WorldWideScience

Sample records for bents

  1. 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...

  2. 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....

  3. 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

  4. 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...

  5. 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.

  6. 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

  7. On bent and semi-bent quadratic Boolean functions

    DEFF Research Database (Denmark)

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

    2005-01-01

    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 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...

  8. Bent Electro-Absorption Modulator

    DEFF Research Database (Denmark)

    2002-01-01

    by applying a variable electric or electronmagnetic field. The modulation of the complex refractive index results in a modulation of the refractive index contrast and the absorption coefficient for the waveguide at the frequency of the light. By carefully adjusting the composition of the semiconducting...... 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......The present invention relates to a method and a device for modulating optical signals based on modulating bending losses in bend, quantum well semiconductor waveguide sections. The complex refractive index of the optical active semiconducting components of the waveguide section is modulated...

  9. 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...

  10. Bent's Old Fort: Amphibians and Reptiles

    Science.gov (United States)

    Muths, E.

    2008-01-01

    Bent's Old Fort National Historic Site sits along the Arkansas River in the semi-desert prairie of southeastern Colorado. The USGS provided assistance in designing surveys to assess the variety of herpetofauna (amphibians and reptiles) resident at this site. This brochure is the results of those efforts and provides visitors with information on what frogs, toads, snakes and salamanders might be seen and heard at Bent's Old Fort.

  11. 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.

  12. 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

  13. 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.

  14. 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.

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

    DEFF Research Database (Denmark)

    Anbar Meidl, Nurdagül; Meidl, Wilfried

    2017-01-01

    For c is an element of F(2)n, a c-bent4 function f from the finite field F(2)n to F-2 is a function with a fiat spectrum with respect to the unitary transform V-f(c), which is designed to describe the component functions of modified planar functions. For c = 0 the transform V-f(c) reduces to the ...... 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....

  16. Intrinsically bent DNA in replication origins and gene promoters.

    Science.gov (United States)

    Gimenes, F; Takeda, K I; Fiorini, A; Gouveia, F S; Fernandez, M A

    2008-06-24

    Intrinsically bent DNA is an alternative conformation of the DNA molecule caused by the presence of dA/dT tracts, 2 to 6 bp long, in a helical turn phase DNA or with multiple intervals of 10 to 11 bp. Other than flexibility, intrinsic bending sites induce DNA curvature in particular chromosome regions such as replication origins and promoters. Intrinsically bent DNA sites are important in initiating DNA replication, and are sometimes found near to regions associated with the nuclear matrix. Many methods have been developed to localize bent sites, for example, circular permutation, computational analysis, and atomic force microscopy. This review discusses intrinsically bent DNA sites associated with replication origins and gene promoter regions in prokaryote and eukaryote cells. We also describe methods for identifying bent DNA sites for circular permutation and computational analysis.

  17. The relative cost of bent-hip bent-knee walking is reduced in water.

    Science.gov (United States)

    Kuliukas, Algis V; Milne, Nick; Fournier, Paul

    2009-01-01

    The debate about how early hominids walked may be characterised as two competing hypotheses: They moved with a fully upright (FU) gait, like modern humans, or with a bent-hip, bent-knee (BK) gait, like apes. Both have assumed that this bipedalism was almost exclusively on land, in trees or a combination of the two. Recent findings favoured the FU hypothesis by showing that the BK gait is 50-60% more energetically costly than a FU human gait on land. We confirm these findings but show that in water this cost differential is markedly reduced, especially in deeper water, at slower speeds and with greater knee flexion. These data suggest that the controversy about australopithecine locomotion may be eased if it is assumed that wading was a component of their locomotor repertoire and supports the idea that shallow water might have been an environment favourable to the evolution of early forms of "non-optimal" hominid bipedalism.

  18. Deposition of aerosol particles in bent pipe

    International Nuclear Information System (INIS)

    Matsui, Hiroshi; Ohhata, Tsutomu

    1989-01-01

    An equation to estimate deposition fraction of aerosol particles in a bent pipe is derived and the validity is verified experimentally. The equation is obtained by assuming that the resultant acceleration of the gravity and the centrifugal force induced in the bend acts on the aerosol particles, and is found to give a relatively accurate estimation of the deposition fraction if a certain correction factor is introduced to the equation. The deposition fraction has a minimum against Reynold number, and the deposition due to centrifugal force dominates at greater Reynolds number than that at the minimum deposition fraction. On the other hand, the smaller the radius of curvature of the bend is, the larger the deposition fraction due to the centrifugal force is. (author)

  19. Bent solenoids for spectrometers and emittance exchange sections

    International Nuclear Information System (INIS)

    Norem, J.

    1999-01-01

    Bent solenoids can be used to transport low energy beams as they provide both confinement and dispersion of particle orbits. Solenoids are being considered both as emittance exchange sections and spectrometers in the muon cooling system as part of the study of the muon collider. They present the results of a study of bent solenoids which considers the design of coupling sections between bent solenoids to straight solenoids, drift compensation fields, aberrations, and factors relating to the construction, such as field ripple, stored energy, coil forces and field errors

  20. 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...

  1. Further Results on Constructions of Generalized Bent Boolean Functions

    Science.gov (United States)

    2016-03-01

    China; 2Naval Postgraduate School, Applied Mathematics Department, Monterey, CA 93943, USA; 3Science and Technology on Communication Security...in 1976 as an interesting combinatorial object with the important property of having op- timal nonlinearity [1]. Since bent functions have many...77–94 10 Zhao Y, Li H L. On bent functions with some symmet- ric properties. Discret Appl Math, 2006, 154: 2537– 2543

  2. Channeling and radiation in periodically bent crystals

    Energy Technology Data Exchange (ETDEWEB)

    Korol, Andrey V.; Solov' yov, Andrey V.; Greiner, Walter [Frankfurt Univ. (Germany). Frankfurt Institute for Advanced Studies (FIAS)

    2013-08-01

    Authored by leading experts in the field. Self-contained introduction to the subject matter. Suitable as graduate text on the topic. 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 focus is on the radiation formed in a Crystalline Undulator, where electromagnetic radiation is generated by a bunch of ultra-relativistic particles channeling through a periodically bent crystalline structure. It is shown that under certain conditions, such a device emits intensive spontaneous monochromatic radiation and may even reach the coherence of laser light sources. Readers will be presented with the underlying fundamental physics and be familiarized with the theoretical, experimental and technological advances made during the last one and a half decades in exploring the various features of investigations into crystalline undulators. This research draws upon knowledge from many research fields - such as materials science, beam physics, the physics of radiation, solid state physics and acoustics, to name but a few. Accordingly, much care has been taken by the authors to make the book as self-contained as possible in this respect, so as to also provide a useful introduction to this emerging field to a broad readership of researchers and scientist with

  3. Dispersion in a bent-solenoid channel with symmetric focusing

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chun-xi [Argonne National Lab. (ANL), Argonne, IL (United States)

    2001-08-21

    Longitudinal ionization cooling of a muon beam is essential for muon colliders and will be useful for neutrino factories. Bent-solenoid channels with symmetric focusing has been considered for beam focusing and for generating the required dispersion in the ``emittance exchange'' scheme of longitudinal cooling. In this paper, we derive the Hamiltonian that governs the linear beam dynamics of a bent-solenoid channel, solve the single-particle dynamics, and give equations for determining the lattice functions, in particular, the dispersion functions.

  4. Precast, Prestressed Concrete Bent Caps : Volume 2, Design Recommendations and Design Examples

    Science.gov (United States)

    2018-04-01

    Recommendations for design of pretensioned bent caps are developed based on the findings of full-scale experimental tests of bent cap subassemblages. Companion examples are provided to demonstrate implementation of the design recommendations. First, ...

  5. 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...

  6. Covalent Attachment of Bent-Core Mesogens to Silicon Surfaces

    NARCIS (Netherlands)

    Scheres, L.; Achten, R.; Giesbers, M.; Smet, de L.; Arafat, A.; Sudhölter, E.J.R.; Marcelis, A.T.M.; Zuilhof, H.

    2009-01-01

    Two vinyl-terminated bent core-shaped liquid crystalline molecules that exhibit thermotropic antiferroelectric SmCPA phases have been covalently attached onto a hydrogen-terminated silicon(111) surface. The surface attachment was achieved via a mild procedure from a mesitylene solution, using

  7. Study of channeling phenomena in bent crystals the new frontiers

    CERN Document Server

    Bolognini, Davide; Scandale, Walter; Vallazza, Erik

    2008-01-01

    More or less 30 years ago, it was experimentally demonstrated how a bent crystal can become a magnet: an object 1 mm thick, a couple of mm wide and a few cm high is, in fact, capable of steering particles as a dipole of several tens of Tesla. Exploiting this feature, from September 2006 the H8RD22 collaboration is testing several bent crystals in order to develop a crystal based collimation system for LHC: in very high energy accelerators, in fact, the typical multi-stage collimation system (that must be very efficient and must tolerate very high radiation) is expected not to allow to reach the nominal luminosity, limiting it to 40% of the desired value. A bent crystal could play a key role being a clever collimator: it is able to steer particles in a given direction with a high efficiency, thus increasing the cleaning efficiency, reducing the constraints on the alignment of the secondary collimator and finally increasing luminosity. But bent crystals are not only collimation: the radiation emitted by light p...

  8. 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.

  9. 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

  10. 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.

  11. New concept of the buildup factor in bent ducts

    International Nuclear Information System (INIS)

    Faik Ouahab, Z.; Jehouani, A.; Groetz, J.-E.

    2011-01-01

    A major problem confronting the radiation shielding designer is the accurate determination of neutron streaming through various penetrations in walls, ducts and mazes. The previous studies on neutron transmission were performed through empty ducts. The aim of this work is to evaluate the neutron transmission probability through a filled bent duct and the proposition of a new concept of the buildup factor for neutrons in multilegged ducts. An angular biaising technique is used in the Monte Carlo simulations to accelerate the calculation convergence. Results are first compared with those obtained by the MCNPX code. For an empty bent duct, the neutron transmission is only due to the neutron reflection on the duct wall. For a filled duct, the major contribution is due to the scattering on the atoms filling the duct.

  12. 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.

  13. Motion of channeling particles in a bent crystal

    International Nuclear Information System (INIS)

    Avakian, A.R.; Harutyunian, A.S.; Hovanessian, A.G.; Shahinian, S.M.; Yang, C.

    1990-01-01

    The motion of high-energy charged particles in a bent crystal is investigated in the approximation of the model of continuous potential of crystallographic planes and with account of incoherent scattering on the atoms of media. Angular distribution of charged particle beams is investigated at the exit of the bent region of the crystal in dependence with the maximum deflection angle and energy of particles. The dependence of the fraction of channeling particles on crystal thickness, crystal curvature and particle energy is found in a simple model approximation. The influence of crystal curvature on incoherent scattering of particles in the crystal is analyzed. The concept of an optimal thickness for the maximum number of particles deflected at a given angle is considered. 8 refs.; 8 figs

  14. 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

  15. 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.

  16. 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

  17. Volume reflection efficiency for negative particles in bent crystals

    Energy Technology Data Exchange (ETDEWEB)

    Biryukov, V.M., E-mail: valery.biryukov@ihep.ru

    2017-02-10

    We suggest a formula for the efficiency of a single volume reflection of negatively charged particles in bent crystal planes and compare it to recent experiments at SLAC, MAMI and CERN with electrons and negative pions in the energy range from 0.855 to 150 GeV in Si crystals. We show that Lindhard reversibility rule provides sufficient basis for quantitative understanding of these experiments.

  18. 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

  19. Gamma-ray streaming in straight pipes and bent ducts

    International Nuclear Information System (INIS)

    Eid, M.; Diop, C.M.; Nimal, J.C.

    1985-04-01

    An important shielding problem is the gamma-ray streaming through voids. These problems are encountered in the reactors and reprocessing plants. A Monte Carlo method has been choosed as one of the most powerful technics to solve this kind of problems. Here in that frame, a biasing system which is adapted for two types of geometries is proposed: straight pipes and bent ducts. A code has been written applying this technique. The numerical results obained show the efficiency and the very good economy of the method proposed. It is hoped to extend the method to deal with more complex geometries and polykinetic situation as well

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

    OpenAIRE

    Kaur, Sarabjot; Panov, V. P.; Greco, C.; Ferrarini, A.; Görtz, Verena; Goodby, John W.; Gleeson, Helen F.

    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 calculat...

  1. First results from bent crystal extraction at the Fermilab Tevatron

    International Nuclear Information System (INIS)

    1996-07-01

    First results from Fermilab Experiment 953 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 for the experiment is to apply crystal extraction to trans-TeV accelerators like the LHC. Extensive simulation work has been carried out. Two accelerator operating modes have been developed for crystal studies, ''kick'' mode and diffusion mode. Results from the first successful extraction in kick mode are presented

  2. 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

  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... Published by Oxford University Press on behalf of the Royal Astronomical Society at South A frican A stronom ical O bservatory on D ecem ber 18, 2014 http://m nras.oxfordjournals.org/ D ow nloaded from Statistics for bent radio sources 3311 are left for a...

  4. Quantum effects for particles channeling in a bent crystal

    Energy Technology Data Exchange (ETDEWEB)

    Feranchuk, Ilya, E-mail: iferanchuk@gmail.com [Atomic Molecular and Optical Physics Research Group, Ton Duc Thang University, 19 Nguyen Huu Tho Str., Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, 19 Nguyen Huu Tho Str., Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Belarusian State University, 4 Nezavisimosty Ave., 220030 Minsk (Belarus); San, Nguyen Quang [Belarusian State University, 4 Nezavisimosty Ave., 220030 Minsk (Belarus)

    2016-09-15

    Quantum mechanical theory for channeling of the relativistic charged particles in the bent crystals is considered in the paper. Quantum effects of under-barrier tunneling are essential when the radius of the curvature is closed to its critical value. In this case the wave functions of the quasi-stationary states corresponding to the particles captured in a channel are presented in the analytical form. The efficiency of channeling of the particles and their angular distribution at the exit crystal surface are calculated. Characteristic experimental parameters for observation the quantum effects are estimated.

  5. 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

  6. Planar channeling and quasichanneling oscillations in a bent crystal

    International Nuclear Information System (INIS)

    Sytov, A.I.; Guidi, V.; Bagli, E.; Bandiera, L.; Germogli, G.; Mazzolari, A.; Tikhomirov, V.V.

    2016-01-01

    Particles passing through a crystal under planar channeling are captured by a continuous potential and experience transverse oscillations in their motion. As channeled particles approach the atomic planes, they are likely to be dechanneled. This effect is being used in ion-beam analysis with MeV energy. We study this effect in a bent crystal for positive and negative particles within a wide range of energies in sight of application of such crystals at accelerators. We look for the conditions for the observation or not of channeling oscillations in the deflection angle distribution in experiments where the beam passes through the bent crystal. Indeed a new kind of oscillations in the deflection angle distribution, strictly related to the motion of over-barrier particles, i.e. quasichanneled particles, is predicted. Such oscillations, named planar quasichanneling oscillations, possess a different nature than channeling oscillations. Through computer simulation, we study this effect and provided a theoretical interpretation for them. We show that channeling oscillations can be observed only for positive particles while quasichanneling oscillations can exist for particles with either sign. The conditions for experimental observation of channeling and quasichanneling oscillations at existing accelerators with available crystal are found and optimized. (orig.)

  7. Planar channeling and quasichanneling oscillations in a bent crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sytov, A.I. [Universita di Ferrara, Dipartimento di Fisica e Scienze della Terra, Ferrara (Italy); Belarusian State University, Research Institute for Nuclear Problems, Minsk (Belarus); INFN, Ferrara (Italy); Guidi, V.; Bagli, E.; Bandiera, L.; Germogli, G.; Mazzolari, A. [Universita di Ferrara, Dipartimento di Fisica e Scienze della Terra, Ferrara (Italy); INFN, Ferrara (Italy); Tikhomirov, V.V. [Belarusian State University, Research Institute for Nuclear Problems, Minsk (Belarus); INFN, Ferrara (Italy)

    2016-02-15

    Particles passing through a crystal under planar channeling are captured by a continuous potential and experience transverse oscillations in their motion. As channeled particles approach the atomic planes, they are likely to be dechanneled. This effect is being used in ion-beam analysis with MeV energy. We study this effect in a bent crystal for positive and negative particles within a wide range of energies in sight of application of such crystals at accelerators. We look for the conditions for the observation or not of channeling oscillations in the deflection angle distribution in experiments where the beam passes through the bent crystal. Indeed a new kind of oscillations in the deflection angle distribution, strictly related to the motion of over-barrier particles, i.e. quasichanneled particles, is predicted. Such oscillations, named planar quasichanneling oscillations, possess a different nature than channeling oscillations. Through computer simulation, we study this effect and provided a theoretical interpretation for them. We show that channeling oscillations can be observed only for positive particles while quasichanneling oscillations can exist for particles with either sign. The conditions for experimental observation of channeling and quasichanneling oscillations at existing accelerators with available crystal are found and optimized. (orig.)

  8. 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.

  9. 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...

  10. Design rules for out-of-plane stability of roller bent steel arches with FEM

    NARCIS (Netherlands)

    Spoorenberg, R.C.; Snijder, H.H.; Hoenderkamp, J.C.D.; Beg, D.

    2012-01-01

    This paper describes a numerical investigation into the out-of-plane buckling behavior of freestanding roller bent steel arches. As roller bent arches have structural imperfections which differ considerably from those of hot-rolled or welded sections, specific attention is paid to their inclusion in

  11. REGULAR METHOD FOR SYNTHESIS OF BASIC BENT-SQUARES OF RANDOM ORDER

    Directory of Open Access Journals (Sweden)

    A. V. Sokolov

    2016-01-01

    Full Text Available The paper is devoted to the class construction of the most non-linear Boolean bent-functions of any length N = 2k (k = 2, 4, 6…, on the basis of their spectral representation – Agievich bent squares. These perfect algebraic constructions are used as a basis to build many new cryptographic primitives, such as generators of pseudo-random key sequences, crypto graphic S-boxes, etc. Bent-functions also find their application in the construction of C-codes in the systems with code division multiple access (CDMA to provide the lowest possible value of Peak-to-Average Power Ratio (PAPR k = 1, as well as for the construction of error-correcting codes and systems of orthogonal biphasic signals. All the numerous applications of bent-functions relate to the theory of their synthesis. However, regular methods for complete class synthesis of bent-functions of any length N = 2k are currently unknown. The paper proposes a regular synthesis method for the basic Agievich bent squares of any order n, based on a regular operator of dyadic shift. Classification for a complete set of spectral vectors of lengths (l = 8, 16, … based on a criterion of the maximum absolute value and set of absolute values of spectral components has been carried out in the paper. It has been shown that any spectral vector can be a basis for building bent squares. Results of the synthesis for the Agievich bent squares of order n = 8 have been generalized and it has been revealed that there are only 3 basic bent squares for this order, while the other 5 can be obtained with help the operation of step-cyclic shift. All the basic bent squares of order n = 16 have been synthesized that allows to construct the bent-functions of length N = 256. The obtained basic bent squares can be used either for direct synthesis of bent-functions and their practical application or for further research in order to synthesize new structures of bent squares of orders n = 16, 32, 64, …

  12. Gamma-ray streaming in bent ducts and voids

    International Nuclear Information System (INIS)

    Bourdet, L.; Nimal, J.C.; Vergnaud, T.

    1983-05-01

    We have developed an analytical method to calculate gamma-ray streaming through straight ducts and a numerical method to study the gamma propagation in bends or in annular clearances. The whole set allows a rigorous treatment of gamma streaming through bent ducts. In the same time a Monte Carlo method allows to study any form of geometry, by using sophisticated biasing techniques. All these developments are made with a simplified albedo. An easy to use code is also proposed to calculate very general albedos and a code to calculate the dose rate due to reflection in a room. Gamma dose rate albedos are determined for all elements and the energy range which concerns fission reactors

  13. 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

  14. 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

  15. Bend-imitating theory and electron scattering in sharply-bent quantum nanowires

    International Nuclear Information System (INIS)

    Vakhnenko, O.O.

    2011-01-01

    The concept of bend-imitating description as applied to the one-electron quantum mechanics in sharply-bent ideal electron waveguides and its development into a self consistent theory are presented. In the framework of bend-imitating approach, the investigation of the electron scattering in a doubly-bent 2D quantum wire with S-like bend has been made, and the explicit dependences of the transmission and reflection coefficients on geometrical parameters of a structure, as well as on the electron energy, have been obtained. The total elimination of the mixing between the scattering channels of a S-like bent quantum wire is predicted.

  16. 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...

  17. Classifying bent radio galaxies from a mixture of point-like/extended images with Machine Learning.

    Science.gov (United States)

    Bastien, David; Oozeer, Nadeem; Somanah, Radhakrishna

    2017-05-01

    The hypothesis that bent radio sources are supposed to be found in rich, massive galaxy clusters and the avalibility of huge amount of data from radio surveys have fueled our motivation to use Machine Learning (ML) to identify bent radio sources and as such use them as tracers for galaxy clusters. The shapelet analysis allowed us to decompose radio images into 256 features that could be fed into the ML algorithm. Additionally, ideas from the field of neuro-psychology helped us to consider training the machine to identify bent galaxies at different orientations. From our analysis, we found that the Random Forest algorithm was the most effective with an accuracy rate of 92% for a classification of point and extended sources as well as an accuracy of 80% for bent and unbent classification.

  18. Experiments and calculations on neutron streaming through bent ducts

    Energy Technology Data Exchange (ETDEWEB)

    Kloosterman, J.L.; Hoogenboom, J.E. (Delft Univ. of Technology (Netherlands). Interfaculty Reactor Inst.); Zsolnay, E.M.

    1993-07-01

    Neutron spectra in a cylindrical straight duct and in bent ducts with angles of 30deg, 60deg and 90deg have been measured by the multiple foil activation and thermoluminescence dosimetry methods. Two-dimensional discrete ordinates and three-dimensional Monte Carlo calculations are executed, and the results are compared with the measurements. The flow rate at the duct entrance calculated by the DOT3.5 code is underestimated by approximately 30 %, due to a conversion of the core and reflector geometry from XY to RZ geometry. The fast neutron flux in the ducts is underestimated by 20 % by the MORSE-SGC/S code due to a too coarse angular mesh of the source, which does not properly represent the actual angular distribution of the fast flux, which is highly peaked forwardly into the ducts. The thermal neutron flux was over-estimated by the Monte Carlo calculation. A method is proposed to calculate the angular distribution of the flow rate at the duct entrance and to calculate the source strength and the angular distribution of the flow rate at the entrance of the second leg of the duct. The results are compared with those of the transport calculations. Generally, the agreement is quite satisfactory. (author).

  19. Elliptically Bent X-ray Mirrors with Active Temperature Stabilization

    International Nuclear Information System (INIS)

    Yuan, Sheng; Church, Matthew; Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Celestre, Rich; McKinney, Wayne R.; Kirschman, Jonathan; Morrison, Greg; Noll, Tino; Warwick, Tony; Padmore, Howard A.

    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 3K does not noticeably affect the mirror figure. Without temperature stabilization, the surface slope changes by approximately 1.5 ?mu rad rms (primarily defocus) under the same conditions.

  20. 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

  1. 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)

  2. Channeling and radiation in periodically bent crystals. 2. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Korol, Andrey V.; Solov' yov, Andrey V. [Frankfurt Univ., Frankfurt am Main (Germany). Physics Dept.; Greiner, Walter [Frankfurt Univ., Frankfurt am Main (Germany). Frankfurt Inst. for Advanced Studies

    2014-07-01

    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 device can emit intensive spontaneous monochromatic radiation and even reach the coherence of laser light sources. Readers will be presented with the underlying fundamental physics and be familiarized with the theoretical, experimental and technological advances made during the last one and a half decades in exploring the various features of investigations into crystalline undulators. This research draws upon knowledge from many research fields - such as materials science, beam physics, the physics of radiation, solid state physics and acoustics, to name but a few. Accordingly, much care has been taken by the authors to make the book as self-contained as possible in this respect, so as to also provide a useful introduction to this emerging field to a broad readership of researchers and scientist with various backgrounds. This new edition has been revised and extended to take recent developments in the field into account.

  3. Measurement and models of bent KAP(001) crystal integrated reflectivity and resolution (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Loisel, G. P., E-mail: gploise@sandia.gov; Wu, M.; Lake, P.; Dunham, G. S.; Bailey, J. E.; Rochau, G. A. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Stolte, W. [National Security Technologies, LLC, Livermore, California 94551 (United States); Kruschwitz, C. [National Security Technologies, LLC, Los Alamos, New Mexico 87544 (United States)

    2016-11-15

    The Advanced Light Source beamline-9.3.1 x-rays are used to calibrate the rocking curve of bent potassium acid phthalate (KAP) crystals in the 2.3-4.5 keV photon-energy range. Crystals are bent on a cylindrically convex substrate with a radius of curvature ranging from 2 to 9 in. and also including the flat case to observe the effect of bending on the KAP spectrometric properties. As the bending radius increases, the crystal reflectivity converges to the mosaic crystal response. The X-ray Oriented Programs (XOP) multi-lamellar model of bent crystals is used to model the rocking curve of these crystals and the calibration data confirm that a single model is adequate to reproduce simultaneously all measured integrated reflectivities and rocking-curve FWHM for multiple radii of curvature in both 1st and 2nd order of diffraction.

  4. 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.

  5. Spatially resolved analysis of short-range structure perturbations in a plastically bent molecular crystal

    Science.gov (United States)

    Panda, Manas K.; Ghosh, Soumyajit; Yasuda, Nobuhiro; Moriwaki, Taro; Mukherjee, Goutam Dev; Reddy, C. Malla; Naumov, Panče

    2015-01-01

    The exceptional mechanical flexibility observed with certain organic crystals defies the common perception of single crystals as brittle objects. Here, we describe the morphostructural consequences of plastic deformation in crystals of hexachlorobenzene that can be bent mechanically at multiple locations to 360° with retention of macroscopic integrity. This extraordinary plasticity proceeds by segregation of the bent section into flexible layers that slide on top of each other, thereby generating domains with slightly different lattice orientations. Microscopic, spectroscopic and diffraction analyses of the bent crystal showed that the preservation of crystal integrity when stress is applied on the (001) face requires sliding of layers by breaking and re-formation of halogen-halogen interactions. Application of stress on the (100) face, in the direction where π···π interactions dominate the packing, leads to immediate crystal disintegration. Within a broader perspective, this study highlights the yet unrecognized extraordinary malleability of molecular crystals with strongly anisotropic supramolecular interactions.

  6. Propagation of polarised light in bent hi-bi spun fibres

    Energy Technology Data Exchange (ETDEWEB)

    Przhiyalkovsky, Ya V; Morshnev, S K; Starostin, N I; Gubin, V P [V.A.Kotel' nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Fryazino branch, Fryazino, Moscow Region (Russian Federation)

    2015-11-30

    The evolution of polarisation states (PS's) of broadband light propagating through a bent optical fibre with a helical structure of its refractive index anisotropy (hi-bi spun fibre) has been studied theoretically and experimentally. It has been shown that there exists a coordinate system of PS's in which the differential Jones matrix can be replaced by a diagonal matrix, which allows the polarisation parameters of the output broadband light to be readily calculated with sufficient accuracy. We have derived a formula for evaluating the magneto-optical sensitivity of a bent spun fibre. An approach has been proposed for restoring the degree of polarisation of light in a bent hi-bi spun fibre and, as a consequence, the visibility (contrast) of the interferometer in a current sensor with a sensing element based on the fibre under consideration. (optical fibres)

  7. 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.

  8. 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.

  9. 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

  10. 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.)

  11. First observation of magnetic moment precession of channeled particles in bent crystals

    International Nuclear Information System (INIS)

    Chen, D.; Albuquerque, I.F.; Baublis, V.V.; Bondar, N.F.; Carrigan, R.A. Jr.; Cooper, P.S.; Lisheng, D.; Denisov, A.S.; Dobrovolsky, A.V.; Dubbs, T.; Endler, A.M.F.; Escobar, C.O.; Foucher, M.; Golovtsov, V.L.; Goritchev, P.A.; Gottschalk, H.; Gouffon, P.; Grachev, V.T.; Khanzadeev, A.V.; Kubantsev, M.A.; Kuropatkin, N.P.; Lach, J.; Lang Pengfei; Lebedenko, V.N.; Li Chengze; Li Yunshan; Mahon, J.R.P.; McCliment, E.; Morelos, A.; Newsom, C.; Pommot Maia, M.C.; Samsonov, V.M.; Schegelsky, V.A.; Shi Huanzhang; Smith, V.J.; Sun, C.R.; Tang Fukun; Terentyev, N.K.; Timm, S.; Tkatch, I.I.; Uvarov, L.N.; Vorobyov, A.A.; Yan Jie; Zhao Wenheng; Zheng Shuchen; Zhong Yuanyuan

    1992-01-01

    Spin precession of channeled particles in bent crystals has been observed for the first time. Polarized Σ + were channeled using bent Si crystals. These crystals provided an effective magnetic field of 45 T which resulted in a measured spin precession of 60±17 degree. This agrees with the prediction of 62±2 degree using the world average of Σ + magnetic moment measurements. This new technique gives a Σ + magnetic moment of (2.40±0.46±0.40)μ N , where the quoted uncertainties are statistical and systematic, respectively. We see no evidence of depolarization in the channeling process

  12. 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.

  13. Shuttle Ku-band bent-pipe implementation considerations. [for Space Shuttle digital communication systems

    Science.gov (United States)

    Batson, B. H.; Seyl, J. W.; Huth, G. K.

    1977-01-01

    This paper describes an approach for relay of data-modulated subcarriers from Shuttle payloads through the Shuttle Ku-band communications subsystem (and subsequently through a tracking and data relay satellite system to a ground terminal). The novelty is that a channel originally provided for baseband digital data is shown to be suitable for this purpose; the resulting transmission scheme is referred to as a narrowband bent-pipe scheme. Test results demonstrating the validity of the narrowband bent-pipe mode are presented, and limitations on system performance are described.

  14. 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

  15. 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...

  16. 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

  17. 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

  18. 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 ...

  19. Multi-GeV electron and positron channeling in bent silicon crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sushko, Gennady B., E-mail: sushko@fias.uni-frankfurt.de [Goethe-Universitat Frankfurt am Main, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany); Korol, Andrei V. [MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany); St. Petersburg State Maritime University, Leninsky Ave. 101, 198262 St. Petersburg (Russian Federation); Solov’yov, Andrey V. [MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany); A.F. Ioffe Physical-Technical Institute, Politekhnicheskaya ul. 26, 194021 St. Petersburg (Russian Federation)

    2015-07-15

    The planar channeling of 3…20 GeV electrons and positrons in bent Si(1 1 1) crystal was simulated by means of the MBN EXPLORER software package. The results of the simulations are analyzed in terms of dechanneling length characterization, angular distribution of outgoing projectiles and radiation spectrum. The results of calculations are compared with the recent experimental data.

  20. Comparison of coupled mode theory and FDTD simulations of coupling between bent and straight optical waveguides

    NARCIS (Netherlands)

    Bertolotti, M.; Symes, W.W.; Stoffer, Remco; Hiremath, K.R.; Driessen, A.; Michelotti, F; Hammer, Manfred

    Analysis of integrated optical cylindrical microresonators involves the coupling between a straight waveguide and a bent waveguide. Our (2D) variant of coupled mode theory is based on analytically represented mode profiles. With the bend modes expressed in Cartesian coordinates, coupled mode

  1. Out-of-plane stability of roller bent steel arches – an experimental investigation

    NARCIS (Netherlands)

    La Poutre, D.B.; Spoorenberg, R.C.; Snijder, H.H.; Hoenderkamp, J.C.D.

    2013-01-01

    This paper presents an experimental investigation of the elastic-plastic out-of-plane buckling response of roller bent circular steel arches subjected to a single force applied to the crown. The experiments are used to validate a finite element model described in a related paper. A series of 15

  2. 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.)

  3. 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.

  4. Outcomes of torsional microcoaxial phacoemulsification performed by 12-degree and 22-degree bent tips.

    Science.gov (United States)

    Helvacioglu, Firat; Yeter, Celal; Tunc, Zeki; Sencan, Sadik

    2013-08-01

    To compare the safety and efficacy of Ozil Intelligent Phaco torsional microcoaxial phacoemulsification surgeries performed with 12-degree and 22-degree bent tips using the Infiniti Vision System. Maltepe University School of Medicine Department of Ophthalmology, Istanbul, Turkey. Comparative case series. Eyes were assigned to 2.2 mm microcoaxial phacoemulsification using the torsional mode with a 22-degree bent tip (Group 1) or a 12-degree bent tip (Group 2). The primary outcome measures were ultrasound time (UST), cumulative dissipated energy (CDE), longitudinal and torsional ultrasound (US) amplitudes, mean surgical time, mean volume of balanced salt solution used, and surgical complications. Both groups included 45 eyes. The mean UST, CDE, longitudinal US amplitude, and torsional US amplitude were 65 seconds ± 27.23 (SD), 11.53 ± 6.99, 0.22 ± 0.26, and 42.86 ± 15.64, respectively, in Group 1 and 84 ± 45.04 seconds, 16.68 ± 10.66, 0.48 ± 0.68, and 46.27 ± 14.74, respectively, in Group 2. The mean UST, CDE, and longitudinal amplitudes were significantly lower in Group 1 (P=.003, P=.008, and P=.022, respectively). The mean volume of balanced salt solution was 73.33 ± 28.58 cc in Group 1 and 82.08 ± 26.21 cc in Group 2 (P=.134). Torsional phacoemulsification performed with 22-degree bent tips provided more effective lens removal than 12-degree bent tips, with a lower UST and CDE. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  5. Interactions between posture and locomotion: motor patterns in humans walking with bent posture versus erect posture.

    Science.gov (United States)

    Grasso, R; Zago, M; Lacquaniti, F

    2000-01-01

    Human erect locomotion is unique among living primates. Evolution selected specific biomechanical features that make human locomotion mechanically efficient. These features are matched by the motor patterns generated in the CNS. What happens when humans walk with bent postures? Are normal motor patterns of erect locomotion maintained or completely reorganized? Five healthy volunteers walked straight and forward at different speeds in three different postures (regular, knee-flexed, and knee- and trunk-flexed) while their motion, ground reaction forces, and electromyographic (EMG) activity were recorded. The three postures imply large differences in the position of the center of body mass relative to the body segments. The elevation angles of the trunk, pelvis, and lower limb segments relative to the vertical in the sagittal plane, the ground reaction forces and the rectified EMGs were analyzed over the gait cycle. The waveforms of the elevation angles along the gait cycle remained essentially unchanged irrespective of the adopted postures. The first two harmonics of these kinematic waveforms explain >95% of their variance. The phase shift but not the amplitude ratio between the first harmonic of the elevation angle waveforms of adjacent pairs was affected systematically by changes in posture. Thigh, shank, and foot angles covaried close to a plane in all conditions, but the plane orientation was systematically different in bent versus erect locomotion. This was explained by the changes in the temporal coupling among the three segments. For walking speeds >1 m s(-1), the plane orientation of bent locomotion indicates a much lower mechanical efficiency relative to erect locomotion. Ground reaction forces differed prominently in bent versus erect posture displaying characteristics intermediate between those typical of walking and those of running. Mean EMG activity was greater in bent postures for all recorded muscles independent of the functional role. The waveforms

  6. 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.

  7. Bent dark soliton dynamics in two spatial dimensions beyond the mean field approximation

    Science.gov (United States)

    Mistakidis, Simeon; Katsimiga, Garyfallia; Koutentakis, Georgios; Kevrekidis, Panagiotis; Schmelcher, Peter; Theory Group of Fundamental Processes in Quantum Physics Team

    2017-04-01

    The dynamics of a bented dark soliton embedded in two spatial dimensions beyond the mean-field approximation is explored. We examine the case of a single bented dark soliton comparing the mean-field approximation to a correlated approach that involves multiple orbitals. Fragmentation is generally present and significantly affects the dynamics, especially in the case of stronger interparticle interactions and in that of lower atom numbers. It is shown that the presence of fragmentation allows for the appearance of solitonic and vortex structures in the higher-orbital dynamics. In particular, a variety of excitations including dark solitons in multiple orbitals and vortex-antidark complexes is observed to arise spontaneously within the beyond mean-field dynamics. Deutsche Forschungsgemeinschaft (DFG) in the framework of the SFB 925 ``Light induced dynamics and control of correlated quantum systems''.

  8. Interference effects in Bragg-case synchrotron section topography of elastically bent silicon implanted crystals

    International Nuclear Information System (INIS)

    Wierzchowski, W.; Wieteska, K.; Graeff, W.

    1997-01-01

    White-beam synchrotron section topography was applied to a silicon crystal implanted with 4.8 MeV α-particles elastically bent with the radius of curvature close to 100 m. A number of section patterns corresponding to different reflections was analysed. It was found that the section pattern in the bent sample was drastically different from those observed in a flat sample. The difference consists in the occurrence of the sets of additional interference fringes covering a long distance up to several millimetres behind the main diffraction maximum. It was possible to reproduce some characteristic features of the fringes both in the implanted and non-implanted region by numerical integration of the Takagi-Taupin equation

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

    Energy Technology Data Exchange (ETDEWEB)

    Su, Yuhua, E-mail: yuhua.su@j-parc.jp [J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195 (Japan); Oikawa, Kenichi; Harjo, Stefanus; Shinohara, Takenao; Kai, Tetsuya; Harada, Masahide; Hiroi, Kosuke [J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195 (Japan); Zhang, Shuoyuan; Parker, Joseph Don [Neutron R& D Division, CROSS-Tokai, 162-1 Shirakata, Tokai, Ibaraki 319-1106 (Japan); Sato, Hirotaka [Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Shiota, Yoshinori; Kiyanagi, Yoshiaki [Graduate School of Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan); Tomota, Yo [Research Center for Strategic Materials, National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2016-10-15

    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.

  10. 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.

  11. Alcohol sensor based on u-bent hetero-structured fiber optic

    Science.gov (United States)

    Patrialova, Sefi N.; Hatta, Agus M.; Sekartedjo, Sekartedjo

    2016-11-01

    A sensor based on a fiber optic hetero-structure to determine the concentration of alcohol has been proposed. The structure of the sensing probe in this research is a singlemode-multimode-singlemode (SMS) which bent into Ushaped and soon called as SMS u-bent. The SMS structure was chosen to get a higher sensitivity. This research utilizes the principle of multimode interference and evanescent field by modifying the cladding with various alcohol concentration. Testing of the sensor's performance has been done by measuring the sensor's power output response to the length of the SMS fiber optic, bending diameter, and alcohol concentration. Based on the experiment result, the ubent SMS fiber optic with 50 mm bending diameter and 63 mm MMF lenght has the highest sensitivity, 3.87 dB/% and the minimum resolution, 0.26 x 10-3 %.

  12. 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.

  13. Low cycle fatigue behavior of hot-bent 347 stainless steel in a simulated PWR water environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun Ho; Seo, Myung Gyu; Jang, Chang Heui [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Hong, Jong Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Tae Soon [Central Research InstituteKorea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

    2016-11-15

    The effect of hot bending on the Low cycle fatigue (LCF) behavior of 347 SS was evaluated in Room temperature (RT) air and simulated Pressurized water reactor (PWR) water environments. The LCF life of 347 SS in PWR water was shorter than that in RT air for the as-received and hot-bent conditions. The LCF life of hot-bent 347 SS was relatively longer than that of the as-received condition in both RT air and PWR water. Microstructure analysis indicated development of dislocation structure near niobium carbide particles and increase in dislocation density for the hot-bent 347 SS. Such microstructure acted as barriers to dislocation movement during the LCF test, resulting in minimal hardening for the hot-bent 347 SS in RT air.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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.)

  20. 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

  1. 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.

  2. 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.

  3. Microstrip silicon detectors in a bent crystal based collimation system: The UA9 experiment

    International Nuclear Information System (INIS)

    Bolognini, D.

    2010-01-01

    In a hadron accelerator like Lhc, a collimation system needs to be developed to protect the accelerator itself from the beam loss damage, increasing the beam luminosity. At present, a classical robust multi-stage collimation system (based on amorphous jaws) allows to protect Lhc, but limits the luminosity to the 40% of the nominal value. In order to solve this problem, a series of low-impedance collimation systems is being developed for the second Lhc collimation phase: among these, a key role could be played by bent crystals. In a bent crystal, in fact, charged particles can be deviated in a given direction with a high efficiency, reducing the impedance and increasing the luminosity. After the satisfactory results on extracted beams, it was decided to test bent crystals on a circular accelerator (the Super Proton Synchrotron Sps at CERN): the UA9 experiment was born. In order to qualify the crystal behavior, a tracking system has been developed: the system is based on microstrip silicon detectors readout by self-triggering ASICs with a spatial resolution of the order of 5 μm; the system, completely remotely controlled and based on the optical fiber transmission, would be able to measure the beam halo phase space x - x 1 . This paper, after a brief introduction of the UA9 experiment, will describe the tracking system and the first results obtained in the commissioning phase and data takings with a detector prototype.

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

    CERN Document Server

    Ren, B; 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) i...

  5. Photoelastic investigation of the stresses in mitred bent cylinders under bending, (1)

    International Nuclear Information System (INIS)

    Sawa, Yoshiaki

    1982-01-01

    Recently large bore pipes have been frequently used, and the techniques of jointing such pipes are important technical problem. As for the actual design of pipe joints, the stress condition has not been sufficiently clarified. When two same diameter pipes are jointed making a certain angle, mitred bent pipes are often used from economical and technical viewpoints as the pipes become large bore. In a mitred bent pipe, there is a sharp edge in its pipe joint, at which the measurement of stress and strain is difficult. The stress distribution near the joint when a mitred bent pipe is subjected to the bending moment in the plane containing the axes of both pipes was analyzed by the freezing three-dimensional photo-elastic method, and not only the bending stress in the joint but also the hoop stress were determined by the wedge method. This stress concentration phenomenon is due to the whole structural factor of the intersection of two pipes and the local stress peak factor caused at the wedge-shaped edge formed in the intersection. The local form of the intersection plays important role in the stress concentration. The manufactured models, the method of loading, slices and the wedge method, and the stress distribution are reported. (Kako, I.)

  6. The free energy profile of tubulin straight-bent conformational changes, with implications for microtubule assembly and drug discovery.

    Directory of Open Access Journals (Sweden)

    Lili X Peng

    2014-02-01

    Full Text Available αβ-tubulin dimers need to convert between a 'bent' conformation observed for free dimers in solution and a 'straight' conformation required for incorporation into the microtubule lattice. Here, we investigate the free energy landscape of αβ-tubulin using molecular dynamics simulations, emphasizing implications for models of assembly, and modulation of the conformational landscape by colchicine, a tubulin-binding drug that inhibits microtubule polymerization. Specifically, we performed molecular dynamics, potential-of-mean force simulations to obtain the free energy profile for unpolymerized GDP-bound tubulin as a function of the ∼12° intradimer rotation differentiating the straight and bent conformers. Our results predict that the unassembled GDP-tubulin heterodimer exists in a continuum of conformations ranging between straight and bent, but, in agreement with existing structural data, suggests that an intermediate bent state has a lower free energy (by ∼1 kcal/mol and thus dominates in solution. In agreement with predictions of the lattice model of microtubule assembly, lateral binding of two αβ-tubulins strongly shifts the conformational equilibrium towards the straight state, which is then ∼1 kcal/mol lower in free energy than the bent state. Finally, calculations of colchicine binding to a single αβ-tubulin dimer strongly shifts the equilibrium toward the bent states, and disfavors the straight state to the extent that it is no longer thermodynamically populated.

  7. 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)

  8. 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.

  9. Using quasi-guided modes for modeling the transfer behavior of bent dielectric slab waveguides

    Directory of Open Access Journals (Sweden)

    M. Stallein

    2010-09-01

    Full Text Available The connection of two straight dielectric multimode slab waveguides by a circular bent waveguide is analyzed by means of quasi-guided modes. These modes correspond to the well known leaky modes, but own real eigenvalues, thus the mathematical description is simpler. Furthermore they are derived as approximate solutions of the exact theory. This work will first give a brief introduction to the basic theory, followed by a discussion of the properties of quasi-guided modes. After a validation by comparison with a numerical simulation using the Finite Integration Technique, results for the bending loss of multimode waveguides are presented.

  10. Observation of Multiple Volume Reflection of Ultrarelativistic Protons by a Sequence of Several Bent Silicon Crystals

    CERN Document Server

    Scandale, Walter; Baricordi, S; Dalpiaz, P; Fiorini, M; Guidi, V; Mazzolari, A; Della Mea, G; Milan, R; Ambrosi, G; Zuccon, P; Bertucci, B; Bürger, W; Duranti, M; Cavoto, G; Santacesaria, R; Valente, P; Luci, C; Iacoangeli, F; Vallazza, E; Afonin, A G; Chesnokov, Yu A; Kotov, V I; Maisheev, V A; Yazynin, I A; Kovalenko, A D; Taratin, A M; Denisov, A S; Gavrikov, Y A; Ivanov, Yu M; Lapina, L P; Malyarenko, L G; Skorogobogatov, V V; Suvorov, V M; Vavilov, S A; Bolognini, D; Hasan, S; Mozzanica, A; Prest, M

    2009-01-01

    The interactions of 400 GeV protons with different sequences of bent silicon crystals have been investigated at the H8 beam line of the CERN Super Proton Synchrotron. The multiple volume reflection of the proton beam has been studied in detail on a five-crystal reflector measuring an angular beam deflection =52.96±0.14 µrad. The efficiency was found larger than 80% for an angular acceptance at the reflector entrance of 70 µrad, with a maximal efficiency value of =0.90±0.01±0.03.

  11. High-Efficiency Volume Reflection of an Ultrarelativistic Proton Beam with a Bent Silicon Crystal

    CERN Document Server

    Scandale, Walter; Carnera, Alberto; 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; Yaznin, Igor A; Afansiev, 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

    2007-01-01

    The volume reflection phenomenon was detected while investigating 400 GeV proton interactions with bent silicon crystals in the external beam H8 of the CERN Super Proton Synchrotron. Such a process was observed for a wide interval of crystal orientations relative to the beam axis, and its efficiency exceeds 95%, thereby surpassing any previously observed value. These observations suggest new perspectives for the manipulation of high-energy beams, e.g., for collimation and extraction in new-generation hadron colliders, such as the CERN Large Hadron Collider.

  12. Linear all-fiber temperature sensor based on macro-bent erbium doped fiber

    International Nuclear Information System (INIS)

    Hajireza, P; Cham, C L; Kumar, D; Abdul-Rashid, H A; Emami, S D; Harun, S W

    2010-01-01

    A new all fiber temperature sensor is proposed and demonstrated based on a pair of 1 meter erbium-doped fiber (EDF), which are respectively macro-bent and straight. The sensor has a linear normalized loss (dB) response to temperature at 6.5 mm bending radius and 1580 nm input wavelength. The main advantage of this sensor is high temperature resolution (less than 1°C) and sensitivity (0.03 dB/°C) due to combination of temperature dependence of EDF and bending loss. The proposed silica based sensor, has the potential for wide range and high temperature applications in harsh environments

  13. 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.

  14. Flexible bent rod model with a saturating induced dipole moment to study the electric linear dichroism of DNA fragments

    Science.gov (United States)

    Bertolotto, Jorge A.; Umazano, Juan P.

    2016-06-01

    In the present work we make a theoretical study of the steady state electric linear dichroism of DNA fragments in aqueous solution. The here developed theoretical approach considers a flexible bent rod model with a saturating induced dipole moment. The electric polarizability tensor of bent DNA fragments is calculated considering a phenomenological model which theoretical and experimental backgroung is presented here. The model has into account the electric polarizability longitudinal and transversal to the macroion. Molecular flexibility is described using an elastic potential. We consider DNA fragments originally bent with bending fluctuations around an average bending angle. The induced dipole moment is supposed constant once the electric field strength grows up at critical value. To calculate the reduced electric linear dichroism we determine the optical factor considering the basis of the bent DNA perpendicular to the molecular axis. The orientational distribution function has into account the anisotropic electric properties and the molecule flexibility. We applied the present theoretical background to fit electric dichroism experimental data of DNA fragments reported in the bibliography in a wide range of molecular weight and electric field. From these fits, values of DNA physical properties are estimated. We compare and discuss the results here obtained with the theoretical and experimental data presented by other authors. The original contributions of this work are: the inclusion of the transversal electric polarizability saturating with the electric field, the description of the electric properties with an electric polarizability tensor dependant on the bending angle and the use of an arc model originally bent.

  15. Total spectrum of photon emission by an ultra-relativistic positron channelling in a periodically bent crystal

    International Nuclear Information System (INIS)

    Krause, W.; Korol, A.V.; Department of Physics, St Petersburg State Maritime Technical University, Leninskii prospect 101, St Petersburg 198262; Solov'yov, A.V.; AF Ioffe Physical-Technical Institute of the Academy of Sciences of Russia, Polytechnicheskaya 26, St Petersburg 194021; Greiner, W.

    2000-01-01

    We present the results of numerical calculations of the channelling and undulator radiation generated by ultra-relativistic positron channelling along a crystal plane, which is periodically bent. The bending might be due to either the propagation of a transverse acoustic wave through the crystal, or the static strain as it occurs in superlattices. The periodically bent crystal serves as an undulator. We investigate the dependence of the intensities of both the ordinary channelling and the undulator radiations on the parameters of the periodically bent channel with simultaneous account for the de-channelling effect of the positrons. We demonstrate that there is a range of parameters in which the undulator radiation dominates over the channelling one and the characteristic frequencies of both types of radiation are well separated. This result is important, because the undulator radiation can be used to create a tunable source of x-ray and γ-radiation. (author). Letter-to-the-editor

  16. Analysis of piston behavior according to eccentricity ratio of disk in bent-axis type piston pump

    International Nuclear Information System (INIS)

    Baek, Il Hyun; Cho, Ihn Sung; Jung, Jae Youn; Hong, Lu

    2008-01-01

    To improve the performance of the bent-axis type axial piston pump driven by the tapered piston, it is necessary to know the driving characteristics and mechanism of the tapered piston and the cylinder block. Since each piston not only rotates on its axis and reciprocates in the cylinder bore but also revolves around the axis of the driving shaft, it is difficult to analyze the driving mechanism theoretically. The theoretical mechanism for the bent-axis type axial piston pump is studied by using the geometrical method. The driving range of the tapered piston is determined by theoretical equations. The results show that the cylinder block is driven by one tapered piston in a limited range and the core parameters such as the tilting angle of the piston and the ahead delay angle influence performance of the bent-axis type axial piston pump

  17. A study on the pressure ripple characteristics in a bent-axis type oil hydraulic piston pump

    International Nuclear Information System (INIS)

    Cho, Ihn Sung; Jung, Jae Youn

    2013-01-01

    To improve the performance of a bent-axis type axial piston pump driven by tapered pistons, it is necessary to know the pressure ripple characteristics. The purpose of this paper is to understand the effect on the pressure ripple characteristics, and to predict by comparing experimental and theoretical analysis results. The simulation model of a bent-axis type axial piston pump is developed in the AMESim environment using the geometrical dimension, and the driving mechanism of the piston pump, such as the stroke of pump, the velocity of piston, the instantaneous volumetric flow, the overlap area of valve plate opening to cylinder bore, the angle of notch, and so on. The results show that theoretical analysis results of the bent-axis type axial piston pump by using the AMESim approximate the pressure ripple characteristic of the test pump, and through this, simulations can be obtained that predict the performance characteristics of a bentaxis type axial piston pump.

  18. 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.

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

    International Nuclear Information System (INIS)

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

    2003-01-01

    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 (≤10 μm) 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-μm resolution over a 20-mm field of view are presented

  20. Bent CNN bond of diazo compounds, RR'(Cdbnd N+dbnd N-)

    Science.gov (United States)

    Akita, Motoko; Takahashi, Mai; Kobayashi, Keiji; Hayashi, Naoto; Tukada, Hideyuki

    2013-02-01

    The reaction of ninhydrin with benzophenone hydrazone afforded 2-diazo-3-diphenylmethylenehydrazono-1-indanone 1 and 2-diazo-1,3-bis(diphenylmethylenehydrazono)indan 2. X-ray crystal structure analyses of these products showed that the diazo functional group Cdbnd N+dbnd N- of 1 is bent by 172.9°, while that of 2 has a linear geometry. The crystal structure data of diazo compounds have been retrieved from the Cambridge Structural Database (CSD), which hit 177 entries to indicate that the angle of 172.9° in 1 lies in one of the most bent structures. The CSD search also indicated that diazo compounds consisting of a distorted diazo carbon tend to bend the Cdbnd N+dbnd N- bond. On the basis of DFT calculations (B3LYP/6-311++G(d,p)) of model compounds, it was revealed that the bending of the CNN bond is principally induced by steric factors and that the neighboring carbonyl group also plays a role in bending toward the carbonyl side owing to an electrostatic attractive interaction. The potential surface along the path of Cdbnd N+dbnd N- bending in 2-diazopropane shows a significantly shallow profile with only 4 kcal/mol needed to bend the Cdbnd N+dbnd N- bond from 180° to 160°. Thus, the bending of the diazo group in 1 is reasonable as it is provided with all of the factors for facile bending disclosed in this investigation.

  1. 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.

  2. FIRST Bent-Double Radio Sources: Tracers of High-Redshift Clusters

    International Nuclear Information System (INIS)

    Blanton, E. L.; Gregg, M. D.; Helfand, D. J.; Becker, R. H.; White, R. L.

    2000-01-01

    Bent-double radio sources can act as tracers for clusters of galaxies. We present imaging and spectroscopic observations of the environments surrounding 10 of these sources (most of them wide-angle tails [WATs]) selected from the VLA FIRST survey. Our results reveal a previously unknown cluster associated with eight of the radio sources with redshifts in the range 0.33< z<0.85; furthermore, we cannot rule out that the other two bent doubles may be associated with clusters at higher redshift. Richness measurements indicate that these clusters are typical of the majority of those found in the Abell catalog, with a range of Abell richness classes from 0 to 2. The line-of-sight velocity dispersions are very different from cluster to cluster, ranging from approximately 300 to 1100 km s-1. At the upper end of these intervals, we may be sampling some of the highest redshift massive clusters known. Alternatively, the large velocity dispersions measured in some of the clusters may indicate that they are merging systems with significant substructure, consistent with recent ideas concerning WAT formation (Burns et al.). (c) 2000 The American Astronomical Society

  3. True Tapping Mode Scanning Near-Field Optical Microscopy with Bent Glass Fiber Probes.

    Science.gov (United States)

    Smirnov, A; Yasinskii, V M; Filimonenko, D S; Rostova, E; Dietler, G; Sekatskii, S K

    2018-01-01

    In scanning near-field optical microscopy, the most popular probes are made of sharpened glass fiber attached to a quartz tuning fork (TF) and exploiting the shear force-based feedback. The use of tapping mode feedback could be preferable. Such an approach can be realized, for example, using bent fiber probes. Detailed analysis of fiber vibration modes shows that realization of truly tapping mode of the probe dithering requires an extreme caution. In case of using the second resonance mode, probes vibrate mostly in shear force mode unless the bending radius is rather small (ca. 0.3 mm) and the probe's tip is short. Otherwise, the shear force character of the dithering persists. Probes having these characteristics were prepared by irradiation of a tapered etched glass fiber with a CW CO 2 laser. These probes were attached to the TF in double resonance conditions which enables achieving significant quality factor (4000-6000) of the TF + probe system (Cherkun et al., 2006). We also show that, to achieve a truly tapping character, dithering, short, and not exceeding 3 mm lengths of a freestanding part of bent fiber probe beam should also be used in the case of nonresonant excitation.

  4. On the discrete spectrum of the Dirac operator on bent chain quantum graph

    Directory of Open Access Journals (Sweden)

    Belov Michail

    2017-01-01

    Full Text Available We study Dirac operators on an infinite quantum graph of a bent chain form which consists of identical rings connected at the touching points by δ-couplings with a parameter α ∈ ℝ. We are interested in the discrete spectrum of the corresponding Hamiltonian. It can be non-empty due to a local (geometrical perturbation of the corresponding infinite chain of rings. The quantum graph of analogous geometry with the Schrodinger operator on the edges was considered by Duclos, Exner and Turek in 2008. They showed that the absence of δ-couplings at vertices (i.e. the Kirchhoff condition at the vertices lead to the absence of eigenvalues. We consider the relativistic particle (the Dirac operator instead of the Schrodinger one but the result is analogous. Quantum graphs of such type are suitable for description of grapheme-based nanostructures. It is established that the negativity of α is the necessary and sufficient condition for the existence of eigenvalues of the Dirac operator (i.e. the discrete spectrum of the Hamiltonian in this case is not empty. The continuous spectrum of the Hamiltonian for bent chain graph coincides with that for the corresponding straight infinite chain. Conditions for appearance of more than one eigenvalue are obtained. It is related to the bending angle. The investigation is based on the transfer-matrix approach. It allows one to reduce the problem to an algebraic task. δ-couplings was introduced by the operator extensions theory method.

  5. Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystals

    International Nuclear Information System (INIS)

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

    2014-01-01

    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 in Albuquerque, New Mexico. 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 double crystal diffractometer 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

  6. 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.

  7. 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.

  8. 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...

  9. True Tapping Mode Scanning Near-Field Optical Microscopy with Bent Glass Fiber Probes

    Directory of Open Access Journals (Sweden)

    A. Smirnov

    2018-01-01

    Full Text Available In scanning near-field optical microscopy, the most popular probes are made of sharpened glass fiber attached to a quartz tuning fork (TF and exploiting the shear force-based feedback. The use of tapping mode feedback could be preferable. Such an approach can be realized, for example, using bent fiber probes. Detailed analysis of fiber vibration modes shows that realization of truly tapping mode of the probe dithering requires an extreme caution. In case of using the second resonance mode, probes vibrate mostly in shear force mode unless the bending radius is rather small (ca. 0.3 mm and the probe’s tip is short. Otherwise, the shear force character of the dithering persists. Probes having these characteristics were prepared by irradiation of a tapered etched glass fiber with a CW CO2 laser. These probes were attached to the TF in double resonance conditions which enables achieving significant quality factor (4000–6000 of the TF + probe system (Cherkun et al., 2006. We also show that, to achieve a truly tapping character, dithering, short, and not exceeding 3 mm lengths of a freestanding part of bent fiber probe beam should also be used in the case of nonresonant excitation.

  10. Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystals

    Energy Technology Data Exchange (ETDEWEB)

    Haugh, M. J., E-mail: haughmj@nv.doe.gov; Jacoby, K. D. [National Security Technologies, LLC, Livermore, California 94550 (United States); Wu, M.; Loisel, G. P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)

    2014-11-15

    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 in Albuquerque, New Mexico. 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 double crystal diffractometer 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.

  11. Long-Lived Triplet Excited States of Bent-Shaped Pentacene Dimers by Intramolecular Singlet Fission.

    Science.gov (United States)

    Sakuma, Takao; Sakai, Hayato; Araki, Yasuyuki; Mori, Tadashi; Wada, Takehiko; Tkachenko, Nikolai V; Hasobe, Taku

    2016-03-24

    Intramolecular singlet fission (ISF) is a promising photophysical process to construct more efficient light energy conversion systems as one excited singlet state converts into two excited triplet states. Herein we synthesized and evaluated bent-shaped pentacene dimers as a prototype of ISF to reveal intrinsic characters of triplet states (e.g., lifetimes of triplet excited states). In this study, meta-phenylene-bridged TIPS-pentacene dimer (PcD-3Ph) and 2,2'-bipheynyl bridged TIPS-pentacene dimer (PcD-Biph) were newly synthesized as bent-shaped dimers. In the steady-state spectroscopy, absorption and emission bands of these dimers were fully characterized, suggesting the appropriate degree of electronic coupling between pentacene moieties in these dimers. In addition, the electrochemical measurements were also performed to check the electronic interaction between two pentacene moieties. Whereas the successive two oxidation peaks owing to the delocalization were observed in a directly linked-pentacene dimer (PcD) by a single bond, the cyclic voltammograms in PcD-Biph and PcD-3Ph implied the weaker interaction compared to that of p-phenylene-bridged TIPS-pentacene dimer (PcD-4Ph) and PcD. The femtosecond and nanosecond transient absorption spectra clearly revealed the slower ISF process in bent-shaped pentacene dimers (PcD-Biph and PcD-3Ph), more notably, the slower relaxation of the excited triplet states in PcD-Biph and PcD-3Ph. Namely, the quantum yields of triplet states (ΦT) by ISF approximately remain constant (ca. 180-200%) in all dimer systems, whereas the lifetimes of the triplet excited states became much longer (up to 360 ns) in PcD-Biph as compared to PcD-4Ph (15 ns). Additionally, the lifetimes of the corresponding triplet states in PcD-Biph and PcD-3Ph were sufficiently affected by solvent viscosity. In particular, the lifetimes of PcD-Biph triplet state in THF/paraffin (1.0 μs) increased up to approximately three times as compared to that in THF

  12. 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

  13. 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

  14. Guiding effect of bent macroscopic quartz tube for high current electron beam

    International Nuclear Information System (INIS)

    Zhang Mingwu; Chen Jing; Wu Yehong; Yang Bian; Wang Wei; Xue Yingli; Yu Deyang; Cai Xiaohong

    2012-01-01

    By using an incident electron beam with the high current and high energy, the guiding effect of the bent macroscopic quartz tube for the electron beam has been investigated. The angular distributions of outgoing electrons depending on the current and energy of incident electrons were measured. The dependences of electron transmitted fraction on energy and current of incident electrons are also shown. As the incident electron energy increasing, the electron transmitted fraction increases, but it decreases while the incident electron current increasing. The results have been compared with the present data. This work presents, the process of guiding electrons is essentially different from that of guiding highly charged ions, the guiding electron beam was caused by both elastic and inelastic collisions between electrons and inner walls of quartz tube, rather than self-organized charging effect on the surface of inner wall of quartz tube. (authors)

  15. Experimental evidence for multi-pass extraction with a bent crystal

    CERN Document Server

    Dehning, Bernd; Fidecaro, Giuseppe; Gyr, Marcel; Herr, Werner; Klem, J T; Scandale, Walter; Vuagnin, G; Weisse, E; Weisz, S; Møller, S P; Uggerhøj, Erik; Freund, A; Hustache, R; Carboni, G; Bussa, M P; Tosello, F

    1996-01-01

    The feasibility of extracting particles from the halo of a circulating proton beam using a bent silicon crystal has been demonstrated experimentally at the SPS for a beam energy of 120 GeV. Presently studies are conducted to understand the extraction mechanisms and the measured efficiencies. In particular the contribution of multi-pass extraction, where the particles can pass through the crystal many times before being channelled and extracted, is investigated. In a recent experiment, using a crystal especially fabricated with a finite amorphous layer on its surface, it has been proven that multi-pass extraction plays an important role. The experiment is described and the implication for further studies are discussed.

  16. 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.

  17. 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.)

  18. 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)

  19. 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.

  20. CRYSTAL simulation code and modeling of coherent effects in a bent crystal at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Sytov, A.I., E-mail: alex_sytov@mail.ru [Research Institute for Nuclear Problems, Belarusian State University, Bobruiskaya str., 11, 220030 Minsk (Belarus); INFN Sezione di Ferrara, Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Via Saragat 1, 44100 Ferrara (Italy); Tikhomirov, V.V., E-mail: vvtikh@mail.ru [Research Institute for Nuclear Problems, Belarusian State University, Bobruiskaya str., 11, 220030 Minsk (Belarus)

    2015-07-15

    A CRYSTAL simulation code for particle tracking in crystals is introduced. Its essence consists in both adequate and fast sampling of proton trajectories in crystals which is crucial for both correct description of experiments and quantitative prediction of new effects. The H8 single-pass experiment at the CERN SPS as well as 7 TeV proton deflection by a bent crystal at the LHC are simulated. We predict the existence of dechanneling peaks corresponding to the planar channeling oscillations as well as describe the possibility of their observation at high energies, specifically at the LHC energy. An effect of excess over the amorphous level of ionization losses in the channeling mode was also found at 7 TeV.

  1. 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.

  2. A double-bent planar leaf flexure guide for a nano-scanner: experimental report

    International Nuclear Information System (INIS)

    Jeon, Jeong-Woo; Kim, Jong-Moon; Lee, Young-Hyoung; Lee, Dong-Yeon

    2014-01-01

    We describe an experimental study on the double-bent leaf flexure-guided nano-scanner introduced in a previous paper [J. Korean Phy. Soc. 57, 1581 (2010)]. The optimally-designed nanoscanner was fabricated. Its performances were verified using a finite element analysis (FEA). The nano-scanner is actuated by a voice coil motor. Its characteristics were measured with a laser interferometer. The first resonant frequency is calculated as 17.1 Hz. The performances of the nano-scanner, including sine tracking capability, a multi-step response, and range of travel check were evaluated using various experimental procedures. Test results reveal that the scanner traveled over a 4.0 mm range and had good nano-precision (4 nm).

  3. 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

  4. The construction and performance of a one-meter-long elliptically bent steel mirror

    International Nuclear Information System (INIS)

    Renner, T.R.; Franck, K.; Howells, M.R.; Irick, S.; Padmore, H.A.

    1997-10-01

    An elliptically bent mirror of total length 1.25 m has been developed at the Advanced Light Source (ALS) for focusing soft x-rays. The mirror is used to produce a small, high flux density illuminated field of view for a Photo Emission Electron Microscope (PEEM). The requirement to collect the maximum horizontal aperture with the need to highly demagnify the source leads to a mirror with a wide range of curvatures along the surface. This combined with the need to produce a low slope error surface at a reasonably low cost has required the authors to develop a mirror based on the controlled bending of a flat substrate. This is an extension of several other mirror projects at the ALS where controlled bending of glass and metal substrates has been used in microfocusing applications. Those mirrors however are a maximum of 200 mm long, and in this paper they describe the new challenges they have faced and the solutions they have adopted in developing a long and highly elliptical mirror. The mirror described here is manufactured from a low carbon steel (1006) which is capable of good dimensional stability, it is electroless nickel plated for polishing, and is bent into an elliptical shape by the application of unequal couples. They describe the mirror fabrication process, the mechanical details of the bending mechanism and the experimentally measured slope error from an ellipse. The final mirror has an rms roughness of 6 angstrom (rms), a full aperture (1.1 m) slope error of 14 microrad (rms), and a slope error of < 3 micro rad when optimized over approximately 2/3 of the required optical length (0.917 m)

  5. 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

  6. Flexible bent rod model with a saturating induced dipole moment to study the electric linear dichroism of DNA fragments

    Directory of Open Access Journals (Sweden)

    Jorge A. Bertolotto

    2016-06-01

    Full Text Available In the present work we make a theoretical study of the steady state electric linear dichroism of DNA fragments in aqueous solution. The here developed theoretical approach considers a flexible bent rod model with a saturating induced dipole moment. The electric polarizability tensor of bent DNA fragments is calculated considering a phenomenological model which theoretical and experimental backgroung is presented here. The model has into account the electric polarizability longitudinal and transversal to the macroion. Molecular flexibility is described using an elastic potential. We consider DNA fragments originally bent with bending fluctuations around an average bending angle. The induced dipole moment is supposed constant once the electric field strength grows up at critical value. To calculate the reduced electric linear dichroism we determine the optical factor considering the basis of the bent DNA perpendicular to the molecular axis. The orientational distribution function has into account the anisotropic electric properties and the molecule flexibility. We applied the present theoretical background to fit electric dichroism experimental data of DNA fragments reported in the bibliography in a wide range of molecular weight and electric field. From these fits, values of DNA physical properties are estimated. We compare and discuss the results here obtained with the theoretical and experimental data presented by other authors. The original contributions of this work are: the inclusion of the transversal electric polarizability saturating with the electric field, the description of the electric properties with an electric polarizability tensor dependant on the bending angle and the use of an arc model originally bent.

  7. Approach to a manufacture-oriented modeling of bent tubes depending on the curvature distribution during three-roll-push-bending

    Science.gov (United States)

    Groth, Sebastian; Engel, Bernd; Frohn, Peter

    2018-05-01

    Kinematic bending processes such as three-roll-push-bending are used to manufacture freeform bent part systems. Due to the kinematic shaping, the bent parts have a characteristic infeed and outfeed area in the transition zone from the straight section into the curved area. These transition zones are currently not considered in the design process, which results in a geometric shape deviation between the CAD model and the bent part. Within this publication, a sensitivity analysis examines the influence of different parameters on the transition zone and the shape deviation. In addition, an approach is presented, which allows a manufacture-oriented modeling of the bending geometry.

  8. 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.

  9. 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.

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

    Science.gov (United States)

    Wang, K. F.; Wang, B. L.

    2018-06-01

    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°, 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.

  11. Relaxation of axially confined 400 GeV/c protons to planar channeling in a bent crystal

    International Nuclear Information System (INIS)

    Bandiera, L.; Mazzolari, A.; Bagli, E.; Germogli, G.; Guidi, V.; Sytov, A.; Kirillin, I.V.; Shul'ga, N.F.; Berra, A.; Lietti, D.; Prest, M.; De Salvador, D.; Vallazza, E.

    2016-01-01

    An investigation on the mechanism of relaxation of axially confined 400 GeV/c protons to planar channeling in a bent crystal was carried out at the extracted line H8 from CERN Super Proton Synchrotron. The experimental results were critically compared to computer simulations, showing a good agreement. We identified a necessary condition for the exploitation of axial confinement or its relaxation for particle beam manipulation in high-energy accelerators. We introduce the idea of using a short bent crystal, aligned with one of its main axis to the beam direction, as a beam steerer or a beam splitter with adjustable intensity in the field of particle accelerators. In particular, in the latter case, a complete relaxation from axial confinement to planar channeling takes place, resulting in beam splitting into the two strongest skew planar channels. (orig.)

  12. Relaxation of axially confined 400 GeV/c protons to planar channeling in a bent crystal

    Energy Technology Data Exchange (ETDEWEB)

    Bandiera, L.; Mazzolari, A.; Bagli, E.; Germogli, G.; Guidi, V. [Universita di Ferrara, Dipartimento di Fisica, Ferrara (Italy); INFN, Ferrara (Italy); Sytov, A. [Universita di Ferrara, Dipartimento di Fisica, Ferrara (Italy); Belarusian State University, Research Institute for Nuclear Problems, Minsk (Belarus); INFN, Ferrara (Italy); Kirillin, I.V. [National Science Center ' ' Kharkov Institute of Physics and Technology' ' , Akhiezer Institute for Theoretical Physics, Kharkov (Ukraine); Shul' ga, N.F. [National Science Center ' ' Kharkov Institute of Physics and Technology' ' , Akhiezer Institute for Theoretical Physics, Kharkov (Ukraine); V.N. Karazin Kharkov National University, Kharkov (Ukraine); Berra, A.; Lietti, D.; Prest, M. [Universita dell' Insubria, Como (Italy); INFN Sezione di Milano Bicocca, Milan (Italy); De Salvador, D. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Universita di Padova, Dipartimento di Fisica, Padua (Italy); Vallazza, E. [INFN Sezione di Trieste, Trieste (Italy)

    2016-02-15

    An investigation on the mechanism of relaxation of axially confined 400 GeV/c protons to planar channeling in a bent crystal was carried out at the extracted line H8 from CERN Super Proton Synchrotron. The experimental results were critically compared to computer simulations, showing a good agreement. We identified a necessary condition for the exploitation of axial confinement or its relaxation for particle beam manipulation in high-energy accelerators. We introduce the idea of using a short bent crystal, aligned with one of its main axis to the beam direction, as a beam steerer or a beam splitter with adjustable intensity in the field of particle accelerators. In particular, in the latter case, a complete relaxation from axial confinement to planar channeling takes place, resulting in beam splitting into the two strongest skew planar channels. (orig.)

  13. Thermal rate coefficients in collinear versus bent transition state reactions: the N+N{sub 2} case study

    Energy Technology Data Exchange (ETDEWEB)

    Lagana, Antonio; Faginas Lago, Noelia; Rampino, Sergio [Dipartimento di Chimica, Universita di Perugia, 06123 Perugia (Italy); Huarte-Larranaga, FermIn [Computer Simulation and Modeling Lab (CoSMoLab), Parc CientIfic de Barcelona, 08028 Barcelona (Spain); GarcIa, Ernesto [Departamento de Quimica Fisica, Universidad del PaIs Vasco, 01006 Vitoria (Spain)], E-mail: lagana05@gmail.com, E-mail: fhuarte@pcb.ub.es, E-mail: e.garcia@ehu.es

    2008-10-15

    Zero total angular momentum exact quantum calculations of the probabilities of the N+N{sub 2} reaction have been performed on the L3 potential energy surface having a bent transition state. This has allowed us to work out J-shifting estimates of the thermal rate coefficient based on the calculation of either detailed (state-to-state) or cumulative (multiconfiguration) probabilities. The results obtained are used to compare the numerical outcomes and the concurrent computational machineries of both quantum and semiclassical approaches as well as to exploit the potentialities of the J-shifting model. The implications of moving the barrier to reaction from the previously proposed collinear geometry of the LEPS to the bent one of L3 are also investigated by comparing the related detailed reactive probabilities.

  14. Two-dimensional fluid dynamics in a sharply bent channel: Laminar flow, separation bubble, and vortex dynamics

    Science.gov (United States)

    Matsumoto, Daichi; Fukudome, Koji; Wada, Hirofumi

    2016-10-01

    Understanding the hydrodynamic properties of fluid flow in a curving pipe and channel is important for controlling the flow behavior in technologies and biomechanics. The nature of the resulting flow in a bent pipe is extremely complicated because of the presence of a cross-stream secondary flow. In an attempt to disentangle this complexity, we investigate the fluid dynamics in a bent channel via the direct numerical simulation of the Navier-Stokes equation in two spatial dimensions. We exploit the absence of secondary flow from our model and systematically investigate the flow structure along the channel as a function of both the bend angle and Reynolds number of the laminar-to-turbulent regime. We numerically suggest a scaling relation between the shape of the separation bubble and the flow conductance, and construct an integrated phase diagram.

  15. 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...

  16. Radiation emission phenomena in bent silicon crystals: Theoretical and experimental studies with 120 GeV/c positrons

    International Nuclear Information System (INIS)

    Lietti, D.; Bagli, E.; Baricordi, S.; Berra, A.; Bolognini, D.; Chirkov, P.N.; Dalpiaz, P.; Della Mea, G.; De Salvador, D.; Hasan, S.; Guidi, V.; Maisheev, V.A.

    2012-01-01

    The radiation emission phenomena in bent silicon crystals have been thoroughly investigated at the CERN SPS-H4 beamline. The incoming and outgoing trajectories of charged particles impinging on a silicon strip crystal have been reconstructed by high precision silicon microstrip detectors. A spectrometer method has been exploited to measure the radiation emission spectra both in volume reflection and in channeling. The theoretical method used to evaluate the photon spectra is presented and compared with the experimental results.

  17. Når omverdenen lukkes inden for i et åbent fængsel – de indsattes perspektiv

    DEFF Research Database (Denmark)

    Abrahamsen, Marie Herping

    2018-01-01

    I artiklen præsenteres et aktionsforskningsprojekt, hvor omverdenen er blevet lukket ind i et åbent fængsel. I projektet har indsatte og folk udefra i en periode på seks måneder kunnet gå til ugentlige fritidsaktiviteter: Rytmisk kor, debataftener og yoga. Projektet tager afsæt i, at en større grad...

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

    KAUST Repository

    Rawashdeh, E.; Karam, A.; Foulds, Ian G.

    2012-01-01

    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.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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

  20. A method to align a bent crystal for channeling experiments by using quasichanneling oscillations

    Science.gov (United States)

    Sytov, A. I.; Guidi, V.; Tikhomirov, V. V.; Bandiera, L.; Bagli, E.; Germogli, G.; Mazzolari, A.; Romagnoni, M.

    2018-04-01

    A method to calculate both the bent crystal angle of alignment and radius of curvature by using only one distribution of deflection angles has been developed. The method is based on measuring of the angular position of recently predicted and observed quasichanneling oscillations in the deflection angle distribution and consequent fitting of both the radius and angular alignment by analytic formulae. In this paper this method is applied on the example of simulated angular distributions over a wide range of values of both radius and alignment for electrons. It is carried out through the example of (111) nonequidistant planes though this technique is general and could be applied to any kind of planes. In addition, the method application constraints are also discussed. It is shown by simulations that this method, being in fact a sort of beam diagnostics, allows one in a certain case to increase the crystal alignment accuracy as well as to control precisely the radius of curvature inside an accelerator tube without vacuum breaking. In addition, it speeds up the procedure of crystal alignment in channeling experiments, reducing beamtime consuming.

  1. 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.)

  2. 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

  3. Alignment and experiment of the HL-1 X-ray bent-crystal spectrometer

    International Nuclear Information System (INIS)

    Chen Jiefu; Yuan Chengji; Zhang Shuxun; Lu Jie; Yie Gaoying; Zhang Li

    1993-04-01

    An X-ray bent-crystal spectrometer, which is developed by Southwestern Institute of Physics, has been aligned and experimental on the HL-1 Tokamak device. It has been used to acquire experimental spectrum. This spectrometer has time resolution function and is a high through-put and high resolution Bragg crystal spectrometer with Johann configuration. It uses a large quartz lamina, its effective area is 11 x 5 cm 2 , with a radius of curvature of 377 cm as the dispersion element. The detector is a large size (10 x 10 cm 2 ) one-dimensional resolving multiwire proportional counter, and the spectral resolving power is R ≅ 18000. Under the injection of Ar into hydrogen plasma, the He-like Ar ion satellite spectra at some wavelength ranges are obtained. The central ion temperature has been given out from the Doppler broadening of He-like Ar x VII 3.9457 angstrom resonance line. This shows the success of spectrometer developed. The experimental results and the further improvement of this spectrometer are also discussed

  4. High-energy e- /e+ spectrometer via coherent interaction in a bent crystal

    Science.gov (United States)

    Bagli, Enrico; Guidi, Vincenzo; Howard, Alexander

    2018-01-01

    We propose a novel spectrometer based on the crystal channeling effect capable of discriminating between positive and negative particles well beyond the TeV energy scale. The atomic order of a crystalline structure generates an electrostatic field built up by all the atoms in the crystals, which confines charged particle trajectories between neighbouring atomic planes. Through such an interaction in a tiny curved crystal, the same dynamical action on the highest energy particles as that of a huge superconducting magnet is achieved. Depending on the charge sign, points of equilibrium of the oscillatory motion under channeling lie between or on atomic planes for positive and negative particles, respectively, forcing positive particles to stably oscillate far from the planes, while negative ones repeatedly cross them. The different interaction rate with atomic planes causes a tremendous discrepancy between the deflection efficiency of positive and negative particles under channeling. We suggest the use of interactions between charged particles and oriented bent crystals as a novel non-cryogenic passive charge spectrometer to aid the search for dark matter in the Universe in satellite-borne experiment. The limited angular acceptance makes this technique particularly suited for directional local sources of energetic charged particles.

  5. 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.)

  6. Monolithic photonic integrated circuit with a GaN-based bent waveguide

    Science.gov (United States)

    Cai, Wei; Qin, Chuan; Zhang, Shuai; Yuan, Jialei; Zhang, Fenghua; Wang, Yongjin

    2018-06-01

    Integration of a transmitter, waveguide and receiver into a single chip can generate a multicomponent system with multiple functionalities. Here, we fabricate and characterize a GaN-based photonic integrated circuit (PIC) on a GaN-on-silicon platform. With removal of the silicon and back wafer thinning of the epitaxial film, ultrathin membrane-type devices and highly confined suspended GaN waveguides were formed. Two suspended-membrane InGaN/GaN multiple-quantum-well diodes (MQW-diodes) served as an MQW light-emitting diode (MQW-LED) to emit light and an MQW photodiode (MQW-PD) to sense light. The optical interconnects between the MQW-LED and MQW-PD were achieved using the GaN bent waveguide. The GaN-based PIC consisting of an MQW-LED, waveguides and an MQW-PD forms an in-plane light communication system with a data transmission rate of 70 Mbps.

  7. 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.

  8. 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.

  9. Ferroelectric Nematic and Ferrielectric Smectic Mesophases in an Achiral Bent-Core Azo Compound.

    Science.gov (United States)

    Kumar, Jitendra; Prasad, Veena

    2018-03-22

    Here, we report the observation of ferroelectric nematic and ferrielectric smectic mesophases in an achiral bent-core azo compound consisting of nonsymmetrical molecules with a lateral fluoro substitution on one of the wings. These mesophases are enantiotropic in nature with fairly low transition temperatures and wide mesophase ranges. The liquid crystalline properties of this compound are investigated using polarizing optical microscope, differential scanning calorimeter, X-ray diffraction, and electro-optical studies. As revealed by X-ray diffraction measurements, the nematic mesophase is composed of skewed cybotactic clusters and, in the smectic mesophase, the molecules are tilted with respect to the layer normal. The polar order in these mesophases was confirmed by the electro-optical switching and dielectric spectroscopy measurements. The dielectric study in the nematic mesophase shows a single relaxation process at low frequency ( f interest is the fact that the smectic phase exhibits a field induced ferrielectric state, which can be exploited for designing of the potential optical devices due to multistate switching.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mazzolari, Andrea, E-mail: mazzolari@fe.infn.it [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1/c, 44122 Ferrara (Italy); INFN, Section of Ferrara (Italy); Camattari, Riccardo; Bellucci, Valerio; Paternò, Gianfranco [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1/c, 44122 Ferrara (Italy); INFN, Section of Ferrara (Italy); Scian, Carlo; Mattei, Giovanni [University of Padova, Department of Physics and Astronomy Galileo Galilei (Italy); Guidi, Vincenzo [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1/c, 44122 Ferrara (Italy); INFN, Section of Ferrara (Italy)

    2015-07-15

    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.

  11. 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...

  12. 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.

  13. 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...

  14. 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.)

  15. Numerical analysis of three-dimensional turbulent flow in a 90deg bent tube by algebraic Reynolds stress model

    International Nuclear Information System (INIS)

    Sugiyama, Hitoshi; Akiyama, Mitsunobu; Shinohara, Yasunori; Hitomi, Daisuke

    1997-01-01

    A numerical analysis has been performed for three dimensional developing turbulent flow in a 90deg bent tube with straight inlet and outlet sections by an algebraic Reynolds stress model. To our knowledge, very little has been reported about detailed comparison between calculated results and experimental data containing Reynolds stresses. In calculation, an algebraic Reynolds stress model together with a boundary-fitted coordinate system is applied to a 90deg bent tube in order to solve anisotropic turbulent flow precisely. The calculated results display comparatively good agreement with the experimental data of time averaged velocity and secondary vectors. In addition, the present method predicts as a characteristic feature that the intensity of secondary flow near the inner wall is increased immediately downstream from the bend outlet by the pressure gradient. With regard to comparison of Reynolds stresses, the present method is able to reproduce well the distributions of streamwise normal stress and shear stress defined streamwise and radial velocity fluctuation except for the shear stress defined streamwise and circumferential velocity fluctuation. The present calculation has been found to simulate many features of the developing flow in bent tube satisfactorily, but it has a tendency to underpredict the Reynolds stresses. (author)

  16. 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

  17. Combining evolutionary algorithms with oblique decision trees to detect bent-double galaxies

    Science.gov (United States)

    Cantu-Paz, Erick; Kamath, Chandrika

    2000-10-01

    Decision tress have long been popular in classification as they use simple and easy-to-understand tests at each node. Most variants of decision trees test a single attribute at a node, leading to axis- parallel trees, where the test results in a hyperplane which is parallel to one of the dimensions in the attribute space. These trees can be rather large and inaccurate in cases where the concept to be learned is best approximated by oblique hyperplanes. In such cases, it may be more appropriate to use an oblique decision tree, where the decision at each node is a linear combination of the attributes. Oblique decision trees have not gained wide popularity in part due to the complexity of constructing good oblique splits and the tendency of existing splitting algorithms to get stuck in local minima. Several alternatives have been proposed to handle these problems including randomization in conjunction wiht deterministic hill-climbing and the use of simulated annealing. In this paper, we use evolutionary algorithms (EAs) to determine the split. EAs are well suited for this problem because of their global search properties, their tolerance to noisy fitness evaluations, and their scalability to large dimensional search spaces. We demonstrate our technique on a synthetic data set, and then we apply it to a practical problem from astronomy, namely, the classification of galaxies with a bent-double morphology. In addition, we describe our experiences with several split evaluation criteria. Our results suggest that, in some cases, the evolutionary approach is faster and more accurate than existing oblique decision tree algorithms. However, for our astronomical data, the accuracy is not significantly different than the axis-parallel trees.

  18. 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

  19. Development of a bent Laue beam-expanding double-crystal monochromator for biomedical X-ray imaging

    International Nuclear Information System (INIS)

    Martinson, Mercedes; Samadi, Nazanin; Belev, George; Bassey, Bassey; Lewis, Rob; Aulakh, Gurpreet; Chapman, Dean

    2014-01-01

    A bent Laue beam-expanding double-crystal monochromator was developed and tested at the Biomedical Imaging and Therapy beamline at the Canadian Light Source. The expander will reduce scanning time for micro-computed tomography and allow dynamic imaging that has not previously been possible at this beamline. The Biomedical Imaging and Therapy (BMIT) beamline at the Canadian Light Source has produced some excellent biological imaging data. However, the disadvantage of a small vertical beam limits its usability in some applications. Micro-computed tomography (micro-CT) imaging requires multiple scans to produce a full projection, and certain dynamic imaging experiments are not possible. A larger vertical beam is desirable. It was cost-prohibitive to build a longer beamline that would have produced a large vertical beam. Instead, it was proposed to develop a beam expander that would create a beam appearing to originate at a source much farther away. This was accomplished using a bent Laue double-crystal monochromator in a non-dispersive divergent geometry. The design and implementation of this beam expander is presented along with results from the micro-CT and dynamic imaging tests conducted with this beam. Flux (photons per unit area per unit time) has been measured and found to be comparable with the existing flat Bragg double-crystal monochromator in use at BMIT. This increase in overall photon count is due to the enhanced bandwidth of the bent Laue configuration. Whilst the expanded beam quality is suitable for dynamic imaging and micro-CT, further work is required to improve its phase and coherence properties

  20. 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

  1. A Monte Carlo simulation on critical current distribution of bent-damaged multifilamentary Bi2223 composite tape

    International Nuclear Information System (INIS)

    Ochiai, S.; Okuda, H.; Fujimoto, M.; Shin, J.K.; Oh, S.S.; Ha, D.W.

    2011-01-01

    We simulate critical current distribution of bent-damaged Bi2223 composite tape. We use a Monte Carlo method and a damage evolution model for simulation. With the present simulation approach, experimental results are described well. Critical current distribution stems mainly from difference in damage evolution. It was attempted to reproduce the measured critical current (I c ) distributions of the Bi2223 composite tape bent by 0-0.833% by simulation. Simulation was carried out with a Monte Carlo method in combination with a model that correlates the critical current to damage evolution. Two variables that differ from specimen to specimen were input in the simulation. One was the damage strain parameter, with which the difference in extent of damage among specimens was expressed. Another was the original critical current (I c0 ) values at zero bending strain. With the present simulation approach, the measured distributions of critical current at various bending strains, and the measured variations of average and coefficient of variation of critical current values with increasing bending strain were reproduced well.

  2. 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.

  3. 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.

  4. In-situ growth of AuNPs on WS2@U-bent optical fiber for evanescent wave absorption sensor

    Science.gov (United States)

    Zhang, Suzhen; Zhao, Yuefeng; Zhang, Chao; Jiang, Shouzhen; Yang, Cheng; Xiu, Xianwu; Li, Chonghui; Li, Zhen; Zhao, Xiaofei; Man, Baoyuan

    2018-05-01

    The sensitivity of the evanescent wave absorption sensor is always a hot topic which has been attracted researchers' discussion. It is still a challenge for developing the effective sensor to sensitively detect some biochemical molecules solution in a simple and low-cost way. In this paper, an evanescent wave absorption (EWA) sensor has been presented based on the U-bent multimode fiber coated with tungsten disulfide (WS2) film and in-situ growth of gold nanoparticles (AuNPs) for the detection of ethanol solution and sodium chloride (NaCl) solution. Benefitted from the effective light coupling produced between U-bent probe and AuNPs, we attained the optimal size of the AuNPs by changing the reaction time between WS2 and tetrachloroauric acid (HAuCl4). With the AuNPs/WS2@U-bent optical fiber, we discussed the behaviors of EWA sensor, such as sensitivity, reproducibility, fast response-recovery time and stability. The sensitivity (△A/△C) of the proposed AuNPs/WS2@U-bent optical fiber EWA sensor is 0.65 for the detection of the ethanol solution. Besides, the AuNPs/WS2@U-bent optical fiber EWA sensor exhibits high sensitivity in detection of the sodium chloride (NaCl), which can reach 1.5 when the proposed sensor was immersed into NaCl solution. Our work demonstrates that the U-bent optical fiber EWA sensor may have promising applications in testing the solution of concentration.

  5. 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

  6. Alternating twist structures formed by electroconvection in the nematic phase of an achiral bent-core molecule.

    Science.gov (United States)

    Tanaka, Shingo; Dhara, Surajit; Sadashiva, B K; Shimbo, Yoshio; Takanishi, Yoichi; Araoka, Fumito; Ishikawa, Ken; Takezoe, Hideo

    2008-04-01

    We report an unusual electroconvection in the nematic phase of a bent-core liquid crystal. In a voltage-frequency diagram, two frequency regions exhibiting prewavy stripe patterns were found, as reported by Wiant We found that these stripes never show extinction dark when cells were rotated under crossed polarizers. Based on the color interchange in between neighboring stripes by the rotation of the cells or an analyzer, twisted molecular orientation is suggested; i.e., the directors are alternately twisted from the top to the bottom surfaces with a pretilt angle in adjacent stripes, which is an analogue of the twisted (splayed) structure observed in surface-stabilized ferroelectric liquid crystal cells. The transmittance spectra calculated using the 4x4 matrix method from the model structure are consistent with the experimental observation.

  7. Optofluidic refractive-index sensors employing bent waveguide structures for low-cost, rapid chemical and biomedical sensing.

    Science.gov (United States)

    Liu, I-Chen; Chen, Pin-Chuan; Chau, Lai-Kwan; Chang, Guo-En

    2018-01-08

    We propose and develop an intensity-detection-based refractive-index (RI) sensor for low-cost, rapid RI sensing. The sensor is composed of a polymer bent ridge waveguide (BRWG) structure on a low-cost glass substrate and is integrated with a microfluidic channel. Different-RI solutions flowing through the BRWG sensing region induce output optical power variations caused by optical bend losses, enabling simple and real-time RI detection. Additionally, the sensors are fabricated using rapid and cost-effective vacuum-less processes, attaining the low cost and high throughput required for mass production. A good RI solution of 5.31 10 -4 × RIU -1 is achieved from the RI experiments. This study demonstrates mass-producible and compact RI sensors for rapid and sensitive chemical analysis and biomedical sensing.

  8. Geometrical and wave-optical effects on the performance of a bent-crystal dispersive X-ray spectrometer

    International Nuclear Information System (INIS)

    Sutter, J.P.; Amboage, M.; Hayama, S.; Diaz-Moreno, S.

    2010-01-01

    The X-ray focusing properties of a bent single crystal diffracting in Bragg geometry are discussed. First, it is assumed that a polychromatic point source is focused to a point image. The elliptical arc that the crystal must trace and the aberrations caused by bending the crystal cylindrically are derived from the ray paths. For a source of finite size, the magnification is found to vary over the crystal's length, so that rays of different wavelength produce images of different size. More realistic treatments of penetration and diffraction are performed with spherical monochromatic incident waves, using Takagi-Taupin calculations to create the diffracted wave and the Fresnel integral to trace the diffracted wave's evolution. Such 'wave-optical' calculations on a symmetric Si (1 1 1) crystal with 7 keV X-rays predict beam sizes different from those found in ray traces. Optimal sample and detector placement therefore requires wave effects to be considered.

  9. 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.

  10. 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.

  11. Experimental demonstration of a simple displacement sensor based on a bent single-mode–multimode–single-mode fiber structure

    International Nuclear Information System (INIS)

    Wu, Qiang; Semenova, Yuliya; Wang, Pengfei; Hatta, Agus Muhamad; Farrell, Gerald

    2011-01-01

    A simple displacement sensor based on a bent single-mode–multimode–single-mode (SMS) fiber structure is proposed and experimentally investigated. The sensor offers a wider displacement range, not limited by the risk of fiber breakage, as well as a three-fold increase in displacement sensitivity by comparison with a straight SMS structure sensor. This sensor can be interrogated by either an optical spectral analyzer (OSA) or a ratiometric interrogation system: (1) if interrogated by an OSA assuming a resolution of 1 pm, it has a sensitivity of 28.2 nm for a displacement measurement range from 0 to 280 µm; (2) if interrogated by a ratiometric interrogation system, it has worst and best case resolutions of 556 and 38 nm, respectively, for a displacement measurement range from 0 to 520 µm

  12. Studying the highly bent spectra of FR II-type radio galaxies with the KDA EXT model

    Science.gov (United States)

    Kuligowska, Elżbieta

    2018-04-01

    Context. The Kaiser, Dennett-Thorpe & Alexander (KDA, 1997, MNRAS, 292, 723) EXT model, that is, the extension of the KDA model of Fanaroff & Riley (FR) II-type source evolution, is applied and confronted with the observational data for selected FR II-type radio sources with significantly aged radio spectra. Aim. A sample of FR II-type radio galaxies with radio spectra strongly bent at their highest frequencies is used for testing the usefulness of the KDA EXT model. Methods: The dynamical evolution of FR II-type sources predicted with the KDA EXT model is briefly presented and discussed. The results are then compared to the ones obtained with the classical KDA approach, assuming the source's continuous injection and self-similarity. Results: The results and corresponding diagrams obtained for the eight sample sources indicate that the KDA EXT model predicts the observed radio spectra significantly better than the best spectral fit provided by the original KDA model.

  13. 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.)

  14. Unusual polarity-dependent patterns in a bent-core nematic liquid crystal under low-frequency ac field.

    Science.gov (United States)

    Xiang, Ying; Zhou, Meng-jie; Xu, Ming-Ya; Salamon, Péter; Éber, Nándor; Buka, Ágnes

    2015-04-01

    Electric-field-induced patterns of diverse morphology have been observed over a wide frequency range in a recently synthesized bent-core nematic (BCN) liquid crystal. At low frequencies (up to ∼25 Hz), the BCN exhibited unusual polarity-dependent patterns. When the amplitude of the ac field was enhanced, these two time-asymmetrical patterns turned into time-symmetrical prewavylike stripes. At ac frequencies in the middle-frequency range (∼50-3000 Hz), zigzag patterns were detected whose obliqueness varied with the frequency. Finally, if the frequency was increased above 3 kHz, the zigzag pattern was replaced by another, prewavylike pattern, whose threshold voltage depended on the frequency; however, the wave vector did not. For a more complete characterization, material parameters such as elastic constants, dielectric permittivities, and the anisotropy of the diamagnetic susceptibility were also determined.

  15. Comunidad bentónica del chanque Concholepas concholepas en el litoral de Tacna, Perú. 2007

    OpenAIRE

    Castillo Rojas, Carlos Raúl; Tejada Cáceres, Alex; González Vargas, Alejandro; Pastor Cuba, Ruslan; Lucero Pérez, Stevens

    2012-01-01

    El estudio se realizó en octubre 2007, en el banco natural Meca-Las Lozas al norte de la Región Tacna. La longitud peristomal de C. concholepas varió de 27 a 109 mm, promedio 53,96 mm y moda principal 54 mm; 98,8% de los ejemplares menores a la talla comercial; proporción sexual de 1,0♂♂:1,1♀♀; IGS de 1,53%. Población estimada en 4.821.922 individuos; con densidad media de 4 ind/m2. Biomasa total estimada en 254,1 t, biomasa media de 0,218 kg/m². La macrofauna bentónica de invertebrados as...

  16. 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.

  17. 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

  18. Cyrtodactylus tahuna sp. nov., a new bent-toed gecko (Reptilia: Squamata: Gekkonidae) from Sangihe Island, North Sulawesi, Indonesia.

    Science.gov (United States)

    Riyanto, Awal; Arida, Evy; Koch, AndrÉ

    2018-03-21

    Cyrtodactylus tahuna sp. nov. is a new bent-toed gecko we describe herein based on three specimens from Sangihe, North Sulawesi, Indonesia, an island situated in the northern corner of the Wallacea biodiversity hotspot. The new species is a medium sized Cyrtodactylus with a SVL of up to 78.5 mm in adult males and 79.2 mm in females. It is easily distinguished from all but four species (Cyrtodactylus fumosus, C. halmahericus, C. papuensis, and C. tambora) occurring on Sulawesi as well as in the Moluccas and the Lesser Sunda Islands, by possessing precloacal and femoral pores, enlarged precloacal and femoral scales, and lacking transversely enlarged median subcaudal scales. It differs from C. fumosus by the presence of tubercles on the ventrolateral fold, more unkeeled dorsal tubercles (19 versus 4-7) and a pit-like precloacal depression in males (versus groove in males); from C. halmahericus by presence of smaller scales between the enlarged precloacal and femoral scales (versus a continuous series of enlarged precloacofemoral scales) and a continuous series of precloacofemoral pores, as well as the presence of a pit-like precloacal depression in male (versus groove in males), from C. papuensis by possessing a pit-like precloacal depression in males (versus a groove ); and from C. tambora by the presence of tubercles on the dorsal surface of the brachium and the possession of femoral pores. Our contribution, along with several other recent descriptions of bent-toad geckos from Southeast Asia, clearly indicating that the diversity of the genus Cyrtodactylus in Indonesia is still underestimated.

  19. 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.

  20. Análisis de la biodiversidad de macroinvertebrados bentónicos del río Cunas mediante indicadores ambientales, Junín-Perú

    Directory of Open Access Journals (Sweden)

    María Custodio Villanueva

    2016-01-01

    Full Text Available El objetivo de la investigación fue analizar el estado de la biodiversidad de macroinvertebrados bentónicos del río Cunas mediante indicadores ambientales. Se definieron tres sectores de muestreo en dos épocas contrastantes. La valoración de las presiones antrópicas se realizó mediante la determinación de la carga de DBO5 aportada por aguas residuales. Se colectaron muestras de agua para la determinación de nitratos, fosfatos y coliformes termotolerantes. Los indicadores medidos in situ fueron: oxígeno disuelto, sólidos totales disueltos, conductividad, temperatura, pH y turbidez. Las muestras de macroinvertebrados bentónicos se colectaron utilizando una red Surber con malla de 250 μm de abertura. Los resultados de la presión antrópica sobre los macroinvertebrados bentónicos fueron: media de DBO5 de aguas residuales de la actividad piscícola 7,70 mg/L, de la actividad pecuaria 869 mg/L y de la actividad urbana 428,3 mg/L. Los resultados de los indicadores físico-químicos y bacteriológicos mostraron diferencias significativas para la conductividad, temperatura y sólidos totales disueltos. Se identificaron cuatro phyla, siete clases, 12 órdenes y 26 familias de macroinvertebrados bentónicos. Se concluye que las descargas de aguas residuales de las actividades pecuaria y urbana son presiones antrópicas significativas sobre la biodiversidad de macroinvertebrados bentónicos. Los indicadores fisicoquímicos y bacteriológicos de la calidad del agua determinados, según sector y época de muestreo, están en el rango de los ECA para agua de ríos de la sierra. La riqueza, abundancia y diversidad de macroinvertebrados bentónicos, según sector y época de muestreo, presentaron diferencias significativas.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. Effects of molecular chirality on self-assembly and switching in liquid crystals at the cross-over between rod-like and bent shapes.

    Science.gov (United States)

    Ocak, Hale; Poppe, Marco; Bilgin-Eran, Belkız; Karanlık, Gürkan; Prehm, Marko; Tschierske, Carsten

    2016-09-21

    A bent-core compound derived from a 4-cyanoresorcinol core unit with two terephthalate based rod-like wings and carrying chiral 3,7-dimethyloctyloxy side chains has been synthesized in racemic and enantiomerically pure form and characterized by polarizing microscopy, differential scanning calorimetry, X-ray diffraction and electro-optical investigations to study the influence of molecular chirality on the superstructural chirality and polar order in lamellar liquid crystalline phases. Herein we demonstrate that the coupling of molecular chirality with superstructural layer chirality in SmCsPF domain phases (forming energetically distinct diastereomeric pairs) can fix the tilt direction and thus stabilize synpolar order, leading to bistable ferroelectric switching in the SmC* phases of the (S)-enantiomer, whereas tristable modes determine the switching of the racemate. Moreover, the mechanism of electric field induced molecular reorganization changes from a rotation around the molecular long axis in the racemate to a rotation on the tilt-cone for the (S)-enantiomer. At high temperature the enantiomer behaves like a rod-like molecule with a chirality induced ferroelectric SmC* phase and an electroclinic effect in the SmA'* phase. At reduced temperature sterically induced polarization, due to the bent molecular shape, becomes dominating, leading to much higher polarization values, thus providing access to high polarization ferroelectric materials with weakly bent compounds having only "weakly chiral" stereogenic units. Moreover, the field induced alignment of the SmCsPF(()*()) domains gives rise to a special kind of electroclinic effect appearing even in the absence of molecular chirality. Comparison with related compounds indicates that the strongest effects of chirality appear for weakly bent molecules with a relatively short coherence length of polar order, whereas for smectic phases with long range polar order the effects of the interlayer interfaces can override

  6. 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.)

  7. Simulation of channeling and radiation of 855 MeV electrons and positrons in a small-amplitude short-period bent crystal

    Energy Technology Data Exchange (ETDEWEB)

    Korol, Andrei V., E-mail: korol@mbnexplorer.com [MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany); Bezchastnov, Victor G. [A.F. Ioffe Physical-Technical Institute, Politechnicheskaya Str. 26, 194021 St. Petersburg (Russian Federation); Peter the Great St. Petersburg Polytechnic University, Politechnicheskaya 29, 195251 St. Petersburg (Russian Federation); Sushko, Gennady B.; Solov’yov, Andrey V. [MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main (Germany)

    2016-11-15

    Channeling and radiation are studied for the relativistic electrons and positrons passing through a Si crystal periodically bent with a small amplitude and a short period. Comprehensive analysis of the channeling process for various bending amplitudes is presented on the grounds of numerical simulations. The features of the channeling are highlighted and elucidated within an analytically developed continuous potential approximation. The radiation spectra are computed and discussed.

  8. Profile measurement of a bent neutron mirror using an ultrahigh precision non-contact measurement system with an auto focus laser probe

    International Nuclear Information System (INIS)

    Morita, S; Guo, J; Yamagata, Y; Yamada, N L; Torikai, N; Takeda, S; Furusaka, M

    2016-01-01

    A bent neutron mirror has been considered as one of the best solutions for focusing neutron beams from the viewpoint of cost-benefit performance. Although the form deviation of the bent profile is expected because of the large spot size, it is difficult to measure due to its geometric limitation. Here, we propose a non-contact measurement system using an auto focus (AF) laser probe on an ultrahigh precision machine tool to precisely evaluate the form deviation of the bent mirror. The AF laser probe is composed of a diode laser, a position sensitive sensor, a charge-coupled device (CCD) camera and a microscope objective lens which is actuated by an electromagnetic motor with 1 nm resolution for position sensing and control. The sensor enables a non-contact profile measurement of a high precision surface without any surface damage in contrast with contact-type ultrahigh precision coordinate measurement machines with ruby styli. In the on-machine measurement system, a personal computer simultaneously acquires a displacement signal from the AF laser probe and 3-axis positional coordinates of the ultrahigh machine tool branched between the linear laser scales and the numerical controller. The acquisition rate of the 4-axis positional data in 1 nm resolution is more than 10 Hz and the simultaneity between the axes is negligible. The profile of a neutron bent mirror was measured from a transparent side using the developed system, and the result proves that the form deviation of the mirror enlarged the the spot size of focused neuron beam. (paper)

  9. 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.

  10. Bis(arene) actinide sandwich complexes, (η6-C6H3R3)2An: Linear or bent?

    International Nuclear Information System (INIS)

    Li, J.; Bursten, B.E.

    1999-01-01

    The syntheses of the sandwich complexes ferrocene, (η 5 -C 5 H 5 ) 2 -Fe, in 1951 and uranocene, (η 8 -C 8 H 8 ) 2 U, in 1968 ushered in the modern eras of organotransition metal and organoactinide chemistry, respectively. Ferrocene and uranocene are examples of linear sandwich complexes, that is, those in which the (ring centroid)-M-(ring centroid) angle (denoted θ) is 180 degree. In the case of (η 5 -C 5 H 5 ) 2 M chemistry, a number of bent (θ 2 An (An = Th-Am) and (η 6 -C 6 H 3 R 3 ) 2 An (An = Th, U, Pu; R = Me, t Bu) obtained by using local density approximation (LDA) and Perdew-Wang (PW91) gradient-corrected relativistic density functional theory (DFT) methods. These DFT methods are found to be able to reproduce the experimental geometries and vibrational frequencies of organoactinide complexes with satisfactory accuracy. The (TTB) 2 An calculations that are reported here are, to date, the largest full geometry optimizations to be carried out on an actinide system

  11. 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.

  12. 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.

  13. Bent paths of a positive streamer and a cathode-directed spark leader in diffuse discharges preionized by runaway electrons

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Cheng; Shao, Tao, E-mail: st@mail.iee.ac.cn; Wang, Ruixue; Yan, Ping [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China); Tarasenko, Viktor F.; Beloplotov, Dmitry V.; Lomaev, Mikhail I.; Sorokin, Dmitry A. [Institute of High Current Electronics, Russian Academy of Science, Tomsk 634055 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk 634050 (Russian Federation)

    2015-03-15

    Diffuse discharges preionized by runaway electrons can produce large-area homogeneous discharges at elevated pressures, which is an intriguing phenomenon in the physics of pulsed discharges. In this paper, runaway-electron-preionized diffuse discharge (REP DD) was obtained in a wide pressure range (0.05–0.25 MPa), and under certain conditions a positive streamer and a cathode-directed spark leader could be observed to propagate at some angles to the applied (background) electric field lines. For a 16-mm gap at an air pressure of 0.08–0.1 MPa, the percentage of pulses in which such propagation is observed is about 5%–50% of their total number, and in the other pulses such bent paths could not be observed because there is even no streamer or cathode-directed spark leader in diffuse discharges. In our opinion, such propagation of the positive streamer and the cathode-directed spark leader at some angle to the background electric field lines owes to different increase rates of the electron density in different regions of the discharge volume under REP DD conditions. Therefore, during the formation of a REP DD, the increase of the electron density is inhomogeneous and nonsimultaneous, resulting in an electron density gradient at the ionization wave front.

  14. Bent paths of a positive streamer and a cathode-directed spark leader in diffuse discharges preionized by runaway electrons

    International Nuclear Information System (INIS)

    Zhang, Cheng; Shao, Tao; Wang, Ruixue; Yan, Ping; Tarasenko, Viktor F.; Beloplotov, Dmitry V.; Lomaev, Mikhail I.; Sorokin, Dmitry A.

    2015-01-01

    Diffuse discharges preionized by runaway electrons can produce large-area homogeneous discharges at elevated pressures, which is an intriguing phenomenon in the physics of pulsed discharges. In this paper, runaway-electron-preionized diffuse discharge (REP DD) was obtained in a wide pressure range (0.05–0.25 MPa), and under certain conditions a positive streamer and a cathode-directed spark leader could be observed to propagate at some angles to the applied (background) electric field lines. For a 16-mm gap at an air pressure of 0.08–0.1 MPa, the percentage of pulses in which such propagation is observed is about 5%–50% of their total number, and in the other pulses such bent paths could not be observed because there is even no streamer or cathode-directed spark leader in diffuse discharges. In our opinion, such propagation of the positive streamer and the cathode-directed spark leader at some angle to the background electric field lines owes to different increase rates of the electron density in different regions of the discharge volume under REP DD conditions. Therefore, during the formation of a REP DD, the increase of the electron density is inhomogeneous and nonsimultaneous, resulting in an electron density gradient at the ionization wave front

  15. Field-induced optically isotropic state in bent core nematic liquid crystals: unambiguous proof of field-induced optical biaxiality

    International Nuclear Information System (INIS)

    Elamain, Omaima; Komitov, Lachezar; Hegde, Gurumurthy; Fodor-Csorba, Katalin

    2013-01-01

    The behaviour of bent core (BC) nematic liquid crystals was investigated under dc applied electric field. The optically isotropic state of a sample containing BC nematic was observed under application of low dc electric fields. The quality of the dark state when the sample was inserted between two crossed polarizers was found to be superb and it did not change when rotating the sample between the polarizers. The coupling between the net molecular dipole moment and the applied dc electric field was considered as the origin of the out-of-plane switching of the BC molecules resulting in switching from the field-off bright state to the field-on dark state. The field-induced optically isotropic state is an unambiguous proof of the field-induced biaxiality in the BC nematic liquid crystal. A simple model explaining the appearance of the isotropic optical state in BC nematics and the switching of the sample slow axis between three mutually orthogonal directions under dc applied electric field is proposed. (paper)

  16. 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.

  17. 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.

  18. Manufacturing and characterization of bent silicon crystals for studies of coherent interactions with negatively charged particles beams

    Energy Technology Data Exchange (ETDEWEB)

    Germogli, G.; Mazzolari, A.; Bandiera, L.; Bagli, E.; Guidi, V.

    2015-07-15

    Efficient steering of GeV-energy negatively charged particle beams was demonstrated to be possible with a new generation of thin bent silicon crystals. Suitable crystals were produced at the Sensor Semiconductor Laboratory of Ferrara starting from Silicon On Insulator wafers, adopting proper revisitation of silicon micromachining techniques such as Low Pressure Chemical Vapor Deposition, photolithography and anisotropic chemical etching. Mechanical holders, which allow to properly bend the crystal and to reduce unwanted torsions, were employed. Crystallographic directions and crystal holder design were optimized in order to excite quasi-mosaic effect along (1 1 1) planes. Prior to exposing the crystal to particle beams, a full set of characterizations were performed. Infrared interferometry was used to measure crystal thickness with high accuracy. White-light interferometry was employed to characterize surface deformational state and its torsion. High-resolution X-rays diffraction was used to precisely measure crystal bending angle along the beam. Manufactured crystals were installed and tested at the MAMI MAinz MIcrotron to steer sub-GeV electrons, and at SLAC to deflect an electron beam in the 1 to 10 GeV energy range.

  19. 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.

  20. 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

  1. Sample-length dependence of the critical current of slightly and significantly bent-damaged Bi2223 superconducting composite tape

    International Nuclear Information System (INIS)

    Ochiai, S; Fujimoto, M; Okuda, H; Oh, S S; Ha, D W

    2007-01-01

    The local critical current along a sample length is different from position to position in a long sample, especially when the sample is damaged by externally applied strain. In the present work, we attempted to reveal the relation of the distribution of the local critical current to overall critical current and the sample-length dependence of critical current for slightly and significantly damaged Bi2223 composite tape samples. In the experiment, 48 cm long Bi2223 composite tape samples, composed of 48 local elements with a length of 1 cm and 8 parts with a length 6 cm, were bent by 0.37 and 1.0% to cause slight and significant damage, respectively. The V-I curve, critical current (1 μV cm -1 criterion) and n value were measured for the overall sample as well as for the local elements and parts. It was found that the critical current distributions of the 1 cm elements at 0.37 and 1.0% bending strains are described by the three-parameter- and bimodal Weibull distribution functions, respectively. The critical current of a long sample at both bending strains could be described well by substituting the distributed critical current and n value of the short elements into the series circuit model for voltage generation. Also the measured relation of average critical current to sample length could be reproduced well in the computer by a Monte Carlo simulation method. It was shown that the critical current and n value decrease with increasing sample length at both bending strains. The extent of the decrease in critical current with sample length is dependent on the criterion of the critical current; the critical current decreases only slightly under the 1 μV cm -1 criterion which is not damage-sensitive, while it decreases greatly with increasing sample length under damage-sensitive criteria such as the 1 μV one

  2. Theoretical and experimental study of bent fully aperiodic large-pitch fibers for enhancing the high-order modes delocalization

    Science.gov (United States)

    du Jeu, Rémi; Dauliat, Romain; Darwich, Dia; Auguste, Jean-Louis; Benoît, Aurélien; Leconte, Baptiste; Malleville, Marie-Alicia; Jamier, Raphaël.; Schuster, Kay; Roy, Philippe

    2018-02-01

    The power scaling of fiber lasers and amplifiers has triggered an extensive development of large-mode area fibers among which the most promising are the distributed mode filtering fibers and the large-pitch fibers. These structures enable for an effective higher-order modes delocalization and subsequently a singlemode emission. An interesting alternative consists in using the fully-aperiodic large-pitch fibers, into which the standard air-silica photonic crystal cladding is replaced by an aperiodic pattern made of solid low-index inclusions cladding. However, in such a structure, the core and the background cladding material surrounding it must have rigorously the same refractive index. Current synthesis processes and measurement techniques offer respectively a maximum resolution of 5×10-4 and 1×10-4 while the indexmatching must be as precise as 1×10-5 . Lately a gain material with a refractive index 1.5×10-4 higher than that of the background cladding material was fabricated, thus re-confining the first higher-order modes in the core. A numerical study is carried out on the benefit of bending such fully-aperiodic fiber to counteract this phenomenon. Optimized bending axis and radius have been determined. Experiments are done in a laser cavity operating at 1030 nm using an 88cm-long 51μm core diameter ytterbium-doped fiber. Results demonstrate an improvement of the M2 from 1.7 when the fiber is kept straight to 1.2 when it is bent with a 100 to 60 cm bend radius. These primary results are promising for future power scaling.

  3. Ferroelectric response in an achiral non-symmetric bent liquid crystal:C{sub 12}C{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Subrahmanyam, S.V.; Chalapathi, P.V. [Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University Kakinada, Kakinada 533003 (India); Mahabaleshwara, S.; Srinivasulu, M. [Department of Chemistry, Manipal Institute of Technology, Manipal University, Manipal 576104 (India); George, A.K. [Department of Physics, College of Sciences, Sultan Qaboos University, PO Box-36, PC-123, Muscat (Oman); Potukuchi, D.M., E-mail: potukuchidm@yahoo.com [Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University Kakinada, Kakinada 533003 (India)

    2014-10-01

    An achiral Non-Symmetric Bent Liquid Crystal (BLC) with a Oxadiazole based hetero cyclic central moiety, abbreviated as C{sub 12}C{sub 10} viz., dodecyl[4-{5-(4′-decyloxy)biphenyl-4-yl}-1,2,4-oxadiazol-3-yl]benzoate, exhibiting FerroElectric (FE) response is reported. Product is confirmed by {sup 1}H NMR, {sup 13}C NMR and elemental analysis. Characterization of BLC phases is carried out by Polarized Optical Microscopy (POM), Differential Scanning Calorimetry (DSC), Spontaneous Polarization (P{sub S}) and Low Frequency (10 Hz–10 MHz) Dielectric Relaxation studies. C{sub 12}C{sub 10} exhibits enantiotropic LC SmA, FE B{sub 2}, SmG, SmE phase variance. I–SmA, B{sub 2}–SmG and SmG–SmE transitions are of first order nature. FE B{sub 2} phases exhibits a moderate P{sub S} of ∼80 nC cm{sup −2}. B{sub 2} phase exhibits Curie–Weiss behavior to confirm FE nature. Off-centered low frequency (KHz) dispersion infers a scissor mode and a high frequency (MHz) mode to reflect the distinct time-scale response. Dielectric Dispersion is relatively susceptible in lower frequency KHz region. Arrhenius shift in Relaxation Frequency (f{sub R}) infers higher activation energy (E{sub a}) in non-FE phases for HF mode and lower value for KHz mode. Trends of f{sub R}, dielectric strength Δε, α-parameter and E{sub a} are discussed in view of the data reported in other LC compounds.

  4. 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.

  5. Pre-bent instruments used in single-port laparoscopic surgery versus conventional laparoscopic surgery: comparative study of performance in a dry lab.

    Science.gov (United States)

    Miernik, Arkadiusz; Schoenthaler, Martin; Lilienthal, Kerstin; Frankenschmidt, Alexander; Karcz, Wojciech Konrad; Kuesters, Simon

    2012-07-01

    Different types of single-incision laparoscopic surgery (SILS) have become increasingly popular. Although SILS is technically even more challenging than conventional laparoscopy, published data of first clinical series seem to demonstrate the feasibility of these approaches. Various attempts have been made to overcome restrictions due to loss of triangulation in SILS by specially designed SILS-specific instruments. This study involving novices in a dry lab compared task performances between conventional laparoscopic surgery (CLS) and single-port laparoscopic surgery (SPLS) using newly designed pre-bent instruments. In this study, 90 medical students without previous experience in laparoscopic techniques were randomly assigned to undergo one of three procedures: CLS, SPLS using two pre-bent instruments (SPLS-pp), or SPLS using one pre-bent and one straight laparoscopic instrument (SPLS-ps). In the dry lab, the participants performed four typical laparoscopic tasks of increasing difficulty. Evaluation included performance times or number of completed tasks within a given time frame. All performances were videotaped and evaluated for unsuccessful attempts and unwanted interactions of instruments. Using subjective questionnaires, the participants rated difficulties with two-dimensional vision and coordination of instruments. Task performances were significantly better in the CLS group than in either SPLS group. The SPLS-ps group showed a tendency toward better performances than the SPLS-pp group, but the difference was not significant. Video sequences and participants` questionnaires showed instrument interaction as the major problem in the single-incision surgery groups. Although SILS is feasible, as shown in clinical series published by laparoscopically experienced experts, SILS techniques are demanding due to restrictions that come with the loss of triangulation. These can be compensated only partially by currently available SILS-designed instruments. The future of

  6. Análisis de la biodiversidad de macroinvertebrados bentónicos del río Cunas mediante indicadores ambientales, Junín-Perú

    OpenAIRE

    María Custodio Villanueva; Fernán Cosme Chanamé Zapata

    2016-01-01

    El objetivo de la investigación fue analizar el estado de la biodiversidad de macroinvertebrados bentónicos del río Cunas mediante indicadores ambientales. Se definieron tres sectores de muestreo en dos épocas contrastantes. La valoración de las presiones antrópicas se realizó mediante la determinación de la carga de DBO5 aportada por aguas residuales. Se colectaron muestras de agua para la determinación de nitratos, fosfatos y coliformes termotolerantes. Los indicadores medidos in situ fuero...

  7. Desarrollo de una herramienta de vigilancia ambiental ciudadana basada en macroinvertebrados bentónicos en la Cuenca del Jequetepeque (Cajamarca, Perú)

    OpenAIRE

    Flores Rojas, Diana; Huamantinco Araujo, Ana

    2017-01-01

    La cuenca de Jequetepeque está amenazada por la contaminación minera y ésta es una de las principales causas de los conflictos socioambientales. La vigilancia ciudadana de sus cuerpos de agua, con macroinvertebrados bentónicos, puede generar alertas tempranas de contaminación y acciones pertinentes de conservación. Atendiendo a esta importancia, el presente estudio tuvo como objetivo desarrollar y evaluar la efectividad de una herramienta de vigilancia ambiental ciudadana para zonas con riesg...

  8. Dependence of critical current on sample length analyzed by the variation of local critical current bent of BSCCO superconducting composite tape

    International Nuclear Information System (INIS)

    Matsubayashi, H.; Mukai, Y.; Shin, J.K.; Ochiai, S.; Okuda, H.; Osamura, K.; Otto, A.; Malozemoff, A.

    2008-01-01

    Using the high critical current type BSCCO composite tape fabricated at American Superconductor Corporation, the relation of overall critical current to the distribution of local critical current and the dependence of overall critical current on sample length of the bent samples were studied experimentally and analytically. The measured overall critical current was described well from the distribution of local critical current and n-value of the constituting short elements, by regarding the overall sample to be composed of local series circuits and applying the voltage summation model. Also the dependence of overall critical current on sample length could be reproduced in computer satisfactorily by the proposed simulation method

  9. Crutch art painting in the Middle Ages as orthopaedic heritage (part II: the peg leg, the bent-knee peg and the beggar).

    Science.gov (United States)

    Hernigou, Philippe

    2014-07-01

    Little of historical value about crutches can be ascertained before the Middle Ages. In contrast, the Middle Ages offer many examples for the study of crutches. Even if no medical report can be found, the immense patronage of the Church, encouraging artists to portray the saints and their miracles, has left great masterpieces that drew people with crutches. Pictures and the history of medieval conceptions of disability appear to provide an interesting chronicle of surgery of the peg leg and the bent-knee peg among the representations of cripples and beggars.

  10. 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...

  11. [Scoliosis: the bent spine].

    Science.gov (United States)

    Radl, R; Maafe, M; Ziegler, S

    2011-05-01

    Scoliosis, a permanent abnormal curvature of the spine to the side, is divided into four forms: idiopathic (infantile, juvenile and adolescent, accounting for 80% of cases), neurogenic, congenital and adult scoliosis. Most patients with adolescent idiopathic scoliosis initially have mainly cosmetic problems. However, neurogenic, congenital and adult scoliosis can lead to severe clinical symptoms. The leading symptom is back pain caused by secondary changes. In recent years the Lenke classification has been proven to be a reliable tool for disease classification. Non-progressive scoliosis is usually treated conservatively. In the case of Cobb angles of greater than 50°, surgical therapy is recommended in patients presenting before adulthood. Technical improvements in implants and the optimisation of surgical methods have set a trend in the direction of surgical therapy.

  12. 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

  13. 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)%.

  14. 走廊弯腰疏散行为试验研究%Experimental Study on Bent-over Walking Behavior of Occupants in Corridors

    Institute of Scientific and Technical Information of China (English)

    杨立兵; 陈建宏; 周汉陵

    2012-01-01

    Bent-over walking behavior of occupants in corridor is studied experimentally in this paper. 6 runs of experiments, with up to 45 students participating in, were conducted with different initial densities . The fundamental diagram of bent-over walking pedestrian flow at low density was obtained by manually analyzing the video recording. The results were compared with pedestrian flow and crawler flow of others. It shows that the free velocity is 1.4 m/s and 1. 7 m/s for the bent-over walking and walking, respectively, while about 0.73 m/s for crawling. When the density is smaller than 0. 5 1/m2, the velocity for these three types of movement behaviors agrees well. While above 0. 5 1/m , there appear clear differences and it can be said that the bent-over walking behavior may be a good way under smoke or heat situation. The frequency distribution of velocity was also investigated for bent-over walking flow. The mean value of speed is about 1. 02 ± 0. 16 m/s and 1. 09 ± 0. 2 m/s for female and male students in these experiments respectively. At low velocity region, the female students account for a larger proportion, whereas the frequency of male students is larger at high velocity regions.%为研究走廊里人群弯腰疏散行为,组织45名学生进行6组不同初始密度疏散试验,通过录像分析得出不同密度时弯腰疏散基本图,将结果与行走及爬行疏散比较.试验结果表明:弯腰和行走疏散的速度分别是1.4 m/s和1.7 m/s,而爬行疏散速度为0.73 m/s;在密度小于0.5人/m2时,3种疏散方式的流动速度相当;在密度大于0.5人/m2时,3种移动方式速度有明显差异;得出弯腰疏散的速度频率分布图,速度均值为:女生1.02±0.16 m/s,男生1.09±0.2 m/s;在低速度区,女生占很大比重,男生在高速度区的频率较高.

  15. Variación espacio-temporal de Chironomidae (Diptera bentónicos y derivantes en un arroyo serrano en Córdoba, Argentina

    Directory of Open Access Journals (Sweden)

    Juan P. Zanotto-Arpellino

    2015-03-01

    Full Text Available Chironomidae es una de las familias más abundantes y diversas en los ecosistemas de agua dulce, sin embargo su complejidad sistemática ha sido motivo de su escaso desarrollo en muchos estudios limnológicos. El objetivo de este estudio fue analizar los ensambles de Chironomidae bentónicos y derivantes de un arroyo serrano de la región central de Argentina evaluando abundancia, diversidad y composición de especies en diferentes hábitats fluviales y distintas estaciones del año. Se tomaron muestras cuantitativas de bentos y deriva en el arroyo Achiras (Córdoba, Argentina en hábitats de rabión y corredera, y se registraron variables ambientales en las cuatro estaciones del año, entre 2007 y 2008. Se registró un total de 25 taxones pertenecientes a cuatro subfamilias. Los quironómidos bentónicos constituyeron el 19% de la comunidad de macroinvertebrados, mientras que en deriva representaron el 33%. En el bentos dominó Thienemannimyia sp. y en la deriva, Corynoneura sp. De acuerdo con los resultados de ANOVAs de dos vías, los mayores valores de riqueza taxonómica y densidad bentónica se registraron en el periodo de aguas bajas (otoño e invierno y la diversidad de quirónomidos bentónicos fue mayor en rabión. Por el contrario, para el ensamble de derivantes sólo la equitatividad fue diferente entre hábitats y entre estaciones. El análisis TWINSPAN mostró una separación espacio-temporal de las muestras de bentos, mientras que las muestras de deriva se segregaron sólo temporalmente lo que sugiere que el transporte aguas abajo de los invertebrados homogeniza la variación espacial observada en el bentos. La densidad de bentos y deriva varió de manera similar a través de las estaciones del año y el coeficiente de Jaccard presentó un alto índice de similitud entre bentos y deriva (86%. Este trabajo posibilitó conocer la dinámica temporal y espacial de los quironómidos bentónicos y derivantes en un arroyo serrano. La

  16. Replication origins oriGNAI3 and oriB of the mammalian AMPD2 locus nested in a region of straight DNA flanked by intrinsically bent DNA sites.

    Science.gov (United States)

    Balani, Valério Américo; de Lima Neto, Quirino Alves; Takeda, Karen Izumi; Gimenes, Fabrícia; Fiorini, Adriana; Debatisse, Michelle; Fernandez, Maria Aparecida

    2010-11-01

    The aim of this work was to determine whether intrinsically bent DNA sites are present at, or close to, the mammalian replication origins oriGNAI3 and oriB in the Chinese hamster AMPD2 locus. Using an electrophoretic mobility shift assay and in silico analysis, we located four intrinsically bent DNA sites (b1 to b4) in a fragment that contains the oriGNAI3 and one site (b5) proximal to oriB. The helical parameters show that each bent DNA site is curved in a left-handed superhelical writhe. A 2D projection of 3D fragment trajectories revealed that oriGNAI3 is located in a relatively straight segment flanked by bent sites b1 and b2, which map in previously identified Scaffold/Matrix Attachment Region. Sites b3 and b4 are located approximately 2 kb downstream and force the fragment into a strong closed loop structure. The b5 site is also located in an S/MAR that is found just downstream of oriB.

  17. 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.

  18. Análisis de la biodiversidad de macroinvertebrados bentónicos del Río Cunas mediante indicadores ambientales, Junín - Perú

    OpenAIRE

    Custodio Villanueva, María

    2013-01-01

    El objetivo de la investigación fue analizar el estado de la biodiversidad de macroinvertebrados bentónicos del río Cunas mediante indicadores ambientales. Se utilizaron los métodos de observación, descripción y explicación; el tipo de investigación es básica y el diseño no experimental, de tipo longitudinal. Se definieron tres sectores de muestreo, San Blas, Huarisca y La Perla. La valoración de las presiones antrópicas se realizó mediante la determinación de DBO5 aportada por aguas residual...

  19. Modeling the Deflection of Polarized Electrons with Energies in the Range 3.35-14 GeV in a Bent Silicon Crystal

    Science.gov (United States)

    Koshcheev, V. P.; Shtanov, Yu. N.; Morgun, D. A.; Panina, T. A.

    2018-04-01

    The evolution of the magnetic moment of a relativistic particle is described with the help of the Bargmann-Michel-Telegdi equation in the planar channels of a bent silicon crystal with allowance for multiple scatteringboth along and transverse to the (111) atomic plane, which consists of chains. Results of numerical simulations demonstrate a strong dependence of the degree of depolarization of the electron beam on the energy since at the energies 3.35 and 4.2 GeV the maximum in the distribution over rotation angles of the electron spin is absent, and at energies from 6.3 to 14 GeV the position of the maximum is in line with the theoretical estimate obtained using the formula of V. L. Lyuboshits.

  20. 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.

  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. 1- to 10-keV x-ray backlighting of annular wire arrays on the Sandia Z-machine using bent-crystal imaging techniques

    International Nuclear Information System (INIS)

    Rambo, Patrick K.; Wenger, David Franklin; Bennett, Guy R.; Sinars, Daniel Brian; Smith, Ian Craig; Porter, John Larry Jr.; Cuneo, Michael Edward; Rovang, Dean Curtis; Anderson, Jessica E.

    2003-01-01

    Annular wire array implosions on the Sandia Z-machine can produce >200 TW and 1-2 MJ of soft x rays in the 0.1-10 keV range. The x-ray flux and debris in this environment present significant challenges for radiographic diagnostics. X-ray backlighting diagnostics at 1865 and 6181 eV using spherically-bent crystals have been fielded on the Z-machine, each with a ∼0.6 eVspectral bandpass, 10 (micro)m spatial resolution, and a 4 mm by 20mm field of view. The Z-Beamlet laser, a 2-TW, 2-kJ Nd:glass laser(λ = 527 nm), is used to produce 0.1-1 J x-ray sources for radiography. The design, calibration, and performance of these diagnostics is presented.

  3. Segmental Mirroring: Does It Eliminate the Need for Intraoperative Readjustment of the Virtually Pre-Bent Reconstruction Plates and Is It Economically Valuable?

    Science.gov (United States)

    Khalifa, Ghada Amin; Abd El Moniem, Nahed Adly; Elsayed, Shadia Abd-ElHameed; Qadry, Yara

    2016-03-01

    The aim of this study was to compare segmental mirroring with mirroring of the entire unaffected side to determine which method obviates intraoperative readjustment of virtually planned pre-bent plates and to evaluate the effect on costs. Patients eligible for inclusion in this prospective study had unilateral mandibular discontinuity defects. Patients were randomly divided into 2 groups. In group I, models were constructed by mirroring the entire unaffected side of the mandible at the midsagittal plane. In group II, only the resected segments were cut and replaced by the corresponding mirrored healthy segments. The lesions were resected, and their sites were reconstructed using pre-bent reconstruction plates. The need for intraoperative plate readjustment, plate placement time, operation time, and operation costs were reviewed. Fifty patients were enrolled in this study. All but 5 plates in group I required readjustment. In group II, plates were placed without intraoperative handling. Average operating times were 4.20 ± 0.56 hours in group I and 3.186 ± 0.28 hours in group II (P = .00002). Mean times for plate placement were 33.36 ± 8.20 and 21.88 ± 5.73 minutes in groups I and II, respectively. The difference resulted in an average time gain of 11.48 minutes. Average personal costs per minute were US$740.77 for group I and US$560.87 for group II. The difference resulted in an average saving of approximately US$179.90. Segmental mirroring is superior in reflecting the bone anatomy in 3-dimensional models, thus eliminating intraoperative plate readjustment and providing better plate adaptation with better contour. It decreases operating time and costs and thus can be recommended for lesions that do not cross the midline. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  4. Ligand field effects in the nuclear magnetic shielding of nitrogen-15 and cobalt-59 in bent nitrosyl complexes of cobalt(III)

    International Nuclear Information System (INIS)

    Duffin, P.A.; Larkworthy, L.F.; Mason, J.; Stephens, A.N.; Thompson, R.M.

    1987-01-01

    A range of square-pyramidal complexes of cobalt(III) with a bent apical nitrosyl ligand has been prepared and examined by 15 N and 59 Co NMR spectroscopy, in a study of nephelauxetic and spectrochemical effects at the metal and nitrogen nuclei in the bent Co-NO chromophore. The basal ligands in this comparison include dithiocarbamate, quadridentate Schiff base or porphine, and bis-chelating diamine or oximate, so as to give S 4 , S 2 N 2 , N 4 , OONN, or ONON coordination in the plane and a range of substituents in the chelate and phenylene rings. The shielding of both cobalt and nitrogen tends to decrease with decrease in the M(d) → π*(NO) back-bonding, as indicated by the MN and NO bond distances, the MNO angle and the NO stretching frequency. The shieldings decrease from sulfur to nitrogen to oxygen coligators and also with electron withdrawal by ring substituents (and vice versa), i.e. with decrease in the ligand field splitting and in the nephelauxetism of the coligands. These parallelisms of the cobalt and nitrogen shielding accord with the orbital theory that was developed to explain the bending of the MNO ligand and influences of the metal and coligands. Significant interdependence of spectrochemical and nephelauxetic effects at cobalt and nitrogen arises from the degree of overlap and similarity in energies of the frontier orbitals for the paramagnetic circulation at nitrogen [n(N) → π* (NO)] and at cobalt (d-d). 43 references, 5 figures, 2 tables

  5. 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.

  6. 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

    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...

  7. 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

  8. Invertebrados bentônicos: relação entre estrutura da fauna e características do mesohabitat

    Directory of Open Access Journals (Sweden)

    Virginia Sanches Uieda

    2016-06-01

    Full Text Available Em ecossistemas lóticos é comum a formação de diferentes mesohabitats intercalados ao longo do rio, como poções, corredeiras e rápidos, frequentemente acompanhados de alterações na estrutura da fauna bentônica associada. No trabalho analisamos a fauna de invertebrados bentônicos em rápidos e corredeiras de um trecho de serra do Rio Capivara (Bacia do Médio Rio Tietê. A análise das características ambientais e a coleta da fauna foram realizadas em três corredeiras e três rápidos, em um mês da estação chuvosa (cinco réplicas de cada. Os mesohabitats se diferenciaram quanto ao maior porcentual de blocos nos rápidos e maiores valores de profundidade, correnteza e porcentual de matacões nas corredeiras. Do total de 57 Unidades Taxonômicas Operacionais (UTO's amostradas, 75% foram comuns aos dois mesohabitats (Similaridade de Morisita = 0,86. Quando analisado o porcentual de abundância, a similaridade espacial se manteve e dois grupos se sobressaíram em abundância: Hexapoda (>80%, sendo a maioria Ephemeroptera, Diptera e Trichoptera e Annelida (10%. As análises exploratórias (cluster e NMDS também apontaram para uma elevada similaridade espacial, porém os resultados da Análise de Similaridade (ANOSIM indicaram uma diferença significativa entre os mesohabitats (p<0,1%, seja analisando o total de UTO's ou retirando as UTO's raras. Cinco grupos tiveram uma maior contribuição para a média de dissimilaridade entre os mesohabitats: Simulium e Baetodes mais abundantes nas corredeiras, Traveryphes, Hagenulopsis e Macrelmis nos rápidos. Assim, os resultados da ANOSIM salientaram a importância do refinamento na identificação para a interpretação mais precisa acerca da relação entre a fauna e a estrutura do habitat.

  9. 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 1977-03-04 to 1977-03-27 (NODC Accession 7700351)

    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...

  10. 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

  11. 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.

  12. A novel U-bent plastic optical fibre local surface plasmon resonance sensor based on a graphene and silver nanoparticle hybrid structure

    International Nuclear Information System (INIS)

    Jiang, Shouzhen; Li, Zhe; Zhang, Chao; Gao, Saisai; Li, Zhen; Li, Chonghui; Yang, Cheng; Liu, Mei; Qiu, Hengwei; Liu, Yanjun

    2017-01-01

    In this work, we have presented a novel local surface plasmon resonance (LSPR) sensor based on the U-bent plastic optical fibre (U-POF). Firstly, a layer of discontinuous silver (Ag) thin film was deposited on the U-POF and then the Ag film was covered by a layer of cladding synthesized by polyvinyl alcohol (PVA), graphene and silver nanoparticles forming the PVA/G/AgNPs@Ag film. The normalized transmittance spectrum of the LSPR sensor have been collected in a range of the refractive index (RI) from 1.330 to 1.3657 in ethanol solution, and 700.3 nm/RIU sensitivity of the developed LSPR sensor has been demonstrated. By experiments, we demonstrated that the graphene could improve the sensitivity of the LSPR sensor and delay the oxidation process of the AgNPs effectively to keep the stability of the LSPR sensor. The LSPR sensor also exhibited good sensitivity and linearity in the detection of glucose solutions. This work shows that the developed LSPR sensor may have promising applications in biosensing. (paper)

  13. Spatiotemporal character of the Bobylev-Pikin flexoelectric instability in a twisted nematic bent-core liquid crystal exposed to very low frequency fields.

    Science.gov (United States)

    Krishnamurthy, K S

    2014-05-01

    The Bobylev-Pikin striped-pattern state induced by a homogeneous electric field is a volume flexoelectric instability, originating in the midregion of a planarly aligned nematic liquid crystal layer. We find that the instability acquires a spatiotemporal character upon excitation by a low frequency (0.5 Hz) square wave field. This is demonstrated using a bent-core liquid crystal, initially in the 90°-twisted planar configuration. The flexoelectric modulation appears close to the cathode at each polarity reversal and, at low voltage amplitudes, decays completely as the field becomes steady. Correspondingly, at successive polarity changes, the stripe direction switches between the alignment directions at the two substrates. For large voltages, the stripes formed nearly along the alignment direction at the cathode gradually reorient toward the midplane director. These observations are generally attributed to inhomogeneous and time-dependent field conditions that come to exist after each polarity reversal. Polarity dependence of the instability is attributed to the formation of intrinsic double layers that bring about an asymmetry in surface fields. Momentary field elevation near the cathode following a voltage sign reversal and concomitant gradient flexoelectric polarization are considered the key factors in accounting for the surfacelike modulation observed at low voltages.

  14. Statistical analysis of the distribution of critical current and the correlation of n value to the critical current of bent Bi2223 composite tape

    International Nuclear Information System (INIS)

    Ochiai, S; Matsubayashi, H; Okuda, H; Osamura, K; Otto, A; Malozemoff, A

    2009-01-01

    Distributions of local and overall critical currents and correlation of n value to the critical current of bent Bi2223 composite tape were studied from the statistical viewpoint. The data of the local and overall transport critical currents and n values of the Bi2223 composite tape specimens were collected experimentally for a wide range of bending strain (0-1.1%) by using the specimens, designed so as to characterize the local and overall critical currents and n values. The measured local and overall critical currents were analyzed with various types of Weibull distribution function. Which of the Weibull distribution functions is suitable for the description of the distribution of local and overall critical currents at each bending strain, and also how much the Weibull parameter values characterizing the distribution vary with bending strain, were revealed. Then we attempted to reproduce the overall critical current distribution and correlation of the overall n value to the overall critical current from the distribution of local critical currents and the correlation of the local n value to the local critical current by a Monte Carlo simulation. The measured average values of critical current and n value at each bending strain and the correlation of n value to critical current were reproduced well by the present simulation, while the distribution of critical current values was reproduced fairly well but not fully. The reason for this is discussed.

  15. Norman M. Dott, master of hypothalamic craniopharyngioma surgery: the decisive mentoring of Harvey Cushing and Percival Bailey at Peter Bent Brigham Hospital.

    Science.gov (United States)

    Prieto, Ruth; Pascual, José M

    2017-10-01

    Norman McOmish Dott (1897-1973) developed surgical neurology in Edinburgh, Scotland, and was a scholar of worldwide renown. One of Dott's most notable contributions to neurosurgery was his understanding of hypothalamic physiology, mostly acquired through the comprehensive study of patients with lesions involving this region of the diencephalon, particularly craniopharyngiomas (CPs). Recognition of symptoms caused by hypothalamic disturbances allowed him to predict the accurate anatomical relationships between CPs and the hypothalamus, despite the rudimentary radiological methods available during the 1930s. His sophisticated knowledge permitted Dott to perform radical removals of CPs originating within the third ventricle floor with acceptable success. Between 1934 and 1937, he operated on 4 CP cases originating in the hypothalamus, achieving a satisfactory postoperative outcome in 3 of the 4 patients. Aware of the strong attachment of hypothalamic CPs to the infundibulo-tuberal area, Dott used a double transbasal and transventricular approach to these lesions, a strategy providing an optimal view and control of the tumor boundaries. The decisive mentorship of several legendary figures of physiology and neurosurgery greatly influenced Dott's surgical evolution. The experimental pituitary gland work he performed with Sir Edward Sharpey-Schäfer at the beginning of his career stirred Dott's curiosity about the issue of hypothalamus-pituitary relationships. As a result, he decided to move to Peter Bent Brigham Hospital (Boston, Massachusetts) in 1923, to train in neurosurgery and neuropathology under the guidance of the leaders in these fields, Harvey Williams Cushing (1869-1939) and Percival Sylvester Bailey (1892-1973). They inspired the young Dott and shared with him their clinical and pathological expertise, in addition to their surgical strategies for best approaching and removing these challenging tumors. In time, Dott would come to surpass his mentors. This

  16. 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.

  17. Estudio del valor indicador de las comunidades de algas bentónicas: una propuesta de evaluación y aplicación en el río Magdalena, Ciudad de México

    OpenAIRE

    Carmona Jiménez, Javier; Ramírez Rodríguez, Rocío; Bojorge-García, Miriam Guadalupe; González Hidalgo, Beatriz; Cantoral-Uriza, Enrique A.

    2016-01-01

    RESUMEN: La aplicación y desarrollo de las leyes ambientales que regulan el manejo de cuencas requiere la identificación de indicadores biológicos, los parámetros y las medidas para establecer su estado ecológico, para lo cual el presente estudio tiene como objetivo caracterizar el valor indicador ecológico de las algas bentónicas en una corriente urbana de la Ciudad de México. Se estudiaron seis sitios del río Magdalena en las estaciones más contrastantes del año: seca cálida, lluviosa y sec...

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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

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    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

  3. Especies de foraminíferos bentónicos indicadoras del estado de óxido-reducción del sedimento superficial en el margen continental central del Perú

    OpenAIRE

    Cardich Salazar, Jorge Aquiles

    2012-01-01

    La comunidad de foraminíferos bentónicos fue estudiada en dos transectas batimétricas frente a Callao (12° S) y Pisco (14° S) entre 2009 y 2011, con el objetivo de determinar especies indicadoras de microhábitats geoquímicos en un gradiente de condiciones de óxido-reducción en el sedimento. Se analizó la variación espacio-temporal y el microhábitat vertical de las especies y su relación con los factores ambientales: oxígeno de fondo (OD), sulfuro de hidrógeno en agua intersticial (H2S), fitop...

  4. 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

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    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.

  5. 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.

  6. 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

  7. 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

  8. 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

  9. 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.

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

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    Iris Gabrielly Arruda dos Santos

    2015-03-01

    Full Text Available 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, 90 e 120 dias. Dois tratamentos foram utilizados: colonização e exclusão da macrofauna. O percentual de biomassa remanescente final (%R foi maior para bolsas de colonização do que para as de exclusão, evidenciando a efetiva participação dos macroinvertebrados no processo de decomposição. Os fragmentadores apresentaram menor participação no processo de decomposição foliar de I. ingoides, sendo Tripletides (Trichoptera: Leptoceridae, Polypedillum e Stenochironomus (Diptera, Chironomidae os táxons predominantes na macrofauna. Filtrador foi o grupo trófico funcional predominante (45,6%, seguido por predador (31,2%, coletor (11,8%, raspador (6,7% e fragmentador (4,8%.

  11. Validity and reliability of isometric muscle strength measurements of hip abduction and abduction with external hip rotation in a bent-hip position using a handheld dynamometer with a belt.

    Science.gov (United States)

    Aramaki, Hidefumi; Katoh, Munenori; Hiiragi, Yukinobu; Kawasaki, Tsubasa; Kurihara, Tomohisa; Ohmi, Yorikatsu

    2016-07-01

    [Purpose] This study aimed to investigate the relatedness, reliability, and validity of isometric muscle strength measurements of hip abduction and abduction with an external hip rotation in a bent-hip position using a handheld dynamometer with a belt. [Subjects and Methods] Twenty healthy young adults, with a mean age of 21.5 ± 0.6 years were included. Isometric hip muscle strength in the subjects' right legs was measured under two posture positions using two devices: a handheld dynamometer with a belt and an isokinetic dynamometer. Reliability was evaluated using an intra-class correlation coefficient (ICC); relatedness and validity were evaluated using Pearson's product moment correlation coefficient. Differences in measurements of devices were assessed by two-way ANOVA. [Results] ICC (1, 1) was ≥0.9; significant positive correlations in measurements were found between the two devices under both conditions. No main effect was found between the measurement values. [Conclusion] Our findings revealed that there was relatedness, reliability, and validity of this method for isometric muscle strength measurements using a handheld dynamometer with a belt.

  12. A new species of karst forest Bent-toed Gecko (genus Cyrtodactylus Gray) not yet threatened by foreign cement companies and a summary of Peninsular Malaysia's endemic karst forest herpetofauna and the need for its conservation.

    Science.gov (United States)

    Grismer, L Lee; Wood, P L Jr; Anuar, Shahrul; Davis, H R; Cobos, A J; Murdoch, M L

    2016-01-04

    A new species of Bent-toed Gecko, Cyrtodactylus gunungsenyumensis sp. nov. of the sworderi complex, is described from Hutan Lipur Gunung Senyum, Pahang, Peninsular Malaysia and is differentiated from all other species in the sworderi complex by having a unique combination of characters including a maximum SVL of 74.7 mm; low, rounded, weakly keeled, body tubercles; 34-40 paravertebral tubercles; weak ventrolateral body fold lacking tubercles; 38-41 ventral scales; an abrupt transition between the posterior and ventral femoral scales; 20-23 subdigital lamellae on the fourth toe; enlarged femoral scales; no femoral or precloacal pores; no precloacal groove; wide caudal bands; and an evenly banded dorsal pattern. Cyrtodactylus gunungsenyumensis sp. nov. is a scansorial, karst forest-adapted specialist endemic to the karst ecosystem surrounding Gunung Senyum and occurs on the vertical walls of the limestone towers as well as the branches, trunks, and leaves of the vegetation in the associated karst forest. Cyrtodactylus gunungsenyumensis sp. nov. is the seventh species of karst forest-adapted Cyrtodactylus and the sixteenth endemic species of karst ecosystem reptile discovered in Peninsular Malaysia in the last seven years from only 12 different karst forests. This is a clear indication that many species remain to be discovered in the approximately 558 isolated karst ecosystems in Peninsular Malaysia not yet surveyed. These data continue to underscore the importance of karst ecosystems as reservoirs of biodiversity and microendemism and that they constitute an important component of Peninsular Malaysia's natural heritage and should be protected from the quarrying interests of foreign industrial companies.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. Bent approximations to synchrotron radiation optics

    International Nuclear Information System (INIS)

    Heald, S.

    1981-01-01

    Ideal optical elements can be approximated by bending flats or cylinders. This paper considers the applications of these approximate optics to synchrotron radiation. Analytic and raytracing studies are used to compare their optical performance with the corresponding ideal elements. It is found that for many applications the performance is adequate, with the additional advantages of lower cost and greater flexibility. Particular emphasis is placed on obtaining the practical limitations on the use of the approximate elements in typical beamline configurations. Also considered are the possibilities for approximating very long length mirrors using segmented mirrors

  20. 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

  1. 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

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    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

  2. 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

  3. A biodiversidade bentônica em lagoa marginal ao rio Paranapanema na zona de sua desembocadura, na represa de Jurumirim = The benthic biodiversity in a lake marginal to the Paranapanema river in its mouth zone into Jurumirim reservoir

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    Rosemary Cristina Souza Davanso

    2006-10-01

    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 emintervalos 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 análiserevelou 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 etemperatura 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 analyzed

  4. Discusión sobre el número de unidades muestrales y tamaño de unidad muestral para la estimación de valores de densidad de macroinvertebrados bentónicos en ambientes lóticos

    OpenAIRE

    Oyague-Passuni, Eduardo

    2009-01-01

    En este documento se discute sobre el número apropiado de Unidades Muestrales y el Tamaño Mínimo de Unidad Muestral (TUM) recomendable, para la estimación más precisa posible de un valor referencial de la densidad de macroinvertebrados bentónicos. El enfoque del análisis está referido a secciones con parámetros homogéneos en cuanto a fisiografía y características generales de hábitat, en ambientes lóticos en selva de montaña. Se analizaron datos provenientes de un muestreo intensivo mediante ...

  5. 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

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    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

  6. Macroinvertebrados bentônicos como indicadores do impacto ambiental promovido pelos efluentes de áreas orizícolas e pelos de origem urbana/industrial Benthic macroinvertebrates as indicators of environmental impact promoted by rice crop flood and by urban/industrial effluents

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    Karine Delevati Colpo

    2009-10-01

    Full Text Available Os macroinvertebrados bentônicos têm sido amplamente utilizados como bioindicadores de qualidade ambiental. O objetivo deste estudo foi comparar a qualidade da água que sai de uma área com cultivo de arroz irrigado (água de drenagem com a água de irrigação, oriunda do Rio Gravataí, em um ponto na grande Porto Alegre. Este estudo de monitoramento foi conduzido na Estação Experimental do Arroz, pertencente ao Instituto Rio Grandense do Arroz (IRGA, em Cachoeirinha, Rio Grande do Sul (RS, ao longo da safra de 2006/2007. Uma camada de 5cm de solo contendo macroinvertebrados bentônicos foi amostrada, utilizando um Corer (78,54cm², na fonte de irrigação da lavoura (Rio Gravataí e Canal de Irrigação e no receptor de seus efluentes (Canal de Drenagem. Além disso, o oxigênio dissolvido (O2 na água foi registrado em cada ponto. O material foi filtrado em uma peneira com malha de 0,5mm, fixado, triado e identificado. A abundância, riqueza, biodiversidade e equitabilidade foram avaliadas e comparadas entre os pontos amostrados. Tais parâmetros ecológicos demonstraram uma comunidade mais estruturada e complexa no canal de drenagem que no canal de irrigação e no Rio Gravataí, indicando que a qualidade ambiental é melhor no ponto que recebe a água que passa pela lavoura que nos pontos de entrada da água. Portanto, a comunidade de macroinvertebrados bentônicos neste estudo sugere que os efluentes produzidos pelas cidades e indústrias, como os presentes na bacia hidrográfica do Rio Gravataí, em especial da Grande Porto Alegre, são mais agressivos aos ambientes aquáticos que os efluentes drenados de uma lavoura manejada de acordo com as recomendações técnicas para a cultura.The macroinvertebrates have been used as indicators of environmental quality. The objective of this study was to compare the quality of water which drains from the rice flooded crop (drainage water with the irrigation water, sourced from Gravataí River

  7. 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

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    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

  8. 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

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    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.

  9. 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.

  10. The Patagonian scallop fishing grounds in shelf break frontal areas: the non assessed benthic fraction Bancos de pesca de vieira patagónica en áreas del frente de talud: fracción bentónica no evaluada

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    María de los Ángeles Sánchez

    2011-01-01

    Full Text Available In this study, a Picard dredge was used to sample the benthic community in shelf break frontal areas off Argentina in order to detect species that could be sensitive to fishing activities but are not usually caught during the annual monitoring of Patagonian scallop and associated fauna. The present results show at least 62 taxa not reported previously as components of the benthos in the scallop grounds that are potentially subjected to trawling disturbance.En este trabajo se utilizó una rastra Picard para muestrear la comunidad bentónica en áreas del frente de talud, Argentina, para detectar especies que serían sensibles a la actividad pesquera pero no son capturadas usualmente durante los monitoreos anuales de vieira patagónica y fauna asociada. Los resultados muestran que al menos 62 taxa, no reportados previamente como componentes del bentos en los bancos de vieira, están potencialmente sujetos a perturbaciones por el arrastre.

  11. 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

  12. Living (stained calcareous benthic foraminifera from recent sediments off Concepción, central-southern Chile (~36° S Foraminíferos bentónicos calcáreos vivos (teñidos en sedimentos recientes de Concepción, Chile centro-sur (~36° S

    Directory of Open Access Journals (Sweden)

    RAÚL TAPIA

    2008-09-01

    Full Text Available This study examines onshore-offshore and vertical distribution of living (Rose Bengal stained benthic foraminifera (> 180 μm fraction from three sediment stations along a bathymetric transect off Concepción, Chile (station 18 = 88 m water depth, station 26 = 120 m, station 40 = 1,030 m, within and below the oxygen minimum zone. All cores were collected in austral winter. Calcareous foraminifera dominated the three stations. The species composition, living foraminifera density, and vertical distribution patterns within the sediment changed in accordance with bottom water dissolved oxygen concentration and food availability. Onshore-offshore pattern revealed overall highest living foraminiferal densities at shelf stations 18 and 26 where bottom water dissolved oxygen was lowest (~ 0.2 mL-1 and content in labile organic matter highest. Within the sediment, maximum relative abundances (50-60 % of living organisms were found in the 0-1 cm interval at the organic-rich and oxygen-poor shelf stations 18 and 26. In the well-oxygenated (2.7 mL-1 slope station 40, 70 % of living foraminifera were observed deeper than the first centimeter. The number of species and the contribution of the > 250 μm fraction to the total fauna larger than 180 μm increased offshore. Nonionella auris (d'Orbigny dominated at stations 18 and 26 while a more diverse foraminifera fauna was found at station 40. This study provides the first quantitative data on living benthic foraminifera in the area; seasonal and interannual changes are not addressed.Este estudio examina la distribución costa-océano y vertical de los foraminíferos bentónicos calcáreos (fracción > 180 im vivos (teñidos en tres estaciones a lo largo de un transecto batimétrico frente al área de Concepción, Chile (estación 18 = 88 m, estación 26 = 120 m, estación 40 = 1.030 m de profundidad, dentro y bajo la zona mínima de oxígeno. Todos los testigos de sedimento fueron recolectados durante el per

  13. 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

  14. FERMILAB: Tevatron upgrade; Magnetic precession in bent crystals

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1993-01-15

    The Fermilab accelerator complex is in the middle of a major upgrade to increase the luminosity beyond the original design goal. During Phase I of this upgrade, there have been major modifications to the Tevatron. These modifications were commissioned at the start of the latest collider run and include the installation of electrostatic separators to separate the orbits of the stored beams and new low beta insertions to squeeze the colliding proton and antiproton beams at both experiment interaction regions. These modifications have already enabled the Tevatron to achieve a record peak luminosity of 6.93 x 10{sup 30} per sq cm per s and a record weekly integrated luminosity of 10{sup 60} inverse nanobarns. The peak goal for the present run of 5.0 x 10{sup 30} has already been exceeded.

  15. 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

  16. 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....

  17. 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

  18. Proposed residual stress model for roller bent wide flange sections

    NARCIS (Netherlands)

    Spoorenberg, R.C.; Snijder, H.H.; Hoenderkamp, J.C.D.

    2011-01-01

    The manufacturing process of structural wide flange steel sections introduces residual stresses in the material. These stresses due to hot-rolling or welding influence the inelastic buckling response of structural steel members and need to be taken into account in the design. Based on experimental

  19. Imaging voids beneath bridge bent using electrical resistivity tomography.

    Science.gov (United States)

    2014-02-01

    Five electrical resistivity tomography (ERT) profiles and borehole control were acquired beneath two bridges on the bank of the : Gasconade River in order to determine extension of the underground water-filled openings in rock encountered during a dr...

  20. FERMILAB: Tevatron upgrade; Magnetic precession in bent crystals

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    The Fermilab accelerator complex is in the middle of a major upgrade to increase the luminosity beyond the original design goal. During Phase I of this upgrade, there have been major modifications to the Tevatron. These modifications were commissioned at the start of the latest collider run and include the installation of electrostatic separators to separate the orbits of the stored beams and new low beta insertions to squeeze the colliding proton and antiproton beams at both experiment interaction regions. These modifications have already enabled the Tevatron to achieve a record peak luminosity of 6.93 x 10 30 per sq cm per s and a record weekly integrated luminosity of 10 60 inverse nanobarns. The peak goal for the present run of 5.0 x 10 30 has already been exceeded

  1. 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...

  2. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Bagli, E.; Bandiera, L.; Bellucci, V.; Camattari, R.; Germogli, G.; Guidi, V.; Mazzolari, A. [Univ. di Ferrara, Dipartimento di Fisica, Ferrara (Italy); INFN, Sezione di Ferrara (Italy); Berra, A.; Lietti, D.; Prest, M. [Univ. dell' Insubria, Como (Italy); INFN Sezione di Milano Bicocca, Milan (Italy); De Salvador, D. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Univ. di Padova, Dipartimento di Fisica, Padua (Italy); Lanzoni, L. [San Marino Univ. (San Marino). Dept. of Engineering; Tikhomirov, V.V. [Belarusian State University, Research Institute for Nuclear Problems, Minsk (Belarus); Vallazza, E. [INFN, Sezione di Trieste (Italy)

    2014-10-15

    The usage of a crystalline undulator (CU) has been identified as a promising solution for generating powerful and monochromatic γ-rays. A CU was fabricated at Sensors and Semiconductors Lab (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. (orig.)

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

    International Nuclear Information System (INIS)

    Syphers, Michael; Michelotti, Leo

    2000-01-01

    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

  5. Estimates of dispersive effects in a bent NLC main linac

    OpenAIRE

    Syphers, M.; Michelotti, L.

    2000-01-01

    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 an equipotential. We 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...

  6. 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

  7. 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

  8. Ecological attributes of the benthic community and indices of water quality in urban, rural and preserved environments Atributos ecológicos da comunidade bentônica e índices de qualidade da água de ambientes urbanos, rurais e preservados

    Directory of Open Access Journals (Sweden)

    Claudia Eiko Yoshida

    2012-09-01

    as alterações da paisagem dos riachos e de seu entorno com as mudanças na estrutura da comunidade de macroinvertebrados desses ambientes; OBJETIVOS: O presente estudo teve como objetivos correlacionar as mudanças da paisagem com os atributos ecológicos da comunidade e índices de qualidade da água e, recomendar valores de condição referencial de integridade de riachos para a região de Jundiaí/SP; MÉTODOS: Foram amostradas a fauna bentônica de três riachos urbanos, três rurais e três preservados, com amostrador do tipo Surber, em julho de 2010. As características da paisagem foram avaliadas por meio da Diversidade de Habitat (DH; a comunidade, analisada quanto a S, N, J', H' e curvas de rarefação S e de dominância K e; a qualidade da água aferida pelos índices ICB Rio, BMWP-CETEC, ASPT e SOMI; RESULTADOS: A estrutura e a composição das comunidades variaram em função dos riachos e refletiram-se nos valores dos índices biológicos e de qualidade ambiental. As melhores condições foram encontradas nos riachos preservados, as intermediárias, nos riachos rurais e, as piores, nos urbanos. As significativas correlações (r > 0.73 e P < 0.05 entre o índice de diversidade de habitat (DH e os atributos ecológicos e de qualidade da água dos riachos de Jundiaí, demonstraram que DH pode ser um bom preditor das características ambientais avaliadas e como tal, recomenda-se como valores de condição de referencia de riachos: DH ≥ 80; H' ≥ 2,3 e J ≥ 0.8 (família como nível taxonômico e; qualidade de água boa (ICB Rio, BMWP-CETEC e BI, de levemente poluída a limpa (ASPT e regular (SOMI.

  9. Ecological attributes of the benthic community and indices of water quality in urban, rural and preserved environments Atributos ecológicos da comunidade bentônica e índices de qualidade da água de ambientes urbanos, rurais e preservados

    Directory of Open Access Journals (Sweden)

    Claudia Eiko Yoshida

    2012-01-01

    as alterações da paisagem dos riachos e de seu entorno com as mudanças na estrutura da comunidade de macroinvertebrados desses ambientes; OBJETIVOS: O presente estudo teve como objetivos correlacionar as mudanças da paisagem com os atributos ecológicos da comunidade e índices de qualidade da água e, recomendar valores de condição referencial de integridade de riachos para a região de Jundiaí/SP; MÉTODOS: Foram amostradas a fauna bentônica de três riachos urbanos, três rurais e três preservados, com amostrador do tipo Surber, em julho de 2010. As características da paisagem foram avaliadas por meio da Diversidade de Habitat (DH; a comunidade, analisada quanto a S, N, J', H' e curvas de rarefação S e de dominância K e; a qualidade da água aferida pelos índices ICB Rio, BMWP-CETEC, ASPT e SOMI; RESULTADOS: A estrutura e a composição das comunidades variaram em função dos riachos e refletiram-se nos valores dos índices biológicos e de qualidade ambiental. As melhores condições foram encontradas nos riachos preservados, as intermediárias, nos riachos rurais e, as piores, nos urbanos. As significativas correlações (r > 0.73 e P < 0.05 entre o índice de diversidade de habitat (DH e os atributos ecológicos e de qualidade da água dos riachos de Jundiaí, demonstraram que DH pode ser um bom preditor das características ambientais avaliadas e como tal, recomenda-se como valores de condição de referencia de riachos: DH ≥ 80; H' ≥ 2,3 e J ≥ 0.8 (família como nível taxonômico e; qualidade de água boa (ICB Rio, BMWP-CETEC e BI, de levemente poluída a limpa (ASPT e regular (SOMI.

  10. 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.

  11. A technique for measuring the quality of an elliptically bent pentaerythritol [PET(002)] crystal

    Energy Technology Data Exchange (ETDEWEB)

    Haugh, M. J., E-mail: haughmj@nv.doe.gov; Jacoby, K. D. [National Security Technologies, LLC, Livermore, California 94550 (United States); Barrios, M. A.; Thorn, D.; Emig, J. A.; Schneider, M. B. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)

    2016-11-15

    We present a technique for determining the X-ray spectral quality from each region of an elliptically curved PET(002) crystal. The investigative technique utilizes the shape of the crystal rocking curve which changes significantly as the radius of curvature changes. This unique quality information enables the spectroscopist to verify where in the spectral range that the spectrometer performance is satisfactory and where there are regions that would show spectral distortion. A collection of rocking curve measurements for elliptically curved PET(002) has been built up in our X-ray laboratory. The multi-lamellar model from the XOP software has been used as a guide and corrections were applied to the model based upon measurements. But, the measurement of R{sub I} at small radius of curvature shows an anomalous behavior; the multi-lamellar model fails to show this behavior. The effect of this anomalous R{sub I} behavior on an X-ray spectrometer calibration is calculated. It is compared to the multi-lamellar model calculation which is completely inadequate for predicting R{sub I} for this range of curvature and spectral energies.

  12. 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...

  13. "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....

  14. Dynamic stability of a curved pipe bent in the arc of a circle on hinge ...

    Indian Academy of Sciences (India)

    of numerical solution of the dynamic stability of a pipe in its plane are developed. An example of a ... Most scientific researches in the area of vibrations of pipes conveying liquids are concerned with investigation of ..... is good coincidence. 5.

  15. High resolution monochromatic X-ray imaging system based on spherically bent crystals

    International Nuclear Information System (INIS)

    Aglitskiy, Y.; Lehecka, T.; Obenschain, S.; Bodner, S.; Pawley, C.; Gerber, K.; Sethian, J.; Brown, C.M.; Seely, J.; Feldman, U.; Holland, G.

    1997-01-01

    We have developed a new X-ray imaging system based on spherically curved crystals. It is designed and used for diagnostics of targets ablatively accelerated by the Nike KrF laser [1,2]. The imaging system is used for plasma diagnostics of the main target and for characterization of potential backlighters. A spherically curved quartz crystal (2d=6.687 Angstrom, R=200mm) is used to produce monochromatic backlit images with the He-like Si resonance line (1865 eV) as the source of radiation. The spatial resolution of the X-ray optical system is 3 endash 4 μm. Time resolved backlit monochromatic images of CH planar targets driven by the Nike facility have been obtained with 6 endash 7 μm spatial resolution. copyright 1997 American Institute of Physics

  16. High resolution monochromatic X-ray imaging system based on spherically bent crystals

    International Nuclear Information System (INIS)

    Aglitskiy, Y.; Lehecka, T.; Obenschain, S.; Bodner, S.; Pawley, C.; Gerber, K.; Sethian, J.; Brown, C. M.; Seely, J.; Feldman, U.; Holland, G.

    1997-01-01

    We have developed a new X-ray imaging system based on spherically curved crystals. It is designed and used for diagnostics of targets ablatively accelerated by the Nike KrF laser. The imaging system is used for plasma diagnostics of the main target and for characterization of potential backlighters. A spherically curved quartz crystal (2d=6.687 A, R=200 mm) is used to produce monochromatic backlit images with the He-like Si resonance line (1865 eV) as the source of radiation. The spatial resolution of the X-ray optical system is 3-4 μm. Time resolved backlit monochromatic images of CH planar targets driven by the Nike facility have been obtained with 6-7 μm spatial resolution

  17. High-resolution monochromatic x-ray imaging system based on spherically bent crystals

    International Nuclear Information System (INIS)

    Aglitskiy, Y.; Lehecka, T.; Obenschain, S.; Bodner, S.; Pawley, C.; Gerber, K.; Sethian, J.; Brown, C.M.; Seely, J.; Feldman, U.; Holland, G.

    1998-01-01

    We have developed an improved x-ray imaging system based on spherically curve crystals. It is designed and used for diagnostics of targets ablatively accelerated by the Nike KrF laser. A spherically curved quartz crystal (2d=6.687 Angstrom, R=200 mm) has been used to produce monochromatic backlit images with the He-like Si resonance line (1865 eV) as the source of radiation. The spatial resolution of the x-ray optical system is 1.7 μm in selected places and 2 - 3 μm over a larger area. Time-resolved backlit monochromatic images of polystyrene planar targets driven by the Nike facility have been obtained with a spatial resolution of 2.5 μm in selected places and 5 μm over the focal spot of the Nike laser. copyright 1998 Optical Society of America

  18. A technique for measuring the quality of an elliptically bent pentaerythritol [PET(002)] crystal

    International Nuclear Information System (INIS)

    Haugh, M. J.; Jacoby, K. D.; Barrios, M. A.; Thorn, D.; Emig, J. A.; Schneider, M. B.

    2016-01-01

    We present a technique for determining the X-ray spectral quality from each region of an elliptically curved PET(002) crystal. The investigative technique utilizes the shape of the crystal rocking curve which changes significantly as the radius of curvature changes. This unique quality information enables the spectroscopist to verify where in the spectral range that the spectrometer performance is satisfactory and where there are regions that would show spectral distortion. A collection of rocking curve measurements for elliptically curved PET(002) has been built up in our X-ray laboratory. The multi-lamellar model from the XOP software has been used as a guide and corrections were applied to the model based upon measurements. But, the measurement of R I at small radius of curvature shows an anomalous behavior; the multi-lamellar model fails to show this behavior. The effect of this anomalous R I behavior on an X-ray spectrometer calibration is calculated. It is compared to the multi-lamellar model calculation which is completely inadequate for predicting R I for this range of curvature and spectral energies.

  19. 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

  20. 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...

  1. 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.

  2. 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.

  3. Hoe goed bent u 'in control' over de robuustheid van uw ICT-keten?

    NARCIS (Netherlands)

    Bastiaansen, H.J.M.; Joosten, H.J.M.; Meeuwissen, H.B.; Roijers, F.

    2011-01-01

    ICT-ketens worden enerzijds steeds complexer en anderzijds van steed vitaler belang voor de maatschappij en voor organisaties. Daarbij neemt ook het belang van robuustheid van ICT-ketens en de beheersing daarvan toe. De auteurs beschrijven een nieuwe methodiek waarmee de mate van beheersing van de

  4. Gauche effect in 1,2-difluoroethane. Hyperconjugation, bent bonds, steric repulsion.

    Science.gov (United States)

    Goodman, Lionel; Gu, Hongbing; Pophristic, Vojislava

    2005-02-17

    Natural bond orbital deletion calculations show that whereas the gauche preference arises from vicinal hyperconjugative interaction between anti C-H bonds and C-F* antibonds, the cis C-H/C-F* interactions are substantial (approximately 25% of the anti interaction). The established significantly >60 degrees FCCF dihedral angle for the equilibrium conformer can then be rationalized in terms of the hyperconjugation model alone by taking into account both anti interactions that maximize near 60 degrees and the smaller cis interactions that maximize at a much larger dihedral angle. This explanation does not invoke repulsive forces to rationalize the 72 degrees equilibrium conformer angle. The relative minimum energy for the trans conformer is the consequence of a balance between decreasing hyperconjugative stabilization and decreasing steric destabilization as the FCCF torsional angle approaches 180 degrees . The torsional coordinate is predicted to be strongly contaminated by CCF bending, with the result that approximately half of the trans --> gauche stabilization energy stems from mode coupling.

  5. 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

  6. 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

  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. 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

  9. 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.

  10. 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...

  11. 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

  12. A fitting program for potential energy surfaces of bent triatomic molecules

    International Nuclear Information System (INIS)

    Searles, D.J.; Nagy-Felsobuki, E.I. von

    1992-01-01

    A program has been developed in order to fit analytical power series expansions (Dunham, Simon-Parr-Finlan, Ogilvie and their exponential variants) and Pade approximants to discrete ab initio potential energy surfaces of non-linear triatomic molecules. The program employs standard least-squares fitting techniques using the singular decomposition method in order to dampen the higher-order coefficients (if deemed necessary) without significantly degrading the fit. The program makes full use of the symmetry of a triatomic molecule and so addresses the D 3h , C 2v and C S cases. (orig.)

  13. 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.)

  14. 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...

  15. NMR studies of bent DNA using {sup 13}C-enriched samples

    Energy Technology Data Exchange (ETDEWEB)

    Zimmer, D.P.; Crothers, D.M. [Yale Univ., New Haven, CT (United States)

    1994-12-01

    Bending of the DNA double helix can be brought about by introducing runs of adenines (A-tracts) in phase with the helical repeat of the DNA. The requirements for bending of DNA by A-tracts are that the length of the A-tract be greater than 3 base pairs and that the A-tracts must be in phase with the helical repeat (every 10 or 11 bp). Other factors, such as the number of adenines in the run, flanking sequences, and whether the A-tracts are phased with respect to the 5{prime}A or the 3{prime}A, have effects upon the degree of bending as assayed by electrophoretic mobility on native polyacrylamide gels. There are a number of models for bending A-tract DNA. The junction-bending model postulates that the structure of A-tracts is similar to the fiber diffraction structure of poly A, in which there is a significant degree of base pair tilt with respect to the helix axis. In this model, bending occurs at the junction between the A-tract and the B-form helix to allow favorable stacking interactions to occur. The bend of the helix could arise as a result of some other perturbation of B-form DNA by A-tracts, such as propeller twist; bending also could be due to a combination of factors. Our goal is to find the structural features of A-tracts responsible for bending of the helix by performing NMR on oligonucleotides containing A-tracts to obtain higher resolution structural data. One of the problems encountered in NMR structure determination of nucleic acids and other macromolecules is the assignment of resonances to nuclei. This procedure can be greatly facilitated through the use of {sup 13}C-enriched nucleic acid samples. We are developing a technique for the enzymatic synthesis of labeled DNA for NMR. The technique we are developing is similar to RNA labeling techniques already in use. The technique involves growth of methylotrophic bacteria on {sup 13}CH{sub 3}OH.

  16. 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

  17. "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.

  18. Structural properties and out-of-plane stability of roller bent steel arches

    NARCIS (Netherlands)

    Spoorenberg, R.C.

    2011-01-01

    In contemporary architecture the use of steel arches has seen a significant increase. They are applied in buildings and large span bridges, combining structural design with architectural merits. For arches lacking lateral support (or freestanding arches) the out-of-plane structural stability

  19. Out-of-plane buckling of roller bent wide flange arches - imperfections and finite element modeling

    NARCIS (Netherlands)

    Spoorenberg, R.C.; Snijder, H.H.; Hoenderkamp, J.C.D.; Beg, D.; Chan, S.L.; Shu, G.P.

    2012-01-01

    Steel arches are used more and more in contemporary architecture, combining structural efficiency with architectural merits. If lateral supports are absent, these arches are prone to out-of-plane buckling. Arches are often made by cold bending wide flange beams at ambient temperature. This

  20. '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

  1. 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,…

  2. A comparison of performance of flat and bent photovoltaic luminescent solar concentrators

    NARCIS (Netherlands)

    Vishwanathan, B.; Reinders, A. H.M.E.; de Boer, D.K.G.; Desmet, L.; Ras, A. J.M.; Zahn, F. H.; Debije, M.G.

    2015-01-01

    To employ new solar photovoltaic technologies in products and buildings, many systems need to be adapted. Inspired by the cylindrical shape, in this work we have evaluated the performance of luminescent solar concentrator photovoltaic (LSC-PV) elements with narrow PV cell strips that could be

  3. 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

  4. 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.

  5. 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

  6. Sistemática de Foraminíferos Bentónicos de playa Gómez isla Gorgona

    Directory of Open Access Journals (Sweden)

    Concha Londoño de Hoyos

    1996-01-01

    Full Text Available One hundred species of benthonic Foraminifera grouped in 46 genera, 22 families, 9 superfamilies and 3 suborders were identified. The total number of individuals studied was 1.445; according to the data repported by the literature on benthonic Foraminifera, 77% of the individuals studied could be considered as in sifu fauna, the rernaining 23% are considered as displaced tests.

  7. 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

    Spanish maps of New Mexico, such as the "Jornada del Muerto" and the "Llanos sin Agua " (Miera y Pacheco 1778). Accommodations to these limitations also... reused for purposes other than those intended by the manufacturer, for example, bottle glass worked into scrapers. Data entered in artifact tables

  8. 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

  9. Spontaneous and stimulated undulator radiation by an ultra-relativistic positron channeling in a periodically bent crystal

    International Nuclear Information System (INIS)

    Krause, W.; Korol, A.V.; Solov'yov, A.V.; Greiner, W.

    2001-01-01

    We discuss the radiation generated by positrons channeling in a crystalline undulator. The undulator is produced by periodically bending a single crystal with an amplitude much larger than the interplanar spacing. Different approaches for bending the crystal are described and the restrictions on the parameters of the bending are discussed. We also present numeric calculations of the spontaneous emitted radiation and estimate the conditions for stimulated emission. Our investigations show that the proposed mechanism could be an interesting source for high energy photons and is worth to be studied experimentally

  10. A new karst-dwelling bent-toed gecko (Squamata: Gekkonidae: Cyrtodactylus) from Xiangkhoang Province, northeastern Laos.

    Science.gov (United States)

    Nazarov, Roman A; Pauwels, Olivier S G; Konstantinov, Evgeniy L; Chulisov, Anatoliy S; Orlov, Nikolai L; Poyarkov, Nikolay A

    2018-05-18

    We describe a new karst-dwelling Cyrtodactylus from Ban Thathom, Xiangkhoang Province, northeastern Laos. The new species can be distinguished from other congeners by having four dark dorsal bands between limb insertions, a discontinuous nuchal loop, 10 precloacal pores in males or 10-12 precloacal pits (females) separated by a diastema from a series of enlarged femoral scales bearing 18 or 19 pores (male) or 8-10 pits (females) along each femur, 14-18 dorsal tubercle rows at midbody, no precloacal groove, 30-36 midbody scale rows across belly between ventrolateral skin folds, transversely enlarged subcaudal plates, and a maximal known snout-vent length of 75.5 mm. Our description brings to 22 the number of Cyrtodactylus species recorded from Laos.

  11. 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

  12. 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

  13. [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.

  14. 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

  15. 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

  16. 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.

  17. Experimentation and simulation of H.S.L.A. sheet metal bending bent pats behaviour's prediction during working life

    International Nuclear Information System (INIS)

    Avril, Ludovic

    2003-01-01

    A pulsed Nd-YAG laser is used to irradiate and alloy X30Cr13 stainless steel by surface melting, with incorporation of boron or hexagonal boron nitride (h-BN), and to obtain thick coatings: multiphase borided alloys or metal-ceramic composites. The metallographic analyses allow to determine the thickness for each coating (melting zone) and reveal characteristic solidification microstructures: planar front and cellular dendrites. Optical characteristics of the laser beam are measured: divergence, focal length spot radius and power distribution in the focal plane. Heat effect simulations are based on the finite difference modelling of the temporal progression of temperature distribution in the steel irradiated by scanning of the pulsed beam. Melting zone thickness is computed and progression of melting front during irradiation is simulated and so, a better description of the conditions of material incorporation by successive melting and solidifications becomes possible. The mechanical properties, elastic modulus and hardness, of the different coatings are determined from nano-indentation tests. Under optimal irradiation conditions, the hardness reaches 14 GPa for composite coating and 10 GPa for borided alloy, whereas that for untreated steel is 4 GPa. Friction and wear tests are systematically performed in a ball-on-disc configuration, at 25 C under various loads (1 to 10 N), then at 300 and 500 C under 2 N. At ambient temperature, the dry sliding on ruby ball of these two types of coatings is characterized by a reduced friction coefficient and a weak wear rate, compared with the untreated steel, revealing a very reinforced resistance towards adhesive and/or abrasive wear. On the other hand, their wear resistance is decreased from 300 C, in the spite of the significant lowering of friction coefficient. (author)

  18. 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

  19. 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.

  20. Aportación a la flora bentónica de las Islas Baleares. IV. Flora de Ibiza

    Directory of Open Access Journals (Sweden)

    Rull Lluch, J.

    1988-01-01

    Full Text Available In this study 21 taxa from different places in Ibiza are presented. 13 of the mare a new references for the Balearic archipelago and the rest are quite unknown species in these islands. The most important record is Discosporangium mesarthrocarpum (Falkenb. Hauk, until now unknown in the Spanish Mediterranean coast and very seldom reported in the rest of the Mediterranean.

    En este trabajo se presentan 21 táxones procedentes de diferentes localidades de la isla de Ibiza, 13 de los cuales suponen nuevas citas para el archipiélago balear y los restantes son especies poco conocidas en estas islas. Se destaca Discosporangium mesarthrocarpum (Falkenb. Hauck, desconocida hasta ahora en las costas mediterráneas españolas y escasamente citada en el resto de este mar.

  1. Focusing X-rays to a 1-μm spot using elastically bent, graded multilayer coated mirrors

    International Nuclear Information System (INIS)

    Underwood, J.H.; Thompson, A.C.; Kortright, J.B.

    1997-01-01

    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 μm. This has been improved to 1 μm 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

  2. 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.

  3. “A Tree Must Be Bent While It Is Young”: Teaching Urological Surgical Techniques to Schoolchildren

    Science.gov (United States)

    Buntrock, Stefan

    2012-01-01

    Background 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. Objectives To teach surgical skills to schoolchildren in order to attract them to urology as a professional choice later in life. Materials and Methods 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. Results 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. Conclusions Making use of virtual reality to attract and educate a new generation of urologists is an important step in designing the future of urology. PMID:23573467

  4. Development of Bent Perfect Crystal Monochromator (II): Experiments for the evaluation of BPC for a monochromator of neutron diffractometers

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yong Nam; Kim, Shin Ae; Lee, Chang Hee [KAERI, Taejon (Korea, Republic of); Kim, Sung Kyu [Pusan National Univ., Pusan (Korea, Republic of); Kim, Seong Baek [Kookmin Univ., Seoul (Korea, Republic of); Mikula, P. [NPI, Prague (Czech Republic)

    2004-11-01

    Various experimental properties of BPC monochromator at the FCD mode of the ST1 test station have been investigated. To test and verify the performance of the Si-BPC monochromator for the substitutional monochromator, diffraction measurements using copper single crystal and polycrystalline copper rod at various diffraction geometries were carried out. Considering the situation of FCD instrument which is used for both single crystal and texture measurement, a special cut silicon BPC slab which contains (331), (311) and (220) diffraction planes would be a best candidate. Diffraction measurements at the monochromatic focusing is the first experimental demonstration of the theoretical properties and give us a suggestion that the simultaneous measurement at both parallel and anti-parallel diffraction positions could be achievable with a reasonal resolution property as well as the intensity gain.

  5. A new forest-dwelling Bent-toed Gecko (Squamata: Gekkonidae: Cyrtodactylus) from Doi Inthanon, Chiang Mai Province, northern Thailand.

    Science.gov (United States)

    Kunya, Kirati; Sumontha, Montri; Panitvong, Nonn; Dongkumfu, Wuttipong; Sirisamphan, Thana; Pauwels, Olivier S G

    2015-01-14

    We describe a new forest-dwelling Cyrtodactylus from Doi Inthanon, Chiang Mai Province, northern Thailand. Cyrtodactylus inthanon sp. nov. is characterized by a maximum known SVL of 87.3 mm; 18 to 20 longitudinal rows of dorsal tubercles; a continuous series of 34 to 37 enlarged femoro-precloacal scales, including four to six pitted (female) or pore-bearing (male) scales on each femur separated by a diastema from five pitted (females) or pore-bearing (male) precloacal scales; no precloacal groove or depression; transversely enlarged subcaudal scales; and three to five irregular beige dorsal bands between limb insertions. The discovery of a new reptile endemic to Doi Inthanon reinforces the high importance of this mountain in terms of biodiversity conservation.

  6. A new forest-dwelling Bent-toed Gecko (Squamata: Gekkonidae: Cyrtodactylus) from Doi Suthep, Chiang Mai Province, northern Thailand.

    Science.gov (United States)

    Kunya, Kirati; Panmongkol, Aumporn; Pauwels, Olivier S G; Sumontha, Montri; Meewasana, Jiraporn; Bunkhwamdi, Woraphot; Dangsri, Siriwat

    2014-06-03

    We describe a new forest-dwelling Cyrtodactylus from Doi Suthep, Chiang Mai Province, northern Thailand. Cyrtodactylus doisuthep sp. nov. is characterized by a maximal known SVL of 90.5 mm; 19 or 20 longitudinal rows of dorsal tubercles; a continuous series of 34 or 35 enlarged femoro-precloacal scales, including six or seven pitted scales on each femur (male and females) separated by a diastema from six pitted (females) or pore-bearing (male) precloacal scales; no precloacal groove or depression; transversely enlarged subcaudal scales; and six or seven irregular thin beige dorsal bands between limb insertions. 

  7. 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

  8. Focusing Double Bent Crystal (DBC) diffractometer for medium-resolution small-angle. Neutron scattering (SANS) experiments

    International Nuclear Information System (INIS)

    Mikula, P.; Wagner, V.; Scherm, R.

    1991-01-01

    A new modification of a focusing SANS instrument where at least the first crystal is set for diffraction in the asymmetric transmission geometry is presented. Unlike an earlier version which employed both crystals in the symmetric Bragg-case geometry, the new modification permits one simultaneously to exploit the effects of natural wavelength focusing and space condensation of the diffracted beam due to asymmetric diffraction. This DBC instrument seems to be suitable for use with beams with a large cross section at the first crystal and for SANS experiments on samples with a small width (few mm). (orig.)

  9. Bent crystal spectrometer for both frequency and wavenumber resolved x-ray scattering at a seeded free-electron laser.

    Science.gov (United States)

    Zastrau, Ulf; Fletcher, Luke B; Förster, Eckhart; Galtier, Eric Ch; Gamboa, Eliseo; Glenzer, Siegfried H; Heimann, Philipp; Marschner, Heike; Nagler, Bob; Schropp, Andreas; Wehrhan, Ortrud; Lee, Hae Ja

    2014-09-01

    We present a cylindrically curved GaAs x-ray spectrometer with energy resolution ΔE/E = 1.1 × 10(-4) and wave-number resolution of Δk/k = 3 × 10(-3), allowing plasmon scattering at the resolution limits of the Linac Coherent Light Source (LCLS) x-ray free-electron laser. It spans scattering wavenumbers of 3.6 to 5.2/Å in 100 separate bins, with only 0.34% wavenumber blurring. The dispersion of 0.418 eV/13.5 μm agrees with predictions within 1.3%. The reflection homogeneity over the entire wavenumber range was measured and used to normalize the amplitude of scattering spectra. The proposed spectrometer is superior to a mosaic highly annealed pyrolytic graphite spectrometer when the energy resolution needs to be comparable to the LCLS seeded bandwidth of 1 eV and a significant range of wavenumbers must be covered in one exposure.

  10. Variation of local critical current and its influence on overall current of bent multifilamentary Bi2223/Ag tape

    International Nuclear Information System (INIS)

    Ochiai, S.; Doko, D.; Rokkaku, H.; Fujimoto, M.; Okuda, H.; Hojo, M.; Tanaka, M.; Sugano, M.; Osamura, K.; Mimura, M.

    2006-01-01

    The correlation between the local and overall currents in a multifilamentary Bi2223/Ag/Ag alloy composite tape under bending strain was studied. The correlation of the measured distributed local critical current and n-value to overall critical current was described comprehensively with a voltage summation model that regards the overall sample to be composed of a series circuit. The analysis of the measured critical current and n-value revealed that the distribution of local critical current could be described with the Weibull distribution function and the n-value could be expressed as a function of critical current as a first approximation. By combining the Weibull distribution function of the local critical current, the empirical formula of the n-value as a function of critical current, voltage summation model and Monte Carlo method, the overall current and n-value could be predicted fairly well from those of local elements

  11. Multidisciplinary Restoration of Traumatized and Displaced Maxillary Central Incisor by Bent Wire System-A Novel Approach.

    Science.gov (United States)

    Sasalawad, Shilpa S; Jogani, Vivek; Pai, Suryakanth M; Chour, Rashmi C; Balehosur, Deepti V

    2016-11-01

    Management of traumatic injuries to teeth is a challenge to dental practice, as it occurs when dentists are least prepared for it. The direction and the force of the object or the fall significantly affects the diagnosis, treatment plan and therefore the outcome of the treatment. These traumatic injuries may present with different clinical situations which demand immediate attention and assessment by the clinician. The maxillary central incisor crown fractures are the most common variant of trauma, because of the anterior and protrusive positioning. This case report describes the novel method to produce expansion of the dental arches to correct the post-traumatic displacement of the central incisor along with aesthetic and functional rehabilitation of Ellis Class IV fracture of permanent maxillary central incisor.

  12. Residual stress evaluation by X-Ray diffraction and hole-drilling in an API 5L X70 steel pipe bent by hot induction

    International Nuclear Information System (INIS)

    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

    2016-01-01

    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)

  13. Composición de la macrofauna bentónica en substratos sedimentarios del Parque Nacional Isla del Coco, Costa Rica

    OpenAIRE

    Sibaja Cordero, Jeffrey

    2012-01-01

    [spa] El Parque Nacional Isla del Coco (PNIC), en Costa Rica, posee una alta biodiversidad; esto por representar un punto de unión de las faunas de ambos lados del Pacífico, las Galápagos y una zona de endemismo. Sin embargo, pocos trabajos se han realizado sobre ecología del sedimento marino. Además para la Isla del Coco datos de granulometría y materia orgánica son inexistentes. Esta memoria presenta información sobre los tópicos antes mencionados, para una mejor comprensión de los procesos...

  14. 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

  15. 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)

  16. X-ray absorption tomography of a high-pressure metal-halide lamp with a bent arc due to Lorentz-forces

    NARCIS (Netherlands)

    Denisova, N.; Haverlag, M.; Ridderhof, E.J.; Nimalasuriya, T.; Mullen, van der J.J.A.M.

    2007-01-01

    The arc temperature is one of the most important characteristics which cotrol the emission properties of plasma light sources. X-ray absorption technique has received some attention as a powerful method to determine the temperature in high-pressure metal-halide lamps. An important advantage of x-ray

  17. Minimization of spurious strains by using a Si bent-perfect-crystal monochromator: neutron surface strain scanning of a shot-peened sample

    Science.gov (United States)

    Rebelo Kornmeier, Joana; Gibmeier, Jens; Hofmann, Michael

    2011-06-01

    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.

  18. 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

  19. 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)

  20. 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.

  1. Assessment of the effect of No Stay, Bent Stay or Straight Stay when the Clothe the Soldier Rucksack is Worn with the Fragmentation Vest

    National Research Council Canada - National Science Library

    Reid, S. A; Stevenson, J. M; Kudryk, I

    2006-01-01

    ...) with Bullet Resistant Plates (BRP), Tactical Vest (TV), the Rucksack, and a Small Pack System which have been designed to be compatible Loads carried in the CTS rucksack often exceed the officially recommended 25 kg and are reported to approach 45 kg...

  2. 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 ...

  3. 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.

  4. 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

    rights, franchises and appurtainances thereunto belonging and, also all that certain piece or parcel of land being and situated within the distance of...saddler. Two ice-houses near the bluff were used for ice storage during the warm months. The post bakery was built of sandstone and measured 24 feet by 46

  5. Ostrácodos bentónicos de dos transectos: bahía de Tumaco y Punta El Coco e Isla Gorgona, Pacífico colombiano

    Directory of Open Access Journals (Sweden)

    Lucy Reyes

    1995-01-01

    between 4 and 90 m deed, while aboard Pacific cruiser IX-ERFEN VI, in 1986. 20 species (220 individualsl belonging to 15 genera and grouped in 8 families were studied of wich the best represented are Trachyleberididae and Cytheruridae. The species with de major number of individuals are: Palmoconcha laevimarginata Swain and Gilby and Pterigocythereis semitranslucens Crouch. In general it could be said that the population found, correspond to a typical Pacific faunistic grouping, characterized by a large diversity and a low abundance of the group. It is observe that the abundance is determined by certain characteristics of the sampling zone. Thus, there is a low number of individuals in the bay of Tumaco and a mayor number of them in the area Iying between Punta El Coco and Gorgona island.

  6. [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)

  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. 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.

  9. 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.

  10. Quantitative structure of a complex between a minor-groove-specific drug and a bent DNA decamer duplex: Use of 2D NMR data and NOESY constrained energy minimization

    International Nuclear Information System (INIS)

    Sarma, M.H.; Gupta, G.; Garcia, A.E.; Umemoto, K.; Sarma, R.H.

    1990-01-01

    Two-dimensional nuclear magnetic resonance (2D NMR) studies on d(GA4T4C)2 and d(GT4A4C)2 showed that A.T pairs are propeller twisted. As a result, A/T tracts form a straight rigid structural block with an array of bifurcated inter base pair H bonds in the major groove. It was demonstrated (previous paper) that replacement of methyl group by hydrogen (changing from T to U) in the major groove does not disrupt the array of bifurcated H bonds in the major groove. In this article, we summarize results of 2D NMR and molecular mechanic studies on the effect of a minor-groove-binding A.T-specific drug on the structure d(GA4T4C)2. A distamycin analogue (Dst2) was used for this study. It is shown that Dst2 binds to the minor groove of d(GA4T4C)2 mainly driven by van der Waals interaction between A.T pairs and the drug; as a consequence, an array of bifurcated H bonds can be formed in the minor groove between amide/amino protons of Dst2 and A.T pairs of DNA. NOESY data suggest that Dst2 predominantly binds at the central 5 A.T pairs. NOESY data also reveal that, upon drug binding, d(GA4T4C)2 does not undergo any significant change in conformation from the free state; i.e., propeller-twisted A.T pairs are still present in DNA and hence the array of bifurcated H bonds must be preserved in the major groove. NOESY data for the A5-T6 sequence also indicate that there is little change in junction stereochemistry upon drug binding

  11. 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.

  12. Foraminíferos bentónicos como indicadores paleoecológicos de la Formación Uscari (Mioceno Temprano-Medio), Cuenca de Limón (Sur), Costa Rica

    OpenAIRE

    Betancur, Julliet

    2014-01-01

    La Formación Uscari (en los ríos Torito y Calvario, y las secciones 3X, Peralta y Alto Guayacán), muestra una somerización desde zonas batiales inferiores hasta zonas neríticas durante el Mioceno Temprano. En el Mioceno Medio cambia nuevamente a zonas batiales no tan profundas como las alcanzadas en el área de 3X, durante el intervalo anterior. Durante el Mioceno Temprano las zonas batiales estuvieron caracterizadas por ambientes eutróficos a mesotróficos depositadas bajo condiciones de surge...

  13. 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

    prison: a regime that plays a big role in the Nordic prison practices. In the article, I am investigating how inmates experience the transition from a closed to an open prison regime, and how it feels to serve time in a regime without prison walls. In addition, I am looking at how inmates experience......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...

  14. Estudio de la biología trófica de cinco especies de peces bentónicos de la costa de Cullera. Relaciones con la acumulación de metales pesados

    OpenAIRE

    JARAMILLO LONDOÑO, ÁNGELA MARÍA

    2010-01-01

    Los estudios acerca de la ecología trófica de los peces, en los cuales se relacionan la biología y fisiología de las especies con su hábitat, régimen alimentario, tipo de dieta y relaciones bióticas, aportan información básica y necesaria para comprender el papel ecológico que desempeñan estos organismos dentro del ecosistema que habitan, y por lo tanto para establecer protocolos de gestión de sus poblaciones. Esta tesis aporta un mayor conocimiento de la biología, fenología y hábitos alim...

  15. 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.

  16. 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.

  17. As relações de organismos bentônicos bioindicadores com a poluição por metais e metaloides em represas do sistema Cantareira, São Paulo

    OpenAIRE

    Beghelli, Frederico

    2016-01-01

    Vivemos atualmente, um cenário de crise hídrica mundial. Tal crise inclui tanto aspectos quantitativos quanto qualitativos ameaçando a segurança hídrica das sociedades humanas e os ecossistemas do planeta Terra. No Brasil, a região hidrográfica do Paraná destaca-se como região com maior densidade populacional, desenvolvimento econômico e industrial do país sendo, portanto, a região com maior demanda pelo recurso. No Estado de São Paulo desenha-se uma situação de crise hídrica agravada em ambo...

  18. Aspectos do ciclo de vida de espécies bentônicas nativas e sua utilização na avaliação da qualidade de sedimentos de lagos naturais e reservatórios

    OpenAIRE

    Caio Augusto de Almeida

    2007-01-01

    Os estudos ecológicos, com vistas para a conservação do meio ambiente, vêm sendo intensificados desde meados do século XX. Devido à integração com várias outras ciências durante o processo de formação do conhecimento ecológico, esses estudos têm se tornado essenciais para o desenvolvimento de tecnologias e de políticas adequadas ao gerenciamento dos recursos naturais, em especial dos recursos hídricos. Estudos que contemplem a comparação entre sistemas naturais e artificiais são importantes n...

  19. 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...

  20. 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 ...

  1. Fault diagnosis in rotating machinery by vibration analysis

    International Nuclear Information System (INIS)

    Behzad, M.; Asayesh, M.

    2002-01-01

    Dynamic behavior of unbalanced bent shaft has been investigated in this research. Finite element method is used for unbalance response calculation of a bent shaft. The result shows the effect of bent on the unbalance response. The angle between bent vector and unbalance force, position and type of supports, shaft diameter and disk position can affect the outcome. The results of this research can significantly help in fault diagnosis in rotating machinery

  2. 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)

  3. 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...

  4. 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.

  5. 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

  6. "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.

  7. Algas marinhas bentônicas da Reserva Biológica Estadual da Praia do Sul, Ilha Grande, Angra dos Reis, Rio de Janeiro, Brasil Benthic marine algae of the State Biological Reserve of Praia do Sul, Ilha Grande, Angra dos Reis, Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    Lísia Mônica de Souza Gestinari

    1998-04-01

    Full Text Available Na Reserva foram encontradas 121 espécies, sendo 27 de Chlorophyceae, 21 de Phaeophyceae e 73 de Rhodophyceae. Dentre estas espécies, 38 são novas referências para a ilha, sendo que Cladophora catenata (L. Kütz. é pela primeira vez citada para o litoral do Rio de Janeiro. Não foram encontradas espécies endêmicas e nem flora específica de região insular. A comparação da flora da Reserva com a de regiões vizinhas indica alta percentagem de espécies em comum entre elas.A survey in the Reserve showed 27 species of Chlorophyceae, 21 of Phaeophyceae and 73 of Rhodophyceae. Among the recorded species, 38 are new references to the Island and Cladophora catenata (L. Kütz. is for the first time quoted to the Rio de Janeiro coast. Neither endemic species nor specific flora from insular area were found in the Reserve. A comparison between the flora of the Reserve and those of neighboring areas, showed a high percentage of similarity.

  8. 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"...

  9. Tæt på relationen

    DEFF Research Database (Denmark)

    Siersted, Mette

    1998-01-01

    sættes på begreb : teori og metode / Janne Hedegaard Hansen og Bent Madsen ; Velfærdsstaten i det moderne. Bent Madsen: Refleksion og fortolkning - i lyset af George Herbert Meads symbolske interaktionisme ; At beskrive praksis : fra empiri til praksisportræt. Med praksis som kilde til kundskab : otte...

  10. 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)

  11. Kold krig anno 2014

    DEFF Research Database (Denmark)

    Lund, Joachim

    2014-01-01

    Anmeldelse af: ' Ulve, får og vogtere - Den Kolde Krig i Danmark 1945-1991'. Bent Jensen. Gyldendal, 2014. 1.512 sider. 799 kroner.......Anmeldelse af: ' Ulve, får og vogtere - Den Kolde Krig i Danmark 1945-1991'. Bent Jensen. Gyldendal, 2014. 1.512 sider. 799 kroner....

  12. 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.

  13. 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.

  14. The "Global" Formulation of Thermodynamics and the First Law: 50 Years On

    Science.gov (United States)

    Gislason, Eric A.; Craig, Norman C.

    2011-01-01

    Nearly 50 years ago, Henry Bent published his groundbreaking article in this "Journal" introducing the "global" formulation of thermodynamics. In the following years, the global formulation was elaborated by Bent and by one of the present authors. The global formulation of the first law focuses on conservation of energy and the recognition that…

  15. 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...

  16. 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, ...

  17. 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.

  18. 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.

  19. Erectile Dysfunction: MedlinePlus Health Topic

    Science.gov (United States)

    ... Men's Health (Hormone Health Network) Also in Spanish Sex and the Man With Cancer (American Cancer Society) Also in Spanish Specifics Bent Penis (Mayo Foundation for Medical Education and Research) Videos and Tutorials Simultaneous Inflatable Penile Prosthesis (IPP) and ...

  20. Observeren in drie minuten

    NARCIS (Netherlands)

    van der Lans, Rikkert

    2017-01-01

    Stel, je bent een schoolleider van een locatie met vijftig leraren en je wilt lesobservaties gaan inzetten. Er zijn zo’n vier lesbezoeken per leraar nodig voor betrouwbare feedback. Hoe passen tweehonderd lesobservaties in de agenda?

  1. 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...

  2. Posterior Cruciate Ligament Injury

    Science.gov (United States)

    ... your knee is bent also can cause this injury. Risk factors Being in a motor vehicle accident and participating in sports such as football and soccer are the most common risk factors for a PCL injury. Complications In ...

  3. 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 ...

  4. Prevention: Exercise

    Medline Plus

    Full Text Available ... hips and knees bent. Use your hips to push your body back to a standing position, then ... your forehead, then use your neck muscles to push against your palm. Hold for ten seconds and ...

  5. Sonohysterography

    Medline Plus

    Full Text Available ... with you lying on your back, possibly with your feet in stirrups similar to a gynecologic exam. Doppler ... on your back with your knees bent or your feet in stirrups. The cervix will be cleansed, and ...

  6. Decay of Hoyle state

    Indian Academy of Sciences (India)

    2014-11-02

    Nov 2, 2014 ... T K RANA, C BHATTACHARYA, S KUNDU, ... of various direct 3α decay mechanisms of the Hoyle state. ... Pramana – J. Phys., Vol. ... FMD predicts a compact triangle shape and LEFT predicts a bent arm chain structure,.

  7. Hysterosalpingography

    Medline Plus

    Full Text Available ... her back on the exam table, with her knees bent or her feet held up with stirrups ... of the abdominal cavity, causing generalized lower abdominal pain, but this should also be minimal and not ...

  8. Sonohysterography

    Medline Plus

    Full Text Available ... as you lie on your back with your knees bent or your feet in stirrups. The cervix ... performed to look for a cause of pelvic pain, the sonogram itself should not be painful or ...

  9. 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.

  10. 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 ...

  11. Agrobacterium tumefaciens-mediated transformation of biofuel plant ...

    African Journals Online (AJOL)

    Yomi

    2010-09-27

    Sep 27, 2010 ... several plant species including Arabidopsis (Chang et al.,. 1994; Clough and Bent, ... and Technology Talents Scheme of Yunnan Province. (Grant no. .... of shoots and roots from Jatropha curcas L. explants. J. Horticult. Sci.

  12. 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"

  13. Hysterosalpingography

    Medline Plus

    Full Text Available ... pregnant by allowing the radiologist to evaluate the shape and structure of the uterus, the openness of ... exam table, with her knees bent or her feet held up with stirrups and a speculum is ...

  14. Penis Health: Identify and Prevent Problems

    Science.gov (United States)

    ... erection or orgasm. Aggressive or acrobatic sex or masturbation. If your penis is bent suddenly or forcefully ... can significantly reduce your risk of erectile dysfunction. Practice good hygiene. If you're not circumcised, regularly ...

  15. Diagnostics of laser-produced plasmas

    Directory of Open Access Journals (Sweden)

    Batani Dimitri

    2016-12-01

    Full Text Available We present the general challenges of plasma diagnostics for laser-produced plasmas and give a few more detailed examples: spherically bent crystals for X-ray imaging, velocity interferometers (VISAR for shock studies, and proton radiography.

  16. Trigger Finger

    Science.gov (United States)

    ... in a bent position. People whose work or hobbies require repetitive gripping actions are at higher risk ... developing trigger finger include: Repeated gripping. Occupations and hobbies that involve repetitive hand use and prolonged gripping ...

  17. 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 ...

  18. Phase transformation kinetics and microstructure of NiTi shape ...

    Indian Academy of Sciences (India)

    2017-07-28

    Jul 28, 2017 ... exhibiting thermoelastic martensitic transition is deformed or bent at a temperature ... Memory-Metalle Gmbh, Germany. The nominal composi- ... ture Ap, martensite peak temperature Mp and absorbed energy values during ...

  19. Genetics Home Reference: congenital contractural arachnodactyly

    Science.gov (United States)

    ... underdeveloped muscles, a rounded upper back that also curves to the side ( kyphoscoliosis ), permanently bent fingers and ... Information What information about a genetic condition can statistics provide? Why are some genetic conditions more common ...

  20. 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 ...

  1. 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 ...

  2. 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...

  3. Language and embodied consciousness: A Peircean ontological ...

    African Journals Online (AJOL)

    An ontology of language: its source and place in First Language ... knowledge they supposedly gain in school with their immediate environment and their lived .... looking stick in space looks bent at the point it enters the medium of water.

  4. Degree of coupling in high-rise mixed shear walls structures

    Indian Academy of Sciences (India)

    assessment of the structural behaviour of coupled shear wall bents in mixed shear wall ... efficient lateral load resisting system against wind and earthquake effects. .... can be obtained from the second derivative of equation (11) which must be ...

  5. Short-wavelength InAlGaAs/AlGaAs quantum dot superluminescent diodes

    Science.gov (United States)

    Liang, De-Chun; An, Qi; Jin, Peng; Li, Xin-Kun; Wei, Heng; Wu, Ju; Wang, Zhan-Guo

    2011-10-01

    This paper reports the fabrication of J-shaped bent-waveguide superluminescent diodes utilizing an InAlGaAs/AlGaAs quantum dot active region. The emission spectrum of the device is centred at 884 nm with a full width at half maximum of 37 nm and an output power of 18 mW. By incorporating an Al composition into the quantum dot active region, short-wavelength superluminescent diode devices can be obtained. An intersection was found for the light power-injection current curves measured from the straight-waveguide facet and the bent-waveguide facet, respectively. The result is attributed to the conjunct effects of the gain and the additional loss of the bent waveguide. A numerical simulation is performed to verify the qualitative explanation. It is shown that bent waveguide loss is an important factor that affects the output power of J-shaped superluminescent diode devices.

  6. Monitoring of Moisture in Transformer Oil Using Optical Fiber as Sensor

    OpenAIRE

    S. Laskar; S. Bordoloi

    2013-01-01

    This paper describes an optical fiber sensor and temperature sensor-based instrumentation system to measure the moisture content in transformer oil. The sensor system consists of (i) Diode Laser Source, (ii) a bare and bent multimode fiber as sensor probe, (iii) an LDR as detector, (iv) LM35-based temperature sensor, and (v) microcontroller system having a trained ANN for processing and calibration. The bare and bent optical fiber sensor and the temperature sensor LM35 are used to provide the...

  7. Effects of Herbal Supplements on PTSD-Induced Changes in Rat Behavior & Brain Gene Expression

    Science.gov (United States)

    2014-06-10

    Corporation; 2008. 14. Bent S. Herbal medicine in the United States: review of efficacy, safety, and regulation: grand rounds at University of...Ceremuga, Thomas COL (Ret) USU Project Number: N10-P12 70. Bent S: Herbal medicine in the United States: review of efficacy, safety, and regulation...2012;177(7):814-822. 135. Ang-Lee MK, Moss J, Yuan CS. Herbal medicines and perioperative care. Jama. Jul 11 2001;286(2):208-216. 136. Jankowsi K

  8. The superluminal radio source 4c 39. 25 as relativistic jet prototype. El cuasar superluminal 4C 93. 25 como prototipo de jet relativistia

    Energy Technology Data Exchange (ETDEWEB)

    Alberdi, A.; Gomez, J.L.; Marcaide, J.M.

    1993-01-01

    We have developed a numerical code which solves the synchrotron radiation transfer equations to compute the total and polarized emission of bent shocked relativistic jets, and we have applied it to reproduce the compact structure, kinematic evolution of the superluminal radio source 4C 39.25 contains a bent relativistic jet which is misaligned relative to the observer near the core region, leading to a relatively low core brightness. (Author) 12 refs.

  9. Acoustic Liners for Turbine Engines

    Science.gov (United States)

    Jones, Michael G (Inventor); Grady, Joseph E (Inventor); Kiser, James D. (Inventor); Miller, Christopher (Inventor); Heidmann, James D. (Inventor)

    2016-01-01

    An improved acoustic liner for turbine engines is disclosed. The acoustic liner may include a straight cell section including a plurality of cells with straight chambers. The acoustic liner may also include a bent cell section including one or more cells that are bent to extend chamber length without increasing the overall height of the acoustic liner by the entire chamber length. In some cases, holes are placed between cell chambers in addition to bending the cells, or instead of bending the cells.

  10. 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....

  11. 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...

  12. Are Sb4n (n>1) clusters weakly interacting tetrahedra?

    International Nuclear Information System (INIS)

    Kumar, V.

    1993-03-01

    The electronic and atomic structure of Sb 4 and Sb 8 clusters is studied using the ab-initio molecular dynamics method in the local density approximation. While for Sb 4 we obtain a regular tetrahedron to be about 2.0 eV lower in energy than a bent rhombus, for Sb 8 two structures, (1) two weakly interaction tetrahedra and (2) a bent rhombus interacting with a stretched tetrahedron, obtained from the simulated annealing lie only within about 0.1 eV indicating the importance of the bent rhombus structure for larger clusters. As compared to two isolated tetrahedra, the binding energy of Sb 8 is about 0.5 eV. Our results are thus in excellent agreement with the experimental data which show predominantly the abundance of tetramers above room temperature. (author). 18 refs, 5 figs, 1 tab

  13. Adsorption structure of dimethyl ether on silicalite-1 zeolite determined using single-crystal X-ray diffraction

    International Nuclear Information System (INIS)

    Fujiyama, Shinjiro; Seino, Shintaro; Kamiya, Natsumi; Nishi, Koji; Yokomori, Yoshinobu

    2014-01-01

    The most stable sorption site of dimethyl ether on silicalite-1 is the sinusoidal channel. The configuration of guest molecules (linear or bent) plays an important role in determining where the stable sorption site is situated. The adsorption structures of dimethyl ether (DME) on silicalite-1 zeolite (MFI-type) are determined using single-crystal X-ray diffraction. The structure of low-loaded DME-silicalite-1 indicates that all DME molecules are located in the sinusoidal channel, which is the most stable sorption site based on the van der Waals interaction between DME and the framework. The configuration of guest molecules (linear or bent) plays an important role in determining where the stable sorption site is in the pore system of MFI-type zeolites. Bent molecules favor the sinusoidal channel, while linear molecules favor the straight channel. The contribution of DME–DME interactions is considerable in the high-loaded DME-silicalite-1 structure

  14. Observation of channeling for 6500 GeV/c protons in the crystal assisted collimation setup for LHC

    Energy Technology Data Exchange (ETDEWEB)

    Scandale, W. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Laboratoire de l' Accelerateur Lineaire (LAL), Universite Paris Sud Orsay, Orsay (France); INFN Sezione di Roma, Piazzale Aldo Moro 2, 00185 Rome (Italy); Arduini, G.; Butcher, M.; Cerutti, F.; Garattini, M.; Gilardoni, S.; Lechner, A.; Losito, R.; Masi, A.; Mirarchi, D.; Montesano, S.; Redaelli, S. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Rossi, R. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); INFN Sezione di Roma, Piazzale Aldo Moro 2, 00185 Rome (Italy); Schoofs, P. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Smirnov, G. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); INFN Sezione di Roma, Piazzale Aldo Moro 2, 00185 Rome (Italy); Valentino, G. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Breton, D.; Burmistrov, L.; Chaumat, V.; Dubos, S. [Laboratoire de l' Accelerateur Lineaire (LAL), Universite Paris Sud Orsay, Orsay (France); and others

    2016-07-10

    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.

  15. Observation of channeling for 6500 GeV/c protons in the crystal assisted collimation setup for LHC

    International Nuclear Information System (INIS)

    Scandale, W.; Arduini, G.; Butcher, M.; Cerutti, F.; Garattini, M.; Gilardoni, S.; Lechner, A.; Losito, R.; Masi, A.; Mirarchi, D.; Montesano, S.; Redaelli, S.; Rossi, R.; Schoofs, P.; Smirnov, G.; Valentino, G.; Breton, D.; Burmistrov, L.; Chaumat, V.; Dubos, S.

    2016-01-01

    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.

  16. 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.

  17. Channeling and dechanneling at high energy

    International Nuclear Information System (INIS)

    Carrigan, R.A. Jr.

    1987-01-01

    The possibility of using channeling as a tool for high energy particle physics has now been extensively investigated. Bent crystals have been used as an accelerator extraction element and for particle deflection. Applications as accelerating devices have been discussed but appear remote. The major advantage in using a bent crystal rather than a magnet is the large deflection that can be achieved in a short length. The major disadvantage is the low transmission. A good understanding of dechanneling is important for applications. 43 refs., 1 fig., 3 tabs

  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. Relativistic jet with shock waves like model of superluminal radio source. Jet relativista con ondas de choque como modelo de radio fuentes superluminales

    Energy Technology Data Exchange (ETDEWEB)

    Alberdi, A.; Gomez, J.L.; Marcaide, J.M.

    1993-01-01

    The structure of the compact radio sources at milliarcsecond angular resolution can be explained in terms of shock waves propagating along bent jets. These jets consist of narrow-angle cones of plasma flowing at bulk relativistic velocities, within tangled magnetic fields, emitting synchrotron radiation. We have developed a numerical code which solves the synchrotron radiation transfer equations to compute the total and polarized emission of bent shocked relativistic jets, and we have applied it to reproduce the compact structure, kenimatic evolution and time flux density evolution of the superluminal radio source 4C 39.25 and to obtain its jet physical parameters. (Author) 23 ref.

  20. 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...... previously discovered in the Madsen group for the direct coupling of alcohols and amines to amides under dihydrogen liberation. The goal was to synthesize isolatable ruthenium catalysts and two 18-electron complexes capable of performing the reaction in excellent yields were prepared and characterized...

  1. 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.

  2. A horizontal two-axis diffractometer for high-energy X-ray diffraction using synchrotron radiation on bending magnet beamline BL04B2 at SPring-8

    CERN Document Server

    Kohara, S; Kashihara, Y; Matsumoto, N; Umesaki, N; Sakai, I

    2001-01-01

    A horizontal two-axis diffractometer for glasses and liquids, installed at SPring-8 bending magnet beamline BL04B2, operated at 8 GeV electron energy, is described. Photon energies of 37.8 and 61.7 keV were obtained using a bent Si (1 1 1) crystal and a bent Si (2 2 0) crystal, respectively. The instrument has been successfully applied to measure diffraction spectra of vitreous SiO sub 2 in transmission geometry up to scattering vector Q=36 A sup - sup 1 , and measured total structure factor S(Q) was well reproduced by reverse Monte Carlo modelling.

  3. A horizontal two-axis diffractometer for high-energy X-ray diffraction using synchrotron radiation on bending magnet beamline BL04B2 at SPring-8

    International Nuclear Information System (INIS)

    Kohara, Shinji; Suzuya, Kentaro; Kashihara, Yasuharu; Matsumoto, Norimasa; Umesaki, Norimasa; Sakai, Ichiro

    2001-01-01

    A horizontal two-axis diffractometer for glasses and liquids, installed at SPring-8 bending magnet beamline BL04B2, operated at 8 GeV electron energy, is described. Photon energies of 37.8 and 61.7 keV were obtained using a bent Si (1 1 1) crystal and a bent Si (2 2 0) crystal, respectively. The instrument has been successfully applied to measure diffraction spectra of vitreous SiO 2 in transmission geometry up to scattering vector Q=36 A -1 , and measured total structure factor S(Q) was well reproduced by reverse Monte Carlo modelling

  4. Papel ecológico en la cadena trófica de los peces que pasan el invierno en ecosistema de la laguna Culbin Sands, NE Escocia: Identificación de las principales interacciones tróficas y comprovación de los efectos del pez Pomatoschistus microps (Pall

    OpenAIRE

    Mariyam Mendonça, Vanda; Raffaelli, David; Boyle, Peter; Emes, Chas

    2007-01-01

    Se estudió el ecosistema de la laguna Culbin Sands, NE Escocia, durante un periodo de tres años (1994-1996) con objeto de identificar los principales acoplamientos tróficos desde invertebrados bentónicos a depredadores epibentónicos, y para evaluar el impacto de los peces que pasan el invierno sobre las comunidades de sus presas. Cada 2-4 semanas, la fauna móvil se muestreó para estudiar su dieta. Las principales interacciones tróficas identificadas, entre invertebrados bentóncos y depredador...

  5. Flujos de oxígeno y nutrientes entre sedimento y columna de agua: caso de las arenas finas infralitorales

    OpenAIRE

    Sospedra Ciscar, Javier

    2016-01-01

    RESUMEN En el metabolismo bentónico de las zonas costeras y someras interactúan de forma compleja un gran número de procesos y factores tanto físicos como químicos y biológicos. La respiración bentónica y la regeneración de nutrientes en los fondos de arenas permeables del infralitoral han sido, tradicionalmente, poco estudiadas, sin embargo, éstas pueden tener una repercusión directa y transcendental en los ecosistemas costeros. Esta tesis tiene como propósito general la de...

  6. Flora ficologica da plataforma continental do litoral setentrional da bacia potiguar (RN), Brasil, com ênfase em chlorophyta

    OpenAIRE

    De Lourdes Montenegro Cocentino, Adilma

    2009-01-01

    Foram estudadas as macroalgas marinhas bentônicas de um habitat pouco explorado (Bacia Potiguar, Rio Grande do Norte, Nordeste do Brasil) e cuja informação florística é rara, para se conhecer a diversidade taxonômica e padrões de distribuição em um infralitoral tropical, onde vários empreendimentos estão em fase de instalação, sendo enfatizadas as Chlorophyta, como indicadoras da qualidade ambiental. Amostragens de macroalgas bentônicas foram feitas, com dois tipos de dragas e ...

  7. Optical forces through guided light deflections

    DEFF Research Database (Denmark)

    Palima, Darwin; Bañas, Andrew Rafael; Vizsnyiczai, Gaszton

    2013-01-01

    . In this work we look into the object shaping aspect and its potential for controlled optical manipulation. Using a simple bent waveguide as example, our numerical simulations show that the guided deflection of light efficiently converts incident light momentum into optical force with one order...

  8. Direct Seeding Scarlet Oak in the North Carolina Mountains

    Science.gov (United States)

    Earl R. Sluder

    1965-01-01

    Seedling establishment rates varied from 0 to 50 percent in a direct seeding study with scarlet oak (Quercus coccinea Muenchh.) on the Bent Creek Experimental Forest near Asheville, North Carolina. Acorns planted 2 inches deep in the spring with screen protection produced the most seedlings; those surface sown without screens in the spring or fall...

  9. Longitudinal mixed-effects models for latent cognitive function

    NARCIS (Netherlands)

    van den Hout, Ardo; Fox, Gerardus J.A.; Muniz-Terrera, Graciela

    2015-01-01

    A mixed-effects regression model with a bent-cable change-point predictor is formulated to describe potential decline of cognitive function over time in the older population. For the individual trajectories, cognitive function is considered to be a latent variable measured through an item response

  10. Trans-sinusoidal maxillary distraction in three cleft patients.

    NARCIS (Netherlands)

    Wenghoefer, M.H.; Martini, M.; Nadjmi, N.; Schutyser, F.A.C.; Jagtman, A.K.; Bergé, S.J.

    2006-01-01

    The trans-sinusoidal maxillary distractor (TS-MD) was used to achieve maxillary advancement in three patients with repaired cleft lip and palate. After preoperative computer-aided planning of the distraction vectors, each TS-MD was bent on a stereolithographic model of the maxilla of the patient.

  11. Erotic Hymns

    DEFF Research Database (Denmark)

    Bonde, Lars Ole

    2012-01-01

    "Erotic Hymns" is a sacred son cycle in which the composer Bent Lorentzen (b. 1935) combines Baroque and contemporary Dansih poetry in a fascinating exploration of the realtionship between erotic and religious experience. The cd is a world premiere recording by baritone Morten Frank Larsen...

  12. Selfies are out - Now we take Healthies

    DEFF Research Database (Denmark)

    Fausing, Bent

    2014-01-01

    This article is about healthy selfies. Images of fit bodies and sweat are the hottest thing in selfies these days. They fit somewhere between recognition and narcissism, says an associate professor and PhD, Bent Fausing, who believes that the fit body is an images of success - and protection...

  13. Louisiana Coastal Area, Louisiana. Freshwater Diversion to Barataria and Breton Sound Basins. Feasibility Study. Volume 1. Draft Main Report. Draft Environmental Impact Statement.

    Science.gov (United States)

    1984-09-01

    and fresh marshes. 5.2.8.3. The study arca saipports r ich popula tions of phytoplankton, zooplankton, bent hos, macroinvertebrates , and numerous small...Foundation and consists primarily of saline marsh with a net-work of bayous, ditches, and lagoons . Rabbit hunting is considered excellent in the area

  14. Element nodes of sports equipment double back flip factions and double back flip hunched performed gymnast in floor exercise

    Directory of Open Access Journals (Sweden)

    V.A. Potop

    2014-07-01

    Full Text Available Purpose: to identify the node elements of sports equipment double back somersault tuck and double back flip bent. To compare the two types of nodes for double somersault. Material : the study involved eight gymnasts (age 12 - 14 years. All finalists in the competition floor exercise - reserve team Romania. The method of video - computer research and method of postural orientation movements. Results : identified nodal elements of sports equipment double back somersault tuck and double back flip bent. In the preparatory phase of motor actions - launcher body posture for reaching is repulsive to flip. In the phase of basic motor action - animation body postures (double back somersault tuck and bent (bent double back flip. Exercises are performed on the ascending and descending parts of the flight path of the demonstration of individual maximum lift height common center of mass. In the final phase of motor actions - final body posture - steady landing. Conclusions : indicators of key elements of sports equipment acrobatic exercises contain new scientific facts kinematic and dynamic structures of motor actions. They are necessary for the development of modern training programs acrobatic exercises in step specialized base preparation.

  15. Wat er gaat gebeuren en waarom

    NARCIS (Netherlands)

    drs. Frans van den Reep

    2012-01-01

    1e en 2e alinea column: Een beetje analyse over hoe ik denk dat het verder gaat in bedrijfsleven en politiek. Met accent op de interne logica van de ontwikkeling zodat je mijn redenering kan zien, eventueel overnemen en voorbereid bent op the next move. Om dit extra toe toelichten heb ik een figuur

  16. Application of a high density adsorbent in expanded bed adsorption ...

    African Journals Online (AJOL)

    PRECIOUS

    2010-01-11

    Jan 11, 2010 ... bent, the EBA process can be performed at high flow velocity or high particulate ... were done by (Gao et al., 2007) for understanding the interaction ..... used was not strong enough to dissociate hydrophobic bond presence or ...

  17. On the ecological genetics of the clonal perennial Agrostis stolonifera

    NARCIS (Netherlands)

    Kik, Christoffel

    1987-01-01

    There have to date been few studies specifically addressed to the evolution of clonal organisms. The present study attempts to fill this gap and aims to analyse the distribution pattern of a clonal plant species, using the wide-spread grass Agrostis stolonifera L.(Creeping Bent) as a model species.

  18. 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…

  19. Determination of ten steroid hormones in animal waste manure and agricultural soil using inverse and integrated clean-up pressurized liquid extraction and gas chromatography-tandem mass spectrometry

    DEFF Research Database (Denmark)

    Hansen, Martin; Krogh, Kristine Andersen; Halling-Sørensen, Bent

    2011-01-01

    ... Martin Hansen , Kristine A. Krogh , Bent Halling ... in a 22 mL PLE cell : firstly by flushing the sample with heptane to remove unwanted matrix components (inverse- PLE , i- PLE ) and secondly, performing internal clean-up (ic- PLE ) and eluting the steroid hormones by attaching an ...

  20. Away with Good Bantus: De-Linking African Language Literature from Culture, "Tribe" and Propriety

    Science.gov (United States)

    Mkhize, Nomalanga

    2016-01-01

    This paper argues that the "institutionalisation" model used by universities to spearhead the intellectualisation of African languages is a non-starter for taking African languages in new creative directions. The major constraint for African language literary culture is that written output has historically been heavily bent towards…

  1. Research Article Special Issue

    African Journals Online (AJOL)

    pc

    2018-03-07

    Mar 7, 2018 ... International License. Libraries Resource ... Firstly, the sunlight searching circuit was made-up for motor driving of a parabolic trough to ... For the structure, zinc plate in the size of 80 cm width wide and 90 cm length was bent ...

  2. What's Hot, What's Not 2013

    Science.gov (United States)

    Raths, David

    2013-01-01

    With the exception of a plague of locusts, it seems as if the past five years have thrown every imaginable challenge at IT--from the incredible shrinking budget to BYOD and now the MOOC monster. For those of a superstitious bent, these were probably just appetizers to the crises that will inevitably accompany a year featuring the number 13 (cue…

  3. In vitro antioxidant, antibacterial and anti-tumor activities of total ...

    African Journals Online (AJOL)

    Purpose: To investigate the in vitro antioxidant, antibacterial and anti-tumor activities of total flavonoids from Elsholtzia densa Benth of Sichuan Province, China. Methods: The total flavonoids of Elsholtzia densa Bent were extracted utilizing the ultrasonic extraction method, and purified by D101 macroporous adsorption resin ...

  4. L-Tromino Tiling of Multilated Chessboards

    Science.gov (United States)

    Gardner, Martin

    2009-01-01

    An "n" x "n" chessboard is called deficient if one square is missing from any spot on the board. Can all deficient boards with a number of cells divisible by 3 be tiled by bent (or L-shaped) trominoes? The answer is yes, with exception of the order-5 board. This paper deals with the general problem plus numerous related puzzles and proofs…

  5. Controversies in orbital reconstruction-III. Biomaterials for orbital reconstruction : a review with clinical recommendations

    NARCIS (Netherlands)

    Dubois, L.; Steenen, S. A.; Gooris, P. J. J.; Bos, R. R. M.; Becking, A. G.

    The goal of orbital reconstruction is to repair trauma defects, to correct the position of the eye anatomically, avoiding enophthalmos, and to restore ocular function. For the reconstruction of (trauma) defects, many surgeons recommend materials that can be bent into an anatomical shape and that

  6. A high resolution powder diffractometer using focusing optics

    Indian Academy of Sciences (India)

    E-mail: siruguri@csr.ernet.in. Abstract. In this paper, we describe the design, construction and performance of a new high resolution neutron powder diffractometer that has been installed at the Dhruva reactor, Trombay, India. The instrument employs novel design concepts like the use of bent, perfect crystal monochromator ...

  7. 76 FR 23288 - Certain Lined Paper Products From the People's Republic of China: Notice of Final Results of the...

    Science.gov (United States)

    2011-04-26

    ... measurement purposes, pages with tapered or rounded edges shall be measured at their longest and widest points... storage. Both ends of the spiral wire are cut and then bent backwards to overlap with the previous coil... the credibility of the Department's verification as well as the reliability of Watanabe's books and...

  8. Ligament-bone interaction in a three-dimensional model of the knee

    NARCIS (Netherlands)

    Blankevoort, L.; Huiskes, H.W.J.

    1991-01-01

    In mathematical knee-joint models, the ligaments are usually represented by straight-line elements, connecting the insertions of the femur and tibia. Such a model may not be valid if a ligament is bent in its course over bony surfaces, particularly not if the resulting redirection of the ligament

  9. Ligament-bone interaction in a three-dimensional model of the knee

    NARCIS (Netherlands)

    Blankevoort, L.; Huiskes, R.

    1991-01-01

    In mathematical knee-joint models, the ligaments are usually represented by straight-line elements, connecting the insertions of the femur and tibia. Such a model may not be valid if a ligament is bent in its course over bony-surfaces, particularly not if the resulting redirection of the ligament

  10. "Gone fishing": modeling diversity in work ethics

    NARCIS (Netherlands)

    Freyberg-Inan, A.; Koçer, R.G.

    2012-01-01

    In his "Anecdote Concerning the Lowering of Productivity", written in 1963, the West-German writer Heinrich Böll humorously contrasts the mindset of an enterprising capitalist, bent on the maximization of profit, with that of a person we might call a profit "satisficer," a maximizer of leisure or

  11. Radioopacity of the right paracardiac lung field due to pectus excavatum (funnel chest)

    International Nuclear Information System (INIS)

    Hoeffel, J.C.; Winants, D.; Marcon, F.; Worms, A.M.

    1990-01-01

    Increased density of the right paracardiac lung field is frequently visible in patients with pectus excavatum. This sign is due to compression of the lungs by the bent costal cartilages of the pectus and should not be interpreted as evidence of pulmonary infiltrate. (orig.) [de

  12. 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...

  13. Exercise physiology

    DEFF Research Database (Denmark)

    Kiens, Bente; Richter, Erik; Wojtaszewski, Jørgen

    2014-01-01

    The passing of Professor Bengt Saltin on September 12, 2014 truly marks the end of an era. As editor of the Journal of Applied Physiology and one of Bengt’s many collaborators and colleagues, I wanted the Journal to celebrate his many seminal contributions by means of an Editorial. Professor Bent...

  14. New banana-type liquid crystal with a methoxy group substituted near the central ring

    Czech Academy of Sciences Publication Activity Database

    Kašpar, Miroslav; Hamplová, Věra; Novotná, Vladimíra; Glogarová, Milada; Vaněk, Přemysl

    2002-01-01

    Roč. 12, - (2002), s. 2221-2224 ISSN 0959-9428 Institutional research plan: CEZ:AV0Z1010914 Keywords : bent-shaped liquid crystal * nm-chiral * B 2 phase Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.683, year: 2002

  15. Prevention: Exercise

    Medline Plus

    Full Text Available ... through your legs to touch the wall, keeping hips and knees bent. Use your hips to push your body back to a standing ... your abdominal wall in. Continue to breathe. Lift hips away from table keeping your head, shoulders and ...

  16. Creation and detection of optical modes with spatial light modulators

    CSIR Research Space (South Africa)

    Forbes, A

    2016-06-01

    Full Text Available (1979). 24. J. A. Davis, K. O. Valade´z, and D. M. Cottrell, “Encoding amplitude and phase information onto a binary phase-only spatial light modulator,” Appl. Opt. 42, 2003–2008 (2003). 25. E. Bolduc, N. Bent, E. Santamato, E. Karimi, and R. W. Boyd...

  17. Direct mapping of light propagation in photonic crystal waveguides

    DEFF Research Database (Denmark)

    Bozhevolnyi, S.I.; Volkov, V.S.; Arentoft, J.

    2002-01-01

    Using near-field optical microscopy, we directly map the propagation of light in the wavelength range of 1510-1560 nm along bent photonic crystal waveguides formed by removing a single row of holes in the triangular 400-nm-period lattice and connected to access ridge waveguides, the structure being...

  18. Reciprocal Learning Strategy in CALL Environment: A Case Study of EFL Teaching at X University in Shanghai

    Science.gov (United States)

    Liu, An; Bu, Yuhua

    2016-01-01

    Colleges and universities in China have been bent on remolding the existing unitary teacher-centered education mode and enhancing students' individualized and autonomous learning with the help of multimedia and cyber technology in order to meet the College English Curriculum Requirements instituted by the Ministry of Education in 2004. Admittedly…

  19. Core-to-core dimers forming switchable mesophase

    Czech Academy of Sciences Publication Activity Database

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

    2017-01-01

    Roč. 53, č. 18 (2017), s. 2721-2724 ISSN 1359-7345 R&D Projects: GA ČR GA15-02843S Institutional support: RVO:68378271 Keywords : liquid crystals * bent- core mesogens * dimers Subject RIV: JJ - Other Materials OBOR OECD: Nano-materials (production and properties) Impact factor: 6.319, year: 2016

  20. Transitivity And The Narrator's Role In Selected TRC Testimonies

    African Journals Online (AJOL)

    Information Technology

    how the different narrators' roles and perspectives on the events shape their ... injustices committed in the past (Truth and Reconciliation of South Africa Report, Vol. ..... testimony, and CDS answers some additional questions from commissioners at .... self-explanatory: CDS construes the police as active participants bent on ...