Stacking fault tetrahedron induced plasticity in copper single crystal

Energy Technology Data Exchange (ETDEWEB)

Zhang, Liang, E-mail: lz592@uowmail.edu.au [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Lu, Cheng, E-mail: chenglu@uow.edu.au [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Tieu, Kiet; Su, Lihong; Zhao, Xing [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Pei, Linqing [Department of Mechanical Engineering, Chongqing University, Chongqing 400044 (China)

2017-01-05

Stacking fault tetrahedron (SFT) is the most common type of vacancy clustered defects in fcc metals and alloys, and can play an important role in the mechanical properties of metallic materials. In this study, molecular dynamics (MD) simulations were carried out to investigate the incipience of plasticity and the underlying atomic mechanisms in copper single crystals with SFT. Different deformation mechanisms of SFT were reported due to the crystal orientations and loading directions (compression and tension). The results showed that the incipient plasticity in crystals with SFT resulted from the heterogeneous dislocation nucleation from SFT, so the stress required for plastic deformation was less than that needed for perfect single crystals. Three crystal orientations ([1 0 0], [1 1 0] and [1 1 1]) were specified in this study because they can represent most of the typical deformation mechanisms of SFT. MD simulations revealed that the structural transformation of SFT was frequent under the applied loading; a metastable SFT structure and the collapse of SFT were usually observed. The structural transformation resulted in a different reduction of yield stress in compression and tension, and also caused a decreased or reversed compression/tension asymmetry. Compressive stress can result in the unfaulting of Frank loop in some crystal orientations. According to the elastic theory of dislocation, the process of unfaulting was closely related to the size of the dislocation loop and the stacking fault energy.

Preparation of Carbon-Encapsulated ZnO Tetrahedron as an Anode Material for Ultralong Cycle Life Performance Lithium-ion Batteries

International Nuclear Information System (INIS)

Ren, Zhimin; Wang, Zhiyu; Chen, Chao; Wang, Jia; Fu, Xinxin; Fan, Chenyao; Qian, Guodong

2014-01-01

Highlights: • A novel architecture of 3D carbon framework to encapsulate ZnO nanocrystals was prepared. • The ZnO@C exhibits ultralong cycle life and high specific capacity when was used as anode. • The in situ carbonization leads to a strong connection between the carbon and ZnO. - ABSTRACT: In this paper we report a novel architecture of three-dimension (3D) carbon framework to encapsulate tetrahedron ZnO nanocrystals that serves as an anode material for lithium-ion batteries (LIBs). The ZnO@C composites are prepared via a simple internal-reflux method combined with subsequent calcination in argon. The amorphous carbon is formed on the surface of the ZnO crystals by in situ carbonization of the surfactant, which leads to a strong connection between the carbon framework and the active materials and guarantees faster charge transfer on the electrode. The ZnO crystal calcined at 500°C (ZnO@C-5) possesses regular tetrahedron shape with a side length of 150-200 nm and all of them are uniformly anchored among the network of amorphous carbon. The developed ZnO@C structures not only improve the electronic conductivity of the electrode, but they also offer a larger volume expansion of ZnO during cycling. As a result, the ZnO@C-5 demonstrates a higher reversible capacity, ultralong cycle life and better rate capability than that of the ZnO@C-7 and pure ZnO crystals. After 300 cycles, the ZnO@C-5 demonstrates a high capacity of 518 mAhg −1 at a current density of 110.7 mAg −1 . Moreover, this simple approach prepared the 3D composites architecture could shed light on the design and synthesis of other transition metal oxides for energy storage

Identification of rotating and vibrating tetrahedrons in the heavy nucleus {sup 208}Pb

Energy Technology Data Exchange (ETDEWEB)

Heusler, A.

2017-11-15

Ten known states in the heavy nucleus {sup 208}Pb at 2.6 < E{sub x} < 7.9 MeV are described by rotating and vibrating tetrahedrons. The 3{sup -} and 4{sup +} yrast states are the first members of the rotational band. A 2{sup ±} doublet state with the 2{sup +} yrast state as one member and the newly recognized 2{sup -} yrast state as the other member, the 1{sup -} yrast state, and the third 0{sup +} state are the heads of the three elementary tetrahedral rotating and vibrating bands. The newly recognized state at E{sub x} = 4142 keV was assigned spin 2 in 1975 and is suggested to have negative parity by the absent {sup 208}Pb(α, α{sup '}) excitation. Four more states at 5.7 < E{sub x} < 7.9 MeV are identified as the next members of the three elementary tetrahedral rotating and vibrating bands. The ambiguous spin assignment to the state at E{sub x} = 7020 keV is settled with 3{sup -}, the state at E{sub x} = 7137 keV is assigned 4{sup -}. (orig.)

Aluminum-centered tetrahedron-octahedron transition in advancing Al-Sb-Te phase change properties.

Science.gov (United States)

Xia, Mengjiao; Ding, Keyuan; Rao, Feng; Li, Xianbin; Wu, Liangcai; Song, Zhitang

2015-02-24

Group IIIA elements, Al, Ga, or In, etc., doped Sb-Te materials have proven good phase change properties, especially the superior data retention ability over popular Ge2Sb2Te5, while their phase transition mechanisms are rarely investigated. In this paper, aiming at the phase transition of Al-Sb-Te materials, we reveal a dominant rule of local structure changes around the Al atoms based on ab initio simulations and nuclear magnetic resonance evidences. By comparing the local chemical environments around Al atoms in respective amorphous and crystalline Al-Sb-Te phases, we believe that Al-centered motifs undergo reversible tetrahedron-octahedron reconfigurations in phase transition process. Such Al-centered local structure rearrangements significantly enhance thermal stability of amorphous phase compared to that of undoped Sb-Te materials, and facilitate a low-energy amorphization due to the weak links among Al-centered and Sb-centered octahedrons. Our studies may provide a useful reference to further understand the underlying physics and optimize performances of all IIIA metal doped Sb-Te phase change materials, prompting the development of NOR/NAND Flash-like phase change memory technology.

Real-Time Study of the Interaction between G-Rich DNA Oligonucleotides and Lead Ion on DNA Tetrahedron-Functionalized Sensing Platform by Dual Polarization Interferometry.

Science.gov (United States)

Wang, Shuang; Lu, Shasha; Zhao, Jiahui; Huang, Jianshe; Yang, Xiurong

2017-11-29

G-quadruplex plays roles in numerous physiological and pathological processes of organisms. Due to the unique properties of G-quadruplex (e.g., forming G4/hemin complexes with catalytic activity and electron acceptability, binding with metal ions, proteins, fluorescent ligands, and so on), it has been widely applied in biosensing. But the formation process of G-quadruplex is not yet fully understood. Here, a DNA tetrahedron platform with higher reproducibility, regenerative ability, and time-saving building process was coupled with dual polarization interferometry technique for the real-time and label-free investigation of the specific interaction process of guanine-rich singled-stranded DNA (G-rich ssDNA) and Pb 2+ . The oriented immobilization of probes greatly decreased the spatial hindrance effect and improved the accessibility of the probes to the Pb 2+ ions. Through real-time monitoring of the whole formation process of the G-quadruplex, we speculated that the probes on the tetrahedron platform initially stood on the sensing surface with a random coil conformation, then the G-rich ssDNA preliminarily formed unstable G-quartets by H-bonding and cation binding, subsequently forming a completely folded and stable quadruplex structure through relatively slow strand rearrangements. On the basis of these studies, we also developed a novel sensing platform for the specific and sensitive determination of Pb 2+ and its chelating agent ethylenediaminetetraacetic acid. This study not only provides a proof-of-concept for conformational dynamics of G-quadruplex-related drugs and pathogenes, but also enriches the biosensor tools by combining nanomaterial with interfaces technique.

Recycled tetrahedron-like CuCl from waste Cu scraps for lithium ion battery anode.

Science.gov (United States)

Hou, Hongying; Yao, Yuan; Liu, Song; Duan, Jixiang; Liao, Qishu; Yu, Chengyi; Li, Dongdong; Dai, Zhipeng

2017-07-01

The wide applications of metal Cu inevitably resulted in a large quantity of waste Cu materials. In order to recover the useful Cu under the mild conditions and reduce the environmental emission, waste Cu scraps were recycled in the form of CuCl powders with high economic value added (EVA) via the facile hydrothermal route. The recycled CuCl powders were characterized in terms of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The results suggested that the recycled CuCl powders consisted of many regular tetrahedron-like micro-particles. Furthermore, in order to reduce the cost of lithium ion battery (LIB) anode and build the connection of waste Cu scraps and LIB, the recycled CuCl powders were evaluated as the anode active material of LIB. As expected, the reversible discharge capacity was about 171.8mAh/g at 2.0C even after 50 cycles, implying the satisfactory cycle stability. Clearly, the satisfactory results may open a new avenue to develop the circular economy and the sustainable energy industry, which would be very important in terms of both the resource recovery and the environmental protection. Copyright © 2017. Published by Elsevier Ltd.

Generalized magnetic susceptibilities in metals: application of the analytic tetrahedron linear energy method to Sc

International Nuclear Information System (INIS)

Rath, J.; Freeman, A.J.

1975-01-01

A detailed study of the generalized susceptibility chi(vector q) of Sc metal determined from an accurate augmented-plane-wave method calculation of its energy-band structure is presented. The calculations were done by means of a computational scheme for chi(vector q) derived as an extension of the work of Jepsen and Andersen and Lehmann and Taut on the density-of-states problem. The procedure yields simple analytic expressions for the chi(vector q) integral inside a tetrahedral microzone of the Brillouin zone which depends only on the volume of the tetrahedron and the differences of the energies at its corners. Constant-matrix-element results have been obtained for Sc which show very good agreement with the results of Liu, Gupta, and Sinha (but with one less peak) and exhibit a first maximum in chi(vector q) at (0, 0, 0.31) 2π/c [vs (0, 0, 0.35) 2π/c obtained by Liu et al.] which relates very well to dilute rare-earth alloy magnetic ordering at vector q/sub m/ = (0, 0, 0.28) 2π/c and to the kink in the LA-phonon dispersion curve at (0, 0, 0.27) 2π/c. (U.S.)

Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

Science.gov (United States)

Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

2014-02-01

Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source-dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10-15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source-dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented.

Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

International Nuclear Information System (INIS)

Kim, Joshua; Zhang, Tiezhi; Lu, Weiguo

2014-01-01

Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source–dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10–15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source–dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented. (paper)

Atomic Scale Picture of the Ion Conduction Mechanism in Tetrahedral Network of Lanthanum Barium Gallate

Energy Technology Data Exchange (ETDEWEB)

Jalarvo, Niina H [ORNL; Gourdon, Olivier [ORNL; Bi, Zhonghe [ORNL; Gout, Delphine J [ORNL; Ohl, Michael E [ORNL; Paranthaman, Mariappan Parans [ORNL

2013-01-01

Combined experimental study of impedance spectroscopy, neutron powder diffraction and quasielastic neutron scattering was performed to shed light into the atomic scale ion migration processes in proton and oxide ion conductor; La0.8Ba1.2GaO3.9 . This material consist of tetrahedral GaO4 units, which are rather flexible and rocking motion of these units promotes the ionic migration process. The oxide ion (vacancy) conduction takes place on channels along c axis, involving a single elementary step, which occurs between adjacent tetrahedron (inter-tetrahedron jump). The proton conduction mechanism consists of intra-tetrahedron and inter-tetrahedron elementary processes. The intra-tetrahedron proton transport is the rate-limiting process, with activation energy of 0.44 eV. The rocking motion of the GaO4 tetrahedron aids the inter-tetrahedral proton transport, which has the activation energy of 0.068 eV.

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African Journals Online (AJOL)

Ley, S.V.; Woodward, P.R. Tetrahedron Letters 1987, 28, 345. 9. Labelled reagents were bought from Aldrich Chemical Company. 10. Davidson, D.; Bernhard, S.A. J. Am. Chem. Soc. 1948, 70, 3426; Philhaja, K.; Sielo,. M. Acta Chem. Scand. 1968, 22, 3053. 11. Baig, M.V.A.; Owen, L.N. J. Chem. Soc. /C 1966, 540: Neises, ...

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Indian Academy of Sciences (India)

IAS Admin

[D C DeJongh and G N Evenson, Tetrahedron Letters, Vol.12, p.4093, 1971.] 7. Ph. Ph. Ph. Ph. ∆. [M Stiles and V Burckhardt, J. Am. Chem. Soc., Vol.86, p.3396,. 1964.] 8. N. CH3COOK. NaNH2. CN. NH. 2. CN. [Y Ogata and K Takagi, J. Am. Chem. Soc., Vol.96, p.5933,. 1974.] 9. HCOOH. [J K Stille, P S Kasper and D R ...

Local Nonobtuse Tetrahedral Refinements of a Cube

Czech Academy of Sciences Publication Activity Database

Korotov, S.; Křížek, Michal

2003-01-01

Roč. 16, - (2003), s. 1101-1104 ISSN 0893-9659 R&D Projects: GA AV ČR IAA1019201 Institutional research plan: CEZ:AV0Z1019905 Keywords : finite-element method * nonobtuse tetrahedron * path tetrahedron Subject RIV: BA - General Mathematics Impact factor: 0.395, year: 2003

silica nanoparticles as a highly efficient catalyst for the one

African Journals Online (AJOL)

Ramazani, A.; Souldozi, A. Phosphorus, Sulfur, Silicon Relat. Elem. 2003, 178, 2663. 14. Souldozi, A.; Ramazani, A.; Bouslimani, N.; Welter, R. Tetrahedron Lett. 2007, 48, 2617. 15. Souldozi, A.; Ramazani, A. Tetrahedron Lett. 2007, 48, 1549. 16. Ramazani, A.; Ahmadi, Y.; Rouhani, M.; Shajari, N.; Souldozi, A. Heteroatom ...

short communication regioselective iodination of aryl amines using 1

African Journals Online (AJOL)

B. S. Chandravanshi

Reddy, S.K.K.; Narender, N.; Rohitha, C.N.; Kulkarni, S.I. Synth. Commun. 2008, 38, 3894. 15. Adimurthy, S.; Ramachandraiah, G.; Ghosh, P.K.; Bedekar, A.V. Tetrahedron Lett. 2003,. 44, 5099. 16. Sathiyapriya, R.; Karunakaran, R.J. Synth. Commun. 2006, 36, 1915. 17. Yamamoto, T.; Toyota, K.; Morita, N. Tetrahedron Lett.

Notes on the quantum tetrahedron

CERN Document Server

Coquereaux, Robert

2002-01-01

This is a set of notes describing several aspects of the space of paths on ADE Dynkin diagrams, with a particular attention paid to the graph E6. Many results originally due to A. Ocneanu are here described in a very elementary way (manipulation of square or rectangular matrices). We define the concept of essential matrices for a graph and describe their module properties with respect to right and left actions of fusion algebras. In the case of the graph E6, essential matrices build up a right module with respect to its fusion algebra but a left module with respect to the fusion algebra of A11. We present two original results: 1) We show how to recover the Ocneanu graph of quantum symmetries of the Dynkin diagram E6 from the natural multiplication defined in the tensor square of its fusion algebra (the tensor product should be taken over a particular subalgebra); this is the Cayley graph for the two generators of the twelve dimensional algebra (E6 \\otimes_A3 E6); here A3 and E6 refer to the commutative fusion...

Untitled

Indian Academy of Sciences (India)

Therefore it can accommodate extra ligands for complexation. There are two types of metal environments in 3. Four metal atoms form an inner tetrahedron and the other four cap the faces of this inner tetrahedron. Four Ti atoms around one C2 unit form a butterfly arrangement with the two inner titanium atoms as the hinge.

New series of 3 D lattice integrable models

International Nuclear Information System (INIS)

Mangazeev, V.V.; Sergeev, S.M.; Stroganov, Yu.G.

1993-01-01

In this paper we present a new series of 3-dimensional integrable lattice models with N colors. The weight functions of the models satisfy modified tetrahedron equations with N states and give a commuting family of two-layer transfer-matrices. The dependence on the spectral parameters corresponds to the static limit of the modified tetrahedron equations and weights are parameterized in terms of elliptic functions. The models contain two free parameters: elliptic modulus and additional parameter η. 12 refs

Asymptotics of Wigner 3nj-symbols with small and large angular momenta: an elementary method

International Nuclear Information System (INIS)

Bonzom, Valentin; Fleury, Pierre

2012-01-01

Yu and Littlejohn recently studied in (2011 Phys. Rev. A 83 052114 (arXiv:1104.1499)) some asymptotics of Wigner symbols with some small and large angular momenta. They found that in this regime the essential information is captured by the geometry of a tetrahedron, and gave new formulae for 9j-, 12j- and 15j-symbols. We present here an alternative derivation which leads to a simpler formula, based on the use of the Ponzano–Regge formula for the relevant tetrahedron. The approach is generalized to Wigner 3nj-symbols with some large and small angular momenta, where more than one tetrahedron are needed, leading to new asymptotics for Wigner 3nj-symbols. As an illustration, we present 15j-symbols with one, two and four small angular momenta, and give an alternative formula to Yu’s recent 15j-symbol with three small spins. (paper)

DEVELOPMENTS OF POLYHEDRA USING OBLIQUE COORDINATES

Directory of Open Access Journals (Sweden)

J. Akiyama

2007-04-01

Full Text Available This paper is an exposition of the results in the paper entitled "Convex Development of a Regular Tetrahedron" by J. Akiyama, et. al. [1]. We fill in the detail which have been omitted in the paper. We determine all convex developments of a regular tetrahedron V using a tiling generated by V and we arrive at conditions for convex polygons to be convex develpments of V . Moreover, we identify all convex polyhedra whose convex developments can be determined by the method used for V .

Three new d10 transition metal selenites containing PO4 tetrahedron: Cd7(HPO4)2(PO4)2(SeO3)2, Cd6(PO4)1.34(SeO3)4.66 and Zn3(HPO4)(SeO3)2(H2O)

Science.gov (United States)

Ma, Yun-Xiang; Gong, Ya-Ping; Hu, Chun-li; Mao, Jiang-Gao; Kong, Fang

2018-06-01

Three new d10 transition metal selenites containing PO4 tetrahedron, namely, Cd7(HPO4)2(PO4)2(SeO3)2 (1), Cd6(PO4)1.34(SeO3)4.66 (2) and Zn3(HPO4)(SeO3)2(H2O) (3), have been synthesized by hydrothermal reaction. They feature three different structural types. Compound 1 exhibits a novel 3D network composed of 3D cadmium selenite open framework with phosphate groups filled in the 1D helical tunnels. The structure of compound 2 displays a new 3D framework consisted of 2D cadmium oxide layers bridged by SeO3 and PO4 groups. Compound 3 is isostructural with the reported solids of Co3(SeO3)3-x(PO3OH)x(H2O) when x is equal to 1.0. Its structure could be viewed as a 3D zinc oxide open skeleton with SeO3 and HPO4 polyhedra attached on the wall of the tunnels. They represent the only examples in metal selenite phosphates in addition to the above cobalt compounds. Optical diffuse reflectance spectra revealed that these solids are insulators, which are consistent with the results of band structure computations based on DFT algorithm.

Crystallization of a self-assembled three-dimensional DNA nanostructure

International Nuclear Information System (INIS)

Rendek, Kimberly N.; Fromme, Raimund; Grotjohann, Ingo; Fromme, Petra

2013-01-01

In this work, the crystallization of a self-assembling three-dimensional B-DNA nanostructure is described. The powerful and specific molecular-recognition system present in the base-pairing of DNA allows for the design of a plethora of nanostructures. In this work, the crystallization of a self-assembling three-dimensional B-DNA nanostructure is described. The DNA nanostructure consists of six single-stranded oligonucleotides that hybridize to form a three-dimensional tetrahedron of 80 kDa in molecular mass and 20 bp on each edge. Crystals of the tetrahedron have been successfully produced and characterized. These crystals may form the basis for an X-ray structure of the tetrahedron in the future. Nucleotide crystallography poses many challenges, leading to the fact that only 1352 X-ray structures of nucleic acids have been solved compared with more than 80 000 protein structures. In this work, the crystallization optimization for three-dimensional tetrahedra is also described, with the eventual goal of producing nanocrystals to overcome the radiation-damage obstacle by the use of free-electron laser technology in the future

Binding of anions in triply interlocked coordination catenanes and dynamic allostery for dehalogenation reactions† †Electronic supplementary information (ESI) available: Characterization data and additional tables and figures. CCDC 1515722 and 1515723. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc04070a

Science.gov (United States)

Yang, Linlin; Jing, Xu; An, Bowen; Yang, Yang

2017-01-01

By synergistic combination of multicomponent self-assembly and template-directed approaches, triply interlocked metal organic catenanes that consist of two isolated chirally identical tetrahedrons were constructed and stabilized as thermodynamic minima. In the presence of suitable template anions, the structural conversion from the isolated tetrahedral conformers into locked catenanes occurred via the cleavage of an intrinsically reversible coordination bond in each of the tetrahedrons, followed by the reengineering and interlocking of two fragments with the regeneration of the broken coordination bonds. The presence of several kinds of individual pocket that were attributed to the triply interlocked patterns enabled the possibility of encapsulating different anions, allowing the dynamic allostery between the unlocked/locked conformers to promote the dehalogenation reaction of 3-bromo-cyclohexene efficiently, as with the use of dehalogenase enzymes. The interlocked structures could be unlocked into two individual tetrahedrons through removal of the well-matched anion templates. The stability and reversibility of the locked/unlocked structures were further confirmed by the catching/releasing process that accompanied emission switching, providing opportunities for the system to be a dynamic molecular logic system. PMID:29675152

Binding of anions in triply interlocked coordination catenanes and dynamic allostery for dehalogenation reactions.

Science.gov (United States)

Yang, Linlin; Jing, Xu; An, Bowen; He, Cheng; Yang, Yang; Duan, Chunying

2018-01-28

By synergistic combination of multicomponent self-assembly and template-directed approaches, triply interlocked metal organic catenanes that consist of two isolated chirally identical tetrahedrons were constructed and stabilized as thermodynamic minima. In the presence of suitable template anions, the structural conversion from the isolated tetrahedral conformers into locked catenanes occurred via the cleavage of an intrinsically reversible coordination bond in each of the tetrahedrons, followed by the reengineering and interlocking of two fragments with the regeneration of the broken coordination bonds. The presence of several kinds of individual pocket that were attributed to the triply interlocked patterns enabled the possibility of encapsulating different anions, allowing the dynamic allostery between the unlocked/locked conformers to promote the dehalogenation reaction of 3-bromo-cyclohexene efficiently, as with the use of dehalogenase enzymes. The interlocked structures could be unlocked into two individual tetrahedrons through removal of the well-matched anion templates. The stability and reversibility of the locked/unlocked structures were further confirmed by the catching/releasing process that accompanied emission switching, providing opportunities for the system to be a dynamic molecular logic system.

No acute tetrahedron is an 8-reptile

NARCIS (Netherlands)

Haverkort, H.J.

2018-01-01

An r-gentiling is a dissection of a shape into r ≥ 2 parts which are all similar to the original shape. An r-reptiling is an r-gentiling of which all parts are mutually congruent. The complete characterization of all reptile tetrahedra has been a long-standing open problem. This note concerns acute

Neutron diffraction study of TiCxNyHz

International Nuclear Information System (INIS)

Khidirov, I.

1996-01-01

Neutron diffraction study of titanium carbonitridohydride is carried out. It is shown that TiC x N y H z may have a disordered, on ordered and a partially ordered structure depending on the composition. Both in the ordered and in the disordered structure the atoms of carbon and nitrogen are located in octahedron interstices only. Under (C+N)/Ti > 0.70 the atoms of hydrogen are located in octahedron interstices only. Under (C+N)/Ti < 0.50 and under high temperatures the atoms of hydrogen occupy both octahedron and tetrahedron interstices; under low temperatures the transition of some hydrogen atoms from tetrahedron into octahedron interstices is observed. 15 refs.; 1 fig.; 1 tab

Luminescent properties of complexly substituted oxides Ме2Ln8 (XO46O2 (Me=Sr, Ca; Ln=La, Gd, Eu; X= Si, P

Directory of Open Access Journals (Sweden)

A. A. Vasin

2014-11-01

Full Text Available In the current work it is established that the maximum intensity of a luminescence of crystalline phosphors with structure silicate-apatite of general formulae: Ca2Eu8Si6(1-xP6xO26, Sr2Gd7.2Eu0.8Si6(1-xP6xO26 and Ca2La8(1-xEu8xSi6O26 is reached at concentration of europium equal 0,15. The maximum intensity of a luminescence of these substances, at replacement in an anion sublattice of tetrahedrons [SiO4]4- on tetrahedrons [PO4]3- takes place at concentration of phosphorus 0,05.

Multi-region unstructured volume segmentation using tetrahedron filling

Energy Technology Data Exchange (ETDEWEB)

Willliams, Sean Jamerson [Los Alamos National Laboratory; Dillard, Scott E [Los Alamos National Laboratory; Thoma, Dan J [MDI, INSTITUTES; Hlawitschka, Mario [UC DAVIS; Hamann, Bernd [UC DAVIS

2010-01-01

Segmentation is one of the most common operations in image processing, and while there are several solutions already present in the literature, they each have their own benefits and drawbacks that make them well-suited for some types of data and not for others. We focus on the problem of breaking an image into multiple regions in a single segmentation pass, while supporting both voxel and scattered point data. To solve this problem, we begin with a set of potential boundary points and use a Delaunay triangulation to complete the boundaries. We use heuristic- and interaction-driven Voronoi clustering to find reasonable groupings of tetrahedra. Apart from the computation of the Delaunay triangulation, our algorithm has linear time complexity with respect to the number of tetrahedra.

Concluding Remarks%序

Institute of Scientific and Technical Information of China (English)

Sunney I.Chan

1997-01-01

@@ Thank you for your kind introduction, T.L. I am, of course, honored to have been the Honorary Chairman of ISOC 4, and I thank the Organizing Committee for bestowing this honoron me. As you know, I am not a card- carrying organic chemist, and one might wonder what a physical biochemist could really contribute to this Symposium. But, as Professor Chi - Huey Wong noted during his keynote address, I am over the hill in my own field. Perhaps, my colleagues at CUHK think I might be able to begin a second career as an organic chemist. Lest you question the seriousness of this suggestion, my students and I have recently published in the Journal of Organic Chemistry and Tetrahedron Letters!

Multicomponent synthesis of imidazo [1,2-a] pyridines using catalytic zinc chloride

CSIR Research Space (South Africa)

Rousseau, AL

2007-06-01

Full Text Available HN R1 R2 Scheme 1. Tetrahedron Letters 48 (2007) 4079–4082 chloride,12 acetic acid,10a perchloric acid,10e or Montmo- rillonite clay K1013 to catalyze the reaction. The use of solid supports with a range of acid catalysts in the 3CC reaction... tempera- ture (for reactions catalyzed by scandium triflate, acetic acid, toluenesulfonic acid or perchloric acid) or using N X N 1 X=CH 2 X=N N N 3 R1=R2=Cl, R3=R4=C3H7 4 R1=R2=R3=R4=CH3 R1 R2 O N R3 R4 N N SO2Me antagonists.9 Drug...

Jahn-Teller effect in vanadium, niobium and tantalum tetrafluoride molecules: ab initio study by the CASSCF method

International Nuclear Information System (INIS)

Solomonik, V.G.; Pogrebnaya, T.P.

2001-01-01

The basic and the first exciting electronic state of the VF 4 , NbF 4 and TaF 4 molecules were studied by the self-consistent field multifunctional method in the approximation of active orbitals full space. The symmetry of these states is defined as 2 E and 2 T 2 at tetrahedron configuration of the nuclei. The energies of electron excitation 2 E → 2 T 2 comprise 11610 (VF 4 ), 13450 (NbF 4 ) and 12560 cm -1 (TaF 4 ). In line to Jahn-Teller theorem the calculations evidenced instability of tetrahedron configuration of the molecules in the orbital-singular electronic states 2 E and 2 T 2 . The properties of the systems of the molecule potential energies were found, in keeping with deformation of tetrahedron configuration of the nuclei along the oscillation coordinates of the e symmetry, active in the Jahn-Teller effect. Equilibrium geometric configuration of the molecules with the lowest energy has a symmetry D 2d as in the basic ( 2 A 1 ), so in the first excited electronic state. The energy of the adiabatic electronic excitation 2 A 1 → 2 B 2 is equal to 8440 (VF 4 ), 9050 (NbF 4 ) and 11920 cm -1 (TaF 4 ). Deviations of molecules equilibrium geometry on the structure of the normal tetrahedron and the energy of Jahn-Teller stabilization E JT grow essentially in the series of the molecules VF 4 → NbF 4 → TaF 4 : E JT =E(T d , 2 E)Epy - E(D 2d , 2 A 1 )=412, 1856, 5970 cm -1 ; E JT =E(T d , 2 T 2 ) - E(D 2d , 2 B 2 )=3584, 6259, 6611 cm -1 . The quadratic force constants, the frequencies of normal oscillations and the intensities in the IR spectra of the VF 4 , NbF 4 and TaF 4 molecules in the basic state were calculated [ru

Geometry of the Gene Expression Space of Individual Cells.

Directory of Open Access Journals (Sweden)

Yael Korem

2015-07-01

Full Text Available There is a revolution in the ability to analyze gene expression of single cells in a tissue. To understand this data we must comprehend how cells are distributed in a high-dimensional gene expression space. One open question is whether cell types form discrete clusters or whether gene expression forms a continuum of states. If such a continuum exists, what is its geometry? Recent theory on evolutionary trade-offs suggests that cells that need to perform multiple tasks are arranged in a polygon or polyhedron (line, triangle, tetrahedron and so on, generally called polytopes in gene expression space, whose vertices are the expression profiles optimal for each task. Here, we analyze single-cell data from human and mouse tissues profiled using a variety of single-cell technologies. We fit the data to shapes with different numbers of vertices, compute their statistical significance, and infer their tasks. We find cases in which single cells fill out a continuum of expression states within a polyhedron. This occurs in intestinal progenitor cells, which fill out a tetrahedron in gene expression space. The four vertices of this tetrahedron are each enriched with genes for a specific task related to stemness and early differentiation. A polyhedral continuum of states is also found in spleen dendritic cells, known to perform multiple immune tasks: cells fill out a tetrahedron whose vertices correspond to key tasks related to maturation, pathogen sensing and communication with lymphocytes. A mixture of continuum-like distributions and discrete clusters is found in other cell types, including bone marrow and differentiated intestinal crypt cells. This approach can be used to understand the geometry and biological tasks of a wide range of single-cell datasets. The present results suggest that the concept of cell type may be expanded. In addition to discreet clusters in gene-expression space, we suggest a new possibility: a continuum of states within a

Effect of lead salts on phase, morphologies and photoluminescence of nanocrystalline PbMoO4 and PbWO4 synthesized by microwave radiation

Directory of Open Access Journals (Sweden)

Phuruangrat Anukorn

2016-09-01

Full Text Available PbMoO4 and PbWO4 were successfully synthesized by microwave radiation using different lead salts (acetate, chloride, nitrate and sulfate and Na2MO4 (M = Mo, W in propylene glycol. The products were characterized by X-ray diffraction (XRD, scanning and transmission electron microscopy (SEM, TEM, Fourier transform infrared (FT-IR, Raman spectroscopy and photoluminescence (PL spectroscopy. In this research, morphologies, crystallization and photoluminescence of the products were influenced by the kinetics of anions, including the detection of M–O (M = Mo, W stretching modes in the (MO42− tetrahedrons. Photoluminescence of PbMoO4 synthesized from Pb(NO32 and of PbWO4 synthesized from PbCl2 showed the strongest blue emission due to the electronic diffusion in tetrahedrons at room temperature.

Bernstein's paradox of entangled quantum states

International Nuclear Information System (INIS)

Belinsky, A V; Chirkin, A S

2013-01-01

Bernstein's classical paradox of a regular colored-faced tetrahedron, while designed to illustrate the subtleties of probability theory, is strongly flawed in being asymmetric. Faces of tetrahedron are nonequivalent: three of them are single-colored, and one is many-colored. Therefore, even prior to formal calculations, a strong suspicion as to the independence of the color resulting statistics arises. Not so with entangled quantum states. In the schematic solutions proposed, while photon detection channels are completely symmetric and equivalent, the events that occur in them turn out to be statistically dependent, making the Bernstein paradox even more impressive due to the unusual behavior of quantum particles not obeying classical laws. As an illustrative example of the probability paradox, Greenberger–Horne–Zeilinger multiqubit states are considered. (methodological notes)

IR spectra and structure of glasses in the BaO-WO3-P2O5 system

International Nuclear Information System (INIS)

Miroshnichenko, O.Ya.; Mombelli, V.V.

1979-01-01

Studied are IR absorption spectra and determined are the main structural characteristics of tungstophosphate glasses of the BaO-WO 3 -P 2 O 5 system in all the area of glass formation. It is shown that the main structural components of their anion network are phosphate chains consisting of PO 4 tetrahedrons and tungstate chains consisting of WO 4 tetrahedrons and of WO 6 octahedrons. These chains are connected by P-O-W bridges into three-dimentional tungstophosphate network, where the ratio of phosphate and tungstate structural units and their polymerization degree change without limits depending on the glass composition. Analysis of concentration frequency dependence and spectral band intensity permit to clarify the effect of each component on the glass structure in all the area of glass formation of the triple system

Meltability in system of K2TaF7-NaF-NaCl-KCl

International Nuclear Information System (INIS)

Kartsev, V.E.; Kovalev, F.V.; Korshunov, B.G.

1975-01-01

Thermographic and visual-polythermal techniques were used to study the meltability in K 2 TaF 7 -NaF-NaCl-KCl system. The tetrahedron-forming sections NaF-NaCl-K 2 TaF 7 xKCl and NaF-K 2 TaF 7 xKCl-2K 2 TaF 7 xNaCl divide the concentration tetrahedron into three particular tetrahedra: NaF-K 2 TaF 7 xKCl-2K 2 TaF 7 xNaCl-K 2 TaF 7 , NaF-NaCl-K 2 TaF 7 xKCl-2K 2 TaF 7 xaCl, and NaF-NaCl-KCl-K 2 TaF 7 xKCl. Non-variant equilibrium points in all of the particular four-component systems have been determined

Geometric structure of thin SiO xN y films on Si(100)

Science.gov (United States)

Behrens, K.-M.; Klinkenberg, E.-D.; Finster, J.; Meiwes-Broer, K.-H.

1998-05-01

Thin films of amorphous stoichometric SiO xN y are deposited on radiation-heated Si(100) by rapid thermal low-pressure chemical vapour deposition. We studied the whole range of possible compositions. In order to determine the geometric structure, we used EXAFS and photoelectron spectroscopy. Tetrahedrons constitute the short-range units with a central Si atom connected to N and O. The distribution of the possible tetrahedrons can be described by a mixture of the Random Bonding Model and the Random Mixture Model. For low oxygen contents x/( x+ y)≤0.3, the geometric structure of the film is almost the structure of a-Si 3N 4, with the oxygen preferably on top of Si-N 3 triangles. Higher oxygen contents induce changes in the bond lengths, bond angles and coordination numbers.

Bronsted acid-functionalized choline chloride-butane sultone for the ...

Indian Academy of Sciences (India)

M P PADMA PRIYA

2018-03-21

Mar 21, 2018 ... Choline chloride and 1,4-butane sultone were combined to obtain a sulphonic acid-functionalized ..... Knifton J F and Sanderson J R 1990 Method for produc- ... alkenes via the Knoevenagel condensation Tetrahedron. Lett.

A symmetry-controlled and face-driven approach for the assembly of cerium-based molecular polyhedra.

Science.gov (United States)

Liu, Yang; Lin, Zhihua; He, Cheng; Zhao, Liang; Duan, Chunying

2010-12-14

A well-defined Ce-based molecular tetrahedron and a cube-like architecture were achieved via self-assembly by incorporating NOO tridentate chelators into the rationally designed ligands with C(3) or C(2v) symmetries, respectively.

Recurring polyhedral motifs in the amorphous indium gallium zinc oxide network

Energy Technology Data Exchange (ETDEWEB)

Divya; Deepak [Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur (India); National Center for Flexible Electronics, Indian Institute of Technology, Kanpur (India); Prasad, Rajendra [Department of Physics, Indian Institute of Technology, Kanpur (India)

2017-02-15

The coordination polyhedra around the cations are the building blocks of ionic solids. For amorphous InGaZn oxide (a-IGZO), these coordination polyhedra are identified to investigate properties that depend on short range interactions. Therefore, in this first principles based study, a large number (10) of samples of a-IGZO were prepared by ab initio melt-and-quench molecular dynamics, so that several distinct samples of the amorphous landscape are obtained corresponding to local minima in energy. Based on a method of comparing bond angles between metal and oxygen atoms, the identified polyhedra were matched to the polyhedral motifs present in the related crystalline systems, such as, InGaZnO{sub 4}, In{sub 2}O{sub 3}, Ga{sub 2}O{sub 3}, and ZnO. Consequently, we find, the a-IGZO primarily consists of the following polyhedra: a tetrahedron from space group 199 and an octahedron from space group 206 of In{sub 2}O{sub 3}; a tetrahedron from space group 12 and an octahedron from space group 167 of Ga{sub 2}O{sub 3}; a tetrahedron from space group 186 of ZnO; zinc and gallium trigonal bipyramids from c-IGZO; and one zinc fourfold, one zinc fivefold, and one indium fivefold coordination polyhedra that occur only in the amorphous phase. Thus, we were able to reduce the description of structure from 360 to 10 groups of polyhedra. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Recurring polyhedral motifs in the amorphous indium gallium zinc oxide network

International Nuclear Information System (INIS)

Divya; Deepak; Prasad, Rajendra

2017-01-01

The coordination polyhedra around the cations are the building blocks of ionic solids. For amorphous InGaZn oxide (a-IGZO), these coordination polyhedra are identified to investigate properties that depend on short range interactions. Therefore, in this first principles based study, a large number (10) of samples of a-IGZO were prepared by ab initio melt-and-quench molecular dynamics, so that several distinct samples of the amorphous landscape are obtained corresponding to local minima in energy. Based on a method of comparing bond angles between metal and oxygen atoms, the identified polyhedra were matched to the polyhedral motifs present in the related crystalline systems, such as, InGaZnO_4, In_2O_3, Ga_2O_3, and ZnO. Consequently, we find, the a-IGZO primarily consists of the following polyhedra: a tetrahedron from space group 199 and an octahedron from space group 206 of In_2O_3; a tetrahedron from space group 12 and an octahedron from space group 167 of Ga_2O_3; a tetrahedron from space group 186 of ZnO; zinc and gallium trigonal bipyramids from c-IGZO; and one zinc fourfold, one zinc fivefold, and one indium fivefold coordination polyhedra that occur only in the amorphous phase. Thus, we were able to reduce the description of structure from 360 to 10 groups of polyhedra. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Schiff base transition metal complexes for Suzuki–Miyaura cross ...

Indian Academy of Sciences (India)

RASHEEDA M ANSARI

2017-08-19

Aug 19, 2017 ... simple, fast, cheap and more efficient methodologies for different .... then refluxed for 3 h followed by filtration of obtained product, washing with diethyl ..... C–C cross-coupling of aryl iodides with terminal alkynes. Tetrahedron ...

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

Coherent states, 6j symbols and properties of the next to leading order asymptotic expansions

Energy Technology Data Exchange (ETDEWEB)

Kamiński, Wojciech, E-mail: wkaminsk@fuw.edu.pl [Wydział Fizyki, Uniwersytet Warszawski, Hoża 69, 00-681, Warsaw (Poland); Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada); Max Planck Institute for Gravitational Physics, Am Mühlenberg 1, D-14476 Potsdam (Germany); Steinhaus, Sebastian, E-mail: steinhaus.sebastian@gmail.com [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada); Max Planck Institute for Gravitational Physics, Am Mühlenberg 1, D-14476 Potsdam (Germany)

2013-12-15

We present the first complete derivation of the well-known asymptotic expansion of the SU(2) 6j symbol using a coherent state approach, in particular we succeed in computing the determinant of the Hessian matrix. To do so, we smear the coherent states and perform a partial stationary point analysis with respect to the smearing parameters. This allows us to transform the variables from group elements to dihedral angles of a tetrahedron resulting in an effective action, which coincides with the action of first order Regge calculus associated to a tetrahedron. To perform the remaining stationary point analysis, we compute its Hessian matrix and obtain the correct measure factor. Furthermore, we expand the discussion of the asymptotic formula to next to leading order terms, prove some of their properties and derive a recursion relation for the full 6j symbol.

Coherent states, 6j symbols and properties of the next to leading order asymptotic expansions

International Nuclear Information System (INIS)

Kamiński, Wojciech; Steinhaus, Sebastian

2013-01-01

We present the first complete derivation of the well-known asymptotic expansion of the SU(2) 6j symbol using a coherent state approach, in particular we succeed in computing the determinant of the Hessian matrix. To do so, we smear the coherent states and perform a partial stationary point analysis with respect to the smearing parameters. This allows us to transform the variables from group elements to dihedral angles of a tetrahedron resulting in an effective action, which coincides with the action of first order Regge calculus associated to a tetrahedron. To perform the remaining stationary point analysis, we compute its Hessian matrix and obtain the correct measure factor. Furthermore, we expand the discussion of the asymptotic formula to next to leading order terms, prove some of their properties and derive a recursion relation for the full 6j symbol

Coherent states, 6j symbols and properties of the next to leading order asymptotic expansions

Science.gov (United States)

Kamiński, Wojciech; Steinhaus, Sebastian

2013-12-01

We present the first complete derivation of the well-known asymptotic expansion of the SU(2) 6j symbol using a coherent state approach, in particular we succeed in computing the determinant of the Hessian matrix. To do so, we smear the coherent states and perform a partial stationary point analysis with respect to the smearing parameters. This allows us to transform the variables from group elements to dihedral angles of a tetrahedron resulting in an effective action, which coincides with the action of first order Regge calculus associated to a tetrahedron. To perform the remaining stationary point analysis, we compute its Hessian matrix and obtain the correct measure factor. Furthermore, we expand the discussion of the asymptotic formula to next to leading order terms, prove some of their properties and derive a recursion relation for the full 6j symbol.

The Influence of Particle Shape and Size on the Activity of Platinum Nanoparticles for Oxygen Reduction Reaction: A Density Functional Theory Study

DEFF Research Database (Denmark)

Tripkovic, Vladimir; Cerri, Isotta; Bligaard, Thomas

2014-01-01

We present first principle investigation of the influence of platinum nanoparticle shape and size on the oxygen reduction reaction activity. We compare the activities of nanoparticles with specific shapes (tetrahedron, octahedron, cube and truncated octahedron) with that of equilibrium particle s...

Screening marine organisms for antimicrobial activity against clinical pathogens

Digital Repository Service at National Institute of Oceanography (India)

PrabhaDevi; Wahidullah, S.; Tonima, K.; DeSouza, L.

, 37 (1982) 179. 15 Gonzalez, A. G., Estrada, D. M., Martin, J. D., Martin, S. W., Perez, C. & Perez, R., New antimicrobial diterpenes from the sponge Spongia officinalis, Tetrahedron, (1984) 4109. 16 Rinehart, K.L., Shaw, Jr P.D., Shield, L...

Optimal Weighting of Multi-Spacecraft Data to Estimate Gradients of Physical Fields

Science.gov (United States)

Chanteur, G. M.; Le Contel, O.; Sahraoui, F.; Retino, A.; Mirioni, L.

2016-12-01

Multi-spacecraft missions like the ESA mission CLUSTER and the NASA mission MMS are essential to improve our understanding of physical processes in space plasmas. Several methods were designed in the 90's during the preparation phase of the CLUSTER mission to estimate gradients of physical fields from simultaneous multi-points measurements [1, 2]. Both CLUSTER and MMS involve four spacecraft with identical full scientific payloads including various sensors of electromagnetic fields and different type of particle detectors. In the standard methods described in [1, 2], which are presently in use, data from the four spacecraft have identical weights and the estimated gradients are most reliable when the tetrahedron formed by the four spacecraft is regular. There are three types of errors affecting the estimated gradients (see chapter 14 in [1]) : i) truncature errors are due to local non-linearity of spatial variations, ii) physical errors are due to instruments, and iii) geometrical errors are due to uncertainties on the positions of the spacecraft. An assessment of truncature errors for a given observation requires a theoretical model of the measured field. Instrumental errors can easily be taken into account for a given geometry of the cluster but are usually less than the geometrical errors which diverge quite fast when the tetrahedron flattens, a circumstance occurring twice per orbit of the cluster. Hence reliable gradients can be estimated only on part of the orbit. Reciprocal vectors of the tetrahedron were presented in chapter 4 of [1], they have the advantage over other methods to treat the four spacecraft symmetrically and to allow a theoretical analysis of the errors (see chapters 4 of [1] and 4 of [2]). We will present Generalized Reciprocal Vectors for weighted data and an optimization procedure to improve the reliability of the estimated gradients when the tetrahedron is not regular. A brief example using CLUSTER or MMS data will be given. This approach

Untitled

Indian Academy of Sciences (India)

. Venkatachalapathi Y V and Balaram P 1981 Biochemistry 20 1 137. Vijayakumar E. K S and Balaram P 1983a Tetrahedron 392725. Vijayakumar E K S and Balaram P 1983b Biopolymers 22 2133. Vijayakumar E K S and Balaran P 1984 ...

Two-dimensional silica: Structural, mechanical properties, and strain-induced band gap tuning

Energy Technology Data Exchange (ETDEWEB)

Gao, Enlai; Xie, Bo [Applied Mechanics Laboratory, Department of Engineering Mechanics, and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084 (China); Xu, Zhiping, E-mail: xuzp@tsinghua.edu.cn [Applied Mechanics Laboratory, Department of Engineering Mechanics, and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084 (China); State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

2016-01-07

Two-dimensional silica is of rising interests not only for its practical applications as insulating layers in nanoelectronics, but also as a model material to understand crystals and glasses. In this study, we examine structural and electronic properties of hexagonal and haeckelite phases of silica bilayers by performing first-principles calculations. We find that the corner-sharing SiO{sub 4} tetrahedrons in these two phases are locally similar. The robustness and resilience of these tetrahedrons under mechanical perturbation allow effective strain engineering of the electronic structures with band gaps covering a very wide range, from of that for insulators, to wide-, and even narrow-gap semiconductors. These findings suggest that the flexible 2D silica holds great promises in developing nanoelectronic devices with strain-tunable performance, and lay the ground for the understanding of crystalline and vitreous phases in 2D, where bilayer silica provides an ideal test-bed.

Stability and selectivity of alkaline proteases in hydrophilic solvents

DEFF Research Database (Denmark)

Pedersen, Lars Haastrup; Ritthitham, Sinthuwat; Pleissner, Daniel

2008-01-01

, A. Bouchu, G. Descotes, Y. Queneau, Tetrahedron: Lett. 2000, 41, 3597. [7]           Q. Wu, N. Wang, Y.M. Xiao, D.S. Lu, X.F. Lin, Carbohydr. Res., 2004, 339, 2059. [8]           H.G. Park, H.N. Chang, Biotechnol. Lett. 2000, 22, 39 [9]           S. Riva, M. Nonini, G. Ottolina, B. Danieli......, Carbohydr. Res., 1998, 314, 259. [10]         N.R. Pedersen, R. Wimmer, R. Matthiesen, L.H. Pedersen, A. Gessesse, Tetrahedron: Asymmetry 2003, 14, 667. [11]         L. H. Pedersen, S. Ritthitham and M. Kristensen (2008) in Modern Biocatalysis Eds W. D. Fessner and T. Anthonsen, Wiley-VCH in press...

Modeling amorphization of tetrahedral structures under local approaches

International Nuclear Information System (INIS)

Jesurum, C.E.; Pulim, V.; Berger, B.; Hobbs, L.W.

1997-01-01

Many crystalline ceramics can be topologically disordered (amorphized) by disordering radiation events involving high-energy collision cascades or (in some cases) successive single-atom displacements. The authors are interested in both the potential for disorder and the possible aperiodic structures adopted following the disordering event. The potential for disordering is related to connectivity, and among those structures of interest are tetrahedral networks (such as SiO 2 , SiC and Si 3 N 4 ) comprising corner-shared tetrahedral units whose connectivities are easily evaluated. In order to study the response of these networks to radiation, the authors have chosen to model their assembly according to the (simple) local rules that each corner obeys in connecting to another tetrahedron; in this way they easily erect large computer models of any crystalline polymorphic form. Amorphous structures can be similarly grown by application of altered rules. They have adopted a simple model of irradiation in which all bonds in the neighborhood of a designated tetrahedron are destroyed, and they reform the bonds in this region according to a set of (possibly different) local rules appropriate to the environmental conditions. When a tetrahedron approaches the boundary of this neighborhood, it undergoes an optimization step in which a spring is inserted between two corners of compatible tetrahedra when they are within a certain distance of one another; component forces are then applied that act to minimize the distance between these corners and minimize the deviation from the rules. The resulting structure is then analyzed for the complete adjacency matrix, irreducible ring statistics, and bond angle distributions

Calculation of Spectra of Solids:

DEFF Research Database (Denmark)

Lindgård, Per-Anker

1975-01-01

The Gilat-Raubenheimer method simplified to tetrahedron division is used to calculate the real and imaginary part of the dynamical response function for electrons. A frequency expansion for the real part is discussed. The Lindhard function is calculated as a test for numerical accuracy...

Passivity Based Nonlinear Attitude Control of the Rømer Satellite

DEFF Research Database (Denmark)

Quottrup, Michael Melholt; Krogh-Sørensen, J.; Wisniewski, Rafal

2001-01-01

This paper suggests nonlinear attitude control of the Danish satellite Rømer. This satellite will be designed to fulfil two scientific objectives: The observation of stellar oscillations and the detection and localisation of gamma-ray bursts. The satellite will be equipped with a tetrahedron...

Synthesis, Anticonvulsant Activity and In silco Studies of Schiff ...

African Journals Online (AJOL)

Georgette M, Castanedo, Daniel PS. Synthesis of tetrasubstituted thiophenes on solid support using the Gewald reaction.Tetrahedron lett 2001; 42: 7181-7184. 11. Pushyamitra M, Hardesh K, Maurya, Brijesh K, Vishnu. K, Tandon, Vishnu JR. synthesis of thiophenes and pyranone fused thiophenes by base induced inter.

Theoretical Analyses of Superconductivity in Iron Based ...

African Journals Online (AJOL)

fire7-

using double time temperature dependent Green's function formalism and a suitable decoupling approximation technique, we ... phenomenon of zero electric resistivity in mercury was soon followed by the observation of the superconducting state in ... The iron, Fe2+ forms tetrahedron within the layers. This means that, iron-.

Součet úhlů ve čtyřstěnu

Czech Academy of Sciences Publication Activity Database

Brandts, J.; Cihangir, A.; Křížek, Michal

2015-01-01

Roč. 60, č. 2 (2015), s. 113-122 ISSN 0032-2423 R&D Projects: GA ČR GA14-02067S Institutional support: RVO:67985840 Keywords : dihedral angle * solid angle * nonobtuse tetrahedron * optimal bounds Subject RIV: BA - General Mathematics http://hdl.handle.net/10338.dmlcz/144405

Computer simulation of void formation in residual gas atom free metals by dual beam irradiation experiments

International Nuclear Information System (INIS)

Shimomura, Y.; Nishiguchi, R.; La Rubia, T.D. de; Guinan, M.W.

1992-01-01

In our recent experiments (1), we found that voids nucleate at vacancy clusters which trap gas atoms such as hydrogen and helium in ion- and neutron-irradiated copper. A molecular dynamics computer simulation, which implements an empirical embedded atom method to calculate forces that act on atoms in metals, suggests that a void nucleation occurs in pure copper at six and seven vacancy clusters. The structure of six and seven vacancy clusters in copper fluctuates between a stacking fault tetrahedron and a void. When a hydrogen is trapped at voids of six and seven vacancy, a void can keep their structure for appreciably long time; that is, the void do not relax to a stacking fault tetrahedron and grows to a large void. In order to explore the detailed atomics of void formation, it is emphasized that dual-beam irradiation experiments that utilize beams of gas atoms and self-ions should be carried out with residual gas atom free metal specimens. (author)

Conforming to interface structured adaptive mesh refinement: 3D algorithm and implementation

Science.gov (United States)

Nagarajan, Anand; Soghrati, Soheil

2018-03-01

A new non-iterative mesh generation algorithm named conforming to interface structured adaptive mesh refinement (CISAMR) is introduced for creating 3D finite element models of problems with complex geometries. CISAMR transforms a structured mesh composed of tetrahedral elements into a conforming mesh with low element aspect ratios. The construction of the mesh begins with the structured adaptive mesh refinement of elements in the vicinity of material interfaces. An r-adaptivity algorithm is then employed to relocate selected nodes of nonconforming elements, followed by face-swapping a small fraction of them to eliminate tetrahedrons with high aspect ratios. The final conforming mesh is constructed by sub-tetrahedralizing remaining nonconforming elements, as well as tetrahedrons with hanging nodes. In addition to studying the convergence and analyzing element-wise errors in meshes generated using CISAMR, several example problems are presented to show the ability of this method for modeling 3D problems with intricate morphologies.

In vitro and in silico characterization of open-cell structures of trabecular bone.

Science.gov (United States)

Ramos-Infante, S J; Pérez, M A

2017-11-01

This work aimed to perform a detailed in vitro and in silico characterization of open-cell structures, which resemble trabecular bone, to elucidate osteoporosis failure mechanisms. Experimental and image-based computational methods were used to estimate Young's modulus and porosities of different open-cell structures (Sawbones; Malmö, Sweden). Three different open-cell structures with different porosities were characterized. Additionally, some open-cell structures were scanned using a microcomputed tomography system (μCT) to non-destructively predict specimen Young's modulus of the structures by developing voxel-based and tetrahedral finite element (FE) models. A 3D reconstruction and FE analyses were used. The experimental and computational results with different element types (linear and quadratic tetrahedrons and voxel-based meshes) were compared with Sawbones data (Sawbones; Malmö, Sweden) revealing important differences in Young's modulus and porosities. The specimens with high and low volume fractions were best represented by linear and quadratic tetrahedrons, respectively. These results could be used to develop new osteoporosis-prevention strategies.

Blocking Mechanism Study of Self-Compacting Concrete Based on Discrete Element Method

Science.gov (United States)

Zhang, Xuan; Li, Zhida; Zhang, Zhihua

2017-11-01

In order to study the influence factors of blocking mechanism of Self-Compaction Concrete (SCC), Roussel’s granular blocking model was verified and extended by establishing the discrete element model of SCC. The influence of different parameters on the filling capacity and blocking mechanism of SCC were also investigated. The results showed that: it was feasible to simulate the blocking mechanism of SCC by using Discrete Element Method (DEM). The passing ability of pebble aggregate was superior to the gravel aggregate and the passing ability of hexahedron particles was bigger than tetrahedron particles, while the tetrahedron particle simulation results were closer to the actual situation. The flow of SCC as another significant factor affected the passing ability that with the flow increased, the passing ability increased. The correction coefficient λ of the steel arrangement (channel section shape) and flow rate γ in the block model were introduced that the value of λ was 0.90-0.95 and the maximum casting rate was 7.8 L/min.

Molecular dynamics simulation of nano-indentation of (111) cubic boron nitride with optimized Tersoff potential

International Nuclear Information System (INIS)

Zhao, Yinbo; Peng, Xianghe; Fu, Tao; Huang, Cheng; Feng, Chao; Yin, Deqiang; Wang, Zhongchang

2016-01-01

Highlights: • We optimize Tersoff potential to simulate the cBN better under nanoidentation. • Dislocations slip more easily along and directions on the {111} plane. • Shuffle-set dislocation slip along direction on {111} plane first. • A tetrahedron structure is found in the initial stage of the indentation. - Abstract: We conduct molecular dynamics simulation of nanoindentation on (111) surface of cubic boron nitride and find that shuffle-set dislocations slip along direction on {111} plane at the initial stage of the indentation. The shuffle-set dislocations are then found to meet together, forming surfaces of a tetrahedron. We also find that the surfaces are stacking-fault zones, which intersect with each other, forming edges of stair-rod dislocations along direction. Moreover, we also calculate the generalized stacking fault (GSF) energies along various gliding directions on several planes and find that the GSF energies of the {111} and {111} systems are relatively smaller, indicating that dislocations slip more easily along and directions on the {111} plane.

Energy-Based Tetrahedron Sensor for High-Temperature, High-Pressure Environments

Science.gov (United States)

Gee, Kent L.; Sommerfeldt, Scott D.; Blotter, Jonathan D.

2012-01-01

An acoustic energy-based probe has been developed that incorporates multiple acoustic sensing elements in order to obtain the acoustic pressure and three-dimensional acoustic particle velocity. With these quantities, the user can obtain various energy-based quantities, including acoustic energy density, acoustic intensity, and acoustic impedance. In this specific development, the probe has been designed to operate in an environment characterized by high temperatures and high pressures as is found in the close vicinity of rocket plumes. Given these capabilities, the probe is designed to be used to investigate the acoustic conditions within the plume of a rocket engine or jet engine to facilitate greater understanding of the noise generation mechanisms in those plumes. The probe features sensors mounted inside a solid sphere. The associated electronics for the probe are contained within the sphere and the associated handle for the probe. More importantly, the design of the probe has desirable properties that reduce the bias errors associated with determining the acoustic pressure and velocity using finite sum and difference techniques. The diameter of the probe dictates the lower and upper operating frequencies for the probe, where accurate measurements can be acquired. The current probe design implements a sphere diameter of 1 in. (2.5 cm), which limits the upper operating frequency to about 4.5 kHz. The sensors are operational up to much higher frequencies, and could be used to acquire pressure data at higher frequencies, but the energy-based measurements are limited to that upper frequency. Larger or smaller spherical probes could be designed to go to lower or higher frequency range

Planet map generation by tetrahedral subdivision

DEFF Research Database (Denmark)

Mogensen, Torben Ægidius

2010-01-01

We present a method for generating pseudo-random, zoomable planet maps for games and art.  The method is based on spatial subdivision using tetrahedrons.  This ensures planet maps without discontinuities caused by mapping a flat map onto a sphere. We compare the method to other map...

Restricting rotation of triple bond through π-stacking interactions in ...

Indian Academy of Sciences (India)

SANKARARAMAN

For various X and Y activation barrier range from 42-79 kJ/mole. Vögtle, F., et.al., Angew. Chem. Int. Ed., 1979, 18, 159. Toyota, S., et.al., Bull. Chem. Soc. Jpn, 2000, 73, 205 and 2591. Toyota, S., et.al., Tetrahedron Lett., 2001, 57, 3521.

SUBSTITUED COUMARINS Hülya Çelik Onar1*and Begüm

African Journals Online (AJOL)

the most widely applied for the synthesis of coumarins due to simple reaction conditions and good yields. Nowadays ... oxalic acid (10 mol%) was heated to 80 oC till completion of the reaction (monitored using. TLC). Then, the .... coumarin anticoagulants via hetero-Diels–Alder cycloaddition Tetrahedron Asymm. 2001,.

Novel synthesis of a strained para-cyclophane derivative

Institute of Scientific and Technical Information of China (English)

Zhi Hao Shi; Yun Yang Wei

2007-01-01

A [P. Rajakumar, A.M.A. Rasheed, Tetrahedron 61(22) (2005) 5351] para-cyclophane derivative was synthesized via intramolecular esterification of a dipeptide surrogate containing asparagine to form tetrahydropyrimidinone ring. The structures of the product and intermediates were characterized by 1H NMR, 13C NMR and mass spectrum.

Aerobic oxidation of alcohols in visible light on Pd-grafted Ti ...

Science.gov (United States)

The titanium cluster with the reduced band gap has been synthesized having the palladium nanoparticles over the surface, which not only binds to the atmospheric oxygen but also catalyzes the oxidation of alcohols under visible light. Prepared as an invited article for submission to the Elsevier journal, Tetrahedron.

APPLICATION OF QUATERNIONS FOR REFLECTOR PARAMETER

Directory of Open Access Journals (Sweden)

I. A. Konyakhin

2016-09-01

Full Text Available Subject of Research. The paper deals with application of quaternions for optimization of reflector parameters at autocollimation measurements in comparison with a matrix method. Computer-based results on the quaternionic models are presented that have given the possibility to determine conditions of measurement error reduction in view of apriori information on the rotation axis position. The practical synthesis technique for tetrahedron reflector parameters using found ratios is considered. Method. Originally, received conditions for reduction of autocollimation system measurement error are determined with the use of a matrix method for definition of an angular object position as a set of three equivalent consecutive turns about coordinate axes. At realization of these conditions the numerous recalculation of orientation parameters between various systems of coordinates is necessary that increases complexity and reduces resulting accuracy of autocollimation system at practical measurements. The method of quaternions gives the possibility to analyze the change of an absolute angular position in space, thus, there are conditions of accuracy increase regardless of the used systems of coordinates. Main Results. Researches on the mathematical model have shown, that the orthogonal arrangement of two basic constant directions for autocollimator tetrahedron reflector is optimal with respect to criterion of measurement error reduction at bisection arrangement of actual turn axis against them. Practical Relevance. On the basis of the found ratios between tetrahedron reflector angles and angles of its initial orientation parameters we have developed a practical method of reflector synthesis for autocollimation measurements in case of apriori information on an actual turn axis at monitoring measurements of the shaft or pipelines deformations.

Strongly regular family of boundary-fitted tetrahedral meshes of bounded C^2 domains

Czech Academy of Sciences Publication Activity Database

Hošek, Radim

2016-01-01

Roč. 61, č. 3 (2016), s. 233-251 ISSN 0862-7940 EU Projects: European Commission(XE) 320078 - MATHEF Institutional support: RVO:67985840 Keywords : boundary fitted mesh * strongly regular family * Sommerville tetrahedron Subject RIV: BA - General Mathematics Impact factor: 0.618, year: 2016 http://hdl.handle.net/10338.dmlcz/145699

short communication microwave assisted oxidative coupling of thiols

African Journals Online (AJOL)

Preferred Customer

13C NMR (300 MHz, CDCl3) δ 126.21 (S), 130.42 (d),. 127.3 (d), 124.85 (s), .... Ser B. 1989, 43,. 799. 5. Srivastav, V. ... Ley, S.V.; Meerholz, A.; Barton, D.H.R. Tetrahedron 1982, 38, 231. 16. Muathen, H.A. ... 1990, 31, 5007. 18. Tamamura, H.

An Electrochemical and Infrared Study of Chloranil in n-Butylpyridinium Chloride: Aluminum Chloride Ionic Liquid.

Science.gov (United States)

1982-06-01

Chem. Soc., 4540 (1962). 32. G. B. Ansell , P. R. Hammond, S. V. Hering and P. Corradini, Tetrahedron, 25, 2549 (1969). 33. L. G. Boxall, H. L. Jones and...Rill, New Jersey 07974 1 Materials Division, Research 6 Technology Deoartment Dr. Adam Weller Naval Surface Weapons Center Bell Laboratories White

On the "stacking fault" in copper

NARCIS (Netherlands)

Fransens, J.R.; Pleiter, F

2003-01-01

The results of a perturbed gamma-gamma angular correlations experiment on In-111 implanted into a properly cut single crystal of copper show that the defect known in the literature as "stacking fault" is not a planar faulted loop but a stacking fault tetrahedron with a size of 10-50 Angstrom.

Initial Chemical Events in CL-20 Under Extreme Conditions: An Ab Initio Molecular Dynamics Study

Science.gov (United States)

2006-11-01

M.; Ehara, M.; Toyota , K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li, X.; Knox, J. E...M.P.; Nissan , R.A.; Vanderah, D.J.; Gilardi, R.D.; George, C. F.; Flippen-Anderson, J. L. Tetrahedron, 1998, 54, 11793- 11812. 27. Okovytyy, S

Structures, energetics and magnetic properties of (NiSn) n clusters ...

Indian Academy of Sciences (India)

The preference for tetrahedron unit of Ni3 Sn is seen in the lowest-energy configuration of these clusters. The multi-centre bonding between Ni atoms play an important role in stabilizing the stoichiometric Ni–Sn clusters. Doping of Sn atoms enhances the binding energy and reduces the ionization potential of nickel clusters.

Synthesis, characterization, crystal structure and antibacterial activity of new sulfur-bridged dinuclear silver(I) thiosemicarbazone complex [Ag.sub.2./sub.(PPh.sub.3./sub.).sub.2./sub.(μ-S-Brcatsc).sub.2./sub.(η.sup.1./sup.-S-Brcatsc).sub.2./sub.](NO.sub.3./sub.).sub.2./sub..

Czech Academy of Sciences Publication Activity Database

Shahsavani, E.; Khalaji, A.D.; Feizi, N.; Kučeráková, Monika; Dušek, Michal

2015-01-01

Roč. 429, Apr (2015), 61-66 ISSN 0020-1693 R&D Projects: GA ČR(CZ) GA14-03276S Institutional support: RVO:68378271 Keywords : sulfur-bridged dinuclear silver(I) * thiosemicarbazone complex * single-crystal * distorted tetrahedron * antibacterial activity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.918, year: 2015

Triangles: Shapes in Math, Science and Nature.

Science.gov (United States)

Ross, Catherine Sheldrick

This book examines everything having to do with the triangle. It begins with a basic definition of the triangle and continues with discussions on tetrahedrons, triangular prisms, and pyramid shapes. Some ideas addressed include how triangles are used to measure heights and distances, the importance of triangles to builders, Alexander Graham Bell's…

Computing the Symmetry Groups of the Platonic Solids With the ...

Indian Academy of Sciences (India)

In this article we will determine the symmetry groups of the platonic solids by a combination of some elementary group theory and use of the computer algebra package. Maple. The five platonic solids are the tetrahedron, the cube, the octahedron, the dodecahedron, and the icosa- hedron. By determining a symmetry group, ...

Polyhedral meshing in numerical analysis of conjugate heat transfer

Science.gov (United States)

Sosnowski, Marcin; Krzywanski, Jaroslaw; Grabowska, Karolina; Gnatowska, Renata

2018-06-01

Computational methods have been widely applied in conjugate heat transfer analysis. The very first and crucial step in such research is the meshing process which consists in dividing the analysed geometry into numerous small control volumes (cells). In Computational Fluid Dynamics (CFD) applications it is desirable to use the hexahedral cells as the resulting mesh is characterized by low numerical diffusion. Unfortunately generating such mesh can be a very time-consuming task and in case of complicated geometry - it may not be possible to generate cells of good quality. Therefore tetrahedral cells have been implemented into commercial pre-processors. Their advantage is the ease of its generation even in case of very complex geometry. On the other hand tetrahedrons cannot be stretched excessively without decreasing the mesh quality factor, so significantly larger number of cells has to be used in comparison to hexahedral mesh in order to achieve a reasonable accuracy. Moreover the numerical diffusion of tetrahedral elements is significantly higher. Therefore the polyhedral cells are proposed within the paper in order to combine the advantages of hexahedrons (low numerical diffusion resulting in accurate solution) and tetrahedrons (rapid semi-automatic generation) as well as to overcome the disadvantages of both the above mentioned mesh types. The major benefit of polyhedral mesh is that each individual cell has many neighbours, so gradients can be well approximated. Polyhedrons are also less sensitive to stretching than tetrahedrons which results in better mesh quality leading to improved numerical stability of the model. In addition, numerical diffusion is reduced due to mass exchange over numerous faces. This leads to a more accurate solution achieved with a lower cell count. Therefore detailed comparison of numerical modelling results concerning conjugate heat transfer using tetrahedral and polyhedral meshes is presented in the paper.

Shape Factor Modeling and Simulation

Science.gov (United States)

2016-06-01

and there are only 5, as shown in Fig. 9. Fig. 9. The 5 Platonic solids, from left to right, are tetrahedron, cube or hexahedron, octahe- dron ...hidden surfaces, much like the Icosahe- dron Gage. The black curve is the lognormal fit. The maximum likelihood estimate is µ = 0.537 and σ = 0.297, which

Computing the Symmetry Groups of the Platonic Solids With the ...

Indian Academy of Sciences (India)

group theory and use of the computer algebra package. Maple. The five platonic solids are the tetrahedron, the cube, the octahedron, the dodecahedron, and the icosa- hedron. By determining a symmetry group, we lllean not just to determine its elements but to identify it, up to isomorphism, with a well-known group, such as ...

Red refinements of simplices into congruent subsimplices

Czech Academy of Sciences Publication Activity Database

Korotov, S.; Křížek, Michal

2014-01-01

Roč. 67, č. 12 (2014), s. 2199-2204 ISSN 0898-1221 R&D Projects: GA ČR GA14-02067S Institutional support: RVO:67985840 Keywords : sommerville tetrahedron * red refinement * higher-dimensional simplex Subject RIV: BA - General Mathematics Impact factor: 1.697, year: 2014 http://www.sciencedirect.com/science/article/pii/S0898122114000662

Introduction to chemistry of crystalline zeolites and its applications

International Nuclear Information System (INIS)

Lobo Cabezas, Raul Francisco

2006-01-01

Establishes the zeolites as the most important group of solid acids and its relation to the contemporaneous chemical industry. It describes that zeolites are used in the following applications: refineries, chemicals/petrochemicals, environmental chemistry, separation of gas, adsorbent ia and ionic exchange in water purification in mineral processes, medicine and agricultural industry. Zeolites are defined as crystalline aluminium silicates with a compound structure of interconnected tetrahedrons. It mentions the key components in zeolites structure. It focuses that structural basic unity of the zeolite is the tetrahedron and compound structural unities are: cells and columns. Besides, it describes that pore system defines a lot of all its properties; but chemical composition affects them. Composition and properties of zeolites are established: adsorption, molecular sieves, acidity, selectivity, transition state in the hydrocarbon's chemistry. It concludes that the newer application of zeolite is in oxidations: Titanium-Silicate-1; production of propylene's oxide using peroxide of hydrogen as oxidizing. The catalysis is an active area of research, and the most popular areas are related to chemicals and the environment [es

Molecular dynamics simulation of nano-indentation of (111) cubic boron nitride with optimized Tersoff potential

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yinbo [College of Aerospace Engineering, Chongqing University, Chongqing 400044 (China); Peng, Xianghe, E-mail: xhpeng@cqu.edu.cn [College of Aerospace Engineering, Chongqing University, Chongqing 400044 (China); State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044 (China); Fu, Tao; Huang, Cheng; Feng, Chao [College of Aerospace Engineering, Chongqing University, Chongqing 400044 (China); Yin, Deqiang [School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065 (China); Wang, Zhongchang, E-mail: zcwang@wpi-aimr.tohoku.ac.jp [College of Aerospace Engineering, Chongqing University, Chongqing 400044 (China); Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2016-09-30

Highlights: • We optimize Tersoff potential to simulate the cBN better under nanoidentation. • Dislocations slip more easily along <110> and <112> directions on the {111} plane. • Shuffle-set dislocation slip along <112> direction on {111} plane first. • A tetrahedron structure is found in the initial stage of the indentation. - Abstract: We conduct molecular dynamics simulation of nanoindentation on (111) surface of cubic boron nitride and find that shuffle-set dislocations slip along <112> direction on {111} plane at the initial stage of the indentation. The shuffle-set dislocations are then found to meet together, forming surfaces of a tetrahedron. We also find that the surfaces are stacking-fault zones, which intersect with each other, forming edges of stair-rod dislocations along <110> direction. Moreover, we also calculate the generalized stacking fault (GSF) energies along various gliding directions on several planes and find that the GSF energies of the <112>{111} and <110>{111} systems are relatively smaller, indicating that dislocations slip more easily along <110> and <112> directions on the {111} plane.

Two new ternary chalcogenides Ba{sub 2}ZnQ{sub 3} (Q = Se, Te) with chains of ZnQ{sub 4} tetrahedra. Syntheses, crystal structure, and optical and electronic properties

Energy Technology Data Exchange (ETDEWEB)

Prakash, Jai; Beard, Jessica; Malliakas, Christos D.; Ibers, James A. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Mesbah, Adel [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; ICSM, UMR 5257 CEA/CNRS/UM2/ENSCM, Bagnols-sur-Ceze (France); Rocca, Dario; Lebegue, Sebastien [Univ. de Lorraine, Vandoeuvre-les-Nancy (France). Lab. de Cristallographie, Resonance Magnetique et Modelisations (CRM2, UMR CNRS 7036)

2016-08-01

Single crystals of Ba{sub 2}ZnQ{sub 3} (Q = Se, Te) were obtained by solid-state reactions at 1173 K. These isostructural compounds crystallize in the K{sub 2}AgI{sub 3} structure type. The Zn atoms in this structure are coordinated to four Q atoms (2 Q1, 1 Q2, 1 Q3) and these form a distorted tetrahedron around each Zn atom. Each ZnQ{sub 4} tetrahedron shares two corners with neighboring ZnQ{sub 4} tetrahedra resulting in the formation of infinite chains of [ZnQ{sub 4}{sup 4-}] units. The absorption spectrum of a single crystal of Ba{sub 2}ZnTe{sub 3} shows an absorption edge at 2.10(2) eV, consistent with the dark-red color of the crystals. From DFT calculations Ba{sub 2}ZnSe{sub 3} and Ba{sub 2}ZnTe{sub 3} are found to be semiconductors with electronic band gaps of 2.6 and 1.9 eV, respectively.

Atomic and nano-scale characterization of a 50-year-old hydrated C3S paste

KAUST Repository

Geng, Guoqing; Taylor, Rae; Bae, Sungchul; Herná ndez-Cruz, Daniel; Kilcoyne, David A.; Emwas, Abdul-Hamid M.; Monteiro, Paulo J M

2015-01-01

This paper investigates the atomic and nano-scale structures of a 50-year-old hydrated alite paste. Imaged by TEM, the outer product C-S-H fibers are composed of particles that are 1.5-2 nm thick and several tens of nanometers long. 29Si NMR shows 47.9% Q1 and 52.1% Q2, with a mean SiO4 tetrahedron chain length (MCL) of 4.18, indicating a limited degree of polymerization after 50 years' hydration. A Scanning Transmission X-ray Microscopy (STXM) study was conducted on this late-age paste and a 1.5 year old hydrated C3S solution. Near Edge X-ray Absorption Fine Structure (NEXAFS) at Ca L3,2-edge indicates that Ca2 + in C-S-H is in an irregular symmetric coordination, which agrees more with the atomic structure of tobermorite than that of jennite. At Si K-edge, multi-scattering phenomenon is sensitive to the degree of polymerization, which has the potential to unveil the structure of the SiO44 - tetrahedron chain. © 2015 Elsevier Ltd. All rights reserved.

Tetrahedral gray code for visualization of genome information.

Directory of Open Access Journals (Sweden)

Natsuhiro Ichinose

Full Text Available We propose a tetrahedral Gray code that facilitates visualization of genome information on the surfaces of a tetrahedron, where the relative abundance of each [Formula: see text]-mer in the genomic sequence is represented by a color of the corresponding cell of a triangular lattice. For biological significance, the code is designed such that the [Formula: see text]-mers corresponding to any adjacent pair of cells differ from each other by only one nucleotide. We present a simple procedure to draw such a pattern on the development surfaces of a tetrahedron. The thus constructed tetrahedral Gray code can demonstrate evolutionary conservation and variation of the genome information of many organisms at a glance. We also apply the tetrahedral Gray code to the honey bee (Apis mellifera genome to analyze its methylation structure. The results indicate that the honey bee genome exhibits CpG overrepresentation in spite of its methylation ability and that two conserved motifs, CTCGAG and CGCGCG, in the unmethylated regions are responsible for the overrepresentation of CpG.

Crystal structure and thermal stability of AgIn(MoO4)2

International Nuclear Information System (INIS)

Klevtsov, P.V.; Solodovnikov, S.F.; Perepelitsa, A.P.; Klevtsova, R.F.

1984-01-01

Tetragonal crystals of double molybdate AgIn(MoO 4 ) 2 are prepared bi crystallization from solution in Ag 2 Mo 2 O 7 melt (a=4.998, c=36.725 A, space group I4 1 , Z=6). Its crystal structure is determined (autodaffractometer ''Syntex P2 1 '', MoKsub(α)-radiation, 876 reflections, R=0.054) in which along with Mo-tetrahedrons Mo-octahedrons are present. By mutual edges latter are united into bands forming fragments of wolframite structure alonside with (In, Ag) octahedrons. In the direction of c axis wolframite fragments alternate with scheelite fragments consisting of Mo-tetrahedrons and Ag-octavertices. The crystallochemical formula of the compound is Ag(Insub(0.75)Agsub(0.25))sub(2)Mosub(2)Osub(8) [MoO 4 ]. At a temperature of about 600 deq C AgIn-molybdate transforms into modification with NaIn(MoO 4 ) 2 structure NaIn(MoO 4 ) 2 and melts at 650 deg C decomposing into In 2 (MoO 4 ) 3 solid phase and Ag 2 MoO 4 melt

Structures of Pt clusters on graphene doped with nitrogen, boron, and silicon: a theoretical study

Institute of Scientific and Technical Information of China (English)

Dai Xian-Qi; Tang Ya-Nan; Dai Ya-Wei; Li Yan-Hui; Zhao Jian-Hua; Zhao Bao; Yang Zong-Xian

2011-01-01

The structures of Pt clusters on nitrogen-, boron-, silicon- doped graphenes are theoretically studied using densityfunctional theory. These dopants (nitrogen, boron and silicon) each do not induce a local curvature in the graphene and the doped graphenes all retain their planar form. The formation energy of the silicon-graphene system is lower than those of the nitrogen-, boron-doped graphenes, indicating that the silicon atom is easier to incorporate into the graphene.All the substitutional impurities enhance the interaction between the Pt atom and the graphene. The adsorption energy of a Pt adsorbed on the silicon-doped graphene is much higher than those on the nitrogen- and boron-doped graphenes.The doped silicon atom can provide more charges to enhance the Pt-graphene interaction and the formation of Pt clusters each with a large size. The stable structures of Pt clusters on the doped-graphenes are dimeric, triangle and tetrahedron with the increase of the Pt coverage. Of all the studied structures, the tetrahedron is the most stable cluster which has the least influence on the planar surface of doped-graphene.

Atomic and nano-scale characterization of a 50-year-old hydrated C3S paste

KAUST Repository

Geng, Guoqing

2015-07-15

This paper investigates the atomic and nano-scale structures of a 50-year-old hydrated alite paste. Imaged by TEM, the outer product C-S-H fibers are composed of particles that are 1.5-2 nm thick and several tens of nanometers long. 29Si NMR shows 47.9% Q1 and 52.1% Q2, with a mean SiO4 tetrahedron chain length (MCL) of 4.18, indicating a limited degree of polymerization after 50 years\\' hydration. A Scanning Transmission X-ray Microscopy (STXM) study was conducted on this late-age paste and a 1.5 year old hydrated C3S solution. Near Edge X-ray Absorption Fine Structure (NEXAFS) at Ca L3,2-edge indicates that Ca2 + in C-S-H is in an irregular symmetric coordination, which agrees more with the atomic structure of tobermorite than that of jennite. At Si K-edge, multi-scattering phenomenon is sensitive to the degree of polymerization, which has the potential to unveil the structure of the SiO44 - tetrahedron chain. © 2015 Elsevier Ltd. All rights reserved.

Monopole scattering with a twist

International Nuclear Information System (INIS)

Houghton, C.J.; Sutcliffe, P.M.

1996-01-01

By imposing certain combined inversion and rotation symmetries on the rational maps for SU(2) BPS monopoles we construct geodesics in the monopole moduli space. In the moduli space approximation these geodesics describe a novel kind of monopole scattering. During these scattering processes axial symmetry is instantaneously attained and, in some, monopoles with the symmetries of the regular solids are formed. The simplest example corresponds to a charge three monopole invariant under a combined inversion and 90 circle rotation symmetry. In this example three well-separated collinear unit charge monopoles coalesce to form first a tetrahedron, then a torus, then the dual tetrahedron and finally separate again along the same axis of motion. We explicitly construct the spectral curves in this case and use a numerical ADHMN construction to compute the energy density at various times during the motion. We find that the dynamics of the zeros of the Higgs field is extremely rich and we discover a new phenomenon; there exist charge k SU(2) BPS monopoles with more than k zeros of the Higgs field. (orig.)

Atomic and nano-scale characterization of a 50-year-old hydrated C3S paste

International Nuclear Information System (INIS)

Geng, Guoqing; Taylor, Rae; Bae, Sungchul; Hernández-Cruz, Daniel; Kilcoyne, David A.; Emwas, Abdul-Hamid; Monteiro, Paulo J.M.

2015-01-01

This paper investigates the atomic and nano-scale structures of a 50-year-old hydrated alite paste. Imaged by TEM, the outer product C–S–H fibers are composed of particles that are 1.5–2 nm thick and several tens of nanometers long. 29 Si NMR shows 47.9% Q 1 and 52.1% Q 2 , with a mean SiO 4 tetrahedron chain length (MCL) of 4.18, indicating a limited degree of polymerization after 50 years' hydration. A Scanning Transmission X-ray Microscopy (STXM) study was conducted on this late-age paste and a 1.5 year old hydrated C 3 S solution. Near Edge X-ray Absorption Fine Structure (NEXAFS) at Ca L 3,2 -edge indicates that Ca 2+ in C–S–H is in an irregular symmetric coordination, which agrees more with the atomic structure of tobermorite than that of jennite. At Si K-edge, multi-scattering phenomenon is sensitive to the degree of polymerization, which has the potential to unveil the structure of the SiO 4 4− tetrahedron chain.

Rapid Synthesis of 2-Substituted-2,3-dihydro-4(1H)-quinazolinones ...

African Journals Online (AJOL)

NICO

dron Lett., 2003, 44, 6153. 26 C. Mukhopadhyay, A. Datta and R.J. Butcher, Tetrahedron Lett., 2009,. 50, 4246. 27 G. Harichandran, S.D. Amalraj and P. Shanmugam, J. Iran. Chem. Soc.,. 2011, 8, 298. 28 M. Wang, T.T. Zhang and Z.G. Song, Chin. Chem. Lett., 2011, 22, 427. RESEARCH ARTICLE. Z. Karimi-Jaberi and L.

A Cu (NO3)2.3H2O catalysed facile synthesis of substituted 4(3H ...

Indian Academy of Sciences (India)

MS received 31 March 2012; revised 2 June 2012; accepted 28 June 2012 ... been well-established through a number of research ... do not satisfy the requirements such as operational ... 1H NMR spectra in CDCl3/DMSO-d6 as a solvent ..... 86 124. 45. Varala R, Nasreen A, Ramu E and Adapa S R 2007. Tetrahedron Lett.

A triad of rhenium-mediated transformations

Indian Academy of Sciences (India)

Unknown

Gangopadhyay J, Sengupta S, Bhattacharyya S, Chakraborty I and Chakravorty A 2002 Inorg. Chem. 41 2616. 9. Geldard J F and Lions F 1965 J. Org. Chem. 30 318. 10. Kliegman J M and Barnes R K 1970 Tetrahedron 26 2555. 11. Bhattacharyya S, Chakraborty I, Dirghangi B K and Chakravorty A 2001 Inorg. Chem.40286.

Synthesis and characterization of a reduced heteropoly ...

Indian Academy of Sciences (India)

Compound (1) crystallizes in a cubic space group 3 ¯ , with = 22.2001(6) Å and = 8. The anion [VVO4W 10 VI V 2 IV O36]7- is a typical Keggin type structure with VVO4 as the central tetrahedron. (1) has further been characterized by elemental analyses, redox titration, IR, EPR, and electronic spectroscopy and room ...

Iron(III) Chloride mediated reduction of Bis(1-isoquinolylcarbonyl ...

Indian Academy of Sciences (India)

32. Ostendorf M, Romagnoli R, Cabeza Pereiro I C, Roos. E C, Moolenaar M J, Speckamp W N and Hiemstra H. 1997 Tetrahedron: Asymmetry 8 1773. 33. Wocadlo S, Massa W and Folgado J 1993 Inorg. Chim. Acta. 207 199. 34. Bedford R B, Bruce D W, Frost R M, Goodby J W and. Hird M 2004 Chem. Commun. 2822. 35.

A non conforming finite element method for computing eigenmodes of resonant cavities

International Nuclear Information System (INIS)

Touze, F.; Le Meur, G.

1990-06-01

We present here a non conforming finite element in R 3 . This finite element, built on tetrahedrons, is particularly suited for computing eigenmodes. The main advantage of this element is that it preserves some structural properties of the space in which the solutions of the Maxwell's equations are to be found. Numerical results are presented for both two-dimensional and three-dimensional cases

Entropy estimate in three-dimensional simplicial quantum gravity

International Nuclear Information System (INIS)

Ambjoern, J.; Varsted, S.

1991-04-01

We give an estimate of the number of simplicial 3d manifolds as a function of the number N of tetrahedrons used to built the manifolds. By use of a new Monte Carlo method for generating these manifolds we provide evidence that the number is exponentially bounded if the topology of the manifold is restricted to that of S 3 . (orig.)

On the Lorentz invariance of bit-string geometry

International Nuclear Information System (INIS)

Noyes, H.P.

1995-09-01

We construct the class of integer-sided triangles and tetrahedra that respectively correspond to two or three discriminately independent bit-strings. In order to specify integer coordinates in this space, we take one vertex of a regular tetrahedron whose common edge length is an even integer as the origin of a line of integer length to the open-quotes pointclose quotes and three integer distances to this open-quotes pointclose quotes from the three remaining vertices of the reference tetrahedron. This - usually chiral - integer coordinate description of bit-string geometry is possible because three discriminately independent bit-strings generate four more; the Hamming measures of these seven strings always allow this geometrical interpretation. On another occasion we intend to prove the rotational invariance of this coordinate description. By identifying the corners of these figures with the positions of recording counters whose clocks are synchronized using the Einstein convention, we define velocities in this space. This suggests that it may be possible to define boosts and discrete Lorentz transformations in a space of integer coordinates. We relate this description to our previous work on measurement accuracy and the discrete ordered calculus of Etter and Kauffman (DOC)

Co-existence of long-range order and spin fluctuation in a new geometric frustration series M2(OH)3Cl

International Nuclear Information System (INIS)

Zheng, X.G.; Hagihala, Masato; Toriyi, Takato

2007-01-01

Recently, we observed the co-existence of a long-range magnetic order and spin fluctuation in a clean compound of clinoatacamite, Cu 2 (OH) 3 Cl (PRL95 (2005) 057201). The present work reports magnetic studies on other compounds of this transition metal series M 2 (OH) 3 Cl, where M represents three-dimensional (3D)-electron magnetic ions of Co 2+ , Fe 2+ , etc., respectively. The present study shows that this co-existence is a common feature of the M 2 Cl(OH) 3 series, no matter whether it is anti-ferromagnetic, as in the case of Fe 2 (OH) 3 Cl (T N =15 K), or ferromagnetic, as in the case of Co 2 (OH) 3 Cl (T C =10.5 K). These compounds show a 3D network of corner-sharing tetrahedrons for the magnetic ions. The tetrahedron is slightly tilted with roughly 10% longer distance between the M-M bonded by Cl than those bonded by O and this distortion is suspected to be responsible for the partial order. This research suggests that the transition metal hydroxyhalide M 2 Cl(OH) 3 series are new geometric frustration system on tetrahedral lattice for d-electron spins

Enstatite, Mg/sub 2/Si/sub 2/O/sub 6/: A neutron diffraction refinement of the crystal structure and a rigid-body analysis of the thermal vibration

Energy Technology Data Exchange (ETDEWEB)

Ghose, S.; Schomaker, V.; McMullan, R.K.

1986-01-01

Synthetic enstatite, Mg/sub 2/Si/sub 2/O/sub 6/, is orthorhombic, space group Pbca, with eight formula units per cell and lattice parameters a = 18.235(3), b = 8.818(1), c = 5.179(1) A at 23/sup 0/C. A least-squares structure refinement based on 1790 neutron intensity data converged with an agreement factor R(F/sup 2/) = 0.032, yielding Mg-O and Si-O bond lengths with standard deviations of 0.0007 and 0.0008 A, respectively. The variations observed in the Si-O bond lengths within the silicate tetrahedra A and B are caused by the differences in primary coordination of the oxygen atoms and the proximity of the magnesium ions to the silicon atoms. The latter effect is most pronounced for the bridging bonds of tetrahedron. A. The smallest O-Si-O angle is the result of edge-sharing by the Mg(2) octahedron and the A tetrahedron. An analysis of rigid-body thermal vibrations of the two crystallographically independent (SiO/sub 4/) tetrahedra indicates considerable librational motion, leading to a thermal correction of apparent Si-O bond lengths as large as +0.002 A at room temperature.

Enstatite, Mg2Si2O6: A neutron diffraction refinement of the crystal structure and a rigid-body analysis of the thermal vibration

International Nuclear Information System (INIS)

Ghose, S.; Schomaker, V.; McMullan, R.K.

1986-01-01

Synthetic enstatite, Mg 2 Si 2 O 6 , is orthorhombic, space group Pbca, with eight formula units per cell and lattice parameters a = 18.235(3), b = 8.818(1), c = 5.179(1) A at 23 0 C. A least-squares structure refinement based on 1790 neutron intensity data converged with an agreement factor R(F 2 ) = 0.032, yielding Mg-O and Si-O bond lengths with standard deviations of 0.0007 and 0.0008 A, respectively. The variations observed in the Si-O bond lengths within the silicate tetrahedra A and B are caused by the differences in primary coordination of the oxygen atoms and the proximity of the magnesium ions to the silicon atoms. The latter effect is most pronounced for the bridging bonds of tetrahedron. A. The smallest O-Si-O angle is the result of edge-sharing by the Mg(2) octahedron and the A tetrahedron. An analysis of rigid-body thermal vibrations of the two crystallographically independent [SiO 4 ] tetrahedra indicates considerable librational motion, leading to a thermal correction of apparent Si-O bond lengths as large as +0.002 A at room temperature. (orig.)

A TQFT of Tuarev-Viro type on shaped triangulations

Energy Technology Data Exchange (ETDEWEB)

Kashaev, Rinat [Geneva Univ. (Switzerland); Luo, Feng [Rutgers Univ., Piscataway, NJ (United States). Dept. of Mathematics; Vartanov, Grigory [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-10-15

A shaped triangulation is a finite triangulation of an oriented pseudo three manifold where each tetrahedron carries dihedral angles of an ideal hyberbolic tetrahedron. To each shaped triangulation, we associate a quantum partition function in the form of an absolutely convergent state integral which is invariant under shaped 3-2 Pachner moves and invariant with respect to shape gauge transformations generated by total dihedral angles around internal edges through the Neumann-Zagier Poisson bracket. Similarly to Turaev-Viro theory, the state variables live on edges of the triangulation but take their values on the whole real axis. The tetrahedral weight functions are composed of three hyperbolic gamma functions in a way that they enjoy a manifest tetrahedral symmetry. We conjecture that for shaped triangulations of closed 3-manifolds, our partition function is twice the absolute value squared of the partition function of Techmueller TQFT defined by Andersen and Kashaev. This is similar to the known relationship between the Turaev-Viro and the Witten-Reshetikhin-Turaev invariants of three manifolds. We also discuss interpretations of our construction in terms of three-dimensional supersymmetric field theories related to triangulated three-dimensional manifolds.

Synthesis, crystal structures and luminescence properties of two metal carboxyphosphonates

Energy Technology Data Exchange (ETDEWEB)

Wang, Chaonan; Feng, Pingjing; Li, Jintang, E-mail: leejt@xmu.edu.cn; Luo, Xuetao

2017-05-15

Two metal carboxyphosphonates, [Co{sub 2}(OOCC{sub 5}H{sub 3}NPO{sub 3}){sub 2·}(H{sub 2}O){sub 3}] (Compound1) and Zn{sub 3}[OOCC{sub 6}H{sub 3}CH(OH)PO{sub 3}]{sub 2·}2H{sub 2}O (Compound2) were successfully synthesized under the hydrothermal reactions. In compound 1, two (Co1-NO{sub 5}) octahedra link the (CPO{sub 3}) by sharing the corner, which link the two (Co2-O{sub 6}) octahedra. From a-axis the six clusters form the layer. Each layer is linked through hydrogen bond. In compound 2, the (Zn-O{sub 4}) tetrahedron and (CPO{sub 3}) tetrahedron are corner-shared, which arrange in line. From a-axis, each line forms the columnar. The thermal and luminescence properties of these compounds were investigated. - Graphical abstract: The synthesis conditions of the two compounds and the crystal morphology. Compound 1 shows the layer and the compound 2 shows the pillared-layer. - Highlights: • Two new carboxyphosphonate ligands have been prepared. • Using the two ligands, two metal carboxyphosphonates have been synthesized. • The two MOFs may be candidates for fluorescent materials.

Length expectation values in quantum Regge calculus

International Nuclear Information System (INIS)

Khatsymovsky, V.M.

2004-01-01

Regge calculus configuration superspace can be embedded into a more general superspace where the length of any edge is defined ambiguously depending on the 4-tetrahedron containing the edge. Moreover, the latter superspace can be extended further so that even edge lengths in each the 4-tetrahedron are not defined, only area tensors of the 2-faces in it are. We make use of our previous result concerning quantization of the area tensor Regge calculus which gives finite expectation values for areas. Also our result is used showing that quantum measure in the Regge calculus can be uniquely fixed once we know quantum measure on (the space of the functionals on) the superspace of the theory with ambiguously defined edge lengths. We find that in this framework quantization of the usual Regge calculus is defined up to a parameter. The theory may possess nonzero (of the order of Planck scale) or zero length expectation values depending on whether this parameter is larger or smaller than a certain value. Vanishing length expectation values means that the theory is becoming continuous, here dynamically in the originally discrete framework

Tetra-μ3-iodido-tetrakis[(tri-n-butylphosphane-κPcopper(I

Directory of Open Access Journals (Sweden)

Simon Klenk

2014-04-01

Full Text Available The title complex, [Cu4I4(C12H27P4], crystallizes with six molecules in the unit cell and with three independent one-third molecule fragments, completed by application of the relevant symmetry operators, in the asymmetric unit. The tetranuclear copper core shows a tetrahedral geometry (site symmetry 3... The I atoms also form a tetrahedron, with I...I distances of 4.471 (1 Å. Both tetrahedra show an orientation similar to that of a pair of self-dual platonic bodies. The edges of the I-tetrahedral structure are capped to the face centers of the Cu-tetrahedron and vice versa. The Cuface...I distances are 2.18 Å (averaged and the Iface...Cu distances are 0.78 Å (averaged. As a geometric consequence of these properties there are eight distorted trigonal–bipyramidal polyhedra evident, wherein each trigonal face builds up the equatorial site and the opposite Cu...I positions form the axial site. As expected, the n-butyl moieties are highly flexible, resulting in large elongations of their anisotropic displacement parameters. Some C atoms of the n-butyl groups were needed to fix alternative discrete disordered positions.

Vibrational spectroscopic and dielectric properties investigations of phase transitions in KMgPO4 compound

Science.gov (United States)

Miladi, L.; Oueslati, A.; Guidara, K.

2017-11-01

The potassium orthophosphate KMgPO4 with a β-tridymite structure was synthesized via solid-state reaction. X-ray diffraction study confirms the formation of a single phase material which crystallizes at room temperature in monoclinic system. This compound has been investigated by vibrational spectroscopy in the temperature range573-723 K. Thermal analysis shows that this composition undergoes two phase transitions at T1=633Kand T2=693 K.The evolution of Raman line ν and half -width Δν versus temperature introduces huge changes which are associated with the phase transitions originating from the reorientation of the PO4 tetrahedron. Besides, an analysis of the dielectric constants ε‧ and ε″versus temperature at several frequencies shows a distribution of relaxation times. This relaxation is probably due to the change in dynamical state of the K+ cation. The ac conductivity behavior can be understood in terms of the motions of K+ cations along the tunnels which are formed by six-membered rings of MgO4 and PO4 tetrahedron linked by common vertices. The activation energies values obtained from the thermal evolution of the conductivity are: Ea1=0.52 eV (T693 K).

Structural characterization and compositional dependence of the optical properties of Ge-Ga-La-S chalcohalide glass system

Science.gov (United States)

Li, Lini; Jiao, Qing; Lin, Changgui; Dai, Shixun; Nie, Qiuhua

2018-04-01

In this paper, chalcogenide glasses of 80GeS2sbnd (20sbnd x)Ga2S3sbnd xLa2S3 (x = 0, 1, 3, 5 mol%) were synthesized through the traditional melt-quenching technique. The effects of La2S3 addition on the thermal, optical, and structural properties of Gesbnd Gasbnd S glasses were investigated. Results showed that the synthesized glasses possessed considerably high glass transition temperature, improved glass forming ability, high refractive index, and excellent infrared transmittance. A redshift at the visible absorbing cut-off edge lower than 500 nm was observed with increasing of La2S3 content. Direct and indirect optical band gap values were calculated. SEM result suggested that this glass system owned better glass forming ability and uniformity. Raman spectral analysis indicated that the introduction of La2S3 induced the dissociation of Gesbnd Ge metal bonds and transformed the [S3Gesbnd GeS3] structure to GeS4 tetrahedrons. Consequently, the connectivity between tetrahedrons of the vitreous network was enhanced. This work suggests that La2S3 modified Ge-Gasbnd Lasbnd S glass is a promising material for infrared optical research.

Logical and Geometrical Distance in Polyhedral Aristotelian Diagrams in Knowledge Representation

Directory of Open Access Journals (Sweden)

Lorenz Demey

2017-09-01

Full Text Available Aristotelian diagrams visualize the logical relations among a finite set of objects. These diagrams originated in philosophy, but recently, they have also been used extensively in artificial intelligence, in order to study (connections between various knowledge representation formalisms. In this paper, we develop the idea that Aristotelian diagrams can be fruitfully studied as geometrical entities. In particular, we focus on four polyhedral Aristotelian diagrams for the Boolean algebra B 4 , viz. the rhombic dodecahedron, the tetrakis hexahedron, the tetraicosahedron and the nested tetrahedron. After an in-depth investigation of the geometrical properties and interrelationships of these polyhedral diagrams, we analyze the correlation (or lack thereof between logical (Hamming and geometrical (Euclidean distance in each of these diagrams. The outcome of this analysis is that the Aristotelian rhombic dodecahedron and tetrakis hexahedron exhibit the strongest degree of correlation between logical and geometrical distance; the tetraicosahedron performs worse; and the nested tetrahedron has the lowest degree of correlation. Finally, these results are used to shed new light on the relative strengths and weaknesses of these polyhedral Aristotelian diagrams, by appealing to the congruence principle from cognitive research on diagram design.

A TQFT of Tuarev-Viro type on shaped triangulations

International Nuclear Information System (INIS)

Kashaev, Rinat; Luo, Feng

2012-10-01

A shaped triangulation is a finite triangulation of an oriented pseudo three manifold where each tetrahedron carries dihedral angles of an ideal hyberbolic tetrahedron. To each shaped triangulation, we associate a quantum partition function in the form of an absolutely convergent state integral which is invariant under shaped 3-2 Pachner moves and invariant with respect to shape gauge transformations generated by total dihedral angles around internal edges through the Neumann-Zagier Poisson bracket. Similarly to Turaev-Viro theory, the state variables live on edges of the triangulation but take their values on the whole real axis. The tetrahedral weight functions are composed of three hyperbolic gamma functions in a way that they enjoy a manifest tetrahedral symmetry. We conjecture that for shaped triangulations of closed 3-manifolds, our partition function is twice the absolute value squared of the partition function of Techmueller TQFT defined by Andersen and Kashaev. This is similar to the known relationship between the Turaev-Viro and the Witten-Reshetikhin-Turaev invariants of three manifolds. We also discuss interpretations of our construction in terms of three-dimensional supersymmetric field theories related to triangulated three-dimensional manifolds.

Untitled

Indian Academy of Sciences (India)

Beak P and Chen C W 1985 Tetrahedron Lett. 4979. Boatman R J, Whitlock B J and Whitlock H W 1977 J. An. Chen. Soc. 99 4822. Diamond S E, Szalkiewicz A and Mares F 1979 J. Ann. Chen. Soc. 101 490. Ellefson C R 1979 J. Org. Chem. 44 1533. Gschwend H W and Rodriguez H R 1979 Organic reactions 26 Chapter I.

Applications of the theorem of Pythagoras in R3

Science.gov (United States)

Srinivasan, V. K.

2010-01-01

Three distinct points ? and ? with ? are taken, respectively on the x, y and the z-axes of a rectangular coordinate system in ? Using the converse of the theorem of Pythagoras, it is shown that the triangle ? can never be a right-angled triangle. The result seems to be intuitive, but nevertheless requires a proof. As an application, some intuitive results about a tetrahedron are confirmed.

Coordination Structure of Aluminum in Magnesium Aluminum Hydroxide Studied by 27Al NMR

Institute of Scientific and Technical Information of China (English)

无

2003-01-01

The coordination structure of aluminum in magnesium aluminum hydroxide was studiedby 27Al NMR. The result showed that tetrahedral aluminum (AlⅣ) existed in magnesiumaluminum hydroxide, and the contents of AlⅣ increased with the increase of the ratio of Al/Mg andwith the peptizing temperature. AlⅣ originated from the so-called Al13 polymer with the structureof one Al tetrahedron surrounded by twelve Al octahedrons.

Nonobtuse local tetrahedral refinements towards a polygonal face/interface

Czech Academy of Sciences Publication Activity Database

Korotov, S.; Křížek, Michal

2011-01-01

Roč. 24, č. 6 (2011), s. 817-821 ISSN 0893-9659 R&D Projects: GA AV ČR(CZ) IAA100190803 Institutional research plan: CEZ:AV0Z10190503 Keywords : finite element method * nonobtuse tetrahedron * local refinement * discrete maximum principle * boundary and interior layers * interface problem Subject RIV: BA - General Mathematics Impact factor: 1.371, year: 2011 http://www.sciencedirect.com/science/article/pii/S0893965910004726

Consideration of the Verleur model of far-infrared spectroscopy of ternary compounds

International Nuclear Information System (INIS)

Robouch, B. V.; Kisiel, A.; Sheregii, E. M.

2001-01-01

The clustering model proposed by Verleur and Barker [Phys. Rev. 149, 715 (1966)] to interpret far infrared data for face-centered-cubic ternary compounds is critically analyzed. It is shown that their approach, satisfactory for fitting some ternary compound spectral curves, is too restricted by its one-parameter β model to be able to describe preferences (with respect to a random distribution case) for the five tetrahedron configurations

Structure and conformational dynamics of scaffolded DNA origami nanoparticles

Science.gov (United States)

2017-05-08

vertices of the tetrahedron, and an unconstrained 4-arm vertex region corresponding to the vertices of the octahe- dron (Figure 2B and C). Both the 3...all-atommodels of the tetrahe- dron , octahedron, unconstrained 3- and 4-arm vertices, and the unconstrained duplex bulge represent equilibrium val...structural analysis of 4-arm vertices within a self-assembled octahe- dron imaged using cryo-EM (87). This prediction suggests an enantiomeric preference

In search of empty space: the Cluster mission

International Nuclear Information System (INIS)

Johnstone, Alan

1990-01-01

Using four spacecraft, orbiting the earth, in the formation of a regular tetrahedron, European scientists will study the auroras around the planet caused by variations in the Sun's magnetic field. These cluster satellites will also study supernovae from their interplanetary position and the plasma of space surrounding us on the Earth. A growing understanding of the plasma dynamics is hoped to assist in the study of nuclear fusion. (UK)

An Approach for Autonomy: A Collaborative Communication Framework for Multi-Agent Systems

Science.gov (United States)

Dufrene, Warren Russell, Jr.

2005-01-01

Research done during the last three years has studied the emersion properties of Complex Adaptive Systems (CAS). The deployment of Artificial Intelligence (AI) techniques applied to remote Unmanned Aerial Vehicles has led the author to investigate applications of CAS within the field of Autonomous Multi-Agent Systems. The core objective of current research efforts is focused on the simplicity of Intelligent Agents (IA) and the modeling of these agents within complex systems. This research effort looks at the communication, interaction, and adaptability of multi-agents as applied to complex systems control. The embodiment concept applied to robotics has application possibilities within multi-agent frameworks. A new framework for agent awareness within a virtual 3D world concept is possible where the vehicle is composed of collaborative agents. This approach has many possibilities for applications to complex systems. This paper describes the development of an approach to apply this virtual framework to the NASA Goddard Space Flight Center (GSFC) tetrahedron structure developed under the Autonomous Nano Technology Swarm (ANTS) program and the Super Miniaturized Addressable Reconfigurable Technology (SMART) architecture program. These projects represent an innovative set of novel concepts deploying adaptable, self-organizing structures composed of many tetrahedrons. This technology is pushing current applied Agents Concepts to new levels of requirements and adaptability.

Pseudo-topotactic conversion of carbon nanotubes to T-carbon nanowires under picosecond laser irradiation in methanol.

Science.gov (United States)

Zhang, Jinying; Wang, Rui; Zhu, Xi; Pan, Aifei; Han, Chenxiao; Li, Xin; Dan Zhao; Ma, Chuansheng; Wang, Wenjun; Su, Haibin; Niu, Chunming

2017-09-25

Pseudo-topotactic conversion of carbon nanotubes into one-dimensional carbon nanowires is a challenging but feasible path to obtain desired diameters and morphologies. Here, a previously predicted but experimentally unobserved carbon allotrope, T-carbon, has been produced from pseudo-topotactic conversion of a multi-walled carbon nanotube suspension in methanol by picosecond pulsed-laser irradiation. The as-grown T-carbon nanowires have the same diameter distribution as pristine carbon nanotubes, and have been characterized by high-resolution transmission electron microscopy, fast Fourier transform, electron energy loss, ultraviolet-visible, and photoluminescence spectroscopies to possess a diamond-like lattice, where each carbon is replaced by a carbon tetrahedron, and a lattice constant of 7.80 Å. The change in entropy from carbon nanotubes to T-carbon reveals the phase transformation to be first order in nature. The computed electronic band structures and projected density of states are in good agreement with the optical absorption and photoluminescence spectra of the T-carbon nanowires.T-carbon is a previously predicted but so far unobserved allotrope of carbon, with a crystal structure similar to diamond, but with each atomic lattice position replaced by a carbon tetrahedron. Here, the authors produce T-carbon nanowires via laser-irradiating a suspension of carbon nanotubes in methanol.

Determination of the structures of small gold clusters on stepped magnesia by density functional calculations.

Science.gov (United States)

Damianos, Konstantina; Ferrando, Riccardo

2012-02-21

The structural modifications of small supported gold clusters caused by realistic surface defects (steps) in the MgO(001) support are investigated by computational methods. The most stable gold cluster structures on a stepped MgO(001) surface are searched for in the size range up to 24 Au atoms, and locally optimized by density-functional calculations. Several structural motifs are found within energy differences of 1 eV: inclined leaflets, arched leaflets, pyramidal hollow cages and compact structures. We show that the interaction with the step clearly modifies the structures with respect to adsorption on the flat defect-free surface. We find that leaflet structures clearly dominate for smaller sizes. These leaflets are either inclined and quasi-horizontal, or arched, at variance with the case of the flat surface in which vertical leaflets prevail. With increasing cluster size pyramidal hollow cages begin to compete against leaflet structures. Cage structures become more and more favourable as size increases. The only exception is size 20, at which the tetrahedron is found as the most stable isomer. This tetrahedron is however quite distorted. The comparison of two different exchange-correlation functionals (Perdew-Burke-Ernzerhof and local density approximation) show the same qualitative trends. This journal is © The Royal Society of Chemistry 2012

Methylene blue adsorption of GMZ bentonite and the effect of hyper-alkaline solution erosion

International Nuclear Information System (INIS)

Chen Bao; Zhang Huixin; Zhu Chunming; Chen Ping

2012-01-01

The method of combining the halo method with the spectrometer method, was used to study on the Methylene blue (MB) adsorption of Gaomiaozi (GMZ) bentonite, which had been eroded by hyper-alkaline solution, to investigate the mechanism of the effect of hyper-alkaline pore water on the buffer/backfill properties of GMZ bentonite. Results present, method employed in this article is brief and feasible, and high accuracy; The total specific surface area calculated by the test of MB adsorption is more accurate than the method of ethylene glycol monomethyl ether (EGIVIE). The MB adsorption of samples, which had been eroded by hyper-alkaline solution, decreases with the increase of the concentration of hyper-alkaline solution, and the change law agrees with the variation of the mass percentage of montmorillonite in bentonite tested by X- Ray diffraction (XRD). Therefore, the erosion of hyper-alkaline pore water might dissolve montmorillonite, which is the effective composition of bentonite, and destroy the tetrahedron- octahedron-tetrahedron (T-O-T) structure of montmorillonite, then lead to the decrease of cation exchange capability and the specific surface area of montmorillonite, and the the macroscopic expressions are the decrease of MB adsorption, the swelling potential and the increase of permeability. (authors)

The behavior of hydrogen in metals

International Nuclear Information System (INIS)

Hirabayashi, Makoto

1975-01-01

Explanation is made on the equilibrium diagrams of metal-hydrogen systems and the state of hydrogen in metals. Some metals perform exothermic reaction with hydrogen, and the others endothermic reaction. The former form stable hydrides and solid solutions over a wide range of composition. Hydrogen atoms in fcc and bcc metals are present at the interstitial positions of tetrahedron lattice and octahedron lattice. For example, hydrogen atoms in palladium are present at the intersititial positions of octahedron. When the ratio of the composition of hydrogen and palladium is 1:1, the structure becomes NaCl type. Hydrogen atoms in niobium and vanadium and present interstitially in tetrahedron lattice. Metal hydrides with high hydrogen concentration are becoming important recently as the containers of hydrogen. Hydrogen atoms diffuse in metals quite easily. The activation energy of the diffusion of hydrogen atoms in Nb and V is about 2-3 kcal/g.atom. The diffusion coefficient is about 10 -5 cm 2 /sec in alpha phase at room temperature. The number of jumps of a hydrogen atom between neighboring lattice sites is 10 11 --10 12 times per second. This datum is almost the same as that of liquid metals. Discussion is also made on the electronic state of hydrogen in metals. (Fukutomi, T.)

Size, Shape, and Sequence-Dependent Immunogenicity of RNA Nanoparticles

Directory of Open Access Journals (Sweden)

Sijin Guo

2017-12-01

Full Text Available RNA molecules have emerged as promising therapeutics. Like all other drugs, the safety profile and immune response are important criteria for drug evaluation. However, the literature on RNA immunogenicity has been controversial. Here, we used the approach of RNA nanotechnology to demonstrate that the immune response of RNA nanoparticles is size, shape, and sequence dependent. RNA triangle, square, pentagon, and tetrahedron with same shape but different sizes, or same size but different shapes were used as models to investigate the immune response. The levels of pro-inflammatory cytokines induced by these RNA nanoarchitectures were assessed in macrophage-like cells and animals. It was found that RNA polygons without extension at the vertexes were immune inert. However, when single-stranded RNA with a specific sequence was extended from the vertexes of RNA polygons, strong immune responses were detected. These immunostimulations are sequence specific, because some other extended sequences induced little or no immune response. Additionally, larger-size RNA square induced stronger cytokine secretion. 3D RNA tetrahedron showed stronger immunostimulation than planar RNA triangle. These results suggest that the immunogenicity of RNA nanoparticles is tunable to produce either a minimal immune response that can serve as safe therapeutic vectors, or a strong immune response for cancer immunotherapy or vaccine adjuvants.

Minima de L'intégrale D'action du Problème Newtoniende 4 Corps de Masses Égales Dans R3: Orbites `Hip-Hop'

Science.gov (United States)

Chenciner, Alain; Venturelli, Andrea

2000-09-01

We consider the problem of 4 bodies of equal masses in R 3 for the Newtonian r-1 potential. We address the question of the absolute minima of the action integral among (anti)symmetric loops of class H 1 whose period is fixed. It is the simplest case for which the results of [4] (corrected in [5]) do not apply: the minima cannot be the relative equilibria whose configuration is an absolute minimum of the potential among the configurations having a given moment of inertia with respect to their center of mass. This is because the regular tetrahedron cannot have a relative equilibrium motion in R 3 (see [2]). We show that the absolute minima of the action are not homographic motions. We also show that if we force the configuration to admit a certain type of symmetry of order 4, the absolute minimum is a collisionless orbit whose configuration ‘hesitates’ between the central configuration of the square and the one of the tetrahedron. We call these orbits ‘hip-hop’. A similar result holds in case of a symmetry of order 3 where the central configuration of the equilateral triangle with a body at the center of mass replaces the square.

Green procedures for the chemoselective synthesis of acylals and ...

Indian Academy of Sciences (India)

Li C J and Chan T H 1999 Tetrahedron 55 11149. 5. Li C J 2005 Chem. Rev. 105 3095. 6. Greene T W and Wuts P G M 1999 In Protective Groups in Organic Synthesis 3rd ed. (New York: John Wiley and. Sons) p. 306. 7. Gregory M J 1970 J. Chem. Soc. B. 1201. 8. Jin T S, Sun G, Li Y W and Li T S 2002 Green Chem. 4. 255.

Butterfly wing color: A photonic crystal demonstration

Science.gov (United States)

Proietti Zaccaria, Remo

2016-01-01

We have theoretically modeled the optical behavior of a natural occurring photonic crystal, as defined by the geometrical characteristics of the Teinopalpus Imperialis butterfly. In particular, following a genetic algorithm approach, we demonstrate how its wings follow a triclinic crystal geometry with a tetrahedron unit base. By performing both photonic band analysis and transmission/reflection simulations, we are able to explain the characteristic colors emerging by the butterfly wings, thus confirming their crystal form.

Acid indium strontium phosphate SrIn2[PO3(OH)]4: synthesis and crystal structure

International Nuclear Information System (INIS)

Rusakov, D.A.; Bobylev, A.P.; Komissarova, L.N.; Filaretov, A.A.; Danilov, V.P.

2007-01-01

Acid indium-strontium phosphate SrIn 2 [PO 3 (OH)] 4 is synthesized and characterized. Crystal structure and lattice parameters ate determined. In atoms in SrIn 2 [PO 3 (OH)] 4 structure are in distorted InO 6 octahedrons and form with PO 3 (OH) tetrahedrons mixed paraskeleton {In 2 [PO 3 (OH)] 4 } 3∞ 2- with emptinesses occupied by big Sr 2+ cations. The compound is thermally stable up to 400 Deg C [ru

Dislocation-stacking fault tetrahedron interaction: what can we learn from atomic-scale modelling

International Nuclear Information System (INIS)

Osetsky, Yu.N.; Stoller, R.E.; Matsukawa, Y.

2004-01-01

The high number density of stacking fault tetrahedra (SFTs) observed in irradiated fcc metals suggests that they should contribute to radiation-induced hardening and, therefore, taken into account when estimating mechanical properties changes of irradiated materials. The central issue is describing the individual interaction between a moving dislocation and an SFT, which is characterized by a very fine size scale, ∼100 nm. This scale is amenable to both in situ TEM experiments and large-scale atomic modelling. In this paper we present results of an atomistic simulation of dislocation-SFT interactions using molecular dynamics (MD). The results are compared with observations from in situ deformation experiments. It is demonstrated that in some cases the simulations and experimental observations are quite similar, suggesting a reasonable interpretation of experimental observations

Hydrogen Bonded Supramolecular Polymers in Both Apolar and Aqueous Media： Self-Assembly and Reversible Conversion of Vesicles and Gels%Hydrogen Bonded Supramolecular Polymers in Both Apolar and Aqueous Media： Self-Assembly and Reversible Conversion of Vesicles and Gels

Institute of Scientific and Technical Information of China (English)

杜平; 孔军; 王贵涛; 赵新; 李光玉; 蒋锡夔; 黎占亭

2011-01-01

In a preliminary letter （Tetrahedron Lett. 2010, 51, 188）, we reported two new hydrazide-based quadruple hydrogen-bonding motifs, this is, two monopodal （la and lb） and five dipodal （2a, 2b and 3a--3c） aromatic hydrazide derivatives, and the formation of supramolecular polymers and vesicles from the dipodal motifs in hydrocarbons. In this paper, we present a full picture on the properties of these hydrogen-bonding motifs with an emphasis on their self-assembling behaviors in aqueous media. SEM, AFM, TEM and fluorescent micrographs indicate that all the dipodal compounds also form vesicles in polar methanol and water-methanol （up to 50% of water） mixtures. Control experiments show that lb does not form vesicles in same media. Addition of lb to the solution of the dipodal compounds inhibits the latter＇s capacity of forming vesicles. At high concentrations, 3b and 3c also gelate discrete solvents, including hydrocarbons, esters, methanol, and methanol-water mixture. Concentration-dependent SEM investigations reveal that the vesicles of 3b and 3c fuse to form gels and the gel of 3c can de-aggregate to form the vesicles reversibly.

Letter Names, Letter Sounds and Phonological Awareness: An Examination of Kindergarten Children across Letters and of Letters across Children

Science.gov (United States)

Evans, Mary Ann; Bell, Michelle; Shaw, Deborah; Moretti, Shelley; Page, Jodi

2006-01-01

In this study 149 kindergarten children were assessed for knowledge of letter names and letter sounds, phonological awareness, and cognitive abilities. Through this it examined child and letter characteristics influencing the acquisition of alphabetic knowledge in a naturalistic context, the relationship between letter-sound knowledge and…

Rondorfite-type structure — XPS and UV–vis study

Energy Technology Data Exchange (ETDEWEB)

Dulski, M., E-mail: mateusz.dulski@smcebi.edu.pl [Institute of Material Science, University of Silesia, 75 Pułku Piechoty 1a, 41-500 Chorzow (Poland); A.Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Bilewska, K., E-mail: kbilewska@us.edu.pl [A.Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1a, 41-500 Chorzow (Poland); Institute of Non-Ferrous Metals, Sowińskiego 5, 44-100 Gliwice (Poland); Wojtyniak, M., E-mail: marcin.wojtyniak@us.edu.pl [Institute of Material Science, University of Silesia, 75 Pułku Piechoty 1a, 41-500 Chorzow (Poland); Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1a, 41-500 Chorzow (Poland); Szade, J., E-mail: jacek.szade@us.edu.pl [A.Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1a, 41-500 Chorzow (Poland); Kusz, J., E-mail: joachim.kusz@us.edu.pl [A.Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Nowak, A., E-mail: ana.maria.nowak@gmail.com [A.Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1a, 41-500 Chorzow (Poland); Wrzalik, R., E-mail: roman.wrzalik@us.edu.pl [A.Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1a, 41-500 Chorzow (Poland); and others

2015-10-15

Highlights: • Structural and spectroscopic characterization of chlorosilicate mineral, rondorfite. • Characterization of main photoemission lines and valence band spectra. • The study of color origin’s using UV–vis spectroscopy. • Analysis of structural changes in context of origin of natural fluorescence. • Discussion of a new application possibilities of analyzed mineral - Abstract: This paper focuses on X-ray diffraction, X-ray photoelectron and UV–vis spectroscopy of two different (green, orange) rondorfite samples. The differences in the sample color originate from various O/Cl ratios. The orange color was found to be related either to the isomorphic substitution of Fe{sup 3+}/Al{sup 3+} for Mg{sup 2+}, the presence of atypical [MgO{sub 4}] tetrahedrons in crystal structure or electronegativity of the sample. The tetrahedron is known to be very prone to accumulation of impurities and substitute atoms. Moreover, the XPS data showed tetrahedrally coordinated Mg{sup 2+} and isomorphic substitution of Al{sup 3+}/Fe{sup 3+} for Mg{sup 2+}, which influences local disordering and the point defects density and distribution. Non-equilibrium chlorine positions inside the crystal cages as well as Ca-Cl bonds have also been found. The XPS measurements as a function of temperature indicate occurrence of a structural transformation at about 770 K which is accompanied by a rotation of silicate tetrahedra within magnesiosilicate pentamer and luminescence disappearance.

Effect of Al/Ga substitution on the structural and luminescence properties of Y3(Al1-xGax)5O12: Ce3+ phosphors

Science.gov (United States)

Fu, Sheng; Tan, Jin; Bai, Xin; Yang, Shanjie; You, Lei; Du, Zhengkang

2018-01-01

As candidates for display and lighting materials, a series of gallium-substituted cerium-doped yttrium aluminum garnet (Y3(GaxAl1-x)5O12: Ce3+) phosphors were synthesized by high temperature solid-state reaction. The phases, morphology, luminescence spectra and thermal stability of the phosphors were investigated. The volatilization of Ga2O3 induces the constituents out of stoichiometric ratio and different impurities in the system. The excitation and emission spectra occur red shift (339 nm - 351 nm) and blue shift (465 nm - 437 nm), and blue shift (541 nm - 517 nm), respectively. The spectra have no further blue shift and the luminescence intensity decrease with x over 0.4. Combining crystal structure with PL spectrum, the distortion of dodecahedron and crystal field splitting of 5d level of Ce3+ are influenced by Ga3+ in octahedral coordination polyhedron rather than tetrahedron. The crystalline perfection and Ga3+ occupying the tetrahedron induce less garnet phase formation, more impurities and the 5d level located in the conductive bands, thus accounting for the x = 0.4 turning points of the PL and PLE intensity. Based on the thermal quenching and CIE, the Y3(GaxAl1-x)5O12: Ce3+0.06 phosphors have great potential for use on the w-LED.

Size, Shape, and Sequence-Dependent Immunogenicity of RNA Nanoparticles.

Science.gov (United States)

Guo, Sijin; Li, Hui; Ma, Mengshi; Fu, Jian; Dong, Yizhou; Guo, Peixuan

2017-12-15

RNA molecules have emerged as promising therapeutics. Like all other drugs, the safety profile and immune response are important criteria for drug evaluation. However, the literature on RNA immunogenicity has been controversial. Here, we used the approach of RNA nanotechnology to demonstrate that the immune response of RNA nanoparticles is size, shape, and sequence dependent. RNA triangle, square, pentagon, and tetrahedron with same shape but different sizes, or same size but different shapes were used as models to investigate the immune response. The levels of pro-inflammatory cytokines induced by these RNA nanoarchitectures were assessed in macrophage-like cells and animals. It was found that RNA polygons without extension at the vertexes were immune inert. However, when single-stranded RNA with a specific sequence was extended from the vertexes of RNA polygons, strong immune responses were detected. These immunostimulations are sequence specific, because some other extended sequences induced little or no immune response. Additionally, larger-size RNA square induced stronger cytokine secretion. 3D RNA tetrahedron showed stronger immunostimulation than planar RNA triangle. These results suggest that the immunogenicity of RNA nanoparticles is tunable to produce either a minimal immune response that can serve as safe therapeutic vectors, or a strong immune response for cancer immunotherapy or vaccine adjuvants. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Letter-Sound Knowledge: Exploring Gender Differences in Children When They Start School Regarding Knowledge of Large Letters, Small Letters, Sound Large Letters, and Sound Small Letters

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Hermundur Sigmundsson

2017-09-01

Full Text Available This study explored whether there is a gender difference in letter-sound knowledge when children start at school. 485 children aged 5–6 years completed assessment of letter-sound knowledge, i.e., large letters; sound of large letters; small letters; sound of small letters. The findings indicate a significant difference between girls and boys in all four factors tested in this study in favor of the girls. There are still no clear explanations to the basis of a presumed gender difference in letter-sound knowledge. That the findings have origin in neuro-biological factors cannot be excluded, however, the fact that girls probably have been exposed to more language experience/stimulation compared to boys, lends support to explanations derived from environmental aspects.

Saturnian north polar region: a triangle inside the hexagon?

Science.gov (United States)

Kochemasov, Gennady G.

2010-05-01

The famous and "mysterious" stable hexagon structure around the North Pole of Saturn was earlier interpreted as projections of faces of a structural tetrahedron [1]. This "hidden" simplest Plato's polyhedron is a result of an interference of four fundamental (wave 1) warping waves having in any rotating celestial body four directions: orthogonal and diagonal. Origin of the warping waves in any celestial body is due to their movements in elliptical keplerian orbits with periodically changing accelerations. The structural tetrahedron is an intrinsic geometric feature marking the celestial bodies ubiquitous tectonic dichotomy as in a tetrahedron always there is an opposition of a face (expansion) and a vertex (contraction). In the saturnian case the tetrahedron shows a face at the north and a vertex at the south. Morphologically this is manifested by the hexagon and opposing it in the south a vertex. Blue and pink hues of the northern and southern hemispheres also underline the tectonic dichotomy. These geometric expressions are enforced by a subtle dark equilateral triangle appearing in the image PIA11682 also around the north pole and inside the hexagon (the triangle side is about 15000 km long). One angle of the triangle is clearly visible, another one just shows itself and the third one is barely distinguished. The sides of the triangle are not strait lines but slightly broken amidst lines what makes the triangle appear a bit hexagonal (spherical) and the angle is a bit bigger than 60 degrees of a classical equilateral triangle (~70 degrees). The central part of the triangle is not imaged (a black hole in the PIA11682). This image also confirms that the wide northern polar region is also densely "peppered" with bright cloudy more or less isometric spots on average 400 to 800 km across as in other latitudinal belts of Saturn [2, 3, 4]. Earlier they were observed in IR wavelengths, now they show themselves in visible wavelengths. Their origin and size were

Antifouling sesquiterpene from the Indian soft coral, Sinularia kavarattiensis Alderslade and Prita

Digital Repository Service at National Institute of Oceanography (India)

LimnaMol, V.P.; Raveendran, T.V.; Parameswaran, P.S.; Kunnath, R.J.; Sathyan, N.

analysis of preference data, Appl Entomol Zool, 33 (1998) 339-347. 16 Williams D H & Faulkner D J, Two practical syntheses of an anti-inflammatory sesquiterpene furoic acid from Sinularia spp. Tetrahedron, 52 (1996) 4245-4256. 17 Rittschof D, Lai C H..., Kok L M & Teo S L M, Pharmaceuticals as antifoulants: Concept and principles, Biofouling, 19 (2003) 207-212. 18 Kwong T F N, Miao L, Li X & Qian P Y, Novel Antifouling and Antimicrobial Compound from a Marine-Derived Fungus Ampelomyces sp., Mar...

Understanding the Relative Contributions of and Critical Enzymes for the Three Pathways for Intracrine Metabolism of Testicular Androgens in Advanced Prostate Cancer

Science.gov (United States)

2017-10-01

Peroxisomal Enzymes: Cytisine-linked Isoflavonoids as Inhibitors of Hydroxysteroid 17-beta-dehydrogenase-4 (HSD17B4) Journal: Org Biomol Chem Volume...J. Chem. 2010, 88, 1233–1239; c) R. A. Valiulin, T. M. Arisco, A. G. Kutateladze, J. Org . Chem. 2011, 76, 1319–1332; d) P. J. Cremins, S. T...Saengchantara, T. W. Wallace, Tetrahedron 1987, 43, 3075–3082; e) R. P. Hsung, J. Org . Chem. 1997, 62, 7904–7905. [11] a) M. Von Strandtmann, M. P. Cohen, J

The investigation of platonic solids symmetry operations with clifford algebra

International Nuclear Information System (INIS)

Kilic, A.

2005-01-01

The geometric algebra produces the new fields of view in the modern mathematical physics, definition of bodies and rearranging for equations of mathematics and physics. The new mathematical approaches play an important role in the progress of physics. After presenting Clifford algebra and quarantine's, the symmetry operations with Clifford algebra and quarantine's are defined. This symmetry operations are applied to a Platonic solids, which are called as tetrahedron, cube, octahedron, icosahedron and dodecahedron. Also, the vertices of Platonic solids presented in the Cartesian coordinates are calculated

Randomly Generating Four Mixed Bell-Diagonal States with a Concurrences Sum to Unity

International Nuclear Information System (INIS)

Toh, S. P.; Zainuddin Hishamuddin; Foo Kim Eng

2012-01-01

A two-qubit system in quantum information theory is the simplest bipartite quantum system and its concurrence for pure and mixed states is well known. As a subset of two-qubit systems, Bell-diagonal states can be depicted by a very simple geometrical representation of a tetrahedron with sides of length 2√2. Based on this geometric representation, we propose a simple approach to randomly generate four mixed Bell decomposable states in which the sum of their concurrence is equal to one. (general)

MetaRep, an extended CMAS 3D program to visualize mafic (CMAS, ACF-S, ACF-N) and pelitic (AFM-K, AFM-S, AKF-S) projections

Science.gov (United States)

France, Lydéric; Nicollet, Christian

2010-06-01

MetaRep is a program based on our earlier program CMAS 3D. It is developed in MATLAB ® script. MetaRep objectives are to visualize and project major element compositions of mafic and pelitic rocks and their minerals in the pseudo-quaternary projections of the ACF-S, ACF-N, CMAS, AFM-K, AFM-S and AKF-S systems. These six systems are commonly used to describe metamorphic mineral assemblages and magmatic evolutions. Each system, made of four apices, can be represented in a tetrahedron that can be visualized in three dimensions with MetaRep; the four tetrahedron apices represent oxides or combination of oxides that define the composition of the projected rock or mineral. The three-dimensional representation allows one to obtain a better understanding of the topology of the relationships between the rocks and minerals and relations. From these systems, MetaRep can also project data in ternary plots (for example, the ACF, AFM and AKF ternary projections can be generated). A functional interface makes it easy to use and does not require any knowledge of MATLAB ® programming. To facilitate the use, MetaRep loads, from the main interface, data compiled in a Microsoft Excel ™ spreadsheet. Although useful for scientific research, the program is also a powerful tool for teaching. We propose an application example that, by using two combined systems (ACF-S and ACF-N), provides strong confirmation in the petrological interpretation.

Dehydration of a layered double hydroxide-C2AH8

International Nuclear Information System (INIS)

Ukrainczyk, N.; Matusinovic, T.; Kurajica, S.; Zimmermann, B.; Sipusic, J.

2007-01-01

Thermal dehydration of dicalcium aluminate hydrate, C 2 AH 8 , has been investigated by simultaneous differential thermal and thermo gravimetric analysis (DTA/TGA), powder X-ray diffraction (XRD), temperature-dependent infrared spectroscopy (FT-IR), and BET method of surface area measurement. The temperature-dependent infrared measurements were studied by two-dimensional infrared (2D-IR) correlation spectroscopy. The structure of aluminum-oxide polyhedron, characterized by 27 Al solid state NMR spectrum method and FT-IR, shows tetrahedron and octahedron as the main forms of aluminum-oxide polyhedrons in C 2 AH 8 sample. From the results obtained a variety of structural transformations observed are explained as a consequence of the removal of loosely held interlayer water molecules at lower temperatures, followed by grafting process of the interlayer [Al(OH) 4 ] - anion. Structural model of a grafting process of the interlayer [Al(OH) 4 ] - tetrahedron onto hydroxylated octahedrons of [Ca 2 Al(OH) 6 ] + layers has been proposed in order to explain observed loss of one water molecule, shrinkage of interlayer spacing and qualitative changes of FT-IR spectra. At higher temperatures the dehydroxylation of the lattice and decomposition of the interlayer species occurs, yielding amorphous material that crystallizes into C 3 A and C 12 A 7 at 885 deg. C. Those findings provide improvement in the interpretation of thermo-analytical results of calcium aluminate cements (CAC) hydration products, and better understanding of CAC conversion process

Helicity and potential vorticity in the surface boundary layer turbulence

Science.gov (United States)

Chkhetiani, Otto; Kurgansky, Michael; Koprov, Boris; Koprov, Victor

2016-04-01

An experimental measurement of all three components of the velocity and vorticity vectors, as well as the temperature and its gradient, and potential vorticity, has been developed using four acoustic anemometers. Anemometers were placed at vertices of a tetrahedron, the horizontal base of which was a rectangular triangle with equal legs, and the upper point was exactly above the top of the right angle. The distance from the surface to the tetrahedron its base was 5.5 m, and the lengths of legs and a vertical edge were 5 m. The measurements were carried out of total duration near 100 hours both in stable and unstable stratification conditions (at the Tsimlyansk Scientific Station in a uniform area of virgin steppe 700 x 650 m, August 2012). A covariance-correlation matrix for turbulent variations in all measured values has been calculated. In the daytime horizontal and vertical components of the helicity are of the order of -0.03 and +0.01 m s-2, respectively. The nighttime signs remain unchanged, but the absolute values are several times smaller. It is confirmed also by statistics of a relative helicity. The cospectra and spectral correlation coefficients have been calculated for all helicity components. The time variations in the components of "instantaneous" relative helicity and potential vorticity are considered. Connections of helicity with Monin-Obukhov length and the wind vertical profile structure are discussed. This work was supported by the Russian Science Foundation (Project No 14-27-00134).

Spontaneous polarization and pyroelectric effect in improper ferroelectrics-ferroelastics Gd2(MoO4)3 and Tb2(MoO4)3 at low temperature

International Nuclear Information System (INIS)

Matyjasik, S; Shaldin, Yu.V.

2013-01-01

Experimental dependencies for spontaneous polarization ΔP s (T) and pyroelectric coefficient γ s (T)for Gd 2 (MoO 4 ) 3 (GMO) and Tb 2 (MoO 4 ) 3 (TMO) reported here differs from those for intrinsic ferroelectrics. We found fundamental distinction in GMO and TMO samples behavior at their repolarization at the fixed temperatures 300 and 4.2 K. In TMO monodomainization temperature does not affect experimental data, while in GMO monodomainization at 4.2 K results in increase of ΔP s (T) by order of magnitude at 85 K and γ s (T) dependence shows well-defined anomalies, reaching a record magnitude of 3 centre dot 10 -4 C/(m 2 centre dot K) at T = 25 K. At T = 200 K the pyroelectric coefficients values are -1.45 centre dot 10 -6 C/(m 2 centre dot K) and-1.8 centre dot 10 -6 C/(m 2 centre dot K). Taking into account our data, results related to transformation of structure in (001) plane and symmetry reasons we suggested crystallographic model of GMO type improper ferroelectric. It is formed by four meso-tetrahedrons constructed of three coordination tetrahedrons MO 4 (a, b and c types). In the framework of this model we discuss the physical meaning of pseudodeviator Q 12 *, coefficient, that initiate the phase transition at T > 433 K from noncentrosymmetric phase (mm2) to another one (4-bar2m).

The Biochemistry Tetrahedron and the Development of the Taxonomy of Biochemistry External Representations (TOBER)

Science.gov (United States)

Towns, Marcy H.; Raker, Jeffrey R.; Becker, Nicole; Harle, Marissa; Sutcliffe, Jonathan

2012-01-01

Visual literacy, the ability to interpret and create external representations (ERs), is essential to success in biochemistry. Studies have been conducted that describe students' abilities to use and interpret specific types of ERs. However, a framework for describing ERs derived through a naturalistic inquiry of biochemistry classrooms has not…

Critical Analysis of Nitramine Decomposition Data: Product Distributions from HMX and RDX Decomposition

Science.gov (United States)

1985-06-01

12. It was stated that analysis of the gaseous products showed that they consisted of N2O, NO, N2, CO, CO2, F^CO and traces of N,* The products of...IR, UV and mass spectrometry. These were (yields summarized in Table 1) as follows: No 1 N2O, NO, CO2, CO, HCN, CH2O, and I^O. NO2 and a trace ...Ramirez, "Reaction of Gem-Nitronitroso Compounds with Triethyl Phosphite ," Tetrahedron, Vol. 29, p. 4195, 1973. J. Jappy and P.N. Preston

Studies of the fluorescent excited state of impurities in ionic crystals

International Nuclear Information System (INIS)

Romestain, Robert

1972-01-01

The author of this research thesis first presents experimental methods used in this research: principles (recall on the optical spectrum of an impurity in a solid, use of fluorescence polarization) and techniques (sample preparation, liquid helium cryostat, application of a disturbance, optical detection). Then, he reports the study of the Mn ++ ion in a tetrahedron crystalline field, the study of the Jahn Teller effect on the excited state of the F + centre in CaO, and the study by double resonance of a specific excited state of this same centre in CaO

A high volume cost efficient production macrostructuring process. [for silicon solar cell surface treatment

Science.gov (United States)

Chitre, S. R.

1978-01-01

The paper presents an experimentally developed surface macro-structuring process suitable for high volume production of silicon solar cells. The process lends itself easily to automation for high throughput to meet low-cost solar array goals. The tetrahedron structure observed is 0.5 - 12 micron high. The surface has minimal pitting with virtually no or very few undeveloped areas across the surface. This process has been developed for (100) oriented as cut silicon. Chemi-etched, hydrophobic and lapped surfaces were successfully texturized. A cost analysis as per Samics is presented.

Matrix-controlled morphology evolution of Te inclusions in CdZnTe single crystal

International Nuclear Information System (INIS)

He, Yihui; Jie, Wanqi; Xu, Yadong; Wang, Tao; Zha, Gangqiang; Yu, Pengfei; Zheng, Xin; Zhou, Yan; Liu, Hang

2012-01-01

The fine morphologies of microscale Te inclusions in CdZnTe single crystal were investigated to reveal their shape evolution. Such inclusions from crystal ingots with different post-growth cooling rates were analyzed using scanning electron microscopy after surface treatment. A tetrakaidecahedron model embodying {1 0 0} and {1 1 1} matrix facets was developed to interpret the form of the Te inclusions. An entire shape evolution process was also proposed where the final configuration of the Te inclusions was a tetrahedron comprising {1 1 1}B facets.

Aromaticine, a sesquiterpene lactone from Amblyopappus pusillus

Directory of Open Access Journals (Sweden)

Matías López-Rodríguez

2008-02-01

Full Text Available Aromaticine (systematic name: 4a,8-dimethyl-3-methylene-3,3a,4,4a,7a,8,9,9a-octahydroazuleno[6,5-b]furan-2,5-dione, C15H18O3, is a natural lactone isolated from Amblyopappus pusillus. The molecular structure and conformation agree with the results of Romo, Joseph-Nathan & Díaz [(1964. Tetrahedron, 20, 79–85]. The fused-ring system contains a seven-membered ring in a twist-boat conformation and two five-membered rings trans fused in envelope conformations.

Inferring biological tasks using Pareto analysis of high-dimensional data.

Science.gov (United States)

Hart, Yuval; Sheftel, Hila; Hausser, Jean; Szekely, Pablo; Ben-Moshe, Noa Bossel; Korem, Yael; Tendler, Avichai; Mayo, Avraham E; Alon, Uri

2015-03-01

We present the Pareto task inference method (ParTI; http://www.weizmann.ac.il/mcb/UriAlon/download/ParTI) for inferring biological tasks from high-dimensional biological data. Data are described as a polytope, and features maximally enriched closest to the vertices (or archetypes) allow identification of the tasks the vertices represent. We demonstrate that human breast tumors and mouse tissues are well described by tetrahedrons in gene expression space, with specific tumor types and biological functions enriched at each of the vertices, suggesting four key tasks.

Visualization of 2-D and 3-D fields from its value in a finite number of points

International Nuclear Information System (INIS)

Dari, E.A.; Venere, M.J.

1990-01-01

This work describes a method for the visualization of two- and three-dimensional fields, given its value in a finite number of points. These data can be originated in experimental measurements, numerical results, or any other source. For the field interpolation, the space is divided into simplices (triangles or tetrahedrons), using the Watson algorithm to obtain the Delaunay triangulation. Inside each simplex, linear interpolation is assumed. The visualization is accomplished by means of Finite Elements post-processors, capable of handling unstructured meshes, which were also developed by the authors. (Author) [es

Acid-Catalyzed Degradation of Poly(2-butyl-1,3,6-trioxocane.

Science.gov (United States)

1985-10-21

case, n = 8, was not studied. The detailed investigation of ring formation by Illuminati and his coworkers 1 1 󈧐 show that formation of 8-membered... Illuminati et al. have evaluated the oxygen effect in eq. 8 by studying the effect of replacing X = CH2 with X= 0. a o- (CCHn 2Br B 8 0 X-(CH )-Br .(H) +B...Macrosol. 16, 21 1000. 10. S. Winsten, E. Allred, R. Heck and R. Olick, Tetrahedron, 10. 3, 1. 29 11. G. Illuminati and L. Mandolini, Acct Ce 14, 95. 12

Letters in the Forest: Global precedence effect disappears for letters but not for non-letters under reading-like conditions

Directory of Open Access Journals (Sweden)

Thomas eLachmann

2014-07-01

Full Text Available Normally-skilled reading involves special processing strategies for letters, which are habitually funneled into an abstract letter code. On the basis of previous studies we argue that this habit leads to the preferred usage of an analytic strategy for the processing of letters, while non-letters are preferably processed via a holistic strategy. The well-known Global Precedence Effect (GPE seems to contradict to this assumption, since, with compound, hierarchical figures, including letter items, faster responses are observed to the global than to the local level of the figure, as well as an asymmetric interference effect from global to local level. We argue that with letters these effects depend on presentation conditions; only when they elicit the processing strategies automatized for reading, an analytic strategy for letters in contrast to non-letters is to be expected. We compared the GPE for letters and non-letters in central viewing, with the global stimulus size close to the functional visual field in whole word reading (6.5o of visual angle and local stimuli close to the critical size for fluent reading of individual letters (.5o of visual angle. Under these conditions, the GPE remained robust for non-letters. For letters, however, it disappeared: letters showed no overall response time advantage for the global level and symmetric congruence effects (local-to-global as well as global-to local interference. We interpret these results as according to the view that reading is based on resident analytic visual processing strategies for letters.

Sublatitudinal Isotope Heterogeneity of The Atlantic and Adjacent Continents: A Relation To The Litospheric Plates and Superplums

Science.gov (United States)

Mironov, Yu. V.; Ryakhovsky, V. M.; Pustovoy, A. A.; Lapidus, I. V.

Four Sr-Nd-Pb isotope sublatitudinal provinces are chosen in the Atlantic and on ad- jacent continents. They include mid-ocean ridges, oceanic rises and islands, as well as Late Mesozoic - Cenozoic continental rifts and traps. A modified Zindler-Hart "man- tle tetrahedron" (1986) have been used for rock systematics. Its major classification element alongside with known end-members (DM, HIMU, EM1, EM2) is any in- tratetrahedron component F ("focal") (Mironov et al., 2000; Rundquist et al., 2000; Ryakhovsky, 2000). It represents average characteristic of all known intratetrahedron components (FOZO, C, PREMA etc.), updated by methods of multidimensional statis- tics. Northern province includes Mid-Atlantic Ridge from a southern part of Reykjanes ridge up to 24S, numerous islands and rises, located at the same latitudes, Cameroon Line, African and European rifts, Aden and Red sea spreading centres, and also Co- mores in Indian ocean. The main composition dispersion of volcanics from withinplate oceanic and continental structures is determined by mixture of F and HIMU (rarely with admixture EM2). MORB within this area are characterized by stable admixture HIMU. Similar composition have the rocks in Bouvet-Antarctic province, within the limits of which the rises Spiss and Shona, the most southern part of Mid-Atlantic ridge, island Bouvet, an adjacent part of Southwest-Indian Ridge, and also traps and rifts on northern coast of Antarctic Continent are located. The Southern province lies in outlines of known Southern hemisphere DUPAL-anomaly (Hart, 1984). The with- inplate oceanic rocks (Gough, Tristan-da-Kunha, Walvis ridge, Rio Grande Plateau, Discovery) correspond to a mixture F + EM1 (sometimes F + EM1 + EM2) and are similar with traps of Southern America and Africa. Further to east this province is traced on islands and mid-ocean ridges in Indian ocean. MORB of Southern Atlantic and Indian ocean are enriched EM1. The Arctic province includes spreading ridges of

Four-Spacecraft Magnetic Curvature and Vorticity Analyses on Kelvin-Helmholtz Waves in MHD Simulations

Science.gov (United States)

Kieokaew, Rungployphan; Foullon, Claire; Lavraud, Benoit

2018-01-01

Four-spacecraft missions are probing the Earth's magnetospheric environment with high potential for revealing spatial and temporal scales of a variety of in situ phenomena. The techniques allowed by these four spacecraft include the calculation of vorticity and the magnetic curvature analysis (MCA), both of which have been used in the study of various plasma structures. Motivated by curved magnetic field and vortical structures induced by Kelvin- Helmholtz (KH) waves, we investigate the robustness of the MCA and vorticity techniques when increasing (regular) tetrahedron sizes, to interpret real data. Here for the first time, we test both techniques on a 2.5-D MHD simulation of KH waves at the magnetopause. We investigate, in particular, the curvature and flow vorticity across KH vortices and produce time series for static spacecraft in the boundary layers. The combined results of magnetic curvature and vorticity further help us to understand the development of KH waves. In particular, first, in the trailing edge, the magnetic curvature across the magnetopause points in opposite directions, in the wave propagation direction on the magnetosheath side and against it on the magnetospheric side. Second, the existence of a "turnover layer" in the magnetospheric side, defined by negative vorticity for the duskside magnetopause, which persists in the saturation phase, is reminiscent of roll-up history. We found significant variations in the MCA measures depending on the size of the tetrahedron. This study lends support for cross-scale observations to better understand the nature of curvature and its role in plasma phenomena.

Mechanism of Properties of Noble ZnS-SiO2 Protection Layer for Phase Change Optical Disk Media

Science.gov (United States)

Tsu, David V.; Ohta, Takeo

2006-08-01

A ZnS-SiO2 composite dielectric is widely used in the optical stack designs of rewritable optical recording media as an index-matching medium and as a protection layer for the high-index chalcogenide (compound with sixth group element of S, Se, Te) phase change material used in these media. The addition of Si and O to ZnS is primarily intended to stabilize against crystalline grain growth of ZnS with high numbers of direct overwriting cycles. In this study, we carry out infrared (IR) spectroscopy to clarify the role of Si in this stabilization process. IR spectroscopy is performed on sputter as-deposited and annealed ZnS-SiO2 dielectric protection layers. We find that Si exists not in the SiO2 oxide phase but as [SiS4-nOn] tetrahedrons. Moreover, zinc and sulfur do not exist as ZnS, but in highly chemically disordered ZnS:O crystallites. The highly directional and rigid covalent bonds in the [SiS4-nOn] tetrahedrons are key to establishing thermal stability against the coalescence of ZnS. The importance of the Si-S bond also extends into a more thorough understanding of the low thermal conductivity of the ZnS-SiO2 material. The consideration of elastic implications allows us to predict an average phonon velocity less than 50% compared to that in SiO2. With this, we predict a thermal conductivity of 0.0067 W cm-1 K-1 for this material, which is in complete agreement with measured values.

A new algorithm for finite element simulation of wedge osteotomies in voxel models with application to the tibia

Directory of Open Access Journals (Sweden)

Thomas Pressel

2010-01-01

Full Text Available Thomas Pressel1, Markus D Schofer1, Jörg Meiforth2, Markus Lengsfeld1, Jan Schmitt11Department of Orthopaedics and Rheumatology, University Hospital Marburg, Marburg, Germany; 2St. Vincentius Kliniken, Klinik für Orthopädie, Karlsruhe, GermanyAbstract: Wedge osteotomies are used to correct bone deformities or change the forces acting on bones and joints in the human body. Finite element models can be employed to simulate the effect of such operations on the bone or adjacent joints. The automatic generation of voxel models derived from computed tomography data is a common procedure, but the major drawback of the method lies in irregular model surfaces. Therefore, the concept of hybrid models combining voxel and tetrahedron meshes was developed. We present an algorithm to simulate wedge osteotomies in voxel models by adding tetrahedron to brick elements. Applicability of the procedure was tested by performing a parametric study using a tibia model created from computed tomography scans taken in vivo applying individually calculated force conditions. The osteotomy angle largely affected maximum stresses: at 2.5 degrees valgus, the stresses at the medial and lateral tibial plateau were equivalent, while increasing valgus angles reduced medial stresses. The algorithm described here is an improvement of former mesh generation procedures and allows a better representation of the geometry at the osteotomy level. The algorithm can be used for all wedge osteotomies and is not limited to the tibia.Keywords: finite element/osteotomy/voxel/pre-operative planning, simulation, mesh algorithm

Structured printed referral letter (form letter; saves time and improves communication

Directory of Open Access Journals (Sweden)

R.P.J.C. Ramanayake

2013-01-01

Full Text Available Referral of patients to hospitals, specialists and other institutions is an essential part of primary health care. Patients are referred to specialists when investigation or therapeutic options are exhausted in primary care or when opinion or advice is needed from them. Referral has considerable implications for patients, health care system and health care costs. Good communication between primary and secondary care is essential for the smooth running of any health care system. Referral and reply letters are the sole means of communication between doctors most of the time and breakdown in communication could lead to poor continuity of care, delayed diagnoses, polypharmacy, increased litigation risk and unnecessary testing. A referral letter also helps to avoid patient dissatisfaction and loss of confidence in family physician. Studies of referral letters have reported that specialists are dissatisfied with their quality and content. Inclusion of letter writing skills in the medical curriculum, peer assessment and feedback have shown to improve the quality of referral letters. . Form letters have shown to enhance information content and communication in referral process. In Sri Lanka referral letters are usually hand written and frequent complaints are that these letters do not contain adequate information and retrieval of information is a problem due to poor legibility and clarity. Sometimes Primary care doctors refer patients to hospitals and specialists with only verbal instructions. To address these short comings this form letter was introduced. Based on the guidelines and systematic review of published articles, items of information to be included were decided. Printed forms of the letter are kept in the practice and the doctor has to just fill up relevant information under each heading. The objectives of introducing this structured referral letter was to improve the quality and standard of referral letters and save time for both general

ALI (Autonomous Lunar Investigator): Revolutionary Approach to Exploring the Moon with Addressable Reconfigurable Technology

Science.gov (United States)

Clark, P. E.; Curtis, S. A.; Rilee, M. L.; Floyd, S. R.

2005-01-01

Addressable Reconfigurable Technology (ART) based structures: Mission Concepts based on Addressable Reconfigurable Technology (ART), originally studied for future ANTS (Autonomous Nanotechnology Swarm) Space Architectures, are now being developed as rovers for nearer term use in lunar and planetary surface exploration. The architecture is based on the reconfigurable tetrahedron as a building block. Tetrahedra are combined to form space-filling networks, shaped for the required function. Basic structural components are highly modular, addressable arrays of robust nodes (tetrahedral apices) from which highly reconfigurable struts (tetrahedral edges), acting as supports or tethers, are efficiently reversibly deployed/stowed, transforming and reshaping the structures as required.

In situ transmission electron microscopy of individual carbon nanotetrahedron/ribbon structures in bending

Energy Technology Data Exchange (ETDEWEB)

Kohno, Hideo, E-mail: kohno.hideo@kochi-tech.ac.jp [School of Environmental Science and Engineering, Kochi University of Technology, Kami, Kochi 782-8502 (Japan); Masuda, Yusuke [Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

2015-05-11

When the direction of flattening of a carbon nanotube changes during growth mediated by a metal nanoparticle, a carbon nanotetrahedron is formed in the middle of the carbon nanoribbon. We report the bending properties of the carbon nanotetrahedron/nanoribbon structure using a micro-manipulator system in a transmission electron microscope. In many cases, bending occurs at an edge of the carbon nanotetrahedron. No significant change is observed in the tetrahedron's shape during bending, and the bending is reversible and repeatable. Our results show that the carbon nanotetrahedron/nanoribbon structure has good durability against mechanical bending.

Properties and structure of high erbium doped phosphate glass for short optical fibers amplifiers

International Nuclear Information System (INIS)

Seneschal, Karine; Smektala, Frederic; Bureau, Bruno; Floch, Marie Le; Jiang Shibin; Luo, Tao; Lucas, Jacques; Peyghambarian, Nasser

2005-01-01

New phosphate glasses have been developed in order to incorporate high rare-earth ions concentrations. These glasses present a great chemical stability and a high optical quality. The phosphate glass network is open, very flexible, with a linkage of the tetrahedrons very disordered and contains a larger number of non-bridging oxygens (66%). The great stability and resistance against crystallization associated with the possibility to incorporate high doping concentration of rare-earth ions in these phosphate glasses make them very good candidates for the realization of ultra short single mode amplifiers with a high gain at 1.55 μm

A first-principles study of short range order in Cu-Zn

International Nuclear Information System (INIS)

Slutter, M.; Turchi, P.E.A.; Johnson, D.D.; Nicholson, D.M.; Stocks, G.M.; Pinski, F.J.

1990-01-01

Recently, measurements of short-range order (SRO) diffuse neutron scattering intensity have been performed on quenched Cu-Zn alloys with 22.4 to 31.1 atomic percent (a/o) Zn, and pair interactions were obtained by inverse Monte Carlo simulation. These results are compared to SRO intensities and effective pair interactions obtained from first-principles electronic structure calculations. The theoretical SRO intensities were calculated with the cluster variation method (CVM) in the tetrahedron-octahedron approximation with first-principles pain interactions as input. More generally, phase stability in the Cu-Zn alloy system is discussed, using ab-initio energetic properties

Data structures and languages in support of parallel image processing for astronomy

International Nuclear Information System (INIS)

Tanimoto, S.L.

1985-01-01

This paper discusses data structures, and aspects of programming languages and systems that are relevant to image processing of astronomy data. Emphasis is on image processing computations, because this kind of data processing is obviously a ripe one for parallelism and is important in astronomy. However, some discussion of general possibilities are also presented. The role of algorithms is examined since they are not dependent on a particular language. As an implementation of an algorithm a program is equally tied to data structure, operations, architecture and language, and therefore the issue of programming resides in the center of the tetrahedron

An h-adaptive finite element solver for the calculations of the electronic structures

International Nuclear Information System (INIS)

Bao Gang; Hu Guanghui; Liu Di

2012-01-01

In this paper, a framework of using h-adaptive finite element method for the Kohn–Sham equation on the tetrahedron mesh is presented. The Kohn–Sham equation is discretized by the finite element method, and the h-adaptive technique is adopted to optimize the accuracy and the efficiency of the algorithm. The locally optimal block preconditioned conjugate gradient method is employed for solving the generalized eigenvalue problem, and an algebraic multigrid preconditioner is used to accelerate the solver. A variety of numerical experiments demonstrate the effectiveness of our algorithm for both the all-electron and the pseudo-potential calculations.

Integrability in three dimensions: Algebraic Bethe ansatz for anyonic models

Directory of Open Access Journals (Sweden)

Sh. Khachatryan

2015-10-01

Full Text Available We extend basic properties of two dimensional integrable models within the Algebraic Bethe Ansatz approach to 2+1 dimensions and formulate the sufficient conditions for the commutativity of transfer matrices of different spectral parameters, in analogy with Yang–Baxter or tetrahedron equations. The basic ingredient of our models is the R-matrix, which describes the scattering of a pair of particles over another pair of particles, the quark-anti-quark (meson scattering on another quark-anti-quark state. We show that the Kitaev model belongs to this class of models and its R-matrix fulfills well-defined equations for integrability.

Monte Carlo Simulations of Phosphate Polyhedron Connectivity in Glasses

Energy Technology Data Exchange (ETDEWEB)

ALAM,TODD M.

1999-12-21

Monte Carlo simulations of phosphate tetrahedron connectivity distributions in alkali and alkaline earth phosphate glasses are reported. By utilizing a discrete bond model, the distribution of next-nearest neighbor connectivities between phosphate polyhedron for random, alternating and clustering bonding scenarios was evaluated as a function of the relative bond energy difference. The simulated distributions are compared to experimentally observed connectivities reported for solid-state two-dimensional exchange and double-quantum NMR experiments of phosphate glasses. These Monte Carlo simulations demonstrate that the polyhedron connectivity is best described by a random distribution in lithium phosphate and calcium phosphate glasses.

On the computation of the demagnetization tensor field for an arbitrary particle shape using a Fourier space approach

International Nuclear Information System (INIS)

Beleggia, M.; Graef, M. de

2003-01-01

A method is presented to compute the demagnetization tensor field for uniformly magnetized particles of arbitrary shape. By means of a Fourier space approach it is possible to compute analytically the Fourier representation of the demagnetization tensor field for a given shape. Then, specifying the direction of the uniform magnetization, the demagnetizing field and the magnetostatic energy associated with the particle can be evaluated. In some particular cases, the real space representation is computable analytically. In general, a numerical inverse fast Fourier transform is required to perform the inversion. As an example, the demagnetization tensor field for the tetrahedron will be given

Role of PO4 tetrahedron in LiFePO4 and FePO4 system.

Science.gov (United States)

Zeng, Yuewu

2015-06-01

Using high resolution transmission electron microscopy with image simulation and Fourier analysis, the Li1- x FePO4 (x < 0.01), Li1- x FePO4 (x ∼ 0.5), and FePO4 particles, prepared by charging or discharging the 053048 electrochemical cells (thickness: 5 mm, width: 30 mm, height: 48 mm) and dismantled inside an Ar-filled dry box, were investigated. The high resolution images reveal: (1) the solid solution of Li1- x FePO4 (x < 0.01) contains some missing Li ions leading PO4 group distorted around M1 tunnel of the unit cell; (2) the texture of the particles of Li1- x FePO4 (x ∼0.5) has homogeneously distributed compositional domains of LiFePO4 and FePO4 resulting from spinodal decomposition which promote Li ion easily getting into the particle due to uphill diffusion, (3) the particles of FePO4 formed in charging have heavily distorted lattice and contain some isolated LiFePO4 , (4) interface between LiFePO4 and FePO4 and between amorphous and crystal region provides the lattice distortion of small polarons. © 2015 Wiley Periodicals, Inc.

Letter and symbol identification: No evidence for letter-specific crowding mechanisms.

Science.gov (United States)

Castet, Eric; Descamps, Marine; Denis-Noël, Ambre; Colé, Pascale

2017-09-01

It has been proposed that letters, as opposed to symbols, trigger specialized crowding processes, boosting identification of the first and last letters of words. This hypothesis is based on evidence that single-letter accuracy as a function of within-string position has a W shape (the classic serial position function [SPF] in psycholinguistics) whereas an inverted V shape is obtained when measured with symbols. Our main goal was to test the robustness of the latter result. Our hypothesis was that any letter/symbol difference might result from short-term visual memory processes (due to the partial report [PR] procedures used in SPF studies) rather than from crowding. We therefore removed the involvement of short-term memory by precueing target-item position and compared SPFs with precueing and postcueing. Perimetric complexity was stringently matched between letters and symbols. In postcueing conditions similar to previous studies, we did not reproduce the inverted V shape for symbols: Clear-cut W shapes were observed with an overall smaller accuracy for symbols compared to letters. This letter/symbol difference was dramatically reduced in precueing conditions in keeping with our prediction. Our results are not consistent with the claim that letter strings trigger specialized crowding processes. We argue that PR procedures are not fit to isolate crowding processes.

The effect of letter string length and report condition on letter recognition accuracy.

Science.gov (United States)

Raghunandan, Avesh; Karmazinaite, Berta; Rossow, Andrea S

Letter sequence recognition accuracy has been postulated to be limited primarily by low-level visual factors. The influence of high level factors such as visual memory (load and decay) has been largely overlooked. This study provides insight into the role of these factors by investigating the interaction between letter sequence recognition accuracy, letter string length and report condition. Letter sequence recognition accuracy for trigrams and pentagrams were measured in 10 adult subjects for two report conditions. In the complete report condition subjects reported all 3 or all 5 letters comprising trigrams and pentagrams, respectively. In the partial report condition, subjects reported only a single letter in the trigram or pentagram. Letters were presented for 100ms and rendered in high contrast, using black lowercase Courier font that subtended 0.4° at the fixation distance of 0.57m. Letter sequence recognition accuracy was consistently higher for trigrams compared to pentagrams especially for letter positions away from fixation. While partial report increased recognition accuracy in both string length conditions, the effect was larger for pentagrams, and most evident for the final letter positions within trigrams and pentagrams. The effect of partial report on recognition accuracy for the final letter positions increased as eccentricity increased away from fixation, and was independent of the inner/outer position of a letter. Higher-level visual memory functions (memory load and decay) play a role in letter sequence recognition accuracy. There is also suggestion of additional delays imposed on memory encoding by crowded letter elements. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

Letters and Letter Writing in Early Modern Culture: An Introduction

Directory of Open Access Journals (Sweden)

Gabriella Del Lungo Camiciotti

2014-04-01

Full Text Available The recently renewed scholarly interest in historical letters and letter writing has given rise to several studies which explore the culture of epistolarity from different perspectives. The article offers an introduction to recent scholarship on epistolary discourse and practices in early modern culture. Given the importance of letters as data for several types of diachronic investigation, the article focuses on three points that are crucial for an understanding of the relevance of epistolary discourse itself in early modern European culture. Firstly, letters are invaluable data for historical linguistics, to which they provide information for the history of languages, and sociohistorical and sociolinguistic research. A second recent field of investigation considers letters as documents and material items; the results of research in this area have contributed to the reconstruction of official relationships and information exchanges in past cultures and shed light on social interaction. A third, more traditional area of study, deals with the letter as a form that has given rise to many different genres across the centuries, both practical and literary.

Effect of orthographic processes on letter-identity and letter-position encoding in dyslexic children

Directory of Open Access Journals (Sweden)

Caroline eReilhac

2012-05-01

Full Text Available The ability to identify letters and encode their position is a crucial step of the word recognition process. However and despite their word identification problem, the ability of dyslexic children to encode letter-identity and letter-position within strings was not systematically investigated. This study aimed at filling this gap and further explored how letter identity and letter position encoding is modulated by letter context in developmental dyslexia. For this purpose, a letter-string comparison task was administered to French dyslexic children and two chronological-age (CA and reading-age (RA-matched control groups. Children had to judge whether two successively and briefly presented 4-letter-strings were identical or different. Letter-position and letter-identity were manipulated through the transposition (e.g., RTGM vs. RMGT or substitution of two letters (e.g., TSHF vs. TGHD. Non-words, pseudo-words and words were used as stimuli to investigate sub-lexical and lexical effects on letter encoding. Dyslexic children showed both substitution and transposition detection problems relative to CA controls. A substitution advantage over transpositions was only found for words in dyslexic children whereas it extended to pseudo-words in RA controls and to all type of items in CA controls. Letters were better identified in the dyslexic group when belonging to orthographically familiar strings. Letter position encoding was very impaired in dyslexic children who did not show any word context effect in contrast to CA controls. Overall, the current findings point to a strong letter identity and letter position encoding disorder in developmental dyslexia.

Ab initio study of the adsorption of antimony and arsenic on the Si(110) surface

Energy Technology Data Exchange (ETDEWEB)

Huitzil-Tepanecatl, Arely [Postgrado en Fisica Aplicada, Facultad de Ciencias Fisico-Matematicas, BUAP, Apartado Postal 52, Puebla 72000 (Mexico); Cocoletzi, Gregorio H., E-mail: cocoletz@sirio.ifuap.buap.m [Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Km. 107 Carretera Tijuana-Ensenada, Codigo Postal 22860, Apartado Postal 2732 Ensenada, Baja California (Mexico); Centro de Nanociencia y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Apartado Postal 2681, Ensenada, Baja California, 22800 (Mexico); Instituto de Fisica, Universidad Autonoma de Puebla, Apartado Postal J-48, Puebla 72570 (Mexico); Takeuchi, Noboru [Centro de Nanociencia y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Apartado Postal 2681, Ensenada, Baja California, 22800 (Mexico)

2010-10-29

We have performed first principles total energy calculations to investigate the adsorption of Sb and As adatoms on the Si(110) surface using a (2 x 3) supercell. The energetics and atomic structures have been investigated in four atomic configurations. One structure is obtained by placing 1/3 of a monolayer (ML) of Sb (As) atoms on the Si(110) surface. The other three geometries are obtained by depositing 1 ML of Sb (As) atoms on the surface. In the first case the structure is formed by four trimers, in the second case the geometry is formed by zigzag atomic chains and in the third case the structure contains 'microfacets'. The energetics results of the Sb adsorption show that for low coverage the tetrahedrons formed by the adsorption of 1/3 ML is the most stable configuration, while in the monolayer region the zigzag atomic chain is the most stable structure. However, the total energies of the trimer and microfacet structures are slightly higher, indicating that under some conditions, they may be formed. In an experimental report it has been suggested that the adsorption of 1/3 and 1 ML of Sb corresponds to the low and high coverage in the experiments of Zotov et al. [A. V. Zotov, V. G. Lifshifts, and A. N. Demidchik, Surf. Sci. 274, L583 (1992)]. On the other hand, our results of the As adsorption show that for low coverage, the tetrahedrons in the adsorption of 1/3 ML also give the most stable configuration. However, at the 1 ML coverage, a structure formed by microfacets is the most stable structure, in agreement with previous results.

Ab initio study of the adsorption of antimony and arsenic on the Si(110) surface

International Nuclear Information System (INIS)

Huitzil-Tepanecatl, Arely; Cocoletzi, Gregorio H.; Takeuchi, Noboru

2010-01-01

We have performed first principles total energy calculations to investigate the adsorption of Sb and As adatoms on the Si(110) surface using a (2 x 3) supercell. The energetics and atomic structures have been investigated in four atomic configurations. One structure is obtained by placing 1/3 of a monolayer (ML) of Sb (As) atoms on the Si(110) surface. The other three geometries are obtained by depositing 1 ML of Sb (As) atoms on the surface. In the first case the structure is formed by four trimers, in the second case the geometry is formed by zigzag atomic chains and in the third case the structure contains 'microfacets'. The energetics results of the Sb adsorption show that for low coverage the tetrahedrons formed by the adsorption of 1/3 ML is the most stable configuration, while in the monolayer region the zigzag atomic chain is the most stable structure. However, the total energies of the trimer and microfacet structures are slightly higher, indicating that under some conditions, they may be formed. In an experimental report it has been suggested that the adsorption of 1/3 and 1 ML of Sb corresponds to the low and high coverage in the experiments of Zotov et al. [A. V. Zotov, V. G. Lifshifts, and A. N. Demidchik, Surf. Sci. 274, L583 (1992)]. On the other hand, our results of the As adsorption show that for low coverage, the tetrahedrons in the adsorption of 1/3 ML also give the most stable configuration. However, at the 1 ML coverage, a structure formed by microfacets is the most stable structure, in agreement with previous results.

Selective molecular recognition, C-H bond activation, and catalysis in nanoscale reaction vessels

Energy Technology Data Exchange (ETDEWEB)

Fiedler, Dorothea; Leung, Dennis H.; Raymond, Kenneth N.; Bergman, Robert G.

2004-11-27

Supramolecular chemistry represents a way to mimic enzyme reactivity by using specially designed container molecules. We have shown that a chiral self-assembled M{sub 4}L{sub 6} supramolecular tetrahedron can encapsulate a variety of cationic guests, with varying degrees of stereoselectivity. Reactive iridium guests can be encapsulated and the C-H bond activation of aldehydes occurs, with the host cavity controlling the ability of substrates to interact with the metal center based upon size and shape. In addition, the host container can act as a catalyst by itself. By restricting reaction space and preorganizing the substrates into reactive conformations, it accelerates the sigmatropic rearrangement of enammonium cations.

Coordination polymers of scandium sulfate. Crystal structures of (H2Bipy)[Sc(H2O)(SO4)2]2·2H2O and (H2Bipy)[HSO4]2

International Nuclear Information System (INIS)

Petrosyants, S.P.; Ilyukhin, A.B.

2005-01-01

Compounds with general formula Cat x [Sc(H 2 O) z (SO 4 ) y ]·nH 2 O (Cat=NH 4 , H 2 Bipy (Bipy - 4,4'-bipyridine), HEdp (Edp - ethylene dipyridine)) identified on element analysis data and IR spectra are synthesized. X-ray diffraction analysis of (H 2 Bipy)[Sc(H 2 O)(SO 4 ) 2 ] 2 ·2H 2 O shows that in structure of the compound chains of ScO 6 octahedron and SO 4 tetrahedrons are joined in bands by tridentate coordination of sulfate ions. Bands form skeleton in endless emptiness of which there are H 2 Bipy 2+ cations [ru

Design of an Adaptive-Neural Network Attitude Controller of a Satellite using Reaction Wheels

Directory of Open Access Journals (Sweden)

Abbas Ajorkar

2015-04-01

Full Text Available In this paper, an adaptive attitude control algorithm is developed based on neural network for a satellite using four reaction wheels in a tetrahedron configuration. Then, an attitude control based on feedback linearization control has been designed and uncertainties in the moment of inertia matrix and disturbances torque have been considered. In order to eliminate the effect of these uncertainties, a multilayer neural network with back-propagation law is designed. In this structure, the parameters of the moment of inertia matrix and external disturbances are estimated and used in feedback linearization control law. Finally, the performance of the designed attitude controller is investigated by several simulations.

Generalized Momentum Control of the Spin-Stabilized Magnetospheric Multiscale Formation

Science.gov (United States)

Queen, Steven Z.; Shah, Neerav; Benegalrao, Suyog S.; Blackman, Kathie

2015-01-01

The Magnetospheric Multiscale (MMS) mission consists of four identically instrumented, spin-stabilized observatories elliptically orbiting the Earth in a tetrahedron formation. The on-board attitude control system adjusts the angular momentum of the system using a generalized thruster-actuated control system that simultaneously manages precession, nutation and spin. Originally developed using Lyapunov control-theory with rate-feedback, a published algorithm has been augmented to provide a balanced attitude/rate response using a single weighting parameter. This approach overcomes an orientation sign-ambiguity in the existing formulation, and also allows for a smoothly tuned-response applicable to both a compact/agile spacecraft, as well as one with large articulating appendages.

Quaternary reciprocal system Na,K//Cl,Co3,MoO4

International Nuclear Information System (INIS)

Kochkarov, Zh.A.; Gasanaliev, A.M.

2004-01-01

Quaternary reciprocal system Na,K//Cl,Co 3 ,MoO 4 has been investigated for the first time by differential thermal analysis using the methods of projective and differential geometry. A stable (KCl) 2 -Na 2 CO 3 -K 2 CO 3 -K 2 MoO 4 tetrahedron and (NaCl) 2 -(KCl) 2 -Na 2 CO 3 -K 2 MoO 4 -Na 2 MoO 4 pentatope have been revealed in the system. It has been found that four quadruple invariant points are realized in the Na,K//Cl,Co 3 ,MoO 4 system, including one eutectic and three peritectic points [ru

Vibrational modes of deuterium in KD2PO4

International Nuclear Information System (INIS)

Mizoguchi, Kohji; Agui, Akane; Tominaga, Yasunori; Nakai, Yusuke; Ikeda, Susumu.

1993-01-01

In order to study the deuteration effect in hydrogen-bonded compounds such as KH 2 PO 4 , hydrogen and deuterium modes in KH 2 PO 4 and K(D x H 1-x ) 2 PO 4 (x = 95 %) were investigated by means of inelastic neutron-scattering measurements over a wide energy range. By comparing Raman spectra of KH 2 PO 4 and KD 2 PO 4 with neutron-scattering spectra, the vibrational modes of deuterium and those of PO 4 tetrahedrons in the energy range of 30 < ε < 150 meV have been investigated. At least two deuterium modes have been found at 87 meV and 106 meV. (author)

Propagator with positive cosmological constant in the 3D Euclidean quantum gravity toy model

International Nuclear Information System (INIS)

Bunting, William E; Rovelli, Carlo

2014-01-01

We study the propagator on a single tetrahedron in a three-dimensional toy model of quantum gravity with positive cosmological constant. The cosmological constant is included in the model via q-deformation of the spatial symmetry algebra, that is, we use the Turaev–Viro amplitude. The expected repulsive effect of dark energy is recovered in numerical and analytic calculations of the propagator at large scales comparable to the infrared cutoff. However, due to the simplicity of the model, we do not obtain the exact Newton limit of the propagator. This is a first step toward the similar calculation in the full 3+1 dimensional theory with larger numbers of simplicies. (paper)

New challenges in grid generation and adaptivity for scientific computing

CERN Document Server

Formaggia, Luca

2015-01-01

This volume collects selected contributions from the “Fourth Tetrahedron Workshop on Grid Generation for Numerical Computations”, which was held in Verbania, Italy in July 2013. The previous editions of this Workshop were hosted by the Weierstrass Institute in Berlin (2005), by INRIA Rocquencourt in Paris (2007), and by Swansea University (2010). This book covers different, though related, aspects of the field: the generation of quality grids for complex three-dimensional geometries; parallel mesh generation algorithms; mesh adaptation, including both theoretical and implementation aspects; grid generation and adaptation on surfaces – all with an interesting mix of numerical analysis, computer science and strongly application-oriented problems.

Crystal structure of polyphosphates NaCd(PO3)3 and NaMn(PO3)3

International Nuclear Information System (INIS)

Murashova, E.V.; Chudinova, N.N.

1997-01-01

Crystal structure of NaCd(PO 3 ) 3 (1) and NaMn(PO 3 ) 3 (2) isostructural polyphosphates was determined for twin samples. Rhombic lattice parameters of (1): a = 14.678, b = 14.669, c = 14.705 A, sp. gr. P2 1 2 1 2 1 , Z = 16. The structure of compounds is of frame type. Polyphosphate chain with repetition period of 24 PO 4 tetrahedrons contacts with NaO 6 and M 2 O 6 octahedrons by means of common oxygen vertices. Similarities and differences in structure of mentioned polyphosphates and earlier analyzed NaMg(PO 3 ) 3 polyphosphate are noted [ru

Hydrothermal synthesis and crystal structure of CsFe23(HPO4)2(PO4)(H2O)

International Nuclear Information System (INIS)

Anisimova, N.Yu.; Ilyukhin, A.B.; Chudinova, N.N.; Serafin, M.

2001-01-01

The double acid iron-cesium orthophosphate CsFe 2 3 (HPO 4 ) 2 (PO 4 )(H 2 O) was prepared by hydrothermal synthesis (from the Fe 2 O 3 , Cs 2 CO 3 and H 3 PO 4 mixture at 290 Deg C during 1 h following by cooling to 25 Deg C). Its crystal structure (a = 5.021(3), b = 15.80(1), c = 13.646(8), β 94.49(4) Deg, sp. gr. P2 1 /n, Z = 4) was analyzed by X-ray diffraction. The structure is formed by the orthophosphate tetrahedrons and the FeO 6 octahedrons, the water molecule is coordinated by the iron atom [ru

A kinetic-phase transformation near 250 K in potassium tetrachlorozincate

International Nuclear Information System (INIS)

Noiret, I.; Hedoux, A.; Guinet, Y.; Foulon, M.

1993-01-01

Raman-scattering experiments have been performed to study the successive phase transitions of K 2 ZnCl 4 over the temperature range (100/600) K. The spectra provide the temperature dependence of the mode frequencies and linewidths for two different spatial configurations: a(bb) c and c(aa) b. Special emphasis is put upon a new phenomenon observed in the spectra around 250 K in the c * /3 superstructure. Its kinetic character is revealed by complementary DSC measurements carried out over the range (120/300) K. This phenomenon is interpreted as a progressive structural transformation which corresponds to a slow modification of the tetrahedron distortions. (orig.)

Effect of effective mass and spontaneous polarization on photocatalytic activity of wurtzite and zinc-blende ZnS

International Nuclear Information System (INIS)

Dong, Ming; Zhang, Jinfeng; Yu, Jiaguo

2015-01-01

Semiconductor zinc sulphide (ZnS) has two common phases: hexagonal wurtzite and cubic zinc-blende structures. The crystal structures, energy band structures, density of states (DOS), bond populations, and optical properties of wurtzite and zinc-blende ZnS were investigated by the density functional theory of first-principles. The similar band gaps and DOS of wurtzite and zinc-blende ZnS were found and implied the similarities in crystal structures. However, the distortion of ZnS 4 tetrahedron in wurtzite ZnS resulted in the production of spontaneous polarization and internal electric field, which was beneficial for the transfer and separation of photogenerated electrons and holes

H-D exchange on natural aluminosilicates of orthosilicate group

International Nuclear Information System (INIS)

Markevich, S.V.; Kolesnikov, I.M.

1982-01-01

Experimental data are presented on the effect of aluminium ion coordination in the composition of polyhedrons on the capability of polyhedrons to change the reaction rate of H-D exchange (on the example of ethylene). It is shown that at temperature lower 400 deg C the rate of isotopic exchange reaction is low. Experimental results both for irradiated and non-irradiated minerals are presented. The conclusion is made that the increase of aluminosilicates activity under radiation is connected with the presence of (AlO 4 )-tetrahedrons in the system and change of their state. (AlO 5 ) and (AlO 6 )-polyhedrons are not activated with gamma rays

What Do Letter Migration Errors Reveal About Letter Position Coding in Visual Word Recognition?

Science.gov (United States)

Davis, Colin J.; Bowers, Jeffrey S.

2004-01-01

Dividing attention across multiple words occasionally results in misidentifications whereby letters apparently migrate between words. Previous studies have found that letter migrations preserve within-word letter position, which has been interpreted as support for position-specific letter coding. To investigate this issue, the authors used word…

Analysis of reliability of professor recommendation letters based on concordance with self-introduction letter.

Science.gov (United States)

Kim, Sang Hyun

2013-12-01

The purpose of this study was to examine the concordance between a checklist's categories of professor recommendation letters and characteristics of the self-introduction letter. Checklists of professor recommendation letters were analyzed and classified into cognitive, social, and affective domains. Simple correlation was performed to determine whether the characteristics of the checklists were concordant with those of the self-introduction letter. The difference in ratings of the checklists by pass or fail grades was analyzed by independent sample t-test. Logistic regression analysis was performed to determine whether a pass or fail grade was influenced by ratings on the checklists. The Cronbach alpha value of the checklists was 0.854. Initiative, as an affective domain, in the professor's recommendation letter was highly ranked among the six checklist categories. Self-directed learning in the self-introduction letter was influenced by a pass or fail grade by logistic regression analysis (pprofessor recommendation letters and the sum of all characteristics in the self-introduction letter.

Crystal structure refinements of tetragonal (OH,F)-rich spessartine and henritermierite garnets

Energy Technology Data Exchange (ETDEWEB)

Antao, Sytle M.; Cruickshank, Laura A.

2018-01-30

Cubic garnet (space group Ia\\overline 3 d) has the general formulaX₃Y₂Z₃O₁₂, whereX,YandZare cation sites. In the tetragonal garnet (space groupI4₁/acd), the corresponding cation sites areX1 andX2,Y, andZ1 andZ2. In both space groups only theYsite is the same. The crystal chemistry of a tetragonal (OH,F)-rich spessartine sample from Tongbei, near Yunxiao, Fujian Province, China, with composition^X(Mn_2.82Fe^{2+}_{0.14}Ca_0.04)_Σ3^Y{Al_1.95Fe^{3+}_{0.05}}_Σ2^Z[(SiO₄)_2.61(O₄H₄)_0.28(F₄)_0.11]_Σ3(Sps₉₄Alm₅Grs₁) was studied with single-crystal X-ray diffraction and space groupI4₁/acd. The deviation of the unit-cell parameters from cubic symmetry is small [a= 11.64463(1),c= 11.65481 (2) Å,c/a= 1.0009]. Point analyses and back-scattered electron images, obtained by electron-probe microanalysis, indicate a homogeneous composition. TheZ2 site is fully occupied, but theZ1 site contains vacancies. The occupiedZ1 andZ2 sites with Si atoms are surrounded by four O atoms, as in anhydrous cubic garnets. Pairs of split sites are O1 with F11 and O2 with O22. When theZ1 site is vacant, a larger [(O₂H₂)F₂] tetrahedron is formed by two OH and two F anions in the O22 and F11 sites, respectively. This [(O₂

A STUDY ON LEGIBILITY OF LETTERING

Directory of Open Access Journals (Sweden)

Merve ERSAN,

2016-04-01

Full Text Available In the most general sense, lettering is the art of drawing letters, in which the letter forms carry illustrtive features. In this research which is titled "An Analysis on Legibility in Letterings Used in Print Advertisements", letterings used in and specially designed for print ads are analysed and their contribution to the ads are examined. Legibility, which is the fundamental function of writing and typography is examined in the field of lettering that has an illustrative approach. Also, the article puts emphasis on the technique and form’s contribution on content in letterings. Keywords: Lettering, print advertisements, letter design, illustration, legibility.

First-principles simulation of Raman spectra and structural properties of quartz up to 5 GPa

International Nuclear Information System (INIS)

Liu Lei; Lv Chao-Jia; Yi Li; Liu Hong; Du Jian-Guo; Zhuang Chun-Qiang

2015-01-01

The crystal structure and Raman spectra of quartz are calculated by using first-principles method in a pressure range from 0 to 5 GPa. The results show that the lattice constants (a, c, and V) decrease with increasing pressure and the a-axis is more compressible than the c axis. The Si–O bond distance decreases with increasing pressure, which is in contrast to experimental results reported by Hazen et al. [Hazen R M, Finger L W, Hemley R J and Mao H K 1989 Solid State Communications 725 507–511], and Glinnemann et al. [Glinnemann J, King H E Jr, Schulz H, Hahn T, La Placa S J and Dacol F 1992 Z. Kristallogr. 198 177–212]. The most striking changes are of inter-tetrahedral O–O distances and Si–O–Si angles. The volume of the tetrahedron decreased by 0.9% (from 0 to 5 GPa), which suggests that it is relatively rigid. Vibrational models of the quartz modes are identified by visualizing the associated atomic motions. Raman vibrations are mainly controlled by the deformation of the tetrahedron and the changes in the Si–O–Si bonds. Vibrational directions and intensities of atoms in all Raman modes just show little deviations when pressure increases from 0 to 5 GPa. The pressure derivatives (dν i /dP) of the 12 Raman frequencies are obtained at 0 GPa–5 GPa. The calculated results show that first-principles methods can well describe the high-pressure structural properties and Raman spectra of quartz. The combination of first-principles simulations of the Raman frequencies of minerals and Raman spectroscopy experiments is a useful tool for exploring the stress conditions within the Earth. (paper)

Synthesis and reactivity of single-phase Be{sub 17}Ti{sub 2} intermetallic compounds

Energy Technology Data Exchange (ETDEWEB)

Kim, Jae-Hwan, E-mail: kim.jaehwan@jaea.go.jp [Breeding Functional Materials Development Group, Sector of Fusion Research and Development, Japan Atomic Energy Agency (Japan); Iwakiri, Hirotomo; Furugen, Tatsuaki [Faculty of Education Elementary and Secondary School Teacher Training Program, University of the Ryukyus, Okinawa (Japan); Nakamichi, Masaru [Breeding Functional Materials Development Group, Sector of Fusion Research and Development, Japan Atomic Energy Agency (Japan)

2016-01-15

Highlights: • Preliminary synthesis of single-phase Be{sub 17}Ti{sub 2} was succeeded. • Reactivity difference between beryllium and beryllides may be caused by a lattice strain. • Oxidation of Be{sub 17}Ti{sub 2} at high temperatures results in the formation of TiO{sub 2}. • Simulation results reveal that a stable site for hydrogen at the center of tetrahedron exists. - Abstract: To investigate feasibility for application of Be{sub 17}Ti{sub 2} as a neutron multiplier as well as a refractory material, single-phase Be{sub 17}Ti{sub 2} intermetallic compounds were synthesized using an annealing heat treatment of the starting powder and a plasma sintering method. Scanning electron microscopic observations and X-ray diffraction measurements reveal that the single-phase Be{sub 17}Ti{sub 2} compounds were successfully synthesized. We examined the reactivity of Be{sub 17}Ti{sub 2} with 1% H{sub 2}O and discovered that a larger stoichiometric amount of Ti resulted in the formation of TiO{sub 2} on the surface at high temperatures. This oxidation may also contribute to an increase in both weight gain and generation of H{sub 2}. This suggests that the formation of the Ti-depleted Be{sub 17}Ti{sub 2−x} layer as a result of oxidation facilitates an increased reactivity with H{sub 2}O. To evaluate the safety aspects of Be{sub 17}Ti{sub 2}, we also investigated the hydrogen positions and solution energies based on the first principle. The calculations reveal that there are 10 theoretical sites, where 9 of these sites have hydrogen solution energies with a positive value (endothermic) and 1 site located at the center of a tetrahedron comprising two Be and two Ti atoms gives a negative value (exothermic).

[Influence of cations on the laser Raman spectra of silicate glasses].

Science.gov (United States)

Xiong, Yi; Zhao, Hong-xia; Gan, Fu-xi

2012-04-01

Na2O(K2O)-CaO(MgO)-SiO2, Na2O(K2O)-Al2O3-SiO2, Na2O(K2O)-B2O3-SiO2, Na2O(K2O)-PbO-SiO2 and PbO-BaO-SiO2 glass systems were investigated using laser Raman spectroscopic technique. The modification of short-range structure of glass caused by network modifier cations will influence Raman signature. Alkali and alkali-earth ions can weaken the bridging oxygen bond, thus lower the frequency of Si-O(b)-Si anti-symmetric stretching vibration. When coordina ted by oxygen ions, B3+ can form [BO4] tetrahedron and enter the silicon-oxygen network, but this effect had little impact on the frequency of Raman peaks located in the high-frequency region. Al3+ can also be coordinated by oxygen ions to form [AlO4] tetrahedron. [AlO4] will increase the disorder degree of network while entering network. Ba2+ can increase the density of electron cloud along the Si-O(nb) bond when it bonds with non-bridging oxygen, which will lead to a higher peak intensity of O-Si-O stretching vibration. The Raman peaks of alkli- and alkali-earth silicate glasses are mainly distributed in the region of 400 - 1 200 cm(-1), while in the spectrum of Na2O(K2O)-PbO-SiO2 glass system a 131 cm(-1) peak existed. The authors assigned it to the Pb-O symmetric stretching vibration. Some of the samples were produced in the laboratory according to the average compositions of ancient glasses, so this research is very significant to discriminating ancient silicate glasses of different systems by Laser Raman spectroscopic technique.

Credit Card Debt Hardship Letter Samples

OpenAIRE

lissa coffey

2016-01-01

Having trouble with your credit card debt? Below you will find examples of hardship letters. There are several things to consider when writing a credit card hardship letter. A hardship letter is the first step to letting the credit card company know that things are bad. This free credit card hardship letter sample is only a guide in order to start the negotiation. Credit card debt hardship letter example, hardship letter to credit card. If you are having trouble paying off your debt and need ...

Critical contrastive rhetoric: The influence of L2 letter writing instruction on L1letter writing

Directory of Open Access Journals (Sweden)

Mehrnoosh Fakharzadeh

2014-08-01

Full Text Available The present study employed critical contrastive rhetoric to investigate the L2 to L1 transfer of organizational pattern and directness level of speech acts in business complaint letters. By examining the L1 complaint letters of 30 tourism university students in two phases of study, pre and post instruction of English complaint letter, the study revealed that the rhetorical organization of Persian letters are in a state of hybridity. The post instruction comparison of letters, however, showed a tendency towards applying English conventions both in organization and directness level of complaint speech act in the L1 complaint letters. The results also revealed that after instruction the expert in the field of tourism viewed some letters as inappropriate in terms of politeness which is reflected through some lexical items.

The method to evaluate the position error in graphic positioning technology

Institute of Scientific and Technical Information of China (English)

Huiqing Lu(卢慧卿); Baoguang Wang(王宝光); Lishuang Liu(刘力双); Yabiao Li(李亚标)

2004-01-01

In the measurement of automobile body-in-white, it has been widely studied to position the two dimensional(2D)visual sensors with high precision. In this paper a graphic positioning method is proposed,a hollow tetrahedron is used for a positioning target to replace all the edges of a standard automobile body.A 2D visual sensor can be positioned through adjusting two triangles to be superposed on a screen of the computer, so it is very important to evaluate the superposition precision of the two triangles. Several methods are discussed and the least square method is adopted at last, it makes the adjustment more easy and intuitive with high precision.

First principles calculation of L21+A2 coherent equilibria in the Fe-Al-Ti system

International Nuclear Information System (INIS)

Alonso, Paula R.; Gargano, Pablo H.; Ramirez-Caballero, Gustavo E.; Balbuena, Perla B.; Rubiolo, Gerardo H.

2009-01-01

By combining first-principles density functional total energy calculations and statistical mechanics the ground state and the phase equilibria at finite temperatures of the ternary system Fe-Al-Ti have been investigated. Total energy calculations have been performed by means of the Wien 2k code to establish the ground state energetic. A cluster expansion method was therewith used to describe solid solutions. At several chosen finite temperatures the cluster variation method in the irregular tetrahedron approximation was employed in order to calculate the iron rich ternary bcc equilibria. It is confirmed that there are two kinds of phase separations of the bcc phase, A2+L2 1 and B2+L2 1 .

Representation and shape estimation of Odin, a parallel under-actuated modular robot

DEFF Research Database (Denmark)

Lyder, Andreas; Petersen, Henrik Gordon; Støy, Kasper

2009-01-01

To understand the capabilities and behavior of a robot it is important to have knowledge about its physical structure and how its actuators control its shape. In this paper we analyze the kinematics and develop a general representation of a configuration of the heterogeneous modular robot Odin....... The basics of estimating the shape of the Odin robot is presented, which leads the way for further research on the Odin robot and similar robots. We present an example of how to represent and estimate the shape of a tetrahedron configuration with various types of modules. We conclude that this representation...... can be used to find the physical constraints of the Odin robot and estimate the shape of a configuration....

DFT study of the structures and energetics of 98-atom AuPd clusters.

Science.gov (United States)

Bruma, Alina; Ismail, Ramli; Paz-Borbón, L Oliver; Arslan, Haydar; Barcaro, Giovanni; Fortunelli, Alessandro; Li, Z Y; Johnston, Roy L

2013-01-21

The energetics, structures and segregation of 98-atom AuPd nanoclusters are investigated using a genetic algorithm global optimization technique with the Gupta empirical potential (comparing three different potential parameterisations) followed by local minimizations using Density Functional Theory (DFT) calculations. A shell optimization program algorithm is employed in order to study the energetics of the highly symmetric Leary Tetrahedron (LT) structure and optimization of the chemical ordering of a number of structural motifs is carried out using the Basin Hopping Monte Carlo approach. Although one of the empirical potentials is found to favour the LT structure, it is shown that Marks Decahedral and mixed FCC-HCP motifs are lowest in energy at the DFT level.

Generation of quantum logic operations from physical Hamiltonians

International Nuclear Information System (INIS)

Zhang Jun; Whaley, K. Birgitta

2005-01-01

We provide a systematic analysis of the physical generation of single- and two-qubit quantum operations from Hamiltonians available in various quantum systems for scalable quantum information processing. We show that generation of single-qubit operations can be transformed into a steering problem on the Bloch sphere, which represents all R z -equivalence classes of single-qubit operations, whereas the two-qubit problem can be generally transformed into a steering problem in a tetrahedron representing all the local-equivalence classes of two-qubit operations (the Weyl chamber). We use this approach to investigate several physical examples for the generation of two-qubit operations. The steering approach provides useful guidance for the realization of various quantum computation schemes

Role of P{sub 2}O{sub 5} on protonic conduction in sol-gel-derived binary phosphosilicate glasses

Energy Technology Data Exchange (ETDEWEB)

Wang, C.; Abe, Y.; Kasuga, T.; Nogami, M. [Nagoya Institute of Technology, Aichi (Japan). Dept. of Materials Sceince and Engineering

1999-11-01

Sol-gel derived P{sub 2}O{sub 5}-SiO{sub 2} glasses were studied and a remarkable improvement in protonic conduction was observed by increasing the P{sub 2}O{sub 5} content. This was attributed to (1) the variation in glass structure including the reduction of the degree of cross-linking skeleton and the increase of specific surface area of glass due to the non-bridging oxygen (P=O) in P-O tetrahedron, (2) the formation of stronger hydrogen bond between hydroxyl group and P=O group as well as hydroxyl group and, (3) the p-{pi} resonance effect in O{sub (3-t)}PO(OH){sub t} unit. (author)

A Letter to Ahmad Khan

Directory of Open Access Journals (Sweden)

I.M. Mirgaleev

2016-12-01

Full Text Available We bring to attention of specialists an undated letter of Ottoman ruler Mehmed II Fatih to the Great Horde khan Ahmad from the collection of famous collector of Ottoman charters Feridun-bey [1, S. 289]. The addressee is the famous ruler of the Great Horde, khan Ahmad. Daulat Khan mentioned in the letter is Nur-Davlet. He was connected with khan Ahmad, and, as indicated by the letter, he had also set in close contact with the Ottomans whose ruler openly declares in a letter that “our sight of benevolence and patronage is directed toward him”. Thereby the Sultan made it clear to the “principal” Tatar khan Akhmad that Nur-Davlet was under the patronage of the Ottoman Empire. Considering the period of activity of Nur-Davlet in Crimea, presumably the letter was written in 1477. Famous researcher of the Crimean Khanate V.D. Smirnov had already examined the letter and the question of why Ahmad Khan was named the Crimean khan in the title of the letter [2, p. 221–222].

Letter Knowledge in Parent–Child Conversations

Science.gov (United States)

Robins, Sarah; Treiman, Rebecca; Rosales, Nicole

2014-01-01

Learning about letters is an important component of emergent literacy. We explored the possibility that parent speech provides information about letters, and also that children’s speech reflects their own letter knowledge. By studying conversations transcribed in CHILDES (MacWhinney, 2000) between parents and children aged one to five, we found that alphabetic order influenced use of individual letters and letter sequences. The frequency of letters in children’s books influenced parent utterances throughout the age range studied, but children’s utterances only after age two. Conversations emphasized some literacy-relevant features of letters, such as their shapes and association with words, but not letters’ sounds. Describing these patterns and how they change over the preschool years offers important insight into the home literacy environment. PMID:25598577

Letter-transposition effects are not universal: The impact of transposing letters in Hebrew.

Science.gov (United States)

Velan, Hadas; Frost, Ram

2009-10-01

We examined the effects of letter transposition in Hebrew in three masked-priming experiments. Hebrew, like English has an alphabetic orthography where sequential and contiguous letter strings represent phonemes. However, being a Semitic language it has a non-concatenated morphology that is based on root derivations. Experiment 1 showed that transposed-letter (TL) root primes inhibited responses to targets derived from the non-transposed root letters, and that this inhibition was unrelated to relative root frequency. Experiment 2 replicated this result and showed that if the transposed letters of the root created a nonsense-root that had no lexical representation, then no inhibition and no facilitation were obtained. Finally, Experiment 3 demonstrated that in contrast to English, French, or Spanish, TL nonword primes did not facilitate recognition of targets, and when the root letters embedded in them consisted of a legal root morpheme, they produced inhibition. These results suggest that lexical space in alphabetic orthographies may be structured very differently in different languages if their morphological structure diverges qualitatively. In Hebrew, lexical space is organized according to root families rather than simple orthographic structure, so that all words derived from the same root are interconnected or clustered together, independent of overall orthographic similarity.

Overt use of a tactile-kinesthetic strategy shifts to covert processing in rehabilitation of letter-by-letter reading.

Science.gov (United States)

Lott, Susan Nitzberg; Carney, Aimee Syms; Glezer, Laurie S; Friedman, Rhonda B

2010-11-01

BACKGROUND: Letter-by-letter readers identify each letter of the word they are reading serially in left to right order before recognizing the word. When their letter naming is also impaired, letter-by-letter reading is inaccurate and can render even single word reading very poor. Tactile and/or kinesthetic strategies have been reported to improve reading in these patients, but only under certain conditions or for a limited set of stimuli. AIMS: The primary aim of the current study was to determine whether a tactile/kinesthetic treatment could significantly improve reading specifically under normal reading conditions, i.e. reading untrained words presented in free vision and read without overt use of the strategy. METHODS #ENTITYSTARTX00026; PROCEDURES: Three chronic letter-by-letter readers participated in a tactile/kinesthetic treatment aimed at first improving letter naming accuracy (phase 1) and then letter-by-letter reading speed (phase 2). In a multiple case series design, accuracy and speed of reading untrained words without overt use of the trained tactile/kinesthetic strategy was assessed before phase 1, after phase 1 and again after phase 2. OUTCOMES #ENTITYSTARTX00026; RESULTS: All three patients significantly improved both their speed and accuracy reading untrained words without overt use of the trained tactile/kinesthetic strategy. All three patients required the additional practice in phase 2 to achieve significant improvement. Treatment did not target sentence level reading, yet two of the three patients became so adept that they could read entire sentences. CONCLUSIONS: This study replicates previous findings on the efficacy of tactile/kinesthetic treatment for letter-by-letter readers with poor letter naming. It further demonstrates that this treatment can alter cognitive processing such that words never specifically trained can be read in free vision without overtly using the trained strategy. The data suggest that an important element in achieving

Writing more informative letters of reference.

Science.gov (United States)

Wright, Scott M; Ziegelstein, Roy C

2004-05-01

Writing a meaningful and valuable letter of reference is not an easy task. Several factors influence the quality of any letter of reference. First, the accuracy and reliability of the writer's impressions and judgment depend on how well he knows the individual being described. Second, the writer's frame of reference, which is determined by the number of persons at the same level that he has worked with, will impact the context and significance of his beliefs and estimations. Third, the letter-writing skills of the person composing the letter will naturally affect the letter. To support the other components of a candidate's application, a letter of reference should provide specific examples of how an individual's behavior or attitude compares to a reference group and should assess "intangibles" that are hard to glean from a curriculum vitae or from test scores. This report offers suggestions that should help physicians write more informative letters of reference.

Letters From Peplau.

Science.gov (United States)

Peden, Ann R

2018-03-01

Dr. Hildegard Peplau, considered to be our first modern Nurse theorist and the Mother of Psychiatric Nursing, was a prolific writer, engaging in correspondence with colleagues and students who sought her professional and theoretical expertise. Through these letters, she influenced psychiatric nursing while maintaining a broad international network of professional colleagues. An analysis of letters, written between 1990 and 1998, provides insights into Peplau's last decade of professional life and a model of how to support the next generation of nurse scholars. Using content analysis, 24 letters received between 1990 and 1998 were read, reread, and coded. Recurring themes were identified. Three themes were identified. These include Peplau, the Person: Living a Life of Professional Balance; Lighting a Spark: Investing in the Next Generation; and Work in the Vineyards of Nursing: Maintaining a Life of Scholarship. The letters depict Peplau's keen intellect, her wide professional network, her leisure time spent with family and friends, and her own work to assure that her theoretical legacy continued. Peplau's insights continue to be relevant as psychiatric mental health nursing leaders engage in activities to support the next generation of scholars and leaders.

The legibility of letters and words

DEFF Research Database (Denmark)

Beier, Sofie

2016-01-01

The saying made famous by Mathew Carter that "type is a beautiful group of letters, not a group of beautiful letters”, highlights the fact that although a typeface consists of a number of letters it is when the letters are assembled in a word that they become type. However, research indicates...... that what makes letters legible in isolation is not necessarily the same as what makes them legible in words. Is it possible to create a typeface where both letters and words have a high level of legibility or are those factors so different that they cannot be combined? Through a literature review...... on relevant experimental investigations, I will in this talk present examples of when the legibility findings on letters and words correlate and when they differ....

Can "CANISO" Activate "CASINO"? Transposed-Letter Similarity Effects with Nonadjacent Letter Positions

Science.gov (United States)

Perea, Manuel; Lupker, Stephen J.

2004-01-01

Nonwords created by transposing two "adjacent" letters (i.e., transposed-letter (TL) nonwords like "jugde") are very effective at activating the lexical representation of their base words. This fact poses problems for most computational models of word recognition (e.g., the interactive-activation model and its extensions), which assume that exact…

Integrated Approach to Industrial Packaging Design

Science.gov (United States)

Vorobeva, O.

2017-11-01

The article reviews studies in the field of industrial packaging design. The major factors which influence technological, ergonomic, economic and ecological features of packaging are established. The main modern trends in packaging design are defined, the principles of marketing communications and their influence on consumers’ consciousness are indicated, and the function of packaging as a transmitter of brand values is specified. Peculiarities of packaging technology and printing techniques in modern printing industry are considered. The role of designers in the stage-by-stage development of the construction, form and graphic design concept of packaging is defined. The examples of authentic packaging are given and the mention of the tetrahedron packaging history is made. At the end of the article, conclusions on the key research aspects are made.

Crystals structure of Na3Li(TiF6)2

International Nuclear Information System (INIS)

Popov, D.Yu.; Antokhina, T.F.; Gerasimenko, A.V.; Kajdalova, T.A.; Sergienko, V.I.

2004-01-01

Crystals of Na 3 Li(TiF 6 ) 2 (1) were synthesized in aqueous solution and characterized by the elementary and X-ray phase analysis methods. According to X-ray diffraction analysis data compound 1 is crystallized in a tetragonal crystal system with the following parameters: a=5.130(1), c=18.046(4) A, Z=2, space group P4-bar2 1 c. Alternating layers on the basis of dimers made up by octahedrons of TiF 6 and Na(1)F 6 constitute the frame of compound 1 crystal structure. The dimer layers are joined in a continuous frame by Na(2) and Li cations. Coordination polyhedron of Li atom is tetrahedron (Li-F 1.898(3) A) [ru

A Kalman Filter for Mass Property and Thrust Identification of the Spin-Stabilized Magnetospheric Multiscale Formation

Science.gov (United States)

Queen, Steven Z.

2015-01-01

The Magnetospheric Multiscale (MMS) mission consists of four identically instrumented, spin-stabilized observatories, elliptically orbiting the Earth in a tetrahedron formation. For the operational success of the mission, on-board systems must be able to deliver high-precision orbital adjustment maneuvers. On MMS, this is accomplished using feedback from on-board star sensors in tandem with accelerometers whose measurements are dynamically corrected for errors associated with a spinning platform. In order to determine the required corrections to the measured acceleration, precise estimates of attitude, rate, and mass-properties are necessary. To this end, both an on-board and ground-based Multiplicative Extended Kalman Filter (MEKF) were formulated and implemented in order to estimate the dynamic and quasi-static properties of the spacecraft.

Kalman Filter for Mass Property and Thrust Identification (MMS)

Science.gov (United States)

Queen, Steven

2015-01-01

The Magnetospheric Multiscale (MMS) mission consists of four identically instrumented, spin-stabilized observatories, elliptically orbiting the Earth in a tetrahedron formation. For the operational success of the mission, on-board systems must be able to deliver high-precision orbital adjustment maneuvers. On MMS, this is accomplished using feedback from on-board star sensors in tandem with accelerometers whose measurements are dynamically corrected for errors associated with a spinning platform. In order to determine the required corrections to the measured acceleration, precise estimates of attitude, rate, and mass-properties is necessary. To this end, both an on-board and ground-based Multiplicative Extended Kalman Filter (MEKF) were formulated and implemented in order to estimate the dynamic and quasi-static properties of the spacecraft.

Elastic electron scattering from 4N nuclei in the α-cluster model with dispersion

Energy Technology Data Exchange (ETDEWEB)

Berezhnoy, Yu.A. [Karazin Kharkov National University, Kharkov (Ukraine); Mikhailyuk, V.P. [Institute for Nuclear Research, Kiev (Ukraine)

2017-06-15

The α-cluster model with dispersion has been developed for some 4N nuclei in the 2s-1d shell. The previously considered molecule-like configuration for the {sup 24}Mg nucleus is compared with the octahedron one. For the {sup 32}S nucleus both the cubic and bitetrahedron configurations are discussed. Molecule-like configurations with the {sup 32}S nucleus core and additional dumb-bell for the {sup 40}Ca nucleus are proposed. The structure of the {sup 40}Ca nucleus consisting of six α-clusters arranged in a octahedron outside of tetrahedron {sup 16}O core is also considered. The calculated charge form factors and root mean square radii of such nuclei are in a reasonable agreement with the available experimental data. (orig.)

Satellite Control Laboratory

DEFF Research Database (Denmark)

Wisniewski, Rafal; Bak, Thomas

2001-01-01

The Satellite Laboratory at the Department of Control Engineering of Aalborg University (SatLab) is a dynamic motion facility designed for analysis and test of micro spacecraft. A unique feature of the laboratory is that it provides a completely gravity-free environment. A test spacecraft......-axis magnetometer, three piezoelectric gyros, and four reaction wheels in a tetrahedron configuration. The operation of the spacecraft is fully autonomous. The data flow between the transducers and the onboard computer placed physically outside the satellite is provided by a radio link. The purpose...... can be implemented in the laboratory, e.g. three-axis attitude control, slew manoeuvres, spins stabilization using magnetic actuation and/or reaction wheels. The spacecraft attitude can be determined applying magnetometer measurements....

Crystal structure of RbCe(SeO4)2 · 5H2O

International Nuclear Information System (INIS)

Ovanesyan, S.M.; Iskhakova, L.D.; Trunov, V.K.

1987-01-01

RbTR(SeO 4 ) 2 x5H 2 O TR=La-Pr are synthesized. Crystal structure of RbCe(SeO 4 ) 2 x5H 2 O is studied. Monoclinic unit parameters are: a=7,200(2), b=8,723(1), c=19,258(6) A, Β=90,88(2), ρ (calc) =3,304 sp.gr. P2 1 /c. Within the structure the Ce nine vertex cages are united by Se(1)- and Se(2)-tetrahedrons in (Ce(SeO 4 ) 2 (H 2 O) 5 ) 2 ∞ n- layers. Some crystal structure regularities of the laminated MTR(EO 4 ) 2 xnH 2 O (M=NH 4 ,K,Rb,Cs; TR=La-Ln, E=S,Se) are considered

Different effect of quenching temperature on Fe1+σTe0.5Se0.5 and β-FeSe

Directory of Open Access Journals (Sweden)

Zhongnan Guo

2015-02-01

Full Text Available In this work, we have demonstrated a different effect on Fe1+σTe0.5Se0.5 and β-FeSe by changing the quenching temperature. Tc is clearly reduced in Fe1+σTe0.5Se0.5 after increasing the quenching temperature from 300 °C to 500 °C, while that of β-FeSe is almost unchanged. Structure refinement indicates that after quenched at 500 °C, FeTe4 tetrahedron exhibits an expansion with the stretched Fe-Te bond, together with the increased amount of interstitial iron. These particular changes on structure are believed to be responsible for the suppression of superconductivity in Fe1+σTe0.5Se0.5.

Refinement of hydrogen positions in (NH4)2SeO4

International Nuclear Information System (INIS)

Loose, A.; Mel'nik, G.; Zink, N.; Wozniak, K.; Dominiak, P.; Smirnov, L.S.; Pawlukojc, A.; Shuvalov, L.A.

2005-01-01

The crystal structure of ammonium selenate has been studied by means of single crystal X-ray and neutron diffraction with the purpose of the refinement of hydrogen positions. The refined hydrogen positions obtained by single crystal neutron diffraction show that N-H bond lengths form a regular tetrahedron in an ammonium ion. The single crystal X-ray diffraction data show that N-H bond lengths are shorter than those obtained by neutron diffraction and are not equal between themselves. Thus, the comparison of the results of X-ray and neutron diffraction allows one to suggest that the shorter N-H bond lengths by X-ray diffraction reflect the distribution of the electron charge density of ammonium ions within the (NH 4 ) 2 SeO 4 crystal lattice

Synthesis and structure of (bis(3,5-dimethyl-1H-pyrazol-1-yl)methane)diiodocobalt(II)

International Nuclear Information System (INIS)

Bushuev, M.B.; Virovets, A.V.; Peresypkina, E.V.; Naumov, D.Yu.; Lavrenova, L.G.; Potapov, A.S.; Khlebnikov, A.I.; Vasilevskij, S.F.

2005-01-01

Cobalt(II) iodo complex with bis(3,5-dimethyl-1H-pyrazol-1-yl)methane (L), CoLI 2 , is synthesized and its monocrystals are grown. The complex is characterized by electronic spectra and X-ray diffraction. CoLI 2 belongs to the monoclinic crystal system, sp. gr. P2 1 /m, a=8.4044(4), b=13.3120(5), c=14.5824(7) A; β=94.7290(10) deg; Z=4; d clcd =2.112 g/cm 3 . In its structure the complex is molecular and mononuclear one. Ligand L is coordinated in a bidentate-cyclic manner; the cobalt polyhedron is a CoN 2 I 2 tetrahedron formed by nitrogen atoms of the L pyrazole fragments and iodine atoms [ru

$^{8}$Be, $^{12}$C, $^{16}$O, $^{20}$Ne, $^{24}$Mg, and $^{32}$S nuclei and alpha clustering within a generalized liquid drop model

CERN Document Server

Royer, G; Eudes, P

2015-01-01

The potential energy governing the shape and the entrance and decay channels of the 12 C, 16 O, 20 Ne, 24 Mg, and 32 S 4n-nuclei has been determined within a generalized liquid drop model. Different three-dimensional and planar shapes have been investigated: linear chain, triangle, square, tetrahedron, pentagon, trigonal bipyramid, square pyramid, hexagon, octahedron, octogon and cube. The rms radii of the linear chains are higher than the experimental rms radii of the ground states. The binding energies of the planar shapes at the contact point are lower than the ones of the three-dimensional configurations. The a particle plus A-4 daughter configuration leads always to the lowest potential barrier relatively to the sphere configuration.

Polysialates binders preparation and their influence to shear strength of foundry sand mixtures

Directory of Open Access Journals (Sweden)

R. Fridrich

2008-07-01

Full Text Available This paper deals with polysialates water-glasses preparation. There were used various procedures with the goal to create inorganic polymer on silicon and aluminum base. The one composed of SiO2 and AlO4 tetrahedron chains. For the preparation was concentrated NaOH solution used together with metakaolinite in a way low-temperature synthesis in the presence of alkaline silicate: higher pressure and temperature (autoclave to direct making of alkaline silicate made of sand, NaOH with metakaolinite addition and by melting fritted glass together with metakaolinite and dissolution in autoclave. The dissolving effectivity was evaluated by the concentration of aluminum in alkaline silicate and by the influence to reduce strengths after heat exposition with this inorganic binder.

Preparation, characterization and photoluminescence of nanocrystalline calcium molybdate

International Nuclear Information System (INIS)

Phuruangrat, Anukorn; Thongtem, Titipun; Thongtem, Somchai

2009-01-01

Nanocrystalline calcium molybdate was successfully synthesized from Ca(NO 3 ) 2 and Na 2 MoO 4 in ethylene glycol using a microwave radiation method. Body-centered tetragonal structured calcium molybdate with narrow nanosized distribution was detected using XRD, SAED and TEM. A diffraction pattern was also simulated and was found to be in accordance with those obtained from the experiment and JCPDS standard. Raman and FTIR spectra show the Mo-O prominent stretching bands in the [MoO 4 ] 2- tetrahedrons at 879.59 and 743-895 cm -1 , respectively. Photoluminescence emission of CaMoO 4 was detected at 477 nm, caused by the annihilation of a self-trapped excitons from the [MoO 4 ] 2- excited complex.

Application of the cluster variation method to ordering in an interstitital solid solution

DEFF Research Database (Denmark)

Pekelharing, Marjon I.; Böttger, Amarante; Somers, Marcel A. J.

1999-01-01

The tetrahedron approximation of the cluster variation method (CVM) was applied to describe the ordering on the fcc interstitial sublattice of gamma-Fe[N] and gamma'-Fe4N1-x. A Lennard-Jones potential was used to describe the dominantly strain-induced interactions, caused by misfitting of the N...... atoms in the interstitial octahedral sites. The gamma-Fe[N]/gamma'-Fe4N1-x miscibility gap, short range ordering (SRO), and long-range ordering (LRO) of nitrogen in gamma-Fe[N] and gamma'-Fe4N1-x, respectively, and lattice parameters of gamma and gamm' were calculated. For the first time, N distribution...... parameters,as calculated by CVM, were compared directly to Mössbauer data for specific surroundings of Fe atoms....

Inter-vessels in-service inspection of Super-Phenix

International Nuclear Information System (INIS)

Asty, M.; Saglio, R.; Viard, J.; Lerat, B.

1984-01-01

The vessels design of fast breeder reactor Super-Phenix enables inspection during operating time. A self-moving machine -MIR- has been built up especially for that purpose. It is able to carry out visual and ultrasonorous inspection. MIR structure is that of a tetrahedron, all tops of which are fitted with two wheels, as for traction and direction. The wheels are leaning on booth the two vessels. Thanks to a computer-assisted control system, MIR is able to move along in every part of the inter-vessels space. Studies have been carried on at the French Commissariat a l'Energie Atomique, by two Sections of the advanced technologies Service. After outlining MIR working conditions, its main characteristics are described [fr

ERP correlates of letter identity and letter position are modulated by lexical frequency

Science.gov (United States)

Vergara-Martínez, Marta; Perea, Manuel; Gómez, Pablo; Swaab, Tamara Y.

2013-01-01

The encoding of letter position is a key aspect in all recently proposed models of visual-word recognition. We analyzed the impact of lexical frequency on letter position assignment by examining the temporal dynamics of lexical activation induced by pseudowords extracted from words of different frequencies. For each word (e.g., BRIDGE), we created two pseudowords: A transposed-letter (TL: BRIGDE) and a replaced-letter pseudoword (RL: BRITGE). ERPs were recorded while participants read words and pseudowords in two tasks: Semantic categorization (Experiment 1) and lexical decision (Experiment 2). For high-frequency stimuli, similar ERPs were obtained for words and TL-pseudowords, but the N400 component to words was reduced relative to RL-pseudowords, indicating less lexical/semantic activation. In contrast, TL- and RL-pseudowords created from low-frequency stimuli elicited similar ERPs. Behavioral responses in the lexical decision task paralleled this asymmetry. The present findings impose constraints on computational and neural models of visual-word recognition. PMID:23454070

The letter knowledge assessment tool.

Science.gov (United States)

Pedro, Cassandra; Lousada, Marisa; Pereira, Rita; Hall, Andreia; Jesus, Luis M T

2017-10-10

There is a need to develop letter knowledge assessment tools to characterise the letter knowledge in Portuguese pre-schoolers and to compare it with pre-schoolers from other countries, but there are no tools for this purpose in Portugal. The aim of this paper is to describe the development and validation procedures of the Prova de Avaliação de Competências de Pré-Literacia (PACPL), which assesses letter knowledge. This study includes data that has been gathered in two phases: pilot and main study. In the pilot study, an expert panel of six speech and language pathologists analysed the instrument. Children (n = 216) aged 5;0-7;11 participated in the main study that reports data related to the psychometric characteristics of the PACPL. Content validity, internal consistency, reliability and contributing factors to performance were examined statistically. A modified Bland-Altman method revealed good agreement amongst evaluators. The main study showed that the PACPL has a very good internal consistency and high inter-rater (96.2% of agreement and a Cohen's k value of 0.92) and intra-rater (95.6% of agreement and a Cohen's k value of 0.91) agreement. Construct validity of the PCAPL was also assured (Cronbach's α of 0.982). Significant differences were found between age groups with children increasing their letter knowledge with age. In addition, they were better at identifying than at producing both letter names and letter sounds. The PACPL is a valid and reliable instrument to assess letter knowledge in Portuguese children.

Letter-Transposition Effects Are Not Universal: The Impact of Transposing Letters in Hebrew

Science.gov (United States)

Velan, Hadas; Frost, Ram

2009-01-01

We examined the effects of letter-transposition in Hebrew in three masked-priming experiments. Hebrew, like English has an alphabetic orthography where sequential and contiguous letter strings represent phonemes. However, being a Semitic language it has a non-concatenated morphology that is based on root derivations. Experiment 1 showed that…

7 CFR 3560.709 - Demand letter.

Science.gov (United States)

2010-01-01

... 7 Agriculture 15 2010-01-01 2010-01-01 false Demand letter. 3560.709 Section 3560.709 Agriculture... DIRECT MULTI-FAMILY HOUSING LOANS AND GRANTS Unauthorized Assistance § 3560.709 Demand letter. (a) If a... repayment schedule, the Agency will send the borrower a demand letter specifying: (1) The amount of...

Letters of Map Change (LOMC)

Data.gov (United States)

Department of Homeland Security — Documents, including different types of Letters of MAP Revision (LOMR) and Letters of Map Amendment (LOMA), which are issued by FEMA to revise or amend the flood...

31 CFR 29.511 - Demand letters.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Demand letters. 29.511 Section 29.511... Overpayments § 29.511 Demand letters. Except as provided in § 29.516(e), before starting collection action to recover an overpayment, the Benefits Administrator must send a demand letter that informs the debtor in...

Letter Dice. Technical Note No. 6.

Science.gov (United States)

Gunter, Jock

Letter and syllable dice devised for a project in rural Ecuador provide inexpensive, easily reproducible learning materials for practice in basic literary skills. Eleven wooden cubes with six letters on each cube are cast onto a surface and the player constructs words from the letters on the top side of the dice. After a word is formed and…

Letter to the parliament:

DEFF Research Database (Denmark)

2017-01-01

This piece was a letter directed towards various ministers in the parliament, targeted at raising a discussion on the values in the education of architects in Denmark and various related topics.......This piece was a letter directed towards various ministers in the parliament, targeted at raising a discussion on the values in the education of architects in Denmark and various related topics....

Resource Letter: GW-1: Global warming

Science.gov (United States)

Firor, John W.

1994-06-01

This Resource Letter provides a guide to the literature on the possibility of a human-induced climate change—a global warming. Journal articles and books are cited for the following topics: the Greenhouse Effect, sources of infrared-trapping gases, climate models and their uncertainties, verification of climate models, past climate changes, and economics, ethics, and politics of policy responses to climate change. [The letter E after an item indicates elementary level or material of general interest to persons becoming informed in the field. The letter I, for intermediate level, indicates material of somewhat more specialized nature, and the letter A indicates rather specialized or advanced material.

Implied reading direction and prioritization of letter encoding.

Science.gov (United States)

Holcombe, Alex O; Nguyen, Elizabeth H L; Goodbourn, Patrick T

2017-10-01

Capacity limits hinder processing of multiple stimuli, contributing to poorer performance for identifying two briefly presented letters than for identifying a single letter. Higher accuracy is typically found for identifying the letter on the left, which has been attributed to a right-hemisphere dominance for selective attention. Here, we use rapid serial visual presentation (RSVP) of letters in two locations at once. The letters to be identified are simultaneous and cued by rings. In the first experiment, we manipulated implied reading direction by rotating or mirror-reversing the letters to face to the left rather than to the right. The left-side performance advantage was eliminated. In the second experiment, letters were positioned above and below fixation, oriented such that they appeared to face downward (90° clockwise rotation) or upward (90° counterclockwise rotation). Again consistent with an effect of implied reading direction, performance was better for the top position in the downward condition, but not in the upward condition. In both experiments, mixture modeling of participants' report errors revealed that attentional sampling from the two locations was approximately simultaneous, ruling out the theory that the letter on one side was processed first, followed by a shift of attention to sample the other letter. Thus, the orientation of the letters apparently controls not when the letters are sampled from the scene, but rather the dynamics of a subsequent process, such as tokenization or memory consolidation. Implied reading direction appears to determine the letter prioritized at a high-level processing bottleneck. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

A contribution to the computation of the impedance in acceleration resonators

International Nuclear Information System (INIS)

Liu, Cong

2016-05-01

symmetric curvilinear tetrahedrons are applied to the Superconducting Proton Linac (SPL) cavity. Afterwards, a parallel complex-valued FEM (CEM3Dc) eigenmode solver based on curvilinear tetrahedrons is applied to the TESLA 1.3 GHz and the third harmonic 3.9 GHz superconducting cavities.

A contribution to the computation of the impedance in acceleration resonators

Energy Technology Data Exchange (ETDEWEB)

Liu, Cong

2016-05-15

symmetric curvilinear tetrahedrons are applied to the Superconducting Proton Linac (SPL) cavity. Afterwards, a parallel complex-valued FEM (CEM3Dc) eigenmode solver based on curvilinear tetrahedrons is applied to the TESLA 1.3 GHz and the third harmonic 3.9 GHz superconducting cavities.

SU-C-202-05: Pilot Study of Online Treatment Evaluation and Adaptive Re-Planning for Laryngeal SBRT

Energy Technology Data Exchange (ETDEWEB)

Mao, W [The University of Texas Southwestern Medical Ctr, Dallas, TX (United States); Henry Ford Health System, Detroit, MI (United States); Liu, C; Zhong, H [Henry Ford Health System, Detroit, MI (United States); Rozario, T; Lu, W; Gu, X; Yan, Y; Jia, X; Sumer, B; Schwartz, D [The University of Texas Southwestern Medical Ctr, Dallas, TX (United States)

2016-06-15

Purpose: We have instigated a phase I trial of 5-fraction stereotactic body radiotherapy (SBRT) for advanced-stage laryngeal cancer. We conducted this pilot dosimetric study to confirm the potential utility of online adaptive re-planning to preserve treatment quality. Methods: Ten cases of larynx cancer were evaluated. Baseline and daily SBRT treatment plans were generated per trial protocol. Daily volumetric images were acquired prior to every fraction of treatment. Reference simulation CT images were deformably registered to daily volumetric images using Eclipse. Planning contours were then deformably propagated to daily images. Reference SBRT plans were directly copied to calculate delivered dose distributions on deformed reference CT images. In-house software platform has been developed to calculate cumulative dose over a course of treatment in four steps: 1) deforming delivered dose grid to reference CT images using deformation information exported from Eclipse; 2) generating tetrahedrons using deformed dose grid as vertices; 3) resampling dose to a high resolution within every tetrahedron; 4) calculating dose-volume histograms. Our inhouse software was benchmarked with a commercial software, Mirada. Results: In all ten cases including 49 fractions of treatments, delivered daily doses were completely evaluated and treatment could be re-planned within 10 minutes. Prescription dose coverage of PTV was less than intended in 53% of fractions of treatment (mean: 94%, range: 84%–98%) while minimum coverage of CTV and GTV was 94% and 97%, respectively. Maximum bystander point dose limits to arytenoids, parotids, and spinal cord remained respected in all cases, although variances in carotid artery doses were observed in a minority of cases. Conclusion: Although GTV and CTV coverage is preserved by in-room 3D image guidance of larynx SBRT, PTV coverage can vary significantly from intended plans. Online adaptive treatment evaluation and re-planning is potentially

Emergence of complex networks from diffusion on fractal lattices. A special case of the Sierpinski gasket and tetrahedron

International Nuclear Information System (INIS)

Chełminiak, Przemysław

2012-01-01

A new approach to the assemblage of complex networks displaying the scale-free architecture is proposed. While the growth and the preferential attachment of incoming nodes assure an emergence of such networks according to the Barabási–Albert model, it is argued here that the preferential linking condition needs not to be a principal rule. To assert this statement a simple computer model based on random walks on fractal lattices is introduced. It is shown that the model successfully reproduces the degree distributions, the ultra-small-worldness and the high clustering arising from the topology of scale-free networks. -- Highlights: ► A new mechanism of evolution for scale-free complex networks is proposed. ► The preferential attachment rule is not necessary to construct such networks. ► It is shown that they reveal some basic properties of classical scale-free nets.

Geometric spin frustration for isolated plaquettes of the lattices: An extended irreducible tensor operator method

International Nuclear Information System (INIS)

Wang Fan; Chen Zhida

2006-01-01

A new strategy to search for the good quantum numbers for the corner-sharing spin systems, as archetypal plaquettes of the lattices, was suggested for the first time in order to study on geometric spin frustration. The calculations on energy spectra by using the irreducible tensor operator method with the new strategy can be much reduced. As representative examples the energy spectra for the spin pentamer of the tetrahedron with a centered spin site and the spin heptamer of three corner-sharing equilateral-triangle were examined in order to confirm efficiency of the new strategy. Through our code, with automatically searching for the good quantum numbers, the projection operators S iz , S ix and S iy matrices in the ground state space for the spin heptamer were reliably constructed

Force Balance at the Magnetopause Determined with MMS: Application to Flux Transfer Events

Science.gov (United States)

Zhao, C.; Russell, C. T.; Strangeway, R. J.; Petrinec, S. M.; Paterson, W. R.; Zhou, M.; Anderson, B. J.; Baumjohann, W.; Bromund, K. R.; Chutter, M.;

Examples of 3-D field calculations using GFUN

International Nuclear Information System (INIS)

Lari, R.J.

1981-01-01

Magnets are described that were calculated using GFUN. A four-step procedure is used to calculate magnets using GFUN. First, the interactive TSO system is used to draw the geometry of the magnet on a Tektronix 4012 graphic display unit. When the geometry is correct, it is stored on a disc file that is shared by the batch computers 3033 and 195. A file JCL and data can be created on TSO and submitted to the batch computers to calculate the magnetization of the steel tetrahedron elements. The results of this approx. 1 hour batch job are stored on disc. In the same job, or in a separate one, the fields can be calculated at desired points and stored on a shared disc. The fourth step is to plot these fields interactively in TSO

ECMOR 4. 4th European conference on the mathematics of oil recovery. Topic C: Scale change procedures. Proceedings

Energy Technology Data Exchange (ETDEWEB)

1994-01-01

The report with collected proceedings from a conference, deals with mathematics of oil recovery with the focus on scale change procedures. Topics of proceedings are as follow: Upscaling permeability, mathematics of renormalization; a new method for the scale up of displacement processes in heterogeneous reservoirs; The scaleup of two-phase flow using permeability tensors; upscaling of permeability based on wavelet representation; preferential flow-paths detection for heterogeneous reservoirs using a new renormalization technique; averaged heterogeneous porous media by minimization of the error on the flow rate; change of scale for the full permeability tensor on a tetrahedron grid; effective relative permeabilities and capillary pressure for 1D heterogeneous media; practical and operational method for the calculation of effective dispersion coefficients in heterogeneous porous media. Nine papers are prepared. 144 refs., 71 figs., 10 tabs.

Highly macroscopically degenerated single-point ground states as source of specific heat capacity anomalies in magnetic frustrated systems

Science.gov (United States)

Jurčišinová, E.; Jurčišin, M.

2018-04-01

Anomalies of the specific heat capacity are investigated in the framework of the exactly solvable antiferromagnetic spin- 1 / 2 Ising model in the external magnetic field on the geometrically frustrated tetrahedron recursive lattice. It is shown that the Schottky-type anomaly in the behavior of the specific heat capacity is related to the existence of unique highly macroscopically degenerated single-point ground states which are formed on the borders between neighboring plateau-like ground states. It is also shown that the very existence of these single-point ground states with large residual entropies predicts the appearance of another anomaly in the behavior of the specific heat capacity for low temperatures, namely, the field-induced double-peak structure, which exists, and should be observed experimentally, along with the Schottky-type anomaly in various frustrated magnetic system.

Infrared spectroscopy of different phosphates structures.

Science.gov (United States)

Jastrzębski, W; Sitarz, M; Rokita, M; Bułat, K

2011-08-15

Infrared (IR) spectroscopic studies of mineral and synthetic phosphates have been presented. The interpretation of the spectra has been preceded by the isolated [PO(4)](3-) tetrahedron spectra analyse. The K(3)PO(4) saturated aqueous solution was measured in the special cell for liquids. The obtained IR results have been compared with the theoretical number of IR-active modes. The number and positions of the bands due to P-O vibrations have been established. The phase composition of the phosphates has been determined using XRD and IR spectroscopy methods. The influence of non-tetrahedral cations on the shape of the spectra and the positions of bands has been analysed and the crystalline field splitting effect has been discussed. Copyright © 2010 Elsevier B.V. All rights reserved.

A computational study of nodal-based tetrahedral element behavior.

Energy Technology Data Exchange (ETDEWEB)

Gullerud, Arne S.

2010-09-01

This report explores the behavior of nodal-based tetrahedral elements on six sample problems, and compares their solution to that of a corresponding hexahedral mesh. The problems demonstrate that while certain aspects of the solution field for the nodal-based tetrahedrons provide good quality results, the pressure field tends to be of poor quality. Results appear to be strongly affected by the connectivity of the tetrahedral elements. Simulations that rely on the pressure field, such as those which use material models that are dependent on the pressure (e.g. equation-of-state models), can generate erroneous results. Remeshing can also be strongly affected by these issues. The nodal-based test elements as they currently stand need to be used with caution to ensure that their numerical deficiencies do not adversely affect critical values of interest.

[μ-1,2-Bis(diphenylphosphinoethane-κ2P:P′]bis{[1,2-bis(diphenylphosphinoethane-κ2P,P′]cyanidocopper(I} methanol disolvate

Directory of Open Access Journals (Sweden)

Rong Wang

2010-08-01

Full Text Available The title centrosymmetric complex, [Cu2(CN2(C26H24P23]·2CH3OH, consists of two five-membered [Cu(dppeCN] rings [dppe is 1,2-bis(diphenylphosphinoethane] bridged by one μ2-dppe ligand, and two methanol solvent molecules. The angles around the central metal atom indicate that each CuI atom is located in the center of a distorted tetrahedron. The coordination sphere of each CuI atom is formed by three P atoms from two dppe ligands, and one C atom from the cyanide ligand. The crystal structure is stabilized by O—H...N hydrogen bonds, which are formed by the O—H donor group from methanol and the N-atom acceptor from a cyanide ligand.

Utilisation of computational fluid dynamics techniques for design of molybdenum target specification

International Nuclear Information System (INIS)

Yeoh, G.H.; Wassink, D.

2003-01-01

A three-dimensional computational fluid dynamics (CFD) model to investigate the hydraulic behaviour within a model of the liner and irradiation rig, located in the central portion of the HIFAR fuel element is described. Flow visualisation and LDV measurements are performed to better understand the fluid flow around the narrow spaces within the irradiation rig, annular target cans and liner. Based on the unstructured meshing consisted of triangular elements and tetrahedrons within the flow space generated for the geometrical structure, the CFD model was able to predict complex flow structures inside the liner containing the irradiation rig and target cans. The reliability of the model was validated against experiments. The predicted flow behaviour was comparable to the experimental observations. Predicted velocities were also found to be in good agreement with LDV measurements. (author)

48 CFR 42.504 - Postaward letters.

Science.gov (United States)

2010-10-01

... CONTRACT ADMINISTRATION AND AUDIT SERVICES Postaward Orientation 42.504 Postaward letters. In some circumstances, a letter or other written form of communication to the contractor may be adequate postaward...

A Stimulus Sampling Theory of Letter Identity and Order

Science.gov (United States)

Norris, Dennis; Kinoshita, Sachiko; van Casteren, Maarten

2010-01-01

Early on during word recognition, letter positions are not accurately coded. Evidence for this comes from transposed-letter (TL) priming effects, in which letter strings generated by transposing two adjacent letters (e.g., "jugde") produce large priming effects, more than primes with the letters replaced in the corresponding position (e.g.,…

Launch of Zoological Letters.

Science.gov (United States)

Fukatsu, Takema; Kuratani, Shigeru

2016-02-01

A new open-access journal, Zoological Letters, was launched as a sister journal to Zoological Science, in January 2015. The new journal aims at publishing topical papers of high quality from a wide range of basic zoological research fields. This review highlights the notable reviews and research articles that have been published in the first year of Zoological Letters, providing an overview on the current achievements and future directions of the journal.

Letters to those who Dare Feel: Using Reflective Letter-Writing to Explore the Emotionality of Research

Directory of Open Access Journals (Sweden)

Kathleen Pithouse-Morgan

2012-02-01

Full Text Available Using reflective letter-writing as a method of generating data, a group of four researchers embarked on a collaborative autoethnographic inquiry into the emotional dimensions of researching social aspects of HIV & AIDS. In this article, we use the medium of a narrative dialogue to represent and re-examine our reflective letter-writing method. The dialogue draws attention to key features of reflective letter-writing as a collaborative autoethnographic research method and, in so doing, highlights and explores the nature, potential significance, and challenges of this method. Our discussion points to the value of a collaborative process of reflective letter-writing as a way for researchers to access and portray emotional aspects of their research experience, to deepen their engagement with these emotional dimensions, and to gain insight into their own and others' lived research experiences.

Written Communications Simulation: Write Me a Letter.

Science.gov (United States)

North Carolina State Dept. of Public Instruction, Raleigh. Div. of Vocational Education.

This simulation is intended for use as a culminating activity after students have been exposed to personal and/or business letter writing, use of reference manuals, typing of letters, mailing procedures, typing of numbers, punctuation practice, and filing procedures. Stated objectives are to enable students to type a mailable letter; to inspect,…

On Coding Non-Contiguous Letter Combinations

Directory of Open Access Journals (Sweden)

Frédéric eDandurand

2011-06-01

Full Text Available Starting from the hypothesis that printed word identification initially involves the parallel mapping of visual features onto location-specific letter identities, we analyze the type of information that would be involved in optimally mapping this location-specific orthographic code onto a location-invariant lexical code. We assume that some intermediate level of coding exists between individual letters and whole words, and that this involves the representation of letter combinations. We then investigate the nature of this intermediate level of coding given the constraints of optimality. This intermediate level of coding is expected to compress data while retaining as much information as possible about word identity. Information conveyed by letters is a function of how much they constrain word identity and how visible they are. Optimization of this coding is a combination of minimizing resources (using the most compact representations and maximizing information. We show that in a large proportion of cases, non-contiguous letter sequences contain more information than contiguous sequences, while at the same time requiring less precise coding. Moreover, we found that the best predictor of human performance in orthographic priming experiments was within-word ranking of conditional probabilities, rather than average conditional probabilities. We conclude that from an optimality perspective, readers learn to select certain contiguous and non-contiguous letter combinations as information that provides the best cue to word identity.

Writing More Informative Letters of Reference

OpenAIRE

Wright, Scott M; Ziegelstein, Roy C

2004-01-01

Writing a meaningful and valuable letter of reference is not an easy task. Several factors influence the quality of any letter of reference. First, the accuracy and reliability of the writer's impressions and judgment depend on how well he knows the individual being described. Second, the writer's frame of reference, which is determined by the number of persons at the same level that he has worked with, will impact the context and significance of his beliefs and estimations. Third, the letter...

Use of Standard Guidelines for Department of Medicine Summary Letters.

Science.gov (United States)

Fitz, Matthew; La Rochelle, Jeffrey; Lang, Valerie; DeWaay, Deborah; Adams, William; Nasraty, Farah

2018-04-12

Phenomenon: Fourth-year medical students obtain Department of Medicine (DOM) letters ("Chair" letters) to support their residency applications. Writing and interpreting DOM letters are challenging. There is heterogeneity in the letters that makes it difficult to both write and read these letters. The purpose of this study is to determine the value of new guidelines developed by a task force of clerkship directors and program directors in internal medicine and assess the implementation of these guidelines. The Clerkship Directors in Internal Medicine performed a cross-sectional survey of internal medicine clerkship directors at U.S. and Canadian medical schools in 2014. In addition, the primary author's institution reviewed 1,347 DOM letters between 2012 and 2014 to assess the implementation of these guidelines. The survey response rate was 78%. DOM letter writers reported the guidelines were better, easier to implement, and more compatible with the purpose of DOM letters than previously. Most letter readers reported that letters using the guidelines were more credible. Writers of DOM letters in lower academic ranks rated the letters with guidelines higher in several domains than those in higher academic ranks. Readers of DOM letters in higher academic ranks rated the letters with guidelines higher in several domains than those in lower academic ranks. In the DOM letters examined, the odds of meeting each guideline increased with each additional year. However, for 3 guidelines there was an initial decline in adherence from 2012 to 2013 before increasing again in 2014-the recommended length, clerkship description, and detailed narrative guidelines. Letters solely written by a chair were less likely to incorporate the guidelines. Insights: Clerkship directors often write the DOM letters and identify with the purpose of the guidelines. As writers, lower ranking academic faculty value the guidelines more than higher ranking academic faculty. As readers of DOM letters

Maritime Geo-Fence Letter Report

Science.gov (United States)

2016-07-01

1 Classification | CG-926 RDC | author | audience | month year Maritime Geo-Fence Letter Report Authors: Irene Gonin and Gregory...Johnson   Distribution Statement A: Approved for public release; distribution is unlimited. July 2016 Report No. CG-D-10-16 Maritime Geo-Fence...United States Coast Guard Research & Development Center 1 Chelsea Street New London, CT 06320 Maritime Geo-Fence Letter Report 1

The role of sensorimotor learning in the perception of letter-like forms: tracking the causes of neural specialization for letters.

Science.gov (United States)

James, Karin H; Atwood, Thea P

2009-02-01

Functional specialization in the brain is considered a hallmark of efficient processing. It is therefore not surprising that there are brain areas specialized for processing letters. To better understand the causes of functional specialization for letters, we explore the emergence of this pattern of response in the ventral processing stream through a training paradigm. Previously, we hypothesized that the specialized response pattern seen during letter perception may be due in part to our experience in writing letters. The work presented here investigates whether or not this aspect of letter processing-the integration of sensorimotor systems through writing-leads to functional specialization in the visual system. To test this idea, we investigated whether or not different types of experiences with letter-like stimuli ("pseudoletters") led to functional specialization similar to that which exists for letters. Neural activation patterns were measured using functional magnetic resonance imaging (fMRI) before and after three different types of training sessions. Participants were trained to recognize pseudoletters by writing, typing, or purely visual practice. Results suggested that only after writing practice did neural activation patterns to pseudoletters resemble patterns seen for letters. That is, neural activation in the left fusiform and dorsal precentral gyrus was greater when participants viewed pseudoletters than other, similar stimuli but only after writing experience. Neural activation also increased after typing practice in the right fusiform and left precentral gyrus, suggesting that in some areas, any motor experience may change visual processing. The results of this experiment suggest an intimate interaction among perceptual and motor systems during pseudoletter perception that may be extended to everyday letter perception.

Teaching Complaint and Adjustment Letters--And Tact (My Favorite Assignment).

Science.gov (United States)

Deimling, Paula

1992-01-01

Describes a three-part assignment in which each student writes a complaint letter and an adjustment letter responding to another student's complaint letter. Discusses how the third part of the assignment--journal entries--allows students to formulate their own criteria for excellent letters based upon their reactions to the letters they receive.…

Exploring Corporate Rhetoric: Metadiscourse in the CEO's Letter.

Science.gov (United States)

Hyland, Ken

1998-01-01

Examines how metadiscourse is used to create a positive corporate image in 137 CEOs' letters, showing how CEOs use nonpropositional material to realize rational, credible, and affective appeals. Reveals the essentially rhetorical nature of CEOs' letters by comparing the frequency and distribution of metadiscourse in their letters and directors'…

Synthesis and crystal structure of hydrogen phosphites RbH2PO3, CsH2PO3, and TlH2PO3

International Nuclear Information System (INIS)

Kosterina, E.V.; Troyanov, S.I.; Kemnits, Eh.; Aslanov, L.A.

2001-01-01

The crystal acid phosphites RbH 2 PO 3 , CsH 2 PO 3 and TlH 2 PO 3 were separated during reaction of Rb, Cs and Tl carbonates with phosphorous acid solution. The crystal structure of the compounds was analyzed by X-ray diffraction method at 150 K. CsH 2 PO 3 has a monoclinic system, a = 7.930(2), b = 8.929(2), c = 13.163(3) A, β = 104.84(3) Deg, V = 900.9(4) A 3 , Z 8, sp. gr. P2 1 /c, R 1 = 0.239. In the structure hydrogen bonds integrate the PHO 3 tetrahedrons in the unlimited zigzag chains [HPHO 3 ] n n- laying at the layers, which are alternate to the layers of metal cations. The layers of anion chains have a wavy form [ru

Oxygen vacancy induced magnetization switching in Fe{sub 3}O{sub 4} epitaxial ultrathin films on GaAs(100)

Energy Technology Data Exchange (ETDEWEB)

Huang, Zhaocong, E-mail: zhaocong.huang@gmail.com [Department of Physics, Southeast University, Nanjing 211189 (China); Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD (United Kingdom); School of Electronic Science and Engineering, Southeast University, Nanjing 210096 (China); Chen, Qian; Zhai, Ya, E-mail: yazhai@seu.edu.cn, E-mail: jlwang@seu.edu.cn; Wang, Jinlan, E-mail: yazhai@seu.edu.cn, E-mail: jlwang@seu.edu.cn [Department of Physics, Southeast University, Nanjing 211189 (China); Xu, Yongbing [Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD (United Kingdom); Wang, Baoping [School of Electronic Science and Engineering, Southeast University, Nanjing 210096 (China)

2015-05-04

The magnetic and transport properties of half metallic Fe{sub 3}O{sub 4}, which are sensitive to the stoichiometry, are the key issue for applications in spintronics. An anomalous enlargement of the saturation magnetic moment is found in a relatively thick sample of epitaxial Fe{sub 3}O{sub 4} film by post-growth oxidation method. The investigation of the thickness dependence of magnetic moment suggests that the enhanced magnetism moment may come from the existence of oxygen vacancies. First-principles calculations reveal that with oxygen vacancies in Fe{sub 3}O{sub 4} crystal the spin of Fe ions in the tetrahedron site near the vacancy is much easier to switch parallel to the Fe ions in the octahedron site by temperature disturbance, supported by the temperature dependence of magnetic moment of Fe{sub 3}O{sub 4} films in experiment.

A pneumatic cylinder driving polyhedron mobile mechanism

Science.gov (United States)

Ding, Wan; Kim, Sung-Chan; Yao, Yan-An

2012-03-01

A novel pneumatic cylinder driving polyhedron mobile mechanism is proposed in this paper. The mechanism is comprised of 5 tetrahedrons which includes a pneumatic cylinder in each edge. It locomotes by rolling and the rolling principle refers to the center of mass (CM) of the mechanism moved out of the supporting area and let it tip over through the controlling of the motion sequence of these cylinders. Firstly, the mathematical model is built to analysis the relation between the configuration and the CM of the mechanism. Then, a binary control strategy is developed to simplify and improve the control of this mobile mechanism. After that, dynamic simulation is performed to testify the analytical validity and feasibility of the rolling gaits. At last, a prototype is fabricated to achieve the rolling successfully to demonstrate the proposed concept.

The collapse of stacking-fault tetrahedra by interaction with gliding dislocations

International Nuclear Information System (INIS)

Matsukawa, Y.; Osetsky, Yu.N.; Stoller, R.E.; Zinkle, S.J.

2005-01-01

The collapse of stacking-fault tetrahedra (SFT) by gliding dislocations was observed in in situ straining experiments in a transmission electron microscope (TEM). A stacking-fault tetrahedron was collapsed by intersection with a gliding perfect dislocation: only the base portion divided by the gliding plane of the dislocation annihilated, while the apex portion remained intact. As a result of analysis on evolution of atom configuration induced by intersection with perfect dislocation in SFT, it was found that an unusual atom configuration inevitably appeared in one of the ledges formed on stacking-fault planes, which is traditionally called I-ledge: the atoms on adjacent (1 1 1) planes were overlapping each other. The overlapping configuration provides a strong repulsive force, being a conceivable driving force to induce a chain reaction of atom displacements that collapses the SFT base portion

Giant magnetocaloric effect, magnetization plateaux and jumps of the regular Ising polyhedra

International Nuclear Information System (INIS)

Strečka, Jozef; Karľová, Katarína; Madaras, Tomáš

2015-01-01

Magnetization process and adiabatic demagnetization of the antiferromagnetic Ising spin clusters with the shape of regular polyhedra (Platonic solids) are exactly examined within the framework of a simple graph-theoretical approach. While the Ising cube as the only unfrustrated (bipartite) spin cluster shows just one trivial plateau at zero magnetization, the other regular Ising polyhedra (tetrahedron, octahedron, icosahedron and dodecahedron) additionally display either one or two intermediate plateaux at fractional values of the saturation magnetization. The nature of highly degenerate ground states emergent at intermediate plateaux owing to a geometric frustration is clarified. It is evidenced that the regular Ising polyhedra exhibit a giant magnetocaloric effect in a vicinity of magnetization jumps, whereas the Ising octahedron and dodecahedron belong to the most prominent geometrically frustrated spin clusters that enable an efficient low-temperature refrigeration by the process of adiabatic demagnetization

Low conductive support for thermal insulation of a sample holder of a variable temperature scanning tunneling microscope.

Science.gov (United States)

Hanzelka, Pavel; Vonka, Jakub; Musilova, Vera

2013-08-01

We have designed a supporting system to fix a sample holder of a scanning tunneling microscope in an UHV chamber at room temperature. The microscope will operate down to a temperature of 20 K. Low thermal conductance, high mechanical stiffness, and small dimensions are the main features of the supporting system. Three sets of four glass balls placed in vertices of a tetrahedron are used for thermal insulation based on small contact areas between the glass balls. We have analyzed the thermal conductivity of the contacts between the balls mutually and between a ball and a metallic plate while the results have been applied to the entire support. The calculation based on a simple model of the setup has been verified with some experimental measurements. In comparison with other feasible supporting structures, the designed support has the lowest thermal conductance.

A decade of cost-reduction in very large telescopes - The SST as prototype of special-purpose telescopes

Science.gov (United States)

Smith, Harlan J.

1989-10-01

Many design and technical innovations over the past ten or fifteen years have reduced the costs of very large telescopes by nearly an order of magnitude over those of classical designs. Still a further order of magnitude reduction is possible if the telescope is specialized for on-axis spectroscopy, giving up especially the luxuries of wide field, multiple focal positions, and access to all the sky at will. The SST (Spectroscopic Survey Telescope) will use eighty-five 1-m circular mirrors mounted in a steel frame composed of hundreds of interlocking tetrahedrons, keeping a fixed elevation angle of 60 deg with rotation only in azimuth. Using an optical fiber it will feed as much light to spectrographs as can be done by a conventional 8-m telescope, yet has a target basic completion cost of only $6 million.

Synthesis of mullite nanometers microwave from bentonite delaminated

International Nuclear Information System (INIS)

Gomes, J.; Azevedo, N.A.; Vieira, D.A.; Neves, G.A.; Santana, L.N.L.; Menezes, R.R.

2011-01-01

The smectite clays present as lamellar structure is formed by two layers of silica tetrahedrons and one layer of aluminum octahedra, which can be individually delaminated, reaching a thickness of about 1mm. Mullite is the only thermodynamically stable crystalline phase of SiO 2 and Al2O 3 system and can be synthesized from minerals that exhibit these oxides in its composition. The microwave synthesis offers advantages over conventional methods, the heating is rapid and uniform, avoiding an undesirable grain growth. This study aims to obtain nanometric mullite from bentonites delamined subjected to microwave heating. The samples were initially treated, then rehydrated, frozen and deagglomeration in a ball mill for 4 and 8 hours. Subsequently subjected to centrifugation, drying and microwave heating. The results showed that nano-mullite was obtained for samples subjected to longer heating and dispersions. (author)

Passivity based nonlinear attitude control of the Rømer satellite

DEFF Research Database (Denmark)

Quottrup, Michael Melholt; Krogh-Sørensen, J.; Wisniewski, Rafal

This paper suggests nonlinear attitude control of the Danish satellite Rømer. This satellite will be designed to fulfil two scientific objectives: The observation of stellar oscillations and the detection and localisation of gamma-ray bursts. The satellite will be equipped with a tetrahedron...... configuration of Wide Angle Telescopes for Cosmic Hard x-rays (WATCH), that server the dual purpose of X-ray detectors and momentum wheels. By employing passivity theory it is shown, that the satellite is a passive system. This paper shows, that global asymptotic can be obtained with a passive and an imput...... and output strictly passive system in a feedback interconnection. It is demonstrated in a simulation study that the resultant control has a potential for on-board implementation in the acquistion phase, where global stabillity of the control law is vital...

Ion-Scale Secondary Flux Ropes Generated by Magnetopause Reconnection as Resolved by MMS

Science.gov (United States)

Eastwood, J. P.; Phan, T. D.; Cassak, P. A.; Gershman, D. J.; Haggerty, C.; Malakit, K.; Shay, M. A.; Mistry, R.; Oieroset, M.; Russell, C. T.;

Crystal structure and thermal behavior of KB3O6

International Nuclear Information System (INIS)

Bubnova, R.S.; Fundamenskij, V.S.; Filatov, S.K.; Polyakova, I.G.

2004-01-01

The structure of potassium triborate prepared in metastable state by crystallization from melt at ∼ 800 deg C was studied by the method of X-ray diffraction analysis. It was ascertained that KB 3 O 6 belongs to monoclinic crystal system, space group P2 1 /c, a = 9.319(1), b = 6.648(1), c = 21.094(2) A, β = 94.38(1) deg, Z = 12. The compound is referred to a new structural type. Anion of the structure is a single boron-oxygen frame formed by three independent rigid triborate rings of [B 3 O 5 ] - , each of them consisting of two BO 3 triangles and BO 4 tetrahedron. Phase transformations during KB 3 O 6 heating up to 800 deg C, as well as thermal expansion in the range of 20-650 deg C, were studied [ru

Coordinated Cluster/Double Star observations of dayside flux transfer events on 6 April 2004

Science.gov (United States)

Wang, Jue; Pu, ZuYin; Zhou, XuZhi; Zhang, XianGuo; Dunlop, Malcolm; Fu, SuiYan; Xie, Lun; Zong, QiuGang; Xiao, ChiJie; Wang, XiaoGang; Liu, ZhenXing

2008-10-01

With the Double Star Program TC1 in the equatorial orbit and Cluster tetrahedron in the high latitude polar orbit, a conjunct observation of FTEs on the dayside magnetopause (MP) on April 6, 2004 is presented in this study. The FTEs observed by TC1 at low latitudes are characterized to be generated in the subsolar region and the obtained flux tube axes orientate along the predicted low latitude component magnetic reconnection X-line, indicating that these FTEs were more likely to be generated through multiple X-line reconnection or single X-line bursty reconnection. During the same period, Cluster also encountered a series of magnetosheath FTEs with their axes pointing roughly along the interplanetary magnetic field. At last, the global FTE configuration is obtained from observations in different locations, which is in good agreement with the "elbow shape" model.

Angles of Refraction: The Letters of Mary Delany

Directory of Open Access Journals (Sweden)

Eleonora Chiavetta

2014-04-01

Full Text Available Mary Delany (1700-1788 is particularly famous for her paper-cuttings or ‘mosaicks’ based on botanical subjects. A very lively woman of fashion, she was close to Queen Charlotte and one of the Bluestocking Ladies. She left a vivid portrait of life and society in eighteenth century England and Ireland in the six volumes of her Autobiography and Letters, edited in 1861 by her descendant Lady Llanover. Her autobiography is made up of 18 letters sent to her most intimate friend, Margaret Cavendish, Duchess of Portland. The first letter is dated 1740, but in this, as in the following ones, Mrs. Delany narrates her past life to her friend, starting from the early years of her life, describing her unhappy marriage, financial difficulties as a widow, and family relationships. Along with these ‘autobiographical’ letters, other letters written by her to her sister Ann are introduced, which date to the periods of life Mrs. Delany is dealing with. The aim of this paper is to focus on the textual, linguistic and content differences between the two letter types, and analyse how the identity of Mary Delany is differently constructed and perceived in the explicit autobiographical letters addressed to the Duchess of Portland, and the ones written to her sister. 

The non-selective cation-permeable channel TRPC3 is a tetrahedron with a cap on the large cytoplasmic end

International Nuclear Information System (INIS)

Mio, Kazuhiro; Ogura, Toshihiko; Hara, Yuji; Mori, Yasuo; Sato, Chikara

2005-01-01

TRPC3 plays important roles in neuronal differentiation and immune cell maturation by mediating the cationic current in response to phospholipase C activation, Ca 2+ depletion, and diacylglycerol stimulation. Here, we purified the TRPC3 channel using a glycosylated tetramer and observed the structure using electron microscopy. Negatively stained specimens demonstrate homogeneous protein particles containing an internal cavity-like structure. These particle images were picked up by automated pick-up programs, aligned, and classified by the growing neural gas network method. Similarly oriented projections were averaged to decrease the signal-to-noise ratio. The averaged images progress from the top view to the side views, which are representative of their raw images. The top view confirmed the hypothesis of a four-domain structure, and the side view demonstrates a large cytoplasmic domain with a capped structure at the bottom, which is near a predicted locus of ion release. The total image of the protein is a blunt-edged trapezoid of 200 x 200 x 235 A. This large dimension of TRPC3 is also supported by the Stokes radius (92 A) obtained from gel filtration chromatography

Student Teacher Letters of Reference: A Critical Analysis

Science.gov (United States)

Mason, Richard W.; Schroeder, Mark P.

2012-01-01

Letters of reference are commonly used in acquiring a job in education. Despite serious issues of validity and reliability in writing and evaluating letters, there is a dearth of research that systematically examines the evaluation process and defines the constructs that define high quality letters. The current study used NVivo to examine 160…

Sixty-Minute Review of Letter Writing

Science.gov (United States)

Cunningham, Donald H.; Graham, Louise

1974-01-01

The article describes a one-hour presentation which provides a basic stereotyped pattern of letter organization for the four types of letters (order, request, claim, and reply) the business of secretarial student is most likely to have to write. The four paragraphs of the pattern are: purpose, explanation, optional, and closing. (AG)

Initial and noninitial name-letter preferences as obtained through repeated letter rating tasks continue to reflect (different aspects of) self-esteem.

Science.gov (United States)

Hoorens, Vera; Takano, Keisuke; Franck, Erik; Roberts, John E; Raes, Filip

2015-09-01

We tested the usefulness of name-letter preference scores as indirect indicators of self-esteem by exploring whether multiple unsupervised self-administrations of letter rating tasks within a short period of time yield useful data. We also examined whether preferences for initials and noninitial name-letters tap different aspects of self-esteem. Participants from a community sample (N = 164; 58 men and 106 women, 17-67 years, Mage = 34.57, SD = 13.28) completed daily letter rating tasks and state self-esteem questionnaires for 7 consecutive days. They also completed a trait self-esteem questionnaire on the first measurement day as well as 6 months later. Preference scores for first-name initials were stronger but more unstable than preference scores for other name-letters. Preferences for first-name initials were primarily associated with directly measured state self-esteem whereas preferences for noninitials were primarily associated with directly measured trait self-esteem even if the latter was measured 6 months later. Thus, we showed that preferences for initials and noninitials are not simply interchangeable. Previous letter rating studies, which almost exclusively used initial preferences, should be interpreted in terms of state rather than trait self-esteem. In future studies, researchers should focus on the name-letter preference that reflects the aspect of self-esteem they wish to address. (c) 2015 APA, all rights reserved.

Advice letter on policy instruments renewable electricity

International Nuclear Information System (INIS)

2011-01-01

In a letter of July 2010 the Energy Council made recommendations for a policy framework with more obligations and fewer subsidies. This included the Energy Council's advice to investigate whether the introduction of a supplier obligation could play a major role in the realisation of the CO2 emission target of the Netherlands and increase the share of renewable energy in line with European agreements. This advice letter deals with one aspect of the broader considerations: the share of renewable electricity and the kind of incentive framework that is needed to achieve the target concerned. In this letter we will examine the possibilities of the SDE+ support (financial incentive for renewable energy) scheme and the supplier obligation, the effects on the market and the consequences for achieving the target. This letter closes with conclusions and recommendations. [nl

Alphabetical: How Every Letter Tells a Story

OpenAIRE

Rosen, Michael

2013-01-01

From minding your Ps and Qs to wondering why X should mark the spot, Alphabetical is a book for everyone who loves words and language. Whether it's how letters are arranged on keyboards or Viking runes, textspeak or zip codes, this book will change the way you think about letters for ever. How on Earth did we fix upon our twenty-six letters, what do they really mean, and how did we come to write them down in the first place? Michael Rosen takes you on an unforgettable adventure through the hi...

Visual and Artistic Functions of Letters in Khaghani’s Poetry

Directory of Open Access Journals (Sweden)

Mohsen Zolfaghari

2013-11-01

Full Text Available Abstract The intensity of emotion and fluctuation of meaning in the poet's mind causes him to go beyond the ordinary language and convey intellectual and emotional meanings through metaphors, similes and linguistic preparations. He has sharp eyes and a sensitive spirit and creative temperament and attempts strengthening his own literary language and creating personal style by inventing novel images, showing the creativity and imagination and entering in various arenas of imagination. This point more than anything else could be done by presenting images and new figures. Perhaps in the sixth century, and especially in Azerbaijani school, more than other periods, poets have been looking for creating innovative style in eloquence. Their major attempts were mainly in imaging, a wide field that they have competed. It is obvious that in this illustration the alphabet letters would be very helpful. Khaghani's Divan of poetry, as one of the greatest poets of this school, is the perfect poetical book of paintings in which meaning has been hidden under a delicate pattern and new different scientific, cultural and religious images. Letters are a broad range of elements that put a new field in front of the poet and he is aware of the potential features of the letters, new images, and artistic creativity techniques as well. This paper shows descriptive - analytical study of various aspects of Khaghani’s poetry and frequency of letters in the alphabet letters, alphabetic-based authenticity of images, different similarity reasons, semantic and literal multi-relevance of letters in the context of poetry, producing figures of speech based on letters, sensational relationship exists between images and letters which have been shown in his poetry. Letter have a double and even multiple application in Khaghani's poetic works (divan and moreover the construction of words and conveying meaning which is the real and common usage, they were used as artistic instruments

Letter position coding across modalities: the case of Braille readers.

Science.gov (United States)

Perea, Manuel; García-Chamorro, Cristina; Martín-Suesta, Miguel; Gómez, Pablo

2012-01-01

The question of how the brain encodes letter position in written words has attracted increasing attention in recent years. A number of models have recently been proposed to accommodate the fact that transposed-letter stimuli like jugde or caniso are perceptually very close to their base words. Here we examined how letter position coding is attained in the tactile modality via Braille reading. The idea is that Braille word recognition may provide more serial processing than the visual modality, and this may produce differences in the input coding schemes employed to encode letters in written words. To that end, we conducted a lexical decision experiment with adult Braille readers in which the pseudowords were created by transposing/replacing two letters. We found a word-frequency effect for words. In addition, unlike parallel experiments in the visual modality, we failed to find any clear signs of transposed-letter confusability effects. This dissociation highlights the differences between modalities. The present data argue against models of letter position coding that assume that transposed-letter effects (in the visual modality) occur at a relatively late, abstract locus.

Digit and letter alexia in carbon monoxide poisoning

Institute of Scientific and Technical Information of China (English)

Qingyu Shen; Xiaoming Rong; Rui Pan; Ying Peng; Wei Peng; Yamei Tang

2012-01-01

This study examined a 24-year-old patient with delayed encephalopathy, who was admitted to hospital with complaints of headache and visual impairment 1 week after acute carbon monoxide poisoning. The results of a visual field assessment, electroencephalography and head magnetic resonance imaging indicated damage to the cerebral cortex. After a 2-week treatment period, the patient had recovered from the visual impairment, but exhibited digit- and letter-reading difficulty. The Chinese aphasia battery and the number and letter battery supplement were conducted. The results revealed that the patient exhibited digit and letter alexia, while the ability to read Chinese characters was preserved. In contrast, the patient exhibited a deficit in Chinese character writing, while number and letter writing remained intact. Following treatment, reading and writing ability was improved and electroencephalographic abnormalities were ameliorated. Overall, our experimental findings demonstrated that delayed encephalopathy following acute carbon monoxide poisoning was characterized by digit and letter alexia.

The Indirect Empathic Approach to Claim Letters.

Science.gov (United States)

Bell, James D.

1985-01-01

In discussing letter-writing methods for business communication classes, the article explains that claim letter formats other than the direct approach are not only legitimate, but also effective, and suggests that the approach selected should depend upon the circumstances surrounding the claim. (CT)

Culture and subculture in transactional letter writing

DEFF Research Database (Denmark)

Shaw, Philip; Okamura, Akiko

2000-01-01

This study examines the relative contributions of subculture membership and mother-tongue status/target culture membership in writing transactional letters. We examined the letters accompanying articles initially submitted for publication by 26 NSE and 23 NNSE academics, and compared them with ef...

50 CFR 216.257 - Letters of Authorization.

Science.gov (United States)

2010-10-01

... ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE MAMMALS Taking Marine Mammals Incidental to Conducting Precision Strike Weapon Missions in the Gulf of Mexico § 216.257 Letters of Authorization. (a) A Letter of Authorization, unless suspended or revoked...

Particles and nuclei, letters

International Nuclear Information System (INIS)

2004-01-01

The present collection of letters from JINR, Dubna, contains nine separate letters on data on elastic (p,n) charge exchange: compilation, the potentialities of δ-electron control of luminosity in experiments with internal targets at the Nuclotron, pion broadening and low-mass dilepton production, fluctuation of electromagnetic cascade axis in dense amorphous segmented media, the forward detector of the ANKE spectrometer. Tracking system and its use in data analysis, quantum field theory with three-dimensional vector time, curvature decomposition and the Einstein-Yang-Mills equations, an integral equation for the spinor amplitude of a massive neutral Dirac particle in a curved space time with arbitrary geometry and surprising resonances in 147 Sm(nα) 144 Nd reaction

Letter position coding across modalities: the case of Braille readers.

Directory of Open Access Journals (Sweden)

Manuel Perea

Full Text Available The question of how the brain encodes letter position in written words has attracted increasing attention in recent years. A number of models have recently been proposed to accommodate the fact that transposed-letter stimuli like jugde or caniso are perceptually very close to their base words.Here we examined how letter position coding is attained in the tactile modality via Braille reading. The idea is that Braille word recognition may provide more serial processing than the visual modality, and this may produce differences in the input coding schemes employed to encode letters in written words. To that end, we conducted a lexical decision experiment with adult Braille readers in which the pseudowords were created by transposing/replacing two letters.We found a word-frequency effect for words. In addition, unlike parallel experiments in the visual modality, we failed to find any clear signs of transposed-letter confusability effects. This dissociation highlights the differences between modalities.The present data argue against models of letter position coding that assume that transposed-letter effects (in the visual modality occur at a relatively late, abstract locus.

Experimental test of contemporary mathematical models of visual letter recognition.

Science.gov (United States)

Townsend, J T; Ashby, F G

1982-12-01

A letter confusion experiment that used brief durations manipulated payoffs across the four stimulus letters, which were composed of line segments equal in length. The observers were required to report the features they perceived as well as to give a letter response. The early feature-sampling process is separated from the later letter-decision process in the substantive feature models, and predictions are thus obtained for the frequencies of feature report as well as letter report. Four substantive visual feature-processing models are developed and tested against one another and against three models of a more descriptive nature. The substantive models predict the decisional letter report phase much better than they do the feature-sampling phase, but the best overall 4 X 4 letter confusion matrix fits are obtained with one of the descriptive models, the similarity choice model. The present and other recent results suggest that the assumption that features are sampled in a stochastically independent manner may not be generally valid. The traditional high-threshold conceptualization of feature sampling is also falsified by the frequent reporting by observers of features not contained in the stimulus letter.

When Do First Letters Mnemonics Aid Recall?

Science.gov (United States)

Morris, P. E.; Cook, N.

1978-01-01

The evidence for the effectiveness of the first letter mnemonic technique is confused. There are at least three studies showing no effect, and one where an improvement in recall occurred. Reports two experiments which attempted to locate the conditions under which the first letter mnemonic is effective. (Author/RK)

Extra-large letter spacing improves reading in dyslexia

Science.gov (United States)

Zorzi, Marco; Barbiero, Chiara; Facoetti, Andrea; Lonciari, Isabella; Carrozzi, Marco; Montico, Marcella; Bravar, Laura; George, Florence; Pech-Georgel, Catherine; Ziegler, Johannes C.

2012-01-01

Although the causes of dyslexia are still debated, all researchers agree that the main challenge is to find ways that allow a child with dyslexia to read more words in less time, because reading more is undisputedly the most efficient intervention for dyslexia. Sophisticated training programs exist, but they typically target the component skills of reading, such as phonological awareness. After the component skills have improved, the main challenge remains (that is, reading deficits must be treated by reading more—a vicious circle for a dyslexic child). Here, we show that a simple manipulation of letter spacing substantially improved text reading performance on the fly (without any training) in a large, unselected sample of Italian and French dyslexic children. Extra-large letter spacing helps reading, because dyslexics are abnormally affected by crowding, a perceptual phenomenon with detrimental effects on letter recognition that is modulated by the spacing between letters. Extra-large letter spacing may help to break the vicious circle by rendering the reading material more easily accessible. PMID:22665803

The Predictive Validity of Teacher Candidate Letters of Reference

Science.gov (United States)

Mason, Richard W.; Schroeder, Mark P.

2014-01-01

Letters of reference are widely used as an essential part of the hiring process of newly licensed teachers. While the predictive validity of these letters of reference has been called into question it has never been empirically studied. The current study examined the predictive validity of the quality of letters of reference for forty-one student…

A mathematical tapestry demonstrating the beautiful unity of mathematics

CERN Document Server

Hilton, Peter; Donmoyer, Sylvie

2010-01-01

This easy-to-read 2010 book demonstrates how a simple geometric idea reveals fascinating connections and results in number theory, the mathematics of polyhedra, combinatorial geometry, and group theory. Using a systematic paper-folding procedure it is possible to construct a regular polygon with any number of sides. This remarkable algorithm has led to interesting proofs of certain results in number theory, has been used to answer combinatorial questions involving partitions of space, and has enabled the authors to obtain the formula for the volume of a regular tetrahedron in around three steps, using nothing more complicated than basic arithmetic and the most elementary plane geometry. All of these ideas, and more, reveal the beauty of mathematics and the interconnectedness of its various branches. Detailed instructions, including clear illustrations, enable the reader to gain hands-on experience constructing these models and to discover for themselves the patterns and relationships they unearth.

Resistance Distances in Vertex-Face Graphs

Science.gov (United States)

Shangguan, Yingmin; Chen, Haiyan

2018-01-01

The computation of two-point resistances in networks is a classical problem in electric circuit theory and graph theory. Let G be a triangulation graph with n vertices embedded on an orientable surface. Define K(G) to be the graph obtained from G by inserting a new vertex vϕ to each face ϕ of G and adding three new edges (u, vϕ), (v, vϕ) and (w, vϕ), where u, v and w are three vertices on the boundary of ϕ. In this paper, using star-triangle transformation and resistance local-sum rules, explicit relations between resistance distances in K(G) and those in G are obtained. These relations enable us to compute resistance distance between any two points of Kk(G) recursively. As explanation examples, some resistances in several networks are computed, including the modified Apollonian network and networks constructed from tetrahedron, octahedron and icosahedron, respectively.

Tetrahedral hohlraums at omega

International Nuclear Information System (INIS)

Kyrala, G.A.; Goldman, S.R.; Batha, S.H.; Wallace, J.M.; Klare, K.A.; Schappert, G.T.; Oertel, J.; Turner, R.E.

2000-01-01

We have initiated a study of the usefulness of tetrahedrally illuminated spherical hohlraums, using the Omega laser beams, to drive planar shocks in packages that require indirect drive. A first suite of experiments used spherical hohlraums with a 2-μm thick gold wall surrounded by a 100-μm thick epoxy layer and had an internal diameter of 2.8 mm. Four laser entrance holes each of diameter 700 μm, located on the tips of a regular tetrahedron were used. The shock velocities and the shock uniformities were measured using optical shock break out techniques. The hohlraum x-ray radiation spectrum was also measured using a 10-channel x-ray detector. Tentatively, peak temperatures approaching 195 eV were achieved and shock speeds of 60 μm/ns were measured, when the hohlraum was driven by 22 kJ of 3 ω radiation. (authors)

Riding Bare-Back on unstructured meshes for 21. century criticality calculations - 244

International Nuclear Information System (INIS)

Kelley, K.C.; Martz, R.L.; Crane, D.L.

2010-01-01

MCNP has a new capability that permits tracking of neutrons and photons on an unstructured mesh which is embedded as a mesh universe within its legacy geometry capability. The mesh geometry is created through Abaqus/CAE using its solid modeling capabilities. Transport results are calculated for mesh elements through a path length estimator while element to element tracking is performed on the mesh. The results from MCNP can be exported to Abaqus/CAE for visualization or other-physics analysis. The simple Godiva criticality benchmark problem was tested with this new mesh capability. Computer run time is proportional to the number of mesh elements used. Both first and second order polyhedrons are used. Models that used second order polyhedrons produced slightly better results without significantly increasing computer run time. Models that used first order hexahedrons had shorter runtimes than models that used first order tetrahedrons. (authors)

6j symbols for the modular double, quantum hyperbolic geometry, and supersymmetric gauge theories

Energy Technology Data Exchange (ETDEWEB)

Teschner, J.; Vartanov, G.S.

2012-02-15

We revisit the definition of the 6j-symbols from the modular double of U{sub q}(sl(2,R)), referred to as b-6j symbols. Our new results are (i) the identification of particularly natural normalization conditions, and (ii) new integral representations for this object. This is used to briefly discuss possible applications to quantum hyperbolic geometry, and to the study of certain supersymmetric gauge theories. We show, in particular, that the b-6j symbol has leading semiclassical asymptotics given by the volume of a non-ideal tetrahedron. We furthermore observe a close relation with the problem to quantize natural Darboux coordinates for moduli spaces of flat connections on Riemann surfaces related to the Fenchel-Nielsen coordinates. Our new integral representations finally indicate a possible interpretation of the b-6j symbols as partition functions of three-dimensional N=2 supersymmetric gauge theories. (orig.)

A diethylhydroxylaminate based mixed lithium/beryllium aggregate

Energy Technology Data Exchange (ETDEWEB)

Berger, Raphael J.F. [Paris-Lodron Universitaet Salzburg (Austria). Fachbereich fuer Materialwissenschaften und Physik; Jana, Surajit [Asansol Girls College, West-Bengal (India). Dept. of Chemistry; Froehlich, Roland [Muenster Univ. (Germany). Organisch-Chemisches Inst.; Mitzel, Norbert W. [Bielefeld Univ. (Germany). Anorganische Chemie und Strukturchemie

2015-07-01

A mixed lithium/beryllium diethylhydroxylaminate compound containing {sup n}butyl beryllium units of total molecular composition {sup n}Be(ONEt{sub 2}){sub 2} [(LiONEt{sub 2}){sup 2} {sup n}BuBeONEt{sub 2}]{sub 2} (1) was isolated from a reaction mixture of {sup n}butyl lithium, N,N-diethylhydroxylamine and BeCl{sub 2} in diethylether/thf. The crystal structure of 1 has been determined by X-ray diffraction. The aggregate is composed of two ladder-type subunits connected in a beryllium-centered distorted tetrahedron of four oxygen atoms. Only the lithium atoms are engaged in coordination with the nitrogen donor atoms. The DFT calculations support the positional occupation determined for Li and Be in the crystal structure. The DFT and the solid-state structure are in excellent agreement, indicating only weak intermolecular interactions in the solid state. Structural details of metal atom coordination are discussed.

Improving magnetosphere in situ observations using solar sails

Science.gov (United States)

Parsay, Khashayar; Schaub, Hanspeter; Schiff, Conrad; Williams, Trevor

2018-01-01

Past and current magnetosphere missions employ conventional spacecraft formations for in situ observations of the geomagnetic tail. Conventional spacecraft flying in inertially fixed Keplerian orbits are only aligned with the geomagnetic tail once per year, since the geomagnetic tail is always aligned with the Earth-Sun line, and therefore, rotates annually. Solar sails are able to artificially create sun-synchronous orbits such that the orbit apse line remains aligned with the geomagnetic tail line throughout the entire year. This continuous presence in the geomagnetic tail can significantly increase the science phase for magnetosphere missions. In this paper, the problem of solar sail formation design is explored using nonlinear programming to design optimal two-craft, triangle, and tetrahedron solar sail formations, in terms of formation quality and formation stability. The designed formations are directly compared to the formations used in NASA's Magnetospheric Multi-Scale mission.

Structural features of layered iron pnictide oxides (Fe{sub 2}As{sub 2})(Sr{sub 4}M{sub 2}O{sub 6})

Energy Technology Data Exchange (ETDEWEB)

Ogino, H., E-mail: tuogino@mail.ecc.u-tokyo.ac.j [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); JST-TRIP, Sanban-cho, Chiyoda-ku, Tokyo 102-0075 (Japan); Sato, S.; Matsumura, Y.; Kawaguchi, N.; Ushiyama, K. [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); JST-TRIP, Sanban-cho, Chiyoda-ku, Tokyo 102-0075 (Japan); Katsura, Y. [Magnetic Materials Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Horii, S. [JST-TRIP, Sanban-cho, Chiyoda-ku, Tokyo 102-0075 (Japan); Kochi University of Technology, Kami, Kochi 782-8502 (Japan); Kishio, K.; Shimoyama, J. [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); JST-TRIP, Sanban-cho, Chiyoda-ku, Tokyo 102-0075 (Japan)

2010-12-15

Structural features of newly found perovskite-based iron pnictide oxide system have been studied. Compared to REFePnO system, perovskite-based system tend to have smaller Pn-Fe-Pn angle and higher pnictogen height owing to low electronegativity of alkaline earth metal and small repulsive force between pnictogen and oxigen atoms. As-Fe-As angles of (Fe{sub 2}As{sub 2})(Sr{sub 4}Cr{sub 2}O{sub 6}), (Fe{sub 2}As{sub 2})(Sr{sub 4}V{sub 2}O{sub 6}) and (Fe{sub 2}Pn{sub 2})(Sr{sub 4}MgTiO{sub 6}) are close to ideal tetrahedron and those pnictogen heights of about 1.40 A are close to NdFeAsO with optimized carrier concentration. These structural features of this system may lead to realization of high-T{sub c} superconductivity in this system.

Expounding the mathematical seed volume 2 : the supplements : a translation of Bhāskara I on the mathematical chapter of the Āryabhatīya

CERN Document Server

Keller, Agathe

2006-01-01

In the 5th century the Indian mathematician Aryabhata (476-499) wrote a small but famous work on astronomy, the Aryabhatiya. This treatise, written in 118 verses, gives in its second chapter a summary of Hindu mathematics up to that time. Two hundred years later, an Indian astronomer called Bhaskara glossed this mathematial chapter of the Aryabhatiya. An english translation of Bhaskara's commentary and a mathematical supplement are presented in two volumes. Subjects treated in Bhaskara's commentary range from computing the volume of an equilateral tetrahedron to the interest on a loaned capital, from computations on series to an elaborate process to solve a Diophantine equation. This volume contains explanations for each verse commentary translated in Volume 1. These supplements discuss the linguistic and mathematical matters exposed by the commentator. Particularly helpful for readers are an appendix on Indian astronomy, elaborate glossaries, and an extensive bibliography.

Reaction of giant wheel polyoxomolybdate clusters with ethanol

International Nuclear Information System (INIS)

Bielanski, A.; Malecka-Lubanska, A.; Pozniczek, J.; Mueller, A.; Krickemeyer, E.; Diemann, E.

2001-01-01

The conversion of ethanol at 100-280 o C was used in order to characterise the redox and acid centers present in Na 15 0.5[Mo 152 O 457 H 14 (H 2 O) 68 ]·0.5[Mo 154 O 462 H 14 (H 2 O) 70 ]· ca.400H 2 O (1). It is concluded that Mo V /Mo VI pairs at the external surface of the rings, of which the structure of 1 is composed, are the redox centers active in ethanol dehydrogenation to acetaldehyde. Simultaneous ethanol dehydration to diethyl ether or ethylene is a typical reaction occurring on the acid centers. It is suggested that OH groups situated in (μ 3 -O) 2 O 2 tetrahedrons inside the ring structure play such role, The formation of ethane predominating at highest temperatures is attributed to secondary reactions of primary ethylene. (author)

6j symbols for the modular double, quantum hyperbolic geometry, and supersymmetric gauge theories

International Nuclear Information System (INIS)

Teschner, J.; Vartanov, G.S.

2012-02-01

We revisit the definition of the 6j-symbols from the modular double of U q (sl(2,R)), referred to as b-6j symbols. Our new results are (i) the identification of particularly natural normalization conditions, and (ii) new integral representations for this object. This is used to briefly discuss possible applications to quantum hyperbolic geometry, and to the study of certain supersymmetric gauge theories. We show, in particular, that the b-6j symbol has leading semiclassical asymptotics given by the volume of a non-ideal tetrahedron. We furthermore observe a close relation with the problem to quantize natural Darboux coordinates for moduli spaces of flat connections on Riemann surfaces related to the Fenchel-Nielsen coordinates. Our new integral representations finally indicate a possible interpretation of the b-6j symbols as partition functions of three-dimensional N=2 supersymmetric gauge theories. (orig.)

Crystal structure of beryllium amide, Be(NH2)2

International Nuclear Information System (INIS)

Jacobs, H.

1976-01-01

The x-ray investigation of single crystals of beryllium amide led to the following results. The compound crystallizes tetragonally a = 10.170 +- 0.005 A, c = 16.137 +- 0.008 A, and c/a = 1.587. The space group is I4 1 /acd. The lattice contains 32 formula units. The positions of all atoms including hydrogen were determined. The structure of Be(NH 2 ) 2 can be described by a strongly deformed cubic closepacking of anions. The cations occupy tetrahedral interstices so that 4 Be 2+ ions form a regular tetrahedron with the shortest Be-Be distances. This causes units, which can be described by Be 4 (NH 2 ) 6 (NH 2 ) 4 / 2 whereas the outer 4 amide ions serve as bridging anions to give a threedimensional arrangement. The orientation of the amide ions is given and compared with earlier results on similar metal amides. (author)

Fabrication of superhydrophobic surfaces via CaCO3 mineralization mediated by poly(glutamic acid)

Science.gov (United States)

Cao, Heng; Yao, Jinrong; Shao, Zhengzhong

2013-03-01

Surfaces with micrometer and nanometer sized hierarchical structures were fabricated by an one-step in situ additive controlled CaCO3 mineralization method. After chemical modification, the surfaces with various morphologies showed superhydrophobicity in different states, which could be easily adjusted by the initial supersaturation of the mineralization solution (concentration of calcium ion and poly(glutamic acid)). Generally, the "lotus state" surface which was covered by a thick layer of tetrahedron-shaped CaCO3 particles to exhibit a contact angle (CA) of 157±1° and a very low contact angle hysteresis (CAH) (roll-off angle=1°) was produced under high supersaturation. On the other hands, the petal-like surface with flower-shaped calcite spherulites was obtained in a relative low supersaturation, which showed both high CA (156±2°) and CAH (180°) in a "Cassie impregnating wetting state".

The Substructure of a Flux Transfer Event Observed by the MMS Spacecraft

Science.gov (United States)

Hwang, K.-J.; Sibeck, D. G.; Giles, B. L.; Pollock, C. J.; Gershman, D.; Avanov, L.; Paterson, W. R.; Dorelli, J. C.; Ergun, R. E.; Russel, C. T.;

Teaching letter sounds to kindergarten English language learners using incremental rehearsal.

Science.gov (United States)

Peterson, Meredith; Brandes, Dana; Kunkel, Amy; Wilson, Jennifer; Rahn, Naomi L; Egan, Andrea; McComas, Jennifer

2014-02-01

Proficiency in letter-sound correspondence is important for decoding connected text. This study examined the effects of an evidence-based intervention, incremental rehearsal (IR), on the letter-sound expression of three kindergarten English language learners (ELLs) performing below the district benchmark for letter-sound fluency. Participants were native speakers of Hmong, Spanish, and Polish. A multiple-baseline design across sets of unknown letter sounds was used to evaluate the effects of IR on letter-sound expression. Visual analysis of the data showed an increase in level and trend when IR was introduced in each phase. Percentage of all non-overlapping data (PAND) ranged from 95% to 100%. All participants exceeded expected growth and reached the spring district benchmark for letter-sound fluency. Results suggest that IR is a promising intervention for increasing letter-sound expression for ELLs who evidence delays in acquiring letter sounds. Copyright © 2013 Society for the Study of School Psychology. Published by Elsevier Ltd. All rights reserved.

40 CFR 280.99 - Letter of credit.

Science.gov (United States)

2010-07-01

... (UST) Financial Responsibility § 280.99 Letter of credit. (a) An owner or operator may satisfy the... brackets are to be replaced with the relevant information and the brackets deleted: Irrevocable Standby.... We certify that the wording of this letter of credit is identical to the wording specified in 40 CFR...

Particles and Nuclei, Letters

International Nuclear Information System (INIS)

2004-01-01

The present collection of letters from JINR, Dubna, contains eight separate letters on analysis of experimental data on relativistic nuclear collisions in the Lobachevski space, relativistic contribution of the final-state interaction to deuteron photodisintegration, on the charge asymmetry of the like-sign lepton pairs induced by B - B bar - production asymmetry, limits on the ν e → ν e neutrino oscillation parameters from an experiment at the IHEP-JINR neutrino detector, excitation of high spin isomers in photonuclear reactions, study of product formation in proton-nuclear reactions on the 129 I target induced by 660-MeV protons, application of jet pumps in the cryogenic system of the Nuclotron - superconducting accelerator of relativistic particles and study of the silicon drift detector performance with inclined tracks

The elaboration of motor programs for the automation of letter production.

Science.gov (United States)

Thibon, Laurence Séraphin; Gerber, Silvain; Kandel, Sonia

2018-01-01

We investigated how children learn to write letters. Letter writing evolves from stroke-by-stroke to whole-letter programming. Children of ages 6 to 9 (N=98) wrote letters of varying complexity on a digitizer. At ages 6 and 7 movement duration, dysfluency and trajectory increased with stroke number. This indicates that the motor program they activated mainly coded information on stroke production. Stroke number affected the older children's production much less, suggesting that they programmed stroke chunks or the whole letter. The fact that movement duration and dysfluency decreased from ages 6 to 8, and remained stable at ages 8 and 9 suggests that automation of letter writing begins at age 8. Automation seems to require the elaboration of stroke chunks and/or letter-sized motor programs. Copyright © 2017 Elsevier B.V. All rights reserved.

Peer assessment of outpatient consultation letters – feasibility and satisfaction

Directory of Open Access Journals (Sweden)

Dojeiji Suzan

2007-05-01

Full Text Available Abstract Background Written correspondence is one of the most important forms of communication between health care providers, yet there is little feedback provided to specialists. The objective of this study was to determine the feasibility and satisfaction of a peer assessment program on consultation letters and to determine inter-rater reliability between family physicians and specialists. Methods A rating scale of nine 5-point Likert scale items including specific content, style items, education value of the letter and an overall rating was developed from a previous validated tool. Nine Internal Medicine specialists/subspecialists from two tertiary care centres submitted 10 letters with patient and physician identifiers removed. Two Internal Medicine specialists, and 2 family physicians from the other centre rated each letter (to protect writer anonymity. A satisfaction survey was sent to each writer and rater after collation of the results. A follow-up survey was sent 6–8 months later. Results There was a high degree of satisfaction with the process and feedback. The rating scale information was felt to be useful and appropriate for evaluating the quality of consultation letters by 6/7 writers. 5/7 seven writers felt that the feedback they received resulted in immediate changes to their letters. Six months later, 6/9 writers indicated they had maintained changes in their letters. Raters rank ordered letters similarly (Cronbach's alpha 0.57–0.84 but mean scores were highly variant. At site 1 there were significant differences in scoring brevity (p Conclusion Most participants found peer assessment of letters feasible and beneficial and longstanding changes occurred in some individuals. Family physicians and specialists appear to have different expectations on some items. Further studies on reliability and validity, with a larger sample, are required before high stakes professional assessments include consultation letters.

Pseudo-synesthesia through reading books with colored letters.

Directory of Open Access Journals (Sweden)

Olympia Colizoli

Full Text Available BACKGROUND: Synesthesia is a phenomenon where a stimulus produces consistent extraordinary subjective experiences. A relatively common type of synesthesia involves perception of color when viewing letters (e.g. the letter 'a' always appears as light blue. In this study, we examine whether traits typically regarded as markers of synesthesia can be acquired by simply reading in color. METHODOLOGY/PRINCIPAL FINDINGS: Non-synesthetes were given specially prepared colored books to read. A modified Stroop task was administered before and after reading. A perceptual crowding task was administered after reading. Reading one book (>49,000 words was sufficient to induce effects regarded as behavioral markers for synesthesia. The results of the Stroop tasks indicate that it is possible to learn letter-color associations through reading in color (F(1, 14 = 5.85, p = .030. Furthermore, Stroop effects correlated with subjective reports about experiencing letters in color (r(13 = 0.51, p = .05. The frequency of viewing letters is related to the level of association as seen by the difference in the Stroop effect size between upper- and lower-case letters (t(14 = 2.79, p = .014 and in a subgroup of participants whose Stroop effects increased as they continued to read in color. Readers did not show significant performance advantages on the crowding task compared to controls. Acknowledging the many differences between trainees and synesthetes, results suggest that it may be possible to acquire a subset of synesthetic behavioral traits in adulthood through training. CONCLUSION/SIGNIFICANCE: To our knowledge, this is the first evidence of acquiring letter-color associations through reading in color. Reading in color appears to be a promising avenue in which we may explore the differences and similarities between synesthetes and non-synesthetes. Additionally, reading in color is a plausible method for a long-term 'synesthetic' training program.

Letter of Map Revision

Data.gov (United States)

Earth Data Analysis Center, University of New Mexico — The National Flood Hazard Layer (NFHL) data incorporates all Digital Flood Insurance Rate Map(DFIRM) databases published by FEMA, and any Letters Of Map Revision...

Particles and nuclei, letters

International Nuclear Information System (INIS)

2004-01-01

The present collection of letters from JINR, Dubna, contains nine separate letters on nonlocal chiral quark model with confinement, perturbation of finite-lattice spectral levels by nearby nuclear resonances, on the application of 'Z 0 + jet' events for determining the gluon distribution in a proton at the LHC, account of light velocity constancy in the Galilean problem on the free movement of a particle and its fall onto the ground, first results of crystal deflector investigations at the Nuclotron external beams, decay parameters of K mesons, measured at proton synchrotron U-70 using 'Hyperon' set-up and modern world data, prototype of atomic-emission spectrometer on the basis of one-electrode impulse RF discharge for analytical measurements, polarimeter for Nuclotron internal beam and primordial bubbles of colour superconducting quark matter

Patient information letters on nutrition: development and implementation.

NARCIS (Netherlands)

Binsbergen, J.J. van; Drenthen, A.J.

2003-01-01

BACKGROUND: In 1998 the Dutch College of General Practitioners (NHG) began developing patient information letters (PILs), based on the practice guidelines for family physicians (FPs) (NHG standards). Five nutritional guidance letters have since been developed with the Dutch Nutrition Center.

Color associations for days and letters across different languages

Science.gov (United States)

Rouw, Romke; Case, Laura; Gosavi, Radhika; Ramachandran, Vilayanur

2014-01-01

While colors are commonplace in everyday metaphors, relatively little is known about implicit color associations to linguistic or semantic concepts in a general population. In this study, we test color associations for ordered linguistic concepts (letters and days). The culture and language specificity of these effects was examined in a large group (457) of Dutch-speaking participants, 92 English-speaking participants, and 49 Hindi-speaking participants. Non-random distributions of color choices were revealed; consistencies were found across the three language groups in color preferences for both days and letters. Interestingly, while the Hindi-speaking participants were presented with letter stimuli matched on phonology, their pattern of letter-to-color preferences still showed similarities with Dutch- and English-speaking participants. Furthermore, we found that that the color preferences corresponded between participants indicating to have conscious color experiences with letters or days (putative synesthetes) and participants who do not (non-synesthetes). We also explored possible mechanisms underlying the color preferences. There were a few specific associations, including red for “A,” red for “Monday,” and white for “Sunday.” We also explored more general mechanisms, such as overall color preferences as shown by Simner et al. (2005). While certainly not all variation can be explained or predicted, the results show that regularities are present in color-to-letter or color-to-day preferences in both putative synesthetes and non-synesthetes across languages. Both letter-to-color and day-to-color preferences were influenced by multiple factors. The findings support a notion of abstract concepts (such as days and letters) that are not represented in isolation, but are connected to perceptual representational systems. Interestingly, at least some of these connections to color representations are shared across different language/cultural groups. PMID

Color associations for days and letters across different languages

Directory of Open Access Journals (Sweden)

Romke eRouw

2014-05-01

Full Text Available While colors are commonplace in everyday metaphors, relatively little is known about implicit color associations to linguistic or semantic concepts in a general population. In this study, we test color associations for ordered linguistic concepts (letters and days. The culture and language specificity of these effects was examined in a large group (457 of Dutch-speaking participants, 92 English-speaking participants, and 49 Hindi-speaking participants. Non-random distributions of color choices were revealed; consistencies were found across the three language groups in color preferences for both days and letters. Interestingly, while the Hindi-speaking participants were presented with letter stimuli matched on phonology, their pattern of letter-to-color preferences still showed similarities with Dutch- and English-speaking participants. Furthermore, we found that that the color preferences corresponded between participants indicating to have conscious color experiences with letters or days (putative synesthetes and participants who do not (non-synesthetes. We also explored possible mechanisms underlying the color preferences. There were a few specific associations, including red for A, red for Monday, and white for Sunday. We also explored more general mechanisms, such as overall color preferences shown by Simner et al (2005. While certainly not all variation can be explained or predicted, the results show that regularities are present in color-to-letter or color-to-day preferences in both putative synesthetes and non-synesthetes across languages. Both letter-to-color and day-to-color preferences were influenced by multiple factors. The findings support a notion of abstract concepts (such as days and letters that are not represented in isolation, but are connected to perceptual representational systems. Interestingly, at least some of these connections to color representations are shared across different language/cultural groups.

Michelangelo, a Tireless Letter Writer

Directory of Open Access Journals (Sweden)

Adelin Charles Fiorato

2014-04-01

Full Text Available A titan of artistic creation, the sculptor-painter-architect Michelangelo was also a tireless letter writer. Five hundred and eighteen of his letters have reached us, stretching from his youth to the eve of his death, but we know that many others have been lost. Written in a kind of familiar Florentine and in a style of minimalist ‘realism’ – which does not prevent the presence of either impetuous polemical flights or pages of literary indulgence – these letters deal mainly with everyday subjects: day-by-day relationships, either endearing or resentful, with his relatives, financial or property matters and, above all, the marriage problems which concerned his nephew Leonardo, the sole heir of the family. But one also discovers in them the artist’s warm feelings of friendship and love, his poetic and aesthetic exchanges, his relationships, often conflictual, with his fellow-artists and patrons as well as his reflections on old age and death. All in all, these letters represent a documentary chronicle of a Florentine bourgeois family and the technical hassle of an entrepreneur’s activity. If, on the one hand, the Carteggio does not shed light either on Michelangelo’s conception of art or the way in which he realized his works, on the other it illustrates certain latent aspects of his projects, as well as of his personality, which was at the same time melancholy and aggressive, surprisingly whole and manifold. This luxuriant correspondence presents, so to speak, a ‘genetic’ interest, since it reveals the hidden face of the brilliant conceiver and creator, of the artist and entrepreneur struggling with the obstacles whose overcoming makes creation possible. 

How To Write a Business Letter. Power of the Printed Word.

Science.gov (United States)

Forbes, Malcolm

Business letters should turn people on rather than turning them off. To write a good business letter, know what the goal is before starting to write, call the reader by name, tell what the letter is about in the first paragraph, refer to dates when answering letters, and write from the reader's point of view. Be positive, be nice, and be natural.…

DOCUMENTARY LETTER OF CREDIT IN THE REGULATION OF 600-PARIS PUBLICATION

Directory of Open Access Journals (Sweden)

VASILE NEMES

2011-04-01

Full Text Available In the year 2007 was adopted the Publication no. 600 of Paris regarding the Rules and the Uniform Practices for documentary letters of credit which replaced the Publication no. 500. Publication no. 600 (UCP 600 is applied to all the irrevocable documentary letters of credit when the parties make express reference to these Rules. The Publication no. 600 includes uniform rules, international practices and standards of irrevocable documentary letters of credit. The new Publication has brought a number of changes on the issues regarding the performance of the letters of credit, both in the relationship with the nonbanking institutions participants and in the relationship between the credit institutions participating in the performance of the letter of credit. This study, without being exhaustive, aims to capture the main aspects of novelty brought by the publication no. 600 and their legal approach to the new perspective of the international trade relations. It has in view, in particular, the irrevocable character of the letter of credit, the elaboration method and procedure of the letter of credit, the participants to the unfolding of the specific relationship of the letter of credit and the main duties of the involved credit institutions.

Return to sender: Constantijn Huygens as a man of letters

NARCIS (Netherlands)

Gosseye, L.; Blom, F.; Leerintveld, A.

2013-01-01

Return to Sender takes as its starting point Constantijn Huygens’ letters and shows us the author in his different guises: intimus of René Descartes, translator of John Donne, collector of art, writer of flirtatious love letters and the author of a long consolatory letter-poem for an ailing friend

Evidence for magnocellular involvement in the identification of flanked letters

NARCIS (Netherlands)

Omtzigt, D.; Hendriks, A.W.C.J.; Kolk, H.H.J.

2002-01-01

Little is known about the role of the magno system in reading. One important hypothesis is that this system is involved in the allocation of attention. We reasoned that the presentation of a single letter automatically draws attention to this letter, whereas in the case of a flanked letter, an

Letter to Carl Niigeli

Indian Academy of Sciences (India)

We reproduce an english translation of one of these letters below, in which ... contemporary scientific knowledge, and that under the circumstances ... generation it became necessary to limit the numbers because of lack of space, so that, in.

Letters of intent

International Nuclear Information System (INIS)

Anon.

1993-01-01

Thursday 5 November was another major milestone en route to the establishment of the experimental programme for CERN's LHC protonproton collider to be built in the 27- kilometre LEP tunnel. After initial discussions of 'Expressions of Interest' at the specially arranged meeting at Evian-les-Bains, France, earlier this year (May, page 1), three Letters of Intent have emerged, together involving nearly 2000 physicists from research institutes all over the world. As well as these researchers listed on the documents, the plans in fact involve many additional technical specialists who work behind the scenes. It was a historic moment as these three detector proposals were aired at the first open meeting of the new LHC Experiments Committee. CERN's main auditorium and a large overflow room receiving relayed video pictures were both packed. From these three schemes - ATLAS, CMS and L3P - and the first reactions to their letters of intent, eventually two projects will emerge, for which full technical proposals will be prepared, including construction plans and credible costings

Pseudo-synesthesia through reading books with colored letters

NARCIS (Netherlands)

Colizoli, O.; Murre, J.M.J.; Rouw, R.

2012-01-01

Background Synesthesia is a phenomenon where a stimulus produces consistent extraordinary subjective experiences. A relatively common type of synesthesia involves perception of color when viewing letters (e.g. the letter ‘a’ always appears as light blue). In this study, we examine whether traits

Letters on nuclear controversy

International Nuclear Information System (INIS)

Kafka, P.; Maier-Leibnitz, H.

1982-01-01

Heinz Maier-Leibnitz a well-known scientist, nuclear physicist, for 50 years, who publicily supported the idea not to overrate the dangers of peaceful utilization of nuclear energy, has grown tired of talking only to colleagues. He invites a junior fellow physicist, who held engaged speeches against the nuclear power plant Zwentendorf, to an exchange of thoughts. Peter Kafka, an astro-physicist studied the self organisation of the universe from the big bang to the economic crisis and encountered the question of which conditions have to be fulfilled to prevent progress from becoming caranogenous. He became one of the spokesmen of 'political ecology' and called for resistance again large-scale technological use of scientific knowledge. He was enthusiastic about the idea of an exchange of letters, because he - just like his partner - believes in gaining knowledge by discussion. The variety of subjects is sketched briefly in form of three lectures. In the letters both scientists discuss intensly about: - Freedom of science and responsibility of science. - Decisions on energy questions under time-pressure. - Risks of nuclear plants. - Large scale technology and large-scale research or decentralization. - Energy utilization and energy waste. - Nuclear energy and alternatives. - Sense and nonsense of detailed future planning. In the end no one has convinced the other. The reader however finds a lot of new incentives in the letters - printed in unabridged form - a lot of new and significant arguments for a discussion which has only just started. (orig.) [de

Transposed-letter priming of prelexical orthographic representations.

Science.gov (United States)

Kinoshita, Sachiko; Norris, Dennis

2009-01-01

A prime generated by transposing two internal letters (e.g., jugde) produces strong priming of the original word (judge). In lexical decision, this transposed-letter (TL) priming effect is generally weak or absent for nonword targets; thus, it is unclear whether the origin of this effect is lexical or prelexical. The authors describe the Bayesian Reader theory of masked priming (D. Norris & S. Kinoshita, 2008), which explains why nonwords do not show priming in lexical decision but why they do in the cross-case same-different task. This analysis is followed by 3 experiments that show that priming in this task is not based on low-level perceptual similarity between the prime and target, or on phonology, to make the case that priming is based on prelexical orthographic representation. The authors then use this task to demonstrate equivalent TL priming effects for nonwords and words. The results are interpreted as the first reliable evidence based on the masked priming procedure that letter position is not coded absolutely within the prelexical, orthographic representation. The implications of the results for current letter position coding schemes are discussed.

Insights from developmental and acquired letter position dyslexia on morphological decomposition in reading

Directory of Open Access Journals (Sweden)

Naama eFriedmann

2015-07-01

Full Text Available We explored morphological decomposition in reading, the locus in the reading process in which it takes place and its nature, comparing different types of morphemes. We assessed these questions through the analysis of letter position errors in readers with letter position dyslexia(LPD. LPD is a selective impairment to letter position encoding in the early stage of word reading, which results in letter migrations (cloud-could. We used the fact that migrations in LPD occur mainly in word-interior letters, whereas exterior letters rarely migrate.The rationale was that if morphological decomposition occurs prior to letter position encoding and strips off affixes, word-interior letters adjacent to an affix (signs-signs would become exterior following affix-stripping and hence exhibit fewer migrations.We tested 11 Hebrew readers with developmental LPD and 1 with acquired LPD in 6 experiments of reading aloud, lexical decision, and comprehension, at the single word and sentence levels. We examined migrations next to inflectional,derivational,or bound function morphemes compared with exterior letters.Root letters adjacent to inflectional and derivational morphemes were treated like middle letters, and migrated frequently, whereas root letters adjacent to bound function morphemes patterned with exterior letters, and almost never migrated. Given that LPD is a pre-lexical deficit, these results indicate that morphological decomposition takes place in an early, pre-lexical stage. Morphologically complex nonwords showed the same pattern, indicating that this decomposition is structurally, rather than lexically, driven.We suggest that letter position encoding takes place before morphological analysis, but in some cases, as with bound function morphemes, the complex word is re-analyzed as two separate words. In this reanalysis, letter positions in each constituent word are encoded separately,and hence the exterior letters of the root are treated as exterior and

7 CFR 1737.80 - Description of characteristics letter.

Science.gov (United States)

2010-01-01

... the amount of the proposed loan, its purposes, rate of interest, loan security requirements, and other... SERVICE, DEPARTMENT OF AGRICULTURE PRE-LOAN POLICIES AND PROCEDURES COMMON TO INSURED AND GUARANTEED TELECOMMUNICATIONS LOANS Characteristics Letter § 1737.80 Description of characteristics letter. (a) After all of the...

Pseudo-Synesthesia through Reading Books with Colored Letters

Science.gov (United States)

Colizoli, Olympia; Murre, Jaap M. J.; Rouw, Romke

2012-01-01

Background Synesthesia is a phenomenon where a stimulus produces consistent extraordinary subjective experiences. A relatively common type of synesthesia involves perception of color when viewing letters (e.g. the letter ‘a’ always appears as light blue). In this study, we examine whether traits typically regarded as markers of synesthesia can be acquired by simply reading in color. Methodology/Principal Findings Non-synesthetes were given specially prepared colored books to read. A modified Stroop task was administered before and after reading. A perceptual crowding task was administered after reading. Reading one book (>49,000 words) was sufficient to induce effects regarded as behavioral markers for synesthesia. The results of the Stroop tasks indicate that it is possible to learn letter-color associations through reading in color (F(1, 14) = 5.85, p = .030). Furthermore, Stroop effects correlated with subjective reports about experiencing letters in color (r(13) = 0.51, p = .05). The frequency of viewing letters is related to the level of association as seen by the difference in the Stroop effect size between upper- and lower-case letters (t(14) = 2.79, p = .014) and in a subgroup of participants whose Stroop effects increased as they continued to read in color. Readers did not show significant performance advantages on the crowding task compared to controls. Acknowledging the many differences between trainees and synesthetes, results suggest that it may be possible to acquire a subset of synesthetic behavioral traits in adulthood through training. Conclusion/Significance To our knowledge, this is the first evidence of acquiring letter-color associations through reading in color. Reading in color appears to be a promising avenue in which we may explore the differences and similarities between synesthetes and non-synesthetes. Additionally, reading in color is a plausible method for a long-term ‘synesthetic’ training program. PMID

30 CFR 1.3 - Use of letters and acronym MSHA.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Use of letters and acronym MSHA. 1.3 Section 1.3 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR OFFICIAL EMBLEM AND...; ESTABLISHMENT AND USE OF OFFICIAL EMBLEM § 1.3 Use of letters and acronym MSHA. The letters and acronym MSHA may...

Anonymous letters? DNA and fingerprints technologies combined to solve a case.

Science.gov (United States)

Barbaro, A; Cormaci, P; Teatino, A; La Marca, A; Barbaro, A

2004-12-02

Two brothers, living in two different cities, received two different anonymous letters. We performed latent prints development and DNA research on the letters and also on a glass used by a cousin suspected to be the letters' sender.

Letters of Marcus Antonius Kappus from colonial America IV

Directory of Open Access Journals (Sweden)

Janez Stanonik

1989-12-01

Full Text Available The letter of Marcus Antonius Kappus which we publish in our present the fourth - continuation of his letters from Colonial America, is not preserved - as the first three letters are - in a manuscript. Instead we find it published in the famous contemporary collection of Jesuitic letters which appeared from 1728 till 1758 under the editorship of Joseph Stöcklein and his successors in Augsburg and Graz under the title Der neue Welt-Bott mit Allerhand Nachrichten derer Missionariorum Soc. Jesu. Kappus' letter can be found in vol. I, part II, p. 86-88 under the number 56. It has never since 1728 been reprinted in German, neither has it ever been published in an English translation. Our reprint of the German text is justified because Stöcklein's collection is generally not available even in the largest libraries, especially in America. An English translation can be useful because of the difficulties the old form of its German with its localisms can cause to its readers.

Name-letter branding under scrutiny: real products, new algorithms, and the probability of buying.

Science.gov (United States)

Stieger, Stefan

2010-06-01

People like letters matching their own first and last name initials more than nonname letters. This name-letter effect has also been found for brands, i.e., people like brands resembling their own name letters (initial or first three). This has been termed name-letter branding effect. In the present study of 199 participants, ages 12 to 79 years, this name-letter branding effect was found for a modified design (1) using real products, (2) concentrating on product names rather than brand names, (3) using five different products for each letter of the Roman alphabet, (4) asking for the buying probability, and (5) using recently introduced algorithms, controlling for individual response tendencies (i.e., liking all letters more or less) and general normative popularity of particular letters (i.e., some letters are generally preferred more than other letters).

Open Letter to Religious Leaders about Sex Education

Science.gov (United States)

American Journal of Sexuality Education, 2011

2011-01-01

The "Open Letter to Religious Leaders about Sex Education" reinforces scriptural and theological commitments to truth-telling in calling for "full and honest education about sexual and reproductive health." This "Open Letter" was published in 2002, at about the midpoint of a decade-long federal government commitment to…

Analyzing International Letters in a Business Communication Class.

Science.gov (United States)

Devet, Bonnie

1998-01-01

Shows how students can use persuasive principles of communication (format and writer's purpose) and of classical rhetoric (organization, ethos, pathos, logos, and style) to improve their ability to analyze business letters. Shows how applying these principles to the analysis of business letters from other countries helps students write better and…

Synthesis of 4-methoxybenzyl ester of monochloro pyrethrum acid%偏氯菊酸对甲氧基苄酯的合成研究

Institute of Scientific and Technical Information of China (English)

陈震; 张昌军; 林晓辉

2011-01-01

Synthesis of a new ester of monochloro pyrethrum acid was reported. 4, 6, 6-Trichloro-3, 3-dimethyl-hexahoic acid methyl ester was synthesized from methyl 3,3-dimethyl pentenoate and chloroform initiated with ferrous chloride in a confined system. Followed by ring-closure, elimination, hydrolysis and acidification,3-(2-chloro-ethenyl)-2,2-dimethyl-cy-clopropanecarboxylic acid ( monochloro pyrethrum acid) was obtained. 4-Methoxybenzyl ester of monochloro pyrethrum acid was obtained by the reaction between sodium of monochloro pyrethrum acid and a quaternary ammonium salt. Three undocumented compounds were obtained. Using the method reported in ' Tetrahedron letter ', benzoyl peroxide or nitrile azo used as initiator and reaction under atmospheric pressure, target product was not obtained.%报道了一种新的拟除虫菊酯——偏氯菊酯的合成方法.以贲亭酸甲酯为原料,氯化亚铁作为引发剂在密闭体系中与氯仿加成后得到3,3-二甲基-4,6,6-三氯己酸甲酯,再成环、脱卤化氢,水解酸化后得到2,2-二甲基-3-(乙氯乙烯基)-环丙烷羧酸(偏氯菊酸),偏氯菊酸钠与季铵盐回流得到标题化合物.在合成中得到了3种未见文献报道的新化合物.而采用文献原有的方法,使用过氧化苯甲酰或偶氮异丁腈在常压下反应则没有获得目标产物.

The distributed neural system for top-down letter processing: an fMRI study

Science.gov (United States)

Liu, Jiangang; Feng, Lu; Li, Ling; Tian, Jie

2011-03-01

This fMRI study used Psychophysiological interaction (PPI) to investigate top-down letter processing with an illusory letter detection task. After an initial training that became increasingly difficult, participant was instructed to detect a letter from pure noise images where there was actually no letter. Such experimental paradigm allowed for isolating top-down components of letter processing and minimizing the influence of bottom-up perceptual input. A distributed cortical network of top-down letter processing was identified by analyzing the functional connectivity patterns of letter-preferential area (LA) within the left fusiform gyrus. Such network extends from the visual cortex to high level cognitive cortexes, including the left middle frontal gyrus, left medial frontal gyrus, left superior parietal gyrus, bilateral precuneus, and left inferior occipital gyrus. These findings suggest that top-down letter processing contains not only regions for processing of letter phonology and appearance, but also those involved in internal information generation and maintenance, and attention and memory processing.

Nonlinear radiated MHD flow of nanoliquids due to a rotating disk with irregular heat source and heat flux condition

Science.gov (United States)

Mahanthesh, B.; Gireesha, B. J.; Shehzad, S. A.; Rauf, A.; Kumar, P. B. Sampath

2018-05-01

This research is made to visualize the nonlinear radiated flow of hydromagnetic nano-fluid induced due to rotation of the disk. The considered nano-fluid is a mixture of water and Ti6Al4V or AA7072 nano-particles. The various shapes of nanoparticles like lamina, column, sphere, tetrahedron and hexahedron are chosen in the analysis. The irregular heat source and nonlinear radiative terms are accounted in the law of energy. We used the heat flux condition instead of constant surface temperature condition. Heat flux condition is more relativistic and according to physical nature of the problem. The problem is made dimensionless with the help of suitable similarity constraints. The Runge-Kutta-Fehlberg scheme is adopted to find the numerical solutions of governing nonlinear ordinary differential systems. The solutions are plotted by considering the various values of emerging physical constraints. The effects of various shapes of nanoparticles are drawn and discussed.

Radiation damage in heavy irradiated aluminum nitride

Energy Technology Data Exchange (ETDEWEB)

Atobe, Kozo; Honda, Makoto; Fukuoka, Noboru [Naruto Univ. of education, Tokushima (Japan); Okada, Moritami; Nakagawa, Masuo

1996-04-01

AlN, one of candidate for ceramic materials used in nuclear fusion reactor, was irradiated by fast and thermal neutrons. The high concentration of irradiated defects and the nuclear transformation elements were detected by electron spin resonance (ESR) and x-ray photoelectron spectroscopy (XPS) method. The exposure of fast neutron and thermal neutron were 1.2x10{sup 20}n/cm{sup 2} and 1.2x10{sup 21}n/cm{sup 2}, respectively. The spreads of ESR spectra of ultra hyperfine structure depending on interaction between {sup 27}Al nuclear spin and electron trapped in tetrahedron consisted of Al atoms was found in the spectra of heavy irradiated AlN. F type defects was estimated 10{sup 19}n/cm{sup 3}. Photoelectrons from 2s and 2p in {sup 28}Si which produced in process of {beta}-decay of {sup 27}Al(n,{gamma}){sup 28}Al were observed in XPS spectra of irradiated samples. (S.Y.)

Melting behavior of a model molecular crystalline GeI4

International Nuclear Information System (INIS)

Fuchizaki, Kazuhiro; Asano, Yuta

2015-01-01

A model molecular crystalline GeI 4 was examined using molecular dynamics simulation. The model was constructed in such a way that rigid tetrahedral molecules interact with each other via Lennard-Jones potentials whose centers are located at the vertices of a tetrahedron. Because no other interaction that can “soften” the intermolecular interaction was introduced, the melting curve of the model crystalline material does not exhibit the anomaly that was found for the real substance. However, the current investigation is useful in that it could settle the upper bound of pressure below which the model can predict properties of the molecular liquid. Moreover, singularity-free nature of the melting curve allowed us to analytically treat the melting curve in the light of the Kumari-Dass-Kechin equation. As a result, we could definitely conclude that the well-known Simon equation for the melting curve is merely an approximate expression. The condition for the validity of Simon’s equation was identified. (author)

BPS/CFT Correspondence III: Gauge Origami Partition Function and qq-Characters

Science.gov (United States)

Nekrasov, Nikita

2018-03-01

We study generalized gauge theories engineered by taking the low energy limit of the Dp branes wrapping {X × {T}^{p-3}}, with X a possibly singular surface in a Calabi-Yau fourfold Z. For toric Z and X the partition function can be computed by localization, making it a statistical mechanical model, called the gauge origami. The random variables are the ensembles of Young diagrams. The building block of the gauge origami is associated with a tetrahedron, whose edges are colored by vector spaces. We show the properly normalized partition function is an entire function of the Coulomb moduli, for generic values of the {Ω} -background parameters. The orbifold version of the theory defines the qq-character operators, with and without the surface defects. The analytic properties are the consequence of a relative compactness of the moduli spaces M({ěc n}, k) of crossed and spiked instantons, demonstrated in "BPS/CFT correspondence II: instantons at crossroads, moduli and compactness theorem".

Real-time simulation of soft tissue deformation and electrocautery procedures in laparoscopic rectal cancer radical surgery.

Science.gov (United States)

Sui, Yuan; Pan, Jun J; Qin, Hong; Liu, Hao; Lu, Yun

2017-12-01

Laparoscopic surgery (LS), also referred to as minimally invasive surgery, is a modern surgical technique which is widely applied. The fulcrum effect makes LS a non-intuitive motor skill with a steep learning curve. A hybrid model of tetrahedrons and a multi-layer triangular mesh are constructed to simulate the deformable behavior of the rectum and surrounding tissues in the Position-Based Dynamics (PBD) framework. A heat-conduction based electric-burn technique is employed to simulate the electrocautery procedure. The simulator has been applied for laparoscopic rectum cancer surgery training. From the experimental results, trainees can operate in real time with high degrees of stability and fidelity. A preliminary study was performed to evaluate the realism and usefulness. This prototype simulator has been tested and verified by colorectal surgeons through a pilot study. They believed both the visual and the haptic performance of the simulation are realistic and helpful to enhance laparoscopic skills. Copyright © 2017 John Wiley & Sons, Ltd.

Steady, three-dimensional, internally heated convection

International Nuclear Information System (INIS)

Schubert, G.; Glatzmaier, G.A.; Travis, B.

1993-01-01

Numerical calculations have been carried out of steady, symmetric, three-dimensional modes of convection in internally heated, infinite Prandtl number, Boussinesq fluids at a Rayleigh number of 1.4x10 4 in a spherical shell with inner/outer radius of 0.55 and in a 3x3x1 rectangular box. Multiple patterns of convection occur in both geometries. In the Cartesian geometry the patterns are dominated by cylindrical cold downflows and a broad hot upwelling. In the spherical geometry the patterns consist of cylindrical cold downwellings centered either at the vertices of a tetrahedron or the centers of the faces of a cube. The cold downflow cylinders are immersed in a background of upwelling within which there are cylindrical hot concentrations (plumes) and hot halos around the downflows. The forced hot upflow return plumes of internally heated spherical convection are fundamentally different from the buoyancy-driven plumes of heated from below convection

From Two- to Three-Dimensional Structures of a Supertetrahedral Boran Using Density Functional Calculations.

Science.gov (United States)

Getmanskii, Iliya V; Minyaev, Ruslan M; Steglenko, Dmitrii V; Koval, Vitaliy V; Zaitsev, Stanislav A; Minkin, Vladimir I

2017-08-14

With help of the DFT calculations and imposing of periodic boundary conditions the geometrical and electronic structures were investigated of two- and three-dimensional boron systems designed on the basis of graphane and diamond lattices in which carbons were replaced with boron tetrahedrons. The consequent studies of two- and three-layer systems resulted in the construction of a three-dimensional supertetrahedral borane crystal structure. The two-dimensional supertetrahedral borane structures with less than seven layers are dynamically unstable. At the same time the three-dimensional superborane systems were found to be dynamically stable. Lack of the forbidden electronic zone for the studied boron systems testifies that these structures can behave as good conductors. The low density of the supertetrahedral borane crystal structures (0.9 g cm -3 ) is close to that of water, which offers the perspective for their application as aerospace and cosmic materials. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Two Comments on Bond Angles

Science.gov (United States)

Glaister, P.

1997-09-01

Tetrahedral Bond Angle from Elementary Trigonometry The alternative approach of using the scalar (or dot) product of vectors enables the determination of the bond angle in a tetrahedral molecule in a simple way. There is, of course, an even more straightforward derivation suitable for students who are unfamiliar with vectors, or products thereof, but who do know some elementary trigonometry. The starting point is the figure showing triangle OAB. The point O is the center of a cube, and A and B are at opposite corners of a face of that cube in which fits a regular tetrahedron. The required bond angle alpha = AÔB; and using Pythagoras' theorem, AB = 2(square root 2) is the diagonal of a face of the cube. Hence from right-angled triangle OEB, tan(alpha/2) = (square root 2) and therefore alpha = 2tan-1(square root 2) is approx. 109° 28' (see Fig. 1).

New gamma-pyrone propionates from the Indian Ocean sacoglossam Placobranchus ocellatus

Digital Repository Service at National Institute of Oceanography (India)

Manzo, E.; Ciavatta, M.L.; Gavagnin, M.; Mollo, E.; Wahidullah, S.; Cimino, G.

methine H-7 and the methyl at C-12. The perox- ide bridge was a-oriented with respect to the plane of the 16 1.88 s 7.2 q — 1.84 s 7.0 q — 17 1.98 s 9.8 q — 1.94 s 12.9 q — 18 1.25 s 15.5 q H-7, H-13 1.51 s 18.9 q H-7, H-13 19 1.78 s 23.4 q H-7 1.20 s 21...–468 1 5 6 7 9 11 13 15 16 18 1920 21 1 3 5 6 9 11 12 13 7 O OMe O 2 O OMe O O O O 9 1 3 5 O OMe O H H H O O 17 466 E. Manzo et al. / Tetrahedron C 22 H 30 O 3 . The 1 H NMR spectrum (Table 1) immedia- tely suggested a polypropionate skeleton. In fact...

Modeling of amorphous SiCxO6/5 by classical molecular dynamics and first principles calculations

Science.gov (United States)

Liao, Ningbo; Zhang, Miao; Zhou, Hongming; Xue, Wei

2017-02-01

Polymer-derived silicon oxycarbide (SiCO) presents excellent performance for high temperature and lithium-ion battery applications. Current experiments have provided some information on nano-structure of SiCO, while it is very challenging for experiments to take further insight into the molecular structure and its relationship with properties of materials. In this work, molecular dynamics (MD) based on empirical potential and first principle calculation were combined to investigate amorphous SiCxO6/5 ceramics. The amorphous structures of SiCO containing silicon-centered mix bond tetrahedrons and free carbon were successfully reproduced. The calculated radial distribution, angular distribution and Young’s modulus were validated by current experimental data, and more details on molecular structure were discussed. The change in the slope of Young’s modulus is related to the glass transition temperature of the material. The proposed modeling approach can be used to predict the properties of SiCO with different compositions.

Conformal bootstrap, universality and gravitational scattering

Directory of Open Access Journals (Sweden)

Steven Jackson

2015-12-01

Full Text Available We use the conformal bootstrap equations to study the non-perturbative gravitational scattering between infalling and outgoing particles in the vicinity of a black hole horizon in AdS. We focus on irrational 2D CFTs with large c and only Virasoro symmetry. The scattering process is described by the matrix element of two light operators (particles between two heavy states (BTZ black holes. We find that the operator algebra in this regime is (i universal and identical to that of Liouville CFT, and (ii takes the form of an exchange algebra, specified by an R-matrix that exactly matches the scattering amplitude of 2+1 gravity. The R-matrix is given by a quantum 6j-symbol and the scattering phase by the volume of a hyperbolic tetrahedron. We comment on the relevance of our results to scrambling and the holographic reconstruction of the bulk physics near black hole horizons.

Radiation damage in heavy irradiated aluminum nitride

International Nuclear Information System (INIS)

Atobe, Kozo; Honda, Makoto; Fukuoka, Noboru; Okada, Moritami; Nakagawa, Masuo.

1996-01-01

AlN, one of candidate for ceramic materials used in nuclear fusion reactor, was irradiated by fast and thermal neutrons. The high concentration of irradiated defects and the nuclear transformation elements were detected by electron spin resonance (ESR) and x-ray photoelectron spectroscopy (XPS) method. The exposure of fast neutron and thermal neutron were 1.2x10 20 n/cm 2 and 1.2x10 21 n/cm 2 , respectively. The spreads of ESR spectra of ultra hyperfine structure depending on interaction between 27 Al nuclear spin and electron trapped in tetrahedron consisted of Al atoms was found in the spectra of heavy irradiated AlN. F type defects was estimated 10 19 n/cm 3 . Photoelectrons from 2s and 2p in 28 Si which produced in process of β-decay of 27 Al(n,γ) 28 Al were observed in XPS spectra of irradiated samples. (S.Y.)

Structures of Bi14WO24 and Bi14MoO24 from neutron powder diffraction data

International Nuclear Information System (INIS)

Ling, C.D.; Withers, R.L.; Thompson, J.G.; Schmid, S.

1999-01-01

The (isomorphous) structures of Bi 14 WO 24 , tetradecabismuth tungsten tetracosaoxide, and Bi 14 MoO 24 , tetradecabismuth molybdenum tetracosaoxide, have been solved and refined using neutron powder diffraction data in the space group I4/m. The metal-atom array is fully ordered in terms of composition, and in terms of atomic positions deviates only slightly from a fluorite-type δ-Bi 2 O 3 -related parent structure. Three independent O-atom sites (accounting for 70 out of 78 O atoms in the unit cell) are also very close to fluorite-type parent positions. The remaining two O-atom sites, which coordinate W, exhibit partial occupancies and displacive disorder, neither of which could be better modelled by lowering of symmetry. The W site is coordinated by four O atoms in highly distorted tetrahedral coordination, the tetrahedron necessarily being orientationally disordered on that site. Nonetheless, the structure appears to be chemically reasonable. (orig.)

Theoretical prediction of the mechanical properties of zeolitic imidazolate frameworks (ZIFs)

KAUST Repository

Zheng, Bin; Zhu, Yihan; Fu, Fang; Wang, Lian Li; Wang, Jinlei; Du, Huiling

2017-01-01

A good resistance against mechanical stress is essential for the utilization of metal-organic frameworks (MOFs) in practical applications such as gas sorption, separation, catalysis or energy conversion. Here, we report on the successful modification of the mechanical properties of zeolitic imidazolate frameworks (ZIFs) achieved through a substitution of the terminal group. The mechanical modulus of SALEM-2 was found to significantly improve when the -H groups at position 2 of the imidazole linkers were replaced with electron withdrawing groups (-CHO, -Cl, or -Br). The charge distribution and electron density were analyzed to reveal the mechanism behind the observed variation of the elastic stiffness. Furthermore, ZIF-I with a -I group at position 2 of the imidazole linkers was predicted to exhibit an excellent mechanical strength in our study and then prepared experimentally. The results indicate that an inconspicuous change of the structure of ZIFs, i.e., additional groups strengthening the ZnN4 tetrahedron, will lead to a stiffer framework.

Crystal structure of CsTb(PO3)4 compound

International Nuclear Information System (INIS)

Palkina, K.K.; Maksimova, S.I.; Kuznetsov, V.G.; Chibiskova, N.T.

1978-01-01

The X-ray structural study of compounds of the CsLn(PO 3 ) 4 series has been made. Found is the presence of two structural types for CsPr(PO 3 ) 4 (cubic and monoclinic modifications), one type for CsNd(PO 3 ) 4 (cubic modification) and for CsTb(PO 3 ) 4 (monoclinic modification). For the CsTb(PO 3 ) 4 monocrystal the lattice parameters are determined: a=7.032 +- 0.001; b=8.705 +- 0.001; c=9.051 +- 0.001 A; α=90 deg, β=90 deg, γ=100 deg, Z=2, V=545.68 A 3 , dsub(exp)=3.70 g/cm 3 . The structure character is presented as infinite chains of (PO 4 ) tetrahedrons, stretched along the ''C'' period. Tb and Cs atoms are rounded by 8 atoms of oxygen. Tb polyhedron are irregular octaapexes or strongly deformed tetragonal antiprisms. Tb-Tb shortest distance is 6.59 A

Numerical electromagnetic frequency domain analysis with discrete exterior calculus

Science.gov (United States)

Chen, Shu C.; Chew, Weng Cho

2017-12-01

In this paper, we perform a numerical analysis in frequency domain for various electromagnetic problems based on discrete exterior calculus (DEC) with an arbitrary 2-D triangular or 3-D tetrahedral mesh. We formulate the governing equations in terms of DEC for 3-D and 2-D inhomogeneous structures, and also show that the charge continuity relation is naturally satisfied. Then we introduce a general construction for signed dual volume to incorporate material information and take into account the case when circumcenters fall outside triangles or tetrahedrons, which may lead to negative dual volume without Delaunay triangulation. Then we examine the boundary terms induced by the dual mesh and provide a systematical treatment of various boundary conditions, including perfect magnetic conductor (PMC), perfect electric conductor (PEC), Dirichlet, periodic, and absorbing boundary conditions (ABC) within this method. An excellent agreement is achieved through the numerical calculation of several problems, including homogeneous waveguides, microstructured fibers, photonic crystals, scattering by a 2-D PEC, and resonant cavities.

Raman and optical absorption spectroscopic investigation of Yb-Er codoped phosphate glasses containing SiO2

Institute of Scientific and Technical Information of China (English)

Youkuo Chen; Lei Wen; Lili Hu; Wei Chen; Y. Guyot; G. Boulon

2009-01-01

Yb-Er codoped Na2O-Al2O3-P2Os-xSiO2 glasses containing 0 鈥? 20 mol% SiO2 were prepared successfully. The addition of SiO2 to the phosphate glass not only lengthens the bond between P5+ and non-bridging oxygen but also reduces the number of P=O bond. In contrast with silicate glass in which there is only four-fold coordinated Si4+, most probably there coexist [SiO4] tetrahedron and [SiO6] octahedron in our glasses. Within the range of 0 鈥? 20 mol% SiO2 addition, the stimulated emission cross-section of Er3+ ion only decreases no more than 10%. The Judd-Ofelt intensity parameters of Er3+, 惟.2 does not change greatly, but 惟74 and 惟6 decrease obviously with increasing SiO2 addition, because the bond between Er + and O2- is more strongly covalently bonded.

Synthesis and luminescent properties of Y(As, Nb, P, V)O4:Eu3+ red phosphors by combinatorial chemistry method

International Nuclear Information System (INIS)

Zeon, Il Woon; Park, Hee Dong; Sohn, Kee Sun; Ryu, Seung Kon

2001-01-01

Eu doped YRO 4 (R=As, Nb, P, V)red phosphors were prepared by the combinatorial chemistry method. The quaternary material library of tetrahedron-type composition array was designed to investigate the luminescence of the host material under UV and VUV excitations (254, 147 nm). The photoluminescent characteristics of the samples were comparable to the commercially available red phosphors such as (Y, Gd)BO 3 :Eu 3+ and Y 2 O 3 :Eu 3+ . In view of the luminescence yield, V rich region was found to be optimum under UV excitation. But the results under VUV excitation were different from those of UV excitation, the samples of the composition containing a large amount of P shows the highest luminescence. Especially, higher luminescence was obtained in Y 0.9 (As 0.06 Nb 0.06 P 0.83 V 0.06 )O 4 :Eu 0.1 phosphors than commercial (Y, Gd)BO 3 red phosphors under 147 nm excitation

Theoretical prediction of the mechanical properties of zeolitic imidazolate frameworks (ZIFs)

KAUST Repository

Zheng, Bin

2017-08-25

A good resistance against mechanical stress is essential for the utilization of metal-organic frameworks (MOFs) in practical applications such as gas sorption, separation, catalysis or energy conversion. Here, we report on the successful modification of the mechanical properties of zeolitic imidazolate frameworks (ZIFs) achieved through a substitution of the terminal group. The mechanical modulus of SALEM-2 was found to significantly improve when the -H groups at position 2 of the imidazole linkers were replaced with electron withdrawing groups (-CHO, -Cl, or -Br). The charge distribution and electron density were analyzed to reveal the mechanism behind the observed variation of the elastic stiffness. Furthermore, ZIF-I with a -I group at position 2 of the imidazole linkers was predicted to exhibit an excellent mechanical strength in our study and then prepared experimentally. The results indicate that an inconspicuous change of the structure of ZIFs, i.e., additional groups strengthening the ZnN4 tetrahedron, will lead to a stiffer framework.

Ab initio elastic properties and tensile strength of crystalline hydroxyapatite.

Science.gov (United States)

Ching, W Y; Rulis, Paul; Misra, A

2009-10-01

We report elastic constant calculation and a "theoretical" tensile experiment on stoichiometric hydroxyapatite (HAP) crystal using an ab initio technique. These results compare favorably with a variety of measured data. Theoretical tensile experiments are performed on the orthorhombic cell of HAP for both uniaxial and biaxial loading. The results show considerable anisotropy in the stress-strain behavior. It is shown that the failure behavior of the perfect HAP crystal is brittle for tension along the z-axis with a maximum stress of 9.6 GPa at 10% strain. Biaxial failure envelopes from six "theoretical" loading tests show a highly anisotropic pattern. Structural analysis of the crystal under various stages of tensile strain reveals that the deformation behavior manifests itself mainly in the rotation of the PO(4) tetrahedron with concomitant movements of both the columnar and axial Ca ions. These results are discussed in the context of mechanical properties of bioceramic composites relevant to mineralized tissues.

Crystal structures of the solid solutions Na3Zn0.912Cd0.088B5O10 and Na3Zn0.845Mg0.155B5O10

Directory of Open Access Journals (Sweden)

Xue-An Chen

2017-11-01

Full Text Available Two new pentaborates, trisodium zinc cadmium pentaborate, Na3Zn0.912Cd0.088B5O10, and trisodium zinc magnesium pentaborate, Na3Zn0.845Mg0.155B5O10, have been synthesized by high-temperature solution reactions at 1023 K. Their crystal structures were determined by single-crystal X-ray diffraction. Both solid solutions crystallize in the orthorhombic form of the parent compound Na3ZnB5O10 (space group type Pbca, Z = 8 and contain the double ring [B5O10]5− anion composed of one BO4 tetrahedron and four BO3 triangles as the basic structural motif. The anions are bridged by tetrahedrally coordinated and occupationally disordered M2+ (M = Zn/Cd, Zn/Mg cations via common O atoms to form [MB5O10]n3n− layers. The intralayer intersecting channels and the interlayer voids are occupied by Na+ cations to balance the charge.

An efficicient data structure for three-dimensional vertex based finite volume method

Science.gov (United States)

Akkurt, Semih; Sahin, Mehmet

2017-11-01

A vertex based three-dimensional finite volume algorithm has been developed using an edge based data structure.The mesh data structure of the given algorithm is similar to ones that exist in the literature. However, the data structures are redesigned and simplied in order to fit requirements of the vertex based finite volume method. In order to increase the cache efficiency, the data access patterns for the vertex based finite volume method are investigated and these datas are packed/allocated in a way that they are close to each other in the memory. The present data structure is not limited with tetrahedrons, arbitrary polyhedrons are also supported in the mesh without putting any additional effort. Furthermore, the present data structure also supports adaptive refinement and coarsening. For the implicit and parallel implementation of the FVM algorithm, PETSc and MPI libraries are employed. The performance and accuracy of the present algorithm are tested for the classical benchmark problems by comparing the CPU time for the open source algorithms.

Comparative evaluations of the Monte Carlo-based light propagation simulation packages for optical imaging

Directory of Open Access Journals (Sweden)

Lin Wang

2018-01-01

Full Text Available Monte Carlo simulation of light propagation in turbid medium has been studied for years. A number of software packages have been developed to handle with such issue. However, it is hard to compare these simulation packages, especially for tissues with complex heterogeneous structures. Here, we first designed a group of mesh datasets generated by Iso2Mesh software, and used them to cross-validate the accuracy and to evaluate the performance of four Monte Carlo-based simulation packages, including Monte Carlo model of steady-state light transport in multi-layered tissues (MCML, tetrahedron-based inhomogeneous Monte Carlo optical simulator (TIMOS, Molecular Optical Simulation Environment (MOSE, and Mesh-based Monte Carlo (MMC. The performance of each package was evaluated based on the designed mesh datasets. The merits and demerits of each package were also discussed. Comparative results showed that the TIMOS package provided the best performance, which proved to be a reliable, efficient, and stable MC simulation package for users.

Small clusters with anisotropic antiferromagnetic exchange in a magnetic field

International Nuclear Information System (INIS)

Parkinson, J B; Elliott, R J; Timonen, J

2004-01-01

We consider small symmetric clusters of magnetic atoms (spins) with anisotropic exchange interaction between the atoms in a magnetic field at zero temperature. The inclusion of the anisotropy leads to a wealth of different phases as a function of the applied magnetic field. These are not phases in the thermodynamic sense with critical properties but rather physical structures with different arrangements of the spins and hence different symmetries. We study the spatial symmetry of these phases, for the classical and quantum cases. Results are presented mainly for three frustrated systems, the triangle, the tetrahedron and the five-atom ring, which have many interesting features. In the classical limit we obtain phase diagrams in which some of the phase changes occur because of energy crossings and others due to energy bifurcations, corresponding to 'first-' and 'second-order' changes. In the quantum case we show how the symmetries of the states are related to the corresponding classical symmetries

Professional Citation Practices in Child Maltreatment Forensic Letters

Science.gov (United States)

Schryer, Catherine F.; Bell, Stephanie; Mian, Marcellina; Spafford, Marlee M.; Lingard, Lorelei

2011-01-01

Using rhetorical genre theory and research on reported speech, this study investigates the citation practices in 81 forensic letters written by paediatricians and nurse practitioners that provide their opinion for the courts as to whether a child has experienced maltreatment. These letters exist in a complex social situation where a lack of…

Readability of "Dear Patient" device advisory notification letters created by a device manufacturer.

Science.gov (United States)

Mueller, Luke A; Sharma, Arjun; Ottenberg, Abigale L; Mueller, Paul S

2013-04-01

In 2006, the Heart Rhythm Society (HRS) recommended that cardiovascular implantable electronic device (CIED) manufacturers use advisory notification letters to communicate with affected patients. To evaluate the readability of the HRS sample "patient device advisory notification" letter and those created by 1 CIED manufacturer. The HRS sample letter and 25 Boston Scientific Corporation letters dated from 2005 through 2011 were evaluated by using 6 readability tests. Readability (Flesch-Kincaid score) of the HRS sample letter was grade level 12.5, and median readability of the device manufacturer letters was grade level 12.8 (range 10.8-18.9). Similar results were obtained by using other readability scales. No letters had readability scores at the National Work Group on Literacy and Health's recommended reading level-fifth grade; the letters' readability exceeded this recommended level by an average of 7.7 grades (95% confidence interval 6.9-8.5; Preadability scores at the average reading level of US adults-eighth grade; the letters' readability exceeded this level by an average of 4.7 grades (95% confidence interval 3.9-5.5; Preadability of the HRS sample letter and those created by a CIED manufacturer significantly exceeded the recommended and average US adults' reading skill levels. Such letters are unlikely to be informative to many patients. CIED manufacturers should ensure that advisory letters are comprehensible to most affected patients. Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Visual and Artistic Functions of Letters Khaghani’s Poetry

Directory of Open Access Journals (Sweden)

Dr. M. Zolfaghari

Full Text Available The intensity of emotion and vibration of meaning in the poet's mind causes him to go beyond the ordinary language and through metaphors, similes and linguistic preparation he conveys intellectual and emotional meanings. He has a sharp eye and a sensitive spirit and creative temprement and by inventing new images shows the creativity and imagination in various arenas and attempts in the way of literary strength and creating personal style and this point more than anything else must be done by presenting images and newness. Perhaps in the sixth century, and especially in Azerbaijani school, more than other periods, poets have been looking for creating innovative style in eloquence. Their major attempts were mainly in imaging, it was a wide field that they have competed and it is natural that in this illustration the alphabet letters would be very helpful. Khaghani poetry as one of the greatest poets of this school has the perfect poetrical book of painting and meaning, and delicated pattern in new and different scientific, cultural and religious paintings and letters are a broad range of elements that put a new field in front of the poet and he is aware of the potential features of the letters and also the new images and the artistic creativity.This paper shows descriptive - analytical study of various aspects of Khaghani’s poetry and frequency of letters in the alphabet, authentic images based on alphabet, taken at different pseudo relevance of poetry in the context of multiple semantic and literal characters, making figures of speech based on literary characters, images and characters and the sense of connection . . . which has been shown in his poetry.Letter has double and even multiple uses in Khaghani poetic works (divan and more than the construction of words which is the real and common sense that is used as an artistic. There is a world in the heart of every letter, word and morpheme lies in the poet's point of view is the last and

Letter Frequency Analysis of Lithuanian and Other Languages Using the Latin Alphabet

Directory of Open Access Journals (Sweden)

Gintautas Grigas

2015-12-01

Full Text Available It is important to evaluate specificities of alphabets, particularly the letter frequencies while designing keyboards, analyzing texts, designing games based on alphabets, and doing some text mining. In order to adequately compare lettter frequences of Lithuanian language to other languages in the Internet space, Wikipedia source was selected which content is common to different languages. The method of letter frequency jumps is used. The main attention is paid to the analysis of letter frequencies at the boundary between native letters and foreign letters used in Lithuanian and other languages.

Letter-By-Letter Reading: Natural Recovery and Response to Treatment

Directory of Open Access Journals (Sweden)

Pélagie M. Beeson

2005-01-01

Full Text Available The present investigation provides a longitudinal study of an individual (RB with acquired alexia following left posterior cerebral artery stroke. At initial testing, RB exhibited acquired alexia characterized by letter-by-letter (LBL reading, mild anomic aphasia, and acquired agraphia. Repeated measures of reading accuracy and rate were collected for single words and text over the course of one year, along with probes of naming and spelling abilities. Improvements associated with natural recovery (i.e., without treatment were documented up to the fourth month post onset, when text reading appeared to be relatively stable. Multiple oral reading (MOR treatment was initiated at 22 weeks post-stroke, and additional improvements in reading rate and accuracy for text were documented that were greater than those expected on the basis of spontaneous recovery alone. Over the course of one year, reading reaction times for single words improved, and the word-length effect that is the hallmark of LBL reading diminished. RB's response to treatment supports the therapeutic value of MOR treatment to in LBL readers. His residual impairment of reading and spelling one-year post stroke raised the question as to whether further progress was impeded by degraded orthographic knowledge.

Standardized Letter of Recommendation for Otolaryngology Residency Selection

Science.gov (United States)

Perkins, Jonathan N.; Liang, Conan; McFann, Kim; Abaza, Mona M.; Streubel, Sven-Olrik; Prager, Jeremy D.

2013-01-01

Objectives/Hypothesis Develop a standardized letter of recommendation (SLOR) for otolaryngology residency application that investigates the qualities desired in residents and letter writer’s experience. Compare this SLOR to narrative letters of recommendation (NLOR). Study Design Prospective SLOR/NLOR Comparison. Methods The SLOR was sent to a NLOR writer for each applicant. The applicant’s NLOR/SLOR pair was blinded and ranked in seven categories by three reviewers. Inter-rater reliability and NLOR/SLOR rankings were compared. Means of cumulative NLOR and SLOR scores were compared to our departmental rank list. Results Thirty-one SLORs (66%) were collected. The SLORs had higher inter-rater reliability for applicant’s qualifications for otolaryngology, global assessment, summary statement, and overall letter ranking. Writer’s background, comparison to contemporaries/predecessors, and letter review ease had higher inter-rater reliability on the NLORs. Mean SLOR rankings were higher for writer’s background (p=0.0007), comparison of applicant to contemporaries/predecessors (p=0.0031), and letter review ease (p<0.0001). Mean SLOR writing time was 4.17±2.18 minutes. Mean ranking time was significantly lower (p<0.0001) for the SLORs (39.24±23.45 seconds) compared to the NLORs (70.95±40.14 seconds). Means of cumulative SLOR scores correlated with our rank list (p=0.004), whereas means of cumulative NLOR scores did not (p=0.18). Means of cumulative NLOR and SLOR scores did not correlate (p=0.26). Conclusions SLORs require little writing time, save reviewing time, and are easier to review compared to NLORs. Our SLOR had higher inter-rater reliability in 4 of 7 categories and was correlated with our rank list. This tool conveys standardized information in an efficient manner. PMID:23172646

Should intellectual property be disseminated by "forwarding" rejected letters without permission?

Science.gov (United States)

Gupta, V K

1996-08-01

Substantive scientific letter writing is a cost-effective mode of complementing observational and experimental research. The value of such philosophically uncommitted and unsponsored well-balanced scientific activity has been relegated. Critical letter writing entails the abilities to: maintain rational scepticism; refuse to conform in order to explain data; persist in keeping common sense centre-stage; exercise logic to evaluate the biological significance of mathematical figures, including statistics, and the ability to sustain the will to share insights regarding disease mechanisms on an ostensibly lower research platform. During peer review, innovative letter writing may share the occasionally unfortunate fate of innovative research. Rejected scientific letters do not automatically lose copyright. Periodicals with high letter loads will see some valuable contributions wasted, but that is the price for maintaining autonomy in scientific publication. The scientific community is an integrated whole that must respect the rights of authors at all levels. Unauthorised forwarding of rejected letters sets the dangerous precedent of justifying unjust means.

Letters to a Young Baller: Exploring Epistolary Criticism

Science.gov (United States)

Chawansky, Megan

2010-01-01

This article explores the possibilities of epistolary criticism within the realm of sport studies and aspires to encourage scholars to consider the use of non-traditional sport memorabilia and source materials when telling emotive stories about sport and sport practices. The use of letters and the letter-writing format to tell a personal narrative…

Melanie Klein's letters addressed to Marcelle Spira (1955-1960).

Science.gov (United States)

Quinodoz, Jean-Michel

2009-12-01

Between 1955 and 1960, Melanie Klein wrote some 45 hitherto unpublished letters to Marcelle Spira, the Swiss psychoanalyst living at that time in Geneva. In 2006, after Spira's death, these letters were deposited with the Raymond de Saussure Psychoanalysis Centre in Geneva. They are the only known letters that Klein addressed to her psychoanalyst colleagues. Several topics are mentioned in them: (1) the meetings between the two women in Geneva and London; (2) Spira's contribution to Boulanger's translation into French of The Psychoanalysis of Children, which Klein herself carefully revised; (3) the papers that Klein was at that time working on, including Envy and Gratitude; (4) Spira's own work; (5) the difficulties that Spira, a Kleinian psychoanalyst who trained in Buenos Aires, was encountering in her attempt to be admitted to the Swiss Psychoanalytical Society; and (6) a few items of personal and family news. In addition to the invaluable historical information that these letters provide, they offer us a very moving epistolary self-portrait of Melanie Klein, enabling us to discover her personality in the final years of her life - she died in September 1960, just two months after writing her last letter to Spira.

[Representation of letter position in visual word recognition process].

Science.gov (United States)

Makioka, S

1994-08-01

Two experiments investigated the representation of letter position in visual word recognition process. In Experiment 1, subjects (12 undergraduates and graduates) were asked to detect a target word in a briefly-presented probe. Probes consisted of two kanji words. The latters which formed targets (critical letters) were always contained in probes. (e.g. target: [symbol: see text] probe: [symbol: see text]) High false alarm rate was observed when critical letters occupied the same within-word relative position (left or right within the word) in the probe words as in the target word. In Experiment 2 (subject were ten undergraduates and graduates), spaces adjacent to probe words were replaced by randomly chosen hiragana letters (e.g. [symbol: see text]), because spaces are not used to separate words in regular Japanese sentences. In addition to the effect of within-word relative position as in Experiment 1, the effect of between-word relative position (left or right across the probe words) was observed. These results suggest that information about within-word relative position of a letter is used in word recognition process. The effect of within-word relative position was explained by a connectionist model of word recognition.

[Patients' letters and pre-modern medical lay-culture].

Science.gov (United States)

Stolberg, Michael

2007-01-01

Consulting by letter was fairly common practice among the educated, upper classes of early modern Europe. Surviving letters of consultation written by patients, relatives or friends count among the most valuable source for the analysis of pre-modern experiences of disease and the body. This essay gives a brief overview of the various types of consultation letters and related documents which resulted from this practice before tracing the historical development of epistolary consultations from the late Middle Ages through the heyday medical correspondence in the 18th c. before its decline in the 19th c. It presents "experience", "self-fashioning" and "discourse" as three particularly fruitful levels of analysis on which patients' letters can be used within the wider framework of a cultural history of medicine. These three levels of analysis, or three distinct approaches, enable historians to access a greater awareness of the ways in which the experience of illness and the body is culturally framed with an analysis of the performative effects of patients' narratives and the influence of medical discourse among the wider society.

Collected Letters of José Martí: a linguistic approach

Directory of Open Access Journals (Sweden)

Guerra, Ana Jústiz

2012-01-01

Full Text Available Any approach to José Marti’s literary production should consider the study of his collected letters, which are noticeable for its content and expressive devices. This article synthesizes the criteria of former researchers who have considered Marti’s collected letters as a privileged genre among the multiple and diverse cultivated by the Apostle (speeches, dramas, essays, journal article, short stories and literary criticism. The collected letters takes a large proportion of his prolific literary production and its expressive force has been widely recognized as a source of inspiration for other poets. His collection of letters is outstanding and lasting in time for its expressive magnificence, its depth of content and precise choice of words. Originally written for a definite addressee, the letters are currently read by new generations of readers, who rediscover a new message in each. Topic considered in this article is part of a wider range study which is been prepared as Ph. D. thesis.

The Complaint Letter and Response.

Science.gov (United States)

Shukla, P. K.

1998-01-01

Describes an assignment in which students write a letter of complaint, and discusses how this assignment aids students in seeing the importance of effective written communication to their daily lives. (SR)

Scientific Letter: Monosymptomatic Hypochondriacal Psychosis ...

African Journals Online (AJOL)

Scientific Letter: Monosymptomatic Hypochondriacal Psychosis (somatic delusional disorder): A report of two cases. ... African Journal of Psychiatry. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives.

Particles and nuclei, letters

International Nuclear Information System (INIS)

2004-01-01

The present collection of letters from JINR, Dubna, contains thirteen separate letters on start-to-end simulations of SASE FEL at the TESLA test facility, possible ways of improvement of the FEM oscillator with a Bragg resonator, the status and perspectives of the electron cooling method development, crystalline ion beams in storage rings, latest results of modeling of LHC beam injection, charge exchange injection in a synchrotron equipped with an electron cooling system, fringe and hysteresis effects in electron guns, nonstationary regimes of electron flow formation in secondary emission inverse coaxial diodes, a proposal of the experiment testing of the fine structure of the Vavilov-Cherenkov radiation, computer simulation of the electron beam dynamics at the accelerator structure and the injector of S-band linac with energies of 3 and 10 MeV, calculation of the electron beam dynamics of the accelerator LUE-200, the accelerator-accumulation facility ITEP-TWAC and accelerators-drivers of electronuclear facilities

Burroughs's Postcolonial Visions in The Yage Letters

OpenAIRE

Keomany, Melanie

2016-01-01

In her article "Burroughs's Postcolonial Visions in The Yage Letters" Melanie Keomany discusses the contents of William S. Burroughs and Allen Ginsberg's The Yage Letters which could be dismissed as openly bigoted and racist. Keomany posits that the text reveals valuable connections between the colonial expansion of the eighteenth century and 1950s USA and Latin America. By re-shaping Burroughs's lived experiences in the Amazon into a text where the narrator William Lee mimics sardonically an...

Letters to a Young Writer.

Science.gov (United States)

Waldman, Anne; Becker, Robin

2002-01-01

Presents words of encouragement to a young poet. Includes empathetic words and motivating ideas. Presents a letter including a quote from "Tintern Abbey" by William Wordsworth and ideas about that quote. (SG)

The impact of familiarization strategies on the missing-letter effect.

Science.gov (United States)

Plamondon, Andréanne; Roy-Charland, Annie; Chamberland, Justin; Quenneville, Joannie; Laforge, Christian

2017-08-01

When reading a text and searching for a target letter, readers make more omissions of the target letter if it is embedded in frequent function words than if it is in rare content words. While word frequency effects are consistently found, few studies have examined the impacts of passage familiarity on the missing-letter effect and studies that have present conflicting evidence. The present study examines the effects of passage familiarity, as well as the impacts of passage familiarization strategy promoting surface or deep encoding, on the missing-letter effect. Participants were familiarized with a passage by retyping a text, replacing all common nouns with synonyms, or generating a text on the same topic as that of the original text, and then completed a letter search task on the familiar passage as well as an unfamiliar passage. In Experiment 1, when both familiar and unfamiliar passages use the same words, results revealed fewer omissions for the retyping and synonyms conditions. However, in Experiment 2, when different words are used in both types of texts, no effect of familiarization strategy was observed. Furthermore, the missing-letter effect is maintained in all conditions, adding support to the robustness of the effect regardless of familiarity with the text.

Open letter to EU Commission about proposed EDC Criteria

DEFF Research Database (Denmark)

Ågerstrand, Marlene; Bero, Lisa; Beronius, Anna

2016-01-01

Open letter in response to the proposed criteria for identification and regulation of endocrine disrupting chemicals, under the PPP and Biocides Regulations......Open letter in response to the proposed criteria for identification and regulation of endocrine disrupting chemicals, under the PPP and Biocides Regulations...

50 CFR 216.258 - Renewal of Letters of Authorization.

Science.gov (United States)

2010-10-01

... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE MAMMALS Taking Marine Mammals Incidental to Conducting Precision Strike Weapon Missions in the Gulf of Mexico § 216.258 Renewal of Letters of Authorization. (a) A Letter of Authorization...

David Bohm : causality and chance, letters to three women

CERN Document Server

2017-01-01

The letters transcribed in this book were written by physicist David Bohm to three close female acquaintances in the period 1950 to 1956. They provide a background to his causal interpretation of quantum mechanics and the Marxist philosophy that inspired his scientific work in quantum theory, probability and statistical mechanics. In his letters, Bohm reveals the ideas that led to his ground breaking book Causality and Chance in Modern Physics. The political arguments as well as the acute personal problems contained in these letters help to give a rounded, human picture of this leading scientist and twentieth century thinker.

Contributions of Emergent Literacy Skills to Name Writing, Letter Writing, and Spelling in Preschool Children

Science.gov (United States)

Puranik, Cynthia S.; Lonigan, Christopher J.; Kim, Young-Suk

2011-01-01

The purpose of this study was to examine which emergent literacy skills contribute to preschool children’s emergent writing (name-writing, letter-writing, and spelling) skills. Emergent reading and writing tasks were administered to 296 preschool children aged 4–5 years. Print knowledge and letter-writing skills made positive contributions to name writing; whereas alphabet knowledge, print knowledge, and name writing made positive contributions to letter writing. Both name-writing and letter-writing skills made significant contributions to the prediction of spelling after controlling for age, parental education, print knowledge, phonological awareness, and letter-name and letter-sound knowledge; however, only letter-writing abilities made a significant unique contribution to the prediction of spelling when both letter-writing and name-writing skills were considered together. Name writing reflects knowledge of some letters rather than a broader knowledge of letters that may be needed to support early spelling. Children’s letter-writing skills may be a better indicator of children’s emergent literacy and developing spelling skills than are their name-writing skills at the end of the preschool year. Spelling is a developmentally complex skill beginning in preschool and includes letter writing and blending skills, print knowledge, and letter-name and letter-sound knowledge. PMID:21927537

LETTERS OF MARIA KUNCEWICZOWA TO HER LATE HUSBAND

Directory of Open Access Journals (Sweden)

Anna Wzorek

2017-04-01

Full Text Available The article discusses the last book of Maria Kuncewiczowa – a set of twenty-three letters (provided with a postscript addressed to her deceased husband. The uniqueness of this correspondence, presented in literary form, lies in the fact that the recipient is dead, treated by the sender as someone constantly present in the real world and still associated with the temporality. "Listy do Jerzego" ("Letters to Jerzy" are – as Tadeusz Swat, one of the reviewers say – “an attempt at denial of death, to save Jerzy by love, memory, and literature.” The analysis of the work highlights the occurring axiological categories. It has been demonstrated that "Letters to Jerzy" is a book about eternal love reaching beyond the grave (in this respect, in stark contrast with "Tristan" 1946, felt with dignity of old age, and finally transcending into faith. "Letters to Jerzy" is also an attempt to reduce the suffering of the writer over the loss of her beloved husband. To some extent, therefore, they correspond to her earlier work "Cudzoziemka" ("Foreigner" in which Kuncewiczowa liberates from the negative emotions associated with the death of her mother.

Referral letters to the psychiatrist in Nigeria: is communication ...

African Journals Online (AJOL)

history, may not be elements that non-psychiatrist phy- sicians routinely collect during their examinations and, therefore, one would not expect such information to be available to be included in referral letters. Conclusion. Deficits in communication or information transfer through referral letters to the psychiatrist are common.

Referral letters to the psychiatrist in Nigeria: is communication ...

African Journals Online (AJOL)

Result: A majority (>80%) of the referral letters had no information on the current medication list, relevant psychosocial history, outline of management to date, results of investigations to date, and known allergies. Conclusion: Deficits in communication or information transfer through referral letters to the psychiatrist are ...

Love letters to the dead: resurrecting an epistolary art.

Science.gov (United States)

Lander, Dorothy A; Graham-Pole, John R

This article explores the art of letter-writing, specifically to our beloved dead, as a form of autoethnographic research, pedagogy, and care work. As university teachers and qualitative researchers in palliative and end-of-life care, we review the literature and history of epistolary communications with the deceased, as a prelude to writing our own letters. John writes to his long-dead mother and Dorothy to her recently deceased spouse Patrick, each letter followed by a reflective dialogue between us. Through this dialogue, we highlight the potential application of this art, or handcraft, to formal and informal palliative care, and the implications for practice, pedagogy, policy, and research. We propose that such direct, non-mediated, communications can offer a valuable form of healing for bereaved people. The therapeutic potential of letter writing and the abundance of literary and popular culture exemplars of responses from the dead are also largely unexplored in death education and research.

Letters in this Issue

Science.gov (United States)

1998-01-01

Reforming the General Chemistry Textbook individual letters by Edward T. Samulski; Stephen J. Hawkes; Stephen J. Fisher; J. Stephen Hartman; A. R. H. Cole; Stanley Pine, Ronald Archer, and Herbert Kaesz; Jimmy Reeves; Robert Hill; and Brock Spencer, C. Bradley Moore and Nedah Rose. Re: article by R. J. Gillespie The author replies

Letter processing and font information during reading: beyond distinctiveness, where vision meets design.

Science.gov (United States)

Sanocki, Thomas; Dyson, Mary C

2012-01-01

Letter identification is a critical front end of the reading process. In general, conceptualizations of the identification process have emphasized arbitrary sets of distinctive features. However, a richer view of letter processing incorporates principles from the field of type design, including an emphasis on uniformities across letters within a font. The importance of uniformities is supported by a small body of research indicating that consistency of font increases letter identification efficiency. We review design concepts and the relevant literature, with the goal of stimulating further thinking about letter processing during reading.

The Syntax of Persuasion: Two Business Letters of Request.

Science.gov (United States)

Limaye, Mohan R.

1983-01-01

Business letter-writers are advised to develop reader empathy and benefit before they ask a favor. The author analyzed two model 16th century letters of request to determine if similar advice was given in the past, and found that the request was subordinate to building a mutually beneficial relationship. (PD)

Undergraduate nursing students writing therapeutic letters to families: an educational strategy.

Science.gov (United States)

Erlingsson, Christen

2009-02-01

Writing therapeutic letters to families is discussed in this article as an educational strategy encouraging students to think reflectively about family nursing. At the University of Kalmar, Sweden, undergraduate nursing students in a primary care module interviewed families using the Calgary Family Assessment Model and wrote therapeutic letters to these families. This article describes (a) the examination process, which was the context for writing therapeutic letters, (b) results of analyses of the letters, and (c) student's post-examination evaluation comments. Results indicate that most students needed encouragement to focus on the family's strengths and resources instead of focusing on own feelings or problems they perceived the family as having. Students also needed support in relinquishing their hierarchical role of "expert nurse." Students' evaluation comments showed that writing therapeutic letters provided students with opportunities to reflect about the connections between family nursing theory and the family itself.

A Fragmentary Archive: Migratory Feelings in Early Anglo-Saxon Women's Letters.

Science.gov (United States)

Watt, Diane

2017-01-01

The letters by Anglo-Saxon women in the Boniface correspondence are connected by cultural practices and emotions centered on the conversion mission that functioned to maintain connections between the Anglo-Saxon diaspora. A striking recurring focus of these letters is on loss and isolation, which connects them to the Old English elegies. Many of the letters describe the writers' traumatic experiences that result from the death or absence of kin. These are women who endured the trauma of being left behind when others migrated overseas or who, in traveling away from their homeland, found themselves isolated in an alien environment, displaced in time as well as space. This article offers an analysis of the letters, focusing on the queer temporalities they explore, the queer emotions they evoke, and the queer kinships that they forge. It argues that the women's letters represent fragments of an early queer archive of migratory feelings.

Open letter to the Vatican.

Science.gov (United States)

1999-01-01

An open letter was published by Latin American and Caribbean women during the Special Session of the UN General Assembly on the International Conference on Population and Development. The letter generally focused on the Church¿s stand on women's reproductive rights. In particular, it questioned the Church on the following aspects of reproductive health, which include: 1) maternal death related to lack of access to reproductive health care; 2) Vatican representatives insisting that only parents can supervise their children education and health, which also lead to many cases of sexual abuse and incest; 3) women's sexual inequality and daily violence; 4) the Vatican delegation blocking the advances of contraception, sexual education, and HIV prevention; 5) problems of migrants and allocation of resources; and 6) the Church failing to recognize the capacity of young people to make decisions based on their own conscience.

Scientific Letter: High-intent suicide and the Beck's Suicide Intent ...

African Journals Online (AJOL)

Scientific Letter: High-intent suicide and the Beck's Suicide Intent scale: a case report. ... African Journal of Psychiatry. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current ... Abstract. Scientific Letter - No Abstract Available ...

[Changes in CIRUGIA ESPANOLA Letters to the Editor between 2000 and 2007].

Science.gov (United States)

Rosell-Pradas, Jorge; Sánchez-Cantalejo, Emilio

2008-09-01

To describe the frequency and bibliographic characteristics of letters to the editor in the journal, Cirugía Española published between 2000 and 2007 and to compare the differences in the periods between 2000-2003 and 2004-2007. A descriptive and cross-sectional study, using the letters to the editor published in Spanish surgery between 2000 and 2007, as observation units. The variables considered were: the number of letters according to the volume and year of publication, substantive content of the paper, text length, graphics resources use, number of signatories and their professional profile, institutions of the authors, by origin and number of Autonomous Communities and number of bibliographical references. To meet the second objective, we compared letters from the period 2000-2003 with the period 2004-2007 against the rest of variables considered as a result. We used descriptive statistics and statistical analysis for comparison of distributions (chi2), with a level of significance of p < 0.05, using the SPSS software (Version 15.0). We identified 312 documents classified as letters. Between 2002 and 2005 their number was small. Often referring to clinical cases 187 (59.9%) and related letters, 98 (31.4%). Of those, 81.1% met the standard length of the text and only 6 letters (1.9%) was the use of graphics exceeded. In 122 letters (39.1%) the permitted number of authors was exceeded. They were mostly contributed by surgeons, 238 cases (76.3%), usually a single hospital, with 294 letters (94.2%) mainly from, Catalonia, Andalusia, Madrid and Valencia. Only 58.1% of the letters complied with the permitted number of references. More related letters were published in the last period (59 letters; 42.1%) than during the years 2000-2003 (39 letters; 22.7%) (chi2 = 14.79; p < 0.001). The correct length of the text improved in the second period, 136 (97.1%), compared to the first 117 (68%) (chi2 = 42.67; p < 0.001. The graphics resources were used properly in both

32 CFR 884.17 - Commander's instruction letter to member.

Science.gov (United States)

2010-07-01

... instruction letter to member. Subject: Instructions in Case of Release on Bail or Personal Recognizance 1. You... 32 National Defense 6 2010-07-01 2010-07-01 false Commander's instruction letter to member. 884.17... civilian custody on bail or on your own recognizance, report immediately in person or by telephone to the...

Lost and Found, Letters and Methods: Assessing Attitudes toward Chiropractic and Medical Care

Directory of Open Access Journals (Sweden)

Hannah Kern

2010-10-01

Full Text Available Attitudes toward traditional and chiropractic medicine were compared using Milgram's lost letter technique. A total of 192 letters were placed on the windshields of vehicles in parking lots at six restaurants and department stores in each of four quadrants of a medium-sized, Southeastern city. These letters were addressed to "Admissions" at either a fictitious Institute of Medicine or Institute of Chiropractic Care. Return addresses included either a male or a female name. Thus, those who found a lost letter were faced with the option of returning or not returning a letter from either a male or a female, addressed to an Institute of traditional or non-traditional medicine. After examining previous studies which had used the lost letter technique, numerous methodological improvements were implemented. For example, letters were randomly assigned to potential drop spots for each of 24 study locations (six study locations in each of four city quadrants, and a Latin square design was used to control for possible order effects in the four study conditions that were implemented. Nearly 65% of the letters (124 of 192 were returned. We found: 1 letters addressed to a fictitious Institute of Chiropractic Care were just as likely to be returned as those addressed to a fictitious Institute of Medicine; 2 letters with female return addresses were as likely to be returned as those with male return addresses; 3 there was no interaction between study conditions; 4 based on what was essentially a replication study, a comparison of the pattern of returns using the first and second cycle of lost letters (n = 96 for each cycle revealed an equivalent pattern of no-difference findings. DOI: 10.2458/azu_jmmss.v1i1.78

Contemporary trends in the research of the Letter to Philemon

Directory of Open Access Journals (Sweden)

Bartosz Adamczewski

2005-03-01

Full Text Available In the period of last two or three decades interpretation of the Letter to Philemon has undergone significant changes. Exegetes applying the historical-critical method proposed recently several new ways of reconstructing the situation that occasioned Paul’s writing the letter. It has been suggested e.g. that Onesimus was no runaway, but probably an envoy from Colossae, or Philemon’s estranged brother, or a slave justifiably seeking intercession, or a roamer. Synchronic methods applied by many exegetes (structural, rhetorical, narrative and pragmatic criticism elucidate various kinds of influence of the letter upon the reader. More and more popular becomes also nowadays manifold liberationist approach. However, beyond applying these various hermeneutic procedures there is also, at least for believing exegetes, an important task of adequate explaining the significance of the Letter to Philemon as an inspired writing.

A classification of marked hijaiyah letters' pronunciation using hidden Markov model

Science.gov (United States)

Wisesty, Untari N.; Mubarok, M. Syahrul; Adiwijaya

2017-08-01

Hijaiyah letters are the letters that arrange the words in Al Qur'an consisting of 28 letters. They symbolize the consonant sounds. On the other hand, the vowel sounds are symbolized by harokat/marks. Speech recognition system is a system used to process the sound signal to be data so that it can be recognized by computer. To build the system, some stages are needed i.e characteristics/feature extraction and classification. In this research, LPC and MFCC extraction method, K-Means Quantization vector and Hidden Markov Model classification are used. The data used are the 28 letters and 6 harakat with the total class of 168. After several are testing done, it can be concluded that the system can recognize the pronunciation pattern of marked hijaiyah letter very well in the training data with its highest accuracy of 96.1% using the feature of LPC extraction and 94% using the MFCC. Meanwhile, when testing system is used, the accuracy decreases up to 41%.

The A.I.D.A. Plan and the Writing of Sales Letters.

Science.gov (United States)

Jong, Rowena

A study based on textual analysis of sales letters is reported that evaluates the Attention, Interest, Desire, and Action (AIDA) approach to teaching the writing of sales letters. Thirty business letters written by undergraduate business students and executives were analyzed. The forms of cohesion, voice pattern, and information focus of the…

22 CFR 201.71 - Terms of letters of credit.

Science.gov (United States)

2010-04-01

... shall not be inconsistent with or contrary to the terms of the letter of commitment. Any such letter of credit or agreement may be modified or extended at any time in such a manner and to such extent as is acceptable to the approved applicant and the bank: Provided, That such modification or extension may not be...

24 CFR 242.49 - Funds and finances: deposits and letters of credit.

Science.gov (United States)

2010-04-01

... collection under the letter of credit. In the event a demand for payment thereunder is not immediately met... letters of credit. 242.49 Section 242.49 Housing and Urban Development Regulations Relating to Housing and...: deposits and letters of credit. (a) Deposits. Where HUD requires the mortgagor to make a deposit of cash or...

Scientific Letter: Stabbing nails into the neck: an unusual self ...

African Journals Online (AJOL)

Scientific Letter: Stabbing nails into the neck: an unusual self-damaging behavior mandating neurosurgery. A Aghabiklooei, R Aghabiklooei, N Zamani. Abstract. Scientific Letter - No Abstract Available. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT.

Involuntary attention with uncertainty: peripheral cues improve perception of masked letters, but may impair perception of low-contrast letters.

Science.gov (United States)

Kerzel, Dirk; Gauch, Angélique; Buetti, Simona

2010-10-01

Improvements of perceptual performance following the presentation of peripheral cues have been ascribed to accelerated accrual of information, enhanced contrast perception, and decision bias. We investigated effects of peripheral cues on the perception of Gabor and letter stimuli. Non-predictive, peripheral cues improved perceptual accuracy when the stimuli were masked. In contrast, peripheral cues degraded perception of low-contrast letters and did not affect the perception of low-contrast Gabors. The results suggest that involuntary attention accelerates accrual of information but are not entirely consistent with the idea that involuntary attention enhances subjective contrast. Rather, peripheral cues may cause crowding with single letter targets of low contrast. Further, we investigated the effect of the amount of uncertainty on involuntary attention. Cueing effects were (initially) larger when there were more possible target locations. In addition, cueing effects were larger when error feedback was absent and observers had no knowledge of results. Despite these strategic factors, location uncertainty was not sufficient to produce cueing effects, showing that location uncertainty paired with non-predictive cues reveals perceptual and not (only) decisional processes.

The Danish letters

DEFF Research Database (Denmark)

Beier, Sofie; Ejlers, Steen

2011-01-01

The talk will focus on Danish type designers and their work on Æ (AE), Ø (Oslash) and Å (Aring). These 'anomalies' found in the Danish written language, often causes difficulties for type designers. The counters of Ø/ø sometimes appear overcrowded, the uppercase Æ can result in an uncomfortably o......' attempt to create the optimal variation of these letters, we will give a brief introduction to the Danish typography tradition ranging from the early 20th Century and up until today....

Letters to the Editor

Science.gov (United States)

1999-09-01

All the Letters to the Editor in this issue are in the same PostScript or PDF file. Contents The imaginary Sun? Harold Aspden Energy Science Ltd, PO Box 35, Southampton SO16 7RB, UK Difficult physics? Tim Akrill Chief Examiner, A-level Physics, Edexcel Foundation Was it a dream? Bill Jarvis 6 Peggy's Mill Road, Edinburgh EH4 6JY

Analysis of letter name knowledge using Rasch measurement.

Science.gov (United States)

Bowles, Ryan P; Skibbe, Lori E; Justice, Laura M

2011-01-01

Letter name knowledge (LNK) is a key predictor of later reading ability and has been emphasized strongly in recent educational policy. Studies of LNK have implicitly treated it as a unidimensional construct with all letters equally relevant to its measurement. However, some empirical research suggests that contextual factors can affect the measurement of LNK. In this study, we analyze responses from 909 children on measures of LNK using the Rasch model and its extensions, and consider two contextual factors: the format of assessment and the own-name advantage, which states that children are more likely to know letters in their own first names. Results indicate that both contextual factors have important impacts on measurement and that LNK does not meet the requirements of Rasch measurement even when accounting for the contextual factors. These findings introduce philosophical concerns for measurement of constrained skills which have limited content for assessment.

Harvard Education Letter. Volume 26, Number 4, July-August 2010

Science.gov (United States)

Chauncey, Caroline T., Ed.

2010-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Learning Progressions in Science: A New Approach Emphasizes Sustained Instruction in Big Ideas (Patti Hartigan); (2) Putting the "Boy Crisis" in…

29 CFR 1621.3 - Procedure for requesting an opinion letter.

Science.gov (United States)

2010-07-01

... 1621.3 Labor Regulations Relating to Labor (Continued) EQUAL EMPLOYMENT OPPORTUNITY COMMISSION PROCEDURES-THE EQUAL PAY ACT § 1621.3 Procedure for requesting an opinion letter. (a) A request for an opinion letter should be submitted in writing to the Chairman, Equal Employment Opportunity Commission...

Pirates at Parties: Letter Position Processing in Developing Readers

Science.gov (United States)

Kohnen, Saskia; Castles, Anne

2013-01-01

There has been much recent interest in letter position coding in adults, but little is known about the development of this process in children learning to read. Here, the letter position coding abilities of 127 children in Grades 2, 3, and 4 (aged 7-10 years) were examined by comparing their performance in reading aloud "migratable" words (e.g.,…

Referral letters to the emergency department: is the medication list accurate?

LENUS (Irish Health Repository)

McCullagh, M

2015-02-01

Medication errors are common when patients transfer across healthcare boundaries. This study was designed to investigate the quality of information on medicines provided by general practitioners (GPs) on emergency department (ED) referral letters. A convenience sample of referral letters to the ED of a teaching hospital was reviewed. The medication list and\\/or patient\\'s drug allergy status were noted. Medicines reconciliation including patient (or carer) interview was conducted to determine the patient\\'s actual home medication list. This was compared with the GP list and any discrepancies were identified and addressed. A total of 92 referral letters were included in the analysis of which 60 were computer-generated and 32 were hand-written. GPs provided dose and frequency of administration information in 47 (51%) of the letters sampled i.e. 44 (71%) computer-generated versus 3 (10%) hand-written; p < 0.001. In addition, the patient was taking their medicines exactly as per the GP list in 20 (22%) of cases. The patient\\'s drug allergy status was documented in 13 (14%) of the letters.

Harvard Education Letter. Volume 23, Number 1, January-February 2007

Science.gov (United States)

Chauncey, Caroline, Ed.

2007-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Response to Intervention: A New Approach to Reading Instruction Aims to Catch Struggling Readers Early (Nancy Walser); (2) Getting Advisory Right: Focus and…

Harvard Education Letter. Volume 26, Number 2, March-April 2010

Science.gov (United States)

Chauncey, Caroline T., Ed.

2010-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Online Testing, Version 1.0: Oregon's Adaptive Computer-Based Accountability Test Offers a Peek at a Brave New Future (Robert Rothman); (2) Beyond…

Harvard Education Letter. Volume 26, Number 5, September-October 2010

Science.gov (United States)

Walser, Nancy, Ed.

2010-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Scenes from the School Turnaround Movement: Passion, Frustration, Mid-Course Corrections Mark Rapid Reforms (Laura Pappano); (2) The Media Savvy Educator:…

Harvard Education Letter. Volume 28, Number 2, March-April 2012

Science.gov (United States)

Chauncey, Caroline T., Ed.

2012-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Course Credits on the Quick: Controversial Online Recovery Programs Speed the Path to Graduation (Andrew Brownstein); (2) Collaborating to Make Schools More Inclusive…

Harvard Education Letter. Volume 27, Number 4, July-August 2011

Science.gov (United States)

Chauncey, Caroline T., Ed.

2011-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Integrated Data Systems Link Schools and Communities: Researchers Combine School and Non-School Data to Inform Interventions and Policy (Patti Hartigan);…

Harvard Education Letter. Volume 25, Number 3, May-June 2009

Science.gov (United States)

Chauncey, Caroline T., Ed.

2009-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Improving Teaching and Learning through Instructional Rounds (Lee Teitel); (2) Developmentally Appropriate Practice in the Age of Testing: New Reports Outline Key Principles…

Harvard Education Letter. Volume 25, Number 6, November-December 2009

Science.gov (United States)

Chauncey, Caroline T., Ed.

2009-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) "Platooning" Instruction: Districts Weigh Pros and Cons of Departmentalizing Elementary Schools (Lucy Hood); (2) Behind the Classroom Door: A Rare Glimpse Indicates the…

Harvard Education Letter. Volume 24, Number 4, July-August 2008

Science.gov (United States)

Chauncey, Caroline, Ed.

2008-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Taking the Measure of New Teachers: California Shifts from Standardized Tests to Performance-Based Assessment as a Condition of Licensure (Robert Rothman);…

Harvard Education Letter. Volume 27, Number 1, January-February 2011

Science.gov (United States)

Walser, Caroline T., Ed.

2011-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) The Greening of Environmental Ed: Teachers Focus on Complexity, Evidence, and Letting Students Draw Their Own Conclusions (Lucy Hood); (2) Like Teacher,…

Harvard Education Letter. Volume 27, Number 3, May-June 2011

Science.gov (United States)

Chauncey, Caroline T., Ed.

2011-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Bringing Art into School, Byte by Byte: Innovative Programs Use Technology to Expand Access to the Arts (Patti Hartigan); (2) Differentiated Instruction…

Harvard Education Letter. Volume 25, Number 4, July-August 2009

Science.gov (United States)

Chauncey, Caroline T., Ed.

2009-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Putting the Brakes on "Summer Slide": Modified School Calendars Build in Time to Enrich Learning and Sustain Gains (Brigid Schulte); (2) Closing…

Harvard Education Letter. Volume 25, Number 1, January-February 2009

Science.gov (United States)

Chauncey, Caroline, Ed.

2009-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Learning Across Distance: Virtual-Instruction Programs Are Growing Rapidly, but the Impact on "Brick-and-Mortar" Classrooms Is Still up in the Air…

Different letter-processing strategies in diagnostic subgroups of developmental dyslexia.

Science.gov (United States)

Lachmann, Thomas; van Leeuwen, Cees

2008-07-01

Normally reading adults (N = 15) and primary school children (N = 24) and two diagnostic subgroups of children with developmental dyslexia (N = 21)-all native German speakers-performed a successive same-different task with pairs of letters and nonletters (pseudoletters or geometrical shapes). The first item of a pair was always presented on its own, and the second either on its own or surrounded by a congruent or incongruent nontarget shape. Adults showed congruence effects with nonletters but not with letters, and children with both types of stimuli. Frequent-word reading-impaired dyslexics (N = 11) in addition showed dramatically slower overall reaction times. Nonword reading-impaired dyslexics (N = 10) showed congruence effects with nonletters but negative congruence effects with letters. The results support the notion that normal readers have established a special visual processing strategy for letters. Processing speed rather than reading expertise seems crucial for this strategy to emerge. The contrasting effects between subgroups of dyslexics reveal specific underlying deficits.

How to write effective business letters: scribing information for pharmacists.

Science.gov (United States)

Hamilton, C W

1993-11-01

Pharmacists frequently write letters but lack specific training on how to do it well. This review summarizes strategies for improving business correspondence, emphasizes basic writing guidelines, and offers practical advice for pharmacists. The first steps for effective communication are careful planning and identifying the main message to be conveyed. The purpose for writing should be stated in the opening paragraph of the letter. To ensure a successful outcome, actions needed should be clearly summarized and visually highlighted. The tone of the letter should reflect a reasonable speech pattern, not the cryptic writing found in many scientific papers. The layout of the letter should be inviting, which is readily achievable through judicious use of word processing. Many delivery options are available, such as traditional postal services, express mail, and facsimile transmission. Readers are encouraged to test these basic writing principles and decide for themselves whether these recommendations affect the success of business correspondence.

John von Neumann selected letters

CERN Document Server

2005-01-01

John von Neuman was perhaps the most influential mathematician of the twentieth century, especially if his broad influence outside mathematics is included. Not only did he contribute to almost all branches of mathematics and created new fields, but he also changed post-World War II history with his work on the design of computers and with being a sought-after technical advisor to many figures in the U.S. military-political establishment in the 1940s and 1950s. The present volume is the first substantial collection of (previously mainly unpublished) letters written by von Neumann to colleagues, friends, government officials, and others. The letters give us a glimpse of the thinking of John von Neumann about mathematics, physics, computer science, science management, education, consulting, politics, and war. Readers of quite diverse backgrounds will find much of interest in this fascinating first-hand look at one of the towering figures of twentieth century science.

Harvard Education Letter. Volume 22, Number 6, November-December 2006

Science.gov (United States)

Chauncey, Caroline, Ed.

2006-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) (In)formative Assessments: New Tests and Activities Can Help Teachers Guide Student Learning (Robert Rothman); (2) Recent Research on the Achievement Gap: How Lifestyle…

Harvard Education Letter. Volume 25, Number 5, September-October 2009

Science.gov (United States)

Chauncey, Caroline T., Ed.

2009-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) The Invisible Hand in Education Policy: Behind the Scenes, Economists Wield Unprecedented Influence (David McKay Wilson); (2) Bonding and Bridging: Schools Open Doors for…

Harvard Education Letter. Volume 26, Number 1, January-February 2010

Science.gov (United States)

Chauncey, Caroline T., Ed.

2010-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Charters and Unions: What's the Future for This Unorthodox Relationship? (Alexander Russo); (2) From Special Ed to Higher Ed: Transition Planning for Disabled Students Focuses…

Harvard Education Letter. Volume 24, Number 3, May-June 2008

Science.gov (United States)

Chauncey, Caroline, Ed.

2008-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) "Equity, Access, and Opportunity": Despite Challenges, More Districts Adopt One-to-One Laptop Programs (Colleen Gillard); (2) Small Kids, Big Words: Research-Based Strategies…

Harvard Education Letter. Volume 26, Number 6, November-December 2010

Science.gov (United States)

Walser, Nancy, Ed.

2010-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Video Games Take Testing to the Next Level: Researchers See Promise in Game-Like Assessments That Measure Complex Skills (Robert Rothman); (2) An Academic…

Harvard Education Letter. Volume 28, Number 1, January-February 2012

Science.gov (United States)

Walser, Nancy, Ed.

2012-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Using Theater to Teach Social Skills: Researchers Document Improvements for Children with Autism (Patti Hartigan); (2) The Family Model of Schooling Revisited: Few Teachers,…

Harvard Education Letter. Volume 23, Number 5, September-October 2007

Science.gov (United States)

Chauncey, Caroline, Ed.

2007-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Confronting the Autism Epidemic: New Expectations for Children with Autism Means a New Role for Public Schools (Kate McKenna); (2) Internet Research 101:…

Intertextuality in Ba's So Long a Letter and Umunnakwe's Dear ...

African Journals Online (AJOL)

Intertextuality takes for granted the interdependence of literary texts because every artistic creation is a re-echoing of past knowledge. Mariama Ba's So Long A Letter and Ndubisi Umunnakwe's Dear Ramatoulaye are African examples. This work examines how Ba's So Long A Letter intertextualises with Umunnakwe's Dear ...

24 CFR 200.63 - Required deposits and letters of credit.

Science.gov (United States)

2010-04-01

... Commissioner for collection under the letter of credit. In the event a demand for payment thereunder is not... credit. 200.63 Section 200.63 Housing and Urban Development Regulations Relating to Housing and Urban... Required deposits and letters of credit. (a) Deposits. Where the Commissioner requires the mortgagor to...

Harvard Education Letter. Volume 21, Number 6, November-December 2005

Science.gov (United States)

Chauncey, Caroline, Ed.

2005-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Is History... History?: Standards, Accountability, and the Future of Our Nation's Past (Robert Rothman); (2) Curriculum Access for All: How Teachers Can Use Universal Design…

Electronic Discharge Letter Mobile App

NARCIS (Netherlands)

Lezcano, Leonardo; Triana, Michel; Ternier, Stefaan; Hartkopf, Kathleen; Stieger, Lina; Schroeder, Hanna; Sopka, Sasa; Drachsler, Hendrik; Maher, Bridget; Henn, Patrick; Orrego, Carola; Specht, Marcus

2014-01-01

The electronic discharge letter mobile app takes advantage of Near Field Communication (NFC) within the PATIENT project and a related post-doc study. NFC enabled phones to read passive RFID tags, but can also use this short-range wireless technology to exchange (small) messages. NFC in that sense

Traditions of martyrdom in the Ignatian Letters

Directory of Open Access Journals (Sweden)

S. Fuhrmann

2011-06-01

Full Text Available The letters of Ignatius represent one of the key texts for the emergence of martyrdom during the second century AD in Christianity. This article is concerned with the question whether Ignatius contributed to a “theology of martyrdom” or whether he rather relied on previous traditions. The author argues, by undertaking an analysis of certain pragmatics and semantics, that the motif of martyrdom is solely used to buttress Ignatius’ claim for authority among his intended addressees by referring to an understanding of martyrdom that has its roots in the New Testament. An identification of the author of the letters with a historical martyr is regarded as unlikely.

Harvard Education Letter. Volume 27, Number 2, March-April 2011

Science.gov (United States)

Walser, Nancy, Ed.

2011-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Hybrid Schools for the iGeneration: New Schools Combine "Bricks" and "Clicks" (Brigid Schulte); (2) Dual Language Programs on the Rise: "Enrichment" Model Puts Content Learning…

Harvard Education Letter. Volume 26, Number 3, May-June 2010

Science.gov (United States)

Chauncey, Caroline T., Ed.

2010-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Unleashing the "Brain Power" of Groups in the Classroom: The Neuroscience behind Collaborative Work (Nancy Walser); (2) Putting AP to the Test: New Research Assesses the…

Harvard Education Letter. Volume 25, Number 2, March-April 2009

Science.gov (United States)

Chauncey, Caroline, Ed.

2009-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Money and Motivation: New Initiatives Rekindle Debate over the Link between Rewards and Student Achievement (David McKay Wilson); (2) An Inexact Science: What Are the Technical…

Harvard Education Letter. Volume 24, Number 6, November-December 2008

Science.gov (United States)

Chauncey, Caroline, Ed.

2008-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) When Worlds Collide: Universal PreK Brings New Challenges for Public Elementary Schools (David McKay Wilson); (2) Answers and Questions: Schools Survey Their Students--and…

Harvard Education Letter. Volume 23, Number 6, November-December 2007

Science.gov (United States)

Chauncey, Caroline, Ed.

2007-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Charting a New Course toward Racial Integration: Districts Seek Legal Routes to Capture the Benefits of Diversity (Brigid Schulte); (2) Voluntary Integration: Two Views--(a)…

Harvard Education Letter. Volume 27, Number 6, November-December 2011

Science.gov (United States)

Walser, Nancy, Ed.

2011-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) With Cheating on the Rise, Schools Respond (David McKay Wilson); (2) Waldorf Education in Public Schools: Educators Adopt--and Adapt--This Developmental, Arts-Rich Approach…

Harvard Education Letter. Volume 24, Number 2, March-April 2008

Science.gov (United States)

Chauncey, Caroline, Ed.

2008-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Educating Teenage Immigrants: High Schools Experiment with Ways to Group New English-Language Learners (Lucy Hood); (2) Hot Topics and Key Words: Pilot Project Brings Teachers…

Letter-Sound Reading: Teaching Preschool Children Print-to-Sound Processing

Science.gov (United States)

Wolf, Gail Marie

2016-01-01

This intervention study investigated the growth of letter sound reading and growth of consonant-vowel-consonant (CVC) word decoding abilities for a representative sample of 41 US children in preschool settings. Specifically, the study evaluated the effectiveness of a 3-step letter-sound teaching intervention in teaching preschool children to…

Why Doctors Do Not Answer Referral Letters | Smith | South African ...

African Journals Online (AJOL)

Background: Healthcare workers at primary healthcare (PHC) clinics are frustrated by the fact that they do not receive replies to their referral letters to doctors. Referral letters act as permission slips to allow patients easy access to treatment by specialists at secondary and tertiary service levels and communicate reasons for ...

21 CFR 170.6 - Opinion letters on food additive status.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Opinion letters on food additive status. 170.6... (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES General Provisions § 170.6 Opinion letters on food additive status. (a) Over the years the Food and Drug Administration has given informal...

Teaching Braille Letters, Numerals, Punctuation, and Contractions to Sighted Individuals

Science.gov (United States)

Putnam, Brittany C.; Tiger, Jeffrey H.

2015-01-01

Braille-character recognition is one of the foundational skills required for teachers of braille. Prior research has evaluated computer programming for teaching braille-to-print letter relations (e.g., Scheithauer & Tiger, 2012). In the current study, we developed a program (the Visual Braille Trainer) to teach not only letters but also…

Trends in the Employment Process: Resumes and Job Application Letters.

Science.gov (United States)

Spinks, Neld; Wells, Barron

1999-01-01

Surveys of Fortune 500 companies in 1978, 1985, and 1995 revealed trends and preferences in content of resumes and cover letters. Compared to earlier years, current preferences were for both letters and resumes in the initial contact, more emphasis on grammar and spelling, and acceptance of two-page resumes. (SK)

Harvard Education Letter. Volume 24, Number 1, January-February 2008

Science.gov (United States)

Chauncey, Caroline, Ed.

2008-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Leadership Lessons From Schools Becoming "Data Wise" (Jennifer L. Steele and Kathryn Parker Boudett); (2) A Guide on the Side: Mentors Help New Leaders Prepare for Life in the…

Harvard Education Letter. Volume 27, Number 5, September-October 2011

Science.gov (United States)

Chauncey, Caroline T., Ed.

2011-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Teaching Students to Ask Their Own Questions: One Small Change Can Yield Big Results (Dan Rothstein and Luz Santana); (2) Voice of Experience: Jerry Weast--Leading a System…

Harvard Education Letter. Volume 23, Number 2, March-April 2007

Science.gov (United States)

Chauncey, Caroline, Ed.

2007-01-01

"Harvard Education Letter" is published bimonthly at the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) More Than "Making Nice": Getting Teachers to (Truly) Collaborate (Laura Pappano); (2) "Doing the Critical Things First": An Aligned Approach to PreK and Early Elementary Math;…

Harvard Education Letter. Volume 24, Number 5, September-October 2008

Science.gov (United States)

Chauncey, Caroline, Ed.

2008-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Teaching 21st Century Skills: What Does It Look Like in Practice? (Nancy Walser); (2) Getting and Spending: Schools and Districts Share Lessons on the Effective Uses of…

21 CFR 570.6 - Opinion letters on food additive status.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Opinion letters on food additive status. 570.6... (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES General Provisions § 570.6 Opinion letters on food additive status. (a) Over the years the Food and Drug Administration has given informal...

Mud, Blood, and Bullet Holes: Teaching History with War Letters

Science.gov (United States)

Carroll, Andrew

2013-01-01

From handwritten letters of the American Revolution to typed emails from Iraq and Afghanistan, correspondence from U.S. troops offers students deep insight into the specific conflicts and experiences of soldiers. Over 100,000 correspondences have been donated to the Legacy Project, a national initiative launched in 1998 to preserve war letters by…

46 CFR 308.522 - Collateral deposit fund, letter of transmittal, Form MA-302.

Science.gov (United States)

2010-10-01

... 46 Shipping 8 2010-10-01 2010-10-01 false Collateral deposit fund, letter of transmittal, Form MA... Collateral deposit fund, letter of transmittal, Form MA-302. The standard form of letter of transmittal for use in establishing a collateral deposit fund, may be obtained from the American War Risk Agency or...

Resource Letter MP-3: The Manhattan Project and Related Nuclear Research

Science.gov (United States)

Reed, B. Cameron

2016-10-01

This Resource Letter is a supplement to the earlier Resource Letters MP-1 and MP-2, and provides further sources on the Manhattan Project and related research. Books, review papers, journal articles, videos, and websites are cited for the following topics: general works, technical works, biographical and autobiographical works, foreign wartime nuclear programs and related allied intelligence, the use of the bombs against Hiroshima and Nagasaki, technical papers of historical interest, postwar policy and technical developments, and educational materials. Together, these three Resource Letters describe nearly 400 sources of information on the Manhattan Project.

Dear Hacker Letters to the Editor of 2600

CERN Document Server

Goldstein, Emmanuel

2010-01-01

Actual letters written to the leading hackers' magazine. For 25 years, 2600: The Hacker Quarterly has given voice to the hacker community in all its manifestations. This collection of letters to the magazine reveals the thoughts and viewpoints of hackers, both white and black hat, as well as hacker wannabes, technophiles, and people concerned about computer security. Insightful and entertaining, the exchanges illustrate 2600 's vast readership, from teenage rebels, anarchists, and survivalists to law enforcement, consumer advocates, and worried parents.: 2600: The Hacker Quarterly has been the

Harvard Education Letter. Volume 23, Number 3, May-June 2007

Science.gov (United States)

Chauncey, Caroline, Ed.

2007-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) The Road to School Improvement: It's Hard, It's Bumpy, and It Takes as Long as It Takes (Richard F. Elmore and Elizabeth A. City); (2) Better Teaching with Web Tools: How…

Harvard Education Letter. Volume 23, Number 4, July-August 2007

Science.gov (United States)

Chauncey, Caroline, Ed.

2007-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) Meeting of the Minds: The Parent-Teacher Conference Is the Cornerstone of School-Home Relations. How Can It Work for All Families? (Laura Pappano); (2) In Search of That "Third…

Composing chaotic music from the letter m

Science.gov (United States)

Sotiropoulos, Anastasios D.

Chaotic music is composed from a proposed iterative map depicting the letter m, relating the pitch, duration and loudness of successive steps. Each of the two curves of the letter m is based on the classical logistic map. Thus, the generating map is xn+1 = r xn(1/2 - xn) for xn between 0 and 1/2 defining the first curve, and xn+1 = r (xn - 1/2)(1 - xn) for xn between 1/2 and 1 representing the second curve. The parameter r which determines the height(s) of the letter m varies from 2 to 16, the latter value ensuring fully developed chaotic solutions for the whole letter m; r = 8 yielding full chaotic solutions only for its first curve. The m-model yields fixed points, bifurcation points and chaotic regions for each separate curve, as well as values of the parameter r greater than 8 which produce inter-fixed points, inter-bifurcation points and inter-chaotic regions from the interplay of the two curves. Based on this, music is composed from mapping the m- recurrence model solutions onto actual notes. The resulting musical score strongly depends on the sequence of notes chosen by the composer to define the musical range corresponding to the range of the chaotic mathematical solutions x from 0 to 1. Here, two musical ranges are used; one is the middle chromatic scale and the other is the seven- octaves range. At the composer's will and, for aesthetics, within the same composition, notes can be the outcome of different values of r and/or shifted in any octave. Compositions with endings of non-repeating note patterns result from values of r in the m-model that do not produce bifurcations. Scores of chaotic music composed from the m-model and the classical logistic model are presented.

Verse Letter from Gregory of Nazianzus to Vitalianus

Directory of Open Access Journals (Sweden)

Erika Brodňanská

2012-12-01

Full Text Available The article offers a complex view of the poetic letter of Gregory of Nazianzus II, II, 3 Ad Vitalianum, which has not yet been the subject of modern criticism. The letter is a plea by Vitalianus’ banished sons for their father to take them back. Based on the manuscript tradition, the article’s author concludes that the fictional author of the letter is the son Phocas rather than Peter. The disrupted relationship between father and sons is reflected in both the content of the poem and the forms of salutations used: the seemingly positive epithets φέριστε, μακάρτατε, and φίλε; forms of address which directly express a certain distance and coldness (μέγα φέρτατε, ὦ ἄνα, or even animosity towards the father (ὀλοώτατε δαῖμον, ὦ κακόβουλε. The poetic letter has a concentric structure (A; B; C; D; E; F; G; F´; E´; D´; C´; B´; A´, with individual com­ponents linked for the most part thematically. The letter is written in dactylic hexameter. The most frequently used metre in the verses is the holodactyl, and the most frequent caesura is the caesura post tertium trochaeum. As far as the breach of Hermann’s bridge in verses is concerned, and based on the understanding of the term ‘word’ in metrics, the author of the article concludes that in the majority of cases the breach is only ‘visual’, and cannot be detected when listened to. Gregory did not avoid three true hiatuses; and in two verses, in order to keep the rhythm of dactylic hexameter, it is essential to measure a long syllable as a short one. However, metric errors may be related to prosodic licence.

Allograph priming is based on abstract letter identities: Evidence from Japanese kana.

Science.gov (United States)

Kinoshita, Sachiko; Schubert, Teresa; Verdonschot, Rinus G

2018-04-23

It is well-established that allographs like the uppercase and lowercase forms of the Roman alphabet (e.g., a and A) map onto the same "abstract letter identity," orthographic representations that are independent of the visual form. Consistent with this, in the allograph match task ("Are 'a' and 'A' the same letter?"), priming by a masked letter prime is equally robust for visually dissimilar prime-target pairs (e.g., d and D) and similar pairs (e.g., c and C). However, in principle this pattern of priming is also consistent with the possibility that allograph priming is purely phonological, based on the letter name. Because different allographic forms of the same letter, by definition, share a letter name, it is impossible to rule out this possibility a priori. In the present study, we investigated the influence of shared letter names by taking advantage of the fact that Japanese is written in two distinct writing systems, syllabic kana-that has two parallel forms, hiragana and katakana-and logographic kanji. Using the allograph match task, we tested whether a kanji prime with the same pronunciation as the target kana (e.g., - い, both pronounced /i/) produces the same amount of priming as a kana prime in the opposite kana form (e.g., イ- い). We found that the kana primes produced substantially greater priming than the phonologically identical kanji prime, which we take as evidence that allograph priming is based on abstract kana identity, not purely phonology. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Open letter to Mr Christian Bataille, Deputy of Nord region, France. Open letter on nuclear energy

International Nuclear Information System (INIS)

Delacroix P

2007-02-01

The author, by means of a letter to the deputy Christian Bataille, presents arguments to the shutdown of old nuclear power plants. He points out the environmental and economical arguments in favor of a decrease of the nuclear power use in France. (A.L.B.)

50 CFR 216.219 - Renewal and modifications of Letters of Authorization.

Science.gov (United States)

2010-10-01

... OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE MAMMALS Taking of Marine Mammals Incidental to Explosive Severance.... Gulf of Mexico § 216.219 Renewal and modifications of Letters of Authorization. (a) A Letter of...

Letter: Meyerhofer

International Nuclear Information System (INIS)

Mackinnon, A.J.

2011-01-01

This letter confirms that the Laboratory for Laser Energetics (LLE) was an important part of the FY10 NIF Polar Drive Exploding Pusher experiments on the National Ignition Facility (NIF). These experiments were designed by LLE to produce requested neutron yields to calibrate and qualify nuclear diagnostics. LLE built a deuterium-tritium filling system for the glass shells and provided them to LLNL for mounting. In FY10, four exploding pusher implosions were performed with measured neutron yields within a factor of two of requested and ion temperatures within 20% of requested. These implosions are proving to be an ideal platform for commissioning the nuclear diagnostic suite on the NIF and are achieving all of the objectives planned for this campaign.

SiD Letter of Intent

CERN Document Server

Aihara, H.; Oreglia, M.; Berger, E.L.; Guarino, V.; Repond, J.; Weerts, H.; Xia, L.; Zhang, J.; Zhang, Q.; Srivastava, A.; Butler, J.M.; Goldstein, Joel; Velthuis, J.; Radeka, V.; Zhu, R.-Y.; Lutz, P.; de Roeck, A.; Elsener, K.; Gaddi, A.; Gerwig, H.; Grefe, C.; Klempt, W.; Linssen, L.; Schlatter, D.; Speckmayer, P.; Thom, J.; Yang, J.; Christian, D.C.; Cihangir, S.; Cooper, W.E.; Demarteau, M.; Fisk, H.E.; Garren, L.A.; Krempetz, K.; Kutschke, R.K.; Lipton, R.; Para, A.; Tschirhart, R.; Wenzel, H.; Yarema, R.; Grunewald, M.; Pankov, A.; U., Gomel State Tech.; Dutta, T.; Dauncey, P.D.; Balbuena, J.P.; Fleta, C.; Lozano, M.; Ullan, M.; Christian, G.B.; Faus-Golfe, A.; Fuster, J.; Lacasta, C.; Marinnas, C.; Vos, M.; Duarte, J.; Fernandez, M.; Gonzalez, J.; Jaramillo, R.; Lopez, Virto A.; Martinez-Eivero, C.; Moya, D.; Ruiz-Mimeno, A.; Vila, I.; Colledani, C.; Dorokhov, A.; Hu-Guo, C.; Winter, M.; Moortgat-Pick, G.; Onoprienko, D.V.; Kim, G.N.; Park, H.; Adloff, C.; Blaha, J.; Blaising, J.-J.; Cap, S.; Chefdeville, M.; Drancourt, C.; Espargiliare, A.; Gaglione, R.; Geffroy, N.; Jacquemier, J.; Karyotakis, Y.; Prast, J.; Vouters, G.; Gronberg, J.; Walston, S.; Wright, D.; Sawyer, L.; Laloum, M.; Ciobanu, C.; Chauveau, J.; Savoy-Navarro, A.; Andricek, L.; Moser, H.-G.; Cowan, R.f.; Fisher, P.; Yamamoto, R.K.; Kenney, ClMl; Boos, E.E.; Merkin, M.; Chen, S.; Chakraborty, D.; Dyshkant, A.; Hedin, D.; Zutshi, V.; Galkin, V.; D'Ascenzo, N.; Ossetski, D.; Saveliev, V.; Kapusta, F.; De Masi, R.; Vrba, V.; Lu, C.; McDonald, K.T.; Smith, A.J.S.; Bortoletto, D.; Coath, R.; Crooks, J.; Damerell, C.; Gibson, M.; Nichols, A.; Stanitzki, M.; Strube, J.; Turchetta, R.; Tyndel, M.; Weber, M.; Worm, S.; Zhang, Z.; Barklow, T.L.; Belymam, A.; Breidenbach, M.; Cassell, R.; Craddock, W.; Deaconu, C.; Dragone, A.; Graf, N.A.; Haller, G.; Herbst, R.; Hewett, J.L.; Jaros, J.A.; Johnson, A.S.; Kim, P.C.; MacFarlane, D.B.; Markiewicz, T.; Maruyama, T.; McCormick, J.; Moffeit, K.; Neal, H.A.; Nelson, T.K.; Oriunno, M.; Partridge, R.; Peskin, M.E.; Rizzo, T.G.; Rowson, P.; Su, D.; Woods, M.; Chakrabarti, S.; Dieguez, A.; Garrido, Ll.; Kaminski, J.; Conway, J.S.; Chertok, M.; Gunion, J.; Holbrook, B.; Lander, R.L.; Tripathi, S.M.; Fadeyev, V.; Schumm, B.A.; Oreglia, M.; Gill, J.; Nauenberg, U.; Oleinik, G.; Wagner, S.R.; Ranjan, K.; Shivpuri, R.; Varner, G.S.; Orava, R.; Van Kooten, R.; Bilki, B.; Charles, M.; Kim, T.J.; Mallik, U.; Norbeck, E.; Onel, Y.; Brau, B.P.; Willocq, S.; Taylor, G.N.; Riles, Keith; Yang, H.-J.; Kriske, R.; Cremaldi, L.; Rahmat, R.; Lastovicka-Medin, G.; Seidel, S.; Hildreth, M.D.; Wayne, M.; Brau, J.E.; Frey, R.; Sinev, N.; Strom, D.M.; Torrence, E.; Banda, Y.; Burrows, P.N.; Devetak, E.; Foster, B.; Lastovicka, T.; Li, Y.-M.; Nomerotski, A.; Riera-Babures, J.; Vilasis-Cardona, X.; Manly, S.; Adeva, B.; Iglesias Escudero, C.; Vazquez Regueiro, P.; Saborido Silva, J.J.; Gallas Torreira, A.; Gao, D.; Jie, W.; Jungfeng, Y.; Li, C.; Liu, S.; Liu, Y.; Sun, Y.; Wang, Q.; Yi, J.; Yonggang, W.; Zhao, Z.; De, K.; Farbin, A.; Park, S.; Smith, J.; White, A.P.; Yu, J.; Lou, X.C.; Abe, T.; Iwasaki, M.; Lubatti, H.J.; Band, H.R.; Feyzi, F.; Prepost, R.; Karchin, P.E.; Milstene, C.; Baltay, C.; Dhawan, S.; Kwon, Y.-J.

2009-01-01

Letter of intent describing SiD (Silicon Detector) for consideration by the International Linear Collider IDAG panel. This detector concept is founded on the use of silicon detectors for vertexing, tracking, and electromagnetic calorimetry. The detector has been cost-optimized as a general-purpose detector for a 500 GeV electron-positron linear collider.

Electron paramagnetic resonance investigations of Fe3+ doped layered TiInS2 and TiGaSe2 single crystals

International Nuclear Information System (INIS)

Faik, Mikailov; Bulat, Rameev; Sinan, Kazan; Bekir, Aktash; Faik, Mikailov; Bulat, Rameev

2005-01-01

Full text : TiInS 2 and TiGaSe 2 single crystals doped by paramagnetic Fe ions have been studied at room temperature by Electron Paramagnetic Resonance (EPR) technique. A fine structure of EPR spectra of paramagnetic Fe 3 + ions was observed. The spectra were interpreted to correspond to the transitions among spin multiplet which are splitted by the local ligand crystal field (CF) of orthorhombic symmetry. Four equivalent Fe 3 + centers have been observed in the EPR spectra and the local symmetry of crystal field at the Fe 3 + site and CF parameters were determined. It was established that symmetry axis of the axial component in the CF is making an angle of about 48 and 43 degree with the plane of layers of TiInS 2 and TiGaSe 2 crystals respectively. Experimental results indicate that the Fe ions substitute In (GA) at the center of InS 4 (GaSe 4 ) tetrahedrons, and the rhombic distortion of the CF is caused by the TI ions located in the trigonal cavities between the tethedral complexes

Spin-1/2 Heisenberg antiferromagnet on the pyrochlore lattice: An exact diagonalization study

Science.gov (United States)

Chandra, V. Ravi; Sahoo, Jyotisman

2018-04-01

We present exact diagonalization calculations for the spin-1/2 nearest-neighbor antiferromagnet on the pyrochlore lattice. We study a section of the lattice in the [111] direction and analyze the Hamiltonian of the breathing pyrochlore system with two coupling constants J1 and J2 for tetrahedra of different orientations and investigate the evolution of the system from the limit of disconnected tetrahedra (J2=0 ) to a correlated state at J1=J2 . We evaluate the low-energy spectrum, two and four spin correlations, and spin chirality correlations for a system size of up to 36 sites. The model shows a fast decay of spin correlations and we confirm the presence of several singlet excitations below the lowest magnetic excitation. We find chirality correlations near J1=J2 to be small at the length scales available at this system size. Evaluation of dimer-dimer correlations and analysis of the nature of the entanglement of the tetrahedral unit shows that the triplet sector of the tetrahedron contributes significantly to the ground-state entanglement at J1=J2 .

SHAPE GENERATION BY MEANS OF A NEW METHOD OF ORTHOGRAPHIC REPRESENTATION ("PROEKTIVOGRAFIYA": DRAWINGS OF MULTI-COMPONENT POLYHEDRA

Directory of Open Access Journals (Sweden)

Andrey Ivashchenko Viktorovich

2012-10-01

Full Text Available The authors analyze the capabilities of a traditional set of shape generation techniques that employ orthographic representation in the generation of polyhedra with account for the advanced approach to the research of new multi-nuclear structures. In the past, designs based on one nucleus were used in practice. The use of two or more nuclei is considered in the article. In the most common case, the resulting system of planes will constitute multiple orthographic representations. The characteristics of a binuclear system depend on the mutual positions and relation of dimensions of the nuclei. In addition to regular parameters, complete description of the system need particular supplementary parameters that determine the mutual positions of the nuclei. Increase in the number of nuclei causes increase in the number of descriptive parameters. The authors provide examples of binuclear systems composed of tetrahedrons, cubes, and dodecahedrons, implemented in the Delphi medium. The results can be exported into any three-dimensional modeling system with a view to their further study and use.

HPLC-DAD-MS Profiling of Polyphenols Responsible for the Yellow-Orange Color in Apple Juices of Different French Cider Apple Varieties.

Science.gov (United States)

Le Deun, Erell; Van der Werf, Remmelt; Le Bail, Gildas; Le Quéré, Jean-Michel; Guyot, Sylvain

2015-09-09

The pigments responsible for the yellow-orange coloration of apple juices have remained largely unknown up to now. Four French cider apple juices were produced in conditions similar to those used in the cider-making industry. The oxidized juices, characterized using the CIE L a b parameters, displayed various colors depending on the apple variety and native phenolic composition. HPLC-DAD-MS revealed contrasting pigment profiles related to oxidized tanning and nontanning molecules. The latter were divided into two groups according to their polarity and their visible spectra. With regard to phenolic classes, flavanol monomers and hydroxycinnamic acids played an essential role in the formation of oxidation products. Interestingly, dihydrochalcones appeared to include precursors of some yellow compounds. Indeed, the yellow pigment phloretin xyloglucoside oxidation product (PXGOPj), derived from phloretin xyloglucoside, was clearly identified in apple juices as a xyloglucose analogue of the yellow pigment phloridzin oxidation product (POPj), previously characterized in a model solution by Le Guernevé et al. (Tetrahedron Lett. 2004, 45 (35), 6673-6677).

High-pressure polymorphism as a step towards high density structures of LiAlH{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Huang, Xiaoli; Duan, Defang; Li, Xin; Li, Fangfei; Huang, Yanping; Wu, Gang; Liu, Yunxian; Zhou, Qiang; Liu, Bingbing; Cui, Tian, E-mail: cuitian@jlu.edu.cn [State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012 (China)

2015-07-27

Two high density structures β- and γ-LiAlH{sub 4} are detected in LiAlH{sub 4}, a promising hydrogen storage compound, upon compression in diamond anvil cells, investigated with synchrotron X-ray diffraction and first-principle calculations. The joint of the experimental and theoretical results has confirmed the sequence of the pressure-induced structural phase transitions from α-LiAlH{sub 4} (space group P2{sub 1}/c) to β-LiAlH{sub 4} (P2{sub 1}/c-6C symmetry), and then to γ-LiAlH{sub 4} (space group Pnc2), which are not reported in previous literatures. At the α to β transition point for LiAlH{sub 4}, the estimated difference in cell volume is about 20%, while the transformation from β to γ phase is with a volume drop smaller than 1%. The α to β phase transition is accompanied by the local structure change from a AlH{sub 4} tetrahedron into a AlH{sub 6} octahedron, which contributes to a large volume collapse.

Structures of metal complexes with anions of di(hydroxymethyl)phosphinic and di(chloromethyl)phosphinic acids

International Nuclear Information System (INIS)

Sergienko, V.S.; Aleksandrov, G.G.

2001-01-01

The structural peculiarities of the different metals [Cu, Ni, rare earths (La, Nd, Er, Lu), Ag, Li, Na, Sr] with anions of di-substituted monophosphonic acids - di(hydroxymethyl) phosphonic acid (HOCH 2 ) 2 PO 2 - (L 1 ) and di(chloromethyl) phosphonic acid (ClCH 2 ) 2 PO 2 - (L 2 ), and the methods of coordinating ligands L 1 and L 2 with these metals were viewed. Coordination number of metal decreases from eight in the case of La, Nd to seven for Er, and further to six for Lu with decreasing size of rare earth element. M-O bond lengths decrease the same way. The LiL 2 · H 2 O structure was determined, Li atom shows tetrahedron coordination by three oxygen atoms of the three ligands L 2 and atom O(ω) of water molecule. The ligand L 1 are acting as a tetradentate chelate μ 3 -bridge function in the structure of the Sr(L 1 ) 2 compound. The interval of Sr-O distances comprises 2.521 - 2.683 A [ru

First-order character of the displacive structural transition in BaWO4

International Nuclear Information System (INIS)

Tan Da-Yong; Xiao Wan-Sheng; Zhou Wei; Chen Ming; Xiong Xiao-Lin; Song Mao-Shuang

2012-01-01

Nearly all displacive transitions have been considered to be continuous or second order, and the rigid unit mode (RUM) provides a natural candidate for the soft mode. However, in-situ X-ray diffraction and Raman measurements show clearly the first-order evidences for the scheelite-to-fergusonite displacive transition in BaWO 4 : a 1.6% volume collapse, coexistence of phases, and hysteresis on release of pressure. Such first-order signatures are found to be the same as the soft modes in BaWO 4 , which indicates the scheelite-to-fergusonite displacive phase transition hides a deeper physical mechanism. By the refinement of atomic displacement parameters, we further show that the first-order character of this phase transition stems from a coupling of large compression of soft BaO 8 polyhedrons to the small displacive distortion of rigid WO 4 tetrahedrons. Such a coupling will lead to a deeper physical insight in the phase transition of the common scheelite-structured compounds. (condensed matter: structural, mechanical, and thermal properties)

Crystal structure of molybdenyl tetrapolyphosphate (MoO)2P4O13

International Nuclear Information System (INIS)

Minacheva, L.Kh.; Antsishkina, A.S.; Lavrov, A.V.; Sakharova, V.G.; Nikolaev, V.P.; Poraj-Koshits, M.A.

1979-01-01

The structure of crystals of molybdenyl tetrapolyphosphate [MoO] 2 P 4 O 13 has been determined. The substance is crystallized in the monoclinic syngony with the following parameters of the elementary cell: a=8.288 (2); b=10.690 (3); c=19.529 (5) A; γ=106.7 (3) deg. The structural units are molybdenyl groups MoO(3 + ) and polyphosphate anions P 4 O 13 (6 - ) that are composed of four PO 4 tetrahedrons whose apexes are connected in series. Three atoms of phasphate anion form the ''internal'' P-O-P bridges, while the remaining oxygen atoms, the ''external'' P-O-Mo bridges. The optimum temperature of crystals synthesis is 450 - 460 deg C. A mixture of phase of MoO 2 P 4 O 13 and Mo(PO 3 ) 3 is obtained as temperature is raised up to 600 deg C. Consequently, the stepwise dissociation of molybdenyl ions with the splitting off of oxygen and gradual reduction in the degree of molybdenum oxidation (MoO 2 ) 2+ → (MoO) 3+ → Mo 3+ occurs in the solution

Solid Phase Equilibrium Relations in the CaO-SiO2-Nb2O5-La2O3 System at 1273 K

Science.gov (United States)

Qiu, Jiyu; Liu, Chengjun

2018-02-01

Silicate slag system with additions Nb and RE formed in the utilization of REE-Nb-Fe ore deposit resources in China has industrial uses as a metallurgical slag system. The lack of a phase diagram, theoretical, and thermodynamic information for the multi-component system restrict the comprehensive utilization process. In the current work, solid phase equilibrium relations in the CaO-SiO2-Nb2O5-La2O3 quaternary system at 1273 K (1000 °C) were investigated experimentally by the high-temperature equilibrium experiment followed by X-ray diffraction, scanning electron microscope, and energy dispersive spectrometer. Six spatial independent tetrahedron fields in the CaO-SiO2-Nb2O5-La2O3 system phase diagram were determined by the Gibbs Phase Rule. The current work combines the mass fraction of equilibrium phase and corresponding geometric relation. A determinant method was deduced to calculate the mass fraction of equilibrium phase in quaternary system according to the Mass Conservation Law, the Gibbs Phase Rule, the Lever's Rule, and the Cramer Law.

Mo{sub 2}B{sub 4}O{sub 9} - connecting borate and metal-cluster chemistry

Energy Technology Data Exchange (ETDEWEB)

Schmitt, Martin K.; Huppertz, Hubert [Institut fuer Allgemeine, Anorganische und Theoretische Chemie, Universitaet Innsbruck (Austria); Janka, Oliver; Poettgen, Rainer [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster (Germany); Benndorf, Christopher [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster (Germany); Institut fuer Physikalische Chemie, Universitaet Muenster (Germany); Institut fuer Mineralogie, Kristallographie und Materialwissenschaften, Universitaet Leipzig (Germany); Oliveira, Marcos de Jr. [Sao Carlos Institute of Physics, University of Sao Paulo, Sao Carlos (Brazil); Eckert, Hellmut [Institut fuer Physikalische Chemie, Universitaet Muenster (Germany); Sao Carlos Institute of Physics, University of Sao Paulo, Sao Carlos (Brazil); Pielnhofer, Florian; Tragl, Amadeus-Samuel [Institut fuer Anorganische Chemie, Universitaet Regensburg (Germany); Weihrich, Richard [Institut fuer Materials Resource Management, Universitaet Augsburg (Germany); Joachim, Bastian [Institut fuer Mineralogie und Petrographie, Universitaet Innsbruck (Austria); Johrendt, Dirk [Department Chemie, Ludwig-Maximilians-Universitaet Muenchen (Germany)

2017-06-01

We report on the first thoroughly characterized molybdenum borate, which was synthesized in a high-pressure/high-temperature experiment at 12.3 GPa/1300 C using a Walker-type multianvil apparatus. Mo{sub 2}B{sub 4}O{sub 9} incorporates tetrahedral molybdenum clusters into an anionic borate crystal structure - a structural motif that has never been observed before in the wide field of borate crystal chemistry. The six bonding molecular orbitals of the [Mo{sub 4}] tetrahedron are completely filled with 12 electrons, which are fully delocalized over the four molybdenum atoms. This finding is in agreement with the results of the magnetic measurements, which confirmed the diamagnetic character of Mo{sub 2}B{sub 4}O{sub 9}. The two four-coordinated boron sites can be differentiated in the {sup 11}B MAS-NMR spectrum because of the strongly different degrees of local distortions. Experimentally obtained IR and Raman bands were assigned to vibrational modes based on DFT calculations. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)