interface(ec) was calculated under different membrane surface charge quantity Q and variable electrolyte concentration C. The membrane/solution interface CL thickness(em) is obviously related with the membrane properties, and decreases dramatically in a higher electrolyte concentration, em values are 76.3nm and 110.3 nm respectively for Nafion1135 and PE01 ion exchange membrane in 0.05 mol/L H2SO4 solution, and em values for both membrane tend to 2 nm in 2 mol/L H2SO4 solution. For Nafion1135 membrane, the comparison of ec and em gives the result that CL thickness em obtained by resistance measurement fits well with the calculated CPL thickness ec while proton in CL transferred to membrane surface is 14.56 × l0-10 mol, which corresponds to the fixed exchange group number in a surface layer with a thickness τ=2 nm for Nafion1135 membrane.

  10. Two-Dimensional Pnictogen Honeycomb Lattice: Structure, On-Site Spin-Orbit Coupling and Spin Polarization.

    Science.gov (United States)

    Lee, Jason; Tian, Wen-Chuan; Wang, Wei-Liang; Yao, Dao-Xin

    2015-01-01

    Because of its novel physical properties, two-dimensional materials have attracted great attention. From first-principle calculations and vibration frequencies analysis, we predict a new family of two-dimensional materials based on the idea of octet stability: honeycomb lattices of pnictogens (N, P, As, Sb, Bi). The buckled structures of materials come from the sp(3) hybridization. These materials have indirect band gap ranging from 0.43 eV to 3.7 eV. From the analysis of projected density of states, we argue that the s and p orbitals together are sufficient to describe the electronic structure under tight-binding model, and the tight-binding parameters are obtained by fitting the band structures to first-principle results. Surprisingly large on-site spin-orbit coupling is found for all the pnictogen lattices except nitrogen. Investigation on the electronic structures of both zigzag and armchair nanoribbons reveals the possible existence of spin-polarized ferromagnetic edge states in some cases, which are rare in one-dimensional systems. These edge states and magnetism may exist under the condition of high vacuum and low temperature. This new family of materials would have promising applications in electronics, optics, sensors, and solar cells. PMID:26122870

  11. Extinction Partially Reverts Structural Changes Associated with Remote Fear Memory

    Science.gov (United States)

    Vetere, Gisella; Restivo, Leonardo; Novembre, Giovanni; Aceti, Massimiliano; Lumaca, Massimo; Ammassari-Teule, Martine

    2011-01-01

    Structural synaptic changes occur in medial prefrontal cortex circuits during remote memory formation. Whether extinction reverts or further reshapes these circuits is, however, unknown. Here we show that the number and the size of spines were enhanced in anterior cingulate (aCC) and infralimbic (ILC) cortices 36 d following contextual fear…

  12. The structural changes in the Mexican coffee sector

    NARCIS (Netherlands)

    Padron, Benigno Rodriguez; Burger, Kees

    2016-01-01

    This paper analyses the structural changes which have been present since the economic clauses of the International Coffee Agreements have no longer been in effect. It studies the elements that modified the coffee policy over time. It also investigates the main characteristics of the entire coffee

  13. The Changing Social Structure of Music in India.

    Science.gov (United States)

    Joshi, O. P.

    1982-01-01

    Recent contact with harmonic and popular music has radically changed traditional forms of Indian music. The impact of Western music on classical styles, the social role of folk and popular music, and aspects of the social structure of music are discussed. (AM)

  14. Effective Organizational Structures and Processes: Addressing Issues of Change

    Science.gov (United States)

    Andrade, Maureen Snow

    2016-01-01

    This chapter describes organizational structures and processes at the institutional and project levels for the development and support of distance learning initiatives. It addresses environmental and stakeholder issues and explores principles and strategies of effective leadership for change creation and management.

  15. CHANGES IN THE CHEMICAL STRUCTURE OF THERMALLY TREATED WOOD

    Directory of Open Access Journals (Sweden)

    Birol Uner

    2010-07-01

    Full Text Available Changes in the chemical structure of hornbeam and uludag fir woods during thermal treatment were investigated at three temperatures (170, 190, and 210 oC and three durations (4, 8, and 12 hours. After thermal treatment, the extents of degradation in the chemical structure of the samples were determined, and the effects on the chemical composition of hornbeam wood and uludag fir wood were investigated. The data obtained were analyzed using variance analysis, and Tukey’s test was used to determine the changes in the chemical structure of uludag fir and hornbeam woods. The results showed that heating wood permanently changes several of its chemical structures and that the changes are mainly caused by thermal degradation of wood polymers. It was found that decreasing of the cellulose and holocelluloses ratio had a favorable effect on the interaction of the wood with moisture. According to the obtained results, hornbeam wood is affected more than uludag fir wood. For each wood, the maximum decreases of holocellulose and α-cellulose were found at 210oC for 12 hours, and the maximum increase of lignin occurred at the same treatment combination.

  16. Computed Tomography Structural Lung Changes in Discordant Airflow Limitation

    NARCIS (Netherlands)

    F.A.A. Mohamed Hoesein (Firdaus); P.A. de Jong (Pim); J.W.J. Lammers; W.P. Mali (Willem); M. Schmidt (Michael); H.J. de Koning (Harry); C.M. van der Aalst (Carlijn); M. Oudkerk (Matthijs); R. Vliegenthart (Rozemarijn); B.T.J. van Ginneken (Berbke); E.M. van Rikxoort (Eva); P. Zanen (Pieter)

    2013-01-01

    textabstractBackground:There is increasing evidence that structural lung changes may be present before the occurrence of airflow limitation as assessed by spirometry. This study investigated the prevalence of computed tomography (CT) quantified emphysema, airway wall thickening and gas trapping acco

  17. Computed tomography structural lung changes in discordant airflow obstruction

    NARCIS (Netherlands)

    Hoesein, F.A.A.M.; Jong, P.A. de; Lammers, J.W.; Mali, W.P.Th.; Schmidt, M.; Koning, H.J. de; Aalst, C. van der; Oudkerk, M.; Vliegenthart, R.; Ginneken, B. van; Rikxoort, E.M. van; Zanen, P.

    2013-01-01

    Background: There is increasing evidence that structural lung changes may be present before the occurrence of airflow limitation as assessed by spirometry. This study investigated the prevalence of computed tomography (CT) quantified emphysema, airway wall thickening and gas trapping according to cl

  18. Computed Tomography Structural Lung Changes in Discordant Airflow Limitation

    OpenAIRE

    Firdaus A A Mohamed Hoesein; de Jong, Pim A; Lammers, Jan-Willem J; Willem Pthm Mali; Michael Schmidt; de Koning, Harry J.; Carlijn van der Aalst; Matthijs Oudkerk; Rozemarijn Vliegenthart; Bram van Ginneken; van Rikxoort, Eva M; Pieter Zanen

    2013-01-01

    BACKGROUND: There is increasing evidence that structural lung changes may be present before the occurrence of airflow limitation as assessed by spirometry. This study investigated the prevalence of computed tomography (CT) quantified emphysema, airway wall thickening and gas trapping according to classification of airflow limitation (FEV1/FVC 70%; group 2LLN; and group 370% but FEV1

  19. A structural framework for anomalous change detection and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Lakshman [Los Alamos National Laboratory; Theiler, James P [Los Alamos National Laboratory

    2009-01-01

    We present a spatially adaptive scheme for automatically searching a pair of images of a scene for unusual and interesting changes. Our motivation is to bring into play structural aspects of image features alongside the spectral attributes used for anomalous change detection (ACD). We leverage a small but informative subset of pixels, namely edge pixels of the images, as anchor points of a Delaunay triangulation to jointly decompose the images into a set of triangular regions, called trixels, which are spectrally uniform. Such decomposition helps in image regularization by simple-function approximation on a feature-adaptive grid. Applying ACD to this trixel grid instead of pixels offers several advantages. It allows: (1) edge-preserving smoothing of images, (2) speed-up of spatial computations by significantly reducing the representation of the images, and (3) the easy recovery of structure of the detected anomalous changes by associating anomalous trixels with polygonal image features. The latter facility further enables the application of shape-theoretic criteria and algorithms to characterize the changes and recognize them as interesting or not. This incorporation of spatial information has the potential to filter out some spurious changes, such as due to parallax, shadows, and misregistration, by identifying and filtering out those that are structurally similar and spatially pervasive. Our framework supports the joint spatial and spectral analysis of images, potentially enabling the design of more robust ACD algorithms.

  20. Social dilemma structures hidden behind traffic flow with lane changes

    International Nuclear Information System (INIS)

    Aiming to merge traffic flow analysis with evolutionary game theory, we investigated the question of whether such structures can be formed from frequent lane changes in usual traffic flow without any explicit bottlenecks. In our model system, two classes of driver-agents coexist: C-agents (cooperative strategy) always remain in the lane they are initially assigned, whereas D-agents (defective strategy) try to change lanes to move ahead. In relatively high-density flows, such as the metastable and high-density phases, we found structures that correspond to either n-person prisoner dilemma (n-PD) games or quasi-PD games. In these situations, lane changes by D-agents create heavy traffic jams that reduce social efficiency. (paper)

  1. Dramatic changes in electronic structure revealed by fractionally charged nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Aron J. [Department of Chemistry, Lensfield Rd., University of Cambridge, Cambridge CB2 1EW (United Kingdom); Mori-Sánchez, Paula, E-mail: paula.mori@uam.es [Departamento de Química, Universidad Autónoma de Madrid, 28049 Madrid (Spain)

    2014-01-28

    Discontinuous changes in the electronic structure upon infinitesimal changes to the Hamiltonian are demonstrated. These are revealed in one and two electron molecular systems by full configuration interaction (FCI) calculations when the realm of the nuclear charge is extended to be fractional. FCI electron densities in these systems show dramatic changes in real space and illustrate the transfer, hopping, and removal of electrons. This is due to the particle nature of electrons seen in stretched systems and is a manifestation of an energy derivative discontinuity at constant number of electrons. Dramatic errors of density functional theory densities are seen in real space as this physics is missing from currently used approximations. The movements of electrons in these simple systems encapsulate those in real physical processes, from chemical reactions to electron transport and pose a great challenge for the development of new electronic structure methods.

  2. STRUCTURAL CHANGES IN THE RAT TESTES CAUSED BY DIAZINON ADMINISTRATION

    Directory of Open Access Journals (Sweden)

    R. TOMAN

    2013-07-01

    Full Text Available The aim of this study was to find the structural changes in the rat testis after a diazinon administration. The testis structure changes after the diazinon administration of 20 mg/kg b.w. (i.p. and daily dose of 40 mg/l in drinking water (p.o. were evaluated in light microscopy. 36 hours after the diazion i.p. administration, the vacuolization of the seminiferous epithelium, evacuation of germ cells into the tubule lumen, epithelium necrosis and interstitium extension were observed. After 90 days of daily oral administration, the changes in the testis were not as visible as in the acute intoxication. The germ cells released from the basal lamina and then were visible in the tubule lumen. Diazinon causes the damage of the germinal epithelium in the testes leading to the spermatogenesis failure. The infertility can then appear.

  3. Polarized scattering with Paschen-Back effect, hyperfine structure, and partial frequency redistribution in magnetized stellar atmospheres

    CERN Document Server

    Sowmya, K; Stenflo, J O; Sampoorna, M

    2015-01-01

    $F$-state interference significantly modifies the polarization produced by scattering processes in the solar atmosphere. Its signature in the emergent Stokes spectrum in the absence of magnetic fields is depolarization in the line core. In the present paper, we derive the partial frequency redistribution (PRD) matrix that includes interference between the upper hyperfine structure states of a two-level atom in the presence of magnetic fields of arbitrary strengths. The theory is applied to the Na I D$_2$ line that is produced by the transition between the lower $J=1/2$ and upper $J=3/2$ states which split into $F$ states because of the coupling with the nuclear spin $I_s=3/2$. The properties of the PRD matrix for the single-scattering case is explored, in particular, the effects of the magnetic field in the Paschen--Back regime and their usefulness as a tool for the diagnostics of solar magnetic fields.

  4. Inflatable shape changing colonies assembling versatile smart space structures

    Science.gov (United States)

    Sinn, Thomas; Hilbich, Daniel; Vasile, Massimiliano

    2014-11-01

    Various plants have the ability to follow the sun with their flowers or leaves during the course of a day via a mechanism known as heliotropism. This mechanism is characterised by the introduction of pressure gradients between neighbouring motor cells in the plant's stem, enabling the stem to bend. By adapting this bio-inspired mechanism to mechanical systems, a new class of smart structures can be created. The developed overall structure is made up of a number of cellular colonies, each consisting of a central pressure source surrounded by multiple cells. After launch, the cellular arrays are deployed in space and are either preassembled or alternatively are attached together during their release or afterwards. A central pressure source is provided by a high-pressure storage unit with an integrated valve, which provides ingress gas flow to the system; the gas is then routed through the system via a sequence of valve operations and cellular actuations, allowing for any desired shape to be achieved within the constraints of the deployed array geometry. This smart structure consists of a three dimensional adaptable cellular array with fluid controlling Micro Electromechanical Systems (MEMS) components enabling the structure to change its global shape. The proposed MEMS components include microvalves, pressure sensors, mechanical interconnect structures, and electrical routing. This paper will also give an overview of the system architecture and shows the feasibility and shape changing capabilities of the proposed design with multibody dynamic simulations. Example applications of this lightweight shape changing structure include concentrators, mirrors, and communications antennas that are able to dynamically change their focal point, as well as substructures for solar sails that are capable of steering through solar winds by altering the sails' subjected area.

  5. Internal Structure of the North Polar Layered Deposits on Mars From SHARAD Observations

    Science.gov (United States)

    Putzig, N. E.; Holt, J. W.; Phillips, R. J.; Seu, R.; Biccari, D.; Campbell, B. A.; Carter, L. M.; Safaeinili, A.; Egan, A. F.

    2007-12-01

    The Shallow Radar (SHARAD) instrument onboard the Mars Reconnaissance Orbiter is revealing detailed layering patterns within the North Polar Layered Deposits (NPLD) in Planum Boreum. Since the beginning of its primary science mission in November of 2006, SHARAD has acquired over 400 subsurface sounding observations (radargrams) that cross the NPLD. Each radargram consists of a two-dimensional profile beneath the instrument's ground track and shows a series of returns corresponding to dielectric contrasts in the subsurface to depths of 2 to 3 km. We have imported a subset of these data together with associated location information into an interactive subsurface data interpretation software package, thereby allowing us to delineate and map horizons and faults within the NPLD in three dimensions. Our initial results show: 1) several discrete units of sub-parallel reflections separated by regional unconformities and situated above a diffusely reflective zone (DRZ) that extends throughout the main lobe of the NPLD and appears to correspond to a previously identified Basal Unit (Byrne and Murray 2002, JGR 107 E6, 5044); 2) apparent large-scale faulting or imbrication of the DRZ in portions of the main lobe to the east of Chasma Boreale; 3) the absence of the distinct basal reflections beneath the main lobe and Olympia Planum that have been identified in MARSIS results (Picardi et al. 2005, Science 310, #5756, pp. 1925-1928; Phillips et al. 2007, LPSC XXXVIII, Abstract 1925); and 4) shallow subsurface layering in portions of Olympia Planum that are proximal to the main lobe. These findings have significant implications for the history of accumulation and erosion of the NPLD, which may provide a record of the global climate history for much of the Amazonian epoch. Efforts to correlate the internal units unveiled by SHARAD with those mapped on the basis of images and other surface data are in progress. Acknowledgments: Thanks to the Italian Space Agency (ASI) and NASA/JPL.

  6. Anisotropic structural and optical properties of semi-polar (11-22) GaN grown on m-plane sapphire using double AlN buffer layers.

    Science.gov (United States)

    Zhao, Guijuan; Wang, Lianshan; Yang, Shaoyan; Li, Huijie; Wei, Hongyuan; Han, Dongyue; Wang, Zhanguo

    2016-01-01

    We report the anisotropic structural and optical properties of semi-polar (11-22) GaN grown on m-plane sapphire using a three-step growth method which consisted of a low temperature AlN buffer layer, followed by a high temperature AlN buffer layer and GaN growth. By introducing double AlN buffer layers, we substantially improve the crystal and optical qualities of semi-polar (11-22) GaN, and significantly reduce the density of stacking faults and dislocations. The high resolution x-ray diffraction measurement revealed that the in-plane anisotropic structural characteristics of GaN layer are azimuthal dependent. Transmission electron microscopy analysis showed that the majority of dislocations in the GaN epitaxial layer grown on m-sapphire are the mixed-type and the orientation of GaN layer was rotated 58.4° against the substrate. The room temperature photoluminescence (PL) spectra showed the PL intensity and wavelength have polarization dependence along parallel and perpendicular to the [1-100] axis (polarization degrees ~ 0.63). The realization of a high polarization semi-polar GaN would be useful to achieve III-nitride based lighting emission device for displays and backlighting.

  7. Technological Progress, Structural Change and China's Energy Efficiency

    Institute of Scientific and Technical Information of China (English)

    Wang Junsong; He Canfei

    2009-01-01

    China has witnessed rapid economic development since 1978, and during the time, energy production and consumptiondeveloped at a tremendous speed as well.Energy efficiency which can he measured by energy consumption per unit of GDP, how-ever, experienced continuous decrease.Theoretically, the change of energy efficiency can be attributed to industry structural change and technological change.In order to explain the transformation of Chinese energy efficiency, we adopt logarithmic mean Divisia index techniques to decompose changes in energy intensity in the period of 1994-2005.We find that technological change is the dominant contributor in the decline of energy intensity, but the contribution has declined since 2001.The change in industry structure has decreased the energy intensity before 1998, but raised the intensity after 1998.Decomposed technological effects for all sectors indicate that technological progresses in high energy consuming industries such as raw chemical materials and chemi-cal products, smelting and pressing of ferrous metals, manufacture of non-metallic mineral products and household contribute are the principal drivers of China's declining energy intensity.

  8. Integrating Access to Arctic Environmental Change and Human Health Research for the International Polar Year and Beyond

    Science.gov (United States)

    Garrett, C. L.

    2006-12-01

    Each day, people in the communities of the Arctic face challenges to their health and well-being from changing climatic and environmental conditions and increasing levels of pollution to emerging infectious diseases. For this reason, it is critical that Arctic researchers and residents have access to timely, accurate, and relevant information addressing their unique concerns. To meet this need, the National Library of Medicine (NLM) and the University of Alaska Anchorage (UAA) have developed the Arctic Health website, www.arctichealth.org. The website provides an easy-to-use one-stop shop for information on the diverse health-related aspects of the Arctic region. It is organized around relevant topics, including climate change and environmental health, traditional healing and telehealth/telemedicine. The Arctic Health website provides links to the most reliable resources available from local, state, and international agencies, universities, and professional organizations. Two major goals of the site are to create a comprehensive, accessible repository for various media and a listing of research projects, past and present that relate to climate change and human health in the Arctic. To increase the site's relevance, the project has established and continues to create collaborations with researchers, communities, and other organizations to supply publications not available elsewhere, including gray literature, streaming video of traditional healers, and oral histories. These collaborations will also help ensure a database with a comprehensive list of research projects being done in the Arctic, from the international to the local level. Finding ways to negotiate the legal, cultural and national concerns of data sharing are a continuing job for the management team. All of this helps to create a system that will eventually track and ensure that data and reports from the research database translate to the publications database. As part of these efforts, the site is

  9. THE STRUCTURE AND LINEAR POLARIZATION OF THE KILOPARSEC-SCALE JET OF THE QUASAR 3C 345

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, David H.; Wardle, John F. C.; Marchenko, Valerie V., E-mail: roberts@brandeis.edu [Department of Physics MS-057, Brandeis University, Waltham, MA 02454-0911 (United States)

    2013-02-01

    Deep Very Large Array imaging of the quasar 3C 345 at 4.86 and 8.44 GHz has been used to study the structure and linear polarization of its radio jet on scales ranging from 2 to 30 kpc. There is a 7-8 Jy unresolved core with spectral index {alpha} {approx_equal} -0.24 (I{sub {nu}}{proportional_to}{nu}{sup {alpha}}). The jet (typical intensity 15 mJy beam{sup -1}) consists of a 2.''5 straight section containing two knots, and two additional non-co-linear knots at the end. The jet's total projected length is about 27 kpc. The spectral index of the jet varies over -1.1 {approx}< {alpha} {approx}< -0.5. The jet diverges with a semi-opening angle of about 9 Degree-Sign , and is nearly constant in integrated brightness over its length. A faint feature northeast of the core does not appear to be a true counter-jet, but rather an extended lobe of this FR-II radio source seen in projection. The absence of a counter-jet is sufficient to place modest constraints on the speed of the jet on these scales, requiring {beta} {approx}> 0.5. Despite the indication of jet precession in the total intensity structure, the polarization images suggest instead a jet re-directed at least twice by collisions with the external medium. Surprisingly, the electric vector position angles in the main body of the jet are neither longitudinal nor transverse, but make an angle of about 55 Degree-Sign with the jet axis in the middle while along the edges the vectors are transverse, suggesting a helical magnetic field. There is no significant Faraday rotation in the source, so that is not the cause of the twist. The fractional polarization in the jet averages 25% and is higher at the edges. In a companion paper, Roberts and Wardle show that differential Doppler boosting in a diverging relativistic velocity field can explain the electric vector pattern in the jet.

  10. Effect of Population Structure Change on Carbon Emission in China

    Directory of Open Access Journals (Sweden)

    Wen Guo

    2016-03-01

    Full Text Available This paper expanded the Logarithmic Mean Divisia Index (LMDI model through the introduction of urbanization, residents’ consumption, and other factors, and decomposed carbon emission changes in China into carbon emission factor effect, energy intensity effect, consumption inhibitory factor effect, urbanization effect, residents’ consumption effect, and population scale effect, and then explored contribution rates and action mechanisms of the above six factors on change in carbon emissions in China. Then, the effect of population structure change on carbon emission was analyzed by taking 2003–2012 as a sample period, and combining this with the panel data of 30 provinces in China. Results showed that in 2003–2012, total carbon emission increased by 4.2117 billion tons in China. The consumption inhibitory factor effect, urbanization effect, residents’ consumption effect, and population scale effect promoted the increase in carbon emissions, and their contribution ratios were 27.44%, 12.700%, 74.96%, and 5.90%, respectively. However, the influence of carbon emission factor effect (−2.54% and energy intensity effect (−18.46% on carbon emissions were negative. Population urbanization has become the main population factor which affects carbon emission in China. The “Eastern aggregation” phenomenon caused the population scale effect in the eastern area to be significantly higher than in the central and western regions, but the contribution rate of its energy intensity effect (−11.10 million tons was significantly smaller than in the central (−21.61 million tons and western regions (−13.29 million tons, and the carbon emission factor effect in the central area (−3.33 million tons was significantly higher than that in the eastern (−2.00 million tons and western regions (−1.08 million tons. During the sample period, the change in population age structure, population education structure, and population occupation structure

  11. Optical and micro-structural characterizations of MBE grown indium gallium nitride polar quantum dots

    KAUST Repository

    Elafandy, Rami T.

    2011-12-01

    Comparison between indium rich (27%) InGaN/GaN quantum dots (QDs) and their underlying wetting layer (WL) is performed by means of optical and structural characterizations. With increasing temperature, micro-photoluminescence (μPL) study reveals the superior ability of QDs to prevent carrier thermalization to nearby traps compared to the two dimensional WL. Thus, explaining the higher internal quantum efficiency of the QD nanostructure compared to the higher dimensional WL. Structural characterization (X-ray diffraction (XRD)) and transmission electron microscopy (TEM)) reveal an increase in the QD indium content over the WL indium content which is due to strain induced drifts. © 2011 IEEE.

  12. Structural Changes are More Important than Compositional Changes in Driving Biomass Loss in Ugandan Forest Fragments

    Directory of Open Access Journals (Sweden)

    C. Bulafu

    2014-01-01

    Full Text Available Aboveground biomass (AGB contained in privately-owned forests is less frequently measured than in forest reserves despite their greater likelihood of degradation. We demonstrate how density changes in contrast to species compositional changes have driven AGB changes in privately-owned fragments in Uganda over two decades. Data on tree assemblages in fragments were obtained by re-sampling a 1990 dataset in 2010 and AGB estimated using generalised allometric equation that incorporates diameter at breast height (DBH and species-specific wood density. AGB were highly variable between fragments and over time. Structural changes contributed a higher proportion of change in AGB than species compositional changes in all forests. Non-pioneer species constituted over 50% of AGB in reserve forest, in contrast to private forests where pioneer species dominated. Our study demonstrates the potential of private forests to hold comparable AGB to plantation. Reduction in exploitation pressure is required if fragments are to mitigate carbon emissions.

  13. Depletion of phosphatidylglycerol head-group induces changes in oxygen evolution and protein secondary structures of photosystemⅡ

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The techniques of oxygen electrode polarography and Fourier transform infrared (FT-IR) spectroscopy were employed to explore the roles of polar head-group of phosphatidylglycerol (PG) molecules in the functional and structural aspects of photosystemⅡ(PSⅡ) through enzymatic approach. It was shown that the depletion of PG by treatment of phospholipase C (PLC) on PSⅡ particles caused the inhibition of oxygen evolving activity in PSⅡ. This effect also gave rise to changes in the protein secondary structures of PSⅡ, that is, an increase in α-helical conformation which is compensated by the loss of β-strand structures. It revealed that the head-group of PG molecules plays an important structural role in the maintenance of normal structure of PSⅡ proteins, which is required to maintain the appropriate physiological activity of the PSⅡ complex such as the oxygen evolving activity. It is suggested that there most probably exist hydrogen-bonding interactions between PG molecules and PSⅡ proteins.

  14. Constructional change, paradigmatic structure and the orientation of usage processes

    DEFF Research Database (Denmark)

    Heltoft, Lars

    2014-01-01

    This article presents a model analysis of the interplay between structure and usage in the semantic change of constructions, with a focus on the role of content structure in the sense of paradigmatically organised semantic structure. The case at hand the development of the Danish indirect object...... construction from the 18th century to the present, a specialisation process parallel to the one described for English by Colleman & De Clerck (2011), though not identical to it. The semantics of constructions is described in terms of linguistic content, as distinct from conceptual structure, and the linguistic...... content of constructions is organised to a great extent in paradigmatic oppositions, similar to those found in classical morphology (Nørgård-Sørensen, Heltoft & Schøsler 2011). This organisation principle implies that the semantic description must uncover the boundaries of the construction’s content...

  15. Ownership Structure and Earnings Management in periods of Executive Changes

    DEFF Research Database (Denmark)

    Sommer, Rasmus S.

    This paper reports evidence of earnings management associated with non-routine executive changes in a Danish context. It is hypothesised that incoming executives in non-owner-controlled companies decrease earnings by means of discretionary accruals in the financial statements relating to the period...... this is not the case for owner-controlled companies. Also, a test shows a significant difference in earnings management in owner- versus non-owner-controlled companies around executive changes. The study elaborates on the research in the area by including ownership structure. Furthermore, the study is carried out...... of the executive change. A modified, modified Jones model is used to divide income before tax into discretionary and non-discretionary components. The empirical evidence is consistent with the hypothesis. Non-owner-controlled companies significantly decrease earnings around executive changes, while...

  16. Microbial community structure in lake and wetland sediments from a high Arctic polar desert revealed by targeted transcriptomics.

    Directory of Open Access Journals (Sweden)

    Magdalena K Stoeva

    Full Text Available While microbial communities play a key role in the geochemical cycling of nutrients and contaminants in anaerobic freshwater sediments, their structure and activity in polar desert ecosystems are still poorly understood, both across heterogeneous freshwater environments such as lakes and wetlands, and across sediment depths. To address this question, we performed targeted environmental transcriptomics analyses and characterized microbial diversity across three depths from sediment cores collected in a lake and a wetland, located on Cornwallis Island, NU, Canada. Microbial communities were characterized based on 16S rRNA and two functional gene transcripts: mcrA, involved in archaeal methane cycling and glnA, a bacterial housekeeping gene implicated in nitrogen metabolism. We show that methane cycling and overall bacterial metabolic activity are the highest at the surface of lake sediments but deeper within wetland sediments. Bacterial communities are highly diverse and structured as a function of both environment and depth, being more diverse in the wetland and near the surface. Archaea are mostly methanogens, structured by environment and more diverse in the wetland. McrA transcript analyses show that active methane cycling in the lake and wetland corresponds to distinct communities with a higher potential for methane cycling in the wetland. Methanosarcina spp., Methanosaeta spp. and a group of uncultured Archaea are the dominant methanogens in the wetland while Methanoregula spp. predominate in the lake.

  17. Frequency effects and structural change - the Afrikaans preterite

    Directory of Open Access Journals (Sweden)

    Johanita Kirsten

    2016-07-01

    Full Text Available According to emergent grammar and exemplar theory in cognitive linguistics, the frequency of an item affects its behaviour in terms of structural change. In this article, I illustrate how high frequency items, such as preterital modal auxiliaries and copulas in Afrikaans, resist regularising with the rest of the Afrikaans verbal system. Items with a moderately high frequency can resist change for a time, but succumb to it eventually, such as mog (“might” and wis (“knew”. While the course of change can also be affected by other factors, such as het (“have” and had (“had”, and dink (“think” and gedink/dag/dog (“thought” show, the data in diachronic Afrikaans corpora from 1911 to 2010 confirm that high frequency items resist structural change to a large extent, while low frequency items do not. This links with the cognitive representation of language and language processing, and illustrates how the use of language shapes the structure of language.

  18. Micromachining with femtosecond laser written radial polarization converter

    OpenAIRE

    Beresna, M.; Gecevičius, M.; Kazansky, P. G.; Bellouard, Y.; Champion, A.

    2012-01-01

    Structures for microfluidics are fabricated with radially polarized femtosecond laser beam. Radial polarization is produced using birefringent optical element. Omnidirectional etching can be achieved using cylindrically symmetric polarization.

  19. Correlation between stoichiometry and surface structure of the polar MgAl2O4(100) surface as a function of annealing temperature

    DEFF Research Database (Denmark)

    Jensen, Thomas Nørregaard; Rasmussen, Morten Karstoft; Knudsen, Jan;

    2015-01-01

    The correlation between surface structure, stoichiometry and atomic occupancy of the polar MgAl2O4(100) surface has been studied with an interplay of noncontact atomic force microscopy, x-ray photoelectron spectroscopy and surface x-ray diffraction under ultrahigh vacuum conditions. The Al/Mg ratio...... edges contribute to stabilizing the structure by compensating surface polarity. Surface x-ray diffraction reveals a reduced occupancy in the top two surface layers for both Mg, Al, and O and, moreover, vacancies are preferably located in octahedral sites, indicating that Al and Mg ions interchange sites...

  20. The shallow benthic food web structure in the high Arctic does not follow seasonal changes in the surrounding environment

    Science.gov (United States)

    Kędra, Monika; Kuliński, Karol; Walkusz, Wojciech; Legeżyńska, Joanna

    2012-12-01

    Seasonality, quality and quantity of food resources strongly affect fitness and survival of polar fauna. Most research conducted in polar areas has been carried out during the summer, rarely including aspects of seasonality; therefore, there are gaps in our knowledge of the structure of food webs in the Arctic, particularly information is lacking on the possible shifts in winter feeding strategies of organisms. This study is the first to compare potential shifts in benthic food-web structure between winter and summer in a shallow-water Arctic fjord (Kongsfjorden, Svalbard). Winter data were collected in March when conditions are representative of winter and when Arctic shallow benthic fauna is likely to be most affected by absence of fresh food supply as opposed to summer (August). Samples of particulate suspended organic matter (POM), settled organic matter, surface sediment and benthic organisms were taken and analyzed for stable isotopes signatures (δ13C and δ15N). Four relative trophic levels (TL) were distinguished in both winter and summer, and no differences in the structure of benthic food web were found between seasons. Our study shows that the shallow sublittoral benthos depends on primary production, fresh and reworked settled organic matter and, to a certain degree, on terrestrial input. We also demonstrate that shallow water polar benthic fauna is characterized by a high level of omnivory and feeds at multiple trophic levels showing strong resilience to changing seasonal conditions.

  1. Impact of controlled changes in grain size and pore space characteristics on the hydraulic conductivity and spectral induced polarization response of "proxies" of saturated alluvial sediments

    Directory of Open Access Journals (Sweden)

    K. Koch

    2010-08-01

    Full Text Available Understanding the influence of pore space characteristics on the hydraulic conductivity and spectral induced polarization (SIP response is critical for establishing relationships between the electrical and hydrological properties of surficial unconsolidated sedimentary deposits, which host the bulk of the world's readily accessible groundwater resources. Here, we present the results of laboratory SIP measurements on industrial-grade, saturated quartz samples with granulometric characteristics ranging from fine sand to fine gravel, which can be regarded as proxies for widespread alluvial deposits. We altered the pore space characteristics by changing (i the grain size spectra, (ii the degree of compaction, and (iii the level of sorting. We then examined how these changes affect the SIP response, the hydraulic conductivity, and the specific surface area of the considered samples. In general, the results indicate a clear connection between the SIP response and the granulometric as well as pore space characteristics. In particular, we observe a systematic correlation between the hydraulic conductivity and the relaxation time of the Cole-Cole model describing the observed SIP effect for the entire range of considered grain sizes. The results do, however, also indicate that the detailed nature of these relations depends strongly on variations in the pore space characteristics, such as, for example, the degree of compaction. The results of this study underline the complexity of the origin of the SIP signal as well as the difficulty to relate it to a single structural factor of a studied sample, and hence raise some fundamental questions with regard to the practical use of SIP measurements as site- and/or sample-independent predictors of the hydraulic conductivity.

  2. Effect of spin polarization on the structural properties and bond hardness of Fe$_x$B ($x = 1, 2, 3$) compounds first-principles study

    Indian Academy of Sciences (India)

    AHMED GUEDDOUH; BACHIR BENTRIA; IBN KHALDOUN LEFKAIER; YAHIA BOUROUROU

    2016-10-01

    In this paper, spin and non-spin polarization (SP, NSP) are performed to study structural properties and bond hardness of Fe$_x$B ($x = 1, 2, 3$) compounds using density functional theory (DFT) within generalized gradientapproximation (GGA) to evaluate the effect of spin polarization on these properties. The non-spin-polarization results show that the non-magnetic state (NM) is less stable thermodynamically for Fe$_x$B compounds than spinpolarization by the calculated cohesive energy and formation enthalpy. Spin-polarization calculations show that ferromagnetic state (FM) is stable for FexB structures and carry magnetic moment of 1.12, 1.83 and 2.03 $\\mu$B inFeB, Fe$_2$B and Fe$_3$B, respectively. The calculated lattice parameters, bulk modulus and magnetic moments agree well with experimental and other theoretical results. Significant differences in volume and in bulk modulus werefound between the ferromagnetic and non-magnetic cases, i.e., 6.8, 32.8, respectively.We predict the critical pressure between ferromagnetic and non-magnetic phases. The model for hardness calculation using Mulliken population coupled to semi-empirical hardness theory proved effective in hardness prediction for the metal borides which agree well with the experimental values. These results would help to gain insight into the spin-polarized effect on the structural and bond hardness.

  3. Structural Transformation, Biased Technological Change, and Employment in Vietnam

    DEFF Research Database (Denmark)

    Abbott, Philip; Tarp, Finn; Wu, Ce

    2015-01-01

    Employment in Vietnam and elsewhere in Asia has grown more slowly than GDP over the last several decades. This means GDP per capita is rising. Vietnamese policymakers, however, are concerned that ongoing structural transformation is creating too few jobs. We use data for seven aggregated sectors...... and the overall Vietnamese economy to examine the roles played by structural transformation, technical change and institutional bias towards capital-intensive development to evaluate the Vietnamese development experience. We find that while some of the difference between GDP and employment growth can...

  4. Structural transformation, biased technological change, and employment in Vietnam

    DEFF Research Database (Denmark)

    Abbott, Philip; Tarp, Finn; Wu, Ce

    Employment in Vietnam and elsewhere in Asia has grown more slowly than GDP over the last several decades. This means GDP per capita is rising. Vietnamese policymakers, however, are concerned that ongoing structural transformation is creating too few jobs. We use data for seven aggregated sectors...... and the overall Vietnamese economy to examine the roles played by structural transformation, technical change, and institutional bias toward capital intensive development to evaluate the Vietnamese development experience. We find that while some of the difference between GDP and employment growth can...

  5. Giant Controllable Magnetization Changes Induced by Structural Phase Transitions in a Metamagnetic Artificial Multiferroic.

    Science.gov (United States)

    Bennett, S P; Wong, A T; Glavic, A; Herklotz, A; Urban, C; Valmianski, I; Biegalski, M D; Christen, H M; Ward, T Z; Lauter, V

    2016-01-01

    The realization of a controllable metamagnetic transition from AFM to FM ordering would open the door to a plethora of new spintronics based devices that, rather than reorienting spins in a ferromagnet, harness direct control of a materials intrinsic magnetic ordering. In this study FeRh films with drastically reduced transition temperatures and a large magneto-thermal hysteresis were produced for magnetocaloric and spintronics applications. Remarkably, giant controllable magnetization changes (measured to be as high has ~25%) are realized by manipulating the strain transfer from the external lattice when subjected to two structural phase transitions of BaTiO3 (001) single crystal substrate. These magnetization changes are the largest seen to date to be controllably induced in the FeRh system. Using polarized neutron reflectometry we reveal how just a slight in plane surface strain change at ~290C results in a massive magnetic transformation in the bottom half of the film clearly demonstrating a strong lattice-spin coupling in FeRh. By means of these substrate induced strain changes we show a way to reproducibly explore the effects of temperature and strain on the relative stabilities of the FM and AFM phases in multi-domain metamagnetic systems. This study also demonstrates for the first time the depth dependent nature of a controllable magnetic order using strain in an artificial multiferroic heterostructure. PMID:26940159

  6. Giant Controllable Magnetization Changes Induced by Structural Phase Transitions in a Metamagnetic Artificial Multiferroic

    Science.gov (United States)

    Bennett, S. P.; Wong, A. T.; Glavic, A.; Herklotz, A.; Urban, C.; Valmianski, I.; Biegalski, M. D.; Christen, H. M.; Ward, T. Z.; Lauter, V.

    2016-03-01

    The realization of a controllable metamagnetic transition from AFM to FM ordering would open the door to a plethora of new spintronics based devices that, rather than reorienting spins in a ferromagnet, harness direct control of a materials intrinsic magnetic ordering. In this study FeRh films with drastically reduced transition temperatures and a large magneto-thermal hysteresis were produced for magnetocaloric and spintronics applications. Remarkably, giant controllable magnetization changes (measured to be as high has ~25%) are realized by manipulating the strain transfer from the external lattice when subjected to two structural phase transitions of BaTiO3 (001) single crystal substrate. These magnetization changes are the largest seen to date to be controllably induced in the FeRh system. Using polarized neutron reflectometry we reveal how just a slight in plane surface strain change at ~290C results in a massive magnetic transformation in the bottom half of the film clearly demonstrating a strong lattice-spin coupling in FeRh. By means of these substrate induced strain changes we show a way to reproducibly explore the effects of temperature and strain on the relative stabilities of the FM and AFM phases in multi-domain metamagnetic systems. This study also demonstrates for the first time the depth dependent nature of a controllable magnetic order using strain in an artificial multiferroic heterostructure.

  7. A New Optical Polarization Catalog for the Small Magellanic Cloud: The Magnetic Field Structure

    CERN Document Server

    Gomes, Aiara Lobo; Pereyra, Antonio; Rodrigues, Cláudia Vilega

    2015-01-01

    We present a new optical polarimetric catalog for the Small Magellanic Cloud (SMC). It contains a total of 7207 stars, located in the Northeast (NE) and Wing sections of the SMC and part of the Magellanic Bridge. This new catalog is a significant improvement compared to previous polarimetric catalogs for the SMC. We used it to study the sky-projected interstellar magnetic field structure of the SMC. Three trends were observed for the ordered magnetic field direction at position angles of $(65 \\pm 10)$ deg, $(115 \\pm 10)$ deg, and $(150 \\pm 10)$ deg. Our results suggest the existence of an ordered magnetic field aligned with the Magellanic Bridge direction and SMC's Bar in the NE region, which have position angles roughly at $115.4$ deg and $45$ deg, respectively. However, the overall magnetic field structure is fairly complex. The trends at $115$ deg and $150$ deg may be correlated with the SMC's bimodal structure, observed in Cepheids' distances and HI velocities. We derived a value of $B_{sky} = (0.947 \\pm ...

  8. Polarization Induced Changes in LSM Thin Film Electrode Composition Observed by In Operando Raman Spectroscopy and TOF-SIMS

    DEFF Research Database (Denmark)

    McIntyre, Melissa D.; Walker, Robert; Traulsen, Marie Lund;

    2015-01-01

    an applied potential.1-3 The presented work explores the polarisation induced changes in LSM electrode composition by utilizing in operando Raman spectroscopy and post mortem ToF-SIMS depth profiling on LSM thin film model electrodes fabricated by pulsed laser deposition on YSZ substrates with a thin (200 nm...... that were both reversible and dependent on the direction of the applied potential (Figure 1). The spectral changes were assigned to changes in the LSM electronic structure and specifically to changes in the relative oxide concentration in LSM’s near surface region. Ex situ ToF-SIMS depth profiles were...... and (b) +1 V. The peaks at 440 and 600 cm-1 are signatures from the CGO and YSZ electrolyte, respectively. Figure 2. ToF-SIMS depth profile of LSM electrode polarised at -1V at 700 °C for 2 h. Stapled lines mark layers enriched in different species. References 1 M. Backhaus-Ricoult, K. Adib, T. St...

  9. Optimized Structures for Low-Profile Phase Change Thermal Spreaders

    Science.gov (United States)

    Sharratt, Stephen Andrew

    Thin, low-profile phase change thermal spreaders can provide cooling solutions for some of today's most pressing heat flux dissipation issues. These thermal issues are only expected to increase as future electronic circuitry requirements lead to denser and potentially 3D chip packaging. Phase change based heat spreaders, such as heat pipes or vapor chambers, can provide a practical solution for effectively dissipating large heat fluxes. This thesis reports a comprehensive study of state-of-the-art capillary pumped wick structures using computational modeling, micro wick fabrication, and experimental analysis. Modeling efforts focus on predicting the shape of the liquid meniscus inside a complicated 3D wick structure. It is shown that this liquid shape can drastically affect the wick's thermal resistance. In addition, knowledge of the liquid meniscus shape allows for the computation of key parameters such as permeability and capillary pressure which are necessary for predicting the maximum heat flux. After the model is validated by comparison to experimental results, the wick structure is optimized so as to decrease overall wick thermal resistance and increase the maximum capillary limited heat flux before dryout. The optimized structures are then fabricated out of both silicon and copper using both traditional and novel micro-fabrication techniques. The wicks are made super-hydrophilic using chemical and thermal oxidation schemes. A sintered monolayer of Cu particles is fabricated and analyzed as well. The fabricated wick structures are experimentally tested for their heat transfer performance inside a well controlled copper vacuum chamber. Heat fluxes as high as 170 W/cm2 are realized for Cu wicks with structure heights of 100 μm. The structures optimized for both minimized thermal resistance and high liquid supply ability perform much better than their non-optimized counterparts. The super-hydrophilic oxidation scheme is found to drastically increase the maximum

  10. Changes in Mauna Kea Dry Forest Structure 2000-2014

    Science.gov (United States)

    Banko, Paul C.; Brinck, Kevin W.

    2014-01-01

    Changes in the structure of the subalpine vegetation of Palila Critical Habitat on the southwestern slope of Mauna Kea Volcano, Hawai‘i, were analyzed using 12 metrics of change in māmane (Sophora chrysophylla) and naio (Myoporum sandwicense) trees surveyed on plots in 2000 and 2014. These two dominant species were analyzed separately, and changes in their structure indicated changes in the forest’s health. There was a significant increase in māmane minimum crown height (indicating a higher ungulate “browse line”), canopy area, canopy volume, percentage of trees with ungulate damage, and percentage of dead trees. No significant changes were observed in māmane maximum crown height, proportion of plots with trees, sapling density, proportion of plots with saplings, or the height distribution of trees. The only significant positive change was for māmane tree density. Significantly negative changes were observed for naio minimum crown height, tree height, canopy area, canopy volume, and percentage of dead trees. No significant changes were observed in naio tree density, proportion of plots with trees, proportion of plots with saplings, or percentage of trees with ungulate damage. Significantly positive changes were observed in naio sapling density and the height distribution of trees. There was also a significant increase in the proportion of māmane vs. naio trees in the survey area. The survey methods did not allow us to distinguish among potential factors driving these changes for metrics other than the percentage of trees with ungulate damage. Continued ungulate browsing and prolonged drought are likely the factors contributing most to the observed changes in vegetation, but tree disease or insect infestation of māmane, or naio, and competition from alien grasses and other weeds could also be causing or exacerbating the impacts to the forest. Although māmane tree density has increased since 2000, this study also demonstrates that efforts by managers

  11. Financial crisis and market risk premium: Identifying multiple structural changes

    Directory of Open Access Journals (Sweden)

    Juan J. García-Machado

    2011-03-01

    Full Text Available The relationship between macroeconomic variables and stock market returns is, by now, well-documented in the literature. However, in this article we examine the long-run relationship between stock and bond markets returns over the period from 1991:11 to 2009:11, using Bai and Perron’s multiple structural change approach. Findings indicate that while the market risk premium is usually positive, periods with negative values appear only in three periods (1991:1-1993:2, 1998:3-2002:2 and from 2007:1-2009:11 leading to changes in the GDP evolution. Thereby, the study shows the presence of structural breaks in the Spanish market risk premium and its relationship with business cycle. These findings contribute to a better understanding of close linkages between the financial markets and the macroeconomic variables such as GDP. Implications of the study and suggestions for future research are provided.

  12. CERN's new Career Structure Main Changes in a Nutshell

    CERN Multimedia

    2001-01-01

    All Staff Members will have received an official notification of their position in the new career path structure, with effect from 1 September 2001. A Weekly Bulletin announcement two weeks ago (Bulletin 33/2001) referred to documents and contacts for individual or general information, notably via the HR Division Web site (see below). The present article summarises the main changes between the MOAS and the MAPS (Merit Advancement and Promotion Scheme). The aim of MAPS is to make the career structure more dynamic, while retaining positive elements of the MOAS scheme, notably an annual interview and performance assessment process. The main changes are: - Career reviews including salary band promotion at several stages in a person's career replace the previous automatic grade-to-grade progression within a career path. - Speeds of advancement can be modulated to a greater extent. - The exceptional advancement zone is re-designed. - Premiums or allowances linked to performance, responsibility, and specific labou...

  13. Change in fish community structure in the Barents Sea.

    Directory of Open Access Journals (Sweden)

    Michaela Aschan

    Full Text Available Change in oceanographic conditions causes structural alterations in marine fish communities, but this effect may go undetected as most monitoring programs until recently mainly have focused on oceanography and commercial species rather than on whole ecosystems. In this paper, the objective is to describe the spatial and temporal changes in the Barents Sea fish community in the period 1992-2004 while taking into consideration the observed abundance and biodiversity patterns for all 82 observed fish species. We found that the spatial structure of the Barents Sea fish community was determined by abiotic factors such as temperature and depth. The observed species clustered into a deep assemblage, a warm water southern assemblage, both associated with Atlantic water, and a cold water north-eastern assemblage associated with mixed water. The latitude of the cold water NE and warm water S assemblages varied from year to year, but no obvious northward migration was observed over time. In the period 1996-1999 we observed a significant reduction in total fish biomass, abundance, mean fish weight, and a change in community structure including an increase in the pelagic/demersal ratio. This change in community structure is probably due to extremely cold conditions in 1996 impacting on a fish community exposed to historically high fishing rates. After 1999 the fish community variables such as biomass, abundance, mean weight, P/D ratio as well as community composition did not return to levels of the early 90s, although fishing pressure and climatic conditions returned to earlier levels.

  14. Structural Change Tests for Simulated Method of Moments

    OpenAIRE

    Eric Ghysels; Alain Guay

    1998-01-01

    Simulation-based estimation methods have become more widely used in recent years. We propose a set of tests for structural change in models estimates via Simulated Method of Moments (see Duffie and Singleton (1993)). These tests extend the recent work of Andrews (1993) and Sowell (1996a, b) which covered Generalized Method of Moments estimators not involving simulation. We derive the asymptotic distributions of various tests. We show that the number of simulations does not affect the asymptot...

  15. Strain-induced changes to the electronic structure of germanium

    KAUST Repository

    Tahini, H. A.

    2012-04-17

    Density functional theory calculations (DFT) are used to investigate the strain-induced changes to the electronic structure of biaxially strained (parallel to the (001), (110) and (111) planes) and uniaxially strained (along the [001], [110] and [111] directions) germanium (Ge). It is calculated that a moderate uniaxial strain parallel to the [111] direction can efficiently transform Ge to a direct bandgap material with a bandgap energy useful for technological applications. © 2012 IOP Publishing Ltd.

  16. THE CHANGING STRUCTURE OF NEBRASKA AGRICULTURE 1974 - 1982

    OpenAIRE

    Frederick, A.L. (Roy); Johnson, Bruce B.

    1985-01-01

    This report focuses on changes in the Nebraska farm sector from 1974 to 1982. Items of major interest include number, size, and types of farms; resource use and output; tenure patterns; age of farm operators; forms of farm business organization; and capital investment. A Gini Index procedure is used to measure shifts in concentration of certain structural variables. Data sources are Censuses of Agriculture, with emphasis on the 1982, 1978, and 1974 Censuses. The number of Nebraska farms decli...

  17. THE EFFECT OF IRRADIATION ON ENAMEL MICRO-STRUCTURE CHANGES

    OpenAIRE

    Harun Gunawan; Sri Angky Soekanto; Safrida Hoesin

    2015-01-01

    Radiotherapy plays an important role in the management of head and neck carcinoma therapy. The radiation dose ranges from 40 – 70 Gy, depends on the severity and location of the malignancy. Many patients experience an increased dental caries or sensitivity occurrence following radiotherapy. The objective of this study is to analyze the enamel micro-structure changes after irradiation. Nine polished enamel slabs were prepared from impacted 3rd molars. The slabs were flushed in non-ionic distil...

  18. Structural changes accompanying phosphorylation of tarantula muscle myosin filaments

    OpenAIRE

    1987-01-01

    Electron microscopy has been used to study the structural changes that occur in the myosin filaments of tarantula striated muscle when they are phosphorylated. Myosin filaments in muscle homogenates maintained in relaxing conditions (ATP, EGTA) are found to have nonphosphorylated regulatory light chains as shown by urea/glycerol gel electrophoresis and [32P]phosphate autoradiography. Negative staining reveals an ordered, helical arrangement of crossbridges in these filaments, in which the hea...

  19. Change in Family Structure and Rates of Violent Juvenile Delinquency

    OpenAIRE

    Fry, Jeannie A.

    2010-01-01

    This paper addresses the question: Have the changes in family structure in the U.S. become a catalyst for juvenile delinquency? For this research, I use existing statistics for my three independent variables: divorce rates, rate of working mothers with children under age 18, percent female-headed households. My dependent variable, juvenile violent crime rates, is measured using data from the Office of Juvenile Justice and Delinquency Prevention. My control variables consist of the followin...

  20. Polarized X-ray absorption spectra and electronic structure of molybdenite (2H-MoS2)

    Science.gov (United States)

    Li, Dien; Bancroft, G. M.; Kasrai, M.; Fleet, M. E.; Feng, X. H.; Tan, K. H.

    1995-03-01

    Polarized S K- and L-edge, Mo L3- and L2-edge x-ray absorption near-edge structure (XANES) of natural molybdenite (2H-MoS2) have been measured with synchrotron radiation. These results are qualitatively interpreted using the energy band model of molybdenite and provide important information on the unoccupied states of molybdenite. The valence band (VB) maximum of molybdenite is characterized by fully occupied Mo 4dz 2, and the conduction band (CB) minimum of molybdenite is characterized by unoccupied Mo 4d states. The unoccupied Mo 4d band is split into two sub-bands, designated as t{2g/-}/t{2g/+}and e{g/-}/e{g/+}sets. Although the relative energy of these two sets are difficult to be evaluated, probably the former has the lower energy than the latter, both two sets have the combination wave functions of the other unoccupied Mo 4d components, rather than the simple 4dx 2 — y2 and 4dxy states. The unoccupied Mo 4d sub-bands contain significant DOS of both S 3 p- and 3 s-like states, indicating strong hybridization with S 3s and 3 p states. In the lower energy sub-band, the DOS of the S pz- and px,y-like states are very similar. However, in the higher energy sub-band, the DOS of the S 3 px,y-like state is lower than that of the S 3pz state. Polarized S K-edge XANES also reveal the features of antibonding S pz- and px,y-like states in molybdenite. The feature assigned to the S 3 pz-like states is stronger and sharper, and shifts to lower energy by about 2 eV relative to that for the S 3 px,y-like states.

  1. Changes in protein structure at the interface accompanying complex formation

    Directory of Open Access Journals (Sweden)

    Devlina Chakravarty

    2015-11-01

    Full Text Available Protein interactions are essential in all biological processes. The changes brought about in the structure when a free component forms a complex with another molecule need to be characterized for a proper understanding of molecular recognition as well as for the successful implementation of docking algorithms. Here, unbound (U and bound (B forms of protein structures from the Protein–Protein Interaction Affinity Database are compared in order to enumerate the changes that occur at the interface atoms/residues in terms of the solvent-accessible surface area (ASA, secondary structure, temperature factors (B factors and disorder-to-order transitions. It is found that the interface atoms optimize contacts with the atoms in the partner protein, which leads to an increase in their ASA in the bound interface in the majority (69% of the proteins when compared with the unbound interface, and this is independent of the root-mean-square deviation between the U and B forms. Changes in secondary structure during the transition indicate a likely extension of helices and strands at the expense of turns and coils. A reduction in flexibility during complex formation is reflected in the decrease in B factors of the interface residues on going from the U form to the B form. There is, however, no distinction in flexibility between the interface and the surface in the monomeric structure, thereby highlighting the potential problem of using B factors for the prediction of binding sites in the unbound form for docking another protein. 16% of the proteins have missing (disordered residues in the U form which are observed (ordered in the B form, mostly with an irregular conformation; the data set also shows differences in the composition of interface and non-interface residues in the disordered polypeptide segments as well as differences in their surface burial.

  2. Structural change in molten basalt at deep mantle conditions.

    Science.gov (United States)

    Sanloup, Chrystèle; Drewitt, James W E; Konôpková, Zuzana; Dalladay-Simpson, Philip; Morton, Donna M; Rai, Nachiketa; van Westrenen, Wim; Morgenroth, Wolfgang

    2013-11-01

    Silicate liquids play a key part at all stages of deep Earth evolution, ranging from core and crust formation billions of years ago to present-day volcanic activity. Quantitative models of these processes require knowledge of the structural changes and compression mechanisms that take place in liquid silicates at the high pressures and temperatures in the Earth's interior. However, obtaining such knowledge has long been impeded by the challenging nature of the experiments. In recent years, structural and density information for silica glass was obtained at record pressures of up to 100 GPa (ref. 1), a major step towards obtaining data on the molten state. Here we report the structure of molten basalt up to 60 GPa by means of in situ X-ray diffraction. The coordination of silicon increases from four under ambient conditions to six at 35 GPa, similar to what has been reported in silica glass. The compressibility of the melt after the completion of the coordination change is lower than at lower pressure, implying that only a high-order equation of state can accurately describe the density evolution of silicate melts over the pressure range of the whole mantle. The transition pressure coincides with a marked change in the pressure-evolution of nickel partitioning between molten iron and molten silicates, indicating that melt compressibility controls siderophile-element partitioning.

  3. Structural Change and Economic Development in China and India

    Directory of Open Access Journals (Sweden)

    Vittorio Valli

    2009-06-01

    Full Text Available The comparison of the periods of rapid economic growth in China since 1978 and India since 1992 markedly show different patterns of development and structural change. However, both countries experienced some advantages of "relative economic backwardness" and some aspects of the "fordist model of growth". China had an anticipated and deeper structural change, spurred mainly by economic reforms and the growth of the internal market in the 1980s, and, since the mid-1990s, by a very rapid penetration of its industrial products in the world market. However, a substantial part of China's exports in medium and high tech sectors are due to joint-ventures with foreign multinationals. India had a more balanced structural change and a slower insertion in the world market, although some sectors, such as software, steel, automotive and pharmaceuticals are recently increasing their share in the world markets. Owing to the huge number of micro-enterprises and the great size of the informal sector, India benefited much less than China from the economies of scale and from the third wave of the "fordist model of growth". Both countries, but in particular China, experienced negative externalities of this recent phase of rapid growth, such as higher inequalities, pollution and urban congestion.

  4. Laser-induced periodic surface structures on fused silica upon cross-polarized two-color double-fs-pulse irradiation

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • LIPSS formation on fused silica is studied upon cross-polarized two-color (400 and 800 nm) double-fs-pulse irradiation. • LIPSS orientation follows the polarization of the first pulse. • LIPSS periods are determined by the wavelength of the first pulse. • LIPSS area is increased for temporally overlapping pulses due to nonlinear absorption. - Abstract: The dynamics of the formation of laser-induced periodic surface structures (LIPSS) on fused silica upon irradiation with linearly polarized fs-laser pulses (50 fs pulse duration) is studied by cross-polarized two-color double-fs-pulse experiments. In order to analyze the relevance of temporally distributed energy deposition in the early stage of LIPSS formation, a Mach-Zehnder interferometer was used for generating multiple double-pulse sequences at two different wavelengths (400 and 800 nm). The inter-pulse delay between the individual cross-polarized pulses of each sequence was systematically varied in the sub-ps range and the resulting LIPSS morphologies were characterized by scanning electron microscopy. It is found that the polarization of the first laser pulse arriving to the surface determines the orientation and the periodicity of the LIPSS. These two-color experiments further confirm the importance of the ultrafast energy deposition to the silica surface for LIPSS formation, particularly by the first laser pulse of each sequence. The second laser pulse subsequently reinforces the previously seeded spatial LIPSS characteristics (period, orientation)

  5. Laser-induced periodic surface structures on fused silica upon cross-polarized two-color double-fs-pulse irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Höhm, S., E-mail: hoehm@mbi-berlin.de.de [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Herzlieb, M.; Rosenfeld, A. [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Krüger, J. [BAM Bundesanstalt für Materialforschung und–prüfung, Unter den Eichen 87, D-12205 Berlin (Germany); Bonse, J., E-mail: joern.bonse@bam.de [BAM Bundesanstalt für Materialforschung und–prüfung, Unter den Eichen 87, D-12205 Berlin (Germany)

    2015-05-01

    Graphical abstract: - Highlights: • LIPSS formation on fused silica is studied upon cross-polarized two-color (400 and 800 nm) double-fs-pulse irradiation. • LIPSS orientation follows the polarization of the first pulse. • LIPSS periods are determined by the wavelength of the first pulse. • LIPSS area is increased for temporally overlapping pulses due to nonlinear absorption. - Abstract: The dynamics of the formation of laser-induced periodic surface structures (LIPSS) on fused silica upon irradiation with linearly polarized fs-laser pulses (50 fs pulse duration) is studied by cross-polarized two-color double-fs-pulse experiments. In order to analyze the relevance of temporally distributed energy deposition in the early stage of LIPSS formation, a Mach-Zehnder interferometer was used for generating multiple double-pulse sequences at two different wavelengths (400 and 800 nm). The inter-pulse delay between the individual cross-polarized pulses of each sequence was systematically varied in the sub-ps range and the resulting LIPSS morphologies were characterized by scanning electron microscopy. It is found that the polarization of the first laser pulse arriving to the surface determines the orientation and the periodicity of the LIPSS. These two-color experiments further confirm the importance of the ultrafast energy deposition to the silica surface for LIPSS formation, particularly by the first laser pulse of each sequence. The second laser pulse subsequently reinforces the previously seeded spatial LIPSS characteristics (period, orientation)

  6. Ion induced changes in the structure of bordered pit membranes

    Directory of Open Access Journals (Sweden)

    Jinkee eLee

    2012-03-01

    Full Text Available Xylem hydraulic resistance varies with ion concentration in sap solution. It is assumed that this variation in resistance results from hydrogel like properties of pectins located in bordered pit membranes separating adjacent vessels. Although kinetics of the resistance change suggests swelling/deswelling behavior of the pectins, there is no direct evidence of this activity. In this report we provide evidence of structural changes in bordered pit membranes responding to variation in ionic concentration of solute around it using atomic force microscopy (AFM. AFM revealed bordered pit membranes as relatively smooth, soft and lacking any sharp edges surface when submerged in de-ionized water, in contrast to pictures from scanning electron microscope (SEM or AFM performed on air dry material. Exposure of the bordered pit membranes to 50 mM KCl solution resulted in significant changes in both surface physical properties with and elevation features as bordered pit membrane became harder, with visible edges of fibers and collapsed, while no change in porosity was observed. Analysis suggests a need for a major shift in our understanding to the physical bases of variable xylem resistance from change in porosity to change in pathway length. Findings support the role of actuating properties of hybrid hydrogel-cellulose materials in water redistribution and embolism resistance.

  7. Ion induced changes in the structure of bordered pit membranes.

    Science.gov (United States)

    Lee, Jinkee; Holbrook, N Michele; Zwieniecki, Maciej A

    2012-01-01

    Ion-mediated changes in xylem hydraulic resistance are hypothesized to result from hydrogel like properties of pectins located in the bordered pit membranes separating adjacent xylem vessels. Although the kinetics of the ion-mediated changes in hydraulic resistance are consistent with the swelling/deswelling behavior of pectins, there is no direct evidence of this activity. In this report we use atomic force microscopy (AFM) to investigate structural changes in bordered pit membranes associated with changes in the ionic concentration of the surrounding solution. When submerged in de-ionized water, AFM revealed bordered pit membranes as relatively smooth, soft, and lacking any sharp edges surface, in contrast to pictures from scanning electron microscope (SEM) or AFM performed on air-dry material. Exposure of the bordered pit membranes to 50 mM KCl solution resulted in significant changes in both surface physical properties and elevation features. Specifically, bordered pit membranes became harder and the fiber edges were clearly visible. In addition, the membrane contracted and appeared much rougher due to exposed microfibers. In neither solution was there any evidence of discrete pores through the membrane whose dimensions were altered in response to the ionic composition of the surrounding solution. Instead the variable hydraulic resistance appears to involve changes in the both the permeability and the thickness of the pit membrane.

  8. Community structure changes of macrobenthos in the South Yellow Sea

    Institute of Scientific and Technical Information of China (English)

    ZHANG Junlong; XU Fengshan; LIU Ruiyu

    2012-01-01

    The ecological environment in the Yellow Sea has changed greatly from the 1950s to 1990s and this has had significant impact on marine organisms.In this study,data on soft-sediment macrobenthos occurring in depths from 25 m to 81 m in the South Yellow Sea were used to compare changes in community structure.The agglomerative classification (CLUSTER) and multidimensional scaling (MDS) methods were applied.Five communities were recognized by cluster analysis:1.The Yellow Sea Cold Water Mass community dominated by cold water species,which changed slightly in species composition since the 1950s; 2.The mixed community with the coexistence of cold water species and warm water species,as had been reported previously; 3.The polychaete-dominated eurythermal community in which the composition changed considerably as some dominant species disappeared or decreased; 4.The Changjiang (Yangtze) River Estuarine community,with some typical estuarine species; 5.The community affected by the Yellow Sea Warm Current.The greatest change occurred in the coastal area,which indicated that the change may be caused by human activities.Macrobenthos in the central region remained almost unchanged,particularly the cold water species shielded by the Yellow Sea Cold Water Mass.The depth,temperature and median grain size of sediments were important factors affecting the distributions of macrobenthos in the South Yellow Sea.

  9. Ultrathin flexible terahertz polarization converter based on metasurfaces.

    Science.gov (United States)

    Mo, Weicheng; Wei, Xuli; Wang, Kejia; Li, Yao; Liu, Jinsong

    2016-06-13

    We present a method to design and fabricate a kind of converters based on flexible metasurfaces which can change the polarization state of an incident terahertz beam. The metasurface consists of a two-dimensional array of rectangular metallic antennas that can abruptly change the phase of the incoming terahertz beam. Experimentally demonstrated half-wave plates generate 0.1 THz beam with a π/2 polarization rotation. By slightly changing the structure of the converter, an elliptically or circularly polarized beam is expected to be obtained. These flexible terahertz converters may have many potential applications in terahertz technology. PMID:27410377

  10. Researcher and Educator Long Term Collaboration with NOAA ESRL Regarding Atmospheric Ozone Changes at the South Pole Through the NSF PolarTREC Program

    Science.gov (United States)

    Bergholz, E. H.; Hofmann, D. J.; Johnson, B. J.

    2009-12-01

    The NOAA/ESRL team at South Pole has been monitoring the development of the annual ozone hole over two decades using balloon-borne and ground based instruments. Collaboration with educators has become an important aspect of NOAA/ESRL to educate the public about ozone loss and ozone hole formation. Researcher Bryan Johnson and educator Elke Bergholz worked together at South Pole in 1998/1999 as part of the NSF teacher outreach program called Teachers Experiencing Antarctica (TEA).It has been almost a decade when they collaborated again concerning the ozone changes at South Pole as part of the International Polar Year (IPY) and the PolarTREC ( http://wwpolartrec.com ) teacher outreach program sponsored by NSF. The TEA and PolarTREC programs selected teachers to travel to polar locations to work with research scientists collecting data and running experiments at various Arctic and Antarctic field sites, including Elke Bergholz working at the South Pole with the NOAA/ESRL team. While in the field, daily contact with classrooms and students around the globe was done through the internet journals, answering emails from students, and webinars. This has been followed up with presentations to schools and the public relating Ms. Bergholz’s experience and new “hands-on” understanding of ozone instruments and ozone depletion over Antarctica, and discussing what changes in the ozone we have seen at South Pole since the first outreach program nearly a decade ago. The lesson plans are available through the PolarTREC website or by contacting Elke Bergholz at ebergholz@unis.org.

  11. A critical note on the IAGA-endorsed Polar Cap index procedure: effects of solar wind sector structure and reverse polar convection

    Science.gov (United States)

    Stauning, P.

    2015-11-01

    The International Association of Geomagnetism and Aeronomy (IAGA) has recently endorsed a new Polar Cap (PC) index version to supersede the previous seven different versions of the PCN (North) index and the five different PCS (South) index versions. However, the new PC index has some adverse features which should be known and taken into account by users of the index. It uses in its derivation procedure an "effective" quiet day level (QDC) composed of a "basic" QDC and an added solar wind sector term related to the azimuthal component (By) of the interplanetary magnetic field (IMF). The added IMF By-related terms may introduce unjustified contributions to the PC index of more than 2 index units (mV m-1). Furthermore, cases of reverse convection during strong northward IMF Bz (NBZ) conditions included in the database for calculation of index coefficients can cause unjustified index enhancements of 0.5-1 mV m-1 during calm conditions, reduction of index values by more than 20 % during disturbed conditions, and inconsistencies between index coefficients and index values for the northern and southern polar caps. The aim here is to specify these adverse features and quantify their effects, and to suggest alternative steps for future modifications of the index procedure.

  12. A critical note on the IAGA-endorsed Polar Cap index procedure. Effects of solar wind sector structure and reverse polar convection

    Energy Technology Data Exchange (ETDEWEB)

    Stauning, P. [Danish Meteorological Institute, Copenhagen (Denmark)

    2015-07-01

    The International Association of Geomagnetism and Aeronomy (IAGA) has recently endorsed a new Polar Cap (PC) index version to supersede the previous seven different versions of the PCN (North) index and the five different PCS (South) index versions. However, the new PC index has some adverse features which should be known and taken into account by users of the index. It uses in its derivation procedure an ''effective'' quiet day level (QDC) composed of a ''basic'' QDC and an added solar wind sector term related to the azimuthal component (B{sub y}) of the interplanetary magnetic field (IMF). The added IMF B{sub y}-related terms may introduce unjustified contributions to the PC index of more than 2 index units (mV m{sup -1}). Furthermore, cases of reverse convection during strong northward IMF B{sub z} (NBZ) conditions included in the database for calculation of index coefficients can cause unjustified index enhancements of 0.5-1 mV m{sup -1} during calm conditions, reduction of index values by more than 20% during disturbed conditions, and inconsistencies between index coefficients and index values for the northern and southern polar caps. The aim here is to specify these adverse features and quantify their effects, and to suggest alternative steps for future modifications of the index procedure.

  13. Family Structure Changes and Children's Health, Behavior, and Educational Outcomes

    DEFF Research Database (Denmark)

    Rasmussen, Astrid Würtz

    More and more children do not grow up in traditional nuclear families. Instead, they grow up in single-parent households or in families with a step-parent. Hence, it is important to improve our understanding of the impact of "shocks" in family structure due to parental relationship dissolution...... on children. In this study I empirically test whether children are traumatized both in the short and the long run by shocks in the family structure during childhood. I focus on educational, behavioral, and health outcomes. A population sample of Danish children born in January to May 1985 is used...... for the analysis. The empirical cross-sectional analysis indicates a negative relation between the number of family structure changes and children.s health, behavior, and educational outcomes. These results are con.rmed by a differences-in-differences analysis of health outcomes. This suggests...

  14. Structural changes between soda-lime silicate glass and melt

    International Nuclear Information System (INIS)

    Neutron diffraction has been used to study the structure of a glass and melt of composition 75SiO2-15Na2O-10CaO. RMC modeling of the neutron and X-ray diffraction data for the glass allowed the determination of the Na and Ca environment. The structure has been investigated at 300 K, just below the glass transition at 823 K and in the melt at 1273 K. The short range order does not present important modifications with temperature while significant reorganization appears at the medium range order. These latter changes can be associated with the Si and O pairs and indicate the relaxation of the silicate network. This indicates that the glass formation involved structural rearrangement during cooling. (authors)

  15. Quantum entanglement in manganese(II) hexakisimidazole nitrate: on electronic structure imaging - A polarized neutron diffraction and DFT study

    Science.gov (United States)

    Wallace, Warren A.

    2016-04-01

    Quantum entanglement has been visualized for the first time, in view of the spin density distribution and electronic structure for manganese in manganese(II)hexakisimidazole nitrate. Using polarized neutron diffraction and density functional theory modelling we have found for the complex, which crystallizes in the R3¯ spacegroup, a = b = 12.4898(3) Å, c = 14.5526(4) Å, α = γ = 90°, β = 120°, Z = 3, that spatially antisymmetric and spatially symmetric shaped regions of negative spin density, in the spin density map for manganese, are a result of quantum entanglement of the high spin d5 configuration due to dative imidazole- manganese π- donation and σ-bonding interactions respectively. We have found leakage of the entangled states for manganese observed as regions of positive spin density with spherical (3.758(2) μB) and non-spherical (1.242(3) μB) contributions. Our results, which are supportive of Einstein's theory of general relativity, provide evidence for the existence of a black hole spin density distribution at the origin of an electronic structure and also address the paradoxical views of entanglement and quantum mechanics. We have also found the complex, which is an insulator, to be suitable for spintronic studies.

  16. The Case for Tetrahedral Oxy-subhydride (TOSH Structures in the Exclusion Zones of Anchored Polar Solvents Including Water

    Directory of Open Access Journals (Sweden)

    Klaus Oehr

    2014-11-01

    Full Text Available We hypothesize a mechanistic model of how negatively-charged exclusion zones (EZs are created. While the growth of EZs is known to be associated with the absorption of ambient photonic energy, the molecular dynamics giving rise to this process need greater elucidation. We believe they arise due to the formation of oxy-subhydride structures (OH−(H2O4 with a tetrahedral (sp3 (OH−(H2O3 core. Five experimental data sets derived by previous researchers were assessed in this regard: (1 water-derived EZ light absorbance at specific infrared wavelengths, (2 EZ negative potential in water and ethanol, (3 maximum EZ light absorbance at 270 nm ultraviolet wavelength, (4 ability of dimethyl sulphoxide but not ether to form an EZ, and (5 transitory nature of melting ice derived EZs. The proposed tetrahedral oxy-subhydride structures (TOSH appear to adequately account for all of the experimental evidence derived from water or other polar solvents.

  17. Landscape Structure Changes in Liangshui Nature Reserve, Northeast China

    Institute of Scientific and Technical Information of China (English)

    Niu Jianzhi; Gao Jiarong; Wang Fengyou

    2003-01-01

    This paper systematically studied the landscape dynamic changes in Liangshui Natural Reserve (LNR) in Heilongiang Province, northeast China during three periods (1950s, 1970s and 1990s), by applying landscape space modelMarkov model. The results indicated that the landscape structure in LNR changed and the types of landscape patches increased. The phenomena of increasing and reducing of landscape types happened at the same time and the matrix- natural Pinus koraiensis decreased year by year. The law of transformation of landscape types matches well with the results concluded from statistical data,survey data, and the developing process inherent succession of the forest. By analyzing landscape dynamic changes, some scientific management measures were put forward in this paper.

  18. Structural changes in the rural planting areas of Belgrade region

    Directory of Open Access Journals (Sweden)

    Sibinović Mikica

    2012-01-01

    Full Text Available Socio-economic development of the Belgrade region significantly affects the direction of the change of planting areas use. The increase in urban areas has adversely affected the direction of agricultural land use. Dynamics of change is significantly due to high production costs (high land prices and expensive labor force gives rise to the high price of the product on the market, there is a constant "pressure" of urban areas to arable land, increasing the risk of "loss" of agricultural holdings; increased environmental pollution due to the concentration of industrial plants or road construction. The aim of this study was to investigate the characteristics of structural changes in sowing area in the period from 1991 to 2011. [Projekat Ministarstva nauke Republike Srbije, br. 176017

  19. Local structures of polar wurtzites Zn1-xMgxO studied by raman and 67Zn/25Mg NMR spectroscopies and by total neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Proffen, Thomas E [Los Alamos National Laboratory; Kim, Yiung- Il [UCSB; Cadars, Sylvian [UCSB; Shayib, Ramzy [UCSB; Feigerle, Charles S [UNIV OF TENNESSEE; Chmelka, Bradley F [UCSB; Seshadri, Ram [UCSB

    2008-01-01

    Research in the area of polar semiconductor heterostructures has been growing rapidly, driven in large part by interest in two-dimensional electron gas (2DEG) systems. 2DEGs are known to form at heterojunction interfaces that bear polarization gradients. They can display extremely high electron mobilities, especially at low temperatures, owing to spatial confinement of carrier motions. Recent reports of 2DEG behaviors in Ga{sub 1-x}Al{sub x}N/GaN and Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have great significance for the development of quantum Hall devices and novel high-electron-mobility transistors (HEMTs). 2DEG structures are usually designed by interfacing a polar semiconductor with its less or more polar alloys in an epitaxial manner. Since the quality of the 2DEG depends critically on interface perfection, as well as the polarization gradient at the heterojunction, understanding compositional and structural details of the parent and alloy semiconductors is an important component in 2DEG design and fabrication. Zn{sub 1-x}Mg{sub x}O/ZnO is one of the most promising heterostructure types for studies of 2DEGs, due to the large polarization of ZnO, the relatively small lattice mismatch, and the large conduction band offsets in the Zn{sub 1-x}Mg{sub x}O/ZnO heterointerface. Although 2DEG formation in Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have been researched for some time, a clear understanding of the alloy structure of Zn{sub 1-x}Mg{sub x}O is currently lacking. Here, we conduct a detailed and more precise study of the local structure of Zn{sub 1-x}Mg{sub x}O alloys using Raman and solid-state nuclear magnetic resonance (NMR), in conjunction with neutron diffraction techniques.

  20. Changes in fluorescent emission of cationic fluorophores in the presence of n-alkanes and alcohols in different polarity solvents

    Science.gov (United States)

    Delgado-Camón, Arantzazu; Garriga, Rosa; Mateos, Elena; Cebolla, Vicente L.; Galbán, Javier; Membrado, Luis; Marcos, Susana de; Gálvez, Eva M.

    2011-01-01

    Berberine and coralyne experience either fluorescence enhancement or quenching when long hydrocarbon chain compounds (e.g., n-alkanes or alcohols) are added to their solutions, depending on solvent polarity. In polar solvents, as methanol or acetonitrile, the added compounds provide an apolar microenvironment that hinders alternative relaxation mechanisms, favouring fluorescence emission. However, alkane additions produce quenching in dichloromethane, which has been explained taking into account ion pairing between cationic fluorophore and counterion. The strong quenching measured after alcohol additions in dichloromethane suggests reversed micelle formation. Procedures and results described here may find practical applications in the development of analytical methods.