Science.gov

Sample records for modeling group iv

  1. Transferable tight-binding model for strained group IV and III-V materials and heterostructures

    NASA Astrophysics Data System (ADS)

    Tan, Yaohua; Povolotskyi, Michael; Kubis, Tillmann; Boykin, Timothy B.; Klimeck, Gerhard

    2016-07-01

    It is critical to capture the effect due to strain and material interface for device level transistor modeling. We introduce a transferable s p3d5s* tight-binding model with nearest-neighbor interactions for arbitrarily strained group IV and III-V materials. The tight-binding model is parametrized with respect to hybrid functional (HSE06) calculations for varieties of strained systems. The tight-binding calculations of ultrasmall superlattices formed by group IV and group III-V materials show good agreement with the corresponding HSE06 calculations. The application of the tight-binding model to superlattices demonstrates that the transferable tight-binding model with nearest-neighbor interactions can be obtained for group IV and III-V materials.

  2. Group-IV semiconductor compounds

    SciTech Connect

    Berding, M.A.; Sher, A.; van Schilfgaarde, M.

    1997-08-01

    Properties of ordered group-IV compounds containing carbon, silicon, and germanium are calculated within the local density approximation. Twenty-seven fully relaxed compounds represented by seven different compound structures are compared and, with the exception of SiC, all compounds are found to be metastable. Two trends emerge: carbon-germanium bonds are disfavored, and compounds that have carbon on a common sublattice are the least unbound because of their relatively low strain. When carbon shares a sublattice with silicon or germanium, the large strain results in a narrowing of the band gap, and in some cases the compound is metallic. The most promising structures with the lowest excess energy contain carbon on one sublattice and although they do not lattice match to silicon, they match rather well to silicon carbide. {copyright} {ital 1997} {ital The American Physical Society}

  3. IVS Working Group 4: VLBI Data Structures

    NASA Technical Reports Server (NTRS)

    Gipson, John

    2010-01-01

    In 2007 the IVS Directing Board established IVS Working Group 4 on VLBI Data Structures. This note discusses the current VLBI data format, goals for a new format, the history and formation of the Working Group, and a timeline for the development of a new VLBI data format.

  4. Giant piezoelectricity of monolayer group IV monochalcogenides

    NASA Astrophysics Data System (ADS)

    Fei, Ruixiang; Li, Wenbin; Li, Ju; Yang, Li

    We predict enormous, anisotropic piezoelectric effects in intrinsic monolayer group IV monochalcogenides (MX, M =Sn or Ge, X =Se or S), including SnSe, SnS, GeSe, and GeS. Using first-principle simulations based on the modern theory of polarization, we find that their piezoelectric coefficients are about one to two orders of magnitude larger than those of other 2D materials, such as MoS2 and GaSe, and bulk quartz and AlN which are widely used in industry. This enhancement is a result of the unique ``puckered'' C2v symmetry and electronic structure of monolayer group IV monochalcogenides. Given the achieved experimental advances in the fabrication of monolayers, their flexible character, and ability to withstand enormous strain, these 2D structures with giant piezoelectric effects may be promising for a broad range of applications such as nano-sized sensors, piezotronics, and energy harvesting in portable electronic devices.

  5. Models, Part IV: Inquiry Models.

    ERIC Educational Resources Information Center

    Callison, Daniel

    2002-01-01

    Discusses models for information skills that include inquiry-oriented activities. Highlights include WebQuest, which uses Internet resources supplemented with videoconferencing; Minnesota's Inquiry Process based on the Big Six model for information problem-solving; Indiana's Student Inquiry Model; constructivist learning models for inquiry; and…

  6. Group IV photonics for the mid infrared

    NASA Astrophysics Data System (ADS)

    Soref, Richard

    2013-02-01

    This paper outlines the challenges and benefits of applying silicon-based photonic techniques in the 2 to 5 μm midinfrared (MIR) wavelength range for chem.-bio-physical sensing, medical diagnostics, industrial process control, environmental monitoring, secure communications, Ladar, active imaging, and high-speed communications at 2 μm. Onchip passive and active components, mostly waveguided, will enable opto-electronic CMOS or BiCMOS integrated "circuits" for system-on-a-chip applications such as spectroscopy and lab-on-a-chip. Volume manufacture in a silicon foundry is expected to yield low-cost (or even disposable) chips with benefits in size-weight-power and ruggedness. This is "long-wavelength optoelectronic integration on silicon" which we call LIOS. Room temperature operation appears feasible, albeit with performance compromises at 4 to 5 μm. In addition to the electronics layer (which may include RF wireless), a 3-D LIOS chip can include several inter-communicating layers utilizing the photonic, plasmonic, photoniccrystal and opto-electro-mechanical technologies. The LIOS challenge can be met by (1) discovering new physics, (2) employing "new" IV and III-V alloys, (3) scaling-up and modifying telecom components, and (4) applying nonlinearoptical wavelength conversion in some cases. This paper presents proposals for MIR chip spectrometers employing frequency-comb and Ge blackbody sources. Active heterostructures employing Si, Ge, SiGe, GeSn and SiGeSn are key for laser diodes, photodetectors, LEDs, switches, amplifiers, and modulators that provide totally monolithic foundry integration, while numerous III-V semiconductor MIR devices within the InGaAsSb and InGaAsP families offer practical hybrid integration on Si PICs. Interband cascade and quantum cascade lasers on Ge waveguides are important in this context.

  7. A Renormalisation Group Method. IV. Stability Analysis

    NASA Astrophysics Data System (ADS)

    Brydges, David C.; Slade, Gordon

    2015-05-01

    This paper is the fourth in a series devoted to the development of a rigorous renormalisation group method for lattice field theories involving boson fields, fermion fields, or both. The third paper in the series presents a perturbative analysis of a supersymmetric field theory which represents the continuous-time weakly self-avoiding walk on . We now present an analysis of the relevant interaction functional of the supersymmetric field theory, which permits a nonperturbative analysis to be carried out in the critical dimension . The results in this paper include: proof of stability of the interaction, estimates which enable control of Gaussian expectations involving both boson and fermion fields, estimates which bound the errors in the perturbative analysis, and a crucial contraction estimate to handle irrelevant directions in the flow of the renormalisation group. These results are essential for the analysis of the general renormalisation group step in the fifth paper in the series.

  8. IVS Working Group 4: VLBI Data Structures

    NASA Astrophysics Data System (ADS)

    Gipson, J.

    2012-12-01

    I present an overview of the "openDB format" for storing, archiving, and processing VLBI data. In this scheme, most VLBI data is stored in NetCDF files. NetCDF has the advantage that there are interfaces to most common computer languages including Fortran, Fortran-90, C, C++, Perl, etc, and the most common operating systems including Linux, Windows, and Mac. The data files for a particular session are organized by special ASCII "wrapper" files which contain pointers to the data files. This allows great flexibility in the processing and analysis of VLBI data. For example it allows you to easily change subsets of the data used in the analysis such as troposphere modeling, ionospheric calibration, editing, and ambiguity resolution. It also allows for extending the types of data used, e.g., source maps. I present a roadmap to transition to this new format. The new format can already be used by VieVS and by the global mode of solve. There are plans in work for other software packages to be able to use the new format.

  9. Fleet Followup on Group IV Graduates of A Schools.

    ERIC Educational Resources Information Center

    Anderson, Adolph V.; And Others

    As part of the Navy's research on Project 100,000 personnel, several small units of Group IV men were assigned to six regular Class A Schools to determine whether or not they could successfully complete training in essentially unmodified courses. A 19-item questionnaire designed to gather information relative to work performance, potential, and…

  10. Group IV nanotube transistors for next generation ubiquitous computing

    NASA Astrophysics Data System (ADS)

    Fahad, Hossain M.; Hussain, Aftab M.; Sevilla Torres, Galo A.; Banerjee, Sanjay K.; Hussain, Muhammad M.

    2014-06-01

    Evolution in transistor technology from increasingly large power consuming single gate planar devices to energy efficient multiple gate non-planar ultra-narrow (< 20 nm) fins has enhanced the scaling trend to facilitate doubling performance. However, this performance gain happens at the expense of arraying multiple devices (fins) per operation bit, due to their ultra-narrow dimensions (width) originated limited number of charges to induce appreciable amount of drive current. Additionally arraying degrades device off-state leakage and increases short channel characteristics, resulting in reduced chip level energy-efficiency. In this paper, a novel nanotube device (NTFET) topology based on conventional group IV (Si, SiGe) channel materials is discussed. This device utilizes a core/shell dual gate strategy to capitalize on the volume-inversion properties of an ultra-thin (< 10 nm) group IV nanotube channel to minimize leakage and short channel effects while maximizing performance in an area-efficient manner. It is also shown that the NTFET is capable of providing a higher output drive performance per unit chip area than an array of gate-all-around nanowires, while maintaining the leakage and short channel characteristics similar to that of a single gate-all-around nanowire, the latter being the most superior in terms of electrostatic gate control. In the age of big data and the multitude of devices contributing to the internet of things, the NTFET offers a new transistor topology alternative with maximum benefits from performance-energy efficiency-functionality perspective.

  11. Synthesis and Properties of Group IV Graphane Analogues

    NASA Astrophysics Data System (ADS)

    Goldberger, Joshua

    Similar to how carbon networks can be sculpted into low-dimensional allotropes such as fullerenes, nanotubes, and graphene with fundamentally different properties, it is possible to create similar ligand terminated sp3-hybridized honeycomb graphane derivatives containing Ge or Sn that feature unique and tunable properties. Here, we will describe our recent success in the creation of hydrogen and organic-terminated group IV graphane analogues, from the topochemical deintercalation of precursor Zintl phases, such as CaGe2. We will discuss how the optical, electronic, and thermal properties of these materials can be systematically controlled by substituting either the surface ligand or via alloying with other Group IV elements. Additionally, we have also developed an epitopotaxial approach for integrating precise thicknesses of germanane layers onto Ge wafers that combines the epitaxial deposition of CaGe2 precursor phases with the topotactic interconversion into the 2D material. Finally, we will describe our recent efforts on the synthesis and crystal structures of Sn-containing graphane alloys in order to access novel topological phenomena predicted to occur in these graphanes.

  12. Beyond the Standard Model IV

    NASA Astrophysics Data System (ADS)

    Gunion, John F.; Han, Tao; Ohnemus, James

    1995-08-01

    The Table of Contents for the book is as follows: * Preface * Organizing and Advisory Committees * PLENARY SESSIONS * Looking Beyond the Standard Model from LEP1 and LEP2 * Virtual Effects of Physics Beyond the Standard Model * Extended Gauge Sectors * CLEO's Views Beyond the Standard Model * On Estimating Perturbative Coefficients in Quantum Field Theory and Statistical Physics * Perturbative Corrections to Inclusive Heavy Hadron Decay * Some Recent Developments in Sphalerons * Searching for New Matter Particles at Future Colliders * Issues in Dynamical Supersymmetry Breaking * Present Status of Fermilab Collider Accelerator Upgrades * The Extraordinary Scientific Opportunities from Upgrading Fermilab's Luminosity ≥ 1033 cm-2 sec-1 * Applications of Effective Lagrangians * Collider Phenomenology for Strongly Interacting Electroweak Sector * Physics of Self-Interacting Electroweak Bosons * Particle Physics at a TeV-Scale e+e- Linear Collider * Physics at γγ and eγ Colliders * Challenges for Non-Minimal Higgs Searchers at Future Colliders * Physics Potential and Development of μ+μ- Colliders * Beyond Standard Quantum Chromodynamics * Extracting Predictions from Supergravity/Superstrings for the Effective Theory Below the Planck Scale * Non-Universal SUSY Breaking, Hierarchy and Squark Degeneracy * Supersymmetric Phenomenology in the Light of Grand Unification * A Survey of Phenomenological Constraints on Supergravity Models * Precision Tests of the MSSM * The Search for Supersymmetry * Neutrino Physics * Neutrino Mass: Oscillations and Hot Dark Matter * Dark Matter and Large-Scale Structure * Electroweak Baryogenesis * Progress in Searches for Non-Baryonic Dark Matter * Big Bang Nucleosynthesis * Flavor Tests of Quark-Lepton * Where are We Coming from? What are We? Where are We Going? * Summary, Perspectives * PARALLEL SESSIONS * SUSY Phenomenology I * Is Rb Telling us that Superpartners will soon be Discovered? * Dark Matter in Constrained Minimal

  13. Group IV nanoparticles: synthesis, properties, and biological applications.

    PubMed

    Fan, Jiyang; Chu, Paul K

    2010-10-01

    In this review, the emerging roles of group IV nanoparticles including silicon, diamond, silicon carbide, and germanium are summarized and discussed from the perspective of biologists, engineers, and medical practitioners. The synthesis, properties, and biological applications of these new nanomaterials have attracted great interest in the past few years. They have gradually evolved into promising biomaterials due to their innate biocompatibility; toxic ions are not released when they are used in vitro or in vivo, and their wide fluorescence spectral regions span the near-infrared, visible, and near-ultraviolet ranges. Additionally, they generally have good resistance against photobleaching and have lifetimes on the order of nanoseconds to microseconds, which are suitable for bioimaging. Some of the materials possess unique mechanical, chemical, or physical properties, such as ultrachemical and thermal stability, high hardness, high photostability, and no blinking. Recent data have revealed the superiority of these nanoparticles in biological imaging and drug delivery. PMID:20730824

  14. Polarization and valley switching in monolayer group-IV monochalcogenides

    NASA Astrophysics Data System (ADS)

    Hanakata, Paul Z.; Carvalho, Alexandra; Campbell, David K.; Park, Harold S.

    2016-07-01

    Group-IV monochalcogenides are a family of two-dimensional puckered materials with an orthorhombic structure that is comprised of polar layers. In this article, we use first principles calculations to show the multistability of monolayer SnS and GeSe, two prototype materials where the direction of the puckering can be switched by application of tensile stress or electric field. Furthermore, the two inequivalent valleys in momentum space, which are dictated by the puckering orientation, can be excited selectively using linearly polarized light, and this provides an additional tool to identify the polarization direction. Our findings suggest that SnS and GeSe monolayers may have observable ferroelectricity and multistability, with potential applications in information storage.

  15. Ferroelectricity and Phase Transitions in Monolayer Group-IV Monochalcogenides.

    PubMed

    Fei, Ruixiang; Kang, Wei; Yang, Li

    2016-08-26

    Ferroelectricity usually fades away as materials are thinned down below a critical value. We reveal that the unique ionic-potential anharmonicity can induce spontaneous in-plane electrical polarization and ferroelectricity in monolayer group-IV monochalcogenides MX (M=Ge, Sn; X=S, Se). An effective Hamiltonian has been successfully extracted from the parametrized energy space, making it possible to study the ferroelectric phase transitions in a single-atom layer. The ferroelectricity in these materials is found to be robust and the corresponding Curie temperatures are higher than room temperature, making them promising for realizing ultrathin ferroelectric devices of broad interest. We further provide the phase diagram and predict other potentially two-dimensional ferroelectric materials. PMID:27610884

  16. Doping of indium phosphide with group IV elements

    SciTech Connect

    Zakharenkov, L.F.; Samorukov, B.E.; Zykov, A.M.

    1985-06-01

    This paper studies the doping of single crystals of indium phosphide (InP) with group IV elements using data obtained by measuring the total charge concentration of additives and carriers. Single crystals of indium phosphide were grown by the Czochralski method from liquid melts with a liquid hermetic seal in quartz cubicles. The total impurity concentration was determined by atomic-absorption analysis with + or - 10% error. In order to explain the behavior of germanium and tin in indium phosphide, the authors consider the bond energies of additives in indium phosphide and their tetrahedral radii. The authors conclude that the established higher amphoteric character of germanium with respect to tin is probably explained by the moduli of elasticity of the doped crystal.

  17. A nuclear magnetic resonance probe of group IV clathrates

    NASA Astrophysics Data System (ADS)

    Gou, Weiping

    The clathrates feature large cages of silicon, germanium, or tin, with guest atoms in the cage centers. The group IV clathrates are interesting because of their thermoelectric efficiency, and their glasslike thermal conductivity at low temperatures. Clathrates show a variety of properties, and the motion of cage center atoms is not well understood. In Sr8Ga16Ge30, we found that the slow atomic motion in the order 10-5 s is present in this system, which is much slower than what would be expected for standard atomic dynamics. NMR studies of Sr8Ga16Ge30 showed that Knight shift and T1 results are consistent with low density metallic behavior. The lineshapes exhibit changes consistent with motional narrowing at low temperatures, and this indicates unusually slow hopping rates. To further investigate this behavior, we made a series of measurements using the Carr-Purcell-Meiboom-Gill NMR sequence. Fitting the results to a hopping model yielded an activation energy of 4.6 K. We can understand all of our observations in terms of non-resonant atomic tunneling between asymmetric sites within the cages, in the presence of disorder. For Ba8Ga16Ge30, the relaxation behavior (T1) deviates from the Korringa relation, and the Knight shift and linewidth change with temperature. Those results could be explained by carrier freezout, and the development of a dilute set of magnetic moments due to these localized carriers. For Ba8Ga 16Ge30 samples made from Ga flux, we observed different T1 and Knight shift behavior as compared to n type material. This is due to the differences in carrier type among these different samples. The p type sample has a smaller Knight shift and a slower relaxation rate than n type samples made with the stoichiometric ratio, which is consistent with a change in orbital symmetry between the conduction and valence bands. WDS study for Ba8Al10Ge36 showed the existence of vacancies in the Al-deficient samples, which results in some degree of ordering of Al

  18. Atmosphere of Mars: Mariner IV Models Compared.

    PubMed

    Fjeldbo, G; Fjeldbo, W C; Eshleman, V R

    1966-09-23

    Three classes of models for the atmosphere of Mars differ in identifying the main ionospheric layer measured by Mariner IV as being analogous to a terrestrial F(2), F(1), or E layer. At an altitude of several hundred kilometers, the relative atmospheric mass densities for these models (in the order named) are approximately 1, 10(2), and 10(4), and the temperatures are roughly 100 degrees , 200 degrees , and 400 degrees K. Theory and observation are in best agreement for an F, s model, for which photodissociation of CO(2), and diffusive separation result in an atomic-oxygen upper atmosphere, with O(+) being the principal ion in the isothermal topside of the ionosphere. The mesopause temperature minimum would be at or below the freezing point of CO(2), and dry ice particles would be expected to form. However, an F(1) model, with molecular ions in a mixed and warmer upper atmosphere, might result if photodissociation and diffusive separation are markedly less than would be expected from analogy with Earth's upper atmosphere. The E model proposed by Chamberlain and McElroy appears very unlikely; it is not compatible with the measured ionization profile unless rather unlikely assumptions are made about the values, and changes with height, of the effective recombination coefficient and the average ion mass. Moreover our theoretical heat-budget computations for the atmospheric region probed by Mariner IV indicate markedly lower temperatures and temperature gradients than were obtained for the E model. PMID:17749730

  19. Ratchet model for type IV pilus retraction

    NASA Astrophysics Data System (ADS)

    Lindén, Martin; Tuohimaa, Tomi; Jonsson, Ann-Beth; Wallin, Mats

    2004-03-01

    Type IV pilus rectraction is required for twitching motility in a wide range of bacteriae, including Neisseria gonorrhoeae, Myxococcus xanthus and Pseudomonas aeruginosa. The mechanism of retraction is believed to be filament disassembly mediated by PilT, a member of the AAA family of motor proteins. Recent laser tweezer measurements of the force-velocity relation of PilT in N. gonorrhoeae, reveal that single PilT complexes generate forces of over 100 pN. We assume that PilT forms a cyclic ATPase surrounding the base of the pilus and formulate a model of retraction in terms of coupled flashing ratchets. We obtain a force-velocity relation by numerical simulation of the model which is in qualitative agreement with the experimental results.

  20. 77 FR 16508 - National Emission Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-21

    ..., was published on January 9, 2012 (77 FR 1268). EPA has established the public docket for the proposed...: Group IV Polymers and Resins; Pesticide Active Ingredient Production; and Polyether Polyols Production... pollutants: National Emission Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and...

  1. Estimation of the isotope effect on the lattice thermal conductivity of group IV and group III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Morelli, D. T.; Heremans, J. P.; Slack, G. A.

    2002-11-01

    The isotope effect on the lattice thermal conductivity for group IV and group III-V semiconductors is calculated using the Debye-Callaway model modified to include both transverse and longitudinal phonon modes explicitly. The frequency and temperature dependences of the normal and umklapp phonon-scattering rates are kept the same for all compounds. The model requires as adjustable parameters only the longitudinal and transverse phonon Grüneisen constants and the effective sample diameter. The model can quantitatively account for the observed isotope effect in diamond and germanium but not in silicon. The magnitude of the isotope effect is predicted for silicon carbide, boron nitride, and gallium nitride. In the case of boron nitride the predicted increase in the room-temperature thermal conductivity with isotopic enrichment is in excess of 100%. Finally, a more general method of estimating normal phonon-scattering rate coefficients for other types of solids is presented.

  2. Grouping Children for Instruction in Team Teaching. Module IV.

    ERIC Educational Resources Information Center

    York, L. Jean

    The fourth of seven modules on team teaching, this document deals with grouping children for instruction, in order that teachers may understand the purposes of grouping, the various kinds of grouping, the variables to be considered in choosing a method, the ways grouping can facilitate individualized instruction, and the need for a flexible…

  3. Psychometric Properties of the Generalized Anxiety Disorder Questionnaire for DSM-IV Among Four Racial Groups

    PubMed Central

    Robinson, Christina M.; Klenck, Suzanne C.; Norton, Peter J.

    2010-01-01

    The Generalized Anxiety Disorder Questionnaire-IV (GAD-Q-IV) is a self-report diagnostic measure of generalized anxiety disorder. Previous studies have established the psychometric properties of the GAD-Q-IV revealing excellent diagnostic specificity and sensitivity as well as good test-retest reliability and convergent and discriminant validity (Newman et al., 2002). Recent analyses with other measures of anxiety symptoms have revealed differences across racial or national groups. Given that the GAD-Q-IV was tested primarily on Caucasian (78%) participants, the purpose of this study was to demonstrate the psychometric properties of the GAD-Q-IV across four racial groups: African American, Caucasian, Hispanic/Latino, and Asian. A student sample of 585 undergraduate psychology students completed the GAD-Q-IV as well as other measures of anxiety symptoms. A clinical replication sample was obtained from 188 clinical participants who completed the GAD-Q-IV as part of a larger psychotherapy study. Results indicated excellent and very similar factor structures in the student sample, and similar psychometric properties across both samples across the racial groups. Implications for the use of the GAD-Q-IV across racial groups are discussed. PMID:20830629

  4. Wyoming's Early Settlement and Ethnic Groups, Unit IV.

    ERIC Educational Resources Information Center

    Robinson, Terry

    This unit on Wyoming's early settlement and ethnic groups provides concepts, activities, stories, charts, and graphs for elementary school students. Concepts include the attraction Wyoming held for trappers; the major social, economic, and religious event called "The Rendezvous"; the different ethnic and religious groups that presently inhabit…

  5. Bulk Modulus Calculations for Group-Iv Carbides and Group-Iii Nitrides

    NASA Astrophysics Data System (ADS)

    Mahmood, A.; Sansores, L. E.; Heiras, J.

    Wide band gap semiconductors such as group-IV carbides (SiC, GeC) and group-III nitrides (AlN, GaN and BN) are known to be important materials for novel semiconductor applications. They also have interesting mechanical properties such as having a particularly high value for their bulk modulus and are therefore potential candidates for hard coatings. In this paper we report the theoretical calculations for the bulk modulus for zincblende and wurzite polytypes of these materials. The Density Functional and Total-energy Pseudopotential Techniques in the Generalized Gradient approximation, an ab initio quantum mechanical method, is used to obtain the theoretical structure, from which equilibrium lattice parameters and volume of the cell versus pressure may be extracted. The Murnaghan's equation of state is then used to calculate bulk modulus under elastic deformation, which is related to the hardness of a material under certain conditions. The results for bulk modulus are compared with other theoretical and experimental values reported in the literature.

  6. Division Iv/v Working Group on Active B Stars

    NASA Astrophysics Data System (ADS)

    Peters, Geraldine J.; Jones, Carol E.; Townsend, Richard D.; Fabregat, Juan; Bjorkman, Karen S.; McSwain, M. Virginia; Mennickent, Ronald E.; Neiner, Coralie; Stee, Philippe; Fabregat, Juan

    2010-05-01

    The meeting of the Working Group on Active B Stars consisted of a business session followed by a scientific session containing nine talks. The titles of the talks and their presenters are listed below. We plan to publish a series of articles containing summaries of these talks in Issue No. 40 of the Be Star Newsletter. This report contains an account of the announcements made during the business session, an update on a forthcoming IAU Symposium on active B stars, a report on the status of the Be Star Newsletter, the results of the 2009 election of the SOC for the Working Group for 2009-12, a listing of the Working Group bylaws that were recently adopted, and a list of the scientific talks that we presented at the meeting.

  7. Adsorption and dynamics of group IV, V atoms and molecular oxygen on semiconductor group IV (0 0 1) surfaces

    NASA Astrophysics Data System (ADS)

    Afanasieva, T.

    2016-08-01

    In this review we address (1) the co-adsorption of group V (As, Sb, Bi) atoms and molecular oxygen on the Si(0 0 1) surface and (2) the adsorption and dynamics of Sb, Bi, Si and Ge ad-dimers on the Si(0 0 1) and Ge(0 0 1) surfaces. The adsorption and diffusion processes of group IV and V atoms on the (0 0 1) surfaces of group IV semiconductor surfaces have been studied using multi-configuration self-consistent field methods and density functional theory calculations. Results obtained by various types of first-principle total energy calculations are mutually compared and discussed. Our results demonstrate the capability of these quantum chemistry methods to provide relevant and reliable information on the interaction between adsorbate and semiconductor surfaces.

  8. Adsorption and dynamics of group IV, V atoms and molecular oxygen on semiconductor group IV (0 0 1) surfaces.

    PubMed

    Afanasieva, T

    2016-08-10

    In this review we address (1) the co-adsorption of group V (As, Sb, Bi) atoms and molecular oxygen on the Si(0 0 1) surface and (2) the adsorption and dynamics of Sb, Bi, Si and Ge ad-dimers on the Si(0 0 1) and Ge(0 0 1) surfaces. The adsorption and diffusion processes of group IV and V atoms on the (0 0 1) surfaces of group IV semiconductor surfaces have been studied using multi-configuration self-consistent field methods and density functional theory calculations. Results obtained by various types of first-principle total energy calculations are mutually compared and discussed. Our results demonstrate the capability of these quantum chemistry methods to provide relevant and reliable information on the interaction between adsorbate and semiconductor surfaces. PMID:27299666

  9. Divisions Iv-V / Working Group ap & Related Stars

    NASA Astrophysics Data System (ADS)

    Mathys, Gautier; Cunha, Margarida; Dworetsky, Michael; Kochukhov, Oleg; Kupka, Friedrich; LeBlanc, Francis; Monier, Richard; Paunzen, Ernst; Pintado, Olga; Piskunov, Nikolai; Ziznovsky, Jozef

    2012-04-01

    The purpose of the Working Group on Ap and Related Stars (ApWG) is to promote and facilitate research about stars in the spectral type range from B to early F that exhibit surface chemical peculiarities and related phenomena. This is a very active field of research, in which a wide variety of new developments have taken place since 2009, as illustrated by the following selected highlights.

  10. Introduction of bifunctional groups into mesoporous silica for enhancing uptake of thorium(IV) from aqueous solution.

    PubMed

    Yuan, Li-Yong; Bai, Zhi-Qiang; Zhao, Ran; Liu, Ya-Lan; Li, Zi-Jie; Chu, Sheng-Qi; Zheng, Li-Rong; Zhang, Jing; Zhao, Yu-Liang; Chai, Zhi-Fang; Shi, Wei-Qun

    2014-04-01

    The potential industrial application of thorium (Th), as well as the environmental and human healthy problems caused by thorium, promotes the development of reliable methods for the separation and removal of Th(IV) from environmental and geological samples. Herein, the phosphonate-amino bifunctionalized mesoporous silica (PAMS) was fabricated by a one-step self-assembly approach for enhancing Th(IV) uptake from aqueous solution. The synthesized sorbent was found to possess ordered mesoporous structures with uniform pore diameter and large surface area, characterized by SEM, XRD, and N2 sorption/desorption measurements. The enhancement of Th(IV) uptake by PAMS was achieved by coupling of an access mechanism to a complexation mechanism, and the sorption can be optimized by adjusting the coverage of the functional groups in the PAMS sorbent. The systemic study on Th(IV) sorption/desorption by using one coverage of PAMS (PAMS12) shows that the Th(IV) sorption by PAMS is fast with equilibrium time of less than 1 h, and the sorption capacity is more than 160 mg/g at a relatively low pH. The sorption isotherm has been successfully modeled by the Langmuir isotherm and D-R isotherm, which reveals a monolayer homogeneous chemisorption of Th(IV) in PAMS. The Th(IV) sorption by PAMS is pH dependent but ionic strength independent. In addition, the sorbed Th(IV) can be completely desorbed using 0.2 mol/L or more concentrated nitric acid solution. The sorption test performed in the solution containing a range of competing metal ions suggests that the PAMS sorbent has a desirable selectivity for Th(IV) ions. PMID:24617841

  11. Hydrogen-bond Specific Materials Modification in Group IV Semiconductors

    SciTech Connect

    Tolk, Norman H.; Feldman, L. C.; Luepke, G.

    2015-09-14

    impurity states under transient compression. This research focused on the characterization of photon and ion stimulated hydrogen related defect and impurity reactions and migration in solid state matter, which requires a detailed understanding of the rates and pathways of vibrational energy flow, of the transfer channels and of the coupling mechanisms between local vibrational modes (LVMs) and phonon bath as well as the electronic system of the host material. It should be stressed that researchers at Vanderbilt and William and Mary represented a unique group with a research focus and capabilities for low temperature creation and investigation of such material systems. Later in the program, we carried out a vigorous research effort addressing the roles of defects, interfaces, and dopants on the optical and electronic characteristics of semiconductor crystals, using phonon generation by means of ultrafast coherent acoustic phonon (CAP) spectroscopy, nonlinear characterization using second harmonic generation (SHG), and ultrafast pump-and-probe reflectivity and absorption measurements. This program featured research efforts from hydrogen defects in silicon alone to other forms of defects such as interfaces and dopant layers, as well as other important semiconducting systems. Even so, the emphasis remains on phenomena and processes far from equilibrium, such as hot electron effects and travelling localized phonon waves. This program relates directly to the mission of the Department of Energy. Knowledge of the rates and pathways of vibrational energy flow in condensed matter is critical for understanding dynamical processes in solids including electronically, optically and thermally stimulated defect and impurity reactions and migration. The ability to directly probe these pathways and rates allows tests of theory and scaling laws at new levels of precision. Hydrogen embedded in model crystalline semiconductors and metal oxides is of particular interest, since the associated

  12. Voltage-dependent sodium (NaV) channels in group IV sensory afferents

    PubMed Central

    Elmslie, Keith S

    2016-01-01

    Patients with intermittent claudication suffer from both muscle pain and an exacerbated exercise pressor reflex. Excitability of the group III and group IV afferent fibers mediating these functions is controlled in part by voltage-dependent sodium (NaV) channels. We previously found tetrodotoxin-resistant NaV1.8 channels to be the primary type in muscle afferent somata. However, action potentials in group III and IV afferent axons are blocked by TTX, supporting a minimal role of NaV1.8 channels. To address these apparent differences in NaV channel expression between axon and soma, we used immunohistochemistry to identify the NaV channels expressed in group IV axons within the gastrocnemius muscle and the dorsal root ganglia sections. Positive labeling by an antibody against the neurofilament protein peripherin was used to identify group IV neurons and axons. We show that >67% of group IV fibers express NaV1.8, NaV1.6, or NaV1.7. Interestingly, expression of NaV1.8 channels in group IV somata was significantly higher than in the fibers, whereas there were no significant differences for either NaV1.6 or NaV1.7. When combined with previous work, our results suggest that NaV1.8 channels are expressed in most group IV axons, but that, under normal conditions, NaV1.6 and/or NaV1.7 play a more important role in action potential generation to signal muscle pain and the exercise pressor reflex. PMID:27385723

  13. Group Capability Model

    NASA Technical Reports Server (NTRS)

    Olejarski, Michael; Appleton, Amy; Deltorchio, Stephen

    2009-01-01

    The Group Capability Model (GCM) is a software tool that allows an organization, from first line management to senior executive, to monitor and track the health (capability) of various groups in performing their contractual obligations. GCM calculates a Group Capability Index (GCI) by comparing actual head counts, certifications, and/or skills within a group. The model can also be used to simulate the effects of employee usage, training, and attrition on the GCI. A universal tool and common method was required due to the high risk of losing skills necessary to complete the Space Shuttle Program and meet the needs of the Constellation Program. During this transition from one space vehicle to another, the uncertainty among the critical skilled workforce is high and attrition has the potential to be unmanageable. GCM allows managers to establish requirements for their group in the form of head counts, certification requirements, or skills requirements. GCM then calculates a Group Capability Index (GCI), where a score of 1 indicates that the group is at the appropriate level; anything less than 1 indicates a potential for improvement. This shows the health of a group, both currently and over time. GCM accepts as input head count, certification needs, critical needs, competency needs, and competency critical needs. In addition, team members are categorized by years of experience, percentage of contribution, ex-members and their skills, availability, function, and in-work requirements. Outputs are several reports, including actual vs. required head count, actual vs. required certificates, CGI change over time (by month), and more. The program stores historical data for summary and historical reporting, which is done via an Excel spreadsheet that is color-coded to show health statistics at a glance. GCM has provided the Shuttle Ground Processing team with a quantifiable, repeatable approach to assessing and managing the skills in their organization. They now have a common

  14. Superlattices of group IV elements, a new possibility to produce direct band gap material

    NASA Astrophysics Data System (ADS)

    Kasper, E.

    1991-01-01

    Consideration is given to the diamond lattice type group IV semiconductors C, SiC, Si and Ge, which exhibit an indirect band gap with the conduction band minimum outside the Brillouin zone center. Ultrathin superlattices are predicted to convert the indirect band gap into a quasi-direct one under certain circumstances. Attention is also given to the growth of Si/Ge strained monolayer superlattices (SMS) by molecular beam epitaxy and experimental results obtained with these structures. The existing investigations of Si/Ge SMS have shown folded quasi-direct conditions in group IV superlattices.

  15. Theory and modeling group

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    1989-01-01

    The primary purpose of the Theory and Modeling Group meeting was to identify scientists engaged or interested in theoretical work pertinent to the Max '91 program, and to encourage theorists to pursue modeling which is directly relevant to data which can be expected to result from the program. A list of participants and their institutions is presented. Two solar flare paradigms were discussed during the meeting -- the importance of magnetic reconnection in flares and the applicability of numerical simulation results to solar flare studies.

  16. Theory and modeling group

    NASA Astrophysics Data System (ADS)

    Holman, Gordon D.

    The primary purpose of the Theory and Modeling Group meeting was to identify scientists engaged or interested in theoretical work pertinent to the Max '91 program, and to encourage theorists to pursue modeling which is directly relevant to data which can be expected to result from the program. A list of participants and their institutions is presented. Two solar flare paradigms were discussed during the meeting -- the importance of magnetic reconnection in flares and the applicability of numerical simulation results to solar flare studies.

  17. The Specification of Causal Models with Tetrad IV: A Review

    ERIC Educational Resources Information Center

    Landsheer, J. A.

    2010-01-01

    Tetrad IV is a program designed for the specification of causal models. It is specifically designed to search for causal relations, but also offers the possibility to estimate the parameters of a structural equation model. It offers a remarkable graphical user interface, which facilitates building, evaluating, and searching for causal models. The…

  18. Spectrosmicroscopic and spectroscopic investigation of U(IV) speciation in model mineral-organic matter assemblages

    NASA Astrophysics Data System (ADS)

    Booij, M. J.; Houtenbos, H.; Hoekstra, A. Y. Y.

    2014-12-01

    Both nanocrystalline uraninite (UO2) and non-crystalline U(IV) occur in anoxic sediments, controlling the fate and transport of U in contaminated aquifers. It is important to distinguish between these forms of U because non-crystalline species are more reactive towards oxidants and aqueous complexing ligands, increasing the likelihood of U re-release into groundwater in the presence of such solutes. Much work has been done to elucidate microbiological and geochemical conditions favoring non-crystalline U(IV) or UO2 formation, primarily in model systems containing a single type of U(VI)-reducing bacterium. Research suggests that microbial biomass, including cell walls and exopolymeric substances (EPS), can adsorb U(IV), likely via phosphoryl groups. Furthermore, conditions that favor EPS formation appear to promote non-crystalline U(IV) formation. Non-crystalline U(IV) formation is also favored in the presence of phosphate. However, U(IV) behavior in complicated systems containing competing U(IV) sorbents has not been studied. Investigations of U(IV) behavior in such systems are needed to understand uranium mobility in natural sediments, which contain multiple sinks for U(IV). We have developed a model system in which the native microbial consortia associated with partially decayed plant roots utilize homogenized root material to facilitate U(VI) reduction during anaerobic incubations. The model is intended to simulate an environment similar to that found in anoxic sediments where buried organic matter drives anaerobic respiration. We use this model to address the following questions: (1) Does U(IV) become associated with organic materials or minerals (or both)? (2) Does U(IV) form complexes with particular ligands, such as P? (3) Is UO2 produced when aqueous U(VI) concentrations are relatively low (~1 μM), which is typical of even contaminated sites? We have found that U(IV) does not form UO2 at low, environmentally relevant U:sorbent ratios. Furthermore

  19. Spectrosmicroscopic and spectroscopic investigation of U(IV) speciation in model mineral-organic matter assemblages

    NASA Astrophysics Data System (ADS)

    Bone, S.; Dynes, J.; Bargar, J.

    2015-12-01

    Both nanocrystalline uraninite (UO2) and non-crystalline U(IV) occur in anoxic sediments, controlling the fate and transport of U in contaminated aquifers. It is important to distinguish between these forms of U because non-crystalline species are more reactive towards oxidants and aqueous complexing ligands, increasing the likelihood of U re-release into groundwater in the presence of such solutes. Much work has been done to elucidate microbiological and geochemical conditions favoring non-crystalline U(IV) or UO2 formation, primarily in model systems containing a single type of U(VI)-reducing bacterium. Research suggests that microbial biomass, including cell walls and exopolymeric substances (EPS), can adsorb U(IV), likely via phosphoryl groups. Furthermore, conditions that favor EPS formation appear to promote non-crystalline U(IV) formation. Non-crystalline U(IV) formation is also favored in the presence of phosphate. However, U(IV) behavior in complicated systems containing competing U(IV) sorbents has not been studied. Investigations of U(IV) behavior in such systems are needed to understand uranium mobility in natural sediments, which contain multiple sinks for U(IV). We have developed a model system in which the native microbial consortia associated with partially decayed plant roots utilize homogenized root material to facilitate U(VI) reduction during anaerobic incubations. The model is intended to simulate an environment similar to that found in anoxic sediments where buried organic matter drives anaerobic respiration. We use this model to address the following questions: (1) Does U(IV) become associated with organic materials or minerals (or both)? (2) Does U(IV) form complexes with particular ligands, such as P? (3) Is UO2 produced when aqueous U(VI) concentrations are relatively low (~1 μM), which is typical of even contaminated sites? We have found that U(IV) does not form UO2 at low, environmentally relevant U:sorbent ratios. Furthermore

  20. A Spectrum of IV and V Modeling Techniques

    NASA Technical Reports Server (NTRS)

    Heimdahl, Mats; Owen, David

    2004-01-01

    The aerospace industry in general and NASA in particular is using more (semi-formal) model-based software development. Model-based development produces a collection of artifacts, for example, state diagrams, module diagrams (such as class diagrams), control-block diagrams, etc. These artifacts may than be used as a basis for auto code generation for production use. Therefore, these models must be properly evaluated in the IV and V process. IV and V practitioners know how assess standard procedural systems. But what can we du about IV and V of model-based systems? The goal of the work outlined in this proposal is to use cost effective automated techniques to the largest extent possible during the IV and V process. Our working hypotheses are: 1. There exists a range of validation techniques that can assess models built using a range of modeling techniques of increasing cost and complexity. Specifically, we hypotesize that the "cheaper" techniques can find faults cheaply and early in a project. These early results are then used to predict if this is a problem system and if a more elaborate and expensive IV and V effort is justified. 2. There exists a set of migration procedures that let us seamlessly move from simple models using cheaper techniques into more elaborate models suitable for a more expensive and detailed analysis. 3. We further hypothesize that this migration process is much cheaper than simply remodeling the system under investigation from scratch when moving to models needed for the more detailed and expensive IV and V assessments.

  1. Efficient uptake of dimethyl sulfoxide by the desoxomolybdenum(IV) dithiolate complex containing bulky hydrophobic groups.

    PubMed

    Hasenaka, Yuki; Okamura, Taka-aki; Onitsuka, Kiyotaka

    2015-04-01

    A desoxomolybdenum(IV) complex containing bulky hydrophobic groups and NH···S hydrogen bonds, (Et4N)[Mo(IV)(OSi(t)BuPh2)(1,2-S2-3,6-{(4-(t)BuC6H4)3CCONH}2C6H2)2], was synthesized. This complex promotes the oxygen-atom-transfer (OAT) reaction of DMSO by efficient uptake of the substrate into the active center. The clean OAT reaction of Me3NO is also achieved. PMID:25739371

  2. FACES IV and the Circumplex Model: Validation Study

    ERIC Educational Resources Information Center

    Olson, David

    2011-01-01

    Family Adaptability and Cohesion Evaluation Scale (FACES) IV was developed to tap the full continuum of the cohesion and flexibility dimensions from the Circumplex Model of Marital and Family Systems. Six scales were developed, with two balanced scales and four unbalanced scales designed to tap low and high cohesion (disengaged and enmeshed) and…

  3. Purinergic 2 receptor blockade prevents the responses of group IV afferents to post-contraction circulatory occlusion

    PubMed Central

    Kindig, Angela E; Hayes, Shawn G; Kaufman, Marc P

    2007-01-01

    ATP, by activating purinergic 2 (P2) receptors on group III and IV afferents, is thought to evoke the metabolic component of the exercise pressor reflex. Previously we have shown that injection of PPADS, a P2 receptor antagonist, into the arterial supply of skeletal muscle of decerebrated cats attenuated the responses of group III and IV afferents to static contraction while the muscles were freely perfused. We have now tested the hypothesis that injection of PPADS (10 mg kg−1) attenuated the responses of group III (n = 13) and group IV afferents (n = 9) to post-contraction circulatory occlusion. In the present study, we found that PPADS attenuated the group III afferent responses to static contraction during circulatory occlusion (P < 0.05). Likewise, PPADS abolished the group IV afferent responses to static contraction during occlusion (P = 0.001). During a 1 minute period of post-contraction circulatory occlusion, four of the 13 group III afferents and eight of the nine group IV afferents maintained their increased discharge. A Fischer's exact probability test revealed that more group IV afferents than group III afferents were stimulated by post-contraction circulatory occlusion (P < 0.02). In addition, the nine group IV afferents increased their mean discharge rate over baseline levels during the post-contraction circulatory occlusion period, whereas the 13 group III afferents did not (P < 0.05). PPADS abolished this post-contraction increase in discharge by the group IV afferents (P < 0.05). Our findings suggest that P2 receptors on group IV afferents play a role in evoking the metabolic component of the exercise pressor reflex. PMID:17038431

  4. Preliminary results of GODIVA-IV prompt burst modeling

    SciTech Connect

    Kimpland, R.

    1996-06-01

    The dynamic computer model developed to simulate GODIVA-IV prompt bursts adequately predicts the magnitude of power bursts. Also, it demonstrates the characteristic features of prompt bursts in metal assemblies, such as the change in shape of power pulses and the ringing of fuel surfaces at the onset of inertial effects. The model will be used to test more sophisticated reactivity feedback coefficients and neutronic-hydrodynamic coupling schemes. It will also be used for a more detailed analysis of inertial effects.

  5. Computational prediction of two-dimensional group-IV mono-chalcogenides

    SciTech Connect

    Singh, Arunima K.; Hennig, Richard G.

    2014-07-28

    Density functional calculations determine the structure, stability, and electronic properties of two-dimensional materials in the family of group-IV monochalcogenides, MX (M = Ge, Sn, Pb; X = O, S, Se, Te). Calculations with a van der Waals functional show that the two-dimensional IV-VI compounds are most stable in either a highly distorted NaCl-type structure or a single-layer litharge type tetragonal structure. Their formation energies are comparable to single-layer MoS{sub 2}, indicating the ease of mechanical exfoliation from their layered bulk structures. The phonon spectra confirm their dynamical stability. Using the hybrid HSE06 functional, we find that these materials are semiconductors with bandgaps that are generally larger than for their bulk counterparts due to quantum confinement. The band edge alignments of monolayer group IV-VI materials reveal several type-I and type-II heterostructures, suited for optoelectronics and solar energy conversion.

  6. Modeling the Arm II core in MicroCap IV

    SciTech Connect

    Dalton, A.C.

    1996-11-01

    This paper reports on how an electrical model for the core of the Arm II machine was created and how to use this model. We wanted to get a model for the electrical characteristics of the ARM II core, in order to simulate this machine and to assist in the design of a future machine. We wanted this model to be able to simulate saturation, variable loss, and reset. Using the Hodgdon model and the circuit analysis program MicroCap IV, this was accomplished. This paper is written in such a way as to allow someone not familiar with the project to understand it.

  7. Population Structure and Antimicrobial Resistance of Invasive Serotype IV Group B Streptococcus, Toronto, Ontario, Canada

    PubMed Central

    Teatero, Sarah; McGeer, Allison; Li, Aimin; Gomes, Janice; Seah, Christine; Demczuk, Walter; Martin, Irene; Wasserscheid, Jessica; Dewar, Ken; Melano, Roberto G.

    2015-01-01

    We recently showed that 37/600 (6.2%) invasive infections with group B Streptococcus (GBS) in Toronto, Ontario, Canada, were caused by serotype IV strains. We report a relatively high level of genetic diversity in 37 invasive strains of this emerging GBS serotype. Multilocus sequence typing identified 6 sequence types (STs) that belonged to 3 clonal complexes. Most isolates were ST-459 (19/37, 51%) and ST-452 (11/37, 30%), but we also identified ST-291, ST-3, ST-196, and a novel ST-682. We detected further diversity by performing whole-genome single-nucleotide polymorphism analysis and found evidence of recombination events contributing to variation in some serotype IV GBS strains. We also evaluated antimicrobial drug resistance and found that ST-459 strains were resistant to clindamycin and erythromycin, whereas strains of other STs were, for the most part, susceptible to these antimicrobial drugs. PMID:25811284

  8. 30-Group Neutron, 12-Group Photon Cross Sections from ENDF/B-IV in MATXS Format.

    Energy Science and Technology Software Center (ESTSC)

    1985-12-30

    Version: 00 The library was prepared with a fusion + fission + l/E + thermal Maxwellian weight function and has proved useful for many high energy calculations, including criticals such as GODIVA. It works reasonably well for many shielding problems where resonance selfshielding is not too important. The energy group structures for MATXSl are listed in Table 1, the materials with neutron scattering data in Table 2, those with photon production data in Table 3,more » and those with photon scattering data in Table 4.« less

  9. Genogroup IV and VI Canine Noroviruses Interact with Histo-Blood Group Antigens

    PubMed Central

    Breiman, Adrien; le Pendu, Jacques

    2014-01-01

    ABSTRACT Human noroviruses (HuNV) are a significant cause of viral gastroenteritis in humans worldwide. HuNV attaches to cell surface carbohydrate structures known as histo-blood group antigens (HBGAs) prior to internalization, and HBGA polymorphism among human populations is closely linked to susceptibility to HuNV. Noroviruses are divided into 6 genogroups, with human strains grouped into genogroups I (GI), II, and IV. Canine norovirus (CNV) is a recently discovered pathogen in dogs, with strains classified into genogroups IV and VI. Whereas it is known that GI to GIII noroviruses bind to HBGAs and GV noroviruses recognize terminal sialic acid residues, the attachment factors for GIV and GVI noroviruses have not been reported. This study sought to determine the carbohydrate binding specificity of CNV and to compare it to the binding specificities of noroviruses from other genogroups. A panel of synthetic oligosaccharides were used to assess the binding specificity of CNV virus-like particles (VLPs) and identified α1,2-fucose as a key attachment factor. CNV VLP binding to canine saliva and tissue samples using enzyme-linked immunosorbent assays (ELISAs) and immunohistochemistry confirmed that α1,2-fucose-containing H and A antigens of the HBGA family were recognized by CNV. Phenotyping studies demonstrated expression of these antigens in a population of dogs. The virus-ligand interaction was further characterized using blockade studies, cell lines expressing HBGAs, and enzymatic removal of candidate carbohydrates from tissue sections. Recognition of HBGAs by CNV provides new insights into the evolution of noroviruses and raises concerns regarding the potential for zoonotic transmission of CNV to humans. IMPORTANCE Infections with human norovirus cause acute gastroenteritis in millions of people each year worldwide. Noroviruses can also affect nonhuman species and are divided into 6 different groups based on their capsid sequences. Human noroviruses in genogroups

  10. Direct band gaps in group IV-VI monolayer materials: Binary counterparts of phosphorene

    NASA Astrophysics Data System (ADS)

    Kamal, C.; Chakrabarti, Aparna; Ezawa, Motohiko

    2016-03-01

    We perform systematic investigation on the geometric, energetic, and electronic properties of group IV-VI binary monolayers (XY ), which are the counterparts of phosphorene, by employing density functional theory based electronic structure calculations. For this purpose, we choose the binary systems X Y consisting of equal numbers of group IV (X = C, Si, Ge, Sn) and group VI elements (Y = O, S, Se, Te) in three geometrical configurations, the puckered, buckled and planar structures. The results of binding energy calculations show that all the binary systems studied are energetically stable. It is observed that, the puckered structure, similar to that of phosphorene, is the energetically most stable geometric configuration. Moreover, the binding energies of buckled configuration are very close to those of the puckered configuration. Our results of electronic band structure predict that puckered SiO and CSe are direct band semiconductors with gaps of 1.449 and 0.905 eV, respectively. Band structure of CSe closely resembles that of phosphorene. Remaining group IV-VI binary monolayers in the puckered configuration and all the buckled monolayers are also semiconductors, but with indirect band gaps. Importantly, we find that the difference between indirect and direct band gaps is very small for many puckered monolayers. Thus there is a possibility of making these systems undergo transition from indirect to direct band gap semiconducting state by a suitable external influence. Indeed, we show in the present work that seven binary monolayers, namely, SnS, SiSe, GeSe, SnSe, SiTe, GeTe, and SnTe become direct band gap semiconductors when they are subjected to a small mechanical strain (≤3 % ). This makes nine out of sixteen binary monolayers studied in the present work direct band gap semiconductors. Thus there is a possibility of utilizing these binary counterparts of phosphorene in future light-emitting diodes and solar cells.

  11. Synthesis of Group IV Nanowires on Graphene: The Case of Ge Nanocrawlers.

    PubMed

    Mataev, Elnatan; Rastogi, Sahil Kumar; Madhusudan, Atul; Bone, Jennifer; Lamprinakos, Nicholas; Picard, Yoosuf; Cohen-Karni, Tzahi

    2016-08-10

    In recent years, there has been a growing interest in using graphene as a synthesis platform for polymers, zero-dimensional (0D) materials, one-dimensional materials (1D), and two-dimensional (2D) materials. Here, we report the investigation of the growth of germanium nanowires (GeNWs) and germanium nanocrawlers (GeNCs) on single-layer graphene surfaces. GeNWs and GeNCs are synthesized on graphene films by gold nanoparticles catalyzed vapor-liquid-solid growth mechanism. The addition of hydrogen chloride gas (HCl) at the nucleation step increased the propensity toward GeNCs growth on the surface. As the time lag before HCl introduction during the nucleation step increased, a significant change in the number of out-of-plane GeNWs versus in-plane GeNCs was observed. The nucleation temperature and time played a key role in the formation of GeNCs as well. The fraction of GeNCs (χNCs) decreased from 0.95 ± 0.01 to 0.66 ± 0.07 when the temperature was kept at 305 °C for 15 s versus maintained at 305 °C throughout the process, respectively. GeNCs exhibit ⟨112⟩ as the preferred growth direction whereas GeNWs exhibit both ⟨112⟩ and ⟨111⟩ as the preferred growth directions. Finally, our growth model suggests a possible mechanism for the preference of an in-plane GeNC growth on graphene versus GeNW on SiO2. These findings open up unique opportunities for fundamental studies of crystal growth on graphene, as well as enable exploration of new electronic interfaces between group IV materials and graphene, potentially toward designing new geometries for hybrid materials sensors. PMID:27400248

  12. Generic process for preparing a crystalline oxide upon a group IV semiconductor substrate

    DOEpatents

    McKee, Rodney A.; Walker, Frederick J.; Chisholm, Matthew F.

    2000-01-01

    A process for growing a crystalline oxide epitaxially upon the surface of a Group IV semiconductor, as well as a structure constructed by the process, is described. The semiconductor can be germanium or silicon, and the crystalline oxide can generally be represented by the formula (AO).sub.n (A'BO.sub.3).sub.m in which "n" and "m" are non-negative integer repeats of planes of the alkaline earth oxides or the alkaline earth-containing perovskite oxides. With atomic level control of interfacial thermodynamics in a multicomponent semiconductor/oxide system, a highly perfect interface between a semiconductor and a crystalline oxide can be obtained.

  13. Catalytic Ester–Amide Exchange Using Group (IV) Metal Alkoxide–Activator Complexes

    PubMed Central

    Han, Chong; Lee, Jonathan P.; Lobkovsky, Emil; Porco, John A.

    2005-01-01

    A process for preparation of amides from unactivated esters and amines has been developed using a catalytic system comprised of group (IV) metal alkoxides in conjunction with additives including 1-hydroxy-7-azabenzotriazole (HOAt). In general, ester–amide exchange proceeds using a variety of structurally diverse esters and amines without azeotropic reflux to remove the alcohol byproduct. Initial mechanistic studies on the Zr(Ot-Bu)4–HOAt system revealed that the active catalyst is a novel, dimeric zirconium complex as determined by X-ray crystallography. PMID:16011366

  14. LLNL Chemical Kinetics Modeling Group

    SciTech Connect

    Pitz, W J; Westbrook, C K; Mehl, M; Herbinet, O; Curran, H J; Silke, E J

    2008-09-24

    The LLNL chemical kinetics modeling group has been responsible for much progress in the development of chemical kinetic models for practical fuels. The group began its work in the early 1970s, developing chemical kinetic models for methane, ethane, ethanol and halogenated inhibitors. Most recently, it has been developing chemical kinetic models for large n-alkanes, cycloalkanes, hexenes, and large methyl esters. These component models are needed to represent gasoline, diesel, jet, and oil-sand-derived fuels.

  15. A Randomized Parallel-Group Dietary Study for Stage II–IV Ovarian Cancer Survivors

    PubMed Central

    Paxton, Raheem J.; Garcia-Prieto, Celia; Berglund, Maria; Hernandez, Mike; Hejek, Richard A.; Handy, Beverly; Brown, Jubilee; Jones, Lovell A.

    2011-01-01

    Background Few studies have examined the dietary habits of ovarian cancer survivors. Therefore, we conducted a study to assess the feasibility and impact of two dietary interventions for ovarian cancer survivors. Methods In this randomized, parallel-group study, 51 women (mean age, 53 years) diagnosed with stage II–IV ovarian cancer were recruited and randomly assigned to a low fat, high fiber (LFHF) diet or a modified National Cancer Institute diet supplemented with a soy-based beverage and encapsulated fruit and vegetable juice concentrates (FVJCs). Changes in clinical measures, serum carotenoid and tocopherol levels, dietary intake, anthropometry, and health-related quality of life (HRQOL) were assessed with paired t-tests. Results The recruitment rate was 25%, and the retention rate was 75% at 6 months. At baseline, 28% and 45% of women met guidelines for intake of fiber and of fruits and vegetables, respectively. After 6 months, total serum carotenoid levels and α- and β-carotene concentrations were significantly increased in both groups (P < 0.01); however, β-carotene concentrations were increased more in the FVJC group. Serum β-cryptoxanthin levels, fiber intake (+5.2 g/day), and daily servings of juice (+0.9 servings/day) and vegetables (+1.3 servings/day) were all significantly increased in the LFHF group (all P < 0.05). Serum levels of albumin, lutein and zeaxanthin, retinol, and retinyl palmitate were significantly increased in the FVJC group (all P < 0.05). No changes in cancer antigen-125, anthropometry, or HRQOL were observed. Conclusion Overall, this study supports the feasibility of designing dietary interventions for stage II–IV ovarian cancer survivors and provides preliminary evidence that a low fat high fiber diet and a diet supplemented with encapsulated FVJC may increase phytonutrients in ovarian cancer survivors. PMID:22119991

  16. Growth of group IV mycobacteria on medium containing various saturated and unsaturated fatty acids.

    PubMed Central

    Saito, H; Tomioka, H; Yoneyama, T

    1984-01-01

    Seventy-one strains of 15 species of rapidly growing mycobacteria were studied for their susceptibilities to fatty acids with 2 to 20 carbons by the agar dilution method at pH 7.0. Most mycobacteria other than potential pathogens (Mycobacterium fortuitum and Mycobacterium chelonei) were resistant to saturated fatty acids, except for lauric acid (C12:0) (MIC, 6.25 to 25 micrograms/ml) and capric acid (C10:0) (MIC, 50 to 100 micrograms#ml). M. fortuitum and M. chelonei were substantially insusceptible to these fatty acids. Unsaturated fatty acids with 16 to 20 carbons, except for C20:5, were highly toxic to group IV mycobacteria other than M. fortuitum, M. chelonei, Mycobacterium smegmatis, and Mycobacterium phlei, these being highly resistant to all the unsaturated acids, except for C16:1, C18:3, and C20:5. Introduction of double bonds to C16 to C20 fatty acids caused a marked increase in their activities that depended on the increase in the number of double bonds, at least up to three or four. M. fortuitum and M. chelonei were more resistant to the unsaturated fatty acids (particularly to C20:3 and C20:4) than the other group IV mycobacteria. PMID:6486760

  17. Structural phase stability in group IV metals under static high pressure

    SciTech Connect

    Velisavljevic, Nenad; Chesnut, Garry N; Dattelbaum, Dana M; Vohra, Yogesh K; Stemshorn, Andrew

    2009-01-01

    In group IV metals (Ti, Zr, and Hf) room temperature compression leads to a martensitic transformation from a ductile {alpha} to a brittle {omega} phase. {alpha} {yields} {omega} phase boundary decreases to lower pressure at high temperature and can limit the use of group IV metals in industrial applications. There is a large discrepancy in the transition pressure reported in literature, with some of the variation attributed to experimental conditions (i.e. hydrostatic vs. non-hydrostatic). Shear deformation in non-hydrostatic experiments drives {alpha} {yields} {omega} transition and decreases transition pressure. Impurities can also aid or suppress {alpha} {yields} {omega} transition. By performing x-ray diffraction experiments on samples in a diamond anvil cell we show that interstitial impurities, such as C, N, and O can obstruct {alpha} {yields} {omega} transition and stabilize {alpha} phase to higher pressure. We also show that reduction in grain size can also influence {alpha} {yields} {omega} phase boundary and help stabilize {alpha} phase to higher pressure under non-hydrostatic conditions.

  18. Spectral synthesis in the ultraviolet. IV - A library of mean stellar groups

    NASA Technical Reports Server (NTRS)

    Fanelli, Michael N.; O'Connell, Robert W.; Burstein, David; Wu, Chi-Chao

    1992-01-01

    A library of mean UV stellar energy distributions is derived from IUE spectrophotometry of 218 stars. The spectra cover 1230-3200 A with a spectral resolution of about 6 A. They have been corrected for interstellar extinction and converted to a common flux and wavelength scale. Individual stars were combined into standard groups according to their continuum colors, observed UV spectral morphology, MK luminosity class, and metal abundance. The library consists of 56 groups: 21 dwarf(V), 8 subgiant(IV), 16 giant(III), and supergiant(I + II) groups, covering O3-M4 spectral types. A metal-poor sequence is included, containing four dwarf and two giant groups, as is a metal-enhanced sequence with a single dwarf, subgiant, and giant group. Spectral indices characterizing the continuum and several strong absorption features are examined as temperature, luminosity, and abundance diagnostics. The library is intended to serve as a basis for interpreting the composite UV spectra of a wide variety of stellar systems, e.g., elliptical galaxies, starburst systems, and high-redshift galaxies.

  19. Group-IV Impurity Defect Levels in beta-Gallium Oxide

    NASA Astrophysics Data System (ADS)

    Badescu, Stefan

    2015-03-01

    Beta-Gallium Oxide (β-Ga2O3) is a wide-bandgap semiconductor with a significant potential as a native substrate for electronic devices. One avenue for tuning its carrier concentration and electronic properties is doping with group-IV impurity atoms. This work presents a first-principles understanding of the effects of C, Si, Ge and Sn dopants at Ga sites. C is found to act like a bistable center whereas the other dopants preserve the symmetry of the Ga site. Hybrid functionals are used to describe accurately the effects that occur mainly in the conduction band. A Brillouin zone unfolding is used that enables a direct comparison to possible spectroscopy experiments. We delineate the effects on bandgap modulation induced by charge density on the one hand, and by conduction band resonances and effective masses on the other hand.

  20. Growth and applications of GeSn-related group-IV semiconductor materials

    NASA Astrophysics Data System (ADS)

    Zaima, Shigeaki; Nakatsuka, Osamu; Taoka, Noriyuki; Kurosawa, Masashi; Takeuchi, Wakana; Sakashita, Mitsuo

    2015-08-01

    We review the technology of Ge1-xSnx-related group-IV semiconductor materials for developing Si-based nanoelectronics. Ge1-xSnx-related materials provide novel engineering of the crystal growth, strain structure, and energy band alignment for realising various applications not only in electronics, but also in optoelectronics. We introduce our recent achievements in the crystal growth of Ge1-xSnx-related material thin films and the studies of the electronic properties of thin films, metals/Ge1-xSnx, and insulators/Ge1-xSnx interfaces. We also review recent studies related to the crystal growth, energy band engineering, and device applications of Ge1-xSnx-related materials, as well as the reported performances of electronic devices using Ge1-xSnx related materials.

  1. The development of two dimensional group IV chalcogenides, blocks for van der Waals heterostructures.

    PubMed

    Sa, Baisheng; Sun, Zhimei; Wu, Bo

    2016-01-14

    In this work, we introduce a series of two dimensional (2D) group IV chalcogenides (AX)2 with the building block X-A-A-X (A = Si, Ge, Sn, and Pb, and X = Se and Te) on the basis of ab initio calculations. The analysis of energy evaluation, lattice vibration as well as the chemical bonding demonstrate the good stability of these 2D materials. Furthermore, the pictures for the chemical bonding and electronic features of the 2D (AX)2 are drawn. Their narrow gapped semiconducting nature is unraveled. Especially, strong interactions between the electrons and phonons as well as the topological insulating nature in (SiTe)2 are observed. The present results indicate that such remarkable artificial 2D (AX)2 are building blocks for van der Waals heterostructure engineering, which shows potential applications in nanoscaled electronics and optoelectronics. PMID:26667941

  2. Vacancies and oxidation of two-dimensional group-IV monochalcogenides

    NASA Astrophysics Data System (ADS)

    Gomes, Lídia C.; Carvalho, A.; Castro Neto, A. H.

    2016-08-01

    Point defects in the binary group-IV monochalcogenide monolayers of SnS, SnSe, GeS, and GeSe are investigated using density functional theory calculations. Several stable configurations are found for oxygen defects, however, we give evidence that these materials are less prone to oxidation than phosphorene, with which monochalcogenides are isoelectronic and share the same orthorhombic structure. Concurrent oxygen defects are expected to be vacancies and substitutional oxygen. We show that it is energetically favorable for oxygen to be incorporated into the layers substituting for a chalcogen (OS /Se defects), and different from most of the other defects investigated, this defect preserves the electronic structure of the material. Thus, we suggest that annealing treatments can be useful for the treatment of functional materials where loss mechanisms due to the presence of defects are undesirable.

  3. Two-dimensional group-IV monochalcogenides: structural, electronic and optical properties

    NASA Astrophysics Data System (ADS)

    Gomes, Lidia; Carvalho, Alexandra; Castro Neto, A. H.

    Two-dimensional materials have attracted a massive attention of the scientific and industrial communities due to their unusual and interesting properties. The layered group-IV monochalcogenides-SnS, SnSe, GeS and GeSe- has gained attention as a promising group with potentially useful applications in diverse fields. The bulk SnS, a naturally occurring mineral, has been considered as an alternative to be used in film PV cells, due to its electronic and optical properties. We use first principles calculations to explore structural, electronic and optical properties of this group, with focus in their two-dimensional forms. We show that all those binary compounds are semiconducting, with bandgap energies covering most of the visible range. They have multiple valleys in the valence and conduction bands, with spin-orbit splitting of the order of 19-86 meV. An enhanced static dielectric permittivity is found for the monolayers. Structural analysis shows that the 2D form of these materials presents very high piezoelectric constants, exceeding values recently observed for other 2D-systems. The existence of a negative Poisson ratio is predicted for the GeS compound. We acknowledge the NRF-CRP award ``Novel 2D materials with tailored properties: beyond graphene'' (R-144-000-295-281).

  4. Modeling Interactions in Small Groups

    ERIC Educational Resources Information Center

    Heise, David R.

    2013-01-01

    A new theory of interaction within small groups posits that group members initiate actions when tension mounts between the affective meanings of their situational identities and impressions produced by recent events. Actors choose partners and behaviors so as to reduce the tensions. A computer model based on this theory, incorporating reciprocal…

  5. Y-shape spin-separator for two-dimensional group-IV nanoribbons based on quantum spin hall effect

    SciTech Connect

    Gupta, Gaurav Abdul Jalil, Mansoor Bin; Liang, Gengchiau; Lin, Hsin; Bansil, Arun; Huang, Cheng-Yi; Tsai, Wei-Feng

    2014-01-20

    An efficient spin-separator that operates in quantum spin hall phase has been investigated for two-dimensional group-IV materials. A three-terminal Y-shaped device has been simulated via non-equilibrium Green Function to demonstrate the separation of unpolarized current at source terminal into spin-polarized current of opposite polarity at the two drain terminals. Device controls, i.e., tunable buckling and perpendicular magnetic field have been modeled comprehensively to evaluate the device feasibility and performance. It is shown that these controls can preferentially steer current between the two drains to create a differential charge current with complementary spin polarization, thus enabling a convenient regulation of output signal.

  6. Validation of Nuclear Criticality Safety Software and 27 energy group ENDF/B-IV cross sections

    SciTech Connect

    Lee, B.L. Jr.

    1994-08-01

    The validation documented in this report is based on calculations that were executed during June through August 1992, and was completed in June 1993. The statistical analyses in Appendix C and Appendix D were completed in October 1993. This validation gives Portsmouth NCS personnel a basis for performing computerized KENO V.a calculations using the Martin Marietta Nuclear Criticality Safety Software. The first portion of the document outlines basic information in regard to validation of NCSS using ENDF/B-IV 27-group cross sections on the IBM 3090 at ORNL. A basic discussion of the NCSS system is provided, some discussion on the validation database and validation in general. Then follows a detailed description of the statistical analysis which was applied. The results of this validation indicate that the NCSS software may be used with confidence for criticality calculations at the Portsmouth Gaseous Diffusion Plant. When the validation results are treated as a single group, there is 95% confidence that 99.9% of future calculations of similar critical systems will have a calculated K{sub eff} > 0.9616. Based on this result the Portsmouth Nuclear Criticality Safety Department has adopted the calculational acceptance criteria that a k{sub eff} + 2{sigma} {le} 0.95 is safety subcritical. The validation of NCSS on the IBM 3090 at ORNL was extended to include NCSS on the IBM 3090 at K-25.

  7. First-principles studies on substitutional doping by group IV and VI atoms in the two-dimensional arsenene

    NASA Astrophysics Data System (ADS)

    Du, Juan; Xia, Congxin; Wang, Tianxing; Zhao, Xu; Tan, Xiaoming; Wei, Shuyi

    2016-08-01

    The electronic characteristics of group IV and VI atoms-doped arsenene are investigated by means of first-principles methods. The results show that the influences of group IV and VI impurities are obvious on electronic structures in the arsenene. The spin-up and spin-down states induced by C, Si, Ge and O substituting As atoms lie on the both sides of Fermi level in the arsenene, and induce deeper impurity states with total magnetic moment 1 μB. However, Te substituting As atom is the most possible n-type doping due to the shallowest transition level. These results are useful to further investigate experimentally the electronic structures and magnetic properties of group IV and VI atoms-doped arsenene nanosheets.

  8. Ion implantation induced defect formation and amorphization in the Group IV semiconductors: Diamond, silicon and germanium

    NASA Astrophysics Data System (ADS)

    Hickey, Diane P.

    Silicon, which has been the workhorse of the semiconductor industry for the past several decades, is now being enhanced with other Group IV elements, such as carbon (silicon carbide) and germanium (silicon-germanium strained channels in transistors), to accentuate properties of silicon for various nanoelectronic devices. However, there is little understanding of the relationship between ion implantation and defect evolution in two of the three corners of the Group IV phase diagram. In particular, the rod-like {311} defect is theorized to be unique to the diamond crystal structure elements. Due to its ability to affect dopant diffusion, the {311} defect is well studied in silicon. However, few studies of germanium and none of diamond have analyzed extended defect formation and evolution using transmission electron spectroscopy. Using ion implantation to induce amorphization is a technological process step in Si devices and potentially for diamond nano-electronics. Defects associated with crystal regrowth in Ge and diamond are not well known. My research studies the formation conditions of extended defects and amorphization in carbon and germanium after ion implantation. Ion implantation damage in diamond-cubic single-crystal silicon, germanium and diamond was produced by Si+ implantation at 1 MeV to a dose of 1 x 1014 cm-2 and 1 x 10 15 cm-2. Damage in Si and Ge was produced by Si + implantation at 40 keV to a dose of 1 x 1014 cm-2 and 1 x 1015 cm-2, and amorphizing damage in diamond was produced by Si+ implantation at 1 MeV to a dose of 3 and 7 x 1015 cm-2. All implants were carried out at room temperature. For non-amorphizing implants (1014 Si+ cm-2) into Ge, dot-like defects formed immediately upon implantation and were stable up to temperatures of 650°C. The activation energy of these defects was determined to be approximately 0.2 +/- 0.1 eV. For amorphizing implants (1015 Si+ cm-2) into Ge and upon solid-phase epitaxial regrowth, the same types of defects seen

  9. Chromospheric models for Altair (A7 IV-V)

    NASA Technical Reports Server (NTRS)

    Ferrero, R. Freire; Gouttebroze, P.; Catalano, S.; Marilli, E.; Bruhweiler, F.; Kondo, Y.; Van Der Hucht, K.; Talavera, A.

    1995-01-01

    The star, Altair (A7 IV-V), is clearly shown to have Lyman-alpha emission of chromospheric origin, while no evidence is found for the Mg II emission reported in previous investigations. We present non-Local Thermodymanic Equilibrium (non-LTE) semiempirical models incorporating partial redistribution of the chromosphere of Altair that reproduce the observed Lyman-alpha emission and the Mg II resonance absorption at 2800 A. We unambiguously establihed that chromospheres exist at spectral types as early as A7 on the main sequence, and we also demonstrate that it very unlikely that the observed emission originates in a corotating expanding wind. This result represents a new challenge for chromospheric heating theories. It may indicate that both differential rotation and convection layers, at least near the equator, exist in this fast rotating (v sin i = 220 km/s) star.

  10. Growth and characterization of group IV-based alloys on silicon

    NASA Astrophysics Data System (ADS)

    Chandrasekhar, Durvasulu

    Group IV based alloys have recently received much attention because of the possibility of tailoring the band gap with respect to that of silicon. Significant results have already been achieved with the Sisb1-xGesbx/Si system. But a major drawback is the large lattice mismatch and thermal instability. Hence, alternate material systems, such as Si-Ge-C alloys, are under active investigation. The research presented here focuses on the growth and characterization of Sisb1-x-yGesbxCsby and Sisb1-yCsby films. Group IV alloys were grown on silicon substrates by atmospheric-pressure chemical vapor deposition (APCVD), molecular beam epitaxy (MBE), and ultrahigh-vacuum chemical vapor deposition (UHV-CVD) employing novel precursor molecules. The films were characterized extensively using Rutherford backscattering spectrometry, secondary ion mass spectrometry, transmission electron microscopy, and Fourier transform infrared spectroscopy. Sisb1-x-yGesbxCsby films grown by APCVD between 600 to 700sp°C had compositions in the range: 0.2 < x < 0.5 and 0 < y < 0.12. Layers with less than 3 at. % C were of device quality and defect-free. Increase in carbon led to the formation of a bilayer structure, initial crystalline growth followed by amorphous growth: this behavior was attributed to carbon floating on the surface. Periodic interruptions of the Sisb1-x-yGesbxCsby growth by deposition of a thin Si layer prevented amorphous growth. Sisb1-x-yGesbxCsby/Si heterostructures (0.1 < x < 0.4; 0 < y < 0.045) were deposited by MBE at 450 to 550sp°C, using two different sources for carbon: graphite and silicon carbide (SiC). Introduction of carbon using graphite resulted in non-homogeneous incorporation and rough film growth morphology. Use of Sb surfactant led to abrupt interfaces with more homogeneous incorporation of the elements. Using SiC as the carbon source, led to stabilization of the surface morphology without the need for Sb surfactant. Sisb1-yCsby films (0.04 < y < 0.2) were

  11. Synthesis and characterization of group IV semiconductor nanowires by vapor-liquid-solid growth

    NASA Astrophysics Data System (ADS)

    Lew, Kok-Keong

    There is currently intense interest in one-dimensional nanostructures, such as nanotubes and nanowires, due to their potential to test fundamental concepts of dimensionality and to serve as building blocks for nanoscale devices. Vapor-liquid-solid (VLS) growth, which is one of the most common fabrication methods, has been used to produce single crystal semiconductor nanowires such as silicon (Si), germanium (Ge), and gallium arsenide (GaAs). In the VLS growth of Group IV semiconductor nanowires, a metal, such as gold (Au) is used as a catalyst agent to nucleate whisker growth from a Si-containing (silane (SIH4)) or Ge-containing vapor (germane (GeH 4)). Au and Si/Ge form a liquid alloy that has a eutectic temperature of around 360°C, which, upon supersaturation, nucleates the growth of a Si or Ge wire. The goal of this work is to develop a more fundamental understanding of VLS growth kinetics and intentional doping of Group IV semiconductor nanowires in order to better control the properties of the nanowires. The fabrication of p-type and n-type Si nanowires will be studied via the addition of dopant gases such as diborane (B2H 6), trimethylboron (TMB), and phosphine (PH3) during growth. The use of gaseous dopant sources provides more flexibility in growth, particularly for the fabrication of p-n junctions and structures with axial dopant variations (e.g. p+-p- p+). The study is then extended to fabricate SiGe alloy nanowires by mixing SiH4 and GeH4. Bandgap engineering in Si/SiGe heterostructures can lead to novel devices with improved performance compared to those made entirely of Si. The scientific findings will lead to a better understanding of the fabrication of Si/SiGe axial and radial heterostructure nanowires for functional nanowire device structures, such as heterojunction bipolar transistors (HBTs) and high electron mobility transistors (HEMTs). Eventually, the central theme of this research is to provide a scientific knowledge base and foundation for

  12. Graphene challengers: silicene, germanene and stanene, group IV elemental synthetic electronic materials

    NASA Astrophysics Data System (ADS)

    Le Lay, Guy

    Silicene, germanene and stanene, graphene's group IV elemental cousins, have attracted considerable interest since the birth of silicene in 2012. These novel synthetic two-dimensional (2D) Si, Ge and Sn allotropes are artificially created in situ under ultra high vacuum, since, at variance with graphene, which descents from graphite, they have no parent crystal in nature. They are considered as promising candidates for ultimate scaling of nanoelectronic devices. Indeed, the recent fabrication of the first silicene field effect transistors with ambipolar characteristics operating at room temperature demonstrates their potential as emerging 2D electronic materials. In this invited talk, I will present the archetype 3x3 silicene phase formed on a silver (111) substrate, its sister phases and the growth of multilayer silicene, which hosts Dirac fermions and which is stable in ambient air, protected by its ultra-thin native oxide. The recent synthesis of single layer germanene and stanene, near room temperature 2D topological insulators will be also presented, while multilayer germanene will be further addressed. Challenging graphene, silicene, germanene and stanene, which are directly compatible with the current semiconductor industry, could lead to the development of a new class of low energy consumption nanoelectronic devices.

  13. Photoelectron Spectroscopy and Electronic Structure of Heavy GroupIV-VI Diatomics

    SciTech Connect

    Wang, L.-S.; Niu, B.; Lee, Yuan T.; Shirley, D.A.; Balasubramanian, K.

    1989-09-01

    Vibrationally-resolved HeI (584{angstrom}) photoelectron spectra of the heavy group IV-VI diatomics SnSe, SnTe, PbSe, and PbTe were obtained with a new high temperature molecular beam source. Ionization potentials and spectroscopic constants are reported for all the ionic states observed. Relativistic complete active space MCSCF followed by multireference singles + doubles relativistic CI calculations which included up to 200,000 configurations were made on both the neutral diatomics and their positive ions. Ionization potentials and spectroscopic constants were calculated and were in good agreement with the experimentally-measured values. Relativistic CI potential energy curves were calculated for all the neutral ground states and the ionic states involved. Relativistic effects were shown to play an important role in these heavy diatomics. The {sup 2}{Sigma}{sub 1/2}{sup +} and {sup 2}{Pi}{sub 1/2} states for all four molecular ions showed avoided curve crossings, which resulted in pronounced shoulders in the {Omega} = 1/2 potential energy curves of PbTe{sup +}. Experimentally, autoionization transitions were also observed for the PbTe{sup +} spectrum. The importance of the relativistic effect and chemical bonding in the heavy diatomics are discussed.

  14. Structure and magnetism in novel group IV element-based magnetic materials

    SciTech Connect

    Tsui, Frank

    2013-08-14

    The project is to investigate structure, magnetism and spin dependent states of novel group IV element-based magnetic thin films and heterostructures as a function of composition and epitaxial constraints. The materials systems of interest are Si-compatible epitaxial films and heterostructures of Si/Ge-based magnetic ternary alloys grown by non-equilibrium molecular beam epitaxy (MBE) techniques, specifically doped magnetic semiconductors (DMS) and half-metallic Heusler alloys. Systematic structural, chemical, magnetic, and electrical measurements are carried out, using x-ray microbeam techniques, magnetotunneling spectroscopy and microscopy, and magnetotransport. The work is aimed at elucidating the nature and interplay between structure, chemical order, magnetism, and spin-dependent states in these novel materials, at developing materials and techniques to realize and control fully spin polarized states, and at exploring fundamental processes that stabilize the epitaxial magnetic nanostructures and control the electronic and magnetic states in these complex materials. Combinatorial approach provides the means for the systematic studies, and the complex nature of the work necessitates this approach.

  15. High pressure study of group-IV clathrate by XRD and Raman scattering

    NASA Astrophysics Data System (ADS)

    Kume, Tetsuji; Sasaki, Shigeo

    2013-06-01

    Group-IV clathrates, which are open-structured Si, Ge, and Sn cage-like compounds, have attracted increasing attention because of their potential applications for thermoelectric devices due to the behavior of phonon-glass and electron-crystal. One of the keys for the intriguing properties is so called rattling vibrations of guests. The direct observation of the rattling is important for understanding of the clathrate properties. Furthermore, the systematic observations of the rattling vibrations as a function of the cage size controlled by pressure are very significant to investigate the guest-host interaction. The pressurization also throws light on the structural stability of the clathrate, which is improved by the guest atoms. The clathrate structure with sp3 network is preserved up to very high pressure. Instead of the structural change, the doped Si clathrates undergo an isostructural phase transition. This paper is concerned with the structural stabilities under high pressure and the rattling vibrations of the guest as a function of the cage size, investigated for various semiconductor clathrates (Sr8Ga16Ge30, Eu8Ga16Ge30 and so on) by means of Raman and XRD experiments. On the basis of the recent data, the guest-host interaction is discussed.

  16. Visualization and Modeling Working Group

    SciTech Connect

    Fernandez, S.J.; Dodrill, K.A.

    2007-03-01

    During the 2005 Hurricane season, many consequence predictions were available from 36 to 96 hours before landfalls, via the Department of Energy’s Visualization and Modeling Working Group (VMWG). Real-time data can be tapped by local officials and utilities, and can also be accessed for post-event regulatory audits. An overview of VMWG’s models, results and uses will be presented.

  17. Bifactor Modeling and the Estimation of Model-Based Reliability in the WAIS-IV

    ERIC Educational Resources Information Center

    Gignac, Gilles E.; Watkins, Marley W.

    2013-01-01

    Previous confirmatory factor analytic research that has examined the factor structure of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) has endorsed either higher order models or oblique factor models that tend to amalgamate both general factor and index factor sources of systematic variance. An alternative model that has not yet…

  18. 33 CFR 155.1050 - Response plan development and evaluation criteria for vessels carrying groups I through IV...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Response plan development and evaluation criteria for vessels carrying groups I through IV petroleum oil as a primary cargo. 155.1050 Section 155.1050 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL OR HAZARDOUS...

  19. 33 CFR 155.1050 - Response plan development and evaluation criteria for vessels carrying groups I through IV...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Response plan development and evaluation criteria for vessels carrying groups I through IV petroleum oil as a primary cargo. 155.1050 Section 155.1050 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL OR HAZARDOUS...

  20. Simulated Group Counseling: An Experiential Training Model for Group Work.

    ERIC Educational Resources Information Center

    Romano, John L.

    1998-01-01

    Describes an experiential group training model designed for prepracticum-level counseling graduate students. Simulated Group Counseling (SCG) offers students an opportunity to experience being group members; facilitating a group; and processing the group with peers, an advanced graduate student observer, and the instructor. SGC reduces…

  1. Hybrid Group IV Nanophotonic Structures Incorporating Diamond Silicon-Vacancy Color Centers.

    PubMed

    Zhang, Jingyuan Linda; Ishiwata, Hitoshi; Babinec, Thomas M; Radulaski, Marina; Müller, Kai; Lagoudakis, Konstantinos G; Dory, Constantin; Dahl, Jeremy; Edgington, Robert; Soulière, Veronique; Ferro, Gabriel; Fokin, Andrey A; Schreiner, Peter R; Shen, Zhi-Xun; Melosh, Nicholas A; Vučković, Jelena

    2016-01-13

    We demonstrate a new approach for engineering group IV semiconductor-based quantum photonic structures containing negatively charged silicon-vacancy (SiV(-)) color centers in diamond as quantum emitters. Hybrid diamond-SiC structures are realized by combining the growth of nano- and microdiamonds on silicon carbide (3C or 4H polytype) substrates, with the subsequent use of these diamond crystals as a hard mask for pattern transfer. SiV(-) color centers are incorporated in diamond during its synthesis from molecular diamond seeds (diamondoids), with no need for ion-implantation or annealing. We show that the same growth technique can be used to grow a diamond layer controllably doped with SiV(-) on top of a high purity bulk diamond, in which we subsequently fabricate nanopillar arrays containing high quality SiV(-) centers. Scanning confocal photoluminescence measurements reveal optically active SiV(-) lines both at room temperature and low temperature (5 K) from all fabricated structures, and, in particular, very narrow line widths and small inhomogeneous broadening of SiV(-) lines from all-diamond nanopillar arrays, which is a critical requirement for quantum computation. At low temperatures (5 K) we observe in these structures the signature typical of SiV(-) centers in bulk diamond, consistent with a double lambda. These results indicate that high quality color centers can be incorporated into nanophotonic structures synthetically with properties equivalent to those in bulk diamond, thereby opening opportunities for applications in classical and quantum information processing. PMID:26695059

  2. New Group in the Leptospirillum Clade: Cultivation-Independent Community Genomics, Proteomics, and Transcriptomics of the New Species “Leptospirillum Group IV UBA BS”

    PubMed Central

    Dasari, Mauna; Thomas, Brian C.; Shah, Manesh B.; VerBerkmoes, Nathan C.; Hettich, Robert L.; Banfield, Jillian F.

    2013-01-01

    Leptospirillum spp. are widespread members of acidophilic microbial communities that catalyze ferrous iron oxidation, thereby increasing sulfide mineral dissolution rates. These bacteria play important roles in environmental acidification and are harnessed for bioleaching-based metal recovery. Known members of the Leptospirillum clade of the Nitrospira phylum are Leptospirillum ferrooxidans (group I), Leptospirillum ferriphilum and “Leptospirillum rubarum” (group II), and Leptospirillum ferrodiazotrophum (group III). In the Richmond Mine acid mine drainage (AMD) system, biofilm formation is initiated by L. rubarum; L. ferrodiazotrophum appears in later developmental stages. Here we used community metagenomic data from unusual, thick floating biofilms to identify distinguishing metabolic traits in a rare and uncultivated community member, the new species “Leptospirillum group IV UBA BS.” These biofilms typically also contain a variety of Archaea, Actinobacteria, and a few other Leptospirillum spp. The Leptospirillum group IV UBA BS species shares 98% 16S rRNA sequence identity and 70% average amino acid identity between orthologs with its closest relative, L. ferrodiazotrophum. The presence of nitrogen fixation and reverse tricarboxylic acid (TCA) cycle proteins suggest an autotrophic metabolism similar to that of L. ferrodiazotrophum, while hydrogenase proteins suggest anaerobic metabolism. Community transcriptomic and proteomic analyses demonstrate expression of a multicopper oxidase unique to this species, as well as hydrogenases and core metabolic genes. Results suggest that the Leptospirillum group IV UBA BS species might play important roles in carbon fixation, nitrogen fixation, hydrogen metabolism, and iron oxidation in some acidic environments. PMID:23645189

  3. A new group in the Leptospirillum clade: cultivation-independent community genomics, proteomics and transcriptomics of the new species Leptospirillum group IV UBA BS.

    SciTech Connect

    Goltsman, Daniela; Dasari, Mauna; Thomas, BC; Shah, Manesh B; Verberkmoes, Nathan C; Hettich, Robert {Bob} L; Banfield, Jillian F.

    2013-01-01

    Leptospirillum spp. are widespread members of acidophilic microbial communities that catalyze ferrous iron oxidation, thereby increasing sulfide mineral dissolution rates. These bacteria play important roles in environmental acidification and are harnessed for bioleaching-based metal recovery. Known members of the Leptospirillum clade of the Nitrospira phylum are Leptospirillum ferrooxidans (group I), Leptospirillum ferriphilum and Leptospirillum rubarum (group II), and Leptospirillum ferrodiazotrophum (group III). In the Richmond Mine acid mine drainage (AMD) system, biofilm formation is initiated by L. rubarum; L. ferrodiazotrophum appears in later developmental stages. Here we used community metagenomic data from unusual, thick floating biofilms to identify distinguishing metabolic traits in a rare and uncultivated community member, the new species Leptospirillum group IV UBA BS. These biofilms typically also contain a variety of Archaea, Actinobacteria, and a few other Leptospirillum spp. The Leptospirillum group IV UBA BS species shares 98% 16S rRNA sequence identity and 70% average amino acid identity between orthologs with its closest relative, L. ferrodiazotrophum. The presence of nitrogen fixation and reverse tricarboxylic acid (TCA) cycle proteins suggest an autotrophic metabolism similar to that of L. ferrodiazotrophum, while hydrogenase proteins suggest anaerobic metabolism. Community transcriptomic and proteomic analyses demonstrate expression of a multicopper oxidase unique to this species, as well as hydrogenases and core metabolic genes. Results suggest that the Leptospirillum group IV UBA BS species might play important roles in carbon fixation, nitrogen fixation, hydrogen metabolism, and iron oxidation in some acidic environments.

  4. 40 CFR Appendix IV to Part 600 - Sample Fuel Economy Labels for 2008 and Later Model Year Vehicles

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Sample Fuel Economy Labels for 2008 and Later Model Year Vehicles IV Appendix IV to Part 600 Protection of Environment ENVIRONMENTAL... VEHICLES Pt. 600, App. IV Appendix IV to Part 600—Sample Fuel Economy Labels for 2008 and Later Model...

  5. Electron/phonon coupling in group-IV transition-metal and rare-earth nitrides

    SciTech Connect

    Mei, A. B.; Rockett, A.; Hultman, L.; Petrov, I.; Greene, J. E.

    2013-11-21

    Transport electron/phonon coupling parameters and Eliashberg spectral functions α{sub tr}{sup 2}F(ℏω) are determined for group-IV transition-metal (TM) nitrides TiN, ZrN, and HfN, and the rare-earth (RE) nitride CeN using an inversion procedure based upon temperature-dependent (4 < T < 300 K) resistivity measurements of high-crystalline-quality stoichiometric epitaxial films grown on MgO(001) by magnetically-unbalanced reactive magnetron sputtering. Transport electron/phonon coupling parameters λ{sub tr} vary from 1.11 for ZrN to 0.82 for HfN, 0.73 for TiN, and 0.44 for CeN. The small variation in λ{sub tr} among the TM nitrides and the weak coupling in CeN are consistent with measured superconducting transition temperatures 10.4 (ZrN), 9.18 (HfN), 5.35 (TiN), and <4 K for CeN. The Eliashberg spectral function describes the strength and energy spectrum of electron/phonon coupling in conventional superconductors. Spectral peaks in α{sup 2}F(ℏω), corresponding to regions in energy-space for which electrons couple to acoustic ℏω{sub ac} and optical ℏω{sub op} phonon modes, are centered at ℏω{sub ac} = 33 and ℏω{sub op} = 57 meV for TiN, 25 and 60 meV for ZrN, 18 and 64 meV for HfN, and 21 and 39 meV for CeN. The acoustic modes soften with increasing cation mass; optical mode energies remain approximately constant for the TM nitrides, but are significantly lower for the RE nitride due to a lower interatomic force constant. Optical/acoustic peak-intensity ratios are 1.15 ± 0.1 for all four nitrides, indicating similar electron/phonon coupling strengths α{sub tr}(ℏω) for both modes.

  6. Growth and activation of group IV semiconductors for application in infrared detectors and photovoltaics

    NASA Astrophysics Data System (ADS)

    Xie, Junqi

    Bandgaps in group IV semiconductors such as Ge1-ySn y and Ge1-x-ySixSny are tunable by varying the material composition. The tunable bandgaps make these materials with potential applications in photodetectors, modulators, waveguiders, lasers and photovolatics. This dissertation reports significant improvements of the low-temperature chemical vapor deposition (CVD) process leading to growth of device quality Ge0.98Sn0.02 films with thickness over 500 nm. Highly controlled and efficient doping protocols were also developed to obtain facile substitution and complete activation of dopant atoms at levels 1017 -- 1019 cm-3 via both conventional and custom built molecules. Ge0.98Sn0.02-based PIN structures were subsequently fabricated and characterized. Results show that the incorporation of only 2% of Sn extends the infrared performance of Ge0.98Sn 0.02 based optoelectronic devices to the entire range of transmission windows for telecom applications. Higher Sn content (5% Sn) Ge1-ySny films were also studied to extend the device performance range even further into the infrared. The successful depositions of intrinsic, p- and n-type materials with doping levels 1018-1020/cm3 indicate all components were in place for the fabrication of Ge0.95Sn 0.02-based PIN structures. Meanwhile, a new approach to high quality Ge1-x-ySix Sny ternaries grown directly on both Ge(100) and Si (100) substrates was established based on commercially available sources such as trisilane, digermane and stannane. The soft chemistry process was extended to fabricated p- and n-type layers on Si, and their optical and electrical properties were determined. Characterizations indicate that the properties of GeSiSn are independent of the platform on which they are grown including Si, Ge or GeSn/Si. First-principles calculations show that mixing entropy thermodynamically stabilizes SiGeSn in contrast to GeSn analogs with the same Sn content, in good agreement with experimentally observation. In addition

  7. Structural and energetic properties of acetonitrile-Group IV (A & B) halide complexes.

    PubMed

    Helminiak, Heather M; Knauf, Robin R; Danforth, Samuel J; Phillips, James A

    2014-06-19

    We have conducted an extensive computational study of the structural and energetic properties of select acetonitrile-Group IV (A & B) tetrahalide complexes, both CH3CN-MX4 and (CH3CN)2-MX4 (M = Si, Ge, Ti; X = F, Cl). We have also examined the reactivity of CH3CN with SiF4, SiCl4, GeCl4, and TiCl4, and measured low-temperature IR spectra of thin films containing CH3CN with SiF4, GeCl4, or TiCl4. The six 1:1 complexes fall into two general structural classes. CH3CN-TiCl4, CH3CN-TiF4, and CH3CN-GeF4, exhibit relatively short M-N bonds (~2.3 Å), an intermediate degree of distortion in the MX4 subunit, and binding energies ranging from 11.0 to 13.0 kcal/mol. Conversely, CH3CN-GeCl4, CH3CN-SiF4, and CH3CN-SiCl4, are weakly bonded systems, with long M-N distances (>3.0 Å), little distortion in the MX4 subunit, and binding energies ranging from 3.0 to 4.4 kcal/mol. The structural features of analogous 2:1 systems resemble those of their 1:1 counterparts, whereas the binding energies (relative to three isolated fragments) are roughly twice as large. Calculated M-N potential curves in the gas phase and bulk, dielectric media are reported for all 1:1 complexes, and for two systems, CH3CN-GeF4 and CH3CN-SiF4, these data predict significant condensed-phase structural changes. The effect on the CH3CN-SiF4 potential is extreme; the curve becomes quite flat over a broad range in dielectric media, and at higher ε values, the global minimum shifts inward by about 1.0 Å. In bulk reactivity experiments, no reaction was observed between CH3CN and SiF4, SiCl4, or GeCl4, whereas CH3CN and TiCl4 were found to react immediately upon contact. Also, thin-film IR spectra indicate a strong interaction between CH3CN and TiCl4, yet only weak interactions between CH3CN and GeCl4 or SiF4 in the solid state. PMID:24852185

  8. Lymantria dispar iflavirus 1 (LdIV1), a new model to study iflaviral persistence in lepidopterans.

    PubMed

    Carrillo-Tripp, Jimena; Krueger, Elizabeth N; Harrison, Robert L; Toth, Amy L; Miller, W Allen; Bonning, Bryony C

    2014-10-01

    The cell line IPLB-LD-652Y, derived from the gypsy moth (Lymantria dispar L.), is routinely used to study interactions between viruses and insect hosts. Here we report the full genome sequence and biological characteristics of a small RNA virus, designated Lymantria dispar iflavirus 1 (LdIV1), that was discovered to persistently infect IPLB-LD-652Y. LdIV1 belongs to the genus Iflavirus. LdIV1 formed icosahedral particles of approx. 30 nm in diameter and contained a 10, 044 nt polyadenylated, positive-sense RNA genome encoding a predicted polyprotein of 2980 aa. LdIV1 was induced by a viral suppressor of RNA silencing, suggesting that acute infection is restricted by RNA interference (RNAi). We detected LdIV1 in all tested tissues of gypsy-moth larvae and adults, but the virus was absent from other L. dispar-derived cell lines. We confirmed LdIV1 infectivity in two of these cell lines (IPLB-LD-652 and IPLB-LdFB). Our results provide a novel system to explore persistent infections in lepidopterans and a new model for the study of iflaviruses, a rapidly expanding group of viruses, many of which covertly infect their hosts. PMID:24986084

  9. Validation of DSM-IV Model of Psychiatric Syndromes in Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Lecavalier, Luc; Gadow, Kenneth D.; DeVincent, Carla J.; Edwards, Michael C.

    2009-01-01

    The objective of this study was to assess the internal construct validity of the DSM-IV as a conceptual model for characterizing behavioral syndromes in children with ASD. Parent and teachers completed the Child Symptom Inventory-4, a DSM-IV-referenced rating scale, for 6-to-12 year old clinic referrals with an ASD (N = 498). Ratings were…

  10. 40 CFR Appendix IV to Part 600 - Sample Fuel Economy Labels for 2008 Through 2012 Model Year Vehicles

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 31 2013-07-01 2013-07-01 false Sample Fuel Economy Labels for 2008 Through 2012 Model Year Vehicles IV Appendix IV to Part 600 Protection of Environment ENVIRONMENTAL... VEHICLES Pt. 600, App. IV Appendix IV to Part 600—Sample Fuel Economy Labels for 2008 Through 2012...

  11. 40 CFR Appendix IV to Part 600 - Sample Fuel Economy Labels for 2008 and Later Model Year Vehicles

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Sample Fuel Economy Labels for 2008 and Later Model Year Vehicles IV Appendix IV to Part 600 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY AND CARBON-RELATED EXHAUST EMISSIONS OF MOTOR VEHICLES Pt. 600, App. IV Appendix IV to Part...

  12. Development of group IV molecular catalysts for high temperature ethylene-α-olefin copolymerization reactions.

    PubMed

    Klosin, Jerzy; Fontaine, Philip P; Figueroa, Ruth

    2015-07-21

    This Account describes our research related to the development of molecular catalysts for solution phase olefin polymerization. Specifically, a series of constrained geometry and nonmetallocene (imino-amido-type) complexes were developed for high temperature olefin polymerization reactions. We have discovered many highly active catalysts that are capable of operating at temperatures above 120 °C and producing copolymers with a useful range of molecular weights (from medium to ultrahigh depending on precatalyst identity and polymerization conditions) and α-olefin incorporation capability. Constrained geometry catalysts (CGCs) exhibit very high activities and are capable of producing a variety of copolymers including ethylene-propylene and ethylene-1-octene copolymers at high reactor temperatures. Importantly, CGCs have much higher reactivity toward α-olefins than classical Ziegler-Natta catalysts, thus allowing for the production of copolymers with any desired level of comonomer. In search of catalysts with improved performance, we discovered 3-amino-substituted indenyl-based CGCs that exhibit the highest activity and produce copolymers with the highest molecular weight within this family of catalysts. Phenanthrenyl-based CGCs were found to be outstanding catalysts for the effective production of high styrene content ethylene-styrene copolymers under industrially relevant conditions. In contrast to CGC ligands, imino-amido-type ligands are bidentate and monoionic, leading to the use of trialkyl group IV precatalysts. The thermal instability of imino-amido complexes was addressed by the development of imino-enamido and amidoquinoline complexes, which are not only thermally very robust, but also produce copolymers with higher molecular weights, and exhibit improved α-olefin incorporation. Imido-amido and imino-enamido catalysts undergo facile chain transfer reactions with metal alkyls, as evidenced by a sharp decrease in polymer molecular weight when the

  13. The effects of anion exchange functional-group variations on the sorption of Pu(IV) from nitric acid

    SciTech Connect

    Marsh, S.F.

    1995-12-01

    A macroporous, polyvinylpyridine anion exchange resin has been used for more than five years at the Los Alamos Plutonium Facility to recover plutonium from nitrate media. This strong-base anion exchanger, Reillex{trademark} HPQ, offers higher capacity, faster kinetics, and significantly higher resistance to chemical and radiation damage than conventional polystyrene-based resins. In this study, we measured the sorption of Pu(IV) on Reillex{trademark} HPQ and on three macroporous, strong-base anion exchange resins that differ from Reillex{trademark} HPQ only in the alkyl group used to quaternize the pyridinium. nitrogen. These four resins, prepared by Reilly Industries, Inc., are copolymers of 1-alkyl-4-vinylpyridine, where the alkyl groups are methyl, butyl, hexyl, and octyl. We compare the trends in Pu(IV) sorption on these four resins to those obtained in our previous study of four polystyrene anion exchange resins having trimethyl, triethyl, tripropyl, and tributyl ammonium functionality. The Pu(IV) sorption was measured from 1 M to 9 M nitric acid in both studies.

  14. 45 CFR 310.10 - What are the functional requirements for the Model Tribal IV-D System?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 2 2011-10-01 2011-10-01 false What are the functional requirements for the Model Tribal IV-D System? 310.10 Section 310.10 Public Welfare Regulations Relating to Public Welfare OFFICE OF... requirements for the Model Tribal IV-D System? A Model Tribal IV-D System must: (a) Accept, maintain...

  15. Modeling Grade IV Gas Emboli using a Limited Failure Population Model with Random Effects

    NASA Technical Reports Server (NTRS)

    Thompson, Laura A.; Conkin, Johnny; Chhikara, Raj S.; Powell, Michael R.

    2002-01-01

    Venous gas emboli (VGE) (gas bubbles in venous blood) are associated with an increased risk of decompression sickness (DCS) in hypobaric environments. A high grade of VGE can be a precursor to serious DCS. In this paper, we model time to Grade IV VGE considering a subset of individuals assumed to be immune from experiencing VGE. Our data contain monitoring test results from subjects undergoing up to 13 denitrogenation test procedures prior to exposure to a hypobaric environment. The onset time of Grade IV VGE is recorded as contained within certain time intervals. We fit a parametric (lognormal) mixture survival model to the interval-and right-censored data to account for the possibility of a subset of "cured" individuals who are immune to the event. Our model contains random subject effects to account for correlations between repeated measurements on a single individual. Model assessments and cross-validation indicate that this limited failure population mixture model is an improvement over a model that does not account for the potential of a fraction of cured individuals. We also evaluated some alternative mixture models. Predictions from the best fitted mixture model indicate that the actual process is reasonably approximated by a limited failure population model.

  16. Holistic medicine IV: principles of existential holistic group therapy and the holistic process of healing in a group setting.

    PubMed

    Ventegodt, Søren; Andersen, Niels Jørgen; Merrick, Joav

    2003-12-23

    In existential holistic group therapy, the whole person heals in accordance with the holistic process theory and the life mission theory. Existential group psychotherapy addresses the emotional aspect of the human mind related to death, freedom, isolation, and meaninglessness, while existential holistic group therapy addresses the state of the person"s wholeness. This includes the body, the person's philosophy of life, and often also love, purpose of life, and the spiritual dimension, to the same extent as it addresses the emotional psyche and sexuality, and it is thus much broader than traditional psychotherapy. Where existential psychotherapy is rather depressing concerning the fundamental human condition, existential holistic therapy conceives life to be basically good. The fundamentals in existential holistic therapy are that everybody has the potential for healing themselves to become loving, joyful, sexually attractive, strong, and gifted, which is a message that most patients welcome. While the patient is suffering and fighting to get through life, the most important job for the holistic therapist is to keep a positive perspective of life. In accordance with these fundamentals, many participants in holistic group therapy will have positive emotional experiences, often of an unknown intensity, and these experiences appear to transform their lives within only a few days or weeks of therapy. An important idea of the course is Bohm's concept of "holo-movement" in the group, resulting from intense coherence between the group members. When the group comes together, the individual will be linked to the totality and the great movement forward towards love, consciousness, and happiness will happen collectively--if it happens at all. This gives the individual the feeling that everything that happens is right, important, and valuable for all the participants at the same time. Native Americans and other premodern people refer to this experience as "the spiritual design

  17. First-principles study of monolayer and bilayer honeycomb structures of group-IV elements and their binary compounds

    NASA Astrophysics Data System (ADS)

    Pan, L.; Liu, H. J.; Wen, Y. W.; Tan, X. J.; Lv, H. Y.; Shi, J.; Tang, X. F.

    2011-01-01

    By using first-principles pseudopotential method, we investigate the structural, vibrational, and electronic properties of monolayer and bilayer honeycomb structures of group-IV elements and their binary compounds. It is found that the honeycomb structures of Si, Ge, and SiGe are buckled for stabilization, while those of binary compounds SiC and GeC containing the first row elements C are planar similar to a graphene sheet. The phonon dispersion relations and electronic band structures are very sensitive to the number of layers, the stacking order, and whether the layers are planar or buckled.

  18. Ignition and Growth Modeling of Short Pulse Duration Shock Initiation Experiments on HNS IV

    NASA Astrophysics Data System (ADS)

    Tarver, Craig; Chidester, Steven

    2013-06-01

    Short pulse duration shock initiation experiments on 1.60 g/cm3 density (92% TMD) HNS IV have been reported by Schwarz, Bowden et al., Dudley et al., Goveas et al., Greenaway et al., and others. This flyer threshold velocity for detonation/failure data plus measured unreacted HNS Hugoniot data and detonation cylinder test product expansion data were used as the experimental basis for the development of an Ignition and Growth reactive flow model for the shock initiation of HNS IV. The resulting Ignition and Growth HNS IV model parameters yielded good overall agreement with all of this experimental data. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.: Explosive, HNS IV, shock to detonation transition, Ignition and Growth: 82.33.Vx, 82.40.Fp.

  19. Consistent Multigroup Theory Enabling Accurate Course-Group Simulation of Gen IV Reactors

    SciTech Connect

    Rahnema, Farzad; Haghighat, Alireza; Ougouag, Abderrafi

    2013-11-29

    The objective of this proposal is the development of a consistent multi-group theory that accurately accounts for the energy-angle coupling associated with collapsed-group cross sections. This will allow for coarse-group transport and diffusion theory calculations that exhibit continuous energy accuracy and implicitly treat cross- section resonances. This is of particular importance when considering the highly heterogeneous and optically thin reactor designs within the Next Generation Nuclear Plant (NGNP) framework. In such reactors, ignoring the influence of anisotropy in the angular flux on the collapsed cross section, especially at the interface between core and reflector near which control rods are located, results in inaccurate estimates of the rod worth, a serious safety concern. The scope of this project will include the development and verification of a new multi-group theory enabling high-fidelity transport and diffusion calculations in coarse groups, as well as a methodology for the implementation of this method in existing codes. This will allow for a higher accuracy solution of reactor problems while using fewer groups and will reduce the computational expense. The proposed research represents a fundamental advancement in the understanding and improvement of multi- group theory for reactor analysis.

  20. Giant piezoelectricity of monolayer group IV monochalcogenides: SnSe, SnS, GeSe, and GeS

    NASA Astrophysics Data System (ADS)

    Fei, Ruixiang; Li, Wenbin; Li, Ju; Yang, Li

    2015-10-01

    We predict enormous, anisotropic piezoelectric effects in intrinsic monolayer group IV monochalcogenides (MX, M=Sn or Ge, X=Se or S), including SnSe, SnS, GeSe, and GeS. Using first-principle simulations based on the modern theory of polarization, we find that their piezoelectric coefficients are about one to two orders of magnitude larger than those of other 2D materials, such as MoS2 and GaSe, and bulk quartz and AlN which are widely used in industry. This enhancement is a result of the unique "puckered" C2v symmetry and electronic structure of monolayer group IV monochalcogenides. Given the achieved experimental advances in the fabrication of monolayers, their flexible character, and ability to withstand enormous strain, these 2D structures with giant piezoelectric effects may be promising for a broad range of applications such as nano-sized sensors, piezotronics, and energy harvesting in portable electronic devices.

  1. Effect of phase transition on quantum transport in group-IV two-dimensional U-shape device

    SciTech Connect

    Sadi, Mohammad Abdullah; Gupta, Gaurav Liang, Gengchiau

    2014-10-21

    The effect of phase-transition from the quantum-spin-hall to the band-insulator phase on the transport through a three-terminal U-shape spin-separator has been computationally investigated via non-equilibrium green function formalism. Two-dimensional group-IV elements have been comprehensively appraised as the device material. The device separates the unpolarized current injected at the source-terminal into nearly 100% spin-polarized currents of the opposite polarities at the two drain terminals. The phase-transition activated by the electric-field orthogonal to the device is shown to extensively influence the current magnitude and its spin-polarization, and the effect is stronger for materials with smaller intrinsic spin-orbit coupling. Moreover, the device length and the area under field are shown to critically affect the device characteristics on phase change. It is shown that the same device can be operated as a spin-filter by inducing phase-transition selectively in the channel. The results are important for designing spin-devices from Group-IV monolayers.

  2. Giant piezoelectricity of monolayer group IV monochalcogenides: SnSe, SnS, GeSe, and GeS

    SciTech Connect

    Fei, Ruixiang; Yang, Li; Li, Wenbin; Li, Ju

    2015-10-26

    We predict enormous, anisotropic piezoelectric effects in intrinsic monolayer group IV monochalcogenides (MX, M=Sn or Ge, X=Se or S), including SnSe, SnS, GeSe, and GeS. Using first-principle simulations based on the modern theory of polarization, we find that their piezoelectric coefficients are about one to two orders of magnitude larger than those of other 2D materials, such as MoS{sub 2} and GaSe, and bulk quartz and AlN which are widely used in industry. This enhancement is a result of the unique “puckered” C{sub 2v} symmetry and electronic structure of monolayer group IV monochalcogenides. Given the achieved experimental advances in the fabrication of monolayers, their flexible character, and ability to withstand enormous strain, these 2D structures with giant piezoelectric effects may be promising for a broad range of applications such as nano-sized sensors, piezotronics, and energy harvesting in portable electronic devices.

  3. D category IV: a group of clinically relevant and phylogenetically diverse partial D

    PubMed Central

    von Zabern, Inge; Wagner, Franz F.; Moulds, Joann M.; Moulds, John J.; Flegel, Willy A.

    2013-01-01

    Background The D typing strategies in several European countries protect carriers of D category VI (DVI) from anti-D immunization but not carriers of other partial D. Besides DVI, one of the clinically most important partial D is D category IV (DIV). A detailed description and direct comparison of the different DIV types was missing. Study design and methods RHD nucleotide sequences were determined from genomic DNA. D epitope patterns were established with commercial monoclonal anti-D panels. Results DIV comprises several variants of the D antigen with distinct serology, molecular structures, evolutionary origins and ethnic prevalences. The DIV phenotype is determined by 350H shared by all, but not limited to, DIV variants which are further divided into DIVa and DIVb. The DIVa phenotype is expressed by DIV type 1.0 harboring 350H and the dispersed amino acids 62F, 137V and 152T. The DIVb phenotype is expressed by DIV type 3 to type 5 representing RHD-CE-D hybrids. 4 of the 6 postulated DIV variants were encountered among 23 DIV samples analyzed. Of 12 DIV carriers with anti-D, 10 were female and 7 likely immunized by pregnancy. 2 DIV related alleles are newly described: DWN which differs from DIV type 4 by 350D and epitope pattern. DNT carries 152T, known to cause a large D antigen density. Conclusion DIV alleles arose from at least 2 independent evolutionary events. DIV type 1.0 with DIVa phenotype belongs to the oldest extant human RHD alleles. DIV type 2 to type 5 with DIVb phenotype arose from more recent gene conversions. Anti-D immunization, especially dreaded in pregnancies, will be avoided not only in carriers of DVI but also in carriers of other D variants like DIV, if our proposed D typing strategy is adopted. PMID:23461862

  4. Analysis of spiroplasma proteins: contribution to the taxonomy of group IV spiroplasmas and the characterization of spiroplasma protein antigens.

    PubMed Central

    Mouches, C.; Candresse, T.; McGarrity, G. J.; Bové, J. M.

    1983-01-01

    Spiroplasma strains of group IV were compared by two-dimensional protein analyses on polyacrylamide gels. Although considerable diversity was evident, the assemblages studied were less heterogeneous than the known strains of group I. Two electrophoretic techniques were used to identify spiroplasma proteins that had been used to immunize rabbits. These included monoclonal antibodies prepared against Spiroplasma citri. In the first technique, protein antigens were purified by immunoaffinity chromatography, then identified with SDS-PAGE. In the second technique, spiroplasma proteins were first separated by SDS-PAGE, then antigens were identified by antibody binding to blot-transferred proteins. Finally, two-dimensional protein electrophoresis has been used as a source of immunogens to characterize monospecific antibodies against individual S. citri proteins. Images FIG. 1 FIG. 2 PMID:6206657

  5. Bradykinin-induced modulation of the response behaviour of different types of feline group III and IV muscle receptors.

    PubMed Central

    Mense, S; Meyer, H

    1988-01-01

    1. In order to test the hypothesis that bradykinin has a sensitizing action on muscle receptors (e.g. during a myositis), the response properties of single group III and IV afferent units from the cat gastrocnemius-soleus muscle were compared before and after infiltration of their receptive fields with a bradykinin solution. According to their responses to graded natural stimuli (local pressure, stretch, contractions and temperature changes) the units were classified as (a) nociceptors, (b) low-threshold pressure-sensitive (LTP) receptors, (c) contraction-sensitive (CS) receptors and (d) thermosensitive receptors. 2. Bradykinin activated the majority of both the nociceptive and low-threshold (LTP, CS and thermosensitive) receptors but a sensitization was prominent only among the nociceptors. Most of the sensitized nociceptors showed increased responses to mechanical, but not to thermal, stimuli. The sensitization appeared to be quite specific in that the nociceptors were sensitized either towards local pressure stimulation or to active contractions, but never towards both forms of stimulation. 3. Both group III and group IV nociceptors were sensitized by bradykinin, the proportion of sensitized receptors being greater for group III units. 4. Some of the low-threshold receptors (particularly the CS units) showed a desensitization under the influence of bradykinin. 5. Although bradykinin (by lowering the mechanical thresholds of nociceptors into the innocuous range) could produce the symptom of allodynia, it was not capable of eliciting all the changes in receptor behaviour which are known to occur in inflamed tissues. For instance, no ongoing activity of longer duration and no substantial sensitization of low-threshold receptors have been observed in the present study. PMID:3392680

  6. Compact groups in theory and practice - IV. The connection to large-scale structure

    NASA Astrophysics Data System (ADS)

    Mendel, J. Trevor; Ellison, Sara L.; Simard, Luc; Patton, David R.; McConnachie, Alan W.

    2011-12-01

    We investigate the properties of photometrically selected compact groups (CGs) in the Sloan Digital Sky Survey. In this paper, the fourth in a series, we focus on understanding the characteristics of our observed CG sample with particular attention paid to quantifying and removing contamination from projected foreground or background galaxies. Based on a simple comparison of pairwise redshift likelihoods, we find that approximately half of CGs in the parent sample contain one or more projected (interloping) members; our final clean sample contains 4566 galaxies in 1086 CGs. We show that half of the remaining CGs are associated with rich groups (or clusters), i.e. they are embedded sub-structure. The other half have spatial distributions and number-density profiles consistent with the interpretation that they are either independently distributed structures within the field (i.e. they are isolated) or associated with relatively poor structures. Comparisons of late-type and red-sequence fractions in radial annuli show that galaxies around apparently isolated CGs resemble the field population by 300 to 500 kpc from the group centre. In contrast, the galaxy population surrounding embedded CGs appears to remain distinct from the field out beyond 1 to 2 Mpc, consistent with results for rich groups. We take this as additional evidence that the observed distinction between CGs, i.e. isolated versus embedded, is a separation between different host environments.

  7. Genetic improvement of U.S. soybean in Maturity Groups II, III, and IV

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean [Glycine max (L.) Merr.] improvement via plant breeding has been critical for the success of the crop. The objective of this study was to quantify genetic change in yield and other traits that occurred over the past 80 years of North American soybean breeding in maturity groups (MGs) II, III...

  8. Use of Improved Orbitals for CCSD(T) Calculations for Predicting Heats of Formation of Group IV and Group VI Metal Oxide Monomers and Dimers and UCl6.

    PubMed

    Fang, Zongtang; Lee, Zachary; Peterson, Kirk A; Dixon, David A

    2016-08-01

    The prediction of the heats of formation of group IV and group VI metal oxide monomers and dimers with the coupled cluster CCSD(T) method has been improved by using Kohn-Sham density functional theory (DFT) and Brueckner orbitals for the initial wave function. The valence and core-valence contributions to the total atomization energies for the CrO3 monomer and dimer are predicted to be significantly larger than when using the Hartree-Fock (HF) orbitals. The predicted heat of formation of CrO3 with CCSD(T)/PW91 is consistent with previous calculations including high-order corrections beyond CCSD(T) and agrees well with the experiment. The improved heats of formation with the DFT and Brueckner orbitals are due to these orbitals being closer to the actual orbitals. Pure DFT functionals perform slightly better than the hybrid B3LYP functional due to the presence of exact exchange in the hybrid functional. Comparable heats of formation for TiO2 and the second- and the third-row group IV and group VI metal oxides are predicted well using either the DFT PW91 orbitals, Brueckner orbitals, or HF orbitals. The normalized clustering energies for the dimers are consistent with our previous work except for a larger value predicted for Cr2O6. The prediction of the reaction energy for UF6 + 3Cl2 → UCl6 + 3F2 was significantly improved with the use of DFT or Brueckner orbitals as compared to HF orbitals. PMID:27398941

  9. Teaching Group Work: Modeling Group Leader and Member Behaviors in the Classroom to Demonstrate Group Theory

    ERIC Educational Resources Information Center

    Riva, Maria T.; Korinek, Lauri

    2004-01-01

    Training in group counseling typically includes an academic component, although little has been written about how to teach a group course except for what specific content should be included. This article suggests that while teaching group counseling courses, instructors can intentionally model effective group leader behaviors and use these…

  10. Inter-Division IV-V / Working Group Ap and Related Stars

    NASA Astrophysics Data System (ADS)

    Cunha, Margarida S.; Weiss, Werner W.; Dworetsky, Michael M.; Kochukhov, Oleg; Kupka, Friedrich; Leblanc, Francis; Monier, Richard; Paunzen, Ernst; Piskunov, Nikolai E.; Shibahashi, Hiromoto; Smalley, Barry; Ziznovsky, Jozef

    The diversity of physical phenomena embraced by the study of Chemically Peculiar (CP) stars results in an associated research community with interests that are equally diverse. This fact became once more evident during the CP#Ap Workshop that took place in Vienna (Austria) in September 2007, and which gathered over 80 members of this research community. Besides the excellent scientific outcome of the meeting, during the workshop the community had the opportunity to discuss its organization and plans for the future. Following on those plans, the Working Group has submitted a proposal for a Joint Discussion during the IAU XXVII General Assembly, in Rio de Janeiro, which has meanwhile been accepted. Moreover, through an ApN newsletter forum, the Working Group has compiled requests from the community concerning atomic and related data. These requests have been put together and will be shared with Commission 14.

  11. Fossil group origins. IV. Characterization of the sample and observational properties of fossil systems

    NASA Astrophysics Data System (ADS)

    Zarattini, S.; Barrena, R.; Girardi, M.; Castro-Rodriguez, N.; Boschin, W.; Aguerri, J. A. L.; Méndez-Abreu, J.; Sánchez-Janssen, R.; Catalán-Torrecilla, C.; Corsini, E. M.; del Burgo, C.; D'Onghia, E.; Herrera-Ruiz, N.; Iglesias-Páramo, J.; Jimenez Bailon, E.; Lozada Muoz, M.; Napolitano, N.; Vilchez, J. M.

    2014-05-01

    Context. Virialized halos grow by the accretion of smaller ones in the cold dark matter scenario. The rate of accretion depends on the different properties of the host halo. Those halos for which this accretion rate was very fast and efficient resulted in systems dominated by a central galaxy surrounded by smaller galaxies that were at least two magnitudes fainter. These galaxy systems are called fossil systems, and they can be the fossil relics of ancient galaxy structures. Aims: We started an extensive observational program to characterize a sample of 34 fossil group candidates spanning a broad range of physical properties. Methods: Deep r-band images were obtained with the 2.5-m Isaac Newton Telescope and Nordic Optic Telescope. Optical spectroscopic observations were performed at the 3.5-m Telescopio Nazionale Galileo for ~1200 galaxies. This new dataset was completed with Sloan Digital Sky Survey Data Release 7 archival data to obtain robust cluster membership and global properties of each fossil group candidate. For each system, we recomputed the magnitude gaps between the two brightest galaxies (Δm12) and the first and fourth ranked galaxies (Δm14) within 0.5 R200. We consider fossil systems to be those with Δm12 ≥ 2 mag or Δm14 ≥ 2.5 mag within the errors. Results: We find that 15 candidates turned out to be fossil systems. Their observational properties agree with those of non-fossil systems. Both follow the same correlations, but the fossil systems are always extreme cases. In particular, they host the brightest central galaxies, and the fraction of total galaxy light enclosed in the brightest group galaxy is larger in fossil than in non-fossil systems. Finally, we confirm the existence of genuine fossil clusters. Conclusions: Combining our results with others in the literature, we favor the merging scenario in which fossil systems formed from mergers of L∗ galaxies. The large magnitude gap is a consequence of the extreme merger ratio within

  12. Phase Stability under Irradiation of Precipitates and Solid Solutions in Model ALloys and in ODS Alloys Relevant for Gen IV

    SciTech Connect

    Arthur T. Motta; Robert C. Birtcher

    2007-10-17

    The overall objective of this program is to investigate the irradiation-altered phase stability of oxide precipitates in ODS steels and of model alloy solid solutions of associated systems. This information can be used to determine whether the favorable mechanical propertiies of these steels are maintained under irradiation, thus addressing one of the main materials research issues for this class of steels as identified by the GenIV working groups. The research program will also create fundamental understanding of the irradiation precipitation/dissolution problem by studying a "model" system in which the variables can be controlled and their effects understood individually.

  13. Effect of Astragaloside IV on Neural Stem Cell Transplantation in Alzheimer's Disease Rat Models

    PubMed Central

    Haiyan, Hu; Rensong, Yang; Guoqin, Jin; Xueli, Zhang; Huaying, Xia; Yanwu, Xu

    2016-01-01

    Stem cell-based therapy is a promising treatment strategy for neurodegenerative diseases such as Alzheimer's disease (AD). However, the mechanism underlying the maintenance of renewal and replacement capabilities of endogenous progenitor cells or engrafted stem cells in a pathological environment remains elusive. To investigate the effect of astragaloside IV (ASI) on the proliferation and differentiation of the engrafted neural stem cells (NSCs), we cultured NSCs from the hippocampus of E14 rat embryos, treated the cells with ASI, and then transplanted the cells into the hippocampus of rat AD models. In vitro experimentation showed that 10−5 M ASI induced NSCs to differentiate into β-tubulin III+ and GFAP+ cells. NSCs transplantation into rat AD models resulted in improvements in learning and memory, especially in the ASI-treated groups. ASI treatment resulted in an increase in the number of β-tubulin III+ cells in the hippocampus. Further investigation showed that ASI inhibited PS1 expression in vitro and in vivo. The high-dose ASI downregulated the Notch intracellular domain, whereas the low-dose ASI increased Notch-1 and NICD. In conclusion, ASI treatment resulted in improvements in learning and memory of AD models by promoting NSC proliferation and differentiation partly through the Notch signal pathway. PMID:27034688

  14. IGORR-IV -- Proceedings of the fourth meeting of the International Group on Research Reactors

    SciTech Connect

    Rosenbalm, K.F.

    1995-12-31

    The International Group on Research Reactors was formed to facilitate the sharing of knowledge and experience among those institutions and individuals who are actively working to design, build, and promote new research reactors or to make significant upgrades to existing facilities. Twenty-nine papers were presented in five sessions and written versions of the papers or hard copies of the vugraphs used are published in these proceedings. The five sessions were: (1) Operating Research Reactors and Facility Upgrades; (2) Research Reactors in Design and Construction; (3) ANS Closeout Activities; (4) and (5) Research, Development, and Analysis Results.

  15. Long range ordered alloys modified by group IV-B metals

    DOEpatents

    Liu, Chain T.; Inouye, Henry; Schaffhauser, Anthony C.

    1983-01-01

    Ductile long range ordered alloys having high critical ordering temperatures exist in the (V,M)(Fe,Ni,Co).sub.3 system having the composition comprising by weight 20.6%-22.6% V, 14-50% Fe, 0-64% Co, and 0-40% Ni, and 0.4-1.4% M, where M is a metal selected from the group consisting of Ti, Zr, Hf, and their mixtures. These modified alloys have an electron density no greater than 8.00 and exhibit marked increases at elevated temperature in ductility and other mechanical properties over previously known ordered alloys.

  16. Models of cuspy triaxial stellar systems - IV. Rotating systems

    NASA Astrophysics Data System (ADS)

    Carpintero, D. D.; Muzzio, J. C.

    2016-06-01

    We built two self-consistent models of triaxial, cuspy, rotating stellar systems adding rotation to non-rotating models presented in previous papers of this series. The final angular velocity of the material is not constant and varies with the distance to the centre and with the height over the equator of the systems, but the figure rotation is very uniform in both cases. Even though the addition of rotation to the models modifies their original semi-axes ratios, the final rotating models are considerably flattened and triaxial. An analysis of the orbital content of the models shows that about two-thirds of their orbits are chaotic yet the models are very stable over intervals of the order of one Hubble time. The bulk of regular orbits are short-axis tubes, while long-axis tubes are replaced by tubes whose axes lie on the short-long axes plane, but do not coincide with the major axis. Other types of regular orbits that do not appear in non-rotating systems, like horseshoes and orbits that cross themselves, are also found in the present models. Finally, our frequency maps show empty regions where studies of orbits on fixed potentials found orbits, a likely consequence of the self-consistency of our models that excludes them.

  17. Magnetic properties of the semifluorinated and semihydrogenated 2D sheets of group-IV and III-V binary compounds

    NASA Astrophysics Data System (ADS)

    Ma, Yandong; Dai, Ying; Guo, Meng; Niu, Chengwang; Yu, Lin; Huang, Baibiao

    2011-06-01

    By performing first-principles calculations, the intriguing electronic and magnetic properties of the semidecorated sheets of group-IV and III-V binary compounds are investigated. Our results indicate that the semifluorinated and semihydrogenated ab ( ab = SiC, GeC, SnC, BN, AlN, and GaN) sheets exhibit diverse electronic and magnetic properties. Accordingly, the electronic and magnetic properties of the semidecorated sheets can be precisely modulated by controlling the adsorbed atoms on the a sites. Further, the preference of ferromagnetic or antiferromagnetic coupling can be attributed to the combined effects of both through-bond spin polarization and p- p direct interaction for the semidecorated ab sheets.

  18. Mössbauer parameters of Fe-related defects in group-IV semiconductors: First principles calculations

    NASA Astrophysics Data System (ADS)

    Wright, E.; Coutinho, J.; Öberg, S.; Torres, V. J. B.

    2016-05-01

    We employ a combination of pseudopotential and all-electron density functional calculations, to relate the structure of defects in supercells to the isomer shifts and quadrupole splittings observed in Mössbauer spectroscopy experiments. The methodology is comprehensively reviewed and applied to the technologically relevant case of iron-related defects in silicon, and to other group-IV hosts to a lesser degree. Investigated defects include interstitial and substitutional iron, iron-boron pairs, iron-vacancy, and iron-divacancy. We find that, in general, agreement between the calculations and Mössbauer data is within a 10% error bar. Nonetheless, we show that the methodology can be used to make accurate assignments, including to separate peaks of similar defects in slightly different environments.

  19. Terahertz emission upon the band-to-band excitation of Group-IV semiconductors at room temperature

    SciTech Connect

    Zakhar’in, A. O.; Bobylev, A. V.; Egorov, S. V.; Andrianov, A. V.

    2015-03-15

    Terahertz emission upon the band-to-band excitation of Group-IV semiconductors (Si:B and Ge:Ga) at room temperature by a semiconductor laser emitting in the visible range (660 nm) is observed and investigated. It is established that, as the crystal temperature is elevated above room temperature, the emission intensity increases considerably, while the emission spectrum shifts to higher frequencies. The terahertz-emission spectra of germanium and silicon are quite similar to each other. The pump-intensity dependence of the terahertz-emission intensity is nearly linear. The above features make it possible to attribute the observed terahertz emission to the effect of crystal heating by absorbed pump radiation.

  20. Planetary nebulae as standard candles. IV - A test in the Leo I group

    NASA Astrophysics Data System (ADS)

    Ciardullo, Robin; Jacoby, George H.; Ford, Holland C.

    1989-09-01

    In this paper, PN are used to determine accurate distances to three galaxies in the Leo I group - The E0 giant elliptical NGC 3379, its optical companion, the SB0 spiral NGC 3384, and the smaller E6 elliptical NGC 3377. In all three galaxies, the luminosity-specific PN number densities are roughly the same, and the derived stellar death rates are in remarkable agreement with the predictions of stellar evolution theory. It is shown that the shape of the forbidden O III 5007 A PN luminosity function is the same in each galaxy and indistinguishable from that observed in M31 and M81. It is concluded that the PN luminosity function is an excellent standard candle for early-type galaxies.

  1. Planetary nebulae as standard candles. IV - A test in the Leo I group

    NASA Technical Reports Server (NTRS)

    Ciardullo, Robin; Jacoby, George H.; Ford, Holland C.

    1989-01-01

    In this paper, PN are used to determine accurate distances to three galaxies in the Leo I group - The E0 giant elliptical NGC 3379, its optical companion, the SB0 spiral NGC 3384, and the smaller E6 elliptical NGC 3377. In all three galaxies, the luminosity-specific PN number densities are roughly the same, and the derived stellar death rates are in remarkable agreement with the predictions of stellar evolution theory. It is shown that the shape of the forbidden O III 5007 A PN luminosity function is the same in each galaxy and indistinguishable from that observed in M31 and M81. It is concluded that the PN luminosity function is an excellent standard candle for early-type galaxies.

  2. Synthesis, structural characterization and antimicrobial activities of diorganotin(IV) complexes with azo-imino carboxylic acid ligand: Crystal structure and topological study of a doubly phenoxide-bridged dimeric dimethyltin(IV) complex appended with free carboxylic acid groups

    NASA Astrophysics Data System (ADS)

    Roy, Manojit; Roy, Subhadip; Devi, N. Manglembi; Singh, Ch. Brajakishor; Singh, Keisham Surjit

    2016-09-01

    Diorganotin(IV) complexes appended with free carboxylic acids were synthesized by reacting diorganotin(IV) dichlorides [R2SnCl2; R = Me (1), Bu (2) and Ph (3)] with an azo-imino carboxylic acid ligand i.e. 2-{4-hydroxy-3-[(2-hydroxyphenylimino)methyl]phenylazo}benzoic acid in presence of triethylamine. The complexes were characterized by elemental analysis, IR and multinuclear NMR (1H, 13C and 119Sn) spectroscopy. The structure of 1 in solid state has been determined by X-ray crystallography. Crystal structure of 1 reveals that the compound crystallizes in monoclinic space group P21/c and is a dimeric dimethyltin(IV) complex appended with free carboxylic acid groups. In the structure of 1, the Sn(IV) atoms are hexacoordinated and have a distorted octahedral coordination geometry in which two phenoxy oxygen atoms and the azomethine nitrogen atom of the ligand coordinate to each tin atom. One of the phenoxy oxygen atom bridges the two tin centers resulting in a planar Sn2O2 core. Topological analysis is used for the description of molecular packing in 1. Tin NMR spectroscopy study indicates that the complexes have five coordinate geometry around tin atom in solution state. Since the complexes have free carboxylic acids, these compounds could be further used as potential metallo-ligands for the synthesis of other complexes. The synthesized diorganotin(IV) complexes were also screened for their antimicrobial activities and compound 2 showed effective antimicrobial activities.

  3. "Group IV Nanomembranes, Nanoribbons, and Quantum Dots: Processing, Characterization, and Novel Devices"

    SciTech Connect

    liu, feng

    2014-08-28

    This theoretical project has been carried out in close interaction with the experimental project at UW-Madison under the same title led by PI Max Lagally and co-PI Mark Eriksson. Extensive computational studies have been performed to address a broad range of topics from atomic structure, stability, mechanical property, to electronic structure, optoelectronic and transport properties of various nanoarchitectures in the context of Si and other solid nanomembranes. These have been done by using combinations of different theoretical and computational approaches, ranging from first-principles calculations and molecular dynamics (MD) simulations to finite-element (FE) analyses and continuum modeling.

  4. Homogeneous Ziegler-Natta polymerization of functionalized monomers catalyzed by cationic group IV metallocenes

    SciTech Connect

    Kesti, M.R.; Coates, G.W.; Waymouth, R.M.

    1992-11-18

    Ziegler-Natta catalysts are remarkable in their ability to polymerize {alpha}-olefins to high molecular weight, stereoregular polyolefins. One of the major limitations of conventional Ziegler-Natta catalysts is their intolerance to Lewis bases; catalysts based on titanium halides and alkylaluminum cocatalysts are poisoned by most types of monomers containing ethers, esters, amines, and carboxylic acids. The absence of functionality in hydrocarbon polymers seriously affects their adhesive properties, affinity for dyes, permeability, and compatibility with more polar polymers. Previous attempts to polymerize sterically hindered amines, esters and amides, alkyl halides, and carboxylic acids using catalysts derived from TiCl{sub 3} and AlR{sub 3-n}Cl{sub n} have achieved limited success due to the severe loss of catalytic activity in the presence of these monomers. This work reports that cationic, group four metallocenes are active catalysts for the homo-polymerization of {alpha}-olefins containing silyl-protected alcohols and tertiary amines. Employing different monomers and conditions, a table shows the starting monomer, reaction time and temperature, and spectroscopic analysis of the end products. A major advanatage of these metallocene-based catalysts is that the ligand system can be modified to proved the optimal combination of catalystic activity, stereospecificity, and tolerance to functionality. 32 refs., 1 tab.

  5. Leading Generative Groups: A Conceptual Model

    ERIC Educational Resources Information Center

    London, Manuel; Sobel-Lojeski, Karen A.; Reilly, Richard R.

    2012-01-01

    This article presents a conceptual model of leadership in generative groups. Generative groups have diverse team members who are expected to develop innovative solutions to complex, unstructured problems. The challenge for leaders of generative groups is to balance (a) establishing shared goals with recognizing members' vested interests, (b)…

  6. Joint Individual-Group Modeling for Tracking.

    PubMed

    Bazzani, Loris; Zanotto, Matteo; Cristani, Marco; Murino, Vittorio

    2015-04-01

    We present a novel probabilistic framework that jointly models individuals and groups for tracking. Managing groups is challenging, primarily because of their nonlinear dynamics and complex layout which lead to repeated splitting and merging events. The proposed approach assumes a tight relation of mutual support between the modeling of individuals and groups, promoting the idea that groups are better modeled if individuals are considered and vice versa. This concept is translated in a mathematical model using a decentralized particle filtering framework which deals with a joint individual-group state space. The model factorizes the joint space into two dependent subspaces, where individuals and groups share the knowledge of the joint individual-group distribution. The assignment of people to the different groups (and thus group initialization, split and merge) is implemented by two alternative strategies: using classifiers trained beforehand on statistics of group configurations, and through online learning of a Dirichlet process mixture model, assuming that no training data is available before tracking. These strategies lead to two different methods that can be used on top of any person detector (simulated using the ground truth in our experiments). We provide convincing results on two recent challenging tracking benchmarks. PMID:26353291

  7. Evolutionary models of in-group favoritism

    PubMed Central

    Fu, Feng

    2015-01-01

    In-group favoritism is the tendency for individuals to cooperate with in-group members more strongly than with out-group members. Similar concepts have been described across different domains, including in-group bias, tag-based cooperation, parochial altruism, and ethnocentrism. Both humans and other animals show this behavior. Here, we review evolutionary mechanisms for explaining this phenomenon by covering recently developed mathematical models. In fact, in-group favoritism is not easily realized on its own in theory, although it can evolve under some conditions. We also discuss the implications of these modeling results in future empirical and theoretical research. PMID:25926978

  8. Evolutionary models of in-group favoritism.

    PubMed

    Masuda, Naoki; Fu, Feng

    2015-01-01

    In-group favoritism is the tendency for individuals to cooperate with in-group members more strongly than with out-group members. Similar concepts have been described across different domains, including in-group bias, tag-based cooperation, parochial altruism, and ethnocentrism. Both humans and other animals show this behavior. Here, we review evolutionary mechanisms for explaining this phenomenon by covering recently developed mathematical models. In fact, in-group favoritism is not easily realized on its own in theory, although it can evolve under some conditions. We also discuss the implications of these modeling results in future empirical and theoretical research. PMID:25926978

  9. Abundance and Clustering of C IV Absorption Systems in the SCDM, LCDM, and CHDM Models

    NASA Astrophysics Data System (ADS)

    Bi, Hongguang; Fang, Li-Zhi

    1996-08-01

    We have developed a method for calculating the two-point correlation function of nonlinearly evolved mass and collapsed halos in the Press- Schechter formalism. The nonlinear gravitational interaction is treated as the sum of various individual spherical top-hat clustering. Because no collapsed halo of mass M can exist in initial regions (or top-hat spheres) of mass less than M, the bias that massive halos have stronger correlation than the background mass can be naturally introduced. We apply this method to derive constraints on popular dark-matter models from the spatial number density and the correlation function of C IV absorption systems in QSO spectra. Considering C IV systems should be hosted by collapsed halos, one can obtain an upper limit to the threshold mass of the collapsed halos by requiring their number density to be larger than that of observed C IV systems. On the other hand, in order to explain the observed clustering of C IV systems, a lower limit to the threshold mass will be set for the hosting halos. We found that the standard cold dark matter (SCDM) model and the low-density flat universe with a cosmological constant {LAMBDA}_0_ (LCDM) are consistent with the abundance and clustering of C IV systems. However, the two cold- plus-hot dark matter models (CHDMs) with the cosmological parameters ({OMEGA}_c_+ {OMEGA}_b_)/{OMEGA}_h_ = 0.7/0.3 and 0.8/0.2, respectively, have difficulty passing the two tests simultaneously. In these models, in order to have enough collapsed halos to host C IV systems, the threshold mass of the halos cannot be greater than 10^11^ M_sun_. But in order to agree with the two-point correlation function on the scales of {DELTA}_v_ ~ 300-1000 km s^-1^, the threshold mass should be larger than 10^12^ M_sun_.

  10. A Model of Small Group Facilitator Competencies

    ERIC Educational Resources Information Center

    Kolb, Judith A.; Jin, Sungmi; Song, Ji Hoon

    2008-01-01

    This study used small group theory, quantitative and qualitative data collected from experienced practicing facilitators at three points of time, and a building block process of collection, analysis, further collection, and consolidation to develop a model of small group facilitator competencies. The proposed model has five components:…

  11. Group Recommender Systems: Combining Individual Models

    NASA Astrophysics Data System (ADS)

    Masthoff, Judith

    This chapter shows how a system can recommend to a group of users by aggregating information from individual user models and modelling the users affective state. It summarizes results from previous research in this area. It also shows how group recommendation techniques can be applied when recommending to individuals, in particular for solving the cold-start problem and dealing with multiple criteria.

  12. Comparing Personality Disorder Models: Cross-Method Assessment of the FFM and DSM-IV-TR

    PubMed Central

    Samuel, Douglas B.; Widiger, Thomas A.

    2010-01-01

    The current edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR; American Psychiatric Association, 2000) defines personality disorders as categorical entities that are distinct from each other and from normal personality traits. However, many scientists now believe that personality disorders are best conceptualized using a dimensional model of traits that span normal and abnormal personality, such as the Five-Factor Model (FFM). However, if the FFM or any dimensional model is to be considered as a credible alternative to the current model, it must first demonstrate an increment in the validity of the assessment offered within a clinical setting. Thus, the current study extended previous research by comparing the convergent and discriminant validity of the current DSM-IV-TR model to the FFM across four assessment methodologies. Eighty-eight individuals receiving ongoing psychotherapy were assessed for the FFM and the DSM-IV-TR personality disorders using self-report, informant report, structured interview, and therapist ratings. The results indicated that the FFM had an appreciable advantage over the DSM-IV-TR in terms of discriminant validity and, at the domain level, convergent validity. Implications of the findings and directions for future research are discussed. PMID:21158596

  13. Tidal Downsizing model - IV. Destructive feedback in planets

    NASA Astrophysics Data System (ADS)

    Nayakshin, Sergei

    2016-09-01

    The role of negative feedback from a massive solid core on its massive gas envelope in the Tidal Downsizing scenario of planet formation is investigated via one-dimensional planet evolution models followed by population synthesis calculations. It is shown that cores more massive than ˜10 M⊕ release enough energy to reverse contraction of their parent gas envelopes, culminating in their destruction. This process may help to explain why observed gas giant planets are so rare, why massive cores are so ubiquitous, and why there is a sharp rollover in the core mass function above ˜20 M⊕. Additionally, the short time-scales with which these massive cores are assembled in TD may help explain formation route of Uranus, Neptune and the suspected HL Tau planets. Given the negative role of cores in assembly of gas giants in the model, an antimony is found between massive cores and gas giants: cores in survived gas giant planets are on average less massive than cores free of massive envelopes. In rare circumstances when core feedback self-regulates, extremely metal-rich gas giants, such as CoRoT-20b, a gas giant made of heavy elements by up to ˜50 per cent, can be made.

  14. A Global Magnetic Topology Model for Magnetic Clouds. IV.

    NASA Astrophysics Data System (ADS)

    Hidalgo, M. A.

    2016-05-01

    In the first paper of this series, we introduced a global topology model for the study of magnetic clouds (MCs), fitting it to the experimental magnetic field components and obtaining, for example, the orientation of the axis of the MCs in the interplanetary medium. In the third paper, we extended the model to include theoretical hydrostatic plasma pressure, also incorporating it in the fitting procedure. The present work is complementary to the previous ones, now incorporating the proton current density as deduced from the continuity equation. In particular, we are interested in the component of the proton current density parallel to the magnetic field lines of the MC, {\\boldsymbol{j}} \\parallel , because the perpendicular component is expected to have information similar to the plasma pressure. Under all of these conditions, our fitting procedure now involves simultaneous analysis of the three components of the magnetic field, the trace of the plasma pressure, and the parallel proton current density. This provides us with more information about the physical mechanisms taking place inside MCs, thus helping us to understand the propagation and evolution of these structures in the interplanetary medium.

  15. Testing Structural Models of DSM-IV Symptoms of Common Forms of Child and Adolescent Psychopathology

    ERIC Educational Resources Information Center

    Lahey, Benjamin B.; Rathouz, Paul J.; Van Hulle, Carol; Urbano, Richard C.; Krueger, Robert F.; Applegate, Brooks; Garriock, Holly A.; Chapman, Derek A.; Waldman, Irwin D.

    2008-01-01

    Confirmatory factor analyses were conducted of "Diagnostic and Statistical Manual of Mental Disorders", Fourth Edition (DSM-IV) symptoms of common mental disorders derived from structured interviews of a representative sample of 4,049 twin children and adolescents and their adult caretakers. A dimensional model based on the assignment of symptoms…

  16. Diverse anisotropy of phonon transport in two-dimensional group IV-VI compounds: A comparative study

    NASA Astrophysics Data System (ADS)

    Qin, Guangzhao; Qin, Zhenzhen; Fang, Wu-Zhang; Zhang, Li-Chuan; Yue, Sheng-Ying; Yan, Qing-Bo; Hu, Ming; Su, Gang

    2016-05-01

    New classes of two-dimensional (2D) materials beyond graphene, including layered and non-layered, and their heterostructures, are currently attracting increasing interest due to their promising applications in nanoelectronics, optoelectronics and clean energy, where thermal transport is a fundamental physical parameter. In this paper, we systematically investigated the phonon transport properties of the 2D orthorhombic group IV-VI compounds of GeS, GeSe, SnS and SnSe by solving the Boltzmann transport equation (BTE) based on first-principles calculations. Despite their similar puckered (hinge-like) structure along the armchair direction as phosphorene, the four monolayer compounds possess diverse anisotropic properties in many aspects, such as phonon group velocity, Young's modulus and lattice thermal conductivity (κ), etc. Especially, the κ along the zigzag and armchair directions of monolayer GeS shows the strongest anisotropy while monolayer SnS and SnSe show almost isotropy in phonon transport. The origin of the diverse anisotropy is fully studied and the underlying mechanism is discussed in details. With limited size, the κ could be effectively lowered, and the anisotropy could be effectively modulated by nanostructuring, which would extend the applications to nanoscale thermoelectrics and thermal management. Our study offers fundamental understanding of the anisotropic phonon transport properties of 2D materials, and would be of significance for further study, modulation and applications in emerging technologies.

  17. Diverse anisotropy of phonon transport in two-dimensional group IV-VI compounds: A comparative study.

    PubMed

    Qin, Guangzhao; Qin, Zhenzhen; Fang, Wu-Zhang; Zhang, Li-Chuan; Yue, Sheng-Ying; Yan, Qing-Bo; Hu, Ming; Su, Gang

    2016-06-01

    New classes of two-dimensional (2D) materials beyond graphene, including layered and non-layered, and their heterostructures, are currently attracting increasing interest due to their promising applications in nanoelectronics, optoelectronics and clean energy, where thermal transport is a fundamental physical parameter. In this paper, we systematically investigated the phonon transport properties of the 2D orthorhombic group IV-VI compounds of GeS, GeSe, SnS and SnSe by solving the Boltzmann transport equation (BTE) based on first-principles calculations. Despite their similar puckered (hinge-like) structure along the armchair direction as phosphorene, the four monolayer compounds possess diverse anisotropic properties in many aspects, such as phonon group velocity, Young's modulus and lattice thermal conductivity (κ), etc. Especially, the κ along the zigzag and armchair directions of monolayer GeS shows the strongest anisotropy while monolayer SnS and SnSe show almost isotropy in phonon transport. The origin of the diverse anisotropy is fully studied and the underlying mechanism is discussed in details. With limited size, the κ could be effectively lowered, and the anisotropy could be effectively modulated by nanostructuring, which would extend the applications to nanoscale thermoelectrics and thermal management. Our study offers fundamental understanding of the anisotropic phonon transport properties of 2D materials, and would be of significance for further study, modulation and applications in emerging technologies. PMID:27189263

  18. Education as Experimentation: A Planned Variation Model. Volume IV-E. Supplementary Analyses: Reanalysis of Selected Data Sets. Volume IV-F. Supplementary Analyses: Appendix.

    ERIC Educational Resources Information Center

    Proper, Elizabeth C.; And Others

    This segment of the national evaluation study of the Follow Through Planned Variation Model discusses findings of analyses of achievement test data which have been adjusted to take into consideration the preschool experience of children in three Follow Through cohorts. These analyses serve as a supplement to analyses presented in Volume IV-A of…

  19. Approximate Single-Diode Photovoltaic Model for Efficient I-V Characteristics Estimation

    PubMed Central

    Ting, T. O.; Zhang, Nan; Guan, Sheng-Uei; Wong, Prudence W. H.

    2013-01-01

    Precise photovoltaic (PV) behavior models are normally described by nonlinear analytical equations. To solve such equations, it is necessary to use iterative procedures. Aiming to make the computation easier, this paper proposes an approximate single-diode PV model that enables high-speed predictions for the electrical characteristics of commercial PV modules. Based on the experimental data, statistical analysis is conducted to validate the approximate model. Simulation results show that the calculated current-voltage (I-V) characteristics fit the measured data with high accuracy. Furthermore, compared with the existing modeling methods, the proposed model reduces the simulation time by approximately 30% in this work. PMID:24298205

  20. Does estradiol have an impact on the dipeptidyl peptidase IV enzyme activity of the Prevotella intermedia group bacteria?

    PubMed

    Fteita, Dareen; Könönen, Eija; Gürsoy, Mervi; Söderling, Eva; Gürsoy, Ulvi Kahraman

    2015-12-01

    Initiation and development of pregnancy-associated gingivitis is seemingly related to the microbial shift towards specific gram-negative anaerobes in subgingival biofilms. It is known that Prevotella intermedia sensu lato is able to use estradiol as an alternative source of growth instead of vitamin K. The aim of the present study was to investigate the impact of estradiol on the bacterial dipeptidyl peptidase IV (DPPIV) enzyme activity in vitro as a virulent factor of the Prevotella intermedia group bacteria, namely P. intermedia, Prevotella nigrescens, Prevotella pallens, and Prevotella aurantiaca. In all experiments, 2 strains of each Prevotella species were used. Bacteria were incubated with the concentrations of 0, 30, 90, and 120 nmol/L of estradiol and were allowed to build biofilms at an air-solid interface. DPPIV activities of biofilms were measured kinetically during 20 min using a fluorometric assay. The enzyme activity was later related to the amount of protein produced by the same biofilm, reflecting the biofilm mass. Estradiol significantly increased DPPIV activities of the 8 Prevotella strains in a strain- and dose-dependent manner. In conclusion, our in vitro experiments indicate that estradiol regulates the DPPIV enzyme activity of P. intermedia, P. nigrescens, P. pallens, and P. aurantiaca strains differently. Our results may, at least partly, explain the role of estradiol to elicit a virulent state which contributes to the pathogenesis of pregnancy-related gingivitis. PMID:26386229

  1. Genome-Wide Association Study of Ureide Concentration in Diverse Maturity Group IV Soybean [Glycine max (L.) Merr.] Accessions

    PubMed Central

    Ray, Jeffery D.; Dhanapal, Arun Prabhu; Singh, Shardendu K.; Hoyos-Villegas, Valerio; Smith, James R.; Purcell, Larry C.; King, C. Andy; Boykin, Debbie; Cregan, Perry B.; Song, Qijian; Fritschi, Felix B.

    2015-01-01

    Ureides are the N-rich products of N-fixation that are transported from soybean nodules to the shoot. Ureides are known to accumulate in leaves in response to water-deficit stress, and this has been used to identify genotypes with reduced N-fixation sensitivity to drought. Our objectives in this research were to determine shoot ureide concentrations in 374 Maturity Group IV soybean accessions and to identify genomic regions associated with shoot ureide concentration. The accessions were grown at two locations (Columbia, MO, and Stuttgart, AR) in 2 yr (2009 and 2010) and characterized for ureide concentration at beginning flowering to full bloom. Average shoot ureide concentrations across all four environments (two locations and two years) and 374 accessions ranged from 12.4 to 33.1 µmol g−1 and were comparable to previously reported values. SNP–ureide associations within and across the four environments were assessed using 33,957 SNPs with a MAF ≥0.03. In total, 53 putative loci on 18 chromosomes were identified as associated with ureide concentration. Two of the putative loci were located near previously reported QTL associated with ureide concentration and 30 loci were located near genes associated with ureide metabolism. The remaining putative loci were not near chromosomal regions previously associated with shoot ureide concentration and may mark new genes involved in ureide metabolism. Ultimately, confirmation of these putative loci will provide new sources of variation for use in soybean breeding programs. PMID:26374596

  2. Validation of nuclear criticality safety software and 27 energy group ENDF/B-IV cross sections. Revision 1

    SciTech Connect

    Lee, B.L. Jr.; D`Aquila, D.M.

    1996-01-01

    The original validation report, POEF-T-3636, was documented in August 1994. The document was based on calculations that were executed during June through August 1992. The statistical analyses in Appendix C and Appendix D were completed in October 1993. This revision is written to clarify the margin of safety being used at Portsmouth for nuclear criticality safety calculations. This validation gives Portsmouth NCS personnel a basis for performing computerized KENO V.a calculations using the Lockheed Martin Nuclear Criticality Safety Software. The first portion of the document outlines basic information in regard to validation of NCSS using ENDF/B-IV 27-group cross sections on the IBM3090 at ORNL. A basic discussion of the NCSS system is provided, some discussion on the validation database and validation in general. Then follows a detailed description of the statistical analysis which was applied. The results of this validation indicate that the NCSS software may be used with confidence for criticality calculations at the Portsmouth Gaseous Diffusion Plant. For calculations of Portsmouth systems using the specified codes and systems covered by this validation, a maximum k{sub eff} including 2{sigma} of 0.9605 or lower shall be considered as subcritical to ensure a calculational margin of safety of 0.02. The validation of NCSS on the IBM 3090 at ORNL was extended to include NCSS on the IBM 3090 at K-25.

  3. The symmetry group of the CAFFE model

    NASA Astrophysics Data System (ADS)

    Faria, Sérgio H.

    A new ice-sheet flow model called CAFFE (Continuum-mechanical Anisotropic Flow model based on an anisotropic Flow Enhancement factor) has recently become a source of considerable controversy within the glaciological community. Its main proponents (Placidi, Greve and Seddik) defend the thesis that this model can describe the effect of induced anisotropy on ice-sheet flow, while others assert that the CAFFE model is merely an isotropic model. Here I resolve this dispute by rigorously deriving the symmetry group of the CAFFE model.

  4. Generation of a novel mouse model that recapitulates early and adult onset glycogenosis type IV.

    PubMed

    Akman, H Orhan; Sheiko, Tatiana; Tay, Stacey K H; Finegold, Milton J; Dimauro, Salvatore; Craigen, William J

    2011-11-15

    Glycogen storage disease type IV (GSD IV) is a rare autosomal recessive disorder caused by deficiency of the glycogen branching enzyme (GBE). The diagnostic feature of the disease is the accumulation of a poorly branched form of glycogen known as polyglucosan (PG). The disease is clinically heterogeneous, with variable tissue involvement and age of disease onset. Absence of enzyme activity is lethal in utero or in infancy affecting primarily muscle and liver. However, residual enzyme activity (5-20%) leads to juvenile or adult onset of a disorder that primarily affects muscle as well as central and peripheral nervous system. Here, we describe two mouse models of GSD IV that reflect this spectrum of disease. Homologous recombination was used to insert flippase recognition target recombination sites around exon 7 of the Gbe1 gene and a phosphoglycerate kinase-Neomycin cassette within intron 7, leading to a reduced synthesis of GBE. Mice bearing this mutation (Gbe1(neo/neo)) exhibit a phenotype similar to juvenile onset GSD IV, with wide spread accumulation of PG. Meanwhile, FLPe-mediated homozygous deletion of exon 7 completely eliminated GBE activity (Gbe1(-/-)), leading to a phenotype of lethal early onset GSD IV, with significant in utero accumulation of PG. Adult mice with residual GBE exhibit progressive neuromuscular dysfunction and die prematurely. Differently from muscle, PG in liver is a degradable source of glucose and readily depleted by fasting, emphasizing that there are structural and regulatory differences in glycogen metabolism among tissues. Both mouse models recapitulate typical histological and physiological features of two human variants of branching enzyme deficiency. PMID:21856731

  5. Group Development and Situational Leadership: A Model for Managing Groups.

    ERIC Educational Resources Information Center

    Carew, Donald K.; And Others

    1986-01-01

    An integration of the concepts of situational leadership with what is known about group development and functioning of work groups is discussed as a tool in helping managers, trainers, and group members understand group development and determine the appropriate leader behaviors to use in various situations to build unified, cohesive, and…

  6. Helping General Physical Educators and Adapted Physical Educators Address the Office of Civil Rights Dear Colleague Guidance Letter: Part IV--Sport Groups

    ERIC Educational Resources Information Center

    Lieberman, Lauren; Lucas, Mark; Jones, Jeffery; Humphreys, Dan; Cody, Ann; Vaughn, Bev; Storms, Tommie

    2013-01-01

    "Helping General Physical Educators and Adapted Physical Educators Address the Office of Civil Rights Dear Colleague Guidance Letter: Part IV--Sport Groups" provides the the following articles: (1) "Sport Programming Offered by Camp Abilities and the United States Association for Blind Athletes" (Lauren Lieberman and Mark…

  7. Mixed-ligand complexes of some transition metals in groups IV-VI of the periodic table with trihydroxyfluorones and diantipyrylmethane

    SciTech Connect

    Ganago, L.I.

    1986-03-20

    The purpose of this work was to examine the changes in the principal physicochemical characteristics of mixed-ligand complex compounds of the transition metals in groups IV-VI with one of the sensitive trihydroxyfluorones, viz., o-nitrophenylfluorone, and a base of the pyrazolone series, viz., diantipyrylmethane, and to reveal the possibilities of their analytical application.

  8. The Development and Evaluation of Training Methods for Group IV Personnel. 1. Orientation and Implementation of the Training Methods Development School (TMDS).

    ERIC Educational Resources Information Center

    Steinemann, John H.

    The investigation is part of continuing Navy research on the Trainability of Group IV (low ability) personnel intended to maximize the utilization and integration of marginal personnel in the fleet. An experimental Training Methods Development School (TMDS) was initiated to provide an experimental training program, with research controls, for…

  9. Multiscale Modeling of the Deformation of Advanced Ferritic Steels for Generation IV Nuclear Energy

    SciTech Connect

    Nasr M. Ghoniem; Nick Kioussis

    2009-04-18

    The objective of this project is to use the multi-scale modeling of materials (MMM) approach to develop an improved understanding of the effects of neutron irradiation on the mechanical properties of high-temperature structural materials that are being developed or proposed for Gen IV applications. In particular, the research focuses on advanced ferritic/ martensitic steels to enable operation up to 650-700°C, compared to the current 550°C limit on high-temperature steels.

  10. Introduction of LL-IV Distributed Hydrological Model and Applications in DMIP-II

    NASA Astrophysics Data System (ADS)

    Li, L.; Zhang, H.; Yang, M.; Nicholson, A.

    2011-12-01

    Watershed hydrological models are an important tool for understanding hydrological processes on the earth, and they have been developed from empirical models to stochastic models, to lumped conceptual models, and finally to distributed conceptual models. Among them, the distributed hydrological model with physical bases is a great milestone in the development of hydrological models. The Hydrology Laboratory of the US National Weather Service paid high attention to the applications of distributed hydrological models. This department has proposed the Distributed Model Intercomparison Projects (DMIP-I and DMIP-II) since 2001, which made a major contribution to the development of distributed hydrological models. This paper introduces the development of the LL (Lan Li) distributed hydrological model, which produced satisfactory results in both DMIP-I and DIMP-II. LL-IV is the latest version of the LL distributed hydrological model and its basic equations and structures are detailed in this paper. LL-IV, for the first time, derives convection-diffusion equations for the interflow (in both saturated and unsaturated conditions) and underground flow. In addition, this model describes soil humidity, evaporation from soil, infiltration, overland flow, stream flow etc. by convection-diffusion equations. The advantages of using convection-diffusion equations in LL-IV to represent water cycle process for either the vertical change in a single grid or water interchange between grids are as follows: (1) Convection-diffusion equations require fewer variables compared with St. Venant equations. Whole and continuous data of the velocity and water stage, for example, are not usually available for most watersheds, which limits the application of distributed hydrological model. For LL-IV, however, these data are not always necessary when simulating. (2) LL-IV improves computational efficiency and requires less memory space by using convection-diffusion equations which focus mainly on

  11. The relationship between the Five-Factor Model and latent DSM-IV personality disorder dimensions

    PubMed Central

    Nestadt, Gerald; Costa, Paul T.; Hsu, Fang-Chi; Samuels, Jack; Bienvenu, O. Joseph; Eaton, William W.

    2007-01-01

    This study compared the latent structure of the DSM-IV personality disorders to the Five-Factor Model (FFM) of general personality dimensions. The subjects in the study were 742 community-residing individuals who participated in the Hopkins Epidemiology of Personality Disorder Study. DSM-IV personality disorder traits were assessed by psychologists using the International Personality Disorder Examination, and personality disorder dimensions were derived previously using dichotomous factor analysis. The NEO-PI(R), a measure of the FFM, was administered to all subjects. The relationship between the two sets of personality-related constructs was examined using a construct validity framework and also using Pearson’s correlation coefficients, multiple linear regression models, and spline regression models. The five personality disorder factors each exhibited small to moderate correlations with several NEO dimensions; together, the NEO domain and facet scores “explained” a fifth to a third of the variance in personality disorder dimensions. Examples of non-linear relationships between the personality dimensions were identified. There is a modest correspondence between the personality disorder dimensions and FFM traits, and the traits of FFM only partially explain the variance of the personality disorders. Dimensional measures of general personality may be a suitable alternative to the DSM-IV. Whether additional maladaptive traits would better define the domain of personality disorders remains an important objective for future research. PMID:18063048

  12. 40 CFR Appendix IV to Part 600 - Sample Fuel Economy Labels for 2008 Through 2012 Model Year Vehicles

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Sample Fuel Economy Labels for 2008 Through 2012 Model Year Vehicles IV Appendix IV to Part 600 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY AND GREENHOUSE GAS EXHAUST EMISSIONS OF...

  13. Bayesian Model Selection for Group Studies

    PubMed Central

    Stephan, Klaas Enno; Penny, Will D.; Daunizeau, Jean; Moran, Rosalyn J.; Friston, Karl J.

    2009-01-01

    Bayesian model selection (BMS) is a powerful method for determining the most likely among a set of competing hypotheses about the mechanisms that generated observed data. BMS has recently found widespread application in neuroimaging, particularly in the context of dynamic causal modelling (DCM). However, so far, combining BMS results from several subjects has relied on simple (fixed effects) metrics, e.g. the group Bayes factor (GBF), that do not account for group heterogeneity or outliers. In this paper, we compare the GBF with two random effects methods for BMS at the between-subject or group level. These methods provide inference on model-space using a classical and Bayesian perspective respectively. First, a classical (frequentist) approach uses the log model evidence as a subject-specific summary statistic. This enables one to use analysis of variance to test for differences in log-evidences over models, relative to inter-subject differences. We then consider the same problem in Bayesian terms and describe a novel hierarchical model, which is optimised to furnish a probability density on the models themselves. This new variational Bayes method rests on treating the model as a random variable and estimating the parameters of a Dirichlet distribution which describes the probabilities for all models considered. These probabilities then define a multinomial distribution over model space, allowing one to compute how likely it is that a specific model generated the data of a randomly chosen subject as well as the exceedance probability of one model being more likely than any other model. Using empirical and synthetic data, we show that optimising a conditional density of the model probabilities, given the log-evidences for each model over subjects, is more informative and appropriate than both the GBF and frequentist tests of the log-evidences. In particular, we found that the hierarchical Bayesian approach is considerably more robust than either of the other

  14. Modeling Success in FLOSS Project Groups

    SciTech Connect

    Beaver, Justin M; Cui, Xiaohui; ST Charles, Jesse Lee; Potok, Thomas E

    2009-01-01

    A significant challenge in software engineering is accurately modeling projects in order to correctly forecast success or failure. The primary difficulty is that software development efforts are complex in terms of both the technical and social aspects of the engineering environment. This is compounded by the lack of real data that captures both the measures of success in performing a process, and the measures that reflect a group s social dynamics. This research focuses on the development of a model for predicting software project success that leverages the wealth of available open source project data in order to accurately model the behavior of those software engineering groups. Our model accounts for both the technical elements of software engineering as well as the social elements that drive the decisions of individual developers. We use agent-based simulations to represent the complexity of the group interactions, and base the behavior of the agents on the real software engineering data acquired. For four of the five project success measures, our results indicate that the developed model represents the underlying data well and provides accurate predictions of open source project success indicators.

  15. Activation of group IV cytosolic phospholipase A2 in human eosinophils by phosphoinositide 3-kinase through a mitogen-activated protein kinase-independent pathway.

    PubMed

    Myou, Shigeharu; Leff, Alan R; Myo, Saori; Boetticher, Evan; Meliton, Angelo Y; Lambertino, Anissa T; Liu, Jie; Xu, Chang; Munoz, Nilda M; Zhu, Xiangdong

    2003-10-15

    Activation of group IV cytosolic phospholipase A(2) (gIV-PLA(2)) is the essential first step in the synthesis of inflammatory eicosanoids and in integrin-mediated adhesion of leukocytes. Prior investigations have demonstrated that phosphorylation of gIV-PLA(2) results from activation of at least two isoforms of mitogen-activated protein kinase (MAPK). We investigated the potential role of phosphoinositide 3-kinase (PI3K) in the activation of gIV-PLA(2) and the hydrolysis of membrane phosphatidylcholine in fMLP-stimulated human blood eosinophils. Transduction into eosinophils of Deltap85, a dominant negative form of class IA PI3K adaptor subunit, fused to an HIV-TAT protein transduction domain (TAT-Deltap85) concentration dependently inhibited fMLP-stimulated phosphorylation of protein kinase B, a downstream target of PI3K. FMLP caused increased arachidonic acid (AA) release and secretion of leukotriene C(4) (LTC(4)). TAT-Deltap85 and LY294002, a PI3K inhibitor, blocked the phosphorylation of gIV-PLA(2) at Ser(505) caused by fMLP, thus inhibiting gIV-PLA(2) hydrolysis and production of AA and LTC(4) in eosinophils. FMLP also caused extracellular signal-related kinases 1 and 2 and p38 MAPK phosphorylation in eosinophils; however, neither phosphorylation of extracellular signal-related kinases 1 and 2 nor p38 was inhibited by TAT-Deltap85 or LY294002. Inhibition of 1) p70 S6 kinase by rapamycin, 2) protein kinase B by Akt inhibitor, or 3) protein kinase C by Ro-31-8220, the potential downstream targets of PI3K for activation of gIV-PLA(2), had no effect on AA release or LTC(4) secretion caused by fMLP. We find that PI3K is required for gIV-PLA(2) activation and hydrolytic production of AA in activated eosinophils. Our data suggest that this essential PI3K independently activates gIV-PLA(2) through a pathway that does not involve MAPK. PMID:14530366

  16. Group IV complexes containing the benzotriazole phenoxide ligand as catalysts for the ring-opening polymerization of lactides, epoxides and as precatalysts for the polymerization of ethylene.

    PubMed

    Pappuru, Sreenath; Chokkapu, Eswara Rao; Chakraborty, Debashis; Ramkumar, Venkatachalam

    2013-12-14

    A series of Ti(IV), Zr(IV) and Hf(IV) benzotriazole phenoxide (BTP) complexes were synthesized and characterized by various spectroscopic techniques, elemental analysis and X-ray crystallography. The monosubstituted Zr(IV) BTP complexes [(μ-L)Zr(O(i)Pr)3]2 1-3 [L = (C1)BTP-H (1), (TCl)BTP-H (2), (pent)BTP-H (3)] and tetrasubstituted Zr(IV), Hf(IV) complexes ZrL4 4-6 [L = (C1)BTP-H (4), (TCl)BTP-H (5), (pent)BTP-H (6)] and HfL4 7-9 [L = (C1)BTP-H (7), (TCl)BTP-H (8), (pent)BTP-H (9)] were prepared by the reaction of Zr(O(i)Pr)4·((i)PrOH) and Hf(O(t)Bu)4 in toluene with the respective ligands in different stoichiometric proportions. The reaction between BTP and TiCl4 and ZrCl4 and HfCl4 in a 2 : 1 stoichiometric reaction resulted in the formation of disubstituted group IV chloride complexes L2MCl2 10-12 [L = (C1)BTP-H, M = Ti, Zr and Hf]. The molecular structures of complexes 1, 4, 7, 10, 11, and 12 were determined by single-crystal X-ray studies. The X-ray structure of 1 reveals a dimeric Zr(IV) complex containing a Zr2O2 core bridged through the oxygen atoms of the phenoxide groups. Each Zr atom is distorted from an octahedral symmetry. These complexes were found to be active towards the ring-opening polymerization (ROP) of L-lactide (L-LA) and rac-lactide (rac-LA). Complex 1 produced highly heterotactic poly(lactic acid) (PLA) from rac-LA under melt conditions with narrow molecular weight distributions (MWDs) and well controlled number average molecular weights (M(n)). Additionally, epoxide polymerizations using rac-cyclohexene oxide (CHO), rac-propylene oxide (PO), and rac-styrene oxide (SO) were also carried out with these complexes. The yield and molecular weight of the polymer was found to increase with the extension of reaction time. Compounds 1-12 were activated by methylaluminoxane (MAO) and show good activity for ethylene polymerization and produced high molecular weight polyethylene. PMID:24071827

  17. Retinal Dystrophy and Optic Nerve Pathology in the Mouse Model of Mucolipidosis IV.

    PubMed

    Grishchuk, Yulia; Stember, Katherine G; Matsunaga, Aya; Olivares, Ana M; Cruz, Nelly M; King, Victoria E; Humphrey, Daniel M; Wang, Shirley L; Muzikansky, Alona; Betensky, Rebecca A; Thoreson, Wallace B; Haider, Neena; Slaugenhaupt, Susan A

    2016-01-01

    Mucolipidosis IV is a debilitating developmental lysosomal storage disorder characterized by severe neuromotor retardation and progressive loss of vision, leading to blindness by the second decade of life. Mucolipidosis IV is caused by loss-of-function mutations in the MCOLN1 gene, which encodes the transient receptor potential channel protein mucolipin-1. Ophthalmic pathology in patients includes corneal haze and progressive retinal and optic nerve atrophy. Herein, we report ocular pathology in Mcoln1(-/-) mouse, a good phenotypic model of the disease. Early, but non-progressive, thinning of the photoreceptor layer, reduced levels of rhodopsin, disrupted rod outer segments, and widespread accumulation of the typical storage inclusion bodies were the major histological findings in the Mcoln1(-/-) retina. Electroretinograms showed significantly decreased functional response (scotopic a- and b-wave amplitudes) in the Mcoln1(-/-) mice. At the ultrastructural level, we observed formation of axonal spheroids and decreased density of axons in the optic nerve of the aged (6-month-old) Mcoln1(-/-) mice, which indicates progressive axonal degeneration. Our data suggest that mucolipin-1 plays a role in postnatal development of photoreceptors and provides a set of outcome measures that can be used for ocular therapy development for mucolipidosis IV. PMID:26608452

  18. Costs and Their Assessment to Users of a Medical Library, Part IV: Differences in the Use of a Health Science Library by Various User Groups.

    ERIC Educational Resources Information Center

    Bres, E.; And Others

    Part IV is a summary analysis of sample and survey data collected to facilitate the structure of the cost assessment models and to find out which, if any, subgroups of HAM-TMC user population make more (or less) use of various library services. Sampling data were obtained from brief interviews and in-house files of various user institutions to…

  19. Quantum group extended chiral p-models

    NASA Astrophysics Data System (ADS)

    Hadjiivanov, L. K.; Paunov, R. R.; Todorov, I. T.

    1991-06-01

    The quantum symmetry group U q of an extended chiral conformal model is determined by the requirement that symmetry transformations commute with braid group statistics operators and by the relation between fusion rules and tensor product expansions of a certain class of U 4 representations. For thermal minimal " p-models", involving no more than p - 1 unitary lowest weight representations of the Virasoro algebra Vir, U 4 is the quantum universal enveloping (QUE) algebra U 4(sl(2)) with deformation parameter q satisfying q + q-1 = 2 cos π/ p ( qp = - 1, p = 4, 5,…). To each 2-dimensional local field labelled by a pair of nonnegative integers v, v¯ (0 ⩽ v, v¯ ⩽ p - 2) we make correspond an analytic chiral field φv, of weight Δ vand q- spin I v¯. The correlation functions of φv, transform under an 1-dimensional unitary representation of the braid group. As a result we reproduce the ADE classification of 2-dimensional p models in terms of their extended chiral counterparts. It turns out that U q-extended chiral p-models always involve non-unitary and indecomposable representations of Vir.

  20. Validation of the Monte Carlo criticality program KENO IV and the Hansen-Roach sixteen-energy-group-cross sections for high-assay uranium systems. [KENO IV criticality code

    SciTech Connect

    Handley, G. R.; Masters, L. C.; Stachowiak, R. V.

    1981-04-10

    Validation of the Monte Carlo criticality code, KENO IV, and the Hansen-Roach sixteen-energy-group cross sections was accomplished by calculating the effective neutron multiplication constant, k/sub eff/, of 29 experimentally critical assemblies which had uranium enrichments of 92.6% or higher in the uranium-235 isotope. The experiments were chosen so that a large variety of geometries and of neutron energy spectra were covered. Problems, calculating the k/sub eff/ of systems with high-uranium-concentration uranyl nitrate solution that were minimally reflected or unreflected, resulted in the separate examination of five cases.

  1. Modeling selenium (IV and VI) adsorption envelopes in selected tropical soils using the constant capacitance model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The adsorption of selenium (Se) on soil is important due to the relevance of Se to environmental and health issues. The adsorption of Se(IV) and Se(VI) was evaluated on soil samples from São Paulo state, Brazil, as a function of varying pH, and the experimental data were fitted to the constant capac...

  2. Renormalization Group in the Standard Model

    SciTech Connect

    Kielanowski, P.; Juarez W, S. R.

    2007-11-27

    We discuss two applications of the renormalization group method in the Standard Model. In the first one we present some theorems about the running of the Cabibbo-Kobayashi-Maskawa matrix and show that the evolution depends on one function of energy only. In the second one we discuss the properties of the running of the Higgs potential and derive the limits for the Higgs mass.

  3. A Comprehensive Health Group Practice Model.

    PubMed

    Pihlstrom, Daniel; White, Danny

    2015-01-01

    Permanente Dental Associates includes 17 offices in the Pacific Northwest. Among the distinguishing characteristics of this model are a predominantly HMO structure and integration of care in a general medical program. Staff dentists are on salary and are largely relieved of the business details of practice. Ultimate control of the system is vested in a group of shareholders--the dentists who practice chairside. One of the shareholder-practitioners discusses his perspective on this system. PMID:26562978

  4. Quantum groups, braiding matrices and coset models

    SciTech Connect

    Itoyama, H.

    1989-07-01

    We discuss a few results on quantum groups in the context of rational conformal field theory with underlying affine Lie algebras. A vertex-height correspondence - a well-known procedure in solvable lattice models - is introduced in the WZW theory. This leads to a new definition of chiral vertex operator in which the zero mode is given by the q-Clebsch Gordan coefficients. Braiding matrices of coset models are found to factorize into those of the WZW theories. We briefly discuss the construction of the generators of the universal enveloping algebra in Toda field theories. 21 refs., 2 figs.

  5. Group Chaos Theory: A Metaphor and Model for Group Work

    ERIC Educational Resources Information Center

    Rivera, Edil Torres; Wilbur, Michael; Frank-Saraceni, James; Roberts-Wilbur, Janice; Phan, Loan T.; Garrett, Michael T.

    2005-01-01

    Group phenomena and interactions are described through the use of the chaos theory constructs and characteristics of sensitive dependence on initial conditions, phase space, turbulence, emergence, self-organization, dissipation, iteration, bifurcation, and attractors and fractals. These constructs and theoretical tenets are presented as applicable…

  6. Chemical evolution models of Local Group galaxies

    NASA Astrophysics Data System (ADS)

    Tosi, Monica

    Status quo and perspectives of standard chemical evolution models of Local Group galaxies are summarized, and what we have learned from them is discussed, as well as what we have not learned yet, and what I think will be learned in the near future. Galactic chemical evolution models have shown that: I) stringent constraints on primordial nucleosynthesis can be derived from the observed Galactic abundances of the light elements; II) the Milky Way has been accreting external gas from early epochs to the present time; and III) the vast majority of Galactic halo stars have formed quite rapidly at early epochs. Chemical evolution models for the closest dwarf galaxies, although still uncertain, are expected to become extremely reliable in the immediate future, thanks to the quality of new generation photometric and spectroscopic data which are currently being acquired.

  7. Computational social dynamic modeling of group recruitment.

    SciTech Connect

    Berry, Nina M.; Lee, Marinna; Pickett, Marc; Turnley, Jessica Glicken; Smrcka, Julianne D.; Ko, Teresa H.; Moy, Timothy David; Wu, Benjamin C.

    2004-01-01

    The Seldon software toolkit combines concepts from agent-based modeling and social science to create a computationally social dynamic model for group recruitment. The underlying recruitment model is based on a unique three-level hybrid agent-based architecture that contains simple agents (level one), abstract agents (level two), and cognitive agents (level three). This uniqueness of this architecture begins with abstract agents that permit the model to include social concepts (gang) or institutional concepts (school) into a typical software simulation environment. The future addition of cognitive agents to the recruitment model will provide a unique entity that does not exist in any agent-based modeling toolkits to date. We use social networks to provide an integrated mesh within and between the different levels. This Java based toolkit is used to analyze different social concepts based on initialization input from the user. The input alters a set of parameters used to influence the values associated with the simple agents, abstract agents, and the interactions (simple agent-simple agent or simple agent-abstract agent) between these entities. The results of phase-1 Seldon toolkit provide insight into how certain social concepts apply to different scenario development for inner city gang recruitment.

  8. Multidimensional Model of Fluid Flow and Heat Transfer in Generation-IV Supercritical Water Reactors

    SciTech Connect

    Gallaway, Tara; Antal, Steven P.; Podowski, Michael Z.

    2006-07-01

    This paper is concerned with the mechanistic modeling and theoretical/computational analysis of flow and heat transfer in future Generation-IV Supercritical Water Cooled Reactors (SCWR). The issues discussed in the paper include: the development of analytical models of the properties of supercritical water, and the application of full three-dimensional computational modeling framework to simulate fluid flow and heat transfer in SCWRs. Several results of calculations are shown, including the evaluation of water properties (density, specific heat, thermal conductivity, viscosity, and Prandtl number) near the pseudo-critical temperature for various supercritical pressures, and the CFD predictions using the NPHASE computer code. It is demonstrated that the proposed approach is very promising for future mechanistic analyses of SCWR thermal-hydraulics and safety. (authors)

  9. The relationships between WAIS-IV factor index scores and educational level: A bifactor model approach.

    PubMed

    Abad, Francisco J; Sorrel, Miguel A; Román, Francisco J; Colom, Roberto

    2016-08-01

    IQ summary scores may not involve equivalent psychological meaning for different educational levels. Ultimately, this relates to the distinction between constructs and measurements. Here, we explore this issue studying the standardization of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) for Spain. A representative sample of 743 individuals (374 females and 369 males) who completed the 15 subtests comprising this intelligence battery was considered. We analyzed (a) the best latent factor structure for modeling WAIS-IV subtest performance, (b) measurement invariance across educational levels, and (c) the relationships of educational level/attainment with latent factors, Full Scale IQ (FSIQ), and index factor scores. These were the main findings: (a) the bifactor model provides the best fit; (b) there is partial invariance, and therefore it is concluded that the battery is a proper measure of the constructs of interest for the educational levels analyzed (nevertheless, the relevance of g decreases at high educational levels); (c) at the latent level, g and, to a lesser extent, Verbal Comprehension and Processing Speed, are positively related to educational level/attainment; (d) despite the previous finding, we find that Verbal Comprehension and Processing Speed factor index scores have reduced incremental validity beyond FSIQ; and (e) FSIQ is a slightly biased measure of g. (PsycINFO Database Record PMID:26322798

  10. Can Clinicians Recognize DSM-IV Personality Disorders From Five-Factor Model Descriptions of Patient Cases?

    PubMed Central

    Rottman, Benjamin M.; Ahn, Woo-kyoung; Sanislow, Charles A.; Kim, Nancy S.

    2010-01-01

    Objective This article examined, using theories from cognitive science, the clinical utility of the Five-Factor Model (FFM) of Personality, an assessment and classification system under consideration for integration into the forthcoming fifth edition of the Diagnostic and Statistical Manual (DSM) of Mental Disorders. Specifically, the authors sought to test whether FFM descriptors are specific enough to allow practicing clinicians to capture core features of personality disorders. Method In two studies, a large nationwide sample of clinical psychologists, psychiatrists, and clinical social workers (N= 187 and N=191) were presented case profiles based on symptom formats from either the DSM-IV and/or FFM. Ratings for six aspects of clinical utility for DSM-IV and FFM profiles were obtained and participants provided DSM-IV diagnoses. Prototypic cases (only one personality disorder) and comorbid cases were tested in separate studies. Results Participants rated the DSM-IV as more clinically useful than the FFM on five out of six clinical utility questions. Despite demonstrating considerable background knowledge of DSM-IV diagnoses, participants had difficulty identifying correct diagnoses from FFM profiles. Conclusion The FFM descriptors may be more ambiguous than the criteria of the DSM-IV and the FFM may therefore be less able to convey important clinical details than the DSM-IV. The findings flag challenges to clinical utility for dimensional-trait systems such as the FFM. PMID:19289453

  11. Using clinician-rated five-factor model data to score the DSM-IV personality disorders.

    PubMed

    Miller, Joshua D; Maples, Jessica; Few, Lauren R; Morse, Jennifer Q; Yaggi, Kirsten E; Pilkonis, Paul A

    2010-07-01

    Proposals suggest that many or all of the Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV]; American Psychiatric Association, 1994) personality disorders (PDs) may be omitted from the DSM (5th ed.; DSM-V) and replaced with a dimensional trait model of personality pathology (Krueger, Skodol, Livesley, Shrout, & Huang, 2007; Skodol, 2009). Several authors have expressed concerns that this may be difficult for clinicians and researchers who are more comfortable with the extant PD diagnoses. In this study, we tested whether clinician ratings of traits from the Five-factor model (FFM; Costa & McCrae, 1990) can be used to recreate DSM-IV PDs. Using a sample of 130 clinical outpatients, we tested the convergent and discriminant validity of the FFM PD counts in relation to consensus ratings of the DSM-IV PDs. We then examined whether the FFM and DSM-IV PD scores correlate in similar ways with self-reported personality traits from the Schedule for Nonadaptive and Adaptive Personality (Clark, 1993). Finally, we tested the clinical utility of the FFM PD counts in relation to functional impairment. Overall, the FFM PD counts, scored using clinician ratings of the FFM traits, appeared to function like the DSM-IV PDs, thus suggesting that the use of a dimensional trait model of personality in the DSM-V may still allow for an assessment of the DSM-IV PD constructs. PMID:20552504

  12. Vapor-liquid-soild growth of group IV (Si, Ge, Si1-xGe x) single and heterostructured nanowires

    NASA Astrophysics Data System (ADS)

    Minassian, Sharis

    In this thesis, an alternative Si source, disilane (Si2H 6) has been investigated which is of interest since it is more reactive than SiH4 and therefore may enable higher growth rates at lower temperature and lower partial pressures. The lower thermal stability of Si 2H6 could also be an advantage to enable the growth of Si 1-xGex nanowires over the entire composition range at lower temperatures which are more compatible with the range of conditions typically used for Ge nanowire growth and in turn may enable the fabrication of different types of heterostructures. To fulfill the objective of this research, a systematic study has been developed to explore the growth of group IV (Si, Ge, and Si 1-xGex alloy) single and heterostructured nanowires from Si2H6 and GeH4 precursors. First, the growth kinetics of individual SiNWs from Si2H 6 was investigated by examining the effects of growth parameters on their growth rate. The results were compared to that obtained with SiH 4. In addition, to gain a better insight into the SiNW growth process, the results were also compared with Si films deposited under similar conditions inside the same reactor. Overall compared to SiH4, the use of Si 2H6 enabled higher growth rates for both SiNWs and Si films. For both gases, a nonlinearity was observed in the growth rate of nanowire as a function of gas partial pressure which was explained by a simple decomposition mechanism including the adsorption, desorption and incorporation of precursor molecule on the Au droplet surface. The apparent activation energy of the process was found to be identical for both gases under the conditions examined in the present study, suggesting similar rate-determining step in the nanowire growth process from the two precursors. Upon completion of studies on SiNW growth, the synthesis parameter space was then determined for undoped GeNWs and the influence of growth conditions on their morphology as well as their growth rate was examined. It was found that

  13. Modeling of thorium (IV) ions adsorption onto a novel adsorbent material silicon dioxide nano-balls using response surface methodology.

    PubMed

    Kaynar, Ümit H; Şabikoğlu, Israfil; Kaynar, Sermin Çam; Eral, Meral

    2016-09-01

    The silicon dioxide nano-balls (nano-SiO2) were prepared for the adsorption of thorium (IV) ions from aqueous solution. The synthesized silicon dioxide nano-balls were characterized by Scanning Electron Microscopy/Energy Dispersive X-ray, X-ray Diffraction, Fourier Transform Infrared and BET surface area measurement spectroscopy. The effects of pH, concentration, temperature and the solid-liquid ratio on the adsorption of thorium by nano-balls were optimized using central composite design of response surface methodology. The interaction between four variables was studied and modelled. Furthermore, the statistical analysis of the results was done. Analysis of variance revealed that all of the single effects found statistically significant on the sorption of Th(IV). Probability F-values (F=4.64-14) and correlation coefficients (R(2)=0.99 for Th(IV)) indicate that model fit the experimental data well. The ability of this material to remove Th(IV) from aqueous solution was characterized by Langmuir, Freunlinch and Temkin adsorption isotherms. The adsorption capacity of thorium (IV) achieved 188.2mgg(-1). Thermodynamic parameters were determined and discussed. The batch adsorption condition with respect to interfering ions was tested. The results indicated that silicon dioxide nano-balls were suitable as sorbent material for adsorption and recovery of Th(IV) ions from aqueous solutions. PMID:27451112

  14. Modeling of Internet Influence on Group Emotion

    NASA Astrophysics Data System (ADS)

    Czaplicka, Agnieszka; Hołyst, Janusz A.

    Long-range interactions are introduced to a two-dimensional model of agents with time-dependent internal variables ei = 0, ±1 corresponding to valencies of agent emotions. Effects of spontaneous emotion emergence and emotional relaxation processes are taken into account. The valence of agent i depends on valencies of its four nearest neighbors but it is also influenced by long-range interactions corresponding to social relations developed for example by Internet contacts to a randomly chosen community. Two types of such interactions are considered. In the first model the community emotional influence depends only on the sign of its temporary emotion. When the coupling parameter approaches a critical value a phase transition takes place and as result for larger coupling constants the mean group emotion of all agents is nonzero over long time periods. In the second model the community influence is proportional to magnitude of community average emotion. The ordered emotional phase was here observed for a narrow set of system parameters.

  15. Temperature Distributions in LMR Fuel Pin Bundles as Modeled by COBRA-IV-I

    NASA Astrophysics Data System (ADS)

    Wright, Steven A.; Stout, Sherry

    2005-02-01

    Most pin type reactor designs for space power or terrestrial applications group the fuel pins into a number of relatively large fuel pin bundles or subassemblies. Fuel bundles for terrestrial liquid metal fast breeders reactors typically use 217 - 271 pins per sub-assembly, while some SP100 designs use up to 331 pins in a central subassembly that was surrounded by partial assemblies. Because thermal creep is exponentially related to temperature, small changes in fuel pin cladding temperature can make large differences in the lifetime in a high temperature liquid metal reactor (LMR). This paper uses the COBRA-IV-I computer code to determine the temperature distribution within LMR fuel bundles. COBRA-IV-I uses the sub-channel analysis approach to determine the enthalpy (or temperature) and flow distribution in rod bundles for both steady-state and transient conditions. The COBRA code runs in only a few seconds and has been benchmarked and tested extensively over a wide range of flow conditions. In this report the flow and temperature distributions for two types of lithium cooled space reactor core designs were calculated. One design uses a very tight fuel pin packing that has a pitch to diameter ratio of 1.05 (small wire wrap with a diameter of 392 μm) as proposed in SP100. The other design uses a larger pitch to diameter ratio of 1.09 with a larger more conventional sized wire wrap diameter of 1 mm. The results of the COBRA pin bundle calculations show that the larger pitch-to-diameter fuel bundle designs are more tolerant to local flow blockages, and in addition they are less sensitive to mal-flow distributions that occur near the edges of the subassembly.

  16. Temperature Distributions in LMR Fuel Pin Bundles as Modeled by COBRA-IV-I

    SciTech Connect

    Wright, Steven A.; Stout, Sherry

    2005-02-06

    Most pin type reactor designs for space power or terrestrial applications group the fuel pins into a number of relatively large fuel pin bundles or subassemblies. Fuel bundles for terrestrial liquid metal fast breeders reactors typically use 217 - 271 pins per sub-assembly, while some SP100 designs use up to 331 pins in a central subassembly that was surrounded by partial assemblies. Because thermal creep is exponentially related to temperature, small changes in fuel pin cladding temperature can make large differences in the lifetime in a high temperature liquid metal reactor (LMR). This paper uses the COBRA-IV-I computer code to determine the temperature distribution within LMR fuel bundles. COBRA-IV-I uses the sub-channel analysis approach to determine the enthalpy (or temperature) and flow distribution in rod bundles for both steady-state and transient conditions. The COBRA code runs in only a few seconds and has been benchmarked and tested extensively over a wide range of flow conditions. In this report the flow and temperature distributions for two types of lithium cooled space reactor core designs were calculated. One design uses a very tight fuel pin packing that has a pitch to diameter ratio of 1.05 (small wire wrap with a diameter of 392 {mu}m) as proposed in SP100. The other design uses a larger pitch to diameter ratio of 1.09 with a larger more conventional sized wire wrap diameter of 1 mm. The results of the COBRA pin bundle calculations show that the larger pitch-to-diameter fuel bundle designs are more tolerant to local flow blockages, and in addition they are less sensitive to mal-flow distributions that occur near the edges of the subassembly.

  17. Can Personality Disorder Experts Recognize DSM-IV Personality Disorders from Five-Factor Model Descriptions of Patient Cases?

    PubMed Central

    Rottman, Benjamin M.; Kim, Nancy S.; Ahn, Woo-kyoung; Sanislow, Charles A.

    2012-01-01

    Background Dimensional models of personality are under consideration for integration into the next Diagnostic and Statistical Manual of Mental Disorders (DSM-V), but the clinical utility of such models is unclear. Objective To test the ability of clinical researchers who specialize in personality disorders to diagnose personality disorders using dimensional assessments, and to compare these researchers’ ratings of clinical utility for a dimensional system versus for the DSM-IV. Method A sample of 73 researchers who had each published at least three (Median=15) articles on personality disorders participated between December 2008 and January 2009. The Five-Factor Model (FFM), one of the most-studied dimensional models to date, was compared to the DSM-IV. Participants provided diagnoses for case profiles in DSM-IV and FFM formats, and then rated the DSM-IV and FFM on six aspects of clinical utility. Results Overall, participants had difficulty identifying correct diagnoses from FFM profiles, and the same held true for a subset reporting equal familiarity with the DSM-IV and FFM. Participants rated the FFM as less clinically useful than the DSM for making prognoses, devising treatment plans, and communicating with professionals, but more useful for communicating with patients. Conclusions The results suggest that personality disorder expertise and familiarity with the FFM are insufficient to correctly diagnose personality disorders using FFM profiles. Because of ambiguity inherent in FFM profile descriptors, it may be that this insufficiency is unlikely to be attenuated with increased clinical familiarity with the FFM. PMID:21208595

  18. An Application of the PMI Model at the Project Level Evaluation of ESEA Title IV-C Projects.

    ERIC Educational Resources Information Center

    McBeath, Marcia

    All of the papers presented as part of a symposium concerned the application of the Planning, Monitoring, and Implementation Model (PMI) to the evaluation of the District of Columbia Public Schools' programs supported by the Elementary Secondary Education Act (ESEA) Title IV-C. PMI was developed to provide a model for systematic evaluation of…

  19. DEVELOPMENT AND TESTING OF THE CBM-IV (CARBON-BOND MECHANISM) FOR URBAN AND REGIONAL MODELING

    EPA Science Inventory

    The development and testing of an updated Carbon Bond Mechanism (CBM) is described. The new mechanism, called CBM-IV, was designed for use in EPA's OZIPM-EKMA model. The mechanism, however, is also suitable for use in large air quality simulation models such as the Urban Airshed ...

  20. Solution chemistry of Mo(III) and Mo(IV): Thermodynamic foundation for modeling localized corrosion.

    SciTech Connect

    Wang, P; Wilson, L; Wesolowski, David J

    2010-05-01

    To investigate the behavior of molybdenum dissolution products in systems that approximate localized corrosion environments, solubility of Mo(III) in equilibrium with solid MoO{sub 2} has been determined at 80 C as a function of solution acidity, chloride concentration and partial pressure of hydrogen. The measurements indicate a strong increase in solubility with acidity and chloride concentration and a weak effect of hydrogen partial pressure. The obtained results have been combined with literature data for systems containing Mo(III), Mo(IV), and Mo(VI) in solutions to develop a comprehensive thermodynamic model of aqueous molybdenum chemistry. The model is based on a previously developed framework for simulating the properties of electrolyte systems ranging from infinite dilution to solid saturation or fused salt limit. To reproduce the measurements, the model assumes the presence of a chloride complex of Mo(III) (i.e., MoCl{sup 2+}) and hydrolyzed species (MoOH{sup 2+}, Mo(OH){sup 2+}, and Mo(OH){sub 3}{sup 0}) in addition to the Mo{sup 3+} ion. The model generally reproduces the experimental data within experimental scattering and provides a tool for predicting the phase behavior and speciation in complex, concentrated aqueous solutions. Thus, it provides a foundation for simulating the behavior of molybdenum species in localized corrosion environments.

  1. Enantioselective hydrogenation. IV. Hydrogen isotope exchange in 10,11-dihydrocinchonidine and in quinoline catalyzed by platinum group metals

    SciTech Connect

    Bond, G.; Wells, P.B.

    1994-12-01

    Hydrogen isotope (H/D) exchange in the alkaloid 10,11-dihydrocinchonidine has been studied over 6.4% Pt/silica (EUROPT-1), 5% Ru/alumina, 5% Rh/alumina, and 5% Pd/alumina at 293 K using C{sub 2}H{sub 5}OD and D{sub 2} as solvent and deuterium source. Exchange was accompanied by hydrogenation. Over Pt, fast exchange occurred in the hydroxyl group followed by multiple exchange in which alkaloid molecules containing, 2, 3, 4 and 5 deuterium atoms were formed simultaneously. Mass spectrometry and {sup 1}H NMR showed that this multiple exchange occurred in the quinoline ring system and at C{sub 9}, but not in the quinuclidine ring system. The pattern of exchange in Ru was similar. Over Rh extensive hydrogenolysis of the quinuclidine ring system occurred, and over Pd the quinoline ring system was rapidly hydrogenated. Quinoline exchange and hydrogenation were also studied at 293 K; relatively rapid exchange occurred over Pt, Ru, and Rh, particularly at the 2- and 8-positions, whereas hydrogenation without significant exchange occurred over Pd. 10,11-Dihydrocinchonidine is adsorbed on Pt and Ru via the quinoline ring system and the multiple nature of the exchange indicates that the quinoline moiety is adsorbed approximately parallel to the metal surface by multicenter {pi}-bonding. An additional interaction of the alkaloid molecule with the surface occurs at carbon atom C{sub 9}, which may interpret the slower exchange in the alkaloid by comparison with that in quinoline. This study supports and enhances the model proposed to interpret the origin of enantioselectivity in pyruvate hydrogenation over Pt and Ir modified by cinchona alkaloids. The similarities of exchange over Pt and Ru suggest that enantioselective catalysis should be achievable over Ru. 28 refs., 2 figs., 2 tabs.

  2. THE ACS LCID PROJECT. IV. DETECTION OF THE RED GIANT BRANCH BUMP IN ISOLATED GALAXIES OF THE LOCAL GROUP

    SciTech Connect

    Monelli, M.; Hidalgo, S. L; Aparicio, A.; Gallart, C.; Cassisi, S.; Bernard, E. J.; Skillman, E. D. E-mail: carme@iac.e E-mail: shidalgo@iac.e E-mail: ejb@roe.ac.u

    2010-08-01

    We report the detection and analysis of the red giant branch (RGB) luminosity function bump in a sample of isolated dwarf galaxies in the Local Group. We have designed a new analysis approach comparing the observed color-magnitude diagrams (CMDs) with theoretical best-fit CMDs derived from precise estimates of the star formation histories of each galaxy. This analysis is based on studying the difference between the V magnitude of the RGB bump and the horizontal branch at the level of the RR Lyrae instability strip ({Delta}V {sup bump}{sub HB}) and we discuss here a technique for reliably measuring this quantity in complex stellar systems. By using this approach, we find that the difference between the observed and predicted values of {Delta}V {sup bump}{sub HB} is +0.13 {+-} 0.14 mag. This is smaller, by about a factor of 2, than the well-known discrepancy between theory and observation at low metallicity commonly derived for Galactic globular clusters (GCs). This result is confirmed by a comparison between the adopted theoretical framework and empirical estimates of the {Delta}V {sup bump}{sub HB} parameter for both a large database of Galactic GCs and for four other dwarf spheroidal galaxies for which this estimate is available in the literature. We also investigate the strength of the RGB bump feature (R{sub bump}), and find very good agreement between the observed and theoretically predicted R{sub bump} values. This agreement supports the reliability of the evolutionary lifetimes predicted by theoretical models of the evolution of low-mass stars.

  3. Chemical modeling of arsenic(III, V) and selenium(IV, VI) adsorption by soils surrounding ash disposal facilities

    SciTech Connect

    Goldberg, S.; Hyun, S.; Lee, L.S.

    2008-11-15

    Leachate derived from coal ash disposal facilities is a potential anthropogenic source of As and Se to the environment. To establish a practical framework for predicting attenuation and transport of As and Se in ash leachates, the adsorption of As(III), As(V), Se(IV), and Se(VI) had been characterized in prior studies for 18 soils obtained downgradient from ash landfill sites and representing a wide range of soil properties. The constant capacitance model was applied for the first time to describe As(III), As(V), Se(IV), and Se(VI) adsorption on soils as a function of equilibrium solution As(III), As(V), Se(IV), and Se(VI) concentrations. Prior applications of the model had been restricted to describing Se(IV) and As(V) adsorption by soils as a function of solution pH. The constant capacitance model was applied for the first time to describe As(III) and Se(VI) adsorption by soils. The model was able to describe adsorption of these ions on all soils as a function of solution ion concentration by optimizing only one adjustable parameter, the anion surface complexation constant. This chemical model represents an advancement over adsorption isotherm equation approaches that contain two empirical adjustable parameters. Incorporation of these anion surface complexation constants obtained with the constant capacitance model into chemical speciation transport models will allow simulation of soil solution anion concentrations under diverse environmental and agricultural conditions.

  4. Developmental decline in modulation of glutamatergic synapses in layer IV of the barrel cortex by group II metabotropic glutamate receptors.

    PubMed

    Mateo, Z; Porter, J T

    2015-04-01

    Previously, we demonstrated that group II metabotropic glutamate receptors (mGluRs) reduce glutamate release from thalamocortical synapses during early postnatal development (P7-11). To further examine the role of group II mGluRs in the modulation of somatosensory circuitry, we determined whether group II mGluRs continue to modulate thalamocortical synapses until adulthood and whether these receptors also modulate intra-cortical synapses in the barrel cortex. To address these issues, we examined the effect of the group II mGluR agonists on thalamocortical excitatory postsynaptic currents (EPSCs) and intra-barrel EPSCs in slices from animals of different ages (P7-53). We found that the depression of thalamocortical EPSCs by group II mGluRs rapidly declined after the second postnatal week. In contrast, adenosine continued to depress thalamocortical EPSCs via a presynaptic mechanism in young adult mice (P30-50). Activation of group II mGluRs also reduced intra-barrel EPSCs through a postsynaptic mechanism in young mice (P7-11). Similar to the thalamocortical synapses, the group II mGluR modulation of intra-barrel excitatory synapses declined with development. In young adult animals (P30-50), group II mGluR stimulation had little effect on intra-barrel EPSCs but did hyperpolarize the neurons. Together our results demonstrate that group II mGluRs modulate barrel cortex circuitry by presynaptic and postsynaptic mechanisms depending on the source of the synapse and that this modulation declines with development. PMID:25595969

  5. Developmental decline in modulation of glutamatergic synapses in layer IV of the barrel cortex by group II metabotropic glutamate receptors

    PubMed Central

    Mateo, Zaira; Porter, James T.

    2015-01-01

    Previously, we demonstrated that group II mGluRs reduce glutamate release from thalamocortical synapses during early postnatal development (P7–11). To further examine the role of group II mGluRs in the modulation of somatosensory circuitry, we determined whether group II mGluRs continue to modulate thalamocortical synapses until adulthood and whether these receptors also modulate intra-cortical synapses in the barrel cortex. To address these issues, we examined the effect of the group II mGluR agonists on thalamocortical EPSCs and intra-barrel EPSCs in slices from animals of different ages (P7–53). We found that the depression of thalamocortical EPSCs by stimulation group II mGluRs rapidly declined after the second postnatal week. In contrast, adenosine continued to depress thalamocortical EPSCs via a presynaptic mechanism in young adult mice (P30–50). Activation group II mGluRs also reduced intra-barrel EPSCs through a postsynaptic mechanism in young mice (P7–11). Similar to the thalamocortical synapses, the group II mGluR modulation of intra-barrel excitatory synapses declined with development. In young adult animals (P30–50), group II mGluR stimulation had little effect on intra-barrel EPSCs but did hyperpolarize the neurons. Together our results demonstrate that group II mGluRs modulate barrel cortex circuitry by presynaptic and postsynaptic mechanisms depending on the source of the synapse and that this modulation declines with development. PMID:25595969

  6. The fourth radiation transfer model intercomparison (RAMI-IV): Proficiency testing of canopy reflectance models with ISO-13528

    NASA Astrophysics Data System (ADS)

    Widlowski, J.-L.; Pinty, B.; Lopatka, M.; Atzberger, C.; Buzica, D.; Chelle, M.; Disney, M.; Gastellu-Etchegorry, J.-P.; Gerboles, M.; Gobron, N.; Grau, E.; Huang, H.; Kallel, A.; Kobayashi, H.; Lewis, P. E.; Qin, W.; Schlerf, M.; Stuckens, J.; Xie, D.

    2013-07-01

    The radiation transfer model intercomparison (RAMI) activity aims at assessing the reliability of physics-based radiative transfer (RT) models under controlled experimental conditions. RAMI focuses on computer simulation models that mimic the interactions of radiation with plant canopies. These models are increasingly used in the development of satellite retrieval algorithms for terrestrial essential climate variables (ECVs). Rather than applying ad hoc performance metrics, RAMI-IV makes use of existing ISO standards to enhance the rigor of its protocols evaluating the quality of RT models. ISO-13528 was developed "to determine the performance of individual laboratories for specific tests or measurements." More specifically, it aims to guarantee that measurement results fall within specified tolerance criteria from a known reference. Of particular interest to RAMI is that ISO-13528 provides guidelines for comparisons where the true value of the target quantity is unknown. In those cases, "truth" must be replaced by a reliable "conventional reference value" to enable absolute performance tests. This contribution will show, for the first time, how the ISO-13528 standard developed by the chemical and physical measurement communities can be applied to proficiency testing of computer simulation models. Step by step, the pre-screening of data, the identification of reference solutions, and the choice of proficiency statistics will be discussed and illustrated with simulation results from the RAMI-IV "abstract canopy" scenarios. Detailed performance statistics of the participating RT models will be provided and the role of the accuracy of the reference solutions as well as the choice of the tolerance criteria will be highlighted.

  7. Neurologic, gastric, and opthalmologic pathologies in a murine model of mucolipidosis type IV.

    PubMed

    Venugopal, Bhuvarahamurthy; Browning, Marsha F; Curcio-Morelli, Cyntia; Varro, Andrea; Michaud, Norman; Nanthakumar, Nanda; Walkley, Steven U; Pickel, James; Slaugenhaupt, Susan A

    2007-11-01

    Mucolipidosis type IV (MLIV) is an autosomal recessive lysosomal storage disorder caused by mutations in the MCOLN1 gene, which encodes the 65-kDa protein mucolipin-1. The most common clinical features of patients with MLIV include severe mental retardation, delayed motor milestones, ophthalmologic abnormalities, constitutive achlorhydria, and elevated plasma gastrin levels. Here, we describe the first murine model for MLIV, which accurately replicates the phenotype of patients with MLIV. The Mcoln1(-/-) mice present with numerous dense inclusion bodies in all cell types in brain and particularly in neurons, elevated plasma gastrin, vacuolization in parietal cells, and retinal degeneration. Neurobehavioral assessments, including analysis of gait and clasping, confirm the presence of a neurological defect. Gait deficits progress to complete hind-limb paralysis and death at age ~8 mo. The Mcoln1(-/-) mice are born in Mendelian ratios, and both male and female Mcoln1(-/-) mice are fertile and can breed to produce progeny. The creation of the first murine model for human MLIV provides an excellent system for elucidating disease pathogenesis. In addition, this model provides an invaluable resource for testing treatment strategies and potential therapies aimed at preventing or ameliorating the abnormal lysosomal storage in this devastating neurological disorder. PMID:17924347

  8. The carboxyl group of Glu113 is required for stabilization of the diferrous and bis-FeIV states of MauG

    PubMed Central

    Tarboush, Nafez Abu; Yukl, Erik T.; Shin, Sooim; Feng, Manliang; Wilmot, Carrie M.; Davidson, Victor L.

    2013-01-01

    The diheme enzyme MauG catalyzes a six-electron oxidation required for posttranslational modification of a precursor of methylamine dehydrogenase (preMADH) to complete the biosynthesis of its protein-derived tryptophan tryptophylquinone (TTQ) cofactor. Crystallographic studies have implicated Glu113 in the formation of the bis-FeIV state of MauG, in which one heme is FeIV=O and the other is FeIV with His-Tyr axial ligation. An E113Q mutation had no effect on the structure of MauG, but significantly altered its redox properties. E113Q MauG could not be converted to the diferrous state by reduction with dithionite, but was only reduced to a mixed valence FeII/FeIII state, which is never observed in wild-type (WT) MauG. Addition of H2O2 to E113Q MauG generated a high valence state that formed more slowly and was less stable than the bis-FeIV state of WT MauG. E113Q MauG exhibited no detectable TTQ biosynthesis activity in a steady-state assay with preMADH as the substrate. It did catalyze the steady-state oxidation of quinol MADH to the quinone, but 1000-fold less efficiently than WT MauG. Addition of H2O2 to a crystal of the E113Q MauG-preMADH complex resulted in partial synthesis of TTQ. Extended exposure of these crystals to H2O2 resulted in hydroxylation of Pro107 in the distal pocket of the high-spin heme. It is concluded that the loss of the carboxylic group of Glu113 disrupts the redox cooperativity between hemes that allows rapid formation of the diferrous state, and alters the distribution of high-valence species that participate in charge-resonance stabilization of the bis-FeIV redox state. PMID:23952537

  9. Carboxyl group of Glu113 is required for stabilization of the diferrous and bis-Fe(IV) states of MauG.

    PubMed

    Abu Tarboush, Nafez; Yukl, Erik T; Shin, Sooim; Feng, Manliang; Wilmot, Carrie M; Davidson, Victor L

    2013-09-17

    The diheme enzyme MauG catalyzes a six-electron oxidation required for post-translational modification of a precursor of methylamine dehydrogenase (preMADH) to complete the biosynthesis of its protein-derived tryptophan tryptophylquinone (TTQ) cofactor. Crystallographic studies have implicated Glu113 in the formation of the bis-Fe(IV) state of MauG, in which one heme is Fe(IV)═O and the other is Fe(IV) with His-Tyr axial ligation. An E113Q mutation had no effect on the structure of MauG but significantly altered its redox properties. E113Q MauG could not be converted to the diferrous state by reduction with dithionite but was only reduced to a mixed valence Fe(II)/Fe(III) state, which is never observed in wild-type (WT) MauG. Addition of H2O2 to E113Q MauG generated a high valence state that formed more slowly and was less stable than the bis-Fe(IV) state of WT MauG. E113Q MauG exhibited no detectable TTQ biosynthesis activity in a steady-state assay with preMADH as the substrate. It did catalyze the steady-state oxidation of quinol MADH to the quinone, but 1000-fold less efficiently than WT MauG. Addition of H2O2 to a crystal of the E113Q MauG-preMADH complex resulted in partial synthesis of TTQ. Extended exposure of these crystals to H2O2 resulted in hydroxylation of Pro107 in the distal pocket of the high-spin heme. It is concluded that the loss of the carboxylic group of Glu113 disrupts the redox cooperativity between hemes that allows rapid formation of the diferrous state and alters the distribution of high-valence species that participate in charge-resonance stabilization of the bis-Fe(IV) redox state. PMID:23952537

  10. Molecular-based synthetic approach to new group IV materials for high-efficiency, low-cost solar cells and Si-based optoelectronics.

    PubMed

    Fang, Yan-Yan; Xie, Junqi; Tolle, John; Roucka, Radek; D'Costa, Vijay R; Chizmeshya, Andrew V G; Menendez, Jose; Kouvetakis, John

    2008-11-26

    Ge(1-x-y)Si(x)Sn(y) alloys have emerged as a new class of highly versatile IR semiconductors offering the potential for independent variation of band structure and lattice dimension, making them the first practical group IV ternary system fully compatible with Si CMOS processing. In this paper we develop and apply new synthetic protocols based on designer molecular hydrides of Si, Ge, and Sn to demonstrate this concept from a synthesis perspective. Variation of the Si/Sn ratio in the ternary leads to an entirely new family of semiconductors exhibiting tunable direct band gaps (E(o)) ranging from 0.8 to 1.2 eV at a fixed lattice constant identical to that of Ge, as required for the design of high-efficiency multijunction solar cells based on group IV/III-V hybrids. As a proof-of-concept demonstration, we fabricated lattice-matched Si(100)/Ge/SiGeSn/InGaAs architectures on low-cost Si(100) substrates for the first time. These exhibit the required optical, structural, and thermal properties, thus representing a viable starting point en route to a complete four-junction photovoltaic device. In the context of Si-Ge-Sn optoelectronic applications, we show that Ge(1-x-y)Si(x)Sn(y) alloys serve as higher-gap barrier layers for the formation of light emitting structures based on Ge(1-y)Sn(y) quantum wells grown on Si. PMID:19032100

  11. Lattice Thermal Conductivity of the Binary and Ternary Group-IV Alloys Si-Sn, Ge-Sn, and Si-Ge-Sn

    NASA Astrophysics Data System (ADS)

    Khatami, S. N.; Aksamija, Z.

    2016-07-01

    Efficient thermoelectric (TE) energy conversion requires materials with low thermal conductivity and good electronic properties. Si-Ge alloys, and their nanostructures such as thin films and nanowires, have been extensively studied for TE applications; other group-IV alloys, including those containing Sn, have not been given as much attention as TEs, despite their increasing applications in other areas including optoelectronics. We study the lattice thermal conductivity of binary (Si-Sn and Ge-Sn) and ternary (Si-Ge-Sn) alloys and their thin films in the Boltzmann transport formalisms, including a full phonon dispersion and momentum-dependent boundary-roughness scattering. We show that Si-Sn alloys have the lowest conductivity (3 W /mK ) of all the bulk alloys, more than 2 times lower than Si-Ge, attributed to the larger difference in mass between the two constituents. In addition, we demonstrate that thin films offer an additional reduction in thermal conductivity, reaching around 1 W /mK in 20-nm-thick Si-Sn, Ge-Sn, and ternary Si-Ge-Sn films, which is near the conductivity of amorphous SiO2 . We conclude that group-IV alloys containing Sn have the potential for high-efficiency TE energy conversion.

  12. Band Gap Characters and Ferromagnetic/Antiferromagnetic Coupling in Group-IV Monolayers Tuned by Chemical Species and Hydrogen Adsorption Configurations.

    PubMed

    Yu, Wen-Zhe; Yan, Jia-An; Gao, Shang-Peng

    2015-12-01

    One-side semihydrogenated monolayers of carbon, silicon, germanium, and their binary compounds with different configurations of hydrogen atoms are investigated by density functional theory. Among three considered configurations, zigzag, other than the most studied chair configuration, is energetically the most favorable structure of one-side semihydrogenation. Upon semihydrogenation, the semimetallic silicene, germanene, and SiGe become semiconductors, while the band gap in semiconducting SiC and GeC is reduced. Semihydrogenated silicene, germanene, SiGe, and GeC with chair configuration are found to be ferromagnetic semiconductors. For semihydrogenated SiC, it is ferromagnetic when all hydrogen atoms bond with silicon atoms, while an antiferromagnetic coupling is predicted when all hydrogen atoms bond with carbon atoms. The effect of interatomic distance between two neighboring magnetic atoms to the ferromagnetic or antiferromagnetic coupling is studied. For comparison, properties of one-side and both-side fully hydrogenated group-IV monolayers are also calculated. All fully hydrogenated group-IV monolayers are nonmagnetic semiconductors with band gaps larger than those of their semihydrogenated counterparts. PMID:26334543

  13. On the relation between the microscopic structure and the sound velocity anomaly in elemental melts of groups IV, V, and VI.

    PubMed

    Greenberg, Yaron; Yahel, Eyal; Caspi, El'ad N; Beuneu, Brigitte; Dariel, Moshe P; Makov, Guy

    2010-09-01

    The sound velocity of some liquid elements of groups IV, V, and VI, as reported in the literature, displays anomalous features that set them apart from other liquid metals. In an effort to determine a possible common origin of these anomalies, extensive neutron diffraction measurements of liquid Bi and Sb were carried out over a wide temperature range. The structure factors of liquid Sb and Bi were determined as a function of temperature. The structure of the two molten metals was carefully analyzed with respect to peak locations, widths, and coordination numbers in their respective radial distribution function. The width of the peaks in the radial distribution functions was not found to increase and even decreased within a certain temperature range. This anomalous temperature dependence of the peak widths correlates with the anomalous temperature dependence of the sound velocity. This correlation may be accounted for by increased rigidity of the liquid structure with temperature. A phenomenological correlation between the peak width and the sound velocity is suggested for metallic melts and is found to agree with available data for normal and anomalous elemental liquids in groups IV-VI. PMID:20831323

  14. Probing Bis-Fe(IV) MauG: Experimental Evidence for the Long-Range Charge-Resonance Model

    PubMed Central

    Geng, Jiafeng; Davis, Ian

    2015-01-01

    The biosynthesis of tryptophan tryptophylquinone, a protein-derived cofactor, involves a long-range reaction mediated by a bis-Fe(IV) intermediate of a di-heme enzyme, MauG. Recently, a unique charge-resonance (CR) phenomenon was discovered in this intermediate, and a biological, long-distance CR model was proposed. This model suggests that the chemical nature of the bis-Fe(IV) species is not as simple as it appears; rather, it is composed of a collection of resonance structures in a dynamic equilibrium. Here, we experimentally evaluated the proposed CR model by introducing small molecules to, and measuring the temperature dependence of, bis-Fe(IV) MauG. Spectroscopic evidence was presented to demonstrate that the selected compounds increase the decay rate of the bis-Fe(IV) species via disrupting the equilibrium of the resonance structures that constitutes the proposed CR model. The results support this new CR model and bring a fresh concept to the classical CR theory. PMID:25631460

  15. Antinociceptive activity of astragaloside IV in the animal model of chronic constriction injury.

    PubMed

    Shi, Guo-Bing; Fan, Rong; Zhang, Wei; Yang, Chen; Wang, Qi; Song, Juan; Gao, Yue; Hou, Ming-Xiao; Chen, Yu-Feng; Wang, Tong-Chao; Cai, Guo-Jun

    2015-08-01

    To investigate the applicability of astragaloside IV (AG) for the treatment of refractory neuropathic pain, we systemically evaluated the antinociceptive activity of AG in the animal model of chronic constriction injury. We studied behaviors, electrophysiology, and biochemistry from day 2 to day 23 after the surgery. We found that when administered intraperitoneally at the dose of 60 mg/kg, AG caused significant inhibition of allodynia and hyperalgesia induced by mechanic and thermal stimuli as well as downregulation of the expressions of a series of proteins involved in mediating neuropathic pain in the dorsal root ganglia, such as P2X purinoceptor 3, glial cell-derived neurotrophic factor, glial cell-derived neurotrophic factor family receptor α1, and transient receptor potential cation channel subtypes A1 and V1. Further investigation showed that AG restored the nerve conduction velocity and the histological structure of the damaged sciatic nerve on day 23 after the surgery. Moreover, results from immunoelectron microscope showed that glial cell-derived neurotrophic factor family receptor α1 induced by AG could form a circular band in the myelin debris between the injured axons and Schwann cells, contributing toward restoration of the damaged nerve. In conclusion, in our animal model, AG effectively inhibited the neuropathic pain induced by chronic constriction injury. PMID:25974189

  16. A Dynamic Model of Group Interaction.

    ERIC Educational Resources Information Center

    Bauer, Connie L.; And Others

    A theory of group interaction with a focus on the trajectories of relevant variables as they change over time is developed in this paper. The four major components of the group interaction process (communication, conflict, involvement, and centralization) are presented and conceptually defined, and the nature of their interdependence is discussed.…

  17. 45 CFR 310.10 - What are the functional requirements for the Model Tribal IV-D System?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 2 2010-10-01 2010-10-01 false What are the functional requirements for the Model Tribal IV-D System? 310.10 Section 310.10 Public Welfare Regulations Relating to Public Welfare OFFICE OF CHILD SUPPORT ENFORCEMENT (CHILD SUPPORT ENFORCEMENT PROGRAM), ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND...

  18. Chemical Variations Among L-Chondrites--IV. Analyses, with Petrographic Notes, of 13 L-group and 3 LL-group Chondrites

    NASA Astrophysics Data System (ADS)

    Jarosewich, E.; Dodd, R. T.

    1985-03-01

    We review our procedures for selecting, preparing and analyzing meteorite samples, present new analyses of 16 ordinary chondrites, and discuss variations of Fe, S and Si in the L-group. A tendency for Fe/Mg, S/Mg and Si/Mg to be low in L chondrites of facies d to f testifies that post-metamorphic shock melting played a significant role in the chemical diversification of the L-group. However, these ratios also vary widely and sympathetically in melt-free chondrites, indicating that much of the L-group's chemical variation arose prior to thermal metamorphism and is in that sense primary. If all L chondrites come from one parent body, type-correlated chemical trends suggest: 1) that the body had a traditional "onion skin" structure, with metamorphic intensity increasing with depth; and 2) that it formed from material that became more homogeneous, slightly poorer in iron, and significantly richer in sulfur as accretion proceeded.

  19. Performance modeling of the Ballard Mark IV solid polymer electrolyte fuel cell. 1: Mechanistic model development

    SciTech Connect

    Amphlett, J.C.; Baumert, R.M.; Mann, R.F.; Peppley, B.A.; Roberge, P.R. ); Harris, T.J. )

    1995-01-01

    A parametric model predicting the performance of a solid polymer electrolyte, proton exchange membrane (PEM) fuel cell has been developed using a combination of mechanistic and empirical modeling techniques. This paper details the mechanistic model development. Mass transport properties are considered in the mechanistic development via Stefan-Maxwell equations. Thermodynamic equilibrium potentials are defined using the Nernst equation. Activation overvoltages are defined via a Tafel equation, and internal resistance are defined via the Nernst-Planck equation, leading to a definition of ohmic overvoltage via an Ohm's law equation. The mechanistic model cannot adequately model fuel cell performance, since several simplifying approximations have been used in order to facilitate model development. Additionally, certain properties likely to be observed in operational fuel cells, such as thermal gradients, have not been considered. Nonetheless, the insights gained from the mechanistic assessment of fuel cell processes were found to give the resulting empirical model a firmer theoretical basis than many of the models presently available in the literature. Correlation of the empirical model to actual experimental data was very good.

  20. The group IV-A cyclic nucleotide-gated channels, CNGC19 and CNGC20, localize to the vacuole membrane in Arabidopsis thaliana

    PubMed Central

    Yuen, Christen C. Y.; Christopher, David A.

    2013-01-01

    Plant cyclic nucleotide-gated channels (CNGCs) are implicated in the uptake of both essential and toxic cations, Ca2+ signalling, and responses to biotic and abiotic stress. The 20 CNGC paralogues of Arabidopsis are divided into five evolutionary groups. Group IV-A is highly isolated and consists only of two closely spaced genes, CNGC19 and CNGC20. Prior studies have shown that both genes are induced by salinity and biotic stress. A unique feature of CNGC19 and CNGC20 is their long hydrophilic N-termini. To determine the subcellular locations of CNGC19 and CNGC20, partial and full-length fusions to GFP(S65T) were generated. Translational fusions of the N-termini of CNGC19 (residues 1–171) and CNGC20 (residues 1–200) to GFP(S65T) were targeted to punctate structures when transiently expressed in leaf protoplasts. In the case of CNGC20, but not CNGC19, the punctate structures were co-labelled with a marker for the Golgi. The full-length CNGC19-GFP fusion co-localized with markers for the vacuole membrane (αTIP- and γTIP-mCherry). Vacuole membrane labelling by the full-length CNGC20-GFP fusion was also observed, but the signal was weak and accompanied by numerous punctate signals that did not co-localize with αTIP- or γTIP-mCherry. These punctate structures diminished, and localization of full-length CNGC20-GFP to the vacuole increased, when it was co-expressed with the full-length CNGC19-mCherry. Vacuole membrane labelling was also detected in planta via immunoelectron microscopy using a CNGC20-antiserum on cryopreserved ultrathin sections of roots. We hypothesize that the role of group IV-A CNGCs is to mediate the movement of cations between the central vacuole and the cytosol in response to certain types of abiotic and biotic stress.

  1. “Structural Transformations in Ceramics: Perovskite-like Oxides and Group III, IV, and V Nitrides”

    SciTech Connect

    James P. Lewis , Dorian M. Hatch , and Harold T. Stokes

    2006-12-31

    1 Overview of Results and their Significance Ceramic perovskite-like oxides with the general formula (A. A0. ...)(B. B0. ...)O3and titanium-based oxides are of great technological interest because of their large piezoelectric and dielectric response characteristics.[1] In doped and nanoengineered forms, titantium dioxide finds increasing application as an organic and hydrolytic photocatalyst. The binary main-group-metal nitride compounds have undergone recent advancements of in-situ heating technology in diamond anvil cells leading to a burst of experimental and theoretical interest. In our DOE proposal, we discussed our unique theoretical approach which applies ab initio electronic calculations in conjunction with systematic group-theoretical analysis of lattice distortions to study two representative phase transitions in ceramic materials: (1) displacive phase transitions in primarily titanium-based perovskite-like oxide ceramics, and (2) reconstructive phase transitions in main-group nitride ceramics. A sub area which we have explored in depth is doped titanium dioxide electrical/optical properties.

  2. A Chakra-Based Model of Group Development.

    ERIC Educational Resources Information Center

    Gilchrist, Roger; Mikulas, William L.

    1993-01-01

    Describes a model for sequential stages of group development based on yogic chakra system. Compares chakra-based model with other models of group developmental stages. Using context of chakra system, specifies basic dynamic issues and leader interventions for each stage and discusses relationship of individual development to group process. (Author)

  3. RAGBEEF: a FORTRAN IV implementation of a time-dependent model for radionuclide contamination of beef

    SciTech Connect

    Pleasant, J C; McDowell-Boyer, L M; Killough, G G

    1982-06-01

    RAGBEEF is a FORTRAN IV program that calculates radionuclide concentrations in beef as a result of ingestion of contaminated feeds, pasture, and pasture soil by beef cattle. The model implemented by RAGBEEF is dynamic in nature, allowing the user to consider age- and season-dependent aspects of beef cattle management in estimating concentrations in beef. It serves as an auxiliary code to RAGTIME, previously documented by the authors, which calculates radionuclide concentrations in agricultural crops in a dynamic manner, but evaluates concentrations in beef for steady-state conditions only. The time-dependent concentrations in feeds, pasture, and pasture soil generated by RAGTIME are used as input to the RAGBEEF code. RAGBEEF, as presently implemented, calculates radionuclide concentrations in the muscle of age-based cohorts in a beef cattle herd. Concentrations in the milk of lactating cows are also calculated, but are assumed age-dependent as in RAGTIME. Radionuclide concentrations in beef and milk are described in RAGBEEF by a system of ordinary linear differential equations in which the transfer rate of radioactivity between compartments is proportional to the inventory of radioactivity in the source compartment. This system is solved by use of the GEAR package for solution of systems of ordinary differential equations. The accuracy of this solution is monitored at various check points by comparison with explicit solutions of Bateman-type equations. This report describes the age- and season-dependent considerations making up the RAGBEEF model, as well as presenting the equations which describe the model and a documentation of the associated computer code. Listings of the RAGBEEF and updated RAGTIME codes are provided in appendices, as are the results of a sample run of RAGBEEF and a description of recent modifications to RAGTIME.

  4. Performance modeling of the Ballard Mark IV solid polymer electrolyte fuel cell. 2: Empirical model development

    SciTech Connect

    Amphlett, J.C.; Baumert, R.M.; Mann, R.F.; Peppley, B.A.; Roberge, P.R. ); Harris, T.J. )

    1995-01-01

    A parametric model predicting the performance of a solid polymer electrolyte, proton exchange membrane (PEM) fuel cell has been developed using a combination of mechanistic and empirical modeling techniques. This paper details the empirical analysis which yielded the parametric coefficients employed in the model. A 28 run experiment covering a range of operating currents (50 to 300 ASF), temperatures (328 to 358 K), oxygen partial pressures (0.6 to 3.1 atm abs.) and hydrogen partial pressures (2.0 to 3.1 atm abs.) was conducted. Parametric equations for the activation overvoltage and the internal resistance of the fuel cell were obtained from linear regression. The factors to be employed in the linear regression had been previously determined through a mechanistic analysis of fuel cell processes. Activation overvoltage was modeled as a function of the operating temperature, the product of operating temperature, and the logarithm of the operating current, and the product of operating temperature and the logarithm of the oxygen concentration at the catalyst reaction sites. The internal resistance of the fuel cell was modeled as a function of the operating temperature and the current. Correlation of the empirical model to experimental data was very good. It is anticipated that the mechanistic validity yielded by the coupling of mechanistic and empirical modeling techniques will also allow for accurate predictive capabilities outside of the experimental range.

  5. Vanadium(V) and -(IV) complexes of anionic polysaccharides: Controlled release pharmaceutical formulations and models of vanadium biotransformation products.

    PubMed

    Kremer, Lauren E; McLeod, Andrew I; Aitken, Jade B; Levina, Aviva; Lay, Peter A

    2015-06-01

    Uncontrolled reactions in biological media are a main obstacle for clinical translation of V-based anti-diabetic or anti-cancer pro-drugs. We investigated the use of controlled-release pharmaceutical formulations to ameliorate this issue with a series of V(V) and (IV) complexes of anionic polysaccharides. Carboxymethyl cellulose, xanthan gum, or alginic acid formulations were prepared by the reactions of [VO4](3-) with one or two molar equivalents of biological reductants, L-ascorbic acid (AA) or L-cysteine (Cys), in the presence of excess polysaccharide at pH~7 or pH~4. XANES studies with the use of a previously developed library of model V(V), V(IV) and V(III) complexes showed that reactions in the presence of AA led mostly to the mixtures of five- and six-coordinate V(IV) species, while the reactions in the presence of Cys led predominantly to the mixtures of five- and six-coordinate V(V) species. The XANES spectra of some of these samples closely matched those reported previously for [VO4](3-) biotransformation products in isolated blood plasma, red blood cells, or cultured adipocytes, which supports the hypothesis that modified polysaccharides are major binders of V(V) and V(IV) in biological systems. Studies by EPR spectroscopy suggested predominant V(IV)-carboxylato binding in complexes with polysaccharides. One of the isolated products (a V(IV)-alginato complex) showed selective release of low-molecular-mass V species at pH~8, but not at pH~2, which makes it a promising lead for the development of V-containing formulations for oral administration that are stable in the stomach, but release the active ingredient in the intestines. PMID:25958254

  6. Generation IV benchmarking of TRISO fuel performance models under accident conditions. Modeling input data

    SciTech Connect

    Blaise Collin

    2014-09-01

    This document presents the benchmark plan for the calculation of particle fuel performance on safety testing experiments that are representative of operational accidental transients. The benchmark is dedicated to the modeling of fission product release under accident conditions by fuel performance codes from around the world, and the subsequent comparison to post-irradiation experiment (PIE) data from the modeled heating tests. The accident condition benchmark is divided into three parts: the modeling of a simplified benchmark problem to assess potential numerical calculation issues at low fission product release; the modeling of the AGR-1 and HFR-EU1bis safety testing experiments; and, the comparison of the AGR-1 and HFR-EU1bis modeling results with PIE data. The simplified benchmark case, thereafter named NCC (Numerical Calculation Case), is derived from ''Case 5'' of the International Atomic Energy Agency (IAEA) Coordinated Research Program (CRP) on coated particle fuel technology [IAEA 2012]. It is included so participants can evaluate their codes at low fission product release. ''Case 5'' of the IAEA CRP-6 showed large code-to-code discrepancies in the release of fission products, which were attributed to ''effects of the numerical calculation method rather than the physical model''[IAEA 2012]. The NCC is therefore intended to check if these numerical effects subsist. The first two steps imply the involvement of the benchmark participants with a modeling effort following the guidelines and recommendations provided by this document. The third step involves the collection of the modeling results by Idaho National Laboratory (INL) and the comparison of these results with the available PIE data. The objective of this document is to provide all necessary input data to model the benchmark cases, and to give some methodology guidelines and recommendations in order to make all results suitable for comparison with each other. The participants should read this document

  7. pH-responsive and photostable group IV metal oxide functionalized porous silicon platforms and novel applications of spectroscopic imaging methods for functional and hybrid materials analysis

    NASA Astrophysics Data System (ADS)

    Destino, Joel F.

    This dissertation covers two research topics that center on the spectroscopic characterization of functional materials. First, the performance (i.e. pH stability, photostability, shelf life) of novel photoluminescent group IV metal oxide functionalized porous silicon platforms is discussed. Spectroscopic techniques are used to provide insight into the chemistry of these substrates, and investigate pH-dependent PL response. The second section covers various novel applications of spectroscopic imaging methods. Colocalized Raman and atomic force microscopy and fluorescence imaging results for two- and three-component hybrid antifouling xerogel thin films are presented. Analysis investigates the relationship between surface structure, surface charge, surface pH and chemistry as it relates to antifouling performance. Lastly, practical aspects of tip-enhanced Raman spectroscopy are discussed and preliminary results of WS2 on Au are presented.

  8. Geographic structure evidenced in the toxic dinoflagellate Alexandrium pacificum Litaker (A. catenella - group IV (Whedon & Kofoid) Balech) along Japanese and Chinese coastal waters.

    PubMed

    Genovesi, Benjamin; Berrebi, Patrick; Nagai, Satoshi; Reynaud, Nathalie; Wang, Jinhui; Masseret, Estelle

    2015-09-15

    The intra-specific diversity and genetic structure within the Alexandrium pacificum Litaker (A. catenella - Group IV) populations along the Temperate Asian coasts, were studied among individuals isolated from Japan to China. The UPGMA dendrogram and FCA revealed the existence of 3 clusters. Assignment analysis suggested the occurrence of gene flows between the Japanese Pacific coast (cluster-1) and the Chinese Zhejiang coast (cluster-2). Human transportations are suspected to explain the lack of genetic difference between several pairs of distant Japanese samples, hardly explained by a natural dispersal mechanism. The genetic isolation of the population established in the Sea of Japan (cluster-3) suggested the existence of a strong ecological and geographical barrier. Along the Pacific coasts, the South-North current allows limited exchanges between Chinese and Japanese populations. The relationships between Temperate Asian and Mediterranean individuals suggested different scenario of large-scale dispersal mechanisms. PMID:26188429

  9. All-electron molecular Dirac-Hartree-Fock calculations: Properties of the group IV monoxides GeO, SnO and PbO

    NASA Technical Reports Server (NTRS)

    Dyall, Kenneth G.

    1991-01-01

    Dirac-Hartree-Fock calculations have been carried out on the ground states of the group IV monoxides GeO, SnO and PbO. Geometries, dipole moments and infrared data are presented. For comparison, nonrelativistic, first-order perturbation and relativistic effective core potential calculations have also been carried out. Where appropriate the results are compared with the experimental data and previous calculations. Spin-orbit effects are of great importance for PbO, where first-order perturbation theory including only the mass-velocity and Darwin terms is inadequate to predict the relativistic corrections to the properties. The relativistic effective core potential results show a larger deviation from the all-electron values than for the hydrides, and confirm the conclusions drawn on the basis of the hydride calculations.

  10. Control of the growth orientation and electrical properties of polycrystalline Cu2O thin films by group-IV elements doping

    NASA Astrophysics Data System (ADS)

    Ishizuka, Shogo; Akimoto, Katsuhiro

    2004-11-01

    The effects of group-IV element dopants on the structural and electrical properties of Cu2O thin films were studied. Similar dopant-induced behavior was found in the observed variations of the growth orientation and electrical properties of Si- and Ge-doped Cu2O thin films. Ge doping was found to induce electrically active acceptors with an activation energy of 0.18 eV, comparable to the 0.19 eV value of Si-doped Cu2O. These results suggest that locally formed silicate and germanate have the same effect on the structural and electrical properties of Cu2O. On the other hand, Sn and Pb likely act as donors when incorporated substitutionally onto Cu-lattice sites, although further study may be required to suppress self-compensation effects in Cu2O to achieve n-type conductivity.

  11. Group Modeling in Social Learning Environments

    ERIC Educational Resources Information Center

    Stankov, Slavomir; Glavinic, Vlado; Krpan, Divna

    2012-01-01

    Students' collaboration while learning could provide better learning environments. Collaboration assumes social interactions which occur in student groups. Social theories emphasize positive influence of such interactions on learning. In order to create an appropriate learning environment that enables social interactions, it is important to…

  12. Sensitivity of Urban Airshed Model (UAM-IV) calculated air pollutant concentrations to the vertical diffusion parameterization during convective meteorological situations

    SciTech Connect

    Nowacki, P.; Samson, P.J.; Sillman, S.

    1996-10-01

    It is shown that Urban Airshed Model (UAM-IV) calculated air pollutant concentrations during photochemical smog episodes in Atlanta, Georgia, depend strongly on the numerical parameterization of the daytime vertical diffusivity. Results found suggest that vertical mixing is overestimated by the UAM-IV during unstable daytime conditions, as calculated vertical diffusivity values exceed measured and comparable literature values. Although deviations between measured and UAM-IV calculated air pollutant concentrations may only in part be due the UAM-IV diffusivity parameterization, results indicate the large error potential in vertical diffusivity parameterization. Easily implemented enhancements to UAM-IV algorithms are proposed, thus improving UAM-IV modeling performance during unstable stratification. 38 refs., 14 figs., 1 tab.

  13. Group therapy model for refugee and torture survivors.

    PubMed

    Kira, Ibrahim A; Ahmed, Asha; Mahmoud, Vanessa; Wasim, Fatima

    2010-01-01

    The paper discusses the Center for Torture and Trauma Survivors' therapy group model for torture survivors and describes two of its variants: The Bashal group for African and Somali women and the Bhutanese multi-family therapy group. Group therapies in this model extend to community healing. Groups develop their cohesion to graduate to a social community club or initiate a community organization. New graduates from the group join the club and become part of the social advocacy process and of group and individual support and community healing. The BASHAL Somali women's group that developed spontaneously into a socio-political club for African women, and the Bhutanese family group that consciously developed into a Bhutanese community organization are discussed as two variants of this new model of group therapy with torture survivors. PMID:20952827

  14. Some Observations on Specifying Models of Group Performance.

    ERIC Educational Resources Information Center

    Goodman, Paul; And Others

    The purpose of this paper is to identify some critical dimensions in specifying a model of group performance. In the first section, the boundaries of the paper, e.g., work groups that produce some identifiable good or service, are discussed. In the second section some models of group performance are explored in order to illustrate theories of…

  15. Toward a Communication Competency Model of Group Leadership.

    ERIC Educational Resources Information Center

    Barge, J. Kevin; Hirokawa, Randy Y.

    1989-01-01

    Argues that current models of group leadership fail to illuminate the relationship between leadership and group performance. Presents an alternative model of leadership based on communication competencies, which are influenced by task complexity, group climate, and role relationships. A series of heuristic propositions are offered linking…

  16. Calorimetric, spectroscopic, and model studies provide insight into the transport of Ti(IV) by human serum transferrin.

    PubMed

    Tinoco, Arthur D; Incarvito, Christopher D; Valentine, Ann M

    2007-03-21

    Evidence suggests that transferrin can bind Ti(IV) in an unhydrolyzed form (without bound hydroxide or oxide) or in a hydrolyzed form. Ti(IV) coordination by N,N'-di(o-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED) at different pH values models the two forms of Ti(IV)-loaded transferrin spectrally and structurally. 13C NMR and stopped-flow kinetic experiments reveal that when the metal is delivered to the protein using an unhydrolyzed source, Ti(IV) can coordinate in the typical distorted octahedral environment with a bound synergistic anion. The crystal structure of TiHBED obtained at low pH models this type of coordination. The solution structure of the complex compares favorably with the solid state from pH 3.0 to 4.0, and the complex can be reduced with E1/2 = -641 mV vs NHE. Kinetic and thermodynamic competition studies at pH 3.0 reveal that Ti(citrate)3 reacts with HBED via a dissociative mechanism and that the stability of TiHBED (log beta = 34.024) is weaker than that of the Fe(III) complex. pH stability studies show that Ti(IV) hydrolyzes ligand waters at higher pH but still remains bound to HBED until pH 9.5. Similarly, at a pH greater than 8.0 the synergistic anion that binds Ti(IV) in transferrin is readily displaced by irreversible metal hydrolysis although the metal remains bound to the protein until pH 9.5. Thermal denaturation studies conducted optically and by differential scanning calorimetry reveal that Ti(IV)-bound transferrin experiences only minimal enhanced thermal stability unlike when Fe(III) is bound. The C- and N-lobe transition Tm values shift to a few degrees higher. The stability, competition, and redox studies performed provide insight into the possible mechanism of Ti2-Tf transport in cells. PMID:17315875

  17. Recursive renormalization group theory based subgrid modeling

    NASA Technical Reports Server (NTRS)

    Zhou, YE

    1991-01-01

    Advancing the knowledge and understanding of turbulence theory is addressed. Specific problems to be addressed will include studies of subgrid models to understand the effects of unresolved small scale dynamics on the large scale motion which, if successful, might substantially reduce the number of degrees of freedom that need to be computed in turbulence simulation.

  18. The Beyond the standard model working group: Summary report

    SciTech Connect

    G. Azuelos et al.

    2004-03-18

    In this working group we have investigated a number of aspects of searches for new physics beyond the Standard Model (SM) at the running or planned TeV-scale colliders. For the most part, we have considered hadron colliders, as they will define particle physics at the energy frontier for the next ten years at least. The variety of models for Beyond the Standard Model (BSM) physics has grown immensely. It is clear that only future experiments can provide the needed direction to clarify the correct theory. Thus, our focus has been on exploring the extent to which hadron colliders can discover and study BSM physics in various models. We have placed special emphasis on scenarios in which the new signal might be difficult to find or of a very unexpected nature. For example, in the context of supersymmetry (SUSY), we have considered: how to make fully precise predictions for the Higgs bosons as well as the superparticles of the Minimal Supersymmetric Standard Model (MSSM) (parts III and IV); MSSM scenarios in which most or all SUSY particles have rather large masses (parts V and VI); the ability to sort out the many parameters of the MSSM using a variety of signals and study channels (part VII); whether the no-lose theorem for MSSM Higgs discovery can be extended to the next-to-minimal Supersymmetric Standard Model (NMSSM) in which an additional singlet superfield is added to the minimal collection of superfields, potentially providing a natural explanation of the electroweak value of the parameter {micro} (part VIII); sorting out the effects of CP violation using Higgs plus squark associate production (part IX); the impact of lepton flavor violation of various kinds (part X); experimental possibilities for the gravitino and its sgoldstino partner (part XI); what the implications for SUSY would be if the NuTeV signal for di-muon events were interpreted as a sign of R-parity violation (part XII). Our other main focus was on the phenomenological implications of extra

  19. African American Children: A Culturally Sensitive Model for Group Practice.

    ERIC Educational Resources Information Center

    Dziegielewski, Sophia F.; Leon, Ana M.; Green, Cheryl E.

    1998-01-01

    Describes a time-limited group model of intervention based on culturally sensitive practice for African-American children, ages 8-12 years old. This group model emphasizes the role of social workers in providing culturally sensitive treatment; introduces this specific model for practice in the short-term treatment setting; and provides specific…

  20. The Lake Superior Oronto Group, a middle Proterozoic exploration model for the late Proterozoic Chuar Group of the Grand Canyon

    SciTech Connect

    Dickas, A.B. ); Mudrey, M.G. Jr )

    1992-04-01

    The Lake Superior Oronto Group and the Grand Canyon Chuar Group are the most significant Precambrian hydrocarbon targets within the conterminous United States. These frontier terrains share common Proterozoic age, comparable total organic carbon source rock values, association with Indian-interest properties, plus similarities in reservoir, trap, and maturation characteristics. Extensively studied since 1980, the exploration philosophy applied to the Oronto Group is presented as a model for Chuar Group hydrocarbon evaluation. Hydrocarbon shows have been reported since 1852 from middle Proterozoic rocks of the Lake Superior basin. Occurrences include stains within stromatolitic facies of the Copper Harbor Conglomerate, live subsurface seeps within Nonesuch units in the White Pine copper mine of Michigan, and impsonite-like inclusions within calcite veins of the Freda Formation. These formations compose the Oronto Group, a synrift package infilling the Lake Superior basin of the mid-continent rift system. Seep analyses identify a low sulfur (0.02%), paraffinic (67%), 34 API crude indirectly dated (Rb/Sr) at a minimum of 1047{plus minus}35 Ma. Nonesuch Formation source shales are present within both central horst structures and flank half-grabens. Reservoir-quality criteria are associated with adjacent Copper Harbor and overlying Freda Formation units. Seismically identified traps range from anticlinal and drag folding to onlap, stratigraphic, and unconformity closures. The Lake Superior segment of the mid-continent rift system is subdivided into four structural units (I-IV). Association of oil seeps with stratiform copper deposits (unit III) suggests evidence of geochemical symbiosis. This crude entered oil-window status circa 1.0 Ga due to migrating cupriferous thermal systems.

  1. Group-IV midinfrared plasmonics

    NASA Astrophysics Data System (ADS)

    Biagioni, Paolo; Frigerio, Jacopo; Samarelli, Antonio; Gallacher, Kevin; Baldassarre, Leonetta; Sakat, Emilie; Calandrini, Eugenio; Millar, Ross W.; Giliberti, Valeria; Isella, Giovanni; Paul, Douglas J.; Ortolani, Michele

    2015-01-01

    The use of heavily doped semiconductors to achieve plasma frequencies in the mid-IR has been recently proposed as a promising way to obtain high-quality and tunable plasmonic materials. We introduce a plasmonic platform based on epitaxial n-type Ge grown on standard Si wafers by means of low-energy plasma-enhanced chemical vapor deposition. Due to the large carrier concentration achieved with P dopants and to the compatibility with the existing CMOS technology, SiGe plasmonics hold promises for mid-IR applications in optoelectronics, IR detection, sensing, and light harvesting. As a representative example, we show simulations of mid-IR plasmonic waveguides based on the experimentally retrieved dielectric constants of the grown materials.

  2. Hydrolysis of the RNA model substrate catalyzed by a binuclear Zr(IV)-substituted Keggin polyoxometalate.

    PubMed

    Luong, Thi Kim Nga; Absillis, Gregory; Shestakova, Pavletta; Parac-Vogt, Tatjana N

    2015-09-21

    The reactivity and solution behaviour of the binuclear Zr(IV)-substituted Keggin polyoxometalate (Et2NH2)8[{α-PW11O39Zr(μ-OH)(H2O)}2]·7H2O (ZrK 2 : 2) towards phosphoester bond hydrolysis of the RNA model substrate 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP) was investigated at different reaction conditions (pD, temperature, concentration, and ionic strength). The hydrolysis of the phosphoester bond of HPNP, followed by means of (1)H NMR spectroscopy, proceeded with an observed rate constant, kobs = 11.5(±0.42) × 10(-5) s(-1) at pD 6.4 and 50 °C, representing a 530-fold rate enhancement in comparison with the spontaneous hydrolysis of HPNP. (1)H and (31)P NMR spectra indicate that at these reaction conditions the only products of hydrolysis are p-nitrophenol and the corresponding cyclic phosphate ester. The pD dependence of kobs exhibits a bell-shaped profile, with the fastest rate observed at pD 6.4. The formation constant (Kf = 455 M(-1)) and catalytic rate constant (kc = 42 × 10(-5) s(-1)) for the HPNP-ZrK 2 : 2 complex, activation energy (Ea) of 63.35 ± 1.82 kJ mol(-1), enthalpy of activation (ΔH(‡)) of 60.60 ± 2.09 kJ mol(-1), entropy of activation (ΔS(‡)) of -133.70 ± 6.13 J mol(-1) K(-1), and Gibbs activation energy (ΔG(‡)) of 102.05 ± 0.13 kJ mol(-1) at 37 °C were calculated from kinetic experiments. Binding between ZrK 2 : 2 and the P-O bond of HPNP was evidenced by the change in the (31)P chemical shift and signal line-broadening of the (31)P atom in HPNP upon addition of ZrK 2 : 2. Based on (31)P NMR experiments and isotope effect studies, a mechanism for HPNP hydrolysis in the presence of ZrK 2 : 2 was proposed. PMID:26256057

  3. Tretinoin Nanogel 0.025% Versus Conventional Gel 0.025% in Patients with Acne Vulgaris: A Randomized, Active Controlled, Multicentre, Parallel Group, Phase IV Clinical Trial

    PubMed Central

    Chandrashekhar, B S; Anitha, M.; Ruparelia, Mukesh; Vaidya, Pradyumna; Aamir, Riyaz; Shah, Sunil; Thilak, S; Aurangabadkar, Sanjeev; Pal, Sandeep; Saraswat, Abir

    2015-01-01

    Background: Conventional topical tretinoin formulation is often associated with local adverse events. Nanogel formulation of tretinoin has good physical stability and enables good penetration of tretinoin into the pilo-sebaceous glands. Aim: The present study was conducted to assess the efficacy and safety of a nanogel formulation of tretinoin as compared to its conventional gel formulation in the treatment of acne vulgaris of the face. Materials and Methods: This randomized, active controlled, multicentric, phase IV clinical trial evaluated the treatment of patients with acne vulgaris of the face by the two gel formulations locally applied once daily at night for 12 wk. Acne lesion counts (inflammatory, non-inflammatory & total) and severity grading were carried out on the monthly scheduled visits along with the tolerability assessments. Results: A total of 207 patients were randomized in the study. Reductions in the total (72.9% vs. 65.0%; p = 0.03) and inflammatory (78.1% vs. 66.9%; p = 0.02) acne lesions were reported to be significantly greater with the nanogel formulation as compared to the conventional gel formulation. Local adverse events were significantly less (p = 0.04) in the nanogel group (13.3%) as compared to the conventional gel group (24.7%). Dryness was the most common adverse event reported in both the treatment groups while peeling of skin, burning sensation and photosensitivity were reported in patients using the conventional gel only. Conclusion: In the treatment of acne vulgaris of the face, tretinoin nanogel formulation appears to be more effective and better tolerated than the conventional gel formulation. PMID:25738069

  4. Theoretical Investigations and Density Functional Theory Based Quantitative Structure–Activity Relationships Model for Novel Cytotoxic Platinum(IV) Complexes

    PubMed Central

    2012-01-01

    Octahedral platinum(IV) complexes are promising candidates in the fight against cancer. In order to rationalize the further development of this class of compounds, detailed studies on their mechanisms of action, toxicity, and resistance must be provided and structure–activity relationships must be drawn. Herein, we report on theoretical and QSAR investigations of a series of 53 novel bis-, tris-, and tetrakis(carboxylato)platinum(IV) complexes, synthesized and tested for cytotoxicity in our laboratories. The hybrid DFT functional wb97x was used for optimization of the structure geometry and calculation of the descriptors. Reliable and robust QSAR models with good explanatory and predictive properties were obtained for both the cisplatin sensitive cell line CH1 and the intrinsically cisplatin resistant cell line SW480, with a set of four descriptors. PMID:23214999

  5. Gifted Parent Groups: The SENG Model. 2nd Edition

    ERIC Educational Resources Information Center

    DeVries, Arlene R.; Webb, James T.

    2007-01-01

    This manual provides the essential information for persons wishing to conduct SENG Model parent support groups for parents of gifted children. Each week, parents in the group read a chapter of "A Parent's Guide to Gifted Children," and then discuss the concepts in the chapter, led by the group facilitator. Parents support one another in practicing…

  6. Chemistry in disks. IV. Benchmarking gas-grain chemical models with surface reactions

    NASA Astrophysics Data System (ADS)

    Semenov, D.; Hersant, F.; Wakelam, V.; Dutrey, A.; Chapillon, E.; Guilloteau, St.; Henning, Th.; Launhardt, R.; Piétu, V.; Schreyer, K.

    2010-11-01

    Context. We describe and benchmark two sophisticated chemical models developed by the Heidelberg and Bordeaux astrochemistry groups. Aims: The main goal of this study is to elaborate on a few well-described tests for state-of-the-art astrochemical codes covering a range of physical conditions and chemical processes, in particular those aimed at constraining current and future interferometric observations of protoplanetary disks. Methods: We considered three physical models: a cold molecular cloud core, a hot core, and an outer region of a T Tauri disk. Our chemical network (for both models) is based on the original gas-phase osu_03_2008 ratefile and includes gas-grain interactions and a set of surface reactions for the H-, O-, C-, S-, and N-bearing molecules. The benchmarking was performed with the increasing complexity of the considered processes: (1) the pure gas-phase chemistry, (2) the gas-phase chemistry with accretion and desorption, and (3) the full gas-grain model with surface reactions. The chemical evolution is modeled within 109 years using atomic initial abundances with heavily depleted metals and hydrogen in its molecular form. Results: The time-dependent abundances calculated with the two chemical models are essentially the same for all considered physical cases and for all species, including the most complex polyatomic ions and organic molecules. This result, however, required a lot of effort to make all necessary details consistent through the model runs, e.g., definition of the gas particle density, density of grain surface sites, or the strength and shape of the UV radiation field. Conclusions: The reference models and the benchmark setup, along with the two chemical codes and resulting time-dependent abundances are made publicly available on the internet. This will facilitate and ease the development of other astrochemical models and provide nonspecialists with a detailed description of the model ingredients and requirements to analyze the cosmic

  7. A Model for Teaching Group Dynamics to Occupational Therapy Students.

    ERIC Educational Resources Information Center

    Kautzmann, Lisette

    A model for teaching group dynamics to undergraduate occupational therapy students was developed. The model incorporated adult education methodology in the teaching of group leadership and personal growth. A literature review was undertaken to identify the purpose and components of laboratory education, which was recognized as the preferred method…

  8. The Punctuated-Tuckman: Towards a New Group Development Model

    ERIC Educational Resources Information Center

    Hurt, Andrew C.; Trombley, Sarah M.

    2007-01-01

    Two commonly accepted theories of group development are the Tuckman model (Tuckman & Jensen, 1977) and the Punctuated-Equilibrium model (Gersick, 1988). Critiques of both are that they assume linear development and that they fail to account for outside influences. In contrast, Tubbs (2004) suggests that group development should be viewed from a…

  9. Clinicians' judgments of clinical utility: a comparison of the DSM-IV with dimensional models of general personality.

    PubMed

    Lowe, Jennifer Ruth; Widiger, Thomas A

    2009-06-01

    Clinical utility, or the usefulness of a diagnostic system in clinical practice, has been identified as a potential limitation of alternative dimensional models of personality disorder, such as the five-factor model (FFM; McCrae & Costa, 1990), the Temperament and Character Inventory (TCI; Cloninger, 2000), the Multidimensional Personality Questionnaire (MPQ; Tellegen & Waller, 1987), and the Shedler & Westen Assessment Procedure-200 (SWAP-200; Shedler & Westen, 1998). Both proponents of and opponents to dimensional models of personality disorder have suggested that their clinical utility be assessed in preparation for DSM-V (e.g., Rounsaville et al., 2002; First et al., 2002; Verheul, 2005; First, 2005). Samuel & Widiger (2006) found the FFM to have significantly greater clinical utility than the existing diagnostic categories. In the current study, 1,572 practicing psychologists were asked to describe one of three cases using the DSM-IV and the constructs of one of four alternative dimensional models (FFM, TCI, MPQ, SWAP). Clinicians then rated each model on six aspects of clinical utility. Results indicate that clinicians find dimensional models to be higher in clinical utility than the DSM-IV on five of the six aspects of clinical utility, but not significantly different from each other. Implications of these findings are discussed. PMID:19538078

  10. Important role of the non-uniform Fe distribution for the ferromagnetism in group-IV-based ferromagnetic semiconductor GeFe

    SciTech Connect

    Wakabayashi, Yuki K.; Ohya, Shinobu; Ban, Yoshisuke; Tanaka, Masaaki

    2014-11-07

    We investigate the growth-temperature dependence of the properties of the group-IV-based ferromagnetic semiconductor Ge{sub 1−x}Fe{sub x} films (x = 6.5% and 10.5%), and reveal the correlation of the magnetic properties with the lattice constant, Curie temperature (T{sub C}), non-uniformity of Fe atoms, stacking-fault defects, and Fe-atom locations. While T{sub C} strongly depends on the growth temperature, we find a universal relationship between T{sub C} and the lattice constant, which does not depend on the Fe content x. By using the spatially resolved transmission-electron diffractions combined with the energy-dispersive X-ray spectroscopy, we find that the density of the stacking-fault defects and the non-uniformity of the Fe concentration are correlated with T{sub C}. Meanwhile, by using the channeling Rutherford backscattering and particle-induced X-ray emission measurements, we clarify that about 15% of the Fe atoms exist on the tetrahedral interstitial sites in the Ge{sub 0.935}Fe{sub 0.065} lattice and that the substitutional Fe concentration is not correlated with T{sub C}. Considering these results, we conclude that the non-uniformity of the Fe concentration plays an important role in determining the ferromagnetic properties of GeFe.

  11. DSM-IV-defined anxiety disorder symptoms in a middle-childhood-aged group of Malaysian children using the Spence Children's Anxiety Scale.

    PubMed

    Ahmadi, Atefeh; Mustaffa, Mohamed Sharif; Udin, Amirmudin; Haghdoost, AliAkbar

    2016-03-01

    Introduction Pediatric anxiety disorders are the most common mental health disorders in the middle-childhood age group. The purpose of this study is to assess anxiety disorder symptoms, as defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV), in a large community sample of low socioeconomic level rural children and to investigate some of the psychometric properties (internal consistency, construct and convergent validity and items rated as often or always experienced) of the Malay version of the Spence Children's Anxiety Scale - Child version (SCAS-C). Method Six hundred children aged 9-11 and 424 of their parents completely answered the child or parent versions of the SCAS. Results Results indicated that the internal reliability of subscales were moderate to adequate. Significant correlations between child and parent reports supported the measure's concurrent validity. Additionally, anxiety levels in this Malaysian sample were lower than among South-African children and higher than among their Western peers. There were both similarities and differences between symptom items reported as often or always experienced by Malaysian students and by children from other cultures. Confirmatory factor analysis provided evidence of the existence of five inter-correlated factors for anxiety disorders based on SCAS-C. Conclusion Although some of the instrument's psychometric properties deviated from those observed in some other countries, it nevertheless appears to be useful for assessing childhood anxiety symptoms in this country. PMID:27007941

  12. Carrier transport properties of the Group-IV ferromagnetic semiconductor Ge{sub 1-x}Fe{sub x} with and without boron doping

    SciTech Connect

    Ban, Yoshisuke Wakabayashi, Yuki; Akiyama, Ryota; Nakane, Ryosho; Tanaka, Masaaki

    2014-09-15

    We have investigated the transport and magnetic properties of group-IV ferromagnetic semiconductor Ge{sub 1-x}Fe{sub x} films (x = 1.0 and 2.3%) with and without boron doping grown by molecular beam epitaxy (MBE). In order to accurately measure the transport properties of 100-nm-thick Ge{sub 1-x}Fe{sub x} films, (001)-oriented silicon-on-insulator (SOI) wafers with an ultra-thin Si body layer (∼5 nm) were used as substrates. Owing to the low Fe content, the hole concentration and mobility in the Ge{sub 1-x}Fe{sub x} films were exactly estimated by Hall measurements because the anomalous Hall effect in these films was found to be negligibly small. By boron doping, we increased the hole concentration in Ge{sub 1-x}Fe{sub x} from ∼10{sup 18} cm{sup −3} to ∼10{sup 20} cm{sup −3} (x = 1.0%) and to ∼10{sup 19} cm{sup −3} (x = 2.3%), but no correlation was observed between the hole concentration and magnetic properties. This result presents a contrast to the hole-induced ferromagnetism in III-V ferromagnetic semiconductors.

  13. Endomicrobium proavitum, the first isolate of Endomicrobia class. nov. (phylum Elusimicrobia)--an ultramicrobacterium with an unusual cell cycle that fixes nitrogen with a Group IV nitrogenase.

    PubMed

    Zheng, Hao; Dietrich, Carsten; Radek, Renate; Brune, Andreas

    2016-01-01

    The bacterial tree contains many deep-rooting clades without any cultured representatives. One such clade is 'Endomicrobia', a class-level lineage in the phylum Elusimicrobia represented so far only by intracellular symbionts of termite gut flagellates. Here, we report the isolation and characterization of the first free-living member of this clade from sterile-filtered gut homogenate of defaunated (starch-fed) Reticulitermes santonensis. Strain Rsa215 is a strictly anaerobic ultramicrobacterium that grows exclusively on glucose, which is fermented to lactate, acetate, hydrogen and CO2. Ultrastructural analysis revealed a Gram-negative cell envelope and a peculiar cell cycle. The genome contains a single set of nif genes that encode homologues of Group IV nitrogenases, which were so far considered to have functions other than nitrogen fixation. We documented nitrogenase activity and diazotrophic growth by measuring acetylene reduction activity and (15)N2 incorporation into cell mass, and demonstrated that transcription of nifH and nitrogenase activity occur only in the absence of ammonium. Based on the ancestral relationship to 'Candidatus Endomicrobium trichonymphae' and other obligate endosymbionts, we propose the name 'Endomicrobium proavitum' gen. nov., sp. nov. for the first isolate of this lineage and the name 'Endomicrobia' class. nov. for the entire clade. PMID:26119974

  14. Synthesis of Ge1-xSnx alloys by ion implantation and pulsed laser melting: Towards a group IV direct bandgap material

    NASA Astrophysics Data System (ADS)

    Tran, Tuan T.; Pastor, David; Gandhi, Hemi H.; Smillie, Lachlan A.; Akey, Austin J.; Aziz, Michael J.; Williams, J. S.

    2016-05-01

    The germanium-tin (Ge1-xSnx) material system is expected to be a direct bandgap group IV semiconductor at a Sn content of 6.5 - 11 at . % . Such Sn concentrations can be realized by non-equilibrium deposition techniques such as molecular beam epitaxy or chemical vapour deposition. In this report, the combination of ion implantation and pulsed laser melting is demonstrated to be an alternative promising method to produce a highly Sn concentrated alloy with a good crystal quality. The structural properties of the alloys such as soluble Sn concentration, strain distribution, and crystal quality have been characterized by Rutherford backscattering spectrometry, Raman spectroscopy, x ray diffraction, and transmission electron microscopy. It is shown that it is possible to produce a high quality alloy with up to 6.2 at . % Sn . The optical properties and electronic band structure have been studied by spectroscopic ellipsometry. The introduction of substitutional Sn into Ge is shown to either induce a splitting between light and heavy hole subbands or lower the conduction band at the Γ valley. Limitations and possible solutions to introducing higher Sn content into Ge that is sufficient for a direct bandgap transition are also discussed.

  15. Fabrication of a Core-Shell-Type Photocatalyst via Photodeposition of Group IV and V Transition Metal Oxyhydroxides: An Effective Surface Modification Method for Overall Water Splitting.

    PubMed

    Takata, Tsuyoshi; Pan, Chengsi; Nakabayashi, Mamiko; Shibata, Naoya; Domen, Kazunari

    2015-08-01

    The design of optimal surface structures for photocatalysts is a key to efficient overall water splitting into H2 and O2. A unique surface modification method was devised for a photocatalyst to effectively promote overall water splitting. Photodeposition of amorphous oxyhydroxides of group IV and V transition metals (Ti, Nb, Ta) over a semiconductor photocatalyst from corresponding water-soluble metal peroxide complexes was examined. In this method, amorphous oxyhydroxide covered the whole surface of the photocatalyst particles, creating a core-shell structure. The water splitting behavior of the novel core-shell-type photocatalyst in relation to the permeation behavior of the coating layer was investigated in detail. Overall water splitting proceeded successfully after the photodeposition, owing to the prevention of the reverse reaction. The photodeposited oxyhydroxide layers were found to function as molecular sieves, selectively filtering reactant and product molecules. By exploiting the selective permeability of the coating layer, redox reactions on the photocatalyst surface could be suitably controlled, which resulted in successful overall water splitting. PMID:26161678

  16. Computational modeling studies of the structures and properties of organotin(IV) and stannyl-thioether systems with comparisons to X-ray crystallography

    NASA Astrophysics Data System (ADS)

    Stem Joseph, Michelle R.

    Controlling the toxic effects of organotin(IV) compounds involves engineering the structure of the molecules to optimize their properties. Molecular engineering, coupled with improved capabilities to generate reliable computational optimization models (COMs), will enable researchers to have greater success at harnessing the highly specific cytotoxicity of organotins. For example, as the thio n ligand phenyl groups were replaced with Cl atoms, the S-Sn intramolecularity was strengthened, the bond distance decreased, and the stannyl tetrahedral structure was deformed from its triphenyl conformation. With each substitution, conformation deformations lowered the damaging bioactivity levels of thio n. Bonding various ligands to organotin(IV) compounds to control structure and electron density, is a significant method of using steric or chemical effects to control the properties of these compounds. Numerous computational optimization treatments (COTs) were applied to o-1-methylthio-benzyl-2-phenylxchloroystannane (thion, where x + y = 3). Exhaustive comparative analyses ascertained the accuracies of the computational optimized models (COMs) generated from each COT relative to experimental data, such as X-ray crystallography (XRC) and solid-state 119Sn NMR (NMR). Further analyses included: (a) three R2SnCl2 structures, (Me2SnCl 2, MePhSnCl2, Ph2SnCl2) such that R = methyl or phenyl, and (b) MeSnCl3 and Me3SnCl, where Me = methyl, and (c) the bimolecular complex, Ph2POCH2Cl·Ph 2SnCl2. This research determined for organotin(IV) molecules, thion : (1) reliable COTs, (2) validation methods, (3) complexities of creating reliable models, (4) hyperconjugation extended to include unexpected thioether OT molecular features, (5) a substitution method to control intramolecularity and hypercoordination, and (6) pre-optimization COM treatments and pre-optimization conformation changes that may influence final conformations. As external validation of the methodology, research on

  17. TOWARD UNDERSTANDING THE B[e] PHENOMENON. IV. MODELING OF IRAS 00470+6429

    SciTech Connect

    Carciofi, A. C.; Miroshnichenko, A. S.; Bjorkman, J. E.

    2010-10-01

    FS CMa type stars are a recently described group of objects with the B[e] phenomenon which exhibits strong emission-line spectra and strong IR excesses. In this paper, we report the first attempt for a detailed modeling of IRAS 00470+6429, for which we have the best set of observations. Our modeling is based on two key assumptions: the star has a main-sequence luminosity for its spectral type (B2) and the circumstellar (CS) envelope is bimodal, composed of a slowly outflowing disklike wind and a fast polar wind. Both outflows are assumed to be purely radial. We adopt a novel approach to describe the dust formation site in the wind that employs timescale arguments for grain condensation and a self-consistent solution for the dust destruction surface. With the above assumptions we were able to satisfactorily reproduce many observational properties of IRAS 00470+6429, including the H I line profiles and the overall shape of the spectral energy distribution. Our adopted recipe for dust formation proved successful in reproducing the correct amount of dust formed in the CS envelope. Possible shortcomings of our model, as well as suggestions for future improvements, are discussed.

  18. Group therapy for refugees and torture survivors: treatment model innovations.

    PubMed

    Kira, Ibrahim A; Ahmed, Asha; Wasim, Fatima; Mahmoud, Vanessa; Colrain, Joanna; Rai, Dhan

    2012-01-01

    The paper discusses varieties of group therapies with refugees and torture survivors and the logic behind enhancing traditional group therapies to fit the unique experiences of refugees and torture survivors. It discusses some lessons learned from practice and from empirical research and some recommended adaptations. Finally, it discusses the Center for Torture and Trauma Survivors' therapy group model for torture survivors and describes two of its variants: The Bashal group for African and Somali women and the Bhutanese multi-family therapy group. Group therapies, in this model, extend to community healing. One of the essential and innovative features of the model is that it focuses not only on treating individual psychopathology but also extends to community healing by promoting the development of social clubs and organizations that promote the values and culture of the graduates of the therapy group and the continuation of social support. New graduates from the group join the club and become part of the social advocacy process and of group and community support and healing. This model adds an ecological dimension to the traditional group therapy. PMID:22229369

  19. Evidence from mathematical modeling that carbonic anhydrase II and IV enhance CO2 fluxes across Xenopus oocyte plasma membranes

    PubMed Central

    Musa-Aziz, Raif; Boron, Walter F.

    2014-01-01

    Exposing an oocyte to CO2/HCO3− causes intracellular pH (pHi) to decline and extracellular-surface pH (pHS) to rise to a peak and decay. The two companion papers showed that oocytes injected with cytosolic carbonic anhydrase II (CA II) or expressing surface CA IV exhibit increased maximal rate of pHi change (dpHi/dt)max, increased maximal pHS changes (ΔpHS), and decreased time constants for pHi decline and pHS decay. Here we investigate these results using refinements of an earlier mathematical model of CO2 influx into a spherical cell. Refinements include 1) reduced cytosolic water content, 2) reduced cytosolic diffusion constants, 3) refined CA II activity, 4) layer of intracellular vesicles, 5) reduced membrane CO2 permeability, 6) microvilli, 7) refined CA IV activity, 8) a vitelline membrane, and 9) a new simulation protocol for delivering and removing the bulk extracellular CO2/HCO3− solution. We show how these features affect the simulated pHi and pHS transients and use the refined model with the experimental data for 1.5% CO2/10 mM HCO3− (pHo = 7.5) to find parameter values that approximate ΔpHS, the time to peak pHS, the time delay to the start of the pHi change, (dpHi/dt)max, and the change in steady-state pHi. We validate the revised model against data collected as we vary levels of CO2/HCO3− or of extracellular HEPES buffer. The model confirms the hypothesis that CA II and CA IV enhance transmembrane CO2 fluxes by maximizing CO2 gradients across the plasma membrane, and it predicts that the pH effects of simultaneously implementing intracellular and extracellular-surface CA are supra-additive. PMID:24965589

  20. Evidence from mathematical modeling that carbonic anhydrase II and IV enhance CO2 fluxes across Xenopus oocyte plasma membranes.

    PubMed

    Occhipinti, Rossana; Musa-Aziz, Raif; Boron, Walter F

    2014-11-01

    Exposing an oocyte to CO2/HCO3 (-) causes intracellular pH (pHi) to decline and extracellular-surface pH (pHS) to rise to a peak and decay. The two companion papers showed that oocytes injected with cytosolic carbonic anhydrase II (CA II) or expressing surface CA IV exhibit increased maximal rate of pHi change (dpHi/dt)max, increased maximal pHS changes (ΔpHS), and decreased time constants for pHi decline and pHS decay. Here we investigate these results using refinements of an earlier mathematical model of CO2 influx into a spherical cell. Refinements include 1) reduced cytosolic water content, 2) reduced cytosolic diffusion constants, 3) refined CA II activity, 4) layer of intracellular vesicles, 5) reduced membrane CO2 permeability, 6) microvilli, 7) refined CA IV activity, 8) a vitelline membrane, and 9) a new simulation protocol for delivering and removing the bulk extracellular CO2/HCO3 (-) solution. We show how these features affect the simulated pHi and pHS transients and use the refined model with the experimental data for 1.5% CO2/10 mM HCO3 (-) (pHo = 7.5) to find parameter values that approximate ΔpHS, the time to peak pHS, the time delay to the start of the pHi change, (dpHi/dt)max, and the change in steady-state pHi. We validate the revised model against data collected as we vary levels of CO2/HCO3 (-) or of extracellular HEPES buffer. The model confirms the hypothesis that CA II and CA IV enhance transmembrane CO2 fluxes by maximizing CO2 gradients across the plasma membrane, and it predicts that the pH effects of simultaneously implementing intracellular and extracellular-surface CA are supra-additive. PMID:24965589

  1. Group force mobility model and its obstacle avoidance capability

    NASA Astrophysics Data System (ADS)

    Williams, Sean A.; Huang, Dijiang

    2009-10-01

    Many mobility models attempt to provide realistic simulation to many real world scenarios. However, existing mobility models, such as RPGM [X. Hong, M. Gerla, G. Pei, C. Chiang, A group mobility model for ad hoc wireless networks, in: Proceedings of ACM/IEEE MSWiM'99, Seattle, WA, August 1999, pp. 53-60] and others, fail to address many aspects. These limitations range from mobile node (MN) collision avoidance, obstacle avoidance, and the interaction of MNs within a group. Our research, the group force mobility model (GFMM) [S.A. Williams, D. Huang, A group force mobility model, Appeared at 9th Communications and Networking Simulation Symposium, April 2006], proposes a novel idea which introduces the concept of attraction and repulsion forces to address many of these limitations. Williams and Huang [A group force mobility model, Appeared at 9th Communications and Networking Simulation Symposium, April 2006] described some of the limitations and drawbacks that many models neglect. This model effectively simulates the interaction of MNs within a group, the interaction of groups to one another, the coherency of a group, and the avoidance of collision with groups, nodes, and obstacles. This paper provides an overview of GFMM and particularly illustrates the GFMM's ability to avoid collision with obstacles, which is a vital property to posses in order to provide a realistic simulaition. We compare our model with the commonly used RPGM model and provide statistical assessments based on connectivity metrics such as link changed, link duration, and relative speed. All will be detailed and explained in this paper.

  2. Two Models for Semi-Supervised Terrorist Group Detection

    NASA Astrophysics Data System (ADS)

    Ozgul, Fatih; Erdem, Zeki; Bowerman, Chris

    Since discovery of organization structure of offender groups leads the investigation to terrorist cells or organized crime groups, detecting covert networks from crime data are important to crime investigation. Two models, GDM and OGDM, which are based on another representation model - OGRM are developed and tested on nine terrorist groups. GDM, which is basically depending on police arrest data and “caught together” information and OGDM, which uses a feature matching on year-wise offender components from arrest and demographics data, performed well on terrorist groups, but OGDM produced high precision with low recall values. OGDM uses a terror crime modus operandi ontology which enabled matching of similar crimes.

  3. Clinician's judgments of the utility of the DSM-IV and five-factor models for personality disordered patients.

    PubMed

    Mullins-Sweatt, Stephanie N; Widiger, Thomas A

    2011-08-01

    The purpose of the current study was to examine the clinical utility of the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 2000) and the Five Factor Model of personality disorder (FFM; Widiger, Costa, & McCrae, 2002) in describing personality pathology. In the current study, practicing psychologists described one or two of their personality disordered patients in terms of the FFM and DSM models. In some instances, the patient was someone who met the criteria for one of the 10 DSM-IV personality disorders; in others, the patient was someone who received a diagnosis of personality disorder, not otherwise specified. Participants then rated each model on six aspects of clinical utility. The current study found that the FFM was consistently rated higher than the DSM model in terms of four of the six aspects of clinical utility. Across both cases, the clinicians rated the FFM as significantly more useful with respect to its ability to provide a global description of the individual's personality, to communicate information to clients, and to encompass all of the individual's important personality difficulties. PMID:21838562

  4. Asteroids IV

    NASA Astrophysics Data System (ADS)

    Michel, Patrick; DeMeo, Francesca E.; Bottke, William F.

    Asteroids are fascinating worlds. Considered the building blocks of our planets, many of the authors of this book have devoted their scientific careers to exploring them with the tools of our trade: ground- and spacebased observations, in situ space missions, and studies that run the gamut from theoretical modeling efforts to laboratory work. Like fossils for paleontologists, or DNA for geneticists, they allow us to construct a veritable time machine and provide us with tantalizing glimpses of the earliest nature of our solar system. By investigating them, we can probe what our home system was like before life or even the planets existed. The origin and evolution of life on our planet is also intertwined with asteroids in a different way. It is believed that impacts on the primordial Earth may have delivered the basic components for life, with biology favoring attributes that could more easily survive the aftermath of such energetic events. In this fashion, asteroids may have banished many probable avenues for life to relative obscurity. Similarly, they may have also prevented our biosphere from becoming more complex until more recent eras. The full tale of asteroid impacts on the history of our world, and how human life managed to emerge from myriad possibilities, has yet to be fully told. The hazard posed by asteroid impacts to our civilization is low but singular. The design of efficient mitigation strategies strongly relies on asteroid detection by our ground- and spacebased surveys as well as knowledge of their physical properties. A more positive motivation for asteroid discovery is that the proximity of some asteroids to Earth may allow future astronauts to harvest their water and rare mineral resources for use in exploration. A key goal of asteroid science is therefore to learn how humans and robotic probes can interact with asteroids (and extract their materials) in an efficient way. We expect that these adventures may be commonplace in the future

  5. Asteroids IV

    NASA Astrophysics Data System (ADS)

    Michel, Patrick; DeMeo, Francesca E.; Bottke, William F.

    Asteroids are fascinating worlds. Considered the building blocks of our planets, many of the authors of this book have devoted their scientific careers to exploring them with the tools of our trade: ground- and spacebased observations, in situ space missions, and studies that run the gamut from theoretical modeling efforts to laboratory work. Like fossils for paleontologists, or DNA for geneticists, they allow us to construct a veritable time machine and provide us with tantalizing glimpses of the earliest nature of our solar system. By investigating them, we can probe what our home system was like before life or even the planets existed. The origin and evolution of life on our planet is also intertwined with asteroids in a different way. It is believed that impacts on the primordial Earth may have delivered the basic components for life, with biology favoring attributes that could more easily survive the aftermath of such energetic events. In this fashion, asteroids may have banished many probable avenues for life to relative obscurity. Similarly, they may have also prevented our biosphere from becoming more complex until more recent eras. The full tale of asteroid impacts on the history of our world, and how human life managed to emerge from myriad possibilities, has yet to be fully told. The hazard posed by asteroid impacts to our civilization is low but singular. The design of efficient mitigation strategies strongly relies on asteroid detection by our ground- and spacebased surveys as well as knowledge of their physical properties. A more positive motivation for asteroid discovery is that the proximity of some asteroids to Earth may allow future astronauts to harvest their water and rare mineral resources for use in exploration. A key goal of asteroid science is therefore to learn how humans and robotic probes can interact with asteroids (and extract their materials) in an efficient way. We expect that these adventures may be commonplace in the future

  6. Complexes with Tunable Intramolecular Ferrocene to Ti(IV) Electronic Transitions: Models for Solid State Fe(II) to Ti(IV) Charge Transfer.

    PubMed

    Turlington, Michael D; Pienkos, Jared A; Carlton, Elizabeth S; Wroblewski, Karlee N; Myers, Alexis R; Trindle, Carl O; Altun, Zikri; Rack, Jeffrey J; Wagenknecht, Paul S

    2016-03-01

    Iron(II)-to-titanium(IV) metal-to-metal-charge transfer (MMCT) is important in the photosensitization of TiO2 by ferrocyanide, charge transfer in solid-state metal-oxide photocatalysts, and has been invoked to explain the blue color of sapphire, blue kyanite, and some lunar material. Herein, a series of complexes with alkynyl linkages between ferrocene (Fc) and Ti(IV) has been prepared and characterized by UV-vis spectroscopy and electrochemistry. Complexes with two ferrocene substituents include Cp2Ti(C2Fc)2, Cp*2Ti(C2Fc)2, and Cp2Ti(C4Fc)2. Complexes with a single ferrocene utilize a titanocene with a trimethylsilyl derivatized Cp ring, (TMS)Cp, and comprise the complexes (TMS)Cp2Ti(C2Fc)(C2R), where R = C6H5, p-C6H4CF3, and CF3. The complexes are compared to Cp2Ti(C2Ph)2, which lacks the second metal. Cyclic voltammetry for all complexes reveals a reversible Ti(IV/III) reduction wave and an Fe(II/III) oxidation that is irreversible for all complexes except (TMS)Cp2Ti(C2Fc)(C2CF3). All of the complexes with both Fc and Ti show an intense absorption (4000 M(-1)cm(-1) < ε < 8000 M(-1)cm(-1)) between 540 and 630 nm that is absent in complexes lacking a ferrocene donor. The energy of the absorption tracks with the difference between the Ti(IV/III) and Fe(III/II) reduction potentials, shifting to lower energy as the difference in potentials decreases. Reorganization energies, λ, have been determined using band shape analysis (2600 cm(-1) < λ < 5300 cm(-1)) and are in the range observed for other donor-acceptor complexes that have a ferrocene donor. Marcus-Hush-type analysis of the electrochemical and spectroscopic data are consistent with the assignment of the low-energy absorption as a MMCT band. TD-DFT analysis also supports this assignment. Solvatochromism is apparent for the MMCT band of all complexes, there being a bathochromic shift upon increasing polarizability of the solvent. The magnitude of the shift is dependent on both the electron density at Ti(IV

  7. An implementation-independent threat model for group communications

    NASA Astrophysics Data System (ADS)

    Hester, Jason; Yurcik, William; Campbell, Roy

    2006-04-01

    The importance of group communications and the need to efficiently and reliably support it across a network is an issue of growing importance for the next decade. New group communication services are emerging such as multimedia conferencing/groupware, distributed interactive simulations, sensor fusion systems, command and control centers, and network-centric military applications. While a succession of point-to-point unicast routes could provide group communications, this approach is inherently inefficient and unlikely to support the increased resource requirements of these new services. There is the lack of a comprehensive process to designing security into group communications schemes. Designing such protection for group communications is best done by utilizing proactive system engineering rather than reacting with ad hoc countermeasures to the latest attack du jour. Threat modeling is the foundation for secure system engineering processes because it organizes system threats and vulnerabilities into general classes so they can be addressed with known protection techniques. Although there has been prior work on threat modeling primarily for software applications, however, to our knowledge this is the first attempt at implementation-independent threat modeling for group communications. We discuss protection challenges unique to group communications and propose a process to create a threat model for group communication systems independent of underlying implementation based on classical security principles (Confidentiality, Integrity, Availability, Authentication, or CIAA). It is our hope that this work will lead to better designs for protection solutions against threats to group communication systems.

  8. Architecture Models and Data Flows in Local and Group Datawarehouses

    NASA Astrophysics Data System (ADS)

    Bogza, R. M.; Zaharie, Dorin; Avasilcai, Silvia; Bacali, Laura

    Architecture models and possible data flows for local and group datawarehouses are presented, together with some data processing models. The architecture models consists of several layers and the data flow between them. The choosen architecture of a datawarehouse depends on the data type and volumes from the source data, and inflences the analysis, data mining and reports done upon the data from DWH.

  9. Therapeutic Enactment: Integrating Individual and Group Counseling Models for Change

    ERIC Educational Resources Information Center

    Westwood, Marvin J.; Keats, Patrice A.; Wilensky, Patricia

    2003-01-01

    The purpose of this article is to introduce the reader to a group-based therapy model known as therapeutic enactment. A description of this multimodal change model is provided by outlining the relevant background information, key concepts related to specific change processes, and the differences in this model compared to earlier psychodrama…

  10. Source-Term and building-Wake Consequence Modeling for the Godiva IV Reactor at Los Alamos National Laboratory

    SciTech Connect

    Letellier, B.C.; McClure, P.; Restrepo, L.

    1999-06-13

    The objectives of this work were to evaluate the consequences of a postulated accident to onsite security personnel stationed near the facility during operations of the Godiva IV critical assembly and to identify controls needed to protect these personnel in case of an extreme criticality excursion equivalent to the design-basis accident (DBA). This paper presents the methodology and results of the source-term calculations, building ventilation rates, air concentrations, and consequence calculations that were performed using a multidisciplinary approach with several phenomenology models. Identification of controls needed to mitigate the consequences to near-field receptors is discussed.