WorldWideScience

Sample records for bents

  1. Construction of bent functions from near-bent functions

    DEFF Research Database (Denmark)

    Leander, Gregor; McGuire, G.

    2009-01-01

    We give a construction of bent functions in dimension 2m from near-bent functions in dimension 2m - 1. in particular, we give the first ever examples of non-weakly-normal bent functions in dimensions 10 and 12, which demonstrates the significance of our construction.......We give a construction of bent functions in dimension 2m from near-bent functions in dimension 2m - 1. in particular, we give the first ever examples of non-weakly-normal bent functions in dimensions 10 and 12, which demonstrates the significance of our construction....

  2. Channeling through Bent Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mack, Stephanie; /Ottawa U. /SLAC

    2012-09-07

    Bent crystals have demonstrated potential for use in beam collimation. A process called channeling is when accelerated particle beams are trapped by the nuclear potentials in the atomic planes within a crystal lattice. If the crystal is bent then the particles can follow the bending angle of the crystal. There are several different effects that are observed when particles travel through a bent crystal including dechanneling, volume capture, volume reflection and channeling. With a crystal placed at the edge of a particle beam, part of the fringe of the beam can be deflected away towards a detector or beam dump, thus helping collimate the beam. There is currently FORTRAN code by Igor Yazynin that has been used to model the passage of particles through a bent crystal. Using this code, the effects mentioned were explored for beam energy that would be seen at the Facility for Advanced Accelerator Experimental Tests (FACET) at a range of crystal orientations with respect to the incoming beam. After propagating 5 meters in vacuum space past the crystal the channeled particles were observed to separate from most of the beam with some noise due to dechanneled particles. Progressively smaller bending radii, with corresponding shorter crystal lengths, were compared and it was seen that multiple scattering decreases with the length of the crystal therefore allowing for cleaner detection of the channeled particles. The input beam was then modified and only a portion of the beam sent through the crystal. With the majority of the beam not affected by the crystal, most particles were not deflected and after propagation the channeled particles were seen to be deflected approximately 5mm. After a portion of the beam travels through the crystal, the entire beam was then sent through a quadrupole magnet, which increased the separation of the channeled particles from the remainder of the beam to a distance of around 20mm. A different code, which was developed at SLAC, was used to

  3. On bent and semi-bent quadratic Boolean functions

    DEFF Research Database (Denmark)

    Charpin, P.; Pasalic, Enes; Tavernier, C.

    2005-01-01

    their results to even n. We further investigate the conditions on the choice of ci for explicit definitions of new infinite families having three and four trace terms. Also, a class of nonpermutation polynomials whose composition with a quadratic function yields again a quadratic semi-bent function is specified...... correlation and high nonlinearity. We say that such a sequence is generated by a semi-bent function. Some new families of such function, represented by f(x) = Sigma(i=1)(n-1/2) c(i)Tr(x(2t+1)), n odd and c(i) is an element of F-2, have recently (2002) been introduced by Khoo et al. We first generalize....... The treatment of semi-bent functions is then presented in a much wider framework. We show how bent and semi-bent functions are interlinked, that is, the concatenation of two suitably chosen semi-bent functions will yield a bent function and vice versa. Finally, this approach is generalized so...

  4. Clues from Bent Jets

    Science.gov (United States)

    Kohler, Susanna

    2018-04-01

    Powerful jets emitted from the centers of distant galaxies make for spectacular signposts in the radio sky. Can observations of these jets reveal information about the environments that surround them?Signposts in the SkyVLA FIRST images of seven bent double-lobed radio galaxies from the authors sample. [Adapted from Silverstein et al. 2018]An active supermassive black hole lurking in a galactic center can put on quite a show! These beasts fling out accreting material, often forming intense jets that punch their way out of their host galaxies. As the jets propagate, they expand into large lobes of radio emission that we can spot from Earth observable signs of the connection between distant supermassive black holes and the galaxies in which they live.These distinctive double-lobed radio galaxies (DLRGs) dont all look the same. In particular, though the jets are emitted from the black holes two poles, the lobes of DLRGs dont always extend perfectly in opposite directions; often, the jets become bent on larger scales, appearing to us to subtend angles of less than 180 degrees.Can we use our observations of DLRG shapes and distributions to learn about their surroundings? A new study led by Ezekiel Silverstein (University of Michigan) has addressed this question by exploring DLRGs living in dense galaxy-cluster environments.Projected density of DLRGcentral galaxy matches (black) compared to a control sample of random positionscentral galaxy matches (red) for different distances from acluster center. DLRGs have a higher likelihood of being located close to a cluster center. [Silverstein et al. 2018]Living Near the HubTo build a sample of DLRGs in dense environments, Silverstein and collaborators started from a large catalog of DLRGs in Sloan Digital Sky Survey quasars with radio lobes visible in Very Large Array data. They then cross-matched these against three galaxy catalogs to produce a sample of 44 DLRGs that are each paired to a nearby massive galaxy, galaxy group

  5. A new construction of bent functions based on Z-bent functions

    DEFF Research Database (Denmark)

    Gangopadhyay, Sugata; Joshi, Anand; Leander, Gregor

    2013-01-01

    Dobbertin has embedded the problem of construction of bent functions in a recursive framework by using a generalization of bent functions called -bent functions. Following his ideas, we generalize the construction of partial spreads bent functions to partial spreads -bent functions of arbitrary...

  6. Bent Core Liquid Crystal Polymers and Elastomers

    Science.gov (United States)

    Verduzco, Rafael; Hong, Seung Ho; Harden, John; Jakli, Antal; Sprunt, Sam; Gleeson, Jim

    2010-03-01

    Bent-core liquid crystals (LCs) have a kinked, or bent, molecular shape in contrast to the more common rod-like LCs. Due to their bent molecular shape, bent-core LCs form locally polar clusters, which result in novel LC phases and potentially useful properties such as ferroelectricity. Polymeric bent-core LCs are of particular interest because they can lead to new nanostructured soft materials with confined bent-core LCs. In this work, we investigate the synthesis, nanoscale structure, and physical properties of a variety of bent-core LCs and polymeric bent-core LCs. SAXS reveals the presence of polar clusters over a wide temperature range in the nematic phase for all materials studied, including bent-core side-group LC polymers and bent-core LC elastomers. The presence of locally polar clusters can account for the unexpected physical properties in nematic bent-core LCs, such as enhanced flexoelectricity. Direct flexoelectric measurements on pure bent-core LCs and swollen LCEs show that nematic bent-core materials have a flexoelectric coupling three orders orders of magnitude larger than calamitic LCs. Nematic clusters in bent-core LCs represent an unexpected and potentially useful phenomenon for building responsive LC devices.

  7. Bent Electro-Absorption Modulator

    DEFF Research Database (Denmark)

    2002-01-01

    components and the applied electric field in relation to the frequency of the modulated radiation, the bending losses (and possibly coupling losses) will provide extinction of light guided by the bent waveguide section. The refractive index contract may be modulated while keeping the absorption coefficient...... by bendng losses co-operates to provide more compact modulators with improved performance (extinction) and speed....

  8. Ion implantation for manufacturing bent and periodically bent crystals

    Energy Technology Data Exchange (ETDEWEB)

    Bellucci, Valerio; Camattari, Riccardo; Guidi, Vincenzo, E-mail: guidi@fe.infn.it; Mazzolari, Andrea; Paternò, Gianfranco [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1/c, 44122 Ferrara, Italy and INFN, Section of Ferrara (Italy); Mattei, Giovanni, E-mail: giovanni.mattei@unipd.it; Scian, Carlo [Department of Physics and Astronomy Galileo Galilei, University of Padova, Via Marzolo 8, 35131 Padova (Italy); Lanzoni, Luca [Dipertimento di Economia e Tecnologia, Università degli Studi della Repubblica di San Marino, Salita alla Rocca, 44, 47890 San Marino Città (San Marino)

    2015-08-10

    Ion implantation is proposed to produce self-standing bent monocrystals. A Si sample 0.2 mm thick was bent to a radius of curvature of 10.5 m. The sample curvature was characterized by interferometric measurements; the crystalline quality of the bulk was tested by X-ray diffraction in transmission geometry through synchrotron light at ESRF (Grenoble, France). Dislocations induced by ion implantation affect only a very superficial layer of the sample, namely, the damaged region is confined in a layer 1 μm thick. Finally, an elective application of a deformed crystal through ion implantation is here proposed, i.e., the realization of a crystalline undulator to produce X-ray beams.

  9. On bent and semi-bent quadratic Boolean functions

    DEFF Research Database (Denmark)

    Charpin, P.; Pasalic, Enes; Tavernier, C.

    2005-01-01

    The maximum-length sequences, also called m-sequences, have received a lot of attention since the late 1960s. In terms of linear-feedback shift register (LFSR) synthesis they are usually generated by certain power polynomials over a finite field and in addition are characterized by a low cross...... their results to even n. We further investigate the conditions on the choice of ci for explicit definitions of new infinite families having three and four trace terms. Also, a class of nonpermutation polynomials whose composition with a quadratic function yields again a quadratic semi-bent function is specified...

  10. Bent functions results and applications to cryptography

    CERN Document Server

    Tokareva, Natalia

    2015-01-01

    Bent Functions: Results and Applications to Cryptography offers a unique survey of the objects of discrete mathematics known as Boolean bent functions. As these maximal, nonlinear Boolean functions and their generalizations have many theoretical and practical applications in combinatorics, coding theory, and cryptography, the text provides a detailed survey of their main results, presenting a systematic overview of their generalizations and applications, and considering open problems in classification and systematization of bent functions. The text is appropriate for novices and advanced

  11. Drop on a bent fibre.

    Science.gov (United States)

    Pan, Zhao; Weyer, Floriane; Pitt, William G; Vandewalle, Nicolas; Truscott, Tadd T

    2018-03-15

    Inspired by the huge droplets attached on cypress tree leaf tips after rain, we find that a bent fibre can hold significantly more water in the corner than a horizontally placed fibre (typically up to three times or more). The maximum volume of the liquid that can be trapped is remarkably affected by the bending angle of the fibre and surface tension of the liquid. We experimentally find the optimal included angle (∼36°) that holds the most water. Analytical and semi-empirical models are developed to explain these counter-intuitive experimental observations and predict the optimal angle. The data and models could be useful for designing microfluidic and fog harvesting devices.

  12. Bent and bent(4) spectra of Boolean functions over finite fields

    DEFF Research Database (Denmark)

    Anbar Meidl, Nurdagül; Meidl, Wilfried

    2017-01-01

    to the conventional Walsh transform, and hence a 0-bent4 function is bent. In this article we generalize the concept of partially bent functions to the transforms V-f(c). We show that every quadratic function is partially bent, and hence it is plateaued with respect to any of the transforms V-f(c). In detail we...... analyse two quadratic monomials. The first has values as small as possible in its spectra with respect to all transforms V-f(c), and the second has a flat spectrum for a large number of c. Moreover, we show that every quadratic function is c-bent4 for at least three distinct c. In the last part we analyse...... a cubic monomial. We show that it is c-bent(4) only for c = 1, the function is then called negabent, which shows that non-quadratic functions exhibit a different behaviour. (C) 2017 Elsevier Inc. All rights reserved....

  13. Behavior of micropiles in bridge bent applications.

    Science.gov (United States)

    2010-12-01

    This project concerned the behavior of micropiles under lateral loads. The North Carolina Department of Transportation was specifically interested in the use of micropiles to support bridge bents. In this configuration micropiles would be subjected t...

  14. Monofluorinated unsymmetrical bent-core mesogens

    NARCIS (Netherlands)

    Achten, R.; Smits, E.A.W.; Reddy, R.A.; Giesbers, M.; Marcelis, A.T.M.; Sudhölter, E.J.R.

    2006-01-01

    The synthesis and mesomorphic properties of 30 bent-core compounds with a fluorine substituent in one of the outer rings are reported. The banana-shaped compounds are all derived from resorcinol and contain esters as linking groups between the five aromatic rings. The different mesophases have been

  15. Wees de controller die u bent

    NARCIS (Netherlands)

    Smit, Marion

    2017-01-01

    Want wie u bent heeft invloed op hoe u uw rol als controller invult, net als uw rol als controller weer invloed heeft op uw identiteit. Een functie is geen objectief of statisch gat waar u in moet passen. Uw collega-controller maakt er iets anders van, de manager verwacht ook wat anders en zelfs de

  16. Imaging with Spherically Bent Crystals or Reflectors

    Energy Technology Data Exchange (ETDEWEB)

    Bitter, M; Hill, K W; Scott, S; Ince-Cushman, A; Reinke, M; Podpaly, Y; Rice, J E; Beiersdorfer, P

    2010-06-01

    This paper consists of two parts: Part I describes the working principle of a recently developed x-ray imaging crystal spectrometer, where the astigmatism of spherically bent crystals is being used with advantage to record spatially resolved spectra of highly charged ions for Doppler measurements of the ion-temperature and toroidal plasmarotation- velocity profiles in tokamak plasmas. This type of spectrometer was thoroughly tested on NSTX and Alcator C-Mod, and its concept was recently adopted for the design of the ITER crystal spectrometers. Part II describes imaging schemes, where the astigmatism has been eliminated by the use of matched pairs of spherically bent crystals or reflectors. These imaging schemes are applicable over a wide range of the electromagnetic radiation, which includes microwaves, visible light, EUV radiation, and x-rays. Potential applications with EUV radiation and x-rays are the diagnosis of laserproduced plasmas, imaging of biological samples with synchrotron radiation, and lithography.

  17. Bent and branched chains of nanoresonators

    Science.gov (United States)

    Melikhova, A. S.; Popov, I. Yu

    2014-10-01

    We study the spectral problem for bent and branched chains of weakly coupled conglobate resonators. At the joint points the δ-coupling is assumed. Our approach is based on the theory of self-adjoint extensions of symmetric operators and transfer matrix method. The structure of the spectrum is described. For the both cases it is proved that the Hamiltonian has negative eigenvalue for some values of the model parameters.

  18. Compensation for gravitational sag of bent mirror

    International Nuclear Information System (INIS)

    Mao, Chengwen; Jiang, Hui; He, Yan; Liang, Dongxu; Lan, Xuying; Yan, Shuai; Shu, De-ming; Li, Aiguo

    2017-01-01

    The gravitational sag of aspheric bent mirrors with face-up or face-down geometry produces a nonnegligible optical error. As an effective compensation, width optimization is used to match the combined effects of the gravitational and bending moments. This method is described by analytical expressions and two calculation algorithms. The results of theoretical simulations and finite element analysis have proved that this method can reduce the slope error resulting from gravitational sag to the level of nano radians.

  19. Compensation for gravitational sag of bent mirror

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Chengwen; Jiang, Hui; He, Yan; Liang, Dongxu; Lan, Xuying; Yan, Shuai [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, CAS, Shanghai 201800 (China); Shu, De-ming [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Li, Aiguo, E-mail: aiguo.li@sinap.ac.cn [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, CAS, Shanghai 201800 (China)

    2017-05-01

    The gravitational sag of aspheric bent mirrors with face-up or face-down geometry produces a nonnegligible optical error. As an effective compensation, width optimization is used to match the combined effects of the gravitational and bending moments. This method is described by analytical expressions and two calculation algorithms. The results of theoretical simulations and finite element analysis have proved that this method can reduce the slope error resulting from gravitational sag to the level of nano radians.

  20. Novel polymerizable bent-shaped monomeric molecules

    Czech Academy of Sciences Publication Activity Database

    Kozmik, V.; Kovářová, A.; Kuchař, M.; Svoboda, Jiří; Novotná, Vladimíra; Glogarová, Milada; Kroupa, Jan

    2006-01-01

    Roč. 33, č. 1 (2006), s. 41-56 ISSN 0267-8292 R&D Projects: GA ČR(CZ) GA202/05/0431; GA MŠk(CZ) OC D14.50 Institutional research plan: CEZ:AV0Z10100520 Keywords : mesogens * polymerizable * bent-shaped molecules * liquid crystals * ferroelectricity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.417, year: 2006

  1. Bent Solenoids with Superimposed Dipole Fields

    Energy Technology Data Exchange (ETDEWEB)

    Meinke, Rainer, B.; Goodzeit, Carl, L.

    2000-03-21

    A conceptual design and manufacturing technique were developed for a superconducting bent solenoid magnet with a superimposed dipole field that would be used as a dispersion device in the cooling channel of a future Muon Collider. The considered bent solenoid is equivalent to a 180° section of a toroid with a major radius of ~610 mm and a coil aperture of ~416 mm. The required field components of this magnet are 4 tesla for the solenoid field and 1 tesla for the superimposed dipole field. A magnet of this size and shape, operating at these field levels, has to sustain large Lorentz forces resulting in a maximum magnetic pressure of about 2,000 psi. A flexible round mini-cable with 37 strands of Cu-NbTi was selected as the superconductor. Detailed magnetic analysis showed that it is possible to obtain the required superimposed dipole field by tilting the winding planes of the solenoid by ~25°. A complete structural analysis of the coil support system and the helium containment vessel under thermal, pressure, and Lorentz force loads was carried out using 3D finite element models of the structures. The main technical issues were studied and solutions were worked out so that a highly reliable magnet of this type can be produced at an affordable cost.

  2. Bent-Pipe Vs On-Board Processing

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Bent-Pipe Vs On-Board Processing. “Bent-Pipe” refers to satellites. that do not process the transmitted signal but merely relay it from one ground station to another. The On-Board Processing allows. Multi-beam frequency re-use which increases satellite raw capacity; ...

  3. 31 CFR 100.11 - Exchange of bent and partial coins.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Exchange of bent and partial coins... OF PAPER CURRENCY AND COIN Exchange of Coin § 100.11 Exchange of bent and partial coins. (a) Definitions. (1) Bent coins are U.S. coins which are bent or deformed so as to preclude normal machine...

  4. Bente Boa, Torm, Denmark

    DEFF Research Database (Denmark)

    Wagtmann, Maria Anne

    2009-01-01

    At the beginning of July 2009, Maria Anne Wagtmann (Associate Professor, PhD, University of Southern Denmark) had the opportunity to interview Ms Bente Boa, a senior marine HR manager in the Danish ship owning firm TORM A/S' (http://www.torm.com/). Bente Boa is also chairwoman of the "The Sea Ser...... Serpent" (in Danish: "Søslangen"), a Danish maritime HR network for professionals in maritime firms....

  5. Channeling and radiation in periodically bent crystals

    CERN Document Server

    Korol, Andrey V; Greiner, Walter

    2014-01-01

    The development of coherent radiation sources for sub-angstrom wavelengths - i.e. in the hard X-ray and gamma-ray range -  is a challenging goal of modern physics. The availability of such sources will have many applications in basic science, technology and medicine, and, in particular, they may have a revolutionary impact on nuclear and solid state physics, as well as on the life sciences. The present state-of-the-art lasers are capable of emitting electromagnetic radiation from the infrared to the ultraviolet, while free electron lasers (X-FELs) are now entering the soft X-ray region. Moving further, i.e. into the hard X and/or gamma ray band, however, is not possible without new approaches and technologies.   In this book we introduce and discuss one such novel approach -the radiation formed in a Crystalline Undulator - whereby electromagnetic radiation is generated by a bunch of ultra-relativistic particles channeling through a periodically bent crystalline structure. Under certain conditions, such a d...

  6. Giant flexoelectricity of bent-core nematic liquid crystals.

    Science.gov (United States)

    Harden, J; Mbanga, B; Eber, N; Fodor-Csorba, K; Sprunt, S; Gleeson, J T; Jákli, A

    2006-10-13

    Flexoelectricity is a coupling between orientational deformation and electric polarization. We present a direct method for measuring the flexoelectric coefficients of nematic liquid crystals (NLCs) via the electric current produced by periodic mechanical flexing of the NLC's bounding surfaces. This method is suitable for measuring the response of bent-core liquid crystals, which are expected to demonstrate a much larger flexoelectric effect than traditional, calamitic liquid crystals. Our results reveal that not only is the bend flexoelectric coefficient of bent-core NLCs gigantic (more than 3 orders of magnitude larger than in calamitics) but also it is much larger than would be expected from microscopic models based on molecular geometry. Thus, bent-core nematic materials can form the basis of a technological breakthrough for conversion between mechanical and electrical energy.

  7. Liquid crystal elastomers: Bent core flexo-electricity

    Science.gov (United States)

    Chambers, Martin; Verduzco, Rafael; Sprunt, Samuel; Gleeson, James T.; Jakli, Antal

    2009-03-01

    We report on the swelling of calamitic liquid crystal elastomers (LCE) with bent-core mesogens (BCM); this swelling took place at a temperature where both materials were in their isotropic phase. The BCM used varied in the degree of saturation of their hydrocarbon tails, which affects both viscosity and phase behaviour. We determined both swelling magnitude and dynamics. The host LCE systems homogeneously imbibe BCM up to 30-40 % mol. Based on differential scanning calorimetry, shape change anisotropy, and optical birefringence measurements, the swollen elastomers are all found to exhibit nematic phases, with some possessing a lower temperature smectic phase. Bent-core liquid crystal elastomers and swollen calamitic LCE in BCM were investigated for the flexoelectric properties by inducing a mechanical deformation. The value of the bend flexoelectric constant, e3 of the swollen BCM containing LCE systems is comparable of that of the neat bent-core liquid crystal.

  8. The Nematic Phases of Bent-Core Liquid Crystals

    Science.gov (United States)

    Gleeson, Helen F; Kaur, Sarabjot; Görtz, Verena; Belaissaoui, Abdel; Cowling, Stephen; Goodby, John W

    2014-01-01

    Over the last ten years, the nematic phases of liquid crystals formed from bent-core structures have provoked considerable research because of their remarkable properties. This Minireview summarises some recent measurements of the physical properties of these systems, as well as describing some new data. We concentrate on oxadiazole-based materials as exemplars of this class of nematogens, but also describe some other bent-core systems. The influence of molecular structure on the stability of the nematic phase is described, together with progress in reducing the nematic transition temperatures by modifications to the molecular structure. The physical properties of bent-core nematic materials have proven difficult to study, but patterns are emerging regarding their optical and dielectric properties. Recent breakthroughs in understanding the elastic and flexoelectric behaviour are summarised. Finally, some exemplars of unusual electric field behaviour are described. PMID:24700653

  9. Residual strain distribution in bent composite boiler tubes

    International Nuclear Information System (INIS)

    Tang Fei; Hubbard, Camden R.; Sarma, Gorti; Keiser, James

    2006-01-01

    Kraft recovery boilers are typically constructed of carbon steel boiler tubes clad with a corrosion resistant layer, and these composite tubes are bent and welded together to form air port panels which enable the combustion air to enter the boiler. In this paper, the through-thickness residual strain in the carbon steel layer of non-heat-treated and heat-treated composite bent tubes were measured by neutron diffraction techniques and modeled by finite element modeling. The results can be used to optimize material selection and manufacturing processes to prevent stress corrosion and corrosion fatigue cracking in the boiler tubes

  10. Mesomorphic properties of a bent-shaped liquid crystalline monomer

    Czech Academy of Sciences Publication Activity Database

    Novotná, Vladimíra; Baumeister, U.; Kohout, M.; Svoboda, J.

    2012-01-01

    Roč. 86, č. 5 (2012), 503-515 ISSN 0141-1594 R&D Projects: GA ČR(CZ) GAP204/11/0723 Institutional support: RVO:68378271 Keywords : liquid crystals * bent-shaped mesogen Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.863, year: 2012

  11. Bent Flyvbjerg: Power and project management, an appreciation

    NARCIS (Netherlands)

    Clegg, S.R.

    2008-01-01

    Purpose – The purpose of this paper is to provide a critique of Bent Flyybjerg's work that has high relevance to the project management (PM) literature. Design/methodology/approach – The paper takes the form of a narrative with argument and analysis. Findings – The paper challenges readers, PM

  12. Bent Shaped 1, 3, 4-Oxadiazole/Thiadiazole heterocyclic rings ...

    Indian Academy of Sciences (India)

    Two series of bent shaped 1,3,4-oxadiazole/thiadiazole heterocyclic ring containing liquid crystalline (LC) compounds were synthesized and characterized by FT-IR, 1H, 13C-NMR and ESI-Mass spectro-scopic techniques. Liquid crystal properties were investigated by polarized optical microscopy and differential scanning ...

  13. Beam-smiling in bent-Laue monochromators

    International Nuclear Information System (INIS)

    Ren, B.; Dilmanian, F. A.; Wu, X. Y.; Huang, X.; Chapman, L. D.; Ivanov, I.; Zhong, Z.; Thomlinson, W. C.

    1997-01-01

    When a wide fan-shaped x-ray beam is diffracted by a bent crystal in the Laue geometry, the profile of the diffracted beam generally does not appear as a straight line, but as a line with its ends curved up or curved down. This effect, referred to as 'beam-smiling', has been a major obstacle in developing bent-Laue crystal monochromators for medical applications of synchrotron x-ray. We modeled a cylindrically bent crystal using the Finite Element Analysis (FEA) method, and we carried out experiments at the National Synchrotron Light Source and Cornell High Energy Synchrotron Source. Our studies show that, while beam-smiling exists in most of the crystal's area because of anticlastic bending effects, there is a region parallel to the bending axis of the crystal where the diffracted beam is 'smile-free'. By applying asymmetrical bending, this smile-free region can be shifted vertically away from the geometric center of the crystal, as desired. This leads to a novel method of compensating for beam-smiling. We will discuss the method of ''differential bending'' for smile removal, beam-smiling in the Cauchios and the polychromatic geometry, and the implications of the method on developing single- and double-bent Laue monochromators. The experimental results will be discussed, concentrating on specific beam-smiling observation and removal as applied to the new monochromator of the Multiple Energy Computed Tomography [MECT] project of the Medical Department, Brookhaven National Laboratory

  14. Flexoelectricity in an oxadiazole bent-core nematic liquid crystal

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, S., E-mail: Sarabjot.Kaur@manchester.ac.uk; Panov, V. P.; Gleeson, H. F. [School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Greco, C.; Ferrarini, A. [Department of Chemical Sciences, University of Padua, Padua I-35131 (Italy); Görtz, V. [Department of Chemistry, University of York, York YO10 5DD (United Kingdom); Department of Chemistry, University of Lancaster, Lancaster LA1 4YB (United Kingdom); Goodby, J. W. [Department of Chemistry, University of York, York YO10 5DD (United Kingdom)

    2014-12-01

    We have determined experimentally the magnitude of the difference in the splay and bend flexoelectric coefficients, |e{sub 1} − e{sub 3}|, of an oxadiazole bent-core liquid crystal by measuring the critical voltage for the formation of flexodomains together with their wave number. The coefficient |e{sub 1} − e{sub 3}| is found to be a factor of 2–3 times higher than in most conventional calamitic nematic liquid crystals, varying from 8 pCm{sup −1} to 20 pCm{sup −1} across the ∼60 K—wide nematic regime. We have also calculated the individual flexoelectric coefficients e{sub 1} and e{sub 3}, with the dipolar and quadrupolar contributions of the bent-core liquid crystal by combining density functional theory calculations with a molecular field approach and atomistic modelling. Interestingly, the magnitude of the bend flexoelectric coefficient is found to be rather small, in contrast to common expectations for bent-core molecules. The calculations are in excellent agreement with the experimental values, offering an insight into how molecular parameters contribute to the flexoelectric coefficients and illustrating a huge potential for the prediction of flexoelectric behaviour in bent-core liquid crystals.

  15. Flexoelectricity in an oxadiazole bent-core nematic liquid crystal

    International Nuclear Information System (INIS)

    Kaur, S.; Panov, V. P.; Gleeson, H. F.; Greco, C.; Ferrarini, A.; Görtz, V.; Goodby, J. W.

    2014-01-01

    We have determined experimentally the magnitude of the difference in the splay and bend flexoelectric coefficients, |e 1 − e 3 |, of an oxadiazole bent-core liquid crystal by measuring the critical voltage for the formation of flexodomains together with their wave number. The coefficient |e 1 − e 3 | is found to be a factor of 2–3 times higher than in most conventional calamitic nematic liquid crystals, varying from 8 pCm −1 to 20 pCm −1 across the ∼60 K—wide nematic regime. We have also calculated the individual flexoelectric coefficients e 1 and e 3 , with the dipolar and quadrupolar contributions of the bent-core liquid crystal by combining density functional theory calculations with a molecular field approach and atomistic modelling. Interestingly, the magnitude of the bend flexoelectric coefficient is found to be rather small, in contrast to common expectations for bent-core molecules. The calculations are in excellent agreement with the experimental values, offering an insight into how molecular parameters contribute to the flexoelectric coefficients and illustrating a huge potential for the prediction of flexoelectric behaviour in bent-core liquid crystals

  16. Cardiorespiratory and metabolic responses during straight and bent knee cycling.

    Science.gov (United States)

    Mandroukas, K; Angelopoulou, N; Christoulas, K; Vrabas, I S

    2000-06-01

    This study examined the influence of knee angle on the cardiorespiratory system loading during submaximal and maximal stationary cycle ergometry. Experimental design and participants: eighteen untrained women (age: 21+/-1.88 years, weight: 57+/-5.75 kg, height: 165+/-5.03 cm, values are mean+/-SD) volunteered as subjects and underwent two-cycle ergometer incremental (Jaeger ER900) tests: 1) straight knee (180 degrees), 2) bent knee (140 degrees). oxygen uptake (VO2), ventilation (VE) and respiratory exchange ratio (RER) were measured continuously during each test using an open circuit spirometry and blood lactate concentration was determined by means of an enzymatic method. Comparing cycling with "straight knee" to cycling with "bent knee" at 50 W, heart rate (HR), V(E) and VO2 were significantly higher (10.6%, 12.5%, 17.8%). At 100 W, blood lactate was significantly lower (10.8%) while VO2 and RER was higher (5.5%, 7.1%). During maximal exercise, the total exercise time was significantly longer (11.2%) and VE, VO2 and HR were significantly higher during cycling with "straight knee" compared to cycling with "bent knee". No significant difference in peak lactate was evident between the two sitting positions. The results of this study indicate that cycling with bent knee requires lower oxygen uptake while pedaling with straight knee is the only way to reach VO2max during cycle testing, since the cardiorespiratory system is fully taxed.

  17. Trafiksikkerhedseffekten af variable hastighedstavler i åbent land

    DEFF Research Database (Denmark)

    Larsen, Mette Kathrine; Andersen, Camilla Sloth

    2017-01-01

    I trafiksikkerhedsarbejdet er effektstudier væsentlige. Effektstudierne udarbejdes, således at andre vejmyndigheder kan se, hvilke effekter et givent tiltag kan have. I dette studie er der udarbejdet et effektstudie over variable hastighedstavler i åbent land, og yderligere er det undersøgt...

  18. Calamitic Smectic A-Polar Smectic APA Transition Observed in Bent Molecules with Large Bent-Angle Central Core of 4,6-Dichlorobenzene and Alkylthio Terminal Tail

    Science.gov (United States)

    Nguyen, Ha; Kang, Sungmin; Tokita, Masatoshi; Watanabe, Junji

    2011-07-01

    New homologs of bent molecules with a large bent-angle central core of 4,6-dichloro benzene and an alkylthio terminal tail have been synthesized. Although the corresponding alkoxy-tail homologs show only the calamitic phases because of its large bent angles around 160°, the new homologs with an alkylthio tail exhibit the antiferroelectric smectic APA (SmAPA) banana phase that is transformed on cooling from the calamitic smectic A (SmA) phase. The biaxial polar packing of bent molecules in the SmAPA phase is considered to arise from the hindered rotation around the molecular long axis due to the expansion of the mesophase temperatures to a lower temperature region. This study indicates that the bent molecules, even with a large bent angle, have the potential to form a switchable banana phase with a remarkable decrease in its phase temperature range to around 60 °C.

  19. Manipulation of hadron beams with bent crystals in circular accelerators

    CERN Document Server

    Rossi, R; Redaelli, S; Scandale, W

    2016-01-01

    Over the past years the understanding and use of coherent interactions of charged particles with ordered crystal lattices has achieved excellent results. Improving collimation of hadron beams in circular accelerators, like the Large Hadron Collider (LHC) of the European Council for Nuclear Research (CERN), it is one of the possible applications. The aim of the UA9 experiment is to demonstrate the feasibility of a two-stage collimation system in the CERN-SPS : the first stage is a bent crystal oriented for an optimal channeling of the incoming halo particles; the second stage is a massive absorber. Two crystals were installed in the LHC last year and a test of crystal assisted collimation at the highest energy will be possible as early as 2015. Finally, the UA9 Collaboration is investigating extraction of particles from a circular accelerator, based on bent crystals.

  20. Converse flexoelectric effect in bent-core nematic liquid crystals.

    Science.gov (United States)

    Kumar, Pramoda; Marinov, Y G; Hinov, H P; Hiremath, Uma S; Yelamaggad, C V; Krishnamurthy, K S; Petrov, A G

    2009-07-09

    We report on the converse flexoelectric effect in two bent-core nematic liquid crystals with opposite dielectric anisotropies. The results are based on electro-optic investigations of inplane field-driven distortions in homeotropic samples (the Helfrich method). They are interpreted by an extension of the Helfrich theory that takes into account the higher order distortions. The bend flexocoefficient for both the compounds is of the usual order of magnitude as in calamitics, unlike in a previously investigated bent-core nematic for which giant values of the bend flexocoefficient are reported. In order to resolve this discrepancy, we propose a molecular model with nonpolar clusters showing quadrupolar flexoelectricity. The study also includes measurements on surface polarization instabilities in the dielectrically positive material; the splay flexocoefficient thereby deduced is also of the conventional order.

  1. Extraction from TEV-range accelerators using bent crystal channeling

    International Nuclear Information System (INIS)

    Carrigan, R.A. Jr.; Jackson, G.; Murphy, C.T.; Newberger, B.

    1993-01-01

    Plans and first results from Fermilab Experiment 853 are presented. E853 is an experiment to test the feasibility and efficiency of extracting a low-intensity beam from the halo of the Tevatron using channeling in a bent silicon crystal. The motivation of the experiment is to apply crystal extraction to trans-TeV accelerators like the SSC. Channeling developments related to crystal extraction and some early results from accelerator studies at the Tevatron are presented

  2. Double bent crystal dispersive arrangement for high resolution diffractometry

    Czech Academy of Sciences Publication Activity Database

    Mikula, Pavol; Vrána, Miroslav; Šaroun, Jan; Em, V.; Seong, B. S.; Woo, W.

    2012-01-01

    Roč. 340, 012014 (2012), s. 1-6 ISSN 1742-6588. [5th European Conference on Neutron Scattering. Praha, 17.07.2011-21.07.2011] R&D Projects: GA ČR GAP204/10/0654; GA AV ČR KJB100480901 EU Projects: European Commission(XE) 226507 - NMI3 Institutional support: RVO:61389005 Keywords : neutron diffraction * double bent Subject RIV: BG - Nuclear, Atomic and Molecular Physics , Colliders

  3. Beam-smiling in bent-Laue monochromators

    International Nuclear Information System (INIS)

    Ren, B.; Dilmanian, F.A.; Wu, X.Y.; Huang, X.; Ivanov, I.; Thomlinson, W.C.

    1997-01-01

    When a wide fan-shaped x-ray beam is diffracted by a bent crystal in the Laue geometry, the profile of the diffracted beam generally does not appear as a straight line, but as a line with its ends curved up or curved down. This effect, referred to as ' beam-smiling', has been a major obstacle in developing bent-Laue crystal monochromators for medical applications of synchrotron x-ray. We modeled a cylindrically bent crystal using the Finite Element Analysis (FEA) method, and we carried out experiments at the National Synchrotron Light Source and Cornell High Energy Synchrotron Source. Our studies show that, while beam-smiling exists in most of the crystal close-quote s area because of anticlastic bending effects, there is a region parallel to the bending axis of the crystal where the diffracted beam is ' smile-free'. By applying asymmetrical bending, this smile-free region can be shifted vertically away from the geometric center of the crystal, as desired. This leads to a novel method of compensating for beam-smiling. We will discuss the method of ' differential bending' for smile removal, beam-smiling in the Cauchios and the polychromatic geometry, and the implications of the method on developing single- and double-bent Laue monochromators. The experimental results will be discussed, concentrating on specific beam-smiling observation and removal as applied to the new monochromator of the Multiple Energy Computed Tomography [MECT] project of the Medical Department, Brookhaven National Laboratory. copyright 1997 American Institute of Physics

  4. Bent versus straight tips in micropulsed longitudinal phacoemulsification.

    Science.gov (United States)

    Stagg, Brian C; Gupta, Isha; Cahoon, Judd; Ronquillo, Cecinio; Shi, Dallas; Zaugg, Brian; Gardiner, Gareth; Barlow, William R; Pettey, Jeff H; Aabid Farukhi, M; Jensen, Jason; Olson, Randall J

    2015-10-01

    The aim of this study was to evaluate bent and straight phacoemulsification tips to determine which tip is more efficient in removal of lens fragments, using micropulsed longitudinal ultrasound in phacoemulsification. In vitro laboratory study. The John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, was the study setting. Pig lenses hardened in a manner comparable with dense human cataracts were cut into 2-mm cubes and removed with micropulsed longitudinal ultrasound using settings previously shown to be optimally efficient (6 milliseconds on and 6 milliseconds off for a bent tip). To verify this time as most efficient for a straight tip, we also tested times of 5, 6, and 7 milliseconds time on and off. The tips were either straight or with a 20-degree bend. Twenty cubes were used for each comparative run. For the straight tip, 6 milliseconds on (1.56 ± 0.815 seconds) was significantly more efficient than 7 milliseconds on (2.45 ± 1.56 seconds, p = 0.001) and not significantly more efficient than 5 milliseconds on (1.69 ± 0.86 seconds, p = 0.43). Five milliseconds off time (1.45 ± 0.76s) was more efficient than 6 milliseconds (2.06 ± 1.37 seconds, p = 0.004) and 7 milliseconds off (2.18 ± 1.24s, p = 0.001). The straight tip was more efficient than the bent tip (1.38 ± 0.83 versus 2.93 ± 2.14 seconds, p = 0.006). Results are contrary to accepted common belief. Micropulsed longitudinal phacoemulsification is more efficient with a straight rather than a bent tip. Copyright © 2015 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

  5. Probing strain in bent semiconductor nanowires with Raman spectroscopy.

    Science.gov (United States)

    Chen, Jianing; Conache, Gabriela; Pistol, Mats-Erik; Gray, Struan M; Borgström, Magnus T; Xu, Hongxing; Xu, H Q; Samuelson, Lars; Håkanson, Ulf

    2010-04-14

    We present a noninvasive optical method to determine the local strain in individual semiconductor nanowires. InP nanowires were intentionally bent with an atomic force microscope and variations in the optical phonon frequency along the wires were mapped using Raman spectroscopy. Sections of the nanowires with a high curvature showed significantly broadened phonon lines. These observations together with deformation potential theory show that compressive and tensile strain inside the nanowires is the physical origin of the observed phonon energy variations.

  6. Non-symmetrical bent-shaped compounds containing chiral moiety

    Czech Academy of Sciences Publication Activity Database

    Novotná, Vladimíra; Mieczkowska, B.; Hamplová, Věra; Domján, A.; Pociecha, D.; Kašpar, Miroslav; Fodor-Csorba, K.

    2012-01-01

    Roč. 39, č. 10 (2012), s. 1252-1260 ISSN 0267-8292 R&D Projects: GA ČR(CZ) GAP204/11/0723 Institutional research plan: CEZ:AV0Z10100520 Keywords : bent-shaped mesogen * columnar phase * ferroelectricity * polar switching Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.959, year: 2012 http://www.tandfonline.com/doi/abs/10.1080/02678292.2012.714485

  7. Surface Curvatures and Diffraction Profiles of Sagittaly Bent Laue Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Shi, X.; Takacs, P.; Ghose, S.; Zhong, Z.; Rehak, M.L.; Kaznatcheev, K.; Dooryhee, E.

    2011-05-17

    The performance of a bent Laue crystal monochromator crucially depends on the sagittal and meridional bending curvatures of the crystal. To optimize the design of monochromator crystals, the surface curvatures and diffraction profiles of a set of sagittally bent Laue crystals with different aspect ratios have been studied experimentally by optical metrology and X-ray measurements. The results were confirmed with finite-element analysis using large-deformation theory. The nonlinear relationship between the curvatures necessitates an experimentally determined parameter in the theoretical modeling of the diffraction profiles. By taking into account the local stress and the aspect ratio of the sagittally bent Laue crystal, the modified analytical approach successfully predicts the rocking-curve width and the integrated reflecting power. The effect of extreme sagittal bending on the rocking curve is also discussed. To retain high reflectivity, the bending curvature should not exceed its critical value for the specified crystal geometry. Furthermore, the uniformity of the bending curvatures across the crystal surface has been examined, which suggests that the minimum crystal dimension should be approximately twice the size of the beam footprint.

  8. Analysis of Circular Polarization of Cylindrically Bent Microstrip Antennas

    Directory of Open Access Journals (Sweden)

    Tiiti Kellomäki

    2012-01-01

    Full Text Available When circularly polarized (CP microstrip antennas are bent, the polarization becomes elliptical. We present a simple model that describes the phenomenon. The two linear modes present in a CP patch are modeled separately and added together to produce CP. Bending distorts the almost-spherical equiphase surface of a linearly polarized patch, which leads to phase imbalance in the far-field of a CP patch. The model predicts both the frequency shifting of the axial ratio band as well as the narrowing of the axial ratio beam. Uncontrolled bending is a problem associated especially with flexible textile antennas, and wearable antennas should therefore be designed somewhat conformal.

  9. Riot at the calc exam and other mathematically bent stories

    CERN Document Server

    Adams, Colin

    2009-01-01

    What's so funny about math? Lots! Especially if you're mathematically bent. In the world of Colin Adams, differential equations bring on tears of laughter. Hollywood producers hire algebraic geometers to punch up a script. In this world, math and humor are synonymous. Riot at the Calc Exam is a proof of this fact. A collection of humorous math stories, this book gives a window into mathematics and the culture of mathematicians. Appropriate for mathematicians, math students, math teachers, lay people with an interest in mathematics, and indeed everyone else. This book is a romp through the wild

  10. A SYNTHESIS METHOD OF BASIC TERNARY BENT-SQUARES BASED ON THE TRIAD SHIFT OPERATOR

    Directory of Open Access Journals (Sweden)

    O. N. Zhdanov

    2017-01-01

    Full Text Available Practical application of advanced algebraic constructions in modern communication systems based on MC-CDMA (Multi Code Code Division Multiple Access technology and in cryptography necessitates their further research. One of the most commonly used advanced algebraic construction is the binary bent-function having a uniform amplitude spectrum of the Walsh-Hadamard transform and, accordingly, having the maximal distance from the codewords of affine code. In addition to the binary bent-functions researchers are currently focuses on the development of synthesis methods of their many-valued analogues. In particular, one of the most effective methods for the synthesis of many-valued bent-functions is the method based on the Agievich bent-squares. In this paper, we developed a regular synthesis method of the ternary bent-squares on the basis of an arbitrary spectral vector and the regular operator of the triad shift. The classification of spectral vectors of lengths N = 3 and N = 9 is performed. On the basis of spectral classification more precise definition of many-valued bent-sequences is given, taking into account the existence of the phenomenon of many-valued bent-sequences for the length, determined by odd power of base. The paper results are valuable for practical use: the development of new constant amplitude codes for MC-CDMA technology, cryptographic primitives, data compression algorithms, signal structures, algorithms of block and stream encryption, based on advanced principles of many-valued logic. The developed bent-squares design method is also a basis for further theoretical research: development of methods of the permutation of rows and columns of basic bent-squares and their sign coding, synthesis of composite bent-squares. In addition, the data on the spectral classification of vectors give the task of constructing the synthesis methods of bent-functions of lengths N = 32k+1, k Є ℕ.

  11. High energy beam line based on bent crystal

    International Nuclear Information System (INIS)

    Biryukov, V.M.; Chesnokov, Yu.A.; Greth, V.N.; Ivanov, A.A.; Kotov, V.I.; Selesnev, V.S.; Tarakanov, M.V.; Terekhov, V.I.; Tsarik, S.V.

    1995-01-01

    A peculiarities of the beam bent with crystals is the independence of the crystal deflector strength Θ=L D /R c ∼0.5 rad of the particle energy (L D is the dechanneling length, R c is the critical radius). The possibility of abrupt bending with crystal of a beam fraction at a large angle allows one to make over a short base a non-traditional beam line to carry out physical experiments. At IHEP, a 150 mrad bent crystal was used to create a test area, to work in parallel with other set-ups consuming practically no power. A 100 mm long Si crystal, placed in the halo of the intense extracted 70 GeV/c beam, extracts along the ∼20 m base 10 6 protons/sec beyond the 2-meter iron-concrete shield. The beam high quality (low emittance and high stability) allows one to carry out the program of the studies of channeling and testing the microstrip detectors. 2 refs.; 2 figs

  12. Numerical Prediction of Springback Shape of Severely Bent Sheet Metal

    International Nuclear Information System (INIS)

    Iwata, Noritoshi; Murata, Atsunobu; Yogo, Yasuhiro; Tsutamori, Hideo; Niihara, Masatomo; Ishikura, Hiroshi; Umezu, Yasuyoshi

    2007-01-01

    In the sheet metal forming simulation, the shell element widely used is assumed as a plane stress state based on the Mindlin-Reissner theory. Numerical prediction with the conventional shell element is not accurate when the bending radius is small compared to the sheet thickness. The main reason is because the strain and stress formulation of the conventional shell element does not fit the actual phenomenon. In order to predict precisely the springback of a bent sheet with a severe bend, a measurement method for through-thickness strain has been proposed. The strain was formulated based on measurement results and calculation results from solid element. Through-thickness stress distribution was formulated based on the equilibrium. The proposed shell element based on the formulations was newly introduced into the FEM code. The accuracy of this method's prediction of the springback shape of two bent processes has been confirmed. As a result, it was found that the springback shape even in severe bending can be predicted with high accuracy. Moreover, the calculation time in the proposed shell element is about twice that in the conventional shell element, and has been shortened to about 1/20 compared to a solid element

  13. Technology transfer: taking science from the books to the ground at Bent Creek Experimental Forest

    Science.gov (United States)

    Julia Kirschman

    2014-01-01

    Technology transfer has been an important part of the research program at Bent Creek Experimental Forest (Bent Creek) since its establishment in 1925. Our stated mission is to develop and disseminate knowledge and strategies for restoring, managing, sustaining, and enhancing the vegetation and wildlife of upland hardwood-dominated forest ecosystems of the Southern...

  14. Magnetic-Force-Assisted Straightening of Bent Mild Steel Strip by Laser Irradiation

    Science.gov (United States)

    Dutta, Polash P.; Kalita, Karuna; Dixit, Uday S.; Liao, Hengcheng

    2017-12-01

    This study proposes a technique to straighten bent metallic strips with magnetic-force-assisted laser irradiation. Experiments were conducted for three different types of mechanically-bent mild strips. The first type was bent strips without any heat treatment. The second type was stress-relieved and third type was subcritical-annealed bent strips. These strips were straightened following different schemes of laser irradiation sequence to understand the performance of straightening. A parametric study was conducted by varying laser power and scanning speed. Micro-hardness, tensile test, Charpy impact test and microstructure after straightening were also studied. Different scanning schemes provided different microstructures and mechanical properties. Any serious deterioration in the quality of straightened strips was not noticed. Overall, subcritical-annealed bent strips provided the best performance in straightening. The proposed straightening scheme has potential of becoming an industrial practice.

  15. Bent Telescopic Rods in Patients With Osteogenesis Imperfecta.

    Science.gov (United States)

    Lee, R Jay; Paloski, Michael D; Sponseller, Paul D; Leet, Arabella I

    2016-09-01

    Telescopic rods require alignment of 2 rods to enable lengthening. A telescopic rod converts functionally into a solid rod if either rod bends, preventing proper engagement. Our goal was to characterize implant bending as a mode of failure of telescopic rods used in the treatment of osteogenesis imperfecta in children. We conducted a retrospective review of our osteogenesis imperfecta database for patients treated with intramedullary telescopic rods at our institution from 1992 through 2010 and identified 12 patients with bent rods. The 6 boys and 6 girls had an average age at the time of initial surgery of 3.1 years (range, 1.8 to 8.3 y) and a total of 51 telescoping rods. Clinic notes, operative reports, and radiographs were reviewed. The rods were analyzed for amount of lengthening, characteristics of bending, presence of cut out, or disengagement from an anchor point. Bends in the rods were characterized by their location on the implant component. The bent and straight rods were compared. Data were analyzed with the Mann-Whitney test (statistical significance set at P≤0.05). Of the 51 telescoping rods, 17 constructs (33%) bent. The average interval between surgery and rod bending was 4.0 years (range, 0.9 to 8.2 y). Before bending, 11 of 17 telescoping rods had routine follow-up radiographs for review. In 10 of the rods, bending was present when early signs of rod failure were first detected. Rod bending did not seem to be related to rod size. There was no area on the rod itself that seemed more susceptible to bending. Rod bending can be an early sign of impending rod failure. When rod bending is first noted, it may predispose the rod to other subsequent failures such as loss of proximal and distal fixation and cut out. Rod bending should be viewed as an indicator for closer monitoring of the patient and discussions regarding future need for rod exchange. Level III-retrospective review.

  16. Modified method for registration of particle deflection by bent crystal

    International Nuclear Information System (INIS)

    Afanas'ev, S.V.; Kovalenko, A.D.; Kuznetsov, V.N.; Romanov, S.V.; Sajfulin, Sh.Z.; Taratin, A.M.; Volkov, V.I.; Voevodin, M.A.; Bojko, V.V.

    2003-01-01

    The modified method for registration of particle deflection by a bent crystal was proposed and studied at the external proton beam of the Nuclotron. The telescope of scintillation counters was placed at the angle that was smaller than a crystal bending angle. The count dependence of the telescope on the crystal orientation was formed by the particles, which passed in channeling states only some part of the crystal length. Two maximums were observed in the dependencies due to particles captured into the channeling states on the crystal surface and in the crystal volume. This allows one to obtain, using the telescope and high-intensity beams, useful data about the particle channeling and the crystal, which usually demands more complicated registration by means of the coordinate detectors

  17. Dynamic relaxation method in analysis of reinforced concrete bent elements

    Directory of Open Access Journals (Sweden)

    Anna Szcześniak

    2015-12-01

    Full Text Available The paper presents a method for the analysis of nonlinear behaviour of reinforced concrete bent elements subjected to short-term static load. The considerations in the range of modelling of deformation processes of reinforced concrete element were carried out. The method of structure effort analysis was developed using the finite difference method. The Dynamic Relaxation Method, which — after introduction of critical damping — allows for description of the static behaviour of a structural element, was used to solve the system of nonlinear equilibrium equations. In order to increase the method effectiveness in the range of the post-critical analysis, the Arc Length Parameter on the equilibrium path was introduced into the computational procedure.[b]Keywords[/b]: reinforced concrete elements, physical nonlinearity, geometrical nonlinearity, dynamic relaxation method, arc-length method

  18. EcoRV catalysis with a pre-bent substrate

    Science.gov (United States)

    Sanchez, Daniel S.; Zocchi, Giovanni

    2015-05-01

    Enzymes are deformable molecules which often adapt their conformation to the substrate's geometry. In the case of restriction enzymes acting on DNA, the substrate (DNA) is deformable also. While it is well established that external mechanical stress exerted on an enzyme modulates the enzymatic activity, the effect of mechanically stressing the substrate is less explored. Here we present the restriction enzyme EcoRV with a series of pre-bent DNA substrates and observe modulation of the overall speed of the enzymatic reaction by up to a factor 50. While in all cases the reaction is slowed down compared to the unstressed substrate, we observe peaks in the reaction rate as we vary the state of stress of the DNA substrate. Both bending moments and torsional moments on the DNA substrate affect the reaction rate.

  19. Dynamical focusing by bent, asymmetrically cut perfect crystals in Laue geometry.

    Science.gov (United States)

    Guigay, J P; Ferrero, C

    2016-07-01

    A semi-analytical approach based on the influence functions of a point source located on the crystal surface has been adopted to show that the focusing ability of cylindrically bent Laue crystals may be strongly enhanced by replacing symmetrically cut crystals with asymmetrically cut crystals. This approach is generally applicable to any distance between the X-ray source and the focusing bent crystal. A mathematically straightforward method to simplify the derivation of the already known expression of the influence functions in the case of deformed crystals with a constant strain gradient (e.g. cylindrically bent crystals) is also presented.

  20. Interpretation of bent-crystal rocking curves using phase-space diagrams

    CERN Document Server

    Ren, B; Chapman, L D; Wu, X Y; Zhong, Z; Ivanov, I; Huang, X

    2000-01-01

    In developing a double bent-Laue crystal monochromator for synchrotron-based monochromatic computed tomography system, we applied a special projection of the phase-space diagram to interpret the shape of bent crystal rocking curves. Unlike the rigorous approach of the ray-tracing method, this graphical method provides direct pictures that allow checks of the physical significance of the shapes of the rocking curves, thereby providing quick guidelines for matching two bent crystals. The method's usefulness is demonstrated with our crexperimental results, and its limitations are discussed.

  1. Evaluation of bent caps in reinforced concrete deck girder bridges : part 2.

    Science.gov (United States)

    2008-09-01

    This report describes research conducted to enable evaluation of existing vintage bent cap beams in reinforced concrete : deck girder bridges. The report is organized into two parts: 1) flexural anchorage capacity response and prediction of : reduced...

  2. Evaluation of bent caps in reinforced concrete deck girder bridges : part 1.

    Science.gov (United States)

    2008-09-01

    This report describes research conducted to enable evaluation of existing vintage bent cap beams in reinforced concrete : deck girder bridges. The report is organized into two parts: 1) flexural anchorage capacity response and prediction of : reduced...

  3. Behavior of Pile to Bent Cap Connections Subjected to Seismic Forces

    Science.gov (United States)

    2012-06-01

    Currently the South Carolina Department of Transportation employs a detail of a plain pile embedment for the : connection between precast prestressed piles and cast-in-place bent caps. This connection has proved beneficial in terms : of time and cost...

  4. Seismic performance of an I-girder to inverted-T bent cap connection.

    Science.gov (United States)

    2011-09-01

    This report presents the research conducted as part of an investigation for the California Department of Transportation (Caltrans) regarding the seismic response and overall moment capacity of precast I-girder to inverted-T bent cap bridge connection...

  5. Precast, Prestressed Concrete Bent Caps : Volume 1, Preliminary Design Considerations and Experimental Test Program

    Science.gov (United States)

    2018-04-01

    Precast prestressed concrete bent caps may provide significant benefits by enabling accelerated construction of bridge substructures and improve longevity by reducing the propensity for cracking. The Texas Department of Transportation enables the use...

  6. Microfocusing of soft X-ray undulator light using an elliptically bent cylinder mirror

    CERN Document Server

    Miura, S; Mashima, K; Miyaji, A; Ishiguro, E; Ohashi, H; Tamenori, Y; Okumura, H; Kanashima, T; Ishikawa, T

    2001-01-01

    The performance of an elliptically bent cylinder mirror, installed in A-branch of the Soft X-ray photochemistry beamline (BL27SU) at the SPring-8, is described. The aim of this branch beamline is to provide a micro white-beam focusing for a need in photochemistry community. This elastically bent mirror is the key component for the extremely intense micro-beam focusing optics.

  7. Photoelastic investigation of the stresses in mitred bent-cylinders under bending, 2

    International Nuclear Information System (INIS)

    Sawa, Yoshiaki

    1984-01-01

    The states of stress distribution in mitred bend subjected to inplane uniform bending moment have been studied systematically by means of photoelastic stress freezing method. The relations between the stress concentration factor of fiber stress σsub(l) and of hoop stress σsub(theta) near the bent part and the angle of mitred bend are thoroughly investigated. The effects of fillet radius of the bent-part and wall thickness on the stress concentration factors are also discussed. (author)

  8. Dechanneling of relativistic protons and nuclei in straight and bent crystals. Rechanneling role

    International Nuclear Information System (INIS)

    Taratin, A.M.

    1997-01-01

    Planar dechanneling of relativistic protons and Pb nuclei with the same momentum per unit charge p z in straight and bent crystals was investigated by simulation. It was shown that the different probability of the recapture into the channeling regime for protons and Pb nuclei infringes the dechanneling length invariance with respect to p z in the straight crystals, whereas in the bent crystals the approximate invariance occurs

  9. On Weak and Strong 2k- bent Boolean Functions

    Science.gov (United States)

    2016-01-01

    s8 (u) + β2Wf⊕ s8 (ū) + β3Wf⊕s2⊕ s8 (u) + β4Wf⊕s2⊕ s8 (ū) + β5Wf⊕s4⊕ s8 (u) + β6Wf⊕s4⊕ s8 (ū...β7Wf⊕s2⊕s4⊕ s8 (u) + β8Wf⊕s2⊕s4⊕ s8 (ū), where β1 = 1 + ζ + ζ2 + ζ3 + ζ4 + ζ5 + ζ6 + ζ7, β2 = 1− ζ + ζ2 − ζ3 + ζ4 − ζ5 + ζ6 − ζ7, β3 = 1 + ζ − ζ2 − ζ3...n odd hold, where: (i) f⊕ s8 is bent-negabent-octabent with the conditions that (Wf⊕ s8 (u), Wf⊕ s8 (ū), Wf⊕s2⊕ s8 (u), Wf⊕s2⊕ s8 (ū), Wf⊕s4⊕ s8 (u), Wf⊕s4⊕ s8

  10. Nematic biaxiality in a bent-core material

    Science.gov (United States)

    Yoon, Hyung Guen; Kang, Shin-Woong; Dong, Ronald Y.; Marini, Alberto; Suresh, Kattera A.; Srinivasarao, Mohan; Kumar, Satyendra

    2010-05-01

    The results of a recent investigation of the nematic biaxiality in a bent-core mesogen (A131) are in apparent disagreement with earlier claims. Samples of mesogen A131 used in the two studies were investigated with polarized optical microscopy, conoscopy, carbon-13 NMR, and crossover frequency measurements. The results demonstrate that textural changes associated with the growth of biaxial nematic order appear at ˜149°C . The Maltese cross observed in the conoscopic figure gradually splits into two isogyres at lower temperatures indicating phase biaxiality. Presence of the uniaxial to biaxial nematic phase transition is further confirmed by temperature trends of local order parameters based on C13 chemical shifts in NMR experiments. Frequency switching measurements also clearly reveal a transition at 149°C . Differences between the two reports appear to be related to the presence of solvent, impurities, and/or adsorbed gases in samples of A131 used in the study of Van Le [Phys. Rev. E 79, 030701 (2009)].

  11. Elliptically Bent X-Ray Mirrors with Active Temperature Stabilization

    International Nuclear Information System (INIS)

    Yuan, S.; Church, M.; Yashchuk, V.V.; Celestre, R.S.; McKinney, W.R.; Morrison, G.; Warwick, T.; Padmore, H.A.; Goldberg, K.A.; Kirschman, J.; Noll, T.

    2010-01-01

    We present details of design of elliptically bent Kirkpatrick-Baez mirrors developed and successfully used at the advanced light source for submicron focusing. A distinctive feature of the mirror design is an active temperature stabilization based on a Peltier element attached directly to the mirror body. The design and materials have been carefully optimized to provide high heat conductance between the mirror body and substrate. We describe the experimental procedures used when assembling and precisely shaping the mirrors, with special attention paid to laboratory testing of the mirror-temperature stabilization. For this purpose, the temperature dependence of the surface slope profile of a specially fabricated test mirror placed inside a temperature-controlled container was measured. We demonstrate that with active mirror-temperature stabilization, a change of the surrounding temperature by more than 3 K does not noticeably affect the mirror figure. Without temperature stabilization, the rms slope error is changed by approximately 1.5 μrad (primarily defocus) under the same conditions

  12. Piezoelectric properties of polymers containing bent-shape liquid crystal molecules

    Science.gov (United States)

    Diorio, N.; Varga, M.; Carif, A.; Puskas, J. E.; Fodor-Csorba, K.; Sprunt, S.; Gleeson, J. T.; Jakli, A.

    2013-03-01

    Recently, bent-core liquid crystal elastomers have shown to exhibit large values of flexoelectricity as many as 3 orders of magnitude larger than liquid crystal elastomers containing rod-shaped molecules. These unusual high responses are attributed to have piezoelectric origin. Motivated by this, in this study, two bent-core liquid crystals were used to make various types of materials; low molecular weight bent-core nematic fluid, side chain bent-core liquid crystal polymer, low molecular liquid crystal dispersed in a polyisobutylene-based thermoplastic elastomer, and side-chain bent-core elastomers. Liquid crystal elastomers combine elasticity and flexibility inherent to rubbers and the optical and electrical properties of liquid crystals, and are promising materials for applications such as electro-optics, flexible electronics and actuator technologies for biomedical applications. Most conventional liquid crystal elastomers have rod-shaped liquid crystal molecules chemically attached to a crosslinked polymer network. Converse piezoelectric responses were measured by a Mirau interferometer and the direct piezoelectric signals were studied by home-made device where the stress is provided by an audio speaker. The results will be analyzed in terms of ferroelectric clusters of the materials in the nematic phase and will be compared with other piezoelectric materials. Supported by Grants NSF-DMR -0964765 and NSF-DMR -0804878.

  13. Deformation mechanisms of bent Si nanowires governed by the sign and magnitude of strain

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lihua, E-mail: wlh@bjut.edu.cn, E-mail: xdhan@bjut.edu.cn, E-mail: j.zou@uq.edu.au [Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Materials Engineering, The University of Queensland, Brisbane, QLD 4072 (Australia); Kong, Deli; Xin, Tianjiao; Shu, Xinyu; Zheng, Kun; Xiao, Lirong; Sha, Xuechao; Lu, Yan; Han, Xiaodong, E-mail: wlh@bjut.edu.cn, E-mail: xdhan@bjut.edu.cn, E-mail: j.zou@uq.edu.au [Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Zhang, Ze [Department of Materials Science, Zhejiang University, Hangzhou 310008 (China); Zou, Jin, E-mail: wlh@bjut.edu.cn, E-mail: xdhan@bjut.edu.cn, E-mail: j.zou@uq.edu.au [Materials Engineering, The University of Queensland, Brisbane, QLD 4072 (Australia); Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, QLD 4072 (Australia)

    2016-04-11

    In this study, the deformation mechanisms of bent Si nanowires are investigated at the atomic scale with bending strain up to 12.8%. The sign and magnitude of the applied strain are found to govern their deformation mechanisms, in which the dislocation types (full or partial dislocations) can be affected by the sign (tensile or compressive) and magnitude of the applied strain. In the early stages of bending, plastic deformation is controlled by 60° full dislocations. As the bending increases, Lomer dislocations can be frequently observed. When the strain increases to a significant level, 90° partial dislocations induced from the tensile surfaces of the bent nanowires are observed. This study provides a deeper understanding of the effect of the sign and magnitude of the bending strain on the deformation mechanisms in bent Si nanowires.

  14. Spectral tuning of a locally bent microfiber taper interferometer with a nanosized liquid crystal overlay.

    Science.gov (United States)

    Luo, Haimei; Wang, Changjing; Ji, Yinghua; Yuan, Wen; Zhang, Guoping; Wang, Yifan; Hong, Zehua; Wang, Xianping

    2016-09-10

    In this paper, the tuning characteristics of locally bent microfiber taper covered with a nanosized high-refractive-index liquid crystal (LC) layer under different temperatures and electric field intensities have been theoretically analyzed and experimentally investigated. A locally bent microfiber taper interferometer with a waist diameter of ∼3.72  μm is fabricated by using the flame brushing technique, followed by bending the transition region of the taper to form a modal interferometer and later by placing a ∼200  nm LC layer over the uniform taper waist region. Experimental results indicate that a high-efficiency thermal or electric tuning of an LC-coated locally bent microfiber taper interferometer could be achieved. This suggests a potential application of this device as tunable all-fiber photonic devices, such as filters, modulators, and sensing elements.

  15. Bent silica nanosheets directed from crystalline templates controlled by proton donors

    International Nuclear Information System (INIS)

    Matsukizono, Hiroyuki; Jin, Ren-Hua

    2011-01-01

    Linear poly(ethyleneimine) (LPEI) is easily crystallizable with the formation of various morphologies in the aqueous medium when its hot solution cooled down to room temperature. Herein, we prepared a series of crystalline precipitates of LPEI grown in the presence of proton donating compounds such as Tris–HCl, tartaric acid, amino acids, and used the precipitates in directing silica deposition. Since the proton donating compounds can mediate the pH with donating the proton to LPEI, the crystallization of LPEI evidently depended on the concentrations of the proton donating compounds. It was found that the precipitates grown in the conditions of the pH ranged 8.2–8.5 directed well-controlled bent nanosheet of silica/LPEI composites. The bent nanosheet is constructed by multi-layered structures with a little slippage between layers. The bent nanosheet silica has slit-like pore with ca. 10 nm width.

  16. Application of spherically bent crystals spectrometer to X-ray diagnosis

    International Nuclear Information System (INIS)

    Liu Lifeng; Xiao Shali; Wang Hongjian; Shi Jun; Qian Jiayu; Liu Shenye; Wei Minxi; Chen Bolun

    2010-01-01

    In order to diagnose X-ray emitted from the plasma, a spherically bent crystals spectrometer was developed based on the X-ray Bragg diffraction theory. In the experiment, the dispersive element of crystal analyzer was quartz, the bent radius was 250 mm and the range of Bragg angle of the crystal was 30 degree to 67.5 degree. The X-ray film, as its principal detector, obtained spectra information which had an effective area of 10 mm x 50 mm. The experiment was carried out at the anode accelerator. The detector obtained the X-ray spectra information of the K-shell Ti spectra. By the analysis of spectra information, the spectral resolution of spherically bent quartz crystals can be achieved for more than 1000, and the spectral passband is 0.43 eV. (authors)

  17. A bent Laue-Laue monochromator for a synchrotron-based computed tomography system

    International Nuclear Information System (INIS)

    Ren, B.; Dilmanian, F.A.; Chapman, L.D.; Ivanov, I.; Wu, X.Y.; Zhong, Z.; Huang, X.

    1999-01-01

    We designed and tested a two-crystal bent Laue-Laue monochromator for wide, fan-shaped synchrotron X-ray beams for the program multiple energy computed tomography (MECT) at the National Synchrotron Light Source (NSLS). MECT employs monochromatic X-ray beams from the NSLS's X17B superconducting wiggler beamline for computed tomography (CT) with an improved image quality. MECT uses a fixed horizontal fan-shaped beam with the subject's apparatus rotating around a vertical axis. The new monochromator uses two Czochralski-grown Si crystals, 0.7 and 1.4 mm thick, respectively, and with thick ribs on their upper and lower ends. The crystals are bent cylindrically, with the axis of the cylinder parallel to the fan beam, using 4-rod benders with two fixed rods and two movable ones. The bent-crystal feature of the monochromator resolved the difficulties we had had with the flat Laue-Laue design previously used in MECT, which included (a) inadequate beam intensity, (b) excessive fluctuations in beam intensity, and (c) instability of the shape of the beam's horizontal profile. Compared with that earlier monochromator, the bent Laue-Laue device tested at 42 and 108 keV showed about a 10-fold larger beam flux, about 5 times better beam stability, 10-fold less harmonic contamination, and a smaller energy bandwidth at certain bending radii. The present work gave us better understanding of the basis for the beam-smiling effect in bent-crystal monochromators, and allowed us to refine the theoretical method of estimating the beam-harmonic contamination in bent-crystal monochromators

  18. Energy funneling in a bent chain of Morse oscillators with long-range coupling

    DEFF Research Database (Denmark)

    Larsen, Peter Ulrik Vingaard; Christiansen, Peter Leth; Bang, Ole

    2004-01-01

    A bent chain of coupled Morse oscillators with long-range dispersive interaction is considered. Moving localized excitations may be trapped in the bending region. Thus chain geometry acts like an impurity. An energy funneling effect is observed in the case of random initial conditions.......A bent chain of coupled Morse oscillators with long-range dispersive interaction is considered. Moving localized excitations may be trapped in the bending region. Thus chain geometry acts like an impurity. An energy funneling effect is observed in the case of random initial conditions....

  19. CO2 laser ablation of bent optical fibers for sensing applications

    International Nuclear Information System (INIS)

    Lévesque, L; Jdanov, V

    2011-01-01

    A procedure for the fabrication of a fiber optic sensor involving CO 2 laser ablation at λ = 10.6 µm is proposed. A basic system to achieve optical fiber bending and material processing on a single mode optical fiber is described and it is demonstrated that an optical fiber can be bent at a very precise angle by focusing a CO 2 beam locally near the glass cladding surface until it reaches melting temperature. A method is also described for removing material at the apex of a bent fiber to obtain a smooth and well flattened plane surface that is suitable for optical fiber sensing

  20. Possibility of high efficient beam extraction from the CERN SPS with a bent crystal. Simulation results

    Energy Technology Data Exchange (ETDEWEB)

    Scandale, W. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Laboratoire de l' AccelerateurLineaire (LAL), Universite Paris SudOrsay, Orsay (France); INFN Sezione di Roma, Piazzale Aldo Moro 2, 00185 Rome (Italy); Kovalenko, A.D.; Taratin, A.M. [Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation)

    2017-03-11

    The extraction of the SPS beam of 270 GeV/c protons assisted by a bent crystal was studied by simulation. Two methods for delivering the SPS beam onto a crystal were considered: transverse diffusion and orbit bump of the beam. It was shown that the main condition for high efficient beam extraction with a bent crystal, which is a small divergence of the incident beam, can be fulfilled. Extraction efficiency up to 99% can be reached for both methods of the beam delivering. The irradiation of the electrostatic septum wires during the beam extraction can be considerably reduced.

  1. Fra rød stue til åbent plan

    DEFF Research Database (Denmark)

    Linde-Bech, Thomas Vestergaard; Hamilton, Stine Del Pin

    2017-01-01

    Indretning i åbent plan i moderne børnehaver påvirker børnenes leg, da de er præget af konstant tilgængelighed og forsøg på afgrænsning.......Indretning i åbent plan i moderne børnehaver påvirker børnenes leg, da de er præget af konstant tilgængelighed og forsøg på afgrænsning....

  2. Dual Symmetry in Bent-Core Liquid Crystals and Unconventional Superconductors

    Directory of Open Access Journals (Sweden)

    Vladimir Lorman

    2010-01-01

    Full Text Available We extend the Landau theory of bent-core mesophases and d-wave high-Tc superconductors by considering additional secondary pseudo-proper order parameters. These systems exhibit a remarkable analogy relating their symmetry groups, lists of phases, and an infinite set of physical tensors. This analogy lies upon an internal dual structure shared by the two theories. We study the dual operator transforming rotations into translations in liquid crystals, and gauge symmetries into rotations in superconductors. It is used to classify the bent-core line defects, and to analyze the electronic gap structure of lamellar d-wave superfluids.

  3. Deflection of high energy channeled charged particles by elastically bent silicon single crystals

    International Nuclear Information System (INIS)

    Gibson, W.M.; Kim, I.J.; Pisharodoy, M.; Salman, S.M.; Sun, C.R.; Wang, G.H.; Wijayawardana, R.; Forster, J.S.; Mitchell, I.V.; Baker, S.I.; Carrigan, R.A. Jr.; Toohig, T.E.; Avdeichikov, V.V.; Ellison, J.A.; Siffert, P.

    1984-01-01

    An experiment has been carried out to observe the deflection of charged particles by planar channeling in bent single crystals of silicon for protons with energy up to 180 GeV. Anomolous loss of particles from the center point of a three point bending apparatus was observed at high incident particle energy. This effect has been exploited to fashion a 'dechanneling spectrometer' to study dechanneling effects due to centripital displacement of channeled particle trajectories in a bent crystal. The bending losses generally conform to the predictions of calculations based on a classical model. (orig.)

  4. Bent crystal X-ray optics for the diagnosis and applications of laser-produced plasmas

    International Nuclear Information System (INIS)

    Loetzsch, Robert

    2012-01-01

    The present thesis discussed several aspects of X-ray optics based on bent crystals and a number of applications of these optics. First, a deeper insight into the reflection properties of elastically bent perfect crystal optics was gained by the consideration of all deformation effects. It was shown that the reflection properties depend on the lateral position on the crystal, an effect that was not addressed before, neither experimentally nor theoretically. To investigate this effect, an apparatus for the measurement of Bragg angles of bent crystals with high angular resolution was built. It was measured that the lattice plane distances of two-dimensionally bent crystals vary laterally by up to 10 -4 . This effect has to be considered in high resolution X-ray spectroscopy and imaging with these bent crystals. It can explain discrepancies in theoretical and experimental spectrometer resolution with spherically bent crystals. Besides these principal investigations, in this thesis a number of X-ray optics were presented that demonstrate the application potential of bent crystal optics. This includes two optics that are used in the field of applications of laser-produced plasmas as high repeating hard X-ray sources. It was shown that an X-ray spectrometer based on full cylinder rings of highly oriented pyrolytic graphite is capable to record the rather weak single shot pulses from a high repeating 1 er-plasma X-ray source. This is possible due to the high collection efficiency of the instrument of up to 5.10 -4 . Furthermore, X-ray optics based on toroidally bent crystals that make it possible to spectrally select a bandwidth of ∝1 eV and focus the ultrashort X-ray pulses from such a laser-plasma source, were designed, prepared and characterized. It was shown that these bent crystals provide the calculated integrated reflectivity, the predicted bandwidth and focus to spot sizes smaller than 60 μm. A novel application of toroidally bent crystals was pointed out: a

  5. Suppression of surface effect by using bent-perfect-crystal monochromator in residual strain scanning

    Czech Academy of Sciences Publication Activity Database

    Vrána, Miroslav; Mikula, Pavol

    490/491, - (2005), s. 234-238 ISSN 0255-5476 R&D Projects: GA ČR GA202/03/0891; GA AV ČR KSK1010104 Institutional research plan: CEZ:AV0Z1048901 Keywords : neutron diffraction * residual strain scanning * bent monochromator Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.399, year: 2005

  6. 3-Hydroxycinnamic acid - a new central core for the design of bent-shaped liquid crystals

    Czech Academy of Sciences Publication Activity Database

    Kohout, M.; Tůma, J.; Svoboda, J.; Novotná, Vladimíra; Gorecka, E.; Pociecha, D.

    2013-01-01

    Roč. 1, č. 32 (2013), s. 4962-4969 ISSN 2050-7526 R&D Projects: GA ČR GA13-14133S; GA ČR(CZ) GAP204/11/0723 Institutional support: RVO:68378271 Keywords : liquid crystals * bent-shaped mesogen * cinnamic acid Subject RIV: JJ - Other Materials

  7. Evaluation of a timber column bent substructure after more than 60 years in-service

    Science.gov (United States)

    James P. Wacker; Xiping Wang; Douglas R. Rammer; William J. Nelson

    2011-01-01

    This paper describes both the field evaluation and laboratory testing of two timber-column-bent bridge substructures. These substructures served as intermediate pier supports for the East Deer Park Drive Bridge located in Gaithersburg, Maryland. A field evaluation of the bridge substructure was conducted in September 2008. Nondestructive testing was performed with a...

  8. Bent crystals in Laue geometry: dynamical focusing of a polychromatic incident beam

    Czech Academy of Sciences Publication Activity Database

    Mocella, V.; Guigay, J. P.; Hrdý, Jaromír; Ferrero, C.; Hoszowska, J.

    2004-01-01

    Roč. 37, - (2004), s. 941-946 ISSN 0021-8898 Institutional research plan: CEZ:AV0Z1010921 Keywords : polychromatic focusing * bent Laue crystals * dynamical diffraction * optics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.534, year: 2004

  9. Steering of sub-GeV electrons by ultrashort Si and Ge bent crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sytov, A.I. [Ferrara Univ. (Italy). Dipt. di Fisica e Scienze della Terra; Belarusian State Univ., Minsk (Belarus). Inst. for Nuclear Problems; INFN Sezione di Ferrara (Italy); Bandiera, L.; Mazzolari, A.; Bagli, E.; Germogli, G.; Guidi, V.; Romagnoni, M. [Ferrara Univ. (Italy). Dipt. di Fisica e Scienze della Terra; INFN Sezione di Ferrara (Italy); De Salvador, D.; Carturan, S.; Maggioni, G. [INFN, Laboratori Nazionali di Legnaro (Italy); Padova Univ. (Italy). Dipt. di Fisica; Berra, A.; Prest, M. [Univ. dell' Insubria, Como (Italy); INFN, Sezione di Milano Bicocca, Milan (Italy); Durighello, C. [Ferrara Univ. (Italy). Dipt. di Fisica e Scienze della Terra; INFN, Laboratori Nazionali di Legnaro (Italy); Padova Univ. (Italy). Dipt. di Fisica; INFN Sezione di Ferrara (Italy); Klag, P.; Lauth, W. [Mainz Univ. (Germany). Inst. fuer Kernphysik; Tikhomirov, V.V. [Belarusian State Univ., Minsk (Belarus). Inst. for Nuclear Problems; Vallazza, E. [INFN, Sezione di Trieste (Italy)

    2017-12-15

    We report the observation of the steering of 855 MeV electrons by bent silicon and germanium crystals at the MAinzer MIkrotron. Crystals with 15 μm of length, bent along (111) planes, were exploited to investigate orientational coherent effects. By using a piezo-actuated mechanical holder, which allowed to remotely change the crystal curvature, it was possible to study the steering capability of planar channeling and volume reflection vs. the curvature radius and the atomic number, Z. For silicon, the channeling efficiency exceeds 35%, a record for negatively charged particles. This was possible due to the realization of a crystal with a thickness of the order of the dechanneling length. On the other hand, for germanium the efficiency is slightly below 10% due to the stronger contribution of multiple scattering for a higher-Z material. Nevertheless this is the first evidence of negative beam steering by planar channeling in a Ge crystal. Having determined for the first time the dechanneling length, one may design a Ge crystal based on such knowledge providing nearly the same channeling efficiency of silicon. The presented results are relevant for crystal-based beam manipulation as well as for the generation of e.m. radiation in bent and periodically bent crystals. (orig.)

  10. Bent-shaped liquid crystals based on 4-substituted 3-hydroxybenzoic acid central core

    Czech Academy of Sciences Publication Activity Database

    Kohout, M.; Kozmík, V.; Slabochová, M.; Tůma, J.; Svoboda, J.; Novotná, Vladimíra; Pociecha, D.

    2015-01-01

    Roč. 42, č. 1 (2015), s. 87-103 ISSN 0267-8292 R&D Projects: GA ČR GA13-14133S Institutional support: RVO:68378271 Keywords : liquid crystals * bent-shaped mesogens * hydroxybenzoic acid Subject RIV: JJ - Other Materials Impact factor: 2.244, year: 2015

  11. The elusive thermotropic biaxial nematic phase in rigid bent-core ...

    Indian Academy of Sciences (India)

    Abstract. The biaxial nematic liquid crystalline phase was predicted several decades ago. Several vigorous attempts to find it in various systems resulted in mis-identifications. The results of X-ray diffraction and optical texture studies of the phases exhibited by rigid bent-core molecules derived from 2 ...

  12. Steering of Sub-GeV electrons by ultrashort Si and Ge bent crystals

    Science.gov (United States)

    Sytov, A. I.; Bandiera, L.; De Salvador, D.; Mazzolari, A.; Bagli, E.; Berra, A.; Carturan, S.; Durighello, C.; Germogli, G.; Guidi, V.; Klag, P.; Lauth, W.; Maggioni, G.; Prest, M.; Romagnoni, M.; Tikhomirov, V. V.; Vallazza, E.

    2017-12-01

    We report the observation of the steering of 855 MeV electrons by bent silicon and germanium crystals at the MAinzer MIkrotron. Crystals with 15 μ m of length, bent along (111) planes, were exploited to investigate orientational coherent effects. By using a piezo-actuated mechanical holder, which allowed to remotely change the crystal curvature, it was possible to study the steering capability of planar channeling and volume reflection vs. the curvature radius and the atomic number, Z. For silicon, the channeling efficiency exceeds 35%, a record for negatively charged particles. This was possible due to the realization of a crystal with a thickness of the order of the dechanneling length. On the other hand, for germanium the efficiency is slightly below 10% due to the stronger contribution of multiple scattering for a higher-Z material. Nevertheless this is the first evidence of negative beam steering by planar channeling in a Ge crystal. Having determined for the first time the dechanneling length, one may design a Ge crystal based on such knowledge providing nearly the same channeling efficiency of silicon. The presented results are relevant for crystal-based beam manipulation as well as for the generation of e.m. radiation in bent and periodically bent crystals.

  13. Note on the glide of a bird with wings bent downwards

    NARCIS (Netherlands)

    Sparenberg, J. A.

    This note considers the influence of the bending down of the wings of a bird on the performance of its glide. The induced drag of bent wings is compared with the induced drag of a corresponding straight wing. Numerical results are given.

  14. Photosensitive bent-core liquid crystals based on methyl substituted 3-hydroxybenzoic acid.

    Czech Academy of Sciences Publication Activity Database

    Kohout, M.; Alaasar, M.; Poryvai, A.; Novotná, Vladimíra; Poppe, S.; Tschierske, C.; Svoboda, J.

    2017-01-01

    Roč. 7, č. 57 (2017), s. 35805-35813 ISSN 2046-2069 R&D Projects: GA ČR GA16-12150S Institutional support: RVO:68378271 Keywords : liquid crystals * photosensitivity * bent-core liquid crystals * 3-hydroxybenzoic acid Subject RIV: JJ - Other Materials OBOR OECD: Nano-materials (production and properties) Impact factor: 3.108, year: 2016

  15. Laterally substituted symmetric and nonsymmetric salicylideneimine-based bent-core mesogens

    Directory of Open Access Journals (Sweden)

    Sonja Findeisen-Tandel

    2012-01-01

    Full Text Available Bent-core mesogens have gained considerable importance due to their ability to form new mesophases with unusual properties. Relationships between the chemical structure of bent-core molecules and the type and physical properties of the formed mesophases are relatively unknown in detail and differ strongly from those known for calamitic liquid crystals. In this paper symmetric and nonsymmetric five-ring salicylideneaniline-based bent-core mesogens are presented, and the effect of lateral substituents attached at the outer phenyl rings (F, Cl, Br or the central phenyl ring (CH3 on the liquid-crystalline behaviour and on the physical properties is studied. Corresponding benzylideneaniline-based compounds were additionally prepared in order to study the influence of the intramolecular hydrogen bond. The occurring mesophases were investigated by differential scanning calorimetry, polarising microscopy, X-ray diffraction and dielectric and electro-optical measurements. The paper reports on new findings with respect to the structure–property relationships of bent-core mesogens. On one hand, the disruptive effect of laterally substituted halogen atoms, F, Cl and Br, on the mesophase behaviour of three isomeric series was much lower than expected. On the other hand, an increase of the clearing temperature by 34 K was observed, caused by small lateral substituents. The electro-optical behaviour, especially the type of polar switching and corresponding molecular movements, is sensitive to variations in the molecular structure.

  16. Coupling sections, emittance growth, and drift compensation in the use of bent solenoids as beam transport elements

    Directory of Open Access Journals (Sweden)

    J. Norem

    1999-05-01

    Full Text Available Bent solenoids can transmit charged particle beams while providing momentum dispersion. While less familiar than quadrupole and dipole systems, bent solenoids can produce superficially simple transport lines and large acceptance spectrometers for use at low energies. Design issues such as drift compensation and coupling sections between straight and bent solenoids are identified, and aberrations such as shears produced by perpendicular error fields are discussed. Examples are considered which provide the basis for the design of emittance exchange elements for the cooling system of a muon collider.

  17. A new family of four-ring bent-core nematic liquid crystals with highly polar transverse and end groups

    Directory of Open Access Journals (Sweden)

    Kalpana Upadhyaya

    2013-01-01

    Full Text Available Non-symmetrically substituted four-ring achiral bent-core compounds with polar substituents, i.e.., chloro in the bent or transverse direction in the central core and cyano in the lateral direction at one terminal end of the molecule, are designed and synthesized. These molecules possess an alkoxy chain attached at only one end of the bent-core molecule. The molecular structure characterization is consistent with data from elemental and spectroscopic analysis. The materials thermal behaviour and phase characterization have been investigated by differential scanning calorimetry and polarizing microscopy. All the compounds exhibit a wide-ranging monotropic nematic phase.

  18. An improved simulation routine for modelling coherent high-energy proton interactions with bent crystals

    CERN Document Server

    Forcher, Francesco; Redaelli, Stefano; Zanetti, Marco; CERN. Geneva. ATS Department

    2018-01-01

    The planes in crystalline solids can constrain the directions that charged particles take as they pass through. Physicists can use this "channelling" property of crystals to steer particle beams. In a bent crystal, for example, channelled particles follow the bend and can change their direction. Several studies are on-going at CERN to verify the possibility of using bent crystals as primary collimators in high energy hadron colliders like the LHC. Simulations have been developed to model the coherent interaction with crystalline planes. The goal of this note is to analyze the data collected on extracted beam from the SPS and develop an improved model to simulate the data’s subtleties, in particular the transition between the volume reflection and amorphous interactions of the beam with crystals.

  19. Using data mining to find bent-double radio galaxies in the FIRST survey

    Science.gov (United States)

    Kamath, Chandrika; Cantu-Paz, Erick; Fodor, Imola K.; Tang, Nu A.

    2001-11-01

    In this paper, we describe the use of data mining techniques to search for radio-emitting galaxies with a bent-double morphology. In the past, astronomers from the FIRST (Faint Images of the Radio Sky at Twenty-cm) survey identified these galaxies through visual inspection. This was not only subjective but also tedious as the on-going survey now covers 8000 square degrees, with each square degree containing about 90 galaxies. In this paper, we describe how data mining can be used to automate the identification of these galaxies. We discuss the challenges faced in defining meaningful features that represent the shape of a galaxy and our experiences with ensembles of decision trees for the classification of bent-double galaxies.

  20. An improved simulation routine for modelling coherent high-energy proton interactions with bent crystals

    CERN Document Server

    AUTHOR|(CDS)2210072; Mirarchi, Daniele; Redaelli, Stefano

    The planes in crystalline solids can constrain the directions that charged particles take as they pass through. Physicists can use this "channelling" property of crystals to steer particle beams. In a bent crystal, for example, channelled particles follow the bend and can change their direction. Experiments are being carried out to study in detail this phenomenon. The UA9 collaboration is using high energy protons and heavy ions beams from the SPS accelerator at CERN to verify the possibility of using bent crystals as primary collimators in high energy hadron colliders like the LHC. Simulations have been developed to model the coherent interaction with crystal planes. The goal of the thesis is indeed to analyze the data and develop an improved simulation routine to better describe the data’s subtleties, in particular the transition between the volume reflection and amorphous modes of beam interaction with the crystal.

  1. [The bent spine syndrome: a focal axial myopathy of late onset].

    Science.gov (United States)

    Redondo, L; Polo, M A; Rodríguez, F; Aguirre, J; Sánchez, A; Chinchón, I; Bautista, J

    1999-10-01

    The bent spine is a rare syndrome appearing at an advanced age which shows a posture of anterior flexion of the trunk, which is reducible and is often hereditary. It is caused by a paresia of the extensor musculature of the trunk by a focal axial myopathy of late onset. We herein describe the case of a 72-year-old woman with a progressive bent spine initiated at the age of 55. Family questioning showed vertical transmission of the process. On exploration paresis of the paravertebral musculature and to a lesser extent of both girdles was observed. Serum CK levels were normal. Vertebral CT showed atrophy with fatty substitution of the paravertebral musculature. EMG of the scapular and paravertebral muscles demonstrated a myopathic pattern. Deltoid muscle biopsy found atrophy of type II fibers and isolated broken red fibers. This case corroborates the myopathic nature of this syndrome. A review of the nosology of the syndrome is also presented.

  2. Time-of-flight neutron Bragg-edge transmission imaging of microstructures in bent steel plates

    International Nuclear Information System (INIS)

    Su, Yuhua; Oikawa, Kenichi; Harjo, Stefanus; Shinohara, Takenao; Kai, Tetsuya; Harada, Masahide; Hiroi, Kosuke; Zhang, Shuoyuan; Parker, Joseph Don; Sato, Hirotaka; Shiota, Yoshinori; Kiyanagi, Yoshiaki; Tomota, Yo

    2016-01-01

    Neutron Bragg-edge transmission imaging makes it possible to quantitatively visualize the two-dimensional distribution of microstructure within a sample. In order to examine its application to engineering products, time-of-flight Bragg-edge transmission imaging experiments using a pulsed neutron source were performed for plastically bent plates composed of a ferritic steel and a duplex stainless steel. The non-homogeneous microstructure distributions, such as texture, crystalline size, phase volume fraction and residual elastic strain, were evaluated for the cross sections of the bent plates. The obtained results were compared with those by neutron diffraction and electron back scatter diffraction, showing that the Bragg-edge transmission imaging is powerful for engineering use.

  3. Development of residual stress measurement apparatus by neutron diffraction and its application to bent carbon steel

    International Nuclear Information System (INIS)

    Hayashi, Makoto; Ohkido, Shinobu; Minakawa, Nobuaki; Morii, Yukio

    1998-01-01

    To establish the measuring technique of neutron diffraction for the internal residual stress distribution in a structural component, a neutron diffraction apparatus was designed and manufactured in Modified Japan Research Reactor 3 (JRR3M). At the first step of measurement, a basic characteristics of the diffractometer was evaluated. The incident neutron beam flux was 10 4 n/cm 2 /sec and the Full Width at Half Maximum (FWHM) was about 0.3 degree. This indicates that the manufactured neutron diffractometer is capable for the residual stress measurement. As the first application of the neutron diffraction measurement, the residual stress distribution in plastically bent carbon steel plate was measured. A typical compressive-tensile-compressive-tensile residual stress pattern in the tangential direction in the bent plane was confirmed. The maximum stress near the surface was about 180 MPa. This means that the technique for residual stress measurement by neutron diffraction can be established in Japan. (author)

  4. Effect of flexoelectricity on electrostatic potential in a bent piezoelectric nanowire

    International Nuclear Information System (INIS)

    Liu, Chenchen; Hu, Shuling; Shen, Shengping

    2012-01-01

    Flexoelectricity presents a strong size effect, and should not be ignored for nanodevices. By taking the flexoelectricity into account, an analytical solution is deduced for the piezoelectric potential generated in a bent ZnO nanowire (NW) cantilever. It is shown that the electric potential in the NW is not independent of z-coordinate, which is different from the results based on the classical piezoelectric theory. The results also show that the effect of flexoelectricity on the voltage is significant in a bent ZnO NW even though the flexoelectric coefficients are set to be the minimum. Moreover, we find that the flexoelectricity plays an important role in filling the gap between the results from the classical piezoelectric theory and experimental results. It is indicated that one can use the flexoelectricity to modify the transfer efficiency from mechanical energy to electrical energy through strain engineering. (paper)

  5. Determining the diffraction properties of a cylindrically bent KAP(001) crystal from 1 to 5 keV

    Energy Technology Data Exchange (ETDEWEB)

    Haugh, Michael [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Lee, Joshua [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Jacoby, Kenneth [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Christensen, C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Loisel, G. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States), Livermore Operations

    2015-08-31

    Various crystals are used for the dispersive component of X-ray spectrometers. The crystals are usually bent to meet the desired measurement needs, such as focusing. The bending can change the crystal diffraction properties, thus altering the spectrometer throughput and resolving power. This work concerns measuring the diffraction properties of a potassium acid phthalate (001) [KAP(001)] crystal bent into a circular cylinder segment. The measurement methods using a diode source and a synchrotron source are described. The multi-lamellar model for calculating the diffraction properties of a bent crystal is described. The measurement results are compared to the multi-lamellar model and show qualitative agreement. The measurements show how to make the multi-lamellar calculations a useful estimate. A method is given to make useful estimates of the diffraction properties of the KAP(001) crystal bent into a circular cylinder segment.

  6. A precast concrete bridge bent designed to re-center after an earthquake : research report, October 2008.

    Science.gov (United States)

    2008-10-01

    In this study the post-earthquake residual displacements of reinforced concrete bridge bents were investigated. The system had mild steel that was intended to dissipate energy and an unbonded, post-tensioned tendon that was supposed to remain elastic...

  7. A precast concrete bridge bent designed to re-center after an earthquake : draft research report, August 2008.

    Science.gov (United States)

    2008-08-01

    In this study the post-earthquake residual displacements of reinforced concrete bridge bents were investigated. The system had mild steel that was intended to dissipate energy and an unbonded, post-tensioned tendon that was supposed to remain elastic...

  8. The signs B and B-bent in Israeli sign language according to the theory of Phonology as Human Behavior.

    Science.gov (United States)

    Fuks, Orit; Tobin, Yishai

    2008-01-01

    The purpose of the present research is to examine which of the two factors: (1) the iconic-semiotic factor; or (2) the human-phonetic factor is more relevant in explaining the appearance and distribution of the hand shape B-bent in Israeli Sign Language (ISL). The B-bent shape has been the subject of much attention in sign language research revolving around the question of its status as a phoneme. The arguments supporting the phonemic status of the B-bent hand shape have been primarily based on the semiotic opposition between the hand shape B and the hand shape B-bent. It has been claimed that in Italian Sign Language the hand shape B is perceptually distinct from the hand shape B-bent, i.e. in opposition to the general, neutral, unmarked meaning of the hand shape B, the iconic hand shape B-bent has a more narrow, specific and marked meaning: DELIMIT. The B-bent hand shape appears in spatial-temporal signs such as "a little before, ahead, postpone or behind". In these signs the iconic structure of the hand shape B-bent is utilized to mark borders in space and time. The arguments opposing the perceptual/phonemic distinction between these hand shapes is based on the human-phonetic factor, i.e. the need to reduce the effort on the part of the wrist joints in specific phonetic environments. We performed a quantitative and qualitative content analysis of the distribution of the basic units of 560 lexical signs taken from a stratified random sample from the ISL dictionary. The results were analyzed in the framework of the sign-oriented linguistic theory of the Columbia School including the theory of Phonology as Human Behavior. Our data revealed that the B-bent hand shape--as all the "building blocks" of the ISL--is a morpho-phonemic unit. We found that there is not only a phonemic distinction between hand shape B and hand shape B-bent in ISL (based on minimal pairs), but there is also a perceptual distinction between them. The qualitative analysis shows that the

  9. Observation of multiple Bragg reflections of neutrons in bent perfect crystals

    Czech Academy of Sciences Publication Activity Database

    Mikula, Pavol; Vrána, Miroslav; Šaroun, Jan; Seong, B. S.; Moon, MK.

    2011-01-01

    Roč. 634, č. 1 (2011), S108-S111 ISSN 0168-9002. [International Workshop on Neutron Optics. Grenoble, 17.03.2010-19.03.2010] R&D Projects: GA ČR GAP204/10/0654 Institutional research plan: CEZ:AV0Z10480505 Keywords : Neutron diffraction * Bent perfect crystal * Multiple reflections Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.207, year: 2011

  10. Optimization of dynamically bent crystals for X-ray focusing monochromators

    Czech Academy of Sciences Publication Activity Database

    Artemiev, A.; Artemiev, Nikolai; Busetto, E.; Hrdý, Jaromír; Mrázek, D.; Savoia, A.

    467-468, - (2001), s. 373-376 ISSN 0168-9002 R&D Projects: GA MŠk OK 305; GA MPO PZ-CH/22 Grant - others:COPERNICUS N ERBIC 15(XE) CT96 Institutional research plan: CEZ:AV0Z1010914 Keywords : bent crystal * focusing x-ray monochromator * synchrotron radiation Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.026, year: 2001

  11. Time-of-flight studies of multiple Bragg reflections in cylindrically bent perfect crystals

    Czech Academy of Sciences Publication Activity Database

    Mikula, Pavol; Furusaka, M.; Ohkubob, K.; Šaroun, Jan

    2012-01-01

    Roč. 45, č. 12 (2012), s. 1248-1253 ISSN 0021-8898 R&D Projects: GA AV ČR KJB100480901; GA ČR GAP204/10/0654 Institutional support: RVO:61389005 Keywords : neutron diffraction * time-of-flight method * multiple reflections * bent perfect crystals Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.343, year: 2012

  12. Observation of nuclear dechanneling length reduction for high energy protons in a short bent crystal

    Directory of Open Access Journals (Sweden)

    W. Scandale

    2015-04-01

    Full Text Available Deflection of 400 GeV/c protons by a short bent silicon crystal was studied at the CERN SPS. It was shown that the dechanneling probability increases while the dechanneling length decreases with an increase of incident angles of particles relative to the crystal planes. The observation of the dechanneling length reduction provides evidence of the particle population increase at the top levels of transverse energies in the potential well of the planar channels.

  13. arXiv Electromagnetic dipole moments of charged baryons with bent crystals at the LHC

    CERN Document Server

    Bagli, E.; Cavoto, G.; Guidi, V.; Henry, L.; Marangotto, D.; Martinez Vidal, F.; Mazzolari, A.; Merli, A.; Neri, N.; Ruiz Vidal, J.

    2017-12-05

    We propose a unique program of measurements of electric and magnetic dipole moments of charm, beauty and strange charged baryons at the LHC, based on the phenomenon of spin precession of channeled particles in bent crystals. Studies of crystal channeling and spin precession of positively- and negatively-charged particles are presented, along with feasibility studies and expected sensitivities for the proposed experiment using a layout based on the LHCb detector.

  14. Anionic tantalum(V) bis(dicarbollide) complexes with bent-metallocene structures

    Energy Technology Data Exchange (ETDEWEB)

    Uhrhammer, R.; Su, Yue-Xin; Swenson, D.C.; Jordan, R.F. [Univ. of Iowa, Iowa City, IA (United States)

    1994-09-14

    Bis(dicarbollide) complexes {eta}{sup 5}-C{sub 2}B{sub 9}H{sub 11}){sub 2}M which adopt ferrocene-type metallocene structures are well known. However, ({eta}{sup 5}-C{sub 2}B{sub 9}H{sub 11}){sub 2}MX{sub n} species with bent metallocene structures are comparitively rare and are limited to the f-block metals. Key examples include Raymond`s dianionic U(IV) complex ({eta}{sup 5}-C{sub 2}B{sub 9}H{sub 11}){sub 2}UCl{sub 2}{sup 2-2} and a series of lanthanide complexes ({eta}{sup 5}-C{sub 2}B{sub 9}H{sub 11}){sub 2}Ln(THF){sup n-} (n = 2, Y; n = 1, Zr, Hf) complexes which adopt bent-metallocene structures. For several years, the authors have been investigating the possibility of exploiting carborane ligands in the construction of electrophilic early transition metal alkyl systems, and they have reported on a series of mixed-ring bent-metallocene (C{sub 5}-Me{sub 5})(C{sub 2}B{sub 9}H{sub 11})M(R) (M = Zr, Hf) and (C{sub 5}H{sub 4}R)(C{sub 2}B{sub 9}H{sub 11})TaX{sub 2} (R = H, Me) species. During the course of this work, the authors prepared a series of anionic tantalum (V) bis(dicarbollide) complexes, ({eta}{sup 5}-C{sub 2}B{sub 9}H{sub 11}){sub 2}TaX{sub 2}- (X = C1 (1), Me (2), F (3)), which adopt bent-metallocene structures. The synthesis and characterization of these compounds are discussed in this contribution.

  15. 3-Aminophenol based bent-shaped liquid crystals with an amide linking group

    Czech Academy of Sciences Publication Activity Database

    Kozmik, V.; Horčic, M.; Svoboda, J.; Novotná, Vladimíra; Pociecha, D.

    2012-01-01

    Roč. 39, č. 8 (2012), s. 943-955 ISSN 0267-8292 R&D Projects: GA ČR(CZ) GAP204/11/0723 Institutional research plan: CEZ:AV0Z10100520 Keywords : liquid crystals * aminophenol * bent-shaped mesogen Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.959, year: 2012 http://dx.doi.org/10.1080/02678292.2012.687781

  16. Naphthalene-based bent-shaped liquid crystals with a semifluorinated terminal chain

    Czech Academy of Sciences Publication Activity Database

    Kovářová, A.; Kozmik, V.; Svoboda, J.; Novotná, Vladimíra; Glogarová, Milada; Pociecha, D.

    2012-01-01

    Roč. 39, č. 6 (2012), s. 755-767 ISSN 0267-8292 R&D Projects: GA ČR(CZ) GAP204/11/0723 Institutional research plan: CEZ:AV0Z10100520 Keywords : liquid crystals * bent-shaped mesogen Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.959, year: 2012 http://www.tandfonline.com/loi/tlct20

  17. Electromagnetic dipole moments of charged baryons with bent crystals at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Bagli, E.; Bandiera, L.; Guidi, V.; Mazzolari, A. [Universita di Ferrara, Ferrara (Italy); INFN, Sezione di Ferrara (Italy); Cavoto, G. [' ' Sapienza' ' Universita di Roma, Rome (Italy); INFN, Sezione di Roma (Italy); Henry, L.; Martinez Vidal, F.; Ruiz Vidal, J. [IFIC, Universitat de Valencia-CSIC, Valencia (Spain); Marangotto, D. [Universita di Milano, Milan (Italy); INFN, Sezione di Milano (Italy); Merli, A.; Neri, N. [Universita di Milano, Milan (Italy); CERN, Geneva (Switzerland); INFN, Sezione di Milano (Italy)

    2017-12-15

    We propose a unique program of measurements of electric and magnetic dipole moments of charm, beauty and strange charged baryons at the LHC, based on the phenomenon of spin precession of channeled particles in bent crystals. Studies of crystal channeling and spin precession of positively- and negatively-charged particles are presented, along with feasibility studies and expected sensitivities for the proposed experiment using a layout based on the LHCb detector. (orig.)

  18. Intrinsic bent DNA sites in the chromosomal replication origin of Xylella fastidiosa 9a5c

    Directory of Open Access Journals (Sweden)

    F. Gimenes

    2008-04-01

    Full Text Available The features of the nucleotide sequences in both replication and promoter regions have been investigated in many organisms. Intrinsically bent DNA sites associated with transcription have been described in several prokaryotic organisms. The aim of the present study was to investigate intrinsic bent DNA sites in the segment that holds the chromosomal replication origin, oriC, of Xylella fastidiosa 9a5c. Electrophoretic behavior analyses, as well as in silico analyses of both the 2-D projection and helical parameters, were performed. The chromosomal segment analyzed contains the initial sequence of the rpmH gene, an intergenic region, the dnaA gene, the oriC sequence, and the 5' partial sequence of the dnaN gene. The analysis revealed fragments with reduced electrophoretic mobility, which indicates the presence of curved DNA segments. The analysis of the helical parameter ENDS ratio revealed three bent DNA sites (b1, b2, and b3 located in the rpmH-dnaA intergenic region, the dnaA gene, and the oriC 5' end, respectively. The chromosomal segment of X. fastidiosa analyzed here is rich in phased AT tracts and in CAnT motifs. The 2-D projection indicated a segment whose structure was determined by the cumulative effect of all bent DNA sites. Further, the in silico analysis of the three different bacterial oriC sequences indicated similar negative roll and twist >34.00° values. The DnaA box sequences, and other motifs in them, may be associated with the intrinsic DNA curvature.

  19. Dynamical chaos and stochastic mechanism of high-energy negatively charged particle deflection by bent crystals

    International Nuclear Information System (INIS)

    Shul'ga, N.F.; Kirillin, I.V.; Truten', V.I.

    2011-01-01

    Deflection of high-energy negatively charged particles in straight and bent crystals through multiple scattering by crystal atomic strings was considered for the case in which the initial angle between the particle momentum and one of the main crystallographic axes was approximately four critical angles of axial channeling. It was shown that in a bent crystal with a small crystal thickness, when the crystal bend was less than the beam incidence angle, the beam deflected in the direction opposite to the direction of the crystal bend. At larger crystal thicknesses, the large part of the beam starts to deflect in the direction of the crystal bend. In addition, there is a group of particles that follow the crystal axis bend in the angular region of approximately the critical angle of axial channeling with respect to the current direction of the crystal axis. It was shown that in all of these deflection processes, the periodicity of the location of atomic strings in the crystal does not influence the angular distributions of scattered particles. This fact is connected with the effect of dynamical chaos in particle motion in the periodical field of bent crystal atomic strings. It was also shown that observed in a recent CERN experiment effect of beam deflection, when the angle between the initial particle momentum and the crystal axis was approximately four critical angles of axial channeling, is due to peculiarities of the stochastic multiple scattering of particles by bent crystal atomic strings. These peculiarities are connected with the effect of dynamical chaos in particle motion in crystals.

  20. Bent-core liquid crystals with a 2-substituted 3-hydroxybenzoic acid central core

    Czech Academy of Sciences Publication Activity Database

    Pallová, L.; Kozmík, V.; Kohout, M.; Svoboda, J.; Novotná, Vladimíra; Pociecha, D.

    2017-01-01

    Roč. 44, č. 8 (2017), s. 1306-1315 ISSN 0267-8292 R&D Projects: GA ČR GA16-12150S; GA MŠk(CZ) LD14007; GA ČR GA15-02843S Institutional support: RVO:68378271 Keywords : liquid crystals * bent-core compounds Subject RIV: JJ - Other Materials OBOR OECD: Nano-materials (production and properties) Impact factor: 2.661, year: 2016

  1. 70 GeV proton volume capture into channeling mode with a bent Si single crystal

    International Nuclear Information System (INIS)

    Chesnokov, Yu.A.; Galyaev, N.A.; Kotov, V.I.; Tsarik, S.V.; Zapol'skij, V.N.

    1990-01-01

    The existence of the volume capture of 70 GeV protons with a Si bent single crystal of (111) orientation into the channeling mode gas experimentally been proved. The data on the probability of capturing protons into the channeling mode versus the bending radius of the crystal have been obtained together with the information on the dynamics of volume captured particle dechanneling. 10 refs

  2. Bent-core mesogens with an aromatic unit at the terminal position

    Czech Academy of Sciences Publication Activity Database

    Bajzikova, K.; Svoboda, J.; Novotná, Vladimíra; Pociecha, D.; Gorecka, E.

    2017-01-01

    Roč. 41, č. 11 (2017), s. 4672-4679 ISSN 1144-0546 R&D Projects: GA ČR GA16-12150S; GA ČR GA15-02843S Institutional support: RVO:68378271 Keywords : bent-core mesogens * liquid crystals Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.269, year: 2016

  3. Model of dark conglomerate structure in the B2 phase of bent-shaped molecules

    Czech Academy of Sciences Publication Activity Database

    Lejček, Lubor; Glogarová, Milada; Novotná, Vladimíra

    2013-01-01

    Roč. 87, č. 4 (2013), "042503-1"-"042503-7" ISSN 1539-3755 R&D Projects: GA ČR(CZ) GAP204/11/0723 Grant - others:GA ČR(CZ) 13-14133S Institutional support: RVO:68378271 Keywords : liquid crystals with bent-shaped molecules * dark conglomerate structure * focal conic domains Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.326, year: 2013

  4. Pre-bent elastic stable intramedullary nail fixation for distal radial shaft fractures in children.

    Science.gov (United States)

    Ge, Yi-hua; Wang, Zhi-gang; Cai, Hai-qing; Yang, Jie; Xu, Yun-lan; Li, Yu-chan; Zhang, Yu-chen; Chen, Bo-chang

    2010-08-01

    To investigate the functional and radiographic outcomes of pre-bent elastic stable intramedullary nail in treatment of distal radial shaft fractures in children. From January 2006 to December 2008, 18 children with distal radial shaft fracture were treated by close reduction and internal fixation with a pre-bent elastic stable intramedullary nail. The age range was from 5 years to 15 years, with an average of 9 years and 8 months. The minimum follow-up was 12 months. All fractures maintained good alignment postoperatively, and 94.4% (17/18) of the patients regained a full range of rotation of the forearm. One patient has limitation of rotation to less than 10°, this had improved by final follow-up. Complications included soft tissue irritation at the site of nail insertion in one patient and transient scar hypersensitivity in another. Fixation with a pre-bent elastic stable intramedullary nail is an effective, safe and convenient method for treating distal radial shaft fractures in children. © 2010 Tianjin Hospital and Blackwell Publishing Asia Pty Ltd.

  5. The bent crystal diffraction spectrometer at the BR2 reactor in Mol

    Science.gov (United States)

    Kaerts, E.; Jacobs, L.; Vandenput, G.; Van Assche, P. H. M.

    1988-05-01

    The DuMond-type bent crystal diffraction spectrometer installed at the BR2 reactor in Mol is presented. The spectrometer is mainly designed to study nuclear γ-transitions following thermal neutron capture. It covers the energy interval 25 ≦ Eγ ≦ 1500 keV. Instead of the traditionally used quartz crystals, a highly perfect silicium crystal is chosen as analysing crystal. Diffraction occurs from the (220) plane. The "quasi-mosaic" width, introduced by bending the crystal, is as small as 0.2″. The integrated reflecting power R of the bent crystal stays constant up to 1.5 MeV in first, 680 keV in second and 300 keV in third diffraction order. For higher photon energies, only an E-1 energy dependence is observed in second and third diffraction order. Consequently, besides improving the energy resolution, the use of these silicium crystals substantially increases the spectrometer efficiency and extends the high energy limit of bent crystal diffraction spectrometers. The diffraction angles are measured with a symmetrical interferometer system which covers an angular range of -6° to +6° with a precision of about 0.01″. Minimum diffraction line widths of 0.9″ have been measured, corresponding to an energy resolution ΔE = 1.35 × 10 -6E2n-1 keV -1. The dominant contribution to the observed line widths arises from the finite extent of the source.

  6. Short bent-core molecules: X-ray, polarization, dielectricity, texture and electro-optics investigations.

    Science.gov (United States)

    Torgova, S; Sreenilayam, S P; Panarin, Yu P; Francescangeli, O; Vita, F; Vij, J K; Pozhidaev, E; Minchenko, M; Ferrero, C; Strigazzi, A

    2017-08-30

    Bent-core liquid crystals based on 1,2,4-oxadiazole as a central unit have been the first mesogens to exhibit a ferroelectric response in the nematic phase. This behavior has been widely recognized as due to the presence of smectic-like polar cybotactic clusters permeating the nematic phase. Unfortunately, these compounds exhibited rather high melting points, about 120 °C, due to the presence of four benzene rings in the molecules. Here we describe the synthesis and physical characterization of a new series of BC mesogens, featuring the same bent core as the previous compounds but shorter outer substituents. By keeping only two benzene rings, we were able to lower the melting points to about 70 °C. However, while X-ray diffraction and dielectric spectroscopy measurements confirm the cybotactic nature of the nematic phase of these compounds, polarization and electro-optical measurements ascribe their polar response to flexoelectricity rather than to spontaneous polarization. Finally, texture investigation suggests the biaxiality of the nematic phase, which is indicated also by conoscopic measurements. These results are important for recognizing size and rigidity limitations in designing bent-core liquid crystal molecules suitable for applications.

  7. Origin of trans-bent geometries in maximally bonded transition metal and main group molecules.

    Science.gov (United States)

    Landis, Clark R; Weinhold, Frank

    2006-06-07

    Recent crystallographic data unambiguously demonstrate that neither Ar'GeGeAr' nor Ar'CrCrAr' molecules adopt the expected linear (VSEPR-like) geometries. Does the adoption of trans-bent geometries indicate that Ar'MMAr' molecules are not "maximally bonded" (i.e., bond order of three for M = Ge and five for M = Cr)? We employ theoretical hybrid density functional (B3LYP/6-311++G) computations and natural bond orbital-based analysis to quantify molecular bond orders and to elucidate the electronic origin of such unintuitive structures. Resonance structures based on quintuple M-M bonding dominate for the transition metal compounds, especially for molybdenum and tungsten. For the main group, M-M bonding consists of three shared electron pairs, except for M = Pb. For both d- and p-block compounds, the M-M bond orders are reflected in torsional barriers, bond-antibond splittings, and heats of hydrogenation in a qualitatively intuitive way. Trans-bent structures arise primarily from hybridization tendencies that yield the strongest sigma-bonds. For transition metals, the strong tendency toward sd-hybridization in making covalent bonds naturally results in bent ligand arrangements about the metal. In the p-block, hybridization tendencies favor high p-character, with increasing avidity as one moves down the Group 14 column, and nonlinear structures result. In both the p-block and the d-block, bonding schemes have easily identifiable Lewis-like character but adopt somewhat unconventional orbital interactions. For more common metal-metal multiply bonded compounds such as [Re2Cl8]2-, the core Lewis-like fragment [Re2Cl4]2+ is modified by four hypervalent three-center/four-electron additions.

  8. Bent and linear Uranium(IV) metallocenes with terminal and bridging cyanide ligands

    International Nuclear Information System (INIS)

    Maynadie, J.; Berthet, J.C.; Thuery, P.; Ephritikhine, M.

    2007-01-01

    Treatment of Cp 2 * UI 2 with KCN in thf led to the formation of Cp 2 * U(CN) 2 (2), which further reacted with NR 4 CN to give [Cp 2 * U(CN) 3 ][ NR 4 ] (R = Et, 3; R = n Bu, 3') and [Cp 2 * U(CN) 5 ][NR 4 ] 3 (R = Et, 4; R n Bu, 4'). While the tri-cyanide 3' adopts the familiar bent sandwich configuration, the penta-cyanide 4 is, after the [Cp 2 * U(NCMe) 5 ] 2+ cation, the second example of a linear metallocene resulting from complete saturation of the equatorial girdle. Compound 3' was also obtained by oxidation of the trivalent compound [Cp 2 * U(CN) 3 ][N n Bu 4 ] 2 ; the rapid and reversible electron transfer between the U(III) and U(IV) complexes was revealed by 1 H NMR spectroscopy. The NMR spectra also revealed that 4 is partially dissociated in thf into 3, providing the first example of an equilibrating couple of bent and linear metallocenes [K = 4.24(4) * 10 -5 at 25 C, ΔH = 199(6) kJ mol -1 , and ΔS = 586(20) J mol -1 K -1 ]. The trinuclear compound [Cp 2 * UCl 2 (μ-CN)] 2 Mg(thf) 4 (1) and the 2D polymeric complex [Cp 2 * U(dmf) 3 -(μ-NC) 2 (AgI) 2 ] n (5), which were obtained during initial attempts on the synthesis of 2-4 and uranium- (V) derivatives, exhibit a bent and linear sandwich structure, respectively. (authors)

  9. Analytical model of the critical current of a bent Nb3Sn strand

    International Nuclear Information System (INIS)

    Koizumi, Norikiyo; Murakami, Haruyuki; Hemmi, Tsutomu; Nakajima, Hideo

    2011-01-01

    The critical current performance of a large Nb 3 Sn cable-in-conduit conductor (CICC) was degraded by periodic bending of strands due to a large transverse electromagnetic force. The degradation of each strand due to this bending should be evaluated in calculations of the critical current of a CICC, but a suitable model has not been developed yet. Therefore, the authors have developed a new analytical model which takes into account plastic deformation of copper and bronze and filament breakage. The calculated results were compared with test results for uniformly bent Nb 3 Sn bronze-route strands. The calculated results assuming a high transverse resistance model (HTRM) show good agreement with the test results, a finding which confirms the validity of the model. Because of a much shorter calculation time than for numerical simulation, the developed model seems much more practical for use in calculating the critical current performance of a Nb 3 Sn CICC. In addition, simulation results show that since the neutral axis of a bent strand shifts to the compressive side due to plastic deformation of the copper and bronze, and/or filament breakage, the strand is elongated by bending. This elongation may enhance the strand's critical current performance. Moreover, the calculated results indicate that the dependence of the critical current on the bending strain is affected by the bending history if the strand is excessively bent, especially when filaments are broken. In a real magnet, since a strand in a CICC is normally subject to the maximum electromagnetic force prior to an evaluation of its performance at a lower electromagnetic force, the effect of over-bending should be taken into account in calculations of its critical current performance, especially when filament breakage occurs.

  10. Straight proximal humeral nails are surrounded by more bone stock in comparison to bent nails in an experimental cadaveric study.

    Science.gov (United States)

    Günther, Christian Max; Müller, Peter Ernst; Mutschler, Wolf; Sprecher, Christoph Martin; Milz, Stefan; Braunstein, Volker

    2014-01-01

    In the management of proximal humeral fractures intramedullary implants with bent and straight shape of the proximal part of nail are available. Based on data from previous studies on bone distribution in the humeral head, we hypothesized, that higher densities might exist in the bone stock surrounding straight nails in comparison to their angulated counterparts. With a known positive correlation between bone density and mechanical stability, this could indicate potentially higher rigidity of osteosyntheses done with straight implants. We performed high resolution peripheral quantitative computed tomographies of the potential straight and bent implant bearing regions of 27 cadaveric proximal humeri. The acquired data were analyzed for differences between straight and bent Volumes of Interest as well as intra- and interindividual bone stock distribution. For both straight and bent volumes of interest a considerably declining bone mineral density was found in craniocaudal direction. Mean densities of bent volumes were significantly lower in comparison to their corresponding straight counterparts (p straight shaped implants can be assumed. Since we found a rapid decrease of bone density in cranio-caudal direction, intramedullary implants should be anchored as proximally in the subcortical area as possible to minimize the risk of displacement or cutout. The high correlation between the Volumes of Interest of the corresponding right and left sides could aid in preoperative planning when considering an intra- or extramedullary approach.

  11. Measurement of grating visibility of a fiber Bragg grating based on bent-spectral analysis.

    Science.gov (United States)

    Gunawardena, Dinusha S; Lai, Man-Hong; Lim, Kok-Sing; Ali, Muhammad M; Ahmad, Harith

    2015-02-10

    In this study, a technique for measuring the grating visibility of the fiber Bragg grating (FBG) based on bent-spectral analysis is proposed. From varying ac and dc coupling coefficients at different bending radii, the grating visibility is estimated with the aid of a simple mathematical model. The investigation begins with the estimation of the grating visibility from the transmission spectra of the FBG during the inscription process. After that, the FBGs are subjected to a bending test with reducing radii, and again the transmission spectra are recorded. It is shown that the estimated grating visibility is in agreement with the result determined from the earlier inscription process.

  12. High resolution x-ray and gamma ray imaging using diffraction lenses with mechanically bent crystals

    Science.gov (United States)

    Smither, Robert K [Hinsdale, IL

    2008-12-23

    A method for high spatial resolution imaging of a plurality of sources of x-ray and gamma-ray radiation is provided. High quality mechanically bent diffracting crystals of 0.1 mm radial width are used for focusing the radiation and directing the radiation to an array of detectors which is used for analyzing their addition to collect data as to the location of the source of radiation. A computer is used for converting the data to an image. The invention also provides for the use of a multi-component high resolution detector array and for narrow source and detector apertures.

  13. Bent and planar structures of μ-η²:η²-N₂ dinuclear early transition metal complexes.

    Science.gov (United States)

    Ma, Xuelu; Tang, Yanhui; Lei, Ming

    2014-08-14

    This work studied the bent and planar structures of M2N2 cores of a series of dinuclear early transition-metal complexes (M = Zr, Hf, Nb, Ta, Mo and W) containing a side-on bridging dinitrogen ligand using DFT method. The calculated results propose three key factors favoring a bent structure: (1) the availability of a single electron in the metal centers which leads to the bonding interaction between two metal atoms, (2) no remarkable steric effect around the metal centers, and (3) the cis conformation of the ligands in the dinitrogen dinuclear complexes. In addition, the bent and planar structures of M2N2 could be transformed into each other if the steric hindrance was slight.

  14. Evaluation of bent-crystal x-ray backlighting and microscopy techniques for the Sandia Z machine.

    Science.gov (United States)

    Sinars, Daniel B; Bennett, Guy R; Wenger, David F; Cuneo, Michael E; Porter, John L

    2003-07-01

    X-ray backlighting and microscopy systems for the 1-10-keV range based on spherically or toroidally bent crystals are discussed. These systems are ideal for use on the Sandia Z machine, a megajoule-class x-ray facility. Near-normal-incidence crystal microscopy systems have been shown to be more efficient than pinhole cameras with the same spatial resolution and magnification [Appl. Opt. 37, 1784 (1998)]. We show that high-resolution (< or = 10 microm) x-ray backlighting systems using bent crystals can be more efficient than analogous point-projection imaging systems. Examples of bent-crystal-backlighting results that demonstrate 10-microm resolution over a 20-mm field of view are presented.

  15. Measuring the X-ray Resolving Power of Bent Potassium Acid Phthalate Diffraction Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Haugh, M. J. [NSTec; Wu, M. [SNL; Jacoby, K. D. [NSTec; Loisel, G. P. [SNL

    2014-11-01

    This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories (SNL) in Albuquerque, NM. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a dual goniometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.

  16. THE SPINDLE: AN IRRADIATED DISK AND BENT PROTOSTELLAR JET IN ORION

    Energy Technology Data Exchange (ETDEWEB)

    Bally, John; Youngblood, Allison; Ginsburg, Adam, E-mail: John.Bally@colorado.edu, E-mail: Allison.Youngblood@colorado.edu, E-mail: Adam.Ginsburg@colorado.edu [Department of Astrophysical and Planetary Sciences, University of Colorado, UCB 389, Boulder, CO 80309 (United States)

    2012-09-10

    We present Hubble Space Telescope observations of a bent, pulsed Herbig-Haro jet, HH 1064, emerging from the young star Parenago 2042 embedded in the H II region NGC 1977 located about 30' north of the Orion Nebula. This outflow contains eight bow shocks in the redshifted western lobe and five bow shocks in the blueshifted eastern lobe. Shocks within a few thousand AU of the source star exhibit proper motions of {approx}160 km s{sup -1} but motions decrease with increasing distance. Parenago 2042 is embedded in a proplyd-a photoevaporating protoplanetary disk. A remarkable set of H{alpha} arcs resembling a spindle surround the redshifted (western) jet. The largest arc with a radius of 500 AU may trace the ionized edge of a circumstellar disk inclined by {approx}30 Degree-Sign . The spindle may be the photoionized edge of either a {approx}3 km s{sup -1} FUV-driven wind from the outer disk or a faster MHD-powered flow from an inner disk. The HH 1064 jet appears to be deflected north by photoablation of the south-facing side of a mostly neutral jet beam. V2412 Ori, located 1' west of Parenago 2042 drives a second bent flow, HH 1065. Both HH 1064 and 1065 are surrounded by LL Ori-type bows marking the boundary between the outflow cavity and the surrounding nebula.

  17. Triggering and measuring bent cosmic muon tracks with the Muon Spectrometer barrel for the first time

    CERN Multimedia

    Fabio Cerutti

    During the ATLAS barrel toroid stability test, bent cosmic muon tracks were seen for the first time in the ATLAS cavern by means of the ATLAS muon spectrometer. The barrel toroid has been powered at its nominal current (20.5 thousand Amperes) and kept in steady state for more than one day during the weekend of 18-19 November (see a report on this test in the Magnet section). During this test one large sector and part of a small sector of the barrel muon spectrometer were readout and used to detect the cosmic muons tracks bent by the toroidal magnetic field. Thirteen muon stations in the feet sectors (sectors 13 and 14) have been used in this test. The muon stations are formed of Resistive Plate Chambers (RPC) that were providing the muon trigger, and Monitored Drift Tubes that were used to measure with high accuracy the muon curvature hence their momentum. The Level-1 Barrel trigger chain was based on the Barrel Middle Large chambers equipped with final production modules on both the on-detector and the o...

  18. Long, elliptically bent, active X-ray mirrors with slope errors <200 nrad.

    Science.gov (United States)

    Nistea, Ioana T; Alcock, Simon G; Kristiansen, Paw; Young, Adam

    2017-05-01

    Actively bent X-ray mirrors are important components of many synchrotron and X-ray free-electron laser beamlines. A high-quality optical surface and good bending performance are essential to ensure that the X-ray beam is accurately focused. Two elliptically bent X-ray mirror systems from FMB Oxford were characterized in the optical metrology laboratory at Diamond Light Source. A comparison of Diamond-NOM slope profilometry and finite-element analysis is presented to investigate how the 900 mm-long mirrors sag under gravity, and how this deformation can be adequately compensated using a single, spring-loaded compensator. It is shown that two independent mechanical actuators can accurately bend the trapezoidal substrates to a range of elliptical profiles. State-of-the-art residual slope errors of <200 nrad r.m.s. are achieved over the entire elliptical bending range. High levels of bending repeatability (ΔR/R = 0.085% and 0.156% r.m.s. for the two bending directions) and stability over 24 h (ΔR/R = 0.07% r.m.s.) provide reliable beamline performance.

  19. Investigation of the Electromagnetic Radiation Emitted by Sub-GeV Electrons in a Bent Crystal.

    Science.gov (United States)

    Bandiera, L; Bagli, E; Germogli, G; Guidi, V; Mazzolari, A; Backe, H; Lauth, W; Berra, A; Lietti, D; Prest, M; De Salvador, D; Vallazza, E; Tikhomirov, V

    2015-07-10

    The radiation emitted by 855 MeV electrons via planar channeling and volume reflection in a 30.5-μm-thick bent Si crystal has been investigated at the MAMI (Mainzer Mikrotron) accelerator. The spectral intensity was much more intense than for an equivalent amorphous material, and peaked in the MeV range in the case of channeling radiation. Differently from a straight crystal, also for an incidence angle larger than the Lindhard angle, the spectral intensity remains nearly as high as for channeling. This is due to volume reflection, for which the intensity remains high at a large incidence angle over the whole angular acceptance, which is equal to the bending angle of the crystal. Monte Carlo simulations demonstrated that incoherent scattering significantly influences both the radiation spectrum and intensity, either for channeling or volume reflection. In the latter case, it has been shown that incoherent scattering increases the radiation intensity due to the contribution of volume-captured particles. As a consequence, the experimental spectrum becomes a mixture of channeling and pure volume reflection radiations. These results allow a better understanding of the radiation emitted by electrons subjected to coherent interactions in bent crystals within a still-unexplored energy range, which is relevant for possible applications for innovative and compact x-ray or γ-ray sources.

  20. In vivo longitudinal micro-CT study of bent long limb bones in rat offspring.

    Science.gov (United States)

    De Schaepdrijver, Luc; Delille, Peter; Geys, Helena; Boehringer-Shahidi, Christian; Vanhove, Christian

    2014-07-01

    Micro-computed X-ray tomography (micro-CT) has been reported as a reliable method to assess ex vivo rat and rabbit fetal skeletons in embryo-fetal developmental toxicity studies. Since micro-CT is a non-invasive imaging modality it has the potential for longitudinal, in vivo investigation of postnatal skeletal development. This is the first paper using micro-CT to assess the reversibility of drug-induced bent long bones in a longitudinal study from birth to early adulthood in rat offspring. Analysis of the scans obtained on postnatal Day 0, 7, 21 and 80 showed complete recovery or repair of the bent long limb bones (including the scapula) within the first 3 weeks. When assessing risk the ability to demonstrate recovery is highly advantageous when interpreting such transient skeletal change. In summary, in vivo micro-CT of small laboratory animals can aid in non-clinical safety assessment, particularly for specific mechanistic purposes or to address a particular concern in developmental biology. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Converse flexoelectric effect in a bent-core nematic liquid crystal.

    Science.gov (United States)

    Harden, J; Teeling, R; Gleeson, J T; Sprunt, S; Jákli, A

    2008-09-01

    Flexoelectricity is a unique property of liquid crystals; it is a linear coupling between electric polarizations and bend and/or splay distortions of the direction of average molecular orientation. Recently it was shown [J. Harden, Phys. Rev. Lett. 97, 157802 (2006)] that the bend flexoelectric coefficient in bent-core nematic liquid crystals can be three orders of magnitude higher than the effect with calamitic (rod-shaped) molecular shape. Here we report the converse of the flexoelectric effect: An electric field applied across a bent-core liquid crystal sandwiched between thin flexible substrates produces a director distortion which is manifested as a polarity-dependent flexing of the substrates. The flex magnitude is shown to be consistent with predictions based upon both the measured value of the bend flexoelectric constant and the elastic properties of the substrates. Converse flexoelectricity makes possible a new class of microactuators with no internal moving parts, which offers applications as diverse as optical beam steering to artificial muscles.

  2. Nanostructures of liquid crystal phases in mixtures of bent-core and rod-shaped molecules

    International Nuclear Information System (INIS)

    Hong, S. H.; Gleeson, J. T.; Sprunt, S.; Verduzco, R.; Jakli, A.

    2011-01-01

    We report small angle x-ray scattering (SAXS) studies of isotropic, nematic, and smectic mesophases formed by binary mixtures of bent-core (BC) and rod-shaped (RS) molecules. While optical studies indicate that the components are fully miscible, SAXS reveals fascinating structures that are consistent with segregation on a nanoscopic scale. We find that tilted smectic clusters, which have been previously reported in both the nematic and isotropic states of the pure BC materials, are also present in mixtures with up to 50 wt% of the RS compound; this is consistent with previous dielectric and flexoelectric studies on such mixtures. Unexpectedly in this concentration range the clusters are present in the isotropic and in the induced smectic phase range, as well as throughout the nematic phase. The results in the smectic phase also reveal complex layering phenomena, providing important insight into the interaction between bent and rod-shaped molecules. These studies will be crucial in the design of promising new functional nanomaterials.

  3. Extraordinary properties of nematic phases of bent-core liquid crystals

    Science.gov (United States)

    Jákli, A.; Chambers, M.; Harden, J.; Madhabi, M.; Teeling, R.; Kim, J.; Li, Q.; Nair, G. G.; Éber, N.; Fodor-Csorba, K.; Gleeson, J. T.; Sprunt, S.

    2008-02-01

    We briefly review systematic and comprehensive studies on several chlorine-substituted bent-core liquid crystal materials in their nematic phases. The results, in comparison to rod-shaped molecules, are both extraordinary and technologically significant. Specifically: a) Electrohydrodynamic instabilities provide unique patterns including well defined, periodic stripes and optically isotropic structures. b) Rheological measurements using different probe techniques (dynamic light scattering, pulsed magnetic field, electrorotation) reveal that the ratio of the flow and rotational viscosities are over two orders of magnitudes larger in bentcore than in calamitic materials which proves that the molecule shape and not its size is responsible for this behaviour. c) Giant flexoelectric response, as measured by dynamic light scattering and by directly probing the induced current when the material is subject to oscillatory bend deformation, turns out to be more than three orders of magnitude larger than in calamitics and 50 times larger than molecular shape considerations alone would predict. The magnitude of this effect renders these materials as promising candidates for efficient conversion between mechanical and electrical energy. d) The converse of this effect when the bent-core material sandwiched between plastic substrates 4 times thicker than the liquid crystal material provided displacements in the range of 100nm that is sensitive to the polarity of the applied field thus suggesting applications as beam steering and precision motion controls.

  4. Proton and light ion deflection at medium energies with planar bent crystals

    Science.gov (United States)

    Ray, C.; Dauvergne, D.

    2017-07-01

    The transmission of protons in planar channeling or in the regime of crystal reflection in bent crystals is now routinely used at high energy. We used the property that channeling critical angle increases as the incident particle momentum decreases, to explore the region of moderate energies (100 MeV-1 GeV). Indeed, such energies are particularly interesting since medical applications such as particle therapy have to face the constraints of being compatible with hospital-based accelerators. Therefore, replacing tens- or even hundreds-tons gantries by bent crystals would - if feasible - meet societal applications. We used binary-encounter simulations of trajectories inside crystals oriented along planar directions. The Molière potential with thermally vibrating lattice atoms was used, and additional transverse heating was introduced to account for multiple elastic scattering by close-collisions on electrons, which depends on the transverse energy of the channeled ions. The survival yield (i.e. the fraction of ions keeping trajectories within plus-minus one critical planar channeling angle with respect to lattice planes) was simulated for protons and carbon ions, as a function of crystal nature (silicon or germanium), crystal temperature, thickness and curvature. Although the transmitted yields are far from the necessary yields required to treat patients, significant survival yields were found through cm-thick crystals at angles beyond 10°. We will discuss possible experimental verification of these findings, and in particular practical aspects of such very large bending angles.

  5. Nanodoping: a route for enhancing electro-optic performance of bent core nematic system

    Science.gov (United States)

    Kumar, Pradeep; Debnath, Somen; Rao, Nandiraju V. S.; Sinha, Aloka

    2018-03-01

    We report the effect of dispersion of barium titanate (BaTiO3) nanoparticles (BNPs) in a four ring bent core nematic (BCN) liquid crystal. Polarizing optical microscopy reveals the presence of a single nematic phase in pure and doped states. Polar switching has been observed in the bent core system and the value of spontaneous polarization (P s) increases with increase in doping concentration of BNPs in BCN. Dielectric study shows a lower frequency mode, which can be ascribed to the formation of cybotactic clusters. These clusters are also responsible for the observed polar switching in pure, as well as, in doped BCNs. Another higher frequency mode, observed only in pure BCN, indicates the rotation of molecules about their long molecular axis. The conductivity of doped samples is also found to decrease as compared to the pure BCN. This reduction helps in the minimization of negative effects caused by free ions in liquid crystal based devices. This study demonstrates that the interaction between BNPs and BCN molecules improves the P s, dielectric behaviour, viscosity and reduces the conductivity of pure BCN. Hence, nanodoping in a BCN is an effective method for the enhancement of electro-optic performances and will lead to the development of faster electro-optic devices.

  6. Toroidal Lagrangian Flow Structues in highly viscous fluids by moving bent rods

    Science.gov (United States)

    Chtcheprov, Pavel; Camassa, Roberto; Holz, David; Marron, David; Martindale, James; McLaughlin, Richard; Vicci, Leandra; Zhao, Longhua

    2010-11-01

    Motile cilia play a large role in fluid motion across the surface of ciliates. Flows caused by the cilia move debris and mucus through mass beat patterns controlled by the motor proteins while rotating about the basal body that attaches the cilium to the cell surface. This study approximates the cilium as a slender body rotating about a point of contact of one of its ends in a viscous fluid. The bent rod sweeps out a virtual cone with a chord connecting both ends. The bend of the rod, the cone angle, the angle between the central axis to the normal plane, and the angle of rotation of the bent rod about its chord affect the flow patterns in a Stokes fluid. The slender body theory allows for an asymptotic solution of the Lagrangian trajectories and flow patterns caused by the precessing rod, which can be directly compared to experimental data. Altering the above parameters produces different toroidal flow structures. Using 3D stereo calibration, accurate quantified comparisons of epicyclic particle trajectories in short and long time are made against the model predictions.

  7. Hidden diversity in bent-winged bats (Chiroptera: Miniopteridae) of the Western Palaearctic and adjacent regions: implications for taxonomy

    Czech Academy of Sciences Publication Activity Database

    Šrámek, J.; Gvoždík, Václav; Benda, P.

    2013-01-01

    Roč. 167, č. 1 (2013), s. 165-190 ISSN 0024-4082 R&D Projects: GA ČR(CZ) GA206/09/0888 Keywords : Arabia * bent-winged bats * cryptic species Subject RIV: EG - Zoology Impact factor: 2.658, year: 2013

  8. Some properties of the neutron monochromatic beams obtained by multiple Bragg reflections realized in bent perfect single crystals

    Czech Academy of Sciences Publication Activity Database

    Mikula, Pavol; Vrána, Miroslav; Šaroun, Jan; Krejčí, F.; Seong, B. S.; Woo, W.; Furusaka, M.

    2013-01-01

    Roč. 46, č. 1 (2013), s. 128-134 ISSN 0021-8898 R&D Projects: GA ČR GAP204/10/0654; GA MŠk LM2010011 Institutional support: RVO:61389005 Keywords : multiple reflections * bent perfect crystals * neutron diffraction Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.950, year: 2013

  9. Supermolecular bent configuration composed of achiral flexible liquid crystal trimers exhibiting chiral domains with opposite handedness.

    Science.gov (United States)

    Sasaki, Haruna; Takanishi, Yoichi; Yamamoto, Jun; Yoshizawa, Atsushi

    2015-03-26

    Chirality's effects on physical properties of materials and how chirality arises have persisted as attractive issues in chemistry. We prepared a homologous series of achiral liquid crystal trimers in which three phenylpyrimidine units are connected via flexible heptamethylene spacers. An equimolecular mixture of a trimer with a nematic (N) phase and that with smectic A (SmA), smectic C (SmC), and smectic B phases was found to exhibit an N phase, a SmC phase, and a B4 phase composed of chiral domains with opposite handedness. The chiral characteristics of the B4 phase were confirmed by uncrossing the polarizers in opposite directions. XRD measurements reveal that both SmC and B4 phases have an interdigitated layer structure. That molecular interdigitation might form a supermolecular bent configuration that can produce saddle splay curvature to drive the B4 phase.

  10. The fourth Bent-toed Gecko of the genus Cyrtodactylus (Squamata: Gekkonidae) from Java, Indonesia.

    Science.gov (United States)

    Riyanto, Awal; Grismer, L Lee; Wood, Perry L

    2015-12-22

    Cyrtodactylus petani sp. nov. is a new species of Bent-toed Gecko from Java, Indonesia that had been masquerading under the name C. fumosus (Müller, 1895). The new species is differentiated from C. fumosus and all its Sundaland congeners by having the following combination of morphological characters: a maximum SVL of 57.2 mm; nine or ten supralabials; seven or eight infralabials; strongly tuberculate body and limbs; 20-25 paravertebral tubercles; 30-35 ventral scales; enlarged precloacal scales; enlarged femoral scales; 17-18 subdigital lamellae on the fourth toe; 31-35 continuous precloacal and femoral pores in males, pores absent in females; no precloacal groove; no enlarged median subcaudals; tubercles on anterior portion of tail; no reticulated pattern on top of head; a blotched dorsal pattern; and no paired, dark, semi-lunar shaped blotches on the nape.

  11. Bent bone dysplasia (BBD)-FGFR2 type: the radiologic manifestations in early gestation

    Energy Technology Data Exchange (ETDEWEB)

    Handa, Atsuhiko; Okajima, Yuka; Kurihara, Yasuyuki [St. Luke' s International Hospital, Department of Radiology, Tokyo (Japan); Izumi, Noriko; Yamanaka, Michiko [St. Luke' s International Hospital, Department of Integrated Women' s Health, Tokyo (Japan)

    2016-02-15

    Bent bone dysplasia-fibroblast growth factor receptor 2 type (BBD-FGFR2) is a recently identified skeletal dysplasia caused by specific FGFR2 mutations, characterized by craniosynostosis and prenatal bowing of the long bones. Only a few cases have been published. We report an affected fetus terminated at 21 weeks of gestation. The clinical and radiologic manifestations mostly recapitulate previous descriptions; however we suggest additional hallmarks of this disorder in early gestation. These hallmarks include distinctive short, thick clavicles and wavy ribs, as well as vertebral bodies that showed striking anteroposterior shortening. Femoral fractures were also present in our case. Although craniosynostosis is a hallmark of the disease, clinicians should be aware that craniosynostosis might not be readily apparent on plain films early in gestation. (orig.)

  12. Performance of bent-crystal x-ray microscopes for high energy density physics research.

    Science.gov (United States)

    Schollmeier, Marius S; Geissel, Matthias; Shores, Jonathon E; Smith, Ian C; Porter, John L

    2015-06-01

    We present calculations for the field of view (FOV), image fluence, image monochromaticity, spectral acceptance, and image aberrations for spherical crystal microscopes, which are used as self-emission imaging or backlighter systems at large-scale high energy density physics facilities. Our analytic results are benchmarked with ray-tracing calculations as well as with experimental measurements from the 6.151 keV backlighter system at Sandia National Laboratories. The analytic expressions can be used for x-ray source positions anywhere between the Rowland circle and object plane. This enables quick optimization of the performance of proposed but untested, bent-crystal microscope systems to find the best compromise between FOV, image fluence, and spatial resolution for a particular application.

  13. Especies bentónicas de Opisthobranchia (Mollusca: Gastropoda presentes en el litoral del norte peruano

    Directory of Open Access Journals (Sweden)

    Katia Nakamura

    2013-05-01

    Full Text Available El presente trabajo muestra las especies bentónicas de Opisthobranchia registradas para el norte del Perú. El trabajo se basa en la recopilación de la literatura científica disponible para el área de interés. Se presentan las 17 especies reportadas para dicha zona, clasificadas dentro del Grupo Informal Opisthobranchia en 6 clados, 12 familias y 14 géneros. A pesar del alto potencial de diversidad que se le otorga a la costa norte peruana, el número de especies registradas es bajo, debido principalmente al escaso número de exploraciones e investigaciones realizadas.

  14. Channeling, volume reflection, and volume capture study of electrons in a bent silicon crystal

    Directory of Open Access Journals (Sweden)

    T. N. Wistisen

    2016-07-01

    Full Text Available We present the experimental data and analysis of experiments conducted at SLAC National Accelerator Laboratory investigating the processes of channeling, volume-reflection and volume-capture along the (111 plane in a strongly bent quasimosaic silicon crystal. These phenomena were investigated at 5 energies: 3.35, 4.2, 6.3, 10.5, and 14.0 GeV with a crystal with bending radius of 0.15 m, corresponding to curvatures of 0.053, 0.066, 0.099, 0.16, and 0.22 times the critical curvature, respectively. Based on the parameters of fitting functions we have extracted important parameters describing the channeling process such as the dechanneling length, the angle of volume reflection, the surface transmission, and the widths of the distribution of channeled particles parallel and orthogonal to the plane.

  15. Electro-optic characterization of a nematic phase formed by bent core mesogens.

    Science.gov (United States)

    Tamba, M-G; Weissflog, W; Eremin, A; Heuer, J; Stannarius, R

    2007-01-01

    The purpose of this paper is the demonstration that bent core nematic phases behave quantitatively and qualitatively very different from ordinary calamitic nematics in their electro-optical characteristics. We present measurements of the elastic properties from the analysis of Brochard-Leger walls that are formed during the splay Fréedericksz transition in sandwich cells. These walls possess an unusually large shape anisotropy as compared to similar structures in calamitic nematics. The wall shapes can be explained when one assumes that the bend elastic constant K(33) is one order of magnitude larger than the twist constant K(22) of the material, supposing that flexoelectricity in the description of the elastic deformations can be neglected. Further we report periodic structures above the splay Fréedericksz transition with a wave vector perpendicular to the director easy axis. They represent either a static instability or an unconventional type of electrically driven convection.

  16. Effects of flexoelectricity and surface elasticity on piezoelectric potential in a bent ZnO nanowire

    Science.gov (United States)

    Zhang, Shuangzhe; Yao, Haiyan; Fan, Wenliang; Hao, Yu; Wu, Xudong; Hou, Dongyuan

    2017-01-01

    In this work, a rapid model is established to study the effects of flexoelectricity and surface elasticity on the piezoelectric potential of a bent ZnO nanowire. Based on the piezoelectric theory and core-surface model, the distribution of piezoelectric potential of the ZnO nanowire is investigated. The analytical solution shows that the flexoelectricity and surface elasticity both significantly influence the piezoelectric potential. However, the effect of flexoelectricity is longitudinal dependent, which vanishes on the top side of nanowire, but only left surface elasticity effect on the potential. Simulation results show that the maximum value of potential on the top side of nanowire is about ± 220.5mV, of which result is lower compared to other theoretical models, but it should be more reasonable.

  17. Real-time slope mapping and defect detection in bent plates using Talbot interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Trivedi, Satya Prakash; Prakash, Shashi; Rana, Santosh; Sasaki, Osami

    2010-02-10

    We demonstrate a simple method for obtaining slope contours of bent plates using Talbot interferometry. The technique has been used to map slope contours of polymethyl methacrylate specimens of different shapes. The Talbot image of a coarse grating is projected onto a specimen such that the self-image is backreflected onto the same grating again. As a Talbot interferometer is basically a grating shearing interferometer, it results in the generation of characteristic slope maps of the specimen under test. Results of the investigation match well with other slope-mapping techniques. Validation of experimental results with theoretical predictions in the case of a cantilever beam specimen has been undertaken. Accuracy of about 4.7% with respect to theoretical predictions is obtained.

  18. Energy loss distributions of 7 TeV protons channeled in a bent silicon crystals

    Directory of Open Access Journals (Sweden)

    Stojanov Nace

    2013-01-01

    Full Text Available The energy loss distributions of relativistic protons axially channeled through the bent Si crystals, with the constant curvature radius, R = 50 m, are studied here. The proton energy is 7 TeV and the thickness of the crystal is varied from 1 mm to 5 mm, which corresponds to the reduced crystal thickness, L, from 2.1 to 10.6, respectively. The proton energy was chosen in accordance with the large hadron collider project, at the European Organization for Nuclear Research, in Geneva, Switzerland. The energy loss distributions of the channeled protons were generated by the computer simulation method using the numerical solution of the proton equations of motion in the transverse plane. Dispersion of the proton scattering angle caused by its collisions with the crystal’s electrons was taken into account. [Projekat Ministarstva nauke Republike Srbije, br. III 45006

  19. Deflection of GeV particle beams by channeling in bent crystal planes of constant curvature

    International Nuclear Information System (INIS)

    Forster, J.S.; Hatton, H.; Toone, R.J.

    1989-01-01

    The deflection of charged particle beams moving within the (110) planes of a 43 mm long silicon crystal has been observed for momenta from 60 to 200 GeV/c. The crystal was bent by a 10.8 μm thick coating of ZnO along the central 26 mm of the crystal. Measurements were made with the crystal at room temperature, where a total deflection of 32.5 mrad was observed, and with the crystal cooled to -145 o C, where a 30.9 mrad deflection was observed. The ratio of the number of particles that dechannel upon entering the bend to the number of initially channeled particles compares well with calculations based on the continuum model. (author)

  20. Dipolar interactions, molecular flexibility, and flexoelectricity in bent-core liquid crystals.

    Science.gov (United States)

    Dewar, Alastair; Camp, Philip J

    2005-11-01

    The effects of dipolar interactions and molecular flexibility on the structure and phase behavior of bent-core molecular fluids are studied using Monte Carlo computer simulations. Some calculations of flexoelectric coefficients are also reported. The rigid cores of the model molecules consist of either five or seven soft spheres arranged in a "V" shape with external bend angle gamma. With purely repulsive sphere-sphere interactions and gamma = 0 degrees (linear molecules) the seven-sphere model exhibits isotropic, uniaxial nematic, and untilted and tilted smectic phases. With gamma > or = 20 degrees the untilted smectic phases disappear, while the system with gamma > or = 40 degrees shows a direct tilted smectic-isotropic fluid transition. The addition of electrostatic interactions between transverse dipole moments on the apical spheres is generally seen to reduce the degree of molecular inclination in tilted phases, and destabilizes the nematic and untilted smectic phases of linear molecules. The effects of adding three-segment flexible tails to the ends of five-sphere bent-core molecules are examined using configurational-bias Monte Carlo simulations. Only isotropic and smectic phases are observed. On the one hand, molecular flexibility gives rise to pronounced fluctuations in the smectic-layer structure, bringing the simulated system in better correspondence with real materials; on the other hand, the smectic phase shows almost no tilt. Lastly, the flexoelectric coefficients of various nematic phases--with and without attractive sphere-sphere interactions--are presented. The results are encouraging, but a large computational effort is required to evaluate the appropriate fluctuation relations reliably.

  1. Chaotic characteristics enhanced by impeller of perturbed six-bent-bladed turbine in stirred tank

    Directory of Open Access Journals (Sweden)

    Deyu Luan

    Full Text Available The fundamental way of improving the mixing efficiency is to induce the chaotic flow in a stirred vessel. The impeller form plays an important role for changing the structure of flow field and realizing chaotic mixing. Based on the velocity time series acquired by the experiment of particle image velocimetry (PIV, with the software Matlab, the macro-instability (MI, largest Lyapunov exponent (LLE, and Kolmogorov entropy in the water stirred tank is investigated respectively with the impeller of perturbed six-bent-bladed turbine (6PBT. The results show that the MI characteristics are obvious and two peak values of MI frequency are observed at the speed N = 60 rpm. With the increasing speed (more than 100 rpm, the peak characteristics of MI frequency disappear and a multi-scale wavelet structure of characterizing the chaotic flow field appears. Moreover, under the speed N = 60 rpm, the LLE is less than 0 and Kolmogorov entropy is 0, which means that the flow field is in the periodic moving state. As the speed is increased to more than 100 rpm, the LLE and Kolmogorov entropy are all more than 0, which indicates that the flow field goes into the chaotic mixing. When the speed reaches up to about 210 rpm, both of the LLE and Kolmogorov entropy achieve the optimum values, which will result in an excellent chaos with the highest mixing efficient. So it is feasible that the MI frequency, the LLE and the Kolmogorov entropy can be used to analyze the flow field characteristics in a stirred tank. The research results promote the understanding of the chaotic mixing mechanism and provide a theoretical reference for the development of new type impeller. Keywords: Macro-instability, The largest Lyapunov exponent, Kolmogorov entropy, The impeller of perturbed six-bent-bladed turbine, Chaotic mixing, PIV

  2. Observation and comparative analysis of proton beam extraction or collimation by different planar channels of a bent crystal

    Directory of Open Access Journals (Sweden)

    A. G. Afonin

    2012-08-01

    Full Text Available In the experiment the efficiency of the 50 GeV proton beam extraction from accelerator by means of a bent crystal as a function of crystal orientation was measured. This allowed one to make a comparative analysis of efficiencies of high-energy protons deflection by different crystal atomic planes with different values of the electrostatic field. The results of simulation of high-energy protons deflection by means of crystal atomic planes and crystal atomic strings are also presented in the article. In the case of planar channeling the simulation shows a good agreement with experimental data. In the case of proton motion in the regime of stochastic scattering by bent atomic strings the simulation shows that angles of particle deflection are much greater than the critical channeling angle.

  3. Electrostatic potential in a bent piezoelectric nanowire with consideration of size-dependent piezoelectricity and semiconducting characterization.

    Science.gov (United States)

    Wang, Kaifa; Wang, Baolin

    2018-03-26

    Determining the electric potential in a bent piezoelectric nanowire (NW) is a fundamental issue of nanogenerators and nanopiezotronics. The combined influence of the flexoelectric effect, the semiconducting performance and the angle of atomic force microscope (AFM) tip has never been studied previously and will be investigated in this paper. The exact solution for the electric potential of a bent piezoelectric semiconductor NW is derived. The electric potential of the present model with consideration of flexoelectric effect varies along the length of the NW and is different from that of the classical piezoelectric model. Flexoelectric effect enhances but the semiconducting performance reduces the electric potential of the NW. In addition, it is found that if the angle of the AFM tip reaches 30 degrees, the error of the electric potential obtained from the model ignored the effect of the angle of the AFM tip is almost 16%, which is unacceptable. © 2018 IOP Publishing Ltd.

  4. Develop Strong and Serviceable Details for Precast, Prestressed Concrete Bent Cap Standards That Can Be Implemented on Everyday Bridge Construction Projects, Project Summary

    Science.gov (United States)

    2018-01-01

    Pretensioned bent caps are an attractive substructure component because they offer contractors an option for fabrication by prestressing plants and can be used to eliminate or reduce cracks. Two sets of design recommendations were developed to enable...

  5. Photo-optical properties of amorphous and crystalline films of azobenzene-containing photochromes with bent-shaped molecular structure

    Czech Academy of Sciences Publication Activity Database

    Bobrovsky, A.; Shibaev, V.; Hamplová, Věra; Bubnov, A.; Novotná, V.; Kašpar, M.; Piryazev, A.; Anokhin, D.; Ivanov, D.

    2016-01-01

    Roč. 316, Feb (2016), s. 75-87 ISSN 1010-6030 R&D Projects: GA ČR GA13-14133S; GA MŠk(CZ) LD14007 Institutional support: RVO:68378271 Keywords : bent-shaped azobenzene-containing compounds * E–Z isomerization * thin films * photoinduced phase transition * photoorientation Subject RIV: CC - Organic Chemistry Impact factor: 2.625, year: 2016

  6. Non-symmetrical bent-shaped liquid crystals based on laterally substituted naphthalene central core with four ester groups

    Czech Academy of Sciences Publication Activity Database

    Kohout, M.; Svoboda, J.; Novotná, Vladimíra; Pociecha, D.

    2011-01-01

    Roč. 38, č. 9 (2011), 1099-1110 ISSN 0267-8292 R&D Projects: GA AV ČR IAA100100911; GA AV ČR(CZ) GA202/09/0047; GA ČR(CZ) GAP204/11/0723 Institutional research plan: CEZ:AV0Z10100520 Keywords : liquid crystals * bent-shaped mesogens Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.858, year: 2011

  7. Unusual polymorphism in new bent-shaped liquid crystals based on biphenyl as a central molecular core

    Czech Academy of Sciences Publication Activity Database

    Kovářová, A.; Světlík, S.; Kozmik, V.; Svoboda, J.; Novotná, Vladimíra; Pociecha, D.; Gorecka, E.; Podoliak, Natalia

    2014-01-01

    Roč. 10, Apr (2014), s. 794-807 ISSN 1860-5397 R&D Projects: GA ČR GA13-14133S; GA ČR(CZ) GAP204/11/0723 Grant - others:AVČR(CZ) M100101211 Institutional support: RVO:68378271 Keywords : bent-shaped * biphenyl core * liquid crystals * mesomorphic behaviour * SmCG phase Subject RIV: JJ - Other Materials Impact factor: 2.762, year: 2014

  8. Characterization of kink actuators as compared to traditional chevron shaped Bent-Beam electrothermal actuators

    KAUST Repository

    Rawashdeh, E.

    2012-07-06

    This paper compares the design and performance of kink actuators, a modified version of the bent-beam thermal actuator, to the standard chevron-shaped designs. A variety of kink and chevron actuator designs were fabricated from polysilicon. While the actuators were electrically probed, these designs were tested using a probe station connected to a National Instruments (NI) controller that uses LabVIEW to extract the displacement results via image processing. The displacement results were then used to validate the thermal-electric-structural simulations produced by COMSOL. These results, in turn, were used to extract the stiffness for both actuator types. The data extracted show that chevron actuators can have larger stiffness values with increasing offsets, but at the cost of lower amplification factors. In contrast, kink actuators showed a constant stiffness value equivalent to the chevron actuator with the highest amplification factor. The kink actuator also had larger amplification factors than chevrons at all designs tested. Therefore, kink actuators are capable of longer throws at lower power levels than the standard chevron designs.

  9. Whole-body muscle MRI to detect myopathies in non-extrapyramidal bent spine syndrome

    International Nuclear Information System (INIS)

    Ohana, Mickael; Durand, Marie-Christine; Marty, Catherine; Lazareth, Jean-Philippe; Maisonobe, Thierry; Mompoint, Dominique; Carlier, Robert-Yves

    2014-01-01

    Bent spine syndrome (BSS), defined as an abnormal forward flexion of the trunk resolving in supine position, is usually related to parkinsonism, but can also be encountered in myopathies. This study evaluates whole-body muscle MRI (WB-mMRI) as a tool for detecting underlying myopathy in non-extrapyramidal BSS. Forty-three patients (90 % women; 53-86 years old) with a non-extrapyramidal BSS were prospectively included. All underwent a 1.5-T WB-mMRI and a nerve conduction study. Muscle biopsy was performed if a myopathy could not be eliminated based on clinical examination and all tests. Systematic MRI interpretation focused on peripheral and axial muscle injury; spinal posture and incidental findings were also reported. WB-mMRI was completed for all patients, with 13 muscle biopsies ultimately needed and myopathy revealed as the final etiological diagnosis in five cases (12 %). All biopsy-proven myopathies were detected by the WB-mMRI. Relevant incidental MRI findings were made in seven patients. This study supports WB-mMRI as a sensitive and feasible tool for detecting myopathy in BSS patients. Associated with electroneuromyography, it can better indicate when a muscle biopsy is needed and guide it when required. Rigorous radiological interpretation is mandatory, so as not to miss incidental findings of clinical consequence. (orig.)

  10. Conformational study of a bent-core liquid crystal: 13C NMR and DFT computation approach.

    Science.gov (United States)

    Dong, Ronald Y; Marini, Alberto

    2009-10-29

    A detailed conformational study is carried out by means of density functional theory (DFT) on a bent-core mesogen (A131) in order to shed light on its uniaxial-biaxial nematic phase transition. The most probable conformational states for this V-shaped core are found, from the potential energy surface (PES) of a five-ring model of A131, to fall into two distinct structural groups, namely, the banana-shaped and the hockey-stick-shaped forms. The chemical shielding tensors (CSTs) of the aromatic carbons, for the four prevalent conformers, have been calculated using the GIAO-DFT approach. The derived CSTs are found to compare well with the chemical shift anisotropy (CSA) tensors measured by the 2D-NMR SUPER technique. The CSA tensors are then used to aid the assignment of the aromatic carbon peaks, and the observed (13)C chemical shifts from its nematic phases are revisited to provide new structural and local orientational order parameters. In light of the conformational states found from the in vacuo DFT calculations, the "average" configuration shapes of the A131 molecule are found to be different in the nematic phases based on their new local order parameters S and D of the aromatic rings.

  11. Analysis of mitochondrial mechanical dynamics using a confocal fluorescence microscope with a bent optical fibre.

    Science.gov (United States)

    Li, Yongbo; Honda, Satoshi; Iwami, Kentaro; Ohta, Yoshihiro; Umeda, Norihiro

    2015-11-01

    The cells in the cardiovascular system are constantly subjected to mechanical forces created by blood flow and the beating heart. The effect of forces on cells has been extensively investigated, but their effect on cellular organelles such as mitochondria remains unclear. We examined the impact of nano-Newton forces on mitochondria using a bent optical fibre (BOF) with a flat-ended tip (diameter exceeding 2 μm) and a confocal fluorescence microscope. By indenting a single mitochondrion with the BOF tip, we found that the mitochondrial elastic modulus was proportional to the (-1/2) power of the mitochondrial radius in the 9.6-115 kPa range. We stained the mitochondria with a potential-metric dye (TMRE) and measured the changes in TMRE fluorescence intensity. We confirmed that more active mitochondria exhibit a higher frequency of repetitive transient depolarization. The same trend was observed at forces lower than 50 nN. We further showed that the depolarization frequency of mitochondria decreases under an extremely large force (nearly 100 nN). We conclude that mitochondrial function is affected by physical environmental factors, such as external forces at the nano-Newton level. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  12. Whole-body muscle MRI to detect myopathies in non-extrapyramidal bent spine syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Ohana, Mickael [Nouvel Hopital Civil - Hopitaux Universitaires de Strasbourg, Service de Radiologie B, Strasbourg (France); Durand, Marie-Christine [AP-HP - Hopital Raymond Poincare, Service de Neurologie, Garches (France); Marty, Catherine; Lazareth, Jean-Philippe [AP-HP - Hopital Raymond Poincare, Service de Rhumatologie, Garches (France); Maisonobe, Thierry [APH-HP - Hopital de la Pitie-Salpetriere, Service de Neuropathologie, Paris (France); Mompoint, Dominique; Carlier, Robert-Yves [AP-HP - Hopital Raymond Poincare, Service de Radiologie, Garches (France)

    2014-08-15

    Bent spine syndrome (BSS), defined as an abnormal forward flexion of the trunk resolving in supine position, is usually related to parkinsonism, but can also be encountered in myopathies. This study evaluates whole-body muscle MRI (WB-mMRI) as a tool for detecting underlying myopathy in non-extrapyramidal BSS. Forty-three patients (90 % women; 53-86 years old) with a non-extrapyramidal BSS were prospectively included. All underwent a 1.5-T WB-mMRI and a nerve conduction study. Muscle biopsy was performed if a myopathy could not be eliminated based on clinical examination and all tests. Systematic MRI interpretation focused on peripheral and axial muscle injury; spinal posture and incidental findings were also reported. WB-mMRI was completed for all patients, with 13 muscle biopsies ultimately needed and myopathy revealed as the final etiological diagnosis in five cases (12 %). All biopsy-proven myopathies were detected by the WB-mMRI. Relevant incidental MRI findings were made in seven patients. This study supports WB-mMRI as a sensitive and feasible tool for detecting myopathy in BSS patients. Associated with electroneuromyography, it can better indicate when a muscle biopsy is needed and guide it when required. Rigorous radiological interpretation is mandatory, so as not to miss incidental findings of clinical consequence. (orig.)

  13. Variance reduction techniques for 14 MeV neutron streaming problem in rectangular annular bent duct

    Energy Technology Data Exchange (ETDEWEB)

    Ueki, Kotaro [Ship Research Inst., Mitaka, Tokyo (Japan)

    1998-03-01

    Monte Carlo method is the powerful technique for solving wide range of radiation transport problems. Its features are that it can solve the Boltzmann`s transport equation almost without approximation, and that the complexity of the systems to be treated rarely becomes a problem. However, the Monte Carlo calculation is always accompanied by statistical errors called variance. In shielding calculation, standard deviation or fractional standard deviation (FSD) is used frequently. The expression of the FSD is shown. Radiation shielding problems are roughly divided into transmission through deep layer and streaming problem. In the streaming problem, the large difference in the weight depending on the history of particles makes the FSD of Monte Carlo calculation worse. The streaming experiment in the 14 MeV neutron rectangular annular bent duct, which is the typical streaming bench mark experiment carried out of the OKTAVIAN of Osaka University, was analyzed by MCNP 4B, and the reduction of variance or FSD was attempted. The experimental system is shown. The analysis model by MCNP 4B, the input data and the results of analysis are reported, and the comparison with the experimental results was examined. (K.I.)

  14. High-resolution bent-crystal spectrometer for the ultra-soft x-ray region

    International Nuclear Information System (INIS)

    Beiersdorfer, P.; von Goeler, S.; Bitter, M.; Hill, K.W.; Hulse, R.A.; Walling, R.S.

    1988-10-01

    A multichannel vacuum Brag-crystal spectrometer has been developed for high-resolution measurements of the line emission from tokamak plasmas in the wavelength region between 4 and 25 /angstrom/. The spectrometer employs a bent crystal in Johann geometry and a microchannel-plate intensified photodiode array. The instrument is capable of measuring high-resolution spectra (λ/Δλ ∼ 3000) with fast time resolution (4 msec per spectrum) and good spatial resolution (3 cm). The spectral bandwidth is Δλ/λ 0 = 8/angstrom/. A simple tilt mechanism allows access to different wavelength intervals. In order to illustrate the utility of the new spectrometer, time- and space-resolved measurements of the n = 3 to n = 2 spectrum of selenium from the Princeton Large Torus tokamak plasmas are presented. The data are used to determine the plasma transport parameters and to infer the radial distribution of fluorinelike, neonlike, and sodiumlike ions of selenium in the plasma. The new ultra-soft x-ray spectrometer has thus enabled us to demonstrate the utility of high-resolution L-shell spectroscopy of neonlike ions as a fusion diagnostic. 43 refs., 23 figs

  15. Flexoelectricity of a Calamitic Liquid Crystal Elastomer Swollen with a Bent-core Liquid Crystal

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, M.; Verduzco, R; Gleeson, J; Sprunt, S; Jakli, A

    2009-01-01

    We have measured the electric current induced by mechanical distortion of a calamitic liquid crystal elastomer (LCE) swollen with a low molecular weight bent-core nematic (BCN) liquid crystal, and have determined, for the first time, the bend flexoelectric coefficient e{sub 3} of such a BCN-LCE composite. In one method, we utilize air-pressure to induce a mechanical bend deformation and flexoelectric polarization in a BCN-LCE film, and then measure the polarization current as a function of time. An alternative technique uses a rotary-motor driven scotch yoke to periodically flex the BCN-LCE; in this case, the magnitude and phase of the induced current are recorded via a lock-in amplifier. The flexoelectric coefficient, e{sub 3}, was found to be {approx}20 nC/cm{sup 2}, and is stable in magnitude from room temperature to {approx}65 C. It is about one third the value measured in samples of the pure BCN; this fraction corresponds closely to the molar concentration of BCN in the LCE. The flexoelectric current increases linearly with the magnitude of the bend deformation and decays with frequency. These observations indicate a promising way forward towards producing very low-cost, self-standing, rugged electromechanical energy conversion devices.

  16. Physical properties of a bent-core nematic liquid crystal and its mixtures with calamitic molecules

    Science.gov (United States)

    Buka, Á.; Éber, N.; Fodor-Csorba, K.; Jákli, A.; Salamon, P.

    2012-10-01

    This article summarizes the results obtained by various experimental methods on the physical properties of a bent-core nematic liquid crystal 4-chloro-1,3-phenylene bis-4-[4‧-(9-decenyloxy) benzoyloxy] benzoate (ClPbis10BB). The material exhibits unusual properties in all aspects tested. Its bend flexoelectric coefficient is 1000 times larger than in calamitics; it is viscoelastic with a large, shear-rate-dependent viscosity. Its bend and twist elastic constants are abnormally low; thus the nematic phase can be rendered to be a blue fog phase with a small amount of chiral dopant. It shows very high flow birefringence and unusually small leading Landau coefficient. It has two types of isotropic phases; at lower temperature it is probably tetrahedratic that can be transferred into the nematic phase with magnetic field. ClPbis10BB has a frequency-dependent conductivity anisotropy which is characterized by a double sign inversion. It exhibits various electroconvection (EC) patterns which are currently not understood in the frame of the standard theory of EC.

  17. Standard practice for preparation and use of Bent-Beam stress-corrosion test specimens

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This practice covers procedures for designing, preparing, and using bent-beam stress-corrosion specimens. 1.2 Different specimen configurations are given for use with different product forms, such as sheet or plate. This practice applicable to specimens of any metal that are stressed to levels less than the elastic limit of the material, and therefore, the applied stress can be accurately calculated or measured (see Note 1). Stress calculations by this practice are not applicable to plastically stressed specimens. Note 1—It is the nature of these practices that only the applied stress can be calculated. Since stress-corrosion cracking is a function of the total stress, for critical applications and proper interpretation of results, the residual stress (before applying external stress) or the total elastic stress (after applying external stress) should be determined by appropriate nondestructive methods, such as X-ray diffraction (1). 1.3 Test procedures are given for stress-corrosion testing by ex...

  18. Variance reduction techniques for 14 MeV neutron streaming problem in rectangular annular bent duct

    International Nuclear Information System (INIS)

    Ueki, Kotaro

    1998-01-01

    Monte Carlo method is the powerful technique for solving wide range of radiation transport problems. Its features are that it can solve the Boltzmann's transport equation almost without approximation, and that the complexity of the systems to be treated rarely becomes a problem. However, the Monte Carlo calculation is always accompanied by statistical errors called variance. In shielding calculation, standard deviation or fractional standard deviation (FSD) is used frequently. The expression of the FSD is shown. Radiation shielding problems are roughly divided into transmission through deep layer and streaming problem. In the streaming problem, the large difference in the weight depending on the history of particles makes the FSD of Monte Carlo calculation worse. The streaming experiment in the 14 MeV neutron rectangular annular bent duct, which is the typical streaming bench mark experiment carried out of the OKTAVIAN of Osaka University, was analyzed by MCNP 4B, and the reduction of variance or FSD was attempted. The experimental system is shown. The analysis model by MCNP 4B, the input data and the results of analysis are reported, and the comparison with the experimental results was examined. (K.I.)

  19. The oogenic cycle of the Caspian bent-toed gecko, Cyrtopodion caspium (Squamata: Gekkonidae in Iran

    Directory of Open Access Journals (Sweden)

    Vida Hojati

    2013-07-01

    Full Text Available The Caspian bent-toed gecko, Cyrtopodion caspium, is one of the commonest lizards in northern Iran. It is nocturnal, anthropophile and oviparous. In this study, the reproductive cycle of this species was studied by focusing on oogenesis, from April 5 to October 20, 2011. In total, 70 adult females were obtained from Mazandaran, one of the northern provinces of Iran where the climate is temperate. Ovaries were removed and processed for histological and morphometric studies. The results show that oocyte growth starts in late April and ends in August. Mating starts in spring, especially at the beginning of May, with oviposition occurring from late May to mid August. Females lay 1-2 eggs per clutch with the possibility of producing a secondary clutch later in the season. Maximum reproductive activity occurs in May and peaks in June. There was no significant difference between right and left side of reproductive system. With oogenesis occurring from April through July, C. caspium follows an oogenic cycle typical for temperate species.

  20. X-ray interferometer with bent gratings: Towards larger fields of view

    International Nuclear Information System (INIS)

    Revol, Vincent; Kottler, Christian; Kaufmann, Rolf; Jerjen, Iwan; Luethi, Thomas; Cardot, Francis; Niedermann, Philippe; Straumann, Ulrich; Sennhauser, Urs; Urban, Claus

    2011-01-01

    Recently, a Talbot-Lau interferometer was proposed to achieve phase contrast and dark field imaging in the hard X-rays domain (10-100 keV). This technique attracts much interest since it does not impose strong requirements on the coherence of the radiation while being sensitive to small phase changes of the beam. However, the limited size of the field of view, some centimeters, prevents its use in many applications where large objects have to be investigated. In the following article, the authors investigate a solution to extend the size of the field of view. After introducing the fundamental limitation on the size of the field of view, a Talbot-Lau interferometer with gratings bent on a cylindrical form is proposed and demonstrated in a compact (60 cm-long) configuration. A significant improvement of the performance could be achieved in comparison to the standard geometry. The theoretical limit imposed by the non-perpendicular angular incidence can thus be practically overcome and large fields of view become realistic. The authors envision a significant impact for high resolution phase sensitive imaging and/or industrial systems.

  1. X-ray interferometer with bent gratings: Towards larger fields of view

    Energy Technology Data Exchange (ETDEWEB)

    Revol, Vincent, E-mail: vincent.revol@csem.ch [Photonics Division, CSEM SA, Technoparkstr. 1, 8005 Zuerich (Switzerland); Physics Institute, University of Zuerich, Winterthurerstr. 190, 8057 Zuerich (Switzerland); Kottler, Christian; Kaufmann, Rolf [Photonics Division, CSEM SA, Technoparkstr. 1, 8005 Zuerich (Switzerland); Jerjen, Iwan; Luethi, Thomas [Laboratory for Electronics/Metrology/Reliability, Swiss Federal Laboratories for Materials Testing and Research, Uberlandstr. 129, 8600 Duebendorf (Switzerland); Cardot, Francis; Niedermann, Philippe [Microsystems Technology, CSEM SA, Rue Jaquet-Droz 1, 2002 Neuchatel (Switzerland); Straumann, Ulrich [Physics Institute, University of Zuerich, Winterthurerstr. 190, 8057 Zuerich (Switzerland); Sennhauser, Urs [Laboratory for Electronics/Metrology/Reliability, Swiss Federal Laboratories for Materials Testing and Research, Uberlandstr. 129, 8600 Duebendorf (Switzerland); Urban, Claus [Photonics Division, CSEM SA, Technoparkstr. 1, 8005 Zuerich (Switzerland)

    2011-08-21

    Recently, a Talbot-Lau interferometer was proposed to achieve phase contrast and dark field imaging in the hard X-rays domain (10-100 keV). This technique attracts much interest since it does not impose strong requirements on the coherence of the radiation while being sensitive to small phase changes of the beam. However, the limited size of the field of view, some centimeters, prevents its use in many applications where large objects have to be investigated. In the following article, the authors investigate a solution to extend the size of the field of view. After introducing the fundamental limitation on the size of the field of view, a Talbot-Lau interferometer with gratings bent on a cylindrical form is proposed and demonstrated in a compact (60 cm-long) configuration. A significant improvement of the performance could be achieved in comparison to the standard geometry. The theoretical limit imposed by the non-perpendicular angular incidence can thus be practically overcome and large fields of view become realistic. The authors envision a significant impact for high resolution phase sensitive imaging and/or industrial systems.

  2. Manufacturing of advanced bent crystals for Laue Optics for Gamma ObservationS (LOGOS)

    Science.gov (United States)

    Mazzolari, Andrea; Camattari, Riccardo; Bellucci, Valerio; Paternò, Gianfranco; Scian, Carlo; Mattei, Giovanni; Guidi, Vincenzo

    2015-07-01

    X- and γ-ray detection is currently a hot topic for a wide scientific community, spanning from astrophysics to nuclear medicine. However, lack of optics capable of focusing photons of energies in the energy range 0.1-1 MeV leaves the photon detection to a direct-view approach, resulting in a limited efficiency and resolution. The main scope of the INFN-LOGOS project is the development of technologies that enable manufacturing highly performing optical elements to be employed in the realization of hard X-ray lenses. Such lenses, typically named Laue lenses, consist of an ensemble of crystals disposed in concentric rings in order to diffract the incident radiation towards the focus of the lens, where a detector is placed. In particular, the INFN-LOGOS project aims at the realization of intrinsically bent silicon and germanium crystals exploiting the quasi-mosaic effect for focusing hard X-rays. Crystal manufacturing relies on a proper revisitation of techniques typically employed in silicon micromachining, such as thin film deposition and patterning or ion implantation.

  3. Comparative results on collimation of the SPS beam of protons and Pb ions with bent crystals

    CERN Document Server

    Scandale, W.; Assmann, R.; Bracco, C.; Cerutti, F.; Christiansen, J.; Gilardoni, S.; Laface, E.; Losito, R.; Masi, A.; Metral, E.; Mirarchi, D.; Montesano, S.; Previtali, V.; Redaelli, S.; Valentino, G.; Schoofs, P.; Smirnov, G.; Tlustos, L.; Bagli, E.; Baricordi, S.; Dalpiaz, P.; Guidi, V.; Mazzolari, A.; Vincenzi, D.; Dabagov, S.; Murtas, F.; Carnera, A.; Della Mea, G.; De Salvador, D.; Lombardi, A.; Lytovchenko, O.; Tonezzer, M.; Cavoto, G.; Ludovici, L.; Santacesaria, R.; Valente, P.; Galluccio, F.; Afonin, A.G.; Bulgakov, M.K.; Chesnokov, Yu.A.; Maisheev, V.A.; Yazynin, I.A.; Kovalenko, A.D.; Taratin, A.M.; Uzhinskiy, V.V.; Gavrikov, Yu.A.; Ivanov, Yu.M.; Lapina, L.P.; Skorobogatov, V.V.; Ferguson, W.; Fulcher, J.; Hall, G.; Pesaresi, M.; Raymond, M.; Rose, A.; Ryan, M.; Zorba, O.; Robert-Demolaize, G.; Markiewicz, T.; Oriunno, M.; Wienands, U.

    2011-01-01

    New experiments on crystal assisted collimation have been carried out at the CERN SPS with stored beams of 120 Gev/c protons and Pb ions. Bent silicon crystals of 2 mm long with about 170 mu rad bend angle and a small residual torsion were used as primary collimators. In channeling conditions, the beam loss rate induced by inelastic interactions of particles with the crystal nuclei is minimal. The loss reduction was about 6 for protons and about 3 for Pb ions. Lower reduction value for Pb ions can be explained by their considerably larger ionization losses in the crystal. In one of the crystals, the measured fraction of the Pb ion beam halo deflected in channeling conditions was 74\\%, a value very close to that for protons. The intensity of the off-momentum halo leaking out from the collimation station was measured in the first high dispersion area downstream. The particle population in the shadow of the secondary collimator-absorber was considerably smaller in channeling conditions than for amorphous orienta...

  4. Conversion of methane to methanol with a bent mono(μ-oxo)dinickel anchored on the internal surfaces of micropores.

    Science.gov (United States)

    Shan, Junjun; Huang, Weixin; Nguyen, Luan; Yu, Ying; Zhang, Shiran; Li, Yuanyuan; Frenkel, Anatoly I; Tao, Franklin Feng

    2014-07-22

    The oxidation of methane to methanol is a pathway to utilizing this relatively abundant, inexpensive energy resource. Here we report a new catalyst, bent mono(μ-oxo)dinickel anchored on an internal surface of micropores,which is active for direct oxidation. It is synthesized from the direct loading of a nickel precursor to the internal surface of micropores of ZSM5 following activation in O2. Ni 2p3/2 of this bent mono(μ-oxo)dinickel species formed on the internal surface of ZSM5 exhibits a unique photoemission feature, which distinguishes the mono(μ-oxo)dinickel from NiO nanoparticles. The formation of the mono(μ-oxo)dinickel species was confirmed with X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). This mono(μ-oxo)dinickel species is active for the direct oxidation of methane to methanol under the mild condition of a temperature as low as 150 °C in CH4 at 1 bar. In-situ studies using UV-vis, XANES, and EXAFS suggest that this bent mono(μ-oxo)dinickel species is the active site for the direct oxidation of methane to methanol. The energy barrier of this direct oxidation of methane is 83.2 kJ/mol.

  5. Comparison of photon organ and effective dose coefficients for PIMAL stylized phantom in bent positions in standard irradiation geometries.

    Science.gov (United States)

    Dewji, Shaheen; Reed, K Lisa; Hiller, Mauritius

    2017-08-01

    Computational phantoms with articulated arms and legs have been constructed to enable the estimation of radiation dose in different postures. Through a graphical user interface, the Phantom wIth Moving Arms and Legs (PIMAL) version 4.1.0 software can be employed to articulate the posture of a phantom and generate a corresponding input deck for the Monte Carlo N-Particle (MCNP) radiation transport code. In this work, photon fluence-to-dose coefficients were computed using PIMAL to compare organ and effective doses for a stylized phantom in the standard upright position with those for phantoms in realistic work postures. The articulated phantoms represent working positions including fully and half bent torsos with extended arms for both the male and female reference adults. Dose coefficients are compared for both the upright and bent positions across monoenergetic photon energies: 0.05, 0.1, 0.5, 1.0, and 5.0 MeV. Additionally, the organ doses are compared across the International Commission on Radiological Protection's standard external radiation exposure geometries: antero-posterior, postero-anterior, left and right lateral, and isotropic (AP, PA, LLAT, RLAT, and ISO). For the AP and PA irradiation geometries, differences in organ doses compared to the upright phantom become more profound with increasing bending angles and have doses largely overestimated for all organs except the brain in AP and bladder in PA. In LLAT and RLAT irradiation geometries, energy deposition for organs is more likely to be underestimated compared to the upright phantom, with no overall change despite increased bending angle. The ISO source geometry did not cause a significant difference in absorbed organ dose between the different phantoms, regardless of position. Organ and effective fluence-to-dose coefficients are tabulated. In the AP geometry, the effective dose at the 45° bent position is overestimated compared to the upright phantom below 1 MeV by as much as 27% and 82% in the 90

  6. Comparison of photon organ and effective dose coefficients for PIMAL stylized phantom in bent positions in standard irradiation geometries

    Energy Technology Data Exchange (ETDEWEB)

    Dewji, Shaheen; Hiller, Mauritius [Oak Ridge National Laboratory, Center for Radiation Protection Knowledge, Environmental Sciences Division, Oak Ridge, TN (United States); Reed, K.L. [Georgia Institute of Technology, Nuclear and Radiological Engineering Program, Atlanta, GA (United States)

    2017-08-15

    Computational phantoms with articulated arms and legs have been constructed to enable the estimation of radiation dose in different postures. Through a graphical user interface, the Phantom wIth Moving Arms and Legs (PIMAL) version 4.1.0 software can be employed to articulate the posture of a phantom and generate a corresponding input deck for the Monte Carlo N-Particle (MCNP) radiation transport code. In this work, photon fluence-to-dose coefficients were computed using PIMAL to compare organ and effective doses for a stylized phantom in the standard upright position with those for phantoms in realistic work postures. The articulated phantoms represent working positions including fully and half bent torsos with extended arms for both the male and female reference adults. Dose coefficients are compared for both the upright and bent positions across monoenergetic photon energies: 0.05, 0.1, 0.5, 1.0, and 5.0 MeV. Additionally, the organ doses are compared across the International Commission on Radiological Protection's standard external radiation exposure geometries: antero-posterior, postero-anterior, left and right lateral, and isotropic (AP, PA, LLAT, RLAT, and ISO). For the AP and PA irradiation geometries, differences in organ doses compared to the upright phantom become more profound with increasing bending angles and have doses largely overestimated for all organs except the brain in AP and bladder in PA. In LLAT and RLAT irradiation geometries, energy deposition for organs is more likely to be underestimated compared to the upright phantom, with no overall change despite increased bending angle. The ISO source geometry did not cause a significant difference in absorbed organ dose between the different phantoms, regardless of position. Organ and effective fluence-to-dose coefficients are tabulated. In the AP geometry, the effective dose at the 45 bent position is overestimated compared to the upright phantom below 1 MeV by as much as 27% and 82% in the

  7. X-ray diagnostics of He-like titanium with the bent crystal spectrometer on FTU

    International Nuclear Information System (INIS)

    Leigheb, M.

    1999-01-01

    X-ray spectra due to intrinsic Titanium are obtained on the FTU tokamak by using a space resolved bent crystal spectrometer. In a single discharge, spectra along five lines of sight with a maximum of 16 acquisitions at different times are recorded. Line identification is straightforward from previously published Ti spectra, and no wavelength disagreement (within the experimental errors) has been observed. To fit the spectra, three different methods are tested, each having as free parameters the background level, position (i.e. channel number of the peak) intensity and width of the resonance w line, and line intensity ratios of the satellites with respect to the resonance. Many information can be deduced from the results of the fit: ion and electron temperatures, He-like/Li-like ion charge ratio. Titanium density in the plasma core. Synthetic spectra built up with the values calculated by the fits are compared with the experimental data, and the temperature values are compared with the values from other diagnostics. The best agreement for ion and electron temperatures is obtained by simultaneous fitting of the resonance with 29 most prominent resolved and unresolved satellites; intensities of the dielectronic satellites have been calculated with the Boltzmann-Saha equation, while intensities of intercombination lines x and y and forbidden line z have been calculated with the Mewe's formula. For the dielectronic satellites as well as for intercombination lines, simulations are satisfactory, whereas for the forbidden line z the simulated lines are only 15-30% of the corresponding experimental values. A comparison of the resonance peak positions in different lines of sight allowed to exclude poloidal plasma rotation velocities > 2 10 4 m/s [it

  8. High-resolution study of x-rays emitted from highly charged S ions using a bent-crystal spectrometer

    Science.gov (United States)

    Kasthurirangan, S.; Banerjee, A.; Kumar, A.; Agnihotri, A. N.; Misra, D.; Tribedi, L. C.

    2013-09-01

    We have measured the projectile x-rays from 56 MeV sulphur ions in collision with thin carbon foils using a high-resolution bent-crystal spectrometer. The resolution of the spectrometer is good enough to resolve lines arising from transitions in H-, He- and Li-like ions. The line energies are compared with values from the NIST x-ray database. The data have also been used to generate the approximate equilibrium charge state distribution, which is compared with semi-empirical model predictions.

  9. The crucial role of the f electrons in the bent or linear configuration of uranium cyanido metallocenes

    International Nuclear Information System (INIS)

    Maynadie, J.; Berthet, J.C.; Thuery, P.; Ephritikhine, M.; Maron, L.; Barros, N.

    2007-01-01

    Here is reported on the U III -U V complexes [Cp * 2 U(CN) 3 ][NR 4 ] n (n=1,2) and [Cp * 2 U(CN) 5 ][NR 4 ] n (n=2,3), which adopt a bent and linear configuration, respectively. These results raise the fundamental question of the nature of the metal-ligand interaction and the influence of the number of f electrons on the geometry of the complexes. The crucial role of the f orbitals is evidenced by density functional theory (DFT) analysis. (O.M.)

  10. Statistical mechanics of bend flexoelectricity and the twist-bend phase in bent-core liquid crystals.

    Science.gov (United States)

    Shamid, Shaikh M; Dhakal, Subas; Selinger, Jonathan V

    2013-05-01

    We develop a Landau theory for bend flexoelectricity in liquid crystals of bent-core molecules. In the nematic phase of the model, the bend flexoelectric coefficient increases as we reduce the temperature toward the nematic to polar phase transition. At this critical point, there is a second-order transition from high-temperature uniform nematic phase to low-temperature nonuniform polar phase composed of twist-bend or splay-bend deformations. To test the predictions of Landau theory, we perform Monte Carlo simulations to find the director and polarization configurations as functions of temperature, applied electric field, and interaction parameters.

  11. High-Temperature Isomerization of Benzenoid Polycyclic Aromatic Hydrocarbons. Analysis through the Bent Bond and Antiperiplanar Hypothesis Orbital Model.

    Science.gov (United States)

    Parent, Jean-François; Deslongchamps, Pierre

    2018-03-16

    L. T. Scott has discovered the 1,2-swapping of carbon and hydrogen atoms which is known to take place on benzenoid aromatics (up to ∼1000 °C range). For example, 13 C-1-naphthalene is specifically converted to 13 C-2-naphthalene, and there is evidence that this occurs through the formation of benzofulvene and a naphthalene-carbene intermediate. Application of the bent bond/antiperiplanar hypothesis leads to the postulate that higher in energy pyramidal singlet diradical intermediates can be used to propose a mechanism that rationalizes various atom rearrangements on benzenoid aromatics and related isomeric compounds.

  12. Spectral algorithms for multiple scale localized eigenfunctions in infinitely long, slightly bent quantum waveguides

    Science.gov (United States)

    Boyd, John P.; Amore, Paolo; Fernández, Francisco M.

    2018-03-01

    A "bent waveguide" in the sense used here is a small perturbation of a two-dimensional rectangular strip which is infinitely long in the down-channel direction and has a finite, constant width in the cross-channel coordinate. The goal is to calculate the smallest ("ground state") eigenvalue of the stationary Schrödinger equation which here is a two-dimensional Helmholtz equation, ψxx +ψyy + Eψ = 0 where E is the eigenvalue and homogeneous Dirichlet boundary conditions are imposed on the walls of the waveguide. Perturbation theory gives a good description when the "bending strength" parameter ɛ is small as described in our previous article (Amore et al., 2017) and other works cited therein. However, such series are asymptotic, and it is often impractical to calculate more than a handful of terms. It is therefore useful to develop numerical methods for the perturbed strip to cover intermediate ɛ where the perturbation series may be inaccurate and also to check the pertubation expansion when ɛ is small. The perturbation-induced change-in-eigenvalue, δ ≡ E(ɛ) - E(0) , is O(ɛ2) . We show that the computation becomes very challenging as ɛ → 0 because (i) the ground state eigenfunction varies on both O(1) and O(1 / ɛ) length scales and (ii) high accuracy is needed to compute several correct digits in δ, which is itself small compared to the eigenvalue E. The multiple length scales are not geographically separate, but rather are inextricably commingled in the neighborhood of the boundary deformation. We show that coordinate mapping and immersed boundary strategies both reduce the computational domain to the uniform strip, allowing application of pseudospectral methods on tensor product grids with tensor product basis functions. We compared different basis sets; Chebyshev polynomials are best in the cross-channel direction. However, sine functions generate rather accurate analytical approximations with just a single basis function. In the down

  13. Dielectric and electro-optic studies of a bimesogenic liquid crystal composed of bent-core and calamitic units.

    Science.gov (United States)

    Balachandran, R; Panov, V P; Vij, J K; Shanker, G; Tschierske, C; Merkel, K; Kocot, A

    2014-09-01

    A bimesogen, BR1, composed of a bent-core and calamitic unit, linked laterally via a flexible spacer is investigated by dielectric and electro-optic techniques. X-ray results show the presence of clusters in the nematic phase, and the cluster size is of the order of the thickness of a single layer. The splitting of the small-angle scattering Δχ/2 is about 50°, which indicates SmC like clusters with a significant tilt of the molecules in the quasilayers. The sign reversal of the dielectric anisotropy Δε' is observed as a function of frequency; the behavior is rather similar to that exhibited by the conventional dual frequency nematics, composed of a calamitic mesogen, with the exception that it occurs at much lower frequencies in this material. Interestingly, as the bimesogen enters its nematic phase, the average permittivity decreases as the temperature is lowered. This indicates the onset of antiparallel association of some of the dipoles in the system, and this type of association is much more prominent in BR1 in comparison to other bent-core liquid crystalline systems composed of the same bisbenzoate core unit. The analysis of the dielectric spectra using the Maier-Meier model confirms the onset of an antiparallel correlation of dipoles occurring at the isotropic to nematic phase transition temperature. Additionally these results support a model of the cluster where the transverse dipole moments in the neighboring layers are antiparalleled to each other.

  14. Electronic Structure of the d Bent-metallocene Cp(2)VCl(2): A Photoelectron and Density Functional Study.

    Science.gov (United States)

    Cranswick, Matthew A; Gruhn, Nadine E; Enemark, John H; Lichtenberger, Dennis L

    2008-04-15

    The Cp(2)VCl(2) molecule is a prototype for bent metallocene complexes with a single electron in the metal d shell, but experimental measure of the binding energy of the d electron by photoelectron spectroscopy eluded early attempts due to apparent decomposition in the spectrometer to Cp(2)VCl. With improved instrumentation, the amount of decomposition is reduced and subtraction of ionization intensity due to Cp(2)VCl from the Cp(2)VCl(2)/Cp(2)VCl mixed spectrum yields the Cp(2)VCl(2) spectrum exclusively. The measured ionization energies provide well-defined benchmarks for electronic structure calculations. Density functional calculations support the spectral interpretations and agree well with the ionization energy of the d(1) electron and the energies of the higher positive ion states of Cp(2)VCl(2). The calculations also account well for the trends to the other Group V bent metallocene dichlorides Cp(2)NbCl(2) and Cp(2)TaCl(2). The first ionization energy of Cp(2)VCl(2) is considerably greater than the first ionization energies of the second- and third-row transition metal analogues.

  15. Fundamental distribution of stress corrosion crack depth on Type 316L stainless steels induced by creviced bent beam test

    International Nuclear Information System (INIS)

    Miyahara, Yuichi; Miura, Yasufumi; Kako, Kenji

    2014-01-01

    The creviced bent beam (CBB) test has been applied for many materials such as nickel base alloys and low carbon austenitic stainless steels. For sensitized austenitic stainless steels, fundamental distribution of crack depth induced by CBB tests was evaluated to establish SCC initiation model and lifetime prediction method. On the other hand, there are a few studies about distribution of crack depth on low carbon austenitic stainless steels. In this study, statistical analysis of crack depth was conducted in Type 316L stainless steels after CBB tests. The results are summarized as follows, (1) Distribution of grain boundary depth designated as distance from surface to triple point of grain boundary fit lognormal probability distribution and exponential probability distribution. (2) Distribution of crack depth approaches lognormal or exponential probability distribution with passage of test duration. Distribution of plastic strain on the specimen surface is not affect to type of crack depth distribution. (3) Inflection or bent point appears on the probability plot at depth of the median of grain boundary depth distribution. (4) Less than median of grain boundary depth, distribution of crack depth is identical to grain boundary depth distribution. More than median + standard deviation of grain boundary depth, crack depth distribution is described by the exponential distribution. (author)

  16. A patient with mandibular deviation and 3 mandibular incisors treated with asymmetrically bent improved superelastic nickel-titanium alloy wires.

    Science.gov (United States)

    Ikeda, Yuhei; Kokai, Satoshi; Ono, Takashi

    2018-01-01

    Skeletal and dental discrepancies cause asymmetric malocclusions in orthodontic patients. It is difficult to achieve adequate functional occlusion and guidance in patients with congenital absence of a mandibular incisor due to the tooth-size discrepancy. Here, we describe the orthodontic treatment of a 22-year-old woman with an asymmetric Angle Class II malocclusion, mandibular deviation to the left, and 3 mandibular incisors. The anterior teeth and maxillary canines were crowded. We used an improved superelastic nickel-titanium alloy wire (Tomy International, Tokyo, Japan) to compensate for the asymmetric mandibular arch and an asymmetrically bent archwire to move the maxillary molars distally. A skeletal anchorage system provided traction for intermaxillary elastics, and extractions were not needed. We alleviated the crowding and created an ideal occlusion with proper overjet, overbite, and anterior guidance with Class I canine and molar relationships. This method of treatment with an asymmetrically bent nickel-titanium alloy wire provided proper Class I occlusion and anterior guidance despite the mandibular deviation to the left and 3 mandibular incisors, without the need for extractions. Copyright © 2017 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  17. Electronic Structure of the d1 Bent-metallocene Cp2VCl2: A Photoelectron and Density Functional Study

    Science.gov (United States)

    Cranswick, Matthew A.; Gruhn, Nadine E.; Enemark, John H.; Lichtenberger, Dennis L.

    2009-01-01

    The Cp2VCl2 molecule is a prototype for bent metallocene complexes with a single electron in the metal d shell, but experimental measure of the binding energy of the d electron by photoelectron spectroscopy eluded early attempts due to apparent decomposition in the spectrometer to Cp2VCl. With improved instrumentation, the amount of decomposition is reduced and subtraction of ionization intensity due to Cp2VCl from the Cp2VCl2/Cp2VCl mixed spectrum yields the Cp2VCl2 spectrum exclusively. The measured ionization energies provide well-defined benchmarks for electronic structure calculations. Density functional calculations support the spectral interpretations and agree well with the ionization energy of the d1 electron and the energies of the higher positive ion states of Cp2VCl2. The calculations also account well for the trends to the other Group V bent metallocene dichlorides Cp2NbCl2 and Cp2TaCl2. The first ionization energy of Cp2VCl2 is considerably greater than the first ionization energies of the second- and third-row transition metal analogues. PMID:19593395

  18. Many-body quantum dynamics in the decay of bent dark solitons of Bose-Einstein condensates

    Science.gov (United States)

    Katsimiga, G. C.; Mistakidis, S. I.; Koutentakis, G. M.; Kevrekidis, P. G.; Schmelcher, P.

    2017-12-01

    The beyond mean-field (MF) dynamics of a bent dark soliton (BDS) embedded in a two-dimensional repulsively interacting Bose-Einstein condensate is explored. We examine the case of a single BDS comparing the MF dynamics to a correlated approach, the multi-configuration time-dependent Hartree method for bosons. Dynamical snaking of this bent structure is observed, signaling the onset of fragmentation which becomes significant during the vortex nucleation. In contrast to the MF approximation ‘filling’ of the vortex core is observed, leading in turn to the formation of filled-core vortices, instead of the MF vortex-antivortex pairs. The resulting smearing effect in the density is a rather generic feature, occurring when solitonic structures are exposed to quantum fluctuations. Here, we show that this filling owes its existence to the dynamical building of an antidark structure developed in the next-to-leading order orbital. We further demonstrate that the aforementioned beyond MF dynamics can be experimentally detected using the variance of single shot measurements. Additionally, a variety of excitations including vortices, oblique dark solitons, and open ring dark soliton-like structures building upon higher-lying orbitals is observed. We demonstrate that signatures of the higher-lying orbital excitations emerge in the total density, and can be clearly captured by inspecting the one-body coherence. In the latter context, the localization of one-body correlations exposes the existence of the multi-orbital vortex-antidark structure.

  19. Distribuição horizontal da macrofauna bentônica na praia do Cassino, extremo sul do Brasil

    Directory of Open Access Journals (Sweden)

    Luciano Peyrer das Neves

    2012-09-01

    Full Text Available A distribuição horizontal da macrofauna bentônica na praia do Cassino, Rio Grande do Sul, Brasil foi estudada durante o período de um ano (junho 2004 a maio de 2005 com base em coletas mensais. Foram escolhidos três locais, com 50 m de distância um do outro, sendo que em cada local foram fundeadas três transversais 2 m equidistantes. Cada transversal estendeu-se da base das dunas primárias até aproximadamente 1 m de profundidade no infralitoral. A distância dos níveis de coleta em cada transversal foi de 20 m até o limite superior da zona de varrido, a partir do qual a distância foi de 10 m. Em algumas ocasiões foi evidenciada variação espacial horizontal de alguns dos principais táxons, bem como da comunidade bentônica dentro de uma escala de 50 m e 100 m. Esta variação foi provavelmente reflexo da ação das marés meteorológicas que causam abrupta elevação do nível do mar.

  20. Focusing Bent Perfect-Crystal Neutron Monochromator -A Key to High-Resolution Stress/Strain Measurement Studies of Polycrystalline Materials-

    Czech Academy of Sciences Publication Activity Database

    Ono, M.; Mikula, Pavol; Harjo, S.; Šaroun, Jan; Yoneda, K.; Sawano, J.; Sakurai, Y.; Kobayashi, T.

    321/324, - (2000), s. 296-301 ISSN 0255-5476 R&D Projects: GA ČR GV202/97/K038 Keywords : focusing bent perfect-crystal * neutron monochromator * two-axis * neutron diffractometer with 1D PSD * stress/strain scanner Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.597, year: 2000

  1. The influence of layer curvature on switching in ferroelectric B.sub.2./sub. phases of liquid crystals having bent-shape molecules

    Czech Academy of Sciences Publication Activity Database

    Lejček, Lubor

    2012-01-01

    Roč. 39, č. 10 (2012), s. 1276-1283 ISSN 0267-8292 R&D Projects: GA ČR(CZ) GAP204/11/0723 Institutional research plan: CEZ:AV0Z10100520 Keywords : B 2 phase * bent-shaped molecules * layer modulation * chirality flipping Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.959, year: 2012

  2. Polarization splay as the origin of the modulation in the B1 and B7 smectic phases of bent-core molecules

    Czech Academy of Sciences Publication Activity Database

    Coleman, D.A.; Jones, C.D.; Nakata, M.; Clark, N.A.; Walba, D.M.; Weissflog, W.; Fodor-Csorba, K.; Watanabe, J.; Novotná, Vladimíra; Hamplová, Věra

    2008-01-01

    Roč. 77, č. 2 (2008), 021703/1-021703/6 ISSN 1539-3755 Grant - others:NSF MRSEC(US) DMR-0213918; NSF(US) DMR-0072989 Institutional research plan: CEZ:AV0Z10100520 Keywords : liquid crystals * bent-core molecules * polarization splay Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.508, year: 2008

  3. Photoinduced changes of surface topography in amorphous, liquid-crystalline, and crystalline films of bent-core azobenzene-containing substance

    Czech Academy of Sciences Publication Activity Database

    Bobrovsky, A.; Mochalov, K.; Oleinikov, V.; Solovyeva, D.; Shibaev, V.; Bogdanova, Y.; Hamplová, Věra; Kašpar, Miroslav; Bubnov, Alexej

    2016-01-01

    Roč. 120, č. 22 (2016), 5073-5082 ISSN 1520-6106 R&D Projects: GA ČR GA16-12150S; GA MŠk(CZ) LH15305 Institutional support: RVO:68378271 Keywords : liquid crystals * azo group * bent-shaped material * nematic * photo-optical behaviour Subject RIV: JJ - Other Materials Impact factor: 3.177, year: 2016

  4. Structural Diversity of Metallosupramolecular Assemblies Based on the Bent Bridging Ligand 4,4′-Dithiodipyridine

    Directory of Open Access Journals (Sweden)

    Rüdiger W. Seidel

    2013-05-01

    Full Text Available 4,4′-Dithiodipyridine (dtdp, also termed 4,4′-dipyridyldisulfide, is a bridging ligand of the 4,4′-bipyridine type. The introduction of the disulfide moiety inevitably leads to a relatively rigid angular structure, which exhibits axial chirality. More than 90 metal complexes containing the dtdp ligand have been crystallographically characterised until now. This review focuses on the preparation and structural diversity of discrete and polymeric metallosupramolecular assemblies constructed from dtdp as bridging ligands. These encompass metallamacrocycles with M2L2 topology and coordination polymers with periodicity in one or two dimensions. One-dimensional coordination polymers represent the vast majority of the metallosupramolecular structures obtained from dtdp. These include repeated rhomboids, zigzag, helical and arched chains among other types. In this contribution, we make an attempt to provide a comprehensive account of the structural data that are currently available for metallosupramolecular assemblies based on the bent bridging ligand dtdp.

  5. The Diet and Sexual Differences of the Caspian Bent-Toed Gecko, Tenuidactylus caspius (Squamata: Gekkonidae, in Northern Iran

    Directory of Open Access Journals (Sweden)

    Vida Hojati

    2014-01-01

    Full Text Available The Caspian bent-toed gecko, Tenuidactylus caspius, is one of the most common nocturnal lizards of Iran with widespread distribution especially in the northern provinces. This research was done in order to study the diet and sexual dimorphism of this species in Sari County from 5 May to 20 October. During this research, 40 specimens of them including 20 males and 20 females were studied for diet and 140 specimens including 70 adult males and 70 adult females were studied for sexual dimorphism. Prey items identified were insects that belong to 15 species of 8 families and 6 orders. The most common prey items were Culex pipiens and Musca domestica. There is no significant difference between diets of males and females. Results show that the adult males in addition of having the apparent femoral and preanal pores are heavier than females and have larger body, head, and tail length.

  6. Study of nanofluid forced convection heat transfer in a bent channel by means of lattice Boltzmann method

    Science.gov (United States)

    Ma, Yuan; Mohebbi, Rasul; Rashidi, M. M.; Yang, Zhigang

    2018-03-01

    In this paper, the laminar forced convection heat transfer of nanofluid through a bent channel was numerically investigated. The lattice Boltzmann method was used for solving the governing equations in the domain. The effect of different parameters such as Reynolds number (50 ≤ Re ≤ 150), vertical passage ratio (2.0 ≤ M ≤ 4.0), and nanoparticle solid volume fractions (Φ = 0, 0.01, 0.03, 0.05) are analyzed in terms of streamlines, isotherms, and local Nusselt numbers. It was concluded from this study that the local and average Nusselt number increased with increasing nanoparticle volume fraction regardless of Re and M. Moreover, the effect of the nanofluid concentration on the increment of heat transfer was more remarkable at higher values of the Reynolds number. Simulations show that by increasing the Reynolds number or decreasing the vertical passage ratio, the local and average Nusselt number increases.

  7. Performances of a bent-crystal spectrometer adapted to resonant x-ray emission measurements on gas-phase samples

    Energy Technology Data Exchange (ETDEWEB)

    Journel, Loiec; El Khoury, Lara; Marin, Thierry; Guillemin, Renaud; Carniato, Stephane; Avila, Antoine; Delaunay, Renaud; Hague, Coryn F.; Simon, Marc [Laboratoire de Chimie Physique-Matiere et Rayonnement, UPMC University of Paris 06, UMR 7614, F-75005 Paris (France) and Laboratoire de Chimie Physique-Matiere et Rayonnement, CNRS, UMR 7614, F-75005 Paris (France)

    2009-09-15

    We describe a bent-crystal spectrometer adapted to measure x-ray emission resulting from core-level excitation of gas-phase molecules in the 0.8-8 keV energy range. The spectrometer is based on the Johann principle, and uses a microfocused photon beam to provide high-resolution (resolving power of {approx}7500). A gas cell was designed to hold a high-pressure (300 mbar) sample of gas while maintaining a high vacuum (10{sup -9} mbar) in the chamber. The cell was designed to optimize the counting rate (2000 cts/s at the maximum of the Cl K{alpha} emission line), while minimizing self-absorption. Example of the K{alpha} emission lines of CH{sub 3}Cl molecules is presented to illustrate the capabilities of this new instrument.

  8. Influence of incoherent scattering on stochastic deflection of high-energy negative particle beams in bent crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kirillin, I.V. [Akhiezer Institute for Theoretical Physics, National Science Center ' ' Kharkov Institute of Physics and Technology' ' , Kharkov (Ukraine); Shul' ga, N.F. [Akhiezer Institute for Theoretical Physics, National Science Center ' ' Kharkov Institute of Physics and Technology' ' , Kharkov (Ukraine); V.N. Karazin Kharkov National University, Kharkov (Ukraine); Bandiera, L. [INFN Sezione di Ferrara, Ferrara (Italy); Guidi, V.; Mazzolari, A. [INFN Sezione di Ferrara, Ferrara (Italy); Universita degli Studi di Ferrara, Dipartimento di Fisica e Scienze della Terra, Ferrara (Italy)

    2017-02-15

    An investigation on stochastic deflection of high-energy negatively charged particles in a bent crystal was carried out. On the basis of analytical calculation and numerical simulation it was shown that there is a maximum angle at which most of the beam is deflected. The existence of a maximum, which is taken in the correspondence of the optimal radius of curvature, is a novelty with respect to the case of positively charged particles, for which the deflection angle can be freely increased by increasing the crystal length. This difference has to be ascribed to the stronger contribution of incoherent scattering affecting the dynamics of negative particles that move closer to atomic nuclei and electrons. We therefore identified the ideal parameters for the exploitation of axial confinement for negatively charged particle beam manipulation in future high-energy accelerators, e.g., ILC or muon colliders. (orig.)

  9. Breakdown of Shape Memory Effect in Bent Cu-Al-Ni Nanopillars: When Twin Boundaries Become Stacking Faults.

    Science.gov (United States)

    Liu, Lifeng; Ding, Xiangdong; Sun, Jun; Li, Suzhi; Salje, Ekhard K H

    2016-01-13

    Bent Cu-Al-Ni nanopillars (diameters 90-750 nm) show a shape memory effect, SME, for diameters D > 300 nm. The SME and the associated twinning are located in a small deformed section of the nanopillar. Thick nanopillars (D > 300 nm) transform to austenite under heating, including the deformed region. Thin nanopillars (D faults in the deformed region. No SME occurs and heating converts only the undeformed regions into austenite. The defect-rich, deformed region remains in the martensite phase even after prolonged heating in the stability field of austenite. A complex mixture of twins and stacking faults was found for diameters 130 nm < D < 300 nm. The size effect of the SME in Cu-Al-Ni nanopillars consists of an approximately linear reduction of the SME between 300 and 130 nm when the SME completely vanishes for smaller diameters.

  10. DNA barcoding of Vietnamese bent-toed geckos (Squamata: Gekkonidae: Cyrtodactylus) and the description of a new species.

    Science.gov (United States)

    Nguyen, Sang Ngoc; Yang, Jun-Xiao; Le, Thanh-Ngan Thi; Nguyen, Luan Thanh; Orlov, Nikolai L; Hoang, Chung Van; Nguyen, Truong Quang; Jin, Jie-Qiong; Rao, Ding-Qi; Hoang, Thao Ngoc; Che, Jing; Murphy, Robert W; Zhang, Ya-Ping

    2014-03-26

    Species of bent-toed gecko (Cyrtodactylus) in Vietnam have been described at a rate of nearly four species per year since 2007 mostly based on morphological data. A tool that guides species delimitation will accelerate the rate of documentation, and at a time when the recognition of species greatly benefits conservation. We use DNA barcoding using COI (550 bp) to re-examine the levels of genetic divergence and taxonomic status of 21 described species of Vietnamese bent-toed geckos. Tree-based analyses resolve all sampled species and identify potential undescribed taxa. Kimura 2-parameter genetic distances between the described species average 21.0±4.2% and range from 4.3% to 28.7%. Further, our analyses discover two potentially new species from Vietnam, two from Laos and one from China. Herein we describe the new species Cyrtodactylus puhuensis sp. nov. from Vietnam on the basis of both genetics and morphology. Genetically, it differs from the remaining species by an average K2P distance of 24.0±1.8%. Morphologically, the new species is diagnosed by its medium-size (snout-vent length 79.24 mm and tail length 82.59 mm, for the single known individual), in having a series of moderately enlarged transverse subcaudals and a series of moderately enlarged femoral scales that extend from precloacal scales, in possessing femoral scales without pores, with males having five precloacal pores, and in exhibiting 8 supralabials, 10 infralabials, 23 narrow subdigital lamellae on its fourth toe, and 36 transverse ventrals.

  11. Evaluation of Contact Friction in Fracture of Rotationally Bent Nitinol Endodontic Files

    Science.gov (United States)

    Haimed, Tariq Abu

    2011-12-01

    The high flexibility of rotary Nitinol (Ni-Ti) files has helped clinicians perform root canal treatments with fewer technical errors than seen with stainless steel files. However, intracanal file fracture can occur, compromising the outcome of the treatment. Ni-Ti file fracture incidence is roughly around 4% amongst specialists and higher amongst general practitioners. Therefore, eliminating or reducing this problem should improve patient care. The aim of this project was to isolate and examine the role of friction between files and the canal walls of the glass tube model, and bending-related maximum strain amplitudes, on Ni-Ti file lifetimes-tofracture in the presence of different irrigant solutions and file coatings. A specifically designed device was used to test over 300 electropolished EndoSequenceRTM Ni-Ti files for number of cycles to failure (NCF) in smooth, bent glass tube models at 45 and 60 degrees during dry, coated and liquid-lubricated rotation at 600rpm. Fractured files were examined under Scanning Electron Microscopy (SEM) afterwards. Four different file sizes 25.04, 25.06, 35.04, 35.06 (diameter in mm/taper %) and six surface modification conditions were used independently. These conditions included, three solutions; (1) a surfactant-based solution, Surface-Active-Displacement-Solution (SADS), (2) a mouth wash proven to remove biofilms, Delmopinol 1%(DEL), and (3) Bleach 6% (vol.%), the most common antibacterial endodontic irrigant solution. The conditions also included two low-friction silane-based coating groups, 3-Hepta-fluoroisopropyl-propoxymethyl-dichlorosilane (3-HEPT) and Octadecyltrichlorosilane (ODS), in addition to an as-received file control group (Dry). The coefficient of friction (CF) between the file and the canal walls for each condition was measured as well as the surface tension of the irrigant solutions and the critical surface tension of the coated and uncoated files by contact angle measurements. The radius of curvature and

  12. Effect of small variations in the refractive index of the ambient medium on the spectrum of a bent fibre-optic Fabry - Perot interferometer

    International Nuclear Information System (INIS)

    Kulchin, Yurii N; Vitrik, O B; Gurbatov, S O

    2011-01-01

    The phase of light propagating through a bent optical fibre is shown to depend on the refractive index of the medium surrounding the fibre cladding when there is resonance coupling between the guided core mode and cladding modes. This shifts the spectral maxima in the bent fibre-optic Fabry - Perot interferometer. The highest phase and spectral sensitivities achieved with this interferometer configuration are 0.71 and 0.077, respectively, and enable changes in the refractive index of the ambient medium down to 5×10 -6 to be detected. This makes the proposed approach potentially attractive for producing highly stable, precision refractive index sensors capable of solving a wide range of liquid refractometry problems.

  13. Effect of small variations in the refractive index of the ambient medium on the spectrum of a bent fibre-optic Fabry - Perot interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Kulchin, Yurii N; Vitrik, O B; Gurbatov, S O [Institute for Automation and Control Processes, Far-Eastern Branch, Russian Academy of Sciences, Vladivostok (Russian Federation)

    2011-09-30

    The phase of light propagating through a bent optical fibre is shown to depend on the refractive index of the medium surrounding the fibre cladding when there is resonance coupling between the guided core mode and cladding modes. This shifts the spectral maxima in the bent fibre-optic Fabry - Perot interferometer. The highest phase and spectral sensitivities achieved with this interferometer configuration are 0.71 and 0.077, respectively, and enable changes in the refractive index of the ambient medium down to 5 Multiplication-Sign 10{sup -6} to be detected. This makes the proposed approach potentially attractive for producing highly stable, precision refractive index sensors capable of solving a wide range of liquid refractometry problems.

  14. Development of resistance of Apera spica-venti (L. P. Beauv. (Loose silky-bent in Lower Saxony in 2013 - also increasingly against Pinoxaden

    Directory of Open Access Journals (Sweden)

    Wolber, Dirk Michael

    2014-02-01

    Full Text Available Herbicide resistance has increased dramatically all over the world. Especially North America, South America and Australia are affected. In the last few years also in Europe different active ingredient groups become more and more ineffectively. The risk of resistance is very high for the ACC-ase inhibitors (Group A, the photosynthese- inhibitors (Group C and by now also for the ALS - inhibitors (Group B. In almost every agricultural region of Lower Saxony the loose silky-bent grass (Apera spica-venti shows resistance to at least one mode of action. Since 2005 especially in the lower saxonian region between Osnabrück, Hannover and Braunschweig resistance in loose silky-bent grass against the ALS- inhibitors occurs. 2012 target site resistance against Pinoxaden was found for the first time. In the last few years also in Europe different active ingredient groups became more and more ineffectively.

  15. A simple criterion for determining the static friction force between nanowires and flat substrates using the most-bent-state method.

    Science.gov (United States)

    Hou, Lizhen; Wang, Shiliang; Huang, Han

    2015-04-24

    A simple criterion was developed to assess the appropriateness of the currently available models that estimate the static friction force between nanowires and substrates using the 'most-bent-state' method. Our experimental testing of the static friction force between Al2O3 nanowires and Si substrate verified our theoretical analysis, as well as the establishment of the criterion. It was found that the models are valid only for the bent nanowires with the ratio of wire length over the minimum curvature radius [Formula: see text] no greater than 1. For the cases with [Formula: see text] greater than 1, the static friction force was overestimated as it neglected the effect of its tangential component.

  16. Deflection of 400  GeV/c proton beam with bent silicon crystals at the CERN Super Proton Synchrotron

    CERN Document Server

    Scandale, Walter; Della Mea, Gianantonio; De Salvador, Davide; Milan, Riccardo; Vomiero, Alberto; Baricordi, Stefano; Dalpiaz, Pietro; Fiorini, Massimiliano; Guidi, Vincenzo; Martinelli, Giuliano; Mazzolari, Andrea; Milan, Emiliano; Ambrosi, Giovanni; Azzarello, Philipp; Battiston, Roberto; Bertucci, Bruna; Burger, William J; Ionica, Maria; Zuccon, Paolo; Cavoto, Gianluca; Santacesaria, Roberta; Valente, Paolo; Vallazza, Erik; Afonin, Alexander G; Baranov, Vladimir T; Chesnokov, Yury A; Kotov, Vladilen I; Maisheev, Vladimir A; Yazynin, Igor A; Afanasiev, Sergey V; Kovalenko, Alexander D; Taratin, Alexander M; Denisov, Alexander S; Gavrikov, Yury A; Ivanov,Yuri M; Ivochkin, Vladimir G; Kosyanenko, Sergey V; Petrunin, Anatoli A; Skorobogatov, Vyacheslav V; Suvorov, Vsevolod M; Bolognini, Davide; Foggetta, Luca; Hasan, Said; Prest, Michela

    2008-01-01

    This paper presents a detailed study of the deflection phenomena of a 400  GeV/c proton beam impinging on a new generation of bent silicon crystals; the tests have been performed at the CERN Super Proton Synchrotron H8 beam line. Channeling and volume reflection angles are measured with an extremely precise goniometer and with high resolution silicon microstrip detectors. Volume reflection has been observed and measured for the first time at this energy, with a single-pass efficiency as large as 98%, in good agreement with the simulation results. This efficiency makes volume reflection a possible candidate for collimation with bent crystals at the CERN Large Hadron Collider.

  17. Radiology and histopathology of the bent limbs in campomelic dysplasia: Implications in the aetiology of the disease and review of theories

    International Nuclear Information System (INIS)

    Pazzaglia, U.E.; Beluffi, G.

    1987-01-01

    The study of the bent bones in a case of campomelic dysplasia and a review of the literature suggest a repair process at the site of angulation. A theory that can explain most of the features of the disease is presented; it supposes a damage of the cartilage model at the midshaft, followed by a fracture of the thin bone collar in the earlier stage of ossification of the diaphysis. (orig.)

  18. Neutron diffraction studies of a double-crystal ( plus n,-m) setting containing a fully asymmetric diffraction geometry (FAD) of a bent perfect crystal (BPC)

    Czech Academy of Sciences Publication Activity Database

    Mikula, Pavol; Vrána, Miroslav; Šaroun, Jan; Em, V.

    2017-01-01

    Roč. 32, Supl-1 (2017), s. 13-18 ISSN 0885-7156 R&D Projects: GA ČR GC16-08803J; GA MŠk LM2015048 Institutional support: RVO:61389005 Keywords : neutron diffraction * monochromator * bent perfect crystal Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.674, year: 2016

  19. Transformation from a rod-like to a hockey-stick-like and bent-shaped molecule in 3,4′-disubstituted azobenzene-based mesogens

    Czech Academy of Sciences Publication Activity Database

    Horčic, M.; Kozmik, V.; Svoboda, J.; Novotná, Vladimíra; Pociecha, D.

    2013-01-01

    Roč. 1, č. 45 (2013), s. 7560-7567 ISSN 2050-7526 R&D Projects: GA ČR GA13-14133S; GA ČR(CZ) GAP204/11/0723 Grant - others:AV ČR(CZ) M100101211 Institutional support: RVO:68378271 Keywords : bent-shaped mesogen * hocky-stick-like mesogen * liquid crystals Subject RIV: JJ - Other Materials

  20. Trans-ligand-dependent arrangement (bent or linear) of Pt II-bound dialkylcyanamide ligands: Molecular structure of trans-dichloro(dimethylcyanamide)(dimethyl sulfoxide)platinum(II)

    Science.gov (United States)

    Anisimova, Tatyana B.; Bokach, Nadezhda A.; Fritsky, Igor O.; Haukka, Matti

    2011-11-01

    The title compound, trans-[PtCl 2(NCNMe 2)(Me 2SO)], is the first example of the structurally characterized Pt II species having the nitrile and the sulfoxide ligands in the trans-position to each other. The most significant feature of this structure is the non-linear arrangement of the Pt sbnd N1 sbnd C1 fragment providing the rare case of the bent form of the dialkylcyanamide ligand.

  1. An Iron Complex with a Bent, O-Coordinated CO2Ligand Discovered by Femtosecond Mid-Infrared Spectroscopy.

    Science.gov (United States)

    Straub, Steffen; Brünker, Paul; Lindner, Jörg; Vöhringer, Peter

    2018-03-06

    The activation of carbon dioxide by transition metals is widely recognized as a key step for utilizing this greenhouse gas as a renewable feedstock for the sustainable production of fine chemicals. However, the dynamics of CO 2 binding and unbinding to and from the ligand sphere of a metal have never been observed in the time domain. The ferrioxalate anion is used in aqueous solution as a unique model system for these dynamics and apply femtosecond UV-pump mid-infrared-probe spectroscopy to explore its photoinduced primary processes in a time-resolved fashion. Following optical excitation, a neutral CO 2 molecule is expelled from the complex within about 500 fs to generate a highly intriguing pentacoordinate ferrous dioxalate that carries a bent carbon dioxide radical anion ligand, that is, a reductively activated form of CO 2 , which is end-on-coordinated to the metal center by one of its two oxygen atoms. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Optimization and Annual Average Power Predictions of a Backward Bent Duct Buoy Oscillating Water Column Device Using the Wells Turbine.

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Christopher S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Willits, Steven M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fontaine, Arnold A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-08-01

    This Technical Report presents work completed by The Applied Research Laboratory at The Pennsylvania State University, in conjunction with Sandia National Labs, on the optimization of the power conversion chain (PCC) design to maximize the Average Annual Electric Power (AAEP) output of an Oscillating Water Column (OWC) device. The design consists of two independent stages. First, the design of a floating OWC, a Backward Bent Duct Buoy (BBDB), and second the design of the PCC. The pneumatic power output of the BBDB in random waves is optimized through the use of a hydrodynamically coupled, linear, frequency-domain, performance model that links the oscillating structure to internal air-pressure fluctuations. The PCC optimization is centered on the selection and sizing of a Wells Turbine and electric power generation equipment. The optimization of the PCC involves the following variables: the type of Wells Turbine (fixed or variable pitched, with and without guide vanes), the radius of the turbine, the optimal vent pressure, the sizing of the power electronics, and number of turbines. Also included in this Technical Report are further details on how rotor thrust and torque are estimated, along with further details on the type of variable frequency drive selected.

  3. Angular distributions of 7 TeV protons axially channeled through the thin bent "100" Si crystal

    CERN Document Server

    Stojanov, N; Neskovic, N; 10.1016/j.nimb.2005.10.030

    2006-01-01

    We have studied theoretically angular distributions of relativistic protons axially channeled through the thin bent left angle bracket100right angle bracket Si crystal. The proton energy is 7TeV, the thickness of the crystal is 1mm, which corresponds to the reduced crystal thickness, is varied from 0.002 to 0.020mrad. The angular distributions of axially channeled protons are generated by the computer simulation method using the numerical solution of the ion equations of motion, with the Lindhard's expression for the continuum interaction potential of the ion and the crystal. Uncertainness of the scattering angle of the proton caused by its collisions with the electrons of the crystal and proton (electronic) energy loss are taken into account. The results of the analysis show that the two additional maxima appear in the angular distributions, for the bending angles alpha less-than-or-equal 0.006mrad. They originate from four areas in the impact parameter plane located in between atomic strings defining the ch...

  4. Broadband silicon polarization beam splitter with a high extinction ratio using a triple-bent-waveguide directional coupler.

    Science.gov (United States)

    Ong, Jun Rong; Ang, Thomas Y L; Sahin, Ezgi; Pawlina, Bryan; Chen, G F R; Tan, D T H; Lim, Soon Thor; Png, Ching Eng

    2017-11-01

    We report on the design and experimental demonstration of a broadband silicon polarization beam splitter (PBS) with a high extinction ratio (ER)≥30  dB. This was achieved using triple-bent-waveguide directional coupling in a single PBS, and cascaded PBS topology. For the single PBS, the bandwidths for an ER≥30  dB are 20 nm for the quasi-TE mode, and 70 nm for the quasi-TM mode when a broadband light source (1520-1610 nm) was employed. The insertion loss (IL) varies from 0.2 to 1 dB for the quasi-TE mode and 0.2-2 dB for the quasi-TM mode. The cascaded PBS improved the bandwidth of the quasi-TE mode for an ER≥30  dB to 90 nm, with a low IL of 0.2-2 dB. To the best of our knowledge, our PBS system is one of the best broadband PBSs with an ER as high as ∼42  dB and a low IL below 1 dB around the central wavelength, and experimentally demonstrated using edge-coupling.

  5. Agromorphological characterization and dollar spot fungus susceptibility in accessions of common bent (Agrostis capillaris L.) collected in northern Spain

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, J. A.; Novo-Uzal, E.; Pomar, F.; Burghrara, S. S.; Afif, E.

    2010-07-01

    Fourteen Agrostis capillaris accessions collected in northern Spain were characterized in a trial with a low fertilization regime, carried out in two successive years (2004 and 2005). The commercial cultivar Golfin was included in the study as a control. All accessions and the commercial cultivar were evaluated for 11 agromorphological characteristics and susceptibility to dollar spot disease, caused by Sclerotinia homoeocarpa F.T. Bennet. The data obtained were reduced to five principal components that cumulatively explained 85.4% of the total variance. Cluster analysis was useful in identifying four groups of accessions that described 50% of the phenotypic variation among accessions. Cluster 1 consisted of four accessions with the highest resistance to dollar spot, dark green colour, late heading date and high autumn turf quality. Cluster 2 included the two earliest heading accessions, dark green colour, intermediate tolerance to dollar spot and low autumn turf quality. Cluster 3 comprised six accessions with the latest heading date, dark green colour and low tolerance to dollar spot. Cluster 4 consisted of two accessions and the Golfin cultivar, with lightest green colour, low autumn turf quality and the poorest tolerance to dollar spot. The results of this study suggest the potential value of some of these common bent accessions collected in northern Spain for turf and forage improvement. (Author) 40 refs.

  6. The Crystal Backlighter Imager: a spherically-bent crystal imager for radiography on the National Ignition Facility

    Science.gov (United States)

    Hall, Gareth; Krauland, Christine; Buscho, Justin; Hibbard, Robin; McCarville, Thomas; Lowe-Webb, Roger; Ayers, Shannon; Kalantar, Daniel; Kohut, Thomas; Kemp, G. Elijah; Bradley, David; Bell, Perry; Landen, Otto; Brewster, Nathaniel; Piston, Kenneth

    2017-10-01

    The Crystal Backlighter Imager (CBI) is a quasi-monochromatic, near-normal incidence, spherically-bent crystal imager being developed for the NIF, which will allow ICF capsule implosions to be radiographed close to stagnation for the first time. This has not been possible using the previous pinhole-based area-backlighter configuration, as the self-emission from the capsule hotspot overwhelms the backlighter in the final stages of the implosion. CBI mitigates the broadband self-emission from the capsule hot spot by using the extremely narrow bandwidth (a few eV) inherent to imagers based on near-normal-incidence Bragg x-ray optics. The development of a diagnostic with the capability to image the capsule during the final stages of the implosion (r less than 200um) is important, as it will allow the shape, integrity and density of the shell to be measured, and will allow the evolution of features, such as the fill tube and capsule support structure, to be imaged close to bang time. The concept and operation of the 11.6keV CBI diagnostic will be discussed, and the first results from experiments on the NIF will be presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

  7. Unusual polymorphism in new bent-shaped liquid crystals based on biphenyl as a central molecular core

    Directory of Open Access Journals (Sweden)

    Anna Kovářová

    2014-04-01

    Full Text Available Bent-shaped mesogens possessing a biphenyl as a central core have been synthesized and the role of the terminal chain and the orientation of the ester as a linkage group have been investigated. For the studied molecular core we have established that both parameters play an important role for the mesomorphic properties. The polyfluoroalkyl terminal chain supports the formation of mesophases, and the introduction of a chiral lactate terminal chain destabilizes mesophases for the first type of mutual orientation of ester groups, attached to the central core. On the contrary, for the opposite orientation of esters, the terminal chain has no effect on the mesomorphic properties, and columnar phases have been found for all compounds. A unique phase sequence has been found for the mesogen with the fluorinated chain. A generalized tilted smectics, SmCG, have been observed in a temperature interval between two different lamellar SmCP phases and characterized by X-ray and dielectric measurements. The dielectric spectroscopy data are unique and presented for the first time in the SmCG phase providing new information about the molecular dynamics.

  8. Redescription of Cyrtodactylus fumosus (Müller, 1895 (Reptilia: Squamata: Gekkonidae, with a revised identification key to the bent-toed geckos of Sulawesi

    Directory of Open Access Journals (Sweden)

    Sven Mecke

    2016-12-01

    Full Text Available The binominal Cyrtodactylus fumosus has frequently been used for populations of bent-toed geckos occurring on some Indonesian islands, including Java, Bali, Sulawesi, and Halmahera. Unfortunately, incorrect usage of this name for different geographic lineages has resulted in confusion about the true identity of C. fumosus. Examination of the type specimen and additional specimens from Rurukan and Mount Masarang, North Sulawesi Province, Indonesia, revealed that this population is distinct from other forms heretofore called ‘fumosus’ by a combination of unique morphological characters. In order to stabilize the taxonomy of C. fumosus sensu stricto, and to prevent further confusion, we provide a comprehensive redescription of this species, whose distribution we herein restrict to North Sulawesi. Cyrtodactylus fumosus is one of the most distinctive species among the six bent-toed geckos recorded from Sulawesi, and it differs from Sulawesi congeners by the presence of (1 precloacofemoral scales, including three pore-bearing scales on each thigh, separated from 10 or 11 pore-bearing scales in the precloacal region by 9-11 interscales in males, (2 a precloacal groove in adult males, (3 flat dorsal tubercles in 4-7 irregularly arranged longitudinal rows at midbody, and (4 a distinct lateral fold lacking tubercles. We also provide a revised identification key to the bent-toed gecko species of Sulawesi.

  9. Method for characterization of a spherically bent crystal for K.alpha. X-ray imaging of laser plasmas using a focusing monochromator geometry

    Science.gov (United States)

    Kugland, Nathan; Doeppner, Tilo; Glenzer, Siegfried; Constantin, Carmen; Niemann, Chris; Neumayer, Paul

    2015-04-07

    A method is provided for characterizing spectrometric properties (e.g., peak reflectivity, reflection curve width, and Bragg angle offset) of the K.alpha. emission line reflected narrowly off angle of the direct reflection of a bent crystal and in particular of a spherically bent quartz 200 crystal by analyzing the off-angle x-ray emission from a stronger emission line reflected at angles far from normal incidence. The bent quartz crystal can therefore accurately image argon K.alpha. x-rays at near-normal incidence (Bragg angle of approximately 81 degrees). The method is useful for in-situ calibration of instruments employing the crystal as a grating by first operating the crystal as a high throughput focusing monochromator on the Rowland circle at angles far from normal incidence (Bragg angle approximately 68 degrees) to make a reflection curve with the He-like x-rays such as the He-.alpha. emission line observed from a laser-excited plasma.

  10. A study on the concentration of CO by the length and the variation of the bent tube of the exhaust pipe for a household gas boiler

    International Nuclear Information System (INIS)

    Leem, Sa Hwan; Huh, Yong Jeong; Lee, Jong Rark

    2008-01-01

    Energy and environment become increasingly serious after the industrial revolution. The demand for gas as an ecofriendly energy source is also increasing. With the demand, the installation and the use of gas boilers have also increased, so the damage to human life by the waste gas (CO and CO 2 ) continues increasing every year. Hence, the aim of this study was to investigate the concentration of CO (Carbon Monoxide) by the length and the variation of the bent tube of the exhaust pipe by installing a boiler with the same method as a household boiler and to discover the harm to humans. For the effect of the length, the allowable concentration of CO is 50ppm, and the 3m of the once bent tube starts exceeding the allowable concentration of CO after 5 minutes, and the 4m and 5m starts exceeding after 3 minutes. In addition, the 1m of three times bent tube starts exceeding the allowable concentration of CO after 3 minutes

  11. Experimental study on incident wave speed and the mechanisms of deflagration-to-detonation transition in a bent geometry

    Science.gov (United States)

    Li, L.; Li, J.; Teo, C. J.; Chang, P. H.; Khoo, B. C.

    2018-03-01

    The study of deflagration-to-detonation transition (DDT) in bent tubes is important with many potential applications including fuel pipeline and mine tunnel designs for explosion prevention and detonation engines for propulsion. The aim of this study is to exploit low-speed incident shock waves for DDT using an S-shaped geometry and investigate its effectiveness as a DDT enhancement device. Experiments were conducted in a valveless detonation chamber using ethylene-air mixture at room temperature and pressure (303 K, 1 bar). High-speed Schlieren photography was employed to keep track of the wave dynamic evolution. Results showed that waves with velocity as low as 500 m/s can experience a successful DDT process through this S-shaped geometry. To better understand the mechanism, clear images of local explosion processes were captured in either the first curved section or the second curved section depending on the inlet wave velocity, thus proving that this S-shaped tube can act as a two-stage device for DDT. Owing to the curved wall structure, the passing wave was observed to undergo a continuous compression phase which could ignite the local unburnt mixture and finally lead to a local explosion and a detonation transition. Additionally, the phenomenon of shock-vortex interaction near the wave diffraction region was also found to play an important role in the whole process. It was recorded that this interaction could not only result in local head-on reflection of the reflected wave on the wall that could ignite the local mixture, and it could also contribute to the recoupling of the shock-flame complex when a detonation wave is successfully formed in the first curved section.

  12. Transitions between paraelectric and ferroelectric phases of bent-core smectic liquid crystals in the bulk and in thin freely suspended films

    Science.gov (United States)

    Eremin, Alexey; Floegel, Martin; Kornek, Ulrike; Stern, Stephan; Stannarius, Ralf; Nádasi, Hajnalka; Weissflog, Wolfgang; Zhu, Chenhui; Shen, Yongqiang; Park, Cheol Soo; Maclennan, Joseph; Clark, Noel

    2012-11-01

    We report on the contrasting phase behavior of a bent-core liquid crystal with a large opening angle between the mesogenic units in the bulk and in freely suspended films. Second-harmonic generation experiments and direct observation of director inversion walls in films in an applied electric field reveal that the nonpolar smectic C phase observed in bulk samples becomes a ferroelectric “banana” phase in films, showing that a mesogen with a small steric moment can give a phase with polar order in freely suspended films even when the corresponding bulk phase is paraelectric.

  13. Superstructural chirality of a periodic system of domains of opposite chirality and π-walls in B.sub.2./sub. phase composed of bent-shaped molecules

    Czech Academy of Sciences Publication Activity Database

    Lejček, Lubor

    2010-01-01

    Roč. 83, 10-11 (2010), s. 1001-1013 ISSN 0141-1594 R&D Projects: GA AV ČR IAA100100911; GA AV ČR(CZ) GA202/09/0047; GA MŠk(CZ) OC10006 Institutional research plan: CEZ:AV0Z10100520 Keywords : B 2 phase * bent-shaped molecules * domains of opposite chirality * π-walls * superstructural chirality Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.006, year: 2010

  14. A Comparative Study of the Crystallite Size and the Dislocation Density of Bent Steel Plates using Bragg-edge Transmission Imaging, TOF Neutron Diffraction and EBSD

    Science.gov (United States)

    Oikawa, K.; Su, Y. H.; Tomota, Y.; Kawasaki, T.; Shinohara, T.; Kai, T.; Hiroi, K.; Zhang, S. Y.; Parker, J. D.; Sato, H.; Kiyanagi, Y.

    Line broadening analysis was performed on the time-of-flight neutron diffraction data for the plastically bent plates of a ferritic steel and a duplex stainless steel. A Rietveld analysis program, Z-Rietveld ver. 1.0 was used to fit the anisotropically broadened patterns where the increase in Lorentzian full width at half maximum (FWHM) and the Gaussian FWHM involves information of the crystallite size and the dislocation density, respectively. The derived results were compared with those obtained by using Bragg-edge transmission spectrum analysis and electron backscatter diffraction (EBSD) observations.

  15. Estrutura latitudinal e temporal de assembleias de cnidários bentônicos em placas de recrutamento em dois portos da costa brasileira

    OpenAIRE

    Marina de Oliveira Fernandez

    2013-01-01

    Diferentes escalas espaciais, nas quais diferentes fatores variam, podem ser importantes em estudos da biodiversidade. Estrutura e dinâmica de comunidades marinhas epifaunais variam com a latitude, mas como essa variação muda ao longo do tempo é pouco estudada. Investigamos como a estrutura de assembleias de cnidários bentônicos em portos varia temporalmente em uma latitude tropical e uma subtropical e devido a fatores locais. No Brasil, estudamos recrutamento ao longo de quatro trimestres em...

  16. Nano to Meso-scale Structure in Liquid Crystals: the Cybotactic Nematic Phase of Bent-core Mesogens

    Science.gov (United States)

    Francescangeli, Oriano

    2012-02-01

    The extent of molecular order and the resulting broken symmetry determine the properties and mesophase type of liquid crystals (LCs). Thermotropic bent-core mesogens (BCMs) represent a new class of LCs exhibiting substantially different physical properties than traditional linear (calamitic) materials. In recent years BCMs have become the focus of intense experimental and theoretical investigation, with several exciting new developments. These include chiral mesophases composed of achiral BCMs, giant flexoelectricity, biaxial nematic (N) order, a ferroelectric response in the N phase, and a large flow birefringence. A key issue that is currently widely debated concerns the actual nature of the N phase of BCMs which gives rise to some of the above mentioned effects and is unambiguously identified by a peculiar low-angle X-ray diffraction pattern (the ``four-spot pattern''). The consensus emerging is that this N phase of BCMs constitutes a new type of mesophase, namely, a cybotactic nematic (Ncyb) phase unrelated to pretransition cybotaxis, in agreement with experimental [1-3] and theoretical findings [4]. This Ncyb phase is composed of nanometer-size clusters of BCMs exhibiting a relatively high degree of internal order---orientational as well as translational order (strata) imposed by close packing the BCM nonlinear shape. This peculiar supramolecular structure of the Ncyb mesophase of BCMs---evanescent, biaxial clusters of tilted and stratified nonlinear mesogens percolating the nematic fluid---accounts for their unusual properties, e.g., biaxial order [4], ferroelectric response [1], and extraordinary field-induced effects [5]. In this talk I will give an overview of the most recent developments and the current state of research on this subject. [4pt] [1] O. Francescangeli et al., Adv. Funct. Mater. 19,2592 (2009). [0pt] [2] O. Francescangeli and E.T. Samulski, Soft Matter 6, 2413 (2010) [0pt] [3] O. Francescangeli et al., Soft Matter 7, 895 (2011). [0pt] [4] A

  17. Downhole adjustable bent assemblies

    International Nuclear Information System (INIS)

    Askew, W.E.

    1992-01-01

    This patent describes downhole adjustable apparatus for creating a bend angle in order to affect the inclination of a drilled borehole. It comprises an upper tubular member having an upper portion and a lower portion; lower tubular member having an upper portion and a lower portion; one of the portions being received within the other for relative rotational movement about an axis that is inclined with respect to the the longitudinal axes of the members, whereby in a first rotational position the longitudinal axes have one geometrical relationship, and in a second rotational position the longitudinal axes have a second, different geometrical relationship

  18. Successful percutaneous coronary intervention for complex bifurcated lesions with combination of "Reverse wire technique" and "Reverse bent wiring with the crusade catheter" novel wire manipulation technique.

    Science.gov (United States)

    Nomura, Tetsuya; Higuchi, Yusuke; Kato, Taku

    2016-04-01

    We encountered a case of percutaneous coronary intervention for complex bifurcated lesions in the mid portion of the left anterior descending (LAD) artery. The diagonal artery branched from the LAD artery with a markedly angulated pattern and there was severe stenosis from just proximal to this diagonal artery. The "reverse wire technique facilitated with the Crusade catheter" enabled us to cross a guidewire through to the markedly angulated diagonal side branch (SB). Next, we adopted a mini-crushing stent strategy for this true bifurcated lesion. Thereafter, we adopted "reverse bent wiring with the Crusade catheter" for wire re-crossing to the incarcerated side branch, and successfully completed all procedures. This technique for successful wire re-crossing is simple but can be very effective in specific situations in practical percutaneous coronary intervention (PCI). Many PCI operators may empirically adopt this kind of wire manipulation technique. However, this case is the first report in the world describing the application of a "reverse bent wiring with the Crusade catheter" for wire re-crossing through a double-folded stent strut to a SB at the optimal point of the bifurcation. In this case, we made the most of the Crusade catheter. This catheter is a very useful device for multifactorial use in practical PCI. It can help us to perform complex PCI procedures successfully. © 2015 Wiley Periodicals, Inc.

  19. Biaxial and antiferroelectric structure of the orthogonal smectic phase of a bent-shaped molecule and helical structure in a chiral mixture system

    Science.gov (United States)

    Kang, Sungmin; Nguyen, Ha; Nakajima, Shunpei; Tokita, Masatoshi; Watanabe, Junji

    2013-05-01

    We examined the biaxial and antiferroelectric properties in the Smectic-APA (Sm-APA) phase of bent-shaped DC-S-8. The biaxiality, which results from the existence of a secondary director, was well established from birefringence observations in the homeotropically aligned Sm-APA. By entering into Sm-APA phase, the birefringence (Δn, difference between two refractive indices of short axes) continuously increased from 0 to 0.02 with decreasing temperature. The antiferroelectric switching and second harmonic generation (SHG) activity on the field-on state were also observed in the Sm-APA phase, and the evaluated spontaneous polarization (PS) value strongly depended on temperature. The temperature dependence of Δn and PS resembles each other and follows Haller's approximation, showing that the biaxiality is due to polar packing in which the molecules are preferentially packed with their bent direction arranged in the same direction, and that the phase transition of Sm-APA to Sm-A is second order. The biaxiality was further examined in chiral Sm-APA*. Doping with chiral components induced the helical twisting of the secondary director in the Sm-APA* phase, which was confirmed by observing the reflection of the circular dichroism (CD) bands in the homeotropically aligned cell. The helical pitch of Sm-APA* is tunable in the range of 300-700 nm wavelength with a variation in the chiral content of 5 to 10 weight (wt)%.

  20. Why are some ML2 molecules (M = Ca, Sr, Ba; L = H, F, Cl, Br) bent while others are linear? Implications of the pseudo Jahn-Teller effect.

    Science.gov (United States)

    Garcia-Fernandez, Pablo; Bersuker, Isaac B; Boggs, James E

    2007-10-18

    The unexpected bent geometries of some alkaline earth dihalides and dihydrides, ML(2) (M = Ca, Sr, Ba; L = H, F, Cl, Br) have been explained in the literature using various models that attribute the effect to different phenomena like covalency, metal core polarization, sd-hybridization, and electron pair repulsion. We employ (based on first principles) the pseudo Jahn-Teller effect, as the only source of instability of high-symmetry configurations in nondegenerate states, to analyze the origin of the geometry of these systems and show that this approach explains all of their main structural features, including the topology of the Laplacian of the electron density and the vibrational frequencies. The main contribution to the distortion of the linear configuration is due to the pseudo Jahn-Teller mixing by bending of the sigma(u) HOMO formed by the ligand orbitals with the unoccupied pig orbitals of the metal (with main d(xz) and d(yz) character), resulting in new covalency which stabilizes the bent configuration. We show that the model approaches to the problem, mentioned above, are either restricted particular cases of the pseudo Jahn-Teller interaction, or they yield very small contributions to the instability that do not explain the origin of the bending. All of our conclusions are supported by high-quality ab initio calculations.

  1. High-efficiency deflection of high energy protons due to channeling along the 〈110〉 axis of a bent silicon crystal

    Directory of Open Access Journals (Sweden)

    W. Scandale

    2016-09-01

    Full Text Available A deflection efficiency of about 61% was observed for 400 GeV/c protons due to channeling, most strongly along the 〈110〉 axis of a bent silicon crystal. It is comparable with the deflection efficiency in planar channeling and considerably larger than in the case of the 〈111〉 axis. The measured probability of inelastic nuclear interactions of protons in channeling along the 〈110〉 axis is only about 10% of its amorphous level whereas in channeling along the (110 planes it is about 25%. High efficiency deflection and small beam losses make this axial orientation of a silicon crystal a useful tool for the beam steering of high energy charged particles.

  2. Hiding in plain sight: a new species of bent-toed gecko (Squamata: Gekkonidae: Cyrtodactylus) from West Timor, collected by Malcolm Smith in 1924.

    Science.gov (United States)

    Kathriner, Andrew; Bauer, Aaron M; O'shea, Mark; Sanchez, Caitlin; Kaiser, Hinrich

    2014-12-24

    We describe a new species of bent-toed gecko from a single specimen initially collected in 1924 by Malcolm Smith on Timor Island in the Lesser Sunda Archipelago of Indonesia. Cyrtodactylus celatus sp. nov. is distinguished from all other congeners by the following combination of characters: small adult size; without spinose tubercles on the ventrolateral body fold and along the lateral margin of the tail; 16 longitudinal rows of tubercles at midbody; 42 ventral scales between the ventrolateral folds at midbody; no transversely enlarged, median subcaudal scales; 17 subdigital lamellae (seven basal + ten distal) under the fourth toe; no abrupt transition between postfemoral and ventral femoral scale series. The specimen is the earliest confirmed record of the genus Cyrtodactylus for Timor, and it is the first putatively endemic gecko species described from this island. 

  3. A possibility of parallel and anti-parallel diffraction measurements on neu- tron diffractometer employing bent perfect crystal monochromator at the monochromatic focusing condition

    Science.gov (United States)

    Choi, Yong Nam; Kim, Shin Ae; Kim, Sung Kyu; Kim, Sung Baek; Lee, Chang-Hee; Mikula, Pavel

    2004-07-01

    In a conventional diffractometer having single monochromator, only one position, parallel position, is used for the diffraction experiment (i.e. detection) because the resolution property of the other one, anti-parallel position, is very poor. However, a bent perfect crystal (BPC) monochromator at monochromatic focusing condition can provide a quite flat and equal resolution property at both parallel and anti-parallel positions and thus one can have a chance to use both sides for the diffraction experiment. From the data of the FWHM and the Delta d/d measured on three diffraction geometries (symmetric, asymmetric compression and asymmetric expansion), we can conclude that the simultaneous diffraction measurement in both parallel and anti-parallel positions can be achieved.

  4. A study of Channeling, Volume Reflection and Volume Capture of 3.35 - 14.0 GeV Electrons in a bent Silicon Crystal

    Energy Technology Data Exchange (ETDEWEB)

    Wistisen, T. N. [Aarhus Univ. (Denmark); Uggerhoj, U. I. [Aarhus Univ. (Denmark); Wienands, U. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Markiewicz, T. W. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Noble, R. J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Benson, B. L. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Smith, T. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Bagli, E. [Univ. of Ferrara (Italy); Bandiera, L. [Univ. of Ferrara (Italy); Germogli, G. [Univ. of Ferrara (Italy); Guidi, V. [Univ. of Ferrara (Italy); Mazzolari, A. [Univ. of Ferrara (Italy); Holtzapple, R. [California Polytechnic State Univ. (CalPoly), San Luis Obispo, CA (United States); Tucker, S. [California Polytechnic State Univ. (CalPoly), San Luis Obispo, CA (United States)

    2015-12-03

    We present the experimental data and analysis of experiments conducted at SLAC National Accelerator Laboratory investigating the processes of channeling, volume-reflection and volume-capture along the (111) plane in a strongly bent quasi-mosaic silicon crystal. Additionally, these phenomena were investigated at 5 energies: 3.35, 4.2, 6.3, 10.5 and 14.0 GeV with a crystal with bending radius of 0.15m, corresponding to curvatures of 0.070, 0.088, 0.13, 0.22 and 0.29 times the critical curvature respectively. We have extracted important parameters describing the channeling process such as the dechanneling length, the angle of volume reflection, the surface transmission and the widths of the distribution of channeled particles parallel and orthogonal to the plane.

  5. An Optically Isotropic Antiferroelectric Liquid Crystal (OI-AFLC) Display Mode Operating over a Wide Temperature Range using Ternary Bent-Core Liquid Crystal Mixtures.

    Science.gov (United States)

    Bergquist, Leah; Zhang, Cuiyu; Ribeiro de Almeida, Roberta R; Pellegrene, Brittany; Salamonczyk, Miroslaw; Kim, Matthew; Hwang, Jung-Im; Kim, Kyeong-Jin; Lee, Joun-Ho; Jákli, Antal; Hegmann, Torsten

    2017-04-01

    We report on the synthesis and characterization of bent-core liquid crystal (LC) compounds and the preparation of mixtures that provide an optically isotropic antiferroelectric (OI-AFLC) liquid crystal display mode over a very wide temperature interval and well below room temperature. From the collection of compounds synthesized during this study, we recognized that several ternary mixtures displayed a modulated SmC a P A phase down to below -40 °C and up to about 100 °C on both heating and cooling, as well as optical tilt angles in the transformed state of approximately 45° (optically isotropic state). The materials were fully characterized and their liquid crystal as well as electro-optical properties analyzed by polarized optical microscopy, differential scanning calorimetry, synchrotron X-ray diffraction, dielectric spectroscopy, and electro-optical tests.

  6. The Nature of the Idealized Triple Bonds Between Principal Elements and the σ Origins of Trans-Bent Geometries-A Valence Bond Study.

    Science.gov (United States)

    Ploshnik, Elina; Danovich, David; Hiberty, Philippe C; Shaik, Sason

    2011-04-12

    We describe herein a valence bond (VB) study of 27 triply bonded molecules of the general type X≡Y, where X and Y are main element atoms/fragments from groups 13-15 in the periodic table. The following conclusions were derived from the computational data: (a) Single π-bond and double π-bond energies for the entire set correlate with the "molecular electronegativity", which is the sum of the X and Y electronegativites for X≡Y. The correlation with the molecular electronegativity establishes a simple rule of periodicity: π-bonding strength generally increases from left to right in a period and decreases down a column in the periodic table. (b) The σ frame invariably prefers trans bending, while π-bonding gets destabilized and opposes the trans distortion. In HC≡CH, the π-bonding destabilization overrides the propensity of the σ frame to distort, while in the higher row molecules, the σ frame wins out and establishes trans-bent molecules with 2(1)/2 bonds, in accord with recent experimental evidence based on solid state (29)Si NMR of the Sekiguchi compound. Thus, in the trans-bent molecules "less bonds pay more". (c) All of the π bonds show significant bonding contributions from the resonance energy due to covalent-ionic mixing. This quantity is shown to correlate linearly with the corresponding "molecular electronegativity" and to reflect the mechanism required to satisfy the equilibrium condition for the bond. The π bonds for molecules possessing high molecular electronegativity are charge-shift bonds, wherein bonding is dominated by the resonance energy of the covalent and ionic forms, rather than by either form by itself.

  7. Benthic macroinvertebrates in the Paranapanema reservoir cascade (southeast Brazil Macroinvertebrados bentônicos dos reservatórios em cascata do rio Paranapanema (sudeste, Brasil

    Directory of Open Access Journals (Sweden)

    A. Jorcin

    2008-11-01

    Full Text Available In this study, the composition, specific richness and abundance of benthic macroinvertebrates (Neste estudo, foi analisada a composição, riqueza específica e abundância de macroinvertebrados bentônicos de oito reservatórios do rio Paranapanema, assim como nos principais tributários (Taquari, Pardo e Tibagi e zona de desembocadura no rio Paraná. Dezenove pontos distribuídos ao longo de 700 km foram amostrados trimestralmente (oito campanhas durante dois anos consecutivos (2000 e 2001. O zoobentos foi caracterizado por uma alta riqueza de espécies (c.a. 100 taxa, com a predominância de Diptera Chironomidae (c.a. 50 taxa. Foi observada uma grande variação espacial na estrutura das assembléias, principalmente quando comparadas às zonas lacustres dos reservatórios e aos trechos fluviais. O Oligochaeta Narapa bonettoi foi dominante em estações de amostragem com sedimento arenoso e elevada velocidade de correnteza, principalmente no rio Pardo e na montante e jusante da zona de desembocadura do rio Paranapanema no rio Paraná. Branchiura sowerbyi, outro Oligochaeta numericamente importante, foi abundante no trecho superior da bacia. O molusco bivalve Corbicula fluminea mostrou-se amplamente distribuído, ocorrendo na maioria dos locais e períodos amostrados. Uma elevação da riqueza e abundância ocorreu no médio Paranapanema. Menor profundidade, maior fluxo e aumento da trofia parecem favorecer o desenvolvimento da fauna bentônica nesta região. Um padrão de variação sazonal durante os dois anos de estudo não pôde ser detectado, principalmente relacionado à abundância de organismos.

  8. Impacto de la captura ilegal en la pesquería del recurso ‘loco’ (Concholepas concholepas) en Áreas de Manejo y Explotación de Recursos Bentónicos: el caso de la Isla Mocha

    OpenAIRE

    Bandin Llanos, Ricardo Máximo

    2013-01-01

    En Chile, el gastrópodo Concholepas concholepas conocido popularmente como ‘loco’, es un importante recurso bentónico de las pesquerías artesanales, con el que el Estado introdujo en la segunda mitad de los 90s un régimen de co-manejo denominado Áreas de Manejo y Explotación de Recursos Bentónicos (AMERB). En él se asignan a pescadores artesanales formalmente organizados, derechos exclusivos de acceso a stocks de recursos bentónicos en áreas marino costeras geográficamente delimitadas, para s...

  9. Ensamble de crustáceos bentónicos en un lago salino tropical Benthic crustaceans assemblage in a tropical, saline lake

    Directory of Open Access Journals (Sweden)

    Ma. del Carmen Hernández

    2010-10-01

    Full Text Available El presente trabajo reconoce la composición, estructura y distribución espacial del ensamble de crustáceos bentónicos de Alchichica, un lago salino tropical ubicado en el extremo oriental del altiplano mexicano. El lago presenta una riqueza taxonómica de crustáceos bentónicos compuesta por 1 anfípodo (Hyalella azteca, 1 isópodo (Caecidotea williamsi y 2 ostrácodos (Limnocythere inopinata y Candona sp.. Comparada con otros lagos tropicales, la riqueza de especies es reducida. A pesar de lo anterior, es importante mencionar el grado elevado de endemismo representado por C. williamsi, recientemente descrita para el lago Alchichica; adicionalmente, es factible que tanto Candona como H. azteca sean especies nuevas y endémicas del lago. Los crustáceos bentónicos se distribuyen desde la zona litoral hasta la zona más profunda del lago (62 m con abundancias y riqueza taxonómica variables. Los ostrácodos fueron los crustáceos que con mayor frecuencia se recolectaron en el lago, en la zona litoral, en el talud, y en la zona profunda de la que son habitantes exclusivos. Los anfípodos constituyeron el segundo grupo en abundancia de la zona litoral y talud y estuvieron ausentes en la zona profunda. Los isópodos sólo se encuentran asociados a los depósitos de tufa, hábitat característico del lago que se extiende a lo largo del talud, por lo que con las técnicas de muestreo tradicional empleadas en el presente estudio no fueron capturados. En este ensamble de crustáceos predominan las especies de desarrollo directo y con posiciones tróficas que incluyen componentes herbívoros (H. azteca, omnívoros (C. williamsi y bacterívoros (L. inopinata y Candona sp..This work acknowledges the composition, structure and spatial distribution of the benthic crustaceans assemblage of Alchichica, a tropical saline lake located in the easternmost portion of the Mexican highlands. The benthic crustaceans' assemblage was comprised by 1 amphipod

  10. Temperature profiles from expendable bathythermograph (XBT) casts from the USNS SILAS BENT in the North Pacific Ocean, East China Sea, and Sea of Japan in support of the Integrated Global Ocean Services System (IGOSS) project from 1975-11-13 to 1975-12-11 (NODC Accession 7601776)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — XBT data were collected from the USNS SILAS BENT in support of the Integrated Global Ocean Services System (IGOSS) project. Data were collected by the US Navy; Naval...

  11. Temperature profiles from expendable bathythermograph (XBT) casts from the USNS SILAS BENT in the North Pacific Ocean in support of the Integrated Global Ocean Services System (IGOSS) project from 1976-02-06 to 1976-02-25 (NODC Accession 7600712)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — XBT data were collected from the USNS SILAS BENT in support of the Integrated Global Ocean Services System (IGOSS) project. Data were collected by the US Navy; Naval...

  12. Direct probe of the bent and linear geometries of the core-excited Renner-Teller pair states by means of the triple-ion-coincidence momentum imaging technique

    International Nuclear Information System (INIS)

    Muramatsu, Y.; Ueda, K.; Chiba, H.; Saito, N.; Lavollee, M.; Czasch, A.; Weber, T.; Jagutzki, O.; Schmidt-Boecking, H.; Moshammer, R.; Becker, U.; Kubozuka, K.; Koyano, I.

    2002-01-01

    The doubly degenerate core-excited Π state of CO 2 splits into two due to static Renner-Teller effect. Using the triple-ion-coincidence momentum imaging technique and focusing on the dependence of the measured quantities on the polarization of the incident light, we have probed, directly and separately, the linear and bent geometries for the B 1 and A 1 Renner-Teller pair states, as a direct proof of the static Renner-Teller effect

  13. Fully nonlinear time-domain simulation of a backward bent duct buoy floating wave energy converter using an acceleration potential method

    Directory of Open Access Journals (Sweden)

    Kyoung-Rok Lee

    2013-12-01

    Full Text Available A floating Oscillating Water Column (OWC wave energy converter, a Backward Bent Duct Buoy (BBDB, was simulated using a state-of-the-art, two-dimensional, fully-nonlinear Numerical Wave Tank (NWT technique. The hydrodynamic performance of the floating OWC device was evaluated in the time domain. The acceleration potential method, with a full-updated kernel matrix calculation associated with a mode decomposition scheme, was implemented to obtain accurate estimates of the hydrodynamic force and displacement of a freely floating BBDB. The developed NWT was based on the potential theory and the boundary element method with constant panels on the boundaries. The mixed Eulerian-Lagrangian (MEL approach was employed to capture the nonlinear free surfaces inside the chamber that interacted with a pneumatic pressure, induced by the time-varying airflow velocity at the air duct. A special viscous damping was applied to the chamber free surface to represent the viscous energy loss due to the BBDB's shape and motions. The viscous damping coefficient was properly selected using a comparison of the experimental data. The calculated surface elevation, inside and outside the chamber, with a tuned viscous damping correlated reasonably well with the experimental data for various incident wave conditions. The conservation of the total wave energy in the computational domain was confirmed over the entire range of wave frequencies.

  14. Detection of multi-scale secondary flow structures using anisotropic 2D Ricker wavelets in a bent tube model for curved arteries

    Science.gov (United States)

    Plesniak, Daniel H.; Bulusu, Kartik V.; Plesniak, Michael W.

    2012-11-01

    Interpretation of complex flow patterns observed in this study of a model curved artery required characterization of multiple, low-circulation secondary flow structures that were observed during the late systolic deceleration and diastolic phases under physiological inflow conditions. Phase-locked, planar vorticity PIV data were acquired at various cross-sectional locations of the 180-degree bent tube model. High circulation, deformed Dean- and Lyne-type vortices were observed during early stages of deceleration, while several smaller scale, highly deformed, low-circulation vortical patterns appeared in the core and near-wall regions during late systolic deceleration and diastolic phases. Due to the multiplicity of vortical scales and shapes, anisotropic 2D Ricker wavelets were used for coherent structure detection in a continuous wavelet transform algorithm (PIVlet 1.2). Our bio-inspired study is geared towards understanding whether optimizing the shape of the wavelet kernel will enable better resolution of several low-circulation, multi-scale secondary flow morphologies and whether new insights into the dynamics of arterial secondary flow structures can accordingly be gained. Supported by the National Science Foundation, Grant No. CBET-0828903 and GW Center for Biomimetics and Bioinspired Engineering (COBRE).

  15. A regime map for secondary flow structures under physiological and multi-harmonic inflow through a bent tube model for curved arteries

    Science.gov (United States)

    Callahan, Shannon M.; Caldwell, Kirin; Bulusu, Kartik V.; Plesniak, Michael W.

    2012-11-01

    Secondary flow structures are known to affect wall shear stress, which is closely related to atherogenesis and drug particle deposition. A regime map provides a framework to examine phase-wise variations in secondary flow structures under physiological and multi-harmonic inflow waveforms under conditions of a fixed Womersley number (4.2) and curvature ratio (1/7). Experimental PIV data were acquired at the 90-degree location in a 180-degree curved test section of a bent tube model for curved arteries using a blood analog working fluid. Coherent structure detection was performed using a continuous wavelet transform algorithm (PIVlet 1.2) and further analysis was carried out by grouping similar secondary flow structures at a fixed secondary Reynolds numbers. Phase-locked, planar vorticity fields over one period of inflow waveform revealed size, structure and strength similarities in secondary flow morphologies during the acceleration and deceleration phases. The utility of the new regime map lies in the a priori identification of pulsatile secondary flow structures, eliminating the need for exhaustive experimentation or computing, requiring only flow rate measurements that are easily acquired under clinical conditions. Supported by the National Science Foundation, Grant No. CBET-0828903 and GW Center for Biomimetics and Bioinspired Engineering (COBRE).

  16. Focusing bent perfect-crystal neutron monochromator a key to high-resolution stress/strain measurement studies of polycrystalline materials

    CERN Document Server

    Ono, M; Harjo, S; Saroun, J; Yoneda, K; Sawano, J; Sakurai, Y; Kobayashi, T

    2000-01-01

    A new neutron focusing device with bent Si-single crystal has been installed at high-resolution neutron diffractometer dedicated to strain/stress investigations in polycrystalline materials and introduced into routine operation as a neutron strain scanner using reactor neutrons from supermirror guider at Kyoto University Research Reactor (KUR). Properties of the diffractometer are described on the basis of experimental results when one slab or two slabs of curved Si single crystals are employed as monochromator:i.e. 1) the luminosity 2) the absolute value of monochromatic neutrons with the Au-foil activation method, 3) beam profiles with the imaging plate method, 4) characterization of the diffractometer with alpha Fe (211) peak and its comparison with the Bragg optical prediction. It is confirmed that the FWHM of the instrumental delta d/d-profile of the peak can be less than 3*10/sup -3/ at d=1.17 A and the resolution permits us to investigate both the macro- and microstrains with good luminosity. The lumin...

  17. A Dual Modulated Homochiral Helical Nanofilament Phase with Local Columnar Ordering Formed by Bent Core Liquid Crystals: Effects of Molecular Chirality.

    Science.gov (United States)

    Li, Lin; Salamonczyk, Miroslaw; Jákli, Antal; Hegmann, Torsten

    2016-08-01

    Helical nanofilament (HNF) phases form as a result of an intralayer mismatch between top and bottom molecular halves in bent-core liquid crystals (BC-LCs) that is relieved by local saddle-splay geometry. HNFs are immensely attractive for photovoltaic and chiral separation applications and as templates for the chiral spatial assembly of guest molecules. Here, the synthesis and characterization of two unichiral BC-LCs and one racemic mixture with tris-biphenyl-diester cores featuring chiral (R,R) and (S,S) or racemic 2-octyloxy aliphatic side chains are presented. In comparison to the achiral compound with linear side chains forming an intralayer modulated HNF phase (HNFmod ), synchrotron small angle X-ray diffraction indicates that the unichiral derivatives form a dual modulated HNF phase with intra- as well as interlayer modulations (HNFmod2 ) suggesting a columnar local structure of the nanofilaments. Transmission electron microscopy and circular dichroism spectropolarimetry confirm that the unichiral materials exclusively form homochiral HNFs with a twist sense-matching secondary twist. A contact preparation provides the first example of two identical chiral liquid crystal phases only differing in their handedness that do not mix and form an achiral liquid crystal phase with an entirely different structure in the contact zone. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Influência dos fatores ambientais sobre a distribuição da comunidade de invertebrados bentônicos em canais de uma planície de inundação neotropomunidade de invertebrados bentônicos em canais secundários e principal de uma planície de inundação neotropical

    Directory of Open Access Journals (Sweden)

    Danielle Katharine Petsch

    2013-05-01

    Full Text Available http://dx.doi.org/10.5007/2175-7925.2013v26n3p127 Um dos temas centrais em ecologia é a importância relativa dos processos locais e regionais na determinação da estrutura de comunidades, pois ambos os processos podem agir como filtros na composição das comunidades locais. Nesse sentido, este estudo analisou a influência dos fatores ambientais sobre a distribuição da comunidade de invertebrados bentônicos em diferentes canais da planície de inundação do alto rio Paraná, por meio de coletas trimestrais realizadas de março a dezembro de 2010. A partir de dados bióticos e abióticos foi realizada Análise de Correspondência Canônica, onde foi possível agrupar os centros dos rios Ivinhema e Paraná e o canal Ipoitã em relação aos demais pontos, principalmente pelos maiores valores de profundidade e velocidade e pelos táxons típicos de ambientes lóticos, como Harpacticoida, Haplotaxidae e Narapidae, e o centro do canal Curutuba, com L. fortunei. Pode-se concluir que a velocidade de fluxo, a textura granulométrica e matéria orgânica do sedimento foram fatores estruturadores da comunidade bentônica, determinando a distribuição dos invertebrados tanto entre os diferentes canais como entre as regiões marginais e centrais desses ambientes, proporcionando maior ou menor disponibilidade de recursos e heterogeneidade ambiental.

  19. Diversidade de habitats físicos e sua relação com macroinvertebrados bentônicos em reservatórios urbanos em Minas Gerais

    Directory of Open Access Journals (Sweden)

    Joseline Molozzi

    2011-09-01

    Full Text Available Foram avaliados os efeitos da estrutura física de habitats em comunidades de macroinvertebrados bentônicos em três reservatórios: Serra Azul (SA, Vargem das Flores (FV e Ibirité (IB. Mensurações de variáveis físicas e químicas e comunidade bentônica foram realizadas em 30 estações de amostragem em cada reservatório. Em SA, foram coletados 12 táxons com predomínio de Melanoides tuberculatus Müller, 1774 (15,2% e Chaoboridae (63,8%. Em VF foram coletados 11 táxons sendo M. tuberculatus (34,2% e Oligochaeta (33,6% os dominantes. Em IB foram coletados 7 táxons com domínio de M. tuberculatus (91,2% e Chaoboridae (6,27%. Em Serra Azul foi observada influência significativa do sub-bosque arbustivo e do ângulo de inclinação do barranco. Nos reservatórios de Ibirité e Vargem das Flores as variáveis significativas foram cobertura do solo, influência humana e macrófitas aquáticas. Concluímos que as ações humanas reduzem a cobertura da vegetação terrestre e a complexidade de habitats físicos na região litorâneos dos reservatórios, levando a uma redução na qualidade de água. Essas mudanças, por sua vez, reduzem a riqueza taxonômica dos macroinvertebrados bentônicos.

  20. Efeito de metais Cobre (Cu e Zinco (Zn sobre a comunidade de macroinvertebrados bentônicos em riachos do sul do Brasil = The effect of metals (Cu and Zn on the benthic macroinvertebrate community in streams in southern Brazil

    Directory of Open Access Journals (Sweden)

    Silvia Vendruscolo Milesi

    2008-07-01

    Full Text Available O objetivo deste estudo foi avaliar os efeitos de metais (Cu e Zn sobre a comunidade de macroinverterados bentônicos. Foram amostrados, trimestralmente, entre setembro de 2006 e junho de 2007, organismos e água em oito trechos de riachos de duas bacias hidrográficas influenciadas por urbanização e agricultura. Foram estimados os valores de densidade de organismos, riqueza taxonômica e diversidade de Shannon. Para avaliação dos dados, foram utilizados testes de variância e regressão linear simples. Os resultados demonstraram variabilidade das concentrações dos metais e da macrofauna entre as estações do ano e riachos estudados. O metal Cobre (Cu apresentou influência apenas sobre a densidade Chironomidae e o metal Zinco (Zn apresentou efeito sobre a densidade total da macrofauna bentônica e de Chironomidae. Nenhum dos metais apresentou efeitos sobre ariqueza e diversidade de macroinvertebrados. Os resultados indicam potencial bioindicador da comunidade bentônica na avaliação da qualidade integrada do ambiente.The aim of this study was to evaluate the effect of metals (Cu and Zn on the benthic macroinvertebrate community. The organismsand water were collected quarterly between September 2006 and June 2007, in eight sites in streams of two hydrographic basins, influenced by urbanization and agriculture. The values of organism density, taxonomic richness and the Shannon diversity index were calculated. For data evaluation, tests of variance and simple linear regression were used. The results showed variability in the metal concentration and benthic community among seasons and studied streams. Cu showed influence only on Chironomidae density. Zn demonstrated effect on the benthic community and Chironomidae density. None of the metals presented effect on the macroinvertebrate richness and diversity. The results indicate a bioindicatorpotential of the benthic community in the evaluation of integral quality of the environment.

  1. Interação de indicadores geoquímicos e foraminíferos bentônicos na avaliação ambiental do Recife de Fora, Porto Seguro, Bahia

    OpenAIRE

    Araújo, Silvia Lisboa de

    2017-01-01

    Com os danos que vêm sendo causados nos ecossistemas recifais brasileiros e considerando suas altas taxas de endemismo, a conservação da biodiversidade dos mesmos é indispensável e a utilização de indicadores ambientais é importante para o estudo dos fenômenos que afetam os ecossistemas marinhos. É nesse contexto que a assembleia de foraminíferos bentônicos tem sido amplamente utilizada como indicadores da qualidade ambiental de ecossistemas de recifes de coral, uma vez que ...

  2. Parasitic Extraction of 900-GeV/c Protons from the Tevatron using a Bent Silicon Crystal and Measurement of the $b \\bar{b}$ Production Cross-Section at $\\sqrt{s}$ = 38.8-GeV

    Energy Technology Data Exchange (ETDEWEB)

    Ramachandran, Sathyadev [UCLA

    1997-01-01

    This dissertation discusses results from an experiment demonstrating the feasibility of a novel extraction scheme using channeling in a bent crystal at future high-energy colliders for doing heavy flavor physics in a fixed target environment concurrently with collider experiments. In the second half of this dissertation we present the results from a measurement of the inclusive cross-section for $b\\bar{b}$ production at the center-of-mass energy of 38.8 GeV using the semileptonic decays of the beauty mesons.

  3. Parasitic extraction of 900-GeV/c protons from the Tevatron using a bent silicon crystal and measurement of the $b \\bar{b}$ production cross-section at $\\sqrt{s}$ = 38.8-GeV

    Energy Technology Data Exchange (ETDEWEB)

    Ramachandran, Sathyadev [Univ. of California, Los Angeles, CA (United States)

    1997-01-01

    This dissertation discusses results from an experiment demonstrating the feasibility of a novel extraction scheme using channeling in a bent crystal at future high-energy colliders for doing heavy avor physics in a xed target environment concurrently with collider experiments. In the second half of this dissertation we present the results from a measurement of the inclusive cross-section for b$\\bar{b}$ production at the center-of-mass energy of 38.8 GeV using the semileptonic decays of the beauty mesons.

  4. Foraminíferos bentônico recentes aplicados a caracterização ambiental da plataforma continental adjacente a foz do rio Paraíba do Sul (RJ)

    OpenAIRE

    Polla, Daniela Lemos

    2016-01-01

    Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas, Programa de Pós-Graduação em Geografia, Florianópolis, 2016. A distribuição de foraminíferos bentônicos foi estudada visando à caracterização dos processos oceanográficos dominantes na Plataforma Continental adjacente à Foz do Rio Paraíba do Sul (RPS) - RJ, entre as isóbatas de 10 e 100 metros. No presente estudo, inserido no contexto do Projeto Habitats ? Heterogeneidade Ambiental da B...

  5. Nuevas citas y aportaciones corológicas para la flora bentónica marina del Atlántico de la Península Ibérica

    OpenAIRE

    Bárbara, Ignacio; Díaz Tapia, Pilar; Peteiro, César; Berecibar, Estibaliz; Peña, Viviana; Sánchez, Noemí; Tavares, Ana Mafalda; Santos, Rui; Secilla, Antonio; Riera Fernández, Pablo; Bermejo, Ricardo; García, Verónica

    2012-01-01

    Se dan a conocer nuevas localizaciones y datos corológicos para 98 especies (61 Rhodophyta, 22 Ochrophyta, 15 Chlorophyta) de algas bentónicas marinas recolectadas en el intermareal y submareal de más de 80 localidades de las costas atlánticas y cantábricas de la Península Ibérica. Polysiphonia devoniensis, P. fibrata y Zonaria tournefortii son novedad para Portugal y 5 especies (Bonnemaisonia hamifera, Calosiphonia vermicularis, P. devoniensis, Hincksia intermedia y Derbesia marina stadium H...

  6. Clorofíceas marinhas bentônicas da Praia de Serrambi, Pernambuco, Brasil Benthic marine Chlorophyceae from Serrambi Beach, Pernambuco, Brazil

    Directory of Open Access Journals (Sweden)

    Sônia Maria Barreto Pereira

    1998-04-01

    Full Text Available É apresentado o levantamento florístico sobre as clorofíceas marinhas bentônicas encontradas na Praia de Serrambi, litoral Sul do Estado de Pernambuco. O material estudado foi coletado em três estações, as quais foram visitadas mensalmente durante o período de abril de 1986 a setembro de 1987. As clorofíceas foram representadas na flora local por 39 espécies, três variedades e uma forma, pertencentes às ordens Ulotrichales, Ulvales, Siphonocladales, Cladophorales, Caulerpales e Dasycladales. Acetabularia calyculus Quoy & Gaimard. In Freycinet, Bryopsis pennata Lamouroux, Bryopsis plumosa (Hudson C. Agardh, Caulerpa ambigua Okamura, Caulerpa serrulata (Forsskål J. Agardh emend Børgesen, Chaetomorpha brachygona Harvey, Cladophora coelothrix Kützing, Cladophoropsis membranacea (C. Agardh Børgesen, Codium intertextum Collins & Hervey, Ernodesmis verticillata (Kützing Børgesen são novas referências para a flora do litoral de Pernambuco. Pringsheimiella scutata (Reinke von Höhnel ex Marchewianka o é também para o litoral continental do Brasil. Halimeda opuntia (L. Lamouroux foi hospedeira de maior número de epífitas, enquanto Bryopsis plumosa, quando epífita, foi a que cresceu sobre maior número de hospedeiros.This survey presents studies about benthics marine chlorophyceae found in the Serrambi Beach, South coast of Pernambuco. The material studied was collected in three stations, which were visited monthly during the period from April, 1986 to September, 1987. The chlorophyceae were represented in this flora by 39 species, three varieties and one form, from orders Ulotrichales, Ulvales, Siphonocladales, Cladophorales, Caulerpales and Dasycladales. Acetabularia calyculus Quoy & Gaimard. In Freycinet, Bryopsis pennata Lamouroux, Bryopsis plumosa (Hudson C. Agardh, Caulerpa ambigua Okamura, Caulerpa serrulata (Forsskål J. Agardh emend Børgesen, Chaetomorpha brachygona Harvey, Cladophora coelothrix Kützing, Cladophoropsis

  7. Algas marinas bentónicas de la costa noroccidental de Guerrero, México Benthic marine algae of the west coast of Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    Luz Elena Mateo-Cid

    2012-12-01

    Full Text Available Se presentan los resultados de un estudio sobre algas marinas bentónicas en 7 localidades de la costa noroccidental de Guerrero, México. Se determinó la presencia de 163 especies de algas marinas. Se identificaron 17 especies de Cyanobacteria, 93 Rhodophyta, 28 Chlorophyta y 25 de Heterokontophyta. Se citan 54 registros nuevos para el litoral de Guerrero, 2 también nuevos, Myrionema strangulans Greville y Acrochaete ramosa (N.L.Gardner O'Kelly para la costa del Pacífico. Cada especie se acompaña de datos sobre su distribución en el área de estudio, su estado reproductivo, nivel de marea, hábitat, observaciones, epifitismo y número de herbario o de recolección. Se comparó la riqueza específica entre la estación climática de lluvias y la de secas. La división Rhodophyta dominó en términos de diversidad en relación con las 3 divisiones restantes. La ficoflora de la costa noroccidental de Guerrero es de afinidad tropical y más diversa en la época de secas.We present results on the study on benthic marine algae in 7 localities from the west coast of Guerrero, Mexico. We report 163 species: 17 Cyanobacteria, 93 Rhodophyta, 28 Chlorophyta and 25 Heterokontophyta. Fifty four are new records for Guerrero; while Myrionema strangulans Greville and Acrochaete ramosa (N.L.Gardner O'Kelly are new to the Pacific coast of Mexico. Each species includes data on its distribution, reproductive stages, tidal level, facies, epiphytism and herbarium's number. Species diversity was compared for 2 different climatic seasons. The Rhodophyta are dominant in terms of diversity in relation to the other groups. The algal flora of the northwest coast of Guerrero is tropical and the greatest diversity was found during dry seasons.

  8. Diversidad, abundancia y distribución de la macrofauna bentónica de las costas rocosas al norte del Estado Sucre, Venezuela

    Directory of Open Access Journals (Sweden)

    Johanna Fernández

    2014-09-01

    Full Text Available La zona litoral rocosa esta entre los ambientes físicamente más extremos de la tierra. Los organismos que allí habitan son azotados alternadamente por factores físico-químicos y biológicos. Debido a la gran importan- cia ecológica que poseen estos ambientes, se estudió la diversidad, abundancia y distribución de la macrofauna bentónica del litoral rocoso, en la costa norte del estado Sucre, Venezuela. Se realizaron muestreos bimensuales, durante un año. La recolecta del material biológico se realizó de forma manual, dentro de una cuadrícula de 0.25m², en la zona litoral (supra, medio e infralitoral. Los organismos fueron preservados en formalina al 10% para su posterior identificación y análisis (parámetros ecológi- cos y prueba Kruskal-Wallis a la abundancia y diversidad. Se obtuvieron un total 19 020 organismos (86spp., en 8 filos, 45 familias y 47 géneros. Los moluscos fueron los más abundantes y diversos (58 spp., seguido de los artró- podos (12spp., anélidos (7spp., equinodermos (5spp., y cnidarios, sipuncúlidos, nemertínidos y urocordados (1sp.. Los resultados encontrados, coincidieron con el esquema universal de zonación de Stephenson & Stephenson (1949. Las localidades de Río Caribe y Boca de Río presentaron los valores más altos de los parámetros ecológicos y Playa Grande los más bajos. Estadísticamente se observaron diferencias en la abundancia y diversidad de la macrofauna, entre las tres zonas. La poca información de la composición y distribución macrobentónica del litoral rocoso, impide una mejor comparación, no obstante los resultados contri- buyen al conocimiento de la biodiversidad marina en esta región venezolana.

  9. Macroinvertebrados bentónicos como indicadores de la calidad de agua en la microcuenca San Alberto, Oxapampa, Perú

    Directory of Open Access Journals (Sweden)

    Stefany Salcedo Gustavson

    2013-12-01

    Full Text Available Objetivos: Evaluar la biodiversidad de macroinvertebrados y la calidad ecológica de la microcuenca San Alberto (provincia de Oxapampa, Pasco de abril a julio de 2013. Métodos: El muestreo fue realizado en tres zonas de la microcuenca San Alberto (cuenca alta, media y baja. En los tres sitios fueron colectados macroinvertebrados bentónicos en piedra y arena. Luego se estimaron: el índice biótico andino (IBA, de hábitat fluvial (IHF, de calidad de vegetación de ribera andina (QBRAnd y de estado ecológico (ECOSTRIAND. Se evaluaron parámetros fisicoquímicos, nutrientes y metales en el agua. Resultados: Se registraron un total de 123 taxones de 47 familias (101 taxones en la cuenca alta, 77 en la cuenca media y 55 en la cuenca baja. La mayor abundancia de macroinvertebrados se presentó en la cuenca media. El IBA resultó ser de “muy buena” calidad para la cuenca alta, media y baja, pero al combinarse este índice con el QBR-And, para elaborar el Índice ECOSTRIAND, se observó el estado ecológico de las cuencas alta y media fueron de “muy buena” calidad y de la cuenca baja fue “regular”. El método de muestreo de limpieza de piedras fue el que permitió colectar la mayor cantidad de taxones. Las mejores condiciones de hábitat fluvial, de vegetación ribereña y de estado ecológico, tras la aplicación de los índices IHF, QBR-And y ECOSTRIAND, se encuentran en la cuenca alta. Conclusiones: Los resultados indican que la diferencia de calidad de hábitat ribereño y fluvial así como de conductividad, sólidos disueltos y nitratos influyen negativamente sobre la calidad del agua, y ésta, sobre la comunidad de macroinvertebrados. Las familias reportadas como sensibles a la contaminación (Leptophlebiidae, Oligoneuriidae, Perlidae, Anomalopsychidae, Calamoceratidae, Helicopsychidae, Odontoceridae, Blephariceridae mostraron ser bioindicadores de calidad de agua para la microcuenca.

  10. Self-assembly of metal-organic coordination polymers constructed from a bent dicarboxylate ligand: diversity of coordination modes, structures, and gas adsorption.

    Science.gov (United States)

    Yang, Wenbin; Lin, Xiang; Blake, Alexander J; Wilson, Claire; Hubberstey, Peter; Champness, Neil R; Schröder, Martin

    2009-12-07

    We have synthesized five new metal-organic coordination polymers incorporating the bent ligand H(2)hfipbb [4,4'-(hexafluoroisopropylidene)bis(benzoic acid)] with different transition metal ions and co-ligands via solvothermal reactions to give [Zn(2)(hfipbb)(2)(py)(2)] x DMF (1), [Zn(2)(hfipbb)(2)(4,4'-bipy)(H(2)O)] (2), [Zn(2)(hfipbb)(2)(bpdab)].2DMF (3), [Cd(2)(hfipbb)(2)(DMF)(2)] x 2 DMF (4), and [Co(hfipbb)(dpp)] x MeOH (5) (py = pyridine, 4,4'-bipy = 4,4'-bipyridine, bpdab = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, dpp = 1,3-di(4-pyridyl)propane). Compound 1 displays a 2-fold 2D-->2D parallel interpenetrated layer network with one-dimensional (1D) helical channels, while 3 exhibits a three-dimensional pillared helical-layer open framework of alpha-Po topology based upon binuclear paddlewheel units. In compounds 2 and 5, binuclear motifs with double carboxylate bridges are linked by hfipbb(2-) ligands into a 1D ribbon, which are further assembled into two-dimensional non-interpenetrated (4,4) layers via bipyridyl co-ligands. However, the different bridging modes of hfipbb(2-) ligands and the different disposition of the coordinated co-ligands around metal ions result in subtle differences in the final architecture. Thus, 2 is based on a binuclear cluster node, double-stranded hfipbb(2-) linkers, and single-stranded 4,4'-bipy linkers, while 5 is based on a binuclear cluster node and hfipbb(2-) and dpp linkers which are both double-stranded. Among these compounds, the Cd(II) complex 4 is possibly the most interesting because it represents a rare example in which metal centers are linked by carboxylate groups into infinite chains further joined together by hfipbb(2-) spacers to form a 2D network with tubular helical channels. All these coordination polymers exhibit low solvent-accessible volumes. Both 3 and 4 retain structural integrity and permanent microporosity upon evacuation of guest molecules, with hydrogen uptakes of 0.57 and 0.78 wt %, respectively, at

  11. A Surprisingly Simple Electrostatic Model Explains Bent Versus Linear Structures in M(+)-RG2 Species (M = Group 1 Metal, Li-Fr; RG = Rare Gas, He-Rn).

    Science.gov (United States)

    Andrejeva, Anna; Breckenridge, W H; Wright, Timothy G

    2015-11-05

    It is found that a simple electrostatic model involving competition between the attractive dispersive interaction and induced-dipole repulsion between the two RG atoms performs extremely well in rationalizing the M(+)-RG2 geometries, where M = group 1 metal and RG = rare gas. The Li(+)-RG2 and Na(+)-RG2 complexes have previously been found to exhibit quasilinear or linear minimum-energy geometries, with the Na(+)-RG2 complexes having an additional bent local minimum [A. Andrejeva, A. M. Gardner, J. B. Graneek, R. J. Plowright, W. H. Breckenridge, T. G. Wright, J. Phys. Chem. A, 2013, 117, 13578]. In the present work, the geometries for M = K-Fr are found to be bent. A simple electrostatic model explains these conclusions and is able to account almost quantitatively for the binding energy of the second RG atom, as well as the form of the angular potential, for all 36 titular species. Additionally, results of population analyses are presented together with orbital contour plots; combined with the success of the electrostatic model, the expectation that these complexes are all physically bound is confirmed.

  12. Macroinvertebrados bentônicos como indicadores de qualidade de água na Barragem Santa Bárbara, Pelotas, RS, Brasil Zoobenthics as indicators of the water quality in the Santa Bárbara Dam, Pelotas, RS, Brazil

    Directory of Open Access Journals (Sweden)

    Sérgio Renato Noguez Piedras

    2006-04-01

    Full Text Available O objetivo deste trabalho foi estudar o impacto de dois afluentes da barragem Santa Bárbara sobre o ambiente da mesma, utilizando a ocorrência de invertebrados bentônicos e características químicas da água. Durante nove meses foram realizadas coletas e análises da água e de invertebrados bentônicos nos afluentes Sanga da Barbuda e Sanga do Passo do Cunha e também no interior da bacia de acumulação da barragem. Os resultados mostram que, embora a Sanga da Barbuda e a Sanga do Passo do Cunha apresentem características químicas abaixo do recomendável, no limite aceitável pela legislação que determina os padrões de qualidade da água para abastecimento público, estes afluentes estão, ainda, sendo diluídos de forma satisfatória na bacia de acumulação da barragem. O estudo das relações entre variáveis químicas e invertebrados bentônicos mostra haver correlação significativa entre os baixos níveis de oxigênio dissolvido e a presença de Oligochaeta, sendo que o aumento do número de Oligochaeta indica uma situação de anoxia na barragem Santa Bárbara.The objective of this work was to study the impact of two tributaries from the Santa Bárbara Dam on this environment using the occurrence of zoobenthics and some water chemical characteristics. Monthly gathering and analysis from the water and zoobenthics were done during nine months in the tributaries Sanga da Barbuda and Sanga Passo do Cunha as well as in the inner part of the accumulation basin in the Santa Barbara dam. The results demonstrate that, though Sanga da Barbuda and Sanga Passo do Cunha present chemical characteristics lower than the recommended but still in the limits acceptable by the law that regulates the water quality standards for the supply, these tributaries are being diluted in a satisfactory way in the accumulation basin in the Santa Barbara dam. The study of the relations between chemical variables and zoobenthics show a significant correlation

  13. Primer informe del género Gambierdiscus (Dinophyceae y otros dinoflagelados bentónicos en el Parque Nacional Isla del Coco, Costa Rica, Pacífico Tropical Oriental

    Directory of Open Access Journals (Sweden)

    Maribelle Vargas-Montero

    2012-11-01

    Full Text Available El Pacífico Tropical Oriental se ha indicado como una región de los océanos libre de ciguatera, una intoxicación que causa serios trastornos gastrointestinales, neurológicos y cardiovasculares, en casos extremos, la muerte. Pero con el presente estudio hemos encontrado una incidencia alta de microalgas bénticas involucradas en la producción de ciguatera en el Parque Nacional Isla del Coco (PNIC, Costa Rica. En campañas oceanográficas realizadas entre el 2006 y el 2011 al PNIC se recolectaron 420 muestras de fitoplancton con el interés de encontrar especies de dinoflagelados bentónicos implicados en la producción de ciguatera. Las muestras se tomaron con red de fitoplancton o mediante buceos, entre los 5 y 30 m de profundidad en zonas de arrecife y por extracción directa de macroalgas. Se encontró a los dinoflagelados Gambierdiscus spp., Coolia tropicales, Coolia cf. areolota, Prorocentrum concavum, Prorocentrum compressum, Amphidinium carterae y Ostreopsis siamensis. Se determinó que la cantidad de dinoflagelados por peso de macroalga era elevada, principalmente para el género Gambierdiscus. Los géneros Ostreopsis y Prorocentrum mostraron tener la mayor distribución en los sitios de colecta. Gambierdiscus es un género productor de ciguatera. Se encontraron dos tamaños diferentes de individuos de Gambierdiscus, Comparando los especímenes de Gambierdiscus encontradas con otros estudios, se concluye que son diferentes a las descritas anteriormente, por lo que podría tratarse de especies nuevas, lo que se confirmará con cultivos y análisis moleculares. Al ser la Isla del Coco un sitio oceánico aislado y en estado de conservación, es un sitio ideal para el estudio de la evolución de especies de fitoplancton marino. Además, el monitoreo a largo plazo es muy importante debido a la variedad de dinoflagelados bentónicos potencialmente tóxicos que habitan en este ecosistema marino. Este es el primer estudio donde se da a

  14. Estudio sistemático de los Foraminíferos bentónicos de las arenas fosilíferas del plioceno de Huelva: su significado paleológico

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    González-Regalado, M. L.

    1989-04-01

    Full Text Available Benthic Foraminifera are a representative fauna from the Neogene materials in the westem sector of Guadalquivir Basin. The Quantitative variations in different species is the basis of the paleoecologic study in the area. The sistematic study of species with the abundance, samples and sections is given in this papero.Los Foraminíferos bentónicos son muy representativos de los materiales del Neógeno en el sector occidental de la Cuenca del Guadalquivir. Las variaciones en las proporciones de las distintas especies son la base del estudio paleoecológico realizado en el área. En este artículo se presenta el estudio sistemático de las especies determinadas, indicándose la abundancia, muestras y secciones en que se han registrado.

  15. Colonização de macroinvertebrados bentônicos em detritos foliares em um riacho de primeira ordem na Floresta Atlântica do nordeste brasileiro

    OpenAIRE

    Santos, Iris Gabrielly Arruda dos; Rodrigues, Gilberto Gonçalves

    2015-01-01

    O objetivo do estudo foi avaliar a colonização de macroinvertebrados bentônicos em detritos foliares de Inga ingoides (Leguminosae) em experimentos de campo em um riacho de primeira ordem da Mata Atlântica do Estado de Pernambuco no nordeste do Brasil. Um total de 270 bolsas de folhiço, distribuídas em três trechos do riacho com características similares em relação à morfologia e parâmetros físicos e químicos da água foram submersas, entre fevereiro a julho de 2013 e retiradas após 7, 30, 60,...

  16. Historical considerations and comments on the type series of Cyrtodactylus marmoratus Gray, 1831, with an updated comparative table for the bent-toed geckos of the Sunda Islands and Sulawesi.

    Science.gov (United States)

    Mecke, Sven; Kieckbusch, Max; Hartmann, Lukas; Kaiser, Hinrich

    2016-10-17

    Cyrtodactylus marmoratus Gray, 1831, a species of bent-toed gecko exhibiting a precloacal groove in males, was described on the basis of specimens collected by Heinrich Kuhl and Johan Conrad van Hasselt in Java, Greater Sunda Islands, Indonesia. Kluge (1985) subsequently designated a lectotype for C. marmoratus from a series of these specimens (i.e., syntypes), now housed in the herpetological collection at Naturalis (formerly the Rijksmuseum van Natuurlijke Historie; RMNH), Leiden, the Netherlands. Our work at Naturalis shows that the type series of C. marmoratus at RMNH actually comprises two sets of specimens, and that examination of specimens from one set or the other by different authors, including Kluge (1985), is responsible for some confusion surrounding the type series of this species. As a consequence, we present relevant morphological data for all 14 specimens constituting the type series of C. marmoratus at RMNH for the first time. The type status of two specimens of C. marmoratus in the collection at the Muséum National d'Histoire Naturelle, Paris, France, remains unresolved at present. Owing to the inconsistent naming and application of terms for some key characters (e.g., groove, sulcus, pit, hollow, depression) used in the diagnoses of Cyrtodactylus species, we here propose a set of novel and useful definitions that are supported by photographs. We also illustrate the sexually dimorphic expression of this character in C. marmoratus. Finally, we present a revised comparative table for the bent-toad geckos of the Sunda Islands and Sulawesi.

  17. Estrutura da comunidade de macroinvertebrados bentônicos de um riacho de serra em Itatinga, São Paulo, Brasil Structure of a benthic macroinvertebrates community in a mountain stream in Itatinga, São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Ludmilla O. Ribeiro

    2005-09-01

    Full Text Available A comunidade de macroinvertebrados bentônicos de um riacho de terceira ordem foi analisada em duas estações do ano, chuvosa e seca. Substratos artificiais foram amostrados semanalmente, ao longo de 56 dias para a coleta de macroinvertebrados, nas duas estações do ano. A composição da comunidade foi caracterizada por uma baixa diversidade, ou seja, presença de muitas espécies raras e poucas espécies abundantes nas duas estações do ano. Uma alta dominância de Chironomidae (Diptera nas duas estações, seguida de Baetidae (Ephemeroptera e Ancylidae (Mollusca, respectivamente nas estações chuvosa e seca, foi característico. Os resultados obtidos reforçam a grande importância de Chironomidae na comunidade bentônica de riachos e salientam a influência da sazonalidade sobre a estruturação destes organismos.The benthic macroinvertebrates community of a third order stream was studied during the wet and dry seasons. The community was analyzed using artificial substrates sampled weekly during 56 days in each season. The community composition was characterized by low species diversity, with high number of rare species and few abundant species for both seasons. A high dominance of Chinonomidae (Diptera for both seasons, followed by Baetidae (Ephemeroptera and Ancylidae (Mollusca, respectively for the wet and dry seasons, was found. The results reinforced the high importance of Chironomidae and the seasonal effect determining the stream benthic community structure.

  18. Efecto de sedimentos naturales enriquecidos con zinc, en modelos aislados y en microcosmos, sobre tres especies de invertebrados bentónicos

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    Marcela Galar Martínez

    2006-06-01

    Full Text Available En los cuerpos acuáticos la disponibilidad de los tóxicos es limitada por las características fisicoquímicas de los sedimentos y agua, así como por las interacciones entre los diversos xenobióticos y entre las especies que los habitan. Por lo anterior, el objetivo del presente trabajo fue relacionar el efecto producido por el zinc (Zn sembrado en sedimentos del embalse Ignacio Ramírez (PIR, en modelos aislados y en microcosmos, sobre el ATP de tres organismos bentónicos con la biodisponibilidad del metal. Las especies seleccionadas fueron: Hyalella azteca, Limnodrilus hoffmeisteri y Stagnicola attenuata, dado que se encuentran en altas proporciones en el embalse y ocupan espacios diferentes en el bentos. Las muestras de sedimentos y organismos se colectaron en la estación de sequía (febrero de 1999. A los primeros se les determinó el pH, textura, tamaño de partícula, nitrógeno total, materia orgánica y concentración de metales (Zn, Fe, Cu y Ni. Posteriormente se realizó un estudio de toxicidad subletal utilizando dos tipos de sistemas estáticos (organismos aislados y en microcosmos. Ambos modelos contenían sedimentos de la PIR enriquecidos con Zn (concentración nominal de 0.8129 mg/kg y agua sintética en una proporción de 1:4. Los organismos de prueba fueron adicionados una vez alcanzado el equilibrio (2 hr considerando la cantidad de biomasa con respecto al volumen (1.0 g de organismo por cada 100 ml de agua:sedimento. Después de 0, 12, 24, 36, 48 y 72 hr de exposición se tomaron muestras del sedimento y de los hidrobiontes, a los cuales se les cuantificó el contenido de Zn por absorción atómica. A los organismos también se les determinó la concentración de ATP. Los resultados obtenidos muestran que el efecto producido por los sedimentos naturales enriquecidos se ve potenciado por la presencia de más de una especie en el sistema (microcosmos. Con respecto a los niveles de Zn, dos de los organismos (L. hoffmeisteri

  19. Effects of carbofuran and metsulfuron-methyl on the benthic macroinvertebrate community in flooded ricefields Efeito do carbofurano e metsulfuron-methyl sobre a comunidade de macroinvertebrados bentônicos de lavoura de arroz irrigado

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    Joele Baumart

    2011-06-01

    Full Text Available AIM: This study evaluated the effect of the insecticide carbofuran and the herbicide metsulfuron-methyl on the abundance and diversity of benthic macroinvertebrates in a paddy ricefield. METHODS: To achieve this goal, two pesticide treatments [the insecticide carbofuran (IC and the herbicide metsulfuron-methyl (HM] and a control (Co treatment with no added pesticide were established in an experimental area of the Plant Science Department of the Federal University of Santa Maria. Soil samples were collected in triplicate from each treatment 30 days before and 1, 10, and 51 days after the pesticide application, for macrofauna identification. RESULTS: Among the 21 taxa identified, Trichoceridae was present only in Co, Hydroptilidae was recorded only in IC, and Corixidae in HM. In Co, the most abundant group was Annelida, while in IC and HM Diptera (Chironomidae was dominant. Significant differences were observed between Co and IC, in the density of Odontoceridae (Control>IC and Hydrophilidae (ControlHM and Hirudinea (ControlOBJETIVO: O objetivo desse estudo foi avaliar o efeito do inseticida carbofurano e do herbicida metsulfuron-methyl na abundância e diversidade de macroinvertebrados bentônicos em campo de arroz irrigado. MÉTODOS: Para isto, dois tratamentos com agrotóxicos [o inseticida carbofurano (IC e o herbicida metsulfuron-methyl (HM] e um controle (Co, tratamento sem pesticida, foram aplicados em uma área experimental no Departamento de Fitotecnia da Universidade Federal de Santa Maria. Amostras de solo foram coletadas em triplicatas em cada tratamento 30 dias antes (DBA e 1, 10 e 51 dias após a aplicação dos pesticidas, posteriormente a macrofauna foi identificada. RESULTADOS: Vinte e um (21 taxa foram identificados, entre esses Trichoceridae esteve presente apenas em Co, enquanto que Hydroptilidae foi coletado apenas em IC, e Corixidae em HM. Em Co e IC, o grupo mais abundante foi Annelida, e em HM foi Diptera (Chironomidae que

  20. The benthic macroinvertebrate fauna of highland streams in southern Brazil: composition, diversity and structure Fauna de macro-invertebrados bentônicos de rios de montanha no sul do Brasil: composição, diversidade e estrutura

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    Ludwig Buckup

    2007-06-01

    Full Text Available Benthic macroinvertebrate in four rivers, three in the Pelotas River basin (Divisa, Marco and Silveira rivers, in the headwaters of the Uruguai River and one in the Taquari-Antas system (Antas River, a tributary in the Guaíba basin, in the state of Rio Grande do Sul, were identified. Two samples were collected in summer, autumn and spring, with one replicate in each river. The total of 28,961 specimens included members of Platyhelminthes, Annelida, Acarina, Insecta, Crustacea and Mollusca. The Silveira and Marco rivers showed significant differences in the indices of Shannon-Weaver (H’, Simpson’s Reciprocal (1/D, Margalef (DMg and Equitability (E. The Silveira River showed the highest means of diversity and the EPT index (Ephemeroptera, Plecoptera, Trichoptera. Comparison among the diversity indices, considered individually, were insufficient to show differences in community structure, for the purpose of ecological characterization of the rivers. The EPT values characterized the Divisa River as having the highest abundance (73%, followed by the Marco (71%, Antas (48% and Silveira (36%. These results suggest that the Silveira River is subject to moderate environmental stress, from human impact, although it showed the highest diversity of the major macrobenthic groups.Os macro-invertebrados bentônicos que ocorrem em quatro rios, três pertencentes à bacia do Rio Pelotas (Rios Divisa, Marco e Silveira nas cabeceiras do Rio Uruguai e um ao sistema Taquari-Antas (Rio Antas, tributário da bacia do Guaíba, no Estado do Rio Grande do Sul, foram identificados. Duas amostras foram coletadas no verão, outono e primavera, com uma réplica em cada rio. Foram coletados 28961 espécimes de macro-invertebrados compreendendo Platyhelminthes, Annelida, Acarina, Insecta, Crustacea e Mollusca. Na comparação entre os rios, Silveira e Marco mostraram diferenças significativas nos índices de Shannon-Weaver (H’, no Recíproco de Simpson (1/D, de

  1. A new species of bent-toed gecko, genus Cyrtodactylus Gray, 1827 (Reptilia: Squamata: Gekkonidae), from Jawa Timur Province, Java, Indonesia, with taxonomic remarks on C. fumosus (Müller, 1895).

    Science.gov (United States)

    Hartmann, Lukas; Mecke, Sven; Kieckbusch, Max; Mader, Felix; Kaiser, Hinrich

    2016-01-26

    A new species of the gekkonid lizard genus Cyrtodactylus Gray, 1827 is described from Klakah, Lumajang Regency, Jawa Timur Province, Java, Indonesia. Cyrtodactylus klakahensis sp. nov. can be distinguished from all other congeners by the presence of (1) a deep precloacal groove in males, (2) three rows of enlarged precloacofemoral scales, of which the third row bears 37-38 pores in males, (3) three or four rows of enlarged scales between the precloacofemoral scale rows and the cloaca, forming distinct chevrons, (4) raised and strongly keeled dorsal tubercles in 15-19 rows at midbody, (5) an indistinct lateral fold, (6) 17-20 subdigital lamellae under the 4th toe, and (7) subcaudal scales which are not transversely enlarged. Cyrtodactylus klakahensis sp. nov. is only the third bent-toed gecko species described from Java, indicating that the diversity of this genus on this island has been neglected in the past. Furthermore, we confirm that C. fumosus (Müller, 1895) is a species that possesses a precloacal groove in males and is most likely restricted to northern Sulawesi. That species is defined by a single female holotype (NMB-REPT 2662). Specimens in museum collections catalogued as C. fumosus from localities elsewhere are misidentified and likely represent undescribed species.

  2. Gobernanza y capital social en el co-manejo de recursos bentónicos en Chile: aportes del análisis de redes al estudio de la pesca artesanal de pequeña escala.

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    Stefan Gelcich

    2012-09-01

    Full Text Available El co-manejo o manejo colaborativo es considerado una institución relacional ya que pone el énfasis, no sólo en la administración de los recursos propiamente tales, sino en las relaciones sociales que se establecen entre múltiples actores con diversos intereses en el territorio. Por esto, existe un creciente interés en su estudio desde el análisis de redes sociales (ARS y el concepto afín de capital social. En este artículo presentamos dos aplicaciones del uso de ARS para comprender el co-manejo, utilizando el sistema chileno de Áreas de Manejo y Explotación de Recursos Bentónicos (AMERB como caso de estudio. Específicamente se aplican herramientas del ARS para: (1 describir y analizar la red de gobernanza que subyace el régimen de AMERB, y (2 explorar el rol del capital social de las organizaciones de pescadores en el funcionamiento y desempeño del co-manejo. En base a las aplicaciones descritas en el artículo planteamos que el enfoque de redes sociales entrega una mirada promisoria y complementaria para el desarrollo y reformulación de políticas públicas más efectivas y con creciente participación de las comunidades locales.

  3. Disjoint geographical distribution of intertidal and nearshore benthic invertebrates in the Southern Hemisphere Distribuciones geográficas disyuntas de invertebrados bentónicos intermareales y del submareal somero en el Hemisferio Sur

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    JUAN C CASTILLA

    2000-12-01

    Full Text Available Biogeographical explanations for the extant and paleo disjoint geographical distribution in the southern hemisphere of five species of nearshore marine benthic invertebrates: Gaimardia trapesina, Ostrea chilensis, Pyura stolonifera taxonomic complex, Aulacomya ater and Concholepas concholepas, showing distinctive reproductive strategies and early life history characteristics are reviewed and analyzed. Through the use of published and new information we contrasted the following hypotheses: a vicariance-historical process, b epiplanktonic larval dispersal, c juvenile/adult dispersal through rafting and d planned or accidental anthropogenic dispersal mechanisms. The juvenile/adult transoceanic dispersal hypothesis by rafting was the only one impossible to be rejected for the species analyzed. The implication and future direction for research in this area are discussedSe revisa y analiza las posibles explicaciones para la distribución geográfica disyunta, presente y pasada, en el hemisferio sur de cinco especies de invertebrados bentónicos marinos litorales: Gaimardia trapesina, Ostrea chilensis, el complejo taxonómico Pyura stolonifera, Aulacomya ater y Concholepas concholepas, con estrategias reproductivas y características de historia de vida distintas. Se discute y pone a prueba, usando información original o publicada, las siguientes hipótesis: a procesos históricos de vicarianza, b dispersión de larvas epi-planctónicas, c dispersión de juveniles o adultos por transporte pasivo y d dispersión antropogénica planificada o accidental. La hipótesis de dispersión transoceánica de juveniles o adultos fue la única imposible de rechazar para las especies analizadas. Se discute las direcciones futuras de investigación en esta área

  4. Efeito de metais Cobre (Cu e Zinco (Zn sobre a comunidade de macroinvertebrados bentônicos em riachos do sul do Brasil - DOI: 10.4025/actascibiolsci.v30i3.677 The effect of metals (Cu and Zn on the benthic macroinvertebrate community in streams in southern Brazil - DOI: 10.4025/actascibiolsci.v30i3.677

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    Luiz Ubiratan Hepp

    2008-10-01

    Full Text Available O objetivo deste estudo foi avaliar os efeitos de metais (Cu e Zn sobre a comunidade de macroinverterados bentônicos. Foram amostrados, trimestralmente, entre setembro de 2006 e junho de 2007, organismos e água em oito trechos de riachos de duas bacias hidrográficas influenciadas por urbanização e agricultura. Foram estimados os valores de densidade de organismos, riqueza taxonômica e diversidade de Shannon. Para avaliação dos dados, foram utilizados testes de variância e regressão linear simples. Os resultados demonstraram variabilidade das concentrações dos metais e da macrofauna entre as estações do ano e riachos estudados. O metal Cobre (Cu apresentou influência apenas sobre a densidade Chironomidae e o metal Zinco (Zn apresentou efeito sobre a densidade total da macrofauna bentônica e de Chironomidae. Nenhum dos metais apresentou efeitos sobre a riqueza e diversidade de macroinvertebrados. Os resultados indicam potencial bioindicador da comunidade bentônica na avaliação da qualidade integrada do ambiente.The aim of this study was to evaluate the effect of metals (Cu and Zn on the benthic macroinvertebrate community. The organisms and water were collected quarterly between September 2006 and June 2007, in eight sites in streams of two hydrographic basins, influenced by urbanization and agriculture. The values of organism density, taxonomic richness and the Shannon diversity index were calculated. For data evaluation, tests of variance and simple linear regression were used. The results showed variability in the metal concentration and benthic community among seasons and studied streams. Cu showed influence only on Chironomidae density. Zn demonstrated effect on the benthic community and Chironomidae density. None of the metals presented effect on the macroinvertebrate richness and diversity. The results indicate a bioindicator potential of the benthic community in the evaluation of integral quality of the environment.

  5. Identificación de macro invertebrados bentónicos en los ríos: Pindo Mirador, Alpayacu y Pindo Grande; determinación de su calidad de agua

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    Alexandra Endara

    2012-12-01

    Full Text Available En un estudio realizado en el mes de mayo del 2012, utilizando una red Surber de 30 x 30 cmde área de superficie y 0,5 mm de abertura de malla, en los ríos: Pindo Mirador, Pindo Grandey Alpayacu, ubicados en el sector de Mera, provincia de Pastaza de la Amazonía ecuatoriana,se analizó la diversidad y la abundancia de los macro invertebrados bentónicos utilizando losíndices BMWP/Col y EPT. Se logró determinar que la calidad del agua de los ríos PindoMirador y Pindo Grande es buena mientras la del río Alpayacu es mala. Este estudio da unaidea general de la situación ambiental de los ecosistemas lóticos cercanos a la EstaciónBiológica Pindo Mirador. Los resultados de ésta investigación permiten determinar laimportancia de las micro-cuencas de los ríos Pindo Mirador y Pindo Grande como fuente deagua para las poblaciones que se encuentran río abajo, así como el modo en el cual lapresencia o ausencia de organismos bioindicadores (macroinvertebrados indica la calidad delagua y de los bosques de la micro-cuenca.Abstract:In May 2012, using a 30x30 cm surface and 0.5 mm aperture Surber net in the rivers: PindoMirador, Pindo Grande and Alpayacu, located in Mera, Pastaza, Ecuadorian Amazonia, thediversity and abundance of macro invertebrates was analyzed applying the BMWP/Col and theEPT indexes. It was determined the good Pindo Mirador, Pindo Grande and Alpayacu rivers’water quality, as well as the bad Alpayacu river’s water quality. This work provides an overviewof the environmental situation of aquatic ecosystems near Pindo Mirador Biological Station, ithighlights the importance of the rivers’ micro-watersheds near Pindo Mirador Biological Station,used as water source by the populations living downstream, and shows how macroinvertebrates can be used as bioindicators for the water and forests quality.

  6. Patrones de distribución espacial de ensambles de macroinvertebrados bentónicos de un sistema fluvial Andino Patagónico Spatial distribution patterns of benthic macroinvertebrates assemblages in an Andean Patagonian fluvial system

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    CAROLINA MOYA

    2009-01-01

    Full Text Available En enero de 2006 se estudiaron los patrones espaciales de distribución de comunidades de macroinvertebrados bentónicos de la cuenca hidrográfica del río Baker (45°50' O y 47°55' S y los principales factores controladores, intentando cubrir la mayor variedad de ecosistemas lóticos. Para llevar a cabo el estudio se seleccionaron 27 estaciones de muestreo ubicadas en las diferentes subcuencas del río. En cada estación se realizó una caracterización fisicoquímica del agua (conductividad, oxígeno disuelto, pH, temperatura y turbidez, y se documentaron las características del tramo de río (e.g. ancho del cauce y tipo de sedimento e información cartográfica utilizando un sistema de información geográfica (SIG. Se identificaron un total de 51 taxa que correspondieron en su mayoría a larvas de insectos (80 %. Los grupos con mayor riqueza fueron los órdenes Ephemeroptera (15 taxa, Plecoptera (8 taxa y Trichoptera (8 taxa. Los análisis de clasificación y ordenación realizados con los datos de abundancia, permitieron reconocer siete grupos de estaciones diferentes (A-F que fueron estadísticamente significativos (P In January of 2006 we studied the distributional patterns of benthic macroinvertebrate communities of the Baker river basin (45°50' O and 47°55' S and their main controlling factors trying to cover the greater variety of the lotic ecosystems. To carry out the study, 27 sampling stations were located in the different sub basins of the river. In each station, physical-chemical parameters of the column of water were quantified (conductivity, dissolved oxygen, pH, temperature and turbidity, and documented characteristics of the segment (e.g. wide of the channel and sediment type and cartographic information using a geographic information system (GIS and complemented with cartographic information using GIS. Identified a total of 51 taxa, are mostly insect larvae (80 %. The groups most richness were orders Ephemeroptera (15

  7. Impacto de la captura ilegal en pesquerías artesanales bentónicas bajo el régimen de co-manejo: el caso de Isla Mocha, Chile

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    Ricardo M Bandin

    2014-07-01

    Full Text Available El régimen de Áreas de Manejo y Explotación de Recursos Bentónicos (AMERB en Chile, considerado uno de los más grandes experimentos de co-manejo a escala global, enfrenta aún amenazas como el robo de recursos. En las AMERB dedicadas al recurso 'loco' (Concholepas concholepas la administración pesquera establece capturas totales permisibles suponiendo robos nulos, comprometiendo asi su sustentabilidad. Tomando como caso de estudio las AMERB dedicadas al recurso 'loco' en la Isla Mocha, mediante entrevistas a usuarios de AMERB, consultas a autoridades fiscalizadoras, y acopio de data secundaria, se reconstruyó una serie anual de robos, se simuló el impacto bio-económico del robo en una AMERB, y se sistematizó la opinión de los usuarios sobre las causas del robo y sus posibles soluciones. Los robos representan entre 32-68% de los ingresos brutos anuales históricos de las AMERB. Según las proyecciones bio-económicas, un stock de 'loco' en AMERB seria resiliente a toda combinación de niveles propuestos de 'Robo', 'Reglas de Cosecha' y 'Precios de Loco', excepto ante un 'Robo Descontrolado' (i.e., doble de la tasa de mortalidad por robo máxima histórica que agota la pesquería formal. Los usuarios de AMERB consideran más grave al robo realizado por pescadores no-isleños respecto del robo isleño, identificando incentivos comunes a ambos; esperan mayor acción del Estado sobre los infractores no-isleños, y confían más en sus propias organizaciones para controlar a los infractores isleños. Para combatir los robos en AMERB se propone mitigar sus incentivos socio-económicos, asignar en algunos casos derechos exclusivos de acceso territorial a las organizaciones asignatarias, y definir estrategias contra las operaciones ilegales previa conciliación de objetivos entre autoridades y grupos de interés.

  8. Impacto de "El Niño 1997-98" sobre el asentamiento larval de algunos invertebrados marinos bentónicos de bahía Independencia, Pisco -Perú

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    Elmer Ramos

    2014-06-01

    Full Text Available Se evaluó mensualmente los cambios y la magnitud del impacto de "El Niño" (EN, sobre el mecanismo del asentamiento larval de algunos invertebrados marinos bentónicos, en sustratos artificiales filamentosos (fibra nylon, entre enero 1996 y julio 1998, en una estación fija, a 10m de profundidad, situada en el lado oriental de la Isla Independencia, en Bahía Independencia, Durante 1996, en la fase fría "La Niña" (LN, el número de especies presentó un pico en abril y la densidad en junio. En la fase cálida EN 199798, la densidad total y el número de especies, presentaron un primer pico en marzo de 1997, luego, un segundo pico, en febrero y julio de 1998, respectivamente. Un primer grupo de especies que intensificó su asentamiento durante la fase fría LN 1996, estuvo constituido por el bivalvo Hiatella solida, el turbelario Notoplana sp. y el gastrópodo Caecum chilense. El segundo grupo intensificó su asentamiento en la etapa temprana de la fase cálida EN 1997-98, Y lo formaron el braquiópodo Discinisca lamel/osa, el equinodermo Ophíactís kr6yerí y bivalvos de la Familia Mytllidae, Un tercer grupo, mostró una intensificación del asentamiento larval, en la etapa tardía de la fase cálida EN 1997-98, a inicios de 1998, y fue formado por el bivalvo Argopecten purpuratus y un gastrópodo turriforme. La aparición de larvas recién asentadas de especies tropicales, como el bivalvo Ptería stema y el gastrópodo Epitoníum sp., tuvo lugar en la etapa tardía de la fase cálida EN 1997-98.

  9. Benthic macroinvertebrate assemblages structure in two headwater streams, south-eastern Brazil Estrutura das assembléias de macroinvertebrados bentônicos em dois córregos de cabeceira no sudeste do Brasil

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    Taynan H. Tupinambás

    2007-12-01

    Full Text Available From December 2003 to September 2004, benthic macroinvertebrates (BM, fishes, water and sediment were collected quarterly at six stations in two streams of the upper São Francisco River basin, south-eastern Brazil. We evaluated the ecological conditions, habitat diversity, water quality, composition and structure of BM communities, as well as the food habits of the local fish fauna. By applying a protocol for rapid characterization of ecological conditions and habitat diversity, three of the sampled localities were classified as "pristine" while the others stations were considered "altered". A well oxygenated water with near neutral pH and low electric conductivity ( 60%. Our results show that human activities such as forest clearing, agriculture and cattle rising have altered the habitat diversity in freshwater ecosystems in a process that affects the aquatic biota and thus the food availability to the fish fauna. The results also highlight the importance of the fish stomach contents analysis as a complementary tool in BM inventories.Entre dezembro de 2003 e setembro de 2004, macroinvertebrados bentônicos (MB e peixes foram capturados e amostras de água e sedimento foram coletadas trimestralmente em seis pontos de dois córregos de cabeceira da bacia do rio São Francisco. Foram avaliadas as condições ecológicas, diversidade de hábitats, qualidade da água, composição e estrutura das comunidades de MB, bem como sua ocorrência na dieta da ictiofauna local. Três trechos amostrados foram classificados como "naturais" e os demais como "alterados". As águas mostraram-se bem oxigenadas, com pH próximo ao neutro, com condutividade elétrica ( 60%. Os resultados sugerem que atividades humanas como desmatamento, agricultura e extração de areia têm alterado a diversidade de hábitats em ecossistemas aquáticos de água doce, em um processo que afeta a biota aquática e consequentemente a disponibilidade de alimento para a ictiofauna. Foi

  10. Hear Here : Hoor waar je bent

    NARCIS (Netherlands)

    Hartendorp, Mijke; Steyvers, Frank

    2013-01-01

    The poster presents the idea for a research project: how can we use the proficiency in wayfinding an navigation of people that have congenital or early visual impairments and that learned to use environmental soundmarks for the development of a tool or application in the training of people who get

  11. Post Impressions: Music Writing as Bent Travelogue

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    Hollis Taylor

    2011-08-01

    Full Text Available The wind is our universal musician and has been recognized as such for millennia. If the wind can play a fence as an aeolian harp, then a violinist armed with a bow could also cause these gigantic structures to sing. Thus, an American woman and an Australian man set out to explore and perform on the giant musical instruments covering the continent of Australia: fences. This presentation excerpts highlights from the voyage, illuminating the range of sounds to be drawn out of a five-wire fence. Playing fences reveals a sound world that is embedded in the physical reality and the psyche of the culture. In pursuit of their instruments, including the Rabbit-Proof Fence and the 5300-kilometre–long Dingo Fence, the duo travels 40,000 kilometres, engaging with a singing dingo, an auctioneer, an Aboriginal gumleaf virtuoso, bush musicians, the first (now ruined piano in Central Australia, and the School of the Air’s distorted, modulating, phasing white and pink electronic noise. PLEASE NOTE: there are four supplementary files that accompany this contribution. Click on the tab 'Supplementary Files' on the right hand side of the screen when accessing the pdf of the article.

  12. Riparian leaf litter processing by benthic macroinvertebrates in a woodland stream of central Chile Procesamiento de detritus ripariano por macroinvertebrados bentónicos en un estero boscoso de Chile central

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    CLAUDIO VALDOVINOS

    2001-06-01

    un importante impacto sobre las características energéticas de las comunidades fluviales de Chile central. Actualmente, los bosques exóticos existentes en esta área están compuestos principalmente por Pinus radiata (D. Don (pino insigne, llegando a cerca. del 80 % de las más de 1.800.000 ha de plantaciones forestales. El objetivo de este estudio fue analizar el efecto de camadas de hojas de una especie nativa dominante (Nothofagus pumilio y una especie exótica (P. radiata sobre el procesamiento de detritus realizado por macroinvertebrados bentónicos, en una cuenca experimental de Chile central (estero Rucúe; 36° 20' 00" S, 71° 47'40" O. Los resultados muestran que las tasas de procesamiento de los paquetes de hojas de la especie nativa son superiores a la exótica, sugiriendo que la sustitución de la flora nativa caducifolia por coníferas exóticas tiene un importante impacto sobre los componentes energéticos de los ecosistemas fluviales de Chile central. Los coeficientes de pérdida (k fueron 0,0072 para N. pumilio y 0,0027 para P. radiata. La abundancia y biomasa de fragmentadores por gramo de paquete de hojas explican las diferencias en las tasas de procesamiento de hojas, especialmente dos plecópteros Gripopterygidae, Limnoperla jaffueli y Antarctoperla michaelseni

  13. Zoogeografía de macroinvertebrados bentónicos de la costa de Chile: contribución para la conservación marina Zoogeography of benthic macroinvertebrates of the Chilean coast: contribution for marine conservation

    Directory of Open Access Journals (Sweden)

    DOMINGO A. LANCELLOTTI

    2000-03-01

    Full Text Available La diversidad de macroinvertebrados marinos ha recibido una atención creciente, no obstante, con un escaso tratamiento en el contexto biogeográfico. Este estudio analiza los registros de 1.601 especies de macroinvertebrados bentónicos pertenecientes a: Demospongiae, Anthozoa, Polychaeta, Mollusca, Crustacea, Echinodermata y Ascideacea, agrupados en 10 zonas y tratados desde una perspectiva zoogeográfica. Mollusca (611 especies, Polychaeta (403 y Crustacea (370 corresponden a los grupos mejor representados a lo largo de la costa chilena, determinantes en el patrón global de la biodiversidad. Este aumenta suavemente de norte a sur, interrumpido por máximos que sugieren esfuerzos diferenciales de estudio más que un comportamiento natural de la biodiversidad. El grado de agrupamiento entre las zonas muestra las tres unidades biogeográficas definidas recientemente por Lancellotti & Vásquez. Este arreglo, que representa lo exhibido por los grupos más diversos, se ve alterado en los grupos menos representados donde las diferencias obedecen al patrón de afinidades mostradas por las zonas comprendidas dentro de la Región Templada Transicional. El quiebre zoogeográfico alrededor de los 41º S, sugerido largamente en la literatura, sólo ocurre en Echinodermata y Demospongiae, evidenciando en los otros taxa la existencia de un área de transición entre los 35º y 48º S, caracterizada por un reemplazo gradual de especies. Dentro de las regiones la biodiversidad muestra homogeneidad, contrario al endemismo, el que alcanza un máximo de 52% en la Región Templada Fría y que parece ser consecuencia del alto número de especies con registros únicos (38,2% de especies citadas para una sóla zona. Esto sugiere un desconocimiento de los macroinvertebrados chilenos (distribución y diversidad, sobrestimando el endemismo regional y distorsionando los patrones locales de biodiversidadThe diversity of marine macroinvertebrates has received increasing

  14. Macroinvertebrados bentónicos como indicadores de calidad de agua de ríos del sur de Chile Benthic macroinvertebrates as indicators of water quality of southern Chile rivers

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    RICARDO FIGUEROA

    2003-06-01

    Full Text Available La Cuenca Hidrográfica del Río Damas (40°39' S, 72°23' O, presenta una intensa actividad agrícola y ganadera en un 78,2 % de su superficie, lo cual se ha traducido en importantes aportes de nutrientes al ecosistema acuático. Los objetivos de este estudio fueron: (a analizar la distribución espacial de la macrofauna bentónica en la cuenca y (b determinar la viabilidad de utilizar el Índice Biótico de Familias (IBF para evaluación de la calidad de las aguas. Los muestreos se realizaron en enero de 1998 con una red Surber (0,09 m², en 15 sitios distribuidos en el curso principal y sus tributarios. Se registró un total de 77 taxa, siendo los grupos más diversos Plecoptera (16 %, Trichoptera (16 %, Diptera (14 % y Ephemeroptera (12 %. Se observó una marcada tendencia a la disminución de riqueza específica desde la cabecera de la cuenca hacia aguas abajo. Las abundancias, biomasas y el IBF, presentaron una tendencia inversa a la riqueza específica. IBF se correlacionó significativa y positivamente con el fósforo total (r² = 0,71, temperatura (r² = 0,66, nitrito (r² = 0,56, conductividad eléctrica (r² = 0,50, demanda biológica de oxígeno (r² = 0,46 y nitrógeno total (r² = 0,46, y negativamente con oxígeno disuelto (r² = 0,53, variables estrechamente asociadas al uso intensivo de fertilizantes en la cuenca. Los resultados sugieren que el IBF es un buen indicador de la calidad de las aguas de los ríos de cuencas agrícolas y ganaderas del sur de ChileThe Damas River Hydrographic Basin (40°39'S, 72°23' W presents an intense agricultural and cattle ranching activities in 78.2 % of its surface, which has resulted in important inputs of nutrients into the aquatic ecosystem. The objectives of this study were: (a to analyze the spatial distribution of the benthic macrofauna in the Damas basin, and (b to determine the feasibility of using the Families Biotic Index (FBI for the evaluation of water quality. The samplings were

  15. Choosing the best non-parametric richness estimator for benthic macroinvertebrates databases Eligiendo el mejor estimador no paramétrico para calcular riqueza en bases de datos de macroinvertebrados bentónicos

    Directory of Open Access Journals (Sweden)

    Carola V. Basualdo

    2011-06-01

    Full Text Available Non-parametric estimators allow to compare the estimates of richness among data sets from heterogeneous sources. However, since the estimator performance depends on the species-abundance distribution of the sample, preference for one or another is a difficult issue. The present study recovers and revalues some criteria already present in the literature in order to choose the most suitable estimator for streams macroinvertebrates, and provides some tools to apply them. Two abundance and four incidence estimators were applied to a regional database at family and genus level. They were evaluated under four criteria: sub-sample size required to estimate the observed richness; constancy of the sub-sample size; lack of erratic behavior and similarity in curve shape through different data sets. Among incidence estimators, Jack1 had the best performance. Between abundance estimators, ACE was the best when the observed richness was small and Chao1 when the observed richness was high. The uniformity of curves shapes allowed to describe the general sequences of curves behavior that could act as references to compare estimations of small databases and to infer the possible behavior of the curve (i.e the expected richness if the sample were larger. These results can be very useful for environmental management, and update the state of knowledge of regional macroinvertebrates.Los estimadores no paramétricos permiten comparar la riqueza estimada de conjuntos de datos de origen diverso. Empero, como su comportamiento depende de la distribución de abundancia del conjunto de datos, la preferencia por alguno representa una decisión difícil. Este trabajo rescata algunos criterios presentes en la literatura para elegir el estimador más adecuado para macroinvertebrados bentónicos de ríos y ofrece algunas herramientas para su aplicación. Cuatro estimadores de incidencia y dos de abundancia se aplicaron a un inventario regional a nivel de familia y género. Para

  16. Controlling factors of benthic macroinvertebrates distribution in a small tropical pond, lateral to the Paranapanema River (São Paulo, Brazil Macroinvertebrados bentônicos e fatores controladores de sua distribuição em uma pequena lagoa tropical adjacente ao rio Paranapanema (São Paulo, Brasil

    Directory of Open Access Journals (Sweden)

    Erika Mayumi Shimabukuro

    2011-06-01

    Full Text Available AIM: The aim of the present study was to examine the benthic fauna in a marginal pond lateral to the Paranapanema River and to identify the main controlling factors of its distribution. Considering the small size of the lacustrine ecosystem, we expected that seasonal variations of the benthic community attributes are more important than spatial variations; METHODS: Two samplings, one in March and another in August, were carried out at nine sites in the pond. Sediment samples were obtained through a Van Veen grab for invertebrate sorting, granulometric analysis, and for quantification of organic matter in sediment. Other abiotic factors were measured, such as water transparency, dissolved oxygen, pH, electric conductivity, temperature, and depth of sediment sampling sites. Regarding the comparative analysis at spatial scale, no significant variations in density of the benthic invertebrate community were found. RESULTS: In relation to the studied abiotic factors, only depth presented significant differences among sampling sites; All the measured environmental parameters presented significant differences among sampling months, except depth and the physical and chemical characteristics of the sediment. The abundance of Chaoboridae and Chironomidae was the unique attribute with a significant difference in comparing the two months. A higher abundance of taxa occurred in August, especially for Oligochaeta, Nematoda, Chaoboridae, and Chironomidae; CONCLUSIONS: Because of the low structural complexity of the studied pond, we concluded that the changes in benthic macroinvertebrate community attributes were mainly due to seasonal effects.OBJETIVO: O presente estudo tem por objetivo examinar a fauna bentônica em lagoa marginal ao rio Paranapanema e os principais fatores reguladores da sua distribuição. Devido ao pequeno tamanho do ambiente lacustre, procurou-se mostrar que as variações sazonais dos atributos da comunidade bentônica são mais

  17. Size structure of a heavily fished benthic/demersal community by shrimp trawling in the Colombian Caribbean Sea Estructura de tamaños de una comunidad bentónica/demersal fuertemente impactada por la pesca de arrastre camaronero en el Mar Caribe de Colombia

    Directory of Open Access Journals (Sweden)

    Paúl Gómez-Canchong

    2011-01-01

    Full Text Available The benthic and demersal communities in the Colombian Caribbean Sea (CCS are heavily fished by the shrimp trawling fishery, which presents very high discard levels. Here, we conducted an analysis of the size structure of these benthic and demersal communities in the northern and southern zones of the CCS. Sampling was conducted onboard shrimp trawlers throughout an entire year. No significant differences were found in the size distributions of the two zones, among sites within southern ecoregions, or among the analyzed cruises. This homogeneity in size structure is remarkable since the zones analyzed possess very different species compositions and environmental conditions. The observed size structures were adequately described by non-linear distributions rather than the traditionally employed linear normalized biomass size spectra. It is hypothesized that the non-linearity is due to the effect of fishing and particularly, of discarding. This study emphasizes the need for a greater understanding of the impacts that trawl fishing has on community size structure and the applicability of this knowledge towards fishery resource management in ecosystems with high diversity.Las comunidades bentónico-demersales en el Mar Caribe de Colombia (MCC son fuertemente explotadas por la pesca de arrastre camaronero, presentando niveles de descarte muy altos. Se efectuó un análisis de la estructura de tamaños de estas comunidades bentónico-demersales en las zonas norte y sur del MCC. Se realizaron muéstreos a bordo de las embarcaciones de arrastre de camarón a lo largo de un año. No se encontraron diferencias significativas entre las distribuciones de tamaños de las diferentes zonas, ecorregiones de la zona sur y cruceros analizados. Esta homogeneidad en la estructura de tamaños es destacable ya que las areas analizadas difieren en composición de especies y condiciones medioambientales. Las estructuras de tamaño observadas, fueron descritas

  18. Caracterización preliminar de los invertebrados bentónicos capturados accidentalmente en la pesca de camarones en el norte del estado de Río de Janeiro, sudeste de Brasil Preliminary characterization of benthic invertebrates caught as by-catch in the shrimp fishery in the north of the Rio de Janeiro State, southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Igor David da Costa

    2009-01-01

    Full Text Available Para caracterizar la biodiversidad de invertebrados bentónicos que componen la fauna asociada a la pesca de camarones en el puerto del Farol de Sao Thomé, costa norte del estado de Río de Janeiro, se realizaron 11 pescas mensuales en el año 2004 con redes de arrastre de fondo, cuya área de operaciones comprende 3-5 mn desde la línea de costa, entre 22°00'S y 22°20'S. Los datos registrados de cada taxon y/o especie se refieren a la frecuencia de ocurrencia, frecuencia numérica, biomasa, índice de Importancia Relativa y abundancia. En total se registraron 27 especies de invertebrados bentónicos de Porifera, Cnidaria, Mollusca, Annelida, Crustácea, Echinodermata y Bryozoa. Crustácea fue el más representativo, tanto en número de ejemplares de Petrochirus diogenes, Hepatus pudibundus y Callinectes ornatos, como en biomasa de P. diogenes y H. pudibundas. En términos de frecuencia de ocurrencia en los muéstreos, 11 especies (40,7% fueron constantes; 6 (22,2% accesorias y 10 (37,0% accidentales.In order to characterize the biodiversity of the benthic invertebrate by-catch associated with the shrimp fishery at Farol de Sao Thome harbor, northern Rio de Janeiro State, Brazil, in 2004, 11 monthly trawls were conducted using bottom trawl nets between 22°00'S and 22°20'S and from 3 to 5 nm from the shoreline. The analyzed data for each talon and/or species include frequency of occurrence, numeric frequency, biomass, index of Relative Importance, and abundance. In total, 27 benthic invertebrate species were recorded, including Peripheral, Cnidarians, Mollusk, Annelid, Crustacea, Echinodermata, and Bryozoa. The most representative group was Crustacea, both in number of specimens (Petrochirus diogenes, Hepatus pudibundus, Callinectes ornatus and in biomass (P. diogenes, H. pudibundus. In terms of the frequency of occurrence in the samples, 11 species (40.7% were constant, 6 species (22.2% were accessories, and 10 species (37.0% were by-catch.

  19. Influence of environmental factors on benthic macroinvertebrate communities of urban streams in Vereda habitats, Central Brazil Influência de variáveis ambientais na comunidade de macroinvertebrados bentônicos de córregos urbanos de Veredas, Brasil Central

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    Renata de Moura Guimaraes Souto

    2011-09-01

    integridade do habitat nas comunidades de macroinvertebrados bentônicos têm aumentado nos anos recentes, entretanto, não há estudos avaliando a influência da urbanização nas comunidades de macroinvertebrados em córregos de veredas. Assim, ampliar o conhecimento da relação entre as variáveis abióticas e fauna bentônica é muito importante para a compreensão do funcionamento dos processos ecológicos e da integridade dos ecossistemas aquáticos. Este estudo investigou a influência de variáveis físicas e químicas nas comunidades de macroinvertebrados bentônicos ao longo de um gradiente de distúrbios antrópicos em quatro córregos de Vereda em Uberlândia (MG; um em uma área preservada e três na área urbana MÉTODOS: as amostras foram coletadas nas estações seca e chuvosa RESULTADOS: A análise de componentes principais separou o córrego da área preservada daqueles da área urbana por apresentar menores valores de DBO, DQO, tamanho do sedimento, condutividade, detergentes, pH, sólidos depositáveis e sólidos totais dissolvidos. Grupos sensíveis à poluição (e.g., Ephemeroptera e Trichoptera foram associados ao córrego da área preservada e grupos mais tolerantes (Chironomidae e Oligochaeta tiveram maior abundância nos córregos da área urbana. A Análise de Correspondência Canônica indicou que oxigênio dissolvido, condutividade, DBO, óleos e graxas e turbidez explicaram 56% da variação na distribuição e abundância de macroinvertebrados; CONCLUSÕES: comunidades bentônicas de córregos de Vereda em áreas urbanas no Bioma Cerrado parecem ser altamente afetadas pelas atividades humanas que aumentam a poluição orgânica da água e a sedimentação.

  20. Variabilidade diária da zonação da macrofauna bentônica em praias arenosas do litoral norte do Rio Grande do Sul Daily zonation variation of sandy beach benthic macrofauna in north coast of the Rio Grande do Sul, Brazil

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    Frederico Monteiro Neves

    2009-03-01

    Full Text Available O objetivo deste trabalho é verificar a variação diária da zonação da macrofauna bentônica nas praias de Tramandaí, Harmonia e Jardim do Éden, Rio Grande do Sul. As coletas foram feitas ao longo de cinco dias consecutivos, utilizando-se um tubo de PVC de 20 cm de diâmetro. Foram demarcadas três transversais distantes 50 m uma da outra, com 4 estações de coleta e três amostras cada. As estações se estenderam desde 8 m acima do limite superior da zona de varrido (definida a cada dia até 1 m de profundidade. Também foram coletados diariamente dados dos perfis topográficos de cada praia. Os resultados mostraram que a macrofauna bentônica apresenta um padrão de zonação regular ao longo dos dias. O intermareal foi marcado pela presença do isópode Excirolana armata (Dana, 1853 e do poliqueta Euzonus furciferus (Ehlers, 1897. A zona de varrido apresentou grande abundância do caranguejo hipídeo Emerita brasiliensis (Schmitt, 1935, do bivalvo Donax hanleyanus (Philippi, 1842 e do poliqueto Scolelepis gaucha (Orensanz & Gianuca, 1974. As zonas de "surf" e arrebentação interna não apresentaram diferenças na composição de espécies, sendo dominantes os juvenis de D. hanleyanus, Mesodesma mactroides (Deshayes, 1854, o anfípode Phoxocephalopsis zimmeri (Schellenberg, 1931, o poliqueto Hemipodus olivieri (Orensanz & Gianuca, 1974, além do bivalve Donax gemmula (Morrison, 1971. Os resultados indicaram que, apesar do padrão de zonação da macrofauna ter sido regular ao longo do estudo, algumas mudanças na posição vertical das espécies foram observadas, principalmente em função da variação da zona de varrido.This work verified the daily zonation of benthic macrofauna in Tramandaí, Harmonia and Jardim do Éden beaches, north coast of the state of Rio Grande do Sul, southern Brazil, for five consecutive days. Biological data were collected with a PVC core (20 cm diameter along three transects distant 50 m of each other

  1. Primer informe del género Gambierdiscus (Dinophyceae y otros dinoflagelados bentónicos en el Parque Nacional Isla del Coco, Costa Rica, Pacífico Tropical Oriental First report of the genus Gambierdiscus (Dinophyceae and other benthic dinoflagellates from Isla del Coco National Park, Costa Rica, Eastern Tropical Pacific

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    Maribelle Vargas-Montero

    2012-11-01

    Full Text Available El Pacífico Tropical Oriental se ha indicado como una región de los océanos libre de ciguatera, una intoxicación que causa serios trastornos gastrointestinales, neurológicos y cardiovasculares, en casos extremos, la muerte. Pero con el presente estudio hemos encontrado una incidencia alta de microalgas bénticas involucradas en la producción de ciguatera en el Parque Nacional Isla del Coco (PNIC, Costa Rica. En campañas oceanográficas realizadas entre el 2006 y el 2011 al PNIC se recolectaron 420 muestras de fitoplancton con el interés de encontrar especies de dinoflagelados bentónicos implicados en la producción de ciguatera. Las muestras se tomaron con red de fitoplancton o mediante buceos, entre los 5 y 30 m de profundidad en zonas de arrecife y por extracción directa de macroalgas. Se encontró a los dinoflagelados Gambierdiscus spp., Coolia tropicales, Coolia cf. areolota, Prorocentrum concavum, Prorocentrum compressum, Amphidinium carterae y Ostreopsis siamensis. Se determinó que la cantidad de dinoflagelados por peso de macroalga era elevada, principalmente para el género Gambierdiscus. Los géneros Ostreopsis y Prorocentrum mostraron tener la mayor distribución en los sitios de colecta. Gambierdiscus es un género productor de ciguatera. Se encontraron dos tamaños diferentes de individuos de Gambierdiscus, Comparando los especímenes de Gambierdiscus encontradas con otros estudios, se concluye que son diferentes a las descritas anteriormente, por lo que podría tratarse de especies nuevas, lo que se confirmará con cultivos y análisis moleculares. Al ser la Isla del Coco un sitio oceánico aislado y en estado de conservación, es un sitio ideal para el estudio de la evolución de especies de fitoplancton marino. Además, el monitoreo a largo plazo es muy importante debido a la variedad de dinoflagelados bentónicos potencialmente tóxicos que habitan en este ecosistema marino. Este es el primer estudio donde se da a

  2. Effects of cutting disturbance in Schoenoplectus californicus (C.A. Mey. Soják on the benthic macroinvertebrates = Efeito do distúrbio de corte em Schoenoplectus californicus (C.A. Mey. Soják sobre a fauna de macroinvertebrados bentônicos

    Directory of Open Access Journals (Sweden)

    Thiago Cesar Lima Silveira

    2011-01-01

    Full Text Available Lagoons are considered protected areas because these systems play a key ecological role. However, the extraction of macrophyte Schoenoplectus californicus is held for manufacture of handcrafts, being an alternative income for riverbank communities. This studyevaluated the impact of S. californicus experimental cutting on benthic macroinvertebrates trough a field experiment. Macroinvertebrates were sampled at 1, 12, 26 and 60 days after themacrophyte cutting in demarked plots (1 m², as well at control plots. The families number was not statistically different (ANOVA, p > 0.05, but the total density of invertebrates, and the density of Ceratopogonidae were significant (ANOVA, p No Brasil, as margens de lagoas são consideradas áreas protegidas por desempenharem importante papel ecológico. No entanto, a extração da macrófita Schoenoplectus californicus é realizada para a fabricação de artesanato, sendo alternativa de renda para as comunidades ribeirrinhas. Este estudo teve como objetivo avaliar o impacto do corte de S. californicus sobre os macroinvertebrados bentônicos por meio de um experimento de campo. Os macroinvertebrados foram amostrados um dia, 12, 26 e 60 dias após o corte em macrófitas em parcelas demarcadas (1 m², bem como nas parcelas-controle. As famílias de macroinvertebrados mais abundantes não apresentaram diferenças significativas (ANOVA, p < 0,05, mas a densidade total de invertebrados e a densidade de Ceratopogonidae foram significativas (ANOVA, p < 0,05 para a interação entre a data de amostragem e tratamento. A Análise de Componentes Principais identificou que a profundidade no local do experimento foi a variável que influenciou a variabilidade entre as amostras coletadas no experimento. Concluiu-seque o corte de S. californicus, nessa área, como a intensidade do corte realizado, não afeta drasticamente a composição de macroinvertebrados aquáticos. Os resultados sugerem que o extrativismo em pequenas

  3. Ram pressure statistics for bent tail radio galaxies

    CSIR Research Space (South Africa)

    Mguda, Z

    2015-01-01

    Full Text Available ), Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa 2South African Astronomical Observatory (SAAO), PO Box 9, 7935 Observatory, Cape Town, South Africa 3Department of Physics, University of Witwatersrand...

  4. Tree Planting at the Bent Creek Experimental Forest

    Science.gov (United States)

    John C. Barber

    1953-01-01

    Foresters everywhere are becoming increasingly conscious of the potentialities of tree selection and breeding. In the quest for suitable breeding material, many of the plantations of the past are assuming importance, for each plantation of introduced species may provide information on its adaptability to a certain area and the desirable and undesirable traits which...

  5. On the spectrum of a bent chain graph

    Czech Academy of Sciences Publication Activity Database

    Duclos, P.; Exner, Pavel; Turek, O.

    2008-01-01

    Roč. 41, č. 41 (2008), 415206/1-415206/18 ISSN 1751-8113 R&D Projects: GA MŠk LC06002 Institutional research plan: CEZ:AV0Z10480505 Keywords : quantum * Schrodinger operators * Hamiltonian has Subject RIV: BE - Theoretical Physics Impact factor: 1.540, year: 2008

  6. Bent-Pipe Vs On-Board Processing

    Indian Academy of Sciences (India)

    Multi-beam frequency re-use which increases satellite raw capacity;; Empty uplink time slots to be discarded, increasing the efficiency of downlink transmission;; Dynamic reallocation of unused bandwidth;; Asymmetric Uplink and down link bandwidth to take advantage of traffic statistics;; Statistical multiplexing which ...

  7. Gap asymptotics in a weakly bent leaky quantum wire

    Czech Academy of Sciences Publication Activity Database

    Exner, Pavel; Kondej, S.

    2015-01-01

    Roč. 48, č. 49 (2015), s. 495301 ISSN 1751-8113 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : singular Schroedinger operators * delta interaction * leaky quantum wires * weak perturbation * asymptotic expansion Subject RIV: BE - Theoretical Physics Impact factor: 1.933, year: 2015

  8. Exact equivalent straight waveguide model for bent and twisted waveguides

    DEFF Research Database (Denmark)

    Shyroki, Dzmitry

    2008-01-01

    Exact equivalent straight waveguide representation is given for a waveguide of arbitrary curvature and torsion. No assumptions regarding refractive index contrast, isotropy of materials, or particular morphology in the waveguide cross section are made. This enables rigorous full-vector modeling...... of in-plane curved or helically wound waveguides with use of available simulators for straight waveguides without the restrictions of the known approximate equivalent-index formulas....

  9. Analytic approach to dielectric optical bent slab waveguides

    Czech Academy of Sciences Publication Activity Database

    Hiremath, K. R.; Hammer, M.; Stoffer, R.; Prkna, Ladislav; Čtyroký, Jiří

    2005-01-01

    Roč. 37, 1/3 (2005), s. 37-61 ISSN 0306-8919 R&D Projects: GA ČR(CZ) GA102/05/0987 Grant - others:European Commission(XE) IST-2000-28018 NAIS Institutional research plan: CEZ:AV0Z20670512 Keywords : integrated optics * optical waveguide theory * modelling Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.688, year: 2005

  10. Experimental evidence of planar channeling in a periodically bent crystal

    CERN Document Server

    Bagli, E; Bellucci, V; Berra, E; Camattari, R; De Salvador, D; Germogli, G; Guidi, V; Lanzoni, L; Lietti, D; Mazzolari, A; Prest, M; Tikhomirov, V V; Vallazza, E

    2014-01-01

    The usage of a Crystalline Undulator (CU) has been identified as a promising solution for generating powerful and monochromatic $\\gamma$-rays. A CU was fabricated at SSL through the grooving method, i.e., by the manufacturing of a series of periodical grooves on the major surfaces of a crystal. The CU was extensively characterized both morphologically via optical interferometry at SSL and structurally via X-ray diffraction at ESRF. Then, it was finally tested for channeling with a 400 GeV/c proton beam at CERN. The experimental results were compared to Monte Carlo simulations. Evidence of planar channeling in the CU was firmly observed. Finally, the emission spectrum of the positron beam interacting with the CU was simulated for possible usage in currently existing facilities.

  11. Estimates of dispersive effects in a bent NLC Main Linac

    Energy Technology Data Exchange (ETDEWEB)

    Michael Syphers and Leo Michelotti

    2000-10-31

    An alternative being considered for the Next Linear Collider (NLC) is not to tunnel in a straight line but to bend the Main Linac into an arc so as to follow a gravitational equipotential. The authors begin here an examination of the effects that this would have on vertical dispersion, with its attendant consequences on synchrotron radiation and emittance growth by looking at two scenarios: a gentle continuous bending of the beam to follow an equipotential surface, and an introduction of sharp bends at a few sites in the linac so as to reduce the maximum sagitta produced.

  12. An elastically Bent silicon monochromator for a neutron diffractometer

    Czech Academy of Sciences Publication Activity Database

    Tanaka, I.; Niimura, N.; Mikula, Pavol

    1999-01-01

    Roč. 32, - (1999), s. 525-529 ISSN 0021-8898 R&D Projects: GA ČR GV202/97/K038; GA AV ČR KSK1048601 Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.901, year: 1999

  13. Theoretical reflectivities of bent crystal analyzers for fusion plasma diagnostics

    International Nuclear Information System (INIS)

    Caciuffo, R.; Ferrero, C.; Francescangeli, O.; Melone, S.

    1990-01-01

    The performances of curved crystal analyzers used in the plasma diagnostic spectrometers at several fusion laboratories are evaluated by means of a physical model based on the dynamical theory of x-ray diffraction. We present reflectivity curves and diffraction parameters calculated as a function of the crystal curvature for different wavelengths corresponding to the most relevant spectra of metal impurity ions present in high-energy laboratory plasma sources

  14. Macroalgas bentônicas associadas a bancos de Hypnea musciformis (Wulfen J.V. Lamour. (Rhodophyta - Gigartinales em duas praias do litoral baiano Macroalgae associated with banks of Hypnea musciformis (Wulfen J.V. Lamour. (Rhodophyta, Gigartinales on two beaches on the coast of Bahia

    Directory of Open Access Journals (Sweden)

    Iara Oliveira Costa

    2012-06-01

    Full Text Available Este trabalho caracteriza a estrutura e dinâmica das comunidades de macroalgas bentônicas associadas a populações de H. musciformis ocorrentes em formações recifais nas praias de Stella Maris (Salvador e Itacimirim (Camaçari. As coletas ocorreram entre agosto de 2007 e junho de 2008. As formações recifais foram divididas em compartimentos com base no hidrodinamismo. Utilizou-se três transectos em cada compartimento, onde foram dispostos cinco quadrados de 20 x 20 cm. Foram obtidos dados de riqueza, biomassa, percentual de importância (Pi%, diversidade (H' e equitabilidade (J'. Na área estudada ocorreram 60 espécies: 30 Rhodophyta, 20 Chlorophyta e 10 Ochrophyta; biomassa média de 136 g.m-² (peso seco; e índices médios de H' e J' de 2,7 e 0,97, respectivamente. Houve predominância das rodofíceas, tanto em riqueza específica quanto em valores de biomassa. Foi encontrada maior contribuição do grupo morfo-funcional de algas corticadas. Dentre a flora associada, Gelidiella acerosa, Sargassum cymosum e Palisada perforata apresentaram maiores valores de biomassa. O compartimento recifal mais representativo em riqueza específica e biomassa foi a região frontal do recife. As comunidades das praias estudadas foram consideradas distintas devido à fisionomia das formações recifais.This study characterized the structure and dynamics of macroalgae communities associated with benthic populations of H. musciformis occurring in reef formations on the beaches of Stella Maris (Salvador and Itacimirim (Camaçari, Bahia. The samples were collected between August 2007 and June 2008. The reef formations were divided into compartments based on hydrodynamics. Three transects where made for each compartment, and each of these had five quadrants of 20 x 20cm. Data about the richness, biomass, percentage of importance (Pi%, diversity (H' and evenness (J' was collected. The study recorded 60 species, 30 Rhodophyta, 20 Chlorophyta and 10 Ochrophyta

  15. Effects of flow reduction and spillways on the composition and structure of benthic macroinvertebrate communities in a Brazilian river reach Efeitos da redução de vazão e construção de soleiras vertentes sobre a composição e estrutura de comunidades de macroinvertebrados bentônicos em um trecho de rio brasileiro

    Directory of Open Access Journals (Sweden)

    DM. Maroneze

    2011-08-01

    Full Text Available Dams are a major threat to aquatic biological diversity. By altering the natural flow of rivers, dams modify fluvial habitats, making them unsuitable for the growth and reproduction of many aquatic species. The aim of this study was to evaluate the effects of a reduced flow reach (RFR on benthic macroinvertebrate communities. Benthic macroinvertebrates were collected at six sites downstream of the Amador Aguiar Power Plant I before (lotic phase and after (semi-lentic phase Araguari River mean flow was reduced from 346 to 7 m³.s-1. Changes in macroinvertebrates richness, diversity and total biomass were not observed. Ablabesmyia, Tanytarsus (Chironomidae, Diptera, Leptoceridae and Polycentropodidae (Trichoptera densities significantly increased the first year after flow reduction and the construction of spillways (t-test; p As represas constituem uma das principais ameaças à diversidade biológica. Ao alterarem a vazão natural de um rio, modificam os habitats fluviais tornando-os inadequados para o crescimento e reprodução de diversas espécies aquáticas. O objetivo deste estudo foi avaliar os efeitos de um trecho de vazão reduzida sobre as comunidades de macroinvertebrados bentônicos. Os organismos foram coletados em seis estações amostrais à jusante da UHE Amador Aguiar I antes (fase lótica e após (fase semilêntica a vazão média do rio Araguari (MG ter sido reduzida de 346 para 7 m³.s-1. Não foram registradas mudanças na riqueza, diversidade e biomassa total dos macroinvertebrados. As densidades (ind.m-2 de Ablabesmyia, Tanytarsus (Diptera, Leptoceridae e Polycentropodidae (Trichoptera aumentaram significativamente no primeiro ano após a redução da vazão e construção das soleiras vertentes (t-test; p < 0,05. Uma análise de similaridade (ANOSIM apontou diferenças significativas na composição taxonômica, porém houve sobreposição das comunidades entre as fases lótica e semilêntica (R = 0,3; p < 0,01. Em ambas as

  16. A biodiversidade bentônica em lagoa marginal ao rio Paranapanema na zona de sua desembocadura, na represa de Jurumirim - DOI: 10.4025/actascibiolsci.v28i4.166 The benthic biodiversity in a lake marginal to the Paranapanema river in its mouth zone into Jurumirim reservoir- DOI: 10.4025/actascibiolsci.166

    Directory of Open Access Journals (Sweden)

    Rosemary Cristina Souza Davanso

    2007-11-01

    Full Text Available O presente trabalho teve como objetivo principal verificar a biodiversidade bentônica em áreas do fundo da lagoa do Coqueiral, zona de desembocadura do rio Paranapanema, na represa de Jurumirim, Estado de São Paulo. Foram selecionados dezoito pontos de amostragem, englobando áreas rasas e áreas profundas. As coletas foram feitas em intervalos trimestrais ao longo de um ano; também foram analisadas as variáveis físicas e químicas da água (nível, transparência, temperatura, oxigênio dissolvido, pH e condutividade elétrica. Amostras do sedimento, para análise da fauna e de fatores abióticos (granulometria e conteúdo orgânico, foram recolhidas em tréplicas, utilizando como coletor a draga de Petersen. O material foi triado e analisado sob microscópio estereoscópico. Contagem e identificação dos organismos foram realizadas, e densidade, abundância relativa, riqueza taxonômica e índice de dominância foram calculados. A análise revelou uma fauna com baixa diversidade e a dominância de Chironomidae e Ephemeroptera. Domínio de Ephemeroptera, constituído por Campsurus, ocorreu no período mais quente do ano e com baixa profundidade da lagoa. A distribuição dos organismos teve como principais fatores determinantes profundidade, transparência, pH e temperatura da água. Na comparação feita entre áreas rasas e profundas, foi observada uma menor densidade de organismos nas regiões profundas.Coqueiral lake is a marginal lake located at the southeast São Paulo State, in the mouth zone of the Paranapanema river into Jurumirim Reservoir and it has high connectivity with the Paranapanema river. This work aimed to verify the benthic biodiversity in areas of the lake bottom. 18 sampling sites in the lake were selected, including shallow and deep areas. The samples were taken every three months during one year. Physical and chemical water variables (level, transparency, dissolved oxygen, pH, and electric conductivity were

  17. Composição das espécies de moluscos bentônicos nos reservatórios do baixo rio Tietê (São Paulo, Brasil com uma avaliação do impacto causado pelas espécies exóticas invasoras Species composition of benthic molluscs in the reservoirs of Low Tietê River (São Paulo, Brazil with an evaluation of the impact of exotic invader species

    Directory of Open Access Journals (Sweden)

    Roberta S. França

    2007-03-01

    Full Text Available A composição taxonômica, a densidade e a distribuição espacial de moluscos bentônicos nos reservatórios do baixo rio Tietê (São Paulo foram analisadas. A amostragem dos moluscos foi realizada em novembro de 2002 e agosto de 2003. As características físicas e químicas dos reservatórios também foram avaliadas buscando-se correlacioná-las à composição taxonômica e à distribuição dos táxons através da Análise de Correspondência Canônica (ACC. A espécie exótica Melanoides tuberculata esteve distribuída em todas as porções amostradas e foi a espécie mais abundante, correspondendo a 65,9% ou mais da abundância total, sendo dominante em todos os reservatórios, com densidade máxima de 23753 ind.m-2 registrada na profundidade de 2 m da porção superior do reservatório de Nova Avanhandava. As demais espécies exóticas, Corbicula fluminea e Helisoma sp., foram bem menos abundantes e não foram registradas em todas as porções dos reservatórios. As espécies nativas foram Aylacostoma tenuilabris, Biomphalaria glabrata, B. intermedia, Physa cubensis e Pomacea canaliculata. Essas espécies representaram menos de 20% das espécies presentes nos reservatórios, ocorreram em abundância baixa e em densidades bem inferiores àquelas das espécies exóticas, principalmente em relação a M. tuberculata, podendo indicar o impacto das espécies exóticas invasoras sobre as populações nativas.The taxonomic composition, density and the spatial distribution of benthic molluscs in low Tietê, São Paulo reservoirs were analyzed in November 2002 and August 2003. The exotic species Melanoides tuberculata was distributed in all portions sampled and was the most abundant species, corresponding to 65.9% or more of the total abundance, being dominant in all reservoirs, with a maximum density of 23,753 ind.m-2 recorded in the depth of 2 m, at the superior portion of Nova Avanhandava reservoir.The other exotic species, Corbicula

  18. First observation of luminosity-driven extraction using channeling with a bent crystal

    Directory of Open Access Journals (Sweden)

    R. A. Carrigan, Jr.

    1998-06-01

    Full Text Available Luminosity-driven channeling extraction has been observed for the first time using a 900 GeV circulating proton beam at the superconducting Fermilab Tevatron. The extraction efficiency was found to be about 30%. A 150 kHz beam was obtained during luminosity-driven extraction with a tolerable background rate at the collider experiments. A 900 kHz beam was obtained when the background limits were doubled. This is the highest energy at which channeling has been observed.

  19. Rheology limits for grout materials used for precast bent cap pile pockets in hot weather.

    Science.gov (United States)

    2017-02-28

    While prefabricated bridge elements and systems (PBES) have been used for many years in Florida, The Florida Department : of Transportation (FDOT) is currently developing local specifications for PBES to ad- dress the Federal Highway : Administration...

  20. Photoelastic investigation of the stresses in mitered bent-cylinders under bending, 2

    International Nuclear Information System (INIS)

    Sawa, Yoshiaki

    1983-01-01

    The results of the stress analysis near the joints by freezing photoelastic method are described when two mitered cylinders of same diameter were directly joined, and the joint was subjected to inplane bending. The intersecting angle was changed from 45 deg through 60 and 90 deg to 120 deg, and the change of the stress distribution was examined, and the relation of the axial and circumferential peak stress values to the intersecting angle, wall thickness and corner radius was determined. In the experiment changing the intersecting angle, mostly the wall thickness and corner radius were taken as 1/10 of cylinder outside diameter. The models were made of Araldite B type and by machining and filing. In order to apply pure bending moment, four-point loading method was adopted. The photoelastic pictures, the state of stress distribution and the change of stress concentration factor due to the change of the intersecting angle are reported. The stress concentration factor was relatively high, and in particular, that of axial stress at the corner was remarkably affected by the corner radius. Other points of high peak stress were found. (Kako, I.)

  1. 'Gewoon worden wie je bent': Over authenticiteit en anti-institutionalisme

    NARCIS (Netherlands)

    S.D. Aupers (Stef); D. Houtman (Dick); I. van der Tak

    2003-01-01

    textabstractAnalysis of a dozen semi-structured interviews with Dutch New Age trainers demonstrates that the modern 'ethics of authenticity' underlies contemporary society's anti-institutional mood. All institutions, be they traditional or modern, or so our respondants argue, prevent one from being

  2. History of Cardiac Surgery at the Peter Bent Brigham and Brigham and Women's Hospital, Boston, Massachusetts.

    Science.gov (United States)

    Cohn, Lawrence H

    2015-01-01

    The history of the Brigham dates from 1913, Harvey Cushing was the first chief of surgery and while at Hopkins did research on mitral stenosis, In 1913 he chose Elliot cutler to be a resident and in 1913 Cutler did the first successful valve operation in the world setting the tone of innovation and dedication to cardiac disease surgical treatment over the next century. There was large numbers of closed mitrals operations in 40s-60s. Bioprothetic valve implantation in the 70s mitral valve repair beginning in the 80s and continuing to the present and one of the first proponents of minimally invasive valve surgery starting in the 90s continuing to the present . Copyright © 2015. Published by Elsevier Inc.

  3. Optimization of bent perfect Si(220)-crystal monochromator for residual strain/stress instrument - Part II

    Czech Academy of Sciences Publication Activity Database

    Moon, MK; Mikula, Pavol; Hong, K.P.

    2005-01-01

    Roč. 368, - (2005), s. 70-75 ISSN 0921-4526 R&D Projects: GA ČR GA202/03/0891 Institutional research plan: CEZ:AV0Z10480505 Keywords : neutron diffraction * focusing * neutron diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.796, year: 2005

  4. Optimization of bent perfect Si(220)-crystal monochromator for residual strain/stress instrument - Part II

    Czech Academy of Sciences Publication Activity Database

    Moon, MK.; Em, Vt.; Lee, C.H.; Mikula, Pavol; Hong, KP; Choi, YH; Cheon, JK; Nam, UW; Kong, KN; Jin, KC

    2005-01-01

    Roč. 368, 1 2 3 4 (2005), s. 70-75 ISSN 0921-4526 R&D Projects: GA ČR(CZ) GA202/03/0891 Institutional research plan: CEZ:AV0Z10480505 Keywords : neutron monochromator * residual stress measurement * neutron diffractometers Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.796, year: 2005

  5. Algas marinas bentónicas de la Isla Gorgona, costa pacífica colombiana

    Directory of Open Access Journals (Sweden)

    Mónica Murillo Muñoz

    2014-02-01

    Full Text Available Se presenta el listado de las algas marinas bénticas del Parque Nacional Natural Isla Gorgona, el inventario corresponde a la flora algal asociada a los diferentes ambientes marinos de la isla, a saber: arrecifes coralinos y fondos blandos. El monitoreo de las comunidades de algas se llevó a cabo entre octubre de 2010 y mayo de 2011, se realizó una estimación de abundancia y cobertura para lo cual se establecieron transeptos paralelos a la línea de costa y se evaluó el porcentaje de cobertura en cuadrantes de 0.25m². Se reportó un total de 43 especies para los dos ambientes estudiados (coralino y fondos blandos, 24 Rhodophyta, 12 Clorophyta, 6 Ochrophyta y una Cyanobacteria. El grupo más representativo fue el perteneciente a la clase Rhodophyceae, que correspondió al 55.8% de la flora inventariada. Los resultados de nuevos registros en la isla ratifican su importancia fitogeográfica, por cuanto la composición florística insular contribuye significativamente a la biodiversidad de la costa pacífica colombiana, destacándose la presencia de arrecifes coralinos como los principales ambientes marinos para el desarrollo de la flora algal de la región.

  6. The elusive thermotropic biaxial nematic phase in rigid bent-core ...

    Indian Academy of Sciences (India)

    the second optic axis lies along the secondary director m in the plane perpendicular to n. To this day, only the existence of ... diffractometer which uses the area detector X-1000 system. An in situ magnetic field of. ~2.5 kG was used ... A square wave voltage with variable amplitude was applied to create varying electric field ...

  7. Cross-flow shearing effects on the trajectory of highly buoyant bent-over plumes

    Science.gov (United States)

    Tohidi, Ali; Kaye, Nigel Berkeley; Gollner, Michael J.

    2017-11-01

    The dynamics of highly buoyant plumes in cross-flow is ubiquitous throughout both industrial and environmental phenomena. The rise of smoke from a chimney, wastewater discharge into river currents, and dispersion of wildfire plumes are only a few instances. There have been many previous studies investigating the behavior of jets and highly buoyant plumes in cross-flow. So far, however, very little attention has been paid to the role of shearing effects in the boundary layer on the plume trajectory, particularly on the rise height. Numerical simulations and dimensional analysis are conducted to characterize the near- and far-field behavior of a highly buoyant plume in a boundary layer cross-flow. The results show that shear in the cross-flow leads to large differences in the rise height of the plume in relation to a uniform cross-flow, especially at far-field. This material is based upon work supported by the National Science Foundation under Grant No.1200560. Any opinions, findings, and conclusions or recommendations expressed in the material are of the authors and do not necessarily reflect the views of NSF.

  8. Closure Welding Design and Justification for Canister S00645 (Bent Flange)

    International Nuclear Information System (INIS)

    Cannell, G.R.

    1998-01-01

    This report provides the design basis and justification for a closure welding technique using the manual Gas Tungsten Are Welding (GTAW) process. Other aspects affecting closure of Canister S00645, e.g., shielding, facility and administrative requirements, etc., are addressed elsewhere

  9. "Forlagbranchen satser på de unges sprog" interview med Bent Fausing af Naj Helen Hertzum

    DEFF Research Database (Denmark)

    Fausing, Bent

    2009-01-01

    Om afsmitningen af sms sprog på det almindelige sprog, samt afsmitningen af billedbeskeder og digitale fotostreams på Social Network Sites (Twitter, Facebook, Fælickr etc.) på æstetikken og kunsten i det hele taget.......Om afsmitningen af sms sprog på det almindelige sprog, samt afsmitningen af billedbeskeder og digitale fotostreams på Social Network Sites (Twitter, Facebook, Fælickr etc.) på æstetikken og kunsten i det hele taget....

  10. Recent evolution and degradation of the bent Jatunraju glacier (Cordillera Blanca, Peru)

    Czech Academy of Sciences Publication Activity Database

    Emmer, A.; Loarte, E.C.; Klimeš, Jan; Vilímek, V.

    2015-01-01

    Roč. 228, JAN 1 (2015), s. 345-355 ISSN 0169-555X R&D Projects: GA ČR(CZ) GAP209/11/1000 Institutional support: RVO:67985891 Keywords : debris-covered glacier * rock glacier * surface movements * buried ice degradation * supraglacial lakes Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 2.813, year: 2015

  11. Characteristics of natural circulation flow in a bent loop with a U-shape-type cooler

    International Nuclear Information System (INIS)

    Ishida; Ishizuka, M.; Futamura, Y.; Akagawa, K.; Fujii, T.; Hashimoto, K.; Kutuna, H.

    1985-01-01

    An experiment on transient single phase natural circulation in a closed loop was conducted to study the core cooling behavior by natural circulation in the loop-type PWR for marine application. The system employed a loop that had two U-shaped, and three inverse U-shaped flow paths, and a small elevation difference between the heater and cooler. The experiment was conducted at atmospheric pressure with the heater input held constant (Q = 0.5 kW to 3.5 kW), and the cooling water flow rate of the cooler constant during the transient following tripping of the pump. From the experiment, a flow stability map was obtained which correlated heater input versus elevation differences. Comparison between experimental and numerical results obtained by RETRAN-02 analyses yielded general agreement

  12. As the twig is bent: the biology and socialization of gender roles in women.

    Science.gov (United States)

    Casey, M B; Brabeck, M M; Nuttall, R L

    1995-03-01

    The present study supports the view that biological predisposition interacts with perceived parental influences to affect cross-gender role identity. Geschwind and colleagues have identified two patterns of brain organization (anomalous and standard dominance) assessed through individual and familial handedness. Anomalous dominant women who perceived their parents as definitely giving them permission for cross-gender behavior demonstrated high masculine/low feminine characteristics on the Bem Sex Role Inventory. The cross-gender role identity in this group differed significantly from the traditional gender role identity found in all other groups of females (including anomalous dominant women whose parents were perceived as less permissive and the women with standard dominance reporting both styles of parenting.

  13. Controlled growth and electrical characterization of bent single-walled carbon nanotubes

    Science.gov (United States)

    Huang, Jun; Choi, Won Bong

    2008-12-01

    The frequency of appearance and curvature of zigzag shaped single-walled carbon nanotubes (SWNTs) are tailored by adjusting the gas flow rate, and changing the gas flow direction with respect to the step-edges on a single-crystal quartz substrate. The electrical resistance of SWNTs is found to increase with the number of bends. The resistance in SWNT segments with sharp curvature is observed to be 10-880 kΩ µm-1 higher than that in segments with smooth curvature. The increment in resistance may be attributed to the introduction of topological defects and heterojunctions at the curved part. Our results suggest the possibility of growing SWNTs with multiple-bend geometry in a simple one-step process and modulating the conductance of SWNTs by controlling the number of bends and the curvature of bends.

  14. Macroinvertebrados bentónicos del humedal de Palo Verde, Costa Rica

    Directory of Open Access Journals (Sweden)

    F.A Trama

    2009-11-01

    Full Text Available El humedal de Palo Verde es uno de los más importantes de Centro America para aves acuáticas. Durante el período 2002 y 2005, se llevaron a cabo actividades de manejo para controlar la invasión de Typha domingensis. Con el fin de establecer una línea base para monitoreos futuros, en el 2003 se realizó una evaluación de macroinvertebrados acuáticos. Se efectuó un muestreo mensual durante un año, usando el método de sustratos artificiales. Se identificaron 116 táxones pertenecientes a 47 familias y a 18 órdenes. La mayor abundancia se encontró en la clase Conchostraca y la familia Chironomidae que juntas representaron casi la mitad de todos los individuos colectados. En contraste, el 97% de los táxones tuvieron, cada uno, menos del 1% del total de la abundancia. La diversidad de táxones, así como la abundancia de individuos y el número de especies, fueron mayores en la época seca que en la lluviosa. La curva acumulada de especies indicó que se hubiera registrado una mayor cantidad de táxones si los muestreos se hubieran extendido por más tiempo. Con este trabajo damos a conocer la primera lista de macroinvertebrados para el humedal de Palo Verde.

  15. Macroinvertebrados bentónicos del humedal de Palo Verde, Costa Rica

    Directory of Open Access Journals (Sweden)

    F.A Trama

    2009-11-01

    Full Text Available El humedal de Palo Verde es uno de los más importantes de Centro America para aves acuáticas. Durante el período 2002 y 2005, se llevaron a cabo actividades de manejo para controlar la invasión de Typha domingensis. Con el fin de establecer una línea base para monitoreos futuros, en el 2003 se realizó una evaluación de macroinvertebrados acuáticos. Se efectuó un muestreo mensual durante un año, usando el método de sustratos artificiales. Se identificaron 116 táxones pertenecientes a 47 familias y a 18 órdenes. La mayor abundancia se encontró en la clase Conchostraca y la familia Chironomidae que juntas representaron casi la mitad de todos los individuos colectados. En contraste, el 97% de los táxones tuvieron, cada uno, menos del 1% del total de la abundancia. La diversidad de táxones, así como la abundancia de individuos y el número de especies, fueron mayores en la época seca que en la lluviosa. La curva acumulada de especies indicó que se hubiera registrado una mayor cantidad de táxones si los muestreos se hubieran extendido por más tiempo. Con este trabajo damos a conocer la primera lista de macroinvertebrados para el humedal de Palo Verde.Benthic macroinvertebrates of the Palo Verde wetland, Costa Rica. Palo Verde, Costa Rica, is one of the most important wetlands in the region now recovering from some invasive plants, especially Typha domingensis, and monitoring programs were started, including studies on the aquatic macoinvertebrate fauna. We sampled benthic macroinvertebrates monthly for more than a year with artificial substrates, and identified 116 taxa from 57 families and 18 orders, with 90 morfospecies of insects. The highest abundances were in the class Conchostraca (typical in seasonal wetlands and in the family Chironomidae (Diptera, Insecta, which together represent almost half of all individuals collected. In contrast, 97 taxa were less than 1% of total abundance each. Number of individuals and number of species were higher at lower water levels (dry season. Cumulative species curves indicate that more species would be found if sampling had continued for more time. Rev. Biol. Trop. 57 (Suppl. 1: 275-284. Epub 2009 November 30.

  16. Design of an elliptically bent refocus mirror for the MERLIN beamline at the advanced light source

    International Nuclear Information System (INIS)

    Kelez, Nicholas; Chuang, Yi-De; Smith-Baumann, Alexis; Franck, Keith; Duarte, R.; Lanzara, A.; Hasan, M.Z.; Dessau, D.S.; Chiang, T.C.; Shen, Z.-X.; Hussain, Zahid

    2007-01-01

    There is an increasing demand for well-focused beam with high quality imaging of the full field to further explore the potential of novel instruments. For beamlines operating at focal point, mechanical benders have often been used to shape the refocusing mirror into an ideal elliptical cylinder. Unfortunately, the limited number of couplings for these mechanisms requires specific substrate side-shaping, often calculated using beam bending theory [J.H. Underwood, Space Sci. Instrum. 3 (1977) 259; M. Howells et al., Opt. Eng. 39 (2000) 2748; T. Warwick et al., Document available at OSTI website: http://www.osti.gov/energycitations/servlets/purl/842557-JYZCS3/native/], to meet demanding figure requirements. Here, we use finite element analysis (FEA) to validate the side-shaping algorithm and then couple the output with SHADOW to evaluate mirror performance when an ideal ellipse is not achieved

  17. A liquid crystalline co-polysiloxane with asymmetric bent-shaped side chains

    Czech Academy of Sciences Publication Activity Database

    Bubnov, Alexej; Novotná, Vladimíra; Pociecha, D.; Kašpar, Miroslav; Hamplová, Věra; Galli, G.; Glogarová, Milada

    2011-01-01

    Roč. 212, č. 2 (2011), s. 191-197 ISSN 1022-1352 R&D Projects: GA AV ČR IAA100100911; GA AV ČR(CZ) GA202/09/0047; GA MŠk(CZ) OC10006; GA MŠk MEB050818 Grant - others:Federal Agency for Science and Innovation, Russian Federation(RU) RFASI No 02.740.11.5166 Institutional research plan: CEZ:AV0Z10100520 Keywords : calorimetry * liquid-crystalline polymers ( LCP ) * phase behaviou * polysiloxanes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.361, year: 2011 http://onlinelibrary.wiley.com/doi/10.1002/macp.201000356/pdf

  18. Optimized polychromatic x-ray imaging with asymmetrically cut bent crystals

    Czech Academy of Sciences Publication Activity Database

    Podorov, S. G.; Renner, Oldřich; Wehrhan, O.; Förster, E.

    2001-01-01

    Roč. 34, - (2001), s. 2363-2368 ISSN 0022-3727 Grant - others:-(DE) B508-99027; CZ-DE Bilateral Corporation in Science(XC) CZE-00-008 Institutional research plan: CEZ:AV0Z1010921 Keywords : x-ray imaging * x-ray diffraction * ray-tracing simulations Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.260, year: 2001

  19. Correction for the twist and the conical defects of a sagittaly bent crystal

    CERN Document Server

    Ferrer, J L

    1999-01-01

    The symmetrical bending of the focusing crystal of a double X-ray monochromator is a difficult problem. Indeed, the slope due to the curvature is usually three orders of magnitude higher than the accepted slope error (typically, the Darwin width of the crystal). In these conditions, even a low parasitic slope error induced by the bending process may lead to quite a strong intensity decrease. When the bending moment is applied, the main parasitic distortions which may appear are typically the anticlastic curvature, the inhomogeneous sagittal curvature, the conical shape and the twist. On the D2AM beamline at the ESRF, a program called CHKC2 has been developed to correct on-line the latter two distortions: the conical shape and the twist. On this beamline the X-ray beam, which has been collimated by a grazing angle mirror, is monochromatized first by a flat silicon crystal, and then diffracted by the sagittaly curved crystal. A fluorescent screen gives an image of this diffracted beam. The CHKC2 program records...

  20. Dynamic stability of a curved pipe bent in the arc of a circle on hinge ...

    Indian Academy of Sciences (India)

    Sofia e-mail: dlolov@yahoo.com; lilkova−fhe@uacg.bg. MS received 12 September 2005; revised 29 April 2006. Abstract. Curved pipes conveying fluids are investigated in the paper. Methods of numerical solution of the dynamic stability of a pipe in its plane are developed. An example of a curved pipe is solved by these ...

  1. Measurement of Short Living Baryon Magnetic Moment using Bent Crystals at SPS and LHC

    CERN Document Server

    Burmistrov, L; Ivanov, Yu; Massacrier, L; Robbe, P; Scandale, W; Stocchi, A

    2016-01-01

    The magnetic moments of baryons containing u,d and s quarks have been extensively studied and measured. The experimental results are all obtained by a well-assessed method that consists in measuring the polarisation vector of the incoming particles and the precession angle when the particle is travelling through an intense magnetic field. The polarization is evaluated by analysing the angular distribution of the decay products. No measurement of magnetic moments of charm or beauty baryons (and τ leptons) has been performed so far. The main reason is the lifetimes of charm/beauty baryons, too short to measure the magnetic moment by standard techniques. Historically, the prediction of baryon magnetic moments was one of the striking successes of the quark model. The importance of the measurement of heavy quark magnetic moment is to test the possibility that the charmed and/or beauty quarks has an anomalous magnetic moment, arising if those quarks are composite objects. Measurements on magnetic moments of heav...

  2. Bubble generation in a twisted and bent DNA-like model

    DEFF Research Database (Denmark)

    Larsen, Peter Ulrik Vingaard; Christiansen, Peter Leth; Bang, Ole

    2004-01-01

    The DNA molecule is modeled by a parabola embedded chain with long-range interactions between twisted base pair dipoles. A mechanism for bubble generation is presented and investigated in two different configurations. Using random normally distributed initial conditions to simulate thermal...

  3. Microwave Tomographic Imaging Utilizing Low-Profile, Rotating, Right Angle-Bent Monopole Antennas

    Directory of Open Access Journals (Sweden)

    N. R. Epstein

    2014-01-01

    Full Text Available We have developed a simple mechanism incorporating feedline bends and rotary joints to enable motion of a monopole antenna within a liquid-based illumination chamber for tomographic imaging. The monopole is particularly well suited for this scenario because of its small size and simplicity. For the application presented here a full set of measurement data is collected from most illumination and receive directions utilizing only a pair of antennas configured with the rotating fixture underneath the imaging tank. Alternatively, the concept can be adapted for feed structures entering the tank from the sides to allow for measurements with vertically and horizontally polarized antennas. This opens the door for more advanced imaging applications where anisotropy could play an important role such as in bone imaging.

  4. Een instrument (leren) bespelen? : Hoe oud je ook bent: oefenen moet je toch!

    NARCIS (Netherlands)

    Linda Hendriks

    2016-01-01

    Met een consortium van muziekdocenten die zich gespecialiseerd hebben in ouderen en muziek voerde het lectoraat Lifelong Learning in Music van 2010-2012 onderzoek uit naar het leren bespelen van een instrument op oudere leeftijd. Maar hoe is het om voor het eerst een instrument te leren bespelen in

  5. Een instrument (leren) bespelen?: Hoe oud je ook bent: oefenen moet je toch!

    OpenAIRE

    Hendriks, Linda

    2016-01-01

    Met een consortium van muziekdocenten die zich gespecialiseerd hebben in ouderen en muziek voerde het lectoraat Lifelong Learning in Music van 2010-2012 onderzoek uit naar het leren bespelen van een instrument op oudere leeftijd. Maar hoe is het om voor het eerst een instrument te leren bespelen in de drukste levensfase in combinatie met kinderen en werk. Linda Hendriks leerde klarinet te spelen in deze levensfase en reflecteerde op de uitkomsten van eerder onderzoek naar muziekbeoefening doo...

  6. Bent Shaped 1,3,4-Oxadiazole/Thiadiazole heterocyclic rings ...

    Indian Academy of Sciences (India)

    Solvents such as dry toluene, tetrahydrofu- ran, ethanol and dichloromethane were purified by the reported procedure.26 Elemental analysis of the com- pounds was determined by Heraeus CHN analyzer. The. FT-IR spectra of the compounds were obtained from. Perkin Elmer FT-IR spectrometer using KBr pellets. 1H.

  7. "A tree must be bent while it is young": teaching urological surgical techniques to schoolchildren.

    Science.gov (United States)

    Buntrock, Stefan

    2012-01-01

    Playing video games in childhood may help achieve advanced laparoscopic skills later in life. The virtual operating room will soon become a reality, as "doctor games 2.0" will doubtlessly begin to incorporate virtual laparoscopic techniques. To teach surgical skills to schoolchildren in order to attract them to urology as a professional choice later in life. As part of EAU Urology Week 2010, 108 school children aged 15-19 attended a seminar with lectures and simulators (laparoscopy, TUR, cystoscopy, and suture sets) at the 62nd Congress of the German Society of Urology in Düsseldorf. A Pub-Med and Google Scholar search was also performed in order to review the beneficial effects of early virtual surgical training. MeSh terms used were "video games," "children," and "surgical skills." Searches were performed without restriction for a certain period of time. In terms of publicity for urology, EAU Urology Week, and the German Society of Urology, the event was immensely successful. Regarding the literature search, four relevant publications were found involving children. An additional three articles evaluated the usefulness of video gaming in medical students and residents. Making use of virtual reality to attract and educate a new generation of urologists is an important step in designing the future of urology.

  8. Bent Bone Dysplasia-FGFR2 type, a Distinct Skeletal Disorder, Has Deficient Canonical FGF Signaling

    Czech Academy of Sciences Publication Activity Database

    Merrill, A.E.; Sarukhanov, A.; Krejčí, Pavel; Idoni, B.; Carmacho, N.; Estrada, K.D.; Lyons, K.M.; Deixler, H.; Robinson, H.; Chitayat, D.; Curry, C.J.; Lachman, R.S.; Wilcox, W.R.; Krakow, D.

    2012-01-01

    Roč. 90, č. 3 (2012), s. 550-557 ISSN 0002-9297 Grant - others:-(US) HD22657; -(US) 5 P30 DE020750-02 Institutional research plan: CEZ:AV0Z50040702 Institutional support: RVO:68081707 Keywords : APERT- SYNDROME * LADD SYNDROME * GROWTH Subject RIV: BO - Biophysics Impact factor: 11.202, year: 2012

  9. Phylogeny of bent-toed geckos (Cyrtodactylus) reveals a west to east pattern of diversification.

    Science.gov (United States)

    Wood, Perry L; Heinicke, Matthew P; Jackman, Todd R; Bauer, Aaron M

    2012-12-01

    The Asian/Pacific genus Cyrtodactylus is the most diverse and among the most widely distributed genera of geckos, and more species are continually being discovered. Major patterns in the evolutionary history of Cyrtodactylus have remained largely unknown because no published study has broadly sampled across the geographic range and morphological diversity of the genus. We assembled a data set including sequences from one mitochondrial and three nuclear loci for 68 Cyrtodactylus and 20 other gekkotan species to infer phylogenetic relationships within the genus and identify major biogeographic patterns. Our results indicate that Cyrtodactylus is monophyletic, but only if the Indian/Sri Lankan species sometimes recognized as Geckoella are included. Basal divergences divide Cyrtodactylus into three well-supported groups: the single species C. tibetanus, a clade of Myanmar/southern Himalayan species, and a large clade including all other Cyrtodactylus plus Geckoella. Within the largest major clade are several well-supported subclades, with separate subclades being most diverse in Thailand, Eastern Indochina, the Sunda region, the Papuan region, and the Philippines, respectively. The phylogenetic results, along with molecular clock and ancestral area analyses, show Cyrtodactylus to have originated in the circum-Himalayan region just after the Cretaceous/Paleogene boundary, with a generally west to east pattern of colonization and diversification progressing through the Cenozoic. Wallacean species are derived from within a Sundaland radiation, the Philippines were colonized from Borneo, and Australia was colonized twice, once via New Guinea and once via the Lesser Sundas. Overall, these results are consistent with past suggestions of a Palearctic origin for Cyrtodactylus, and highlight the key role of geography in diversification of the genus. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. Connecting Minds: Emergence of a Future Bent, Writing/Thinking Intensive Psychology Course. Occasional Paper #10

    Science.gov (United States)

    Fluellen, J. E., Jr.

    2011-01-01

    How might students engage mindful learning? How might the professor engage mindful teaching? Both questions derived from fieldnotes a participant observer had created for the Future of Learning 2010 Summer Institute (Harvard Graduate School of Education) and the Tests and Measurements course, fall 2010 at Edward Waters College (EWC). Additionally,…

  11. Marine Natural Products from Seaweeds [Produtos Naturais de Algas Marinhas Bentônicas

    OpenAIRE

    Valéria L. Teixeira

    2013-01-01

    Natural products from seaweeds have been studied with the aim of finding new drugs of industrial value, understanding their ecological role, and well as establishing the limits of taxonomic species, genera and families of marine algae. The present review shows the main features of natural products from seaweeds of the Divisions Chlorophyta – Class Ulvophyceae (green seaweeds), Ochrophyta – Class Phaeophyceae (Brown seaweeds) and Rhodophyta (red seaweeds). The most important examples of natura...

  12. Preparation of a bent crystal and its use in neutron scattering

    International Nuclear Information System (INIS)

    Kraxenberger, H.

    1980-01-01

    The aim of this thesis was the construction of a horizontally bendable neutron monochromator e.g. analyzator, the application to different measuring problem in neutron scattering, and the development of an exact theory. (HSI) [de

  13. Bent Shaped 1,3,4-Oxadiazole/Thiadiazole heterocyclic rings ...

    Indian Academy of Sciences (India)

    NMR and ESI-Mass spectro- scopic techniques. Liquid crystal properties ... revealed that replacement of sulphur by oxygen atom causes complete loss of liquid ... reported procedure.26 Elemental analysis of the com- pounds was determined by ...

  14. Volume reflection and channeling of ultrarelativistic protons in germanium bent single crystals

    Directory of Open Access Journals (Sweden)

    S. Bellucci

    2016-12-01

    Full Text Available The paper is devoted to the investigation of volume reflection and channeling processes of ultrarelativistic positive charged particles moving in germanium single crystals. We demonstrate that the choice of atomic potential on the basis of the Hartree-Fock method and the correct choice of the Debye temperature allow us to describe the above mentioned processes in a good agreement with the recent experiments. Moreover, the universal form of equations for volume reflection presented in the paper gives a true description of the process at a wide range of particle energies. Standing on this study we make predictions for the mean angle reflection (as a function of the bending radius of positive and negative particles for germanium (110 and (111 crystallographic planes.

  15. Laterally substituted naphthalene-2,7-diol-based bent-shaped liquid crystals

    Czech Academy of Sciences Publication Activity Database

    Kozmík, V.; Kuchař, M.; Svoboda, J.; Novotná, Vladimíra; Glogarová, Milada; Baumeister, U.; Diele, S.; Pelzl, G.

    2005-01-01

    Roč. 32, č. 9 (2005), s. 1151-1160 ISSN 0267-8292 R&D Projects: GA ČR(CZ) GA202/02/0840; GA ČR(CZ) GA202/05/0431; GA MŠk(CZ) 1P04OCD14.60 Grant - others:EU(XE) COST D14 WG 00015 Institutional research plan: CEZ:AV0Z1010914 Keywords : naphthalene - based liquid crystals * x-ray Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.432, year: 2005

  16. A malacofauna bentônica das represas do médio rio Tietê (São Paulo, Brasil e uma avaliação ecológica das espécies exóticas invasoras, Melanoides tuberculata (Müller e Corbicula fluminea (Müller Benthic malacofauna of the reservoirs of the Middle River Tietê (São Paulo, Brazil and an ecological evaluation of the invading exotic species, Melanoides tuberculata (Müller and Corbicula fluminea (Müller

    Directory of Open Access Journals (Sweden)

    Ana L. Suriani

    2007-03-01

    Full Text Available Este trabalho analisa a composição de espécies, a densidade e a distribuição espacial e temporal da malacofauna bentônica em três represas do médio rio Tietê. As coletas foram realizadas em dois períodos climáticos, o chuvoso em novembro de 2002 e o seco em agosto de 2003, amostrando-se três porções em cada represa (superior, mediana e barragem e seguindo uma varredura com seis pontos amostrais em cada transecto. Os dados limnológicos obtidos evidenciaram que as represas do médio rio Tietê encontram-se eutrofizadas com elevadas concentrações de nutrientes (totais e dissolvidos. Foram registradas oito espécies de moluscos sendo seis nativas e duas exóticas. Destas, a espécie dominante foi o molusco exótico e invasor Melanoides tuberculata (Müller, 1774, presente em todas as represas. A outra espécie exótica Corbicula fluminea (Müller, 1774, também esteve presente em todas as represas e em ambos os períodos de coleta (exceto na represa de Barra Bonita. Na represa de Barra Bonita só ocorreram as duas espécies exóticas, enquanto nas represas de Bariri e Ibitinga as espécies nativas Aylacostoma tenuilabris (Bernardi, 1856, Biomphalaria glabrata (Say, 1818, Biomphalaria intermedia (Paraense & Deslandes, 1962, Diplodon expansus (Küster, 1853, Physa cubensis (Pfeiffer, 1839 e Pomacea canaliculata (Lamarck, 1822 ocorreram em pelo menos um dos períodos amostrados. A ocupação generalizada de M. tuberculata e C. fluminea e as elevadas densidades destas espécies nas represas estudadas revelam o alto potencial invasor das mesmas e a provável competição com as espécies nativas.This study analyze the composition of species, the density and the spatial and temporal distribution of benthic malacofauna in three reservoirs of the Middle Tietê River. The samplings were carried out in two climatic periods, the rainy season in November 2002 and the dry season in August 2003, showing three portions in each reservoir (upper

  17. Rheology limits for grout materials used for precast bent cap pile pockets in hot weather : project summary.

    Science.gov (United States)

    2017-03-01

    The use of prefabricated bridge elements and systems (PBES) saves time and money, both for transportation agencies and the traveling public. PBES is an emphasis area in the Federal Highway Administrations Every Day Counts program in which FHWA and...

  18. Neutron monochromator based on dispersive double-reflections excited in a cylindrically bent-perfect-crystal (BPC) slab

    Czech Academy of Sciences Publication Activity Database

    Mikula, Pavol; Vrána, Miroslav; Lott, D.; Wagner, V.

    385/386, 2 (2006), s. 1274-1276 ISSN 0921-4526. [International Conference on Neutron Scattering /8./. Sydney, 27.11.2005-2.12.2005] R&D Projects: GA MŠk OC P7.003; GA ČR GA202/06/0601 Institutional research plan: CEZ:AV0Z10480505 Keywords : neutron diffraction * double reflections Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.872, year: 2006

  19. Als-je-voor-een-dubbeltje-geboren-bent ... Representation of the lower classes in fin de siecle Dutch literature

    NARCIS (Netherlands)

    Kemperink, M

    2000-01-01

    This essay discusses the representation of the lower classes in fin the siecle Dutch literature. Especially the two following questions are focused: (1) The scientific theories (on heredity, degeneration and the masses) and (2) the ideologies(in the wide sense of visions) that inspired this

  20. Progress towards sub-micron hard x-ray imaging using elliptically bent mirrors and its applications

    International Nuclear Information System (INIS)

    MacDowell, A.A.; Lamble, G.M.; Celestre, R.S.; Padmore, H.A.; Chang, C.H.; Patel, J.R.

    1998-06-01

    The authors have developed an x-ray micro-probe facility utilizing mirror bending techniques that allow white light x-rays (4--12keV) from the Advanced light Source Synchrotron to be focused down to spot sizes of micron spatial dimensions. They have installed a 4 crystal monochromator prior to the micro-focusing mirrors. The monochromator is designed such that it can move out of the way of the input beam, and allows the same micron sized sample to be illuminated with either white or monochromatic radiation. Illumination of the sample with white light allows for elemental mapping and Laue x-ray diffraction, while illumination of the sample with monochromatic light allows for elemental mapping (with reduced background), micro-X-ray absorption spectroscopy and micro-diffraction. The performance of the system will be described as will some of the initial experiments that cover the various disciplines of Earth, Material and Life Sciences

  1. Optimization of Bent Perfect Si(311)-Crystal Monochromator for Residual Strain/Stress Instrument at HANARO Reactor - Part I

    Czech Academy of Sciences Publication Activity Database

    Moon, M. K.; Mikula, Pavol

    2005-01-01

    Roč. 369, 1-4 (2005), s. 1-7 ISSN 0921-4526 Institutional research plan: CEZ:AV0Z10480505 Keywords : neutron diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.796, year: 2005

  2. All-organic liquid crystalline radicals with a spin unit in the outer position of a bent-core system

    Czech Academy of Sciences Publication Activity Database

    Bajzíková, A.; Kohout, M.; Tarábek, Ján; Svoboda, J.; Novotná, Vladimíra; Vejpravová, Jana; Pociecha, D.; Gorecka, E.

    2016-01-01

    Roč. 4, č. 48 (2016), s. 11540-11547 ISSN 2050-7526 R&D Projects: GA ČR GA15-02843S Institutional support: RVO:61388963 ; RVO:68378271 Keywords : mesogenic cores * ester groups * rigid core Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.256, year: 2016

  3. Progress towards sub-micron hard x-ray imaging using elliptically bent mirrors and its applications

    Energy Technology Data Exchange (ETDEWEB)

    MacDowell, A.A.; Lamble, G.M.; Celestre, R.S.; Padmore, H.A. [Lawrence Berkeley National Lab., CA (United States); Chang, C.H.; Patel, J.R. [Lawrence Berkeley National Lab., CA (United States). Advanced Light Source Div.]|[Stanford Univ., CA (United States)

    1998-06-01

    The authors have developed an x-ray micro-probe facility utilizing mirror bending techniques that allow white light x-rays (4--12keV) from the Advanced light Source Synchrotron to be focused down to spot sizes of micron spatial dimensions. They have installed a 4 crystal monochromator prior to the micro-focusing mirrors. The monochromator is designed such that it can move out of the way of the input beam, and allows the same micron sized sample to be illuminated with either white or monochromatic radiation. Illumination of the sample with white light allows for elemental mapping and Laue x-ray diffraction, while illumination of the sample with monochromatic light allows for elemental mapping (with reduced background), micro-X-ray absorption spectroscopy and micro-diffraction. The performance of the system will be described as will some of the initial experiments that cover the various disciplines of Earth, Material and Life Sciences.

  4. Synthesis, phase behaviour and photooptical properties of bent-core methacrylate with azobenzene group and corresponding side-chain polymethacrylate

    Czech Academy of Sciences Publication Activity Database

    Novotná, Vladimíra; Bobrovsky, A.; Shibaev, V.; Pociecha, D.; Kašpar, Miroslav; Hamplová, Věra

    2016-01-01

    Roč. 6, č. 70 (2016), 65747-65755 ISSN 2046-2069 R&D Projects: GA ČR GA16-12150S; GA MŠk(CZ) LH15305 Institutional support: RVO:68378271 Keywords : liquid crystals * liquid crystalline polymers * photosensitivity Subject RIV: JJ - Other Materials Impact factor: 3.108, year: 2016

  5. Experimental studies of dispersive double reflections excited in cylindrically bent perfect-crystal slabs at a constant neutron wavelength

    Czech Academy of Sciences Publication Activity Database

    Mikula, Pavol; Vrána, Miroslav; Šaroun, Jan; Davydov, Vadim; Em, V.; Seong, B. S.

    2012-01-01

    Roč. 45, č. 1 (2012), s. 98-105 ISSN 0021-8898 R&D Projects: GA ČR GAP204/10/0654 Institutional research plan: CEZ:AV0Z10480505 Keywords : RESIDUAL STRAIN-STRESS INSTRUMENT * MULTIPLE BRAGG-REFLECTIONS * SINGLE-CRYSTAL Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.343, year: 2012

  6. Photochromic and fluorescent LC gels based on a bent-shaped azobenzene-containing gelator

    Czech Academy of Sciences Publication Activity Database

    Bobrovsky, A.; Shibaev, I.; Hamplová, Věra; Novotná, Vladimíra; Kašpar, Miroslav

    2015-01-01

    Roč. 5, č. 70 (2015), 56891-56895 ISSN 2046-2069 R&D Projects: GA ČR GA13-14133S Institutional support: RVO:68378271 Keywords : liquid crystals * photochromic LC- gels Subject RIV: CC - Organic Chemistry Impact factor: 3.289, year: 2015

  7. A new species of karst-dwelling bent-toed gecko (Squamata: Gekkonidae) from Khammouane Province, central Laos.

    Science.gov (United States)

    Luu, Vinh Quang; Nguyen, Truong Quang; Le, Minh Duc; Bonkowski, Michael; Ziegler, Thomas

    2016-02-10

    We describe a new species of the genus Cyrtodactylus from Khammouane Province, central Laos based on morphological features and molecular data. Morphologically, Cyrtodactylus bansocensis sp. nov. is differentiated from other congeners by a unique combination of the following characters: medium size, SVL reaching 74.0 mm; dorsal pattern consisting of four light transverse bands between limb insertions; supranasals in contact with each other; dorsal tubercles at midbody in 14-15 irregular rows; lateral folds present without interspersed tubercles; ventral scales between ventrolateral folds 34-35; precloacal and femoral pores in males 34, separated by four poreless scales in the male holotype and in a continuous row in the male paratype; enlarged femoral and precloacal scales present; postcloacal tubercles 5-7 on each side; dorsal tubercles present at tail base; and subcaudal scales transversely enlarged. Molecular analyses revealed the new species to be closely related to Cyrtodactylus rufford, which is also found in Khammouane Province.

  8. Cyrtodactylus rufford, a new cave-dwelling bent-toed gecko (Squamata: Gekkonidae) from Khammouane Province, central Laos.

    Science.gov (United States)

    Luu, Vinh Quang; Calame, Thomas; Nguyen, Truong Quang; Le, Minh Duc; Bonkowski, Michael; Ziegler, Thomas

    2016-01-21

    We describe a new species of the gekkonid genus Cyrtodactylus from Khammouane Province, central Laos based on morphological and molecular data. Morphologically, Cyrtodactylus rufford sp. nov. differs from its congeners by a unique combination of the following characters: medium size, SVL reaching 72.5 mm; dorsal pattern with three or four light transverse bands between limb insertions; one intersupranasal; 14-16 irregular dorsal tubercle rows at midbody, weakly developed in the paravertebral region; 27-29 ventral scale rows between ventrolateral folds; 42-43 precloacal and femoral pores in a continuous row in males, enlarged femoral and precloacal scales present; 4 or 5 postcloacal tubercles on each side; dorsal tubercles present at base of tail; medial subcaudal scales enlarged. Molecular analyses show that the new species is closely related to C. khammouanensis, which was originally described from Khammouane Province.

  9. Focusing Bent perfect-crystal neutron monochromator a key to high - resolution stress/strain measurement studies of polycrystalline materials

    Czech Academy of Sciences Publication Activity Database

    Ono, M.; Mikula, Pavol; Harjo, S.; Šaroun, Jan; Yoneda, K.; Sawano, J.; Sakurai, Y.; Kobayashi, T.

    321/324, - (2000), s. 296-301 ISSN 0255-5476. [European Powder Diffraction Conference EPDIC /6./. Budapest, 22.08.1998-25.08.1998] R&D Projects: GA ČR GV202/97/K038; GA AV ČR KSK1010601 Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.597, year: 2000

  10. Stripe and line textures in the B2 phase of bent-shape molecules in samples with polar surface anchoring

    Czech Academy of Sciences Publication Activity Database

    Lejček, Lubor; Novotná, Vladimíra; Glogarová, Milada

    2011-01-01

    Roč. 84, č. 6 (2011), 061701/1-061701/12 ISSN 1539-3755 R&D Projects: GA ČR(CZ) GAP204/11/0723 Institutional research plan: CEZ:AV0Z10100520 Keywords : liquid crystals Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.255, year: 2011

  11. [As the twig is bent, so is the tree inclined: children and the Liga Brasileira de Higiene Mental's eugenic programs].

    Science.gov (United States)

    Reis, J R

    2000-01-01

    Created in the early 1920s, at a moment when the country's psychiatric field was embracing the preventive outlook, the Liga Brasileira de Higiene Mental included within its members the elite of Brazilian psychiatry, along with a number of physicians and intellectuals. The article discusses the institution's proposals for intervention among children. The league ended up incorporating into its theoretical arsenal the basic themes of mental hygiene and eugenics as part of its general goal of collaborating in Brazil's process of "racial sanitation". With this objective in mind, and viewing the child as a "pre-citizen" who is a "fundamental part within the man of the future", league members included the children's issue in their projects and saw an imperative need for mental health care from early ages on.

  12. Successful Percutaneous Coronary Intervention through a Severely Bent Artificial Ascending Aorta Using the DIO Thrombus Aspiration Catheter

    Directory of Open Access Journals (Sweden)

    Akinori Fujikake

    2016-01-01

    Full Text Available A 66-year-old man was admitted to our institute because of chest pain. He had undergone replacement of the ascending aorta due to aortic dissection 9 years previously. We made a diagnosis of acute coronary syndrome, and coronary artery angiography was performed. Although the right coronary artery was successfully cannulated, a severe bend of the artificial aorta made it very difficult to advance the catheter into the left coronary artery. Ultimately, a DIO thrombus aspiration catheter was used to enter the left coronary artery, and a stent was implanted successfully. The DIO catheter is very useful when the selection of a guiding catheter is complicated, such as in the case of severe vessel tortuosity or a bend of the ascending aorta.

  13. Determination of the properties of cereal stalks when being bent and cut with the aid of a universal test bench

    Directory of Open Access Journals (Sweden)

    Andrej Batos

    2015-07-01

    Full Text Available Für die Messung der Biege- und Schnitteigenschaften halmartiger Güter wurde ein Universalprüfstand entworfen. Die mit ihm ermittelten Messwerte dienen der Erstellung von Simulationsmodellen zur Abbildung landtechnischer Schnittprozesse. In der vorliegenden Studie werden Weizenhalme untersucht. Die Schnittversuche erfolgen mit zwei Geschwindigkeiten und zwei Schnittwinkeln. Die Mittelwerte aus jeweils 50 Messungen werden miteinander verglichen. Der Feuchtigkeitsgehalt der Proben liegt zwischen 5,5 und 7,1 %. Die Biegespannungen betragen für das erste Internodium 1,09 N/mm², für das zweite 0,99 N/mm² und für das dritte 1,07 N/mm². Bei den Schnittversuchen tritt die höchste Spannung (4,44 N/mm² beim Schneiden des zweiten Internodiums auf (50 mm/s, 40°. Die niedrigste Spannung (2,20 N/mm² tritt beim Schneiden des dritten Internodiums auf (150 mm/s, 60°. Bis auf eine Ausnahme ist die auf den Probenquerschnitt bezogene Schnittenergie (12,18–19,85 mJ/mm² bei der Auswahl des größeren Winkels höher. Die mittleren Variationskoeffizienten liegen zwischen 5 und 32 %.

  14. Neutron Diffraction Studies of a Fully Asymmetric Diffraction Geometry of a Bent Perfect Crystal with the Output Beam Compression

    Czech Academy of Sciences Publication Activity Database

    Mikula, Pavol; Vrána, Miroslav; Šaroun, Jan; Em, V.; Čapek, J.

    2016-01-01

    Roč. 130, č. 4 (2016), s. 1114-1117 ISSN 0587-4246 R&D Projects: GA ČR GB14-36566G; GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : SANS * neutron diffraction * crystal Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.469, year: 2016

  15. Bent-shaped liquid crystals based on 4-substituted 3-hydroxybenzoic acid central core – Part II

    Czech Academy of Sciences Publication Activity Database

    Tůma, J.; Kohout, M.; Svoboda, J.; Novotná, Vladimíra; Pociecha, D.

    2016-01-01

    Roč. 43, č. 4 (2016), s. 547-563 ISSN 0267-8292 R&D Projects: GA ČR GA13-14133S Institutional support: RVO:68378271 Keywords : liquid crystals Subject RIV: JJ - Other Materials Impact factor: 2.661, year: 2016

  16. Bent Metal in a Bone: A Rare Complication of an Emergent Procedure or a Deficiency in Skill Set?

    Directory of Open Access Journals (Sweden)

    Mridula Krishnan

    2016-01-01

    Full Text Available Intraosseous (IO access is an important consideration in patients with difficult intravenous (IV access in emergent situations. IO access in adults has become more popular due to the ease of placement and high success rates. The most common sites of access include the proximal tibia and the humeral head. The complications associated are rare but can be catastrophic: subsequent amputation of a limb has been described in the literature. We report a 25-year-old female presenting with diabetic ketoacidosis (DKA in whom emergent IO access was complicated by needle bending inside the humerus. Conventional bedside removal was impossible and required surgical intervention in operating room.

  17. Focusing X-rays to a 1-{mu}m spot using elastically bent, graded multilayer coated mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Underwood, J.H.; Thompson, A.C.; Kortright, J.B. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    In the x-ray fluorescent microprobe at beamline 10.3.1, the ALS bending magnet source is demagnified by a factor of several hundred using a pair of mirrors arranged in the Kirkpatrick-Baez (K-B) configuration. These are coated with multilayers to increase reflectivity and limit the pass band of the x-rays striking the sample. The x-rays excite characteristic fluorescent x-rays of elements in the sample, which are analyzed by an energy dispersive Si-Li detector, for a sensitive assay of the elemental content. By scanning the focal spot the spatial distribution of the elements is determined; the spatial resolution depends on the size of this spot. When spherical mirrors are used, the spatial resolution is limited by aberrations to 5 or 10 {mu}m. This has been improved to 1 {mu}m through the use of an elliptical mirror formed by elastically bending a plane mirror of uniform width and thickness with the optimum combination of end couples.

  18. Evaluative Testing of the Bent Canyon Stage Station on the Pinon Canyon Maneuver Site, Las Animas County, Colorado

    Science.gov (United States)

    2005-01-01

    almost impenetrable thickets of alders and willows, as to render our progress extremely tedious and painful " (Thwaites 1905, pp.67-68), cited in... gastropod , and shell fragments from a second invertebrate. The bulk of the faunal assemblage was concentrated in Feature 9 (n = 178). Materials were also...faunal taxa recovered from the 2000 excavations at 5LA3179 is presented in Table 3. 177 Table 3: Faunal taxa recovered Taxon Count Totals Gastropod 1 1

  19. Neutron diffraction studies of a double-crystal ( plus n,-m) setting containing a fully asymmetric diffraction geometry of a bent perfect crystal with output beam expansion

    Czech Academy of Sciences Publication Activity Database

    Mikula, Pavol; Vrána, Miroslav; Pilch, Jan; Seong, B. S.; Woo, W.; Em, V.

    2014-01-01

    Roč. 47, APR (2014), s. 599-605 ISSN 0021-8898 R&D Projects: GA MŠk LM2010011; GA ČR GB14-36566G; GA MŠk(XE) LM2011019 Institutional support: RVO:61389005 Keywords : neutron diffraction * diffractometer * silicon crystal Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.720, year: 2014

  20. Optimization of the bent perfect Si(311)-crystal monochromator for a residual strain/stress instrument at the HANARO reactor - Part I

    Czech Academy of Sciences Publication Activity Database

    Moon, MK; Lee, Ch.H.; Vyacheslav, T.; Mikula, Pavol

    2005-01-01

    Roč. 369, - (2005), s. 1-7 ISSN 0921-4526 R&D Projects: GA ČR GA202/03/0891 Institutional research plan: CEZ:AV0Z10480505 Keywords : neutron monochromator * residual stress measurement * neutron diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.796, year: 2005

  1. Bent-core liquid crystals based on 6-substituted 3-hydroxybenzoic acid: the role of substitution and linkage group orientation on mesomorphic properties

    Czech Academy of Sciences Publication Activity Database

    Tůma, J.; Kohout, M.; Svoboda, J.; Novotná, Vladimíra; Pociecha, D.

    2016-01-01

    Roč. 43, č. 12 (2016), s. 1889-1900 ISSN 0267-8292 R&D Projects: GA ČR GA15-02843S Institutional support: RVO:68378271 Keywords : liquid crystals Subject RIV: JJ - Other Materials Impact factor: 2.661, year: 2016

  2. Propiedades dieléctricas y térmicas de cristales líquidos: dímeros y bent-core

    OpenAIRE

    Robles Hernández, Beatriz

    2016-01-01

    194 p. Los cristales líquidos son materiales de gran interés tecnológico que combinan propiedades de los líquidos, fluidez, y de los sólidos cristalinos, anisotropía.En esta tesis se presenta un estudio detallado de cristales líquidos con diferentes geometrías y grado de flexibilidad. Por un lado se han estudiado dímeros, dos unidades mesógenas unidas por una cadena flexible, algunos de los cuales presentan la novedosa fase nemática twist-bend y por otro lado se han estudiado compuestos ti...

  3. Sustancias naturales de moluscos opistobranquios: estudio de su estructura, origen y función en ecosistemas bentónicos

    OpenAIRE

    Ávila Escartín, Conxita

    1993-01-01

    Los Moluscos Opistobranquios, en relación a la reducción o incluso pérdida de la concha, han desarrollado múltiples y sofisticados métodos de defensa (incluyendo la defensa química) que les han permitido sobrevivir sin dicha defensa mecánica. En esta Tesis se estudia el papel de las sustancias naturales de Moluscos Opistobranquios, haciendo énfasis en aspectos biológicos tales como el origen dietético o biosintético de las mismas, su localización en el organismo, y su actividad y función en e...

  4. Zeg, bent u misschien de nieuwe professional? De omslag van de visie over welzijn naar het handelen van de nieuwe professional

    Directory of Open Access Journals (Sweden)

    Maaike Kluft

    2012-03-01

    Met de introductie van de Wmo en het uitvoeringsprogramma Welzijn Nieuwe Stijl, worden welzijnsorganisaties gestimuleerd om hun manier van werken en de prioriteiten die zij stellen aan de geboden ondersteuning te herzien. De Nederlandse samenleving maakt een ommezwaai van welzijnsstaat naar participatiestaat, wat betekent dat burgers meer verantwoordelijkheid moeten nemen voor hun leven, maar ook voor hun omgeving en sociale netwerk. Dit artikel gaat in op de ondersteuning die nodig is om deze ommezwaai te realiseren en op de consequenties die dit heeft op het werk en de houding van de sociale professional.

  5. Utilização da meiofauna bentônica nomonitoramento do cultivo do camarão Litopenaeus vannamei

    OpenAIRE

    Porchat de Assis Murolo, Priscila

    2005-01-01

    Uma das maiores ameaças ao ecossistema estuarino tem sido o rápido aumento na aqüicultura costeira, e em particular a criação de camarões. O efluente da carcinicultura pode ser a principal fonte de poluição nos estuários. Considerando a sensibilidade da meiofauna à entrada de material antrópico e o grupo Copepoda Harpacticoida como o mais sensível à poluentes, este trabalho teve como objetivo, avaliar a influência da carcinicultura no estuário do rio Botafogo (Itapissuma-PE) utilizando a meio...

  6. Composición y estructura de las comunidades de algas bentónicas de ambientes portuarios: El puerto de Blanes

    Directory of Open Access Journals (Sweden)

    Rodríguez-Prieto, Concepció

    1997-12-01

    Full Text Available The species composition and the estructure of the harbour communities of Enteromorpha compressa, Corallina elongate and the internal communities in Blanes harbour (Girona, España, have been studied by means of descriptive and analytical data. All the quantitative parameters studied show a decrease of diversity in the more superficial stations of the mouth of the harbour, and also an increasing diversity and a drastic decreasing of the reproduction indices at the more poluted stations.

    Se estudia la composición y estructura, por grupos sistemáticos y ecológicos, de tres comunidades portuarias invernales: Enteromorpha compressa, Corallina elongata y las comunidades más interiores del puerto de Blanes (Girona, España. Todos los parámetros cuantitativos estudiados revelan una disminución de la diversidad en las estaciones superficiales de la bocana del puerto, así como un aumento de la diversidad y una drástica disminución de los índices de reproducción en las estaciones más contaminadas.

  7. Minimization of spurious strains by using a Si bent-perfect-crystal monochromator: neutron surface strain scanning of a shot-peened sample

    International Nuclear Information System (INIS)

    Rebelo Kornmeier, Joana; Hofmann, Michael; Gibmeier, Jens

    2011-01-01

    Neutron strain measurements are critical at the surface. When scanning close to a sample surface, aberration peak shifts arise due to geometrical and divergence effects. These aberration peak shifts can be of the same order as the peak shifts related to residual strains. In this study it will be demonstrated that by optimizing the horizontal bending radius of a Si (4 0 0) monochromator, the aberration peak shifts from surface effects can be strongly reduced. A stress-free sample of fine-grained construction steel, S690QL, was used to find the optimal instrumental conditions to minimize aberration peak shifts. The optimized Si (4 0 0) monochromator and instrument settings were then applied to measure the residual stress depth gradient of a shot-peened SAE 4140 steel sample to validate the effectiveness of the approach. The residual stress depth profile is in good agreement with results obtained by x-ray diffraction measurements from an international round robin test (BRITE-EURAM-project ENSPED). The results open very promising possibilities to bridge the gap between x-ray diffraction and conventional neutron diffraction for non-destructive residual stress analysis close to surfaces

  8. Cyrts in the city: a new Bent-toed Gecko (Genus Cyrtodactylus) is the only endemic species of vertebrate from Batu Caves, Selangor, Peninsular Malaysia.

    Science.gov (United States)

    Grismer, L Lee; Wood, Perry L; Onn, Chan Kin; Anuar, Shahrul; Muin, Mohd Abdul

    2014-03-07

    Cyrtodactylus metropolis sp. nov. from Batu Caves massif, Selangor, Peninsular Malaysia is differentiated from all congeners by having a unique suite of morphological and color pattern characteristics. Remarkably, this species has been overlooked despite a plethora of field studies at Batu Caves from 1898 to the present and no specimens had ever been examined until now. As with all other limestone forest-adapted Cyrtodactylus in Peninsular Malaysia, C. metropolis sp. nov. is not a cave-adapted species but is far more common on the exterior surfaces of the Batu Caves limestone massif and its surrounding limestone vegetation. We suggest that researchers devote time exploring the exterior surfaces of limestone massifs as well the interiors of their caves.

  9. Udpegning af risikolokaliteter på det tosporede vejnet i åbent land baseret på data om vejens karakteristika

    DEFF Research Database (Denmark)

    Andersen, Camilla Sloth

    I det stedbestemte trafiksikkerhedsarbejde har udpegning og udbedring af sorte pletter (identificering, analyse samt udbedring af risikolokaliteter på vejnettet) siden 1970’erne været en af de primære aktiviteter. Imidlertid er sortpletarbejdet med årene blevet vanskeligere af to grunde: Dels er ...

  10. Reversible Coordination of Boron-, Aluminum-, Zinc-, Magnesium-, and Calcium-Hydrogen Bonds to Bent {CuL2} Fragments: Heavy σ Complexes of the Lightest Coinage Metal.

    Science.gov (United States)

    Hicken, Alexandra; White, Andrew J P; Crimmin, Mark R

    2017-08-07

    A series of copper(I) complexes bearing electron-deficient β-diketiminate ligands have been prepared. The study includes [{{ArNC(CR 3 )} 2 CH}Cu(η 2 -toluene) n ] (Ar = Mes, R = F, n = 0.5, [1 2 ·tol]; Ar = C 6 F 5 , R = Me, n = 1, [2·tol]; Ar = 2,6-Cl 2 C 6 H 3 , R = H, n = 0.5, [3 2 ·tol]). Reactions of [1-3 n ·tol] with boranes, alanes, a zinc hydride, a magnesium hydride, and a calcium hydride generate the corresponding σ complexes ([1-3·B], [3·B'], [3·Al], [3·Al'], [1-3·Zn], [1·Mg], and [1·Ca]). These species all form reversibly, being in equilibrium with the arene solvates in solution. With the exception of the calcium complex, the complexes have all been characterized by single-crystal X-ray diffraction studies. In solution, the σ-hydride of the aluminum, zinc, magnesium, and calcium derivatives resonates between -0.12 and -1.77 ppm (C 6 D 6 or toluene-d 8 , 193-298 K). For the σ-borane complexes, the hydrides are observed as a single resonance between 2 and 3.5 ppm (C 6 D 6 , 298 K) and bridging and terminal hydrides rapidly exchange on the NMR time scale even at 193 K. Quantification of the solution dynamics by van't Hoff analysis yields expectedly small values of ΔH° and negative values of ΔS° consistent with weak binding and a reversible process that does not involve aggregation of the copper species. The donor-acceptor complexes can be rationalized in terms of the Dewar-Chatt-Duncanson model. Density functional theory calculations show that the donation of σ-M-H (or E-H) electrons into the 4s-based orbital (LUMO or LUMO+1) of the copper fragment is accompanied by weak back-donation from a d xz -based orbital (HOMO or HOMO-1) into the σ*-M-H (or E-H) orbital.

  11. The effects of lateral halogen substituents on the low-temperature cybotactic nematic phase in oxadiazole based bent-core liquid crystals

    NARCIS (Netherlands)

    Jason Nguyen, [Unknown; Wonderly, William; Tauscher, Tatum; Harkins, Robin; Vita, Francesco; Portale, Giuseppe; Francescangeli, Oriano; Samulski, Edward T.; Scharrer, Eric

    2015-01-01

    We have previously demonstrated that the incorporation of lateral methyl groups on oxadiazole-based liquid crystals leads to relatively low-temperature cybotactic nematic phases which, in some cases, supercool to room temperature. We report here the synthesis and phase behaviour of related compounds

  12. A naphthyl-substituted pentamethylcyclopentadienyl ligand and its Sm(II) bent-metallocene complexes with solvent-induced structure change.

    Science.gov (United States)

    Yatabe, Takeshi; Karasawa, Masaki; Isobe, Kiyoshi; Ogo, Seiji; Nakai, Hidetaka

    2012-01-14

    A naphthyl-substituted pentamethylcyclopentadienyl ligand (Cp(Naph) = η(5)-C(5)Me(4)CH(2)C(10)H(7)) and its Sm(II) complexes [Sm(Cp(Naph))(2)(THF)(x)] (1: x = 2, 2: x = 0) have been prepared and characterised. The solvent-induced reversible conversion between the di-THF solvated purple complex 1 and the un-solvated dark green complex 2 is presented.

  13. Residual stress evaluation by X-Ray diffraction and hole-drilling in an API 5L X70 steel pipe bent by hot induction

    Energy Technology Data Exchange (ETDEWEB)

    Ceglias, Rodrigo Braga; Alves, Juciane Maria; Botelho, Ramon Alves; Baeta Junior, Eustaquio de Souza; Santos, Igor Cuzzuol dos; Moraes, Nicki Robbers Darciano Cajueiro de; Oliveira, Rebeca Vieira de; Diniz, Saulo Brinco; Brandao, Luiz Paulo, E-mail: brandao@ime.eb.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Engenharia Mecanica e de Materiais

    2016-09-15

    The API 5L X70 steel is used in high-pressure gas transmission pipelines. Because of this, knowledge of presence of residual stress and their magnitude is important to assess the material integrity in service. For the pipeline manufacturing, tubes need to be curved which is often made using the hot induction bending process. This process can introduce different residual stress depending of tube position. For this research, in order to evaluate the residual stress, was used an API 5L X70 tube that was previously curved by hot induction process. Samples were taken from the extrados, intrados, neutral line and straight section of the curved tube. Residual stresses were studied by two conventional methods: X-Ray Diffraction (XRD) and Hole-Drilling, which are destructive and non-destructive methods, respectively, in order to assess their qualitative responses. Each of these methods presents particular methodologies in sample preparation and material analysis, but also they differ in factors such time consumption and cost of the analysis. The qualitative responses obtained by the two different methods were comparable and satisfactory and pointed out the existence of a compressive residual stress state in steel pipe. (author)

  14. Avaliação da qualidade ambiental, utilizando invertebrados bentônicos, nos rios Atibaia, Atibainha e Cachoeira, SP

    OpenAIRE

    Helio Rubens Victorino Imbimbo

    2006-01-01

    As fases imaturas dos insetos das Ordens Ephemeroptera, Plecoptera e Trichoptera (EPT) são consideradas membros sensíveis da comunidade macrobentônica dos ecossistemas lóticos. Portanto, são freqüentemente utilizados como indicadores de perturbações ambientais como a poluição. Foram adotados oito pontos de amostragem ao longo dos rios Atibainha, Cachoeira e Atibaia, na bacia do rio Piracicaba, São Paulo. Nestes locais foram determinadas as qualidades e toxicidades da água e do sedimento, bem ...

  15. Organic reactions for the electrochemical and photochemical production of chemical fuels from CO2--The reduction chemistry of carboxylic acids and derivatives as bent CO2 surrogates.

    Science.gov (United States)

    Luca, Oana R; Fenwick, Aidan Q

    2015-11-01

    The present review covers organic transformations involved in the reduction of CO2 to chemical fuels. In particular, we focus on reactions of CO2 with organic molecules to yield carboxylic acid derivatives as a first step in CO2 reduction reaction sequences. These biomimetic initial steps create opportunities for tandem electrochemical/chemical reductions. We draw parallels between long-standing knowledge of CO2 reactivity from organic chemistry, organocatalysis, surface science and electrocatalysis. We point out some possible non-faradaic chemical reactions that may contribute to product distributions in the production of solar fuels from CO2. These reactions may be accelerated by thermal effects such as resistive heating and illumination. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Two new Bent-toed Geckos of the Cyrtodactylus pulchellus complex from Peninsular Malaysia and multiple instances of convergent adaptation to limestone forest ecosystems.

    Science.gov (United States)

    Grismer, L Lee; Wood, Perry L; Anuar, Shahrul; Grismer, Marta S; Quah, Evan S H; Murdoch, Matthew L; Muin, Mohd Abdul; Davis, Hayden R; Aguilar, César; Klabacka, Randy; Cobos, Anthony J; Aowphol, Anchalee; Sites, Jack W

    2016-04-25

    A new species of limestone cave-adapted gecko of the Cyrtodactylus pulchellus complex, C. hidupselamanya sp. nov., is described from an isolated karst formation at Felda Chiku 7, Kelantan, Peninsular Malaysia. This formation is scheduled to be completely quarried for its mineral content. From what we know about the life history of C. hidupselamanya sp. nov., this will result in its extinction. A new limestone forest-adapted species, C. lenggongensis sp. nov., from the Lenggong Valley, Perak was previously considered to be conspecific with C. bintangrendah but a re-evaluation of morphological, color pattern, molecular, and habitat preference indicates that it too is a unique lineage worthy of specific recognition. Fortunately C. lenggongensis sp. nov. is not facing extinction because its habitat is protected by the UNESCO Archaeological Heritage of the Lenggong Valley due to the archaeological significance of that region. Both new species can be distinguished from all other species of Cyrtodactylus based on molecular evidence from the mitochondrial gene ND2 and its flanking tRNAs as well as having unique combinations of morphological and color pattern characteristics. Using a time-calibrated BEAST analysis we inferred that the evolution of a limestone habitat preference and its apparently attendant morphological and color pattern adaptations evolved independently at least four times in the C. pulchellus complex between 26.1 and 0.78 mya.

  17. Erratum: International Journal of Global Energy Issues, Vol. 13, Nos. 1-3, 2000, p.247. Bent Soerensen and Peter Meibom 'A global renewable energy scenario'

    International Nuclear Information System (INIS)

    2001-01-01

    5.1 ecentralised renewable energy 2050 scenario. The demand categories have already, as shown in Table 6, been simplified under the assumption of an abundant fraction of the supply being in the form of electric energy. We now determine the sources of supply for each demand type. For the vegetable food-fraction, the results of comparing local supply and demand are shown in Figures 38 and 39, where Figure 38 shows the amount of surplus for those geographical grid cells, where supply exceeds demand, and Figure 39 shows the amount of deficit for those local cells where demand exceeds supply. Regional sums are given in Table 10, while the sums of individual contributions to demand and supply are given in Tables 6 and 8. It follows that on average, worldwide supply exceeds demand by 35%. This must be considered reasonable, as there has to be room for variations in crop harvests and thus food production from year to year, and further the transportation required for evening out supply and demand will entail some additional losses. Like today, there is surplus vegetable food production in the Americas and Western Europe (regions 1, 2 and 4), and by the year 2050 also in region 3 (including Russia), due to substantial improvements in agricultural practices assumed for this region. Region 5 (including China and India) will be just self-sufficient by the year 2050, whereas Africa (region 6) will have a deficit that must be covered by imports. In the scenario, Africa is the only region that by 2050 is in a development situation where it may offer labour at lower expense that the other regions, and thus there will be the possibility of paying for food imports by industrial revenues, provided that an education policy is pursued, that will give the workforce the necessary skills. In addition to inter-regional exchange, Figures 38 and 39 indicate scenario requirements for transport of vegetable food within regions, especially from farming areas into cities. The scenario assumptions for inter-regional trade in food is indicated in Figures 55-60, where the regional exports have been selected from the surpluses available. The substantial needs for both vegetable and animal foods in Africa are uniformly imported from regions 1-4. (author)

  18. Assessment of Gravel Operation Damage to Prehistoric Sites and Recording the Santa Fe Trail within the John Martin Reservoir Project Area, Bent County, Colorado and Evaluation of Old Las Animas (5BN176), a Late Nineteenth Century Town on the Arkansas River, Bent County, Colorado.

    Science.gov (United States)

    1987-06-01

    include sandhill cranes, magpies , wild turkeys, partridges, ;Ifad rattlesnakes. Probably also present but not observed are cottontail, il lrabhit...the Ninth Cavalry, part of which was stationed at Fort Lyon. Miller had been tried and found guilty of murder , his trial being held in a civilian court

  19. [UO{sub 2}Cl{sub 2}(phen){sub 2}], a simple uranium(VI) compound with a significantly bent uranyl unit (phen=1,10-phenanthroline)

    Energy Technology Data Exchange (ETDEWEB)

    Schoene, Sebastian; Radoske, Thomas; Maerz, Juliane; Stumpf, Thorsten; Patzschke, Michael; Ikeda-Ohno, Atsushi [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology, Dresden (Germany)

    2017-10-04

    A simple synthesis based on UO{sub 2}Cl{sub 2}.n H{sub 2}O and 1,10-phenanthroline (phen) resulted in the formation of a new uranyl(VI) complex [UO{sub 2}Cl{sub 2}(phen){sub 2}] (1), revealing a unique dodecadeltahedron coordination geometry around the uranium center with significant bending of the robust linear arrangement of the uranyl (O-U-O) unit. Quantum chemical calculations on complex 1 indicated that the weak but distinct interactions between the uranyl oxygens and the adjacent hydrogens of phen molecules play an important role in forming the dodecadeltahedron geometry that fits to the crystal structure of 1, resulting in the bending the uranyl unit. The uranyl oxygens in 1 are anticipated to be activated as compared with those in other linear uranyl(VI) compounds. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Ecología, sistemática y distribución de Foraminíferos Bentónicos entre la desembocadura del río Sinú y Coveñas, Caribe Colombiano

    Directory of Open Access Journals (Sweden)

    Parada Ruffinatti Carmen

    1985-09-01

    Full Text Available En cuatro ecosistemas diferentes: estuario, laguna costera, zona litoral y zona infralitoral, se identificó una microfauna constituida por 75 taxa, de los cuales un 14.6110estuvo representado en la biocenosis. Se  encontró que Ammonia beccarii es la especie de más amplia distribución en todos los ambientes estudiados.Los grupos faunísticos se relacionaron con algunos parámetros ecológicos.En el ecosistema marino infralitoral se estableció un predominio de género Quinqueloculina en sedimentos arenosos y del genera Nonionella, en sedimentos limo-arcillosos. Quinqueloculina distorqueata Cushman, Q. ferussacii d'Orbigny y Fursenkoina fusiformis (Williamson son reportadas por primera vez en el Caribe.

  1. Foraminíferos bentónicos de tres playas en Isla Barú (Caribe colombiano y su relación con algunos parámetros sedimentológicos

    Directory of Open Access Journals (Sweden)

    Carlos Delgado Mejía

    1995-01-01

    Full Text Available Benthic foraminiferal communities and sediments in three shores of Barú island are studied. These ones were selected because they have different characteristics. In Mohan beach, situed al norwest side of the island, the sediments are coarse grained, with high contents of calcium carbonate. In Marimberos beach, situated at Barbacoas bay, the sediments are something finer and of continental origino at Muertos beach, situated at southeastearn extreme, there are intermediate characteristics. About the biothic component, there are different distribution between the foraminiferal species, that are related with calcium carbonate, grain size and e/N relationship.

  2. Hábitats y grupos funcionales alimentarios de los macroinvertebrados bentónicos en la costa bonaerense del Río de la Plata: relación con la contaminación

    OpenAIRE

    Ambrosio, Eugenia Soledad

    2014-01-01

    La calidad ecológica de los ecosistemas está determinada por la interacción de dos ejes principales: la calidad del hábitat, estimada a partir del análisis de los hábitats funcionales y la calidad del agua, estimada a partir del grado de contaminación (características físico-químicas). Esta interacción determina la calidad biótica del sistema, de manera que la estructura y función de los ensambles de macroinvertebrados varían según la intensidad de cada uno de los factores que intervienen. ...

  3. Riparian leaf litter processing by benthic macroinvertebrates in a woodland stream of central Chile Procesamiento de detritus ripariano por macroinvertebrados bentónicos en un estero boscoso de Chile central

    OpenAIRE

    CLAUDIO VALDOVINOS

    2001-01-01

    Leaf litter input from riparian landscapes has been identified as both a major energy flow to stream ecosystems and as a food source for stream macroinvertebrates. In riparian landscapes of woodland streams of central Chile, the native deciduous hardwoods are being artificially replaced by exotic coniferous trees at a large spatial scale. It is suggested that this process has a significant impact on the stream communities of central Chile. Today, exotic plantations occur throughout central Ch...

  4. Estrutura da comunidade de invertebrados bentônicos em dois cursos d'água do Rio Grande do Sul, Brasil Community structure of benthic invertebrates in two watercourses in Rio Grande do Sul State, southern Brazil

    Directory of Open Access Journals (Sweden)

    Alessandra A. P. Bueno

    2003-03-01

    Full Text Available The benthic fauna has an important role in the trophic chain of limnic environments, serving as food for fishes and crustaceans. This work aimed to identify and compare, quantitative and qualitatively, the macrobenthic communities from two watercourses in Rio Grande do Sul State. Samplings were done with a Surber sampler, monthly, from September 1999 to August 2000, in one of the creeks forming Tainhas River(29º15'30,2"S, 50º13'12,5"W, around São Francisco de Paula city and in Mineiro Creek (29º30'0,2"S, 50º46'50"W, around Taquara city. At each sampling point, physical and chemical variables of the waters were registered. In the laboratory, the samples were sorted out and the animals identified and quantified. Dissolved oxigen, pH and stream speed were very similar for both environments, whilst conductivity had extreme values. Insects, crustaceans, acari and molluscs dominated in the samples. Abundance, richness and diversity indexes in Tainhas subsidiary had relatively higher average values than Mineiro Creek. Similarity matrix groupings between sampling units indicate three groups. Our research revealed important characteristics of the ecology and distribution of benthic invertebrates, information that can subsidise future environmental monitoring in the region of São Francisco de Paula and Taquara.

  5. Duften af frihed i det åbne fængsel - en analyse af hvordan det opleves at afsone i et åbent fængsel

    DEFF Research Database (Denmark)

    Abrahamsen, Marie Herping

    2017-01-01

    The sociological interest in prison has traditionally focused on common feature and the main attention have been on the more restrictive and closed prison regimes (Liebling 2004; Crewe 2007). In the last 10 years, this has changed partly because of John Pratts two-parted article “Scandinavian...

  6. Evolution in karst massifs: Cryptic diversity among bent-toed geckos along the Truong Son Range with descriptions of three new species and one new country record from Laos.

    Science.gov (United States)

    Luu, Vinh Quang; Bonkowski, Michael; Nguyen, Truong Quang; Le, Minh Duc; Schneider, Nicole; Ngo, Hanh Thi; Ziegler, Thomas

    2016-05-02

    Species designated as 'cryptic' share a similar morphotype, and are often only clearly separable by molecular data. Cyrtodactylus, the most diverse gecko genus of the family Gekkonidae, is a prime example, because many morphologically similar taxa have only recently been identified as new species as a result of available genetic evidence. However, while cryptic diversity of Cyrtodactylus is already well documented on the Vietnamese side of the Truong Son range, only scarce data is available from central Laos. In this study, we address this issue by means of an integrative approach, which employs morphological, molecular, and ecological data to distinguish cryptic species of the Cyrtodacylus phongnhakebangensis species group primarily distributed along the northern Truong Son Range. Our analyses based on 12 selected morphological characters, a partial mitochondrial gene (COI), and five ecological parameters revealed three undescribed cryptic Cyrtodactylus species from Hin Nam No National Protected Area, which are described as Cyrtodactylus calamei sp. nov., Cyrtodactylus hinnamnoensis sp. nov., and Cyrtodactylus sommerladi sp. nov. A fourth discovered Cyrtodactylus population in Hin Nam No proved to be the first country record of C. cryptus for Laos. Our results highlight the importance of applying an integrative approach to resolving the taxonomy of complex and cryptic species groups, and the role of the Truong Son Range in maintaining the high level of biodiversity over time.

  7. The systematics and independent evolution of cave ecomorphology in distantly related clades of Bent-toed Geckos (Genus Cyrtodactylus Gray, 1827) from the Mekong Delta and islands in the Gulf of Thailand.

    Science.gov (United States)

    Grismer, L Lee; Wood, P L Jr; Tri, Ngo Van; Murdoch, Matthew L

    2015-06-26

    An integrative taxonomic analysis of the distantly related Cyrtodactylus condorensis and intermedius species complexes of the Mekong Delta revealed that C. paradoxus is a junior synonym of C. condorensis and that C. thochuensis is a junior synonym of C. leegrismeri. Additionally, the analysis revealed that a cave-dwelling ecomorpholgy has evolved independently early on in the evolution of both complexes (represented by C. hontreensis in the intermedius complex and C. grismeri and C. eisenmani in the condorensis complex) and cave ecomorphs exist in sympatry-but not syntopy-with general scansorial ecomorphs. Multiple, recent, cyclical, glacioeustatic driven changes in sea levels across the Sunda Shelf are hypothesized to account for the evolution and distribution of the widely separated, conspecific insular populations of C. condorensis and C. leegrismeri. The independent evolution of cave ecomorphology is proposed to have been driven by competition avoidance. Habitat islands across the Mekong Delta are an important source of endemism and in need of protection.

  8. Análise Multivariada de Dados Ecológicos da Baía de Guanabara- RJ,com Base em Foraminíferos Bentônicos.

    Directory of Open Access Journals (Sweden)

    Priscila Tavares dos Santos

    2007-07-01

    Full Text Available Guanabara bay is an estuary environment situated in the seaboard of Rio de Janeiro state, under the coordinates 22º 40’ and 23º 00’S and 43º 00’ and 43º 20’W. Nowadays, it has an approximate area of 377 km2, it has had a reduction of 91 km2 since the discovery of Brazil, being considered one of the most polluted seacoast regions of the country. The environmental monitoring of Guanabara bay becomes increasingly necessary in order to be capable of taking effectivemeasures in its management. Therefore, the use of bioindicator organisms, like foraminifera, is an excellent tool because of their rapid response to environmental changes. The goal of this paper is to apply statistical analyses to the biotic data benthicforaminifera, aiming to observe how they behave in Guanabara bay. In November 1999, samples of bottom sediment were collected along Guanabara bay; 52 of them distributed along all the bay were used in this study. They were treated and classified according to the pattern methodology for foraminifera. For the numerical ecology, grouping analysis and indicating species analysis (ISA were done using the programs Statistica 6.0 and PCORD. Through the groupinganalysis, it was observed the formation of groups in both samples and species. ISA showed what species is the best one toindicate the actual state of Guanabara bay - Ammonia tepida. The multivaried ecological analyses had an optimal response in the evaluation of patterns of pollution in Guanabara bay, based on benthic foraminifera.

  9. Prevention: Exercise

    Medline Plus

    Full Text Available ... legs to touch the wall, keeping hips and knees bent. Use your hips to push your body ... Abdominal Exercise Lay on your back with both knees bent. Draw abdominal wall in. Maintaining abdominal wall ...

  10. Dramatik, dialog, duel

    DEFF Research Database (Denmark)

    Bonde, Lars Ole

    2006-01-01

    Introduktion til instrumentalkoncerten som genre i Bent Lorentzens oeuvre, og beskrivelse af tre koncerter: Klaverkoncerten, Italiensk koncert og Jagtkoncert......Introduktion til instrumentalkoncerten som genre i Bent Lorentzens oeuvre, og beskrivelse af tre koncerter: Klaverkoncerten, Italiensk koncert og Jagtkoncert...

  11. Is this about me ? : responding to subtle discrimination beyond an individual versus group perspective

    NARCIS (Netherlands)

    Stroebe, Katherine

    2009-01-01

    Stel: Je bent Marokkaans en hebt gesolliciteerd op een baan. Je wordt afgewezen. Hoe voel je je als je ontdekt dat je bent afgewezen omdat je Marokkaans bent? Eerder onderzoek biedt tegenstrijdig antwoord op deze vraag: Het toeschrijven van negatieve uitkomsten aan discriminatie heeft soms

  12. Immobilizing Bacillus subtilis on the carrier of poly (acrylic acid)/sodium bentonite for treating sludge from Pangasius fish ponds

    International Nuclear Information System (INIS)

    Nguyen Thanh Duoc; Doan Binh; Pham Thi Thu Hong

    2016-01-01

    Sodium bentonite (NaBent) was modified by poly(acrylic acid) (PAAc) to prepare the carriers for immobilization of Bacillus subtilis. Different mixtures of NaBent/AAc were regularly dispersed in distilled water and irradiated under gamma rays at an absorbed dose of 6.5 kGy with dose rate of 0.85 kGy/hr in air for polymerization of acrylic acid and formation of poly(acrylic acid)/sodium bentonite (PAAc-NaBent). The reaction yield was determined with the initial concentration of acrylic acid (AAc). The functional group properties of the resulting PAAc-NaBent were analyzed by Fourier Transform Infrared spectra (FTIR). Bacillus subtilis cells were immobilized on both NaBent and PAAc-NaBent as carriers by adsorption method for treating the sludge contaminated by fish feces and residual feed from the Pangasius farming ponds. The results showed that immobilization capacity of Bacillus subtilis on the PAAc-NaBent was better than that on non-modified NaBent. Analysis of BOD for the farming pond water containing Bacillus subtilis and the bacteria immobilized carriers with time revealed the lower BOD values obtained with the samples containing PAAc-NaBent, suggested that degradation of organic pollutants by Bacillus subtilis immobilized on the PAAc-Na Bent was faster than that by free bacteria. (author)

  13. Crystals channel high-energy beams in the LHC

    CERN Multimedia

    CERN Bulletin

    2015-01-01

    Bent crystals can be used to deflect particle beams, as suggested by E. Tsyganov in 1976. Experimental demonstrations have been carried out for four decades in various laboratories worldwide. In recent tests, a bent crystal inserted into the LHC beam halo successfully channelled and deflected 6.5 TeV protons into an absorber, with reduced secondary irradiation.    Quasimosaic crystal for the LHC (developed by PNPI). Bent crystal technology was introduced at CERN and further developed for the LHC by the UA9 Collaboration. For about ten years, experts from CERN, INFN (Italy), Imperial College (UK), LAL (France), and PNPI, IHEP and JINR (Russia) have been investigating the advantages of using bent crystals in the collimation systems of high-energy hadron colliders. A bent crystal replacing the primary collimator can deflect the incoming halo deeply inside the secondary collimators, improving their absorption efficiency. “The bent crystals we have just tested at the world-record en...

  14. Seasonal variability on the structure of sublittoral macrozoobenthic association in the Patos Lagoon estuary, southern Brazil Variabilidade sazonal na estrutura da associação de macroinvertebrados bentônicos em uma enseada estuarina da Lagoa dos Patos, sul do Brasil

    Directory of Open Access Journals (Sweden)

    Leonir A. Colling

    Full Text Available The aim of this study is to analyze and relate the spatial-temporal variability of macrozoobenthic assemblages to bottom characteristics and salinity fluctuations, in an estuarine shallow water region of Patos Lagoon. Monthly samples, between September 2002 and August 2003, were taken on six sampling stations (distant 90 m. Three biological samples with a 10 cm diameter corer, one sample for sediment analysis, fortnightly bottom topography measurements, and daily data of temperature and salinity were taken from each station. Two biotic and environmental conditions were identified: the first corresponding to spring and summer months, with low macrozoobenthos densities, low values of salinity, small variations in bottom topographic level and weak hydrodynamic activity. A second situation occurred in the months of fall and winter, which showed increased salinity, hydrodynamics and macrobenthos organisms. These results which contrast with previous studies carried out in the area, were attributed to failure in macrozoobenthos recruitments during summer period, especially of the bivalve Erodona mactroides Bosc, 1802 and the tanaid Kalliapseuses schubartii Mañe-Garzón, 1949. This results showed that recruitments of dominant species were influenced by salinity and hydrodynamic conditions.Objetiva-se analisar e relacionar a variabilidade espaço-temporal de uma associação macrozoobentônica com as características do substrato e variações da salinidade, numa enseada da região estuarina da Lagoa dos Patos. Amostragens mensais entre setembro de 2002 e agosto de 2003 foram realizadas em seis pontos de coleta distantes 90 m entre si. Em cada ponto foram tomadas três amostras biológicas com tubo extrator de 10 cm de diâmetro, uma amostra para análise do sedimento, medidas quinzenais da topografia do fundo e dados diários de temperatura e salinidade. Foram identificadas duas situações ambientais e bióticas bem definidas: uma correspondente aos meses de primavera e verão com baixas densidades do macrozoobentos, baixos valores de salinidade e pouca variação no nível do substrato, refletindo neste caso uma menor atividade hidrodinâmica. A outra situação ocorreu nos meses de outono e inverno, que mostrou uma situação oposta em relação às variáveis bióticas e abióticas. Esses resultados, que contrariam trabalhos anteriores efetuados na região, foram atribuídos a falhas nos recrutamentos do macrozoobentos durante o período de verão, especialmente do bivalve Erodona mactroides Bosc, 1802 e do tanaidáceo Kalliapseudes schubartii Mañe-Garzón, 1949. Verificou-se que os recrutamentos das espécies dominantes foram influenciados pelas condições de salinidade e pela hidrodinâmica.

  15. Biología, distribución e integración del alga alóctona Undaria pinnatifida (Laminariales, Phaeophyta en las comunidades bentónicas de las costas de Galicia (NW de la Península Ibérica

    Directory of Open Access Journals (Sweden)

    Cremades Ugarte, Javier

    2006-12-01

    Full Text Available Undaria pinnatifida is an Asian seaweed that is valuable as an edible species. This kelp was first reported for Spain in the 1980s on Galician coasts, where it is now widely distributed and incorporated into the native community. In Galicia, intertidal populations of the sporophytic phase typically inhabit sites under moderate wave-exposure in the early spring, albeit they can be found throughout the year as the species displays at least two recruitment periods per year. The morphology varies between individuals and depends strongly on the spatiotemporal pattern of environmental conditions. The chronology of the introduction of this species and the types of habitat where it is currently integrated on Galician coasts clearly reveal that the presence and local expansion of this kelp is influenced largely by human activities, mainly shellfish aquaculture and maritime traffic. U. pinnatifida has a slow natural expansion, limited aggressiveness and it temporarily fills empty niches; this kelp displays luxuriant growth only on artificial substrates or in otherwise disturbed communities.Undaria pinnatifida es una especie asiática de gran interés económico como alga alimentaria que en la década de los ochenta apareció por primera vez en España en las costas de Galicia, donde actualmente se encuentra ampliamente distribuida y naturalizada. Las poblaciones intermareales de los esporófitos de esta especie en la costa gallega son propias de localidades moderadamente expuestas a la acción del oleaje, siendo muy notorias a principios de primavera; aunque pueden encontrarse casi todoel año, al existir al menos dos períodos anuales de reclutamiento. La morfología de los ejemplares que las forman es muy variable y está fuertemente relacionada con las variaciones espaciotemporales de las condiciones ambientales. Analizando la cronología de su introducción en Galicia y los hábitats y tipos de comunidades en las que se integra, se observa claramente la influencia de las actividades humanas en todo ello, sobre todo las derivadas de la acuicultura de moluscos y el tráfico marítimo. U. pinnatifida es una especie de lenta expansión natural, poco agresiva y que ocupa temporalmente nichos ecológicos vacíos, siendo solo abundante sobre sustratos artificiales o en aquellos naturales cuya vegetación ha sido en alguna medida previamente degradada.

  16. Full dimensional Franck-Condon factors for the acetylene tilde{{A}} 1Au—{tilde{X}} {^1Σ _g^+} transition. I. Method for calculating polyatomic linear—bent vibrational intensity factors and evaluation of calculated intensities for the gerade vibrational modes in acetylene

    Science.gov (United States)

    Park, G. Barratt

    2014-10-01

    Franck-Condon vibrational overlap integrals for the tilde{A} {^1A_u}—{tilde{X}} {^1Σ _g^+} transition in acetylene have been calculated in full dimension in the harmonic normal mode basis. The calculation uses the method of generating functions first developed for polyatomic Franck-Condon factors by Sharp and Rosenstock [J. Chem. Phys. 41(11), 3453-3463 (1964)], and previously applied to acetylene by Watson [J. Mol. Spectrosc. 207(2), 276-284 (2001)] in a reduced-dimension calculation. Because the transition involves a large change in the equilibrium geometry of the electronic states, two different types of corrections to the coordinate transformation are considered to first order: corrections for axis-switching between the Cartesian molecular frames and corrections for the curvilinear nature of the normal modes at large amplitude. The angular factor in the wavefunction for the out-of-plane component of the trans bending mode, ν _4^' ' }, is treated as a rotation, which results in an Eckart constraint on the polar coordinates of the bending modes. To simplify the calculation, the other degenerate bending mode, ν _5^' ' }, is integrated in the Cartesian basis and later transformed to the constrained polar coordinate basis, restoring the conventional v and l quantum numbers. An updated tilde{A}-state harmonic force field obtained recently in the R. W. Field research group is evaluated. The results for transitions involving the gerade vibrational modes are in qualitative agreement with experiment. Calculated results for transitions involving ungerade modes are presented in Paper II of this series [G. B. Park, J. H. Baraban, and R. W. Field, "Full dimensional Franck-Condon factors for the acetylene tilde{A} {^1A_u}—{tilde{X}} {^1Σ _g^+} transition. II. Vibrational overlap factors for levels involving excitation in ungerade modes," J. Chem. Phys. 141, 134305 (2014)].

  17. Diversity, dynamics and biogeography of Chilean benthic nearshore ecosystems: an overview and guidelines for conservation Diversidad, dinámica y biogeografía del ecosistema costero bentónico de Chile: revisión y bases para conservación marina

    Directory of Open Access Journals (Sweden)

    MIRIAM FERNANDEZ

    2000-12-01

    Full Text Available Despite Chile has been one of the pioneering countries in studies of human impact on marine communities, and despite the enormous economic and social significance that the marine environment has for the country, the development of marine conservation programs and the scientific basis for sustainability has not kept pace, with the exploitation rate of marine fisheries and the increasing use of the coast for other purposes. Although we think that the establishment of any conservation policies along the vast coastline of Chile must be based on a multitude of approaches and considerations, scientific, biological, and ecological principles should guide much of these efforts. In this paper, we attempt to present a general overview of the current knowledge about the ecology and biogeography of nearshore systems in Chile. Based on the most relevant existing information, our goals are to: 1 Identify major biogeographic and ecological features of nearshore ecosystems, and the obvious gaps in information, 2 identify the most harmful human activities impacting the structure and dynamics of these systems, and 3 suggest the possible use of indicators to assess the conservational status of different environments along the coast. This overview shows, on one side, the geographic areas of deficitary knowledge on nearshore environments that are critical for future marine conservation and management plans, and on the other, the availability of high quality information for other geographic areas along the coast. Regarding the taxonomy and large-scale patterns of species distribution, important gaps in information were detected, however no big changes in the total number of species are expected in the future. There are few large-scale patterns of species distribution are reported in the literature, and in this contribution, but more work needs to be done, particularly for some taxa, to identify areas of high species diversity as well as areas which possess unique characteristics in terms of ecosystem processes (e.g., particular disturbance and upwelling regimes in coastal marine ecosystems and species (e.g., endemic and keystone species. For most marine invertebrates and macroalgae, hotspots in species diversity are present in southern Chile. New studies addressing the causal factors generating these large-scale patterns of species distribution are also needed; information about coastal oceanography and larval supply is still poor. This information crucial for the design of a marine reserve network. The information available on community structure and ecosystem functioning, especially highlighting the effect of human impact, comes from very few geographic regions. More information about community structure for other areas of the coast is required, particularly considering the strong differences in temperature, circulation patterns, habitat heterogeneity, species composition, as well as of upwelling and El Niño effects along the 4,000 km of coastline. Finally, we list what we think are the most harmful human activities by area and environment along the coast, and integrate this information to suggest possible environmental indicators, and basic needs and guidelines for marine conservation in ChileA pesar de que Chile ha sido un país pionero en estudios del efecto del impacto humano sobre la estructura comunitaria en ambientes marinos, y a pesar de la enorme importancia económica y social que el ambiente marino tiene para el país, el desarrollo de programas de conservación marina y de bases científicas para la sustentabilidad no se han generado a la misma tasa a la que han explotado los recursos y se ha utilizado el ambiente costero para diversos fines. Aunque nosotros pensamos que el establecimiento de planes de conservación a lo largo de la costa de Chile debe basarse en varios factores, los principios científicos, biológicos y ecológicos deben guiar muchos de estos esfuerzos, y en este trabajo nosotros intentamos presentar una visión general del estado actual del conocimiento sobre la ecología y la biogegrafía del sistema costero en Chile. En base a la información más relevante existente, nuestros objetivos son: 1 identificar las características biogeográficas y ecológicas del ecosistema costero y también vacíos en información, 2 identificar las actividades humanas más dañinas que tengan impacto en la estructura y dinámica de estos sistemas, y 3 sugerir el uso de posibles indicadores para determinar la situación de diferentes áreas de la costa de Chile, y las necesidades de conservación. Esta revisión muestra, por un lado, áreas geográficas con información crítica deficitaria para planes futuros de manejo y conservación marina , y por el otro lado, la disponibilidad de información de alta calidad para otras zonas geográficas del país. Respecto de la información existente sobre taxonomía y patrones de distribución de especies a gran escala, existen importantes vacíos de información; no se esperan en el futuro grandes cambios en el número total de especies. Existen pocos estudios sobre patrones de distribución de especies a gran escala, y más información es necesaria para identificar áreas de alta diversidad de especies, especialmente para algunos taxa, como también para identificar áreas que posean características únicas en relación a especies (endémicas, especies claves y a procesos ecosistémicos (disturbios, surgencias. Para la mayoría de los invertebrados y macroalgas, las áreas de alta diversidad de especies se encuentran en el sur de Chile. Nuevos estudios dirigidos a entender los factores que podrían generar patrones a macroescala son necesarios, como también información sobre oceanografía costera y disponibilidad de larvas. Esta información es clave para el diseño de una futura red de parques marinos. Por otro lado, la información disponible sobre estructuras comunitarias y funcionamiento ecosistémico, especialmente sobre el efecto del impacto humano, provienen de pocas regiones geográficas. Mas información sobre otras zonas geográficas es requerida, particularmente si se consideran las diferencias notables en temperatura, patrones de circulación, heterogeneidad del habitat, y composición de especies, como también el efecto de surgencia y de El Niño a lo largo de los más de 4.000 km de costa de Chile. Finalmente, listamos las que consideramos son las actividades humanas más dañinas para el ambiente marino, e integramos esta información para sugerir posibles indicadores ambientales y necesidades básicas y sugerencias para conservación marina in Chile

  18. "De pequenino é que se torce o pepino": a infância nos programas eugênicos da Liga Brasileira de Higiene Mental "As the twig is bent, so is the tree inclined": children and the Liga Brasileira de Higiene Mental’s eugenic programs

    Directory of Open Access Journals (Sweden)

    José Roberto Franco Reis

    2000-06-01

    Full Text Available Este artigo propõe-se a discutir as propostas de intervenção na problemática infantil apresentadas pela Liga Brasileira de Higiene Mental (LBHM, instituição criada no começo da década de 1920 que reunia a elite da psiquiatria brasileira, mas também alguns médicos e intelectuais em geral. Fundada num momento de afirmação, no campo psiquiátrico, da perspectiva preventiva, a LBHM vai incorporar ao seu arsenal teórico os temas básicos da higiene mental e da eugenia, tendo em vista o seu objetivo maior de colaborar no "saneamento racial" brasileiro. Assim, é a partir desse objetivo e vendo na criança um "pré-cidadão", "peça fundamental do homem do futuro", que os psiquiatras da liga incluem a questão infantil nos seus projetos, passando a considerar imperiosa a necessidade de cuidados desde a mais tenra idade.Created in the early 1920s, at a moment when the country’s psychiatric field was embracing the preventive outlook, the Liga Brasileira de Higiene Mental included within its members the elite of Brazilian psychiatry, along with a number of physicians and intellectuals. The article discusses the institution’s proposals for intervention among children. The league ended up incorporating into its theoretical arsenal the basic themes of mental hygiene and eugenics as part of its general goal of collaborating in Brazil’s process of "racial sanitation". With this objective in mind, and viewing the child as a "pre-citizen" who is a "fundamental part within the man of the future", league members included the children’s issue in their projects and saw an imperative need for mental health care from early ages on.

  19. Ecologia de comunidades de insetos bentônicos (Ephemeroptera, Plecoptera e Trichoptera, em córregos do parque ecológico de Goiânia, Goiás, Brasil Ecology of benthic insects communi ites (Ephemeroptera, Plecoptera and Trichoptera in streams at parque ecológico de Goiânia, Goiás, Brazil

    Directory of Open Access Journals (Sweden)

    Leandro Gonçalves Oliveira

    1997-12-01

    Full Text Available Relationships among some abiotic factors (temperature, velocity, flow, conductivity, oxy-reduction potential and pH and the seazonal density of benthic insects (immature forms of the orders Ephemeroptera, Plecoptera and Trichoptera at the Parque Ecológico de Goiânia, Goiás are studied. An area of 1m² was sampled and abiotic factors were recorded in 4 sites from August/1994 to July/1995. The faunistic composition was 75% Ephemeroptera, 1% Plecoptera and 24% Trichoptera. The data suggest the water velocity and flow as the main factors that determined the aquatic insects abundance.

  20. Distribución de foraminíferos bentónicos (Protozoa: Foraminiferida en la ensenada Quillaipe (41°32' S; 72°44' O, Chile: Implicaciones para el estudio del nivel del mar Distribution of benthic foraminifera (Protozoa: Foraminiferida in the Quillaipe Inlet (41°32' S; 72°44' W, Chile: Implications for sea level studies

    Directory of Open Access Journals (Sweden)

    LEONARDO D FERNÁNDEZ

    2010-12-01

    Full Text Available Los foraminíferos de las marismas salobres son utilizados como indicadores del cambio producido en el nivel del mar durante el Holoceno. No obstante, los foraminíferos de las marismas de Chile han sido escasamente estudiados por lo que se desconoce la factibilidad de utilizarlos para este fin. Para subsanar esto se desarrolló una investigación en el intermareal de la ensenada de Quillaipe, Chile, con los objetivos de determinar los foraminíferos y su distribución vertical; analizar los parámetros que explican su distribución y determinar las especies que son útiles como indicadoras del nivel del mar. Los resultados revelaron 18 especies (nueve aglutinadas y nueve calcáreas distribuidas en dos grandes Zonas (I y II. La Zona I se restringió a la parte más alta y vegetada del intermareal (marisma y estuvo habitada solo por taxa aglutinados. Aquí se registraron bajos valores de diversidad (H' = 0.567, pH (6.6 y salinidad (18.7 y un dominio de la especie aglutinada Haplophragmoides manilaensis. En cambio, la Zona II se limitó a la zona menos elevada y sin vegetación del intermareal (llanura de marea y estuvo habitada por una comunidad calcárea-aglutinada. Contrariamente, los valores de diversidad (H' = 0.909, pH (7.7 y salinidad (32.8 fueron más altos, y la especie dominante fue la calcárea Ammonia beccarii. Por otro lado, la asociación aglutinada Trochamminita salsa-Jadammina macrescens se restringió a la parte más alta de la marisma y a los valores más bajos de salinidad y pH. Estos antecedentes permiten concluir que la distribución de los foraminíferos está controlada por la salinidad, el pH y la elevación del intermareal y que la asociación Trochamminita salsa-Jadammina macrescens son indicadoras del máximo nivel del mar en la ensenada de Quillaipe.Saltmarsh foraminifera are used as indicators of sea-level change which occurs during the Holocene. In Chile however, the saltmarsh foraminifera have been poorly studied, so it is unknown the feasibility of using them for this purpose. To address this issue, a research was conducted in the intertidal Quillaipe Inlet, Chile, in order to determine the vertical distribution of foraminifera and to analyze the parameters that explain their distribution and determine the species that are useful as indicators of sea level. The results revealed 18 species (nine calcareous and nine agglutinated distributed in two zones (I and II. Zone I was restricted to the saltmarsh and inhabited exclusively by agglutinated community. Here, diversity (H' = 0.567, pH (6.6 and salinity (18.7 values were low with a dominance of agglutinated species Haplophragmoides manilaensis. Zone II was restricted to tidal fíat and inhabited by a calcareous-agglutinated community. In contrast, diversity (H' = 0.909, pH (7.7 and salinity (32.8 values were higher, and the dominant species was the calcareous Ammonia beccarii. On the other hand, the agglutinated association Trochamminita salsa-Jadammina macrescens was restricted to the top of the saltmarsh and to low salinity and pH values. We conclude that the distribution of foraminifera is controlled by salinity, pH and the elevation of intertidal área and suggest that Trochamminita salsa-Jadammina macrescens association could be used as indicators of the maximum sea-level in the Quillaipe Inlet.

  1. From antiferroelectricity to ferroelectricity in smectic mesophases ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 61; Issue 2. From antiferroelectricity to ... In this discussion particular attention will be made to polyphilic bent-core molecules, composed of three incompatible units, a bent aromatic core, alkyl chains and an oligosiloxane unit. The importance of the decoupling of the ...

  2. IT-projekter er stadig risikable

    DEFF Research Database (Denmark)

    Harboe, Peter Georg

    2011-01-01

    Anmeldelse af Bent Flyvbjergs artikel i Harvard Business Review "Why your IT-projects may be riskier than you think"......Anmeldelse af Bent Flyvbjergs artikel i Harvard Business Review "Why your IT-projects may be riskier than you think"...

  3. Nitrosyl isomerism in amorphous Mn(TPP)(NO) solids.

    Science.gov (United States)

    Kurtikyan, Tigran S; Hayrapetyan, Vardan A; Martirosyan, Garik G; Ghazaryan, Robert K; Iretskii, Alexei V; Zhao, Hailiang; Pierloot, Kristine; Ford, Peter C

    2012-12-25

    Reaction of NO with amorphous Mn(TPP) layers gives two Mn(TPP)(NO) isomers with linear and bent Mn-N-O geometries that reversibly interconvert with changes in temperature. DFT computations predict that the linear complex is the singlet ground state while the bent structure is a triplet state.

  4. Influence of the chemical modification and content of the clay on the mechanical properties of polypropylene and national bentonite composites

    International Nuclear Information System (INIS)

    Libano, Elaine V.D.G.; Pacheco, Elen B.A.V.; Visconte, Leila L.Y.

    2011-01-01

    The polypropylene/national clay composite was prepared by melt intercalation in a counter-rotating twin screw extruder, using bentonite as filler either in the natural (BENT) form or modified with the ammonium salt, cetyltrimethylammonium chloride (BENT-org). The clay was used in 1, 3 and 5%w. The influence of the modification and content of clay on the mechanical properties of this system was analysed. The analyses of infrared spectroscopy (FTIR) and X-ray diffraction (XRD) showed that clay organophilization did occur. The tensile modulus and the tensile strength at the yield point were not affected by chemical modification (BENT and BENT-org) or clay content. On the other hand, it was evidenced that the elongation at the yield point decreased with the addition of BENT and BENT-org to polypropylene. According to the thermogravimetric results, it was evidenced that the incorporation of clay into polypropylene improved thermal stability of the polymer in the composites with 5%w of BENT and 3 and 5%w of BENT-org. (author)

  5. 77 FR 23547 - Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Columbia River Crossing...

    Science.gov (United States)

    2012-04-19

    ..., using a stacked alignment that would reduce the number of in-water piers in the Columbia River by... bridge would have four or five in-water bents, consisting of one to three drilled shafts. A bent is part... Harbor crossings would be constructed using drilled shafts, rather than impact-driven piles. However, the...

  6. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Using 1.4 GHz ATCA & VLA images with 5.5 GHz ATCA data, we present a sample of 12 bent-tailed galaxies over the 4 deg2 area of the Chandra Deep Field South (CDFS). We find 10 new sources, one of which is possibly the highest red-shift bent-tailed galaxy detected at ∼ 2.

  7. Behavior of Reworked Steel Reinforcement Bars in Reinforced ...

    African Journals Online (AJOL)

    Steel reinforcement bars are a key component in reinforced concrete and are mainly employed to carry tensile stresses since concrete on its own is weak in tension. Sometimes these bars are wrongly bent, straightened and re bent, resulting in the altering of their original characteristics. Some of such steel has been used ...

  8. Organometallic Reactions Development, Mechanistic Studies and Synthetic Applications

    DEFF Research Database (Denmark)

    Dam, Johan Hygum

    of the successful total synthesis of the cyclophane cavicularin, which contains a bent aromatic moiety. The pivotal step in the synthesis embodied a pyrone-alkyne Diels-Alder cycloaddition with CO2-extrusion to deliver the bent aromatic residue. The fourth project involved further development of the conditions...

  9. Drama, drive and sensuous appeal

    DEFF Research Database (Denmark)

    Bonde, Lars Ole

    2002-01-01

    Introduction to Bent Lorentzen and his music, with focus on the piano music. Booklet accomapnying a complete recording of the piano works by Erik Kaltoft......Introduction to Bent Lorentzen and his music, with focus on the piano music. Booklet accomapnying a complete recording of the piano works by Erik Kaltoft...

  10. Classical Dynamics of Triatomic Systems

    Energy Technology Data Exchange (ETDEWEB)

    Parr, Christopher Alan [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    1968-09-05

    The classical equations of motion of some bent triatomic harmonic molecular models are integrated numerically to investigate the assumptions underlying contemporary theories of unimolecular reaction rates. The classical equations of motion of two anharmonic bent triatomic molecular models are integrated numerically. Also, a Sato surface, free of spurious wells, is proposed for the reaction H + DBr.

  11. CHAPTER 1

    African Journals Online (AJOL)

    Dr Olaleye

    abnormality observed was rudimentary tail and secondary abnormalities included bent mid-piece, curved mid-piece, bent tail, curved tail, tail-less head, ... become more beneficial to humans and animals, toxicity assessment of these plants is .... of spermatozoa with rudimentary tails in the Wistar rats administered with the.

  12. Bronze Age Acrobats

    DEFF Research Database (Denmark)

    Iversen, Rune

    2014-01-01

    . The exact same appearance is found on Egyptian depictions related to ceremonies and festivals.OnMinoan Crete backwards-bent acrobats are related to bull leaping and bull ceremonies. Despite local variations, backwards-bent acrobatic performances carried out by topless female actorswere part...

  13. We All Want to Live Longer and Nobody Wants to be Called Old. In: Oldetopia - an Exhibition on Age and Ageing

    DEFF Research Database (Denmark)

    Otto, Lene

    Kataloget bag udstillingen Oldetopia, vist på Medicinsk Museion fra den 12. oktober 2007 til den 14. december 2008. Bidrag af Camilla Mordhorst, Bente Vinge Pedersen, Thomas Söderqvist, Bente Klarlund Pedersen, Mette Sørensen, Tinna Stevnsner, Vilhelm A. Bohr, Bernard Jeune, Liv Carlé Mortensen, ...

  14. Analysis of residual stress and hardness in regions of pre-manufactured and manual bends in fixation plates for maxillary advancement.

    Science.gov (United States)

    Araújo, Marcelo Marotta; Lauria, Andrezza; Mendes, Marcelo Breno Meneses; Claro, Ana Paula Rosifini Alves; Claro, Cristiane Aparecida de Assis; Moreira, Roger William Fernandes

    2015-12-01

    The aim of this study was to analyze, through Vickers hardness test and photoelasticity analysis, pre-bent areas, manually bent areas, and areas without bends of 10-mm advancement pre-bent titanium plates (Leibinger system). The work was divided into three groups: group I-region without bend, group II-region of 90° manual bend, and group III-region of 90° pre-fabricated bends. All the materials were evaluated through hardness analysis by the Vickers hardness test, stress analysis by residual images obtained in a polariscope, and photoelastic analysis by reflection during the manual bending. The data obtained from the hardness tests were statistically analyzed using ANOVA and Tukey's tests at a significance level of 5 %. The pre-bent plate (group III) showed hardness means statistically significantly higher (P < 0.05) than those of the other groups (I-region without bends, II-90° manually bent region). Through the study of photoelastic reflection, it was possible to identify that the stress gradually increased, reaching a pink color (1.81 δ / λ), as the bending was performed. A general analysis of the results showed that the bent plate region of pre-bent titanium presented the best results.

  15. Wire in the Cable-Driven System of Surgical Robot

    Science.gov (United States)

    Wang, X. F.; Lv, N.; Mu, H. Z.; Xue, L. J.

    2017-07-01

    During the evolution of the surgical robot, cable plays an important role. It translates motion and force precisely from surgeon’s hand to the tool’s tips. In the paper, the vertical wires, the composition of cable, are mathematically modeled from a geometric point of view. The cable structure and tension are analyzed according to the characteristics of wire screw twist. The structural equations of the wires in different positions are derived for both non-bent cable and bent cable, respectively. The bending moment formula of bent cable is also obtained. This will help researchers find suitable cable and design more matched pulley.

  16. Attachment for mass exchange apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Maksimenko, M.Z.; Maksimenko, M.M.; Prokopov, O.I.

    1982-01-01

    An attachment is proposed which contains a cylindrical housing in which the windows are profiled with inward bent windows. In order to improve the effectiveness of the attachment by increasing its surface, and mobility, the ends of the housing are equipped with inner annular partitions with radial cross sections. The sections of the partitions between them are bent inwards towards the forming housing in series, from the side of each section. The inward-bent sections of the partitions and the edges are directed to one side or to different sides.

  17. Mosaiikpilte Norramaa köögist / Moonika Siimets

    Index Scriptorium Estoniae

    Siimets, Moonika, 1980-

    2009-01-01

    Norra reisist: Väiketootja Inger Rosenfeldi juustu edust Prantsusmaal, Ameerikas ja Norras; 1993. aasta kokandusolümpia "Bocuse d`Or" võitjast Bent Stiansenist; norralaste toitumisharjumustest; Preikestolen Fjellstue ökomajas asuva turismikeskuse restoranis pakutavatest roogadest.

  18. Hysterosalpingography

    Medline Plus

    Full Text Available ... exam table, with her knees bent or her feet held up with stirrups and a speculum is ... information you were looking for? Yes No Please type your comment or suggestion into the following text ...

  19. Sonohysterography

    Medline Plus

    Full Text Available ... you lying on your back, possibly with your feet in stirrups similar to a gynecologic exam. Doppler ... your back with your knees bent or your feet in stirrups. The cervix will be cleansed, and ...

  20. Afterword (September 2001): The Sharpening Fight for the Future

    National Research Council Canada - National Science Library

    Arquilla, John; Ronfeldt, David

    2001-01-01

    .... The same technology that aids social activists and those desiring the good of all is also available to those with the darkest intentions, bent on destruction and driven by a rage reminiscent of the Middle Ages...

  1. A Study of the Stress Corrosion Susceptibility of Cupro-Nickel and Titanium under Desalination Conditions

    National Research Council Canada - National Science Library

    Orava, R

    1968-01-01

    ... characteristic of those encountered during desalination operations. Bent-beam specimens from sheet and tubing, and C-rings from tubing were exposed at or near the macroscopic yield stress to brackish well water, seawater or sea-salt brines...

  2. Prevention: Exercise

    Medline Plus

    Full Text Available ... for ten seconds, and repeat six times... Side Bridge On your side with knees bent at 90 ... Repeat 1-5 times or to fatigue... Prone Bridge/Plank Prop up onto elbows and knees. Keep ...

  3. Prevention: Exercise

    Medline Plus

    Full Text Available ... building the muscles that provide support for your body. Pilates, yoga and martial arts all provide well- ... knees bent. Use your hips to push your body back to a standing position, then extend your ...

  4. Prevention: Exercise

    Medline Plus

    Full Text Available ... done with quick short movements, or slow full movements. Repeat 10-15 times, to fatigue... Abdominal Exercise Lay on your back with both knees bent. Draw abdominal wall in. Maintaining abdominal wall ...

  5. Pop / Lauri Tikerpe

    Index Scriptorium Estoniae

    Tikerpe, Lauri

    2006-01-01

    Heliplaatidest: Stereotyp "Keepin' Me", Bent "Intercept!", The Mars Volta "Amputechture", X-press 2 "Makeshift Feelgood", Kosmikud "Pulmad ja matused", Beck "The Information", Ursula "Armastan end aeglaselt", Envy "Insomniac Doze", Joe Colley & Jason Lescalleet "Annihilate This Week"

  6. Prostate Ultrasound

    Medline Plus

    Full Text Available ... and to lie on your side with your knees toward your chest. To obtain high-quality images, ... asked to lie on your side with your knees bent. A disposable protective cover is placed over ...

  7. Modified planar functions and their components

    DEFF Research Database (Denmark)

    Anbar Meidl, Nurdagül; Meidl, Wilfried Meidl

    2017-01-01

    functions in odd characteristic as a vectorial bent function. We finally point out that though these components behave somewhat different than the multivariate bent4 functions, they are bent or semibent functions shifted by a certain quadratic term, a property which they share with their multivariate......Zhou ([20]) introduced modified planar functions in order to describe (2n; 2n; 2n; 1) relative difference sets R as a graph of a function on the finite field F2n, and pointed out that projections of R are difference sets that can be described by negabent or bent4 functions, which are Boolean...... functions given in multivariate form. One of the objectives of this paper is to contribute to the understanding of these component functions of modified planar functions. Moreover, we obtain a description of modified planar functions by their components which is similar to that of the classical planar...

  8. A flexible infrared sensor for tissue oximetry

    DEFF Research Database (Denmark)

    Petersen, Søren Dahl; Thyssen, Anders; Engholm, Mathias

    2013-01-01

    integrated in a flexible array. The flexibility is achieved by combining silicon with Polydimethylsiloxane and polyimide using standard IC manufacturing. This ensures that the electrical interconnects on the sensor can withstand being bent in order for the sensor to confine to the curved surface of the head...... of a neonatal. The sensor platform has been tested and is found to be very durable and capable of being both bent to small radii of curvature and strained in the longitudinal direction. The electrical interconnects on the sensor only experience a relative small increase in resistance when the sensor is bent up...... to 90° and they can withstand a longitudinal strain of up to 5% without being damaged. A durability test has shown no fatigue or change in resistance for the electrical interconnects when the sensor had been bent 10,000 times. Two different sizes of photo detectors have been characterized. The smaller...

  9. Prevention: Exercise

    Medline Plus

    Full Text Available ... Tighten your abdominal muscles, then reach through your legs to touch the wall, keeping hips and knees bent. Use your hips to push your body back to a standing position, then extend your arms and reach over ...

  10. Prevention: Exercise

    Medline Plus

    Full Text Available ... movements. Repeat 10-15 times, to fatigue... Abdominal Exercise Lay on your back with both knees bent. ... repetitions at a slow and controlled pace... Resistance Training Resistance training is exercise done against something providing ...

  11. Prevention: Exercise

    Medline Plus

    Full Text Available ... extend one leg (if your abdominal wall lifts up or your back arches, your leg is too ... side with knees bent at 90 degrees, prop up on your elbow, elongate neck away from shoulder, ...

  12. Does body posture during tree felling influence the physiological load of a chainsaw operator?

    Directory of Open Access Journals (Sweden)

    Witold Grzywiński

    2017-09-01

    A working posture during tree felling by chainsaw has influence on the level of physiological workload of an operator. Standing bent forward body postures cause higher heart response than squatting and half-kneeling.

  13. Observation of wave packet dichotomy and adiabatic stabilization in an optical waveguide

    International Nuclear Information System (INIS)

    Longhi, S.; Marangoni, M.; Janner, D.; Ramponi, R.; Laporta, P.; Cianci, E.; Foglietti, V.

    2005-01-01

    We report on the first experimental observation of wave packet dichotomy and adiabatic stabilization of light in a periodically bent optical waveguide in analogy with similar behavior of atoms in high-frequency strong laser fields

  14. Genetics Home Reference: campomelic dysplasia

    Science.gov (United States)

    ... newborn period. The term "campomelic" comes from the Greek words for "bent limb." Affected individuals are typically ... SOX9 gene and occur in people with no history of the disorder in their family. Rarely, affected ...

  15. Sonohysterography

    Medline Plus

    Full Text Available ... knees bent or your feet in stirrups. The cervix will be cleansed, and a catheter will be ... clinical situations. In women with stenosis of the cervix, it may be somewhat difficult to insert the ...

  16. Continuity diaphragm for skewed continuous span precast prestressed concrete girder bridges.

    Science.gov (United States)

    2004-10-01

    Continuity diaphragms used on skewed bents in prestressed girder bridges cause difficulties in detailing and : construction. Details for bridges with large diaphragm skew angles (>30) have not been a problem for LA DOTD. : However, as the skew angl...

  17. [Adsorption Properties of Fluorine onto Fulvic Acid-Bentonite Complex].

    Science.gov (United States)

    Fang, Dun; Tian, Hua-jing; Ye, Xin; He, Ci-li; Dan, You-meng; Wei, Shi-yong

    2016-03-15

    Fulvic Acid-Bentonite (FA-BENT) complex was prepared using coprecipitation method, and basic properties of the complex and sorption properties of fluorine at different environmental conditions were studied. XRD results showed that the d₀₀₁ spacing of FA- BENT complex had no obvious change compared with the raw bentonite, although the diffraction peak intensity of smectite in FA-BENT complex reduced, and indicated that FA mainly existed as a coating on the external surface of bentonite. Some functional groups (such as C==O, −OH, etc. ) of FA were observed in FA-BENT FTIR spectra, thus suggesting ligand exchange-surface complexation between FA and bentonite. Higher initial pH values of the reaction system were in favor of the adsorption of fluorine onto FA-BENT, while the equilibrium capacity decreased with the increase of pH at initial pH ≥ 4.50. The adsorption of fluorine onto FA-BENT was also affected by ionic strength, and the main reason might be the "polarity" effect. The adsorption of fluorine onto FA-BENT followed pseudo-second-order kinetic model and was controlled by chemical process ( R² = 0.999 2). Compared with the Freundlich model, Langmuir model was apparently of a higher goodness of fit (R² > 0.994 9) for absorption of fluorine onto FA-BENT. Thermodynamic parameters indicated that the adsorption process of fluorine was an spontaneously endothermic reaction, and was an entropy-driven process (ΔH 32.57 kJ · mol⁻¹, ΔS 112.31 J · (mol · K)⁻¹, ΔG −0.65- −1.76 kJ · mol⁻¹).

  18. Construction and analysis of cryptographic functions

    CERN Document Server

    Budaghyan, Lilya

    2015-01-01

    This book covers novel research on construction and analysis of optimal cryptographic functions such as almost perfect nonlinear (APN), almost bent (AB), planar and bent functions. These functions have optimal resistance to linear and/or differential attacks, which are the two most powerful attacks on symmetric cryptosystems. Besides cryptographic applications, these functions are significant in many branches of mathematics and information theory including coding theory, combinatorics, commutative algebra, finite geometry, sequence design and quantum information theory. The author analyzes equ

  19. Ultra-relativistic heavy-ion physics with AFTER@LHC

    DEFF Research Database (Denmark)

    Rakotozafindrabe, A.; Arnaldi, R.; Brodsky, Stanley

    2013-01-01

    We outline the opportunities for ultra-relativistic heavy–ion physics which are offered by a next generation and multi-purpose fixed-target experiment exploiting the proton and ion LHC beams extracted by a bent crystal.......We outline the opportunities for ultra-relativistic heavy–ion physics which are offered by a next generation and multi-purpose fixed-target experiment exploiting the proton and ion LHC beams extracted by a bent crystal....

  20. The National Shipbuilding Research Program, Proceedings of the REAPS Technical Symposium (2nd) held in Palm Beach Shores, Florida, on 24-25 Jun 1975: Full Proceedings

    Science.gov (United States)

    1975-06-01

    calculated to minimize cumulative bent to this aim position, section can then be rebent the springback is iteratively based error, the beam is measured...the new springback estimate unless the beam was already bent too far. Finally, the beam is fed until the reference point on the beam stops within the...COMPUTER OPERATING SYSTEM PROBLEM: USE ADDITIONAL SHEETS IF NECESSARY ENCLOSURES: ❑ LISTING ❑ SOURCE DEcK ❑ OTHER DATE I SIGNED: NOTES : () [f the area of

  1. Equipment for radioactive logging

    International Nuclear Information System (INIS)

    Meier, V.A.

    1974-01-01

    Equipment is described featuring a means for the mechanical connection of a transmitting probe to the electronic supply unit which consists of a flexible rod which may only be bent in a single plane. The transmitting probe is pressed against the borehole wall by a spring attached to the probe whose longitudinal axis is in the same plane in which the rod may be bent. (B.S.)

  2. Industrial Protection Manual.

    Science.gov (United States)

    1981-06-01

    bent; instruments decalibrated. 3. Moderate to heav damage: Faces of panels bent/buckled 4 2 2 24 4 with corresponding damage to elec. components...unbacked re- 2 1 2 8 1 fractory heavily damaged; other refractory cracked; accessories damaged; panels & covers damage components 3. Moderate to heav ...contd) Keyseating machine Lapping machine Lathe Milling machines Nipple threading machine Numerically control led Pivot polishing machine Planers Presses

  3. Spin rotation and oscillations for high energy particles in a crystal and possibility to measure the quadrupole moments and tensor polarizabilities of elementary particles and nuclei

    OpenAIRE

    Baryshevsky, V. G.; Gurinovich, A. A.

    2005-01-01

    It is shown that particle motion in a bent (straight) crystal is accompanied by particle spin rotation and oscillations that allows to measure the tensor electric and magnetic polarizabilities of nuclei and elementary particles. It is shown that channelling of particles in either straight or bent crystal with the polarized nuclei could be used both to analyze polarization of high energy particles and polarize them.

  4. The Effect of Contouring on Fatigue Strength of Spinal Rods: Is it Okay to Re-bend and Which Materials Are Best?

    Science.gov (United States)

    Slivka, Michael A; Fan, Yung K; Eck, Jason C

    2013-11-01

    Small-diameter spinal rods were tested in fatigue loading before and after contouring in pedicle screw constructs using dynamic testing machines. To characterize the change in fatigue performance of spinal rods resulting from contouring. Spine surgeons have a variety of rod materials to choose from, and selecting the best rod depends on patient characteristics and rod material properties, including fatigue performance. Four rod materials were tested, all 4.5 mm in diameter: titanium alloy (Ti), cobalt-chromium alloy (CoCr), and 2 different grades of stainless steel (SS and ultra SS). Three conditions were tested: straight (virgin rods), bent (rods bent to a radius of curvature of 100 mm), and re-bent (rods over-bent to a radius of 50 mm, then partially straightened to a 100-mm radius). Fatigue testing was conducted on unilateral vertebrectomy constructs with polyaxial screws. In all conditions, the endurance limit of the CoCr rods was at least 25% higher than the other materials but could not be determined because screw failure precluded rod failure. In the bent condition, the endurance limits of Ti, standard SS and ultra SS were reduced between 20% and 40%. In the re-bent condition, the endurance limit of Ti, standard SS, and ultra SS increased compared with the bent condition. Changes in fatigue performance are best explained by residual rod stresses induced during contouring. It appears safe to over-bend and then re-bend, for 1 cycle, small-diameter spinal rods made of the materials tested in this study using tube benders, and CoCr rods were clearly superior for all conditions. However, larger rods, multiple cycles of bending and re-bending, and rods bent using other instruments such as French benders were not studied and may result in different performance under the same conditions. Copyright © 2013 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.

  5. Towards a male-only release system for SIT with the Queensland fruit fly, Bactrocera tryoni, using a genetic sexing strain with a temperature-sensitive lethal mutation.

    Science.gov (United States)

    Meats, A; Maheswaran, P; Frommer, M; Sved, J

    2002-09-01

    Flies that are homozygous for the recessive autosomal mutation bent wings have a limited ability to fly and are less tolerant of high temperatures than normal flies in both the egg and puparial stages. The differences between the mutant and normal flies were found sufficient to be the basis of a genetic sexing strain. Genetic sexing strains were created using translocations of the autosome bearing the wild-type allele of bent wings (chromosome 2) to the Y chromosome, and crossing male flies carrying the translocation to mutant bent wings females. In the resulting strain, the females were homozygous for the bent wings mutation and the males were phenotypically normal for wing characters. Several translocations were recovered after irradiation, but only one translocation involving chromosome 2 was both stable and expressed in a stock that was vigorous enough for long-term viability. Unfortunately, all stocks containing the translocation showed high levels of temperature-dependent lethality, including, inexplicably, both males and females. Translocation stocks showing this effect included bent wings, another second chromosome mutation, white marks, and an otherwise normal stock. This phenomenon is probably rare, as it has not been reported before. It is likely that bent wings could be suitably used with another translocation.

  6. Crystals in the LHC

    CERN Multimedia

    Antonella Del Rosso

    2012-01-01

    Bent crystals can be used to deflect charged particle beams. Their use in high-energy accelerators has been investigated for almost 40 years. Recently, a bent crystal was irradiated for the first time in the HiRadMat facility with an extreme particle flux, which crystals would have to withstand in the LHC. The results were very encouraging and confirmed that this technology could play a major role in increasing the beam collimation performance in future upgrades of the machine.   UA9 bent crystal tested with a laser. Charged particles interacting with a bent crystal can be trapped in channelling states and deflected by the atomic planes of the crystal lattice (see box). The use of bent crystals for beam manipulation in particle accelerators is a concept that has been well-assessed. Over the last three decades, a large number of experimental findings have contributed to furthering our knowledge and improving our ability to control crystal-particle interactions. In modern hadron colliders, su...

  7. Does body posture during tree felling influence the physiological load of a chainsaw operator?

    Science.gov (United States)

    Grzywiński, Witold; Jelonek, Tomasz; Tomczak, Arkadiusz; Jakubowski, Marcin; Bembenek, Mariusz

    2017-09-21

    Holding determined body postures during work is connected with muscles activity. The more forced the posture, the larger the number of muscles taking an active part in holding and stabilizing the work posture. During logging, the greatest share of awkward (forced) working postures occurs in tree felling by chainsaw. A group of 10 experienced fellers aged 47.5±7.3 (37 - 59-years-old) was studied. Heart rate (HR) was measured during simulation of felling activity in 4 working postures: back bent forward with straight legs (stoop), back bent forward with bent legs (flexed-stoop), squat and kneeling on one knee (half-kneel). The lowest value of HR was noticed for squatting - 114.1 bpm, then for kneeling on one knee - 116.3 bpm. HR during felling in a standing posture with straight legs amounted to 121.5 bpm and for standing with bent legs 125.3 bpm. For all studied postures the differences in average HR values were statistically significant at pposture during tree felling by chainsaw has influence on the level of physiological workload of an operator. Standing bent forward body postures cause higher heart response than squatting and half-kneeling.

  8. Observation of channeling for 6500 GeV/c protons in the crystal assisted collimation setup for LHC

    Directory of Open Access Journals (Sweden)

    W. Scandale

    2016-07-01

    Full Text Available Two high-accuracy goniometers equipped with two bent silicon crystals were installed in the betatron cleaning insertion of the CERN Large Hadron Collider (LHC during its long shutdown. First beam tests were recently performed at the LHC with 450 GeV/c and 6500 GeV/c stored proton beams to investigate the feasibility of beam halo collimation assisted by bent crystals. For the first time channeling of 6500 GeV/c protons was observed in a particle accelerator. A strong reduction of beam losses due to nuclear inelastic interactions in the aligned crystal in comparison with its amorphous orientation was detected. The loss reduction value was about 24. Thus, the results show that deflection of particles by a bent crystal due to channeling is effective for this record particle energy.

  9. Multivariate Generalized Linear Mixed Models with High Complexity / Modèles linéaires généralisés mixtes multivariés avec complexité élevée

    DEFF Research Database (Denmark)

    Labouriau, Rodrigo

    The theory of exponential dispersion models (EDM), for which Bent Jørgensen made substantial contributions, provides a flexible framework of models alternative to the classic Gaussian linear models (e.g. generalized linear models and additive models). I review some multivariate extensions of those...... models that allow the distribution of the different dimensions to belong to different EDMs. As an illustration, I present some applications in quantitative genetics with high complexity (several hundreds of thousand observations and deep pedigrees). In all the presented applications, it is crucial...... to understand the underlying stochastic process related to the EDMs used to represent well and interpret biological questions of interest. Bent Jørgensen advocated similar ideas in his work since the 1980s. La théorie des modèles de dispersion exponentielle (EDM), à laquelle Bent Jørgensen a apporté d...

  10. Combined rotor fault diagnosis in rotating machinery using empirical mode decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Sukhjeet; Kumar, Navin [Indian Institute of Technology, Ropar Rupnagar (India)

    2014-12-15

    Unbalance, misalignment, partial rub, looseness and bent rotor are one of the most commonly observed faults in rotating machines. These faults cause breakdowns in rotating machinery and create undesired vibrations while operating. In this study, an approach to detect combined fault of unbalance and bent rotors for advance detection of the features of the fault rotors diagnosis is proposed. Empirical mode decomposition (EMD) is used efficiently to decompose the complex vibration signals of rotating machinery into a known number of intrinsic mode functions so that the fault characteristics of the unbalanced and bowed shaft can be examined in the time-frequency Hilbert spectrum. A test bench of Spectra-Quest has been used for performing experiments to illustrate the unbalance and the bent rotor conditions as well as the healthy rotor condition. Analysis of the results shows the usefulness of proposed approach in diagnosing the unbalance and bowed fault of the shaft in rotating machinery.

  11. Focusing Optics for High-Energy X-ray Diffraction

    DEFF Research Database (Denmark)

    Leinert, U.; Schulze, C.; Honkimäki, V.

    1998-01-01

    Novel focusing optical devices have been developed for synchrotron radiation in the energy range 40-100 keV. Firstly, a narrow-band-pass focusing energy-tuneable fixed-exit monochromator was constructed by combining meridionally bent Laue and Bragg crystals. Dispersion compensation was applied...... to retain the high momentum resolution despite the beam divergence caused by the focusing. Next, microfocusing was achieved by a bent multilayer arranged behind the crystal monochromator and alternatively by a bent Laue crystal. A 1.2 mu m-high line focus was obtained at 90 keV. The properties...... of the different set-ups are described and potential applications are discussed. First experiments were performed, investigating with high spatial resolution the residual strain gradients in layered polycrystalline materials. The results underline that focused high-energy synchrotron radiation can provide unique...

  12. Contribution to the measurement of the reflection coefficient for curved crystals between 50 and 80 keV

    International Nuclear Information System (INIS)

    Chartier, J.

    1968-09-01

    In the first part, we summarize the main approximate theories dealing with the diffraction of electromagnetic radiation by the crystalline medium, allowing the determination of the characteristic properties of flat and bent crystals used in X and gamma-Ray spectroscopy ('Laue Case'). We describe the experimental setting and we explain our method to measure Γ: reflectivity of elastically or plastically bent-crystals from narrow wave-length intervals in the continuous X-Ray spectrum. We discuss our experimental results obtained with different crystals (quartz (3140), Al (200), FLi (200) and compare them with theoretical ones. Finally, we refer to a use of the bent-crystal spectrometer (Cauchois arrangement) in dosimetry. (author) [fr

  13. Controlling charges distribution at the surface of a single GaN nanowire by in-situ strain

    Directory of Open Access Journals (Sweden)

    Xiao Chen

    2017-08-01

    Full Text Available Effect of the strain on the charge distribution at the surface of a GaN semiconductor nanowire (NW has been investigated inside transmission electron microscope (TEM by in-situ off-axis electron holography. The outer and inner surfaces of the NW bent axially under compression of two Au electrodes were differently strained, resulting in difference of their Fermi levels. Consequently, the free electrons flow from the high Fermi level to the low level until the two Fermi levels aligned in a line. The potential distributions induced by charge redistribution in the two vacuum sides of the bent NW were examined respectively, and the opposite nature of the bounded charges on the outer and inner surfaces of the bent NW was identified. The results provide experimental evidence that the charge distribution at the surfaces of a single GaN NW can be controlled by different strains created along the NW.

  14. Storhedsvanvid

    DEFF Research Database (Denmark)

    Flyvbjerg, Bent

    2007-01-01

    Manchet: Bent Flyvbjerg er professor i planlægning ved Aalborg Universitets Institut for Samfundsudvikling og Planlægning. Han forsvarer i dag sin anden doktorafhandling. Forsvaret kan følges på websitet video.ikt.hum.aau.dk/uploads/media/AAU.asx fra kl. 13.00.......Manchet: Bent Flyvbjerg er professor i planlægning ved Aalborg Universitets Institut for Samfundsudvikling og Planlægning. Han forsvarer i dag sin anden doktorafhandling. Forsvaret kan følges på websitet video.ikt.hum.aau.dk/uploads/media/AAU.asx fra kl. 13.00....

  15. The past, present, and future of hockey-stick-shaped liquid crystals

    Science.gov (United States)

    Choi, E.-Joon

    2014-02-01

    Recently, the liquid crystalline materials with a bent-core mesogen have attracted attentions because their interesting properties such as polarity and biaxiality of the mesophase. There are several types of bent-core mesogenic structures have been reported, for instance, banana-shaped, V-shaped molecules, boomerang-shaped, hockey stick-shaped, and Yshaped molecules. In this study, the liquid crystals and the reactive mesogens with the hockey-stick shaped mesogens will be described concerning with the structure-property relationship.

  16. Fra forskningens forfront

    DEFF Research Database (Denmark)

    Jørgensen, Bent

    2005-01-01

    Sudoku-bølgen er også skyllet ind over landets højere læreanstalter. Således skriver professor Bent Jørgensen, Forskningsenheden for Statistik ved Syddansk Universitet, Odense, at sudokuen skam anvendes inden for forskningens absolutte forfront.......Sudoku-bølgen er også skyllet ind over landets højere læreanstalter. Således skriver professor Bent Jørgensen, Forskningsenheden for Statistik ved Syddansk Universitet, Odense, at sudokuen skam anvendes inden for forskningens absolutte forfront....

  17. Historisierung der Energiefrage

    DEFF Research Database (Denmark)

    Czeskleba-Dupont, Rolf

    2014-01-01

    Anmeldelse af prof.em.Bent Sørensens bog, der præsenterer energiregnskaber fra Neanderthalerne til vor tid inden for det geografiske område, som Danmark dækker/har dækket. Bidrag til et kommende fag energi-historie.......Anmeldelse af prof.em.Bent Sørensens bog, der præsenterer energiregnskaber fra Neanderthalerne til vor tid inden for det geografiske område, som Danmark dækker/har dækket. Bidrag til et kommende fag energi-historie....

  18. Crystal Deflectors for High Energy Ion Beams

    CERN Document Server

    Scandale, W

    2013-01-01

    The motion of charged particles entering a crystal at small angles with respect to a crystalline plane is strongly influenced by the average electric field of the ordered nuclei. For sufficiently small angles the particles can be captured in channeling states, thus performing quasi-harmonic oscillations in the potential well between the crystal planes. Channeled particles in a bent crystal are deflected along the bent planes of the crystal. This provides a powerful method to steer and control particle trajectories that has been investigated and occasionally exploited for some decades already.

  19. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    Energy Technology Data Exchange (ETDEWEB)

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2005-06-22

    An area planted in 2004 on Bent Mountain in Pike County was shifted to the Department of Energy project to centralize an area to become a demonstration site. An additional 98.3 acres were planted on Peabody lands in western Kentucky and Bent Mountain to bring the total area under study by this project to 556.5 acres as indicated in Table 2. Major efforts this quarter include the implementation of new plots that will examine the influence of differing geologic material on tree growth and survival, water quality and quantity and carbon sequestration. Normal monitoring and maintenance was conducted and additional instrumentation was installed to monitor the new areas planted.

  20. Power Production and Economical Feasibility of Tideng Tidal Stream Power Converter

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Frigaard, Peter; Kofoed, Jens Peter

    This report is a product of the contract between Aalborg University and TIDENG (by Bent Hilleke) on the evaluation and development of the TIDENG Tidal Energy Conversion System (TECS). The work has focused on the evaluation of the yearly power production of the device and its economical feasibility...

  1. SERPUKHOV: Focusing particles by a crystal

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    With several Laboratories having shown how bent crystals can be used to steer particle beams, a team working at the Institute for High Energy Physics (IHEP) at Serpukhov, near Moscow, has shown how these crystals can also be used to focus particle beams

  2. Disciplinary Identity as Analytic Construct and Design Goal: Making Learning Sciences Matter

    Science.gov (United States)

    Carlone, Heidi B.

    2017-01-01

    Bent Flyvbjerg (2001), in his book "Making Social Science Matter: Why Social Inquiry Fails and How It Can Succeed Again," argues that social science's aims and methods are currently, and perhaps always will be, ill suited to the type of cumulative and predictive theory that characterizes inquiry and knowledge generation in the natural…

  3. Cooper’s hawk nest site characteristics in the Pineywoods Region

    Science.gov (United States)

    Richard R. Schaefer; D. Craig Rudolph; Jesse F. Fagan

    2011-01-01

    Early accounts describe the Cooper’s Hawk (Accipiter cooperi) as a species in decline in much of North America during the early twentieth century (Bent 1937), particularly when in close proximity to humans (Eaton 1914). This decreasing population trend continued to be recognized later in the century in both Texas (Oberholser 1974) and Louisiana (Lowery 1974). Shooting...

  4. Tris-Ala -NHMe

    African Journals Online (AJOL)

    NICO

    The 50 ns MD trajectories revealed a tendency of the trishomocubane polypeptide to adopt bent conformations in .... 2a and 2b, respectively), where the conformational space of TRIS residue was found to be well explored, confirming ... analysis of the secondary motifs was performed. For this purpose we used the CLASICO ...

  5. Female-pitched sound-producing voice prostheses - initial experimental and clinical results

    NARCIS (Netherlands)

    van der Torn, M; Verdonck-de Leeuw, IM; Festen, JM; de Vries, MP; Mahieu, HF

    2001-01-01

    In order to improve voice quality in female laryngectomees and/or laryngectomees with a hypotonic pharyngo-oesophageal segment, a sound-producing voice prosthesis was designed. The new source of voice consists of either one or two bent silicone lips which perform an oscillatory movement driven by

  6. Multiple reflections (MRs) - a new challenge for high-resolution neutron diffractometry and spectrometry

    Czech Academy of Sciences Publication Activity Database

    Mikula, Pavol; Vrána, Miroslav; Wagner, V.; Furusaka, M.

    2008-01-01

    Roč. 586, č. 1 (2008), s. 18-22 ISSN 0168-9002. [European Workshop on Neutron Optics (NOP 07). Villigen, 05.03.2007-07.03.2007] Institutional research plan: CEZ:AV0Z10480505 Keywords : neutron scattering * Bragg diffraction optics * bent perfect crystal Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.019, year: 2008

  7. Hyggeligt, men lavt til loftet, eller er det plat at have det godt

    DEFF Research Database (Denmark)

    Klausen, Søren Harnow

    2010-01-01

    Undersøger hvordan forskellige litterære fremstillinger - bl.a. hos Tage Skou-Hansen, Bent Vinn Nielsen, George Eliot og Virginia Woolf - kan være med til at kvalificere diskussionen om velfærdsstaten....

  8. An evaluation of the hardwood regeneration model (REGEN) 16 years post-harvest of a regenerated stand in East Tennessee

    Science.gov (United States)

    Wayne K. Clatterbuck

    2015-01-01

    The REGEN model (developed by USDA Forest Service, Southern Research Station, Bent Creek Experimental Forest) was used prior to harvest to predict species composition of hardwoods at crown closure. This study evaluates whether the predictive ability of the model was effective by using post-harvest information after 16 years. Regeneration data were collected prior to...

  9. Calcined eggshell (CES): An efficient natural catalyst for ...

    Indian Academy of Sciences (India)

    percentage of calcium carbonate, nearly about 94%.21. Waste eggshells have been utilized as humidity adsor- bent,22 as an adsorbent in the removal of chromium from its aqueous solution,23 and also as a low cost solid catalyst for biodiesel production,24 as a catalyst for lactose isomerization to lactulose.25 Being a natu-.

  10. Sadhana | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Mechanical properties of specimens were measured by means of compression testing, based on the concept of nominal stress, using a universal testing machine and special grips that were constructed for this purpose. pp 537-541. Dynamic stability of a curved pipe bent in the arc of a circle on hinge supports at the ends.

  11. Modernism in School Reform: Promoting Private over Public Good

    Science.gov (United States)

    Nordgren, R. D.

    2016-01-01

    School reform in the past several decades has taken a "modernist" bent in that it has focused on quantitatively based accountability systems modeled after business (Ravitch, 2013; Tienken & Orlich, 2013). The author uses a model devised by a Finnish scholar to demonstrate that 1) these reforms are indeed modernist, and 2) the private…

  12. The Ethnic Primordialist-Constructivist/Instrumentalist Debate, and ...

    African Journals Online (AJOL)

    This study claims that the traditionally different understandings of ethnicity by the primordialists and the constructivists/instrumentalists foster the politics of disjunction, the divisionist bent that undermines the common cultivation of the ethos of national integration in Nigeria. The primordialists take the so-called ethnic groups ...

  13. Bacterial Community of Leaehate from a Waste—Dump and an ...

    African Journals Online (AJOL)

    sample was aseptically transferred onto freshly prepared nutrient agar plates and spread with a sterile bent glass rod. The inoculated plates were inverted ... Coagulase, Sugar fermentation, Motility, Methyl red,. Voges Proskauer, lndole and Citrate utilization. The pure cultures of bacterial isolates were identified on the basis ...

  14. Photoelastic stress analysis in mitred bend under internal pressure

    International Nuclear Information System (INIS)

    Sawa, Yoshiaki

    1987-01-01

    The stress analysis and stress relaxation in mitred bend subjected to internal pressure have been studied by means of the photoelastic stress freezing method. The experimental results show that stress concentration occurs in the wedge tip of the intersectional plane and it is considerably influenced by the bent angle. Then, the stress relaxation was obtained by planing the wedge tip. (author)

  15. Still Battling the Surf: Teaching English after 100 Years

    Science.gov (United States)

    Goering, Christian Z.

    2012-01-01

    In this article, the author reflects on on his role in preparing English teachers. Leading into his twelfth year concerned with the art and science of teaching English, he wondered what exactly he could say or do to help them stick their toes in some uncertain waters. What could he say of an educational context bent on holding people--different by…

  16. Dynamic Weighted Data Structures.

    Science.gov (United States)

    1982-06-01

    and Bonnie Hampton, who taught me much more than how to play the cello. Finally, for hours of artistic satisfaction, I thank Johannes Brahms , Ludwig...van "j Beethoven, Igor Stravinsky, Glan-Carlo Menotti, and Johann Sebastian Bach. Dynamic Weighted Data Structures Samuel W. Bent This thesis discusses

  17. Decay of Hoyle state

    Indian Academy of Sciences (India)

    2014-11-02

    Nov 2, 2014 ... Hoyle state also, there is discrepancy between various model predictions [18]; whereas. FMD predicts a compact triangle shape and LEFT predicts a bent arm chain structure,. BEC model predicts the Hoyle state to be spherically symmetric. Moreover, the r.m.s. radii of the Hoyle state, predicted by the above ...

  18. 49 CFR Appendix B to Part 215 - Schedule of Civil Penalties 1

    Science.gov (United States)

    2010-10-01

    ... outer springs 5,000 7,500 (e) Truck bolster-center plate interference 5,000 7,500 (f) Brake beam shelf... couplers: (a) Shank bent out of alignment 1,000 2,000 (b) Crack in highly stressed junction area. 2,500 5...

  19. Interplay of nonlinearity and geometry in a DNA-related, Klein-Gordon model with long-range dipole-dipole interaction

    DEFF Research Database (Denmark)

    Archilla, J. F.R.; Christiansen, Peter Leth; Gaididei, Yuri Borisovich

    2002-01-01

    Most of the studies on mathematical models of DNA are limited to next neighbor interaction. However, the coupling between base pairs is thought to be caused by dipole interaction, and, when the DNA strand is bent, the distances between base pairs become shorter, therefore the interactions with di...

  20. Moby-Dick

    NARCIS (Netherlands)

    Melville, Herman

    2005-01-01

    On board the whaling ship Pequod a crew of wise men and fools, renegades and seeming phantoms is hurled through treacherous seas by a crazed captain hell-bent on hunting down the mythic White Whale. Melville transforms the little world of the whale-ship into a crucible where mankind's fears, faith